JPH0235201B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an exhaust heat recovery boiler device, and more particularly to an exhaust heat recovery boiler device that prevents low-temperature corrosion of economizers and the like.

Conventional heat recovery boilers include, for example, high-pressure superheaters,
A high-pressure boiler system having a high-pressure evaporator, a high-pressure economizer, and a high-pressure drum, a low-pressure boiler system consisting of a low-pressure evaporator, a low-pressure economizer, and a low-pressure drum, and a low-pressure and It consists of a make-up water system that supplies water to each high-pressure drum.

In the above boiler device, when using a condensate deaeration method such as a condenser without using a dealerator to deaerate the water supplied to the low-pressure economizer, the temperature of the feed water supplied to the low-pressure economizer is For example, the temperature can be as low as about 30°C, and low-temperature corrosion may occur due to acidic components contained in the exhaust gas in low-pressure economizers.

An object of the present invention is to eliminate the drawbacks of the above-mentioned prior art and to provide a device that can prevent low-temperature corrosion after the low-pressure economizer of an exhaust heat recovery boiler device.

To achieve the above object, the present invention provides a high-pressure drum and a low-pressure drum connected to a high-pressure evaporator and a low-pressure evaporator, respectively, and supplying make-up water to the drums through a high-pressure economizer and a low-pressure economizer, respectively. An exhaust heat recovery boiler device equipped with a water supply system, characterized in that a pipe line is provided for recirculating a part of the water supply at the inlet of the high-pressure economizer via a high-pressure pump immediately before the low-pressure economizer. .

In the present invention, it is preferable to provide a temperature control device that adjusts the amount of the circulating water supply and controls the temperature of the water supply to the low pressure economizer.

Hereinafter, the present invention will be explained in more detail with reference to the drawings.

FIG. 1 is an apparatus system diagram showing a typical embodiment of the exhaust heat recovery boiler apparatus of the present invention installed in an exhaust gas flow path of a gas turbine plant. In the figure, this device consists of a low-pressure boiler system consisting of a low-pressure drum 1, a low-pressure economizer 5, and a low-pressure evaporator 6, and a high-pressure boiler system consisting of a high-pressure drum 2, a high-pressure economizer 7, a high-pressure evaporator 8, and a high-pressure superheater 9. A low-pressure energy saver 5 is connected to the boiler system and the low-pressure pump 3 from the condenser 12.
A low-pressure water supply system replenishes water to the low-pressure drum 1 via the flow rate adjustment valve 10, and a portion of the supplied water is taken out and boosted by the high-pressure pump 4, passed through the high-pressure energy saver 7 and the high-pressure flow rate adjustment valve 11, and then supplied to the high-pressure drum 1. A high-pressure water supply system that supplies water to the drum 2 and a portion of the high-temperature water supply are taken out from the middle of the flow path between the high-pressure pump 4 and the high-pressure economizer 7 and sent to the flow path between the low-pressure pump 3 and the low-pressure economizer 5. The recirculation flow path 13 to be recirculated and the temperature of the inlet feed water of the low pressure economizer 5 are detected by a thermometer 15, and the temperature of the recirculation flow path 13 is adjusted so that the temperature becomes equal to or higher than the critical temperature that causes low-temperature corrosion. It is mainly composed of a temperature control device 16 that adjusts the opening degree of a flow rate adjustment valve 14 that adjusts the amount of recirculated water supplied.

In the device configured as described above, the feed water deaerated by the condenser 12 is fed into the low pressure drum 1 by the low pressure pump 3 via the economizer 5 and the flow rate regulating valve 10, and the feed water that has exited the economizer 5 is fed into the low pressure drum 1 by the low pressure pump 3. A portion is further pressurized by the high-pressure pump 4 and sent to the high-pressure drum 2 via the high-pressure economizer 7 and the flow rate adjustment valve 11. At this time, the temperature of the feed water is measured by a thermometer installed in the inlet flow path of the low-pressure economizer 5, and the temperature is adjusted so that the temperature is higher than the critical temperature that causes low-temperature corrosion (for example, 33°C), preferably 50 to 70°C. Control device 16
The opening degree of the flow rate regulating valve 14 of the recirculation flow path 13 is adjusted, and a portion of the high-temperature, high-pressure water is recirculated.

As described above, a part of the high-temperature feed water at the inlet of the high-pressure economizer 7 is recirculated to the inlet side of the low-pressure economizer 5, and the temperature of the inlet water to the low-pressure economizer 5 is heated to a temperature at which low-temperature corrosion does not occur. By doing so, it is possible to prevent corrosion of the economizer and its peripheral equipment due to acidic components in the exhaust gas. Furthermore, in the embodiment described above, even when the high-pressure boiler system is in a stopped state, the high-pressure pump 4 is always in an operating state, so that an effect of shortening the start time of the high-pressure boiler system can also be obtained.

In the above embodiments, the present invention is applied to a mixed pressure boiler installed in a combined gas turbine plant, but the present invention is not limited to this and can be similarly applied to other boiler devices. can.

As described above, according to the present invention, it is possible to effectively prevent low-temperature corrosion of the low-pressure economizer and its related equipment in the exhaust heat recovery boiler.

[Brief explanation of drawings]

FIG. 1 is a system diagram of an exhaust heat recovery boiler device showing one embodiment of the present invention. 1...Low pressure drum, 2...High pressure drum, 3...Low pressure pump, 4...High pressure pump, 5...Low pressure economizer, 7...High pressure economizer, 12...Condenser, 13...Recirculation channel, 14...Flow rate adjustment valve , 15...Thermometer, 16...Temperature control device, 20...Gas turbine exhaust gas.

Claims (1)

[Claims] 1. A high-pressure drum and a low-pressure drum connected to a high-pressure evaporator and a low-pressure evaporator, respectively, and a water supply system that supplies makeup water to the drums through a high-pressure economizer and a low-pressure economizer, respectively. An exhaust heat recovery boiler device comprising: a pipe line for recirculating a part of the water supplied at the inlet of the high-pressure economizer via a high-pressure pump immediately before the low-pressure economizer. Boiler equipment. 2. The exhaust heat recovery boiler device according to claim 1, further comprising a temperature control device that adjusts the amount of the circulating water supply and controls the temperature of the water supply to the low-pressure economizer.