application or fertilizer.” White personally believes biochar is specifically for agriculture or soil remediation, and refers to CHAR Technologies’ different products as biocarbons. UNDERSTANDING HTP To produce different types of biocarbon, there are three types of thermal treatment processes: torrefaction, high temperature pyrolysis (HTP) and fast pyrolysis. “Torrefaction is generally a slow process – the residence time that the material is in the system for is half an hour to an hour, roughly,” White explains. “Torrefaction is generally done at a temperature between two and three hundred degrees Celsius, and what people do with that material generally is use it as a biocoal.” The next step up is high temperature pyrolysis, which is the process CHAR Technologies uses. High temperature pyrolysis falls under the category of slow pyrolysis – materials are slowly heated up between 500 and 900 degrees Celsius for half an hour to an hour. “The big difference is the quality of the product,” White says. “We drive off a lot more volatile matter, so our carbon content is higher. We’re driving off hydrogen and oxygen at those higher temperatures.” Fast pyrolysis has a residence time of one to two seconds, and is generally used to create bio-oil. “To give you the spectrum for an energy product, with torrefied biomass, you’ll get an energy density of between 22 and 25 megajoules per kilogram, depending on how it’s done. High-energy coals are 28 megajoules per kilogram. We can make a product that’s 32 to 34 megajoules per kilogram because of the high temperatures in our process,” White explains. PRODUCT PORTFOLIO are made from coal and generate a solid waste once you use them. Ours is made from organic material, and we actually generate a sulfur-rich soil amendment fertilizer when it’s done being used as a filter.” This product is made using a blend of biosolid-based fertilizers, anaerobic digestates – the solids left over from biogas plants – and some other fibres. CHAR’s London, Ont., facility is located next to a biogas plant owned by StormFisher Environmental, and uses some of its anaerobic digestate in the production of SulfaCHAR. CleanFyre is a coal replacement. “Why that’s beneficial and exciting is because that product is made from wood or woody waste – it’s carbon neutral,” White says. “So generally – high level, rule of thumb – one tonne of coal gives you three tonnes of greenhouse gas emissions. Since we can offset one tonne of coal with one tonne of our CleanFyre, each tonne of CleanFyre will reduce three tonnes of greenhouse gas emissions.” To make CleanFyre, the company uses clean, untreated recycled wood materials, predominantly shredded shipping pallets. AN INDIRECTLY FIRED SYSTEM The general process for turning these waste streams into SulfaCHAR and CleanFyre starts with loading “super sacks” – large bags used to transport both the feedstocks streams and the end products – into a feed hopper. The facility can process two super sacks at a time by hanging them above the feed hopper, for a total processing capacity of 750 kilograms per hour. Then the material goes through a bucket elevator into a rotary valve, which acts like an airlock to keep oxygen out of the system – a key factor in high temperature pyrolysis. The material is then dropped into another feed hopper and is conveyed into a slow pyrolysis kiln unit through a rotating mechanism. “The kiln unit itself is basically a large rotating cylinder that the biomass CHAR Technologies produces and markets two products: SulfaCHAR and CleanFyre. SulfaCHAR is an activated carbon. “Think like a Brita filter for filtering water, except we use it to filter renewable natural gas,” White says. “The benefit there is traditional activated carbons 4.625in x 5in -Detroit Combustion Equipment -Canadian Biomass 2019-03-29 OUTLINE.indd 1 CBM_Detroit Stoker_Spring19_CSA.indd 1 Canadian BIOMASS 3/29/2019 2:12:59 PM 2019-03-29 2:38 PM 13
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