The Coal Tar Reheating Furnace Has Many Different Tube Structures Phase Flow Study On Phase Flow Pattern And Coking Law

Coal tar furnace is a component of floating bed hydrogenation unit.Vertical ushaped furnace tube and horizontal tube racetrack furnace tube are important parts in coal tar heating furnace.Based on computer fluid dynamics(CFD)software,numerical simulation method is used to study the erosion and heat transfer coking in two types of furnace tubes,which is of great significance to the safe operation of coal tar heating furnace.In this paper,FLUENT software was used to carry out numerical simulation of gasliquid-solid multiphase flow field in the furnace tube commonly used in suspended bed hydrogenation process based on Mixture-DPM two-way coupling model.The results show that the u-shaped furnace tube produces obvious erosion at the inlet bend,the middle bend and the outlet,and it weakens in turn.The whole part of the racetrack bend will produce intermittent regional erosion,the most serious part of which occurs in the middle of the bend.The increase of particle mass flow rate,velocity and particle diameter will increase the erosion rate of the pipe wall.Compared with u-shaped furnace tube,the erosion rate of racetrack furnace tube under different conditions is much lower than that of u-shaped furnace tube.When the particle diameter is 200?m,it is the key node affecting the erosion rate of the two furnace tubes.When the particle diameter is 50?m-200?m,the maximum erosion rate increases with the increase of the particle diameter.Above 200 m,the erosion rate begins to decrease.At the same time,on the basis of verifying the correctness of the heat transfer simulation with the industrial data,the heat transfer law of gas-liquid-solid three-phase in the furnace tube is simulated.By simplifying the complete model of the furnace tube,the distribution law of temperature,velocity and gas-liquid two-phase in two kinds of furnace tubes was studied based on the idea of partition calculation,and the possible positions of coking were analyzed.The results show that the heat transfer efficiency of racetrack type furnace tube is higher,and the outlet temperature of racetrack type furnace tube is 1.52% higher than that of U type furnace tube.The coking of racetrack type furnace tube is easy to occur in the upper part of the furnace tube and the second pipe;U-pipe coking is more likely to occur on the inside of the bend near the ground.