Publication: PULP & PAPER MAGAZINE
Weyerhaeuser Invests $105 Million to Expand Valliant Linerboard MillBy KELLY H. FERGUSON, Deputy Editor
Oklahoma facility increases production with new 500-tpd OCC recycling line, reworked stock preparation system, and rebuilt No. 1 linerboard machine
Weyerhaeuser Paper Co. recently started up a $105 million expansion at its Containerboard Packaging
Div. in Valliant, Okla., that has increased the containerboard mill's use of recycled fiber and has enhanced its linerboard properties to better meet changes in Rule 41/Item 222. The project included a new 500-tpd old corrugated container (OCC) recycling line, a reworked and expanded stock preparation system, and a rebuild of the mill's No. 1 paper machine.
Mike Citty, vice president and mill manager of the Valliant facility, said the expansion and rebuild was driven by three major factors. "The first was to get a higher ring crush to meet Rule 41 requirements. The second was production, and by the time we reach the end of the startup curve, we will have increased production by about 500 tpd.
"The third driver was to use more OCC. We fibered the entire production increase with secondary fiber. We were already producing about 400 tpd of OCC in the original line, and we've increased capacity by another 500 tpd by adding the new line."
No. 1 paper machine produces two-ply linerboard in weights of 42-lb and higher, although the mill has made some runs of high-performance 35-lb The furnish, following the expansion and startup curve, is expected to be 38% OCC/62% virgin softwood kraft pulp. The mill also produces lightweight kraft linerboard on its No. 3 machine and corrugating medium on its No. 2 machine.
Citty said Weyerhaeuser studied the project extensively and decided early in the planning stages to use an engineering, procurement, and construction (EPC) type contract. The company chose BE&K to handle the project, but Citty said mill personnel were also highly involved.
"We had heavy involvement from the people in this mill--both hourly and salaried--from conception of the project. We pulled the various engineering support groups, operations, and maintenance employees off their regular jobs to work on the project," Citty said. "The employees around them filled in, tightened their belts, and helped make the project work, so ownership of the project was there."
Bob Williford, BE&K's senior project manager on the Valliant project, said the mill's efforts toward "partnering" the project made a tremendous difference in success. "An agreement was made between Weyerhaeuser and BE&K on how the project was going to be structured, initially defining the scope," Williford said. "Then, as major suppliers were chosen, each became an integral part of the project and participated in everything from monthly sponsor meetings to reviews of their quality programs."
During the delivery phase, major suppliers were asked to participate in the inspection of their own equipment at the job site. Then, during the installation and startup, all major suppliers were present to ensure that their specifications and performance goals were achieved.
"By doing that, I think we developed a partnering arrangement where all the contributors to the project had an open discussion about potential problems and commitment to certain goals," Williford said. "It opened up the communication lines between the various participants to identify problems and solve them, rather than pointing out blame."
A small crew of Weyerhaeuser corporate engineers participated in the expansion, but Citty said the decision was made early on that "if we hired a consultant engineering firm, we were going to live with them. Their obligation was to engineer and purchase the equipment as our agent and handle construction. We weren't going to re-engineer everything they did. The project worked very well from that standpoint."
Citty said the initial bid evaluation included general points that most bids are based on, such as financials. But one of the paramount points for all engineers, construction firms, and suppliers was their safety record.
"When we began asking some of the suppliers to send in their safety performance for the past few years, they had a lot of confusion about what we were asking for," Citty said. "Some of them thought we were asking about their safety in the field, but we wanted to know how many accidents they had in their shop.
"We let equipment suppliers know they would not be eligible for bidding if they had a bad safety performance in their own plants. Our idea was that if they perform safely there, they will perform safely in the field and provide a good product or service."
The mill's project team and BE&K did a lot of research to decide on the major pieces of equipment, including Voith to supply the OCC pulper system, Black Clawson to provide recycled line screening and cleaning systems, and Beloit to provide major paper machine components. A 35-day shutdown was scheduled for August and September 1992 to perform most of the work, but much was done prior to the shutdown.
"We did a good bit of the work on the run," Citty said, "including mounting one of the Bel Bond units (top-wire formers). However, we did not compromise safety. If it was something that could be done in a totally safe manner and everyone was comfortable with the situation, we'd do it on the fly."
