Apparatus and air separation plant

An air separation plant for producing an oxygen product comprising:

• a compressor to compress the air;
• a pre-purification unit connected to the compressor to purify the air and thereby to produce a compressed and purified air stream;
• a booster compressor connected to the pre-purification unit;
• means for cooling part of the compressed and purified air stream and for cooling a compressed air stream formed from a further part of the compressed and purified air stream compressed in the booster compressor;
• an air separation unit connected to the cooling means so as to receive the part of the compressed and purified air stream and the compressed air stream after having been cooled and configured to rectify the air and thereby produce a liquid oxygen stream having an oxygen purity of no less than about 90 percent by volume;
• a pump connected to the air separation unit to pump the liquid oxygen stream, thereby to produce a pumped liquid oxygen stream;
• the cooling means comprising a heat exchanger positioned between the pump and the booster compressor and also configured such that the pumped liquid oxygen stream is heated within the heat exchanger through indirect heat exchange with at least the compressed air stream to produce the oxygen product as a supercritical fluid and the compressed air stream as a liquid;
• the pump set to pump the liquid oxygen stream so that the pumped liquid oxygen stream will be pressurized to an oxygen pressure in a range above about 55 bar(a) and no greater than about 150 bar(a) upon entering the heat exchanger;
• and
• the booster compressor set to compress the compressed air stream so that the compressed air stream will have an air pressure upon entering the heat exchanger equal to a value within a range of no less than ten percent below and no greater than 20 percent above a quantity equal to 0.00003×(oxygen pressure)3−(0.01141×(oxygen pressure))+2.263×(oxygen pressure)+2.5175.