A subsea fluid processing system which receives a wellstream flow. The subsea fluid processing system includes a pressure control device which regulates a pressure of the wellstream flow, a gas-liquid separator unit which receives the wellstream flow downstream of the pressure control device and which provides a liquid stream and a gas stream, a first membrane separator which receives the gas stream and which provides a retentate stream and a permeate stream, a compressor which receives the permeate stream and which provides a compressed permeate stream, and a discharge cooler which receives the compressed permeate stream and which provides a cooled compressed permeate stream for injection into a subsurface reservoir. A density of the cooled compressed permeate stream is higher than a density of the compressed permeate stream.

Various illustrative embodiments of a system and process for recovering high-quality biomethane and carbon dioxide product streams from biogas sources and utilizing or sequestering the product streams are provided. The system and process synergistically yield a biomethane product which meets gas pipeline quality specifications and a carbon dioxide product of a quality and form that allows for its transport and sequestration or utilization and reduction in greenhouse gas emissions. The system and process result in improved access to gas pipelines for products, an improvement in the carbon intensity rating of the methane fuel, and improvements in generation of credits related to reductions in emissions of greenhouse gases.

A process for cleaning and beneficiating biomass is described which may allow removal of entrained salts and light volatiles from biomass materials. The process may also minimize energy use through capturing steam and flue gases for re-use. The process may generally comprise the following steps: prewashing and/or preheating a biomass, pressurizing the biomass in a steam explosion vessel, rapidly depressurizing the steam explosion vessel, releasing the steam from the steam explosion vessel entrained with fine lignin-enriched particles into a cyclone-type gas expansion vessel, routing the steam from the gas expansion vessel to the input hopper, subjecting the biomass to a second washing step, mechanically removing a portion of the water from the biomass, and evaporatively heating the biomass.

Aqueous wastewater from hydrothermal liquefaction (HTL) systems is typically high in chemical oxygen demand (COD), which renders classic aerobic wastewater treatment to be prohibitively expensive. HTL wastewater can be processed using thermochemical wet oxidation in a manner that is not only cost efficient but also contributes more heat than is required for the energetically demanding HTL process. Provided are methods and devices for integrated hydrothermal liquefaction of biomass and treatment of resulting wastewater.

The methane production plant (10) comprises: an electric energy source (11) suitable for supplying electrical energy, an electrolyser (14) fed with the electrical energy supplied by the electric energy source, suitable for supplying hydrogen in gas form, an atmospheric carbon dioxide capture device (16) suitable for supplying carbon dioxide and water, a methanation reactor (15) suitable for receiving the hydrogen supplied by the electrolyser, water and the carbon dioxide that are supplied by the atmospheric carbon dioxide capture device, and suitable for producing methane, and solar collectors (19) and a means for heat transfer from the solar collectors to the carbon dioxide capture device (16).

A combined plant for cryogenic separation and liquefaction of methane and carbon dioxide in a biogas stream, including a mixing means, a compressor, a first exchanger, a distillation column, a second exchanger, a separating means, an expanding means, and a separator vessel. Wherein, the mixing means is configured such that the recycle gas is the overhead vapour stream, and the first exchanger and the expanding means are combined.

Disclosed herein are processes and systems for removing heavy C5+ hydrocarbon components from a natural gas feed gas by subjecting the natural gas feed gas stream to an adsorber. The adsorber in the processes and systems described herein operating at a pressure that may be associated with improved adsorption capacity and longer breakthrough time.

A combined plant for cryogenic separation and liquefaction of methane and carbon dioxide in a biogas stream, including a mixing means, a compressor, a first exchanger, a distillation column, a second exchanger, a separating means, an expanding means, and a separator vessel. Wherein the mixing means is configured such that the recycle gas is the overhead vapour stream, and the first exchanger and the expanding means are combined.

A combined plant for cryogenic separation and liquefaction of methane and carbon dioxide in a biogas stream, including a mixing means, a compressor, a first exchanger, a distillation column, a second exchanger, a separating means, an expanding means, and a separator vessel. Wherein, the mixing means is configured such that the recycle gas is the overhead vapour stream, and the first exchanger and the expanding means are combined.

A combined plant for cryogenic separation and liquefaction of methane and carbon dioxide in a biogas stream, including a mixing means, a compressor, a first exchanger, a distillation column, a second exchanger, a separating means, an expanding means, and a separator vessel. Wherein the mixing means is configured such that the recycle gas is the overhead vapour stream, and the first exchanger and the expanding means are combined.