CONSULTANT: NTPC Limited
OWNER : MEJA URJA NIGAM PRIVATE LIMITED
PROJECT :
MEJA THERMAL POWER PROJECT
STAGE – I (2 x 660 MW)
ASH HANDLING SYSTEM PACKAGE
R2
NTPC DOC. NO. 0360-162-PVM-W-284
TECPRO SYSTEMS LTD.
(ASHTECH DIVISION)
T
KOLKATA – PUNE
TITLE: CONTROL WRITE UP
TSL Doc No. 576-80-06
Rev. No.
REV.
NO.
DATE
ISSUE STATUS
0
23.10.2013
For Approval
1
20.05.2014
For Approval
----
2
23.09.2014
For Approval
----
REMARKS
2
PREPARED
BY
---ASHIM
Digitally
signed
Signature
Not
Verified
by Mohit
Jain
Date: 2014.10.13
SSIST
17:34:32
Reason: CAT I
Location:
ATANU
NTPCEOC
CHECKED
BY
SM
SRS
SB
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
1.
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
REFERENCE P&ID
Sl. No.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Title
Single Line Flow Diagram of Bottom
Ash Handling System.
Single Line Flow Diagram of Fly Ash
Vacuum Conveying System.
Single Line Flow Diagram of Fly Ash
Pressure Conveying System.
Single Line Flow Diagram of Ash
Water & Ash Slurry Disposal System.
Single Line Flow Diagram of HCSD
System.
P&ID of HCSD Pump
NTPC Drawing No.
0360-162-PVM-L-001-R3
TSL Drawing No.
576-01-01
0360-162-PVM-L-002-R3
576-01-02
0360-162-PVM-L-003-R2
576-01-03
0360-162-PVM-L-004-R2
576-01-04
0360-162-PVM-L-005-R3
576-01-05
0360-162-PVM-L-225-R1
576 - 40/751 - 02C
P&I Diagram & Control Write Up Of
Instrument Air Compressor
P&I Diagram & Control Write Up For
IAC Air Drier
P&I Diagram & Control Write Up Of
Transport Air Compressor
P&I Diagram & Control Write Up Of
Refrigerant Air Drier For Transport Air
Compressor
TECPRO SYSTEMS LTD
Page 1
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
2.
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
INTRODUCTION:The Ash Handling Plant consists of the following primary services/sub system:
• Unitized Bottom Ash System along with Bottom Ash Overflow and sludge disposal
system.
• Bottom ash slurry disposal system common for both the units.
• Unitized Fly ash Vacuum conveying system.
• Unitized Fly ash Pressure conveying system.
• Instrument air compressors, Instrument air dryers and Transport air compressors &
dryers.
• Ash water pumping system.
• Seal water pumping system.
• Silo unloading system.
• High concentration slurry disposal (HCSD) system.
• Misc. Drainage System.
3.
General Control and Operation concept:• The control & operation facility of the entire AHP system will be implemented in
DDCMIS based control system of NTPC except controls & operation of HCSD silo
unloading & HCSD system.
• Control & operation of HCSD silo unloading and HCSD system will be implemented in
PLC based control system supplied by M/s Tecpro. PLC panels for these will be located
in VFD panel room and OWS for operation will be placed in the AHP control room.
• One number local panel with push buttons/ selection switches and mimic lamp &
annunciation facia will be provided near bottom ash hopper area of each unit for
operation of BA ash evacuation system of each unit. Push buttons/ selection switches of
these panels will be hardwired to DDCMIS panel and 24V DC mimics/ annunciation
facia will be powered from DDCMIS output. So operation of Bottom ash evacuation
system will generally be done from its local panel (BALCP). However, it will also be
possible to operate bottom ash system from OWS/LVS (NTPC scope) located in AHP
control room.
TECPRO SYSTEMS LTD
Page 2
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
• The operation of fly ash evacuation system, ash water pumps, bottom ash slurry pumps,
IAC, IAD, TAC/TAD etc. will be from OWS/LVS (NTPC scope) located in AHP
control room.
• One number common local panel with push buttons/ selection switches and mimic lamp
& annunciation facia will be provided for fly ash silo. Further one no. silo unloading
panel with push button & lamps will be located near each Fly ash silo. Push buttons/
selection switches of these panels will be hardwired to DDCMIS panel and 24V DC
mimics/ annunciation facia will be powered from DDCMIS output. Operation of silo
unloading system will be from silo unloading panel of respective silo.
•
Some of the systems / equipment like TAC etc. will have their integral controls besides
overall operation from DDCMIS. Same has been detailed out in their respective section.
The TAC will be controlled through PLC i.e. all the logic will be developed in that PLC
only it will be communicated with DDCMIS for overall control.
• The operation of overall system can be taken up either for one unit or both the
depending upon the boiler operations.
units
The normal ash removal requirement from both the units is as below.
• Intermittent removal of bottom ash (twice in a shift of 8 hrs. four hourly basis) from one
unit at a time followed by the other unit. The total time for evacuating 4 hours
collection of bottom ash operation is 90 minutes including 10 minutes time for starting,
stopping, sequential changeover from one unit to second unit and water flushing of the
line.
• The Ash slurry pumps are to be operated for removal of Bottom ash slurry. There are
total three series of Ash slurry disposal pump and each series is connected with
individual sump. Two series of ash slurry pump shall be operated for removal of ash
slurry from Bottom ash of both the units. Other series is common standby.
• The Fly ash system is operated once in a shift to evacuate eight hours collection of fly
ash corresponding to maximum ash collection rates specified in technical specifications
in a period of six hours. However ash removal system shall be running on continuous
basis to ensure that there is no ash accumulation in fly ash hoppers. The ash removal
from various hoppers is carried out sequentially. There are total six streams of vacuum
TECPRO SYSTEMS LTD
Page 3
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
ash conveying system per unit and only one hopper is evacuated from each stream of
vacuum conveying at a time.. The fly ash is collected in complete dry form either in
Dry Ash Silo or in HCSD Silo. APH ash shall be evacuated along with ESP hoppers by
vacuum conveying system. The fly ash evacuation from both the units may take place
simultaneously from their respective unit wise vacuum Pumps.
• FA ash silo unloading system and HCSD silo unloading system & HCSD system are
common for both the units.
4.
OPERATION AND INTERLOCKS OF VARIOUS SYSTEM
The respective sequence of operation, control philosophy and different Interlocks for
various system / sub system and major equipments have been detailed in this part of the
control write up. Equipment wise detailed permissive and protection conditions are
listed in separate table at the end of document.
4.1. BOTTOM ASH EVACUATION SYSTEM :
(a) Bottom ash generated in boiler furnace of each unit is stored in a water impounded
hopper for respective units. This is cleaned twice in a shift of eight hours by means
of jet pumps. Normally Bottom ash removal of only one unit is carried out at a time.
(b) The Bottom ash cleaning system is mainly carried out from Bottom Ash Local
Control Panel (BALCP) located in the respective boiler area with proper
coordination with AHP control room. The main equipments covered under each unit
relate to Clinker Grinder, Bottom Ash Jet pumps, B.A. Overflow transfer pumps,
various water line valves, Bottom ash Feed Gates etc.
(c) Prior to starting of BA cleaning following are to be ensured by control room
operator.
• BALP water pumps in running condition feedback.
• Instrument Air pressure is normal.
• BA seal water pump running feedback.
• BA slurry Seal water pump running feedback.
• 1 working (2 Standby). of slurry disposal pumping stream in operation.
TECPRO SYSTEMS LTD
Page 4
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
(d) The Bottom ash hopper of each unit has three sections and each section is provided
with two (2) nos. Clinker Grinder, two (2) nos. Jet Pumps and two (2) nos. Feed
Gate housing. The bottom ash is cleaned and conveyed through six nos. of slurry
transport lines (Line#1 to Line#6) to ash slurry common trough. Out of six lines,
three lines (one from each section of BA Hopper) shall be in service and other three
are standby.
(e) Any one Feed Gate/Jet Pump from each section of B.A Hopper can be operated at a
time. This selection for each section of BA hopper is available in BALCP.
Based on the above selection any one jet pump water line valve (pneumatic
operated) of that section of B.A Hopper can be opened from Bottom Ash Local
Panel. Necessary interlocks have been provided to ensure that only one water line
valve of Jet pump out of the two connected with same section of bottom ash hopper
can be opened at a time.
(f) Once the Jet pump water line valve is opened, BAHP Pump shall be started by
operator.
(g) Respective Clinker Grinder seal water valve will open in auto with jet Pump water
valve opened feedback.
(h) There are 2 nos. (1W+1S) BA seal water pumps provided to cater to the seal water
requirements of BA overflow pumps and clinker grinders. These pumps are common
for 2 units and are located in Unit #1. Operator shall start BA seal water pump
before starting clinker grinder.
(i) Operator will set the individual clinker grinder jamming removal selection switch in
auto or in manual mode. If in auto mode and jamming is detected, the jamming
removal sequence will start in auto through DDCMIS. However, in manual mode, if
jamming is detected the clinker grinder will stop and operator has to take corrective
actions.
(j) After all the above mentioned valves are opened and respective water line pressure
(BAHP water pressure and seal water line pressure to Clinker Grinder) are above pre
set value, the Clinker Grinder can be started in forward direction by operator. Once
the Clinker Grinder forward operation is ensured, the Feed Gate can be opened from
the panel for ash removal operation.
TECPRO SYSTEMS LTD
Page 5
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
(k) In case water pressure falls below the required value either for Jet pump or for
Clinker Grinder seal water, the entire system will stop in the following sequence.
•
•
Close Feed Gate
Stop Clinker Grinder.
Under the normal mode of operation also the closing sequence is same as above.
Except water and slurry pumping devices, the bottom ash cleaning devices are
generally unit wise & independent. Water and slurry pumping devices are utilized as
common facilities for cleaning of bottom ash from all the units.
(l) There can be a jamming in the Grinder due to excess clinker or large size of clinker
or material other than bottom ash clinker. A zero speed switch is provided on each
clinker grinder to detect jamming. In such events if the Clinker Grinder is in auto
mode, the Clinker Grinder will automatically run in reverse direction. This reverse
direction operation can take place only if the pressure of seal water line is above the
desired level. The reverse rotation of the Clinker Grinder will be for about 20 sec
and immediately thereafter the grinder will stop and automatically start in forward
direction if the entire pre requisites permissive are available for forward running. In
case the grinder jamming is not removed even after three times of such
Forward/Reverse operation, the grinder will stop and Clinker Grinder Jammed
‘annunciation’ will be sounded both in main control room and local control panel. In
case of manual mode, operator will repeat the above said procedure for jamming
removal.
(m) The seal trough shall be continuously flushed through BALP water pump.
Sometime as per requirement the same shall be flushed through BAHP water line
also to clean the deposited ash. The seal trough should be drained out when the
Boiler is under shutdown/tripped and should be filled with fresh water. Continuous
Seal trough overflow should be ensured while the Boiler is under operation. During
Bottom ash evacuation in drawdown mode the emptiness of hopper can be checked
through Inspection window. The inspection window will be flushed by clean water
by opening of individual valve mounted with each inspection window as and when
required particularly during bottom ashing. During bottom ash evacuation, in
drawdown mode, jetting nozzles from one end of the hopper are to be opened one
after another for complete flushing of the hopper when hopper level is already down.
At a time only one set of nozzles can be operated. In level maintained mode jetting
TECPRO SYSTEMS LTD
Page 6
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
nozzles are to be operated one after another in last phase of evacuation before
closing of Feed Gate.
4.2
BOTTOM ASH MAKE-UP / COOLING WATER AND B.A OVERFLOW
SYSTEM.
(a) The operation of bottom ash system has continuous requirement of L.P make up/
cooling water system and intermittent requirement of ash removal system. For Bottom
ash hopper overflow, Bottom ash overflow Transfer pump is to be operated.
(b) The makeup / cooling water system and bottom ash overflow pump can be operated in
the following manner:
The make up /cooling water valve in the bottom ash L.P water line to bottom ash
hopper is generally kept open when the boiler is in operation. The cooling water flows
to bottom ash hopper to maintain the overflow of the hopper so that the inside water
temperature can be maintained below 600C. Overflow from the bottom ash hopper
carrying the heat is discharged into the B.A Overflow Sump. B.A Overflow Pump
discharges water to Settling Tank which is common for both units. Overflow from
settling tank flows to Surge tank by gravity and from Surge tank clean water is taken to
Ash water sump. In drawdown mode of bottom ash evacuation, there will be no
overflow from BA hopper to B.A overflow tank as the B.A hopper make up valve shall
remain closed during evacuation. At that time in low level of tank, make up valve from
BALP shall be opened automatically and the B.A Overflow water pump will be
continued to run with this make up arrangement.
After the bottom ash hopper is emptied the bottom ash hopper make up/ cooling water
valve is immediately opened to allow the water inside the hopper.
(c) The sequence of operation is as below.
There are two (2) nos. (1W+1S) Bottom Ash Overflow Water Pump provided per unit
to cater transferring of bottom ash overflow water to settling tank and Surge tank.
(d) To start Bottom Ash Overflow Water Pump, first BA overflow pump suction valve is to
be opened by operator. B.A overflow Seal water valve will open in auto with suction
valve open feedback.
