Hydrogen sulfide is soluble in water and ethanol, and can be mixed with air to form an explosive mixture, which can be induced by combustion and explosion when exposed to open flame and high heat energy. In case of high heat, the internal pressure of the container increases, and there is a risk of opening and explosion.
Hydrogen sulfide is a byproduct of many industrial productions. Currently, more than 70 occupations have access to hydrogen sulfide. These occupations include mining, oil extraction and refining, leather manufacturing, rubber synthesis, gas production, man-made fibers, papermaking, dyes, printing and dyeing, sugar production, food processing, etc. In addition, hydrogen sulfide is also produced in organic matter spoilage sites, so hydrogen sulfide is also exposed when cleaning garbage, gutters, cesspools, and vegetable cellars.
1. Physical and chemical properties of hydrogen sulfide
hydrogen sulfide: Hydrogen sulfide, CAS: 7783-06-4, molecular formula H2-S, is a colorless, "rotten egg" odor toxic gas, molecular weight 34.08, melting point: -82.9°C, boiling point: -61.8°C, relative density (air = 1): 1.19, Saturated vapor pressure: 2026.5kPa (25.5°C), critical temperature: 100.4°C, critical pressure: 9.01MPa, lower explosion limit: 4.3%, upper explosion upper limit 45.5%, ignition temperature: 260°C, minimum ignition energy: 0.077mJ, maximum explosion pressure: 0.490Mpa, mixed with air can form an explosive mixture, which can cause combustion explosion when exposed to open flame and high temperature. Violent reaction with concentrated nitric acid, fuming nitric acid or other strong oxidizing agents, explosion. Hydrogen sulfide is heavier than air and can diffuse far away at the bottom, quickly causing reignition in open flames. In addition, it is soluble in water, methanol, ethanol and petroleum solvents, and crude oil.
2. Toxicity characteristics of hydrogen sulfide
Hydrogen sulfide is a strong nerve poison that invades the human body by inhalation, and is absorbed through the mucous membranes of the human body faster than poisoning caused by skin absorption. The local irritating effect of hydrogen sulfide on the mucosa is caused by the decomposition of sodium sulfide after contact with the moist mucosa and its own acidity. Since the human central nervous system is most sensitive to hypoxia, it is the human central nervous system that is the first to be damaged. If a person inhales hydrogen sulfide 70~150 mg/cubic meter/1~2 hours, respiratory and eye irritation symptoms will appear: tearing, eye pain, photophobia, blurred vision and runny nose, cough, burning throat, olfactory fatigue after inhalation for 2~5 minutes, no longer smelling odor, and becoming numb; If inhaled mg/cubic meter/1 hour, acute eye irritation symptoms will occur in 6~8 minutes, and pulmonary edema will occur if exposed for a long time. Inhalation of 760 mg/cubic meter/15~60 minutes, pulmonary edema, bronchitis, pneumonia, dizziness, headache, nausea, vomiting, fainting, fatigue, confusion and other symptoms; If inhaled within 1000 mg/cubic meter/seconds, acute poisoning will soon occur, and sudden coma will occur, resulting in respiratory and cardiac arrest, and lightning death. High concentrations of contact with the conjunctiva of the eye can cause edema and corneal ulceration. Long-term exposure to low concentrations can cause neurasthenia syndrome and autonomic nerve dysfunction.
The local irritating effect of hydrogen sulfide on the mucosa is caused by the decomposition of sodium sulfide after contact with the moist mucosa and its own acidity. The systemic effect on the body is hydrogen sulfide and the body's cytochrome oxidase and the disulfide bond (-S-S-) in this enzyme, which affects the cytochrome oxidation process, blocks intracellular respiration, and leads to systemic hypoxia. Hydrogen sulfide acts on hemoglobin and produces hemoglobin sulfide and causes chemical asphyxia, which is the main pathogenesis. In the early stage of acute poisoning, the activity of cytochrome oxidase in brain tissue was inhibited and the glutathione content increased.
