Kynar® Polyvinylidene Fluoride (PVDF) Pulp & Paper
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Long Wire Life To Become Even Longer After Crestbrook Optimization Program
A major $20 million optimization program, now underway at the Skookumchuck Pulp Division of Crestbrook Forest Industries Ltd., will reduce operating costs significantly through reductions in consumption of energy, chemicals, and other materials while increasing fiber utilization and improving product quality and cleanliness.
The capacity of the plant, located 35 miles above Cranbrook in British Columbia, will also be increased 15% to the level of 560 air-dried tons a day of bleached kraft pulp.
One side benefit of the program will likely be an extension of the already exceptionally long service life Crestbrook Forest Industries (CFI) is getting from its bleach washer drum covers made from Kynar® PVDF.
The Skookumchuck mill has been using wire made from Kynar® PVDF resin on all its bleach washer drums since the present 5-stage bleach line went into operation in 1977 and has converted from polypropylene to Kynar® PVDF on its brown and bleach deckers for complete standardization. They're supplied by the Barrday Division of Wheelabrator Corp. of Canada Ltd.
Al Manjak, production superintendent, says he has been getting up to three years of life from Kynar® PVDF on the chlorination stage and up to five years or more on the chlorine dioxide drums. In August of 1985, for example, the covers (made from Kynar® PVDF) on the two dioxide stages had been in place for approximately 5 years each; and the second extraction wire had been running since it was put on in 1977.
Ironically, this good service comes under less than ideal operating conditions, according to Manjak. The existing wire-cleaning shower system no longer provides adequate pressure to clear the buildup of pitch, talc, and stock which can blind the wires on these vacuum-filter drums. The resulting loss of drainage capacity can shorten wire life as well as boost chemical costs through reduced washing efficiency.
To remedy this, a new high-pressure, oscillating-head shower system for cleaning bleach plant wires is being installed at a cost of $115,000 as part of the optimization program. "It should substantially increase the very good wire life we're now getting," according to Manjak.
The drums on Skookumchuck's bleach washers are not designed for D-wire or winding wire. When the bleach plant started up in 1977, this resulted in too much fabric movement and the cutting of fabric. To overcome this, Barrday designed a 10-mesh backing fabric - face wire made from Kynar® PVDF resin - that is shrunk onto the drum before the facing fabric is installed.
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High-Technology Alabama River Mill Standardizes On Face Wires Made From Kynar® PVDF
The Alabama River Pulp Company in Clairbore, Alabama, was designed to serve the international markets of Western Europe, Japan, and U.S. specialty paper mills. The latest technologies and superior processing equipment were specified to ensure a high level of cleanliness and brightness for the bleached kraft pulp.
The 5-stage bleach plant (D/C-E-D-E-D) exposes an average 1,100 tons a day of brown stock to a series of chemical treatments that transform the natural brown fibers into a high brightness pulp.
Face wire made from Kynar® PVDF has been used for the cylinder covers on all five stages ever since the bleach plant went into full operation at the beginning of 1979. This face wire was already industry state-of-the-art when the plant was built; everybody was using it by that time, explains Tom Tippy, mill manager.
"We already had favorable experience with covers made from Kynar® PVDF in our plant in New Brunswick, Canada," he adds. "And it's since proven to be the best material for the job here."
Despite a pH range of 2 to 10.8 on the bleach line, the mill is getting up to one year's life out of the PVDF wire supplied by National Wire Fabric Corporation, Star City, Arkansas. "When we do lose a wire," says Jim Calloway, pulp mill superintendent, "it's usually the result of something else, and a strip patch remedies the situation. We've hardly ever been shut down because of Kynar® PVDF material failure."
In addition to longer service life in these highly corrosive conditions, the face wires are much lighter and easier to install than stainless steel covers. The mill can change a cover in 4 hours compared to the 8 to 10 hours it takes to change the stainless steel wire on its brown stock washer, the one drum in the mill not using wire made from Kynar® PVDF.
