POWER UTILITY
The power and utility area consists of equipments, their potential outputs and general condition.
Boilers (8):
All boiler supply steam to a common 875 psi header at 825°F
No.1 Power:
Design maximum steam flow 200,000 #/hr
Fuel: Sludge, Bark, TDF and natural gas
General condition of this boiler is good. The primary super heater section
is an exception and was scheduled for partial replacement in year 2001.
The ID fan rotor was replaced in 2000.
No.2 Power:
This boiler was dry fired and severely damaged. It is not considered
repairable.
No.2A Package:
Design steam flow 165,000 #/hr
Fuel: Natural Gas General Condition: Fair
This boiler is need of super heater repairs. 50% of super heater tubes were
scheduled for replacement in 2000. The generator wall tubes in this boiler
do not have vibration bars and stress related cracking is suspected to be
present (no failures in this area to date)
No.2B Package:
Design steam flow 165,000 #/hr
Fuel: Natural Gas General Condition: Very Good
This boiler received a major overhaul in 1999 which included generator
wall tube replacement and vibration bars to prevent stress related cracking.
This boiler, like its twin 2A, is difficult to properly warm up and bring into
service due to the lack of a startup burner and an oversized main burner
for starting purposes.
No.2C Package:
Design steam flow 165,000 #/hr
Fuel: Natural Gas General Condition: Excellent
This is a new boiler that went into operation in 1999 to replace the No.2
power boiler.
No.1 Waste Heat:
Design steam flow 65,000 #/hr
Heat Source: #2 Gas Turbine Generator Exhaust
This unit is not operational and requires a major overhaul before returning
to service. It will also require retrofit of steam injection for NOx control
No.2 Waste Heat:
Design steam flow 65,000 #/hr
Heat Source: #3 Gas Turbine Generator Exhaust
This boiler was found to be in good condition following the inspection /
overhaul of the gas turbine generator / waste heat boiler unit in 1999.
Recovery Boiler:
Designed to process 2.1 MM # dry solids/day and generate 250,000 #/hr
steam
Primary Fuel: Black Liquor Secondary Fuel: Natural Gas
This boiler is in poor condition overall. The integrity of the furnace and
other pressure parts are in fair condition. The duct work, cascade
evaporators and precipitator are in extremely poor condition. Five of the
twenty two pendants in the intermediate super heater section have been
removed following tube failures in the past several years. ABB conducted
a study of the boiler capabilities considering the super heater issue and
concluded that the maximum steam output be limited to 200,000 #/hr. This
equates to a 1.8 MM dry solids/day firing rate. The recovery boiler was
last fired in 2000 and is no longer considered an operational unit.
Black Liquor Evaporators:
Design is 1200 gpm, however they are limited to 900 gpm due to
all internal body heaters being bypassed. General condition is fair.
These units were last operated in 2000.
Turbine Generators (4)
No.1 Steam Turbine (General Electric):
Rated 25,000 KW, will operate at 30 MW
Single 65# extraction with condensing exhaust.
General condition: Good. Due for major overhaul in
2001. Mark II EHC is obsolete.
No.4 Steam Turbine (Westinghouse):
Rated 30,000 KW, will operate at 40 MW
Single 65# extraction with condensing exhaust.
General condition: Fair. Scheduled for major
overhaul in 2000.
No.2 Gas Turbine:
Rated 16,000 KW, not operational
No.3 Gas Turbine:
Rated 16,000 KW, limited to approximately
14.5 MW due to NOx emissions. This unit is not
equipped with steam injection for NOx control. This
unit was overhauled in 1999 and is in good
condition.
15 KV Electrical Distribution System
This system consists of original main bus and feeders, plus add-ons that have taken place in past
several years during expansion projects. The system is in fair condition but is not user friendly
and presents risk when bring the public utility on and off the Mill system. Maintaining designed
system voltages across the four buses could not be accomplished primarily due to transformer
taps being frozen in place. A study of entire electrical systems needs to be done in order to
provide for a reliable and efficient operation.
