The risk factors for dissolving acetylene production units are mainly combustion and explosion, as well as poisoning, corrosion and other hazards and harmful factors.

1. Analysis of dangers and harmful factors in the production process

(1) The occurrence section

1 calcium carbide library

The calcium carbide warehouse belongs to the Class A fire danger warehouse. Calcium carbide decomposes with water to produce acetylene, which forms an explosive mixture with air. Water in the calcium carbide warehouse is the main risk factor and should be strictly prevented. For example, when transporting calcium carbide in rainy days, the base of the calcium carbide warehouse is not high enough when heavy rain or flash floods, the water at the top of the warehouse is leaking, the relative humidity is too large, or the fire in the warehouse fire is extinguished.

The calcium carbide powder accumulated in the calcium carbide warehouse and the crushing room is excessively accumulated, and may absorb moisture to decompose and produce acetylene.

Calcium carbide generally contains ferrosilicon, which collides with other metals, and is prone to sparks, which often becomes the source of fire for acetylene combustion explosion.

When the calcium carbide barrel is opened, it is welded with gas or steel. The open flame or spark is easy to cause the acetylene gas to burn in the barrel. When loading and unloading and handling the calcium carbide barrel, the force is too large, and the collision produces a spark, causing an explosion. There is residual calcium carbide powder in the barrel, which will produce acetylene when it is stored.

The presence of certain substances such as iron oxide, copper oxide and aluminum oxide can adsorb acetylene on its porous surface and promote the polymerization and explosion decomposition of acetylene molecules. Iron drums containing acetylene have such adsorption and are at risk of forming explosive mixtures.

In 1989, an underground calcium carbide warehouse in the western part of the Ukrainian city of Vinnitsa, the Soviet Union, exploded, killing 19 people and injuring more than two people. The explosion destroyed 20 homes and partially damaged another 10 houses. The explosion was caused by two workers who lit cigarettes in the warehouse and encountered acetylene at an explosive concentration.

2 acetylene generator

The ignition of the acetylene generator calcium carbide feed port is a part of the dissolution of acetylene which is prone to a malignant accident. The main causes of accidents are: when the stone is added, the collision between the calcium carbide or the calcium carbide and the wall, or the calcium content of the calcium carbide, or the collision of the calcium carbide bucket with the metal, or the electric hoist wire, etc., may cause fire. If the concentration of acetylene in space reaches the explosion limit, it will cause an explosion. Nitrogen replacement is not complete, or because the nitrogen is low, or the nitrogen tube is not smooth, so that the nitrogen intake is insufficient, an explosive mixture of acetylene is formed.

Local overheating of calcium carbide causes decomposition and explosion of acetylene: the amount of water in the acetylene generator is insufficient, or the water is not changed in time according to the regulations, so that the temperature in the reaction zone rises rapidly; the small particle size of the calcium carbide is excessive, the hydrolysis rate is too fast, causing local overheating; the particle size of the calcium carbide is too large. The calcium hydroxide formed during hydrolysis envelops the calcium carbide to form a dense outer skin, causing the calcium carbide to be overheated severely, and may also affect the hydrolysis of the calcium carbide, resulting in hydrolysis of the acetylene in the slag pool to form an explosive mixed gas.

If the generator is operated incorrectly, the liquid level is too low, and the feed water seal loses its effect, which will cause the generator acetylene gas to escape, or the outside air to enter, forming an explosive mixed gas.

3 gas cabinet

The gas cabinet is too low, and the generator gas volume is too late to be replenished. Under the action of the reciprocating compressor or the suction, a negative pressure is formed and enters the air, and an explosive mixed gas is easily formed.

The water tank float water seal is short of water, and the acetylene gas may escape and form an explosive mixed gas.

(2) Purification section

The presence of PH3 in acetylene reduces the autoignition point, and may be self-igniting in contact with air, causing an explosion of acetylene.

The effective chlorine of sodium hypochlorite solution is more than 0.15% (especially when the pH is low), and the risk of explosion of chloroacetylene is easy to occur; when the effective chlorine is above 0.25%, both chlorine and acetylene are prone to violent reaction and explosion. The light can cause this explosion process.

If the acetylene gas flows back into the sodium hypochlorite preparation system, or when the sodium hypochlorite is used, the water in which the acetylene is dissolved (such as the generator circulating water) may cause the acetylene to mix with the chlorine gas, causing an explosion accident.

Chlorine is a highly hazardous medium. Once it leaks into the working space and exceeds the maximum allowable concentration, it will cause harm to the human body. If the concentration is too high, it will cause personal injury or death.

Liquid chlorine also has the property of liquefied gas. The chlorine gas cylinder is not well stored. It is exposed to sunlight, open flame, heat radiation, etc., causing the bottle temperature to be too high. The temperature inside the bottle will significantly increase the pressure inside the tank and cause an explosion.

The liquid chlorine cylinder leaks and the toxic chlorine gas diffuses, which may cause personal poisoning.

The pipeline of liquid chlorine from the gas cylinder to the buffer tank will be frosted by the liquid chlorine gas, and the human body may be exposed to frostbite.

