Numerical Simulation On Spray Drying Of Oilfield Auxiliary Chemical

With the increase of oil demand year by year,some oil fields in China haveentered the middle and late stage of development,and the exploration and development of deep traditional oil and gas resources,such as shale gas,tight gas and tight oil,has become one of the important replacement resources for the increase and production of oil fields.Drilling fluid oilfield additives can effectively prevent the occurrence of accidents such as well wall spalling,collapse and malignant leakage,and are important links to ensure the safety of deep drilling.Therefore,the production of drilling fluid oilfield additives is of great practical significance.Spray drying is an important technological link in the production of oil field auxilaries.It is characterized by simple equipment,rapid drying,simple operation,convenient control and suitable for large-scale production.In this paper,CFD software Fluent was used to conduct relevant research on the gas-solid two-phase flow drying process in the spray drying tower,and detailed analysis was made on the temperature,humidity,section evaporation rate and other laws in the tower.The results show that the temperature in the tower is basically symmetrical and radially distributed,and there are two low-temperature zones in the center and wall of the spray drying tower.In the axial direction,the temperature gradually decreases from top to bottom,the relative humidity gradually increases,and the evaporation rate of the material liquid on the cross section first increases and then decreases.The maximum evaporation rate is 1.135905·E-5kg /s at the section 4m away from the nozzle.After that,the section evaporation rate decreases with the increase of the height of the tower,and the decreasing range is more and more moderate.The evaporation rate at the outlet is only4.696·E-7kg/s.Compared with the traditional dry media-hot air,the superheated steam not only has a larger specific heat capacity(1.09 kj/kg/K),and the exhaust gas is only steam.The latent heat of steam can be recovered and utilized by compression and condensation.Therefore,the dry medium is replaced by superheated steam for simulation.The comparison of the two drying media shows that the temperature of superheated steam is always higher than that of air at the same position in the tower.The temperature difference is the largest at the axial position,but the temperature difference between the two media decreases with the increase of inlet temperature.In addition,although the evaporation rate of air on the same section at 413 K and433K is higher than that of superheated steam,the difference between the maximumevaporation rate on the section decreases from 3.637·E-6kg /s to 0.786·E-6kg /s.The maximum evaporation rate of superheated steam cross section exceeds that of hot air at 453 K and 473 K,with the difference rising from 1.4989·E-6kg/s to 2.46391·E-6kg /s.It can be seen that by increasing the same temperature,the drying rate of superheated steam increases faster,thus deducing the existence of inversion temperature.When the water content of the material is 73% and the initial temperature of the material is 300 K,the average drying rate in the tower is calculated by using hot air and superheated steam respectively,and the Inversion temperature is 451.83 K.When the water content of the material is 68% and 78%,the corresponding Inversion temperature are 461.83 K and 444.78 K,respectively.When the initial temperature of the material is 280 K and 320 K respectively,the corresponding Inversion temperature is 443.95 K and 462.60 K respectively.In other words,both the initial water content and the initial temperature of the material affect the inversion temperature,which decreases with the increase of the initial water content of the material and increases with the increase of the initial temperature of the material.