Audio scheme of acetylene generator

Operators must be specially trained, familiar with the structure and working principle of acetylene generator, and pass the safety technical examination.

2. Layout principle of acetylene generator

The mobile acetylene generator can be placed outdoors or in a well-ventilated room.

. It is strictly forbidden to be placed in forging, casting, heat treatment workshops and operating boiler rooms. The fixed acetylene generator should be arranged in a separate room or special shed. The acetylene generator should not be arranged under the high-voltage lines and sliding lines of hoisting machinery, or near the air compressor, the suction port of the ventilator, the grounding conductor of the lightning rod, or where fireworks and falling objects may fly (such as chimneys and aerial work points). The acetylene generator shall keep a horizontal distance of 10 meter or more from open flames, flying sparks, high-voltage wires and other heat sources. It is not allowed to be placed on the workbench and equipment with severe vibration. When using mobile acetylene generator in summer, it is forbidden to expose to the sun.

3. Preparation before use

First, check the safety devices of the generator (anti-flashback device, safety valve, pressure relief membrane, pressure gauge, water level gauge and thermometer, pipes, valves, operating mechanism, etc.). ) In good condition, water and calcium carbide can be added after it is confirmed to be normal. Acetylene generator must have no water seal safety device that meets the requirements, otherwise it is prohibited to use. The floating acetylene generator should be equipped with rubber enzyme membrane, and the water tongs should be equipped with blades. The floating acetylene generator can pierce the diaphragm when it explodes, and it is not allowed to press the generator air chamber with heavy objects. All parts where acetylene generator may explode (such as gas generating room, backfire-proof aluminum and gas storage room, etc.). ) should be equipped with aluminum foil pressure relief membrane, the thickness of the membrane is 0. 15 ~ 6.20 mm, and the aluminum foil should be engraved with knife marks or flowers to ensure reliable rupture during blasting. Irrigation must be filled with sufficient water according to regulations, with good water quality and clean water without oil pollution or other impurities. Calcium carbide should be fed quantitatively according to the requirements of various generators, not too full. Prevent calcium carbide from decomposing into mature lime, which will increase in volume (more than double), block the water inlet pipe, gas transmission pipe and interlayer, and increase the acetylene pressure in the air where gas occurs. Or because of the overheating of calcium carbide combustion, the air chamber bursts or the calcium carbide tank cannot be pulled out. The particle size of calcium carbide must meet the specifications on the generator. Generally, the particle size of calcium carbide for mobile generators should be within the range of 25 ~ 80 mm, and the particle size of calcium carbide for large calcium carbide acetylene generators should also be within the range of 8 ~ 0 mm, and the particle size of calcium carbide for 2 ~ 8 mm should not exceed 30%. Calcium carbide larger than 80mm should not be used. It is forbidden to use calcium carbide with particle size less than 2mm for generators with general structure. If the generator freezes in winter, it can only be thawed with hot water or steam. It is forbidden to bake with naked fire, electric welding or red-hot iron sheets, and it is not allowed to knock with objects that are easy to generate sparks, such as iron sheets.

4. Start of acetylene generator

Before distributing the money, check the water level of the backfire prevention device. After everything is normal, the inlet valve can be opened to transport calcium carbide water, or the contact between calcium carbide blue and water can be reduced by the joystick to produce acetylene. At this time, check whether the pressure gauge, connector and safety valve are normal. After starting, the pressure gauge reading may rise too fast, even gas escapes from the safety valve, or the pressure gauge indication remains in the military position after starting. All these indicate that the generator is not working normally, so gas production must be stopped immediately, and it can only be restarted after checking and eliminating the old problems. When starting in winter, the medium-voltage mobile generator sometimes starts for a few minutes, but the pointer of the pressure gauge remains motionless. You can observe it for a few minutes and then judge the treatment according to the situation.

