According to the "Notice of the State Administration of Safety on the Announcement of the First Batch of Hazardous Chemical Technology Catalogs for Key Supervision" and the "Notice of the State Administration of Safety on the Announcement of the Second Batch of Hazardous Chemical

According to the "Notice of the State Administration of Safety on the Announcement of the First Batch of Hazardous Chemical Technology Catalogs for Key Supervision" (General Safety Supervision General Supervision 3 [2009] No. 116) and the "Notice of the State Administration of Safety on the Announcement of the Second Batch of Hazardous Chemical Technology Catalogs for Key Supervision and Adjustment of Some Typical Processes in the First Batch of Key Supervision Hazardous Chemical Technology Catalogs for Key Supervision" (General Safety Supervision 3 [2013] No. 3), there are 18 types of hazardous chemical technologies with key supervision. Today, we will select five processes: oxidation, fluoration, diazotization, hydrogenation and nitration, and give you a detailed introduction.

oxidation process

Process introduction:

oxidation is the process of electron loss in a chemical reaction with electron transfer, that is, the process of increasing the oxidation number. The oxidation reaction of most organic compounds is manifested in the reaction raw materials obtaining oxygen or losing hydrogen. The process involved in the oxidation reaction is an oxidation process. Commonly used oxidants include: air, oxygen, hydrogen peroxide, potassium chlorate, potassium permanganate, nitrate, etc.

Typical process

ethylene oxidation to ethylene oxide;

methanol oxidation to prepare formaldehyde;

p-xylene oxidation to prepare terephthalic acid;

cyclohexanyl oxidation to cyclohexanone;

natural gas oxidation to make acetylene;

butene, butane, C4 fraction or benzene to make maleic anhydride;

o-xylene or naphthalene to prepare phthalic anhydride;

p-chlorotoluene oxidation to prepare p-chlorobenzaldehyde (acid);

toluene oxidation to prepare benzaldehyde (acid) ; ; ; oxidation of cyclohexanone/ol mixture to prepare p-nitrobenzoic acid by oxidation of cyclohexanone/olize mixture to make adipic acid; synthesis of glyoxylic acid by oxidation of glyoxylic acid by oxidation of

butyraldehyde to butyric acid; oxidation of nitric acid by oxidation of

ammonia to make nitric acid, etc.

Process hazard characteristics

• reaction raw materials and products are ignition and explosion hazards;
• reaction gas phase composition easily reaches the explosion limit and has a risk of flash explosion; some oxidants in
• have ignition and explosion hazards, such as potassium chlorate, potassium permanganate, chromic anhydride, etc. are all oxidants. If they are exposed to high temperatures or impacts, frictions, and contact with organics and acids, they can cause fire and explosions; peroxides are easily generated in the products of
• , with poor chemical stability, and are easily decomposed, burned or exploded due to high temperatures, frictions or impacts.

Key Monitoring Unit

oxidation Reactor

Key Monitoring Process Parameters

Oxidation Reactor Temperature and Pressure

Oxidation Reactor Stirring Rate

Oxidation Reactor Flow

Reaction Material Ratio

Gas Phase Oxygen Content

Peroxide Content, etc. Basic requirements for safety control of tml1

reactor temperature and pressure alarm and interlocking; proportional control and interlocking of reaction materials and emergency cut-off power system;

emergency disconnection system;

emergency cooling system;

system for emergency inert gas;

gas phase oxygen content monitoring, alarm and interlocking;

safe discharge system;

combustible and toxic gas detection alarm device, etc.

Measures Recommendation

• Enterprises involving oxidation processes should promptly entrust professional institutions to conduct reaction risk assessments and take corresponding measures to ensure process safety based on the evaluation results.
• forms an interlocking relationship between the temperature and pressure in the oxidation reactor and the ratio and flow rate of the reactants, the oxidation reactor jacket cooling water water inlet valve , and the emergency cooling system. An emergency stop system is set up at the oxidation reactor. When the temperature in the oxidation reactor exceeds the standard or the stirring system fails, the feed is automatically stopped and emergency stops.
• is equipped with safety valves, blasting discs and other safety facilities.

