Impure oxygen@ large amt. prodn. avoiding large dia. low pressure column - by distn. of air using a double distn. column with medium and low pressure columns, avoiding extra distn. column mfr., utilising purificn. device, compressor and turbine

摘要

The prodn. comprises the distn. of air in an installation comprising a principal air compressor (1), a device (2) for purifying air by adsorption, a heat exchanger (3) and a double distn. column (4) with a medium pressure column is released into a turbine (11), using at least part of the mechanical energy generated by the turbine to compress (in 10) at least part of the air from the principal air compressor and the gas is used to regenerate the adsorbent in the purifn. device. Installation for producing oxygen at a purity of less than ca. 97% comprises a principal air compressor (1), a device (2) for purifying air by adsorption, a thermal exchanger (3) and a double distn. column (4) with a medium pressure column (5) and a low pressure column (6). The installation also has first a turbine (11) for the release of gas, with the inlet connected to the medium pressure column and the outlet is connected to the purifcn. device, and second an air compressor (10) which is driven by the mechanical energy developed by the turbine. The turbine is pref. fed at a temp. close to or significantly below ambient, and part of the cold produced by the turbine is used to chill the air fed into the compressor (9,10) and/or the purificn. device (2). Or the regeneration gas is reheated (in 22) at the hot end of the thermal exchanger before introducing into the turbine and the temp. of the installation is ensured by the expansion of a circulating fluid in a second turbine (24). The compression (in 10) raises the air to the pressure in the medium pressure column. Oxygen is produced in liq. form in the low pressure column, taken by pump to a high pressure and vaporised in the thermal exchanger at the high pressure by heat exchange with the compressed air. The regeneration gas is nitrogen from the top of the medium pressure column or a gas extracted at an intermediate level from the column. The input to the turbine is at ca. ambient temp. or a temp. significantly below ambient and the thermal exchanger includes tubes for cooling the air fed to the air compressor (10) and/or the purificn. device. The tubes exchange heat with the tubes for reheating the gas from the turbine. There is a heating device (22) for the regeneration gas before it enters the turbine at the hot end of the thermal exchanger. The output from the compressor is connected to the medium pressure column. The installation also comprises a pump for oxygen (12) connected to the bottom of the low pressure column and to the oxygen vaporisation tubes in the thermal exchanger, so the treated air is compressed before entering the thermal exchanger. ADVANTAGE - The system ovecomes the problem of producing large amts. of oxygen without having to make large dia. low pressure columns or an extra distn. column.