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29

2019-09

Working principle of nitrogen making machine

PSA pressure swing adsorption nitrogen production mechanism nitrogen principle Carbon molecular sieve can absorb oxygen and nitrogen in the air at the same time, and its adsorption capacity also increases with the increase of pressure, and at the same pressure oxygen and nitrogen equilibrium adsorption capacity has no obvious difference. Therefore, it is difficult to complete the effective separation of oxygen and nitrogen only by the change of pressure. If further consideration is given to adsorption rates, the adsorption properties of oxygen and nitrogen can be effectively distinguished. The diameter of oxygen molecules is smaller than that of nitrogen molecules, so the diffusion rate is hundreds of times faster than that of nitrogen, so the speed of carbon molecular sieve adsorption of oxygen is also very fast, adsorption of about 1 minutes to reach more than 90%; At this time, the amount of nitrogen adsorption is only about 5%, so the adsorption is mostly oxygen, and the rest is mostly nitrogen. In this way, if the adsorption time is controlled within 1 minute, you can initially separate oxygen and nitrogen, that is to say, adsorption and desorption are achieved by pressure difference, when the pressure increases adsorption, desorption when the pressure drops. The distinction between oxygen and nitrogen is based on the adsorption speed difference between the two, through the control of adsorption time to achieve, the time control is very short, oxygen has been fully adsorbed, and nitrogen has not yet had time to adsorption, stopped the adsorption process. Therefore, pressure change and time control for nitrogen production by pressure swing adsorption should be within 1 minute.

29

2019-09

Air compressor terminology and related knowledge

(1), pressure: the pressure referred to in the compressor industry refers to pressure (P) Ⅰ, standard atmospheric pressure (ATM) Ⅱ, working pressure, suction, exhaust pressure, refers to the air compressor suction, exhaust pressure ① The pressure measured with atmospheric pressure as the zero point is called surface pressure P(G). ② The pressure with absolute vacuum as the zero point is called the absolute pressure P(A). The exhaust pressure usually given on the compressor nameplate is the gauge pressure. Ⅲ, differential pressure, pressure difference Ⅳ, loss of pressure: pressure loss Ⅴ, air compressor, the commonly used pressure unit conversion: 1MPa (MPa) =106Pa (PASCAL) 1bar (bar) =0.1MPa 1atm (standard atmospheric pressure) =1.013bar=0.1013MPa Usually in the air compressor industry, "kg" refers to "bar". (2), nominal flow: nominal flow in China is also known as the displacement or nameplate flow. Generally speaking, under the required exhaust pressure, the gas volume discharged by the air compressor per unit time is converted to the intake state, which is the volume value of the suction pressure and suction temperature and humidity at the first stage of the intake pipe. Unit time refers to one minute. That is, the suction volume Q= CM *λ*D3*N=L/D*D3N L: Length of rotor D: Diameter of the rotor N: The shaft speed of the rotor CM: Coefficient of profile line Lambda: length to diameter ratio According to the national standard, the actual exhaust volume of air compressor is ± 5% of the nominal flow. Reference state: a standard atmospheric pressure, temperature 20℃, humidity is 0℃, this reference state in the United States, Britain, Australia and other English-speaking countries T =15℃. Europe and Japan T =0℃. Standard condition: one standard atmosphere, temperature 0℃, humidity 0 If converted to base state, the unit is :m3/min (cubic per minute) If converted to standard state, the unit is :Nm3/min (standard square per minute) After 1 m/min = 1000 l/min 1 nm after/min after = 1.07 m/min (3) Oil content of gas: Ⅰ, per unit volume of compressed air in the oil (including oil, suspended particles and oil steam), the quality of the conversion to off the pressure of 0.1 MPa, temperature is 20 ℃ and relative humidity of 65% the value of the standard atmospheric conditions. Unit :mg/m3 (refers to absolute pair value) Ⅱ, PPM said a trace substances content in the mixture of symbols, refers to the number in every one million hundreds million (weight than PPMw and volume than PPMv). (referring to the ratio) Usually we refer to PPM as the weight ratio. (One millionth of a kilogram is a milligram) 1PPMW =1.2mg/m3(Pa =0.1MPa, t=20℃, φ=65%) (4) Specific power: refers to the power consumed by a certain volume flow of the compressor. It is a kind of index to evaluate the compressor performance under the same gas compression and the same exhaust pressure. Specific power = shaft power (total input power)/ exhaust (kW/m3·min-1) Shaft power: The power required to drive the shaft of the compressor. P axis =√3×U×I× COS φ(9.5)×η(98%) motor ×η drive (5), electrical and other terms Ⅰ, power: current per unit time to do the work (P), the unit is W (watt We usually use kW (kilowatt), but also horsepower (HP) 1 KW HP1HP = 1.34102 = 0.7357 KW Ⅱ, current: electronic under the action of electric field force, there are rules of move in one direction When it moves, it forms A current in A amperes. Ⅲ, voltage: just because have head and water flow, there is also a potential difference, It is called voltage (U), and the unit is V (volts). Ⅳ, phase, refers to the wire, three phase four wire: refers to the three phase thread (or wire) The center line (or zero line), single phase refers to a phase line (or fire line) Root center line (or zero line) Ⅴ, frequency: alternating current (ac) to complete the electromotive force of the positive and negative transformation cycles a second number, use (f), according to the unit - Hertz (Hz) of 50 Hz alternating current frequency in our country, abroad is 60 Hz. Ⅵ, frequency: change the frequency, in air compressor application, by changing the frequency of the power to change the speed of the motor, so as to achieve the purpose of flow adjustment. The flow rate can be adjusted to 0.1bar by frequency conversion, which greatly reduces idle work and achieves the purpose of energy saving. Ⅶ, controller: there are two main types of controller in industry: instrument type and PL System, we use PLC controller, is a kind of by A programmable controller composed of single chip microcomputer and other components. Ⅷ, straight league: direct connection, in t

