What safety precautions should be paid attention to when working in air separation workshop?

1. What safety measures should be paid attention to when the air separation plant stops to discharge cryogenic liquid?

Answer: The oxygen content of liquid oxygen and liquid air in the air separation plant is high, which will increase the oxygen concentration in some areas after evaporation in the air. If ignited, there is a danger of burning and explosion. A chemical fertilizer plant once had an explosion accident because it discharged a large amount of liquid oxygen into the trench and encountered electric welding sparks. Therefore, it is strictly forbidden to discharge liquid into the trench at will, and it should be discharged into the liquid evaporation tank or special low-temperature resistant metal drainage pit through the pipeline.

The drainage pit should be kept clean, and no organic matter or grease accumulation is allowed. When discharging liquid, it is forbidden to use fire around.

Contact of cryogenic liquid with skin can cause severe frostbite. Mild blistering, redness and pain on the skin; In severe cases, internal tissues and bones and joints will be frozen. If you fall into your eyes, it will do harm to your eyes. Therefore, when discharging liquid, avoid direct contact with liquid by hand, and wear dry cotton gloves and protective glasses when necessary. In case of contact with skin, rinse immediately with warm water (below 45℃).

2. Which parts of the oxygen generator are most likely to explode?

Answer: The location of oxygen generator explosion is related to the type of air separation equipment to some extent. In the process of high pressure, medium pressure and double pressure, the possibility of explosion is relatively large; The main cooling of the device producing liquid oxygen did not explode, but the main cooling of the gas-oxygen device was the center of the explosion. The degree of explosion damage is related to the explosive force, and a weak explosion may only damage individual pipelines, even without being noticed by operators.

The explosion position of condensation evaporator varies with its structure. Generally, it is easy to occur at the boundary of liquid oxygen surface, and some channels with poor liquid oxygen flow also occur at the lower tube plate or the upper cover. For the auxiliary condensing evaporator, the explosion is easy to occur in the lower part of liquid oxygen near evaporation.

According to statistics, except the condenser evaporator, explosions have occurred in other parts. Comprises a lower part of a liquid air inlet of a lower tower; Liquid-air adsorber; Tray at the liquid gas inlet of the upper tower; Liquid oxygen discharge pipe; Liquid oxygen pump; Oxygen channel at the cold end of the switching heat exchanger; Acetylene separator after auxiliary condensing evaporator, etc.

No matter where the explosion occurs, the reason is the existence of liquid oxygen (or oxygen-enriched liquid air), which causes the concentration, accumulation or precipitation of dangerous substances in the evaporation process, forming an explosive mixture and promoting the explosion under certain conditions.

3. What safety precautions should be paid attention to when checking the pressure pipeline?

Answer: For pipelines under pressure, the most common problem in the production process is the leakage at the connecting flange. Once a leak is found, do not tighten the bolt under pressure. Because there are some reasons for leakage in operation, such as gasket damage, pipeline thermal stress and so on. At this time, the problem can't be solved by screwing bolts alone. It is often because the leakage has not been eliminated that the bolt is screwed hard until the bolt is unscrewed, and the high-pressure gas in the pipe is ejected, causing personal injury accidents. Several accidents have occurred in several factories, such as bolt breakage and flange flying out because of screwing bolts.

Therefore, we must strictly abide by the rules that no bolts are allowed to be screwed with pressure, and we must not take chances in order to seize time and catch up with the task and violate the operating procedures.

4. What problems should be paid attention to when maintaining air separation equipment for hot welding?

Answer: When the oxygen generator is shut down for maintenance and needs hot welding, we should pay attention to the following issues:

1) If an open flame is needed in the oxygen generator workshop, it should be approved by the superior, and the oxygen concentration around the site should be detected to strengthen fire control measures. When the oxygen concentration at the welding site is higher than 23%, welding cannot be carried out. When the oxygen concentration is lower than 19%, suffocation accidents should be prevented;

2) Vessels with air pressure cannot be welded before pressure relief;

3) For low-temperature vessels that are not completely heated, it is forbidden to repair them with hot work, so as to avoid excessive thermal stress or failure to guarantee welding quality. In severe cases, if liquid oxygen and gaseous oxygen are released, it may also cause a fire;

4) The whole process of hot work shall be supervised by the safety officer.

