| As long as the power system's reform carrying thoroughly, each power plant develop in succession energy-saving work in order to strengthen own marker competitive power. Heat-engine unit is a complex many-variable system what means there is much factor that influent the unit's efficiency.All the factor of system structure's change, equipment performance's change, operating condition's change and method of operation's change can influent the efficiency of power plant, the operating condition involves the local climatic condition, the using coal kind and the outside load, as also the operating method involves fixed pressure operation, sliding pressure operation and compound mode operation.Generally speaking, the power plant thermodynamic system analysis is refers to the computation of the unit efficient data; but in the true sense, it should include the influence of each kind of turbulence aim to the economy of the thermodynamic system, on the basic of realization, the plant economy can be increased by eliminating the failure, improving adjustment and optimizing dispatching.It is introduced major methods of the thermodynamic system computation in the article. The basic efficient computation has been carried on the basic of design operating mode of home unit whose load is 600MW, what is import, and economy computation under off-design condition on the base of the theory of small disturbance. In the course of computation, The steam turbine is divided to be eight stagings by exhaust point, then after the change of operating condition, the parameter of thermal system is determined through the by Flugel formula and the enthalpy efficiency of staging by taking the staging as unit. The method of dividing staging can be used in any thermodynamic system, and it indicates the general character of the computation model under the off-design operation. Main parameter of thermodynamic system is calculated which conclude temperature and pressure for main steam, reheat steam temperature, turbine vacuum, temperature for feed water, and spray attemperation, and it is gained that the quantitative change of the unit when these parameter change. The result indicates that the influence of the temperature of main steam and reheat steam temperature is also equal, the coal consumption will increase 0.25～0.3% equally when the temperature reduce 10℃. But the influence of spray attemperation of superheater and reheater is difference, the former influence is small, the coal consumption only will increase 0.33% when the quantity of spray attemperation adds by 10%, but the coal consumption of the latter will increase 3.6% on the same condition. The temperature change of feed water is mainly resulted by stopping high level heater, and whose influence to the economy efficiency is severe, even if there only be one high level heater is stopped, the coal consumption will increase 0.64%. The influence of the pressure for main steam and exhaust steam is non-linearity; the pressure for main steam is lower, the economy efficiency is laugher, and the change of economy efficiency is more obvious when pressure change. But the pressure for exhaust steam is lower, the economy efficiency is higher, but it is same as the pressure for main steam, the change of economy efficiency is more obvious when pressure change.The above result has been obtained, at the same time, the article also analyze how the parameter generate the change of the economy efficiency and gives some suggestion measure. This quantitative analysis is significant for the unit caring on the online adjustment, standards production, energy conservation to the consumption falling as well as the economical operation of the unit.There are three kind of innovation in this article: the first is the application of the theory of small disturbance within the calculation; the second is that the expansion line of steam is take into account in the course of calculation under off-design condition; and the third is the general character of the computation model. |
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