5, management and maintenance in the process of work

Before using the gas source, the mixture of acetylene and air in the generator should be discharged. During operation, all parts of the generator should be checked at any time. Once it is found that there is air leakage, the water level does not meet the requirements or the safety device fails, measures should be taken in time to solve it, otherwise it is not allowed to be used. When checking air leakage, use fatty water, and do not use naked flame. Cleaning calcium carbide slag in operation must be carried out after calcium carbide is completely decomposed. If water is found to overflow from the discharge door of the air chamber, and the pressure gauge does not move, it means that the calcium carbide has been completely decomposed and can be cleaned. When the water temperature in the generator exceeds 70℃, it should be flushed, or temporarily stop working and take cooling measures to reduce the temperature. Don't turn on the generator or drain water casually, in case of fire and explosion caused by overheating of calcium carbide. The water seal safety device of acetylene generator must be vertical to the ground. Before starting work, you must check the water seal safety device to ensure that there is no air leakage and freezing, and then inject clean water, the water level of which can melt until water slowly flows out or drips out of the valve. When stopping gas transmission, water injection and water level inspection must be carried out. When the workload is small, check the water simulation of the control valve at least twice per train and once after each fire. If the water level drops, water must be added, but the water level must not be higher than the control valve, so as to avoid acetylene passing through the water seal safety device and damaging the normal work of the welding torch. When stopping the supply of acetylene, the air inlet valve of the water seal safety device must be closed regardless of whether the valve of the welding torch is closed. When welding in cold weather, the shell of water seal protector can be wrapped with felt, or sodium chloride or chlorinated water solution can be used. The lower end of acetylene conduit of low-pressure water seal safety device should be lower than the lower end of safety tube to avoid tempering. The explosion gas should be discharged into the atmosphere through the safety pipe to avoid invading the acetylene generator. The acetylene pipeline in the factory should be equipped with a film safety door, which should be installed in a safe and reliable place to prevent personal injury and fire. The pipeline from the valve should be inspected daily to ensure no leakage. Don't use fire on the acetylene pipeline system that hasn't been blown clean. After each work, remove the hose. When there is a fire in the acetylene station, the power supply of the fire site should be cut off quickly, and all valves on the process pipeline and acetylene cylinder should be closed. Put out the fire with dry powder or carbon dioxide fire extinguisher.

6, stop using cleaning work

When the generator stops, the calcium carbide basket should be lifted off the water surface, or the water inlet valve should be closed to prevent calcium carbide from producing gas. Then close the valve of the gas outlet pipe and stop the acetylene output. When opening the calcium carbide basket, if flame is found, cover the generator immediately. Isolate it from the air, immediately lift the calcium carbide basket out of the water, and then open the cover for drainage after cooling. It is forbidden to drain water immediately after closing the lid. When the temperature of the decomposition chamber drops below 50℃, the acetylene generator with "water supply from water pipe" can be used for cleaning. The removed lime slurry shall be sent to the waste pit. After the winter operation is completed, all the water conservancy and electric lace of the generator water tank should be discharged and washed clean to avoid freezing.

In this paragraph, the technical requirements for manufacturing safety of acetylene generator have been revised.