Today, National Wire supplies the covers made from Kynar® PVDF not only to the 5-stage bleach washer line but also for the brown decker and two bleach deckers. All are 30' wide by 13' diameter drums of split design. Two 15' wires made from Kynar® PVDF are used to cover each cylinder. Alabama River has standardized on Kynar® fluoropolymer for all these reasons: (1) to simplify inventory, (2) to prevent accidental error in wire selection, and (3) because its use of recycled filtrate calls for higher corrosion resistance even on the extraction stages of the bleach line.
Piping Lined With Kynar® PVDF For ClO2 Wet Cl2
Lined piping has been at work here since startup of operations. Approximately 1000' of carbon steel pipe (lined with Kynar® PVDF) supplied by Dow Chemical - most of it 3" to 6" in diameter - moves 20 to 30 tons a day of chlorine dioxide from the chemical prep area to the bleach plant.
Piping lined with Kynar® PVDF is also employed in the ClO2 generating plant and in the mill's wet chlorine lines.
"We find that Kynar® fluoropolymers work better on a cost-performance basis in these applications than stainless steel, in lined FRP, or CPVC (SARAN)-lined systems," says Don Ackerman, maintenance manager.
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Growing Affair With Components Made From Kynar® PVDF In Bleach Plant At Finch, Pruyn Mill
Over the past five years, Finch, Pruyn & Co., Inc., in Glens Falls, N.Y., has had increasing experience with a variety of different fluid handling system components made from Kynar® PVDF.
This includes both solid and lined piping, vessel linings, filter covers and winding wire, and most recently the complete resurfacing of a worn bleach washer drum.
The net result has been a steadily increasing reliance on Arkema's polyvinylidene fluoride material throughout the bleach plant.
In the Hypochlorite System
 The sodium hypochlorite generating plant is a good example. Finch, Pruyn produces NaOCI by combining dry chlorine gas with a mixture of caustic in water. From this point on, just about all of the hypochlorite fluid handling system is protected with Kynar® PVDF resin.
Pipe lined with Kynar® PVDF resin was first introduced into the hypochlorite system around 1977 as a replacement for CPVC when Finch, Pruyn initiated its long range program of upgrading and expanding capacity. Today, hundreds of feet of Resistoflex steel piping lined with Kynar® PVDF resin - in diameter sizes from 1 ½" to 4" - now carry this corrosive bleaching agent all the way from point of production up to the bleaching floor. There solid 2" piping made from Kynar® PVDF takes over, including a 16' long perforated shower line that sprays the NaOCI into the pulp on the discharge side of the preceding caustic stage.
The sodium hypochlorite is at a concentration of 30 g/l of Cl2 at 100°F and has a pH of 12. Evidence of its corrosiveness is the fact that the three centrifugal pumps in the system (for recirculation and delivery, plus a backup) are all made of titanium.
The hypochlorite facility also includes three vessels lined with Kynar® PVDF. Two 900-gallon FRP tanks supplied by Ceilcote - each 5' in diameter by 8 ½' high - are lined with 1/4" thick glassbacked laminate made from Kynar® PVDF. One serves as the recirculating or make-up tank in the system, the other as the NaOCI delivery tank.
These vessels had been lined with a variety of materials in the past, most recently with polypropylene. The polypro on average gave about 10 months of service, according to Steve Eliot, project engineer in charge of the new hypo plant. He expects four times that life from the lining, which is made from Kynar® PVDF and which has already been in service for 16 months without any signs of deterioration.
The third lined vessel supplied by Bee Fiberglass is an instrument pot that serves as an end-point controller for chlorine flow by monitoring the residual Cl2 in the system.
In the Chlorine Supply System
The earliest use of piping made from Kynar® PVDF at the Glens Falls plant was probably in the chlorine supply system where it replaced polypropylene lines.
Finch, Pruyn pumps dry chlorine under pressure from tank cars and moves it through thick-walled steel piping until the point where the Cl2 is vaporized with steam. From that point on steel pipe lined with Kynar® fluoropolymer takes over in handling the corrosive Cl2 gas. The Cl2 is injected though a perforated nozzle (also made from Kynar® PVDF) into a static mixer for combination with the brown stock pulp.
