Regenerative controlled phase-change air pre-heating system and pre-heating method

Abstract

The invention relates to a regenerative controlled phase-change air pre-heating system and a pre-heating method. The pre-heating system comprises an air pre-heater (3), a flue gas channel (4) and an air channel (5); the flue gas channel (4) and the air channel (5) are connected with the air pre-heater (3); a low-temperature heat release device (22) and an air heat return and absorb device (6) are respectively arranged in front of or behind the air pre-heater (3) on the air channel (5) along an air flow direction; a high-temperature heat absorbing device (8) is arranged in front of the air pre-heater (3) on the flue gas channel (4) along a smoke flow direction; a steam manifold (19) connected with the low-temperature heat release device (22) is respectively communicated with the air heat return and absorb device (6) and the high-temperature heat absorbing device (8) by virtue of branch pipes, and a condensate manifold (20) connected with the low-temperature heat release device (22) is respectively communicated with the high-temperature heat absorbing device (8) and the air heat return and absorb device (6) by virtue of the branch pipes. According to the regenerative controlled phase-change air pre-heating system, the afterheat recycling rate and the exhaust gas temperature can be flexibly adjusted according to changes of coal seasons and unit loads.

Description

technical field [0001] The present invention relates to an air preheating system, in particular, the present invention relates to a recuperation type split-controlled phase change air preheating system and a preheating method. Background technique [0002] Due to changes in coal types, equipment conditions, seasons, and unit loads, as well as design errors, the exhaust gas temperature after the air preheater in actual operation often deviates from the design value under the design conditions. Due to the traditional air preheater All adopt fixed design parameters according to the design working conditions, and the heat exchange capacity of the heat exchange equipment cannot be adjusted. Therefore, either because the exhaust gas temperature of the boiler is too high, the loss of energy consumption is very large, or the low temperature corrosion of the air preheater is caused by the exhaust gas temperature being too low. [0003] In winter, a heater is usually installed in fro...

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Problems solved by technology

However, in the above-mentioned split-controlled phase-change heat technology, since the heat source and heat absorption device is located behind the original exhaust heat utilization device, the temperature of the flue gas is lower. The acid dew point is closer, the risk of low-temperature corrosion of the equipment is greater, and the reliability of the control system is higher; at the same time, because the heat source and heat absorption device is located behind the original exhaust heat utilization device, the flue gas temperature is lower, so The heat exchanger area of ​​the phase-change heat source and heat-absorbing device at a low temperature is required to be larger, so the resistance of the flue gas is also greater, and it is easier to block ash at this place; The cost of improving the wear resistance and corrosion resistance is high, the performance drops after leakage occurs, and the maintenance is difficult

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