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Coke oven gas is an important source of crude benzene; if crude benzene cannot be recovered effectively, it leads to waste of this substance and affects the company’s financial earnings. An analysis of the current situation in the crude benzene production process shows that there is still significant room for improving the yield of crude benzene. Therefore, we conduct in-depth analysis and research on the quality control methods and recovery processes for crude benzene, in order to strengthen the management of crude benzene recovery, improve its production efficiency, and maximize the economic benefits of the enterprise. As a very complex compound, crude benzene, which is a product of coking gas, consists mainly of aromatic hydrocarbons such as benzene, toluene, and xylene – all of which are important raw materials in the chemical industry. In recent years, the gradual increase in the price of crude benzene has made coking enterprises realize the importance of crude benzene recovery for them. To improve its economic efficiency, it also increased its research efforts on the crude benzene process, **which led to an increase in the yield of crude benzene. This article takes the quality control measures for crude benzene as the starting point and provides a detailed explanation of the methods to improve the level of crude benzene recovery technology. 1. Quality control measures for crude benzene: To achieve effective control of the quality of crude benzene, special attention should be paid to the following aspects: when the temperature at the top of the benzene removal tower is too high ； When the benzene removal tower is put into operation ； When the benzene removal tower is shut down ； The specific details are as follows: 1.1 When the temperature at the top of the benzene removal tower is too high, generally speaking, when this temperature exceeds 105°C, effective control measures should be taken to ensure the quality of benzene. First, the lean oil flow rate of the oil-oil heat exchanger should be adjusted to keep the rich oil temperature within the range of 110°C to 150°C. Secondly, maintain the temperature of the rich oil at the outlet of the tubular furnace between 170°C and 185°C. Once again, the superheated steam temperature at the outlet of the tubular furnace is controlled between 350°C and 400°C. Finally, the reflux rate of crude benzene is adjusted to keep the top temperature below 105°C. 1.2 When starting up the benzene removal tower, it is necessary to check in advance that the equipment, valves, and pipelines are in good condition. After filling the oil-water separator with water, it is necessary to open the valves of the vent pipe, distillation equipment, oil-rich pump, and regenerator to allow steam to flow through for cleaning, in order to check the operating condition of the equipment. After the cleaning is complete, close all steam valves and start the lean and rich oil pumps to supply oil, which then passes through the first and second lean oil coolers before entering the benzene washing tower. When the liquid level at the bottom of the tower reaches half, the cold circulation system of the rich and lean oil pumps should be activated promptly. Once the cold circulation is operating properly, the tubular heater is ignited for heating; an appropriate amount of oil is added to the regenerator, and the steam valve is kept open. In addition, the staff should also check whether the pressure at the bottom of the benzene removal tower meets the relevant technical requirements. When the temperature of benzene at the outlet of the condensate cooler is 30 degrees Celsius, the cooling water should be turned on. If overflow occurs in the reflux tank, the reflux pump should be started to control the flow rate and ensure that the temperature at the top of the tower remains below 105°C. 1.3 When the debenzene tower is shut down, check the patency of the drain pipes for each piece of equipment; no more fuel should be added to the regenerator. Once the temperature specified for slag discharge is reached, the residues remaining from the regeneration process must be removed, and all pipes should be cleaned. Stop the operation of the regenerator direct steam and benzene reflux pumps, and cease heating the tubular furnace. When the temperature in the furnace chamber falls below 100°C, shut down the rich and lean oil pumps to reduce the amount of cooling water in the condenser. Once all the benzene has flowed out, the water supply can be stopped. In the event of a long-term shutdown, the liquid stored in the pipes and equipment must be completely drained, and the systems should be cleaned using steam. 2. Methods to improve the technical level of crude benzene recovery address the factors that influence this process, such as the temperature of the oil-poor stream, temperature control in coke ovens, and the quality of the washing oil. However, through years of practice and refinement, the relevant technologies have already been optimized. At the current stage, the methods to improve the level of crude benzene recovery mainly involve the following aspects: controlling the levels of hydrogen sulfide and ammonia in coke oven gas ； Replace the material of the oil-gas heat exchanger behind the debenzolization unit ； Resume using the oil washing tank in the tank area ； Calibrate important instruments ； Modify the reflux process at the top of the benzene removal tower ； The specific details are as follows: 2.1 Control the levels of hydrogen sulfide and ammonia in coke oven gas. Since both ammonia and hydrogen in the gas are highly corrosive, it is very important to effectively remove sulfides and ammonia from the gas. The corrosion of equipment by ammonia occurs mainly through the action of electric current, which reacts with the metal materials in the equipment to form corrosive substances, thereby damaging the equipment. Hydrogen sulfide primarily undergoes redox reactions with iron ions at low temperatures, and electrochemical corrosion occurs in the presence of water. Especially in the presence of O2 in the medium, it accelerates the corrosion rate, sometimes increasing it by more than ten times. Furthermore, ammonia and sulfur can cause stress corrosion in the equipment, with more severe corrosive effects. 2.2 Replace the material of the oil-gas heat exchanger located behind the debenzing unit. Currently, the debenzing tower, its components, as well as the coil in the tubular furnace are all made of stainless steel. However, the oil-gas heat exchangers situated behind the debenzing tower are often made of ordinary seamless steel pipes, and heat exchangers made from this material are highly susceptible to corrosion, and may even leak. Therefore, the material of the oil-gas heat exchanger should be replaced with stainless steel. 2.3 During the startup of the crude benzene system using the washing tank in the tank area, since this area was not yet in use, the storage tank had to be used as a washing tank. Once the tank area is fully completed, the oil washing tanks become unnecessary; therefore, there is only one tank of each type – either for oil washing or for crude benzene. During maintenance work, production has to be halted, which reduces the efficiency of crude benzene production. After cleaning through the oil washing tank in the trough area and putting it into use, normal operation of crude benzene production can be restored. 2.4 Adjusting the flow rate of the lean oil in critical instruments has a direct impact on the efficiency of the benzene washing tower. If the flow rate is too low, it is not possible to effectively absorb crude benzene from the gas; on the other hand, if the flow rate is too high, it increases the load on the tubular furnace and the benzene removal tower, as well as raising the power consumption of the lean and rich oil pumps, thereby increasing the burden on the coking plant. Therefore, the important instruments are calibrated to allow for flexible adjustment of the system parameters. 2.5 Modification of the reflux process at the top of the benzene removal tower: The traditional reflux process at the top of the benzene removal tower involves automatic adjustment of the control valve via the pump outlet. Since the amount of reflux is primarily regulated based on the temperature at the top of the tower, it can happen that the amount of reflux is extremely low, or even the control valve remains in a slightly open or closed state; this leads to pressure buildup and potential damage to the pump when crude benzene is refluxed. Now, place the control valve at the inlet of the crude benzene reflux pump, replace it with a regular gate valve, and keep it in the open position. When the flow rate decreases, most of the crude benzene returns to the pump inlet, with only a small amount returning to the benzene removal tower ； When the flow demand increases, the automatic control valve is adjusted to the closed position, allowing all of the crude benzene to be sent to the benzene removal tower. This meets the operational requirements of the benzene removal tower and ensures the safe operation of the crude benzene reflux pump. 3. Conclusion In summary, when carrying out benzene recovery operations, it is necessary to strictly control the absorption temperature, the top temperature of the tower, and the quality of the circulating washing oil. Only in this way can the quality of crude benzene recovery be ensured and its production efficiency improved. Only by scientifically establishing process control parameters can the efficiency of coking enterprises be further improved.