Multi-loop condensation technology for recovery of propylene in polypropylene device tail gas

Abstract

The invention discloses a multi-loop condensation technology for recovery of propylene in polypropylene device tail gas. For tail gas containing steam, firstly, drying processing is carried out or a frost prevention plug and a defrosting measure are arranged in the condensation process of the tail gas. A refrigerating unit is arranged, glycol refrigerated water is generated, and tail gas in different discharging points is condensed by glycol refrigerated water through heat exchangers respectively. Glycol refrigerated water and the tail gas in different discharging points are subjected to heat exchange in respective heat exchanges respectively, and the vast majority of propylene in the tail gas is condensed. Because ingredients and pressures of tail gas in different discharging points are different, respective condensation is selected, the self pressure of tail gas can be utilized, and propylene is recovered in an effective manner. In the obtained condensate liquid, the content of propylene is more than 90% (mass), the content of propylene and propane is more than 99.7% (mass), the total content of light components of hydrogen, nitrogen, C2 and the like is less than 0.15% (mass), and recovery of propylene is achieved indeed.

Description

technical field [0001] The invention belongs to the technical field of petrochemical industry, in particular to a multi-loop condensation process for recycling propylene in the tail gas of a polypropylene device. Background technique [0002] Domestic polypropylene devices are roughly divided into three processes: liquid-phase loop method, gas-phase fluidized bed method, and small-body polymerization kettle method. In the actual production of these three processes, a certain amount of tail gas will be emitted, the main component of which is propylene. Taking a set of 200,000 tons / year liquid-phase loop method polypropylene plant as an example, there are 3 exhaust emission points, as shown in the following table-1: [0003] Table-1 Situation of Exhaust Gas Discharge Points of the Liquid-Phase Loop Method Polypropylene Plant [0004] [0005] Calculated according to Table-1 above, the three tail gases total 600kg / h, of which propylene is 531kg / h. If the tail gas is not r...

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Problems solved by technology

[0007] Some domestic polypropylene devices use membrane separation, pressure swing adsorption and other methods to recover propylene from tail gas. These methods generally have the problem of poor recovery effect. Compared with the present invention, the investment is large, the energy consumption is high, and the process is complicated.

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