Biogas plant

Thanks to the Kiintomädätys® technology, the biogas plant can use both wet and dry feedstocks. The patented reactor with biofilter is a well-insulated biogas reactor with a modular and steel structure. 400 mm blown wool is used as insulation and is designed to withstand challenging weather conditions.

The main component of a biogas plant is slurry from production animals, and you can feed the biogas plant with, for example, over-yearly grass fodder, which is often difficult to dispose. In addition, you can utilise external inputs, such as waste biomasses from the food industry.

The reactor has a steel pool with a concrete bottom and a double membrane dome (gas hood + weather protection). The mixers inside the reactor enhance gas production and mix digestate, which prevents a situation where the mass does not change and the biogas process could interrupt. 1-2 blade and/or propeller mixers are installed into the reactor as needed. The reactor has an integrated equipment room for push throughs, check window and gas handling equipment. Demeca’s gReactor has pressure control and safety devices.

Sludge is crushed to smooth and liquid state with the Demeca Kaira slurry pump and pumped from the barn through a heat exchanger into the reactor. In the reactor, sludge and dry feeds are transformed into digestate, also called ”reject”.

In Demeca’s solution, slurry is pumped to the biogas plant directly from the barn pump well, making the slurry as fresh as possible. The auger slurry pump together with the booster pump feeds sludge from the barn to the plant. The Kaira slurry pump homogenizes sludge and thus enhances gas production through a heat exchanger located in the plant space.

The internal combustion engine uses gas as fuel and runs an electric generator, i.e. a biogas boiler (225-380 kW). In addition to electricity, waste heat and heat from exhaust gases are utilised from the generator. Additional heat can be generated by a gas burner in a separate heat boiler. Only water vapour and carbon dioxide are emitted. In addition to own use, it is possible to sell electricity produced to the national grid.

All plant main connections and equipment control are centralised in one space, where they are easily serviceable and accessible. The plant is connected to a remote access system and can be controlled and controlled from anywhere.

The dry fractions are pretreated in the plant’s gFeed unit by crushing and homogenizing with liquid fractions, after which the homogenised mass, which decomposes well in the bioprocess, is pumped into the reactor for digestion. The gfeed unit processes the dry feed, increasing the specific area of the plant parts, enabling efficient bacterial activity. Solids have signifigant impact to gas production and grows gas production significantly.

When feeds are put dry feed in the unit, it is a good to aim for a steady feed flow, so the gas yield can be influenced by storage methods on the farm.

The 3-stage membrane upgrading of biomethane (50-100 Nm3/h) into vehicle fuel takes place in a separate Demeca gFuel unit. The gFuel unit will be located in the vicinity of the biogas plant of can be delivered as a partial delivery without Demeca biogas plant.

After biogas refining, the gas is pressurised (300 bar) in the gCompress unit next to the filling station and stored in gas tanks, from where it can be refuelled directly to vehicles from the refuelling meter or sold in a gas container. The filling station, payment terminal and Finnish Safety and Chemicals Agency (Tukes) permits come from Demeca.

When the gas consumption site and the gas production plant are located further apart, the gas transmission can be carried out using the Demeca gGrid unit and an underground gas pipeline. Demeca is a registered plastic piping welding company and designs and implements licensed gas transmission lines professionally.

In pre-treatment, the gas is dried in a counterflow heat exchanger, into which a cooling heat pump makes a cold liquid flow, when condensing water is separeted from the gas. After drying, the gas is passed through carbon filters, where hydrogen sulfide and VOC compounds are filtered out from the gas. From pre-treatment, the gas is passed into side channel blower fan into the selected drive line. (example CHP production, biomethane upgrading or torchburn)

Stylish and practical refuelling point for public distribution of biomethane fuel. The most visible parts of the product are the protective canopy anchored to the concrete slab, the distribution meter and the payment terminal. Demeca designs the necessary security systems, surveillance, information boards and other equipment professionally in accordance with the requirements of the site.