TECPRO SYSTEMS LTD
Page 7
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
(e) For each B.A Overflow transfer pump, a motor operated scoop tube fluid coupling is
provided which is to be started by operator from AHP control room (OWS) before
starting B.A Overflow pump.
(f) The selected Bottom Ash Overflow Water Pump can now be started by operator if the
water level inside the overflow water tank is above preset level and other starting
permissive is available.
Initially the scoop position of fluid coupling shall be 0% at the time of starting the BA
Overflow pump and gradually can be increased locally up to 70% (approx) to achieve
the full load condition.
(g) There are two modes of operation of BA Overflow pumps, Auto mode and Manual
mode. In auto mode of operation, the B.A Overflow water pump shall be automatically
started at high level of overflow tank if the starting permissive is satisfied. The pump
shall be automatically stopped at low level of the tank. As BALP pump is continuously
running the makeup valve is always open in maintained level and will remain closed on
drawdown mode.
5.
SETTLING TANK, SURGE TANK AND SLUDGE PUMPING SYSTEM
(a) The settling tank, Surge tank and Sludge pumps are located near Ash water pump
house. The ash comes out from B.A Overflow water is settled in settling tank and
Surge tank .The sludge deposited in settling tank and Surge tank will be
continuously removed by sludge pump to ash slurry sump. At a time only two B.A
Overflow Transfer Pumps (one from each unit) have to run.
(b) There are two (2) nos. sludge pump (1W+1S) provided for cleaning of settled ash of
settling tank and Surge tank. Normally one Sludge pump will be operated
periodically to clean the deposited sludge from both settling and surge tank
irrespective of running of BA overflow transfer pump.
(c) Sludge pumps are provided with seal water from LP seal water pumps.
The sludge pump can be started by operator from AHP control room (OWS) after
availability of necessary permissive.
TECPRO SYSTEMS LTD
Page 8
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
5.
Description And Sequence of Operation of Fly Ash Evacuation System.
5.1
Basic Facility
a. Each unit is provided with dry fly ash removal system for ash collected in ESP hoppers
and air pre heaters hoppers.
b. In ESP of each unit, there are six passes (A, B, C, D, E & F). Each pass is equipped
with 16 hoppers. These hoppers are arranged in 8 fields with 2 hoppers in each field.
One number Material Handling valve (pneumatically operated) is provided below each
hopper.
Other than ESP hoppers, there are 4 nos. APH hoppers (2 nos. Primary APH hoppers
and 2 nos. Secondary APH hoppers). One number Material Handling valve
(pneumatically operated) is provided below each of these hoppers. Ash from APH
hoppers will be connected with ash lines of ESP passes A, B, E, F. Secondary APH
hopper-1 is connected to stream B, Secondary APH hopper-2 is connected to stream E,
Primary APH hopper-1 is connected to stream A, Primary APH hopper-2 is connected
to stream F.
c. Fly ash evacuation system is divided in 2 parts.
• First part is fly ash vacuum conveying system which is envisaged for conveying
ash from ESP hoppers / APH hoppers to buffer hoppers using vacuum pumps.
• Second part is fly ash pressure transportation system which is envisaged to
transport the ash from buffer hoppers to either fly ash silos or HCSD silos using
transport air.
d. The fly ash system is operated once in a shift to evacuate eight (8) hours collection
of fly ash within six hours. However fly ash evacuation shall be continuous to ensure
that there is no ash accumulation inside the ESP hoppers. The ash removal from various
ESP hoppers is carried out sequentially. Only one hopper is evacuated from each stream
of vacuum conveying at a time.
In providing the above fly ash removal facility from all the ESP & APH Hoppers of one
unit, six (6) nos. independent vacuum conveying streams have been provided i.e. one
for each ESP pass. In auto mode, the de-ashing sequence of ESP hoppers of one stream
will be from first hopper of field-1 to field-8 and then second hopper of field-1 to field8 for each ESP pass.
TECPRO SYSTEMS LTD
Page 9
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
Each ash evacuation stream is connected with 2 (1W+1S) Buffer hoppers. Total 12 nos.
Buffer hoppers are provided for 6 nos. vacuum conveying streams. Each buffer hopper
is provided with dedicated vacuum pump, total twelve (12) nos. (6W+6S) Mechanical
Exhausters/ Vacuum Pump. The rated parameter of each vacuum pump is 3385 cu.m/hr.
@ 14” Hg vacuum.
During vacuum conveying the air is separated from ash while passing through bag
filters and then clean air discharges through vacuum pump.
Each buffer hopper is provided with two (2) nos. of air lock vessel. The fly ash from
buffer hopper is discharged into air lock vessels. Four (4) nos. pressure conveying
streams have been provided for each unit, out of which three lines are working and one
is standby.
There are two buffer hopper fluidizing blowers per unit along with heater with three
banks each. One fluidizing blower caters to the requirement of a unit.
At a time, dry ash of all six vacuum streams of a unit can be conveyed to silo.
e. The capacity of the each stream of pressure conveying system is equivalent to the total
fly ash removal capacity of two streams of vacuum conveying system of one unit. There
are total four pressure conveying streams. Each pressure conveying line is connected
with all the six vacuum conveying streams through air lock vessels. However, any two
air lock vessels can be operated through one pressure conveying stream at a time.
Therefore, any three pressure conveying streams can be operated at a time depending
upon the availability of Buffer hoppers and Air Lock Vessels for conveying total
generated ash either to dry ash silo or to HCSD silo.
f. All the four pressure conveying lines of each unit are connected to four Fly ash silo and
three HCSD Silo by providing suitable valve arrangement. Flexibility of operation will
be in built in control system to convey the fly ash to either FA Silo or HCSD Silo.
5.2
Control philosophy & Sequence of operation for each Vacuum
Evacuation stream:
The operation of fly ash is initiated from DDCMIS/OWS/LVS of AHP Control Room
in the following sequence.
TECPRO SYSTEMS LTD
Page 10
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
• First one of the two Buffer hoppers for each stream of vacuum conveying is to be
selected from HMI if the ash level in that buffer hopper is not high.
• The buffer hopper isolation valves, vacuum pump suction and vacuum pump seal water
valve will open in auto based on above selection.
• Bag filter purging of selected buffer hopper will be started by operator from OWS/Pulse
jet timer panel.
• Vacuum pump of the selected buffer hopper will be started by operator.
• The buffer hopper fluidizing blower is started by the operator. When the blower starts,
the fluidizing blower heater comes into service in auto.
• Once, the fluidizing blower and heater are in service, the fluidizing valves of selected
Buffer hoppers are opened in auto.
• The operator has to select the mode of operation (Auto/Manual) for each ESP streams
from HMI.
• Under auto mode, facility is provided to select any ESP hopper(s) for vacuum
evacuation and the cleaning of various hoppers is taken up in a predetermined sequence
(selected hoppers from field-1 to field-8).
• Under manual mode any hopper can be selected through the selection switches provided
in HMI. However, only one hopper can be selected manually for ash removal at a time.
• The operator shall start the vacuum conveying system through the Vacuum System
Start/ Stop Button provided in HMI for each ESP stream. On actuation of system starts,
the branch header valve of the first branch opens in auto. The corresponding Vacuum
Breaker will close and vacuum will start developing.
• For the auto sequence, Sequence Start/ Stop buttons are provided on HMI. Operator
shall press Sequence Start button for initiation of auto sequence when required
permissive are available.
• ESP Branch isolation valve of farthest distance row of selected stream shall open in auto
if vacuum Breaker closed Feed -back is available. The first hopper of corresponding
TECPRO SYSTEMS LTD
Page 11
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
header shall be opened automatically if the header vacuum is ≤ VS4. During each
conveying operation whenever ash is discharged into the vacuum conveying stream, the
vacuum increases and when it reached ≥ VS3 value, the ash intake valve will close.
Shortly after the ash is conveyed, the vacuum will automatically come down and when it
reaches value ≤ VS4, the ash intake valve will again open and ash feeding into the
system will again start. Utilizing this automatic feed control system, the ash is removed
from individual hopper and the same is valid irrespective of auto or manual mode. If the
fly ash line is excessively loaded and vacuum level exceeds VS5, Vacuum Breaker will
automatically open. In auto mode of operation, the Vacuum breaker will automatically
close when vacuum comes down to value less than VS6. The ash intake valve of running
hopper will again open after 20 sec delay from closing of Vacuum Breaker and when the
vacuum value is less than VS4.
• When the hopper is empty, ash feed into the system will be very less in quantity
resulting the line vacuum coming down to low level i.e. vacuum value less than VS2.
After a time lag (approx. 10 sec), sequence will shift to next selected hopper and ash
intake valve of that hopper will open and the same sequence will be repeated as
described above.
• VS1, VS2, VS3, VS4,VS5 are the operator configurable set points of Line Vacuum and
total operation of vacuum conveying is being achieved through these set points.
• Many abnormal conditions can occur in the hopper during de-ashing causing hopper
plugging. Under such conditions, the vacuum value will remain low(≤ 225) for a long
duration. This condition is annunciated as ‘Hopper Plugged’. Operator has to take
corrective measures. In this case, during auto cleaning mode of FA Vacuum system
operation, the sequence will shift to the next selected hopper in auto.
• Once the particular branch is cleaned the operation will shift to the next branch in auto.
It is to be noted that the entire auto operation will take place in sequential manner
already set in the logic.
• The next cycle will start automatically after completion of one sequence unless
interrupted / stop from the HMI.
• If the Dust sensor is activated because of excessive ash ingress in vacuum line, an
annunciation shall be generated in control room for necessary action for attending the
bag filters.
TECPRO SYSTEMS LTD
Page 12
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
• The vacuum extraction system shall be operated as per the following vacuum settings.
These settings are tentative and shall be set at site as per actual arrangement.
(a) No load vacuum 100 mm of Hg (VS1).
(b) Hopper empty 80 mm of Hg (VS2).
(c) Hopper valve intermittent close 280 mm of Hg (VS3)
(d) Hopper valve re-open 260 mm of Hg (VS4)
(e) Vacuum breaker open 350 mm of Hg (VS5)
(f) Vacuum breaker close 200 mm of Hg. (VS6)
• If any high level alarm is activated for ESP hopper, that particular hopper is to be
evacuated in manual mode on top priority.
• If Sequence Stop is pressed, the ash intake valve of current hopper will close and
sequence will be held at that step. Sequence will again start from the same hopper when
Sequence start is pressed again.
• On system stop command, the vacuum breaker shall open and evacuation processes shall
stop.
5.3 Control philosophy & Sequence of operation for Pressure conveying
system:
The operation of pressure conveying of fly ash is initiated from DDCMIS/OWS/LVS of
AHP Control Room in the following sequence:
• First the selection of pressure conveying line is done by operator by selection window
available on HMI. There are 4 pressure conveying lines X, Y, Z and W. Out of these, 3
lines are selected for pressure conveying and one is standby.
• On each pressure conveying line, two ALVs are selected as first vessel and second
vessel. This selection is done by operator considering the selection of Buffer hoppers
(already selected in vacuum evacuation system) and pressure conveying lines as
selected above. Out of 4 ALVs of a ESP pass, at a time only one can be selected.
• Three no. Transport air compressors (3W+2S) are provided to cater the requirement of
fluidizing and transport air for three pressure conveying lines of each unit. The TAC
TECPRO SYSTEMS LTD
Page 13
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
discharge valves and line isolation valves are opened by operator through HMI to
connect the working TAC to each of the pressure conveying line.
• The fluidizing line valve and conveying line valves of the selected pressure conveying
lines are then opened by operator through HMI.
• The ash can be transported to Fly ash Silo or HCSD silo. This selection is done by
operator for all the pressure conveying lines through a common selection in HMI.
Based on this selection and selection of three pressure conveying lines, the Fly ash Silo
and HCSD Silo isolation valves open in auto.
• Further, the operator has to open the Silo ash inlet valves for each of the pressure
conveying line through HMI. It is possible to select same or different silo for each
pressure conveying line.
• Then, the operator has to start through HMI the vent fan and vent filter purging system
of the silo in use.
• Then the TACs are started after checking the requisite permissive. It is recommended
that the selected conveying lines are purged with transport air for approximately 100
sec. before the ALVs operation is started. All the ALV valves (i.e. fluidizing air inlet
valve, discharge valve, vent valve and ash inlet valve) shall be closed during line
purging.
• Once the path from transport air compressors to FA/ HCSD Silo is through and the
required permissive are available, ALVs operation is carried out. There are two modes
of ALVs operation: Flushing mode and Normal mode.
• In flushing mode of ALVs, vessel purging is to be done, both the fluidizing air and
ALV discharge valve of selected vessels are opened. Conveying air enters into the
vessels through Fluidizing air valve and escapes to conveying line through discharge
valve simultaneously for both selected ALVs for approx 90 secs. However, the ALVs
inlet and vent valves will remain close.
TECPRO SYSTEMS LTD
Page 14
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
• It is recommended to carry out flushing of ALVs before running in normal mode where
the ash loading and unloading takes place in cyclic manner.
