Hydromethanation of a carbonaceous feedstock

A process for generating a methane-enriched raw product gas stream and a gas-stripped char stream from a non-gaseous carbonaceous material, the process comprising the steps of:

• (a) preparing a carbonaceous feedstock from the non-gaseous carbonaceous material;
• (b) introducing the carbonaceous feedstock and a hydromethanation catalyst into a hydromethanation reactor, wherein the hydromethanation reactor comprises a char-withdrawal standpipe having a withdrawal end extending into the hydromethanation reactor and a discharge end extending out of the hydromethanation reactor;
• (c) reacting the carbonaceous feedstock in the hydromethanation reactor in the presence of carbon monoxide, hydrogen, steam and hydromethanation catalyst, and at an operating temperature of at least about 1000° F. (at least about 538° C.) and an operating pressure of at least about 250 psig (about 1825 kPa) to produce a methane-enriched raw product gas and a solid by-product char;
• (d) withdrawing a stream of the methane-enriched raw product gas from the hydromethanation reactor as the methane-enriched raw product gas stream, wherein the methane-enriched raw product gas stream comprises methane, carbon monoxide, hydrogen, carbon dioxide, hydrogen sulfide, steam and heat energy;
• (e) withdrawing a stream of the solid by-product char from the hydromethanation reactor via the withdrawal end of the char-withdrawal standpipe, wherein the stream of solid by-product char flows from the withdrawal end to the discharge end of the char-withdrawal standpipe, and wherein the withdrawn solid by-product char comprises an entrained gas;
• (f) feeding a stripping gas into the char-withdrawal standpipe such that the stripping gas flows in a countercurrent direction to the flow of the stream of by-product char within the char-withdrawal standpipe to generate (1) a stripped gas stream enriched in the entrained gas and (2) a gas-stripped char stream depleted in the entrained gas;
• (g) feeding the stripped gas stream into the hydromethanation reactor via the char-withdrawal standpipe;
• (h) feeding the gas-stripped char stream to a screw discharge unit in communication with the discharge end of the char-withdrawal standpipe;
• (i) discharging the gas-stripped char stream from the screw discharge unit at a superatmospheric pressure.