The project was completed almost exactly within the specified time. The OCC plant had already started up about three months prior to the shutdown and was supplying furnish to the other machines. The new winder was also operational prior to a sheet coming off the machine. The mill had planned an aggressive startup curve, and, according to Citty, the machine was making saleable product 26 hours after the sheet initially hit the reel on Sept. 21.
"We didn't have a lot of things to go back down for, even though we had allowed for some downtime in the startup curve," he said. "The last four or five days of the shutdown, we were trying to bring systems up and run water and fiber on the machine, which meant some long hours. But once we reached the point where we were prepared, the actual startup went fairly quickly.
"We had a lot of discussion with our operating crews prior to actual startup about the tenseness of the situation--about not overreacting or panicking. I told them, 'When you see me start to panic, you can panic, but only after you tell me to settle down.'
"Training made a big difference in that situation. The project team put together an excellent training program for the operators and maintenance employees, so I think everyone was prepared and committed to making the startup work."
To handle the increased OCC capacity, the Valliant mill relied on Weyerhaeuser's Recycled Fiber Div. sites around Oklahoma City and Dallas, Texas. The mill also uses about 50 to 100 tpd of double-lined kraft (DLK) clippings from box plants.
The mill's existing OCC bale storage warehouse was left virtually unchanged. It provides 8.4 days of baled waste storage, based on 1,460-lb high-density bales. Some modifications were made to the warehouse to make unloading easier, especially for handling of truck traffic. Also, three new Caterpillar clamp trucks were added to handle the additional bales.
Baled OCC is dewired manually and transported on an apron-style conveyor to the new Voith pulper. The conveyor has a 25-ft loading section and was designed for a maximum incline angle of 20´ to ensure transport of the dewired OCC bales to the pulper.
The pulper is a 70-m3 horizontal unit, including a ´-in.-thick 304L stainless steel tank. The pulper consists of a 58-in.-dia 316 stainless steel rotor with six stellite hard-surfaced vanes. The rotor operates at 237 rpm over an extraction plate with ´-in.-dia holes and is driven by an 800-hp, 900-rpm motor and belt drive. Included with the pulper is a junk trap with two cylinder-operated Loshe-type shutoff valves for connecting to a detrashing screen. The pulper tub has an integral ragger tube for proper rag rope alignment within the tub vortex. A pinch ragger is included with gear motor drive and a hydraulic-powered rag rope cutter. A skid-mounted hydraulic system, including tank, pump, filter, and all necessary piping and controls, was provided by Voith.
A detrashing screening system is included with the pulping system. Stock from the pulper is processed in a Voith-designed Contaminex unit, and the contaminants are concentrated and periodically dumped to a drum screen for removal and fiber recovery. Additional stock defiberization occurs as the pulp passes through an extraction plate with ¨-in.-dia holes. The accepted stock is fed forward in the process at about 4% consistency.
The tailings screen is a Voith drum screen. The screen is constructed of 316L stainless steel and screens the Contaminex rejects via a 4,500-mm-long drum with 12-mm holes. A V-belt drive with guard is included and fixed to rotate the drum at a maximum speed of 25 rpm. Rejects from the drum screen are sent to the rejects handling system for additional dewatering, while the accepted filtrate is sent back to the pulper for fiber recovery.
SCREENING, CLEANING, AND THICKENING.
From the pulper, stock is fed to a dump chest, where it is diluted to about 3% and then sent to the screening system. Screening for the new line consists of a three-stage coarse-screening system followed by three-stage fine-screening supplied by Black Clawson.
Stock from the pulper is pumped through high-density Black Clawson No. 17 Liquid Cyclone cleaners and then to two pressure-type primary coarse screens operating in parallel. These screens are size 400 Ultra-V screens constructed of 316L stainless steel with a screen basket of 0.062-in.-dia holes. The screen holes are continuously cleared by a multi-bladed foil rotor operating at 470 rpm through a V-belt drive located on the bottom of the screen.