29

2019-09

Air compressor room size design matters needing attention

A lot of air compressor users ignore the importance of the design of air compressor room. They think that the air compressor is installed there as long as it is not in the way. But in the late stage, they have learned the bitter fruit of unreasonable design of air compressor room. In summer, air compressor room heat dissipation is not good, and high temperature of air compressor frequently occurs; Air compressor maintenance is not convenient; The construction of waste heat recovery engineer of air compressor is not convenient, so we should ensure that the design of air compressor in the air compressor room is reasonable. If you are an engineer, what will you remind your users to pay attention to in the design of air compressor room? 1. Before the design of air compressor room, it is necessary to understand the design specification and matters needing attention of air compressor room. 2. Choose a place with low relative humidity, less dust, clean air and good ventilation. If the ambient temperature is too high (greater than 45℃), it is recommended to take cooling measures (such as avoiding direct sunlight, opening doors and Windows, etc.) to avoid unnecessary high-temperature shutdown; If the ambient temperature is low (less than 0℃), the freezing point temperature of the lubricating oil must be controlled above the ambient temperature. Consider not only summer low temperatures, but also winter low temperatures, and think long term. 3. If the factory environment is poor and dusty, a ventilation duct should be installed to lead the intake end to a place where the air is relatively clean. The installation of the conduit must be easy to disassemble and assemble for maintenance. The installation size should refer to the external size of the air compressor. 4. There must be enough space around the air compressor for other parts to enter and leave. There must be at least a distance of more than 1500mm between the air compressor and the wall. As far as possible with lifting equipment. The distance between the air compressor and the top space is more than 1500mm. In a word, the design of air compressor room should come from the gas demand that you want to meet, and can not be strictly in accordance with the book knowledge. But the basic matters needing attention should be understood and applied to the actual design of the air compressor room.

10

2019-06

The operation of argon production in air separation unit is complicated.