Accident Review

1. At around 16:00 on June 1, 1974, an explosion occurred in the cyclohexane air oxidation reaction tank of Nypro, British company, causing 28 deaths and 36 injuries in the factory, and 53 people outside the factory were injured. Economic losses reached US$254.4 million.
2. On May 26, 1990, an explosion occurred in a chemical drug factory in Banqiao District, Japan, killing 5 people and injuring 17 people. The direct cause of the accident was: a sudden explosion occurred in the factory during the production of benzoyl peroxide.Benzoyl peroxide is mainly used as a catalyst for plastic polymerization. Its chemical properties are active and will explode if it hits or Mars.
3. At around 17:25 on April 9, 2009, a chemical plant that produced alkali dyes exploded and caught fire while carrying out material transfer operations, causing serious injuries to one person and direct economic losses of more than 600,000 yuan.
4. On April 25, 2016, an explosion occurred during the trial production process of the hydrogen peroxide device of Jiangxi Zhangjiang Chemical Co., Ltd., causing 3 deaths and 1 minor injury, and direct economic losses of about 15 million yuan. The direct cause of the accident is that during the trial production preparation stage, the acidic oxidation working fluid should be alkaline. After the emergency stop, the production manager attempted to recycle the unqualified working fluid, illegally discharged the oxidized working fluid into an acidic storage tank, and added phosphoric acid, attempting to re-adjust the oxidized working fluid to acidic. However, the hydrogen peroxide in the acidic storage tank quickly decomposes and releases heat under alkaline conditions, producing high temperature and combustible gas oxygen, causing the storage tank pressure to suddenly rise and explode, and ignites the oxidation working liquid.

2

fluorination process

process introduction

fluorination is a reaction of introducing fluorinated atoms into molecules, and the process process involving the fluorination reaction is the fluorination process. It is a strong exothermic reaction, and the release of a large amount of heat can damage the molecular structure of the reactant, or even catch fire and explode. Fluorinating agents are usually fluorine gas, halogen group fluoride , inert element fluoride, high-valent metal fluoride, hydrogen fluoride , potassium fluoride, etc.

Typical process

a. Direct fluorination of

yellow phosphorus fluoride preparation of phosphorus pentafluoride, etc.

b. Metal fluoride or hydrogen fluoride gas fluoride gas fluoride

SbF3, AgF2, CoF3 and other metal fluorides react with hydrocarbons to prepare fluorinated hydrocarbons;

Hydrogen fluoride gas reacts with aluminum hydroxide to prepare aluminum fluoride, etc.

c. Replace fluorinated

trichloromethane to prepare difluorommonochloromethane;

tetrachloropyrimidine and sodium fluoride to prepare 2,4,6-trifluoro-5-fluoropyrimidine, etc.

d. Preparation of other fluorides

concentrated sulfuric acid and calcium fluoride (fluorite) to prepare anhydrous hydrogen fluoride, etc.

Process hazard characteristics

1. reaction materials have the danger of burning and explosion;
2. fluorination reaction is a strong exothermic reaction, and the reaction heat is not eliminated in time, which can easily lead to overtemperature and overpressure, causing equipment explosion accidents;
3. most fluorinating agents are highly corrosive and highly toxic, and are prone to dangers caused by leakage, improper operation, misconception and other accidents during production, storage, transportation, and use.

key monitoring unit

fluorinating agent storage and transportation unit

key monitoring process parameters

temperature and pressure in fluorination reactor;

stirring rate in fluorination reactor;

fluorinated flow rate;

additive flow rate;

reactant ratio;

fluoride concentration. Basic requirements for safety control of

1. reaction kettle with alarm and interlocking of reaction feed and emergency cooling system; stable control system for stirring of
2. ; safe discharge system for
3. ;
4. combustible and toxic gas detection alarm device, etc.

