The Design And Implementation Of PLC Controlling System For Steam Boiler

As a production equipment for power media, steam boiler always plays a very importantrole in the Industrial production and people’s life And with the importance and necessity.In theday of fast-growing economy, serious environmental pollution and energy demand increasing,moreover the steam boiler is a hysteretic and coupled system,that designing a PLC controlsystem of adding performance of energy-conserving and environment-protective is a highexpectation thatmany corporationsand individualshasbeenlookingforwardto.By reading, learning and reference, comparing the actual running situation, combiningwith the graduate students have learned during the period of control theory and to participate inthe actual project experience, I think that the intelligent control algorithm is applied to PLCcontrol system of the steam boiler, colleagues can reduce the coupling of the control system asthefocus of thethesis, whichis applied to actual projects. Articlemainly divides intothree parts:the first part is mainly about the background, development present situation, development trendof the steam boiler, working principle, adjustment and design the purpose and significance ofmade an overall introduction and generalization. The second part from the macro to the overalldesign made a basic introduction, clear thinking and steps. At the same time for the steam boilersystem functional decomposition, to extract the main variables and define its role andsignificance. Determine the two control system of steam drum level and wind coal thandichotomy and introduce intelligent control theory and control method, through the flow chart isexplained. The third part is the hardware and software design. Hardware design including maincircuit, control circuit, the design of frequency inverter and soft starter. Software design is thefuzzy PID control, the dichotomy of control on the basis of lower and upper unit state machineprogramming.In this paper, the design and realization of PLC control system of the steam boiler, first ofall, to simplify the control system, through the control of the drum level and wind coal ratio,gives the whole control system is stable, and in the aspect of energy conservation andenvironmental protection has a great improvement. Through fuzzy control PID enhanced wellovercome the effect of coupling and lag, makes the level control more timely and stable andwell to avoid the oscillation phenomenon and the excessive overshoot. By dichotomy delaycontrol coal than the wind, as low as possible to cut the combustion system of steam drum level the negative impact of the coupling effects on the adjustment of the pressure to get an optimalcoal than the wind, and don’t have to use oxygen analyzer. Both achieved the effect of energyconservationandenvironmental protection,andsavea lotofdesign cost.