Rejects from the primary coarse screens are collected in a chest and sent to the secondary coarse screen, a Black Clawson Float Purger operating at about 2% feed consistency. The Float Purger simultaneously screens and removes both heavy and light contaminants while providing for additional defiberization of flakes that are rejected from the primary coarse screens. Contaminants from the Float Purger are collected in a special chamber that periodically dumps to the sand separator. The lightweight material is continuously rejected from the top of the vessel to the next screening stage, while the remainder of the stock is deflaked via a V-belt-driven 25-in.-dia rotor over an extraction plate with ¨-in.-dia holes. The tertiary coarse screen, a Bird Escher Wyss reject sorter that operates at 2% consistency, is an atmospheric tailings screen.
Accepted stock from the primary coarse screen is sent to an agitated primary-screen feed chest and diluted to 1.5% consistency. The stock is pumped through a battery of medium-density Black Clawson No. 17 Liquid Cyclone cleaners and then to two pressure-type primary fine screens operating in parallel. These screens are size 500 Ultra-V screens with a screen basket of 0.010-in. profile slots that are continuously cleared by a multi-bladed foil rotor operating at 527 rpm through a V-belt drive located on the bottom of the screen. Accepts from the primary fine screens flow forward to the first stage of fine forward-flow cleaning. Rejects from the primary fine screens are collected in a tank and then fed at about 1.4% consistency to the secondary fine screen.
The secondary fine screen is a size 300 Ultra-V screen with a screen basket of 0.010-in. profile slots that are continuously cleared by a multi-bladed foil rotor operating at 780 rpm. Accepts from the secondary fine screen combine with the primary fine screen accepts and flow forward to the first stage of the fine forward-flow cleaning system. Rejects from the screen are collected in a tank and pumped to the tertiary fine screen at 1.3% consistency.
The tertiary fine screen is a size 100 Ultra-V screen with a screen basket of 0.010-in. profile slots. The slots are continuously cleared by a multi-bladed foil rotor operating at 780 rpm through a V-belt drive located on the bottom of the screen. Accepts from the tertiary fine screen flow forward to the secondary fine screen feed tank, while the rejects are sent to the rejects handling system for further dewatering.
Both sets of cyclones--high-consistency and medium-consistency--are complete with automatic batch reject system and controls and valuing for connection of elutriation water to minimize rejection of usable fibers. The cleaners are constructed of cast iron with fabricated steel base and are designed to operate at a pressure drop of 20 psi for the high-density units and 25 psi for the medium-density units.
The fine reverse-flow cleaner system consists of two stages of Black Clawson primary X-Clones in series followed by two more stages of the same cleaners in series to comprise the secondary cleaners. The first stage of primary X-Clones is fed at about 1% consistency. Each primary stage consists of four banks of 64 three-in.-dia cleaners in parallel. Accepts from the first stage are sent to a feed tank and then fed to the secondary stage at 1% consistency.
Rejects from the primary X-Clones are fed at about 0.2% consistency through the secondary X-Clones, comprised of two banks of 48 three-in.-dia cleaners each. The secondary X-Clone system operates at a pressure drop of 15 psi with a nonpressurized rejects trough. Accepts from the secondary stage are returned to feed the first stage of primary X-Clones.
Cleaner dilution water is provided from a feed chest, with a supply pump for each primary stand and the No. 2 secondary stage; the first secondary-stage pump takes its dilution from the No. 2 primary feed chest. The rejects from the two primary stages are combined and then sent to the pump suction of the No. 1 secondary-stage pump.
Accepts from the No. 2 primary X-Clones are thickened over a Celleco centerdisc-type thickener to a consistency of 12%. The thickened stock is pumped via a thick-stock MC
pump to either of the two existing high-density storage chests. Filtrate from the thickener is used for dilution, with makeup water provided from excess paper machine whitewater.
REJECTS HANDLING SYSTEM.
The rejects from the secondary X-Clones are collected in a tank, combined with a portion of the No. 1 OCC plant's Contra-Clone rejects, and pumped to a Krofta dissolved air flotation (DAF) clarifier for removal of lightweight and heavyweight contaminants. The contaminants are dewatered while the clarified whitewater is reused in the process.
