Method for measuring concentration of non-spherical particles of spouted bed

Abstract

The invention relates to a method for measuring the concentration of non-spherical particles of a spouted bed. The method comprises the following steps of: respectively acquiring the particle concentration of a sparse high-speed region and the particle concentration of a dense low-speed region of the spouted bed through combined application of dynamic image analysis and static bed sampling, wherein during dynamic image analysis, a high-definition digital image is acquired through a high-speed digital CCD (Charge Coupled Device), the image is analyzed frame by frame to position the non-spherical particles to further obtain the particle concentration of a target region, and during static bed sampling, a plugboard box is rapidly inserted into a bed body of the spouted bed from the top to extract the whole bed layer and radially partition the whole bed layer, a comb-shaped board is axially and elastically partitioned to obtain a mixture sample containing the non-spherical particles, and a sample is screened and analyzed to obtain the particle concentration of the target region. On the basis of the traditional bed collapse method, the method disclosed by the invention improves the plugboard / partition board sampling method, organically combines dynamic image processing with the static bed sampling aiming at the bed-type characteristic that the spouted bed is heterogenic in multiple regions of the same spouted bed and realizes partitioned measurement of the particle concentration of the high-speed sparse region and the particle concentration of the low-speed dense region of the spouted bed.

Description

technical field [0001] The invention relates to a method for measuring the concentration of non-spherical particles in a spouted bed, belonging to the technical fields of gas-solid fluidized bed technology and multiphase flow measurement. Background technique [0002] The spouted bed is a fluidized bed under special conditions, which can handle coarse and narrow sieving particles. The gas flow is injected vertically upwards through a small hole or nozzle to form a jet area that gradually extends upwards. When the jet velocity is high enough, the jet penetrates the bed to form a dilute-phase gas-solid flow that moves upward through the center of the bed. bolt. When these particles rise to a certain height, the particles will fall back to the surface of the annulus region due to gravity like a fountain. These fall-back particles move slowly downward until they are re-entrained by the jet and participate in a new cycle. Therefore, the flow pattern of the spouted bed presents...

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Problems solved by technology

Among these methods, the salt tracer particle method was earlier and widely used in fluidized beds. It analyzed the concentration of tracer particles by measuring the conductivity of a solution in which a certain amount of particles were dissolved in water. Therefore, The advantage of this method is that the measurement is direct, rapid and low cost, but there are disadvantages such as the accumulation of tracer particles in the bed and the disturbance of the flow field in the bed when the particles are injected.

The thermal particle tracer method is also a commonly used method for measuring mixing behavior. This method will not pollute the particles in the bed and is relatively easy to detect, but the biggest disadvantage is that the temperature of the thermal tracer particles decays quickly under the action of cold air flow. , this part of the heat loss needs to be considered in the analysis and calculation, and it is also a very difficult problem in the experimental technique to measure the particle temperature accurately

The phosphorescence particle tracking method overcomes the disturbance of the flow field when the tracer particles are injected, and realizes online detection with very high sensitivity. It is an ideal measurement method for studying the axial and radial mixing behavior in the bed, but this method also has phosphorescence The particle afterglow intensity will gradually decay over time and cannot be detected by the detector, and for denser fluidized bed tracer particles are often easily blocked by other bed materials and affect the accuracy of the experiment

The above-mentioned methods all have a common shortcoming. They can only realize fixed-point detection, but cannot realize full-field detection, and there are limitations in obtaining particle concentration in dense areas.

At the same time, these methods are applicable to fluidized beds, but there are no implementation cases in spouted beds

[0005] With the increasing application of spouted beds in engineering applications, some complex gas-solid two-phase flows, especially the multi-component mixing process of spherical particles / non-spherical particles, are also emerging. The existing understanding of spherical particles is applied to These complex processes still have certain limitations, and it is urgent to conduct in-depth research on the measurement methods of non-spherical particles in spouted beds

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