Research On Control Technology Of Underground Coal Gasification Equipment Based On Coiled Tubing

With the development of the times,today’s society is increasingly pursuing the clean use of energy.China is rich in coal resources,but it is faced with such outstanding problems as high mining difficulty,low combustion efficiency and large environmental pollution.Underground coal gasification technology can effectively solve these problems.Its principle is to use oxygen,air and water vapor as gasification agents to carry out controlled combustion of underground coal and convert it into combustible gas with carbon monoxide,hydrogen and methane as main components.The traditional underground coal gasification technology uses conventional oil pipes.This paper makes a special research on the control technology of underground coal gasification equipment by replacing conventional oil pipes with coiled oil pipes for a certain underground coal gasification project in Inner Mongolia.Firstly,the development status of control technology for underground coal gasification equipment at home and abroad is analyzed and summarized,and the principle of underground coal gasification technology based on coiled tubing is deeply analyzed,and the corresponding control scheme is formulated.By comparing the advantages and disadvantages of various remote communication technologies,the selection of communication modes is completed.In view of the shortcomings of traditional PID control,a strategy of adjusting the concentration of marker gas in underground coal gasification by using fuzzy PID controller is proposed,and two control algorithms of traditional PID and fuzzy PID are simulated and analyzed by Matlab software.The results show that the fuzzy PID controller can effectively improve the control precision and other performances.In order to improve the utilization rate of resources,the idea of using simulation analysis technology to determine the withdrawal distance of coiled tubing is proposed in order to improve the scientific decision-making.With the help of Workbench,a simulation model of underground coal gasifier in a coalfield was established.Fluent was used to simulate the coal combustion process in the gasifier.Combined with previous experience,the distance for coiled tubing to withdraw each time was determined to be 6 meters.Finally,according to the determined control and communication scheme,the hardware design of the control system is completed.The hardware of the control system includes four parts: the minimum system of single chip microcomputer,data acquisition module,GPRS signal transmission module and execution module.The schematic diagram and PCB diagram of the control board with STM32F103VET6 single chip microcomputer as the core are drawn by Altium Designer.Keil u Vision5 is used as the development platform of software program.The design methods of data acquisition program,signal transmission program,data processing program and data output program are mainly introduced.The monitoring system program of upper computer including fuzzy PID program is designed by Labview.The main characteristics of this study are mainly reflected in the following two aspects.First,fuzzy PID controller is used to adjust the concentration of marker gas,which effectively improves the control accuracy.The second is to determine the withdrawal distance of coiled tubing by means of coal combustion simulation,which can avoid waste of resources.Some indoor simulation experiments verify the rationality of the designed system.