Ultra-low temperature economizer for double reheat unit

Abstract

The invention discloses an ultra-low temperature coal economizer for a secondary reheat unit, and relates to a low-pressure coal economizer which is used for a secondary reheat coal-fired generating unit and can replace a low pressure heater to heat condensation water and recycle latent heat of vaporization of vapor contained in partial exhaust gas. The condensation water which is at 35 DEG C or a lower temperature is utilized to absorb almost half of evaporation heat of the vapor contained in the exhaust gas, and the temperature of the exhaust gas is dropped to 50 DEG C. Compared with the prior art, the ultra-low temperature coal economizer does not push out partial certain level vapor extraction, but completely replace the low pressure heater; the water side resistance of the ultra-low temperature coal economizer is far lower than the sum of the water side resistance of four or five sets of the low pressure heater, and the shaft power of a condensate pump is obviously deceased; due to the fact that the temperature of the exhaust gas which enters a desulfurization tower is obviously decreased, the process water consumption is greatly reduced, the volume flow of the exhaust gas is obviously reduced, and the power consumption of an induced draft fan is obviously decreased; the vapor can absorb most of PM2.5, SO3 and NOx in the exhaust gas in the condensation heat release process, and micro-discharge is facilitated for the coal-fired generating unit.

Description

[0001] (1) Technical field: [0002] The invention relates to an ultra-low temperature economizer for a double reheating unit, which relates to a second reheating coal-fired generating set, which can replace a low-pressure heater to heat condensed water, and can recover part of the vaporization of the water vapor contained in the exhaust smoke Latent heat low pressure economizer. [0003] (two) background technology: [0004] 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 / secondary 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 needs of safe and efficient denitrification catalysts. 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 pum...

AI Technical Summary

Problems solved by technology

[0011] The typical prior art double reheat unit is used for 6 pumps, 7 pumps, 8 pumps, 9 pumps, and 10 pumps for condensate recovery. Although the pressure is not high, the enthalpy and excessive The heat is still high, and still has a strong working ability, such as the superheat of 6 pumps reaches 227.6K, and the superheat expressed by the enthalpy value reaches 491.6kJ / kg, which will greatly increase the heat recovery of condensate water at a lower temperature Exergy (exergy) loss during condensate reheating process, heat consumption of lifting unit

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