Cold air heating and flue gas waste heat comprehensive utilization system for power station boiler

Abstract

The invention provides a cold air heating and flue gas waste heat comprehensive utilization system for a power station boiler. The cold air heating and flue gas waste heat comprehensive utilization system for the power station boiler is characterized in that a high-temperature flue is divided into a first flue gas channel and a second flue gas channel which are connected in parallel, and the tailends of the first flue gas channel and the second flue gas channel are combined into a low-temperature flue; the first flue gas channel sequentially passes through a flue gas-water supply heat exchanger and a primary air preheater in the flue gas flow direction, and a water supply pipeline is connected to the flue gas-water supply heat exchanger in a communicating mode; a primary air pipeline is further involved, the primary air pipeline sequentially passes through the primary air preheater and at least one stage of primary air steam heater in the primary air flowing direction, and a steam pipeline is connected to the at least one stage of primary air steam heater in a communicating mode; and the second flue gas channel passes through a secondary air preheater, and a secondary air pipelineis connected to the secondary air heater in a communicating mode. According to the cold air heating and flue gas waste heat comprehensive utilization system, through the above structure, the primaryair heating process and the secondary air heating process are independent respectively, gradient heating is achieved on primary air, the temperature of the primary air is controlled by adjusting the steam flow, the terminal temperature difference is reasonably controlled, the heat loss is reduced, and the heat efficiency of a unit is improved.

Description

technical field [0001] The invention belongs to the field of power station energy saving and emission reduction, and relates to a comprehensive utilization system for cold air heating and flue gas waste heat of a power station boiler. Background technique [0002] Energy saving and emission reduction is the basic strategy that my country's coal-fired power plants need to adhere to for a long time. At present, large-scale coal-fired units have carried out and implemented a large number of research and application of waste heat utilization, and achieved significant effects of coal saving and emission reduction. How to further improve the energy utilization rate of coal-fired power plant units, deeply optimize the system and tap the energy-saving potential has become the next research topic of coal-fired power plants. [0003] At present, the positive pressure direct-blown pulverizing system of medium-speed mill is the type of pulverizing system commonly used in large coal-fir...

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Problems solved by technology

[0003] At present, the positive pressure direct-blown pulverizing system of medium-speed mill is the type of pulverizing system commonly used in large coal-fired power plants in my country. The heated primary air (usually above 300°C) must be mixed with cold air to meet the air temperature requirement at the coal mill inlet. At this time, there will be a greater loss in the mixing of cold and hot primary air, and the more cold air is mixed , the more serious the loss, the worse the thermal economy of the boiler

In order to avoid the mixing of hot and cold primary air, the conventional solution is to install a primary hot air-feed water heat exchanger or a primary hot air-condensate heat exchanger at the primary air outlet of the air preheater to reduce the primary air temperature. For heat supply water and condensate water, due to the increase of the heat exchange process, the irreversible loss of heat exchange increases, and the energy saving effect of this scheme is greatly reduced

Therefore, the current pulverizing system, the heating type of the air preheater, and the solution of mixing hot and cold air all have a large energy waste, and there is still a large room for energy saving

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