Research & Innovation
TMP: Tembec Does It Again: Massive Modernization for Pine Falls
By Pulp & Paper Canada
Tembec calls itself "A company of people building their own future." This being the case, the people in Pine Falls, MB, have built quite a future for themselves. Tembec recently inaugurated a new $124...
By Pulp & Paper Canada
Tembec calls itself “A company of people building their own future.” This being the case, the people in Pine Falls, MB, have built quite a future for themselves. Tembec recently inaugurated a new $124-million TMP plant. This goes along with the $36-million DIP plant that opened in 1996. In all, over $200 million has been invested in modernizing the mill since 1994.
The mill can now produce 180 000 tonnes per year (t/y) of standard newsprint using a furnish composed of 80% TMP and 20% DIP. The new TMP plant has a capacity of 525 t/d. The new TMP plant allowed the mill to close its groundwood and sulphite pulp mills, which accounted for 55% and 20% of the furnish respectively. It also allowed the mill to eliminate the use of kraft pulp in its furnish (5%)
Opened in 1927, in the mid-1990s, it faced an uncertain, if not bleak future. Abitibi-Price (which took the mill over in 1928) could not justify the cost of a needed TMP plant as it felt the return would not be sufficient. The mill was slated to close. Led by mill manager Fern Pitre (and Ashok Narang, now a part owner of Papier Masson), the employees purchased the mill from Abitibi in 1994.
However, as Pine Falls’ vice-president and general manager Denis Beausejour recounted, Pine Falls was probably the highest cost producer of newsprint in North America in 2000. Employees had taken a 10% cut in pay and agreed to a 5-year wage freeze when they bought a 40% share of the mill in an effort to keep it viable. In return, profit sharing was instituted. But now, even the employee management group realized a TMP project was necessary because of quality and cost issues. A partner was needed. In 1998, the mill was sold to Tembec. Original salary levels were restored and the employees shared a sizable amount of money from the sale. Tembec made a commitment that a TMP plant would be built. In addition, a partnership with area First Nations bands has opened the possibility of one, and possibly two, sawmills in the works.
Beausejour said the project leaves Pine Falls in a good position, even with two smallish paper machines. It will be in the low quartile for costs. Its “wood basket” is close to the mill, electrical rates are good and markets are close.
The TMP project is the largest single capital investment in Pine Falls’ history. It had three objectives:
to reduce manufacturing costs;
to make better use of the fibre species mix (spruce and jackpine);
to improve newsprint quality.
Other goals included reducing fossil fuels use and securing the long-term future of Pine Falls.
Detailed engineering began in May 1999 with construction beginning in February 2000. Thirteen months later, on March 1, 2001, the first pulp was produced. Start-up was almost trouble-free and has been called one of the best in North America. Design capacity was reached 28 days after start-up. Beausejour said that the mill was able to eliminate use of its former furnishes quicker than expected. Groundwood production stopped 13 days after start-up. Kraft pulp was gone after 14 days. The sulphite mill was retained at low tonnage, but after 23 days, it was shut.
Uptime reached 75 to 80% rapidly but problems with the secondary refiner — vibration and CD zone dilution — forced a short shutdown.
The mill started at a high production rate but the rejects screening problem made the mill pull back. Once this was corrected, there was a steady ramp-up of production to design capacity by the end of the 28 days when Pine Falls ran at 92, 93 and 100% uptime. Since May, the mill has operated at 425 t/d. With the DIP plant, this is sufficient to meet pulp needs and helps the mill save energy.
The mill uses a mix of spruce and jackpine: 75:25 (450 000 m3/y). It also has used the reverse ratio to test the equipment, but has gone back to 25% jackpine because of its wood inventory. About two-thirds of the mill’s chips come from on-site chipping, using up the inventory left over from the groundwood and sulphite mills. Spruce Products Inc., a Manitoba-based sawmiller, supplies the other 33%. The TMP plant is designed for a 50:50 ratio and this will be the case in the future.
