Ultralow-temperature coal economizer for single-reheat unit

Abstract

The invention discloses an ultralow-temperature coal economizer for a single-reheat unit, particularly for a single-reheat coal-fired power generation unit. The ultralow-temperature coal economizer can replace low-pressure heaters to heat condensed water and is provided with condensation type heating surfaces which can recover vaporization latent heat of water vapor contained in part of discharged smoke. Low-temperature condensed water is used for absorbing nearly half of evaporation heat in the water vapor contained in the smoke; the temperature of the smoke is reduced to 50 DEG C; and electric energy generated additionally by a sixth-stage vapor extractor, a seventh-stage vapor extractor and an eighth-stage vapor extractor which are replaced can reduce the heat consumption of a generator set by 2.3%. Compared with the prior art, the ultralow-temperature coal economizer does not exclude partial vapor extraction or vapor extraction at a certain stage but completely replaces the low-pressure heater; water-side resistance of the ultralow-temperature coal economizer is far less than the sum of water-side resistance of four low-pressure heaters, and the shaft power of a condensate pump is reduced remarkably; the temperature of smoke which enters a desulfurizing tower is reduced remarkably, dosage of process water is reduced substantially, and the power consumption of an induced draft fan is reduced remarkably; and in a condensing and heat-releasing process, water vapor can also absorb PM2.5, SO3 and NOx in the smoke, and the micro-discharge of the coal-fired power generation unit is facilitated.

Description

(1) Technical field: [0001] The invention relates to an ultra-low temperature economizer for a primary reheating unit, which relates to a device for a primary reheating coal-fired generating set, which can replace a low-pressure heater to heat condensed water, and can recover the latent heat of vaporization of water vapor contained in part of exhaust smoke Condensing heating surface. (two) background technology: [0002] The feed water below the saturation temperature flows in the economizer tube, which can effectively cool the flue gas at the outlet of the low-temperature superheater / primary low-temperature reheater. The temperature of the flue gas at the outlet of the economizer is usually 320°C to 390°C to meet the requirements of the denitrification catalyst. Safe and efficient work needs. The inlet of the economizer is connected to the outlet of the pipe side of the high-pressure heater system, and it works under the outlet pressure of the feed water pump, so it is als...

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Problems solved by technology

[0009] Although the pressure of the 5 pumps, 6 pumps, 7 pumps, and 8 pumps used for condensate reheating in a typical prior art primary reheat unit is not high, the enthalpy and superheat are still relatively high after reheating. The exhaust steam enthalpy of the low-pressure cylinder of the heating unit is 96kJ / kg lower than that of the double reheating unit, and it still has a strong working capacity. Because the reheating of condensed water at a lower temperature will greatly increase the exergy (exergy) loss during the condensed water reheating process, and increase the heat consumption of the unit

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