Design And Experimental Research On Two Stage Purification Device Of Straw Carbonization Flue Gas

Carbonization is one of the effective measures for the utilization of straw resource,but the tar and dust produced by carbonization are mixed in the flue gas.It will affect the extraction and utilization of combustible gas in the flue gas if it is not separated and purified,and the tar is easy to stick to the inner wall of the device,corrode the purifying device,block the channel,and the device may not work normally;the environment may be heavily polluted if the flue gas is discharged directly into air.Atwo-stage purification device wasdesigned to increasethe purification rate of the straw charring flue gas based on analysis of the present research status of flue gas purification technology.The main contents and conclusions are as follows:1)A two-stage purification device which combines functions of cyclone and finger roller was designed.The device separates larger particles with cyclone and smaller particles with collision,gathering and centriful force of finger roller.The traditional filter was replaced by the second-stage purification device,the finger roller,which avoid blockage of the equipment and flue gas of straw carbonization will be efficiently purified.2)The function between the total purification rate and the structure parameters of the first-stage purification device was established to improve purification rate of straw charring flue gas,and the parameters were optimized with the Robust simplified surface climbing method and universal global optimization method;the structure parameter of the second stage of purification device was determined based on parameters restrains of the first stage device and design and installation requirements of second stage of the purification device.3)The effect of the two-stage purification device on pressure loss and purification rate was analyzed from the points of structure parameters,operation conditions,sealment of the two-stage purification device and composition of flue gas.The flow of single particle in the First stage of purification device was studied through dynamic analysis,and the conditions for separating were obtained.The separating principle of the particle from flue gas by collision and intercepting separation between particles and fingers was studied and the speed range of the finger is determined.And the detatching conditions for gathered impurities from the finger are further analyzed.4)Purification performance of cyclone and the two-stage purification device was compared and analyzed through numerical simulation,and the results showed that the addition of finger roller in the exhaust tube of cyclone separator can obviously increase the purification rate of small particles.The effect of rotary speed of the finger rolleron velocity distribution in the two-stage purifier on pressure loss and t purification were studied and revealed,which may provide reference for the optimization and development of two-stageflue gas purification device.5)Performance testing experiment of the two-stage purification device was carried out with factors of roller speed,inlet speed of flue gas and depth of roller,and indicators of total purification rate and pressure loss.The optimum range of factors was determined by single factor test.And the regression models between pressure loss and total purification rate and factors were established according to combination test.Interaction effect of factors on total purification rate and pressure loss was analyzed with response surface method.The parameters of two-stage purification device were determined with the Design-Expert optimization moduleas speed of the roller of 3030r/min,the inlet speed of19.5m/s,the insertion depth of the roller of 210 mm,when the pressure loss was1971.73 Pa and the total gas purification rate was 84.2%.It can meet the design requirement of straw carbonization flue gas purification.