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More Than “Just a Mill”

July 17, 2008

By Rodden, Graeme

An eager and educated workforce has set Botnia’s Fray Bentos mill off on the right foot as startup set a record and customer feedback has been positive Although Botnia’s senior vice president, Uruguay operations, Timo Piilonen, may call it “just a standard pulp mill”, Botnia’s impressive new complex in Fray Bentos, western Uruguay, about 300 km north of Montevideo, is really much more than that.

Botnia’s first major investment outside of Finland and Uruguay’s first mega pulp mill has been one of the most talked about pulp and paper projects. At capacity, the $1.2-billion bleached eucalyptus kraft pulp mill will produce one million tonnes/yr. With a successful startup in late 2007, the mill met its nominal daily capacity (about 3,000 tonnes/day) just 145 days after startup. This is a new record for startup, the previous best being 171 days.

When asked if the one million-tonne/yr pulp mill is the new benchmark, Piilonen says that it is more a “symbolic” number, that one million tonnes is no limit, citing the Tres Lagoas mill in Brazil that will produce 1.2-1.3 million tonnes/yr.

Other than the two pulp dryers and four baling lines, the mill is single line. There was talk of a single dryer as well but Botnia opted for the safer option of two. Each can produce 60% of capacity. Also, the local electrical grid has some limitations and two pulp machines makes it easier to keep the mill in balance. The recovery boiler’s nominal capacity is 4,450 tonnes/day of dry solids but Piilonen says it can run more than 5,000 tonnes/day of dry solids.

Prior to becoming a pulp production center – the mill is about 5 km from town Fray Bentos was famous in the first half of the 20th Century as one of the great meat processing centers of the world. At their peak, the packing plants could process 7,000 head of cattle daily. The industry employed 5,000 people, speaking 60 languages. Piilonen points out that Fray Bentos was the first place immigrants went to find work. It is also, he adds, the first location in South America that enjoyed electrical lighting.

However, with the glory days behind it, Fray Bentos had been left behind, until Botnia came calling.

Wood was the reason

With all the attention centered on Brazil becoming world’s leading pulp producer, why choose Uruguay? The original reason was wood. “We had the ‘basement’ here,” Piilonen adds. “The critical volume of wood was in our hands.”

This came about through the work done on the plantations and through tripling the land base through purchases. In the future, Botnia will be able to produce all the wood it needs in-house if necessary. The third-party wood providers that Botnia uses will give the company flexibility in the future.

As the plantations have begun to mature, Piilonen says the time was good for building the pulp mill. Otherwise, the wood would have been exported.

There were other benefits to building in Uruguay that made the Finns more comfortable. Politically, Uruguay is perhaps the most stable country in South America. It has a good educational system with a high degree of literacy among its population.

All of Fray Bentos’ production will be sold through Botnia’s sales organization. On average, 70% will be sold to Botnia’s shareholders: M-real and UPM. Another 30% will be sold as market pulp, going mainly to the company’s existing customers that buy softwood pulp from it. This way, Piilonen says, they will be able to combine the benefits of the two. About 70% of the pulp is destined for European customers; the rest to China.

Piilonen expects the main end use for Fray Bentos’ pulp to be printing and writing grades, both coated and uncoated. There may be some tissue made as well.

Although it has only been operating a few months, he adds that customers are happy. “Quality has been very high from the beginning and customers who have done trials have had no negative feedback.

The mill itself employs more than 300 people. However, with a fair degree of outsourcing, Botnia’s employees number about 190. Kemira, the mill’s sole chemical supplier, has 45 people on site and Andritz, the main machinery supplier, has 90 for mill maintenance. There are also some smaller outside contractors responsible for such things as logistics and the port.

Preparing the staff

In 2004, eight young Uruguayan engineers were chosen to follow a one-year pulp and paper course at the Helsinki University of Technology. Then, they joined the project team, helping with the project engineering for the next year while living in Finland. The project organization crossed the ocean in mid-2006 to take up residence in Uruguay.

The operators are all Uruguayan and most are graduates of the country’s universities and technical schools. The average age of workers in the mill is late 20s.

The supervisors and operators were then given a three-month course in Finland that included a stint working in some of Botnia’s mills. This was followed by theoretical training back in Uruguay. Aracruz also helped out, hosting the operators in its mill for a 2- 3 week work placement.

There is no heavy process industry in Uruguay so Piilonen admits that it was difficult to find people. But, their basic training/ education is so good, Botnia was able to choose the best people. “We are very happy with them. Their attitude is excellent and they have adapted well to the pulp mill environment.” In some ways, he notes, training them was easier, because they had no preconceived notions about how a pulp mill should operate.

Botnia opted for well-proven technology, hence, Piilonen’ comment about the “standard pulp mill”. Still, he points out that Fray Bentos is still the world’s most modern pulp mill. And although it’s proven, it is still the best available technology (BAT) that was used throughout, an important factor for the environmental assessment process.

