Method and device for degassing solid polymer and recovering effluent gas

Abstract

The invention discloses a method for degassing a solid polymer and recovering effluent gas. A solid polymer enters a degassing container for decompression and is subjected to three degassing processes: 1) the solid polymer fully contacts with a gaseous reacting substance to remove the most of a solvent and an unreacted monomer in the solid polymer; 2) the processed solid polymer fully contacts with inert gas to remove the gaseous reacting substance and further remove the solvent and the unreacted monomer; and 3) the processed solid polymer fully contacts with the inert gas containing a catalyst deactivator. The effluent gas discharged in the degassing steps 1) and 2) is separated and processed from gas after being recovered, and the solvent, the unreacted monomer and a degassing medium are all recovered and utilized. The invention also discloses a device for implementing the method. With the method disclosed by the invention, degassing time for a polymer is shortened, the use amount of the degassing medium is reduced, the solvent and the unreacted monomer can be effectively recovered, and the degassing medium is recycled, thereby preventing micromolecules from being accumulated, reducing emission amount and lowering energy consumption. The method has the advantages of strong realistic significance and application value.

Description

technical field [0001] The invention relates to the technical field of solid polymer treatment, in particular to a method for removing solid polymers, especially solvents and unreacted monomers in polyolefin resins, by using gas-phase reactive substances and inert gases, and recovering and recycling exhaust gas and device. Background technique [0002] In the polymerization reaction, depending on the process and physical properties, the polymerization product will be in different states, among which the polymer is typically discharged from the reactor in the form of solid powder, such as the gas phase polyolefin process. When the solid polymer is discharged from the reactor, there are often residual solvents and unreacted monomers in the polymer powder. Taking the gas-phase fluidized bed production process of linear low-density polyethylene (LLDPE) as an example, the LLDPE powder contains unreacted Monomers, comonomers and condensing agents such as ethylene (C 2 h 4 ), pr...

AI Technical Summary

Problems solved by technology

This method can effectively make the solid polymer degassing, and can also effectively utilize the solvent and / or unreacted polymerization feed that reclaims from the solid polymer, yet, there is weak point in this method: (1) through step ( i) The polymer powder after degassing contains a large amount of polymer feed, which is removed by inert gas in step (ii), and the resulting discharge contains inert gas, polymer feed and water The gas is not recovered, but discharged to the torch, which causes a serious waste of raw materials, increases production costs, and pollutes the environment; (2) the drying gas of step (i) contains hydrogen, and the polymer discharged from the reactor It also contains hydrogen, which cannot be effectively separated and gradually accumulates in the degassing container, which will affect the degassing effect of the polymer, increase potential safety hazards, and even affect the entire production system in severe cases until the shutdown

[0010] In summary, the existing solid polymer degassing and exhaust gas recovery methods have disadvantages such as low degassing efficiency and exhaust gas recovery efficiency, high energy consumption, large raw material consumption, and unfriendly environment. Therefore, a degassing method is invented. A solid polymer degassing method with high gas efficiency, effective recycling of raw materials, energy saving and environmental friendliness has high economic benefits and practical significance

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