On Energy-saving Automation System For Heat-exchange Station

Heat-exchange station is a very important part in heating system. In our country many heat-exchange stations are operated by experience which resulted in the waste of energy and inefficiency of heat supply.On the basis of basic heating theory of heat supply engineering, the potential of energy-saving in heat-exchange station is analyzed, and according to the problem of heating control system, the corresponding methods are developed. Local control and PC monitor are used in this paper. PLC is selected in the system to monitor and control the values of the supplied and regurgitant water such as temperature, pressure, the supplied water flux of the first-net and second-net, etc. PLC is connected with PC monitor through Ethernet. Friendly human-machine interface by configure software was designed to monitor and control the running parameters. After such scheme is applied, both of uniform regulation and balance between water and heat power condition of heat-net are more favorable so that equipment investment is reduced and system expansion becomes easier.The value of supplied water temperature of the second-net is set according to outside temperature in order to reduce the expense of heat. By regulating bypass valve of the first-net, the transfer rate of heat-exchange station can be changed and the heat-loss of the first-net can be reduced when the supplied water temperature of the second-net reaches the set value. Frequency conversion timing is adopted in circulating pump control so that the system controllability is improved. Furthermore, the energy and electricity power is saved.With the condition that the users in the same heating area have differences in time of the heat use, regional divided time heating strategy is utilized and intellectual regional heating controller is designed. By using intelligent "pang-pang" control, the valve is regulated so as to make sure that heat can be fed back to heat-net when it is not needed. The experimental results indicate that energy-saving rate of the regional heating can be 30 percent, and the source using rate is improved distinctively.The scheme presented in this thesis can not only be used in classical coal-fired centralized heat supply system, but also be combined with developing heating mode, such as ground-water heat pump and solar energy heating mode with justification of energy-saving so that broad application foreground will be achieved.