Are the isothermal transformation process and catalyst reliable? Let’s all come and discuss it
Thread Content
The shift process has a history of several decades. Traditionally, adiabatic shifting has been used; a single-stage shift converter is sufficient for methanol production, while 2–3 stages are required to meet the requirements for ammonia synthesis. Inter-stage quenching is used for heat removal in the reaction. Recently, an isothermal conversion process has emerged in China; the conversion furnace is somewhat similar to a methanol synthesis tower. The reaction heat is removed via water pipes buried between the catalyst beds, with a steam drum generating steam of the appropriate grade as a by-product. It is understood that domestic patent holders for isothermal conversion generally sell process packages, conversion furnaces and steam drums, as well as catalysts, as a set. I have a few thoughts on this: Given the limited number of studies on isothermal transformations, although it is technically feasible, is the catalyst, which is the core of such transformation reactions, reliable? Is there a risk of leakage in the converter? None of these have yet been tested through 3 to 5 years of practical use. I wonder what everyone thinks about the reliability and market prospects of domestic isothermal transformation technologies?
Indeed, a few furnaces for isothermal transformation have appeared in China, but the exact situation is not clear. I hope those who are aware of the situation can provide some information
The isothermal transformation furnace of Hunan Anchun Company has been in use for over 2 years now.
Isothermal transformation is already a mature technology, and many manufacturers have started using it; our factory’s technical improvement project will adopt isothermal transformation
Most of them are used for 2 to 3 years or less, and to date, no problems have been reported among the manufacturers using them. In terms of the methanol reaction in a shift converter, the conditions in such converters are not too stringent, so the equipment’s service life should be reliable
After the renovation, the four major energy consumption aspects related to ammonia synthesis were significantly reduced. A breakthrough was achieved in the fourth generation of controllable heat transfer conversion technologies. Author/Source: China Chemical Industry News; Date: 3-08-2016; Clicks: 215. Reporters from China Chemical Industry News learned from the Linyi branch of Yangmei Fengxi Group that, as of March 4, one of the company’s ammonia synthesis plants equipped with patented technology from Nanjing Dunxian Chemical Technology Co., Ltd. had been operating stably for a full month, resulting in significant savings in energy use. The steady operation of this device marks a major breakthrough in China’s independently developed fourth-generation controllable heat transfer conversion technology. Compared with the original unit, the power consumption of the modified compressor has been reduced by 55 KWh/tNH3; steam consumption has dropped from 465 kg/tNH3 to 100 kg/tNH3, and circulating cooling water consumption has fallen from 12 m3/tNH3 to 4 m3/tNH3. The energy consumption per ton of ammonia has been reduced by 1984.86 MJ, resulting in a savings of 67.73 kg of standard coal per ton of ammonia, for an annual savings of 16,931.3 tons of standard coal. According to Wang Qingxin, general manager of Nanjing Dunxian Company, this transformation furnace with dual drum controllable heat transfer technology is the fourth-generation DX-Ⅳ patented product developed by the company. The catalyst bed is equipped with a medium-temperature reaction zone, a sub-medium-temperature heat recovery zone, and a low-temperature equilibrium zone. There are two sets of heat exchange tubes embedded in the catalyst bed, which generate saturated steam at two pressure levels: 2.5 MPa and 1.0 MPa respectively. One device replaces the secondary shift reactor, tertiary shift reactor, quaternary shift reactor, as well as the direct or indirect heat transfer equipment between these stages in the conventional adiabatic shift process; the length of the catalyst bed section is reduced by 4/5. In addition, the number of operators has been reduced from 12 per shift to 4 per shift, which is in line with the guidelines for the transformation and upgrading as well as technical upgrades of nitrogen fertilizer enterprises during the 13th Five-Year Plan period. Yuan Zhongqiu, chairman of the Linyi branch of Yangmei Fengxi Group, said that with the use of fourth-generation double-drum controllable heat-transfer shift technology, a single shift unit is sufficient to achieve a production capacity of 750 tons of ammonia per day. Based on the current stable operation at 60% load, the pressure in the conversion system is 1.9 MPa, the system resistance is 0.039 MPa. Approximately 12,000 kg/h of saturated steam at 2.158 MPa is generated and used directly within the conversion system, while 2,810 kg/h of saturated steam at 0.87 MPa is sent out for external use. The exit temperature at the end of the catalyst bed is around 183°C, and the temperature of the gas exiting the terminal gas heat exchanger is less than 87°C. The project has fully achieved its purpose of energy-saving renovation and upgrading. Preliminary estimates indicate that the operating cost per ton of ammonia can be reduced by 85 yuan, allowing for a full recovery of the total project investment within two years. Yuan Zhongqiu told the reporter that the reason for a 40% reduction in energy consumption as a result of this energy-saving upgrade was, firstly, the increase in the design pressure of the system from 0.8 MPa to 2.5 MPa; this led to a reduction in the volume of gas transported by the compressor by 992.2 Nm3/tNH3, thereby saving energy used by the compressor ； The second is the fourth-generation DX-IV type dual-drum controllable heat-transfer conversion furnace, which generates saturated steam as a by-product of the heat exchange tube bundle, thereby reducing the overall steam-to-gas ratio and effectively cutting steam consumption ； Thirdly, the saturated steam is either used within the converter itself or sent outside, which not only reduces steam consumption but also effectively lowers the consumption of circulating cooling water ； Fourthly, in the DX-Ⅳ type double-drum controllably heat-transferred shift reactor, the molar fraction of steam entrained in the shift gas is lower than that in traditional adiabatic full-shift processes, and the dew point temperature is lower, thereby effectively extending the service life of the equipment in the shift system.
