JPH10169907A - Boiler plant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve a higher heat efficiency utilizing remaining heat held by steam by a method wherein blow water extracted from boiler circulation water or a drain generated in a boiler steam system undergoes a steam separation and the steam separated is recovered to a steam condenser in a steam recovery line to be condensed for re-using as boiler circulation water. SOLUTION: Boiler circulation water (blow water) in a boiler drum 2 extracted from a boiler drum 2 and a drain compressed by a steam system of a boiler plate 10 is passed through a blow line 4 to be blown into a flash tank 3 and separated into a steam component and a drain component under a reduced pressure. The steam component thus separated is recovered to a steam condenser 5 through a steam recovery line 6. The drain recovered by the condensing of the stream recovered to the steam condenser 5 is turned to boiler circulation water in the steam condenser 5 together with condensed water obtained by the condensing of the steam discharged from a steam turbine 11. The boiler circulation water is sent to a boiler 1 again via a condensate pump 7, a deaerator, a heater 8 and a boiler feed pump 9 and turned to steam to drive the steam turbine 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a boiler plant applied to a thermal power plant and the like, and in order to prevent the concentration of impurities in the boiler circulating water of a drum type boiler, the boiler circulating water retained in a boiler drum is removed. To reduce and replenish the boiler circulating water by reducing the supply of boiler circulating water by using and recovering the blow water for the blow performed by extraction and the drain water generated for the drain generated in the boiler steam system. Boiler plant.

[0002]

2. Description of the Related Art In a drum type boiler constituting a boiler plant, as the operation time elapses, the boiler circulating water circulating in the boiler plant is evaporated and concentrated, and is maintained at a high temperature for a long time. Minutes are precipitated, and impurities such as scale or sludge are generated, causing various problems. In other words, if the precipitated impurities are left untreated, iron rust formed by corrosion and silicic acid (SiO ₂ ) in the boiler circulating water
To form a scale, reducing the heat transfer efficiency in the boiler heat transfer section, causing fuel loss, or reducing the pipe water supply capacity of a heat transfer pipe or a water supply pipe, or causing precipitation in the heat exchanger. Problems such as a decrease in plant efficiency.

[0003] Therefore, as one method for preventing the concentration of impurities in the boiler circulating water and keeping the water quality normal, boiler circulating water staying in a boiler drum through a blow line,
2. Description of the Related Art A blow operation for removing so-called boiler can water from blown water from a boiler circulating water system to simultaneously remove impurities is performed. In a boiler plant,
In particular, a drain is generated in the steam system at an early stage of the startup, and such a drain is blown through a blow line in the same manner as the blow water, so that the quality of the boiler circulating water is normally maintained.

FIG. 3 is a diagram showing a schematic system of a conventional boiler plant in which high-temperature, high-pressure blow water extracted from such a boiler drum is blown.
In addition, in order to simplify the description, in the following description including the description of these drawings, only the blow water for blowing the boiler circulating water will be described, but the above-described drain blow is performed in the same manner. .

[0005] As shown in the figure, in a boiler plant 50, steam driven by a steam turbine 51 is supplied to a condenser 52.
And condensed by exchanging heat with cooling water in the condenser 52,
The condensate is pumped out by a condensate pump 53, passes through a deaerator, a heater 54, etc., is boosted in pressure by a water supply pump 55, becomes steam again in the boiler 56, and forms a steam cycle to be supplied to the steam turbine 51. Have been. When such a steam cycle in which the boiler circulating water is circulated in the boiler plant 50 is repeated, impurities in the boiler circulating water are removed.
Concentrate in 7 to produce scale.

Accordingly, a blow line 58 is provided in the boiler circulating water system, and the high temperature and high pressure boiler circulating water in the boiler drum 57 is supplied to the blow line 5.
When blown into the flash tank 59 or the flash pipe through 8 and the pressure is reduced to about atmospheric pressure, the blow water is separated into steam and water by self-evaporation.

[0007] The steam component of the blow water separated from the steam is discharged to the atmosphere through a silencer 60, and the high-temperature drain component is also discharged from the drain pipe 61 to the outside of the boiler circulating water system. In addition, since the impurities generated in the boiler circulating water at the time of this blowing are discharged out of the boiler circulating water system together with the high-temperature drain, the impurities are prevented from being concentrated in the boiler circulating water and the above-described problem occurs. be able to. In the figure, reference numeral 62 denotes a circulating water supply line.