3. Based on prevention and strict monitoring
Understanding the characteristics of hydrogen sulfide, strictly preventing the harm of hydrogen sulfide, and strengthening the safety monitoring and management of hydrogen sulfide are urgent and unshirkable.
1. Safety supervision in accordance with the law
Production and business units must strictly abide by the "Work Safety Law of the People's Republic of China", "Fire Protection Law of the People's Republic of China" and "Regulations on the Safety Management of Hazardous Chemicals" and other laws and regulations, and consciously accept the safety audit and safety inspection of the work safety supervision and administration bureau, the Quality and Technical Supervision Bureau, the public security fire protection, hazardous chemical management, supervision and other departments. Relevant production equipment must comply with the "Pressure Vessel Safety Supervision Regulations" and other relevant regulations. Production and business units that use or can produce hydrogen sulfide must choose equipment with legal qualifications.
2. Strengthen basic management
Establish a safety production committee of production and business units, improve the safety production management organization network, clarify that the legal representative of the unit is the first person responsible for safety production work, and implement the safety production responsibility system and the signing and assessment of the responsibility system at all levels. Strictly abide by various safety management rules and regulations and safety operation procedures. Ensure that the management system is in place, the safety responsibility is to the person, the monitoring measures are to the point, and the assessment is in place. Formulate and implement effective emergency response plans for production safety accidents or incidents. Conscientiously do a good job in management and on-site safety inspection, timely implement the rectification of hidden dangers of production safety accidents, and make daily records.
3. Implement training and education
Hydrogen sulfide full-time managers and on-the-job operators must have a high sense of safety responsibility. You must go through regular professional training, retraining and safety commitment education, and obtain a certificate of operation qualification before you can operate with a certificate. must master safety management rules and regulations, safety operation procedures and related safety knowledge. Familiar with the characteristics of production equipment, workplaces, and workplaces, as well as existing risk factors, preventive measures, and accident emergency measures.
4. Open flames and high temperatures are strictly prohibited
Strict fire prevention rules and regulations and management measures must be clarified on site and in warehouses. Hot operations must strictly implement the approval procedures and the principle of "ten do not burn". In summer, measures such as shading and avoiding light, ventilation and cooling must be taken for high temperatures. Open flames, steam, and exposure to the sun are strictly prohibited. It is strictly forbidden to store flammable, explosive, toxic and harmful items. And clearly separated from other departments, especially from flammable, explosive, toxic and harmful chemicals.
5. Strict and safe operation
The work site must clearly set up relevant prohibition signs, warning signs, instruction signs, and reminder signs. Equipment, containers, pipelines, etc. should be safe and firm to prevent collisions and impacts. The connection port, connection pipe, and safety device must fit tightly to prevent damage and leakage. The safety protection, interlocking, signal, alarm, insurance and other devices of the equipment are complete, complete, reliable and effective, so that there must be interlocking if there is danger and alarm if there is a leak. The pressure gauges, control valves, safety devices, measuring equipment, buffers, and lifting and transportation equipment must be complete, effective and reliable. Safety devices such as pressure gauges must be tested and inspected on schedule and in quantity, and can only be used after passing the test and inspection. Special transport vehicles must be marked with dangerous goods and escort supervision measures shall be implemented.
6. Improve emergency measures
Carry out regular safety inspections to eliminate hidden dangers of production safety accidents in a timely manner. Report unexpected production safety accidents or accident seedlings in a timely manner. Equipped with effective gas masks and protective equipment. Equipped with emergency communication equipment, gas detector, smoke alarm, multi-functional fire extinguishing water gun, fire hydrant, sprinkler device, fire hose and other fire rescue facilities, equipment and materials. Regularly organize drills on emergency response plans to improve the emergency response ability of full-time managers, on-the-job operators and fire safety personnel to correctly handle accidents.
