METHOD AND SYSTEM FOR EFFICIENT COMBINED-CYCLE COGENERATION BASED ON GASIFICATION AND METHANATION OF BIOMASS Russian patent published in 2016 - IPC C07C1/04 C10K1/00 C10K3/00 C10J3/86 C10L3/08 C10L3/10 F22B1/18 

FIELD: energy.

SUBSTANCE: invention provides a system and method of steam-gas conversion. Method of combined-cycle cogeneration based on gasification and methanation of biomass involves: 1) gasification of biomass by mixing oxygen and water vapor derived from air separation plant, with the biomass, transportation of the resulting mixture through a nozzle into gasifier, gasification of biomass at temperature of 1500-1800 °C and pressure of 1-3 MPa to obtain a crude gasified gas and transporting the superheated steamunder pressure of 5-6 MPa, resulting from heat recovery to the steam turbine; 2) conversion and purification: in accordance with the methanation reaction the ratio of hydrogen/carbon crude gasified gas generated in step 1) is corrected up to 3:1 using the conversion reaction; recovery at a low temperature of crude gasified gas using methanol to desulfurization and decarbonization, thereby obtaining a purified syngas; 3) methanation: supply of purified syngas obtained at step 2) into methanation section, consisting of a primary and secondary sections, herewith the methanation section comprises a first primary methanation reactor and second primary methanation reactor coupled in series; allowing the portion of the process gas supplied from the second primary reactor to flow back to the input of first primary reactor for mixing with fresh feed gas and further opportunities to enter the first primary reactor, so that the concentration of reagents at the inlet of first reactor reduces and temperature of the catalyst bed is regulated by process gas; supplying the syngas to secondary methanation section comprising a first secondary methanation reactor and a second secondary methanation reactor coupled in series, where a small amount of unreacted CO and a lot of CO₂ converted to CH₄ , transporting the superheated intermediate pressure steam generated in the methanation section to steam turbine; and 4) concentration of methane in natural gas containing trace amounts of nitrogen and water vapor obtained in step 3), concentration of methane by adsorption under alternating pressure, so that the molar concentration of methane reaches 96 % and the calorific value of synthetic gas reaches 8,256 kcal/Nm³.

EFFECT: technical result consists in biomass power converted to pure and easy in use natural gas with high calorific capacity, a large amount of heat resulting from reactions of gasification and methanation of biomass, effectively recycling to form high-quality superheated steam.

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