Research On Optimal Operation Of Cold-end System For 600MW Thermal Power Unit

Thermal power generation still occupied the main position in China’s energy structure. The slogan of energy conservation and emissions reduction is also strongly advocated in today’s society. How to realize saving energy and reducing consumption of thermal power generation is one of the important tasks of scientific research nowadays. The cold-end system of thermal power unit is an important auxiliary system, and its operation quality directly affects the safety and economy of units. Therefore, the analysis and research of the optimal operation and ensure the best operation condition of cold end system is an important means of enhancing the economy, and pointed out the direction of energy saving and consumption reduction for coal-fired power plant.This paper analyses the basic principle of thermal power unit cold-end system aimed at the 600 MW power plant for the optimization of cold-end system, and the cold-end system is divided into the following several parts: the end of the steam turbine exhaust steam, condenser and circulating water pumps. The main study contents are as follows:1、through the analysis of the basic principle of the condenser variable condition, find out the relationship between the end of the steam turbine exhaust steam, circulating water flow, circulating water temperature and the condenser pressure, and establish the specific expression between them;2、this paper analyzes the characteristics of steam turbine low pressure cylinder end exhaust steam, three kinds of method are given that how to determine characteristics of the back pressure steam turbine power, and according to the power characteristic curve of the back pressure turbine that steam turbine manufacturer provide, and fitting out the relation between increases the power and the unit back pressure.3、In view of shortcomings of the calculation of similarity law in the traditional variable frequency pump, and established the calculation model of variable frequency pump power. Work-flow model is established on the basis of the constant speed operation characteristics of circulating water pumps in parallel. At the same time, analyzes the characteristics of frequency conversion water circulating pump parallel operation and through the dichotomy of Matlab programming to establish the work-flow model. Points out the generality of the method and laid the foundation for circulating water pump frequency conversion optimization. 4、Established the different load and different inlet temperature of circulating water and circulating water pump unit under the combination of increased power and circulating water pump power consumption when the difference between the maximum objective function through analysis and research at the end of the steam turbine exhaust steam, condenser and circulating pump running between the coupling characteristics. The aim is find out the best combinations in the different load and constant speed of the circulating water pumps under different inlet temperature of circulating water. 5、the frequency conversion circulating water pump was calculated under different rotating speed ratio of circulating water pump power consumption, analysis of earnings of constant speed circulating pump and frequency conversion water circulating pump, the results show that the fixed frequency optimization, circulating pumps can bring certain energy-saving benefit for power plant, the optimization of cold end system has certain guiding significance.