Risk factors and preventive measures during normal

Risk factors and preventive measures during normal production of hydrocracking

1. abide by the principle of "cooling first and then reducing volume"

during the normal operation and adjustment of the hydrogenation unit, the principles of "cooling first and then reducing the volume" and "increasing the volume first and then increasing the temperature" must be observed to prevent the occurrence of "flying temperature" accidents

2. control of reaction temperature

the reaction temperature of the hydrogenation unit is the most important control parameter, and the hydrogenation reaction temperature and the temperature rise of each bed must be strictly controlled according to the process technical indicators

3. liquid level control of high pressure separator

the liquid level of high pressure separator is a very important process control parameter of hydrogenation device, such as improving the sensitivity of refrigeration system. If the liquid level is too high, it is easy to carry liquid in circulating hydrogen, which will damage the circulating hydrogen compressor; If the liquid level is too low, it is easy to cause high-pressure to low-pressure accidents, causing damage to low-pressure equipment, oil and combustible gas leakage, and even more serious consequences. Therefore, the liquid level of the high-pressure separator should be strictly controlled and the accuracy of the liquid level instrument should be frequently verified

4. reaction system pressure control

the reaction system pressure of the hydrogenation unit is an important process control parameter. The reaction pressure affects the hydrogen partial pressure and has a direct impact on the hydrogenation reaction. There are many factors affecting the reaction system pressure of the hydrogenation unit. An economic, reasonable and convenient control scheme should be selected to control the pressure of the reaction system

5. Control of circulating hydrogen purity

circulating hydrogen purity affects hydrogen partial pressure and has a direct impact on hydrogenation reaction. It is an important process control parameter of hydrogenation unit. There are many factors affecting circulating hydrogen purity. The nature of catalyst, the nature of feed oil, reaction temperature, pressure, purity of fresh hydrogen, tail hydrogen emission and other factors all affect circulating hydrogen purity, of which the operable condition is tail hydrogen emission. Increase the tail hydrogen emission and increase the purity of circulating hydrogen; Reduce the tail hydrogen emission and reduce the purity of circulating hydrogen

if the purity of circulating hydrogen is high, the hydrogen partial pressure will be high, which is conducive to the hydrogenation reaction. However, the high purity of circulating hydrogen is at the cost of a large amount of tail hydrogen emission and increased material consumption; If the purity of circulating hydrogen is low, the hydrogen partial pressure will be low, which is not conducive to the hydrogenation reaction. Moreover, when the purity of circulating hydrogen is low, the average molecule of circulating hydrogen has established a large amount of after-sales service and market quality information feedback mechanism. When the rotating speed of circulating hydrogen compressor remains unchanged, the system differential pressure will increase, and the power consumption of circulating hydrogen compressor will also increase. Therefore, the purity of circulating hydrogen should be properly controlled

6。 Control of Likou heating furnace

heating furnace is an important equipment of hydrogenation unit, and the use of heating furnace should be paid attention to. The flow of each circuit of the heating furnace shall be kept uniform and not lower than the specified value. In addition, coking of the furnace tube shall be prevented; Keep the fire nozzles of the heating furnace burning evenly, and try to make the temperature of all points in the furnace hall uniform; Control the temperature of each point of the heating furnace not to exceed the temperature; Keep the heating furnace in good combustion condition

7. turn off the light and check

the system pressure of the hydrogenation device is high, and the medium is hydrogen, which is prone to leakage. The high pressure is mainly reflected in the following aspects. When hydrogen leaks, it is easy to catch fire. The hydrogen flame is generally light blue, which is not easy to find during the day. After turning off the light at night, it is easy to find this kind of hydrogen leakage point. Therefore, regular night light off inspection is of great significance to find leakage points, eliminate accidents in the bud, and ensure the safe and stable operation of the device