Power station machine furnace integrated cold end comprehensive optimization system

Abstract

The invention discloses a power station machine furnace integrated cold end comprehensive optimization system which belongs to the field of power station energy saving. The system mainly comprises a steam turbine, a main economizer, a main flue, a bypass flue, a convergence flue, a main air pre-heater, smoke-water heat exchangers, a high pressure heater, a low pressure heater, a deaerator, a smoke-air heater and steam extraction condensed air pre-heaters. Multi-stages of the steam extraction condensed air pre-heaters are serially arranged, sequentially extract a part of exhaust steam of the steam turbine and corresponding low-pressure-stage extraction steam and preheat cold air stage by stage; and the first, second and third stage smoke-water heat exchangers are used for heating feeding water and condensed water, and high-pressure extraction steam of the steam turbine is replaced. According to the machine furnace integrated cold end comprehensive optimization system, by means of efficient waste-heat utilization, low-pressure extraction steam is used for heating air, and the high-pressure extraction steam for backheating is saved so that unit output power is obviously increased, deep energy saving and consumption reduction of the coal-fired power generation unit are achieved, the problem of low-temperature corrosion on a heated surface during waste-heat utilization is solved, and economical benefits are remarkable.

Description

technical field [0001] The invention belongs to the field of energy saving and emission reduction, and particularly relates to a comprehensive optimization system for the integrated cold end of a power station machine and furnace, specifically: (1) on the air side, steam turbine exhaust and low-pressure steam extraction are used to preheat the cold air step by step, The preheated air enters the main air preheater and is further heated to the required temperature; (2) The flue gas at the outlet of the boiler economizer enters the main air preheater and the first and second stage flue gas of the bypass flue at the same time. Water heat exchanger, the outlet flue gas enters the third-stage flue-water heat exchanger after being merged at the boiler tail, and then enters the dust removal and desulfurization device; (3) The first-stage flue-water heat exchanger can be used to heat the turbine feed water, replace Partial high-pressure steam extraction, the second and third-stage smok...

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Problems solved by technology

[0005] The waste heat recovery system of the Niederaussem power plant in Germany can save about 7g / kWh of standard coal consumption for power generation. However, since German power plants generally use lignite as fuel, the exhaust gas temperature is generally high, even as high as 160 °C. Therefore, the tail gas waste heat of German coal-fired power plants very high

However, China's coal-fired power plants use ordinary anthracite and bituminous coal as fuel, and the flue gas temperature is relatively low, generally around 120-140°C, which is quite different from the actual situation in German power plants. Such as SO2, SO3, NOx and other corrosive gases, when the wall surface temperature drops below the acid dew point, the low-temperature pipe wall is prone to gas Intense low-temperature flue gas corrosion, and at the same time form a cement-like substance mainly composed of calcium sulfate with the fly ash in the flue gas, which increases the ventilation resistance of the flue gas side, increases the power consumption of the fan, and aggravates the corrosion of the pipe wall, seriously affecting Safe and Economical Operation of Boilers

Therefore, the waste heat recovery system of Niederaussem power plant in Germany is not suitable for coal-fired power plants in China

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