NTPC, Simhadri, 4X500MW, Visakhapatnam, Andhra Pradesh
Unit
Capacity
Year of
Comml
Power Share
AP
TN
Kar
Ker
Pud
Unit-1
500 MW
Sep 2002
100%
X
X
X
X
Unit-2
500 MW
Mar 2003
100%
X
X
X
X
Unit-3
500 MW
Sep 2011
45.8%
22.8%
20.4%
9.2%
1.8%
Unit-4
500 MW
Sep 2012
45.8%
22.8%
20.4%
9.2%
1.8%
This region is suffering from power starvation...
“Customer demanded, we want power and we want it now.”
Generation Loss due to Coal Shortage
Gen Loss due to Coal Shortage (MU)
700.00
638.47
600.00
500.00
498.55
400.00
300.00
200.00
97.49
87.85
100.00
67.43
47.86
3.43
116.35
53.45
0
0.00
Station
51.03
62.41
51.166
Use of High Moisture Imported Coal at
NTPC, Simhadri, A Case Study
By
Chinnmoya Choudhury, ASCE,
R.K.Rout, HOD (OPERATION),
S.Narendra, GM (O&M)
Coal Supplying Mines (NTPC, Simhadri)
Indonesian (Hi GCV)
5800-6500 Kcal/Kg
Moisture-up to 20%
MCL (Talcher Mines)
2800-3400 Kcal/Kg
Moisture up to 10%
Coal
Supplying
Mines
Indonesian (Hi MO)
4500-5500 Kcal/Kg
Moisture-up to 35%
MCL (Ib Mines)
1800-3000 Kcal/Kg
Moisture up to 10%
SCCL (Singareni)
3000-4000 Kcal/Kg
Moisture up to 10%
Imported Coal Property Analysis
MINE
INDONESIA-1
INDONESIA-2
SAMPLE
IMPORTED HIGH GCV
IMPORTED HIGH MOISTURE
AS RECEIVED (ARB)
AS RECEIVED (ARB)
UP TO 20
UP TO 35
UP TO 20 (MAX)
UP TO 12 (MAX)
GCV (Kcal/kg)
5800-6500
4500-5500
SULPHUR (%)
UP TO 0.90 (MAX)
UP TO 0.70 (MAX)
SIZE (mm) *
UP TO 50
UP TO 50
FIXED CARBON (%)
35-50
25-45
VOLATILE MATTER (%)
25-45
25-45
HGI
45-60
45-60
1100-1250
1100-1250
BASIS
TOTAL MOISTURE (%)
ASH (%)
IDT Under Reducing Atmosphere (0C)
* SIZE OF THE COAL LESS THAN 2.36 mm SHALL NOT BE MORE THAN 25% OF THE QUANTITY AS RECEIVED AT THE POWER PLANT
Coal Consumption Pattern
Coal GCV (Kcal/Kg)
3700.00
3600.00
3500.00
3400.00
3300.00
3200.00
3100.00
3000.00
2900.00
2800.00
3629.38
3481.43
3538.82
3452.00
3490.88
3269.00
3348.00
3265.00
3291.00
3215.00
3142.74
Sp Coal (Kg/KWh)
0.749
0.760
0.735
0.740
0.720
0.700
0.713
0.700
0.680
0.719
0.680
0.680
0.682
0.660
0.640
0.620
0.600
0.650
0.725
0.701
Coal Pricing...
₹ 2,000.00
₹ 3,506.00
Coal Cost As Fired
Landed Coal Cost (Talcher)
Landed Coal Cost (Ib)
₹ 1,810.00
₹ 3,000.00
₹ 1,880.00
₹ 2,718.00
₹ 4,000.00
₹ 3,283.00
₹ 5,000.00
₹ 5,000.00
₹ 3,600.00
₹ 6,000.00
Landed Coal Cost (SCCL)
Landed Coal Cost (Hi GCV Imported)
Landed Coal Cost (Hi MO Imported)
₹ 1,000.00
E Procured Coal Cost (Talcher)
₹ 0.00
2012-13
Cost of Coal as Fired
₹ 2,900.00
₹ 2,718.00
₹ 2,700.00
₹ 2,500.00
₹ 2,300.00
₹ 2,100.00
₹ 2,093.00
₹ 1,917.00
₹ 2,043.00
₹ 1,900.00
₹ 1,700.00
₹ 1,500.00
2009-10
2010-11
2011-12
Landed Coal Cost (CAF)
2012-13
Precautions Taken...
