Patent ID: 9593286
Date: 2017-03-14
CPC Classifications: C10J,C10L,F22B,F22G,Y02E

Claim:
1. A method for cogenerating gas-steam based on gasification and methanation of biomass, the method comprising: 1) mixing oxygen and water vapor produced from an air separation plant with biomass, transporting a resulting mixture via a nozzle to a gasifier, gasifying the biomass at a temperature of 1,500-1,800° C. and a pressure of 1-3 MPa to yield crude gasified gas, transporting the crude gasified gas to a waste heat boiler and heating water in the waste heat boiler by the crude gasified gas to yield a superheated steam having a pressure of 5-6 MPa, and transporting the superheated steam to a steam turbine; 2) according to demand for a methanation reaction, adjusting a hydrogen/carbon ratio of the crude gasified gas generated from step 1) to 3:1 using a shift reaction, and eluting the crude gasified gas using low-temperature methanol for desulfurization and decarburization, whereby yield purified syngas; 3) introducing the purified syngas from step 2) to a methanation unit comprising a primary methanation unit and a secondary methanation unit, the primary methanation unit comprising a first primary methanation reactor and a second primary methanation reactor connected in series; allowing part of process gas from the second primary methanation reactor to return to an inlet of the first primary methanation reactor to mix with the purified syngas, and then to enter the first primary methanation reactor, so that a concentration of reactants at the inlet of the first primary methanation reactor is reduced and a temperature of a catalytic bed of the first primary methanation reactor is controlled by the process gas; introducing syngas from the primary methanation unit to the secondary methanation unit comprising a first secondary methanation reactor and a second secondary methanation reactor connected in series, where a small amount of unreacted CO and a large amount of CO 4) concentrating methane of synthetic natural gas containing trace nitrogen and water vapor obtained from step 3) through pressure swing adsorption, so that a molar concentration of methane reaches 96%, and a calorific value of the synthetic natural gas is up to 8,256 kcal/Nm