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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



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.



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



Adding new gas sources to the West-East Natural Gas Pipeline ensures the rapid growth of demand

Well Keshen 902, China's first onshore natural gas production well with a depth of more than 8,000 meters, has been put into operation recently, delivering 400,000 cubic meters of natural gas per day, adding a new gas source to the west-east natural gas pipeline. The Keshen 902 well, located in Baicheng County, Xinjiang Province, is the first and deepest natural gas well to be put into operation on land in China. The production of this well will promote the development of ultra-deep oil and gas resources in Tarim Oilfield, which is of great significance to the construction of 30 billion cubic meters of atmosphere in Tarim Oilfield and the guarantee of China's energy security. Tarim oilfield is one of the main gas sources of west-east natural gas transmission. In recent years, with the increase of gas consumption in the lower reaches of west-east natural gas transmission and gas consumption in the pipeline network of natural gas benefit project in southern Xinjiang, Tarim oilfield continuously strengthens oil and gas exploration and strives to ensure the gas supply. By the end of 2017, the total gas supply from the oilfield to the east exceeded 200 billion cubic meters. Opinions of accelerate the natural gas utilization, points out that natural gas will be to be one of the main energy of our country's modern clean energy system, by 2020, natural gas in primary energy consumption structure in proportion to about 10%, to 2030, strive for the natural gas in primary energy consumption proportion increased to 15%. The guideline on energy work in 2018 calls for China's total energy consumption to be capped at around 4.55 billion tons of standard coal. The proportion of non-fossil energy consumption and natural gas consumption will rise to around 14.3 percent and 7.5 percent respectively, and the proportion of coal consumption will drop to around 59 percent. According to data released by the National Development and Reform Commission, in April 2018, China's apparent consumption of natural gas was 22.13 billion cubic meters, up 16.7% year on year; The cumulative apparent consumption of natural gas from January to April was 91.13 billion cubic meters, up 16.7% year on year. The main reasons for the steady increase in consumption are the steady progress in replacing coal with gas, the recovery of the macro economy and the high price of alternative fuels.



Liquid oxygen liquid nitrogen all the way red behind the reason is...

Nitrogen trifluoride at room temperature is a colorless, odorless, stable gas, is a strong oxidant, nitrogen trifluoride is mainly used in fluorine agent, combustion agent, propellant oxidant, high temperature metal cutting oil, etc., widely used in the semiconductor industry. However, in the early years, the related products were monopolized by foreign countries, and the market pricing power was in the hands of foreign manufacturers. In order to break the monopoly crisis and seize the market opportunity, China successfully developed high purity nitrogen trifluoride in 2009. The products are listed in the national "key new products" and "torch plan", applied in most of the domestic semiconductor, liquid crystal, solar energy industry, and exported to the United States, Japan, France, Germany and other countries. At present, China has built the largest domestic nitrogen trifluoride and other products R & D production base. The coverage rate of nitrogen trifluoride in the domestic market is more than 95% and that in the international market is 30%. In the past two years, the annual growth rate has reached 30%, and we strive to achieve an annual output of 12,000 tons of high-purity nitrogen trifluoride gas by 2020. China's electronic gas is still a short board in the development of electronic materials, need to focus on development. At present, the production of high purity nitrogen trifluoride gas can meet the domestic demand. With the development of semiconductor electronics industry, it is not known whether the production of high purity nitrogen trifluoride gas can also meet the development of the industry. Therefore, although the production of high purity nitrogen trifluoride in China has made a breakthrough, whether it can really reduce the market price is still a problem!



