CHIPPERS
Acrowood produced ‘mini chips’ The Acrowood slant chipper round wood to produce fuel pellets. High fuel oil prices, coupled with an increasing demand for pellets have spurred significant growth in the pellet industry. Acrowood has used it’s experience in chipper manufacturing and focused on the production of small chips for the pellet industry. Producing smaller chips using a disc chipper reduces the horsepower required for the primary breakdown of the logs. The smaller chips are dried more easily and require less milling to
be converted into a size suitable for pellet production. Acrowood slant disc chippers have been producing mini-chips commercially since 2008. Pulp chip applications of slant disc chippers have been in operation since 1979. When configured to cut a small chip length, a slant disc chipper produces uniformly small chips. The following photos compare the 1 ⁄4" chips from the test centre chipper with those from a production chipper running a 3⁄8" chip length with a worn anvil.
The chips produced by both chip lengths were consistently thin and maintained roughly the same thickness to length ratio that is typically found in larger pulp chips produced by a disc chipper. Both 1⁄4" and 3⁄8" chip samples were reviewed by a dryer manufacturer who indicated that either size would work well in their dryer. The very few overs present in either chip sample were still thin and would pose no problem for drying. A rotary screen with single deck could also be used to remove the largest overs. The Acrowood slant disc chipper has long been used to efficiently reduce wastewood from sawmills, producing high quality pulp chips from sawmill residues. Typically fed using a vibrating pan conveyor in waste wood chipping applications, the chipper is selffeeding and requires no powered feedworks. Many chipper manufacturers believe that in order to manufacture micro-chips, a proven and reliable chipper for conventional chips only needs to be set up to cut a small size chip. This thinking comes from their experience making conventionalchip chippers for the pulp and paper industry. What these suppliers fail to recognise is that cost effectively making true microchips is far more difficult and complex than this. Because of CEM machine’s extensive knowledge of chipmaking, CEM recognised immediately that true micro-chips form and behave differently in many ways from conventional chips. CEM therefore invested in researching and developing new patented technology for efficiently
38 International Forest Industries | APRIL/MAY 2013
producing true micro-chips specifically for the pellet and biomass industries. “Largely because the primary end product of bio-energy processes is an energy source, the total energy and biomass consumed in producing the system’s end product becomes critical in the entire process’ competitiveness,” the manufacturer stated. “While clearly only energy-positive systems can survive, those which are more energy positive will outsurvive others in market hard times.” While making micro-chips from logs requires more energy than making conventional chips from logs, it is well known that refining conventional sized chips to microchips through the use of reducing machines requires substantially more total process energy, unnecessarily creating fines and dust, which often become biomass system losses. Such inefficiency and cost can rarely be borne by most bioenergy processes, as the additional processing machinery carries with it problems associated with the equipment’s initial cost, wear, and maintenance (e.g. replacement of wearing parts such as hammers and knives) and invariably results in lower system uptimes and increased total energy consumption. The preparation process that will survive when others do not, will in a single cut, substantially reduce a whole log to a small particle size such that only minimal additional processing and energy are needed to refine the chip, for instance, to drying mill feedstock. “Anyone entering into a biofuel business needs to investigate why CEM’s equipment and the microchips it produces is the best solution for this process.” GreenMech continues to be a leader in innovative technology for the arboricultural industry with the introduction of its Arborist range of 150 mm (6 in) hydraulic wood chippers. The series of two road-tows and one tracked unit have each been engineered to meet the tough demands of