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Cleaning method for high-pressure tubular polyethylene reaction system

A tubular reaction and reaction system technology, used in cleaning methods and utensils, chemical instruments and methods, cleaning hollow objects, etc. The effect of low body consumption, long production cycle and large production capacity

Inactive Publication Date: 2021-06-22
ZHEJIANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to provide a lightening reaction system to overcome the problems such as blockage of pipes and separators, increase of system pressure difference, and decrease of heat removal capacity during the long-term operation of the tubular polyethylene reaction system of high pressure and low density polyethylene. System fouling, blockage, deep cleaning method to extend the operating cycle

Method used

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  • Cleaning method for high-pressure tubular polyethylene reaction system
  • Cleaning method for high-pressure tubular polyethylene reaction system
  • Cleaning method for high-pressure tubular polyethylene reaction system

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0034] use as figure 1The high-pressure low-density polyethylene tubular reaction system cleaning process shown above is used for cleaning. Control the cleaning pressure inside the tubular reactor to 2.3MPa, and the cleaning temperature to 100°C, introduce the cleaning solvent component—toluene from the inlet of the tubular reactor, control the flow rate at 4-6m / s, and gradually dissolve and adhere to the Substances such as polyethylene on the pipe wall. The cleaned mixed solvent is exported from the outlet of the tubular reactor, and passes through the cooler and separator in turn to separate out the cleaned polyethylene and other impurities, and the recyclable solvent enters the cleaning process again. The entire cleaning process takes 30 hours , for multiple cleanings. Combined with the temperature and pressure changes of the reaction system before cleaning, comparing the reaction system before and after cleaning, it was found that the total pressure difference of the rea...

Embodiment 2

[0039] use as figure 1 The high-pressure low-density polyethylene tubular reaction system cleaning process shown above is used for cleaning. Control the cleaning pressure inside the tubular reactor to 2MPa, and the cleaning temperature to 125°C, introduce the cleaning solvent component—xylene from the inlet of the tubular reactor, control the flow rate at 4-6m / s, and gradually dissolve and adhere to the Substances such as polyethylene on the pipe wall. The cleaned mixed solvent is exported from the outlet of the tubular reactor, and passes through the cooler and separator in turn to separate out the cleaned polyethylene and other impurities, and the recyclable solvent enters the cleaning process again. The entire cleaning process takes 20 hours , for multiple cleanings. Combined with the temperature and pressure changes of the reaction system before cleaning, comparing the reaction system before and after cleaning, it was found that the total pressure difference of the react...

Embodiment 3

[0044] use as figure 1 The high pressure LDPE tubular reaction system shown is cleaned. The cleaning pressure inside the tubular reactor is controlled to be 2MPa, the cleaning temperature is 125°C, the solvent component for cleaning—xylene, is introduced from the inlet of the tubular reactor, and the flow rate is controlled at 4-6m / s. The pressure wave of the flow is realized by adjusting the pressure valve switch at the end of the reactor to realize the shock cleaning. By changing the opening of the pressure valve, a shock wave is formed in the tubular reactor, and the valve opening is periodically adjusted according to a certain frequency to gradually dissolve the formed polyethylene sticky wall material. The entire online cleaning process takes 15 hours and is carried out many times. cleaning. Under the same control conditions, comparing the reaction system before and after cleaning, it was found that after cleaning, the total pressure drop of the reaction system decrease...

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Abstract

The invention discloses a cleaning method for a high-pressure tubular polyethylene reaction system. A high-pressure tubular polyethylene production process system is in a supercritical fluid state, a phase separation behavior easily occurs in the state, polyethylene can be separated out under a certain condition to form wall adhesion without a fixed position. The cleaning method is characterized in that a solvent component with the solubility parameter within the range of 7-11cal<1 / 2>*cm<-3 / 2> is introduced from an inlet of a high-pressure tubular polyethylene reactor to dissolve wall adhesion substances accumulated in the system, a cleaned mixed solvent component is poured out from an outlet after cleaning, and the process needs to be carried out offline or is combined with pressure fluctuation to form shockwave on-line cleaning so that solubility can be enhanced for shock flow cleaning. According to the cleaning method, the problems that the final property of a product is influenced due to the fact that operation parameters are changed during traditional wall adhesion elimination and the yield is reduced due to wall adhesion are solved while the wall adhesion substances are deeply cleaned.

Description

technical field [0001] The invention relates to a cleaning method for a high-pressure polyethylene tubular reaction system. Specifically, by considering the effect that polyethylene resin can be dissolved and softened in an organic solvent, an organic solvent with a suitable solubility parameter is added to the tubular reactor, and the Dissolution and cleaning conditions are adjusted to effectively clean the reaction system and increase the productivity of the reactor. Background technique [0002] The high-pressure tubular polyethylene production process unit has high single-pass conversion rate, low monomer consumption, long production cycle, large production capacity, and simple and reliable equipment form, but it often encounters the problem of sticking to the wall during operation, that is, the molten LDPE deposits and adheres to the inner wall of the reaction tube to form a dense polyethylene film. Due to the boundary layer effect of the fluid in the tube, the fluid v...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B08B9/032B08B13/00C11D7/24C11D7/50
CPCB08B9/0321B08B13/00C11D7/247C11D7/5027
Inventor 任聪静范小强王靖岱历伟黄正梁孙婧元杨遥陈毓明童雪青
Owner ZHEJIANG UNIV
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