• In normal mode, one set of Pressure conveying System Start/Stop P.B. is provided for
each Pressure conveying line in HMI. The operation of these ALVs is timer based and
there will be two timers (Timer-1 for first vessel and Timer-2 for second vessel) for
each pressure conveying line. However, both the timers start together.
• Each ALV timer cycle comprises of filling delay time, filling time, conveying delay
time, conveying time which are all user defined and will be given by operator. When
the system start button is pressed, both the timers initiate.
• First Timer: After filling delay time, filling cycle of the first vessel starts & it’s vent
valve opens and after 10 seconds, the ash intake valve opens and will remain open for
filling time duration. After this conveying delay timer will start. At the end of this
timer, conveying timer is initiated & the fluidizing air valve opens. After 10 seconds,
the ALV discharge valve opens and ash is conveyed to silo.
• Second Timer: After conveying delay time, conveying cycle of the second vessel starts
& it’s fluidizing valve opens and after 10 seconds, the ash discharge valve opens and
will remain open for conveying time duration. After this filling delay timer will start. At
the end of this timer, filling timer is initiated & the vent valve opens. After 10 seconds,
the ALV ash intake valve opens and ash is loaded into ALV.
• The above cycle of both timers will run continuously till manually interrupted.
• This cycle of loading of one ALV and conveying of other ALV for a pressure
conveying line continues for the total period of operation of pressure conveying system.
In case, the line pressure value shoots up higher than the value defined for ash
conveying , the ALV discharge valves and fluidizing valves will be closed till the line
pressure comes down below the set value and the cycle will start from there itself
(timers will be paused).
TECPRO SYSTEMS LTD
Page 15
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
• It is to be ensured that the conveying of the both vessels should not take place
simultaneously.
• After completion of the whole process the FA pressure system stop button is pressed
and the valves of the ALV will be closed after the completion of the ongoing cycle.
• It is recommended that after completion of the ALV cycle the vessels are purged with
air i.e. flushing mode should be started.
• Silo purging system, vent fan and all the valves of silos are closed from HMI.
TECPRO SYSTEMS LTD
Page 16
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
5.4 AIR FLOW CONTROL FACILITY
The total conveying air is splited into two segments. While one part of air is directly
provided to the conveying line and the other part of air is allowed to enter the Air Lock
Vessel from the bottom. Referring to the construction detail of Air Lock Vessel, it can
be observed that the air induced into the vessel fluidizes the ash and conveys the same
through outlet of the vessel into the transport line. As such, the two airs are called
‘Fluidizing Air’ and ‘Transport Air’ respectively for regular reference.
There is a control requirement between the preparation of Fluidizing Air and Transport
Air. Accordingly, one orifice is provided in fluidizing line and a control valve is
provided in transport air line to control the respective air flow of a particular stream.
There are two Pressure Transmitters provided at outlet of control valve in conveying
line which indicate the back pressure of ash conveying line. It is to be noted that the
back pressure of conveying air line is dependent on the actual flow condition of ash in
the transport air line. If the ash conveying is on the higher side, the back pressure will
be high and low back pressure indicates the reduced ash flow in the system. DCS
control system monitors opening/closing of conveying line control valves as per the
feedback received from PTs. The set point for the high pressure of the conveying line is
approx 2.5kg/cm2; however this set point may vary at the time of commissioning of the
system.
The DCS provides a single command of pre-set opening of the control valve in the
conveying line as explained above. During normal ash conveying, a portion of
fluidizing air is allowed in the air lock vessel. The same air is discharged through the
outlet pipeline of air lock vessel taking along the ash from air lock vessel. The
discharge of Air lock vessel is connected to the main conveying line; accordingly the
vessel is emptied in every cycle. It is to be noted that the back pressure will increase, if
the ash discharge from the air lock vessel is considerably high. Under such situation
DCS will signal to increase the opening of conveying line control valve so that more air
will be passed and system will balance at an optimum level. On the other hand back
pressure will drop in case there is less ash discharge from the air lock vessel. Under
such situation the control valve opening is reduced up to the lower limit. This will result
in higher rate of ash discharge from ALV. Correspondingly, conveying line back
pressure will increase and the DCS signal will reverse. With this adjustment the ash
conveying from air lock vessels will be carried out pneumatically in an optimized
condition and to achieve desired ash flow capacity.
TECPRO SYSTEMS LTD
Page 17
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
6.
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
ASH WATER SYSTEM
This system consists of Ash water sump, BA HP pumps, BA LP pumps, FA HP pumps,
Flushing water pump, Eco Water pumps, Seal water pumps etc. Total control and
operation of these are envisaged from DDCMIS based OWS/LVS of NTPC located in
AHP control room except FA HP pump which will be operated from OWS of HCSD
PLC. Equipment wise detailed permissive and protection conditions are listed in
separate table at the end of document.
6.1
SEAL WATER PUMPS
(a) B.A SLURRY SEAL WATER PUMPS
There are two nos. (1W+1S) Seal water pump for catering to the seal water
requirements of 1st and 2nd stage of ash slurry pumps, drain pumps. The rated
parameters of Seal water pumps are 29cu.m/hr @ 108 MWC.
Out of the two B.A Slurry Seal water pumps, one is under standby mode. The
working/standby mode is selected from HMI. The pump which is selected in standby
mode automatically starts when the operating pump trips and the starting permissive are
available.
(b) B.A SEAL WATER PUMPS
Two nos.(1W+1S) Seal water pumps are provided to cater seal water requirement of
Clinker Grinders and B.A Overflow Pumps. The rated parameters of Seal water pumps
are 35 cu.m/hr @ 47 MWC.
Out of the two B.A Seal water pumps, one is under standby mode. The working/standby
mode is selected from HMI. The pump which is selected in standby mode automatically
starts when the operating pump trips and the starting permissive are available.
TECPRO SYSTEMS LTD
Page 18
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
Before starting of any pump, the respective suction and discharge valves (manual) of
both the seal water pumps are to be kept opened.
6.2
BALP WATER PUMPS
There are three (3) nos. (2W+1S) BALP pumps provided for catering the cooling water
and make-up requirement of B.A Hopper under various mode of operation for both the
units. The rated parameter of BALP pumps are 810 cu.m/hr. @ 23 MWC.
It may be noted that BALP water pumps are operated with discharge valve (manual) in
fully open condition. One (1) no. pump caters to the requirement of one unit. The pump
is started from HMI of DDCMIS.
6.3
BAHP WATER PUMPS
There are two (2) nos. (1W+1S) BAHP water pumps provided to cater the requirement
of Bottom ash Jet pumps, Flushing & Jetting, for both the units. The rated parameters of
BAHP water pumps are 650 cu.m/hr. @ 118 MWC.
The BAHP water pump is started from HMI of DDCMIS when the respective discharge
valve (manual) is open and at least one water line valve and respective Jet pump
discharge valve is open. One (1) no. pump caters to the requirement of one unit at a
time. The BAHP water pumps are operated only when the Jet pumps of B.A system are
in operation. As such, BAHP water pump operation is intermittent. These pumps can
also be started from BALCP.
6.4
FLY ASH HP WATER PUMPS
There are three (3) nos. (2W+1S) FAHP water pumps provided to cater the water
requirements of Paddle Feeder and Mixing tank of HCSD system. One pump caters to
the requirement of two working streams HCSD system. The rated parameter of FAHP
water pumps are 250 cu.m/hr. @ 36 MWC.
The FAHP water pump is started when the respective discharge valve (manual) is open
and at least one water line valve of downstream is open. The FAHP water pumps
operate only when the HCSD system shall be operated.
6.5
FLUSHING WATER PUMP
TECPRO SYSTEMS LTD
Page 19
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
There is one Flushing water pump provided to cater water requirement for flushing of
ash slurry disposal pump and disposal line before stopping the slurry pumps. The rated
parameter of Flushing water pump is 1375 cu.m/hr. @ 15 MWC. Following sequence
of operation to be followed for flushing water system (FLUSHING MODE OF ASH
SLURRY SERIES):
1.
2.
3.
4.
6.6
Select flushing mode from HMI.
Close Suction valve of Ash Slurry pump series.
Open manual valve of flushing line at slurry pump suction.
Start ash slurry pump series as per logic provided for ash slurry disposal pump
bypassing suction valve and sump level logic.
ECO ASH WATER PUMP
There are two(1W+1S) Eco ash water pump provided to cater water requirement for
agitation / jetting of ash slurry sump, Sludge pump sump and HCSD Silo area washing.
The rated parameter of Eco ash water pump is 80 cu.m/hr. @ 75 MWC.
6.7 ASH WATER SUMP MAKE UP
There are three nos. make up water lines for ash water sump. One is from Raw Water
pump discharge, second is from Cooling Tower Blow down and third is from Recirculated water from ash dyke. B.A Overflow water also returns to ash water sump
through Surge tank after settlement of ash in settling and surge tanks. In case of fast
filling when the sump is completely empty, make up water is taken from Raw water
pump discharge. In normal operating condition make up water is taken from Cooling
tower Blow down (i.e. when sump level is low). The valve will be immediately closed
as soon as the high level of sump is sensed.
7.
ASH SLURRY PUMPING SYSTEM
There are three series of ash slurry pumps provided for ash slurry pumping system each
connected to one ash sump compartment. Each series has two pumps. The rated
parameter of ash slurry pump is 1195 CUM/Hr. @ 47.7 MWC. Normally one series
will be in operation for both the units while one is working standby and other is
maintenance standby. Bottom ash is collected in any sump by selecting the ash slurry
TECPRO SYSTEMS LTD
Page 20
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
common trough by opening or closing of plug gates. The operation of all the series is
similar.
The sequences of operation and control philosophy are as below:
• The entire operation of one series can be initiated through one set of group start/group
stop push button provided in HMI. Or else individual equipment in the series can be
started and stopped through HMI.
• The first stage of slurry pump is provided with fluid coupling having variable speed
drive arrangement. It is to be noted that the First stage pump for first stage series pump
is started/ stopped by operator from HMI of DDCMIS before/after the slurry series
operation.
• Under group auto operation, the sequence of starting of all the equipment in the series
are as below:
• The suction valve will open first.
• The seal water line valve to both the pumps in a series shall open.
• The first stage pump will start on availability of the required permissive.
• The discharge valve shall open after some preset time (5 sec.) after starting of first stage
pump.
• After starting of the first pump there shall be a preset delay after which the 2nd stage
pump will be started. It is to be noted that normally the time delay will be provided 15
sec in between starting of two pumps. While the same may slightly vary during actual
operation.
The above time delays are tentative and will be finalized at site during commissioning.
The above sequence of operation holds good for manual operation of each of the drive
by the operator. The interlocks, starting and running permissive for the ash slurry series
operation are covered at the end of the document.
TECPRO SYSTEMS LTD
Page 21
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
• For stopping the slurry series under group auto operation, when group stop button is
pressed from HMI, both the pumps in a series will stop, then the seal water valve will
close and finally the discharge valve as well as suction valve will close simultaneously.
• It is recommended that Slurry series should be run in flushing mode after each normal
mode operation. The flushing mode of ash slurry series is described along flushing
pump details covered above.
8.
DRAINAGE SYSTEM
8.1
DRAIN PUMP FOR ASH SLURRY PUMP HOUSE AREA
Two nos. drain sump pump (1W + 1S) has been provide near ash slurry pump house for
dewatering of collected water from ash slurry pump house. This drain pump will
discharge the collected water to ash slurry sump. The drain pump is to be operated from
HMI.
8.2
DRAIN PUMP FOR FA SILO AREA
Two nos. drain sump pump (1W + 1S) has been provide near F.A silo area for
dewatering of collected ash water of silo area. This drain pump will discharge the
collected water to ash slurry sump. The drain pump is to be operated from DCS HMI or
from Silo control panel.
8.3
DRAIN PUMP FOR HCSD SILO AREA
Two nos. drain sump pump (1W + 1S) has been provide near F.A silo area for
dewatering of collected ash water of silo area. This drain pump will discharge the
collected water to ash slurry sump. The drain pump is to be operated from DCS HMI or
from Silo control panel.
All the drain pumps can run in Auto/ Manual mode. In auto mode, the drain pumps will start
based on high level and stop on low level of respective drain sumps. The starting and running
permissive of drain pumps are covered at the end of the document.
TECPRO SYSTEMS LTD
Page 22
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
9.
FLUIDIZING AIR SYSTEM
9.1
BUFFER HOPPER FLUIDIZING BLOWER
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
Two nos.(1W + 1S) air blowers are provided for catering the fluidizing air requirements
of buffer hoppers of each unit. The rated parameter of Buffer hopper fluidizing air
blower is 400 cu.m/hr. @ 4000 MMWG.
The basic control philosophy and sequence of operation is as below:
The above blowers are controlled through DDCMIS and are operated from HMI of
DDCMIS. One selection option is provided in HMI for selecting the working /standby
of fluidizing blower.
The air heater corresponding to fluidizing air blower comes into operation in auto. It
may be noted that the air heater is running only when respective air blower is in
operation.
Each air heater comprises of 3 nos. heaters banks/ elements. The cut in/ cut out of these
heater elements is controlled through discharge temperature automatically.