Rejects from the drum screen and the reject sorter are dumped into a chute that feeds a Tru Mag dewatering press. The Krofta DAF clarifier contaminants are dewatered in a Hydradenser and flow to the press feed chute. The Tru Mag press discharge consistency is 50%. These rejects fall through a flop-gate chute to feed either of two dumpsters for removal to landfill or to feed a pneumatic conveying system for burning in a boiler.
The liquid cyclone cleaner-rejects flow to a sand separator that removes heavyweight materials from the reject stream and conveys them to a dumpster bucket. These rejects are combined with the rag rope cuttings and removed to landfill.
Overflow from the sand separator is collected in the plant U-drain system. The U-drain system also features a scalping screen to ensure that foreign particles are removed prior to collection of the various water streams for reuse. Effluent that passes through the scalping screen is collected in a sump and pumped back to the pulper as dilution. This stream is normally comprised of only the sand separator overflow stream and any wash-up hoses or gland water streams in the facility. The system is also designed not to recover the filtrate from the rejects press, which is considered too dirty to reuse. In the event of failure of the sump pump, the sump overflows into the U-drain system that collects the dewatering press filtrate for transport to the waste treatment plant.
Stock is pumped from existing high-density storage tanks and the two existing OCC high-density tanks. New stock pumps were added to handle the increased flow rates as required. Each system has a low-density storage chest preceding the primary refining stage.
The primary top-sheet refiners are four new Beloit Jones 46-in. double-disc units. The top-sheet system has a machine chest followed by two existing 42-in. tickler refiners. Stock arriving from the tickler refiners is piped to the basis weight valve at the top-sheet fan pump.
Basesheet stock is pumped from the low-density storage chest through four 54-in. refiners to the basesheet refined chest. Stock passes through a 54-in. tickler refiner to the basesheet blend chest. From the blend chest, stock is pumped directly to the basesheet fan pump suction.
OCC stock is separately refined through three existing 42-in. refiners and delivered to the basesheet blend chest. Broke is metered into the basesheet blend chest after being deflaked.
NO. 1 PAPER MACHINE REBUILD.
Valliant's No. 1 machine, a 356-in.-trim unit, was originally built in 1972 by KMW and has undergone only minor upgrades since that time. Average tpd prior to the rebuild was 1,300. The rebuild boosted machine output by approximately 33% to about 1,800 tpd.
Primary-screen accepts piping from the screen discharge to the headbox is polished to pass a cotton-ball test and supported to minimize vibration. The new top-line fan pump is of low-pulse design--pressure variations in the discharge are not to exceed 0.15 psi. The two existing basesheet screens were reused, but a new screen was required for the top ply because of the increased volume capacity needed.
The existing screen rejects system remained essentially unchanged. It was necessary, however, to increase the thickener feed pump capacity. One additional thickener was installed due to the increased rejects volume. An existing tile chest was converted into the screen rejects chest.
The machine's primary headbox was left unchanged. It delivers the basesheet onto the forming board at approximately 0.55% consistency. The existing fourdrinier was the basic structure upon which the new forming section was constructed. The fourdrinier saveall pans were designed to handle a layered bottom sheet in the future.
An existing Flo-Vac unit was removed and replaced with three flat boxes. Other existing drainage equipment was relocated and rearranged to handle the new table.
The first top-wire unit is a Bel Bond HC (High Capacity) former, Beloit's first installation of this new design. The former is designed to remove up to 70 gal/min/in., up to three times as much water as standard top wire units. The Bel Bond HC includes a new long, curved lead-in shoe design that provides a smooth, efficient water removal flow. The result is a gradual, gentle dewatering that delivers maximum drainage.
Similar to Beloit's Bel Baie twin-wire former, the Bel Bond HC has no rolls in the forming zone. Stock is influenced by pressure pulses as it passes over a special series of blades, which mobilize the fibers and provide optimum formation.
The primary top-wire unit is followed by a Beloit Concept III secondary headbox, added to deliver a single-layer top sheet onto the basesheet. Stock is delivered at 0.5% consistency. The new secondary headbox is a hydraulic design--no air pad is used, so a separate attenuator is placed in the approach system to absorb hydraulic pulses generated by system dynamics. The attenuator is operated using mill air over a diaphragm in contact with the entering stock. Control is automatic, and the unit can suppress pulses in the range of approximately 3 to 40 Hz. The secondary headbox is designed to be removed from the forming section for changes of the bottom wire.