Total rectification of argon is to separate oxygen from argon in a crude argon column to obtain crude argon with oxygen content less than 1×10-6 directly, and then separate it from fine argon to obtain fine argon with purity of 99.999%.   With the rapid development of air separation technology and the demand of market, more and more air separation units adopt the process of producing argon without hydrogen to produce high purity argon products. However, due to the complexity of argon production operation, many air separation units with argon did not lift argon, and some units in operation of argon system were not satisfactory due to the fluctuation of oxygen use condition and the limitation of operation level. Through the following simple steps, the operator can have a basic understanding of producing argon without hydrogen!   Commissioning of argon making system   * V766 in full opening process before discharging coarse argon column into fine argon column; Liquid blowout and discharge valves V753 and 754 at the bottom of crude argon tower I (24 ~ 36 hours). * Full opening process argon out coarse argon tower I defining argon tower valve V6; Non-condensing gas discharge valve V760 at the top of the argon tower; Precision argon tower, liquid blowing at the bottom of precision argon measuring cylinder, discharge valves V756 and V755 (precooling precision argon tower can be carried out at the same time as precooling coarse argon tower).   Check the argon pump   * Electronic control system -- wiring, control and display are correct; * Sealing gas -- whether the pressure, flow, pipeline is correct and does not leak; * Motor rotation direction -- point motor, confirm the correct rotation direction; * Piping before and after the pump -- check to make sure the piping system is smooth.   Check the argon system instrument thoroughly   (1) Rough argon tower I, Rough argon tower II resistance (+) (-) pressure tube, transmitter and display instrument is correct; (2) Whether all liquid level gauge (+) (-) pressure tube, transmitter and display instrument in argon system are correct; (3) Whether the pressure tube, transmitter and display instrument are correct at all pressure points; (4) Whether the argon flow rate FI-701 (the orifice plate is in the cold box) (+) (-) pressure tube, transmitter and display instrument are correct; ⑤ Check whether all automatic valves and their adjustment and interlocking are correct.   Main tower working condition adjustment   * Increase oxygen production under the premise of ensuring oxygen purity; * Control the lower column oxygen-rich liquid empty 36 ~ 38% (liquid nitrogen restricts into the upper column valve V2); * Reduce the expansion amount under the premise of ensuring the main cold liquid level.   Liquid in coarse argon column   * On the premise of further precooling until the temperature of the argon tower no longer drops (the blowout and discharge valves have been closed), the liquid air is slightly opened (intermittently) and flows into the condensing evaporator valve V3 of the crude argon tower I to make the condenser of the crude argon tower intermittently work to produce backflow liquid, cool the packing of the crude argon tower I thoroughly and accumulate in the bottom part of the tower; Tip: When opening the V3 valve for the first time, pay close attention to the pressure change of PI-701 and do not fluctuate violently (≤ 60kPa); Obact the liquid level LIC-701 at the bottom of crude argon tower I from scratch. Once it rises to 1500mm ~ full scale range, stop precooling and close V3 valve.   Precooling argon pump   * Stop valve before opening the pump; * Blow out the valve V741 and V742 before opening the pump; * slightly open (intermittently) the pump after blowing off valve V737, V738 until the liquid is continuously ejected. Tip: This work is carried out under the guidance of argon pump supplier for the first time. Safety issues to prevent frostbite.   Start the argon pump   * Fully open the return valve after the pump, fully close the stop valve after the pump; * Start argon pump and fully open the back stop valve of argon pump; * Observe that the pump pressure should be stabilized at 0.5 ~ 0.7Mpa(G).   Crude argon column   (1) After starting the argon pump and before opening the V3 valve, the liquid level of LIX-701 will decrease continuously due to the liquid loss. After starting the argon pump, the V3 valve should be opened as soon as possible to make the condenser of the argon tower work and produce backflow liquid. (2) V3 valve opening must be very slow, otherwise the main tower conditions will produce large fluctuations, affecting the purity of oxygen, crude argon tower after work to open the argon pump delivery valve (opening depends on the pump pressure), the final delivery valve and return valve to stabilize the FIC-701 liquid level; (3) The resistance of two crude argon columns is observed. The resistance of

