Study On Energy Saving Optimization Of Cooling Tower Fan Based On VFD System

Cooling tower fan is an important cooling equipment in petrochemical industry, it is also one of the main energy consuming equipment in cycling water system, the implementation of frequency operation for fan energy saving is one of the most effective measures. The operation of fan frequency conversion energy saving is mainly based on the cooling tower heat demand conditions, for the purpose of meeting the demand of the supply water temperature during the production. In order to make the cooling tower fan frequency conversion operation safe, reasonable and further energy saving, there is important realistic significance to research the optimal energy saving fan frequency conversion speed regulating system.This subject is based on analysis of heat transfer theory and fan frequency conversion operation theory, according to the Sinopec Tianjin branch water department the second workshop cooling tower, design and manufacture of fan frequency conversion speed regulation system are finished, and the variable frequency control mode is optimized. The main results of the research are as follows:(1) Research frequency conversion principle and theory of fan operation. Through the analysis of the mechanical and electrical properties of motor frequency conversion, and analysis of parameters of fan variable speed operation, finally study the energy saving situation of variable frequency speed regulation of the fan operation, establish fan frequency conversion operation theory.(2) Study the thermodynamic theory of cooling tower for heat transfer, especially analyze thermo-characteristics of packing, combining with the fan frequency conversion operation theory, establish mathematical mode of the relationship between fan power supply frequency of the motor and the cooling tower characteristic number (heat capacity), fan operation frequency value and the cooling tower heat dissipation capability are corresponding.(3) According to mathematical model of the relationship between fan power supply frequency of the motor and the cooling tower characteristic number (heat capacity), the optimization control mode of fan frequency conversion speed regulating system-the variable frequency mode based on equidifferent discrete characteristic number is proposed and designed, energy saving analysis of this control mode is done. Optimization of the design of variable frequency control mode for Sinopec Tianjin branch water department the second workshop cooling tower fan is finished.(4) Completed the design and manufacture of variable frequency speed regulation system, including the inverter main circuit and control circuit, the electrical design of PLC control circuit, through the PLC program and the external electric circuit, realizes the close loop operation of fan control system, through the force control configuration software to realize remote monitoring for energy saving control of fan remote operation and real-time operation state of the host computer.The optimization energy-saving control system of fans which was researched and manufactured in this paper was applied well in Sinopec Tianjin branch water department the second workshop cooling tower. This system had improved the stability of the system and had significant energying-saving efficiency. It had a high value promotion and broad market prospects.