Application Study On Liquid Ammonia To Urea Used As Denitration Reductant In Guoneng Xuzhou Power Plant

Changing the denitration reductant from liquid ammonia to urea for ammonia production in power plants is an important measure to implement the safe development concept of the Party Central Committee and ensure the safety of people’s lives and property.The original denitration unit of 2 × 1000 MW ultra supercritical unit of Guoneng Xuzhou Power Generatin Co.,Ltd.(hereinafter referred to as Guoneng Xuzhou Power Plant)adopts SCR process and meets the ultra-low emission standard.It is planned to use urea to produce ammonia instead of liquid ammonia.The main processes of ammonia production from urea decomposition for denitrification in power plants include urea pyrolysis and urea hydrolysis.The urea hydrolysis method can be divided into ordinary hydrolysis and catalytic hydrolysis according to whether catalyst is added.Based on the application of flue gas denitration reductant liquid ammonia to urea technology in Guoneng Xuzhou Power Plant,this thesis adopts the method of combining theory with practice to conduct analysis and research,and seeks a technical route and equipment selection scheme more suitable for the actual situation of generator units,so as to provide technical support for the improvement of denitration reducing agent technology of domestic similar units.Firstly,the thesis briefly introduces and compares the existing denitration system equipment of Guoneng Xuzhou Power Plant and various urea ammonia production processes.Through process comparison and selection,it is concluded that the urea hydrolysis process is the best one for flue gas denitration in combination with the actual situation in Xuzhou Power Plant;At the same time,the unique advantages of urea pyrolysis process in terms of economy and reliability are also presented.Based on the urea hydrolysis process used for flue gas denitration,the thesis calculates the basic capacity of the urea hydrolysis ammonia production process equipment,introduces the relevant system equipment of the denitration process,and analyzes the site selection,materials,facilities and supply in detail in combination with the actual situation of the power plant site.The thesis analyzes and studies the relevant influencing factors of the flue gas denitration redutant liquid ammonia to urea.The analysis shows that the fundamental influence of the change of coal type on the emission of nitrogen oxides is the main factor affecting the application effect of liquid ammonia to urea.The upcoming technical transformation of Xuzhou Power Plant,such as zero discharge of desulfurization wastewater and wide load denitration,is also an important factor affecting the selection of liquid ammonia to urea process and equipment layout.At the same time,the thesis also summarized the main problems existing in process of the ammonia production from urea hydrolysis based on the relevant literature and research results.The thesis focuses on the comparison and analysis of the selection of hydrolysis reactor and dilution air in the urea hydrolysis process,especially for the ordinary hydrolysis and catalytic hydrolysis that the power plant focuses on,from the aspects of corrosion resistance of materials,response speed,initial investment and production and operation costs,etc.At the same time,the thesis makes statistical analysis on the actual ammonia consumption change of Guoneng Xuzhou Power Plant and two 1000 MW level units,and draws the relevant conclusion that catalyst is not the decisive factor for urea hydrolysis technology to meet the denitration operation demand.Finally,the thesis introduces and analyzes the results of the application of flue gas denitration reductant liquid ammonia to urea technology,and analyzes the response speed limit of the urea hydrolysis reactor based on the actual operation data of the unit,which further verifies the rationality of using ordinary hydrolysis technology.