Beausejour explained that jackpine was the unknown in the TMP process. The twin roll press was installed to remove the extractives from the process. Although, some fine tuning still remains to be done, he said that it has done the job in removing ionic trash, pitch and extractives. Pine Falls has been able to keep its polymer treatment levels on press felts at the same level, even running with 75% jackpine. No retention aids are needed and there are no problems with deposits.
Pine Falls opted for a Metso Paper TMP plant using a single-line, three-stage refining process using CD 82 refiners (primary, secondary and rejects). Two Metso Conflo refiners were also installed to further develop (polish) the fibres. These act as a sort of fractionation process.
The mill went for a single line because it provided enough capacity; it was simpler to operate; and, a smaller building could be built. “The technology is such now that we are not worried about breakdowns,” Beausejour said. “We have a good TMP inventory so we can react to upsets.”
TMP supervisor Bob Chisholm said the process is fairly standard. Purchased chips arrive by B train and the trucks go through the fully automated Rader dumper. Even chips made on site from the existing wood inventory are trucked to the dumper. A scalping screen at the dumper separates large pieces of trash from the chips. Chips are conveyed (Continental Conveyor) to one of two silos (20 000 m3 capacity, total), one for spruce, one for jackpine, each holding a 2.5-day supply of chips.
From the silos, chips go by metering belts to a bucket elevator that takes them to the chip screening room (the “penthouse”). A rotary chip screen removes the overs (1.75-in.+). There is also a 0.5-in. screen for accepts. The smaller chips go to the Acrowood DiamondRoll. Fines go to the fines bunker for burning in the No. 2 boiler. There is also an air density separator to separate the “big” chips and knots. The latter are burnt; the former are returned to the system.
The accepts are then fed to an atmospheric pre-steaming bin (45-min retention). Chips are heated to 90C with recycled steam from the refiners, then pass through a wash section that takes out sand and other dirt. From there, it’s into a cyclone and drainer to separate the chips from the water. The chip wash water goes to an inclined screen that separates pin chips. Pins go back through the process or to the fines bunker. The water is re-used for chip washing.
The second atmospheric pre-steaming bin follows (15-min retention). A plug screw feeds the chips to an impregnator. A metering conveyor then takes the chips to a preheater plug screw feeder into the preheater (pressurized to 130 kPa, 5-min retention). A discharge screw then feeds the chips into the primary refiner through the side feed and infeed screws.
The refiners are the second set of CD 82s to be installed in North America. The first were at Paper Masson (Pulp & Paper Canada, July 2001). Chisholm said that Pine Falls benefitted immensely from Papier Masson’s experience, especially in the areas of plate design and the dilution zone. Pine Falls’ refiners are powered by ABB’s 26-MW 35 000 hp. motors.
From the primary refiner, the pulp goes to a primary cyclone and then to the secondary refiner. The primary refiner blowline has an ABB consistency transmitter. Following secondary refining, there is another cyclone and the pulp then passes to a latency chest with 15-min retention.
After latency, the pulp goes through the Conflo refiners, which act as a sort of tertiary refining stage. This stage enhances fibre development, improving the tensile strength in particular, Chisholm explained. “We use the additional energy in the Conflos and reduce the freeness,” Chisholm added. The Conflos are not used as energy savers as is the case with other mills.
The pulp then goes into a 30-min latency chest, and between the two latency chests is a Pulp Quality Monitor for freeness, fibre length
and shive measurements.
Following latency, the pulps goes to the screening system, a P1, S1 configuration. Accepts from both screens go to the disc thickener. Rejects go to the secondary screen. Rejects from the secondary screen go to a rejects transfer tank.
The primary screening process uses a 0.20-mm slotted wedge wire basket. The secondary uses a 0.15 slotted wedge wire basket. Accepts go to the Kvaerner 5.2-m dia., 15-row disc thickener. It is designed to handle 580 t/d of pulp.