On Bleach and Brown Stock Washer Drums
Finch, Pruyn produces an ammonium sulfite-based pulp suitable for the production of its fine printing papers in the adjacent paper mill. Present bleached pulp capacity is 350 tons a day and growing. A three-stage bleaching process is used: chlorine, caustic (NaOH), and hypochlorite. There are two bleach washers in the final hypo stage. The process bleaches to an 84 brightness (GE standard).
Face wires and winding wires (made from Kynar® PVDF) supplied by Barrday are now the first choice on all three stages (four washer drums) as well as on the thickener stage and two brown stock washers that precede the bleaching phase.
The first cylinder cover made from Kynar® PVDF was introduced about 5-6 years ago on the chlorine (first) bleaching stage. It replaced polypropylene and gave a full three years or more of service in the severe 140-150°F wet chlorine (pH 2) environment. Face wires made from Kynar® PVDF have since been put on the two hypo stage washer drums and will now also be used on the caustic (NaOH) stage once Finch, Pruyn has used up the stainless steel wires still in inventory.
Innovative Washer Drum Restoration
Latest role here for Arkema's versatile polyvinylidene fluoride has been as the protective outercoat for a completely resurfaced chlorine stage bleach washer drum. The heavily pitted and corroded stainless steel cylinder - measuring 8' in diameter by 16' long - was completely renovated in a new procedure developed by the Impco Division of Ingersoll-Rand in conjunction with El-Chem Construction Company, Ltd., Canada.
The process involves restoration of the mechanical integrity of the drum, and then virtual encapsulation of all exposed surfaces in polyvinylidene fluoride. Three different forms of Kynar® PVDF are involved: dispersion coating, wet of dry laminate, and solid extrusions for capping of the cylinder grids.
The restored drum cost Finch, Pruyn several hundred thousand dollars less than the purchase of a brand new unit, yet should last almost as long. It's on standby now, waiting to replace the next cylinder that has to be pulled.
The bleach plant previously had several other drums resurfaced with fiberglass-reinforced plastic. These have given good service, according to Dick Dingman, maintenance coordinator. Reports from other mills of failures due to peeling off of the FRP, however, prompted Finch, Pruyn to switch to the Kynar® PVDF system.
"The drum lined with Kynar® PVDF can be used on any stage in the plant - either in bleaching or brown stack washing," says Dingman, "and temperature won't bother it."
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St. Regis Reduces Downtime With Switch To Face Wire And Piping Made Ffrom Kynar® PVDF
 The Pensacola, Florida, mill of St. Regis Paper Company, the largest complex of the 136 operated by the company in 10 countries, took a chance on Kynar® polyvinylidene fluoride five years ago. Today, this fluoropolymer is used extensively in the firm's bleach plant and chemical recovery operation.
The 800-acre St. Regis Kraft Center, located 15 miles north of Pensacola, is a sprawling complex where 1,800 employers produce 900 tons of kraft paper and a million multi-wall bags each day.
The kraft paper is used for shipping sacks, linerboard, drinking cups, carton and sanitary food wraps, and pulp for disposable diapers. This production requires an extensive and corrosive bleaching operation, and it was into this bleaching operation that Kynar® PVDF was first introduced in 1974.
While officials at St. Regis now consider Kynar® PVDF valuable in their operations, it took special circumstances for the highly corrosion-resistant material to get a foothold in the bleach plant.
In the late fall of 1974, St. Regis was completely replacing a washer drum - the chlorine stage and first washer in the C-E-H-D-E-H bleaching sequence.
While the chlorine washer was down, St. Regis officials had a choice of putting the usual 317 stainless steel face wire and backing wire on the drum or replacing it with wire made from Kynar® PVDF, which had never been used at St. Regis. In the words of St. Regis Pulp Mill Superintendent Fred Bond, the company decided to "take a fling" with Kynar® fluoropolymer.
"It was strictly a case of taking a calculated risk because it was the first time any of the St. Regis plants had used Kynar® PVDF," Bond reports. The main reason officials opted for the Kynar® PVDF, Bond recalls, was its reputation for quick installation.
 It usually took almost a full day to replace the stainless steel face wire and tacking wire on a washer drum, but the time was considerably shortened by using Kynar® PVDF.
