The air preheater is Waste heat boiler The components of the flue gas side flow are arranged at the downstream of the flue gas as the tail heating surface. There are low temperature corrosion and ash deposition problems of the air preheater. What is the reason why most waste heat boilers do not have air preheaters now? First, we should follow the small editor to learn about the air preheater.

The air preheater arranged separately heats the cold air entering the furnace, and the air preheater is no longer set in the tail flue to avoid the low-temperature corrosion problem of the tail heating surface. At the same time, since the steam air preheater is arranged outside the flue, it is a separate heat exchange unit that does not contact the flue gas, avoiding the ash accumulation problem caused by the flue gas flow.

Working principle of the air preheater: through the cold air pipe, under the action of the blower, it enters the steam air preheater to be heated. The heated hot air enters the air chamber at the bottom of the grate through the hot air pipe, and then enters the furnace.

The air preheater consists of two heaters in series, namely the low-pressure section and the high-pressure section. In the low-pressure section, the heat source is the primary steam extraction of the turbine, the steam flows in the pipe, and the cold air washes the pipe bundle externally for heat exchange. The air inlet temperature is 23 ℃, which rises to 160 ℃ after being heated in the low-pressure section, and the steam becomes condensed water and discharged; In the high-pressure section, the heat source is saturated steam drawn from the steam drum. The steam flows in the pipe, and the air washes the pipe bundle for heat exchange, heating from 160 ℃ to 220 ℃.

At the same time, enter Waste heat boiler The quantity of flue gas is large, the heat required by steam and saturated water is mainly from flue gas, while the auxiliary burner needs less air, but the quantity of flue gas to be cooled is large, and the quantity of air is small, which is difficult to effectively recover the heat in flue gas. If an air preheater is set, not only the heat recovered is small, but also the heat transfer area required is large, Its economic benefits must be very poor. Therefore, the economizer of the general waste heat boiler is much larger than the conventional heating furnace, and the flue gas heat can be effectively recovered through the economizer.