Finnish trials set the stage

Trials were conducted at Botnia’s Kaskinen, Finland, mill and on clients’ paper machines to optimize the pulp “recipe”. This also helped design the bleaching sequence. The Finnish influence is also easy to see when entering the mill’s administration building: lots of wood used in the interior and lots of light. The light and airy look continue in the machine room.

The first foreign mill project for Botnia was also the first Uruguayan project for Andritz. It had done the bulk of the work at the Kaskinen mill 30 years previous, setting the stage for a long relationship. The Fray Bentos project was its first opportunity to supply a complete, large-scale pulp line: woodyard, fiber line including bleaching, drying, baling, chemical recovery and maintenance. It also provided an IDEAS Simulation and Control dynamic process simulator that was used for training that can be used for ongoing education.

Logs are delimbed and debarked (partly) in the woods. Once a log enters the chipping process, about 24 hours later, it leaves as pulp.

There are two chipping lines, each with a capacity of 330 m^sup 3^/hr. At the beginning of each line, there is a PowerFeed infeed conveyor and small debarking drum. This removes whatever leftover bark there is on the log, removes sand and impurities and equalizes log flow to the chippers.

A two-stage log washing system removes residual stones, sand and bark. The logs are fed to one of two HHQ chippers, designed to produce homogenous chips. There are rotating stacker-reclaimers for each of the two chip piles: one of Eucalyptus Grandis; one of Eucalyptus Dunnii. The first-in, first-out principle is used.

Chips are mixed and screened prior to being sent to the digester.

The two-vessel continuous digester uses Andritz’ Downflow Lo- Solids^sup R^ cooking technology. It is designed to increase digester capacity while producing clean pulp.

The TurboFeed^sup R^ system moves chips rapidly to the top of the digester, eliminating some equipment and improving efficiency. The digester is designed to produce 3,200 air dry tonnes/day.

After the cooking, the pulp passes through three Drum Displacer^sup R^ (DD) washers. There are nine DD washers in total in the fiber line. Following washing, there is an oxygen delignification stage, making the pulp easier to bleach. Screening removes knots and other rejected material. Another wash stage precedes bleaching.

Patented bleaching sequence

The bleaching sequence is one part of the process where Botnia did opt for something slightly different. It uses Andritz’ patented A-Stage(TM) for the first stage of the sequence. The A is a sulfuric acid stage to remove hexeneuronic acid, of which there is a high content in eucalyptus pulp. The full sequence is ADE^sub OP^DP. The brightness target is ISO 91.

The four DD washers in the bleach plant help save on chemical consumption. They also allow for a high degree of filtrate recycling without building high levels of chemical oxygen demand (COD).

As noted, there are two Andritz two pulp machines, each capable of producing 1,800 tonnes/day. Pulp is screened (5-stage system) and dewatered (twin wire formers, trim width 5.3 m) prior to entering the dryer. There are 27 drying decks and two cooling decks.

The cutter layboys cut the pulp into sheets, which are then stacked into bales (250 kg). The baling, wrapping, marking and conveying system is totally automated (consisting of four separate Oval baling lines). Two of the lines can prepare tie sheets, i.e., use less wire than wrapping individual bales The warehouse at the mill is virtually empty as the main storage area is at the main port of Nueva Palmira, an 8-hr barge ride away (100 km).

As with most modern pulp mills, the Fray Bentos mill is more than self-sufficient in energy. It can deliver up to 30 MW back to the national grid.

Andritz also supplied the entire chemical recovery island. This includes the 7-effect evaporator set that can remove up to 1,100 tonnes/hr of water from black liquor. The process modifies black liquor viscosity so that it can be concentrated to 80% dry solids.

The black liquor recovery boiler features the Vertical Air(TM) system that optimizes burning to minimize air emissions. The recovery boiler building is 80 m high and the stack reaches 120 m. Andritz claims that SO^sub 2^ emissions can be near zero. Inorganic smelt from the recovery boiler is collected in a dissolver. This green liquor is then causticized to produce white liquor and lime mud.

The white liquor system can deliver up to 10,000 m^sup 3^/day of white liquor for the fiber line. Two X-Filter(TM) units filter the green liquor. These produce a high-quality liquor by removing non- process elements. A CD-Filter(TM) further purifies the white liquor.

The lime mud is sent to the kiln that can produce 830 tonnes/day of lime needed to make the white liquor. It is 135 m long and 4.75 m in diameter. The primary fuel is oil although methanol and hydrogen are also used.

The entire recovery system is very efficient. Less than 1% of the initial raw material has to be discarded.

For electrical power production, Siemens supplied the two turbine- generators.

They are fed with high-pressure steam from the recovery boiler and provide low-and medium-pressure steam for the pulping processes.

Controlling all this is Honeywell’s millwide Experion Process Knowledge System (PKS). The PKS goes beyond the traditional distributed control system (DCS) by unifying the operators with process variables, asset management and business requirements. The PKS extends to the on-site Kemira facility.

