Risk factors analysis and preventive measures of t

Analysis of risk factors of catalytic reforming and its preventive measures

(1) in the process of shutdown, cooling and volume reduction, strictly prevent overheating, abide by the principle of cooling first and then volume reduction, and do not lower the temperature without cooling or slow cooling and rapid volume reduction. Strictly follow the reactor cooling curve to prevent damage to the catalyst caused by too high temperature. Master the cooling speed to prevent the high temperature and high pressure flange leakage and ignition of the hydrogen system caused by too fast cooling

(2) no dead corner shall be left in the nitrogen replacement process, and the water cutting line, sampling valve, instrument pressure lead line, reactor auxiliary line and heat exchanger of each separation tank shall not be omitted. Prevent oil and gas ignition, burning pipelines and equipment, causing casualties and other accidents during maintenance and hot work. When the content of "hydrocarbon + hydrogen" in the sampling and analysis system is 0.3%, it is qualified, and the nitrogen replacement is ended

(3) precautions during the regeneration of pre hydrogenation catalyst:

① the regeneration medium is steam and air. ② At the beginning of coke burning, if the catalyst bed temperature is 200%, the temperature of the bed must be raised to 200 ℃ with nitrogen before steam can be introduced, so as to prevent the steam from condensing into water when it is cold and damaging the catalyst. ③ During the regeneration process, the catalyst is prevented from being broken due to large temperature fluctuations. ④ The catalyst bed temperature is 510 ℃. If it is over temperature, measures should be taken: reduce or stop making up air, reduce the furnace outlet temperature, and shut down the fire in serious cases

(4) precautions for reforming catalyst regeneration process:

① regeneration medium is nitrogen and oxygen. ② The temperature rise should be strictly controlled at all stages. When the temperature rise is close to the index, the amount of air make-up should be reduced as soon as possible. When the temperature rise exceeds the standard, the air make-up should be stopped. If the temperature rise still fails to fall, each furnace can be cooled or flameout, and if necessary, the nitrogen cooling and replacement system should be connected

(5) if the catalyst needs to be replaced, ensure that the content of "hydrocarbon + hydrogen" is 0.3% in the nitrogen environment when opening the reactor cover, and the bed temperature drops below 60%, so as to prevent the spontaneous combustion of iron sulfide and the burning of the reactor under high temperature

(6) pay attention to personal safety during the loading and unloading of catalyst and the cleaning and inspection of reactor, and analyze the oxygen content and hydrogen sulfide content in the reactor before operation. Strictly implement the relevant work permit system. After the analysis is qualified, set up a soft ladder, fasten the safety belt, wear a forced ventilation respirator to enter the reactor for operation, and have a guardian outside the reactor to prevent personnel poisoning and suffocation accidents. Recently

2. Dangerous factors and their prevention during the start-up process

(1) the hydrogen equipment, instruments, pipelines, valves, flanges, welded junctions and threads of the reforming pre hydrogenation system are all subject to nitrogen gas tightness inspection to prevent leakage after the start-up and oil inlet, resulting in fire and explosion and other dangerous accidents

(2) the catalyst drying should be carried out in strict accordance with the temperature rise curve of the scheme. During the temperature rise process, pay close attention to the temperature change of the catalyst bed. If the temperature rise is found, the temperature rise should be stopped immediately

(3) if the temperature of catalyst bed rises during chlorine injection, reduce the chlorine injection speed. When the temperature rises by 20 ℃, timely notify the chlorine injection personnel to stop chlorine injection

(4) in the process of catalyst pre vulcanization, the operator must wear an anti hydrogen sulfide poisoning mask and hydrogen sulfide detector when entering the device for patrol inspection and operation, and quickly evacuate the site when giving an alarm. In case of hydrogen sulfide poisoning accident, the plan to prevent hydrogen sulfide poisoning shall be implemented immediately, and the positive pressure respirator shall be brought to the site to save people

(5) after the start-up of reforming and the completion of pre vulcanization, the oil should be fed quickly to achieve normal operation in the active stage of the initial vulcanization. In the oil feeding stage, attention should be paid to the stability of various process conditions. After reforming oil feeding, pay close attention to whether the reactor bed is overheated. In case of abnormal conditions such as the sharp decline in the purity of circulating hydrogen and the continuous rise of the reactor bed temperature higher than the inlet temperature during the heating up, the constant temperature observation shall be carried out immediately. In case of overtemperature, the laboratory shall closely cooperate with each other to conduct necessary analysis, so as to strengthen the monitoring and judgment of overtemperature. Record the bed temperature every 30min from the oil inlet to 450 ℃. If it is judged to be overtemperature, the following measures can be taken:

① when the purity of hydrogen decreases by less than 10%, or there is a temperature rise of about 5 ℃, it can be observed at a constant temperature. ② In constant temperature, if the hydrogen purity decreases by 10% and the temperature rises by 5 ℃, the workshop will decide whether to inject sulfur again. ③ In order to meet the needs of social products and environmental protection, the secondary injection of sulfur is still ineffective, and measures can be taken to reduce the reaction temperature or stop oil feeding