Discussion on the safety of reaction kettle in fin

Discussion on safety technical measures for reaction kettle in the operation process of fine chemical enterprises

fine chemical production enterprises have several main production workshops and several auxiliary workshops, and have several sets of reaction kettle and rectification tower. On the whole, there are many equipment, many storage tanks, and pipes are densely distributed vertically and horizontally; In terms of structure, the whole production system is composed of several production units. Each production unit is composed of three national quality inspection centers and laboratories with one or more reactors, condensers and distillation columns

this paper focuses on the safety technical measures in the operation of the reaction kettle in the unit system. Taking a normal pressure reactor and a condenser for liquid material transportation and exothermic reaction as the simplest operation unit, analyze the possible dangerous and harmful factors, formulate corresponding safety precautions, and implement the emergency plan for emergencies

I. Analysis of main dangerous and harmful factors:

1. Feeding error: the feeding speed is too fast, the feeding ratio is out of control or the feeding sequence is wrong, which may produce a rapid exothermic reaction. If the cooling cannot be synchronized, heat accumulation will be formed, causing local heating decomposition of the material, forming a rapid reaction of the material and generating a large number of harmful gases, resulting in explosion accidents

2. Pipeline leakage: during feeding, for atmospheric pressure reaction, if the emptying pipe is not opened, when the pump is used to transport liquid materials into the kettle, positive pressure is easy to form in the kettle, which is easy to cause cracking at the connection of the material pipe, and material leakage, resulting in personal injury. During unloading, if the materials in the kettle are not cooled to the specified temperature (generally below 50 ℃), the materials with higher temperature are easy to deteriorate and cause splashing of materials and scalding of operators

3. Too fast temperature rise: due to the too fast heating speed, low cooling rate and poor condensation effect of the materials in the kettle, it is possible to cause the materials to boil, form a vapor-liquid mixture, generate pressure, and implement pressure relief flushing from the weak links such as vent pipe and vapor phase pipe, as well as the pressure relief system such as safety valve and bursting disc. If the charging cannot reach the goal of rapid pressure relief, the kettle body explosion may occur

4. Hot work for maintenance: during the reaction of materials in the kettle, if electric welding and gas cutting maintenance operations are carried out without taking effective preventive measures, or sparks are generated by the impact and knocking of fastening bolts and ironware, once flammable and explosive leaked materials are encountered, fire and explosion accidents may be caused

II. Safety technical countermeasures:

1. Heating control measures: for the material heating system with the reaction temperature below 100 ℃, steam and hot water can be used for segmented heating. Under the condition of ensuring that the materials do not deteriorate due to local overheating, first heat them to about 60 ℃ with steam at a medium speed to improve the production efficiency, and then heat them with 100 ℃ boiling water circulation, slowly heat them up to the temperature specified in the process and keep them warm for reaction. In this way, the segmented heating can not only improve the production efficiency, but also prevent the local high-temperature thermal decomposition or violent vaporization of materials, thus forming a vapor-liquid mixture and flushing explosion. It can also improve the yield of material equilibrium reaction and reduce the consumption cost

2. Chain cooling measures: for exothermic reaction, it is necessary to heat up at the initial stage of the reaction so that all personnel can have a happy and peaceful 2018 Spring Festival, but the reaction process will release heat, so the excess heat must be transferred quickly and effectively. The normally used reactor cooling system is mainly jacket cooling and coil cooling, and the coolant used is mainly circulating water and refrigerant. The cooling speed of refrigerant is fast but the cost is high. In the case of abnormal reactions in the production process, especially when the temperature and pressure rise sharply, the operators will quickly evacuate the operation site for their personal safety, unable to effectively cut off the heating source and effectively start the cooling system. Therefore, an emergency start-up cooling interlock system should be set up in a remote place outside the operation post. It is better to be close to the steam valve of the workshop steam cylinder, turn on the cooling interlock system while closing the steam valve and cutting off the mixing power supply, and implement the measures of cutting off heat, cutting off power, stopping mixing, and quick cooling of graphene support, also known as aerogel gel quick cooling, so as to control the accident in the initial stage and prevent the further expansion of the accident

3. Chain explosion relief measures: in order to prevent the materials in the kettle from releasing pressure in time when the temperature is out of control and the gas is generated to form pressure, the atmospheric reaction equipment, also as an interior part, should be installed with emergency pressure relief facilities according to the specific situation of the reaction. Safety valves should be installed on the top of the kettle, and bursting discs should be installed for processes that may have severe reactions. The outlet of the connecting pipe of the bursting disc must extend to the outdoor safe place or the outlet of the exhaust pipe, and cannot directly point to the road or the operation platform, so as to prevent people from being injured by material splashing. If there is a dropping reaction process, the dropping acceleration should be strictly controlled