Imported Coal mix to a Max of 10% and Bunkering in Mills A to F
Mill O/L temp at 70 0C
Mill I/L temp at 300 0C
Excess Air to maintain Eco O/L Oxygen at 3.0-3.5%
Close Observation of 10.5 Mtr. Peep Holes
Timely Bottom Deashing
Blending of Imported Coal only with MCL Coal (no SCCL Coal)
Methodology
• Case Study data from Unit-1
& Unit-2 Only.
• Data was Logged at
Load>450 MW.
• Main Study Period was OctDec 2012 (Hi MO Blend).
• Coal Blending was done by
Belt Blending .
• Blended Coal was bunkered
preferably in the Mills A-F.
• The Maximum Imported
Coal in the mix was limited
to 10% initially.
• Analysis for the study was
made for the financial year
of 2012-13*.
• In 2012-13, all types of Coal
(MCL-Talcher, MCL-Ib, SCCL,
Indonesia-Hi
GCV,
Indonesia-Hi
Moisture)
were fired in the Boilers of
NTPC Simhadri.
*Data for analysis was taken
up to Jan 2013.
Test Load Conditions
Test Load
514.2
500.0
510.1
505.6
509.8
491.2
484.0
489.6
496.0
490.6
485.3
450.0
400.0
350.0
300.0
Apr-12
May-12
Jun-12
Jul-12
Aug-12
U1 AVG LOAD
Sep-12
U2 AVG LOAD
Oct-12
Nov-12
Dec-12
Jan-13
Observed Parameters
Slagging and Fouling
Tendencies
Hot PA Temperature
Clinkering and Bottom Ash
Hopper Build-ups
Mill O/L Temperatures
Mill Reject Fires and Mill
Fires
Steam Parameters
Flue Gas Exit Temperature
SH & RH Sprays
Oxygen in the Flue-gas
ESP Hopper Evacuation
The Simhadri Experience
Slagging and Fouling
Regular observation of the furnace by operation staff and
Pressure Parts section confirmed ,
• slight soft slagging of the walls that would easily get removed
by regular Wall Blowing.
• Wall Blowing was being done periodically only (88 Blowers
operated per day).
• After 15 minutes of wall blowing activity, the performance of
the heating elements was becoming normal.
Slagging was soft and was not hampering the thermal
efficiency of heating elements.
Wall Blowing Trends (05-11-2012)
The Simhadri Experience
Clinkering
• In the months of Oct to Dec 2012, there was not even a single
reported case of Bottom Ash Hopper Build-up and Clinker
Grinder over-load i.e. clinkering, in all the running Units, at
NTPC, Simhadri.
Clinkering was not Observed while firing Indonesian
Imported Coal even at blending ratios of 30%.
The Simhadri Experience
Mill Reject Problems
• The average Mill Reject Problems encountered while using Hi
GCV Indonesian Coal with MCL Coal was 0.6 per day per unit.
• The average Mill Reject Problems for the period of Oct to
Dec 2012 came down to as low as 0.2 per day per unit when
Hi Moisture Imported Coal was blended with Indian MCL
Coal.
Mill Reject Problems were less and Boiler ‘0”mtr area
housekeeping was quite Improved.
The Simhadri Experience
FGET
160.0
155.4
155.0
150.0
145.0
151.6
147.6
152.0
150.6
147.9
144.1
140.0
150.9
150.3
145.9
144.6
139.3
135.0
140.3
137.6
144.4
139.4
135.7
133.5
130.0
129.5
132.6
125.0
120.0
Apr-12
May-12
Jun-12
Jul-12
Aug-12
U1 AVG FGET
Sep-12
Oct-12
Nov-12
Dec-12
Jan-13
U2 AVG FGET
FGET
• FGET got lowered to 129 0C in Unit-1 and to 145 0C in Unit-2.
• Lowering of FGET is due to low Flue-Gas Temperatures at Furnace.
