The production system of hazardous chemicals enterprises mainly includes dynamic equipment, static equipment, electrical equipment and instrument equipment. The biggest risk of production system of hazardous chemicals enterprises in cold winter is freezing risk, and anti-freezing and anti-freezing is the key work to ensure the smooth operation of production devices in winter. In winter, the climate is dry and the air humidity is low. Experimental studies show that with the increase of environmental humidity, the electrostatic potential decreases rapidly, otherwise it will cause electrostatic accumulation. It is prone to fire and explosion caused by accidental discharge of static electricity. In winter, in the state of cold and high pressure, the measures to be taken to prevent cold and heat preservation in the workplace often affect ventilation, resulting in the accumulation of toxic and harmful gases, which is easy to cause poisoning and suffocation accidents.

On November 27, 2015, heilongjiang Shengnong Science and Technology Development Co., Ltd. rented grass plant equipment of Hegang Xuxiang Heyou Chemical Co., Ltd. for the industrial test of ethyl pyrithanole, poisoning accident occurred, resulting in the death of 3 employees. B its direct cause of the accident, according to new product in the process of the pilot test of phenol, containing methyl mercaptan tail gas pressure absorption and tertiary alkali absorption system of induced draft fan exhaust opening and exhaust connection pipe for low temperature frozen wall, ethyl methyl mercaptan tail gas is contained in its phenol synthesis process cannot eduction, the reaction kettle in steam heating pressure-out, containing methyl mercaptan tail gas leak, Three operators on the scene died of poisoning.

At around 14:07 on September 28, 2020, an explosion occurred at Tianmen Chutian Biotechnology Co., LTD., causing six deaths and one minor injury. Accident direct reason is that enterprises in the use of filter machine for 2 nitro anthraquinone liao, when filter, filter material flows under pressure, electrostatic, and polypropylene fiber filter cloth friction energy accumulation to liao critical value after the outbreak of the electrostatic, liao fire decomposition, a dramatic increase in temperature and pressure in the filter testing machine, This results in the explosion of dinitroanthraquinone in the pressure filtration machine.

01
Risk prevention and control suggestions for winter antifreeze of production system
1. Anti-freezing measures for dynamic equipment
(1) Regularly carry out the investigation of the potential dangers of anti-freezing for large units, set up the dry gas sealing tracing system, and ensure that the insulation measures are intact and effective.
(2) Strengthen the monitoring of sealing liquid level in mechanical sealing system of high-temperature oil pump and light hydrocarbon pump.
(3) Ensure that the flushing line of the mechanical seal of the pump is unblocked, and the double-line valve of cooling water of the rotating equipment should be slightly opened. For the temporarily cut water pump, ensure that the pump inlet and outlet valve is closed strictly. For the inlet and outlet valve that is not closed strictly, blind plate or shower guide valve should be added and normally opened.
(4) Ensure that the heat tracing facilities of the unit and pump lubricating oil system are in good condition and in the state of commissioning.
(5) For the cooling water pipeline of the machine pump, the valve should be maintained at a certain opening to make the water flow long.


2. Anti-freezing measures for static equipment
(1) Safety accessories are in good condition. Ensure that the material before and after the safety valve nozzles does not crystallize or freeze. Heat preservation for the pressure gauge guide pipe, and heat preservation and heat tracing for the on-site level gauge to prevent freezing.
(2) Empty the facilities and pipelines in the underground valve well, close the root valve, empty the water on the upper part of the valve through the drainage valve, and keep the drainage valve normally open, and take sealing and warm measures for the underground valve well.
(3) Heat preservation system should be set up for pressure vessel and pipeline valve to ensure that the heat preservation and tracing system works normally at low temperature. Each dewatering tank of pressure vessel should have good heat preservation, and the drainage outlet should be intact and unobstructed, and the water should be drained regularly.
(4) The atmospheric pressure storage tank with low condensation point is equipped with a heat preservation and tracing system, and it is forbidden to open the sealing surface to prevent the storage tank breathing valve from freezing.
(5) The static equipment and pipelines that are not used for a long time should be emptied, the relevant valves should be closed, and the blind plate should be added if necessary to prevent leakage in the valve; Open the high exhaust valve and low exhaust valve to empty the material in the equipment; Purge and replace residual materials with nitrogen. Always open the low drain valve and check it regularly.
(6) The trap and shower guide valve should be intact and unobstructed, and the standby equipment should also be anti-freezing and anti-coagulation.
(7) Reliable drainage or heat tracing measures should be taken for long-distance pipelines with condensate risk to avoid freezing and blocking; The guide valve on each steam pipe should be slightly opened to ensure that a small amount of steam is discharged.