Boiler Feed Water System
Demineralizers:
Consists of three cation and three anion units. The units are rated in 600
gpm each. The system is in good condition with new resin in all units. All
vessel rubber liners were inspected and repaired in 1999.
Deaerator:
Consists of two heaters with one storage vessel. The system is rated at 1.2
million pounds per hour. The system is in good condition.
Feed Water Pumps:
Consists of four 750 gpm pumps. Three pumps are steam turbine driven
and one electric. All four are in very good condition.
Water Supply
Seven wells at site are capable of providing 20 million gallons/day but are limited to 10% of the
total mill usage by governmental regulation. All are in good condition. The surface water
treatment plant is capable of providing 20 mgd. The city provides lake water to surface water
treatment plant. Equipment consists of a lift station, two clarifiers, eight multimedia filters,
associated pumps and a three million gallon storage tank. The filter media was replaced in 2000.
There are two sludge ponds.
Wastewater Treatment
Hydraulic capacity approximately 18 mgd. Consists of two primary clarifiers, three aeration
basins, two secondary clarifiers, and a lift station to move effluent water through pipe to
discharge at a long distance. The system is in good condition.
Sludge Dewatering Plant
Capable of dewatering up to 225 bone dry tons (BDT) per day of fuel to #1 power boiler. The
system was upgraded to 345 BDT/day. The system includes screw presses, pre-thickening
devices and associated tanks and pumps.
Compressed Air System
The system consists of five rotary compressors with a total output of 9840 cfm. Equipment
consists of two Sullair rated at 1520 cfm each, one Sullair rated at 1800 cfm, two Centex rated at
2500 cfm each. All are in good condition with two being rebuilt in 1999.
Instrument Air Dryers:
Three sets. All required new desiccant in 2000.
Condition: Fair to Good
DEINK PLANT MAJOR PROCESS EQUIPMENT
Warehouse
Bale Dewiring:
One (1) Lamb Mark 5 / 150-08-D Bale Dewiring Machines.
Rated at 90 bales/hr each. Installed in 2000.
Bale Dewiring Conveyor: Nielson & Hiebert 7”-10” x 182’-2”
Rated at 30 FPM, 2592 ODSTPD. Installed in 2000.
Pulper Feeder:
Newsprint Conveyor: Grace Metal Slat Conveyor Rated at 11950
ODSTPD. Installed in 1992
Magazine Conveyor: Grace Metal Slat Conveyor Rated at 211 ODSTPD.
Installed in 1992
Drum Pulper Feeder Conveyor: Nielson & Hiebert 96” x 116.11’
Rated at 30 FPM, 1406 ODSTPD. Installed in 2000.
Deinking Plant
Pulping:
Ahlstrom Drum Pulper – Fiberflow 425 extended
Rated at 1700 ADSTPD. Installed in 2000.
HD Cleaners:
Three (3) BIR 1200 HDC 12” Cleaners
Rated at 1044 GPM @ 3.43% cons. Installed in 1992.
Seven (7) Mill Fabricated 12” Cleaners
Rated at 1079 GPM @ 3.43% cons. Installed in 2000.
Coarse Screening:
Two (2) Thermo Black Clawson Fiberprep CH7 Screens
Rated at 2532 GPM feed @ 3.31% cons. Installed in 1992.
One (1) Thermo Black Clawson Fiberprep CH7 Screen
Rated at 2532 GPM feed @ 3.31% cons. Installed in 2000.
One (1) Thermo Black Clawson Fiberprep CH5 Screen
Rated at 1119 GPM feed @ 3.64% cons. Installed in 1992.
Four (4) Thermo Black Clawson Fiberprep CH3 Screens
Rated at 979 GPM feed @ 3.31% cons. Installed in 1992.
One (1) Thermo Black Clawson Diablo 2 Screen
Rated at 280 GPM feed @ 2.97% cons. Installed in 1992.
