An air separation plant is provided that includes a plurality of air compressors, a plurality of air purification units, and one or more cold boxes. In a first mode of operation, a first air compressor is configured to compress air to a higher pressure than a second air compressor. In a second mode of operation, the second air compressor is configured to compress air to a higher pressure than during the first mode of operation.

The invention relates to a method for providing high-pressure oxygen using low-pressure oxygen containing water, in which method the low-pressure oxygen is subjected to a drying process and subsequently to a pressure increase, the drying process comprising an adsorption step. In the adsorption step, a regeneration gas is used which is provided using oxygen that is provided using the pressure increase and using at least part of the low-pressure oxygen. The pressure increase is performed above 0 C. and using a plurality of compressors or compressor stages which have an intercooler between two compressors and/or compressor stages. At least part of the oxygen which is used to form the regeneration gas is removed from the pressure increase between two of the compressors or compressor stages upstream of the intercooler. Alternatively, the pressure increase is carried out by means of internal compression.

In a method for compressing a gas, the gas is compressed in a compressor having an intermediate stage and a final stage, an intermediate cooler for cooling the gas downstream of the intermediate stage and a final cooler for cooling the gas downstream of the final compression stage, a refrigerant coming from a source is divided into a first flow and a second flow, the first flow is sent to cool the intermediate cooler and the second flow is sent to cool the final cooler, the first and second heated flows being at different temperatures, the first heated flow is sent to provide heat to an element, producing a first cooled flow, and the second heated flow is mixed with the first cooled flow and the mixture is sent to the source.

In this air separation method, compressed air is successively cooled in a cooling step, purified in a purifier and sent to a cryogenic section producing at least one product containing at least one air component. The purifier comprises at least two switchable adsorber vessels, one of them being in adsorption mode. Two sources of compressed air are provided. The first source is an air grid supplying compressed air to further consumers. The second source is a dedicated main air compressor delivering compressed air to the cooling step only. Air portions from both sources are mixed at a mixing point. The air flow to the cryogenic section is controlled by measuring at least one parameter of the air flow upstream or downstream the purifier. According to such measurement, the air flow at the outlet of the main air compressor is set.

A liquid air energy conversion system is provided that is a variant of conventional gas turbine combined cycle (GTCC) that integrates three subsystems or unit operations, namely a main air compression and pre-purification subsystem, a deep sub-ambient gas compression subsystem, and a power expansion and waste heat recovery subsystem. The disclosed liquid air energy conversion system enhances and optimizes the energy extraction from liquid air by avoiding main air compression directly associated with the gas turbine and the air fed to the overall system and process is limited to the air flow required to vaporize the liquid air.

An adsorber for utilization in purification systems for cryogenic fluid processing can include a first layer of adsorbent material and a second layer of adsorbent material within a bed of adsorbent material within the adsorber. The first layer can include alumina or other water removal adsorbent material while the second layer can include NaMSX or other suitable molecular sieve adsorbent material. The first layer can be sized to be substantially smaller than the second layer to facilitate a pre-selected ratio of water adsorption to molecular sieve adsorption so that water can break through the first layer to the second layer during purification operations while the volume of the adsorber can be provided in a much smaller size with much less adsorbent material utilized in the bed as compared to conventional designs. Embodiments can provide an increased purification operational capacity with reduced need for adsorbent material.