Measures Recommendation

• Enterprises involving fluorination processes should promptly entrust professional institutions to conduct reaction risk assessments and take corresponding measures to ensure process safety based on the evaluation results.
• During the fluorination reaction, the fluoride concentration, feed ratio, feed speed and reaction temperature should be strictly controlled. If necessary, an automatic proportional adjustment device and an automatic interlocking control device should be installed.
• forms interlock control with the temperature and pressure of the fluorinated reactor with the stirring of the kettle, the fluorinated material flow rate, and the cooling water inlet valve of the fluorinated reactor jacket, and set up an emergency stop system at the fluorinated reactor. When the temperature or pressure of the fluorinated reactor exceeds the standard or the stirring system fails, the feed is automatically stopped and the vehicle is stopped urgently.
• safe bleed system.

Accident Review

1. On July 26, 2019, a hydrofluoric acid leakage accident occurred at Xingguoxing Fluorochemical Co., Ltd. in the Industrial Park of Xingguo County, Jiangxi Province.On July 27, Xingguo County Emergency Management Bureau issued a second notice on the handling of the leak, pointing out that due to the timely and appropriate on-site disposal methods, the leakage was fully controlled and no casualties were caused by the accident.
2. On January 9, 2016, a hydrogen fluoride leak poisoning accident occurred in the tetrafluoroterephthalene dimethanol workshop of Weifang Changxing Chemical Co., Ltd., killing 3 people and injuring 1 person. During the production process of tetrafluoroterephthalene dimethanol, hydrogen fluoride vapor was generated. Due to the illegal operation of the operation of the production process by the operators and the unscrupulous sealing of the reactor feed cover, hydrogen fluoride leaked and spread, causing poisoning of workers on site and adjacent workshops.
3. On April 14, 2012, three explosions occurred in the production workshop of vinylidene fluoride (VDF) of Inner Mongolia Sanaifu Marriott Fluorochemical Co., Ltd., and the workshop building was seriously damaged, many social security units were damaged, and a large number of pipelines were damaged, causing one person to die.
4. At 10:40 am on August 11, 2009, at 10:40 am, Jinghe Industrial Park, Xi'an City, Shaanxi Province, Sinochem Modern Environmental Protection Chemical (Xi'an) Co., Ltd., a reaction device for producing tetrafluoroethane (a refrigerant, a replacement product of Freon) malfunctioned, causing gas leakage (including more than 70 kilograms of hydrogen fluoride gas), resulting in three people being hospitalized and dozens of people undergoing series of examinations in the hospital.

3

diazogation process

process introduction

primary amine and nitrite at low temperature to generate diazonium salt reaction, such as: aliphatic, aromatic and heterocyclic primary amines. The process involved in diazotization reaction is a diazotization process. Usually, diazotization reagents are temporarily prepared from sodium nitrite and hydrochloric acid. In addition to hydrochloric acid, inorganic acids such as sulfuric acid, perchloric acid and fluoroboric acid can also be used. Aliphatic diazonium salts are very unstable and can quickly and spontaneously decompose even at low temperatures, while aromatic diazonium salts are relatively stable.

Typical process

cis-process

Sodium p-aminobenzenesulfonate and 2-Cai Phenol prepare acidic orange-II dye; aromatic primary amine reacts with sodium nitrite to prepare aromatic diazon compounds, etc.

reverse addition

m-phenylenediamine produces difluoroboric acid isophthalic diazonium salt; aniline reacts with sodium nitrite to produce aniline diazobenzene, etc.

nitrosylsulfate method

2-cyano-4-nitro aniline, 2-cyano-4-nitro-6-bromoaniline, 2,4-dinitro-6-bromoaniline, 2,6-dicyano-4-nitroaniline and 2,4-dinitro-6-cyanoaniline are coupling components of nitrogen components and ether-containing terminal amino groups to form monoazo dispersed dyes; 2-cyano-4-nitroaniline are raw materials to prepare blue dispersed dyes, etc.

Copper sulfate catalyst method

o-ortho-, m-aminophenol diazo compounds of ortho-, m-aminophenol are prepared by reacting weak acids (acetic acid, oxalic acid, etc.) or easy hydrolysis inorganic salts and sodium nitrite.

salting method

amino azo compounds are diazotized by salting method to produce polyazo fuels, etc.

