洁净煤技术

2020, v.26;No.130(06) 229-236

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烟气脱硝用尿素水解制氨技术理论与实践
Theory and practice of ammonia production by hydrolysis of urea for flue gas denitration

孙立群;吴冲;
SUN Liqun;WU Chong;China Huadian Engineering Co.,Ltd.;

摘要(Abstract):

火力发电和石油石化等行业的烟气必须进行脱硝处理,将NOx被还原成N2后被排放到大气中,脱硝还原剂一般为液氨和尿素。由于液氨存在重大的安全隐患,存储和运输均存在一定的限制,并已被列为重大危险源,因此目前还原剂多选择尿素。尿素分解制氨包括尿素热解技术和尿素水解技术,尿素水解技术可分为尿素普通水解和催化水解技术。通过研究不添加催化剂的尿素普通水解技术和添加催化剂的尿素催化水解技术的反应机理,以及反应速率、水解率、能耗随机组负荷变化等,发现尿素催化水解制氨技术由于添加了催化剂,改变了化学反应的中间过程,在相同温度下,催化剂的加入降低了反应活化能,反应速率常数减小,反应速度提高,响应速度加快,达到低温运行的效果,从而能耗降低,尿素利用率可达99%以上;腐蚀减小,解决了普通水解无法满足机组快速变化的需氨量和高温运行造成的腐蚀。催化剂与尿素反应生成一种中间产物,中间产物又分解生成催化剂,因此催化剂在整个反应中无消耗,不会增加系统的运行成本。
Flue gas denitrification treatment must be carried out for flue gas in thermal power generation and petrochemical industries.When NOxis reduced to harmless N2,it is then discharged into the atmosphere. Denitrification reducers are usually liquid ammonia and urea. Due to the major security hidden danger of liquid ammonia,there are certain limits on storage and transport,and liquid ammonia has been listed as one of major hazards. Urea is the most choice for reducing agent at present. Ammonia production from urea decomposition includes urea pyrolysis and urea hydrolysis technology,and urea hydrolysis technology is divided into ordinary urea water solution urea and catalytic hydrolysis technology. By studying the reaction mechanism of urea ordinary hydrolysis technology without catalyst and urea catalytic hydrolysis technology with catalyst,as well as the change of reaction rate,hydrolysis rate and energy consumption random group load,it is found that adding urea catalytic hydrolysis catalyst manufacturing technology by adding ammonia catalyst changes the chemical reactions in the middle of the process. At the same temperature conditions,the addition of catalyst makes chemical reaction activation energy reduced,the reaction rate constant,reaction speed and response speed faster,so as to achieve the effect low-temperature operation,thus resulting in lower energy consumption and increasing urea utilization rate of more than 99%; Corrosion is reduced,which solves the rapid change of ammonia demand and corrosion caused by high temperature operation that the ordinary hydrolysis can not meet. It is found that an intermediate product is formed by the reaction between the catalyst and urea. And the intermediate product is decomposed into a catalyst,which is not consumed in the whole reaction and does not increase the operating cost of the system compared with the ordinary hydrolysis technology.

关键词(KeyWords): 烟气脱硝;尿素催化水解;尿素普通水解;催化剂
flue gas denitration;catalytic-hydrolyzation of urea;hydrolyzation of urea;catalyst

Abstract:

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作者(Author): 孙立群;吴冲;
SUN Liqun;WU Chong;China Huadian Engineering Co.,Ltd.;

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DOI: 10.13226/j.issn.1006-6772.EP20070801

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