Xi’an Jiaotong University
Report on the topic selection of master's degree thesis in engineering
Thesis title:
Last name:
Research direction:
Instructor:
Entry time: September 2003
Topic selection report time: May 2006
First, the scientific basis and significance of this research topic (including scientific significance, research survey at home and abroad, level and development trend, academic thought and theoretical basis. )。
I. Reasons, Purpose and Significance of Project Establishment
There are many synthetic ammonia plants in China, but the control level of them is relatively low. Most manufacturers still stay at the semi-automatic level, and many still rely on manual control. The common problems are: high energy consumption, high cost, long process and low level of automatic control. The products produced in this production situation have high cost and poor market competitiveness, so most fertilizer industries are in a state of meager profit or even loss. In order to change this state, besides changing the backward technological process, it is an effective method to realize the optimal control of the plant production process.
Synthetic ammonia plant is the basis of chemical fertilizer production in China. To improve the automatic control level of the whole ammonia production plant, only by further stabilizing production and reducing energy consumption can we reduce costs and increase efficiency. Realizing the optimization of synthetic ammonia plant is one of the effective measures with less investment and quick results.
The significance of optimal control of ammonia plant lies in improving the automation level of the whole ammonia plant, giving full play to the advantages of optimal control under the existing process conditions, and making the whole production run in the best state for a long time. At the same time, optimizing the application of the system can also save the consumption of raw materials, reduce energy consumption, improve the qualified rate of products and enhance the market competitiveness of products.
Second, the general situation and development trend at home and abroad
Automation technology, including production process control automation and transaction management automation, belongs to the rapidly developing and increasingly mature high technology in the world today. The continuous development of automation technology has also enriched the development of various control software, especially the optimal control has moved from theory to practice.
With the rapid development of microcomputer, automation theory and information technology, the DCS system developed by foreign enterprises with the latest PC technology has been widely used in production devices of various industries, especially in the application of DCS, and many practical optimization softwares have been developed.
In foreign countries, the development of synthetic ammonia production can be roughly divided into five stages: ⅰ. The stage of invention; Ⅱ. Technology promotion stage; Ⅲ. The changing stages of raw material structure; Ⅳ Single series large stage; ⅴ energy saving and consumption reduction stage. The automation technology adapted to the process is also developing constantly, especially in the third stage, different processes put forward different requirements for control tasks. In view of the instrument conditions and the development of control theory at that time, some simple control loops were mainly set for some important process parameters, and gradually developed into some cascade and proportional control loops. such as
As an advanced control scheme, its popularization is inseparable from the development of computers. With the development of computer, on the one hand, some control systems can be effectively realized, on the other hand, it also provides a hardware foundation for optimal operation. According to the characteristics of synthetic ammonia plant, some nonlinear filters were successfully controlled by computer-aided optimization, which improved the production of synthetic ammonia obviously. At present, many synthetic ammonia plants in the world have adopted computer control or DCS system. The control level of synthetic ammonia plant has reached a certain level, and the research and application of optimization and computer management have reached a certain level, which has increased the output, reduced the cost and improved the efficiency.
Second, the research methods and technical routes to be adopted (including the overall safety of the research work)
Arrangement and progress, calculation, experimental methods and steps and their feasibility demonstration, possible problems and solutions. )
The research methods adopted are as follows: firstly, theoretical research is carried out, and the equipment and key circuits that need to be optimized are analyzed from the process requirements and production equipment of synthetic ammonia. Starting from the key loop, the related parameters of each optimization parameter are analyzed in detail, and the control methods before this parameter optimization are understood and analyzed. On this basis, a new control method is proposed and optimized by advanced control method. Write control scheme and draw control block diagram. On this basis, the control program is compiled. Input the control program into DCS system for off-line and on-line debugging, and put the optimized program into operation. Record the parameter operation curve before the optimal control system is put into operation and the operation curve after the optimal control system is put into operation. Analyze the operation of the optimization system and put forward further improvement suggestions. Repeat the above process for the second experiment. Until satisfactory results are achieved.
Work plan: make detailed technical implementation plan (1 project demonstration and preliminary investigation, 2 scheme design and demonstration, 3 detailed implementation plan preparation, 4 drawing relevant design drawings, etc. ); Compile software; Software debugging and trial operation; Software operation evaluation; Operation training and technical exchange; Project evaluation and archiving data. It takes about 1 year to complete the above work.
Possible difficulties and solutions: The practical difficulties that may be encountered are: the process differences of different manufacturers make the optimization system not universal, which needs to be further revised and supplemented according to the specific situation and field conditions. Due to the complexity of the process, the same controlled parameter can not achieve the optimization effect due to some uncontrollable factors such as the change of raw materials, the advancement of time and the change of composition. As far as possible, all the influencing parameters are introduced into the optimization system. Let the uncontrollable factors be as few as possible.