China's wind and photovoltaic power generation into the bidding era may trigger a major industry shake-up

"The most market-oriented policy in history" China's wind power photovoltaic power generation into the bidding era "The opening of competition, new energy price decline is an inevitable trend, very likely to promote a new round of industry reshuffle." On June 2, an industry source from Ningxia, China's first comprehensive demonstration zone for new energy and the first pilot region of the auxiliary power service market in Northwest China, said that newly announced wind power and photovoltaic power generation projects will adopt competitive configuration, giving priority to projects with low subsidy intensity and strong slope regression. The New Deal is bound to affect business investment enthusiasm On May 30th, the National Energy Administration issued "about 2019, wind power, photovoltaic power generation project construction related matters notice, clear wind power, photovoltaic power generation project is divided into two categories, do not need to state subsidies and need state subsidies, in power grid enterprise organization the demonstration of the power project and implement the parity, send out and based on the given condition, promoting the construction of parity project priority, start to state subsidies on the competition project configuration. A person in charge of the new energy department of the bureau said the purpose of the move is to improve the competition allocation mechanism of projects that need state subsidies and reduce the dependence of industry development on state subsidies. This year, the general direction of wind power and photovoltaic power generation is to "adhere to the general keynote of seek improvement in stability, speed up technological progress and reduce the intensity of subsidies, do a good job in coordinating project construction and consumption capacity, and achieve high-quality development". This is known as the "history of the most market-oriented" policy, marking the country's wind power photovoltaic into the bidding era. Since the "13th Five-Year Plan", the application scale of wind power and photovoltaic power generation in China has been expanding, the technical level has been significantly improved, and the cost has gradually decreased. But at the same time, the subsidy gap continues to expand, some areas abandoned wind and light power rationing and other problems are prominent. The latest figures show that the installed capacity of new energy in Ningxia's power grid is about 15 million kilowatts, accounting for 49% of the power generation and 102% of the electricity load. It has become the first provincial power grid in China where the output of wind power and photovoltaic power exceeds the power consumption of the whole region. From 2013 to 2018, the average annual growth rate of wind power installed capacity was 27%, photovoltaic installed capacity was 40%, and new energy installed capacity was 32%, ranking second in the country. An expert from the Ningxia New Energy Research Institute, who declined to be named, said that the fierce competition among energy investment enterprises is mainly reflected in the competition of feed-in tariff. As the price of electricity drops, the return on investment will also decrease, which will inevitably affect the enthusiasm of enterprises to build photovoltaic power stations. On the other hand, some photovoltaic power generation enterprises have to invest by selling power stations in order to digest their production capacity, which also has a great impact on their enthusiasm to build power stations. The main reason is that the price of photovoltaic construction has dropped significantly in recent years, and the decrease of equipment price leads to the decrease of investment cost. The expert said the initial set price was as high as 20 yuan per watt, but dropped to a minimum of 1.6 yuan per watt last year. "This also means that the electricity price to a low level, two years ago the lowest electricity price in Ningxia is 0.55 yuan, now open up the competition, it is estimated that it will reach 0.35 yuan or so, basically close to parity." He admits.



