水泥脱硝过程控制系统研究

发布时间：2018-05-10 07:03

本文选题：水泥脱硝 + 预测控制　；参考：《济南大学》2017年硕士论文

【摘要】：氮氧化物的排放是伴随在水泥生产中不可避免的过程,目前我国面临严峻的大气污染问题,水泥行业氮氧化物的排放受到国家日趋严格的限制,水泥企业面临很大的环保压力。水泥行业脱硝普遍采用SNCR技术,该技术具有投资少和环境效益高的特点,但SNCR技术在实际的脱硝应用中仍存在诸多问题,如脱硝效率不高、氨水消耗量大、依赖合适的温度窗口以及受烧成系统影响较大等等。目前我国水泥脱硝控制水平较低,多数为人工控制或常规PID控制,无法有效解决上述问题,对氮氧化物浓度的控制很难达到稳定的效果,并且喷氨量调节不合理,容易造成氨水的浪费。为了降低氮氧化物浓度,保证环境质量达标,同时控制合理的喷氨量,降低企业运行成本,水泥脱硝采用先进控制技术成为必然趋势。随着控制技术的发展,先进控制技术如预测控制和专家规则越来越多的在工业现场得到实际应用。预测控制对模型的精度要求低,对模型失配有较强的适应能力,能有效克服滞后问题,消除稳态误差,在火电等行业的脱硝工程中得到了应用,因此预测控制是水泥脱硝控制技术的一个很好的选择。专家规则通过总结人工经验,在复杂情况下有较好的控制效果。本文通过对水泥脱硝工艺的分析,并结合现场低排放和减少氨水消耗的实际需求,分析了脱硝过程本身存在纯滞后以及过渡过程时间较长的典型特征以及烧成系统对脱硝过程的影响影响较大等典型问题,总结了现有脱硝控制技术存在的喷氨量调节不合理、无法有效克服滞后以及氮氧化物浓度不稳定等问题,提出了结合预测控制和专家规则的水泥脱硝控制系统方案,并根据方案进行了深入的研究,利用现场数据建立了喷氨量-氮氧化物浓度预测模型,根据动态矩阵控制理论(Dynamic Matrix Control,DMC)设计了基于脱硝过程模型的预测控制器,总结专家经验制定了专家规则,使脱硝控制不再盲目依赖NO_x浓度的反馈值,喷氨量的调节更有前瞻性。根据仿真和现场的调试确定了脱硝控制器各参数,并与常规PID方法进行了对比仿真,结果表明基于预测控制的水泥脱硝控制效果优于常规PID控制效果。本文根据SNCR工艺以及现场实际条件,设计了氨水制备与供给控制系统,进行了点号表的统计、控制器和模块配置、PLC梯形图编程以及上位机组态,实现了氨水的稳定供给。本文以提高氮氧化物浓度控制精度和提高喷氨量调节合理性为目标,以水泥脱硝过程控制系统方案为基础,依托水泥厂现有DCS系统,进行了喷氨量优化控制系统的结构设计、数据库的设计开发和优化控制软件的开发,实现了水泥脱硝过程控制系统的工程化,详细介绍了关键算法和各模块功能的实现过程。经过不断地修改完善以及现场调试,水泥脱硝过程控制系统成功运行,实现了稳定、低浓度的氮氧化物浓度控制和合理、精确的喷氨量调节,减轻了操作员的劳动强度,提高了NO_x浓度控制精度,降低了水泥生产过程的脱硝成本,提高了水泥企业的经济效益和社会效益。
[Abstract]:The emission of nitrogen oxides is an inevitable process in the production of cement. At present, China faces severe air pollution problems. The emission of nitrogen oxides in cement industry is strictly restricted by the state, and the cement enterprises are facing great environmental pressure. SNCR technology is widely used in the cement industry. The technology has less investment and environment. There are many problems with high efficiency, but there are still many problems in the application of SNCR technology in actual denitrification, such as low denitrification efficiency, large amount of ammonia water consumption, relying on appropriate temperature window and burning system, and so on. At present, the control level of cement denitrification is low in our country, most of which are human work control or conventional PID control, which can not effectively solve the above questions. It is difficult to achieve a stable effect on the control of nitrogen oxide concentration, and it is easy to cause the waste of ammonia water. In order to reduce the concentration of nitrogen oxide, ensure the quality of the environment to meet the standard, at the same time control the reasonable amount of ammonia and reduce the operation cost of the enterprise, the advanced control technology of cement denitrification is the inevitable trend. With the control of the cement, the advanced control technology is the inevitable trend. With the control of the cement, the advanced control technology is the inevitable trend. With the control of the cement, the advanced control technology is the inevitable trend. More and more advanced control technologies, such as predictive control and expert rules, have been applied in the industrial field. The precision of predictive control is low, and the model is equipped with a strong adaptability. It can effectively overcome the lag problem and eliminate the steady-state error. It has been applied to the denitrification project in the thermal power industry and other industries. This predictive control is a good choice for the control technology of cement denitrification. By summarizing the manual experience, the expert rule has better control effect in complex conditions. This paper analyzes the process of denitrification by analyzing the cement denitrification process and combining the actual demand of low emission and reduction of ammonia water consumption in the field, and analyses the pure delay in the process of denitrification and the existence of the pure lag in the process of denitrification. The typical characteristics of the longer transition process and the influence of the firing system on the denitrification process are more typical. The problems existing in the existing denitrification control technology are unreasonable, the lag and the nitrogen oxide concentration are not effectively overcome, and the cement removal with the combination of predictive control and expert rules is put forward. The scheme of the nitrate control system is studied. The prediction model of the ammonia content and nitrogen oxide concentration is established by the field data. The predictive controller based on the dynamic matrix control theory (Dynamic Matrix Control, DMC) is designed based on the model of the denitrification process. The expert rules are drawn up to make the denitrification control not. Again, the feedback value of NO_x concentration is blindly dependent, and the regulation of spray ammonia is more forward-looking. According to the simulation and field debugging, the parameters of the denitrification controller are determined and compared with the conventional PID method. The results show that the effect of the cement denitrification control based on the predictive control is better than the conventional PID control effect. This paper is based on the SNCR process and the site. In the actual conditions, the ammonia water preparation and supply control system is designed. The statistics of the dot meter, the controller and the module configuration, the PLC ladder diagram programming and the upper computer configuration are used to realize the stable supply of ammonia water. In this paper, the control system of cement denitrification process is aimed at improving the control precision of the nitrogen oxide concentration and improving the rationality of the regulation of the injection of ammonia. Based on the unified scheme, based on the existing DCS system in the cement plant, the structure design of the optimization control system for the injection of ammonia is carried out, the design and development of the database and the development of the optimization control software have been developed to realize the engineering of the control system of the cement denitrification process. The key algorithm and the realization process of the function of each block are introduced in detail. After continuous modification, the system is improved and perfected. As well as field debugging, the control system of the cement denitrification process has been successfully run, realizing the stability, the low concentration of nitrogen oxide concentration control, reasonable and accurate ammonia injection regulation, reducing the labor intensity of the operator, improving the NO_x concentration control precision, reducing the cost of denitrification in the cement production process, and improving the economic benefit of the cement enterprise. Social results.

【学位授予单位】：济南大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ172.6;TP273

【参考文献】