Off the disc thickener, the pulp has a consistency of 10 to 12%. It enters the twin roll press feed tower with a 30-min retention, where it is diluted with recovered fresh water, heated to 70C (the process temperature) and pumped to the Metso twin roll press. It is thickened to 32% consistency. Part of the filtrate is purged to the atmospheric scrubber and then to the chip wash system and the rest is used for dilution in the disc thickener.
Pulp from the twin roll press is diluted to 12 to 14% consistency with paper machine cloudy white water. One of the aims of the twin roll press is to provide a water block between the paper machines and TMP plant. That is, all the water from the TMP process stays on the TMP side with the same holding true for the paper machine side.
Pulp is then pumped (medium consistency) to the high-density storage tank, which can hold 525 t at 12% consistency. The high-density storage tank can be used as a broke tank if necessary because the mill’s broke capacity is limited.
The unbleached pulp brightness target is 55 ISO. The mill uses sodium hydrosulphite to bleach to 59.5 ISO.
As noted, rejects go to a rejects transfer tank, 3.5% consistency. From this tank, they pass through high-density cleaners into a rejects storage tower, 90-min retention. From there, the rejects pass through two Kvaerner SD70SL screw presses and from there, into the rejects refiner plug screw feeder. The rejects refiner is also a CD 82.
Following refining, a blowline takes the pulp to a rejects cyclone. From there, it goes to the rejects screen, a 0.18-mm slotted wedge wire basket. Accepts go to the disc thickener and mix with the P1 & S1 accepts. Rejects return to the rejects transfer tank. The overall rejects ratio is about 55% by mass.
Steam and water
Back flow steam from the primary and reject refiners goes to a pressure scrubber. This steam is used to heat chips, melt ice and remove air in the two atmospheric pre-steaming bins. Steam from the three cyclones goes to the atmospheric scrubber or to the heat recovery unit. The unit is designed to produce 62 t/h of steam, which is used on the paper machines.
Chisholm explained that all mainline dilution and rejects dilution waters are separated. “In doing that, if we find build-ups in the rejects system, we can purge the system and make up from the clear white water side.”
The mill captures all water used for refiner motor cooling, hydraulic and lube oil cooling. It is used for dilution in the twin roll press. The whole refiner motor cooling system is a closed loop, Chisholm added. In summer, fresh water is added to keep the temperature at a maximum of 25C. The mill also has a steam chiller that takes excess steam generated in the summer to supply air conditioning to all switchgear rooms, offices, labs, etc. It is also a closed loop system.
The mill runs two paper machines equipped with Black Clawson-Kennedy Top Flyte formers (Pulp & Paper Canada, January 1985). As part of the TMP project, Pine Falls installed cleaners and savealls in autumn 2000 at a cost of $12 million.
A new distributed control system (dcs) was also installed as part of the paper machine modification. It was installed in a 3-day shutdown and tie-ins to the TMP plant were made at the same time. The DIP and waste water treatment were already equipped with a dcs.
The benefits of the TMP plant were recognized almost immediately. Chemical use has been reduced. Strength (CD tear) has improved by 30 points. The new pulp also had a big effect on burst; it is now close to 100. Paper machine efficiencies should also improve. “We’re looking for a 2.5% improvement,” Beausejour said. “We should get it if only because of the stability of the pulp supply.” The mill is producing a more consistent pulp so draws are lower and more stable.
Customers noticed the change right away, Beausejour added. “Before TMP we were marginal on linting. We were almost at the point of losing some customers because of linting. We were almost losing clients also because of strength. This is opening up new, modern pressrooms to us.”
In terms of maintenance, plate life is expected to be 2500 hours. No plates were lost during start-up. The mill, with Metso, modified the dilution zone position on the refiners, based on the Masson experience. “This took us into spec right away,” Beausejour said. Plate design has been stable. The mill shuts every four to six weeks for an eight to 10 hours for regular maintenance. Pulp storage capacity is 525 tonnes, equal to more than 24 hours of operation.
Environmentally, the new TMP process has had a big positive effect on the mill’s effluent load. “We saw a reduction, especially in BOD,” Beausejour said. “BOD and COD were 66 to 90% lower than in the previous year.”
