| In recent years, the industry and society in our country have made a spurt of progress. As a consequence, the power consumption keeps rising, the pressure of the power-supplying is rather higher, and the burden of power plants keeps increasing. After the reform of the electricity power system, numbers of captive power plants came to appear in succession with a more intense competition. As a result, most of power plants pay more attention to the control of the cost of power generation and the requirement of the reliability of the generation sets’ operating. The plant consumption rate of the boiler fans is up to 10%, which has a higher energy consumption in the auxiliary equipments of power plants.In a certain private power plant, the primary fan(PF), secondary fan(SF) and induced draft fans(IDF) of the boilers used to apply the traditional damper adjustment to meet the change of air volume, which has lots of throttling loss and a poor system-operating stability. The frequency inverter system is able to complete the changing of the air volume of the boiler fans by adjusting the motor speed of fans without any throttling loss. And the soft-starting and soft-stopping functions of the frequency inverter can protect the operating security of the equipments and the power grid. Therefore considered the superiority of the frequency inverter system, this paper proposed reasonable schemes of frequency conversion transformation for the PF, SF and IDFs of the two boilers, aimed at solving problems such as the high power consumption of boiler fans in this private power plant. Furthermore, this paper made an analytical prediction of the effects of the transformation project. This paper completed the following works:Firstly, this paper made a briefly description of the basic situation about this private power plant, and the process flow chart of air and gas systems in boilers was given. Then this paper explained several methods of air regulation in detail, including the regulating principles, the regulating characteristics, the advantages and disadvantages and so on. Further more, the air regulation methods were compared and analyzed in ways of operating energy consumption, initial investments ect, in which way the superiority of the frequency inverter system was displayed.Secondly, this paper simply introduced the theoretical knowledge about the frequency inverter, including the principle of the frequency conversion, the basic structure, the classification ect. Then the selection of the frequency conversion was discussed emphatically, which included the type selection and the capacity calculation of the frequency conversion. The knowledge about the frequency inverter provided a theoretical foundation for the formation and determination of the frequency conversion transformation schemes in this project.Thirdly, the key parameter of the lower frequency limit was interpreted and its specific number of the frequency conversions of the fans in this project was determined. The frequency conversion transformation schemes were tested and verified by judging whether the given frequency values are equal to or greater than the lower frequency limit value of the frequency conversions. Eventually we determined the reasonable transformation schemes with better energy-saving and more stable system-operating effects, and we provided the train of thought about determining the frequency conversion transformation schemes for similar projects in the future.Lastly, this paper analyzed and predicted the transformation effects about the energy-saving and the system-operating. The calculation results illustrated that the system-operating effect would be optimized, besides of the great energy-saving effect. The calculation results also proved a conclusion that the frequency inverter system is more suitable for those projects with a larger range of load variation. In addition, several notices during the frequency conversion transforming were put forward, aimed at providing references for similar projects in the future. |
PDF Full Text Request