Research And Design Of Biomass Boiler Automatic Control System

Biomass energy is a kind of renewable energy.Biomass boiler with biomass as fuel can effectively solve the problems of energy shortage and environmental pollution.There are some problems such as insufficient capacity utilization,untimely pressure regulation in the furnace,untimely water level regulation,non-automatic feeding and dangerous working environment existing in the biomass boilers developed in China,which mainly refer to the control technology of coal-fired and gas-fired boilers.Because of above reasons,the promotion and application of biomass boilers are greatly affected.Therefore,the control method and control system are the key to improve the automation degree and combustion efficiency of biomass boiler.This thesis is partially supported by the project of enterprise entrustment“Research and Development of Biomass Boiler Control System”.In this thesis,the process improvement measures and methods of biomass boiler are put forward,and the new functions and requirements of the biomass boiler's improved process are analyzed.On this basis,the automatic control system of biomass boiler is designed.The main work and research results this thesis are as follows:(1)In view of the problems of biomass boiler such as insufficient capacity utilization,untimely adjustment of pressure in the furnace,untimely adjustment of water level,failure to realize automatic feeding and dangerous working environment.The improvement scheme of biomass boiler process flow is put forward,such as fuel combustion,heat transfer,steam transfer and other technological processes.The power equipment of biomass boiler is equipped,and the main circuit and operation circuit are designed.What's more,according to the design requirements of automatic control system of biomass boiler,the overall scheme design of automatic control system of biomass boiler is proposed.The hardware and software design of automatic control system of biomass boiler are completed.(2)In order to improve the combustion performance of biomass boiler and the utilization rate of biomass energy,the furnace pressure control of biomass boiler is the key.Therefore,this thesis focuses on the control strategy of furnace pressure of biomass boiler.The double closed-loop control method is chosen to realize the real-time control of the furnace pressure,so as to keep the chamber pressure stable.The inner ring is speed adjustment,which is realized by the frequency converter.The outer ring is pressure adjustment,which adopts fuzzy self-adaptive PID control algorithm and is realized by through PLC programming.This thesis focuses on the biomass boiler furnace pressure control strategy.The fuzzy self-adaptive PID controller is designed,and the parameter setting principle and fuzzy rule of the controller are selected.The fuzzy adaptive PID controller of pressure control system of biomass boiler is simulated and verified by MATLAB simulation software,and compared with the conventional PID control method.The comparison results show that the fuzzy adaptive PID control method has the advantages of fast response,good steady-state performance and high control accuracy.(3)According to the overall scheme design and control strategy of automatic control system of biomass boiler,the PLC control system design of biomass boiler is completed.The hardware part of the automatic control system is composed of the master control module of CPU226 of the PLC and M PPI-EXT of the communication extension module,EM231 of the analog output module,the digital input interface circuit,the digital output interface circuit and the touch screen.The external equipment communicates with the master control module of CPU226 through 485 bus to exchange information and data.External equipment includes electric quantity collection module,furnace pressure transmitter,frequency converter,oxygen content analyzer,boiler pressure controller and digital water level switch.The software design of automatic control system includes the software design of control system of PLC and the design of human-computer interaction monitoring interface.(4)According to the software design scheme of biomass boiler automatic control system,the software design of control system of PLC and the design of humancomputer interaction monitoring interface are designed.The overall structure of the system software design is determined,the monitoring interface and functions are designed,the main flow chart is completed,and the man-machine interaction interface and control interface are designed on the touch screen with MCGS configuration software.(5)The test platform of the automatic control system of biomass boiler was constructed,the automatic control system of biomass boiler was developed,and a system test was conducted to verify the correctness and feasibility of the hardware and software design of the automatic control system of biomass boiler.To sum up,in order to improve process and control system of the original biomass boiler,the technology and control method of primary material boiler are improved.Thus the automation degree and combustion efficiency of biomass boiler are improved.These have certain theoretical significance and practical value.