Sodium hypochlorite solution, lye strong corrosive articles, if spilled and spilled, contact with the operator, there is a risk of burns to the human body. It can cause damage to the body's mucous membranes, especially the eyes.

(3) Compression filling and filling section

The high-pressure part of acetylene is emptied. If there is no flame arrester, it is easy to generate static electricity due to gas friction and cause fire and explosion.

Under high pressure, acetylene does not cool well, encounters high temperature objects or sparks when the valve is actuated, which is prone to decomposition and explosion.

Risk factors for acetylene gas cylinder explosion:

1) The cylinder filling pressure is too high and the speed is too fast, which may cause the acetylene cylinder to overpressure, or the temperature is too high to melt the fusible plug.

2) The material, structure and manufacturing quality of the gas cylinder do not meet the safety requirements, such as brittleness of the material, uneven thickness of the bottle wall, and interlayer.

3) When handling and loading and unloading, the cylinder falls, falls or rolls from a high place, causing a violent collision impact.

4) Poor storage, exposure to sunlight, open flames, heat radiation, etc., resulting in excessive bottle temperature and increased pressure.

5) The bottle valve of the gas cylinder leaks, and the high pressure airflow rushes out, causing an explosion.

6) The acetylene cylinder is discharged in a horizontal position, and acetone and acetylene flow out, causing an explosion.

7) The amount of acetone in the bottle is too small, the amount of gaseous acetylene is increased, or the compressed acetylene is formed, and its stability is poor, and the external energy is liable to explode.

(4) Other dangerous and harmful factors in the production of acetylene

Equipment, pipelines, valves, etc., leak due to poor quality or improper installation or impact, use over-pressure ruptures, leaks, tearing of gaskets, leakage of the gasket, flow meter, instrument connection Leakage, unstable operating pressure causes the water seal to leak. If acetylene leaks easily form a fire or explosion environment, chlorine gas leakage may cause poisoning damage.

When the vehicle is turned on, the nitrogen is not completely drained, and the oxygen content is excessive, which may cause the system to explode.

Nitrogen replacement is not complete, entering the air during maintenance, and forming an explosive mixture with residual acetylene.

Dust hazard: calcium carbide dust is generated during the crushing, sorting and feeding of calcium carbide. If it is improperly protected, skin contact or respiratory absorption can cause chemical burns.

There is no static grounding device or non-standard equipment and pipelines. During the process of storing and transporting acetylene, static electricity accumulates and discharges, which may cause electric fire and may cause fire or explosion.

During on-site inspections, if iron tools are used, there is a possibility that a spark in the collision of the iron will cause a fire and explosion.

The production system uses copper, silver-containing appliances or mercury thermometers to break. Acetylene and copper, silver and mercury easily form metal compounds such as acetylene copper, acetylene silver or acetylene mercury, and they explode spontaneously in the dry state.

2. Common injury

(1) Electric shock injury

There are material pumps, fans, compressors, electric hoists and other electrical equipment in the device. If the electrical equipment is accidentally or the electrical installation is not standardized, the grounding or zeroing is lacking, or the grounding is connected to zero and the damage is invalid, an electric shock injury will occur. Temporary lines laid along the wall or laid along the ground are not covered by protective casing or insulation, and electric shock may occur if they are in contact with the human body. Because the device uses low voltage power, the electric shock is low voltage electric shock. Power distribution room, generating system, purification engineering, compression section, fire pumping station, etc. are dangerous places.

(2) Static electricity, lightning hazard

During the material conveying process, or the compressed gas containing mist droplets and dust leaks and leaks, static electricity is easily generated. If there is no static electricity across the grounding device or fails, there is a danger of fire and explosion caused by static electricity accumulation and discharge. Especially the mixture of air and acetylene has a minimum ignition energy of only 0.019 mJ, which is easily ignited by static sparks.

In the absence of lightning protection facilities or lightning protection facilities, the grounding resistance is too large, and lightning or lightning induced discharge may occur. Therefore, lightning protection facilities should be installed in production plants, warehouses, etc., and inspection and testing should be carried out on time to ensure that the lightning protection facilities are in good condition. The grounding resistance of equipment pipelines should be within the specified requirements to avoid losses caused by lightning induction.

(3) Falling from high altitude and falling from high altitude

There are platforms, ladders, high-level electric hoists or overhaul scaffolding in the installation. In the operation and overhaul of the workers, there is a danger of falling from high altitude and falling from high objects.

(4) Mechanical injury

There are a variety of rotating equipment such as liquid pumps and compressors in the production equipment, which poses a risk of mechanical injury. If the quality of the backrest wheel is not good, the installation is not strong, or the operation is wrong, the back wheel may break and fly out. If the rotating part lacks the guardrail and the guard, during the operation and scrubbing, the employee may hit, the clothing or the long The hair is entangled and causes damage.

(5) Noise damage

There are acetylene compressors, pumps and other rotating equipment in the production equipment. If there is fault or poor lubrication, and the operation is nearby, it will cause noise damage. In addition, gas filling and detection, maintenance and release of gas, collision of loading and unloading cylinders A source of noise is also generated. In noisy jobs, operators must wear earmuffs to reduce the risk of noise.