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Technological Process

Technological Process of Biogas Production

Feed stock every day transported to biogas plant area and discharged to loading bunker Substrates loaded to loading bunker by portions with interval 4-6 hours. Using the conveyor system feedstock is fed for further fermentation. For dilution of the substrate when the startup plant is on the pipeline will be supplied water in the digester. In the operational period the digested substrate is fed in the same volume. The use of digested substrate can reduce the cost of heat energy (because it is warm) and the return part is not digested organics back into the process.

Each of the digesters have a loading system (loading bunker and conveyor system). In the digester, the substrate is heated to a temperature of +45… +480C. The heating system is installed on the walls and bottom of the digesters. Thus, the digester temperature is kept constant during the whole fermentation process. The digesters work in mesophilic regime. Heated substrate is mixed periodically (20-25 minutes per hour) by vertical mixers. The average time of fermentation is 25-27 days. Biogas goes up and flows into overall biogas system with a gasholder.

Digested mass of each reactor goes to Post-Digester where the residual organic matter decomposition. Organic compounds are carbohydrates and protein in a torn condition after fermentation in digesters – this allows more fully digested organic substrate and obtain additional biogas. Retention time in post-digester is 12-14 days. After post-digesting digested substrate pumping to separator where it separating into solid and liquid organic fertilizers. Solid fertilizers are discharged on fertilizer area and transported to the fertilizer storage (used for their own needs), the liquid filtrate directed to the tank for a filtrate from which it is pumped to an existing lagoon and the dilution of the incoming feedstock.

Post-digester equipped with gasholder.

Gasholder is fixed to the belts of post-digester. The volume of gasholder – 1355 m3. Weather protective film protects the gasholder of rainfall and damage by external objects. Protective film is fixed due to the pressure of air injected into the blower. To prevent exceeding pressure gasholder above the permissible it is equipped with safety valve which begins to operate at a pressure of 5 mbar and releases biogas to the atmosphere. Sulphur is removed from biogas by addition of strict and definite quantity of air into digesters.

Then biogas goes through gas pipeline to compressor, where the pressure is raised up to 80-100 mbar to meet engine requirements. Gas pipeline is equipped with condensate discharge unit. All the unit’s work based on gauges limiting values. Biogas is supplied to co-generation power plant, where it is used as fuel for production of electric and heat power. Heat from co-generator goes through heat exchanger for heating digesters. Heating equipment is used for distribution of heat between biogas plant facilities.

All technological processes are controlled and operated by automatic system. Biogas plant work is visualized at central control room monitor. The control room is equipped with central control unit, which allows switch of any biogas plant module into automatic or manual mode with local or remote control.