1, the structure of the generator should ensure that all the gas in the generator can be released, so that the remaining air can be blown clean before reloading calcium carbide. 2. Necessary and qualified installation devices shall be installed. The safety device includes flame-retardant gastric load, explosion-proof pressure relief device and indicating device. The installation parts of safety devices shall meet the requirements. The basic technical requirements of the backfire prevention device (flame arrester) are as follows: (1) It can reliably prevent the spread of flame and explosion wave. And can discharge explosive mixture into the atmosphere; (2) There should be a pressure relief device which should meet the technical requirements; (3) It can meet the requirements of welding process, such as not affecting the flame temperature and gas flow; ④ Easy to check, control, clean and maintain; ⑤ It is best to cut off the gas source when tempering; ⑥ The working pressure of the backfire prevention device should be compatible with that of the acetylene generator; ⑦ Anti-flashback devices have various structural forms, and the water-sealed anti-flashback device has good safety performance and the widest application. The installation position and technical performance of explosion-proof and pressure-relief devices shall meet the requirements of specifications. When the generator pressure rises and exceeds the protection setting value, it should be able to work reliably in time, vent the gas in the mountain device, reduce the pressure and prevent the generator oil tank from cracking. Explosion-proof and decompression devices include safety valves and decompression membranes. Indicating devices include pressure gauges, thermometers and water level gauges. These devices should be sensitive and accurate. 3. Ensure good cooling conditions. The generator must have enough cooling water, and calcium carbide should be decomposed in a large amount of water as much as possible according to the conditions. In the calcium carbide decomposition area, the temperature of water shall not exceed 60℃. The output cooking temperature of the gas generation chamber shall meet the following requirements: dripping, draining or leaching: the gas generation temperature shall be higher than 90℃. The temperature of acetylene output by the generator shall not be higher than 40℃. For the mobile acetylene generator, when the ambient temperature exceeds 30℃, the acetylene temperature output by the acetylene generator is allowed to be 65438 00℃ higher than the ambient air temperature. 4. The structure of the generator and its moving parts should not generate sparks due to collision and friction at work. 5, acetylene generator parts are not allowed to use pure copper (copper), so as not to produce acetylene copper and dangerous, can use the alloy containing copper below 70%. Acetylene adds calcium carbide into the generator to react with water to generate acetylene gas, because impurities in industrial calcium carbide react with water at the same time to generate corresponding impurities such as PH3 and H2S. Main reaction: cac2+2h2o → c2h2+ca (oh) 2+127.2kj/mol; side reaction: Cao+H2O → ca (oh) 2+62.76kj/mol cas+2h2o → ca (oh) 2+H2S = ca3p2+6H2O → 3ca (. 2+2ph3 = ca3n2+6h2o → 3ca (oh) 2+2nh3 = ca2si+4h2o → 3ca (oh) 2+sih4 = ca3as2+6h2o → main reaction Therefore, crude acetylene contains more PH3 (hundreds of ppm) and less H2S (tens of ppm), and phosphide can also be P2H4. When the temperature is about 85℃, there may be the following reactions: adding bimolecular acetylene to produce CH2 = CH-C ≡ CH (vinyl acetylene) and C2H5-S-C2H5 (diethyl sulfide), the content of which can reach 50- 100 ppm. When the temperature is 85℃, crude acetylene contains a lot of water vapor due to the evaporation of water. (General water vapor: acetylene = 1: 1).

Edit the influencing factors in this paragraph.

(1) Quality, particle size and residence time of calcium carbide

Hydrolysis is a liquid-solid reaction. Calcium carbide has good quality and high gas production. The larger the contact area between calcium carbide and water, the faster the hydrolysis reaction. In actual production, considering the complete hydrolysis and safety, combining the generator structure and calcium carbide crushing, the particle size of calcium carbide is controlled at 15-50 mm, so that high-quality calcium carbide can be used together with calcium carbide with equal degree. Particle size of calcium carbide mm 2-4 5-8 5-1515-25 25-50 50-80

1Kg calcium carbide complete hydrolysis time (minutes)1.171.651.824.2313.616.57

Generally, the residence time of calcium carbide in the five-layer tray generator must be greater than 13 minutes.

(2) reaction temperature

The reaction heat of calcium carbide hydrolysis is removed by adding excessive water. The reaction temperature can be controlled by adjusting the amount of water and calcium carbide. With the increase of reaction temperature, the hydrolysis speed is accelerated, and the solubility of acetylene in carbide slag slurry is reduced, which significantly reduces the consumption of calcium carbide. However, if the reaction temperature is too high, the solid content of carbide slag slurry will be large, which will lead to poor overflow or difficult slag discharge. When the reaction temperature is high, the content of water vapor in crude acetylene increases, and slag slurry is entrained, resulting in overload of the rear cooling tower and blockage of pipelines or trays. Based on the above considerations, the reaction temperature is generally controlled at 80-90℃.

