Liquid-liquid phase change absorbent for separating acid gas

Abstract

The invention relates to a liquid-liquid phase change absorbent for separating acid gas. The absorbent comprises the following components in percentages by mass: 10-60% of ethanolamine, 20-60% of other water-soluble organic compounds and 10-70% of water. Before the liquid-liquid phase change absorbent absorbs acid gas, the liquid-liquid phase change absorbent is a homogeneous-phase body, and after the liquid-liquid phase change absorbent absorbs acid gas, the liquid-liquid phase change absorbent forms into liquid-liquid phase spontaneously; the upper liquid phase is a barren liquor phase which loads acid gas, the lower liquid phase is a rich liquor phase which loads acid gas, and only the rich liquor phase enters a desorption unit, so that desorption energy consumption is reduced. After the liquid-liquid phase change absorbent absorbs acid gas, the liquid-liquid phase change absorbent forms into liquid-liquid phase for facilitating separation; according to characteristics of the absorbed acid gas, ratio of the absorbent can be adjusted for adapting to optimal volume ratio of the upper liquid phase and the lower liquid phase and load capacity of the absorbent in the process, so that amount of the rich liquor phase which enters the desorption unit in industrial environment is reduced, and energy consumption in the desorption process is reduced as possible.

Description

technical field [0001] The invention belongs to the technical field of gas separation, and in particular relates to a liquid-liquid phase change absorbent for acid gas separation. Background technique [0002] Exhaust gas from industrial processes and exhaust from automobiles contains a large amount of CO 2 、H 2 S, SO 2 and other acidic gases, seriously polluting the environment. Acid gas separation technology is usually used to reduce the acid gas impurities to an acceptable level. Currently commonly used acid gas separation technologies mainly include: chemical absorption method, physical absorption method, adsorption method, membrane separation method and ionic liquid method, among which chemical absorption method is the most mature method for industrial application. Ethanolamine (MEA) is the most widely used absorbent in the chemical absorption process. However, the existing chemical absorption process using ethanolamine (MEA) has the disadvantage of high energy con...

AI Technical Summary

Problems solved by technology

The above two patents only increase CO in the absorbent 2 Loading way to reduce CO 2 Separation energy consumption, unable to reduce water evaporation energy consumption and absorbent heating energy consumption in the desorption process

Chinese patent application "A Method for Absorbing and Separating Carbon Dioxide" (Application No. 200910244197.2, published on June 16, 2010) uses alcohol amine compounds such as MEA, and uses glycol compounds with less than 10 carbon atoms to replace water as a solvent. The high boiling point of glycol solvents reduces solvent evaporation during the desorption process. Although this patent reduces the energy consumption of water evaporation, the energy consumption of sensible heat for absorbent heating is not considered, and the viscosity of glycol solvents is high, which is not conducive to mass transfer

[0004] Chinese patent application "An amine absorbent and CO capture 2 Method" (application number 201280031688.9, published on May 28, 2014) proposes an amine absorbent and captures CO 2 method, absorbents DIPAE / MAPA, DIPAE / DAB, N-TBDEA / DiAP, DEEA / DMPDA absorb CO 2 After forming two phases, the load CO 2 The enriched phase enters the desorption unit to reduce the amount of desorption liquid and reduce the energy consumption of desorption. The method of this patent application can simultaneously reduce the energy consumption of water evaporation and the energy consumption of absorbent heating, but the concentration of absorbent is high, the viscosity is high and the Expensive, difficult to synthesize, not conducive to its application in industry

Chinese patent application "for CO 2 Combined CO for split systems 2 Phase Change Absorbent" (Application No. 201310212240.3, published on December 28, 2013) proposes an amino-silicone absorbent that absorbs CO 2 After that, solid-liquid two phases are formed, and the solid is carbamate. The regeneration of the absorbent can be realized by heating the solid carbamate during the desorption process. Since the solid is generated during the absorption process, it is easy to block the pipeline, which brings great advantages for industrial applications. Inconvenience

US Patent "PHASETRANSITRONALABSORPTIONMETHOD" (Application No. 11 / 279095, Patent No. US7541011B2, Publication No. September 2, 2009) discloses a method for separating gas from a gas mixture using an absorbent containing at least one activator and at least one solvent. method, the only example of the absorbent is the aqueous mixture of DEA and potassium carbonate, the above patents do not specify the solvent that causes the expected phase separation, and the composition of the absorbent and the concentration of each component are not specified in the examples. Experiments show that different compositions Most absorbents cannot undergo phase separation after the absorption operation, so it is impossible to implement