3. Anti-freezing measures for electrical equipment
(1) To often check the transformer section switch, pressure valve and high and low pressure casing whether there is oil seepage, to timely tighten, oil filling treatment. Strengthen the oil level inspection of oil-filled equipment, timely fill oil in power transformers and other oil-filled equipment, sulfur hexafluoride electrical equipment gas pressure and oil-filled cable, to ensure that the oil level is normal.
(2) Repair and replace the damaged Windows and doors of the power distribution room and transformer room in time, seal the holes in time to prevent small animals from entering, and do a good job of insulation protection for exposed busbars and joints of outdoor power distribution devices.
(3) The outdoor switch mechanism box and terminal box should be closed and intact, and measures should be taken to prevent rain and snow from invading and dampness, water pouring and icing from causing insulation decline, and improve insulation protection measures for power distribution devices.
(4) Outdoor motor junction box and cooling air channel should take measures to prevent rain and leakage, and prevent the coil and lead from being damp and short circuit fault.
(5) Do a good job in the operation and maintenance of electric tracing facilities, and improve the operation reliability of electric tracing facilities. Ensure that the door of the switch control box of electrical equipment is tightly closed and the fastening bolts are complete and fastened to prevent steam discharged from the production device from entering the switch control box nearby and reduce the insulation performance of electrical components.


4. Instrument equipment anti-freezing measures
(1) Control the air water content of the instrument, regularly conduct centralized drainage of the instrument air and liquid gas medium, check and centralized charging of the isolator system.
(2) Strengthen the quality control and storage management of antifreeze liquid, ensure that the quality of antifreeze liquid meets the requirements of use, and pour antifreeze spacer in advance for heavy oil, residual oil, wax oil and other materials that are easy to freeze and set.
(3) The thermal insulation steam of the instrument pipeline is the same as the gas source used for the instrument. Steam must be supplied separately to minimize the relationship with the steam system used for process production. Take measures to prevent water inflow and icing at the inlet, air inlet and vent of the accessories such as instrument, control valve and solenoid valve.
(4) Pay attention to the applicable working environment temperature range of field instruments and working performance changes under low temperature, and do preventive maintenance and rectification work in advance.


02
Anti-static measures for the production system
1. Try to select materials with relatively adjacent positions, small contact area and pressure, less contact times, slow movement and separation in the charged sequence.
2. All objects belonging to an electrostatic conductor must be grounded.
3. Ensure that the static grounding facilities are in good condition, and install the static moderator for high-charged materials.
4. Add an appropriate amount of antistatic additives.
5. Partially or completely shield the charged body to reduce static electricity accumulation.
6. Use an electrostatic eliminator to quickly neutralize static electricity.
7. Control the flow rate when transporting flammable and explosive medium.
8. No sampling or testing operation is carried out during material handling.
9. Increase the relative humidity of the air in places with special static electricity requirements.
10. Equip the workers with antistatic labor protection equipment and explosion-proof tools.


03
Production system anti-gas anti-asphyxiation measures
1. Thoroughly isolate toxic and harmful substances based on lessons learned from the accident.
2. For the continuous release of toxic and harmful substances, compulsory ventilation measures should be taken, and fixed toxic gas detection and alarm instrument should be equipped.
3. Strengthen sampling management. It is strictly prohibited to introduce the instrument gas source pipeline involving toxic gas into the manned operating room.
4. Gas protection stations should be established according to the actual situation of the enterprise, and necessary emergency rescue equipment and first-aid drugs should be equipped.