| Although current crude distillation has been very mature,there are still some problems.The steam stripping of atmospheric tower bottom and lateral line can pull out of the light component that is not drawn,but will increase the cooling load of the overhead condensing system,causing serious low-temperature dew point corrosion.It is not conducive to long-period atmospheric and vacuum distillation unit operation,and will increase the amount of oil-polluted water treatment and emissions,causing a great waste of resources and energy.So it is very important to improve and optimize the crude distillation process.In order to solve the above problems,on the basis of conventional atmospheric and vacuum distillation,this paper puts forward two kinds of dew point corrosion transfer processes of atmospheric tower with water and without water.This paper use PRO/II software to simulate and calculate the three kinds of processes of Russian crude oil 5 million tons / year to explore the influence of two new processes on crude distillation process,especially the influence on the dew point corrosion at the top of atmospheric tower and energy saving effects and studied the influence of operating conditions on the two processes.In addition,this paper also used non equilibrium stage algorithm to evaluate the effect of different reflux temperature difference,optimized the heat extraction ratio of middle circulation from the perspective of the economic benefits of the whole tower and added a flash tower to optimize the crude distillation process.The results show that: compared with conventional atmospheric and vacuum distillation,the largest vapor phase loads were reduced by about 1/3 in dew point corrosion transfer process II and process III of the atmospheric tower.The oil refining sewage volumes were reduced by 70% and by 37% and the overall energy consumptions were reduced by 12.5% and by 13.1%.To supplement the water steam stripping effect,the outlet temperature of the atmospheric furnace is increased to 370?.The upper plate temperature of the two new processes' atmospheric tower is higer than conventional one,and the overhead condenser water vapor dew point temperature is 25.4?,which is far below the temperature of the condenser.67wt% of HCl gas will be transferred to the dry gas,and will be removed in the subsequent alkali washing tan.Therefore,HCl gas is difficult to dissolve in water to form hydrochloric acid solution.So two new energy saving processes at the same time can alleviate the problem of low temperature dew point corrosion of atmospheric tower.Non-equilibrium model can handle the cold reflux such as non-vapor-liquid equilibrium phenomena.Its simulation of middle reflux operation is much closer to the actual situation.Considering the effect of liquid back flow,product yield,entrainment,tray efficiency and the product quality,the reflux temperature difference in the range of 60~80? is reasonable.The optimal proportion of middle heat removal was affected by the market price of the product.Taking into account the overall economic benefits of the whole atmospheric tower,the optimal proportion of heat removal in the middle circulation are different during different periods.Two stage flash can pull out more water and light components in the oil to solve the oil vaporization in heat exchangers,recover more low temperature heat from heat network and reduce the load of furnace and water feed flow into atmospheric tower,which is conducive to the dew point corrosion transfer process. |
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