Manufacturing and Purification Process of Syngas in Linde Company

1 technical progress The process of producing olefins from methanol from coal is mainly composed of three technologies: coal gasification to synthesis gas, synthesis gas to methanol, and methanol to olefins. Coal gasification produces carbon monoxide and H2 (synthesis gas), then methanol is synthesized, and then low-carbon olefins (ethylene and propylene) are produced by fluidized bed reaction similar to catalytic cracking unit. Among them, large-scale coal gasification technology and million tons methanol production technology are mature and reliable, which can meet the needs of economic-scale methanol-to-olefin plants, and the key is methanol-to-olefin technology. At present, methanol to olefins technologies with commercial transfer conditions in the world include methanol to light olefins (MTO) process jointly developed by Global Oil Company of the United States and Hydro Company of Norway, methanol to propylene (MTP) process of Lurgi Company of Germany and methanol to light olefins (DMTO) process of Dalian Institute of Chemistry of Chinese Academy of Sciences. Although these three processes have not been operated in industrial plants, they have been developed for many years and meet the requirements of industrialization. 1. 1 gasification technology At present, the representative types of industrialized coal gasification furnaces are: fixed bed gasification (Lurgi furnace, BGL furnace); Fluidized bed gasification (Winkler furnace, HTW furnace, U-shaped gas furnace, KRW furnace and CFB gasifier); Entrained bed gasification (KT furnace, Texaco furnace, Shell furnace, Prenflo furnace and GSP furnace). These three types of gasifiers have their own characteristics. Lurgi and Texaco are the most mature companies in industrialization. Lurgi furnace uses weakly bonded lump coal as raw material, and the gas cooling efficiency is the highest, but the purification system is complex (tar treatment). Texaco gasifier needs to use low ash and low ash melting point coal as raw materials and operate at high temperature. Although the gasification intensity and gas quality are high, the oxygen consumption and equipment investment are high. The working temperature of high temperature Winkler /HTW is relatively low, which is only suitable for young bituminous coal or lignite. Efficient and clean coal gasification technology developed by developed countries has been commercialized, such as Texaco's Tampa (2000 tons of coal/day, power generation capacity of 250 MW); Shell gasification technology (processing 2000 tons of coal a day and generating 250 MW); Puertollano based on Kropp technology (processing 2600 tons of coal and oil every day and generating 300 MW). 1.2 methanol synthesis technology At present, the scale of new methanol plants in the world is increasing, most of which have increased to 600,000-800,000 t/a, and the largest single-series methanol plant has reached more than 6.5438+0.8 million t/a, and larger single-series methanol plants are also under development. Foreign methanol production mostly adopts low-pressure process, mainly including Davy, Lurgi, Tops and other methods. The first two methods are considered to be relatively advanced methanol technologies, and about 80% methanol plants use these two methods for production. See table 1 for comparison. In addition, Mitsubishi Gas Company of Japan, Linde Company of Germany and Kellogg Company of the United States have developed energy-saving low-pressure methanol production technology. The catalyst needed for synthesis reaction has always been the core of the development of methanol synthesis technology. Although a variety of methanol synthesis catalysts have been developed in the laboratory, only zinc-chromium and copper-based catalysts are used in industry. Zinc-chromium (ZnO/cr2o 3) catalyst is a high-pressure solid catalyst. The activity of Zn-Cr catalyst is low. In order to obtain high catalytic activity, the reaction needs to be between 350-450℃. In order to obtain higher conversion, it is necessary to operate under high pressure, and the operating pressure is 25-35MPa, so it is called high pressure catalyst. Before 1966, almost all methanol synthesis plants in the world used this catalyst, and now it has been gradually eliminated. Copper-based catalyst is a kind of low-pressure catalyst, and its main component is CuO/ZnO/al2o 3, which was successfully developed by ICI Company in Britain and Lurgi Company in Germany. The synthesis temperature of the catalyst is much lower than that of zinc-chromium catalyst, which is beneficial to the methanol reaction balance. At present, copper-based catalysts are mainly used in synthetic production process. 1.3 MTO technology MTO is the process of converting synthesis gas into low-carbon olefins through methanol. Some famous international petrochemical companies, such as ExxonMobil, BASF, UOP and Noske Hydrogen Company, have invested a lot of money and personnel and conducted research for many years. 