"The maintenance men were ready to put the Kynar® PVDF on about 9 p.m., and they were cleaned up and out of the area by shortly after midnight. It saved us almost a full day's time," Bond says.
The original wire made from Kynar® PVDF, installed in the fall of 1974, was not replaced until March of 1977. Its replacement lasted until July 1978 and was replaced then only because of another malfunction in the washer and not due to corrosion. The third generation of face and backing wire made from Kynar® fluoropolymer on that particular washer is still in service.
Wire coated with Kynar® PVDF was installed on a second washer (chlorine dioxide) in June 1975. It lasted until May 1978, and its replacement is still on the washer. This performance was extremely impressive to St. Regis officials since the face wire had lasted almost three years despite subjection to a ClO2 solution with a pH level of 2 and temperatures of 150° F.
Kynar® PVDF was installed on a third washer (the first sodium hypochlorite stage) in April 1978 and that wire is still in operation. It was also installed on a fourth washer drum (the second hypochlorite stage) later on.
While wires made from Kynar® PVDF have served the bleach plant operation well, solid and lined PVDF pipes have also been used at St. Regis with good success.
There are several hundred feet of pipe lined with Kynar® PVDF, supplied by Dow Plastic Lined Piping Products, which carry chlorine throughout the bleach plant. The mill had previously used PVC piping, but Kynar® resin has proved to be tougher in resisting the chlorine which has a pH of 3.5 .
There is also some 60 to 80 feet of solid pipe made from Kynar® PVDF in the by-products plant at St. Regis. The tall oil plant takes black liquor soap, a by-product of the kraft cooking process, and produces a liquid known as "tall oil." The "tall oil" is sold as a basic ingredient for perfume and soap.
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Kynar® Fluoroplastic: The Solution For Corrosion At James River Mill
The chlorine dioxide spent acid line is no longer a problem line at the Naheola Pulp Mill of James River Corporation. Eight years ago, however, high temperatures in the sulfuric acid stream containing chlorine and chlorine dioxide traces necessitated frequent replacement of failed sections of the CPVC-lined steel piping.
Normal operating temperature of the highly corrosive (pH=1) spent acid was 43°C. The problem was further complicated with the addition of insulation and steam heat tracing to prevent freeze-ups during the especially severe winters of the early 70s.
The original CPVC lining material in these 2-inch diameter lines just couldn't take the high and low temperature extremes.
Beginning in 1974, plant maintenance started replacing failed sections with steel pipe lined with Kynar® PVDF, which was supplied by Dow Chemical USA, and soon converted the entire 600-foot system. In the intervening eight years, according to William Irby, mill technical superintendent, "We only had to replace one or two small pieces of the entire 600-foot run."
Situated on the west bank of the Tombigee River, near Pennington, Alabama, the 1000 ton-a-day Neheola Mill (until 1982 a part of American Can) produces pulp, paper, paperboard, and a wide variety of finished paper products. The latter includes a broad range of nationally known quality household and service paper towels, tissues, and napkins.
The favorable introduction of Arkema's fluoropolymer soon led to a similar conversion of the wet section of the plant's chlorine gas lines with similar success.
Kynar®PVDF has since also established itself as the face wire of first choice on the bleach washer drums of both the hardwood and pine bleaching lines. These filter cylinder covers are woven of monofilament (made from Kynar® PVDF) by the National Wire Company of Little Rock, Arkansas, and give up to double the life of the stainless steel face wires they replaced.
The superior performance is most notable on the chlorine and chlorine dioxide stages where the face wire is consistently providing 2-3 years of trouble-free service. The stainless filter covers lasted about 1-1 ½ years before in this service, according to Oscar Spencer, pulp mill area supervisor.
There's another significant benefit to face wire made from Kynar® PVDF, according to Spencer. It can be applied in about half the time it took to install the stainless steel wires. "It takes about 8 hours for the sleeves, compared to about 16 hours for stainless," says Spencer. "Anytime we can eliminate eight hours of downtime in this high productivity mill, we're mighty happy," he added.
Today, components made from Kynar® PVDF are being used at the Naheola Mill everywhere there's an appropriate application. As process engineer Dale Smith claims, "Initially, we only used the lined piping on the pineline, but we recently switched over on the hardwood line too."