Isothermal shift technology used for the first time in synthetic ammonia HT-L gas production. Author/Source: China Chemical Industry News. Date: November 13, 2015. Clicks: 432. On November 10, reporters learned from Xinjiang Zhongneng Wanyuan Chemical Co., Ltd. that the company’s 300,000 tons per year synthetic ammonia plant and 520,000 tons per year urea plant have been in operation successfully and stably for over two months now. This is the first application of the Anchun isothermal shift technology in the gas flow bed powder coal gasification process using an HT-L reactor for the conversion of high-CO crude syngas, thereby meeting the process requirements for a low CO content in the syngas used for ammonia production. The operation results show that, when compared with the design parameters, the performance of the isothermal conversion unit in this project meets all the design requirements and even exceeds them. According to Xu Shen, the chief project supervisor at Xinjiang Zhongneng Company, the gasification section of the company’s “30·52” project utilizes the HT-L pressurized coal gasification process, while the shift section makes use of isothermal low-temperature CO shift reactors and related system technologies developed by Hunan Anchun High-Tech Co., Ltd., which hold complete independent intellectual property rights. The core equipment in this regard is the 3800-phase change heat transfer isothermal shift reactor developed by Anchun Company itself. The project was officially completed and put into production on August 22 this year, and the facility is currently operating stably. The inlet CO content of the isothermal shift system is 63.7%, with a water-to-gas ratio of 0.8; the outlet CO content is 0.62%, achieving a conversion rate as high as 99%. At full load, the resistance of the isothermal reactor is ≤0.02 MPa, and the system resistance is ≤0.1 MPa; 0.76 tons of steam at 4.0 MPa can be produced per ton of ammonia, thereby completely preventing overheating or uncontrolled temperature rises during startup and operation. Compared to traditional and other conversion technologies in use domestically, Anchun Company’s isothermal conversion technology features a small temperature difference across the catalyst bed, low system resistance, and high conversion efficiency. Its advantages of \"low temperature difference, low resistance, and high efficiency\" are very evident; there are no hot spots, and the operation is natural, isothermal, making it a true isothermal conversion technology. It is understood that the phase-change heat transfer isothermal reactor and related application technologies passed the expert evaluation organized by the China Petroleum and Chemical Industry Federation at the end of last year. The evaluation committee deemed that the phase-change heat transfer isothermal reactor developed by Anchun Company has a rational structure and advanced technical specifications, reaching an internationally leading level; it also recommended accelerating the further development, promotion, and application of these technologies. The DDB phase-change heat transfer isothermal transformation reactor developed by Hunan Anchun has four main features: first, it enables precise control of the temperature in the reaction bed, with a temperature difference of <4°C; this results in high reaction efficiency, a long service life for the catalyst, and a high energy recovery rate ； Secondly, the radial distributor ensures even gas distribution, thereby effectively improving the utilization rate of the catalyst ； Thirdly, catalyst loading tubes are evenly distributed between the tube sheets in the design, ensuring uniform catalyst filling ； Fourth, the double-shell plate and double-tube special structure effectively absorbs expansion stress, ensuring safe use. The phase-change heat transfer isothermal shift reaction technology was first applied nationwide in 2012, and it has since been successfully used in the conversion of calcium carbide furnace exhaust gases with high CO content, as well as in the gasification conversion of water-coal slurry and pulverized coal, having withstood thorough market testing. This technology is applicable both to newly installed units and to the retrofitting of conventional conversion units. It can be used in calcium carbide furnace exhaust gases, as well as in various coal chemical plants for producing synthetic ammonia from coal, natural gas from coal, hydrogen from coal, oil from coal, ethylene glycol from coal, methanol from coal, olefins from coal, and sulfur from H2S. It is suitable for CO conversion of gas produced by pressurized continuous gasification of pulverized coal, pressurized continuous gasification of coal slurry, and batch fixed-bed gasification. Its technical and economic advantages are particularly evident in cases of CO conversion involving high CO concentrations and high gas-to-solid ratios.