7. Properly dispose of garbage
Hydrogen sulfide gas that is easy to generate or dispose of at production sites or in sewage, garbage, feces treatment, sedimentation tanks, etc., must be strictly disposed of and prevented in accordance with relevant regulations, and illegal discharge is prohibited. When entering or cleaning sewage treatment tanks, manholes, gutters, and septic tanks, measures must be implemented, filtering gas masks must be worn correctly, pre-inspection and prediction must be done to prevent blind operation and illegal operation, and solo operation is prohibited.
Fourth, emergency rescue is people-oriented
To prevent hydrogen sulfide, focus on implementing measures to prevent poisoning casualties, fire prevention and explosion; In particular, it is necessary to implement a practical and effective emergency response plan, and in the event of an accident or disaster, the emergency rescue plan for hazardous chemical accidents should be quickly implemented, and the evacuation of on-site personnel should be quickly organized, and response measures should be taken to prevent the spread of disasters.
1. Quickly implement protection and rescue
(1) First of all, cover the mouth and nose with soaked towels and other fabrics, quickly evacuate the poisonous and polluted area to the upwind area, and isolate, wash and inspect.
(2) Quickly call 119, 110, 120 and other emergency numbers for help.
(3) Do not run blindly and shout loudly to prevent toxic gas inhalation and smoke choking. It is necessary to borrow the sound of beating and wave light, color and other objects to achieve the purpose of calling for help.
(4) If you encounter a foreign body sensation in your eyes, you should immediately open your eyelids, rinse with plenty of water or saline for at least 15 minutes, and seek medical attention immediately; If you feel that breathing is not good, quickly leave the scene to an open area with fresh air, loosen the collar, and keep the airway open. pay attention to keeping warm when the temperature is low, and closely observe the state of breathing and consciousness; If breathing is difficult, oxygen should be given immediately; If you are faced with respiratory and cardiac arrest, you should immediately perform cardiopulmonary resuscitation such as artificial respiration and chest compressions at the same time, pay attention not to use mouth-to-mouth breathing methods to prevent staggered poisoning, and immediately give oxygen to keep the airway open, apply glucocorticoids in a short distance, and use symptomatic, supportive and other comprehensive therapies in a timely and reasonable manner; Hyperbaric oxygen therapy can be used when conditions permit moderate and severe poisoning. Pay attention to the prevention and treatment of cerebral edema and pulmonary edema, and implement first aid measures.
(5) Fire rescue personnel must do a good job of self-protection and mutual rescue, and wear full-body fire prevention and anti-virus clothing, such as wearing filtered gas masks or oxygen respirators, wearing chemical safety protective glasses, wearing chemical protective gloves, etc., to ensure the safety of rescue personnel and the scene.
2. Immediately organize emergency evacuation
(1) Quickly find and cut off and block dangerous sources such as gas sources and fire sources to prevent spread and spread. If the gas source cannot be cut off for a while, it is not allowed to extinguish the burning or leaking hydrogen sulfide gas. If it encounters a container or pipeline, it should spray water to cool and cool it to reduce the pressure and temperature in the container or pipe.
(2) Standing upwind, use jet mist water to dilute, dissolve and flush the contaminated area to prevent the spread and spread of hydrogen sulfide gas. And use mist water, anti-soluble foam, dry powder and other fire extinguishers to extinguish the fire.
(3) If an accident or danger source is located near densely populated areas such as schools, hospitals, government agencies, museums, important departments, entertainment venues or residential areas, a "water wall" must be immediately set up to prevent fire, explosion, toxic gas disasters, etc.
(4) There are dangerous chemicals such as flammable, explosive, toxic and harmful around, which must be quickly separated and transferred.
(5) Be cautious in using electrical devices and electrical wiring, and it is strictly forbidden to use electrical equipment and tools that are prone to sparks.
3. Strengthen on-site supervision and treatment
(1) Seize the time to repair and inspect, and seal and repair the damaged leakage in time. When entering restricted spaces such as containers, pipelines or other high-concentration areas, supervision must be implemented.
(2) Reasonable local exhaust and comprehensive ventilation should be adopted to accelerate the dissipation of hydrogen sulfidetoxic gas and control it