"Weakness" hard carbon aerogels seem to have a lot of power

Recently, a research group led by Professor Shuhong Yu from the University of Science and Technology of China, inspired by the high strength and elasticity of natural spider webs, has skillfully prepared a series of hard carbon aerogels with a network structure of nanofibers through the template method. This series of aerogels has the advantages of super elasticity, fatigue resistance and good stability. The research results were selected as the back cover of the paper published in Advanced Materials. Aerogel is sometimes referred to as "solid smoke" or "frozen smoke" because of its translucent color and ultra-light weight. Aerogel looks fragile, but it's actually very strong and durable. It can withstand thousands of times its own mass and does not melt until temperatures reach 1,200 degrees Celsius. It also has low thermal conductivity and refractive index, and insulation that is 39 times stronger than the best glass fiber. Because of these properties, aerogel has become an irreplaceable material for space exploration. Both the Russian Mir space station and the American Mars Pathfinder spacecraft have used it for thermal insulation. Carbon materials can be roughly divided into graphite carbon, soft carbon and hard carbon according to the different hybrid orbitals of carbon atoms. Soft carbon and hard carbon are mainly used to describe carbon materials prepared by polymer pyrolysis. During the pyrolysis process, some carbon atoms reconstitute two-dimensional aromatic graphene sheets. If these graphene sheets are roughly parallel, they are prone to graphitization at high temperatures. If these graphene sheets are stacked randomly and cross-linked by edge carbon atoms that cannot be graphitized at high temperatures, the carbon is called hard carbon. Generally speaking, graphite carbon and soft carbon have high elasticity, easy to deformation, but low strength; Due to the existence of the "house of cards" structure on the microstructure of hard carbon, the hard carbon material shows great advantages in mechanical strength and structural stability, but the intrinsic nature is brittle and fragile. How to prepare hard carbon material into super - elastic block is a challenge at present. By using resorcine-formaldehyde (RF) resin as the hard carbon source and using a variety of one-dimensional nanofibers as the structural template, the researchers prepared RF nanofiber aerogels, which were superelastic hard carbon aerogels obtained by carbonization at high temperature. This hard carbon aerogel has a fine microstructure and is made up of a large number of nanofibers and the weld joints between them. This method is simple, efficient and easy to scale production. By adjusting the addition amount of template and resin monomer, the diameter of nanofibers, the density of aerogel and the mechanical properties of the nanofibers can be easily controlled. Unlike traditional hard carbon blocks, which are hard and brittle, this kind of hard carbon aerogel shows excellent elastic properties, such as stable structure, microstructure can still recover after compression by 50%. The rebound speed is higher than that of many graphite-carbon-based elastic materials; Low energy loss coefficient, general graphite and soft carbon materials in the existence of intermolecular forces, will cause adhesion and friction force and dissipate a lot of energy; Fatigue resistance. After 104 cycles of testing at 50% strain, the carbon aerogel showed only 2% plastic deformation and maintained 93% initial stress. The researchers have also explored the application of this hard carbon aerogel in elastic conductors where resistance is almost constant after multiple compression cycles at 50% strain, demonstrating stable mechanical-electrical properties while maintaining hyperelasticity and resistance stability under harsh conditions, such as in liquid nitrogen. Because of its excellent mechanical properties, this kind of hard carbon aerogel is expected to be used in stress sensors with high stability, large range, stretchability or bendability. In addition, this method can be extended to prepare other non-carbon based composite nanofiber aerogels, providing a new way to convert rigid materials into elastic or flexible materials by designing the microstructure of nanofibers in the future.



Air separation equipment petrochemical market share doubled

From the China general machinery industry association branch of gas separation equipment, nearly three years in our country the air separation equipment market structure change in quietly, although the market is still in metallurgical industry is given priority to, but with the rapid development of petrochemical industry, fertilizer industry, air separation equipment in petrochemical industry market share has increased from 14.5% in 2002 to around 30% in 2005. In addition, the large-scale development trend of air separation equipment is more obvious, and the manufacturing technology is becoming more and more mature. It is reported that in 2005, among the 25 sets of air separation equipment above 30,000 grade signed in the domestic market, 10 sets are used in the petrochemical and fertilizer industry; A total of 39 sets of air separation equipment above 20,000 grade have been signed in the whole industry, among which 25 sets of large air separation equipment above 30,000 grade have been signed, which is the fastest year for the development of large air separation equipment market in history. Experts believe that there are three main reasons driving the large-scale development of air separation equipment in China. First, after the macro-control of the steel industry in China, the joint restructuring of the metallurgical industry has brought about new market demand. Second, the development of petrochemical and chemical fertilizer industries, especially the launch of coal-to-oil, large-scale chemical fertilizer and large-scale ethylene projects, has opened up new development space for large-scale air separation equipment. Third, the manufacturing technology of large-scale air separation equipment in China has become increasingly mature and the advantages of cost performance have won the trust of more and more domestic users. In addition, China's air separation equipment manufacturing industry has made new breakthroughs in new product development and new technology application, which has promoted the development of China's air separation equipment manufacturing technology. Among them, the hangyang co., LTD. Provide Iran with two sets of 63000 m3 / h air separation equipment is the maximum level of the current domestic self-developed air separation equipment, the device adopts the low molecular sieve purification absorption, medium voltage air pressurization turbine expander, structured packing and full of pure argon flow system technology of an internal compression process of oxygen, fill the blank of our country develop the level of 60000 air separation equipment; The 52000m3/h air separation equipment provided for the 500,000-ton/year methanol project of Zhongyuan University Chemical Co., Ltd is the largest domestically made air separation equipment in China by adopting the process of air pressurization and oxygen and nitrogen double pump internal compression. It is also reported that at present in the oxygen pressure of 4.6Mpa above the use of chemical enterprises in the air separation device, have adopted the liquid oxygen pump compression process, oxygen extraction rate can reach 95% ~ 97%, argon extraction rate can reach 70% ~ 80%, these technical indicators have been close to the international advanced level.  