Edit the explosion-proof technical measures of acetylene generator in this paragraph.

(1) Danger of acetylene combustion and explosion (1) Pressure and temperature. The spontaneous combustion point of acetylene is 335℃, which is easy to be heated and spontaneously ignited. At 200-300℃, acetylene molecules begin to undergo exothermic polymerization. When the temperature is higher than 500℃, acetylene will explode. If it is decomposed in a closed container, it will explode due to the increase of temperature and pressure. The following figure shows the effects of temperature and pressure on the polymerization and explosive decomposition of acetylene. ② oxidant. Acetylene is mixed with air to form explosive mixed gas, the explosion limit is 2.2-8 1%, and the spontaneous combustion point is 305℃. When mixed with oxygen, the explosion limit is 2.8-93% and the spontaneous combustion point is 300℃. When mixed with fluorine gas, it will explode in the sun or under heating. Acetylene can also combine with fluorine and bromine. , causing combustion and explosion. ③ impurities. Acetylene usually contains phosphine, hydrogen sulfide and other harmful impurities. Phosphine has a low spontaneous combustion point and will spontaneously ignite the mixed gas of acetylene and air at 45-60℃. ④ Catalyst. Catalysts such as iron oxide, copper oxide and alumina can adsorb acetylene molecules on their porous surfaces, increase the concentration of acetylene, and promote the polymerization and explosive decomposition of acetylene molecules. ⑤ Container volume. The smaller the container, the less likely it is to explode; On the contrary, the greater the risk of explosion. In addition, due to the low ignition energy of acetylene (0.0 19mJ), it will form explosive mixture when contacting with other metals. (2) Danger of combustion and explosion of calcium carbide Calcium carbide, commonly known as calcium carbide, has no nature of combustion and explosion. The main hazards of combustion and explosion are: ① Combustion and explosion in contact with water. Calcium carbide decomposes immediately when it meets fire, producing acetylene and releasing a lot of heat, which can lead to acetylene fire and explosion. ② calcium carbide sparks. Calcium carbide generally contains ferrosilicon impurities, which can generate sparks when colliding or rubbing and become the explosion source of acetylene; Calcium phosphide impurities contained in calcium carbide react with water to generate phosphine gas, which has a low natural point and is easy to cause the explosive mixture in the generator to explode. ③ Particle size of calcium carbide. The smaller the particle size of calcium carbide, the faster it decomposes when it reacts with water, and the more heat it releases instantly, which is easy to cause local overheating and produce danger, as shown in the following table. (3) As explosion-proof technical measures for acetylene (1), fire prevention measures. When the combustion speed of the flame is higher than the airflow speed of the mixture of acetylene and oxygen, the gas welding (cutting) flame will burn to the rubber hose along the welding (cutting) torch, which is very dangerous. Therefore, a flame arrester should be installed, which is usually used as a backfire preventer to prevent the flame from escaping into the gas storage tank and the main tank or spreading in the pipeline. According to different pressures, flashback prevention devices are divided into low-pressure type (< < 0.07MPA= =) and medium-pressure type (0.07-0. 15 MPa). According to the structure, it can be divided into two types: open and closed; According to the flame retardant medium, it can be divided into water-sealed type and dry type. ② Pressure relief measures. Pressure relief means that when the pressure of the generator rises beyond a certain limit, or when the explosion produces pressure, it can be released in time to prevent the generator from breaking. Commonly used pressure relief devices are safety valves and bursting discs. A safety valve. Also known as the pressure relief valve, its function is to ensure that the acetylene generator can automatically open when the pressure exceeds the safe pressure (0.2 15MPa) and release some gas; When the pressure drops to a safe range, it will automatically shut down to ensure that the generator will not be damaged by overpressure. In order to ensure the sensitivity and reliability of the safety valve, the exhaust test should be carried out regularly to prevent the exhaust pipe and valve body from being stuck and blocked. In addition, the safety valve should be regularly checked for air leakage or poor exhaust and repaired in time. B bursting disc. The explosion-proof sheet for generator is made of aluminum foil and rubber sheet. In contrast, aluminum foil is ideal. The bursting disc should have moderate strength to withstand working pressure (generally below 0. 