| At present,with the development of global and domestic economy,energy and environmental protection,the development of coal-fired power plants has entered a new critical period.In order to adapt to this new situation and ensure the leading technology of power plant and high efficiency of the units,we should actively create the conditions to adopt advanced and mature technology to carry out the transformation of technical equipment for lagging units with poor economy and safety.In order to reduce resource consumption,increase economic benefits and enhance the competitiveness of the industry,we should make efforts to develop the internal potential,improve the reliability and economy of the unit,and reduce the cost.We will promote the level of technical equipment in power plant and reduce the environmental pollution in accordance with the demand of deep peak load regulation of power grid.Firstly,this paper expounds the theoretical basis and evaluation index of thermal economy calculation method for thermal power unit,and compares different thermal economy calculation methods one by one.Matrix equation method for energy efficiency distribution and thermal balance method are taken as the calculation method for thermal economy in this paper.At the same time,this paper introduces a deep waste heat utilization system for composite thermal power units to improve the shortcomings of conventional thermal power unit system equipment,namely the flue-water composite regeneration system.The principle and composition of the system and the problems that can be solved in thermal power units are described in detail.Secondly,based on the matrix equation method for energy efficiency distribution,the steam-water system of the flue-water composite regeneration system is optimized.The energy efficiency distribution matrix equation is applied to the technical renovation of the deep utilization of waste heat in the tail flue gas of thermal power units to result in the proposal of a general energy efficiency distribution matrix equation for the optimization system of low temperature economizer.Then,the general energy efficiency distribution equation is applied to the steam-water system of the flue-water composite regeneration system to optimize the position of water intake point on the water side of the high-pressure heat exchanger,calculate the thermal economy of the unit with different intake points,and select the optimal scheme by comparison.Finally,according to the performance test data of a domestic 600 MW power plant retrofitted by flue-water composite regeneration system,the thermal economic analysis of the boiler side and the steam turbine side of the unit is carried out by using the heat balance calculation method.Under 100%,75% and 60% load,the coal consumption after putting into operation of flue gas-water composite system is reduced by 6.89g/(kW·h),5.46g/(kW·h)and 2.95g/(kW·h)respectively compared with the former.The actual energy-saving effect of the unit retrofitted by flue-water composite regeneration system is calculated and analyzed from the practical application,which can provide reference for other similar units. |
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