A new catalyst for hydrogen production from water has been developed in China

Hydrogen energy is a kind of high energy, clean and renewable energy. The low cost and high efficiency hydrogen production by electrolysis of water is one of the hot spots in international research. Recently, Professor Song Li and Professor Jiang Jun from the University of Science and Technology of China collaborated to design a platinum catalyst with a "pine cone structure", which reduced the platinum consumption to about 1/75 of that of traditional commercial catalysts without changing the hydrogen production effect. The research results were recently published in the internationally renowned academic journal Nature Energy. Hydrogen is considered the "ultimate energy source," and electrolysis of water is one of the most promising ways to prepare it. Catalysts are needed in the process of water electrolysis, but in the catalytic process, atoms are "busy and idle" phenomenon: the surface atoms of the platinum catalyst are mainly involved in the reaction, while the platinum atoms in the inner layer are "idle", resulting in a waste of resources and high cost. Recently, University of Science and Technology of China researchers came up with a solution. They took the previously flat catalyst and made it into spherical "pinecones", placing the platinum atoms on the surface of the "pinecones", ensuring that they were all in the "production line". Thus, the previous two - dimensional plane reaction is transformed into a three - dimensional reaction. The results showed that the efficiency of hydrogen formation was greatly increased when the reactants in the electrolytic solution passed through the "pine-shaped" catalyst. For the same amount of hydrogen to be produced, the new catalyst requires only about 75 times as much platinum as conventional commercial catalysts, greatly reducing the cost of hydrogen production. It is understood that this study also deepens the understanding of the relationship between catalyst performance and structure, and points out the direction for further optimization of catalyst performance.



What function does the freeze dryer have for production?

Compressed air is widely used and has become the second largest industrial power source. The compressed air freezer dryer is used for drying compressed air equipment. In the compressed air, there are mainly water, dust and oil that need to be removed. The refrigerated dryer undertakes the work of water removal. What's the harm of water? The atmosphere contains a large number of water molecules, after being compressed to produce a large number of liquid water, will make the pipeline and equipment rust. In spraying, PCB and other industries, it will also pollute raw materials, which has a great impact on the production quality. Therefore, the freeze dryer emerged at the historic moment. It is used to dry compressed air through freezing cooling technology. After the compressed air processed by the freeze dryer, 95% of the water molecules are removed. At present, the air compressor station in China is basically equipped with a refrigerated dryer, which is economical and practical, convenient to operate, and not much energy consumption (electricity). If the freeze dryer is not used, there will be a large amount of water in the compressed air into the back end of the gas, resulting in equipment failure and damage, pipeline corrosion, product defect rate reduction will greatly increase the production cost, bringing a huge burden to the enterprise. We have seen a textile factory in Dongguan. Due to the lack of understanding of compressed air and the low initial budget, a filter was installed at the back end, so that a large amount of liquid water entered the air jet loom and pipeline. Although the water did little harm to the cloth, the failure rate of the equipment was very high, and the monthly loss cost was tens of thousands of yuan. And a freeze dryer only needs several thousand yuan, so the biggest role of the freeze dryer for enterprises is to reduce production costs.

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