Innovative heat transfer transformation process receives invention patent; Author/Source: China Chemical Industry News; Date: 2014-09-19; Clicks: 713. On September 16, reporters from China Chemical Industry News learned from Nanjing Dunxian Chemical Technology Co., Ltd. that the new energy-saving deep conversion process with controllable heat transfer, developed by this company, has been granted an **invention patent. The name of the patent is a water-based heat transfer transformation process for energy-saving deep conversion that generates high-quality steam as a by-product. According to Wang Qingxin, General Manager of the company, this patented technology has currently been successfully applied in six plants, including the 200,000-ton/year ammonia synthesis plant utilizing a gasifier based on space technology at Anhui Haoyuan Chemical Group Co., Ltd., and the 150,000-ton/year ammonia synthesis plant with an atmospheric-pressure fixed-bed gasifier at Shandong Lianmeng Chemical Co., Ltd. There are nine more plants currently under design, such as the 350,000-ton/year ammonia synthesis plant and the 750,000-ton/year methanol plant at Shandong Luxi Group, as well as the 200,000-ton/year ammonia synthesis plant and 200,000-ton/year methanol plant at Hebei Qian’an Fertilizer Co., Ltd. Additionally, discussions are underway regarding several other new plants. The products involved include coal-based ammonia, methanol, hydrogen, natural gas, and oil. The maximum processing capacity of the single unit under design is 140.3×104 Nm3/h on a wet basis and 77×104 Nm3/h on a dry basis, making it the largest facility of its kind in China. It is understood that this patented technological achievement passed the evaluation of scientific and technological achievements organized by the China Petroleum and Chemical Industry Federation in June this year. Industry experts unanimously agree that the design concept of having a large temperature difference across the temperature and depth profile of the catalyst bed in this controllably heat-transferred shift reactor reflects the different functions of the catalysts in various regions of the same reactor. It makes full use of the wide temperature range capabilities of cobalt-molybdenum-based shift catalysts, and the controllably heat-transferred shift technology represents an improvement over adiabatic and isothermic bed shift technologies. The evaluation conclusion is that the technical approach is reasonable and feasible, the technical parameters are advanced, and it has reached the international advanced level. It achieves technological improvements in traditional domestic conversion processes, reducing engineering investment and operating costs. It is particularly suitable for harsh operating conditions with high CO concentrations and high water vapor ratios, and can be used in modern coal chemical conversion units across various fields, facilitating the enlargement of such units. It is reported that this patented technology is applicable to all fields that require CO conversion, including modern coal chemical industry, traditional coal chemical industry, natural gas chemical industry, coalbed methane chemical industry, petrochemical industry, biogas chemical industry, and others. Whether it is dry coal powder gasification, which produces a high water-to-gas ratio and high CO levels in pressurized continuous gasifiers for coal slurry, or fixed-bed pressurized or atmospheric pressure gasification processes that result in a low water-to-gas ratio and low CO levels, or various process gases generated as by-products in other industrial installations (such as blast furnace gas and coking gas), this technology exhibits good adaptability. By adjusting the process parameters, it is possible to achieve various hydrogen-to-carbon ratios required for different product specifications. Wang Qingxin stated that the greatest advantage of this patented technology is its flexible process design, as well as its ease of operation and stability. It completely eliminates the occurrence of catalyst overheating or runaway reactions, thereby prolonging the catalyst’s service life and facilitating its scalability to larger scales. At the same time, this patented technology employs a stepped energy recovery system to advance the use of low-grade thermal energy and generate high-grade steam as a by-product, thereby improving the efficiency and value of the thermal energy used in conversion reactions. It features a short process flow, fewer equipment units, low resistance, and reduced investment requirements (investments can be saved by 15% to 50% compared to traditional multi-stage adiabatic conversion processes), as well as significant energy-saving effects. It can provide important technical support for the large-scale development of modern coal chemical industries in China.