9.2
F.A SILO FLUIDIZING BLOWERS
Five nos. (4W + 1S) air blowers are provided for catering the fluidizing air
requirements of four nos. silo. The rated parameter of silo fluidizing air blower is 600
cu.m/hr. @ 7000 MMWG.
The basic control philosophy and sequence of operation is as below:
The above blowers are controlled through DDCMIS and are operated from silo utility
control desk (SCP) or from HMI of DDCMIS.
The air heater corresponding to fluidizing air blower comes into operation in auto. It
may be noted that the air heater is running only when respective air blower is in
operation.
Each air heater comprises of 3 nos. heaters banks/ elements. The cut in/ cut out of these
heater elements is controlled through discharge temperature automatically.
TECPRO SYSTEMS LTD
Page 23
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
9.3
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
HCSD SILO FLUIDIZING BLOWER
Three nos. (2W + 1S) air blowers are provided for catering the fluidizing air
requirements of three nos. HCSD silos. The rated parameter of HCSD silo fluidizing air
blower is 400 cu.m/hr. @ 7000 MMWG.
The basic control philosophy and sequence of operation is as below:
The above blowers are controlled through PLC and are operated from HMI of PLC.
The air heater corresponding to fluidizing air blower comes into operation in auto. It
may be noted that the air heater is running only when respective air blower is in
operation.
Each air heater comprises of 3 nos. heaters banks/ elements. The cut in/ cut out of these
heater elements is controlled through discharge temperature automatically.
10.
SILO UNLOADING SYSTEM
10.1 ASH CONDITIONING WATER PUMP
There are three (3) nos. (2W+1S) Dust conditioning water pumps provided to cater the
requirements of conditioning water to Dust conditioner for unloading of moist ash to
open truck from silo. The rated parameters of A.C water pump are 48 cu.m/hr. @ 54
MWC.
These pumps are controlled through DDCMIS and can be operated through the Start/
Stop push buttons provided in control panel located in Silo utility building (SCP) for
each of the ash conditioning pumps or from the HMI of DDCMIS. The permissive and
interlocks for the operation of these pumps are covered at the end of the document.
10.2 Dry Ash Unloading To Closed Tanker through Telescopic Spout
The control of this system is through DDCMIS. However, the operation of the
equipments is carried out through push buttons/ selector switches provided in Silo
Unloading panel(s) located near each of the Silo.
The dry ash unloading system and sequence of operation is as described below:
TECPRO SYSTEMS LTD
Page 24
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
One no. dry ash unloading spout is provided in each silo for dry ash unloading to close
tanker. There are two nos. limit switches provided for full up and full down position of
dry ash unloading spout. There are two nos. push buttons provided in silo unloading
panel for inching operation of dry ash unloading spout. If lower run is required then
press lower push button. Lower run lamp glows till the lower run is completed, lamp
goes off. If higher run is required then press the raise push button. Raise lamp glows till
the higher run is completed. Then lamp goes off. If intermediate stop is required, then
release the push button.
One no. vent filter is provided for each dry ash unloading spout for unloading dry ash to
close tanker. The fan is started from silo unloading panel through start/ stop push
button only when the dry ash-unloading spout full down limit switch is actuated.
Once the dry ash unloading spout full down limit switch is actuated and the fan is
operated, then the rotary feeder is started from the silo unloading panel through the
respective start/stop push button.
When the fan and rotary feeder run feedback is available, then the remote operated
knife gate valve is opened through the open/close selection switch of KGV located in
silo unloading panel. KGV on the upstream of rotary feeder is automatically closed if
tanker full signal has come or to rotate the selection switch in close position.
If the level switch of the telescopic spout is sensed high, the ash discharge valve (KGV)
will be closed.
Stop Sequence
The stopping sequence of dry ash unloading through dry ash unloading spout is as
below.
• First, the KGV is closed from selection switch.
• Then the rotary feeder is stopped through push button.
• Then the scavenger fan is stopped.
• Then press raise push button of dry ash unloading spout.
10.3
Dry Ash Unloading To Open Truck through Ash Conditioner
The control of this system is through DDCMIS. However, the operation of the
equipments is carried out through push buttons/ selector switches provided in Silo
Unloading panel(s) located near each of the Silo.
TECPRO SYSTEMS LTD
Page 25
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
The wet ash unloading system and sequence of operation is as described below:
One no. ash conditioner is provided in each silo for moist ash unloading to open truck.
For moist ash unloading to open truck through the dust conditioner, first open the dust
conditioning water line valve from open/close selection switch located in silo unloading
panel. Then the dust conditioner is started from silo unloading panel through the
respective start/stop push button on availability of the required permissive.
One no. rotary un loader is provided in the upstream of each dust conditioner. Once the
dust conditioning water line valve is open and dust conditioner run feedback is
available, then the rotary feeder is started from the silo-unloading panel through the
respective start/stop push button.
When the dust conditioner and rotary feeder run feedback is present, then the remote
operated knife gate valve is opened through the open/close selection switch of KGV
located in silo unloading panel.
One no. Rotary Feeder with VFD control is provided in the upstream of each wet ash
unloading. There are two modes of operation of VFD- Auto and Manual. The mode
selection is done by operator from the VFD panel. In auto mode, the speed variation of
VFD is done in auto without operator intervention. However, in manual mode, facility
is provided to vary the speed of VFD manually through potentiometer.
11.
Stop Sequence
The stopping sequence of dry ash unloading through dust conditioner is as below.
• First close the remote operated KGV from selection switch.
• Then press the rotary feeder stop push button.
• Then close the water line valve.
• Lastly, stop the dust conditioner.
INSTRUMENT AIR COMPRESSOR
There are two (2) nos. (1W+1S) Screw type Instrument air compressor provided for
catering the requirement of instrument air of each unit. Instrument air compressor is to
be started before starting the ash evacuation through any system. The rated capacity of
IAC is 942 cu.m/hr. @ 80 MWC. The compressor is provided with loading unloading
facility to control the net total discharge through the compressor depending upon the
system requirement.
The overall operation of I.A.C. (start/ stop) is initiated from HMI of DDCMIS.
However, the integral controls, permissive and interlocks, load & unload operation of
TECPRO SYSTEMS LTD
Page 26
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
the instrument air compressor shall be as given by the OEM recommendation. These
details are covered in the OEM drawings nos. 0360-162-PVM-L-222 R0.
There are two nos. (1w+1s) Heater blower re-activated type air Drier provided for two
(1w+1s) instrument air compressors. The control and operation of instrument air
compressor drier is carried out through DDCMIS. The details of interlocks and
permissive are covered in the OEM drawings nos. 0360-162-PVM-L-224 R4
12.
TRANSPORT AIR COMPRESSOR
There are Five (5) nos. (3W + 2S) transport air compressor provided for catering the
conveying air requirement for transportation of dry fly ash from buffer hopper to silo
for each unit. The T.A.C is to be started before the dry ash evacuation through pressure
conveying system. The rated parameter of T.A.C. are 4500 cu.m/hr. @ 4 Kg/cm2. There
is one air receiver provided for each compressor.
The overall operation of T.A.C. (start/ stop) is initiated from HMI of DDCMIS.
However, the integral controls, permissive and interlocks, load & unload operation of
the instrument air compressor shall be as given by the OEM recommendation. These
details are covered in the OEM drawings nos. 0360-162-PVM-L-223 R1
There are five nos. (3w+2s) Refrigerant type air drier provided for 5 (3w +2s) transport
air compressors per unit. The control and operation of transport air compressor drier is
carried out through integral controller details of which are covered in the OEM
documents no. 0360-162-PVM-L-221 R1
13
HIGH CONCENTRATION SLURRY DISPOSAL SYSTEM
13.1
INTRODUCTION
Two outlet of each HCSD Silo is provided with independent High concentration slurry
disposal system. Each HCSD stream is having minimum ash disposal capacity 132 TPH
(Dry ash basis). The rated parameter of HCSD Pump is 154 cu. m/hr. @ 400 MWC.
The HCSD System shall take fly ash input from HCSD Silos and dispose it
continuously as high concentrated slurry to ash disposal area with 55-60 % ash
concentration. Water is added in mixing tank with moist ash in a controlled manner
through continuous automatic “Instrument Based” monitoring system to ensure that the
TECPRO SYSTEMS LTD
Page 27
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
basic slurry parameters (concentration) remain constant during the transportation of
slurry through the pipe line.
The pump speed shall be varied through VFD drive over the range of 10% to 100% of
maximum flow rate. Necessary remote and manual speed control provision is there.
There are six nos. of dedicated transformer to feed the power supply to VFD and after
VFD to HCSD motor for six nos. HCSD pumps.
The following aspects govern the basic arrangement of high concentration slurry
system.
a)
b)
c)
d)
Controlled Ash Feed.
Controlled water supply to maintain proper slurry density.
HCSD Pump.
Disposal Pipe line.
There are many control features, which have to work for guaranteed monitoring of
proper slurry density in a continuous manner so that the slurry pump can operate
uninterruptedly.
13.2
•
MAJOR EQUIPMENTS FOR HCSD SYSTEM
ROTARY FEEDER WITH VFD
One (1) no. Rotary Feeder is provided in upstream of Paddle Feeder and take fly ash
input from HCSD silo. It is to be noted that the Rotary Feeder have variable speed
control and have ash disposal capacity of 132 TPH. The speed of Rotary Feeder is
automatically adjusted as per the reading of Mass Flow meter to maintain required ash
flow for slurry consistency (55% - 60%).For variation of Rotary Feeder speed a VVVF
drive is provided. Mass flow meter is continuously monitor the feeding rate of fly ash
from Rotary Feeder to Mixer tank through Paddle Feeder and thus control of ash
feeding rate into the system is achieved.
•
PADDLE FEEDER
This is a twin Paddle mixture unloader having capacity 132 TPH. This is provided in
upstream of Slurry mixing tank where dry fly ash is been moist and discharge to ART
(Agitated Retention Tank).
TECPRO SYSTEMS LTD
Page 28
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
•
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
AGITATED RETENTION TANK (ART)
The ART is a rubber lined cylindrical tank with vertical spindle, twin blade, dual
impeller type high torque agitator. The output of Paddle Feeder fed into ART where
required slurry concentration and rheology is maintained and monitored. The ART is
provided with Level Transmitter for continuous level control measurement, Nucleonic
and Non-nucleonic type Density meter for density measurement. The ART is provided
with proper flushing and drain connection.
The mixing tank (ART) will have five level control.
a)
b)
c)
d)
e)
High High Level (90 %).
High Level (80%)
Operating level (70%).
Low level (10%).
Low low level (0%).
Zero level (0%) is set at the start of the lower part of tank. The 90% level is the
maximum slurry level allowable in the tank.
HCSD PUMP
There are two sets of HCSD Pump each having ash disposal capacity of 132 TPH (Dry
ash basis) with motor and VFD. Capacity of each HCSD Pump is 143.5 cu.m/hr @ 40
bar. Two HCSD Pumps are connected with two nos. slurry disposal line with necessary
no interconnection and instrumentation.
The starting permissive of HCSD Pump from HCSD PLC is as follows:
• HCSD Pump not failed.
• HCSD Pump ready to run (Feed back from HCSD PLC to main PLC) under the
following condition:
a) VFD ready to run.
b) Pump ready to run.
c) Lube pump on.
TECPRO SYSTEMS LTD
Page 29
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
d) Suction flow normal.
e) Air pressure normal.
• HCSD Pump Auto/manual selection from HCSD SCADA.
The start permissive of HCSD Pump from main PLC are as follows :
•
•
•
•
•
•
•
•
•
•
•
Silo Fluidizing Blower on.
LP Water tank level normal.
Manual suction valve open.
Agitator in ART run feedback.
ART tank level not low.
IAC Pressure normal.
HCSD PLC ready.
Paddle feeder run feedback.
Mixing tank level above pre set value.
Rotary feeder run feedback.
Charge pump run feedback.
13.3 High Concentration Slurry system (HCSD) Control Philosophy
Preconditions for starting HCSD pump :
1.
2.
3.
4.
5.
6.
7.
8.
Pump priming done.
HCSD pump PLC in remote mode.
HCSD pump PLC is not under fault.
Fly ash feed system is ready to run.
HCSD LP water pump pressure normal.
IAC pressure normal.
VFD for HCSD pumps not under fault.
Parameters are set as per discharge point and ash characteristics.
If anyone/more of the above preconditions is not satisfied, alarm will be generated after
seeking “ system ready” permissive.
System will be carried out in following sequence with “ System start” signal after “ system
ready” permissive is accepted.
TECPRO SYSTEMS LTD
Page 30
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
1.
2.
3.
4.
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
Pump ready to start command will be given by HCSD PLC.
Pump PLC will start lubrication pump.
Pump PLC will check for other healthy/normal conditions.
Pump PLC will convey “pump ready to start” signal to HCSD PLC.
If above conditions are in order/normal, system operation will proceed automatically in the
following sequence:
1. HCSD LP water valve will open to start filling ART tank.
2. Agitator will be started when certain water level reaches pre-set height in ART.
3. After pre-set time, charge pump suction valve will open.
4. Charge pump will be started.
5. When suction pressure pre-set value is reached, HCSD pump will be start.
6. Pump will start at 10% speed and ramp 20% at a preset rate defined in the VFD and
hold.
