Air preheating system and air preheating method for comprehensive waste heat utilization with separate control phase change

Abstract

The invention discloses a respective-control phase change comprehensive waste heat utilization air preheating system and method. The system comprises an air preheater (33), an air preheater front air way (31), an air preheater rear flue (32), a condensate water main pipe (11), a steam main pipe (15), an air heater (28), a flue gas phase change cooler (12), a flue gas water cooler (7), a phase change water heater (17), a condensate water regulating valve (30), a steam flow regulating valve (14) and a liquid flow pipe (5). By means of the respective-control phase change comprehensive waste heat utilization air preheating system and method, a respective-control phase change heat exchange manner is adopted in a final-stage flue gas waste heat recovery heat exchanger, the final-stage flue gas waste heat recovery heat exchanger is combined with a condensate water air heater and a high-temperature flue gas cooler, and waste heat recovery benefits are improved.

Description

technical field [0001] The invention belongs to the technical field of safe and controllable heat transfer, and is particularly suitable for use in the fields of waste heat recovery and utilization of boiler flue gas, air preheating and the like. Background technique [0002] Phase change heat has the characteristics of high heat transfer coefficient, large latent heat carried by the medium, unique correspondence between phase change saturation temperature and saturation pressure, uniform temperature distribution of phase change fluid, and easy control of phase change parameters, so it is widely used in enhanced heat transfer and Waste heat recovery and utilization system. [0003] Separately controlled phase change technology independently controls the phase change parameters of the cold source and heat source, so that the phase change parameters of the heat source are not affected by the heat exchange phase change parameters of the cold source, and reliably guarantees the ...

AI Technical Summary

Problems solved by technology

[0004] However, the existing separate control phase change system is relatively insufficient, because it makes all the waste heat of the flue gas indirectly heat the condensed water, which increases the heat transfer temperature difference and increases the heat transfer process. loss; due to the influence of the poor heat transfer end of the condensate heater, the temperature of the condensate incoming water cannot be too high, so the bypass condensate discharges the low-temperature stage and the low-pressure extraction reduces the efficiency of waste heat utilization; in addition, the existing sub-control The phase change technology uses a vapor-liquid heat exchanger to reduce the supercooling degree of the inlet water of the flue phase change cooler. It needs external auxiliary steam to supplement the heating water. The system is relatively complicated, otherwise it will be affected by the heat transfer difference between the main heating steam and water. The water temperature is difficult to approach the saturation temperature of the main heating steam

Images