Method for measuring fluidization parameter of gas-solid fluidized bed

A fluidized bed and parameter technology, applied in fluid velocity measurement, measurement device, velocity/acceleration/impact measurement, etc., to achieve the effect of high detection accuracy and simple detection device

Inactive Publication Date: 2012-02-01
ZHEJIANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, there is no report on the use of inductive electrostatic sensors to detect fluidization parameters such as particle concentration, particle size, cycle time, fluidization state, and flakes / blocks in a fluidized bed and their distribution.

Method used

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  • Method for measuring fluidization parameter of gas-solid fluidized bed
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  • Method for measuring fluidization parameter of gas-solid fluidized bed

Examples

Experimental program
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Embodiment 1

[0046] Example 1 Detection of particle cycle time

[0047] The method and device described in the present invention are used to measure the circulation time of particles in a gas-solid fluidized bed. The fluidized bed used in the experiment was Φ 150 mm plexiglass bed; the distribution plate adopts a porous iron plate with a hole diameter of 2mm, and the opening rate is 2.6%, and the distribution plate is kept well grounded during the experiment; the fluidized medium is dry nitrogen; the material is linear low-density polyethylene particles , whose melt index and density are 2.0 g·10min, respectively -1 and 920 kg·m -3 , the relative dielectric constant is 2.3, and the average particle size is 0.393 mm. Inductive electrostatic sensors such as figure 1 As shown, it protrudes 5mm from the side wall into the fluidized bed reactor. 8 different heights (30mm, 105mm, 185mm, 265mm, 345mm, 425mm, 505mm, 585mm) and 6 superficial air velocities (0.12m / s, 0.24m / s, 0.30m / s, 0.36m / ...

Embodiment 2

[0053] Example 2 Detection of flakes / blocks

[0054] The experimental device and experimental method are the same as in Example 1. The superficial gas velocity is 0.30 m / s -1 . The volume is 21.9, 40.5, 90, 178.5 cm 3 The 4 knots were placed into the fluidized bed from above the fluidized bed, and the electrostatic signals were collected at three heights of 30mm, 265mm, and 425mm, respectively, with a sampling frequency of 10000Hz and a sampling time of 100s. The electrostatic signal is processed by hardware filtering and software filtering to remove high-frequency noise above 200Hz.

[0055] Method 1: Detect patches / blocks based on the shift of the fundamental modal frequency. The HHT transformation is performed on the electrostatic signal, and the frequency of the fundamental mode is taken as the characteristic parameter. Taking the electrostatic signal measured at a height of 30mm as an example for analysis, the experimental results are as follows Figure 4 As shown, ...

Embodiment 3

[0060] Example 3 Detection of Particle Concentration

[0061] The experimental device and experimental method are the same as in Example 1. The electrostatic signal is processed by hardware filtering and software filtering to remove high-frequency noise above 30Hz. By adjusting the superficial gas velocity, the porosity in the fluidized bed is changed, and then the particle concentration is changed, and the particle concentration is calibrated with a laser concentration detector. At a height of 30mm, collect the electrostatic signals at 6 superficial gas velocities (0.12m / s, 0.24m / s, 0.30m / s, 0.36m / s, 0.42m / s, 0.48m / s). The frequency is 1Hz, and the sampling time is 600s. As the superficial gas velocity increases, the particle concentration decreases. The average value of the electrostatic signal, the amplitude of the fundamental frequency of the electrostatic signal, and the energy of the fundamental mode of the electrostatic signal after HHT transformation are taken as pa...

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Abstract

The invention discloses a method for measuring the fluidization parameter of a gas-solid fluidized bed. The method comprises the following steps of: 1) measuring an electrostatic signal in the gas-solid fluidized bed by use of an inductive electrostatic sensor, wherein the inductive electrostatic sensor is connected with a monitoring system; 2) analyzing the filtered electrostatic signal, and extracting the characteristic parameter; 3) associating the characteristic parameter of the electrostatic signal with the parameters such as particle concentration, speed, circulation time, particle clustering or flaking, fluidized state and the like, and establishing prediction models of the parameters respectively; and 4) detecting the parameters such as particle concentration, speed, circulation time, flaking/blocking and the like as well as the distribution and fluidized state thereof in the fluidized bed by use of the established prediction models. The method adopts a simple detection device, is safe and environmentally-friendly, has high accuracy, and is suitable for the online detection of the industrial production process.

Description

technical field [0001] The invention belongs to the technical field of gas-solid two-phase flow measurement, and in particular relates to a method for measuring fluidization parameters of a gas-solid fluidized bed. Background technique [0002] The key to the operation of the gas-solid fluidized bed reactor is to obtain a good fluidized state and maintain good mixing so that the heat can be removed in time. Taking the gas-phase polyethylene fluidized bed reactor as an example, frequent sheeting will destroy the fluidized state, gas circulation and product discharge from the reactor, and in severe cases will cause the reactor to shut down. In the gas-solid fluidized bed, the particles, gas, and the walls of the gas-solid fluidized bed are charged by themselves or between them. US4803251 and US5391657 point out that the catalyst and resin particles adhere to the reactor wall under the action of electrostatic force, which is the main reason for the formation of flakes. The su...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N15/06G01N27/60G01P5/08
Inventor 王靖岱黄正梁许南董克增蒋斌波阳永荣朱子川何乐路张擎蒋云涛
Owner ZHEJIANG UNIV
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