7. If pressure shoots up abnormally and crosses certain pre-set limit, the pump trips. After
being stabilized, if pressure is under normal set value range, fly ash will be introduced
in the system.
8. HCSD LP water feeding rate and fly ash feeding rate will be adjusted to maintain preset
slurry concentration.
9. When slurry level in ART reaches about 70%, further ramping of the pump will be
activated.
10. Slurry level in ART will be maintained at 55% to 65% with controlled fly ash and water
flow.
HCSD comprises of the following major sub-systems:
1. Fly ash feed system.
TECPRO SYSTEMS LTD
Page 31
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
2. HCSD LP water control system.
3. Closed loop control system.
4. Concentration slurry discharge system.
13.4 Fly Ash Feed System
Dry fly ash feeding will be controlled by VFD rotary feeder. Solid flow meter will
continuously monitor the feeding rate of fly ash from Rotary Feeder and will send
feedback to VFD and thus control of ash feeding rate into the system will be achieved.
13.5 HCSD LP water control system
Opening/closing of flow control valves and pneumatically operated water valves,
providing water to mixer will be controlled by manual/ auto mode. Under automatic
mode, opening/closing of valves will be synchronized with signal generated through
solid flow meter. Provision of an alarm is envisaged if pressure/flow of water falls
below a preset value. If pressure/ flow of water remain low for a pre-set time value,
Pneumatically operated plate valve / KGV below silo will close and rotary feeder will
stop sequentially.
Mixing Tank(ART) Operation and Level Control
The Mixing Tank (ART) will have a suggested five level control:1.
2.
3.
4.
5.
High High Level (90%)
High Level (80%)
Operating Level (70%)
Low Level (10%)
Low Low Level (0%)
Zero level (0%) is set at the start of the concentric part of the mixing tank. The 100% level
is maximum slurry level allowable in the tank.
The Mixing Tank (ART) operating level height will be controlled by the HCSD pump
speed within +/- 10% of the actual speed setting of the pump. When indicating “high level”
or “ low level”, the main system PLC will give an alarm. The alarm will be made visible to
the operator is advised to find the reason of alarm and/ or change system settings.
TECPRO SYSTEMS LTD
Page 32
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
When indicating “High High Level” the slurry feed to the system is stopped. An alarm is
envisaged on HCSD system central control panel. The system will remain in operation but
the slurry feed can only be restarted manually.
When indicating “ Low Low Level” an alarm is made visible on main system PLC screen
and the system will be stopped.
Suction Pressure Monitoring
The charge pump located closely at the ART will feed the slurry at sufficient pressure to
maintain pump. The suction pressure transmitter will signal the suction pressure.
Monitoring of suction pressure is started upon activation of following three signals:
1. Running charge pump.
2. Suction pressure >/= 2 Bar.
3. HCSD pump motor running.
During normal operation the suction pressure is monitored and reported. When this
pressure will become too low, the HCSD pump PLC will generate an alarm but system will
continue to operate. When suction pressure will remain low continuously for a
predetermined time, the HCSD pump will stop.
13.5 HCSD Pump Operation
A. Local/ Remote Mode
The pipeline system flow is a function of, and proportional to the HCSD pump stroke rate.
The HCSD pump drive motor speed and hence stroke rate and flow rate are controlled
with an input signal to HCSD pump VFD. Hence the required capacity of system will be
determine the nominal stroke speed setting for the HCSD pump.
The operating system will be equipped with facilities to adjust and maintain a pre-set
minimum speed, a pre-set maximum speed and the ramp up time.
The pump control panel will be provided with software for local/ remote operation and a
selector switch will be provided for choosing the local/ remote option. In local mode the
operator will control the pump speed and acceleration time manually. In the remote mode,
the pump speed and acceleration will be subject to maximum discharge pressure of system
TECPRO SYSTEMS LTD
Page 33
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
and to the physical limitation of the equipment. An alarm will be generated if pre-set
boundary speed limit is reached.
B. Overpressure Protection
The discharge pressure transmitter, located at the pulsation dampener will monitor the
discharge / pipe line entrance pressure continuously. The system will start diluting the
slurry at a pre-set discharge pressure. An alarm will be generated if the discharge pressure
crosses a pre-set value over continuous operating pressure. Main motor will automatically
stop if discharge pressure crosses a pre-set value over above mentioned alarm generating
pressure. If the pressure goes on increasing for instance, immediately after shut down,
owing to mass inertia of the unit, pump internal safety relief valve will open
automatically.
C. HCSD Pump Tripping
The HCSD pump will trip if during normal operation a trip signal is received from any of
the following:
1.
2.
3.
4.
The pump control PLC
Emergency push button
Trip signal from motor or drive protection system
The main system control PLC, based on programmed scenarios.
Depending on the type of stop, the same HCSD pump may be available for restart and
slurry cleaning procedures.
D. Normal system stop
Sequence to be followed for normal system stopping
1. Pneumatically operated plate valve/ KGV, below HCSD silo, at the ash entry point to
HCSD to be closed.
2. Paddle Feeder is stopped.
3.
4.
5.
6.
Mixer is emptied and stopped.
Mixer is stopped.
The level of ART is allowed to lower until “Low Level” is reached.
Water is feed into the ART and “ High Level” is reached with charge pump and HCSD
pump operating continuously.
TECPRO SYSTEMS LTD
Page 34
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
7. Continuous feeding of water in ART and continuous operation of charge pump and
HCSD pump will be maintained for a pre-set time to flush all pipe length.
8. Water feeding in ART is stopped.
9. Charge pump and HCSD pump will be stopped when “ Low Low Level” on ART is
reached.
The slurry cleaning cycle can be followed or interrupted for the introduction of a scraper
sphere.
The slurry cleaning sequence can be initiated manually when there is scheduled system
stop.
13.6 De-Blocking
The HCSD pump shall be capable of de-blocking the pipe line. De- blocking shall proceed
with pumping of water, which will enter the pipe system at the suction of charge pump.
Protection Interlock for various drives
BOTTOM ASH SYSTEM
1. Clinker Grinders :a)
Forward running permissive :- Following Starting & Running Permissive
are required for any CG forward or reverse running –
TECPRO SYSTEMS LTD
Page 35
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
i) Seal water pressure normal.
ii) Jet pump inlet water pressure normal.
iii) Jet pump inlet water valve open.
iv) Other CG in same section is off.
b)
i)
ii)
iii)
iv)
Trip Condition :Jet Pump inlet valve not open.
Jet pump inlet water pressure low & CG is running in forward direction.
Seal water pressure low & CG is running in forward direction.
Manual mode selected & ZSS operated & CG is running in forward
direction.
c)
i)
ii)
iii)
Actuations :Forward/ reverse and stop buttons in BALCP & HMI.
Auto / manual jamming removal selection in BALCP & HMI.
Auto start & stop commands will come from auto jam removal sequence.
iv)
Local/Remote Selector switches in HMI. When in Local mode operation
Through BALCP be disabled, when in Remote mode operation through
HMI be disabled
d)
i)
ii)
iii)
e)
i)
ii)
iii)
Indications in HMI & BALCP
Forward/ reverse running or stop.
Seal water pressure normal.
Jet Pump inlet water pressure normal on HMI.
Annunciation in HMI & BALCP
CG seal water pressure low.
CG jammed.
CG tripped.
2. Jet pump inlet valve :a) Open permissive :i) Other jet pump inlet valve of that section of BA hopper closed.
TECPRO SYSTEMS LTD
Page 36
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
b) Actuations: - Open & close buttons in BALCP & HMI.
c) Trip Condition: - Nil.
d) Indications in HMI & BALCP
i)
Open/ close status.
ii)
Jet pump inlet pressure normal.
e) Annunciation in HMI & BALCP
i)
Jet pump inlet water pressure low.
3. CG Seal Water Valve:a) Actuations :i)
Open & close buttons in HMI.
ii)
Auto open command with corresponding jet pump inlet valve opened
feedback.
iii) Auto close command with corresponding jet pump inlet valve closed
feedback.
b) Indications in HMI & BALCP:
i)
Open/ close status.
ii) Seal water pressure normal.
c) Annunciation in HMI & BALCP:
i.
Seal water pressure Low.
4. Feed Gate :a) Open permissive :i)
Other feed gate that section of BA hopper closed.
ii)
Corresponding CG is forward running.
iii) Any BA HP pump is running.
TECPRO SYSTEMS LTD
Page 37
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
iv)
v)
vi)
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
Corresponding BA slurry line discharge pressure is not high.
Corresponding jet pump inlet water valve open & water pressure normal.
Corresponding CG seal water pressure normal.
b) Running permissives :i)
Corresponding CG is forward running.
ii)
Any BA HP pump is running.
iii) Corresponding BA slurry line discharge pressure is not high.
iv) Corresponding jet pump inlet water valve open & water pressure normal.
c) Actuations: - Open & close buttons in BALCP & HMI.
d) Indications in HMI & BALCP: - Open/ close status.
5. BA O/F pumps :a) Start permissive :i)
Sump level not low.
ii)
Suction valve opened.
iii) Discharge valve closed.
iv) BA seal water pressure normal.
v)
Fluid coupling pump ON.
vi) Fluid coupling temp not high.
vii) Fluid coupling pressure not low.
b) Running permissive :i)
Sump level not low.
ii)
Suction valve opened.
iii) Pump ON & Discharge valve opened.
iv) BA O/F pump seal water pressure normal.
v)
Fluid coupling pump ON.
vi) Fluid coupling temp not high.
vii) Fluid coupling pressure not low.
TECPRO SYSTEMS LTD
Page 38
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
c) Actuations :i)
Start and stop buttons in BALCP & HMI.
d) Indications in HMI & BALCP
i)
Start & stop status.
ii)
Seal water pressure normal.
iii) BA O/F tank level Low.
iv) BA O/F tank level high.
e) Annunciation in HMI & BALCP
i)
BA O/F seal water pressure low.
ii)
BA O/F pump tripped.
iii) BA O/F tank level high and low.
iv) BA O/F pump F/C temp high.
v)
BA O/F pump F/C pressure low.
6. BA O/F pump suction valve :a) Open permissive: - Nil.
b) Actuations :i)
Open & close buttons in BALCP & HMI.
ii)
Auto close pulse with pump off feedback.
iii) Auto open pulse with pump selection feedback.
c) Indications in HMI & BALCP: Open/ close status.
7. BA O/F pump seal water valve :a) Open permissive:- Nil
b) Actuations :TECPRO SYSTEMS LTD
Page 39
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
i)
ii)
iii)
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
Open & close buttons in HMI.
Auto open pulse with run feedback of corresponding BA O/F pump.
Auto close pulse with pump off feedback.
c) Indications in HMI & BALCP: Open/ close status.
8. BA O/F pump discharge valve :a) Open permissive: - Corresponding BA O/F pump ON.
b) Actuations :i)
Open & close buttons in BALCP & HMI.
ii)
Auto open pulse with corresponding BA O/F pump ON feedback.
iii) Auto close pulse with pump off feedback.
c) Indications in HMI & BALCP: Open/ close status.
9. BA O/F pump F/C oil pump :a) Start permissive: - Nil.
b) Trip permissive: i)
F/C oil temperature High & F/C Pump Running.
ii)
F/C Pump Running & Oil Pressure Low.
c) Actuations :i)
Open & close buttons in HMI.
ii)
Auto start pulse with corresponding BA O/F pumps suction valve open
feedback.
iii) Auto stop pulse with corresponding BA O/F pump off feedback.
d) Indications in HMI: On/ OFF status.
TECPRO SYSTEMS LTD
Page 40
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
e) Annunciation:
i) F/C oil temperature High.
ii) F/C oil pressure Low.
10. BA hopper make valves from BA HP & BA LP:a) Open permissive: - nil.
b) Actuations :i)
Open & close buttons in BALCP & HMI.
c) Indications in HMI & BALCP: Open/ close status.
11. BA Seal Water Pump :a) Start permissive:i)
BA Seal Water Suction pressure not low.
b) Trip Condition: i) BA Seal Water Suction pressure low.
c) Actuations :i) Start & Stop Push Buttons in HMI.
d) Indications:i) ON/OFF status in HMI
ii) Suction Pressure Normal.
e) Annunciation:
i) Suction Pressure not Normal.
TECPRO SYSTEMS LTD
Page 41
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
12. Sludge Pump:a) Start Permissive:i)
Surge Tank level is NOT LOW.
ii)
Discharge valve is CLOSED.
iii) Suction valve is OPENED.
iv) Surge tank or settling tank outlet valve is OPENED.
v)
Seal water pressure is NOT LOW.
b) Trip Permissive:i)
Surge tank level is LOW.
ii)
Discharge pressure is HIGH.
iii) Seal water pressure is LOW.
c) Actuations :i)
Open & close buttons in HMI.
d) Indications:i)
ON and OFF status in HMI.
e) Annunciations:i)
Sludge pumps Trip in HMI.
ii)
Surge tank level LOW.
13. Sludge pump suction valve:a) Open Conditions:i)
Opens with selection of corresponding Sludge pump.
b) Close Conditions:i)
Nil.
c) Actuations :ii)
Open & close buttons in HMI.