"Arkema's fluoropolymer has played a welcome role in helping keep this facility operating full time," adds Smith. "Over 30 railroad carloads of consumer products are scheduled to leave here every day. At this end of the line our responsibility is to keep bleached pulp moving to our manufacturing plant, and components made from Kynar® PVDF are making a constant contribution to that effort.
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Fifteen Years In A Swedish Papermill Not A Long Time For Pipe Lined With Kynar® PVDF
 Jan Åberg, of BTR Industries AB in Sweden, has an interesting paperweight on his desk at the company offices in Halmstad. It's a ninety-degree elbow in two-inch pipe lined with Kynar® PVDF, and it came from the first installation of such pipe sold in Sweden.
The pipe came from a papermill operated by AB lggesunds Bruk at Strömsbruk where it carried the chlorine used in the bleaching process for cellulose. Between the time that Jan Åberg sold the pipe and the time it came back to rest on his desk, it was carrying a high-corrosive chlorine and water mixture at 35°C - 24 hours a day, seven days a week - for 15 years with no downtime for repairs throughout the period.
When piping made from Kynar® PVDF first became available in Sweden in 1967, one of the first applications to be considered was for bleaching plants. Using normal materials, even exotic alloys, bleaching plant pipework had a life expectancy which was measured in months or weeks rather than years. The corrosion-resistance of the Kynar® PVDF promised much better performance, but papermill engineers were skeptical.
The first test of this lined pipe in a bleaching plant was on an experimental basis a the Morrums Bruk plant of Sodra Skogsagarna AB, Sweden's second largest forestry company. With the experiment successful, the first sale of pipe was to AB Iggesunds Bruk for its cellulose factory at Strömsbruk.
Walter Tegenfelder of the Strömsbruk engineering and safety department was skeptical about the quality of pipe made from Kynar® PVDF and made provision in the designs for a second duplicate steel pipeline to run alongside the new line. He was worried that there was a long section of the line which ran in an exposed position outside the building; and with nighttime temperatures which can drop to well below -20°C, he anticipated problems.
He was even more worried when he found that the length of pipe required would need no less than eight joints along its length, each of which would have no extra gaskets or seals and would rely on butt-joints between the flanges (also made from Kynar® PVDF) of each section held in place by bolts tightened to pre-set torque limits. "I was sure it wouldn't work," he says now, "and I was convinced we would need that duplicate pipeline."
That was at the end of 1967. In 1982, Iggesunds Bruk undertook a reorganization. Its cellulose plant, which has specialized in the production of raw material for photographic paper, was to be transferred to another location; and the bleaching plant was taken out of commission. The chlorine pipeline lined with Kynar® PVDF was still there and so was the reserve steel line.
The reserve, however had never been used. In almost fifteen years of continuous use, the lined installation had never had to be closed down apart from normal maintenance. When the two lines were cut by the demolition gangs, the interior of the unused steel duplicate pipeline was in worse condition than its Kynar® PVDF-lined neighbor which had spent its lifetime carrying the chlorine and water mixture! There was no evidence whatsoever of the chlorine permeating the liner made from Kynar® PVDF and attacking the steel casing.
In anticipation of the leaks which he was sure would come, Walter Tegenfelder also laid in a selection of spare lengths of pipe lined with Kynar® PVDF for replacement purposes. Fifteen years later, the pipes still lie in the engineering stores, unused. In all the time that the plant was operating, no replacements were made at all!
Since the first sale of pipe for the bleaching plant, pipe lined with Kynar® PVDF has found a ready acceptance on the Swedish market. Chlorine is one of the most dangerous substances in general industrial use. The need for secure systems for carrying the chlorine is obvious, and the fact that piping made from Kynar® fluoropolymer has received approval from the Swedish safety standards authorities has made its use even more acceptable.
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Steadily Expanding Role For Kynar® PVDF At Boise Cascade's Paper Plant In Rumford, Maine
 Seventeen years of uninterrupted service with PVDF-lined pipe carrying wet chlorine gas have proven the durability and toughness of Kynar® PVDF and led many other corrosion-resistant applications at Boise Cascade's Rumford paper plant.