One (1) Thermo Black Clawson Diablo 3 Screen
Installed in 1992.
Floatation:
Two (2) Flotation Mixing Cells – Voith Sulzer 1.5 Meter Cells
Rated at 3859 GPM @ 1.18% cons. Installed in 1992
Fourteen (14) Primary Flotation Cells – Voith Sulzer 3 Meter Cells
Rated at 4266 GPM @ 1.18% cons. Installed in 1992
Four (4) Secondary Flotation Cells – Voith Sulzer 2 Meter Cells
Rated at 2650 GPM Installed in 1992
One (1) Flotation Mixing Cell – Voith Sulzer ECC6/44
Rated at 20000 GPM Installed in 2000
Six (6) Primary Flotation Cells – Voith Sulzer ECC6/44
Rated at 12700 GPM Installed in 2000
Two (2) Secondary Flotation Cells – Voith Sulzer ECC6/44
Rated at 5200 GPM Installed in 2000
Forward Cleaners:
Five (5) Banks of Alshtrom Cleaners 144, 4 Rows, RB45, SPU
Rated at 6298 GPM @ 0.9151% cons each. Installed in 2000
Four (4) Banks of Beloit PB50 Cleaners – 48 Cleaners per Bank
Rated at 2017 GPM @ 0.8% cons per bank. Installed in 1992
Two (2) Banks of Beloit PB20 Cleaners – 20 Cleaners per Bank
Rated at 586 GPM @ 0.6% cons per bank. Installed in 1992
One (1) Banks of Beloit PB10 Cleaner – 10 Cleaners per Bank
Rated at 193 GPM @ 0.375% cons per bank. Installed in 1992
Fine Screens:
Five (5) Voith Sulzer Screens – VPS 40/16
Rated at 6300 GPM @ 0.9% cons. Installed in 2000
Two (2) Thermo Black Clawson Screens – Fiberprep SPM-1500
Rated at 2780 GPM @ 0.75% cons. Installed in 1992
One (1) Thermo Black Clawson Screens – Fiberprep SPM-800
Rated at 1314 GPM @ 0.685% cons. Installed in 1992
One (1) Thermo Black Clawson Screens – Fiberprep SPM-400
Rated at 308 GPM @ 0.68% cons. Installed in 1992
Disk Filters:
Two (2) Celleco Disk Filters – 4 MLW-18
Rated at 48376 GPM @ 0.77% cons. Installed in 1992
One (1) Kvaerner Disk Filters– DF-520X28/30 MLW-18
Rated at 940 ODSTPD Installed in 2000
Screw Presses:
Three (3) Hymac Presses – SP-70SL
Rated at 150 ODSTPD Installed in 1992
Five (5) Kvaerner Presses – SP-70SL / HHC 5-38RPM
Rated at 210 ODSTPD Installed in 2000
Note: One (1) SP-70SL / HHC was transferred to AR in 2005
(4 on hand now)
Stock Conveyors:
One (1) Collection Conveyor – Nielson & Heibert 42” x 89’
CC / HLOA Rated at 170 T/hr @ 200 FPM Installed in 2000
One (1) Transfer Conveyor – Nielson & Heibert 42” x 77’-2”
HLOA Rated at 170 T/hr @ 200 FPM Installed in 2000
One (1) Stock Conveyor – Continental Conveyor Curved Belt
42” x 1900’ Rated at 170 T/hr @ 300 FPM Installed in 2000
Idled Equipment Available for Sale: Two( 2) High Consistency Hydra Pulpers
Voith – HD40 with Hansen RVK24S 9.9375:1 Ratio
Gearbox and 900HP, 4160V, 1200RPM Motor. Rated at
260 BDSTPD @ 12% Consistency based on application.
Idled in 2000
Two (2) Contaminex – Voith CMS 30 with 120 HP Motor
to be used with Voith Hydra Pulpers. Idled in 2000
Seven (7) Cleaner Banks – Two (2) Beloit UB 20, One (1)
Beloit UB 30 and Four (4) Beloit UB 40 High Flow
UniFlow Cleaner Banks. Removed in 2000
Two (2) Disperger Systems – Suzler – Escher Wyss
HD3 with 900HP, 4160V, 1200RPM Motors, Heating
Screws, etc. Built in 1991
MAJOR EQUIPMENT ASSETS
Wood Handling & Preparation
Major Components have been out of service for approximately 5 years
1.