12

2019-04

Compressed air filter replacement steps and matters needing attention

Compressed air filter use time is too long, will lead to too much internal impurities, affect the gas flow rate, pressure, filtration effect; Therefore, the replacement of compressed air filters needs to be carried out regularly. The general replacement cycle is 1 year. If the user uses the environment well, it can be appropriate for a long time. If the environment is bad, it may need to be replaced in about 8 months. Compressed air filter element replacement steps: 1. Confirm that the air pressure system has stopped running; 2. Prepare suitable filter elements (specifications, material, size, O-ring material, model, etc.), disassembly tools, collection barrels, rags, etc.; 3. Disconnect the filter element that needs to be replaced from the system. Slowly open the exhaust port at the top of the filter to relieve pressure, pay attention to safety during the process to prevent splashing of materials or liquids; 4. Empty the material in the filter, open the upper cover of the filter with a tool, take out the filter element, and install the filter element with a plastic bag to be scrapped; 5. Clean the inside of the filter with a rag; 7, check the O-ring for damage, aging and other problems; 8. The material inflow is installed according to the method of inflow from the outside of the filter element and outflow from inside the filter element. 9. Hold the filter element near one end of the O-ring, insert the filter element socket into the filter element socket vertically, insert the filter element, then install the upper cover of the filter, and tighten the filter with a tool; In the process of replacing the filter element, sealing and cleaning are the most critical work, so in the process of O ring, screw, cover, etc., we should be especially careful.

12

2019-04

Function of refrigerated dryer in air compressor

Xiaobian will briefly share with you the role of freeze dryer in air compressor. Take a look! Advantages: 1, no compressed air consumption, most users of compressed air dew point requirements are not very high, the use of freeze dryer than the use of adsorption dryer to save energy; 2, do not need to regularly add, replace the adsorbent; 3. Low running noise; The adsorption dryer has the noise of pressure relief of the adsorption tower. In the air pressure room, the operation noise of the freeze dryer is generally not heard. 4, no valve parts wear; 5, the daily maintenance is simple, as long as the automatic drain filter can be cleaned on time; 6. There is no special requirement for the pre-pretreatment of air source and supporting air compressor. The general oil-water separator can meet the requirements of the intake air quality of the refrigerated dryer. 7. The refrigerated dryer has a "self-cleaning" effect on the exhaust gas, that is, the content of solid impurities in the discharged gas is less; 8. While discharging the condensate, part of the oil vapor can also be condensed into liquid oil mist and discharged with the condensate.

12

2019-04

Must the dryer be installed behind the air compressor?

Must the dryer be installed in the air compressor post-treatment equipment? The answer is yes, if your enterprise is useful to the air compressor, you must know that the air compressor must be installed after the dryer. After the air compressor, the air storage tank, filter and dryer and other purification equipment need to be installed. It is well known that when the air around us is compressed, the amount of water molecules per unit volume rises dramatically. The compression process results in air containing not only liquid water, oil, and particulate matter, but also large amounts of saturated water molecules. Once the external temperature drops, the saturated water molecules are affected by the low temperature and precipitate liquid water. The lower the temperature, the more liquid water precipitates. When the temperature drops to zero, the liquid water condenses into ice, resulting in ice blockage. And the compressed air containing too much water molecules will also affect the normal operation of the equipment, corrosion of machinery and equipment, causing damage to pneumatic components and so on. Some people may ask, to remove the water molecules in compressed air, you can directly use a filter to remove it, why buy a large price dryer? Why is that? This is because the filter can only remove liquid water in the compressed air, but the water molecules in the compressed air will continue to precipitate liquid water with the lower the temperature. In addition to liquid water, the water molecules in the compressed air will also affect the life of machinery and equipment and the production process of enterprises. Purchase dryer, can dry the water molecules in the compressed air, so that the compressed air can meet the gas standards of the enterprise, so as to meet the production needs of the enterprise. Investment in air compressor post-treatment equipment dryer return is very high, it effectively reduces the water molecules in the air, avoids the damage of machinery and equipment and gas equipment, can improve the production process of enterprises, reduce the product defect rate, and ensure the quality of products.

10

2019-12

Shocking air separation device explosion accident inventory, explosion cause analysis and control measures

