Research On The Influence Of Sulfur Transfer Aids On Heavy Oil Catalytic Cracking Unit

In the production process of the catalytic cracking unit of the refining and chemical enterprise,due to the increasing sulfur content in the processed raw materials,the pollutants such as sulfur dioxide in the flue gas generated by the scorching are also getting higher and higher.Recently,our country has stricter requirements on flue gas emission indicators for refining and chemical enterprises.In order to meet the national environmental protection requirements,Jilin Petrochemical Company II catalytic cracking unit has taken many measures to reduce SO₂ content in flue gas.Sulfur transfer aid is a kind of solid adsorption desulfurization aid which is similar to the catalytic cracking catalyst in the fluidization performance.It has a better effect on reducing the SO₂ content in the flue gas.This paper introduces the development of refining technology firstly.The northeast of the industrial zone is facing environmental problems with poor air quality.It is extremely urgent to reduce pollutant emissions in flue gas.In order to ensure environmental protection standards and achieve energy saving and consumption reduction,it becomes the primary target of equipment research.During the production and operation process,the device encountered many production bottleneck problems,but through the overhaul and process dynamics,the process flow and equipment facilities were continuously improved,and great progress was made in reducing the energy consumption,safety and environmental protection of the device.In this paper,the application effect of SFTS-1 type sulfur transfer aid developed by Qingdao University of Petroleum in Jilin Petrochemical Company II catalytic cracking unit was studied in detail.By comparing and analyzing the data before,during and after the addition of sulfur transfer aids,the results show that the additive can effectively reduce the emission of sulfur dioxide in the flue gas.Moreover,the removal rate of sulfide in the flue gas increases with the increase of sulfur transfer agent amount.When the addition amount is 3%of the storage amount,the desulfurization effect is optimal,reaching 58.5%.The concentration of sulfur dioxide in the flue gas is closely related to the sulfur content in the raw material.The higher the sulfur content in the raw material,the higher the sulfur dioxide concentration in the flue gas,but the concentration is not linear with the sulfur content of the raw material.Analysis results of the sulfur content in the product show that,the sulfur content in the diesel and dry gas increased significantly after the use of sulfur transfer aid,indicating that the sulfur transfer aid will transfer the sulfur in the coke produce by catalytic cracking reaction to dry gas and diesel,and the sulfur elements can be recycled at downstream units.The experimental results show that the application of the sulfur transfer agent within the effective range has no adverse effect on the product yield and product quality of the heavy oil catalytic cracking unit.During the use of the sulfur transfer aid,fouling occurred in the four-unit hood of the unit.The cause of fouling of the hood is the increase of iron ion content in the raw material,and the metal ions are enriched in the surface and pores of the catalyst,which accelerates the electrostatic adsorption of the catalyst fine powder and easily causes fouling of the hood.The sulfur transfer aid contains rare earth elements,iron,vanadium,calcium and phosphorus.The results show that rare earth promotes the formation of sulfides.When iron,calcium and phosphorus are used at a high temperature of 500?to 600?,it is easy to form low-melting calcium sulfate and other compounds under the action of sulfides,resulting in fouling of the machine.In order to solve the scaling problem of the hood,the replacement amount of the fresh agent in the system is increased,the catalyst unit consumption is increased,and the heavy metal content in the regenerated catalyst is reduced.