TECPRO SYSTEMS LTD
Page 42
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
d) Indications:i)
OPEN and CLOSE status in HMI.
14. Sludge pump discharge valve:a) Open Conditions:i)
Corresponding sludge pump is ON.
ii)
Automatically opens with running of sludge pump.
b) Close Conditions:i)
Automatically closes with sludge pump is NOT ON after a delay.
c) Actuations :i)
Open & close buttons in HMI.
d) Indications:i)
OPEN and CLOSE status in HMI.
15. Sludge pump seal water valve:a) Open Conditions:i)
ii)
At least one seal water pump running.
Automatically opens with running of corresponding sludge pump.
b) Close Conditions:i)
Automatically closes with corresponding sludge pump OFF.
c) Actuations :i)
Open & close buttons in HMI.
d) Indications:i)
OPEN and CLOSE status in HMI.
TECPRO SYSTEMS LTD
Page 43
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
16. Surge Tank outlet valve:a) Open Conditions:i)
Surge Tank is selected.
ii)
Surge tank level is NOT LOW.
b) Close Conditions:i)
Nil.
c) Actuations :iii) Open & close buttons in HMI.
d) Indications:i)
OPEN and CLOSE status in HMI.
17. Settling Tank outlet valve:a) Open Conditions:i)
Settling tank is selected.
b) Close Conditions:i)
Nil.
a) Actuations :iv) Open & close buttons in HMI.
b) Indications:OPEN and CLOSE status in HMI
FLY ASH SYSTEM
2. Vacuum Pump :a. Start Permissive :i)
Vacuum Pump seal water pressure is NOT LOW.
TECPRO SYSTEMS LTD
Page 44
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
ii)
iii)
iv)
v)
b. Trip
i)
ii)
iii)
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
Vacuum Pump suction valve is OPENED.
Corresponding Buffer Hopper Vacuum line valve is OPENED.
Corresponding Buffer Hopper Ash line valve is OPENED.
Corresponding Buffer Hopper vacuum breaker valve is opened.
Permissive :Vacuum pump is ON and seal water pressure is LOW after a delay.
Vacuum pump is ON and suction valve is NOT OPENED after a delay.
Corresponding Buffer Hopper Vacuum line valve is closed.
c. Actuations :i)
ON and OFF buttons in HMI.
d. Indications:i)
ON and OFF indications in HMI.
e. Annunciation:i)
Vacuum Pump TRIP in HMI.
ii)
Vacuum pump seal water pressure LOW in HMI.
3. Vacuum Pump Suction Valve:a. Open Conditions:- Nil
b. Close Conditions:- Nil
c. Actuations :i)
Automatically opens with corresponding Buffer Hopper selection
ii)
Automatically closes with Vacuum pump OFF.
d. Indications:i)
OPEN and CLOSE indications in HMI.
4. Vacuum pump Seal Water Valve:TECPRO SYSTEMS LTD
Page 45
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
a. Open Conditions:- Nil
b. Close Conditions:- Nil
c. Actuations :i)
Automatically opens with corresponding Buffer Hopper selection.
ii) Automatically closes with Vacuum pump OFF.
d. Indications:i)
OPEN and CLOSE indications in HMI.
ii)
Seal Water Pressure Normal
e. Annunciation:i) Seal Water Pressure Low.
5.
Buffer Hopper Vacuum Line Valve:-
a) Open Conditions:- Nil
b) Close Conditions:- Nil
c) Actuations :i)
Automatically opens with corresponding Buffer Hopper selection
ii) Automatically closes with Vacuum pump OFF.
d) Indications:i) OPEN and CLOSE indications in HMI.
6. Buffer Hopper Ash Line Valve:a) Open Conditions:- Nil
b) Close Conditions:- Nil
TECPRO SYSTEMS LTD
Page 46
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
c) Actuations :1) Automatically opens with corresponding Buffer Hopper Vacuum line valve
open feedback.
2) Automatically closes with corresponding Buffer Hopper Vacuum line valve
close feedback.
d) Indications:ii)
OPEN and CLOSE indications in HMI.
7. Buffer Hopper vacuum Breaker Valve :a. Open Conditions:i)
Automatically opens when corresponding Buffer Hopper is selected and
Fly Ash STOP command is given.
ii)
Automatically opens when Auto mode is selected, START command is
given and line vacuum is greater than an value(VS5).
iii) Opens in protection when close permissive is NOT there or line vacuum is
greater than a value(VS5).
b. Close Conditions:i)
Corresponding Buffer Hopper is Selected.
ii)
Buffer Hopper valve is OPENED.
iii) Vacuum pump suction valve is OPENED.
iv) Vacuum pump is ON.
v)
Automatically closes when buffer hopper is selected and Fly Ash START
command is given.
vi) Automatically closes when in Auto mode, START command is there and
line vacuum is less than a value(VS6).
c. Actuations:i)
OPEN and CLOSE buttons in HMI.
d. Indications:i)
OPEN and CLOSE indications in HMI.
TECPRO SYSTEMS LTD
Page 47
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
e. Annunciation:i)
Line vacuum very high (greater than a value of VS5).
8.
Stream Branch Isolation Header Valve:-
a) Open Conditions:i)
Buffer hopper selected.
ii)
Other Branch Isolation valve in same stream not opened.
iii) All ESP hopper discharge valve in a stream not bypassed.
iv) Sequentially opens when Fly Ash START command is given or any ash
intake valve of the branch is selected in AUTO mode.
b) Close Conditions:i)
Automatically closes when other branch header valve opens or Fly Ash
STOP command is given.
c) Actuations:ii)
OPEN and CLOSE buttons in HMI.
d) Indications:ii)
OPEN and CLOSE indications in HMI.
9. ESP Hopper Ash Discharge valve:a) Open Conditions:i)
Buffer Hopper is selected.
ii)
Corresponding Buffer Hopper level is not HIGH. .If Buffer Hopper level
high persists then ESP Hopper Discharge Valve will close & will open
automatically when buffer hopper level drops within a preset level in auto
mode evacuation
iii) Corresponding Buffer Hopper Ash Line Valve open.
iv) Corresponding Buffer Hopper vacuum breaker valve is CLOSED.
v)
Corresponding Vacuum pump is ON.
TECPRO SYSTEMS LTD
Page 48
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
vi) BH Pulse jet is ON.
vii) Line vacuum is in operating range.
viii) Once the sequence is in operations then automatically opens and closes
between vacuum levels (VS3 & VS4).
ix) Respective ESP hopper not bypassed.
x)
Respective Branch Isolation Header Valve opened.
xi)
b) Close Conditions:i)
Closes when open conditions are not available.
ii)
Jumps to the next ESP Hopper Ash Discharge Valve when vacuum is
either below the NO Load Vacuum for a preset time or in plugged
condition for a preset time in auto mode.
c) Actuations:ii) OPEN and CLOSE buttons in HMI for manual mode operation.
d) Indications:i)OPEN and CLOSE indications in HMI.
10.
Buffer Hopper Fluidizing Valve:a) Open Conditions:i)
Corresponding Buffer Hopper is selected.
b) Close Conditions:i)
Automatically closes with both buffer hoppers fluidizing blower OFF.
ii)
Automatically closes with buffer hopper not selected.
c) Actuations:i.
OPEN and CLOSE buttons in HMI for manual mode operation in HMI.
ii.
Automatically opens with any buffer hopper fluidizing blower ON.
iii.
Automatically closes with either both buffer hoppers fluidizing blower
OFF or corresponding Buffer Hopper is not selected.
TECPRO SYSTEMS LTD
Page 49
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
d) Indications:i)
OPEN and CLOSE indications in HMI.
11.
Buffer Hopper Fluidizing Blower:a) Start permissive :i.
Any Buffer Hopper Fluidizing Valve Opened.
b) Actuations :i) Start and stop buttons in HMI.
c) Indications :
i)
ON/OFF status in HMI.
d) Annunciation :
i)
Buffer Hopper Fluidizing Blower Tripped annunciation in HMI.
12.
Buffer Hopper Fluidizing Heater Bank-1:a) On permissive:i)
Corresponding fluidizing blower On and
ii)
Fluidizing heater discharge temperature low.
b) OFF Conditions:i)
Corresponding heater discharge temperature danger high
.
c) Actuations :i)
Auto on pulse with corresponding blower on permissive.
ii)
Auto off pulse with heater discharge temperature high or all blower off.
13.
Buffer Hopper Heater Bank-2:-
TECPRO SYSTEMS LTD
Page 50
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
a) On permissive:i)
Corresponding fluidizing blower on and
ii)
Fluidizing heater discharge temperature low or corresponding heater
discharge temperature not high.
b) OFF Conditions:i)
Corresponding heater discharge temperature danger high.
c) Actuations :i)
Auto on pulse with corresponding blower on permissive.
ii)
Auto off pulse with heater discharge temperature very high or
corresponding blower off.
14. Buffer Hopper Fluidizing Heater Bank-3:a) On permissive:i)
Corresponding fluidizing blower on and
ii)
Fluidizing heater discharge temperature low or corresponding heater
discharge temperature not very high.
b) Actuations :i)
Auto on pulse with corresponding blower on permissive.
ii)
Auto off pulse with heater discharge temperature danger high or
corresponding blower off.
c) Indications:i)
Heater on and off indication (any bank on/ off of corresponding heater) in
HMI.
a) Annunciation :
i)
Buffer Hopper Fluidizing Heater Trip annunciation in HMI.
ii)
Buffer Hopper Fluidizing Heater Temp hi and hi-hi.
TECPRO SYSTEMS LTD
Page 51
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
15.
Vacuum system AUTO SEQUENCE (separate sequence for each
ESP pass):a) Sequence start permissive :i)
Instrument air pressure is normal.
ii)
Vacuum pump of selected buffer hopper is running.
iii) Selected vacuum breaker closed.
iv) Pulse jetting of selected buffer hopper is ON.
v)
Any fluidizing blower is ON.
vi) No load vacuum is established (i.e. vacuum more than VS1).
vii) Selected buffer hopper level is not high.
viii) Selected buffer hopper vacuum line valve open.
ix) Selected buffer hopper Ash line valve open
b) Actuations :i)
Auto sequence Start and stop buttons in HMI.
ii)
When Auto sequence stop button is pressed, the sequence will hold at that
step and selected ESP Hopper Discharge Valve will close and when auto
sequence start is pressed again sequence will start from step where it was
held.
c) Indications in HMI: current cycle completed, number of cycles counter, Time
taken by current cycle. Vacuum set points, vacuum analog value.
d) Annunciation:
i.
ii.
16.
Vacuum Very High,
ESP Hopper plugged.
Pressure Conveying system AUTO SEQUENCE (separate sequence
for each pressure conveying line):a) Sequence start permissive :i)
Pressure Conveying line through.
ii)
TAC running.
TECPRO SYSTEMS LTD
Page 52
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
iii)
iv)
v)
vi)
vii)
viii)
ix)
x)
xi)
xii)
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
Normal/Flushing Mode Selected.
HCSD/ FA Silo selected
Selected Silo Vent fan running.
Selected Silo Vent Filter Purging running.
Selected line & Selected Silo Ash Intake valve opened.
Selected Silo Level not high.
Pressure Conveying line selected.
Selected Conveying line Fluidizing valve open.
Selected Conveying line Conveying valve open.
START Push Button pressed.
b) Actuations :i)
Auto sequence Start and stop buttons in HMI.
c) Indications in HMI: current cycle completed, number of cycles counter, Time
taken by current cycle, timer set point configurable from HMI.
d) Annunciation: Pressure Conveying Line chocked.
17.
Pressure Conveying line conveying valve:a) Open Permissive:iii) Automatically opens when corresponding line is selected.
b) Close Conditions:ii)
Automatically closes when corresponding line is de selected.
c) Actuations:i)
OPEN and CLOSE selector switch in HMI.
d) Indications:i)
OPEN and CLOSE indications in HMI.
18.
Pressure Conveying line fluidizing valve:c) Open Conditions:ii)
Automatically opens when corresponding line is selected.
TECPRO SYSTEMS LTD
Page 53
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
d) Close Conditions:ii)
Automatically closes when corresponding line is de selected.
e) Actuations:i)
OPEN and CLOSE selector switch in HMI.
f) Indications:i)
OPEN and CLOSE indications in HMI.
19.
Air Lock vessel Fluidizing valve:1. Open Permissive:i)
Pressure Conveying line through.
ii)
Corresponding TAC running.
iii) Normal/Flushing Mode Selected.
iv) HCSD/ FA Silo selected
v)
Selected Silo Vent fan running.
vi) Selected Silo Vent Filter Purging running.
vii) Selected line & Selected Silo Ash Intake valve opened.
viii) Selected Silo Level not high.
ix) Airlock vessel selected.
x)
Auto Mode the valve will automatically open as per Time Cycle in Normal
/ Flushing mode
2. Close Conditions:i)
Pressure Conveying line not through.
ii)
Corresponding TAC not running.
iii) Selected Silo Vent fan not running.
iv) Selected Silo Vent Filter Purging not running.
v)
Selected line & Selected Silo Ash Intake valve not opened.
vi) Selected Silo Level high.
vii) Airlock vessel not selected.
