A carbon dioxide purification system for the treatment of a waste gas produced by a generator includes a water removal unit having at least one drying device, and a purification unit having a plurality of pressure swing adsorption devices disposed and connected in series with each other. The at least one drying device is used to reduce water vapor in the waste gas and to form a dry gas mixture having carbon dioxide gas. The pressure swing adsorption devices are used to purify carbon dioxide gas from the dry gas mixture, so as to obtain a gas product containing carbon dioxide gas with a purity of more than 99.5%.

In a cyclic adsorptive gas purification process, an impurity laden adsorbent is regenerated by exposing it first to an unheated gas for a pre-determined time period to desorb at least some of the impurity, followed by heating the adsorbent using a flowing stream of a heated gas to desorb the remaining impurities over another pre-determined time period, further followed by cooling of the adsorbent using a flowing stream of gas for yet another pre-determined time period to make it ready for repeating the adsorptive cycle. Introducing an unheated purge stream reduces the energy requirements for the regeneration step compared to a traditional TSA process.

This invention concerns a method for recovering carbon monoxide and carbon dioxide from Fischer-Tropsch off-gas by feeding Fischer-Tropsch off-gas through a column comprising an adsorbent bed, and discharging effluent, optionally rinsing the column and the adsorbent bed by feeding carbon dioxide and discharging effluent until at least 60% of the carbon monoxide that was present in the bed is discharged, pressurizing the column and adsorbent bed with carbon dioxide, rinsing the column and the adsorbent bed by feeding carbon dioxide, until at least 60% of the methane and optionally an amount equal to at least 50% of the carbon dioxide present at the commencement of this rinsing step is discharged, rinsing the column and adsorbent bed by feeding a mixture of hydrogen and nitrogen, pressurizing the column and adsorbent bed by feeding a mixture of hydrogen and nitrogen. With this method a feed comprising at least 50 vol % carbon monoxide can be produced. Furthermore, methane and carbon dioxide at a high pressure can be recovered from the Fischer-Tropsch gas. This can be fed to a gasifier or a reformer. In a preferred embodiment a gas comprising at least 80 vol % hydrogen is produced as well.

In a cyclic adsorptive gas purification process, an impurity laden adsorbent is regenerated by exposing it first to an unheated gas for a pre-determined time period to desorb at least some of the impurity, followed by heating the adsorbent using a flowing stream of a heated gas to desorb the remaining impurities over another pre-determined time period, further followed by cooling of the adsorbent using a flowing stream of gas for yet another pre-determined time period to make it ready for repeating the adsorptive cycle. Introducing an unheated purge stream reduces the energy requirements for the regeneration step compared to a traditional TSA process.

Aspects of the present invention relate to a gas treatment apparatus (1) for treating a process gas. The gas treatment apparatus (1) includes a primary treatment unit (2) and a secondary treatment unit (3), the primary and secondary treatment units (2, 3) being configured to treat the process gas. The primary treatment unit (2) includes a primary process gas inlet (10) for receiving the process gas, a first and a second primary adsorber (12, 13) for treating the process gas, and at least one primary process gas outlet for discharging the treated process gas from the first and the second primary adsorbers (12, 13). The secondary treatment unit (3) includes a secondary process gas inlet (30) for receiving the process gas, at least one secondary adsorber (32, 33) for treating the process gas, and at least one secondary process gas outlet (31) for discharging the treated process gas from the at least one secondary adsorber (32, 33) to the primary treatment unit (2). The primary treatment unit (2) is selectively configurable in a first operating mode and a second operating mode. When operating in the first operating mode, the primary process gas inlet (10) is connected to the first primary adsorber (12) to supply the process gas to the first primary adsorber (12) for treatment; and the second primary adsorber (13) is connected to the at least one secondary process gas outlet (31) to receive treated process gas from the secondary treatment unit (3) for regenerating the second primary adsorber (13). When operating in the second operating mode, the primary process gas inlet (10) is connected to the second primary adsorber (13) to supply the process gas to the second primary adsorber (13) for treatment; and the first primary adsorber (12) is connected to the at least one secondary process gas outlet (31) to receive treated process gas from the secondary treatment unit (3) for regenerating the first primary adsorber (12). Aspects of the present invention also relate to a method of controlling a gas treatment apparatus (1) to treat a process gas; and a liquid air energy storage plant.

A carbon dioxide purification system for the treatment of a waste gas produced by a generator includes a water removal unit having at least one drying device, and a purification unit having a plurality of pressure swing adsorption devices disposed and connected in series with each other. The at least one drying device is used to reduce water vapor in the waste gas and to form a dry gas mixture having carbon dioxide gas. The pressure swing adsorption devices are used to purify carbon dioxide gas from the dry gas mixture, so as to obtain a gas product containing carbon dioxide gas with a purity of more than 99.5%.