As a key piece of equipment in biomass resource processing and utilization, a biomass dryer can effectively reduce the moisture content of various biomass materials, laying the foundation for subsequent resource utilization. The following describes these dryers from three perspectives: applicable materials, operating principles, and application scenarios.
1. Biomass dryers are highly adaptable and can process biomass materials of varying forms and initial moisture levels, primarily including the following:、
Agricultural and forestry waste: Wood processing residues such as sawdust, wood chaff, and sawdust; crop byproducts such as straw (wheat straw, corn straw, and rice straw); rice husks, peanut shells, and cottonseed hulls; and forestry pruning waste such as branches, bark, and leaves. These materials typically have an initial moisture content between 15% and 60%.Livestock and poultry manure: Livestock and poultry excrement such as chicken manure, cow manure, and sheep manure, after initial dehydration (approximately 40% to 70% moisture), can be further dried in a dryer to a state suitable for storage and utilization. Energy crops used to produce biomass fuel, such as sweet sorghum stalks, switchgrass, and Miscanthus, require drying after harvest to reduce moisture and ensure quality for subsequent processing. Other biomass types can also be processed: Industrial biomass waste, such as traditional Chinese medicine residues, distiller's grains, and mushroom residues, as well as cash crop processing residues, such as palm residue and sugarcane bagasse.
2. Currently, mainstream biomass dryers mostly use a drum-type structure. Their operating principle is based on "full contact and heat exchange between hot air and the material." The specific process is as follows:
Feeding: Wet biomass material is fed into the dryer drum via a conveyor. The drum is installed at a certain angle to ensure that the material moves forward gradually as the drum rotates.
Heat exchange drying: The drum is equipped with lifting plates. As the drum rotates, the lifting plates continuously lift and spread the material, forming a uniform material curtain. At the same time, high-temperature hot air (typically 120-300°C) generated by a hot air furnace (which can use biomass itself, coal, or natural gas as a heat source) enters from one end of the drum, flowing counter- or co-currently with the material curtain. Through heat conduction, convection, and radiation, it rapidly evaporates moisture from the material.
Gas-solid separation: The dried material enters a cyclone separator with the airflow, where most of the material is separated and collected as the finished product. The exhaust gas, which contains a small amount of dust, is purified by a bag filter and then discharged into the atmosphere by an induced draft fan, meeting environmental requirements.
Finished product output: The separated dry material is conveyed to a silo for storage via a conveyor, completing the drying process.
3. The application scenarios of biomass dryers are closely related to the resource utilization of biomass resources, primarily focusing on the following areas:
Biomass fuel production: Dried biomass materials (such as wood chips and straw) can be further processed into biomass pellets and biomass briquettes for use in boilers for heating, power generation, and other applications. The dryer must control the moisture content of the material to below 10% to ensure fuel combustion efficiency.
Organic Fertilizer Processing: After drying, livestock and poultry manure, mushroom residue, and other materials can be mixed with other auxiliary materials and fermented to produce organic fertilizer for agricultural use. The drying process not only reduces moisture content, facilitating fermentation, but also kills some pathogens and insect eggs, improving the quality of the organic fertilizer.
Feed Processing: After drying, biomass waste materials such as distiller's grains and traditional Chinese medicine residue can be added to livestock and poultry feed, realizing waste resource utilization. Dryers must ensure that the nutrients in the materials are not excessively destroyed.
Biomass-Based Material Preparation: Dried sawdust, straw, and other materials can be used to produce artificial boards, biochar, and paper pulp. A stable moisture content ensures stability in subsequent processing and product quality.
Biomass dryers efficiently dehydrate various biomass materials, solving the problems of wet biomass storage difficulties and moldiness. They also bridge the gap between "biomass waste" and "high-value resources," playing an indispensable role in energy conservation, environmental protection, and resource recycling.
