Method for completely reclaiming tail gas of polyethylene device

A technology of polyethylene and tail gas, which is applied in the direction of combined devices, separation methods, chemical instruments and methods, etc., can solve the problems of not reaching zero emissions, and achieve the effect of avoiding emissions

Active Publication Date: 2009-09-16
CHINA PETROLEUM & CHEM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] CN101265153A discloses the method utilizing membrane separation and recovery process to reclaim organic hydrocarbons and nitrogen in polyethylene (PE) plant tail gas, but this process is only effective for the recovery of normal hexane and nitrogen, and still has a large amount of carbon-containing two or more such as ethylene, ethyl ether, etc. The tail gas of alkanes and other hydrocarbons needs to be flared and bu...

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  • Method for completely reclaiming tail gas of polyethylene device
  • Method for completely reclaiming tail gas of polyethylene device
  • Method for completely reclaiming tail gas of polyethylene device

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0032] Example 1: The tail gas temperature after the high-pressure condensate tank of a polyethylene plant in a petrochemical enterprise: -10°C, and pressure: 0.85MpaG. The polyethylene tail gas enters the membrane recovery unit after being heated by steam. First, the raw material gas is pretreated, and the solid particles and liquid droplets contained in the raw material gas are removed through the coarse filter and the fine filter. The temperature is 1.4°C and the pressure is 0.75MpaG. Then enter the two-stage membrane separator, the pressure difference between the front and back of the two-stage membrane is less than 0.1Mpa after separation, there is 464Nm 3 / hr The temperature of permeate gas is 7℃, returning to the compressor inlet of the discharge system, 1271Nm 3 / hr The exhaust gas temperature is 7℃ and enters the buffer tank. The composition of exhaust gas, permeate gas and exhaust gas is shown in the table below.

[0033] Table 2. Exhaust gas condition table of polyethyl...

Embodiment 2

[0043] Example 2: The tail gas temperature after the high-pressure condensate tank of a polyethylene plant in a petrochemical enterprise: -10°C and the raw material gas pressure: 0.9MpaG. After steaming and heating, the polyethylene tail gas enters the membrane recovery system. First, it enters the raw material gas pretreatment, and the solid particles and liquid droplets contained in the raw material are removed through the coarse filter and the fine filter. The temperature is 5°C and the pressure is 0.75MpaG. The pressure difference before and after the exhaust gas passes through the coarse filter and the fine filter is less than 10kpa. Then enter the secondary membrane separator. After separation, the permeate temperature is 5°C and the pressure is 30kpa and returns to the compressor inlet of the discharge system. The exhaust tail gas temperature is 7°C and the pressure is 0.7Mpa and enters the buffer tank. The composition of permeate gas and exhaust gas is shown in the table b...

Embodiment 3

[0051] Example 3: After the tail gas of a high-pressure condensate tank of a polyethylene plant in a petrochemical enterprise is heated by low-pressure steam heating, the temperature: 45°C, and the pressure: 0.85MpaG. The polyethylene tail gas enters the membrane recovery unit. First, the raw material gas is pretreated, and the solid particles and liquid droplets in the raw material gas are removed through the coarse filter and the fine filter. The temperature is 40°C and the pressure is 0.75MpaG. Then enter the secondary membrane separator, after separation, there is 504Nm 3 / hr permeate temperature 37℃, return to the compressor inlet of the discharge system, 1395Nm 3 / hr The exhaust gas temperature is 37℃ and enters the buffer tank. The composition of exhaust gas, permeate gas and exhaust gas is shown in the table below.

[0052] Table 6. Exhaust gas condition table of polyethylene plant of a petrochemical enterprise

[0053]

[0054] Calculating from the above table, the recov...

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Abstract

The invention relates to a method for completely reclaiming tail gas of a polyethylene device, which is a method used for reclaiming and recycling a comonomer, an induction condensing agent and ethene in the tail gas after the polyethylene device passes through a high-low pressure cooling and condensing reclaiming system and completely classifying and reclaiming hydrocarbon components with low pressure and high nitrogen content in the tail gas. The tail gas of the polyethylene device first enters a membrane separation reclaiming unit to reclaim the comonomer, the induction condensing agent and the ethene in the tail gas; the tail gas is cycled to an inlet of a compressor, and then returns to a reaction system for reclamation. The waste gas after membrane separation and reclaiming enters a buffer tank; the waste gas discharged by the buffer tank to a flare is introduced to a pressure swing adsorption system for reclamation; the hydrocarbon components are separated from the waste gas, and enter a fuel gas system for comprehensive utilization; and simultaneously concentrated nitrogen is used for the device to purge gas to realize complete reclaiming of the tail gas and zero discharge of flare gas. The method has short production process technical flow, simple operation and easy control, embodies the comprehensive utilization of resources and is favorable for environmental protection.

Description

Technical field [0001] The present invention relates to a method for recycling tail gas of a polyethylene device. More specifically, the present invention relates to a method for completely sorting and recovering tail gas from a polyethylene device through a high and low pressure cooling condensation recovery system. Exhaust gas includes process exhaust gas and flare gas in normal production process, which are hydrocarbon components with high nitrogen content. Background technique [0002] Polyethylene (PE) equipment occupies a very important position in the polymerization process. In the PE production process, many unreacted monomers ethylene, hydrogen, comonomers (such as butene-1, hexene, octene, etc.) and inducing condensing agents (such as isopropyl) are taken out while the inert gas is discharged from the reactor. Pentane, hexane) and so on. At the same time, the polyethylene powder also contains a lot of unreacted monomer ethylene, comonomers (such as butene-1, hexene, oct...

Claims

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Application Information

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IPC IPC(8): B01D50/00
Inventor 姜立良李连福唐旭东文红梅曾芳勇
Owner CHINA PETROLEUM & CHEM CORP
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