Anchun Isothermal Transformation Technology Achieves “One Big and Four Highs” Author/Source: Date: 2014-06-03 Clicks: 565 Hunan Anchun High-Tech Co., Ltd. and Yangmei Group Taiyuan Chemical New Materials Co., Ltd. successfully signed contracts for the isothermal transformation process package and patented equipment. The project is progressing smoothly at present; the process package design has passed the joint review by the project owner and the main design institute, and the design of the patented equipment is nearly complete. The implementation of this project marked the first time that isothermal shift technology was applied on a large scale. Its main features can be summarized by \"one large and four highs\": large scale – a single-system isothermal shift unit is capable of handling a gas flow rate of 183,258 Nm3/h, which corresponds to the gas volume required for the production of 500,000 tons of synthetic ammonia per year; the diameter of the isothermal shift furnace is DN4600. The four highs – high CO, high pressure, high water vapor ratio, and high conversion rate. Gasification uses HTL technology, with CO reaching up to 67% ； Operating pressure 3.7 MPa ； The water vapor ratio is 1.3 ； The CO content in the transformed gas is required to be ≤0.4%; the conversion rate in the isothermal shift reactor is over 98%, with the overall system conversion rate exceeding 99%.
On December 4, 2012, the isothermal transformation process and equipment, independently developed and manufactured by Shijiazhuang Zhengyuan Tower Equipment Co., Ltd., have been in operation in the ammonia synthesis system of Shijiazhuang Zhongji Zhengyuan Chemical Co., Ltd. for 10 days. Operational data show that 250 kilograms of steam are consumed per ton of ammonia, while 580 kilograms of steam at 2.5 MPa are supplied per ton of ammonia. The CO content is kept within the range of 1.5% to 2.0%. The pressure difference has decreased from 1.3 kilograms per cubic meter in the old conversion system to 0.3 kilograms per cubic meter, resulting in a significant reduction in system resistance and meeting the requirements for energy savings and environmental protection in large-scale fertilizer production. “The successful implementation of the isothermal conversion process holds significant reference value for the technical upgrading of conversion systems in fertilizer manufacturers of the same type. At the same time, through adjustments to the process system, the isothermal shift process can be effectively applied in the high-CO shift process of large-scale ammonia synthesis plants, which also provides the technical foundation for Cangzhou Zhengyuan Company’s project to produce 600,000 tons of ammonia and 800,000 tons of urea per year. ”Qi Yongli, deputy general manager of Zhengyuan Tower Equipment, told reporters. According to the technicians, the isothermal transformation process involves placing a heat exchanger within the reactor’s catalyst bed, and using by-product steam to remove the heat generated by the reaction, thereby maintaining a relatively constant temperature in the catalyst bed. This eliminates the need for additional heat exchange and heat recovery equipment, **shortening the process flow. This process utilizes advanced converter technology, resulting in a significant reduction in system resistance ； The reaction temperature can be flexibly adjusted via steam pressure, making it simple to operate. Furthermore, due to the reduction in the number of devices, equipment investment has also **decreased**. According to Qi Yongli, traditional ammonia synthesis uses a fixed-bed batch gasification process. The CO content in semi-water gas is around 30%. For CO conversion, medium-low-low, medium-medium-low-low, and fully low conversion processes are commonly employed, with multiple reaction stages and heat exchange steps used to regulate temperature. This approach results in a relatively complex process, high heat losses, high steam consumption, and high equipment costs. With the development of the fertilizer industry, the enlargement of synthetic ammonia production facilities has become the mainstream trend both domestically and internationally. At present, there are over 40 enterprises in China that produce more than 300,000 tons of synthetic ammonia per year. Large-scale synthetic ammonia systems typically use gasification technologies such as space furnace and Shell water-coal slurry furnace; the CO content in the resulting crude gas ranges from 50% to 76%. Such high concentrations of CO render traditional shift technologies unsuitable for meeting the requirements of large-scale synthetic systems. The isothermal conversion process, with its features of simple operation, low system resistance, and high CO conversion rate, precisely meets the requirements for energy saving and environmental protection in large-scale fertilizer production. After more than a year of research and development on the isothermal transformation process, Zhengyuan Tower Equipment completed the industrial design of the isothermal transformation furnace and the associated process flow in April 2012. On November 25, the Zhongji Zhengyuan ammonia synthesis system using the isothermal shift process was successfully commissioned.
For the first time, Xinlianxin applied isothermal shift technology in a shift reactor equipped with 6.5 MPa water-coal slurry