Low-temperature waste heat recovery technology for sulfuric acid plants
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After more than a decade of development and practical application, the low-temperature waste heat recovery technology for sulfuric acid production in our country is now ready for widespread use in the sulfuric acid industry. The indigenous technology has achieved a significant leap toward industrialization, which has led to a substantial reduction in the licensing fees for similar foreign technologies. At the Sulfuric Acid Technology Exchange Conference held in Yangzhou from May 16th to 17th, industry experts predicted that, with further progress in energy conservation and emission reduction efforts, this technology is likely to be widely adopted in the sulfuric acid industry within three years. Wu Xuemei, secretary-general of the China Sulfuric Acid Industry Association, said that according to incomplete statistics, 16 sulfur-based acid production enterprises in China currently have systems for recovering waste heat at low temperatures installed in their facilities with a capacity of around 11.5 million tons, and these systems are already in use ； 18 enterprises with production capacities of around 10 million tons each will be equipped with low-temperature waste heat recovery systems ； In the future, 10 million tons of production capacity will be available to be equipped with this system, and at that time, the heat recovery rate for sulfur-based acid production, which is currently 80%, will increase to over 90%. Ye Jixuan, chairman of Shanghai Aogli Environmental Protection Engineering Co., Ltd., said that sulfuric acid production facilities should become green energy plants that not only produce sulfuric acid products but also generate large amounts of heat energy at high, medium, and low temperatures. With the tightening of energy supplies and increasing market competition, there is an ever greater need to make full use of the low-temperature heat energy from sulfuric acid production units, in line with China’s national conditions, in order to enhance the viability of sulfuric acid manufacturers and enable this industry to contribute to **energy conservation and emission reduction. Yu Xiangdong, a professor-level senior engineer at Sinopec Nanjing Engineering Co., Ltd., explained that since the Nanjing Chemical Research Institute began working on technologies for utilizing low-temperature heat energy in sulfuric acid production in 2005, 15 such systems have been successfully deployed, with excellent operational results. For example, the 250,000-ton-per-year sulfuric acid production plant in Shandong Bo Feng and the 800,000-ton-per-year sulfuric acid production plant in Guiyang Sinochem KaiPhos both utilize technology developed by Nanjing Research Institute of Chemical Industry. Since they came online last year, they have been operating steadily, with steam generation rates per ton of sulfuric acid of no less than 0.48 and 0.52 respectively; all their performance indicators are at world-class levels. The low-temperature waste heat recovery technology developed by Ogley Company is used to raise the temperature of the circulating absorbent acid, thereby increasing the quality of thermal energy and enabling the production of low-pressure saturated steam. By integrating process design, material research and development, and equipment manufacturing, they have developed and implemented various low-temperature waste heat recovery process technologies with different procedures. Each of these technological processes has its own advantages and is suitable for either new projects or the renovation of existing plants. Since the first set of low-temperature waste heat recovery units was put into operation in 2007, the company has designed and deployed more than a dozen such units, achieving excellent recovery results and economic benefits. Li Chonggui, representative of large-scale sulfuric acid producers and assistant general manager of Yuntianhua International Chemical Co., Ltd., is also full of confidence in the promotion and application of these two domestically developed technologies; he believes that the investment can be recouped within two to three years, while energy conservation and emission reduction can also be achieved.
They all involve \"digesting, introducing, and absorbing\" foreign technologies, demonstrating an \"innovative\" spirit! ! !
The HRS system mainly consists of four units: the HRS heat recovery tower, the HRS acid circulation pump, the HRS boiler, and the HRS diluter. When installing the HRS system in a newly built sulfuric acid plant, an HRS heat recovery tower equipped with upper and lower packing layers is used in place of the traditional single-absorption tower, adopting a single-tower configuration； When adding an HRS system to an existing sulfuric acid plant, an HRS heat recovery tower is installed in front of the original first absorption tower, with the original first absorption tower being used as the second stage of the HRS heat recovery tower, resulting in a dual-tower configuration. The circulating acid ω(H2SO4) is 99.1%-99.6%, and the temperature is 200-220°C. To prevent corrosion, the HRS system strictly controls the circulating acid temperature and concentration within the aforementioned operating ranges, and uses the ZeCor series of specialized alloys that are resistant to corrosion under these specific conditions. The HRS system can recover approximately 0.5 t/t of saturated steam at 0.3–1.0 MPa, depending mainly on the sulfur dioxide concentration in the converter and the steam pressure of the HRS boiler. The 1,000 kt/a sulfuric acid production plant equipped with an HRS system at Shuangshi (Zhangjiagang) Fine Chemicals Company was put into operation in 2005; the HRS system generates 0.548 t/t of saturated steam at 1.0 MPa. The American company Menomonee has designed 33 HRS systems worldwide; its production processes and operational controls are mature and reliable, and it possesses extensive production experience, although the cost is relatively high. The DWHS system mainly consists of six units: the DWHS tower, acid circulation tank, acid circulation pump, evaporator, acid cooler, and venturi diluter, which are installed in front of the absorption tower. The technology and equipment of the DWHS system are entirely domestically produced; the temperature of the circulating acid is controlled at 200°C, and the ω(H2SO4) level is maintained between 98.6% and 99.6%. The DWHS system can recover 0.43–0.50 tons of saturated steam at 1.0 MPa per ton of input material. The 300kt/a sulfuric acid production plant equipped with a DWHS system by Zhejiang Zhongsheng Chemical was put into operation in March 2007; the DWHS system generates saturated steam at 0.7 MPa (the pressure level required by the client), in quantities of over 0.42 t/t.
Hello, whose technology is the DWHS system?
DWHS is a technology developed by Shanghai Aogli Environmental Protection Engineering Co., Ltd. On November 10, 2008, the Zhejiang Provincial Economic and Trade Commission issued a certificate to Zhejiang Aogli Energy Conservation and Environmental Protection Technology Co., Ltd., recognizing that the low-temperature waste heat recovery (DWHS) technology for producing sulfuric acid from sulfur developed by this company had been awarded the title of “New Industrial Technology in Zhejiang Province”.
DWHRS is a technology successfully developed by Nanhua Company
The DWHRS of Nanhua Company consists of main equipment such as high-temperature absorption towers, boilers, heat exchangers, mixers, high-temperature circulation tanks, deaerators, and boiler feed water pumps, along with related auxiliary facilities.
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