However, the boiler drum 5
In the boiler plant in which all the boiler circulating water extracted and blown from the inside of the boiler 7 is discarded outside the boiler circulating water system, the steam content discharged into the atmosphere and the high temperature discharged out of the boiler circulating water system The boiler circulating water corresponding to the drain must be newly supplied to the boiler circulating water system. Therefore, it is necessary to install a large-capacity fresh water generator having a large capacity to newly produce pure water as replenishing water for replenishing the boiler circulating water discarded outside the system in the boiler plant 50. Burden on equipment costs, operating costs, etc.

As shown in FIG. 4, in order to solve this problem, the high-temperature drainage discharged from the drain pipe 61 among the blow water separated by steam and water in the flash tank 59 is stored in the drain tank 63 as shown in FIG. From the drain tank 63 by the drain pump 64 and the condenser 5 by the condensate pump 53
The system is returned to the boiler circulating water system pumped out from 2, and impurities are removed by a purifying device 65 (pure water device), collected and reused, and the amount of makeup water supplied from the circulation water supply line 62 is reduced. There is also a boiler plant 50 'in which the capacity of the fresh water generator is reduced to reduce the burden on facility costs, operation costs, and the like.

[0010] However, in the boiler plant shown in FIG. 4 in which the high-temperature drain is separated from the steam and the high-temperature drain by the flash tank 63 or the like, the boiler circulating water such as silica is used. Since the components that should not be contained in the boiler are concentrated and exist therein, it is necessary to pass the water through the purification device 65 as described above in order to recover the boiler circulation water again. However, there is a problem that the equipment cost and the operation cost are required. In addition, when the blow water extracted from the boiler drum 57 is blown in the flash tank 59 as the temperature and pressure are increased, the proportion of steam becomes larger than that of the high-temperature drain. There was also a problem that the recovery efficiency of blow water that could be recovered as make-up water was not as good as that of a boiler plant.

Further, in any of the boiler plants 50 and 50 'shown in FIGS. 3 and 4, the steam content of the blow water separated in the flash tank 63 is discharged to the atmosphere. Compared to high temperature drain,
The steam containing a small amount of impurities is wasted, and the thermal energy of the steam is also wasted, and the heat efficiency of the boiler plants 50 and 50 ′ is improved together with the above-mentioned problems associated with makeup water. There was also a problem that it was hindered.

[0012]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problem of the conventional boiler plant by blowing blow water extracted from a boiler drum or drain condensed in a steam system of the boiler plant. The generated steam is collected in a condenser to be condensed, make-up water is collected from the steam at the time of blowing, and reused as boiler circulating water. Compared to the case where the content of mineral components such as silica is very low, and it is cleaned by condensation, and the higher the temperature and pressure of the blow water and drain, the greater the proportion of steam during flashing Therefore, an object of the present invention is to provide a boiler plant in which the higher the temperature and pressure of a large-capacity boiler plant, the higher the efficiency of make-up water recovery.

Further, in addition to the above, the present invention utilizes steam generated by blowing blow water as a heating medium for a heat exchanger for steam tracing and the like.
It is an object of the present invention to provide a boiler plant that recovers residual heat of steam to improve thermal efficiency.

[0014]

Therefore, the first boiler plant of the present invention has the following means.

(1) Blow water extracted from boiler circulating water staying in the boiler drum through a blow line disposed between the boiler drum and the flash unit, or boiler at the beginning of boiler plant startup, etc. The drain generated in the steam system is flashed by a flash device of a blow-down system provided in a boiler plant to remove impurities in the boiler circulating water, and is separated into steam and water. The steam is collected in the condenser by the steam recovery line arranged between the flash unit and the condenser,
It was condensed and reused as boiler circulating water.
In addition, the moisture separated by steam and water by a flash device, so-called high-temperature drain, may be discharged to the outside as it is, or the heat energy held by the drain may be recovered by a heat exchanger and then discharged to the outside. May be.