Total suspended solids are also lower. Colour is better. Although it is not regulated in Manitoba, Beausejour noted the outflow colour cannot be differentiated from the regular Winnipeg River water.
There has been a 50% reduction in coal use for the power boilers through steam generation at the TMP plant. The mill can generate over 50 tonnes/h, which goes to the paper machines. Chemical use in the effluent treatment plant has also been reduced.
Although it meant losing jobs, operator acceptance of the project was “tremendous”, according to Beausejour. Selection was based on seniority although a baseline test was first established for those interested.
The training was handled internally by the supervisors except for some limited outside help. Beausejour noted that Tembec likes to build projects itself. There was a mix of classroom and computer-assisted training. “We started up a month ahead of schedule so there was more pressure on the operators,” Beausejour said. “The commissioning of the TMP plant was extremely aggressive.” Tessag KSH was the consultant for the TMP project. Dick Engineering handled the paper machine modifications. Dick also handled the DIP project in 1996.
Pine Falls took advantage of Tembec’s existing TMP expertise — design, start-up, construction — with the company’s Temcell and Spruce Falls Inc. mills. This included employee visits and exchanges.
There were four operators during start-up. Now, the mill is down to two per shift.
The impact of the TMP project was supposed to be a loss of 105 jobs. Because the woodroom is still in use, 20 jobs have been saved for the time being. Thirty-five people took advantage of an early retirement program.
When the sawmill is built, Beausejour said some will find employment there. Despite the loss of jobs, the union wanted the TMP plant because it knew it was crucial to the future of the mill.
There is a large First Nations population in the area. Historically, they had not been well represented in the mill’s workforce. Tembec has tried to establish a better balance in hiring. However, under the seniority system, the first ones hired were the first to be let go. Still, Beausejour explained, when the sawmill is built, 50% of the jobs will go to First Nations people. The other 50% will go to people displaced in the paper mill, many of whom are First Nations.
The First Nations will own 50% of the sawmill and 50% of a newly-formed forest management company. After five years of operation, the First Nations will have the option to buy out Tembec’s 50% share of the sawmill.
As for the problem of an aging workforce, Beausejour said the average age of mill employees is 45 years. “Retirements will be an issue over the next 10 years.”
In these days when every dollar, indeed every cent, counts, Beausejour is proud to say the proje
ct came in $2 million under budget. “It was a tight budget at $124 million and a tight schedule, but it is going well.”
In the short-term, Pine Falls will be a newsprint producer. Despite sluggish markets and prices, Beausejour said that the mill’s potential to be a low-cost producer means that it will be profitable producing newsprint. “Other Tembec mills may convert but we will focus on news.”
Pine Falls could move to 45 g/m2 newsprint from standard 48.8 g/m2. “We will look at opportunities for high-bright, but we will be at the lower end of the grade scale,” Beausejour added.
Pine Falls’ markets are North American; it has no offshore customers. About 65% is exported to the central US, as far away as Denver, CO. Paper goes out by truck (15%) and train (85%). There is a good freight system available. The mill is relatively close to the US and is only about 120 km north of Winnipeg. It is trying to optimize its customer mix with Tembec’s subsidiary, Spruce Falls Inc., Kapuskasing, ON.
The next big step, a “huge” project, Beausejour called it, will be the addition of a sawmill. It will further lower the mill’s production costs. The TMP plant will run on 100% residual chips made on site. No more deliveries will be needed. “It has been a long process,” Beausejour admitted. “The timing now is not good. It is, though, an historic project. Eleven First Nations bands are involved.”
At the official opening, Tembec’s president and ceo, Frank Dottori, said that the addition of the TMP plant means Pine Falls is poised to cut costs by $80/t, placing the mill in the top 10% among low-cost newsprint producers in North America. The next step, he added, is a sawmill, maybe two, After that, another paper machine may be considered. After much uncertainty, the mill appears to be on the brink of a bright future.