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Method for judging polymerization reaction condition at initial production stage of polyethylene process

A technology of polymerization reaction and polyethylene, applied in the direction of material separation, instrumentation, analysis of materials, etc., can solve problems such as economic loss, long induction period, polymerization accidents, etc., and achieve the effect of preventing polymerization accidents

Active Publication Date: 2012-05-16
CHINA PETROLEUM & CHEM CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, chromium-based catalysts have a relatively long induction period for initiating polymerization reactions, and the release of catalyst activity tends to increase gradually. Generally, it takes about five or six hours for the reaction parameters to change significantly. This judgment lag will give the operator The follow-up work of the personnel brings great difficulties. Sometimes the wrong judgment of the actual triggering status of the catalyst leads to the wrong operation of the reactor, and the reaction process cannot be accurately predicted, resulting in the untimely adjustment of the catalyst addition, which leads to excessive or excessive polymerization. A polymerization accident occurs without triggering a polymerization reaction, which seriously endangers the safety of driving
In addition, if the catalyst fails to initiate the polymerization reaction, the judgment time of five or six hours will lead to a large amount of waste of nitrogen and ethylene, resulting in huge economic losses
Currently there is no effective way to solve this problem

Method used

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  • Method for judging polymerization reaction condition at initial production stage of polyethylene process
  • Method for judging polymerization reaction condition at initial production stage of polyethylene process
  • Method for judging polymerization reaction condition at initial production stage of polyethylene process

Examples

Experimental program
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Effect test

Embodiment 1

[0020] Example 1: figure 2 It is the result of analyzing the circulating gas in the reactor by gas chromatography during the successful start-up of the unit. The catalyst used during start-up is S-2 type chromium catalyst, that is, bis(triphenylsilyl)chromate is used as the main catalyst and diethylaluminum oxide is used as the reducing agent. Before judging that the polymerization reaction initiated by the catalyst is successful, only ethylene monomer is added to the reactor, and no comonomer is added, so the olefins other than ethylene appearing in the recycle gas at this time should be produced by ethylene oligomerization.

[0021] figure 2 Among them, the spectrogram (a) is the circulating gas chromatogram when the oxygen value of the water in the reactor is qualified and no catalyst is put in. It can be seen from the figure that the circulating gas before the catalyst is actually refined ethylene without other impurities. The spectrum of chromatographic analysis is th...

Embodiment 2

[0023] Example 2: image 3 It is the result of analyzing the circulating gas in the reactor by gas chromatography during the successful start-up of the unit. The catalyst used during start-up and the reaction conditions of only adding ethylene monomer in the reactor are the same as in Example 1.

[0024] image 3 Among them, the meanings of spectrograms (a)-(e) are the same as in Example 1.

[0025] according to image 3 The gas chromatographic analysis results show that: spectrogram (a), when no catalyst is added, no 1-butene and 1-hexene are detected in the recycle gas, indicating that ethylene has not yet undergone polymerization; After 1 hour of the catalyst, traces of 1-butene and 1-hexene can be detected from the recycle gas. According to the theory that chromium-based catalysts can simultaneously catalyze ethylene oligomerization and polymerization, it is preliminarily judged that the catalyst has begun to initiate the polymerization of ethylene. ; Spectrogram (c)-(...

Embodiment 3

[0026] Example 3: Figure 4 It is the result of analyzing the circulating gas in the reactor by gas chromatography during the successful start-up of the unit. The catalyst used during start-up and the reaction conditions of only adding ethylene monomer in the reactor are the same as in Example 1.

[0027] Figure 4 Among them, the meanings of spectrograms (a)-(e) are the same as in Example 1.

[0028] according to Figure 4The gas chromatographic analysis results show that: spectrogram (a), when no catalyst is added, no 1-butene and 1-hexene are detected in the recycle gas, indicating that ethylene has not yet undergone polymerization; After 1 hour of catalyst, traces of 1-butene and 1-hexene can be detected from the recycle gas. According to the theory that chromium-based catalysts can simultaneously catalyze ethylene oligomerization and polymerization, it is preliminarily judged that the catalyst has begun to initiate the polymerization of ethylene. ; Spectrogram (c)-(e)...

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Abstract

The present invention relates to an initial stage polymerization reaction condition of a polymer resin, and particularly to a method for judging a polymerization reaction condition at an initial production stage of a polyethylene process. The technical scheme of the present invention is that: with the method for judging the polymerization reaction condition at the initial production stage of the polyethylene process, the polyethylene process adopts a chromium catalyst, a gas chromatography method is adopted to detect light olefin in fluidized bed reactor circulation gas to judge whether the chromium catalyst initiates the polymerization reaction, and the production speed of the light olefin is adopted to judge the intensity degree of the polymerization reaction initiated by the chromium catalyst. With the present invention, the rapid detection and the real time monitoring of the polymerization reaction initiation condition at the initial production stage of the polyethylene process can be achieved, wherein the polymerization reaction is initiated by the chromium catalyst; the reaction process can be accurately predicted, the addition amount of the catalyst can be adjusted timely, the production safety can be ensured, and the polymerization accident caused by excessive initiation can be prevented, or the large waste of nitrogen and ethylene can be prevented, wherein the large waste of the nitrogen and the ethylene is caused by no initiation of the catalyst.

Description

technical field [0001] The invention relates to the initial polymerization reaction status of polymer resins, in particular to a judging method for the initial polymerization reaction status of polyethylene technology start-up. Background technique [0002] At present, the judgment of the initiation status of the polymerization reaction at the initial stage of start-up of the gas-phase fluidized bed polyethylene process is determined according to the changes in the fluidized bed reactor’s operating parameters such as material level, temperature, and pressure. This method is suitable for those who have no reaction induction period and Active release stable Ziegler catalysts and metallocene catalysts are effective for the polyethylene process because these parameters can change significantly in a short period of time, reflecting the status of the catalyst-initiated polymerization in real time. However, chromium-based catalysts have a relatively long induction period for initia...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08F10/02C08F4/69G01N30/02
Inventor 石建东王者民阳永荣
Owner CHINA PETROLEUM & CHEM CORP
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