Flue Gas Exit Temperatures got lowered. The FGET was more
than the allowed Cold End Corrossion Temp (125 0C)
The Simhadri Experience
Avg Oxygen
3.70
3.50
3.44
3.42
3.57
3.45
3.48
3.10
3.19
3.20
3.17
3.11
3.16
3.06
3.01
2.90
2.70
3.18
3.39
3.35
3.30
3.10
3.51
3.16
2.90
2.75
2.50
Apr-12
May-12
Jun-12
Jul-12
Aug-12
U1 AVG OXYGEN
Sep-12
Oct-12
Nov-12
Dec-12
Jan-13
U2 AVG OXYGEN
Oxygen at Eco Outlet
• While using the Hi moisture coal for blending, the oxygen (Total Air
Flow) was maintained at 3.0-3.5% to avoid the reaction inside the
furnace in reduced atmosphere.
The Eco O/L Oxygen % was maintained at > 3.0 % during OctDec 2012
The Simhadri Experience
Hot PA Temp
330.0
325.8
325.0
320.0
321.2
315.0
313.9
319.1
319.8
313.2
310.0
305.0
304.8
307.7
310.0
307.8
303.5
308.5
304.9
313.7
314.2
306.3
306.6
310.4
307.1
300.0
295.0
292.5
290.0
Apr-12
May-12
Jun-12
Jul-12
Aug-12
U1 AVG HOT PA TEMP
Sep-12
Oct-12
Nov-12
Dec-12
Jan-13
U2 AVG HOT PA TEMP
Hot PA Temp
• The Hot PA temperature in both Unit-1 and Unit-2 was more or less
stable.
• The marginal increasing in Unit-2 may be due to certain degree of
fouling caused due to prolonged operation and nearing O/H.
The Hi Moisture Coal has made PA Header Temperatures
Stable.
The Simhadri Experience
Mill O/L Temp
85.0
80.0
78.0
77.5
75.0
70.0
73.6
74.7
80.0
77.8
76.3
76.0
76.1
77.4
76.1
76.5
73.9
67.4
65.0
66.2
60.0
66.2
66.8
67.1
73.0
65.7
55.0
50.0
Apr-12
May-12
Jun-12
Jul-12
Aug-12
U1 AVG MILL O/L TEMP
Sep-12
Oct-12
Nov-12
Dec-12
Jan-13
U2 AVG MILL O/L TEMP
Mill O/L Temperatures
• The Mill Outlet Temperatures were low even with Cold Air Gates closed .
• During backing down/Part Load regimes , Mill O/L temps came down to
about 60-62 0C.
• 7th Mill Operation was maintained even when 6th Mill would be sufficient.
The main concern in running units with the high moisture
Indonesian Coal is its adverse effect on the Mill O/L
temperatures.
The Simhadri Experience
Steam Temperatures
540.0
535.0
530.0
525.0
525.8
527.9
527.1
520.0
526.0
528.1
527.3
526.3
516.0
515.0
517.2
517.9
Nov-12
Dec-12
510.0
Apr-12
May-12
Jun-12
U1 AVG MS Temp
Jul-12
Aug-12
U1 AVG HRH TEMP
Sep-12
Oct-12
U2 AVG MS Temp
Jan-13
U2 AVG HRH TEMP
Steam Parameters
• The average SH temp change was marginal in both the Units.
• The HRH temperature in Unit-1 dropped considerably due to high heat
recovery in WW. The HRH temp drop in unit-2 was marginal and
insignificant.
SH temperatures were stable. HRH temperatures were
slightly lowered due to lower FG temperatures.
The Simhadri Experience
Sprays
60.0
55.0
50.0
45.0
45.2
40.0
35.0
30.0
25.0
28.1
27.9
31.2
26.8
34.6
31.2
32.3
29.9
37.9
34.9
38.1
37.8
34.3
29.9
33.1
32.9
28.3
31.6
28.1
20.0
Apr-12
May-12
Jun-12
Jul-12
Aug-12
U1 AVG SH SPRAY
Sep-12
Oct-12
Nov-12
Dec-12
Jan-13
U2 AVG SH SPRAY
SH Sprays
• In Unit-1, the SH spray is on the rise (Due to high heat gain in water
wall and SH circuits in a cleaned Overhauled Furnace).
• In Unit-2, The SH Spray is Stable (slight reduction observed).
