A productive crane solution
The installation of an overhead crane–supplied by Kaverit Steel and Crane with the boom and grapple from Rotobec–has been a solid and productive solution for straightening out misfed and skewed logs at BC pulp mill Celgar.
By Tony Kryzanowski
In the case of the installation of new equipment at the Celgar pulp mill in Castlegar, BC, the results speak for themselves. The installation of an overhead crane to improve log flow from the infeed deck to the wood room at the pulp mill has improved wood room productivity by 20 per cent. Prior to the overhead crane’s installation in November 2003—at a cost of $350,000—the wood room was handling an average of about 41 bundles of logs per day. That has now increased to 50 bundles per day.
The numbers are indeed impressive. “Two records were broken this year,” says project engineer Paul Garthe. “We processed 87 bundles in one day, and there was one month when we processed an average of 57 bundles per day.” Two other factors have contributed to this productivity improvement. Changes to log specifications have improved the quality of logs coming into the wood room, and there has also been an increased emphasis on equipment maintenance. Log bundles arrive by water year round at the pulp mill and are lifted out of the Columbia River using a Colby crane.
This 60-ton capacity crane, equipped with two grapples, was designed to lift whole bundles. Its job is to lift bundles on to the log deck, where steel cables holding the bundles together are cut and removed. The logs, measuring 50 feet long, travel along the infeed deck to the primary sort station where they are sorted according to their diameter. The pulp mill has a large and small log line leading to its wood room where the logs are debarked and whole-log chipped. A 27-inch Nicholson ring debarker debarks logs on the small log line, while a 44-inch Nicholson ring debarker debarks logs on the large log line. “The sort station was identified as the bottleneck in the wood room,” says Garthe. “The new crane’s function is to straighten misfed and skewed wood.” It is an overhead crane with a logging-truck style, self-loader boom and grapple attached to an inverted swivel. The crane has a rated boom capacity of 8,000 lbs. The runway it operates on is 360 feet long, with a width of 66 feet.
The runway beam rail varies from about 30 feet above the deckto 60 feet above the lower road. The crane attachment can rotate 360 degrees and has a 25-foot reach. An Edmonton, Alberta-based company, Kaverit Steel and Crane, which specializes in the manufacture and servicing of cranes, supplied the crane portion of the project. Quebec-based manufacturer Rotobec supplied the boom and grapple portion through its Western office in Oyama, BC. Rotobec specializes in supplying logging truck self-loaders and related equipment. Employees at the Celgar pulp mill call the new crane the “picker” to differentiate it from the larger Colby crane. “This Rotobec loader configuration is definitely unique,” says Rotobec West branch manager Mark Shukla. “The Celgar loader was the first time a Rotobec loader had been designed to be mounted upside down. The Rotobec loader, with its continuous rotation, mounted on a Kaverit crane allows the unit superior range of movement.
It can literally get to every part of the Celgar deck with no limitations.” Prior to the picker’s installation, the large Colby crane was used to straighten out or remove fouled-up logs on the infeed deck. There were a number of problems with this method. The crane had difficulty grabbing individual logs with its large tines. Secondly, the sorter operator sometimes had to wait for the Colby crane to be available if it was busy lifting a bundle or unloading a truck. Finally, the large crane occasionally did damage to the infeed decks and drive shafts by inadvertently pulling on them while attempting to fix a foul-up. Wood room operations supervisor Bill Carlson says the installation of the picker has really helped the wood room overcome the problem of foul-ups on the infeed deck, while keeping the deck and Colby crane in good condition. “We have more versatility with the new crane,” he says. “This saves time, and there is also less maintenance required particularly on the Colby crane, since there is less wear and tear on it.”
Garthe says the crane has exceeded expectations and has delivered some unexpected benefits. In addition to reducing downtime and extending rope life on the Colby crane, the new set-up has the ability to deal with problem logs on the infeed deck without the need for chainsaws or manhandling logs. It can also pick up cables that get carried into the sort station or roll cases, and its installation has avoided the additional expense of having to potentially widen some decks to deal with logs that fall off and skew.
Celgar came up with the preliminary concept for the picker, with Kaverit and Rotobec doing the design, engineering, and supply of the finished product. Kaverit custom designed the crane. Rotobec custom designed the loader/picker. “This situation is an unusual loading condition for a crane,” says Garthe. “Normally, cranes lift straight up. Our situation imposes lateral forces, torque and bending moments on the crane. So the crane needed to be custom engineered by Kaverit to ensure it could be operated safely.” A few modifications have been made to the picker since its installation.
These include water drain holes, making the hydraulic power unit level indicator more visible, adding safety hoops, extending ladders and the runway walk-on platform, adjusting the brakes, and adding grease lines for areas difficult to access. Shukla says from Rotobec’s perspective, the picker has worked very well. “We had some concerns about the range of movement of the loader in relation to all the fixed points of the overhead structure,” he says. “However, the operators have been very careful with the loader, and have factored its range in when they operate it.” The future of the wood room also figured prominently in the pulp mill’s decision to adopt this design as the most successful and economical solution. The mill uses 2.5 million cubic metres of chips annually, with only 300,000 cubic metres of that supplied by the wood room.
Chips produced in the wood room have historically been among the most expensive chips consumed by the pulp mill compared to chips delivered to the site, because of the high cost of raw logs. However, these chips play a critical role in maintaining a consistent overall chip supply to the pulp mill, especially when chips are in short supply. Last fall, for example, chip supply from outside sources to the pulp mill was marginal because forest fires resulted in the closure of forest activities. So, given the importance of the wood room, the pulp mill needed to find ways for it to operate as efficiently and productively as possible.
Wood room personnel investigated a number of other solutions, but they either did not have the ability to reach the entire infeed deck, it required the hiring of extra staff, or it was difficult to use because of poor visibility. “Our Kaverit/Rotobec solution gives us better dexterity in handling the logs, with less wait time when a problem occurs,” says Garthe. “The operators who have the material flow problem can now handle the problem themselves with the picker.” In addition to maintaining log flow, the picker also comes equipped with a cable cutter. This is the first time a cutting device has been designed into a Rotobec grapple and it gives the pulp mill the option of using the picker to cut bundle cables anywhere on the deck. Cables have typically been cut using an oxy-acetylene torch behind protective bunks. Because the cable cutters spring out after a cut, making it difficult to grab cables to pull them out, Celgar has added pinch points on the jaws to grab the cables more easily.
The picker also comes in handy for maintenance staff, who use it to assist in changing deck chains, drive units and shafts. It helps them do their job more quickly. Since the picker works by remote control, it can be operated from anywhere on the deck or at ground level. Celgar has had a few minor problems with the remote control, and is working with the supplier to work out the bugs. The pulp mill is Celgar’s only facility and has been operating since 1960. It has 418 employees, and produces 430,000 tonnes of bleached and semi-bleached kraft pulp per year, using fir, larch, hemlock, spruce, balsam fir, pine and cedar ranging from 12 to 14 inches in diameter. The current owners, the Royal Bank of Canada and the Royal Bank of Scotland, have been looking for a buyer for the facility, and productivity improvements like those at the infeed can only help that endeavor.
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