The present disclosure relates to a power production system that is adapted to achieve high efficiency power production with carbon capture when using a solid or liquid hydrocarbon or carbonaceous fuel. More particularly, the solid or liquid fuel first is partially oxidized in a partial oxidation reactor that is configured to provide an output stream that is enriched in methane content. The resulting partially oxidized stream can be cooled, filtered, additionally cooled, and then directed to a combustor of a power production system as the combustion fuel. The partially oxidized stream is combined with a compressed recycle CO.sub.2 stream and oxygen. The combustion stream is expanded across a turbine to produce power and passed through a recuperator heat exchanger. The recycle CO.sub.2 stream is compressed and passed through the recuperator heat exchanger and optionally the POX heat exchanger in a manner useful to provide increased efficiency to the combined systems.

A carbonaceous fuel gasification system for all-steam gasification with carbon capture includes a micronized char preparation system comprising a devolatilizer that receives solid carbonaceous fuel, hydrogen, oxygen, and fluidizing steam and produces micronized char, steam, volatiles, hydrogen, and volatiles at outlets. An indirect gasifier includes a vessel comprising a gasification chamber that receives the micronized char, a conveying fluid, and steam. The gasification chamber produces syngas, ash, and steam at one or more outlets. A combustion chamber receives a mixture of hydrogen and oxidant and burns the mixture of hydrogen and oxidant to provide heat for gasification and for heating incoming flows, thereby generating steam and nitrogen. The heat for gasification is transferred from the combustion chamber to the gasification chamber by circulating refractory sand. The system of the present teaching produces nitrogen free high hydrogen syngas for applications such as IGCC with CCS, CTL, and Polygeneration plants.

A two-stage syngas production method to produce a final product gas from a carbonaceous material includes producing a first product gas in a first reactor, separating char from the first product gas to produce separated char and char-depleted product gas, and separately reacting the separated char and the char-depleted product gas with an oxygen-containing gas in a second reactor to produce a final product gas. The separated char is introduced into the second reactor above the char-depleted product gas. The solids separation device may include serially connected cyclones, and the separated char may be entrained in a motive fluid in an eductor to produce a char and motive fluid mixture prior to being transferred to the second reactor. A biorefinery method produces a purified product from the final product gas.

Process for the conversion of plastics to olefins comprising the following steps: A) gasification of the plastics to synthesis gas by reaction of the plastics with pure oxygen; B) catalytic conversion of the synthesis gas produced in stage A) to methane in at least three successive stages, in each of which hydrogen is added; C) catalytic conversion of the methane produced in stage B) into olefins by the oxidative coupling reaction of methane; and D) separation of the olefins produced in stage C) from other compounds present in the reaction mixture of said stage C).

Methods and systems for processing construction and demolition (C&D) materials to produce a product gas stream and/or electricity are disclosed herein. In some embodiments, the method comprises pre-processing C&D materials to produce a C&D feed, and processing the C&D feed to produce syngas. The C&D feed can comprise untreated wood, treated wood, paper and cardboard, yard waste, plastic, rubber, and/or foam. Processing the C&D feed can comprise gasifying the C&D feed, steam, and oxygen in a gasifier at a temperature of no more than 950° C. and/or a pressure of no more than 200 psi to produce syngas.

A two-stage syngas production method to produce a final product gas from a carbonaceous material includes producing a first product gas in a first reactor, separating char from the first product gas to produce separated char and char-depleted product gas, and separately reacting the separated char and the char-depleted product gas with an oxygen-containing gas in a second reactor to produce a final product gas. The separated char is introduced into the second reactor above the char-depleted product gas. The solids separation device may include serially connected cyclones, and the separated char may be entrained in a motive fluid in an eductor to produce a char and motive fluid mixture prior to being transferred to the second reactor. A biorefinery method produces a purified product from the final product gas.

Process for the conversion of plastics to olefins comprising the following steps: A) gasification of the plastics to synthesis gas by reaction of the plastics with pure oxygen; B) catalytic conversion of the synthesis gas produced in stage A) to methane in at least three successive stages, in each of which hydrogen is added; C) catalytic conversion of the methane produced in stage B) into olefins by the oxidative coupling reaction of methane; and D) separation of the olefins produced in stage C) from other compounds present in the reaction mixture of said stage C).

Aspects of the invention relate to improvements in the flexibility with which oxygen and hydrogen, for example from electrolysis, may be supplied to processes having both gasification and methanation steps, as well as improvements in how such processes may be operated in response to variations in carbonaceous feeds. Offsets, between the ideal quantity of hydrogen and the quantity available from a given source may be compensated for by adjusting one or more operations of the process, and in particular such operation(s) that ultimately impact the quantity of CO and/or CO.sub.2 available downstream of the gasifier for conversion to methane in an RNG product stream.

A two-stage syngas production method to produce a final product gas from a carbonaceous material includes producing a first product gas in a first reactor, separating char from the first product gas to produce separated char and char-depleted product gas, and separately reacting the separated char and the char-depleted product gas with an oxygen-containing gas in a second reactor to produce a final product gas. The separated char is introduced into the second reactor above the char-depleted product gas. The solids separation device may include serially connected cyclones, and the separated char may be entrained in a motive fluid in an eductor to produce a char and motive fluid mixture prior to being transferred to the second reactor. A biorefinery method produces a purified product from the final product gas.

Aspects of the invention relate to improvements in the flexibility with which oxygen and hydrogen, for example from electrolysis, may be supplied to processes having both gasification and methanation steps, as well as improvements in how such processes may be operated in response to variations in carbonaceous feeds. Offsets, between the ideal quantity of hydrogen and the quantity available from a given source may be compensated for by adjusting one or more operations of the process, and in particular such operation(s) that ultimately impact the quantity of CO and/or CO.sub.2 available downstream of the gasifier for conversion to methane in an RNG product stream.