(A) In the boiler plant of the present invention, the steam separated from the steam by the flash device is collected in the condenser by the above-described means, condensed, and then reused as boiler circulating water circulating in the boiler plant. Conventionally, make-up water equivalent to the steam that is discharged into the atmosphere and is generated by air-water separation during blowing and the high-temperature drain discharged to the outside of the boiler circulating water system is supplied with boiler circulating water. The system had to be replenished, but at least the steam was recovered, so the amount of replenishment water to be supplied to the boiler circulating water could be reduced accordingly, and the capacity to produce pure water as make-up water Therefore, there is no need to install a large-scale desalination apparatus having a large size, and the burden on facility costs, operation costs, and the like is reduced.

[0017] This reduction of the burden is caused by the fact that the higher the temperature and pressure of the blow water extracted from the boiler drum, the greater the rate of vaporization in the flash unit than the rate of drainage. The more boiler plants, the better the efficiency of blow water recovery as boiler circulating water,
It is advantageous because the amount of makeup water can be reduced.

Further, the makeup water obtained by collecting steam condensed in the steam and water and condensing it for use as boiler circulating water has a very low content of minerals such as silica, and , Which can be cleaned by condensing, eliminating the need for a purification device required for purifying make-up water, which collects drainage and turns it into boiler circulating water, or can be made at least a small capacity, and furthermore, the boiler heat transfer section In the boiler circulating water, which lowers the heat transfer efficiency and causes fuel loss, lowers the water transfer capacity of pipes such as heat transfer pipes or water supply pipes, or reduces the plant efficiency by precipitation in heat exchangers. Solid content is precipitated, and the generation of impurities such as scale or sludge and the problems caused by the generation of these impurities can be eliminated.

The second boiler plant of the present invention has the following means. (2) Similar to the above means (1), the blow water or the drain is flashed by a flash device to separate steam and water. ,
The steam separated by this water / water separation is supplied to the heat exchanger by a steam recovery line arranged between the flash unit and the heat exchanger, and after being used as a heating medium, it is condensed or semi-condensed. The steam thus collected was collected in a condenser through a condensed water collection line disposed between the heat exchanger and the condenser, and was reused as boiler circulating water. In the present invention, the moisture separated by water and flash in the flash device, so-called drain, may be discharged to the outside as it is, and the heat energy held by the drain is recovered by a heat exchanger.
It may be discharged outside the boiler circulation water system.

In the boiler plant of the present invention, the steam separated by the flash unit by the above-described means is supplied to a heat exchanger for steam tracing or the like and used as a heating medium for the heat exchanger. Is reused as boiler circulating water for circulating water, so that in addition to the above (a), the residual heat of the steam can be recovered and used effectively, and the thermal efficiency of the boiler plant can be improved. .

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a boiler plant according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a first embodiment of the boiler plant of the present invention.

As shown in the figure, in the boiler plant 10 of the present embodiment, the boiler drum 2 of the drum type boiler 1 is supplied to the flash tank 3 as a flash device.
A blow line 4 is provided, and boiler circulating water in the boiler drum 2, which is extracted from the boiler drum 2, so-called blow water, and drain condensed in the steam system of the boiler plant 10 are passed through the blow line 4 to a flash device. Is blown into the flash tank 3 and decompressed to separate steam and water into steam and drain.

The steam that has been separated from the steam is separated into a steam recovery line 6 that connects the flash tank 3 and the condenser 5.
Through the condenser 5. The drain collected by condensing the steam collected in the condenser 5 becomes condensed and exhausted from the steam turbine 11 in the condenser 5 and becomes condensed water as boiler circulating water. The steam is again sent to the boiler 1 via the heater, the heater 8 and the water supply pump 9 to become steam, and the steam turbine 11 is driven. The high-temperature drain blown into the flash tank 3 and separated into steam and water is discharged from the drain pipe 12 to the outside of the system.

Thus, most of the impurities in the boiler circulating water are discharged from the drain pipe 12 to the outside of the boiler circulating water system together with the high-temperature drain before being concentrated in the boiler drum 2. If necessary, a switching valve is provided so that the flash tank 3 and the condenser 3 can be isolated from each other.
Further, by providing an open-to-atmosphere pipe so that the steam separated from water and water can be released to the atmosphere, versatile operation can be achieved.

