Biogas from Straw

In close collaboration with our partner Kinetic Biofuel, we have developed a briquette machine process which enables you to use briquetted straw in biogas plants.

At C.F. Nielsen, our expertise is waste-to-fuel technologies. The briquette machine press for biofuel is a patented 2nd Generation technology, using straw as raw material. With our unique process, a small steam explosion is created and the cell structure of each individual straw is opened. This gives access to beneficial bacteria, making it easy to disperse the straw briquettes in biofuel reactors. The briquetted straw has a high absorption rate – 7-10 times more than normal straws. As a result, it generates high yields in biofuel plants.

From waste to biogas

In bioethanol plants, the concept works as a pre-treatment process. This makes the handling and introduction of biogas into the ethanol plants fairly simple while still reducing investments and costs in other parts of the ethanol plant.

There are multiple benefits of the waste to fuel technology.

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The three main benefits are

Patented 2nd generation technology increasing yield
High absorption rate
High biogas and methane yield – 250 Nm3 methane per ton of straw

Patented Technology

Using briquette press machines for straw is truly a 2nd generation technology. Straw is often considered waste in agriculture, whereas many of the other biomass based raw materials - such as corn silage - used in a biogas plant are basically food being utilized for energy production. The use of consumable food for producing fuel is under considerable pressure to be reduced in the future, both considering environmental foresight and food distribution.

We can deliver complete briquette press machines with straw handling, shredding, and milling equipment, including sand and stone removal, and high capacity mechanical presses at reduced capex costs due to the reduced complexity of the ethanol process. Line capacities start at 500 kg per hour, but can be up to 20 tonnes per hour.

High absorption rate

The mechanical pre-treatment and high pressure of the briquetting machine press creates small steam explosions. This changes the structure of the straw, enabling it to absorb 7-10 times more than normal straw. In the process, the cell structure is opened by a small steam explosion. This gives free passage for bacteria and eases dispersion of the straw briquettes in biofuel reactors. As a result, the briquettes are absorbed rapidly in the biogas reactor.

The largest briquette machine presses BP6510 and BP7510 hold the capacities of 1,5 and 2,75 tonnes per hour of briquetted straw, respectively. The briquette machine presses are piston and flywheel based presses, which operate with 270 revolutions per minute, creating pressure beyond 2000 kg/m2 and thus causing the small steam explosions which change the structure of the straw.

High biogas and methane yield

Due to the relatively high density of the briquettes, a substantial amount – approximately 10% - can be added to manure in a reactor. For example, a biogas plant, which uses 100.000 tonnes of slurry and produces 2.5 million m3, can produce approximately 6.5 million m3 of biogas. This is the result of the technology and feeding of 10.000 tonne of straw per year.

Loose straws have a bulk weight of 50-80 kg/m3, whereas straw briquettes have a bulk weight of 400-450 kg/m3. This makes it easier to transport in conveyor systems and introduce into the biogas reactor, either through a screw conveyor at the top of the reactor or by mixing the briquettes with slurry, and pumping the raw material into the biogas reactor.

Contact us to learn more about our briquetting solutions for biogas plants.

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