JP4132380B2 - Heat recovery amount increasing device in latent heat recovery boiler - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a heat recovery amount increasing device in a latent heat recovery boiler.
[0002]
[Prior art]
It is widely practiced to improve boiler efficiency by providing an economizer in an exhaust gas passage through which exhaust gas discharged from a boiler passes and preheating feed water with the exhaust gas. The economizer exchanges heat between the exhaust gas in the exhaust gas passage and the heat transfer tube provided in the exhaust gas passage, and as the heat absorption amount of the heat transfer tube increases, the temperature of the feed water sent through the heat transfer tube increases. The efficiency of the boiler is improved. Since the exhaust gas contains moisture generated by combustion in a gaseous state, more heat is also recovered by recovering not only the sensible heat of the exhaust gas but also the latent heat. However, the latent heat recovery unit has a problem that the economizer becomes very large because the efficiency of heat exchange is poor.
[0003]
In addition, the boiler needs to periodically discharge the can water, but since the blown water discharged contains heat, the efficiency is reduced if it is discharged as it is. Therefore, heat is recovered from the blow water by exchanging heat between the high temperature blow water and the water supply before entering the economizer. First, the temperature of the feed water is raised by the heat of the blow water, and the feed water temperature can be further raised by putting the feed water whose temperature has risen into the economizer. However, in the case of an economizer performing latent heat recovery, if the water supply temperature is increased by blow water, the heat absorption efficiency of the economizer will decrease, and the amount of heat recovered from exhaust gas even if heat from the blow water is recovered. Therefore, the overall heat recovery amount did not increase so much.
[0004]
[Problems to be solved by the invention]
The problem to be solved by the present invention is to improve the heat recovery efficiency in the latent heat recovery section, and to increase the amount of latent heat recovery and downsize the latent heat recovery economizer.
[0005]
[Means for Solving the Problems]
Steam is generated using the combustion gas obtained by the flame generated by the combustion device, and the exhaust gas whose temperature has decreased due to heat exchange is discharged through the exhaust gas passage. An economizer is installed in the exhaust gas passage to preheat the water supply. The economizer is a latent heat recovery boiler that collects not only sensible heat of exhaust gas but also latent heat, without directly injecting high-pressure blow water discharged from the boiler into the heat transfer pipe in the exhaust gas passage. By flushing, steam is generated in the exhaust gas passage, and the amount of water contained in the exhaust gas in the economizer part is increased, thereby improving the heat recovery efficiency in the latent heat recovery part of the economizer. In addition, a partition plate that divides the heat transfer tube installation part is provided in the exhaust gas passage, blow water piping is connected to the part divided by the partition plate, and high-pressure blow water discharged from the boiler is flushed at the part divided by the partition plate By doing so, steam is generated in the exhaust gas passage without directly injecting blow water into the heat transfer tube in the exhaust gas passage.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to the drawings. Figure 1 is a cross-sectional view of the boiler and an economizer in one embodiment related to the present onset bright. The boiler 1 burns a flame with the combustion device 4, generates a high-temperature combustion gas by the flame, and heats can water with the combustion gas to generate steam. The generated steam is sent to the steam separator 9 and separated into steam and can water, and the separated can water is left in the boiler and only the steam is taken out. The exhaust gas after the temperature is lowered by heating the can water is exhausted through the exhaust gas passage 2, and an economizer 7 is provided in the middle of the exhaust gas passage 2. A large number of heat transfer tubes 3 extending in the horizontal direction are provided in the economizer 7, and a number of heat absorbing fins 5 are attached to the heat transfer tubes 3. Each heat transfer pipe in the economizer 7 is connected by a bend pipe to form a continuous water supply flow path, and the exhaust gas that has reached the economizer 7 flows downward between the heat transfer pipes 3 in the economizer 7. Yes.
[0007]