2.
3.
4.
Log Handling:
Chip/Bark Handling:
DeBarkers:
Bark Hogs:
Chain Conveyors
Belt Conveyors
Two (2) 12’ x 67.5’ FPM Drum, Two sections gone
Jeffery Bark Hogs
5.
6.
7.
Wood Chipping:
Rechipper:
Chip Screens:
One (1) 104” – 15 Knife Murray Chipper
One (1) 40” – 6 Knife Arcowood
One (1) # 812 Black Clawson – Two (2) Rotex Chip
Screens
Pulp Mill
Major Components have been out of service for approximately 5 years
1.
2.
3.
4.
5.
Kraft Avg. Daily Production Capability; Bleached SWD; 575 Tons Un Bleached and
Semi Bleached
Continuous Digester:
Kamyr
Ground Wood, Stone Avg. Daily Production Un-Bleached SWD; 500 Tons
Grinders: 10 Great Northern Waterous
Ground Wood Refined: 450 Tons
TMP Plant
Major Components have been out of service for approximately 4 years
1.
Sunds Defiberator Refiners: Two (2) RLP58S, 12000 HP Primary
Two (2) R158S, 12000 HP Secondary
One (1) RLP58S, 12000 HP Rejects
Flotation DeInking Facility
Major Components have been out of service for approximately 2 years
Maximum production capacity is 1700 Tons per day
Bleach Plant
Sequence, Kraft; C-E-H, Towers; 1 UpFlow, 2 DownFlow; 500 Tons per day
Major Components have been out of service for approximately 5 years
Pulp Processing
Drainers: Kraft Mill:
Major Components have been out of service for approximately 5 years
1.
2.
3.
4.
5.
6.
7.
Screens: 3 Primary, 2 Secondary, 1 Reject Hymac
Cleaners: 1 - 20’ Magna Cleaners
Washers: 1 – Impco CV Brown Stock, 3 – Dorr Oliver Vacuum Bleached
Stock
Deckers: 1 – Impco Vacuum
Drainers: GWD Mill – 2 Hymac, 2 Thune Presses
Screens: 9 – Impco Vibratory, 11 – Hymac
Cleaners: 5 – 36” Magna Cleaners, 1- Two Stage , Twenty Body Bauer
Steam
PROCESS DESCRIPTION / FLOW DIAGRAM
DEINK PROCESS
The deink mill was initially installed and run in 1993 at a production rate of approx 300 TPD.
Many expansion projects occurred between 1995 until 2001 to replace the pulp production
capacity after the shutdown of Kraft, Groundwood and TMP mills. Total production of the plant
at full operation by design is 1700 TPD. Modifications to the Deink mill from to expansion
projects included changing from the batch pulpers and trash screens to a continuous drum pulper
and trash screens. Other changes included modifications to the high-density cleaners and coarse
screens before the floatation cells, and removal of the reverse screens after the floatation cells.
The pulping chemistry was changed to neutral pH, and the screw presses were located after the
disc filters in the process.
The paper arrives at deink plant by truck and rail. It comes in bales and loose shipments. Old
newspapers known as ONP, and old magazines known as OMG are shipped and are stored
separately so that they may be metered for the deink process. Operators place the paper for the
pulpers on the proper conveyor. As the paper goes to the top its respective conveyor, it passes
through a weighing device, which determines how much paper is being fed to the pulper.