Process hazard characteristics

• Diazo salts are very easy to decompose under slightly higher temperature or light, especially diazonium salts containing nitro, and some can decompose even at room temperature. In the dry state, some diazonium salts are unstable and have strong activity, and can decompose or even explode when heat or friction, impact, etc.; if the amount of acid is insufficient, the generated diazonium salt is easily coupled to the unreacted aromatic amine to form diazonium amino compounds; if the amount of acid is insufficient, the diazonium salt is easily decomposed, and the higher the temperature, the faster the decomposition.
• The sodium nitrite used in the diazotization production process is an inorganic oxidant. It can decompose at 175 °C, react with organic matter, and cause ignition or explosion.
• reaction raw materials are risky of burning and explosion. For example: 2,6-dichloro-p-trifluoromethylaniline, antho-aminobenzenesulfonic acid

key monitoring of process parameters

temperature, pressure, liquid level, pH value in the diazotization reactor;

stirring speed in the diazotization reactor;

nitrite flow rate;

reaction substance ratio;

post-processing unit temperature, etc.Basic requirements for safety control of

1. reactor temperature and pressure alarm and interlocking; proportional control and interlocking system of reaction materials of
2. reaction materials;
3. emergency cooling system;
4. emergency parking system;
5. safety discharge system;
6. post-processing unit is equipped with interlocking devices for temperature monitoring and inert gas protection, etc.

Measures suggest

(1) Safe transportation of raw materials and products

Aryl amine and sodium nitrite must be transported in separate vehicles and stored; products must be lightly loaded and unloaded when transporting diazonium salts to prevent friction and impact; during storage, diazonium salts and sodium nitrite should be kept away from fire sources, power sources or other heat sources, and avoid sunlight.

(2) Strictly control the feeding volume and speed

Sodium nitrite feeding is finished, and the reaction solution is tested using starch potassium iodide test strips. It is slightly blue, which means the feeding volume is appropriate. If excessive sodium nitrite is found, remedial measures should be taken in a timely manner. The control of the feeding rate of sodium nitrite should be different based on the alkalinity of the aromatic amine. The alkalinity is strong, and the feeding speed of sodium nitrite must be slow.

(3) Equipped with safety devices and equipment

forms an interlocking relationship with the temperature and pressure in the diazotization reactor with the stirring, sulfite flow rate, and the cooling water inlet valve of the diazogation reactor jacket. An emergency stop system is set up at the diazotization reactor. When the temperature in the diazotization reactor exceeds the standard or the stirring system fails, the feed is automatically stopped and the vehicle is stopped urgently. Diazo salt post-treatment equipment should be equipped with automatic control and adjustment devices for temperature detection, stirring and cooling interlocking, and drying equipment should be equipped with interlocking devices for temperature measurement, heating heat source switch, and inert gas protection.

(4) has corresponding safety facilities, including safety valves, blasting discs, emergency vent valves, etc.

Accident Review

1. On July 1, 2014, an N-(6-chloro-3-pyridinylmethyl)methylamine storage tank in the production workshop of Ningxia Ruitai Technology Co., Ltd., causing 4 deaths and 1 injury, and direct economic losses of about 5 million yuan. The direct cause of the accident was that the N-(6-chloro-3-pyridinyl)methylamine in the storage tank was in a heat-insulating state for a long time, and a polycondensation reaction occurred. The large amount of heat and gas generated could not be discharged in time, causing the container to explode overpressure.
2. At 7:40 on December 31, 2012, a an anirine leakage accident occurred in Shanxi Tianji Coal Chemical Group Co., Ltd., located in Changzhi City, Lucheng City, and a transport hose rupture occurred.
3. At 6:20 pm on June 12, 2010, in a factory in Hechuan District, Chongqing, an operator was conducting a test, and a container filled with sodium nitrite exploded and leaked. The accident caused no casualties.
4. On November 13, 2005, an explosion occurred in the aniline workshop of the bibenzene plant of Jilin Petrochemical Branch of China National Petroleum and Natural Gas Co., Ltd., and the accident caused 8 deaths and 60 injuries. Tens of thousands of residents and students near the chemical industry area were urgently evacuated, with direct economic losses of 69.08 million yuan, and a water pollution incident in Songhua River was triggered.
5. On February 17, 1994, a poisoning accident occurred in the methylamine branch of Yueyang Nitrogen Fertilizer Factory in Hunan Province, with 3 people killed and 4 people injured, with direct economic losses of about 1.57 million yuan.
6. On September 3, 1991, the escort personnel of hazardous chemicals from the pesticide plant in Shaxi Town, Shangrao, Jiangxi Province, after driving into the village, colliding with mulberry trees beside the road due to violating relevant regulations on hazardous chemical transportation, causing a large amount of highly toxic monomethylamine liquid to quickly gasify and leak, causing 42 deaths, 156 people to be severely poisoned, and 595 people to be poisoned.

