Briquettes

BIOMAC ECOLOGICAL FUELS are made from pure biomass – sawdust, shavings or washed tree bark. This is an inexhaustible source in the Czech Republic, growing in volumes exceeding what is used up, in contrast to the traditional fossil fuels the reserves of which are diminishing constantly and, as a consequence, which come with an ever-increasing price.

From the future heating requirements point of view, the BIOMASS from which the BIOMAC ECOLOGICAL FUELS are produced is the oldest and actually the only renewable source of fuel we have available in the Czech Republic for the 3rd millennium (the sun and water are insufficient as an industrial energy source in this country).

Ecological fuel manufacturing phases:

• Raw material acceptance, biomass processing by crushing and sieving

• Biomass drying

• Biomass compression into the product

• Wood briquette packaging

Line for the incoming raw material

The incoming material includes mainly bulk matter such as sawdust, shavings and chips. Typically, a wheel loader transfers the loose biomass from a sheltered raw material storage area into a large storage bin two or three times during a shift. The loose material is passed through a rotary sieving machine wherefrom the fine fraction 0-10 mm size goes directly to a bin at the dryer while the coarse fraction is additionally crushed in a high-speed crusher or a hammer mill. Once additionally crushed, this fraction is added to the fine fraction in the bin at the dryer.

Drying line

Agricultural BS-6 hot-air dryers are typically used in the Czech Republic to remove excess moisture from the biomass. These are three-way rotary drum dryers in which the material is dried with direct combustion gas, whereby an evaporating capacity up to 2 tons of water can be attained, the specific heat consumption being as low as 6 MJ per kg of evaporated water.

Briquetting line

Generally, wood briquettes are obtained from the dry biomass by high-pressure processing at an elevated temperature, whereby the resin and lignin in the biomass are melted and help transform the biomass into a compact body. No adhesives or other ingredients are added! Three compressing principles have been invented for pressing the biomass into wood briquettes.

• Screw presses, such as the Austrian PINIKEY products. Here a powerful motor with a robust gear drives a “meat grinder” into which the biomass from the dedicated dry biomass bin is dispensed by means of a screw. The press screw pushes the material into a press chamber constantly heated at 250°C. Due to passage through a conical hexagonal press casing, the product leaving the press is an endless hexagonal wood briquette with a 60 mm x 60 mm cross section and with a central hole, compacted to a specific weight of up to 1,250 kg/m³.
• Hydraulic presses: the German RUF presses providing briquettes with a 155 mm x 65 mm cross section and a length of 80 mm to 120 mm are the most widely used. Cylindrical hydraulic briquettes are also manufactured. Their diameter is from 40 mm to 80 mm, length from 50 mm to 200 mm. BRIKLIS s.r.o. is the sole Czech manufacturer. Hydraulic wood briquettes are compacted to a lesser degree than the briquettes leaving the screw press – their specific weight is 700-1,050 kg/m³. As a result, they burn faster than the briquettes from the screw press.
• Mechanical (crank) presses: the Swiss PAWERT-SPM presses producing cylindrical briquette 90 mm in diameter, with or without a central hole, have been available in the market since 1926. BIOMAC is the sole Czech crank press manufacturer, offering 2 press sizes. The hourly throughput of the one size is 600 kg of full-diameter briquettes with 75 mm diameter, that of the other size is 1,200 kg if producing full diameter briquettes with 90 mm diameter or 1,000 kg if producing briquettes with a central hole. The mechanical crank presses use a horizontal crank mechanism with 2 flywheels: a plunger pushes a dry biomass dose into the conical press casing 4 times in a second, and an "endless" briquette leaves the machine at 70 – 90°C. Owing to the powerful plunger impact in a short time, the biomass in the conical casing is compacted at a pressure of up to 1,800 Atm. and the specific weight of the briquette is up to 1,250 kg/m³, which is associated with a long burning time. The dry biomass must be precisely proportioned from the dry matter bin into the press, best by using a closed, variable-speed screw conveyor enabling the press throughput to be controlled. The wood briquette leaving the press is passed through a 10 m cooling duct to cool down and solidify. At the end of the cooling duct, an automatic sawing machine cuts it into precisely 2 kg wood briquettes.

Briquette packaging line

All the briquettes made from biomass are manufactured without using any adhesive: only high pressure and temperature are used to obtain the compact product. The briquettes have only one drawback: they must not get in contact with moisture. To this end, all briquette types are packaged in closed PE (polyethylene) bags or wrapping including the final pallets. For the product to sell well, the goods must be professionally packaged in amounts small enough for a woman or an elderly person to be able to handle the goods without any problems. The package must carry the manufacturer's label, barcode and guaranteed package weight. This process is frequently fully automated in large plants.