5. What safety issues should be paid attention to when exposed to oxygen?

A: Oxygen is a colorless, odorless and tasteless gas. This is a catalyst. It can be mixed with combustible gases (acetylene, methane, etc.). ) are mixed in a certain proportion to form an explosive mixture. When the oxygen concentration in the air increases to 25%, it can cause a violent combustion reaction. When the oxygen concentration reaches 27%, Mars can develop into a lively flame. Therefore, fireworks are strictly prohibited around the oxygen-making workshop and oxygen-making device. When clothes are saturated with oxygen, they will burn quickly when they meet an open flame. Especially clothes contaminated with grease. When exposed to oxygen, it may spontaneously ignite. Therefore, oxygen-saturated clothes should be diluted by outdoor ventilation immediately. At the same time, the oxygen generator operators or those who come into contact with oxygen and liquid oxygen are not allowed to be oiled.

6. What safety issues should be paid attention to when contacting nitrogen?

Answer: Nitrogen is a colorless, tasteless and odorless inert gas. It is harmless to human body, but when the nitrogen content in the air increases, it will reduce the oxygen content and make it difficult for people to breathe. If you inhale pure nitrogen, you will suffocate and die due to severe hypoxia.

In order to avoid the increase of nitrogen content in the air of the workshop, the nitrogen separated from the air separation plant shall not be discharged indoors. Wear an oxygen respirator when there is a lot of nitrogen. When repairing nitrogen charging equipment, containers and pipelines, air must be used for replacement first, and the operation can only be carried out after the oxygen content analysis is qualified. During maintenance, the nitrogen valve should be supervised to prevent personal accidents caused by opening the valve by mistake.

7. What harm does ammonia do to human body? What problems should I pay attention to when contacting?

Answer: Ammonia is colorless and has a pungent smell. Splash of ammonia water into eyes can cause conjunctival congestion and edema rapidly, accompanied by severe pain, and the cornea will be cloudy or even blind. Rinse immediately with plenty of water (not less than 15 minutes) and treat as soon as possible.

Contact of ammonia or high concentration ammonia with skin can cause burns, erythema, blisters and even necrosis. After the skin is burned by ammonia, rinse it with plenty of water 15min or more, then rinse the affected area with 2% acetic acid or wet compress it with 5% boric acid.

Inhalation of ammonia can cause poisoning. Symptoms include irritation of eye mucosa and nasal mucosa, tearing, sneezing, chest tightness, cough and stomachache. In severe cases, it may lead to lung swelling and even death. When the air contains ammonia 1L/0.5 mg/l, there is a danger of poisoning; When it contains 3 mg/L, it can be fatal if it stays for 5 ~ 6 minutes. Generally, the allowable concentration is 0.03 mg/L. After poisoning, you should leave the scene quickly and take it to a place with fresh air for treatment.

Wear rubber gloves and multi-layer wet protective mask when contacting ammonia, and wear gas mask or oxygen respirator when the concentration is high. When dealing with ammonia leakage urgently, cover the respiratory tract with a wet towel and leave the scene as soon as possible.

8. What harm does noise do to human body? How to eliminate noise?

Answer: Noise is an irregular complex tone containing various tonal components, and its harm to human body is mainly hearing damage. The intensity of sound is measured in decibels (dB). If you work under the noise condition of 100dB for a long time (high frequency noise is 80 ~ 90 dB), it will cause hearing damage. Noise will also have adverse effects on the nervous and cardiovascular system of human body.

Therefore, it is currently stipulated that the noise allowed in the workplace should not exceed 90dB.

The noise of oxygen station mainly comes from high-speed compressor and gas outlet. The spectral characteristics of noise are related to the type and speed of compressor, the layout of pipeline, the structure and opening of valve, the pressure and flow rate of gas discharge and other factors.

