A newcomer seeking advice on several issues related to catalytic cracking

1. **Use of the crude gasoline failure limit** – Usually, when it is found during the production process that certain properties of crude gasoline do not meet the quality requirements, the crude gasoline failure limit is used. For example, if the sulfur content, octane rating, evaporation rate, etc., of crude gasoline do not meet the specifications, or if contamination is detected during the storage and transportation of the product, this line may be used to separate the substandard gasoline from the qualified gasoline. 2. **The situation of using stabilized gasoline to improve unqualified crude oil** Stabilized gasoline is generally used to improve the properties of crude gasoline. When the quality issues of crude gasoline are not too severe and can be corrected through blending or other treatment methods, it is common practice to use stabilized gasoline for blending. This can help achieve standard quality while reducing the production of defective products. - **Methods to improve the substandard grade** – **Sequence**: Usually, stable gasoline is first used in mixing to see if it can improve the properties of the crude gasoline. If improvement is not possible, other treatments may be required, such as further refining or returning to the upstream process for reprocessing. - **Series pressure risk**: This refers to the possibility of oil and gas leaks or equipment damage occurring due to pressure changes when dealing with substandard gasoline. When adjusting the rejection line, care should be taken to prevent this from happening. Ensure that the pressure in pipes and equipment remains within safe limits by using appropriate valves and safety devices. 3. **On-site operations and precautions for maintaining pressure during stable shutdowns** – **Operation steps**: First, it is necessary to ensure that the pressure within the equipment and pipelines remains stable. Gradually reduce the feed while maintaining unobstructed exhaust to prevent pressure buildup due to gas accumulation. Then, gradually close the valves to ensure that the equipment and pipelines are not affected by pressure fluctuations during shutdown. - **Precautions**: - **Safety protection**: Ensure that operators wear appropriate safety equipment to avoid direct contact with high-temperature or high-pressure equipment. - **Pressure monitoring**: Continuously monitor the pressure in pipelines and equipment to ensure there are no abnormal changes. - **Leak detection**: Ensure that there are no oil or gas leaks throughout the process; use a leak detector if necessary to carry out inspections. - **Prevent accidental restarts**: Ensure that all switches and valves that could cause the device to restart accidentally are properly turned off. .