Explosion accident of air separation unit at home and abroad On January 4, 1961, an air separation tower of a 4000m3/h air separation equipment in the former Federal Republic of Germany exploded, killing 15 people and seriously damaging the equipment and buildings. On November 23, 1973, the typical malignant explosion of the 3350m3/h air separation unit in Anshan Iron and Steel Oxyoxygen Plant occurred outside the tower, which also caused the explosion of the air separation base inside the tower. The equipment was destroyed in many places, and the production was resumed after six months of maintenance. On July 27, 1986, the 3200m3/h air separation equipment of Qianjin Chemical Plant of Yanshan Petrochemical Company made a loud noise, and the whole equipment became a pile of ruins. On November 1, 1992, an explosion occurred in the 150m3/h air separation tower of the oxygen station of Lanzhou Petrochemical Machinery Plant, resulting in the death of one person and the abandonment of the air separation tower. On July 25, 1993, the main condensing evaporator of 150m3/h air separation tower of Jinchuan Nonferrous Metals Company in Gansu Province suffered a crushing explosion, which killed one person on the spot and scrapped the air separation tower. On March 2, 1996, the 6000m3/h air separation equipment in Xinyu Iron and Steel Plant of Jiangxi Province, under the condition that no abnormal symptoms were found, the plate fin main condensing evaporator suddenly exploded, and the equipment was seriously damaged. The blast wave shattered the glass of the surrounding buildings. On July 18, 1996, the main cooling of the 10000m3/h air separation equipment in the air separation branch of Harbin Gasification Plant exploded, and the main cooling and upper tower were scrapped. On May 16, 1997, a malignant explosion occurred in the 6000m3/h air separation tower of Fushun ethylene chemical plant in Liaoning Province. The equipment and plant were seriously damaged,4 people died,4 people were seriously injured and 27 people were slightly injured. On December 25, 1997, a set of 81760m3/h air separation equipment of Malaysia Bintulu Shell Oil Company suffered a malignant explosion. The explosion started in the main condensation evaporator and expanded to the tower body; The lower tower is pressed into the ground; The upper tower and the main cold were blown 750 meters away; Window frames shattered within 5km and flying metal smashed oil and kerosene tanks, sparking the fire. August 21, 2000, Jiangxi Pingxiang Iron and Steel Company oxygen plant 1500m3/h air separation unit maintenance site of an explosion accident, resulting in 22 deaths, 7 serious injuries, 17 minor injuries. On July 7, 2003, when the 10000m3/h air separation equipment of Shanghai Cosco Chemical Co., Ltd. was preparing to hoist the upper column and the upper section of the coarse argon column, there was a loud noise, and the two-layer plastic color strip on the upper seal of the lower section of the coarse argon column was torn to pieces by the air waves. On August 22, 2003, the 20,00m3 /h air separation equipment in the oxygen plant of Maanshan Iron and Steel Corporation deflagrate occurred during installation, and people were ejected and 35% burned. After rescue, they escaped from the emergency. On September 17, 2003, during the installation of the 10000m3/h air separation equipment of Lengshui Iron and Steel Company in Hunan, a blast of gas burst out, and the welder was knocked out and fell off the platform. He died in the rescue. On April 10, 2017, an air separation accident occurred in Shenhua with 4 million tons of coal-to-oil The explosion occurred at 5:45 PM on July 19, 2019, in the air separation unit C of the Yima Gasification Plant of Henan Energy and Chemical Group in Sanmenxia, Henan Province. The explosion resulted in 15 deaths, 15 serious injuries and 256 hospitalizations. In recent years, with the large-scale of air separation equipment, the explosive energy of air separation equipment is also increasing. From the principle of explosion, air separation equipment can be divided into physical explosion and chemical explosion. Chemical explosions cause more harm than physical explosions. Causes of physical explosion of air separation equipment are as follows: 1. A large amount of high temperature gas enters the fractionation tower containing cryogenic liquid, and the cryogenic liquid rapidly vaporizes, resulting in increased pressure in the fractionation tower, slow pressure relief speed of the safety valve, and deformation and rupture of the air separation tower. 2, air separation, cold box is memory is cryogenic liquid of fractionating column filled with thousands of cubic perlite insulation materials, fractionating column leakage fault occurs, will have a lot of cryogenic liquid, perlite in high temperature gas, cryogenic liquid evaporation sharply, the ratio of cold box burst, a large nu

29

2019-09

What is air separation? Air separation device and system process reveal

Everyone is familiar with all kinds of compressors and steam turbines, but do you really understand their role in air separation? An air separation workshop in a factory, do you know what it is like? Air separation, to put it simply, is used to separate the various components of the air gas, the production of oxygen, nitrogen and argon gas set of industrial equipment. There are also noble gases such as helium, neon, argon, krypton, xenon, radon, etc.

