The development of ammonia synthesis technology focuses on scaling up

Thread Content

Development of ammonia synthesis technology focuses on larger scale / Author/Source: China Chemical Industry News Date: 11-01-2017 Clicks: 7 At present, moving toward larger scales has become the main trend in the development of ammonia synthesis technology. Foreign technologies continue to make advances in terms of larger and super-large scale operations as well as energy savings and consumption reduction, and progress in China is also rapid. In addition, research is also ongoing in areas such as ammonia synthesis catalysts, electrochemical ammonia synthesis at normal temperature and pressure, and chemical simulation of biological nitrogen fixation as techniques for ammonia production. This is information obtained by a reporter from China Chemical Industry News at the 2017 (5th) China International Fertilizer Market Forum and the First High-Level Forum on the Ammonia Synthesis Industry Chain, which were held in Shanghai recently. Foreign countries are at the forefront in this area. Li Zhijian, assistant to the director of the Petroleum and Chemical Industry Planning Institute, pointed out that current developments in ammonia synthesis technology focus on two main aspects: first, improving the net value of ammonia and energy efficiency through process optimization, with a gradual move toward larger-scale production ； Second, continue to expand the range of ammonia synthesis catalysts, with breakthroughs in synthetic catalysts such as new iron-based catalysts, cobalt-containing catalysts, and ruthenium catalysts. According to Li Zhijian, the current mainstream scale of new ammonia synthesis plants used abroad for upgrading old facilities and replacing smaller units with larger ones is 3,000–4,000 tons per day, with a trend toward 5,000 tons per day. Representative low-energy ammonia production processes used internationally for large-scale ammonia synthesis plants include the U.S. KBR process, the Danish Topsoe process, the Swiss Cassali process, the German Wood process, and others. Among them, the plant under construction by Danish company Topso has a maximum capacity of 3,500 tons per day, and the process package design for 5,000 tons per day has been completed ； Iron-based catalysts are still recommended as catalysts, and the development of ruthenium catalysts based on BN and Si3N4 is underway, but they have not yet been put into industrial use. The Swiss Cassali process is a type of ammonia synthesis technology that is widely used in China at present. This process has been applied in several cases related to the renovation of synthesis towers in large-scale ammonia synthesis plants using the Kellogg process in China; it has also been used in projects to renovate synthesis towers equipped with ruthenium catalysts in heat-wall towers, enabling the accumulation of extensive experience in design and operational aspects. German company Wood developed a two-pressure ammonia synthesis process, and the world’s first ammonia synthesis plant with a capacity of 3,300 tons per day was built. Our country is making rapid progress; currently, ammonia synthesis plants with a capacity of 600,000 to 700,000 tons per year in our country have been manufactured domestically. Li Zhijian said that due to issues such as poor gas quality resulting mainly from coal gasification processes and reciprocating compressors, relatively small plant scales, and high requirements for operational flexibility, China’s ammonia synthesis technology has, over the years and alongside overall technological advancements, developed a characteristic approach specific to the country – namely the use of clean gasification for ammonia production. With extensive practical experience and numerous cases available, the conditions for developing larger-scale facilities have now been preliminarily met. For example, Nanjing Guochang has built more than 30 ammonia synthesis units in China, with the largest capacity reaching 600,000 tons per year, and has completed a project for ammonia synthesis with a capacity of 1 million tons per year. Nanjing Jutuo has built more than 20 ammonia synthesis units in China, the largest of which have a capacity of 2,000 tons per day, with the potential to reach 2,400 tons per day (i.e., 800,000 tons per year); its ammonia synthesis process package with an annual capacity of 1.2 million tons has also been developed. Hunan Anchun has built multiple ammonia synthesis plants in China, the largest of which has an annual capacity of 800,000 tons. Yangmei Zhengyuan has completed the 600,000 tons per year ammonia synthesis project at Yangmei Cangzhou Zhengyuan Fertilizer Co., Ltd. Li Zhijian said that in the near to medium term, China’s ammonia synthesis technology will also adapt to the trend toward larger-scale ammonia synthesis plants, with the development of more energy-efficient processes on a larger scale ； There is an even stronger emphasis on regulating investment, energy conservation, and environmental protection. The energy consumption for ammonia synthesis will continue to approach the theoretical energy consumption. According to the reporter’s research, during the 13th Five-Year Plan period, the mainstream capacity of new ammonia synthesis plants in China was 600,000 tons per year. The demonstration project for domestic production of 1 million tons per year of synthetic ammonia has been included in the Ministry of Industry and Information Technology’s \"Development Plan for the Petrochemical and Chemical Industries (2016–2020)\". Three areas are under exploration, Li Zhijian explained. Research on ammonia synthesis technology is focused on the following three areas: first, ammonia synthesis catalysts, particularly those with high activity at low temperatures such as ruthenium-based catalysts, in order to enable ammonia synthesis at lower temperatures, lower pressures, and with higher efficiency. At present, at the laboratory scale, this catalyst can achieve an ammonia yield of over 10% at 200°C and 5 MPa. The second is the electrochemical synthesis of ammonia at normal temperature and pressure. At present, the use of electrochemistry in ammonia synthesis is still in the exploratory stage; however, if it is combined with renewable energy in the future, it holds good prospects for application. Third is chemical simulation of biological nitrogen fixation, which is still in the exploratory stage. Li Zhijian said that once breakthroughs are achieved in these three types of technologies, they will have a transformative impact on the synthetic ammonia industry, leading to significant reductions in investment costs, emissions, and energy consumption.