15MPa): good heat resistance and corrosion resistance; At the same time, it should be brittle; Easily broken; The thickness should be as thin as possible. For storage tanks with a volume of more than 300L, the selection of explosion relief area should be determined by blasting test. The bursting discs shall be made of specified materials and specifications, and shall not be replaced at will. ③ Monitoring measures. The monitoring function is to control the pressure of acetylene, the temperature and quantity of water and acetylene, etc. For stationary acetylene generators, all the above parameters must be monitored; For small-capacity mobile generators, it is not necessary to monitor the temperature. Pressure monitoring. The medium-pressure acetylene generator must be equipped with a pressure gauge to directly display the acetylene pressure in the tank. In order to keep the pressure gauge sensitive and accurate, attention should be paid to maintenance and overhaul during use. Pressure gauges should be kept clean. If the dial glass is broken or the scale is blurred, it should be stopped. The connecting pipe of pressure gauge should be purged regularly to prevent blockage. Always check whether the pointer returns to zero normally after rotation. Pressure gauges must be inspected regularly, and pressure gauges that exceed the validity period should stop working. B water level control. The water level can be indicated by a water level gauge or a water level tap. Water should be added to each water tank of the generator according to the mark of the water level gauge or the water level indicated by the faucet. The indicating scale of the water level gauge should be clear and easy to see, and the water level tap should not be corroded. C temperature monitoring. Alcohol thermometer is used to measure the temperature of acetylene and the water temperature in the electrolytic decomposition area of the generator. Mercury thermometer is prohibited. The glass protection tube of thermometer should be scrubbed frequently to make the scale of thermometer clear. ④ Arrangement of acetylene generator. A it is forbidden to place mobile generators in hot working workshops such as forging, casting and heat treatment, and in operating boiler rooms. B the fixed generator should be arranged in a separate room, and there should be a special shed when it is placed outdoors. C the horizontal distance between acetylene generator and naked flame, spark point, high-voltage power line and other heat sources should be kept above 10m, and it is not allowed to be placed on working platforms and equipment with violent vibration. ⑤ Preparation before using acetylene. A. Check whether the safety device of the generator is complete and its working performance is normal. B irrigate according to the specified amount of water. C should be according to the requirements of various generators quantitative calcium carbide, shall not be too full. D if the generator is found to be frozen in winter, it can only be thawed with hot water or steam. It is forbidden to bake with open flame or red iron, and it is forbidden to use objects that are easy to generate sparks such as iron. ⑥ The use of acetylene generator. Before starting the A generator, check the water level of the backfire prevention device. After everything is normal, open the water supply valve to supply water to calcium carbide. B. After water supply, check whether the pressure gauges, safety valves and joints are normal. C. After starting, if the pressure gauge reading rises too fast, or gas escapes from the safety valve, or the pressure gauge pointer still stops at zero, stop the gas immediately. After troubleshooting, you can restart. ⑦ Explosion-proof during work. A before using the gas source, the mixture of acetylene and air stored in the generator should be preserved. B during this process, all parts of the generator should be checked at any time. Once air leakage, water level discrepancy or safety device failure are found, measures should be taken in time. C carbide slag must be removed after carbide is safely decomposed during operation. D. When the water temperature in the generator exceeds 80℃, cold water should be injected or work should be stopped temporarily, and cooling measures should be taken to cool it down. E. Don't turn on the generator and drain water casually, in case of fire and explosion caused by overheating of calcium carbide.