1995, UOP cooperated with Norwegian NorskHydro company to build a demonstration unit with methanol treatment capacity of 0.75 t/d. After 90 days of continuous operation, the methanol conversion rate was close to 100%, and the carbon-based mass yield of ethylene and propylene reached 80%. The process adopts the design of fluidized bed reactor and regenerator, and the reaction heat is recovered by the generated steam. The deactivated catalyst is sent to the fluidized bed regenerator for carbon regeneration, and then returned to the fluidized bed reactor to continue the reaction. Before separation, the whole product airflow mixture needs to pass through a special raw material airflow heat exchanger to remove most of the moisture and inert substances, then the gas product is further dehydrated through a gas-liquid separation tower, CO2 is removed through an alkali washing tower, and after drying, it enters the product recovery section. This part flows through demethanizer, deethanizer, acetylene saturation tower, ethylene separation tower, propylene separation tower, depropanizer and debutanizer. Oxygenates are also removed in the compression section. It is understood that this process is very similar to the mature catalytic cracking technology in the oil refining industry except that the heat transfer in the reaction section (reaction-regeneration system) is different, the operating conditions are not so harsh, and the technical risks are also under control. The product separation section is similar to the traditional naphtha cracking process to produce olefins, with simpler product composition, less kinds and contents of impurities, and easier to realize product separation and recovery. The MTO process of UOP/Hydro can adjust the output ratio of C=2 and C=3 olefins in the reaction products in a wide range, and manufacturers can produce marketable products according to market demand to obtain the maximum income. SAPO-34 catalyst of UOP/Hydro Company has suitable internal pore size and solid acid strength, which can reduce the oligomerization of low-carbon olefins and improve olefin selectivity. UOP/Hydro Company developed a new catalyst MTO- 100 based on SAPO-34 catalyst. The new catalyst MTO- 100 can make the selectivity of ethylene and propylene reach 80%. 1998 UOP/Hydro process 200,000 tons/year industrial plant completed and put into operation (calculated by ethylene output). At present, European Chemical Technology Company is building a 7500 t/d production plant (calculated from methanol) in Nigeria by using the MTO technology of UOP/Hydro Company. Methanol is used as the raw material of MTO plant. The designed production capacity of ethylene and propylene in MTO plant is 400,000 tons/year, and it is expected to be completed and put into operation in 2007. Dalian Institute of Chemistry of China Academy of Sciences completed the MTO pilot test during the Eighth Five-Year Plan period. In 2005, Dalian Institute of Chemistry, Shaanxi Xinxing Coal Chemical Technology Development Co., Ltd. and Luoyang Petrochemical Engineering Company of China Petrochemical Group built a DMTO industrial test device with a production scale of1.5000 t/a based on raw material methanol in Shaanxi. The device was put into trial operation in June 5438+February 2005, and passed the national appraisal on August 23, 2006. After the appraisal of national scientific and technological achievements, it is determined that the independent innovation industrialization technology of this project is at the international leading level. In an industrial test plant with a daily output of 50t, the methanol conversion rate is close to 100%, and the selectivity of low-carbon olefins (ethylene, propylene and butene) is over 90%. According to the report of 1 in Shaanxi Province, at present, the project with an annual output of 3 million tons of methanol and olefins jointly invested by Zheng Da Energy and Chemical Group, Shaanxi Coal Chemical Group and Shaanxi Investment Group has settled in Yulin, and the preliminary work of the project has been fully carried out. The successful operation of pilot plant and the construction of large-scale DMTO industrial plant in the next step are of great economic and strategic significance for China to comprehensively utilize energy and expand the diversification of low-carbon olefin raw materials. 1.4 MTP technology MTP technology was successfully developed by Lurgi Company of Germany in 1990s. The process adopts stable molecular sieve catalyst and fixed bed reactor, and the catalyst is provided by Sud-Chemie Company. In the first reactor, methanol is converted into dimethyl ether, and in the second reactor, methanol is converted into propylene, and the reaction-regeneration operation is alternately switched. The process flow is basically the same as that of the methanol-to-gasoline plant built in New Zealand in 1980s. The industrial scale-up of the reactor has mature experience for reference, the technology is basically mature, and the risk of industrialization is very small. In 200 1 year, Lurgi Company built a demonstration device of MTP process in Norway, and obtained a lot of data for large-scale industrial design. In March, 2004, Lurgi Company and Iran Fanavaran Petrochemical Company formally signed the MTP technology transfer contract, with a plant scale of 654.38 million tons/year ... Lurgi Company and Iran Petrochemical Technology Research Institute together provided Iran Fanavaran Petrochemical Company with basic design, technical license and main equipment. The project is expected to be completed and put into operation in 2009, when it will become the world's first 1 MTP industrial production device. The reliability and economy of Lurgi MTP technology also need to be tested and verified after the Iranian project is put into production. Lurgi MTP technology is characterized by high propylene yield, proprietary zeolite catalyst, low wear fixed bed reactor and low coking catalyst, which can reduce the number of regeneration cycles and can be regenerated intermittently at reaction temperature. The supplier has completed the development and industrial scale production of the catalyst used in MTP technology. The MTP process developed by Lurgi Company is different from MTO, except that the catalyst has high selectivity to propylene, and the reactor adopts fixed bed instead of fluidized bed. Typical product volume composition is: ethylene 1.6%, propylene 7 1.0%, propane 1.6%, C4/C58.5%, and C+665438+. 0.0 1%。 Due to the relative reduction of by-products, the separation and purification process is simpler than MTO.

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