4

Hydrogenation process

Process introduction

Hydrogenation is a reaction of adding hydrogen atoms to organic compound molecules. The process involved in the hydrogenation reaction is a hydrogenation process, mainly including unsaturated bond hydrogenation, aromatic ring compound hydrogenation, oxygen-containing compound hydrogenation, nitrogen-containing compound hydrogenation, hydrogenation, hydrogenation, etc.

Typical process

• Unsaturated alkynes and triple bonds and double bonds of olefins: cyclopentide hydrogenation to produce cyclopentene, etc.
• aromatic hydrocarbon hydrogenation: benzene hydrogenation to produce cyclohexane; phenol hydrogenation to produce cyclohexanol, etc.
• Hydrogenation of oxygen-containing compounds: carbon monoxide hydrogenation to produce methanol; butanaldehyde hydrogenation to produce butanol; octenal hydrogenation to produce octanol, etc.
• nitrogen-containing compounds hydrogenation: adipiconet hydrogenation to produce hexanediamine; nitrobenzene catalyzed hydrogenation to produce aniline, etc.
• oil product hydrogenation: distillate oil hydrocracking produces naphtha, diesel and tail oil; residual oil hydrogenation and modification; reduced pressure distillate oil hydrogenation and modification; catalytic (isomeristic) dewaxing production of low-condensation diesel, lubricating oil base oil, etc.

Process hazard characteristics

1. reaction materials have the risk of combustion and explosion, and the explosion limit of hydrogen is 4%~75%, which has the characteristics of high combustion and explosion;
2. hydrogenation is a strong exothermic reaction, hydrogen comes into contact with steel under high temperature and high pressure, and the carbon molecules in the steel are easily reacted with hydrogen to form hydrocarbons, which reduces the strength of steel equipment and causes hydrogen embrittlement;
3. catalyst regeneration and activation process is prone to explosion;
4. hydrogenation reaction exhaust gas has incompletely reacted hydrogen and other impurities that are easily ignited or exploded when discharged.

Focus on monitoring process parameters

hydrogen temperature and flow rate;

cooling medium flow rate and outlet temperature;

reaction kettle temperature and pressure;

reactor sealing;

ambient temperature;

system oxygen content;

outlet gas composition and concentration, etc.

basic requirements for security control

is based on a high-performance industrial control computer and an over-control system (DCS/PLC/FCS) as the operating environment. Based on conventional control methods, it realizes complex, multi-variable, large-scale and high-stability high-performance control for equipment devices or specific core equipment in the entire production process. After the actual implementation of advanced control methods, the control effect of the production process can be improved, and various control indicators can be improved to increase the economic effect of the enterprise and reduce energy losses.

• realizes automatic feeding and setting up security interlocking;
• uses an automatic control system to record the device status and interlocking protection conditions and status in real time, and the system can automatically alarm once an abnormality occurs;
• determines the maximum allowable hydrogen pressure in the process and sets current limiting measures that cannot be overshooted;
• adopts a dual temperature control system to monitor the temperature in the kettle in real time that does not exceed the upper limit of the reaction temperature and the maximum temperature allowed by the system;
• sets an emergency cooling system (uninterrupted) to ensure that the reactor can be stopped quickly and cooled in sudden conditions such as cooling water failure and power outages;
• regularly maintains and tests the automatic production system and safety chain system to ensure its reliability;
• sets lightning protection isolation measures.

