Method for separating mixed gas FTrPSA in reaction for preparing propylene by dehydrogenizing propane

Abstract

The invention discloses a method for separating a mixed gas FTrPSA in a reaction for preparing propylene by dehydrogenizing propane. The method comprises the following steps: (1) taking a reactant mixed gas in a reaction zone for preparing the propylene by dehydrogenizing the propane as a raw gas, and performing pre-treatment to obtain a raw gas A; (2) enabling the raw gas A to enter a medium-hightemperature PSA concentrating system with the operating temperature of 30 to 160 DEG C and the operating pressure of 0.2 to 4.0 MPa to obtain a hydrogen-rich gas component and a C<2+>-rich concentrated gas; (3) directly using part of the hydrogen-rich gas component as circulating hydrogen required by a PDH reaction zone, and enabling the other part of the hydrogen-rich gas component to enter a PSA hydrogen extracting process to obtain a product, namely, the hydrogen, wherein desorbed gas of the hydrogen is directly output as fuel; and (4) after the C<2+>-rich concentrated gas is cooled, compressed and subjected to gas-liquid separation, recycling C<2+> and forming a liquid to enter a PDH product fractionation zone to obtain a propylene product, and returning the unreacted propane to propane raw gas to mix and enter the PDH reaction zone for reacting. Through the combination of the processes of performing pre-treatment, medium-high temperature PSA concentrating and PSA hydrogen extracting, the comprehensive energy consumption is low, and the equipment is low in investment cost and is safe.

Description

technical field [0001] The invention relates to the field of energy-saving and consumption-reducing methods for the preparation and separation of propylene and hydrogen in the petrochemical industry, and more specifically relates to a method for separating FTrPSA reaction mixture gas from propane dehydrogenation to propylene. Background technique [0002] Propylene is an important petrochemical basic raw material second only to ethylene. In the long run, the global market will continue to be extremely tight in supply for a long time. However, in recent years, breakthroughs have been made in the development of unconventional natural resources in the world, such as shale gas, petroleum-associated gas, and marine combustible ice, especially the successful commercial development of a large number of shale gas resources, making long-term, stable, relatively Inexpensive propane resources have become possible, and furthermore, the project of producing propylene (PDH) through dehydr...

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Problems solved by technology

[0009] Aiming at the defects of high energy consumption, corrosion resistance, different specifications of circulating hydrogen and product hydrogen in the product separation section of the above-mentioned PDH and hydrocarbon mixed gas dehydrogenation to olefins production process, the investment and operation costs are too high. The purpose of the invention is to provide a FTrPSA separation method for the reaction mixture gas from propane dehydrogenation to propylene, through the combination of pretreatment, medium and high temperature PSA concentration and PSA hydrogen extraction process, to achieve simultaneous acquisition of circulating hydrogen / product hydrogen and C2+ group rich in propylene Separation and extraction of components, low comprehensive energy consumption, low equipment investment cost, and no potential safety hazards

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