Methods and systems for removing contaminants, such as water and/or carbon dioxide, from a gas stream, such as a natural gas stream or a flue gas stream. One or more solid-tolerant heat exchangers are employed to chill the gas stream to a temperature at which the contaminants solidify. The solidified contaminants may then be separated and removed from the gas stream. In one or more aspects, the one or more solid-tolerant heat exchangers may include a scraped heat exchanger.

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.

Disclosed are methods of producing calcined coke from bio-oil from a biomass feedstock. Also disclosed are calcined cokes produced by such methods.

Some variations provide a process for producing biocarbon pellets, comprising: pyrolyzing a biomass-containing feedstock in a first pyrolysis reactor to generate a first biogenic reagent and a pyrolysis vapor; introducing the pyrolysis vapor to a separation unit, to generate a pyrolysis precipitate in liquid or solid form; contacting the first biogenic reagent with the pyrolysis precipitate, thereby generating an intermediate material; pelletizing the intermediate material, to generate intermediate pellets; optionally, drying the intermediate pellets; separately pyrolyzing the intermediate pellets in a second pyrolysis reactor to generate a second biogenic reagent and a pyrolysis off-gas; and recovering the second biogenic reagent as biocarbon pellets. Some variations provide a similar process that utilizes a carbon-containing condensed-matter material, which is not necessarily a pyrolysis precipitate. The disclosure provides improved processes for producing biocarbon compositions, especially with respect to carbon yield and biocarbon properties, such as reactivity.

The present invention relates to a process for forming a fuel pellet, based on using a particular formula for making the fuel pellets. The process for forming a fuel pellet comprising of the following steps:

providing a particulate carbonaceous material having a particle size of <1 mm;

admixing the particulate carbonaceous material with a polysaccharide or a polyvinyl alcohol binder, and a crosslinker;

shaping the so-formed mixture to provide the fuel pellet.

A method of processing exhaust gas containing CO.sub.2, such as exhaust gas from a cement production plant, includes burning fuel in the combustion reactor with the O.sub.2 content of the exhaust gas being used as an oxidizing agent, controlling the combustion in the combustion reactor so that the exhaust gas from the combustion reactor contains less than 10 vol.-% of oxygen and at least 80 vol.-% of a mixture of CO and CO.sub.2, and feeding the exhaust gas from the combustion reactor into a conversion reactor, in which the CO.sub.2 and optionally the CO contained in the exhaust gas is converted into a hydrocarbon fuel.

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.

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.