Water supplied into the economizer enters from the lowermost heat transfer tube of the heat transfer tube group, reaches the uppermost heat transfer tube while being sequentially heated through the heat transfer tubes, is taken out from the economizer, and is supplied into the boiler 1. Therefore, the water temperature of the feed water sent through the heat transfer tube is lower at the lower stage and higher at the upper stage. Further, since the exhaust gas sent from the boiler to the economizer 7 flows downward while exchanging heat with the heat transfer tube in the economizer, the temperature of the exhaust gas becomes lower as it goes downward in the economizer. For this reason, condensation of moisture contained in the exhaust gas occurs on the lower heat transfer tube surface on the downstream side of the exhaust gas flow, and heat generated by the condensation of moisture is absorbed by the heat transfer tube.
[0008]
In the case of FIG. 1, one end is connected to the steam separator 9 and the other end is connected to the exhaust gas passage 2, and a blow water pipe 10 for flushing the blow water into the exhaust gas passage 2 is provided. A flash control valve 11 is provided in the middle of the blow water pipe 10. When the flash control valve 11 is opened, blow water is sent into the exhaust gas passage 2. Since the pressure inside the boiler is high, the pressure of the blow water taken out from the boiler is also high. When high temperature and high pressure blow water is injected into the low pressure exhaust gas passage 2, steam is generated from the blow water. When the blow water is directly injected onto the heat transfer pipe 3, the amount of steam generated from the blow water is reduced, and heat recovery from the exhaust gas cannot be performed at the portion where the blow water is in contact. Therefore, the partition plate 12 is provided in the exhaust gas passage 2 so that the blow water does not directly contact the heat transfer tube 3 and only the steam generated from the blow water contacts the heat transfer tube 3. Blow water is injected to the part separated by the partition plate 12, and steam generated from the blow water is supplied to the exhaust gas.
[0009]
By generating steam in the exhaust gas passage 2, the amount of moisture in the exhaust gas increases. When the amount of moisture in the exhaust gas increases, the dew point of the exhaust gas rises, and condensation of the moisture in the exhaust gas begins at an earlier stage, so that the amount of latent heat recovered from the exhaust gas can be increased. Further, when the amount of water in the exhaust gas is increased, the amount of condensed water also increases, so that the amount of latent heat recovered from the exhaust gas increases. Furthermore, since the steam itself generated in the exhaust gas passage 2 also has heat, the heat transfer tube is also heated by the heat of the steam.
[0010]
By these things, since the heat recovery efficiency in the latent heat recovery part of the economizer is improved and the amount of heat recovery is increased, the efficiency of the boiler is improved. In this case, the heat recovery amount is larger than that in the case where the feed water before being introduced into the economizer is heated by blow water, and then the heat is recovered from the exhaust gas by the economizer.
[00 11 ]
【The invention's effect】
By carrying out the present invention, the heat recovery efficiency in the latent heat recovery unit can be improved, so that the amount of latent heat recovery can be increased. Further, since the heat recovery efficiency is improved, the number of heat transfer tubes can be reduced, and the latent heat recovery economizer can be downsized.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a boiler and an economizer of an embodiment relating to claim 1 of the present invention.
DESCRIPTION OF SYMBOLS 1 Boiler 2 Exhaust gas passage 3 Heat transfer pipe 4 Combustion device 5 Heat absorption fin 6 Flame 7 Economizer 8 Water spray device 9 Steam-water separator 10 Blow water piping 11 Flash control valve 12 Partition plate

Claims (1)

Steam is generated using the combustion gas obtained by the flame generated by the combustion device, and the exhaust gas whose temperature has decreased due to heat exchange is discharged through the exhaust gas passage. An economizer is installed in the exhaust gas passage to preheat the water supply. The economizer is a latent heat recovery boiler that collects not only sensible heat of exhaust gas but also latent heat, and provides a partition plate that divides the heat transfer tube installation part in the exhaust gas passage and is divided by the partition plate The high-pressure blow water discharged from the boiler is flushed at the part divided by the partition plate, so that the blow water is not injected directly into the heat transfer pipe in the exhaust gas passage, and the steam is discharged into the exhaust gas passage. By increasing the amount of moisture contained in the exhaust gas at the economizer part, the heat recovery efficiency at the latent heat recovery part of the economizer is improved. The heat recovery amount increasing device in the latent heat recovery boiler, wherein the door.

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