The system is also tied to Honeywell’s quality control system (QCS) with ProFlow CD actuators and a control package for basis weight and moisture control. The ProWeb monitoring system alerts operators to defects.

The Honeywell scope of supply includes the OptiVision business optimization package with the Quality optimizer and a process historian feature.

There are three control rooms in the mill. The main one is in the administration building. From here, operators control the fiber line, recovery island, chemical plant and water and effluent treatment plants. There are smaller control rooms in the woodyard and machine room.

ABB delivered the entire drive and electrification system for the mill, including 2,000 low-voltage motors, switchgear, distribution transformers and single drives. The drive system for the pulp machines included control application, motors and ACS800 drives.

Vaasa Engineering of Finland supplied the main electrical distribution system including design, delivery of equipment and cable, installation and testing of a 150-kV switchyard, 33-kV GIS medium voltage switchgears, 33-kV harmonic filters, protection relays and a SCAD system for the plant.

Keeping it clean

Degremont supplied the incoming water treatment facility (1,720 L/ sec capacity) as well as the effluent treatment plant. Degremont also supplied the demineralized water treatment plant that feeds various processes in the mill. This water comes from the incoming water treatment plant.

The effluent treatment process uses activated sludge and consists of primary treatment (neutralization, primary clarification [one 46- m dia unit], equalization and cooling); secondary treatment (aeration, decantation [two 65-m dia. units], recirculation/sludge extraction and nutrient addition); and sludge treatment (mixing, dewatering and thickening).

Keeping a million-tonne/yr pulp mill in good working order is no small feat, even if it is a new mill. Botnia opted to concentrate on the business of making pulp and has outsourced the maintenance business to Andritz and its Overall Production Efficiency (OPE) program. Piilonen stresses that the work is done in cooperation between the two parties. Botnia mapped out what it thought should be done and when. “The plans were done together,” he says. This applies to the chemical plant as well.

Andritz has done some maintenance services for Botnia’s Finnish mills since 2002. The 5-year plan at Fray Bentos includes planning, pre-engineering, training, implementation and all preventive and corrective maintenance. One of the goals is to achieve better productivity (maintenance costs per tonne of pulp) at Fray Bentos than in Botnia’s Finnish mills

Piilonen expects that there will be one long (one-week) annual shutdown as well as a shorter one. But, this remains to be seen as the mill is new. The maintenance team has worked to develop local contacts so during shutdowns, it can call upon companies that have had experience (during the construction period) with the equipment.

Piilonen was not willing to go out on a limb about future plans. The mill has a welldesigned layout with the production process going in a straight line from woodyard through shipping. And, there is plenty of space for another line.

But, with the work involved in getting this mill to capacity with a quality acceptable to customers, it’s too soon to be talking about expansions. Although the space is there, there is also the question of a sustainable fiber supply.

For Botnia, it was an adventure to come to Uruguay. It made a brave decision to move out of its comfort zone. And, due to outside influences, there were times that it must have wondered if the project would ever come to fruition. But, Botnia’s perseverance and belief in the project have paid off and now it can concentrate on what it does best: making pulp.

The temperate climate allows Botnia to keep the bleach plant uncovered

Timo Piilonen: The mill exceeded the expectations of a challenging startup curve (Photo courtesy of Andritz AG, photographer Thomas Wedderwille)

There are two chip piles: one for Eucalyptus Grandis (left) and one for Eucalyptus Dunnii

chemical facts

Good “chemistry” between partners

The chemical project at Fray Bentos is a new concept for Kemira. The Finnish company is responsible for all the chemicals for the mill’s pulping process, including chlorine dioxide, hydrogen peroxide and oxygen for bleaching. Kemira’s investment at Fray Bentos is in excess of $100 million.

All chemicals used in the mill pass through Kemira and many are made on site.

Technically, the system is closed. That is, it is integrated with the mill so that the pipes carrying the chemical are linked directly to the mill. As well as supplying chemicals, Kemira also provides technical support in an effort to help Botnia be cost-effective while producing high quality pulp with minimal environmental effect.

The principle is again that Botnia can concentrate on its core capability: making pulp.

The sodium chlorate plant can produce 60,000 tonnes/yr; the chlorine dioxide plant, 10,000 tonnes/yr; the hydrogen peroxide plant, 16,000 tonnes/yr; and the oxygen plant, 65,000 tonnes/yr. Some 15 other chemicals are imported, including sodium hydroxide and sulphuric acid.

Kemira acquired Erco’s R11 technology for producing chlorine dioxide while the sodium chlorate and hydrogen peroxide technology are its own.

There are two pulp machines; each can produce about 60% of total production

Degremont supplied the incoming water treatment and effluent treatment systems

The recovery boiler is among the world’s largest; the building itself is 80 m high

To read more articles on Pulping, visit our Pulping Technology Channel at www.risiinfo.com/technologychannels/pulping

By GRAEME RODDEN, Editor

Copyright Paperloop, Inc. Jun 2008

(c) 2008 Pulp & Paper. Provided by ProQuest Information and Learning. All rights Reserved.