Since its first cook of soda pulp on November 9, 1901, Boise Cascade's Rumford, Maine, plant, long known as the Oxford Paper Company, has grown to the point where today it produces 1,650 tons per day at its site on a bend in the Androscoggin River.
Boise Cascade acquired the plant in 1976. Today, the mill produces coated and uncoated stock for book publishers as well as magazines such as NATIONAL GEOGRAPHIC, VOGUE, COSMOPOLITAN, and TV GUIDE.
Many different factors are responsible for the success of the Boise Cascade plant, and one of them is due to Kynar®polyvinylidene fluoride.
Use of Kynar® PVDF began at the Rumford plant in 1963, then under the ownership of Oxford Paper Company. Plant officials, impressed with similar Kynar® PVDF applications, ordered 200 feet of two-inch piping lined with Kynar® resin and installed it to transport wet chlorine gas. "The pipes have been in place for nearly 17 years and have not required any significant repairs," reports Mel Aylward, plant superintendent. Aylward recalls that the polyvinylidene chloride pipes used prior to 1963 had to be replaced on the average of every six to eight months.
Since that time, the use of Kynar® PVDF has been multiplied many times. Today, pipe lined with Kynar® PVDF is used extensively throughout the bleach plant; and face wire also made from Kynar® PVDF is in service on all eight washer drums in the bleach plant.
There are more than 900 feet of two-inch pipe lined with Kynar® PVDF carrying chlorine dioxide at temperatures of 100°F and higher throughout the bleach plant.
This lined pipe (in 4-inch, 2-inch, and 1-inch diameters) also carries several different corrosive solutions, including 60% sulfuric acid, 46% sodium chlorate solutions, and pure methanol. This piping has been in place on these applications since 1976 without the need for repairs.
This lined pipe is also used in the new chlorine unloading system at Rumford. Less than a year after the system went on line, sections of FRP-lined pipe exposed to wet chlorine failed. Now, pipe lined with Kynar® PVDF is installed whenever wet chlorine may be present.
Boise Cascade obtains more than 95% of its pipe lined with Kynar® PVDF from Resistoflex Corporation and Dow Chemical Company.
Piping is not the only application where Kynar® PVDF has paid dividends at this plant. One of the most interesting uses of PVDF at Boise Cascade was as packing in sodium hypochlorite manufacturing tower. Several types of packing were tried; but Kynar® resin was the only substance that stood up to the sodium hypchlorite solution, which averaged 40 grams per liter at 100°F.
In fact, Kynar® PVDF was also used to coat the tower walls because the FRP lining repeatedly failed after only approximately six months of service. Ceilkote, Inc., which supplied the tower packing, laminated sheets made from Kynar® PVDF to the tower walls. This construction performed without problems for 18 months until the process was discontinued.
"It's too bad we don't know what to do with the Kynar® PVDF in the old tower," says Aylward, "It's as good as the day we put it in."
Kynar® PVDF is also taking over a greater responsibility for corrosion control in the bleaching system at Boise Cascade. The first face wires made from Kynar® fluoropolymer were installed on two washer drums six years ago. The initial face wire installed on the sodium hypochlorite drum at that time is still in service.
Now, all eight washers in the bleach plant (chlorine, sodium hypochlorite, chlorine dioxide, and caustic extractions with temperatures to 158°F) have face wires made from Kynar® PVDF supplied by Barrday. Each wire lasts an average of four years, according to the plant superintendent. This is two to four times as long as the 317 stainless steel wires which were used previously.
The wires made from Kynar® PVDF are also much easier to install. "It takes only about a quarter of the time to replace these face wires, and less downtime means more money in the bank," Aylward says. At Boise Cascade, face wires made from Kynar® resin can be replaced in as little as four hours. Stainless steel wires had taken as long as 16 to 20 hours to change.
Given the wide range of successes at Boise Cascade, it is no wonder plant officials have come to rely on Kynar® polyvinylidene fluoride for many of their corrosion problems.
"We're big Kynar® PVDF fans up here," says Aylwar, "because it works."
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