United Optimization Of Steam Heating System With Circulating Fluidized Bed Boiler

Based on the statistical review of energy resources, steam heating system drivenby coal-fired circulating fluidized bed boiler is selected to be the subject. A literaturesurvey of research on circulating fluidized bed boiler and steam pipeline network iscarried out. The key results and drawbacks are pointed out. This paper focuses onunited optimal control strategy of boiler and the steam pipeline network. Dynamicmodeling of steam pipeline network and circulating fluidized bed boiler is studied aspriori knowledge for the control system development. The research extends thecontrol plant from boiler itself to the united body of boiler and pipelines.First, the paper reviewed the modeling process of steam pipeline networks andcirculating fluidized bed boiler from the first principles, clarified the correlationbetween system variables, and defined the input and output variables of each system.Experimental modeling data were collected through remote register system of steampipeline network and DCS of75t/h circulating fluidized bed boiler in Tianjin AirportIndustry Park. Taking advantages of the recent development in system identificationand control theory, a simulation model of the steam pipeline network and aprediction model of the boiler were built up.With help of these models, a simulation study on the energy efficiency of steamdelivery system was put forward. System performance, including pressures andtemperatures at user inlets and steam flow at boiler outlet, under different steam inputparameters was calculated as well as the energy efficiency. It is figured out that themain influence factor to the energy efficiency of steam delivery system is the steampressure. The degree of superheat helps under high pressures.Finally, taking both models of boiler and pipeline networks into account, acontrol strategy combining model predictive control and steam flow prediction isproposed. The system takes main steam pressure, main steam temperature and boilerbed temperature as control variables, coal supply, primary air, secondary air, andspray water as manipulated variables and main steam flow as measured disturbances.The system performance is simulated in MATLAB/SIMULINK. The controlperformance is better than overriding PID control. The main advantages of the proposed control are better control accuracy and shorter settling time. The resultdemonstrates the proposed control is an effective strategy for steam heating systems.