Method and device for recovering C2 components in dry gas

Abstract

The invention relates to the field of dry gas treatment, and discloses a method and a device for recovering C2 components in dry gas. The method comprises the following steps: (1) compressing raw material dry gas, cooling the obtained compressed gas, and carrying out gas-liquid separation to obtain a gas phase and a liquid phase; (2) contacting the gas phase with an absorbent for C2 component absorption to obtain absorption tail gas and absorption pregnant solution, returning the absorption pregnant solution and mixing the absorption pregnant solution with the compressed gas; (3) reducing the pressure of the liquid phase, performing methane desorption to obtain desorbed gas and a rich absorbent, and returning the desorbed gas to the step (1) for compression or discharge; and (4) desorbing and separating the rich absorbent to obtain a lean absorbent and concentrated gas mainly comprising C2 components, and returning the lean absorbent and mixing the lean absorbent with the absorbent. The C2 component obtained by adopting the method provided by the invention is high in recovery rate, and the total energy consumption of the device is low.

Description

technical field [0001] The invention relates to the technical field of dry gas treatment, in particular to a method and a device for recovering carbon components in dry gas. Background technique [0002] At present, the methods for recovering ethane and ethylene components from dry gas that have been industrialized mainly include: [0003] (1) The cryogenic separation method has a mature process, high ethylene recovery rate and high purity, but requires a drier and a propylene refrigeration device or an ethylene-propylene composite refrigeration device, which requires a large investment and high energy consumption; [0004] (2) The pressure swing adsorption method is simple in operation and generally low in energy consumption, but the product purity is low and the recovery rate of carbon two components is low. When the scale of raw material dry gas treatment is large, the equipment investment and land occupation are large; [0005] (3) Shallow cold oil absorption method, th...

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Problems solved by technology

[0003] (1) The cryogenic separation method has a mature process, high ethylene recovery rate and high purity, but requires a drier and a propylene refrigeration device or an ethylene-propylene composite refrigeration device, which requires a large investment and high energy consumption;

[0004] (2) The pressure swing adsorption method is simple in operation and generally low in energy consumption, but the product purity is low and the recovery rate of carbon two components is low. When the scale of raw material dry gas treatment is large, the equipment investment and land occupation are large;

[0005] (3) Shallow cold oil absorption method, the process is safe and reliable, the recovery rate of C2C3 is high, and there is no requirement for the sulfur content and water content in the raw gas, but the reboiler of the absorption tower (or methane desorption tower) tower kettle The load is large, and the consumption of low-pressure steam in the whole process is large

[0009] To sum up, in order to ensure the purity of the product gas and the recovery rate of carbon 2 when recovering the carbon 2 components in the dry gas, the existing process generally adopts the cryogenic / intercooling separation route, which requires drying and dehydration of the raw material gas, and the equipment investment Larger, or adopt the shallow cooling oil absorption route, usually carry out the oil absorption and methane desorption process under higher pressure, the steam consumption of the reboiler in the methane desorption process is relatively large, and the energy consumption of the device is relatively high

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