TECPRO SYSTEMS LTD
Page 54
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
viii) Auto Mode the valve will automatically close as per Time Cycle in Normal
/ Flushing mode.
e) Actuations:i)
OPEN and CLOSE selector switch in HMI.
f) Indications:i)
OPEN and CLOSE indications in HMI.
20.
Air Lock vessel Discharge valve:1. Open Permissive:i) Pressure Conveying line through.
ii)
Corresponding TAC running.
iii) Normal/Flushing Mode Selected.
iv) HCSD/ FA Silo selected
v)
Selected Silo Vent fan running.
vi) Selected Silo Vent Filter Purging running.
vii) Selected line & Selected Silo Ash Intake valve opened.
viii) Selected Silo Level not high.
ix) Airlock vessel selected.
x)
Auto Mode the valve will automatically open as per Time Cycle in Normal
/ Flushing mode.
2. Close Conditions:i)
Pressure Conveying line not through.
ii)
Corresponding TAC not running.
iii) Selected Silo Vent fan not running.
iv) Selected Silo Vent Filter Purging not running.
v)
Selected line & Selected Silo Ash Intake valve not opened.
vi) Selected Silo Level high.
vii) Airlock vessel not selected.
viii) Auto Mode the valve will automatically close as per Time Cycle in Normal
/ Flushing mode.
3. Actuations:i)
OPEN and CLOSE selector switch in HMI.
TECPRO SYSTEMS LTD
Page 55
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
4. Indications:i)
OPEN and CLOSE indications in HMI.
21.
Air Lock vessel Vent valve:1. Open Permissive:i)
Pressure Conveying line through.
ii)
Corresponding TAC running.
iii) Normal/Flushing Mode Selected.
iv) HCSD/ FA Silo selected
v)
Selected Silo Vent fan running.
vi) Selected Silo Vent Filter Purging running.
vii) Selected line & Selected Silo Ash Intake valve opened.
viii) Selected Silo Level not high.
ix) Airlock vessel selected.
x)
Auto Mode the valve will automatically open as per Time Cycle in Normal
mode
2. Close Conditions:i)
Pressure Conveying line not through.
ii)
Corresponding TAC not running.
iii) Selected Silo Vent fan not running.
iv) Selected Silo Vent Filter Purging not running.
v)
Selected line & Selected Silo Ash Intake valve not opened.
vi) Selected Silo Level high.
vii) Airlock vessel not selected.
viii) Auto Mode the valve will automatically close as per Time Cycle in Normal
mode.
g) Actuations:i)
OPEN and CLOSE selector switch in HMI.
h) Indications:i)
OPEN and CLOSE indications in HMI.
22.
Air Lock vessel Ash Intake valve:-
TECPRO SYSTEMS LTD
Page 56
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
1. Open Permissive:i)
Pressure Conveying line through.
ii)
Corresponding TAC running.
iii) Normal/Flushing Mode Selected.
iv) HCSD/ FA Silo selected
v)
Selected Silo Vent fan running.
vi) Selected Silo Vent Filter Purging running.
vii) Selected line & Selected Silo Ash Intake valve opened.
viii) Selected Silo Level not high.
ix) Air lock vessel selected.
x)
Auto Mode the valve will automatically open as per Time Cycle in Normal
mode.
2. Close Conditions:i)
Pressure Conveying line not through.
ii)
Corresponding TAC not running.
iii) Selected Silo Vent fan not running.
iv) Selected Silo Vent Filter Purging not running.
v)
Selected line & Selected Silo Ash Intake valve not opened.
vi) Selected Silo Level high.
vii) Airlock vessel not selected.
viii) Auto Mode the valve will automatically close as per Time Cycle in Normal
mode.
3. Actuation:i)
OPEN and CLOSE selector switch in HMI.
4. Indications:i)
OPEN and CLOSE indications in HMI.
23.
Buffer Hopper Purging System:1. Open Permissive:i)
Buffer Hopper selected.
TECPRO SYSTEMS LTD
Page 57
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
ii)
iii)
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
Instrument Air Pressure Normal.
Corresponding Vacuum Pump running..
2. Close Conditions:i. Buffer Hopper not selected.
ii. Instrument Air Pressure not Normal.
iii. Corresponding Vacuum Pump not running..
3. Actuation:i)
OPEN and CLOSE selector switch in HMI.
4. Indications:ii)
OPEN and CLOSE indications in HMI.
Note: Purging system will operate sequentially within preset time (two purge
valve at a time for 0.5 sec after every interval of 30 sec). If differential
pressure is high, purging sequence time will be 0.5 sec after every interval of
15 sec.
ASH WATER & ASH SLURRY SYSTEM
1. BAHP Water Pumps :a. Start Permissive :i)
BAHP Water Pump is selected.
TECPRO SYSTEMS LTD
Page 58
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
ii)
iii)
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
Ash water sump is Not Low.
Any Jet pump water inlet valve is Open.
b. Trip Permissive :i)
Ash water Sump level very Low.
ii)
All Jet pump water inlet valve is close.
c. Running Permissive :i)
Ash water sump level is Normal.
d. Actuations :i)
ON and OFF buttons in HMI.
ii)
BAHP water pump selector switch.
e. Indications:i)
ON and OFF indications in HMI.
ii)
BAHP Discharge Pressure indication in HMI.
f. Annunciation:i)
BAHP water pumps Trip in HMI.
ii)
BAHP Discharge pressure LOW.
iii) BAHP Discharge pressure HIGH..
2. BALP Water Pumps :a. Start Permissive :i)
BALP pump is selected. (2 out of 3 pumps can be selected)
ii)
Ash water sump level is Not Low.
b. Trip Permissive :i)
Ash water sump level is very Low.
c. Running Permissive :TECPRO SYSTEMS LTD
Page 59
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
i)
Ash water sump level is Normal.
.
d. Actuations :i)
ON and OFF buttons in HMI.
ii)
BALP water pump selector switch.
e. Indications:i)
ON and OFF indications in HMI.
ii)
BALP Discharge Pressure indication in HMI.
f. Annunciation:i)
BALP water pumps Trip in HMI.
iii) BALP Discharge pressure LOW.
iv) BALP Discharge pressure HIGH..
3. Flushing Water Pump :a. Start Permissive:i)
Ash Slurry series Flushing Mode is Selected.
ii)
Ash water sump level in Not Low.
b. Trip Permissive:i) Ash water sump level in very Low.
c. Running Permissive :i)
Ash water sump level is Normal.
d. Actuations:i)
ON and OFF buttons in HMI.
e. Indications:i)
ON and OFF indications in HMI.
ii)
Flushing Water Pump Discharge Pressure indication in HMI.
f. Annunciations:i)
Flushing water pumps Trip in HMI.
TECPRO SYSTEMS LTD
Page 60
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
ii)
iii)
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
Flushing water pumps Discharge pressure LOW.
Flushing water pumps Discharge pressure HIGH.
4. Eco Ash Water Pump :a. Start Permissive :i)
Eco Ash water pump is selected.
ii)
Ash water sump level in Not Low.
b. Trip Permissive :i)
Ash water sump level in very Low.
c. Running Permissive :v)
Ash water sump level is very Normal.
d. Actuations :i)
ON and OFF buttons in HMI.
e. Indications:i)
ON and OFF indications in HMI.
ii)
ECO water pump Discharge Pressure indication in HMI
f. Annunciations:i)
Eco Ash water pumps Trip in HMI.
ii)
Eco Ash water pumps Discharge pressure LOW.
iii) Eco Ash Water pump Discharge pressure HIGH.
5. Seal Water Pumps :a. Start Permissive:i)
Seal water Tank level is Adequate.
b. Trip Permissive:i)
Seal water Tank level Danger Low.
TECPRO SYSTEMS LTD
Page 61
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
c. Running Permissive :i)
Seal water Tank level in Normal..
ii)
Second pump will Auto Start with tripping of first pump or discharge
pressure low.
d. Actuations:i)
ON and OFF buttons in HMI.
ii)
Working/Standby selector switch in HMI.
e. Indications:i)
ON and OFF indications in HMI.
ii)
Seal water pump Discharge Pressure indication in HMI
f. Annunciation:i)
Seal water pumps Trip in HMI.
ii)
Seal water discharge pressure Low.
6. Ash water sump make valve from CT Blow down:a. Open Conditions:- NIL
b. Close Conditions:- NIL
.
c. Actuations:i)
ON and OFF buttons in HMI.
ii)
Automatically opens when in Auto level control mode and sump level is
LOW.
iii) Automatically closes when in Auto level control mode and sump level is
HIGH
d. Indications:i)
ON and OFF indications in HMI.
ii)
Ash Water Sump Level Indication in HMI.
TECPRO SYSTEMS LTD
Page 62
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
e. Annunciation:i)
Ash Water Sump Level LOW in HMI
ii)
Ash Water Sump Level very LOW in HMI
iii) Ash Water Sump Level LOW in HMI
iv) Ash Water Sump Level LOW in HMI.
7. Ash water sump make valve from Recirculation Ash Water:a. Open Conditions:- NIL
b. Close Conditions:- NIL
.
c. Actuations:i)
ON and OFF buttons in HMI.
ii)
Automatically opens when in Auto level control mode and sump level is
LOW.
iii) Automatically closes when in Auto level control mode and sump level is
HIGH
d. Indications:i)
ON and OFF indications in HMI.
8. Ash water sump make valve from RAW Water:a. Open Conditions:- NIL
b. Close Conditions:- NIL
.
c. Actuations:i)
ON and OFF buttons in HMI.
ii)
Automatically opens when in Auto level control mode and sump level is
Very LOW.
iii) Automatically closes when in Auto level control mode and sump level is
HIGH
TECPRO SYSTEMS LTD
Page 63
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
d. Indications:i)
ON and OFF indications in HMI.
9. First stage slurry pump :a) Start permissive :i)
Suction valve open or flushing mode selected & suction valve closed.
ii)
Discharge valve closed.
iii) Corresponding sump compartment level > very low.
iv) Seal water pressure is normal.
v)
Fluid coupling oil pump ON.
vi) Cooling water pressure to fluid coupling is normal
vii) Fluid coupling oil temp not high.
viii) Motor bearing temp not high.
ix) Motor winding temp not high.
Trip conditions:i)
First stage pump ON & Discharge valve Not opened (with 15 sec time
delay).
i)
Corresponding sump compartment level < very low (with 5 sec time
delay).
ii) Seal water pressure is low (with preset time delay).
iii) Cooling water pressure to fluid coupling is low (time delay 5 sec)
iv) Fluid coupling oil temp high (time delay 5 sec).
v) Motor bearing temp very high (time delay 2 sec).
vi) Motor winding temp high (time delay 2 sec).
ii)
2nd stage pump OFF and Ist stage pump ON (with time delay 30 sec).
b) Actuations :i)
Start and stop buttons in HMI.
ii)
Series group start / Stop from HMI if Auto is selected from HMI.
c) Indications in HMI
vii) Start & stop status.
TECPRO SYSTEMS LTD
Page 64
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
viii) Series discharge pressure, bearing temps, winding temps, seal water
pressure, fluid coupling oil temp, fluid coupling water pressure.
d) Annunciation in HMI
i)
Pump tripped.
ii)
Discharge pressure low.
iii) Discharge pressure High..
iv) Seal water pressure low.
v)
Bearing temp high.
vi) Winding temp high.
10.
2nd stage slurry pump :a) Start permissive :i)
Ist stage slurry pumps ON.
ii)
Series discharge valve is open.
iii) Corresponding sump compartment level > very low.
iv) Seal water pressure is normal.
v)
Motor bearing temp not high.
vi) Motor winding temp not high.
Trip conditions:i)
ii)
First stage pumps OFF (with 2 sec time delay).
Corresponding sump compartment level < very low (with 5 sec time
delay).
iii) Seal water pressure is low (with preset time delay).
iv) Motor bearing temp very high (time delay 2 sec).
v)
Motor winding temp high (time delay 2 sec).
vi) Pump ON and Discharge valve NOT open (time delay 5 sec).
b) Actuations :iii) Start and stop buttons in HMI.
iv) Series group start / Stop from HMI if Auto is selected from HMI.
c) Indications in HMI
ix) Start & stop status.
x) bearing temps, winding temps, seal water pressure,
TECPRO SYSTEMS LTD
Page 65
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
d) Annunciation in HMI
i)
Pump tripped.
ii)
Seal water pressure low.
iii) Bearing temp high.
iv) Winding temp high.
11. Slurry series suction valve
a) Open permissive :- (i) Normal mode selected.
b) Actuations :i)
Open / close buttons in HMI.
ii)
Opens in auto if series group start from HMI is given & normal mode is
selected.
iii) Auto close pulse when flushing mode is selected.
c) Indications in HMI: - Open & close status.
12. Slurry series pumps seal water valve
a) Open permissive: - Nil.
b) Actuations :i)
Open / close buttons in HMI.
ii)
Opens in auto if series group start from HMI is given & respective pump
running.
iii) Closes in auto if respective slurry series is OFF.
c) Indications: - Open & close status In HMI.
13. Slurry series discharge valve
a) Open permissive :- (i) First stage pump on.
