The Dutch company, Unicorn Grain Specialties B.V., has developed a starch-based binding agent specifically tailored for the wood pellet industry. Flour Bond, as the product is called, is a binding agent for use in the manufacture of wood pellets to strengthen the bond between the wood particles which, depending on the process, can be applied from 0.5 to 2 percent of feedstock throughput. Comparative tests The Swedish University of Agricultural Science (SLU) completed a series of comparative testing, both laboratory and field tests, of the Unicorn binding agent. The tests were commissioned by the company and carried out at the Swedish Institute of Biomass Technology and Chemistry facility, fully equipped with a small Bühler production line for wood pellets where various parameters are under full control. According to the test results a number of benefits were achieved by using starch-based binding agents. Fine process benefits The addition of Flour Bond gives better pellet binding during production processing. This creates fewer fines for rework and therefore has a positive effect on either throughput at same energy use or on energy use at same throughput. Using the same energy, pellet hardness is also improved. Hardness was shown to have increased by up to 15 percent. The optimum addition of Flour Bond lies between 0 and 2 percent, as additional dosage above this has less effect on hardness. A second, but very important result of the obtained hardness, is the reduction of fines as a percentage of the final pellets. For domestic use, most countries have standards governing maximum fine levels in wood pellets. For industrial use durability is an important physical requirement. The tests show that using 2 percent binding agent, fines are reduced to 0.6 percent compared to 1.2 percent fines when no agent, was used. Ash melting The Ca/K ratio can be influenced without a negative effect on slagging though it is very difficult to predict the influence on melting temperature as it is dependent on the original mineral composition and quality of wood. Detailed information of the tests can obtained from the company. Text: Dorota Natucka PS1/4715/DN Bioenergy International PS1 2015 21 LOCATED IN BURGDORF just outside the Swiss capital city Bern, Friedli AG is a small family-run engineering company. Founded in 1991 it is firmly rooted in the agricultural feed sector having supplied and constructed grain handling and storage systems throughout central Europe and beyond. The company entered into the wood pellet industry as a turnkey supplier and installer of wood pelleting systems, just after the turn of the century and have an impressive reference list to show for it. Although they do not produce their own pellet presses – instead they partner with German company Salmatec for larger units and Italian La Meccanica for smaller installations – Friedli have developed their own hammermill, conveying, cooling and sieve solutions. ”C-series” for straw At the end of January 2013 the company launched a new turnkey straw pelletising line which had by a number eye-catching features; notably the compact width and length of the unit and ducting, as everything except the material feed-in table is skid-mounted and frame-assembled. This enables transportation in modules and quick on-site set-up. In addition it allows room for expansion, simply set up as many parallel lines as needed. – The entire line is, and of course has to be, ATEX equipment compliant given the nature of the dust explosion hazard, commented Dieter Friedli, director and second-generation Friedli, well versed in the family business during my viewing of the unit. – Most of the material handling, from after the bale shredding to pellets into the storage silo is pneumatic, said Friedli. A vertical PST shaftless spiral conveyor moved ground material from the tempering bin to the mixer. – The heart of the line is the aspiration and filtration system through which all air from the different processes must pass through to remove dust and fine particles, Friedli explained. He added that temperature and spark detection sensors continually monitor the various processes Flour Power - test highlights binding agent benefits The use of a binding agent as a means to improve the yield and technical characteristics of the wood pellet is growing in popularity. and that fire suppression systems are found in strategic spots throughout the unit. Innovative features The aspiration system aside, there are other features that stand out. Their own, very compact hammermill, only 625 mm milling area, with sieve insert, manages an output of 25 m3 material per hour. An optional dosing unit for the binder or other additive is available with injection into the mixer along with moisture injection. The press, a Salmatec, is mounted about 1 m off the ground on a sub-frame via heavy-duty anti-vibration feet. Underneath runs another self-developed innovation, the combined band cooler and sieve for the out-coming pellets. It is an oscillating and vibrating open-top band conveyor through which air is sucked. Rejected pellets, fines and dust are vacuumed back via a cyclone to the tempering bin whereas the cooled pellets are pneumatically transported to storage silo. Market outlook All in all the pelleting line did its thing at the demo, chewed up straw bales and turned them into 8 mm pellets at a reasonable pace. The obvious question is if any such straw pellet lines had been sold and, if so, where? The answer is yes, to Europe. Indeed the very unit we were looking at was being pre-delivery tested. Where to, exactly, is feedstock for a story. Text & photos Alan Sherrard PS1/4702/AS PELLETS Swiss straw pelletiser line As competition for conventional wood-based feedstock for fuel pellets increases, presumptive producers are turning their attention to agricultural residues. Something that has prompted Swiss agricultural engineering company Friedli to launch a purposebuilt turnkey straw pelletising line.
Bioenergy nr 1 - 2015
To see the actual publication please follow the link above