SH Sprays are Slightly Reduced as the FG temperatures
are lower at Furnace.
The Simhadri Experience
Sprays
60.0
57.6
56.8
55.0
50.0
45.0
40.0
56.2
55.9
55.7
55.5
51.9
46.7
45.4
44.6
42.4
40.5
35.0
39.2
40.9
38.3
40.4
44.5
39.5
32.0
30.0
25.3
25.0
20.0
Apr-12
May-12
Jun-12
Jul-12
Aug-12
U1 AVG RH SPRAY
Sep-12
Oct-12
Nov-12
Dec-12
Jan-13
U2 AVG RH SPRAY
RH Sprays
• The RH Spray in Unit-1 was inconsistent and was dependant on the
RH Acromat and Metal Temperatures.
• In Unit-2, the RH Spray was steadily increasing.
RH Sprays are on the rising trend which may be due to
certain degree of Secondary Combustion.
The Simhadri Experience
Opacity
120.0
100.0
95.9
80.4
80.0
60.0
64.0
99.7
92.4
69.0
93.7
92.0
82.8
91.8
84.3
65.7
77.7
66.5
47.2
62.7
40.0
44.8
44.6
Oct-12
Nov-12
43.5
40.3
20.0
0.0
Apr-12
May-12
Jun-12
Jul-12
Aug-12
U1 AVG OPACITY
Sep-12
Dec-12
Jan-13
U2 AVG OPACITY
ESP Evacuation
• Opacity in both the units is in the downward trend.
• The ESP performance has improved considerably and more ash was
getting evacuated.
ESP Performance was Good with the use of Hi MO
Indonesian Coal.
The Simhadri Experience
Coal Flow (TPH)
400.0
390.0
380.0
370.0
360.0
350.0
340.0
330.0
320.0
376.7
378.2
382.3
377.5
371.3
370.1
366.2
384.1
372.8
359.5
354.9
354.0
May-12
Jun-12
Jul-12
Aug-12
U1 AVG COAL
358.8
346.4
348.7
344.3
Apr-12
362.5
354.5
338.0
334.1
Sep-12
Oct-12
Nov-12
Dec-12
Jan-13
U2 AVG COAL
Sp Coal
0.820
0.800
0.780
0.760
0.740
0.720
0.700
0.680
0.660
0.640
0.620
0.801
0.787
0.745
0.758
0.732
0.762
0.725
0.760
0.733
0.721
0.703
0.728
May-12
0.705
0.725
0.688
0.689
Apr-12
0.724
Jun-12
Jul-12
Aug-12
U1 AVG SP COAL
Sep-12
Oct-12
U2 AVG SP COAL
0.703
Nov-12
0.695
Dec-12
0.689
Jan-13
The Simhadri Experience
Coal Consumption
Considerable reduction in coal flow for generating 500 MW
has multiple good effects.
• This causes less grinding requirement at the Mills,
• Less work-load at CHP and lesser work load at ESP and
• Less work-Load at the bottom ash.
Reduction in Sp. Coal has generated less ash and made ESP more
efficient. The Opacity was less and the stack emissions were
lessened.
Conclusion
Conclusion
The other Boiler Performance parameters like
Slagging, Foulling, have very marginal effects.
The Coal is priced low (Rs. 3600) and has a steady
Heating Value (4500 Kcal/Kg). This gives a lot of
stability in fuel security and Control over Cost of
Generation.
Mill Reject area problems are nullified with this
type of coal.
Mill Outlet Temperature is a concern, but it is being
controlled by suitable monitoring of the milling
system by the Operating Staff.
“The High Moisture Indonesian Coal has Edge over the
SCCL Coal and the High GCV Indonesian Coal.”
The Combustion Characteristics of this Grade of Coal
may be studied in detail for any long term effects on
the Boiler Performance and Life.
The High Moisture Indonesian Coal is found
to be suitable for use in BHEL make 500 MW
CE design Corner Fired boilers, while mixed
with the available Indian Sub-Bituminous Low
Grade Coal, up to 30% ratio.
This meticulous study has given a lot of
confidence to the entire thermal power
producers in the country to use the High
Grade High Moisture Imported Coal in the
existing Boilers.
Coal is
Still King