Three. Features and innovations of this project.
Since 1980s, computer control system and DCS system have been gradually introduced into the production process control in China, especially in the chemical fertilizer industry. More than 90% large chemical fertilizer enterprises have introduced foreign DCS systems, more than 80% medium chemical fertilizer enterprises have also applied foreign DCS systems, and 30-40% small chemical fertilizer enterprises have also introduced domestic and foreign control systems on some devices. Judging from the imported DCS system, most enterprises only replace the original instrument system with DCS system, and a few enterprises have done some development work in individual circuits. Generally speaking, the application of DCS is far from exerting its powerful functional advantages. For a synthetic ammonia plant, the biggest feature of the plant is that the process flow is long, the reaction is carried out at high temperature and pressure, the automatic design is relatively simple, and the manual operation rate is high. In order to better control the operation of the whole ammonia plant and make the whole production achieve the purpose of energy saving and stable high yield, it is necessary to further develop and utilize the powerful software function of DCS system and apply some advanced control algorithms in modern control theory to the ammonia plant on the basis of the original preliminary design and according to the needs of process operation.
Fourth, the expected research results.
Because the chemical fertilizer production plant is a comprehensive, large-scale and continuous production mode, the process structure is complex. The continuous expansion of the scale of synthetic ammonia plants in China will have a great impact on whether such plants can achieve optimal design and control, and on infrastructure investment, safe production and product cost. The optimization control software and hardware of synthesis section, shift section and gas-making section of synthetic ammonia plant aims at saving energy and reducing consumption by means of computer, and improving the survival and competitiveness of chemical fertilizer plant.
Because small and medium-sized fertilizer plants in China are all non-optimal designs, each equipment has not been formally simulated, and the transformation of the device has been going on. The operating conditions (process parameters) are basically determined by experience, which is difficult to optimize and has great potential.
Optimal control is to optimize operating parameters online. Under the existing technological process and equipment conditions, the operating parameters of the production unit are optimized by computer to achieve the purpose of saving energy, reducing consumption, reducing the production cost of tons of ammonia and maximizing the profit of the unit. Optimal control is a new effective means for enterprises to tap potential and increase efficiency. With the help of mathematical model and multivariable optimization algorithm, the online optimal control of gasification, transformation and synthesis is realized by establishing the mathematical model of gasification, transformation and synthesis system.
5. Existing research basis.
Tianhua Chemical Machinery Automation Research and Design Institute is a professional research unit engaged in chemical automation and instrumentation for a long time. Engaged in chemical fertilizer process control for more than 30 years. There is a professional research team with strong technical force. Since 1980s, we have been committed to the development and application of optimized control system. We have designed and applied DCS system in Liujiaxia Fertilizer Plant, Hebei Yixian Fertilizer Plant, Anyang Fertilizer Plant, Liuzhou Fertilizer Plant, Shandong Hongri Group and other synthetic ammonia plants, and achieved satisfactory results. He has accumulated rich experience in DCS development, and successively developed and applied YEWPARK MARK, μXL, CENTUM-XL, CS- 1000 of Yokogawa Company, TDC-2000, TDC-3000, Micro-3000, GUS of Honey well Company of the United States, etc. RS3, Prova Cox; Rosement company of the United States; PLC, PCS of Siemens, Germany, etc.
I have been engaged in the research and application of chemical fertilizer detection and control since graduation. Has undertaken the design, configuration, programming and application of DCS system in Anyang Chemical Fertilizer Plant, Liuzhou Chemical Fertilizer Plant, Shandong Hongri Group, Jinchang Chemical Industry Group and other units. Advanced control methods have been successfully applied in some control loops. Satisfactory results have been achieved. Some experience and methods have been accumulated in system integration and control optimization. In addition, with the support and help of my tutor and colleagues, I believe this project will be done well through hard work.
VI. Main reference catalogue.
1 Q&A on production and operation of small ammonia plant; Yang Chunsheng, Chemical Industry Press.
2. Production technology and operation of small synthetic ammonia plants; Wang Yang Baohe, Chemical Industry Press.
3 Honeywell TDC-3000 system operation manual.
Design and application of distributed control system; Liao, Tsinghua University Publishing House.
5 "new control system"; Yu Jinshou, Chemical Industry Press.
6. Modern control theory foundation; Wang, National Defense Industry Press.
7 Essays on Chemical Instruments and Automation
Proceedings of the 5th National Chemical Fertilizer Instrument Automation Technology Exchange Conference: Chemical Fertilizer Department of Ministry of Chemical Industry.
Qi Xilin's 9 Papers on DCS, PLC and Fieldbus.
Seven. Deputy tutor's opinion
Assistant tutor (signature):
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Eight, the tutor's opinion
Tutor (signature):
date month year