Method for prepurifying air in an accelerated tsa cycle

Abstract

The invention relates to a method for prepurifying air by means of adsorption in a TSA cycle, each recipient containing an adsorbent arranged on a radial adsorption bed, and each adsorption cycle consisting of (a) an adsorption stage during which the impurities are eliminated on the adsorbent at an adsorption temperature (rads), the air crossing the adsorption bed in a centripetal manner; (b) a regeneration stage during which the adsorbent is regenerated by flushing with a regeneration gas at a regeneration temperature (Treg), such as Treg>Tads, in order to desorb the impurities; et (c) an adsorbent cooling stage during which the temperature of the regenerated adsorbent is reduced. The maximum duration (rads) of the adsorption is 120 minutes, preferably between 60 and 120 minutes. The regeneration gas is introduced in such a way that it flushes the bed containing the adsorbent in the centrifugal direction. The maximum regeneration rate is 35% of the adsorption rate. The regeneration temperature is reached by means of a heat exchanger arrange outside the adsorber.

Description

technical field [0001] The present invention relates to a TSA process for prepurifying air to be subsequently fractionated by cryogenic processes. Background technique [0002] Traditionally, the air to be cryogenically distilled has been pre-dried, decarbonated and at least partially freed of the contained secondary air pollutants such as hydrocarbons, nitrogen oxides or similar substances. [0003] This method is often referred to as the air pre-purification method or simply the head purification method. [0004] The main purpose of this pre-cleaning is to retain and remove various atmospheric impurities that may be present in the gas stream until the content obtained is suitable for the cryogenic plant supplied with this air, regardless of the performance level or safety (requirement) of the plant. satisfactory operation. [0005] In fact, without such pretreatment, condensation and / or solidification of these impurities can occur during the cooling of the air to cryoge...

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Problems solved by technology

[0057] However, from the above, such a gas flow rate is usually unavailable, because if such a high gas flow rate can be obtained, the PSA cycle should basically be selected instead of the TSA cycle

[0058] In addition, the proportion of effective heat is reduced because the metal mass associated with piping, valves, measuring and control instruments, and the corners of the adsorber remains constant, while the mass of adsorbent and impurities to be desorbed decreases due to the shortened cycle time , which is equivalent to greatly increasing the energy consumption of the entire purification method

[0059] Another disadvantage caused by increasing the regeneration gas flow rate is the increase in the pressure drop of the system, which also increases the energy consumption, unless the diameter of the adsorber is increased, which in turn increases the thermal inertia and dead volume of the system, etc.

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