Surging In The South

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■ pellets article Price LogPro crane and drum debarker into a Hoffman dry chip silo with a Laidig screw and reclaimer system that sends chips to three hammermill lines. Each of three hammermill stations has two CPM- Roskamp HM 5448 hammermills for a total of six hammermills. After the feeder distributes the chips across the width of the system, the chips pass through the air density separator that assists in removing uncrushable foreign material. The 54 in. diameter rotor in the hammermill reduces chips to a nominal less than 5 mm particle size with a majority being less than 3 mm. Material drops onto a BRUKS drag chain and is bound for one of two Hoffman dry fiber silos. Three Rotex screens remove properly sized material while oversize material is conveyed to three secondary CPM-Roskamp hammermills. Material from the secondary hammermills and material that bypassed them then come together. Each stream of fiber (three lines) goes through a CPM pre-conditioner for the addition of water to ensure proper moisture for pelleting, and then the material is conveyed to CPM ripening bins that allow the moisture that was added to homogenize before entering the pelletizer. (At each of three vertical stack pellet production stations, you have a pre-conditioner feeding two ripening silos, with each ripening silo feeding two CPM pellet mills, for a total of four pellet mills at each station, making 12 pellet mills in all.) The CPM gear driven pellet mills are equipped with 450 HP motors and will produce 5 MTPH of finished pellets. The dies are 32 in. inside diameter with a 5 in. wide track. Two rolls, which are greased with an auto lube system, compress the fiber through the dies. The vertical stack design helps to limit pellet handling prior to cooling, resulting in a more durable pellet that is less likely to break down during the transportation process. The pellet mills are equipped with hinged doors for easy access along with a pneumatic hoist for maintenance. The 6 mm diameter pellets are discharged directly into the top of CPM coolers (two pellet mills supply one cooler). After cooling, the pellets are discharged onto Rotex screens to remove the fines and then conveyed to the top of one of two ACT load-out silos. Western Pneumatics supplied all of the components and ducting for the air systems for the hammermills and cooling process. Firefly spark detection and extinguishing zones begin just after the dryers and are located throughout the process risk zones all the way to load-out. Firefly multi gas detectors (MGDs) are placed inside the storage silos at Amite and the port. Each pellet silo has 1665 tons of storage capacity. The design calls for loading out of one silo while filling in the other, which provides pellets more time to cure and cool. Material coming out of the bottom of the silos is screened yet again for fines before going to truck load-out. All of the screened out fines at the pellet mills and at load-out are recycled back into the process. The mill performs various tests on its materials for durability, moisture content, particle distribution and other properties. “We want to make the pellet with the smallest particle size we can so that when they get it over there (in the UK) and grind it up, it burns with very little ash,” comments plant engineer Tommy Taylor. “We have all kinds of lab tests, but after you get experienced with a pellet mill there is a lot of look, touch and feel to see what you’ve got.” Taylor says they currently use a 6 mm pellet die and are experimenting with chamber lengths between 48 to 56 mm to identify optimal production conditions. Alex Swift is the plant manager at Amite BioEnergy, overseeing a workforce of 55. The Morehouse Bioenergy operation employs a similar number. BRUKS Rockwood chip stacker reclaimer 22 Wood Bioenergy / April 2016
■ pellets article Andritz re-sizers for oversized chip reduction at Gloster Port Facility Baton Rouge Transit LLC, a Drax subsidiary, can process 2 million metric tons of pellets per year and load and ship 40 cargo vessels per year. The facility made its first shipment in April 2015. Initially, as it started up, it was bringing in pellets from third party suppliers, but currently it’s all Drax pellets. Drax contracts with Host Terminals for port operations, with Brian Taylor as Terminal Manager. Drax owns the storage and handling equipment, but leases the land from the Port of Greater Baton Rouge. The facility receives trucks from the Gloster mill and rail cars from the Bastrop facility. Drax has streamlined the port road and entry infrastructure for incoming trucks. A truck driver drives into the unload building, scans the ticket he received at the mill, verifies the information, the conveyor system starts and he opens his two hoppers. It’s taking the driver an average of seven minutes from driving in to leaving, though they’ve gone as low as under five minutes. Rail cars come in by Union Pacific from Morehouse in 45-car trains. They sit outside the port until they’re brought in and set up on the Drax tracks. They all unload in seven to eight hours, well below the required 12 hour window. The cars advance one at a time through the unloading pit, and the four bottom hoppers in each car open and unload the pellets, about 1,000 metric tons an hour. The facility is designed to receive a combined 1600 metric tons per hour between truck and rail car deliveries. Drax is awaiting the construction of a chambering yard to support its contracted 80- car trains. Two conveyors from the truck building converge on a main conveyor from the rail car unload, and pellets pass underneath an Eriez magnet. Sensors detect any hot material. Material 140° and above will shut down the process. They prefer that the temperature not exceed 130° by much. Firefly IR detectors are located in all the transfer towers (between conveyor belts) and at the inlets into the silos. If necessary, there are three fire dumps along the way, with everything on the belt going on the ground. Pellets are programmed to move into one of two 40,000 metric ton domes designed by Dome Technology and ES2 (Engineering Systems Solutions). Inside the domes an Integris temperature control system monitors the pellets as they’re stored. Fifty-two cables with 411 sensors hang from the ceiling and provide feedback on temperature and conditions. Each dome has multiple fans to help cool pellets and control the heat. The domes are currently implementing Laidig cleaning/sweeping reclaimers for forwarding the pellets. Conveyors come out from underneath the domes to one outbound conveyor, which brings pellets to the water side belt conveyor that runs parallel to the river and transfers pellets up into the hopper at the BRUKS traveling, shuttling, luffing ship loader. The loader has 520 ft. of travel and can hit all seven holes on a Panamax with its spout, which has 82 ft. of line. The system can load a vessel at 1200 metric tons an hour. Power Station CPM ripening bin above pellet mills Once pellets arrive at the UK ports, they travel on specially designed Drax rail cars to the Drax Power Station. Drax pellets are often aggregated with third-party pellets at the port facilities and at the power station storage domes. Drax invested heavily to streamline pellet handling infrastructure at its UK power station, from the special trains to rail unloading, to screening, storage domes, transfer tower, more screening and then feeding into the boiler house, where pellets are pulverized back into wood fuel for the boilers. Drax Biomass Director of Communications and Policy, David Malkin, comments, “Apart from just the massive investment, what is most noteworthy is that in the process of converting those boilers to run on 100% biomass, we were able to make technical modifications to greatly minimize any impact on efficiency and (power) plant output.” He adds that one of the benefits Drax supplies to the UK is flexible output, as each unit can ramp up or down to between 200 MW and 645 MW. “As the UK makes that transition to 24 Wood Bioenergy / April 2016
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