One way to reduce noise is to absorb sound through sound-absorbing materials (glass wool, foam plastic, microporous sound-absorbing brick, etc.). ), has a significant silencing effect on high-frequency noise; The other is interference, which changes the direction of sound propagation and is more effective for low-frequency noise. At present, there are * or silencing pits at the gas discharge port. For screw compressors, the suction and exhaust ports are also equipped with *.

In order to reduce the noise intensity of the operation site, the pipeline of the turbine air compressor can be covered with sound insulation material, or the whole compressor can be covered with sound insulation cover, or the sound insulation operation control room of the air compressor can be set up separately, and the operation situation can be observed through double glass, and the machine room can be inspected regularly.

9. How to rescue a fire in an oxygen workshop?

A: There are many causes of fire, such as oil fire and electrical equipment fire. There are a lot of combustion-supporting materials (oxygen and liquid oxygen) in the oxygen workshop, which is dangerous. Fire extinguisher, sand, water, nitrogen, etc. It's used to put out fires. Different fire modes should use different fire extinguishing equipment. First of all, we should distinguish the objects and don't use them casually to avoid danger.

When the density is less than that of water and the water-insoluble liquid or oil catches fire, the fire area will be further expanded if water is used to extinguish the fire. Use sand, steam or foam extinguisher to put out the fire, or cut off the air to put out the fire.

When electrical equipment is on fire, carbon tetrachloride fire extinguisher should be used instead of foam extinguisher and water. Because water and foam are conductive, it is likely to cause firefighters to get an electric shock. When the wire is on fire, cut off the power first, and then put it out with sand.

Generally speaking, when a solid catches fire, sand or water can be used to put out the fire.

When the oxygen pipeline is on fire, the gas source must be cut off first.

If the clothes are on fire, don't fight. You should wrap yourself in a fire blanket and roll back and forth on the ground.

In the dangerous parts of the workshop, some nitrogen cylinders or nitrogen pipes can be prepared in advance for fire fighting.

10. What should I pay attention to when touching electrical equipment?

Answer: When using electrical equipment, the main dangers are electric shock and electric injury. The so-called electric shock means that when the current passes through the human body, the whole body will be hurt; Only when the human body is partially injured is it called electric injury. The most dangerous thing is electric shock.

The harm of electric current to people is: burning human body, destroying body tissues, electrolyzing blood and other organic substances, and stimulating nervous system.

The harm degree of current to human body is related to the intensity of current passing through human body, the action time and the situation of human body itself. Facts have proved that the current passing through the human body will be dangerous when it is above 0.05A; More than 0. 1A can be fatal. The longer you get an electric shock, the greater the danger. If the current when getting an electric shock is 0.0 15A, people will not easily leave the power supply.

The human body has certain resistance, especially the skin. The resistance per 1cm2 on the contact surface is about 1000 ~ 1800000ω. When the skin is wet, the resistance will drop obviously. The smaller the resistance, the greater the current flowing at a certain voltage, and the greater the danger. Generally speaking, the voltage is below 45V, and the current is safe even if it passes through the human body.

Therefore, safe voltage (such as safety lights) should be below 45V.

The main causes of electric shock accidents are:

1) Work on damaged equipment (such as motors, wires and electrical switches);

2) Contact with live bare wires or damaged wires;

3) No grounding device or poor grounding device;

4) Lack of necessary protective equipment.

In the safe use of electrical equipment, besides strictly implementing the safety technical regulations, the following basic safety knowledge should also be paid attention to:

1) The external insulation of the line is damaged, so it shall not be used and must be insulated;

2) Always check whether the grounding device of each electrical equipment is disconnected;

3) Push and pull the electrical switch quickly, keep your face out of the way and wear necessary protective equipment;

4) When checking the temperature of the motor casing, it is advisable to touch the casing with the back of your hand, not with your palm, so as to avoid being attracted by electricity and unable to separate;

5) Personnel unfamiliar with electrical equipment shall not touch or repair the equipment without authorization;

6) When cleaning electrical equipment, don't rinse it with water or wipe it with a wet cloth;

7) Rubber insulation board with a thickness of 10mm should be placed before the electrical switch.

1 1. Oxygen workers are required to wear cotton work clothes.