Adsorption process and apparatus, particularly for purifying atmospheric air for separation by distillation, where a residual gas from the distillation is warmed and used to regenerate the adsorbers

摘要

For part of the regeneration phase, an additional heating stage uses an auxiliary heat source to heat the regeneration fluid before it passes through the adsorber, while the compressed gas to be treated is cooled by an auxiliary refrigeration. Otherwise, heat exchange takes place between the gas to be treated and the regeneration fluid. The adsorption process involves: (a) compressing the gas to be treated; (b) circulating it through an adsorber (7, 8) in the adsorption phase; and (c) passing a regeneration fluid flow through the adsorber in the regeneration phase. (c1) During a first part of the regeneration phase, there is an indirect heat exchange between the gas to be treated from stage (a) and the regeneration fluid, to cool the gas to be treated and warm the regeneration fluid. (c2) During a second part of the regeneration phase, the regeneration fluid is passed through the adsorber without the heat exchange in (c1), since (d) there is an auxiliary refrigeration of the gas to be treated during (c2) using an auxiliary source of cooling to treat at least part of the flow through the adsorber. This auxiliary cooling is carried out inside or outside the heat exchanger (3'). An additional cooling stage cools the gas from stage (c1) before it passes through the adsorber. The gas to be treated is atmospheric air and stage (b) purifies it from water and carbon dioxide. The resulting air is then distilled to produce at least one of its constituents and a residual gas which forms the regeneration fluid. An Independent claim is also included for apparatus for carrying out the process, comprising a compressor (2) connected to an adsorber (7, 8) in the adsorption phase; means of circulating the regeneration fluid in the adsorber in the regeneration phase; and a heat exchanger (3') for heating the regeneration fluid by indirect contact with the gas from the compressor. There is also a bypass (30) which can send the regeneration fluid to the adsorber without passing through the heat exchanger, and auxiliary coolers (28) and heaters (14) respectively to cool the gas to be treated and heat the regeneration fluid when the bypass is in operation. The assembly is at the head of a unit separating air by distillation, to purify the inlet air of water and carbon dioxide (CO2). The regeneration fluid is a residual gas from the distillation unit.