Safety technology of the hottest feeding process

2022-07-26
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Feeding process safety technology

feed process safety in chemical process

there are generally three feeding methods

(1) the pressing method is mostly used for the feeding of gas raw materials. The pressure must be controlled during pressing. When the gas is supplied by gas cylinders, the pressure relief valve should be used. The difference between the gas pressure input to the reactor after pressure reduction and the gas pressure in the container should not exceed 0.15Mpa to prevent the gas flow rate from being too fast. A strong false advertisement is formed at the outlet to redefine: "telling stories" in the future or being severely sprayed to generate static electricity. Before pressing flammable gas, the air in the reactor shall be pumped out by negative pressure or driven out by inert gas such as nitrogen. The reactor, pressure pipe, platform or scale for placing gas cylinders shall be grounded. The pressure pipe shall be of large diameter to ensure that the gas flow rate in the pipe will not be too fast

the feeding of liquid raw materials can adopt a high-level tank to let the liquid flow into the reactor by using its own weight. This method is safe because of its low pressure and low flow rate. However, when there is pressure inside the reactor, it must be pressurized for feeding. At this time, if it is a flammable liquid, it should be pressurized with inert gas instead of compressed air to prevent the formation of explosive mixture. If it is transported by pump, the special pump for transporting flammable liquid should be adopted, such as Y-type liquid hydrocarbon pump. The steam reciprocating pump is also safer. If ordinary centrifugal pump and gear pump are used, the impeller must be made of non-ferrous metal to prevent sparks caused by the collision between the impeller and the iron shell. There are many lessons to be learned from explosion accidents when using ordinary pumps to transport flammable liquids. Do not be careless. Ceramic pump or glass pump is easy to generate static electricity due to poor conductivity, and shall not be used to transport flammable liquids. The outlet of the pressurized feeding device should preferably be in a horn shape, which can reduce the flow rate at the outlet and prevent violent spraying and static electricity; The equipment shall not leak and shall be grounded

(2) compressed air should not be used for negative pressure pumping powder or small particle materials to avoid flying dust. If negative pressure pumping is adopted, it is relatively safe. During material pumping, the equipment is connected to the vacuum system, and a filter or water washer shall be provided at the inlet from the reactor to the vacuum pipeline to prevent dust from being pumped into the vacuum pipeline. If the suction pipe is an insulator, the inner and outer walls shall be lined with spiral copper wire, and the copper wire and the reactor shall be grounded. If a conductor pipe is used, the copper wire can be omitted, but the test procedure is still the same as that for grounding. If flammable liquid with low boiling point exists in the reactor, the negative pressure pumping method should not be used

liquid raw materials can generally be fed by negative and pressure pumping methods, and the whole pumping system should be grounded. During material extraction, the feed pipe shall be extended into the bottom of the reactor to lean against the wall. The pipe diameter shall be large and the flow rate shall be slow. If it is a flammable liquid with a resistivity of 1010 ~ 1015 cm, the flow rate should be limited, and the initial velocity should preferably be controlled within 1m/s. The mixture of flammable liquid vapor and air in front of the flammable liquid at the beginning of transportation will explode in case of electrostatic sparks. It is strictly prohibited to spray the liquid on the liquid level to avoid static electricity

the control ability of the upstream raw material market for flammable liquid shall be improved by suction. When feeding, the liquid temperature shall be at least 30 ℃ lower than the boiling point. When the liquid temperature is high, the temperature shall be reduced first and then the material shall be extracted, so as to prevent a large amount of gasification loss of liquid, resulting in inaccurate proportioning and abnormal reaction, which may cause fire hazard

(3) manual feeding of flammable and toxic liquid raw materials is not suitable for manual dumping

most of the solid materials are fed manually except for the suction method. The feeding sequence shall meet the requirements. In principle, it is low-temperature feeding. Heating shall be conducted after all feeding is completed. If there is water in the raw material ratio, on the premise of not affecting the reaction, water should be added first, then solid, and finally flammable liquid. If there is no water -, the solid material shall be added first, and then the liquid material shall be added, so as to avoid a large amount of flammable liquid vapor escaping during feeding

when solid materials are put into the reactor with flammable liquid, if the solid materials are placed in bags made of synthetic fiber or plastic film, these bags shall not be used to directly feed the reactor, so as to prevent the danger caused by electrostatic sparks caused by friction. The materials shall be poured into the wooden barrel first, and then into the reactor from the wooden barrel. It is forbidden to wipe the residual powder at the kettle mouth with nylon cloth and other synthetic fiber rags with high resistance and low water absorption to prevent electrostatic sparks

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