The trial operation of the urea-to-ammonia production project at Chang’an Yiyang Company was successful

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Successful trial operation of urea-based ammonia production project at Chang’an Yiyang Company Author/Source: Shaanxi Coal Group Date: 2022-03-26 Clicks: 15 Recently, Chang’an Yiyang Company successfully completed the trial operation of the urea-based ammonia production system using four units; the system is now operating normally, the equipment is in good condition, and the emission concentration of nitrogen oxides at the outlet is less than 50 milligrams per cubic meter, meeting **environmental standards. This marks the successful completion of the trial operation of the project to replace liquid ammonia with urea as the denitration reagent at Chang’an Yiyang Company. This project is one of the major safety and environmental protection technological upgrade projects undertaken by Chang’an Yiyang Company, with an investment of around 26 million yuan. With increasingly stringent environmental policies, the controls on flue gas emissions from coal-fired power plants are becoming more strict; the emission standard for nitrogen oxides in boiler flue gas has been reduced from 100 milligrams per cubic meter to 50 milligrams per cubic meter. At the same time, regarding the control of major hazard sources, liquid ammonia, which is used as a denitration reducing agent, has faced more restrictions. Ammonia is a toxic substance that can burn the skin, eyes, and mucous membranes of the respiratory organs; excessive inhalation of it can cause lung swelling, leading to death. There are also strict standard regulations for the transportation and storage of liquid ammonia; storage quantities exceeding 10 tons are considered major hazard sources. To eliminate the major hazards in the ammonia production area, Chang’an Yiyang Company converted the denitration reagent to urea for ammonia production, changing the liquid ammonia process to a urea hydrolysis process for ammonia generation. In this revised urea hydrolysis process, urea, being a solid that is soluble in water, can be completely decomposed into ammonia gas at high temperatures, making it safer and more convenient for transportation and storage. To complete the denitration retrofitting of the four units efficiently and to high quality, Chang’an Yiyang Company carried out tasks such as bidding and design review as planned since the project began. In May 2021, construction of the urea plant started, and the denitration urea-to-ammonia project officially entered the phase of actual construction. To ensure the project is put into operation on schedule, strict attention is paid to safety management, quality management, and schedule management by focusing on the source of issues at each level, giving priority to safety and quality, strictly controlling key milestones, exercising comprehensive supervision, and implementing rigorous assessments. At the same time, the company planned ahead, made use of the time available, and took advantage of the short period required for unit adjustments to complete the technical upgrades on the urea ammonia injection systems of all four units, enabling them to be connected to the system on time and ensuring that the units could start up as scheduled. During the commissioning of this project, the urea hydrolysis and ammonia injection tests were successful on the first attempt. Throughout the 168-hour continuous operation of the denitration system, all environmental protection parameters remained within acceptable limits. Today, the technical upgrade project to convert liquid ammonia into urea has been put into operation successfully and efficiently.