Phase transition combined air preheater

Abstract

The invention provides a phase transition combined air preheater, which is suitable for the field of recycling of boiler waste heat. The phase transition combined air preheater comprises a tubular air preheater and a phase transition heat exchanger, wherein the tubular air preheater is connected with the upper section of the phase transition heat exchanger through an air duct; a flow valve which is used for controlling the flow passing through the phase transition heat exchanger by using a control device is arranged on the upper section of the phase transition heat exchanger; the lower section of the phase transition heat exchanger is connected with a gas duct on the tail part of a boiler; a temperature acquisition module which is electrically connected with the control device is arranged on the lower section tube wall of the phase transition heat exchanger; and the control device is used for controlling the open degree of the flow valve according to wall temperatures acquired by the temperature acquisition module. On the one hand, the wall temperature of a heat exchange tube is 10 to 30 DEG C higher than the tube wall temperature of a vertical tubular air preheater, and the corrosion prevention of the heat exchange tube is facilitated; and on the other hand, flow media in the heat exchange tube is air, so that less accumulated dust is generated in the heat exchange tube.

Description

Technical field [0001] The invention relates to the technical field of waste heat recovery of boiler equipment. The invention also particularly relates to a phase change combined air preheater capable of adjusting the wall temperature. Background technique [0002] Existing boiler design tubular or regenerative air preheaters are designed to avoid low-temperature corrosion and fouling of the wall. If the inlet air temperature is 20°C, the exhaust gas temperature should be higher than 158°C (when the acid dew point is 80°C). This will cause higher exhaust smoke loss and wasted valuable heat source. If you want to further reduce the exhaust gas temperature of the boiler and ensure that the current minimum temperature of the pipe wall of the air preheater is not lower than the flue gas dew point, it is impossible to use traditional technical solutions. [0003] At the same time, the inlet air temperature of the air preheater changes with the season, and the exhaust gas temperature i...

AI Technical Summary

Problems solved by technology

This will result in high exhaust loss and waste of valuable heat source

If you want to further reduce the exhaust gas temperature of the boiler and ensure that the minimum temperature of the tube wall of the current air preheater is not lower than the dew point of the flue gas, it is impossible to use traditional technical solutions

[0003] At the same time, the inlet air temperature of the air preheater will change with the seasons, and the exhaust gas temperature will also be affected by load, combustion, etc. When the wall temperature of the air preheater is lower than the acid dew point temperature, the end of the air preheater will Low-temperature corrosion problems such as local dust accumulation, increased system resistance, and scaling on the heating surface occur, thereby affecting the thermal efficiency of the boiler

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