From March 19th to March 24th in 2018, The Italy Italy Customer came to visist XLA. During this trip, They visited Yi chuan &Xishui Plant site in China. They spoke highly for the two plants。They visited the workshop in XLA. They approve the air separation plant of XLA. They considered the technology from design to manufacturing of air separation plant by XLA is vey mature and XLA also accumulated a lot of experience in this industry, which will get a higher level in the air separation industry.
The air separation unit adopts cryogenic technology, which uses oxygen and nitrogen gas to separate gas at different boiling point under the same pressure to extract oxygen, nitrogen and other gas components in the air. At present, the main air separation processes are divided into internal compression processes and external compression processes.
Most of the newly designed air separation units use the DCS control system. The DCS control system better realizes the chain protection and anti-surge control of air compressors, the sequence control of molecular sieve systems, and other conventional controls. The implementation of the DCS system has smoothed the operation of the equipment to some extent, and improved the control level of the equipment.
In order to achieve automatic variable load control and multivariable predictive control, and to achieve a better control effect, attention should be paid to the following aspects to ensure the optimal control system operation.
The performance of the air compressor can avoid entering the anti-surge zone during low load operation, and the inlet guide vane has good control of rapidity and stability.
The distillation tower ensures high stability in the full load range.
Instrument selection and design of adjustment control system minimizes measurement lag and guarantees the accuracy of continuous inspection.
The requirement of accuracy and rapidity of field instruments are relatively high.
The definition of LNG
Liquid natural gas (LNG) is natural gas (predominantly methane, CH4, with some mixture of ethane C2H6) that has been converted to liquid form for ease and safety of non-pressurized storage or transport. It takes up about 1/600th the volume of natural gas in the gaseous state (at standard conditions for temperature and pressure). It is odorless, colorless, non-toxic and non-corrosive. Hazards include flammability after vaporization into a gaseous state, freezing and asphyxia. The liquefaction process involves removal of certain components, such as dust, acid gases, helium, water, and heavy hydrocarbons, which could cause difficulty downstream. The natural gas is then condensed into a liquid at close to atmospheric pressure by cooling it to approximately −162 °C (−260 °F); maximum transport pressure is set at around 25 kPa (4 psi).
Xinglu air separation plant manufacturing equipment–Laser cutting machine.
Xinglu air separation plant manufacturing workshop-delicate skid-mounted fabricating
Suzhou Xinglu Air Separation Plant Science and Technology Development Co.,Ltd. focuses on the research&development, design and manufacture of cryogenic technical field.
The video will show you the air separation manufacturing in workshop.
steel industry is the main power for the development of air-separation industry which lead air-separation industry into its golden time.
According to the oxygen consumption of steel industry, during the process in the blast furnace, converter, continuous casting and rolling of the traditional process, the oxygen consumption of per ton steel is about 120 Nm3/h. Every year millions of tons of steel production scale need match air separation plants with the capacity of 15000 Nm3/h, when not in oxygen-enriched blast furnace can be reduced to 10000 Nm3/h. When using COREX puddling technology, electric converter, continuous casting and rolling steel are installed, the capacity of the spare parts required for each million tons of steel shall be increased to 50,000 Nm3/h, which is three to five times to traditional technology.
Steel industry is the big customer to air-separation worldwide, accounting for 60%~70% of total amount. 60s~80s of last century, the dramatic development boomed air-separation industry. After Japan introduced oxygen converters, the steel output increased from ten million tons to 100 million ton during ten years, the output of oxygen increased 20 times during 16 years. After a detour, China’s steel industry got back on track in the 1980s and exceeded 100 million tons in 1996. 340 million tons in 2005. China became the largest steel country in the world in 2005 with 340 million tons which was more than the sum of the three, Japan, the United States and Russia. And it is expected to be 620 million tons in 2010, more than the sum total of countries that ranked from 2nd to 21st behind.
From 2001 to 2010, due to the rapid development of national economy and the global manufacturing transferring to China, Chinese steel industry promoted developed rapidly. With the average annual output of 46 million tons of crude steel increased, per million tons of supporting air separation unit 15000 Nm3/h, a single steel, need new air separation unit capacity is 690000 Nm3/h.Thus, the gas industry was booming, and the golden period of Chinese air separation was brought forward.
During this period, Chinese air separation industry has followed the world’s advanced level and improves its competitive power. Both software and hardware facilities are ready for the take-off of the air separation industry.
The processes of puddling and steel-making need much oxygen.
Oxygen top blowing converter steel-making
Blast furnace rich oxygen blast
Electric furnace steel-making
Steel processing, continuous casting flame cutting, cleaning and so on, tonnage oxygen consumption is 10 ~ 12Nm3
Nitrogen is mainly used in metallurgical works for sealing gas, conveying gas, protecting gas, stirring gas, blowing gas, instrument gas, etc.
At present, the consumption ratio of oxygen and nitrogen in metallurgical plants is about 1:1, and the nitrogen consumption is also increasing. The nitrogen production should be properly reserved on design.
Argon is used for stainless steel smelting, steel ladle argon lowing, conticaster steel ladle and tundish nozzle sealing, protecting gas, etc.
At present, the energy consumption of argon in metallurgical plants is not very large, about 3 ~ 4.5Nm cubed per ton of steel, usually after the total amount is extracted, spare parts are sold.
Interdependence and mutual promotion is the relationship between steel industry and air-separation industry. Growth of steel industry leads the development of gas industry and the development of gas industry promotes steel industry, which is similar to the closed acting force and counter-acting force. New technologies appeared in steel industry require new quantity, quality and technology from gas industry now and again. To meet the continuous demands of steel industry, gas industry has developed itself and promoted the steel industry forward, which can be noticed when looking back the development of domestic and overseas air-separation industry. Get a clear understanding of the relationship between the two industries is extremely important to gas industry, which can remind us to focus the development trends of steel industry and make or modify industry development strategies. It also help gas industry to research new gas technology combined with steel industry to capture business opportunities and control the market. When the steel industry flags, a clear understanding can adjust the marketing direction in time, improve the old air separation plants transformation and reserve technologies.
After impurity removal, air is taken by compressor and compressed to ~1.1MPa. After cooling down, harmful components, such as moisture, CO2, C2H2 are removed by purifying system.
After purification, compressed air is cooled down by the main heat exchanger and cold refrigerator, and sent to rectification column for rectification. Through sub-cooler, liquid air, liquid waste nitrogen and liquid pure nitrogen are sent to upper column for secondary rectification. In upper column, liquid oxygen at 99.6% is obtained at bottom, which is delivered out of cold box via sub-cooling as product.
Waste nitrogen is drawn from top of upper column. Through heat exchanger, it is expanded to provide coldness to the whole system. After warming up, it is delivered out of cold box and divided into 2 streams. First stream goes to purifying system for regeneration of molecular sieve. Second stream is delivered to pre-cooling system to cool down the cooling water.
While third stream of waste nitrogen delivered out of cold box is compressed by recycle compressor and booster of turbine. Afterwards, it goes into cold box and is cooled down by heat exchanger. Cool gas is expanded subsequently to supply coldness to whole system. After expansion, it is warmed up in heat exchanger and goes for another round of circulation.
The production of argon works on hydrogen-free rectification process specified as following described: Liquid argon fraction is drawn out from the upper column into crude argon column and pure argon column, where liquid argon product is got through rectification.