During pulping, water, chemicals, ONP and OMG are all added to the pulper. These work to
hydrolyze the fiber and also separate ink and filler from the mixture. The system continuously
feeds into the drum pulper the desired quantities of hydrogen peroxide, sodium silicate, DTPA
(chelant) and surfactant along with hot water and paper. As the paper travels through the drum,
the mechanical rubbing brought about by the rotation breaks down the paper into pulp. The
chemicals and water help the paper to disintegrate for removal of ink from the fibers. The end
section of the pulper has a screen and shower nozzles and wash the pulp from the drum. As the
pulp is flushed from the drum, the contaminants roll to the end and are discharged to the ground.
The pulp is pumped from the pulper to coarse screen feed chest. From the chest, pulp is fed to
high density cleaners in to banks. The high density cleaners remove large material that is heavier
than water. These contaminants include rocks, glass, nuts, bolts, etc. From the high density
cleaners the stock passes through two banks of centrifugal coarse screens with holes that remove
additional rejects from the stock. Rejects from the quaternary screen are discharged to a sand
separator and are subsequently land filled.
After removal of large contaminants, the pulp enters the floatation system for ink removal. The
stock is diluted to a 1.25% consistency after the floatation feed chest before it enters the
floatation mixing cell chamber. There are three lines of floatation with two stages each, the
primary stage and the secondary stage. In each cell, air is drawn in and thoroughly mixed with
the pulp. The ink attaches to the air bubbles and is turned into inky foam which is skimmed off.
The accepted pulp exits the bottom of first cell and moves to the second cell to repeat the process
through all seven cells on A and B line and six cells on C line. The accepted pulp from the
primary floatation stage is discharged into a deareation chest to be further processed. The inky
foam discharges into a weir and onto the secondary system. The secondary floatation stage
which operate like the primary stage, recovers acceptable fiber from the inky foam. The inky
foam rejected from the secondary stage goes into the sludge tank. The accepted pulp returns into
the floatation cells for additional cleaning.
The accepted pulp after being deinked in the floatation system must now be cleaned. The stock is
pumped to the forward cleaners. The forward cleaners perform under the same principles as the
high density cleaners, only at much lower consistency. There are four stages in forward cleaners
to remove additional contaminants and ink heavier than water. The accepted pulp enters the fine
screen feed chest and the rejects go to the sludge tank. The fine screen also contains four stages
and removes all but the smallest of particles. The accepted pulp from the fine screens is sent to
the disc filters and the rejects are sent to the sludge tank. The pulp sent to disc filters is
dewatered to a 12% to 15% consistency using vacuum. From the disc filters the pulp is conveyed
and pumped to the screw press feed chest. Screw presses remove the water from the stock by
squeezing it at high pressure. The stock exits the press at approximately 30% consistency. The
removed water is reused in the pulping process.
PAPER PROCESS
The process for the paper machines begins with stock preparation. The stock preparation process
is to bleach the mechanical and deink pulps with sodium hydrosulfite to improve brightness, and
meter these pulps together with bleached Kraft. The pulps are mixed together in blend chests that
are agitated, and then diluted with recycled water to slurry of 99% water and 1% fiber. After
blending the stock is de-aerated, screened to remove contaminants not removed in the pulping
process, dyed, pH controlled, and heated. At this time, the pulp is ready for paper machines.
The paper machine complex consists of three twin wire paper machines. All three paper
machines make a newspaper grade made from pulp manufactured in the mills for pulping
processes. The pulp furnishes vary with the grade of paper that is being manufactured. In the wet
end of the paper machine, the mixed pulp is sprayed from the head box between two moving
wire screens. Water is removed from the pulp with vacuum pumps which create a pressure
differential between the stock and the screen. After passing between the wire screens, the stock
begins to form a paper sheet which passes through the press section of the machines. Water is
squeezed out of the sheet while moving between several rollers. The sheet then enters the dryer
section where the water is removed by evaporation. In the dryer section, the sheet moves along a
series of rolls called the calendar stack. The calendar stack is designed to remove the wrinkles
and smooth the sheet. The sheet is then collected on a reel and then cut to customer
specifications. Through the paper machine process, the pulp is dewatered and dried from a 99%
consistency to about a 4% consistency as finished paper. A large portion of the water that is
dewatered from the pulp is recycled and reused in the paper making process.