Measures recommended

• every time you use the reactor, you need to have airtight inspection and strengthen on-site ventilation to minimize the leakage of combustible gases and reduce their concentration below the explosion limit;
• strictly controls the fire source to avoid combustible gas fire and explosion accidents;
• regularly maintains and checks the maintenance and verification of on-site alarm instruments.
• strictly monitors important parts such as reactors, high-pressure heat exchangers, high-pressure air coolers, circulating hydrogen compressors, circulating hydrogen desulfurization towers, tail oil systems, etc. Once problems such as over-temperature and over-pressure and over-process indicators occur, they will be quickly alarmed and processed in a timely manner;
• During the shutdown of the device, it pays attention to the complete and full release of hydrogen by high-pressure hydrogen equipment to prevent the occurrence of hydrogen embrittlement;
• strengthens the management of the equipment and improves the inherent safety factor of the device. Pay attention to areas where high temperature hydrogen corrosion may occur. Material upgrades are carried out for equipment and pipelines with severe corrosion to ensure the inherent safety of the equipment;
• strengthens drills for accident emergency plans, regularly organizes job operators to learn various accident plans, and improves employees' ability to handle emergencies;
• strengthens fire protection and gas prevention management to ensure that fire protection and gas prevention facilities are intact and fire roads are unobstructed; combustible gas alarm facilities in the
• device are regularly verified.

Accident Review

1. At around 1:40 pm on January 15, 2020, the pre-hydrogenation unit of Guangdong Zhuhai Changlian Petrochemical Equipment Co., Ltd. flashed and exploded, and the scene was filled with flames. At 4:06 pm, the Propaganda Department of Zhuhai Municipal Party Committee issued a message saying that the open fire at the scene had been extinguished and there were no abnormalities in the indicators of the online environmental monitoring site.
2. At around 13:49 on May 3, 2018, a flash explosion occurred in the kettle during the catalyst removal process of the hydrogenation kettle No. 1 hydrogenation workshop of Taixing Yangzi Pharmaceutical Chemical Co., Ltd., which caused one person to die and a direct economic loss of 1.446 million yuan.
3. At 16:14 on March 12, 2018, a 600,000-ton/year diesel hydrogenation device raw material buffer tank V501 of Sinopec Jiujiang Branch suffered an explosion, killing 2 people and slight burns, with direct economic losses of 3.38 million yuan.
4. At 7:00 on March 22, 1987, the low-pressure separator of the hydrogen refining plant in the Greater Month refinery in the UK exploded due to overpressure, and a fire followed. The accident caused one person to die, the device was seriously damaged, and economic losses of $78.5 million.

5

Nitrification process

Process introduction

Nitrification is the reaction of introducing nitro (-NO2) into organic compound molecules, and the most common is the substitution reaction. The nitration method can be divided into direct nitration method, indirect nitration method and nitroscopy method, which are used to produce nitro compounds, nitramines, nitrate esters and nitroscopy compounds, etc. The process involved in nitration reaction is the nitration process.

typical process

direct nitration method

glycerol reacts with mixed acid to prepare nitroglycerol

chlorobenzene nitration preparation ortho-nitrochlorobenzene, p-nitrochlorobenzene

benzene nitration preparation nitrobenzene

anthraquinone nitration preparation 1-nitroanthraquinone

toluene nitration production trinitrotoluene (commonly known as Tienti, TNT)

propane and other alkanes are prepared by gas-phase reaction with nitric acid nitroalkane, etc.

indirect nitration method

phenol, use substituted nitration of sulfonyl groups to prepare picric acid, etc.

nitrite method

2-naphthol and nitrite to prepare 1-nitroso-2-naphthol

diphenylamine react with sodium nitrite and aqueous sulfuric acid to prepare nitroso-dianiline, etc.

nitration reaction in small or intermediate tests, the reactor is small, the material is uniform, and the reaction temperature is easy to control. Once industrialized, if replaced with a large reactor, the situation will be completely different and the risk will be greatly increased. reaction risk research and safety risk assessment can essentially study the safety and reliability of the process, and effectively guide process optimization through risk research, providing parameters for process design.

