| ALR is a kind of mixing reactor with good mass and heat transfer performance and can achieve good mixing effect without mechanical agitation.ALR has been widely used in the field of biochemistry,environment.There are good application prospects about ALR due to large flow velocity,good effect of backmixing and advantages of solid particles not easy to deposit in suspension bed hydrocracking technology.However,because of the complexity of flow field in ALR,the reactor industry amplification still has a lot of uncertainty.In this paper,by means of computational fluid dynamics(CFD),using two-fluid model to establish CFD model which can describe the complex flow to provide theoretical basis for industrial reactor amplification.Firstly,using ALR of 50,0000 tons/year heavy oil processing as the research object,examines the flows change with liquid level height and research system and then taking 24 ton/year,10,0000 tons/year,50,0000tons/year and 1 million tons/year heavy oil processing as the benchmark,examine the amplification rule that the gas holdup and liquid circulation velocity changes with the ratio between liquid level height and diversion tube length and research system.Secondly,examine the flow changes with diversion tube diameter,length and position,the taper at the bottom of the reactor,the diameter,the position and the structure of nozzle for 500000 tons/year heavy oil processing.Finally,taking 24 ton/year,10,0000 tons/year,50,0000 tons/year and 1 million tons/year heavy oil processing as the benchmark,examine the diameter ratio between the diversion tube and outer tube,the length ratio between the diversion tube and the outer tube,the ratio between the distance from the bottom and the diversion tube diameter,the taper at the bottom of the reactor,the diameter ratio between the nozzle diameter and the diversion tube diameter,the location,the angle and the nozzle layer effect on the flow in the amplification process.Results of the flows change with the liquid level height and the research system and the amplification rule that the gas holdup and liquid circulation velocity change with the ratio between liquid level height and diversion tube length and research system show that liquid level has little impact on gas holdup,liquid circulation velocity in the dropper becomes slightly larger with the increasing of liquid level height.Relative to air-water system,hydrogen-kerosene system has higher gas holdup and smaller liquid circulation velocity.As the ratio between liquid level height and diversion tube length increases,the overall gas becomes less and liquid circulation velocity increases,but the change is small.As the reactor volume amplifies,relative to air-water system,hydrogen-kerosene system has greater gas holdup and smaller liquid circulation velocity.Results of the flow changes with diversion tube diameter,diversion tube length and diversion tube position,the taper at the bottom of the reactor,the diameter of nozzle,the nozzle position and nozzle structure show that the gas holdup and liquid circulation velocity in the riser,dropper and overall zone increase with the increasing of diversion tube diameter within a certain scope;the circulation effect falls when diversion tube diameter is too big.The overall gas holdup and liquid circulation velocity will increase with the diversion tube length increases in a certain range.The flow improves little when the diversion tube length surpasses 11~12m.With the improvement of the diversion tube location,the gas holdup and liquid circulation velocity increase after first trend of decrease,the flow achieve the best when diversion tube location is 0.82 m.With the increase of taper at the bottom of the reactor,the gas holdup increases and liquid circulation velocity reduces slightly.With the increase of nozzle diameter,the gas holdup in the riser and dropper increases,however,the liquid circulation velocity in the two zones decreases,the variation amplitude of liquid circulation velocity is bigger.The gas holdup is greater when the nozzle is placed high than flat and low location.The gas holdup is similar when the nozzle location is horizontal and low.The order of liquid circulation velocity under three types of nozzle position is as follows: low,flat and high.The larger nozzle angle can improve the radial distribution of gas holdup and liquid circulation within a certain range,the circulation effect will decrease when nozzle angle is overlarge.The radial distribution of gas holdup and liquid circulation is more uniform with the increase of nozzle layer.Results of the flow changes with the diameter ratio between the diversion tube and outer tube,the length ratio between the diversion tube and the outer tube,the ratio between the distance from the diversion tube bottom to the outer tube bottom and the diversion tube diameter,the taper at the bottom of the reactor,the diameter ratio between the nozzle diameter and the diversion tube diameter,the nozzle location,the angle of the nozzle and the nozzle layer effect on the flow in the amplification process show that geometric structure have little impact on flow characteristics under the small reactor size.As the reactor volume amplifies,the diameter ratio between diversion tube and outer tube is reduced,the ratio between the distance of the diversion tube bottom apart from the bottom of reactor and diversion tube diameter increased and the length ratio between diversion tube and outer tube increased under the optimal flow;the diameter ratio between the diversion tube and outer tube decrease from 0.75 to 0.70,the ratio between the distance of the diversion tube bottom apart from the bottom of reactor and diversion tube diameter increased from 0.27~0.42 to 0.42 ~ 0.45 and the length ratio between the diversion tube and the outer tube increased from 0.37 to 0.45.The nozzle position under the optimal flow sets from high to low in the amplification process.The flow is better for smaller diameter ratio between nozzle and diversion tube,45~60 degree of nozzle angel and three-layer nozzle structure in the amplification process. |
PDF Full Text Request