Design And Experimental Research Of New Feed Nozzle For Residue Fluidized Catalytic Cracking

Catalytic cracking feed nozzle is the core equipment of Residue Fluidized Catalytic Cracking(RFCC)device.Its spray quality directly affects the production efficiency of the plant.Currently,there are many problems in domestic refinery RFCC feed injector,such as poor atomization quality,small coverage area of oil mist in riser,high steam consumption and small operation flexibility.According to the demands of riser feed parameters obtained from the earlier research based on the optimization of the cross flow structure group and the relevant worldwide research results,a new type of high efficiency RFCC feed nozzle was developed and designed by three kinds of atomization,such as bubble atomization,swirling atomization and increasing gas and liquid velocity difference atomization.The research of the subject has important practical value on engineering.Gas consumption,spray angle,droplet size was considered as the evaluation indexes and the cold experimental equipment was built using DP-02 laser particle test system and flash photography system device to analyse the influence of operating parameters and structure parameters on the outside flow field characteristics of the nozzle.The results show when the ratio of gas to liquid is 0.012~0.023 and the ratio of gas to liquid is 1~1.2,the atomization quality becomes better.With the decrease of nozzle diameter,inner hole diameter and air hole diameter,the consumption of atomized steam is significantly reduced and the mixing effect of oil additives in the riser is significantly improved.Limited to the engineering actual,the diameter of the nozzle hole should not be less than 10 mm and the inner hole diameter of the nozzle should not be less than 25 mm and the air hole diameter should not be less than 4mm.When the angle of the nozzle hole is 45 degrees,the distribution of oil is more uniform.When the mixing chamber's length diameter ratio is about 0.318 and the inner nozzle's shrinkage angle is about 31.4 degree,the atomizing droplet diameter of the nozzle is smaller and the atomization quality is better.The addition of guide vane swirler in the nozzle can reduce the consumption of atomizing steam and increase the swirling intensity of the fluid and reduce the average diameter of the atomized droplet(Sauter mean diameter,SMD)and improve the atomizing effect of the nozzle.Through theoretical analysis,the theoretical calculation formula of the outlet flow coefficient of nozzle was derived.Based on the measured data,the relationship between liquid flow and GLR,the relationship between total head loss and GLR,the relationship between outlet flow coefficient and GLR were obtained by fitting the experimental data.Finally,the design process of the new RFCC feed nozzle was summarized,and the nozzle structure design calculation is carried out under the actual working conditions.At the same time,the calculation software of nozzle structure is compiled based on VB language,which realizes the visualization and routinization.