Process hazard characteristics

1. fast reaction speed and large heat release. Most nitration reactions are carried out in heterogeneous phases, and the uneven distribution of reaction components can easily cause local overheating and causing danger. Especially at the beginning of the nitration reaction, it is very dangerous to stop stirring or cause stirring failure due to falling off the stirring blades. Once the stirring starts again, it will suddenly trigger a local intense reaction, instantly releasing a large amount of heat, causing an explosion accident; the
2. reaction material has the risk of combustion and explosion; the
3. nitrating agent has strong corrosiveness and strong oxidation, and contact with oils and greases, organic compounds (especially unsaturated organic compounds) can cause combustion or explosion; the
4. nitration products and by-products are explosive.

focus on monitoring process parameters

• impurity content;
• feeding flow, feeding temperature;
• nitration reactor heat exchanger heat exchange medium;
• nitration kettle temperature (multiple temperature probe points should be set);
• stirrer current, voltage, stirring rate.

basic requirements for safety control

• realizes automatic feeding and sets safety interlocking; calculation process control requires the maximum allowable flow, set fixed non-overshooting flow limiting measures; set drop-added material pipe mirrors.
• The nitration kettle is equipped with a dual thermometer to strictly control the upper and lower limits of the nitration reaction temperature, and prohibit the temperature exceeding the limit, especially the state of exceeding the lower limit, so as to avoid the process out of control caused by material accumulation and reaction lag.
• nitrification kettle is equipped with an emergency cooling system (uninterrupted) to ensure that the nitrification device can be stopped urgently in emergencies such as cooling water failure and power outage.
• key equipment of nitrification system, such as nitrification kettle stirring, should be equipped with an independent backup power supply (EPS), which can ensure that the stirring runs normally until safely stop when the power grid fluctuates.
• has added a Process Information Manager System (PIMS) to strengthen the supervision of violations of DCS operators, and can automatically send alarm information to relevant personnel for abnormal important process parameters of nitrification devices.
• regularly maintains and tests the nitrification automatic production system and safety interlocking system to ensure the reliability of DCS and safety interlocking systems.
• sets lightning protection isolation measures for DCS system.

Measures suggest that

1. related enterprises should establish a complete nitration process safety information file, including improving thermodynamic research in all links of the process, especially thermal characteristic data such as heat release velocity and heat release, and screen the best control points for the reaction based on the real information to achieve the inherent safety and controllability of the process.
2. carries out process risk identification and evaluation, comprehensively collects safety production information on chemical material characteristics, processes and equipment involved in the production process, proposes safety factor parameters such as process control points, equipment selection requirements, operation redundancy requirements, inspection points, etc., and gradually improves safety information files such as process system transformation, factory design, production operations, equipment maintenance experience, emergency response measures, etc.
3. is strictly prohibited from disabling the nitration reaction system's temperature, feed, cooling, stirring, emergency emission and other alarm and automatic safety interlocking systems, so as to prevent unpredictable results due to artificial removal of interlocking or forgetting to enter interlocking.
4. When the production process changes, the changed process must be re-analyzed, process reaction safety assessment, etc., and relevant personnel training and assessment should be conducted for the changed process.
5. sets up a complete process parameter change system. When it comes to process parameter changes, strictly follow the system. Operators are prohibited from changing the reaction process parameters at will.
6. is strictly prohibited from illegal operations and unlawful operations, and clarify the job responsibilities of employees at all levels.
7. regularly conducts OTS simulation operation training and accident drills to improve the emergency response capabilities of relevant personnel.
8. is strictly prohibited from occupying blocked fire passages, and an emergency gathering and avoidance area is set up.
9. When it comes to the treatment of nitrification product waste, risk identification and evaluation must be carried out, and relevant information must be provided to the disposal party completely.