POWER SYSTEM
The power and utilities department plays a key role in the manufacturing of newsprint. It
supplies four services to the mill: electricity, steam, air and water. The water is supplied to the
mill as surface water from a nearby lake and from seven wells located on the mill site. Chlorine
gas, used as Biocide, Alum and Polymer are added to the raw water as it enters the surface water
treatment plant. The water used to make steam in the boilers at the mill must be treated before its
use. Demineralizing is the process which removes minerals in order to prevent scaling on boiler
tubes. This is a critical concern on any boiler operation. There are six boilers in the power and
utilities area that produce 875 psi steam. The No.1 power boiler is a negative draft type boiler
with a fluidized sand bed. This boiler is fueled form the bark from the woodyard, sludge from the
waste water treatment plant, and tire derived fuel (or scrap tire chips) which can be supplemented
with natural gas. It produces 200,000 pounds of steam per hour. There are also 2A, 2B and 2C
package boilers which are fired by natural gas and can each produce 165,000 pounds of steam
per hour. The last two boilers are the No.1 and No.2 waste heat boilers. The exhaust heat
produced in No.1 and No.2 gas turbines can be used to generate steam in the waste heat boilers.
These boilers can each produce 70,000 pounds of steam per hour which is an efficient use of mill
resources.
WASTEWATER TREATMENT
The purpose of the wastewater treatment plant is to eliminate pollutants from the water so it can
be safely discharged. The mill uses an activated sludge process to remove these pollutants. The
main sewer carries wastewater generated at the mill into the division structure. The process
sewer at the deink plant also joins at this point. The influent is divided into two primary
clarifiers. Sludge is removed from the bottom of the clarifiers and pumped to the surge tank.
From the clarifiers, the overflow goes onto the chemical feed box where nutrients in the form of
ammonia and phosphoric acid are supplemented. Defoamer is also fed on as needed basis. From
the box, the effluent goes through the aeration basins which are equipped with mechanical
surface aerators. The effluent enters two secondary clarifiers for final clarification before it is
discharged to the outfall. A portion of the biological sludge that settles at the secondary clarifiers
is recycled back to the aeration basins to maintain the microbial population.
From the surge tank, sludge is pumped to the sludge plant for dewatering. A portion of the deink
sludge is directly pumped from the deink plant to the sludge plant. Sludge is combined kept
agitated in the mix tanks. Polymer and Alum are added to the sludge for conditioning. Sludge is
pumped to flock tanks which feed the gravity belt thickeners (GBT’s). From the GBT’s the
sludge goes into the screw presses where any remaining water is extracted to achieve
approximately 50% dryness. Sludge emerging from the screw presses is transported to the No.1
power boiler by a conveyor. The derived fuel is also deposited on this conveyor to be burned in
the boiler as supplemental fuel.
FINISHING AND SHIPPING
Once the paper sheet has been manufactured, the rolls are processed and stored in the finishing
area prior to be shipped out to the customer. After the rolls are cut to the size on the winder, they
are conveyed by a series of automatic elevators, conveyors, ramps, kickers, cushion stops and
turntables, to the roll wrap area. After the rolls are inspected, a protective wrap is placed on
them, inside protective heads are inserted, and the roll ends are crimped. The roll ends are then
glued in preparation of protective outside head application, using heat, the heads are sealed to the
ends of the roll.
After the rolls leave finishing, they enter the shipping area on one of the two conveyor belts. The
rolls are checked for proper identification numbers, size and weight and marked for rail, truck or
warehouse storage for later shipments. The storage for paper at the mill is for 5,000 tons of
paper. At the time of loading, the rolls are secured with air bags, wood supports or metal
banding. Once a load is completed, the shipment is checked for correct roll and weight count.