The secondary headbox is immediately followed by a second, standard Bel Bond unit. Both top-wire units are cantilevered for wire changing.
The existing suction pickup, double-felted first press was left essentially intact without major revisions. Sheet consistency entering the first press is approximately 25%. The sheet is transferred from the forming unit with a suction pickup roll (existing). The sheet is then carried through the first press and is transferred to the new second press bottom felt by the suction transfer roll. Nip loading for the first press is 700 pli.
New framing was installed for the new second press and adapted to fit with the existing first press framing. The new press, a Beloit Extended Nip Press (ENP) with variable-controlled crown roll, is a shoe design that permits long nip dwelltime. Citty said the mill is achieving 42% to 45% sheet solids, which is an increase of about 10% in the sheet entering the dryer section. Nip loading on the ENP is around 6,000 pli.
Jim Crews, Valliant's No. 1 machine superintendent and production coordinator for the expansion project, said the ENP has made significant improvements in sheet characteristics. "We've achieved a much denser sheet, caliper is lower, and STFI is higher," he said. "One of the major reasons we added the ENP is to achieve higher STFI, so we are meeting all the goals we had planned."
Because the ENP is very heavy, modifications were made to the existing framing. Included with the new press were four new Uhle boxes, additional showers, a steam hood with suction box, a suction transfer roll, new hydraulic systems, and a support structure for the bottom second press felt stretcher and other basement felt run equipment.
Two hydraulic systems were used. One is dedicated to the controlled crown roll; the other one powers the press-loading shoe system. Each system has dual pumps, oil coolers, and filtration systems.
DRYER SECTION AND WINDER.
In the dryer section, the breaker stack was left in place. The doctors in the first dryer section were replaced with new units, and new doctors were added in both the second and third dryer sections. Spoiler bars were installed in all the dryers. The first dryer section's first and second felt rolls were replaced with suction rolls to aid in sheet transfer from the press section.
The tail transfer system was upgraded to improve operation at the higher rates planned. A Paprima water jet tail cutter was installed in section seventy to assist threading at the dry end. No changes were made to the calender or reel.
A new, high-speed winder was installed, designed by Beloit Lenox to operate at a maximum speed of 7,500 fpm. Because of the very high maximum production rate possible, the winder was fitted with numerous automation options required to minimize the set cycle time. Included in the automation was a sheet holder, automatic slitter setting, automatic core injection, threading assist system, tension controls, powered side lay adjustment, empty spool removal system, and automatic set changing system. A new regenerative drive was installed with the winder.
The mill rebuilt its three original Lowerator lowering tables to eliminate bottlenecks caused by the additional number of rolls coming off the winder. The mill also added a labeling system in addition to its stenciling for finished rolls.
The rebuilt machine requires a considerable increase in the air handling capacity of the vacuum system. The couch roll airflow was approximately doubled, and the press section Uhle boxes were increased by similar magnitudes.
New vacuum pumps were required for the couch roll, the flat boxes, and transfer box systems. The remaining vacuum service requirements are supplied by existing vacuum pumps. Some repiping of the existing systems was required, and the couch roll and second press Uhle box systems were newly piped. Two existing vacuum pumps were rebuilt to increase the vacuum capability for the pickup roll system.
Excess whitewater from the paper machine is clarified in a new disc saveall. The saveall feed is made up of whitewater and sweetener stock required to bring the saveall feed consistency to the minimum needed for proper operation. In addition, the saveall is designed to accept relatively large variations in feed consistency, which can occur in this type of system. Clarified filtrate from the saveall system is reused for showers as much as possible. Cloudy filtrate is used for dilution or recirculated to the saveall. Recovered stock from the saveall is returned to the broke high-density chest.
As much as possible of the existing machine shower system was reused. Additional high-pressure shower equipment was required for the forming section. Where clarified whitewater is not practical for use in such showers as the high-pressure wire and felt showers, reclaimed cooling water is used.
Because of the increase in the maximum production rate, it was necessary to rebuild the dry end pulper and modify the existing press section pulp and couch pit. Broke pumping capacity was increased from the pulpers to the broke surge chest. The remaining broke system was not changed.
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