TECPRO SYSTEMS LTD
Page 66
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
b) Actuations :i)
Open / close buttons in HMI.
ii)
Opens in auto with first stage pump ON feedback.
iii) Auto close pulse when slurry series is OFF.
c) Indications in HMI: - Open & close status.
14. Slurry sump make up valve
a) Open permissive :- Nil
b) Actuations :i)
Open / close buttons in HMI.
ii)
Auto open & close pulse with slurry sump level low & high respectively, if
selected in auto mode.
c) Indications: - Open & close status in HMI.
15. Slurry area drain pumps
a) Start permissive:i)
Drain sump level not low.
ii)
Respective Drain sump pump seal water pressure not low.
b) Trip permissive:i)
Drain sump level very low.
iii) Respective Drain sump pump seal water pressure low.
c) Actuations :i)
Start & stop buttons in HMI.
ii)
Auto start & stop pulse with drain sump level high & low respectively, if
selected in Auto mode.
d) Indications in HMI: - Open & close status, seal water pressure Normal.
TECPRO SYSTEMS LTD
Page 67
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
e) Annunciation: drain sump level high, seal water pressure low, pump tripped.
18. Slurry Series 1st stage pump F/C oil pump :f) Start permissive: - Nil.
g) Trip permissive: i)
F/C oil temperature High & F/C Pump Running.
iii)
F/C Pump Running & Oil Pressure Low.
h) Actuations :iv) Open & close buttons in HMI.
v)
Auto start pulse with corresponding 1st stage pumps suction valve open
feedback.
vi) Auto stop pulse with corresponding 1st stage pump off feedback.
i) Indications in HMI: On/ OFF status.
j) Annunciation:
i) F/C oil temperature High.
ii) F/C oil pressure Low.
19. FA Silo isolation valve:a) Open Conditions:-
NIL
b) Close Conditions:-
NIL
c) Actuations:i)
OPEN and CLOSE selector switch in HMI.
TECPRO SYSTEMS LTD
Page 68
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
ii)
Automatically opens when FA silo is selected. & corresponding conveying
line is selected. & Corresponding HCSD Silo isolation valve in the same
line is CLOSED
iii) Automatically closes when above conditions are not there.
d) Indications:i)
OPEN and CLOSE indication in HMI.
20. HCSD Silo isolation valve:a) Open Conditions:-
NIL
b) Close Conditions:-
NIL
c) Actuations:iv) OPEN and CLOSE selector switch in HMI.
v)
Automatically opens when HCSD silo is selected. & corresponding
conveying line is selected. & Corresponding FA Silo isolation valve in the
same line is CLOSED
vi) Automatically closes when above conditions are not there.
d) Indications:ii)
OPEN and CLOSE indication in HMI.
21. FA Silo Vent Fan:a) Start Permissive:ii)
Any of ash intake valves of the selected silo is OPENED.
b) Trip Permissive:ii)
Nil.
c) Actuations:i)
Start and Stop push buttons in HMI.
d) Indications:i)
Start and Stop indications in HMI.
e) Annunciations:TECPRO SYSTEMS LTD
Page 69
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
i)
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
Vent Fan TRIP in HMI.
22. HCSD Silo Vent Fan:a) Start Permissive:i)
Any of ash intake valves of the selected silo is OPENED.
b) Trip Permissive:i)
Nil.
c) Actuations:i)
Start and Stop push buttons in HMI.
d) Indications:i)
Start and Stop indications in HMI.
e) Annunciations:i)
Vent Fan TRIP in HMI.
23. TAC discharge line to conveying line valve:a) Open Conditions:i)
To be opened by operator by deciding which TAC is to be connected to
which conveying line.
b) Close Conditions:i)
Nil.
c) Actuations:i)
OPEN and CLOSE selector switch in HMI.
d) Indications:i)
OPEN and CLOSE indications in HMI.
24. TAC discharge line valve:a) Open Conditions:i)
To be opened by operator by deciding which TAC is to be connected to
which conveying line.
b) Close Conditions:i)
Nil.
c) Actuations:TECPRO SYSTEMS LTD
Page 70
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
i)
OPEN and CLOSE selector switch in HMI.
d) Indications:i)
OPEN and CLOSE indications in HMI.
25. Over head Tank makeup valve:a) Open Conditions:- Nil
b) Close Conditions:- NIL
c) Actuations:i)
OPEN and CLOSE selector switch in HMI.
ii)
Automatically opens with Tank level LOW.
iii) Automatically closes with Tank level HIGH.
d) Indications:ii)
OPEN and CLOSE indications in HMI.
i)
SILO UNLOADING SYSTEM
26. Wet Ash Unloading Discharge Valve :a. Open Permissive :i)
Wet unloading Rotary Feeder VFD ON and
ii)
Respective silo Rotary Unloader ON.
TECPRO SYSTEMS LTD
Page 71
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
b. Close Conditions:i)
Wet unloading Rotary Feeder VFD OFF
ii)
Respective silo Ash Conditioner OFF.
c. Actuations :i)
Open/Close Selector switch in SLUP & HMI
d. Indications:i)
Open/ close status in SCP, SLUP & HMI.
27. Dry Ash Unloading Discharge Valve:a) Open Permissive :i)
Dry Ash unloading Rotary Feeder VFD ON and
ii)
Respective silo tanker level NOT HIGH.
b) Close Conditions:i)
Dry Ash unloading Rotary Feeder VFD OFF
ii)
Respective silo tanker level HIGH. or
iii) Respective spout winch DOWN.
c) Actuations :i)
Open/Close Selector switch in SLUP & HMI
d) Indications:i)
Open/ Close status in SCP, SLUP & HMI
28. Wet Ash Unloading Rotary Feeder VFD :a. On Permissive:i)
Respective wet unloading Rotary Feeder VFD L/R switch in Remote
mode and
ii)
Respective wet unloading Rotary Feeder VFD NOT TRIPPED and
iii) Respective wet unloading Rotary Feeder VFD Ready to Run and
iv) Respective wet unloading Ash Conditioner ON and
v)
Any fluidizing Blower ON and
vi) Respective Silo fluidizing valve OPEN.
TECPRO SYSTEMS LTD
Page 72
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
b. Trip Permissive:i)
VFD will trip any of the above stated permissive is absent.
c. Actuations:vii) ON, OFF push buttons in SLUP, HMI and VFD panel.
d. Indications:iii) ON, OFF push buttons in SLUP, HMI and VFD panel.
e. Annunciations:iv) Trip in SCP & HMI.
29. Ash Conditioner:a. On permissive :i)
Respective conditioning water pressure is adequate.
b. Actuations :i)
On & Off Push Buttons in SLUP & HMI.
c. Indications:i)
On & Off status in SLUP, SCP & HMI.
30. Silo Ash Conditioner Water line Valve :a. Open/Close permissive:b.
c.
i) Nil.
Actuations:i) Open/Close selector switch in SLUP and HMI..
Indications:-
TECPRO SYSTEMS LTD
Page 73
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
i)
ii)
iii)
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
Open indication in SLUP, SCP and HMI.
Conditioning water pressure normal indication in SLUP, SCP and HMI.
Conditioning water pressure indication in SLUP, SCP and HMI.
31. Vent Fan For Telescopic Chute :a) On permissive:- NIL
b) Trip Permissive:- NIL
c) Actuations:i) Start, Stop push buttons in SLUP & HMI.
d) Indications:i)
ON and OFF status in SCP, SLUP & HMI.
32. Telescopic Spout :a) Down permissive:i)
Corresponding Purging system on and
ii)
Corresponding Vent fan ON.
b) Up permissive :iv) Corresponding Purging system on and
v)
Corresponding vent fan ON and
vi) Closed truck level high.
c) Actuation:i)
UP and DOWN push buttons in SLUP and HMI.
d) Indications:i)
UP, DOWN and STOP indication lamps in SLUP, SCP and HMI.
TECPRO SYSTEMS LTD
Page 74
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
33. Silo Fluidizing valve :a) Open/Close permissive:i)
Nil.
b) Actuations:i)
Open/Close Selector switches in SCP & HMI.
ii)
Automatically open when silo selected & any fluidizing blower on
iii) Automatically close when silo deselected or all fluidizing blower on
c) Indications:i)
Open status in SCP & HMI.
34. Silo Fluidizing Blower:a) On permissive:i) Fluidizing valve of any FA Silo opened.
b) Actuations :i)
Start, Stop push buttons in SCP & HMI.
c) Indications:i)
ON and OFF indications in SCP & HMI.
35. Silo Fluidizing Heater Bank-1:a) On permissive:i)
Corresponding fluidizing blower On and
ii)
Fluidizing heater discharge temperature low
b) Off Conditions:i)
Corresponding heater discharge temperature danger high.
TECPRO SYSTEMS LTD
Page 75
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
c) Actuations :i)
Auto on pulse with corresponding blower on permissive.
ii)
Auto off pulse with heater discharge temperature high or corresponding
blower off.
36. Silo Fluidizing Heater Bank-2:a) On permissive:i)
Corresponding fluidizing blower on and
ii)
Fluidizing heater discharge temperature low or corresponding heater
discharge temperature not high.
b) Off Conditions:i)
Corresponding heater discharge temperature danger high.
c) Actuations :i)
Auto on pulse with corresponding blower on permissive.
ii)
Auto off pulse with heater discharge temperature very high or
corresponding blower off.
37. Silo Fluidizing Heater Bank-3:a) On permissive:i)
Corresponding fluidizing blower on and
ii)
Fluidizing heater discharge temperature low or corresponding heater
discharge temperature not very high.
b) Actuations :i)
Auto on pulse with corresponding blower on permissive.
ii)
Auto off pulse with heater discharge temperature danger high or
corresponding blower off.
c) Indications:ii)
Heater on and off indication (any bank on/ off of corresponding heater) in
SCP and HMI.
TECPRO SYSTEMS LTD
Page 76
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
38. Wash Water Pump:a) On permissive:i) Over ground tank level not low.
b) Trip Conditions:i)
Over ground tank level Very low.
c) Actuations :i)
Start, Stop push buttons in SCP and HMI.
d) Indications:i)
On, Off indication in SCP and HMI.
39. Ash Conditioner Water Pump:a) On permissive:i)
Over ground tank level not low.
b) Trip Conditions:i)
Over ground tank level very low.
c) Actuations :i)
Start, Stop push buttons in SCP and HMI.
d) Indications:i)
On, off indication in SCP and HMI.
40. Silo Area Drain Pump:a) On permissive:i) Silo area drain sump level not low.
b) Trip Conditions:i)
Corresponding drain pump on and.
ii)
Corresponding drain pump seal water pressure not adequate.
TECPRO SYSTEMS LTD
Page 77
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
c) Actuations :i)
Auto on pulse with sump level high.
ii)
Auto off pulse with sump level low.
iii) On, off push buttons in SCP and HMI.
d) Indications:i)
On, off indication in SCP and HMI.
41. Silo Area Drain Pump Seal Water Valve:a) Open permissive:i) Any Wash water pump on.
b) Actuations :i)
Auto on pulse with silo area drain pump on.
ii)
Auto off pulse with silo area drain pump off.
iii) On, off push buttons in SCP and HMI.
c) Indications:ii)
Seal water pressure normal indication in SCP and HMI.
42. Silo Area Over Ground Water Tank Make up Valve:a) Open permissive: - NIL
b) Close Conditions:- :- NIL
c) Actuations:i)
Open/Close selector switch in SCP and HMI.
ii)
In Auto open, Silo area over ground tank level low.
iii) In Auto Close Silo area over ground tank level high..
d) Indications:i)
Open indication in SCP and HMI
TECPRO SYSTEMS LTD
Page 78
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
43. Silo Purging System:1. Open Permissive:i)
Silo selected.
ii)
Instrument Air Pressure Normal.
iii) Corresponding vent fan running..
2.
i.
ii.
iii.
Trip Conditions:Buffer Hopper not selected.
Instrument Air Pressure not Normal.
Corresponding Vacuum Pump not running..
3. Actuation:ii)
OPEN and CLOSE selector switch in HMI.
4.
iii)
Indications:OPEN and CLOSE indications in HMI.
Note: Purging system will operate sequentially within preset time (two purge
valve at a time for 0.5 sec after every interval of 30 sec). If differential
pressure is high, purging sequence time will be 0.5 sec after every interval of
15 sec.
24.
Telescopic Spout Purging System:1. Open Permissive:i)
Instrument Air Pressure Normal.
ii)
Corresponding Vent Fan running..
2. Trip Conditions:i.
Instrument Air Pressure not Normal.
ii.
Corresponding Vent Fan not running..
TECPRO SYSTEMS LTD
Page 79
MEJA THERMAL POWER PROJECT
STAGE-I, 2 X 660 MW
CONTROL WRITE – UP
NTPC DOC. NO. 0360-162-PVM-W-284
TSL DOC. NO. 576-80-06
3. Actuation:i)
OPEN and CLOSE selector switch in HMI.
4. Indications:i)
OPEN and CLOSE indications in HMI.
Note: Purging system will operate sequentially within preset time (two purge
valve at a time for 0.5 sec after every interval of 30 sec). If differential
pressure is high, purging sequence time will be 0.5 sec after every interval of
15 sec.
TECPRO SYSTEMS LTD
Page 80