14

2019-06

Application of air separation unit in iron and steel industry (conventional blast furnace smelting and melting reduction process and calculation with oxygen)

A large number of industrial gases such as oxygen, nitrogen and argon are used in the smelting process of iron and steel enterprises. Oxygen is mainly used in blast furnace, melting reduction smelting furnace, converter, electric furnace smelting; Nitrogen is mainly used for furnace sealing, protective gas, steelmaking and refining, slag splashing in converter to protect furnace, security gas, heat transfer medium and system purging, etc. Argon gas is mainly used in steelmaking and refining. In order to meet the production requirements and ensure the safe and stable operation of production, large steel mills are equipped with special oxygen station and oxygen, nitrogen and argon power pipe network system. Large-scale full-process steel enterprises are currently equipped with conventional processes: coke oven, sintering, blast furnace steelmaking, converter electric furnace steelmaking, rolling process, etc. Due to the emphasis on environmental protection and simplification of process flow, the international iron and steel industry has developed a short process process before iron in modern times - melting reduction iron making, which directly reduces iron ore raw materials into molten iron in a smelting furnace. There is a big difference in the industrial gas required by the two different smelting processes. The oxygen required by conventional smelting blast furnace accounts for 28% of the total oxygen demand of the steel plant, and the oxygen required by steelmaking accounts for 40% of the total oxygen demand of the steel plant. However, the smelt-reduction (COREX) process requires 78% of the total amount of oxygen needed for iron production and 13% of the total amount of oxygen needed for steel making. The above two processes, especially the melting reduction iron making process, have been popularized in China. Steel mill gas requirements: The main role of oxygen supply in blast furnace smelting is to ensure a certain high temperature in the furnace, rather than directly participate in the smelting reaction. Oxygen is mixed into blast furnace and mixed as oxygen-rich air into blast furnace. The oxygen enrichment efficiency of the blast air proposed in the previous process is generally below 3%. With the improvement of the blast furnace process, in order to save coke, after the use of large coal injection process, and to meet the requirements of the blast furnace production to promote output, the oxygen enrichment rate of the blast air is increased to 5∽6%, and the single consumption of oxygen is up to 60Nm3/T iron. Because the oxygen mixture of blast furnace is oxygen-rich air, the purity of oxygen can be low. The oxygen in the melting reduction steelmaking process needs to be involved in the smelting reaction, and the oxygen consumption is directly proportional to the steel production. The oxygen consumption in the melting reduction furnace is 528Nm3/t iron, which is 10 times of the oxygen consumption in the blast furnace process. The minimum oxygen supply required to maintain production in the melting reduction furnace is 42% of the normal production amount. The oxygen purity required by the melting reduction furnace is greater than 95%, the oxygen pressure is 0.8∽ 1.0MPa, the pressure fluctuation range is controlled at 0.8MPa±5%, and the oxygen must be ensured to have a certain amount of continuous supply for a certain time. For example, for the Corex-3000 furnace, it is necessary to consider the liquid oxygen storage of 550T. Steelmaking process is different from blast furnace and melting reduction furnace smelting method. Oxygen used in converter steelmaking is intermittent, and oxygen is loaded when blowing oxygen, and oxygen is involved in smelting reaction. There is a direct proportional relationship between the amount of oxygen needed and steelmaking output. In order to improve the service life of the converter, nitrogen slag splashing technology is generally adopted in steel mills at present. Nitrogen is in intermittent use, and the load is large during use, and the required nitrogen pressure is greater than 1.4MPa. Argon is needed for steelmaking and refining. With the improvement of steel varieties, the requirements for refining are higher, and the amount of argon used is gradually increasing. The nitrogen consumption of the cold rolling mill is required to reach 50∽67Nm3/t per unit. With the addition of the cold rolling mill in the steel rolling area, the nitrogen consumption of the steel mill increases rapidly. Electric furnace steel-making mainly uses arc heat, and the temperature in the arc action zone is as high as 4000℃. Smelting process is generally divided into melting period, oxidation period and reduction period, in the furnace can not only cause oxidation atmosphere, but also can cause reducing atmosphere, so the efficiency of dephosphorization, desulfurization is very high. Intermediate frequency electric furnace is a kind of will power freque

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