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Method and device for detecting mist entrainment in multiphase flow equipment

A technology of mist entrainment and detection method, which is applied in the processing of detection response signals and the use of sonic/ultrasonic/infrasonic waves to analyze fluids. , Easy to use, small measurement error

Inactive Publication Date: 2011-12-28
ZHEJIANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0013] 1) The research object is mainly the plate distillation column, and there are few studies on other equipment, such as aeration stirring tank, bubble column, etc.
[0014] 2) The research focus is mainly on the analysis and correlation of the causes of mist entrainment and the main influencing factors, and there are few studies on the detection methods of mist entrainment
[0015] 3) The research system is mainly the gas-liquid mass transfer system, and there are few studies on the phenomenon that solids are entrained together in the gas-liquid-solid three-phase system
[0016] 4) The collection method is often used to measure the amount of mist entrainment, which has large errors and is inconvenient to operate, and cannot be applied to industrial devices
[0017] 5) There are many reports about demisters. The analysis of demister performance is mainly carried out in the laboratory. Due to the limitation of detection methods in industry, it is difficult to obtain direct results of demister effect.
However, wavelet analysis is based on Fourier analysis, so it has the disadvantage of Fourier analysis and can only give a physical interpretation of the linear case
Another problem with wavelet analysis is that it is not adaptive, once the basic wavelet is selected, it must be used to analyze all the data to be analyzed

Method used

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  • Method and device for detecting mist entrainment in multiphase flow equipment
  • Method and device for detecting mist entrainment in multiphase flow equipment

Examples

Experimental program
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Effect test

Embodiment 1

[0106] An industrial test was carried out in a slurry polyethylene production workshop with an annual output of 120,000 tons, and the acoustic emission technology was used to detect the entrainment of mist during the process of increasing the load of the polymerization kettle. Collect the vibration signal or acoustic wave signal when the amount of mist entrainment in the polymerization kettle is known; the collected vibration signal or acoustic wave signal is processed by HHT for multi-scale analysis, and the characteristic parameters are calculated; The parameter is the dependent variable, and the curve fitting method is used to establish a prediction model, that is, a regression model, which is used to monitor the mist entrainment in the polymerization kettle in real time.

[0107] In the polymerization tank, hexane is used as a solvent, and ethylene is passed through to carry out slurry polymerization to produce high-density polyethylene (HDPE). The hexane evaporated from t...

Embodiment 2

[0114] An industrial test was carried out in a slurry polyethylene production workshop with an annual output of 70,000 tons. The acoustic emission technology was used to detect the mist entrainment during the load drop of the polymerization kettle. Collect the vibration signal or acoustic wave signal when the amount of mist entrainment is known in the polymerization kettle; use FFT processing and wavelet decomposition to perform multi-scale analysis on the collected vibration signal or acoustic wave signal, and calculate the characteristic parameters; take the entrainment amount of mist as the independent variable , with the characteristic parameters as the dependent variable, the partial least squares method is used to establish a prediction model, that is, a regression model, which is used to monitor the mist entrainment in the polymerization tank in real time.

[0115] In the polymerization tank, hexane is used as a solvent, and ethylene is passed through to carry out slurry...

Embodiment 3

[0124] A cold mold device was established in the laboratory, and acoustic emission technology was used to detect and control the amount of mist entrainment at the top of the stirred tank.

[0125] The detection and control system of mist entrainment in the stirred tank is attached Figure 14 As shown, the stirring tank 11 is a gas-liquid two-phase or gas-liquid-solid three-phase stirring system. The gas enters the tank through the inlet pipe, and when it flows out from the top of the tank, a small amount of liquid or liquid-solid mixture will be entrained. A mist entrainment collection device 13 is arranged on the top of the kettle to collect and measure the mist entrainment amount, which is used to establish an acoustic emission technology prediction model for the mist entrainment amount. The acoustic signal receiving device 2 is placed at the gas outlet of the tank top, and the received acoustic signal is amplified by the signal amplifier 3, collected by the signal acquisiti...

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Abstract

The invention discloses a method for detecting mist entrainment in multiphase flow equipment, comprising the steps of: 1) receiving vibration signals or sound wave signals in multiphase flow equipment; 2) selecting the total energy and characteristics of the vibration signals or sound wave signals The energy of the frequency band or the energy fraction of the characteristic frequency band is used as the characteristic parameter; 3) Substituting the characteristic parameter into the prediction model between the pre-established characteristic parameter and the mist entrainment amount, and calculating the mist entrainment amount in the multiphase flow equipment. The method adopts a nonlinear method to process the signal, can obtain the characteristic parameters of the signal more accurately and effectively, and obtain the real-time mist entrainment amount; the method has sensitive response, small measurement error and wide application. The invention also discloses a detection device, which includes a signal receiving device, a signal amplifying device, a signal collecting device, a signal processing device, an output display device and a control device. The device is non-intrusive for ease of use and does not interfere with fluid motion or chemical reactions; no emission source is required.

Description

technical field [0001] The invention relates to the field of chemical dynamic monitoring methods and devices, in particular to a dynamic detection method and device for mist entrainment in multiphase flow equipment. Background technique [0002] There are many multiphase flow equipment in the chemical process, such as plate tower, gas-liquid two-phase or gas-liquid-solid three-phase stirred tank, bubbling bed, etc., when gas-liquid mixing is often accompanied by mist entrainment. Fog entrainment refers to the phenomenon that when the gas passes through the liquid layer from bottom to top, the mist generated by the turbulence of the liquid surface is carried away by the air flow and enters the upper device or pipeline. For the three-phase system, there will also be a small amount of solids entrained by the gas along with the mist droplets. [0003] Fog entrainment has a detrimental effect on chemical processes. In the polymerization reaction device, a large amount of mist e...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N29/036G01N29/44
Inventor 王靖岱胡雨晨黄正梁蒋斌波阳永荣
Owner ZHEJIANG UNIV
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