Anaerobic digestion system and process

In an anaerobic digestion system:

• means for producing a raw gas containing methane and other gaseous components, and means for misting the gas with process water which has been separated from sludge in the system to cool the gas at atmospheric pressure to a temperature at which the other gaseous components have a substantially higher solubility in water than methane and are substantially all absorbed into the water without changing state, leaving dry methane gas.

In a gas separation:

• a source of raw gas containing methane and other gaseous components, and a cooling coil for cooling the gas at atmospheric pressure in the presence of a liquid to a temperature at which the other gaseous components have a substantially higher solubility in the liquid than methane and are substantially all absorbed into the liquid without changing state, leaving pure, dry methane gas.

In an anaerobic digestion system:

• means for producing a raw gas containing methane and other gaseous components, means for cooling the gas at atmospheric pressure in the presence of a liquid to a temperature at which the other gaseous components have a substantially higher solubility in the liquid than methane and are substantially all absorbed into the liquid without changing state, leaving pure, dry methane gas, and means for compressing and heating the methane gas and supplying the heated methane gas to a digester in the system.

In a process for separating methane gas from a raw gas containing methane and other gaseous components, the step of cooling the gas at atmospheric pressure in the presence of water to a temperature at which the other gaseous components have a substantially higher solubility in water than methane and are substantially all absorbed into the water without changing state, leaving pure, dry methane.

In a process for separating methane gas from a raw gas containing methane and other gaseous components, the step of cooling the gas at atmospheric pressure in the presence of a liquid to a temperature at which the other gaseous components have a substantially higher solubility in the liquid than methane and are substantially all absorbed into the liquid without changing state, leaving pure, dry methane.

In an anaerobic digestion process which produces a raw gas containing methane and other gaseous components, the step of cooling the gas at atmospheric pressure in the presence of water to a temperature no higher than about 5° C. where the other gaseous components have a substantially higher solubility in water than methane and are substantially all absorbed into the water without changing state, leaving pure, dry methane.

In an anaerobic digestion process which produces a raw gas containing methane and other gaseous components, the step of misting the gas with process water which has been separated from sludge in the anaerobic digestion process to cool the gas at atmospheric pressure to a temperature at which the other gaseous components have a substantially higher solubility in the liquid than methane and are substantially all absorbed into the liquid without changing state, leaving pure, dry methane.

In a gas separation process, the step of cooling a gas containing methane and other gaseous components in the presence of a liquid at atmospheric pressure to a temperature at which the other gaseous components have a substantially higher solubility in the liquid than methane and are substantially all absorbed into the liquid without changing state, leaving pure, dry methane, the gas being cooled by a refrigeration system which is powered by burning the methane gas.

In an anaerobic digestion process which produces a raw gas containing methane and other gaseous components, the steps of cooling the gas in the presence of a liquid at atmospheric pressure to a temperature at which the other gaseous components have a substantially higher solubility in the liquid than methane and are substantially all absorbed into the liquid without changing state, leaving pure, dry methane, and compressing and heating the methane gas and supplying the heated methane gas to a digester.

In a gas separation system:

• a source of raw gas containing methane, carbon dioxide and hydrogen sulfide, and means for cooling the gas at atmospheric pressure in the presence of water to a temperature no higher than about 5° C. so that the carbon dioxide and the hydrogen sulfide are almost totally absorbed into the water without changing state, leaving pure, dry methane gas.

In a process for separating methane gas from a raw gas containing methane, carbon dioxide and hydrogen sulfide, the step of cooling the gas in the presence of water to a temperature no higher than about 5° C. so that the carbon dioxide and the hydrogen sulfide are almost totally absorbed into the water without changing state, leaving pure, dry methane gas.

In a process for separating methane gas from a raw gas containing methane, carbon dioxide and hydrogen sulfide, the step of cooling the gas at atmospheric pressure in the presence of water to a temperature no higher than about 5° C. so that the carbon dioxide and the hydrogen sulfide are almost totally absorbed into the water without changing state, leaving pure, dry methane gas.