Experimental Study On The Structure Optimization Of Pre-stripping Section Of SVQS

In this paper,an experiment was carried out on the SVQS cold model experiment that was coupled with a gas-solid phase flow pre-stripping section and a stripping section.The flow parameters of pre-stripping section with two different structures were compared and analyzed.The pre-stripping section ? have a gas distribution plate under the draft tube area and a gas distribution tube under the annulus area.The influence of the introduction of vapor-stripping gas on the gas-solid flow characteristics of the two structures is discussed,such as circulation velocity,particle concentration,stripping efficiency and gas flow rate.In order to develop a simple,efficient and suitable circulation stripping section for industrial application in FCC riser SVQS system.PV-6D optical fiber system was used to compare the influence of the introduction of vapor-lift gas on the particle concentration distribution of the two structures.The results show that the particle concentration in the lower part of the draft tube area of the pre-stripping section ? and ? is uniformly distributed along the radial direction,and the concentration of the particles in the middle and upper part of the draft tube is in the form of a ring-nucleate distribution.The average particle concentration of the draft tube and the annulus area of the pre-stripping section ? decreases with the increase of axial direction when only has annulus gas and two gases are present.The particle concentration in the draft tube and annular area of the pre-stripping section ? and ? decreases with the increase of the gas velocity of the draft tube or the stripping gas velocity.When there is one of stripping gas and draft tube gas and the gas velocity is low,the particle concentration of pre-stripping section ? is greater than that of section ?.When the gas velocity is higher,there's not much difference between section ? and section ?.In this paper,the influence of stripping gas on the stripping efficiency,particle circulation velocity and the gas flow of the two structures were investigated by using the gas tracer technique.At the same time,this paper presents a new method to study the stripping efficiency using gas tracer technology.The results show that the stripping efficiency of the pre-stripping section ? and ? increases with the increase of the gas velocity of the draft tube.In the same operating condition,the stripping efficiency of the pre-stripping section ? is higher than that of the pre-stripping section ?,and the stripping efficiency of the pre-stripping section ? is higher than the stripping efficiency of the stripping section(free bed).The circulation velocity and the flow rate of the pre-stripping section ? are greater than that of the pre-stripping section ?.The gas volume fraction X_d and the amount of gas Q_sX_d in the draft tube in the pre-stripping section ? are higher than that in the pre-stripping section ?,and the X_a and Q_sX_a of the pre-stripping section ? are lower than the pre-stripping section ?.