As described above, according to the boiler plant 10 of the present embodiment, the supply of pure water to the boiler circulating water system is greatly reduced only by providing a line communicating from the flash tank 3 to the condenser 5. It is possible to reduce at least the capacity of the fresh water generator required for producing the makeup water, and to reduce the cost of equipment and the consumption of utilities and the like. Further, in the boiler plant of the present embodiment, by using condensed water obtained by recovering steam as replenishing water to be supplied to the boiler circulating water system, pure pure water with little silica or the like can be obtained. In addition, the burden on the purification device 65 provided in the boiler circulating water system can be reduced.

Furthermore, since the amount of steam separated in the flash tank 3 is greater in the high-temperature and high-pressure boiler blow water and the drain, the supply water is more recovered than in the case of collecting makeup water from the separated drain. A large amount of make-up water can be recovered, and the larger the boiler plant 10 is, the more water is saved, and the load on the pure water apparatus for producing boiler make-up water is reduced.

Next, FIG. 2 is a block diagram showing a second embodiment of the boiler plant according to the present invention.

As in FIG. 1, the blow water and the drain discharged from the boiler drum 2 are depressurized in the flash tank 3, and are separated into steam and drain by steam and water. In the boiler plant 20 of the present embodiment, the steam component thus separated into steam and water is sent to the heat exchanger 13 for steam tracing or the like, used as a heating medium, and subjected to heat exchange. The condensed water is collected in the condenser 5 from the heat exchanger 13 by a condensed water recovery line 14 disposed in the condenser 5 and is again used as boiler circulating water.

The drain separated in the flash tank 3 is stored in a drain tank 15 via a drain pipe 12, so that heat energy in the drain can be used. Thus, the boiler plant 2 of the present embodiment
According to No. 0, in addition to the boiler plant of the first embodiment described above, the blow water discharged from the boiler drum 2 and the drain condensed in the boiler steam system are depressurized in the flash tank 3 to reduce the steam content and the water content. By sending the steam separated to the heat exchanger 13 to use it as a heating medium for steam tracing and the like, the residual heat can be recovered, and the condensed water can be reused as boiler water. Thereby, the thermal efficiency of the boiler plant can be improved as compared with the boiler plant of the first embodiment.

[0030]

As described above, according to the boiler plant of the present invention, according to the constitution set forth in the claims, (1) replenishment of the boiler circulating water discharged out of the boiler circulating water system by blowing. The amount of make-up water to be performed can be reduced, the capacity of a fresh water generator for producing pure water make-up water can be reduced, and equipment costs and utility costs can be reduced. Further, the larger the capacity of the boiler plant, the more the makeup water obtained from the blow water becomes, and the quantity of the makeup water from the fresh water generator can be reduced.

(2) The make-up water obtained from the blow water is close to pure water, so that a purifying device can be made unnecessary, or at least the load on the purifying device can be reduced.

(3) The thermal efficiency of the boiler plant can be improved by recovering the heat of the steam that is obtained from the blow water and becomes makeup water.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of a boiler plant according to the present invention;

FIG. 2 is a block diagram showing a second embodiment of the boiler plant according to the present invention;

FIG. 3 is a block diagram showing an example of a conventional boiler plant.

FIG. 4 is a block diagram showing another example of a conventional boiler plant.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Drum type boiler 2 Boiler drum 3 Flash tank 4 Blow line 5 Condenser 6 Steam recovery line 7 Condenser pump 8 Circulating water heater 9 Feed water pump 10 Boiler plant 11 Steam turbine 12 Drain pipe 13 Heat exchanger 14 Condensed water recovery Line 15 Drain tank 20 Boiler plant 50, 50 'Boiler plant 51 Steam turbine 52 Condenser 53 Condenser pump 54 Heater 55 Water supply pump 56 Boiler 57 Boiler drum 58 Blow line 59 Flash tank 60 Silencer 61 Drain pipe 62 Circulating water Supply line 63 Drain tank 64 Drain pump 65 Purifier

Claims (2)

[Claims] In a boiler plant provided with a blowdown system for removing impurities in boiler circulating water, blow water extracted from the boiler circulating water in a boiler drum through a blow line and / or generated in a boiler steam system. The drain is flashed by a flash device provided in the blow-down system to separate steam and water, and the separated steam is collected in a condenser by a steam recovery line to be used as the boiler circulating water. Boiler plant characterized. 2. The steam is supplied to a heat exchanger in the steam recovery line, and is used as a heating medium. Then, the steam is recovered in a condensed water recovery line by a condenser and used as the boiler circulating water. The boiler plant according to claim 1, wherein: