Canadian Biomass Magazine

Drying Technology

October 18, 2010
By Canadian Biomass

From biomass combustion to wood pellet and briquette production, drying your biomass can be a key step in your plant’s processing efficiency.  Wood biomass dryers come in a variety of types, temperatures, and configurations.  Canadian Biomass provides a comprehensive guide of the biomass drying technology available to help you in considering the best system for your particular application. All information is provided by the manufacturers.

From biomass combustion to wood pellet and briquette production, drying your biomass can be a key step in your plant’s processing efficiency.  Wood biomass dryers come in a variety of types, temperatures, and configurations. Canadian Biomass provides a comprehensive guide of the biomass drying technology available to help you in considering the best system for your particular application. All information is provided by the manufacturers.

Read our latest spotlight on drying technology here:

swisscombiThe Swiss Combi belt dryer is a proven low-temperature belt dryer. It can use waste heat from other processes as a heat source. A wide variety of bulky biomass can be dried, such as sawdust, wood chips, and bark. Because of the low drying temperature, no significant volatile organic compounds are emitted. The multi-layer drying process (up to three layers) makes it possible to dry the product to 1% moisture content with excellent efficiency. It also minimizes dust emissions and allows full saturation of the drying air. This is because the lowest layer of material is wettest and acts as a filter. Swiss Combi has re-engineered its low-temperature Kuvo belt dryer. The new Kuvo is stronger, modularized, and can be manufactured more cost effectively. All components can be transported in standard size trucks or 40-foot containers. Module assembly on-site is fast and easy with no welding required. Inspection and maintenance access has been optimized. The lateral sealings have been improved for reduced air leakage and lower dust emissions. Depending on local requirements, various noise reduction concepts are available.

andritzAndritz offers a complete range of biomass drying solutions, and technology is selected based on customer requirements, raw material, and available heating media. Belt dryers are the primary choice for low-value heat sources and are easily maintainable and cleanable. They use energy sources such as hot water, steam, hot oil, or flue gas. Pneumatic dryers are typical for lime kiln and boiler firing. Pneumatic dryers offer a high final dryness, exceeding 96%, and a high degree of milling for small particles and clear cut-off. These dryers are generally heated by waste gas flows. Rotary drum dryers are the technology of choice for high-value heat sources. They have very forgiving characteristics and good air circulation, which means low oxygen content. They offer simple operation and a high degree of automation, along with low exhaust gas flow and high energy efficiency. Fluid-bed dryers are suitable for particulate and granulate material. With or without an internal in-bed heat exchanger, the high heat transfer rate makes drying and cooling efficient. For more information, contact Joanne Turnell,, 289-239-9456.

earthcareEarth Care Products offers drying equipment supply and engineering along with torrefaction technology. Its drying systems comprise proven state-of-the-art equipment with 38 years of continuous improvement, providing customers with some of the best and most efficient dryer systems available. Earth Care Products’ drying system starts with its patented Z8 dryer. This unit implements a reverse flow, eight-zone drum design for increased materials exposure to hot gas turbulence, increasing drying efficiency. The material passes through a single-pass section and then through a reverse flow, triple-pass section, and then repeats the process. The reverse flow design uses increasing velocity through the drum, creating more uniform drying of different particle sizes without overheating fine particles. This design has been shown to prevent volatile organic compound emissions from drying wood biomass. Earth Care Products provides simple dryer seals, wedged tracks, full tooth sprockets, stainless skin, and heavy-duty trunnions and drives for long service life. The company offers designed biomass burners to compliment its Z8 dryer, along with full control packages and material handling equipment.

bruksThe Bruks bed dryer is intended for use in drying wood chips, sawdust, hogged fuel, and biofuels. Materials are spread evenly across a wide bed and pulled slowly and gently over a steel plate with small holes (no wire screens). Air is pushed through the holes under pressure, which drives the moisture from the bottom of the mat to the top. As the material moves through the dryer, large volumes of steam escape through the top of the mat, leaving the dried materials behind. An infrared moisture sensor monitors the dryer’s progress and controls the position of the final skimming screw that ensures the output moisture level. Low drying temperatures (120˚C maximum) keep volatile organic compound and particle emissions to a minimum, making it possible to meet even the most stringent environmental permit limits without having to treat the exhaust air. The interior is fully accessible while the dryer is running.

saimatecSaimatec Engineering Oy of Finland is bringing new technology for drying various types of biomass to the worldwide market. These highly energy-efficient drying systems are suitable for various types of biomass, including wood chips, bark, sawdust, and even sludges when mixed with other biomass. Other key benefits include robust, reliable construction that takes only a small footprint in the plant area, as well as flexible integration with various external processes. The vertical silo-type dryer technology has been successfully test run at the full-sized test plant at Saimatec’s facility in Savonlinna, Finland. Various types of mainly forest-based biomass (chips, bark, etc.) have been dried in these comprehensive tests. Potential applications include heating plants, combined heat and power plants, wood pellet plants, and biorefineries for fuel and chemical production. For more information, contact Heikki Rasimus,, +358 10 525 8109.

altentechAltentech’s new, direct-contact, vertical, small-footprint biomass dryers have been engineered to dry virtually any type of biomass, including but not limited to wood fibre, agricultural byproducts, peat residue, and even sewage sludge, from a moisture content as high as 80% down to 10%. Furthermore, they can do this cost effectively, consistently, and quickly, allowing for applications in high-volume industrial installations such as the seamless integration of biomass into coal-fired operations. Compared with conventional dryers that require mass air movement, Altentech’s biomass dryers’ unique, mild, “in vacuum” process results in greatly reduced particulate emissions. Additionally, they are designed to be integrated with a variety of heat sources, including high-efficiency cyclone burners and/or waste heat where available.

agroenergienAgroenergien’s BDS-C is a biomass drying system built in a container. It is a compact belt dryer with a synthetic belt. Its uncompromising robustness, drying results, and availability make it useful in various fields. The BDS-C dryer has many advantages, including clear intersections, easy adaptation to existing equipment, and short assembly time because of pre-fabrication. It is portable and can be made ready for use within a minimum time. The container is weatherproof and can be placed outside; no building or roof is needed. Most of these dryers are placed next to biogas plants and use the thermal output (70–90˚C) from the combined heat and power generation unit to dry digestates up to 85% dry substance. The BDS-C can also be used to dry other products such as wood chips, grains, and sewage sludge.

aeroglideBuhler Aeroglide offers industrial rotary and conveyor dryers for biomass products, including wood, pulp, and recycled/waste materials. Each system is capable of using multiple heat sources, including direct-fired biomass burners, low-pressure steam, or waste heat from power generation or other allied processes. Rotary driers are used to dry wet products such as DDGS or cellulose products such as wood chips or sawdust to a stable final moisture content. Aeroglide rotary coolers are used for final cooling or tempering of the dried product prior to storage or loading. Conveyor driers are suited for a wide range of material requiring high throughputs with low operating temperatures or long retention times. This technology has been successfully deployed with harvested organic materials such as wood or cellulosic feed stocks and recovered waste streams. The end products can be pelletized for direct combustion or further processed for cellulosic ethanol, gasification, or torrefaction. For more information, call 919-851-2000.

stelaStela Laxhuber’s low-temperature drying system is a highly efficient and individually adaptable modular plant system. Biomass is fed directly into the dryer by a conveyor and spread evenly onto the drying belt by a distribution unit. A level adjustment unit modifies the biomass layer thickness to meet specific drying parameters. Hot air flow ventilates the biomass and dries the wet product continuously. This convective drying method is gentle, heating the biomass only marginally, especially during the first drying step. The heat can be supplied from multiple sources, including hot air, flue gases, hot water, and steam. An online moisture sensor controls the drying process to maintain constant final moisture content within narrow tolerances. Wet and dry cleaning systems clean the belt at infeed and discharge to maintain trouble-free, continuous operation. Additional safety devices provide automatic shutdown in emergencies. Belt run, tension, and alignment are monitored continuously and adjusted as necessary. Multi-vent technology allows selective air control for individual drying stages, increasing the drying speed and reducing noise and power load. Stela Laxhuber has supplied and installed many belt drying systems over several decades and can provide systems engineered to suit specific needs.

geabarrrosinGEA Barr-Rosin energy-efficient Superheated Steam Dryer (SSD) is an indirect-heated pneumatic dryer in which water in the product produces steam at 0.5 to 4 bar gauge pressure. There is no air or flue gas in contact with the product, and no emissions to the atmosphere produced. Boiler steam, flue gas, thermal oil, or even hot water can be used as indirect heating media. In comparison to open-type dryers, the SSD consumes less gross energy (about 1,280 BTU/pound of evaporated water). The heat recovery in the evaporated water (steam) is about 1,025 BTU/pound. Sludge, bark, and wood waste can be dried to 90–95% dryness before being used as fuel. This results in a maximum and stable production of heat from the boiler, which can be used for heating or as power production in a steam turbine. Only part of the steam is used for heating the SSD; about 80% is recovered by using the generated steam from the dryer in a pulp and paper or other process.

kdsThe wood pellet industry is developing a reputation for being risky because of significant fires and explosions. The Kinetic Disintegration Energy (KDS) Micronex uses new technology to pulverize and dry material in one operation, without fires. The KDS Micronex grinder/dryer will accept any fibre type, moisture content, or size of inbound material up to six inches in length. The KDS Micronex has undergone more than 10 years of development without any fires. It dries material, reducing moisture content from 70 to 5%, and has the capability to pulverize six-inch material down to 200 microns, using no high-cost fuel for drying. It can process wood, straw, manure, sludge, and more. It has low operating and capital costs, with easy permitting, and is proven technology, with over 40 machines sold worldwide. A pellet operation that requires dried sawdust and shavings but can’t afford the typical grinders, rotary dryer, shaker screen, stoker retort burner, dust collection, and emissions system, including WESP and scrubber, can have its pellet manufacturing plans made reasonable again by the KDS Micronex. One simple machine can change an operation’s installation requirements. For more information, call 503-644-6699 or e-mail

solagenMore than 25 years of experience has taught SolaGen that developing a good drying system begins with experienced process engineering and equipment designs that are tailored to suit the specific material and load to be dried. SolaGen pioneered the single pass dryer with satellite center assembly, which has become the industry standard. In addition, many other proprietary features like bolt-in flighting and drive teeth allow for greater longevity at a lower maintenance cost. SolaGen’s rotary dryer systems are all of heavy-duty industrial quality and renowned in many industries for their low maintenance, high efficiency and evaporation rates, and low stack emissions. SolaGen offers many standard dryer designs, ranging from 3 to 20 foot diameter with lengths up to 60 feet, but can design virtually any system the customer’s needs require. When coupled with its state-of-the-art Enertek Suspension Burners, rated from 10 million to 160 million BTU/hour, and its recycled gas systems, SolaGen offers comprehensively designed drying systems.

dieffenbacherSchenkmann-Piel-Engineering, a member of Dieffenbacher Group, has long and worldwide experience in drying technology. For wood particles as used in pellet production, single-pass drum dryers have proven to be an optimal solution. In this system, the wood material feeds into the dryer drum, where it comes into contact with the heated steel interior. The heat supply is provided by hot air from solid fuel combustion or hot gas generation. Heat transfer takes place via contact with the steel parts and convection between the hot air and wood particles. The internal flights of the drum and the hot air move the material towards the discharge area. The principle of this drying system is that fine and dry particles move faster while bigger material with higher moisture moves slower. This results in very homogeneous final moisture content. A large temperature difference gives a low gas volume and fan capacity. The exhaust volume can be reduced by gas recirculation. The main features of these dryers are low thermal and electrical energy demand, low exhaust volume, little space required, and low investment cost.

energyunlimitedEnergy Unlimited Inc. drying systems have been in production since 1985. With processing rates from 1 ton/hour up to 15 tons/hour and moisture reduction capacities from over 60% in to less than 10% out, these systems offer a wide range of diversity for moisture reduction. The systems are offered as complete packages, including solid fuel burner and a variety of dust control equipment. Once installed, the system is ready for wet product in-feed and dry material out-feed, which are also available options. Offered in both triple and single pass, the wet product and heat are drawn through the dryer, with the product dried by both convection and contact. In the triple-pass unit, the material flows through concentric passes as it becomes dryer and lighter, allowing for a very uniform drying pattern. The single-pass unit, as its name suggests, allows for a less free-flowing material to achieve a very uniform dryness while keeping production rates at an effective level.

bakerrullmanBaker-Rullman Manufacturing Inc., located in Watertown, Wisconsin, manufactures corrugated steel storage bins, hoppers, steel structures, and triple-pass rotary drum dryers. Baker-Rullman’s dehydration division manufactures custom and standard dehydration systems in a wide variety of sizes. These systems use triple-pass rotary drum dryers for biomass in industrial, agricultural, and municipal applications to handle all kinds of drying needs. Hundreds of Baker-Rullman dehydration systems and rotary drum dryers are in service in more than 50 countries and in almost every U.S. state. Baker-Rullman continues the quality heritage of the Heil design, delivering extensively proven dehydration system technology. The engineers at Baker-Rullman have developed and refined rotary drying through the years, demonstrating that the triple-pass design is a highly reliable and proven technology.

mecM-E-C Company is a designer and manufacturer of drying systems for biofuels, as well as the particleboard, medium density fibreboard, and oriented strandboard forest products industries. It operates manufacturing facilities where high-quality single-pass, triple-pass, and flash tube dryers are fabricated, along with key process components such as storage bins, conveyors, fans, and pneumatic equipment. Its shops are capable of manufacturing dryers more than 6 metres in diameter and more than 30 metres in length. It also produces compact, factory-built, easy-to-operate TherMec Dry Wood Fuel Suspension Systems, available in a range of sizes with capacities up to 30 MW/hour. M-E-C and its subsidiary, Pro-Environmental Inc., offer a seamless supply of wood drying systems equipped with air pollution control equipment for guaranteed drying capacity and assured environmental compliance. For more information, call 620-325-2673 or e-mail

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