Effect of raw material preheating temperature of catalytic cracking unit on reaction operation

The thing mentioned above should refer to catalysis! 1. When the reaction temperature is constant, the preheating temperature of the raw materials directly affects the circulation amount of the catalyst, thereby affecting the depth of the reaction. ； 2. When the regenerator does not have heat extraction facilities, the raw material preheating temperature can control the bed temperature of the regenerator (heat balance of the regenerator) ； 3. According to different product plans, catalyst properties and raw material properties, each device should choose an appropriate preheating temperature and select appropriate operating conditions.

If the raw material preheating temperature is too high, the raw material atomization effect will be good, but when the reaction temperature is certain, the agent-oil ratio will decrease and the product distribution will become worse. The preheating temperature of the raw materials is too low, the atomization effect of the raw materials is poor, and the product distribution is also poor. This post was last edited by Shui Changshou on 2009-2-10 15:27 ]

High raw material preheating temperature will cause the agent-oil ratio to decrease, but the oil viscosity will decrease and the atomization performance will improve. The preheating temperature is low and the atomization effect is not good. When the ratio of agent to oil increases, the ratio of agent to oil increases. If the amount of stripping steam remains unchanged, the bed temperature may rise and the oxygen content will decrease. The burning effect will decrease. Severe cases may cause charcoal piles.

The preheating temperature is not a parameter that is often adjusted. Its level can affect the agent-oil ratio or reaction temperature, and can further affect the heat balance. The preheating temperature is generally determined based on the properties of the raw materials. ； When the device's processing capacity reaches the limit, the preheating temperature can also be increased to alleviate or slightly increase the processing capacity.

It also affects the heat balance of the fractionation system. If the feed oil exchanges heat with the oil slurry at the bottom of the tower, it can affect the production of saturated steam (from the perspective of our device, Shiwei Technology)

The raw material preheating temperature will affect the agent-oil ratio, heat balance, raw material atomization effect and passivation agent effect. When the temperature is low, the agent-oil ratio increases, the raw material atomization effect becomes worse, the reaction heat absorption increases, and the temperature is too high. On the contrary, the passivation agent will be thermally decomposed. If the raw material exchanges heat with the oil slurry, it will also affect the temperature of the oil slurry returning to the tower and the steam volume of the oil slurry steam generator. This post was last edited by Futou on 2009-2-9 16:08 ]

For the riser reaction, the reaction temperature is mainly adjusted by controlling the regeneration catalyst circulation amount through the regeneration slide valve. The raw material preheating temperature is no longer the main means of adjusting the reaction temperature. With the widespread adoption of various high-efficiency nozzles, the requirements for raw material preheating temperature are getting lower and lower. The reaction temperature, regeneration temperature, and raw material preheating temperature are closely related to each other. Under the same reaction temperature and feed amount, the raw material preheating temperature increases, the catalyst circulation volume decreases, the agent-oil ratio decreases, the conversion rate decreases, the coke production rate decreases, and the gas yield decreases. Generally speaking, if the raw material preheating temperature increases by 50°C, the regeneration temperature will increase by 10°C, the conversion rate will decrease by 2%, and the coke yield will decrease by 5 to 10% (based on the original coke yield). Catalytic cracking of coke has high yield and residual heat. Lowering the raw material preheating temperature is conducive to thermal balance. When the reaction temperature remains unchanged, lowering the raw material preheating temperature can increase the catalyst circulation volume and the agent-oil ratio. However, the raw material preheating temperature also has a lower limit. When the temperature is lower than 93°C, it will have adverse effects on transportation and feed atomization. For devices using cold feed, the raw material preheating temperature is generally not lower than 150°C.

Thanks! It has benefited a lot. We usually control it at 185 or 190 degrees. I don’t know what to do?

The preheating temperature of raw materials has a great influence on the reaction. As mentioned above, if it is high, the ratio of agent to oil will be low, and if it is low, the atomization effect will be poor. At present, each device fixes the raw material temperature at a lower temperature value that meets the atomization effect, and uses the catalyst circulation amount to control the reaction depth. Unless there are special circumstances such as major changes in the properties of the raw materials, the temperature of the raw materials is generally not adjusted.