JPH10132207A - Boiler facility - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the increase in the temperature of the supplied water of a boiler that passes through an economizer, and to maintain a large temperature difference between a combustion gas and the supplied water of the boiler by returning one portion of the supplied water of the boiler that has passed through the heat transfer pipe of the economizer to a deaerator and increasing the amount of the supplied water of the boiler that passed through the economizer. SOLUTION: The boiler facility has a steam generation part 5 for turning supplied water 4 of a boiler into a steam 4a, a steam usage part 7 that is connected to the steam generation part 5, a steam condenser 11 that is connected to the steam usage part 7, a deaerator 13 that is connected to the steam condenser 11, and an economizer 15 that is connected halfway to a boiler water- supply pipeline 14 for connecting the deaerator 13 to the steam generation part 5 and is provided at an exhaust pipeline 3. In this case, a branch steam pipeline 16 for extracting a portion of the steam being generated at the steam generation part 5 to the deaerator 13 is connected halfway to a steam pipeline 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a boiler facility which utilizes, for example, thermal energy of a combustion gas generated when incinerating wastes for power generation.

[0002]

2. Description of the Related Art Conventionally, there is a boiler facility which utilizes thermal energy for incinerating waste for power generation.

[0003] As shown in FIG.
Reference numeral 0 denotes a steam generator (for example, a combustion chamber and a boiler integrated with the combustion chamber) 63 which is provided in the exhaust pipe 62 of the combustion gas 61 and is heated by the combustion gas 61 to turn the boiler feed water into steam. A steam-using section (steam turbine or the like) 65 connected to the generating section 63 via a steam pipe 64
A condenser 66 connected to the steam using section 65, a deaerator 68 connected to the condenser 66 via a condenser pipe 67, a deaerator 68 and a steam generating section 63, And an economizer (also referred to as a economizer) 71 which is connected in the middle of a water supply pipe 70 connecting the steam generator 63 with the steam generation section 63 and which is mounted on the exhaust downstream side of the exhaust pipe 62. A condensate pump 72 is provided in the middle of 67, and a water supply pump 74 for supplying boiler water 73 from the deaerator 68 to the steam generator 63 is provided in the middle of the water supply line 70.

[0004] In the boiler equipment 60 configured as described above, the boiler water 73 supplied from the deaerator 68 to the steam generator 63 by the water supply pump 74 passes through the heat transfer tube 76 of the economizer 71 and burns on the way. Heat is exchanged with the gas 61 to be heated in advance, and then the heated boiler feedwater 73 is supplied to the steam generation unit 63 to become steam 76, and passes through the steam pipe 64 to the steam use unit 65. After the work is performed on the steam using section 65, the condensed water is condensed by a condenser 66 to become condensed water 75, and then sent to a deaerator 68 by a condensate pump 72. Degassed.

The temperature of the boiler feed water 73 from the deaerator 68 to the heat transfer tube 76 of the economizer 71 increases due to heat exchange with the combustion gas 61.
The temperature of the combustion gas 61 is lowered to a predetermined temperature and discharged from the exhaust pipe 62.

When heat exchange is performed between the combustion gas 61 and the boiler feed water 73 passing through the heat transfer tube 76, the heat exchange rate increases as the temperature difference between the two increases. The temperature of the boiler feed water 73 is 130 °
It is set relatively high at about 140 °.

[0007] The reason is that the combustion gas 61 generated when burning waste such as municipal waste contains chlorine and sulfuric acid gas, so that the boiler feed water 73 passing through the heat transfer pipe 76 is used.
If the temperature is lowered, the surface temperature of the heat transfer tube 76 becomes lower than the acid dew point temperature, and low-temperature corrosion occurs.

[0008]

In the conventional boiler equipment 60, the heat exchange rate in the economizer 71 can be improved by increasing the temperature difference between the combustion gas 61 and the boiler feed water 73. The temperature of the boiler feed water 73 passing through the heat transfer tube 76 cannot be reduced in order to prevent low-temperature corrosion of the boiler.

Therefore, if the heat transfer area of the heat transfer tube 76 in the economizer 71 is increased, a predetermined heat exchange rate can be obtained without lowering the temperature of the boiler feed water 73. However, if the economizer 71 is configured as described above, There is a problem that it is large and uneconomical, and a large space must be secured for installing the economizer 71.

[0010] Therefore, an object of the present invention is to provide a boiler facility capable of solving the above-mentioned problems.

[0011]

Means for solving the problems of the present invention are: a steam generating section for heating boiler feed water into steam by heating with a combustion gas; and a steam feeding section of the steam generating section. A steam-using section connected via a pipe, a condenser connected to the steam-using section to condense the used steam and condense water, and a condensate feed side of the condenser. A deaerator connected via a condensate line to deaerate condensate water, and connected to a midway of the boiler water supply line connecting the deaerator and the steam generator, and attached to the exhaust line Since a return pipe for returning a part of the boiler feed water after heat exchange to the deaerator is connected to the boiler feed pipe line on the steam generating section side of the economizer, Degassing part of the boiler feedwater that passed through the heat transfer tubes of the economizer 1 By increasing the amount of boiler feedwater passing through the economizer, the rise in the temperature of the boiler feedwater passing through the economizer is suppressed, and the temperature difference between the combustion gas and the boiler feedwater is kept large. The heat exchange rate in the economizer is improved without increasing the heat transfer area of the heat transfer tube.

Further, an economizer connected to the middle of a boiler feed line connecting the deaerator and the steam generator and attached to an exhaust line is provided, and one of the boiler feed water supplied from the deaerator is provided. A return pipe is provided for returning the section to the deaerator again, and a feedwater heater for heating a part of the boiler feedwater provided in the exhaust pipe and connected to the return pipe is provided. The boiler feedwater supplied to the steam generator is heated, and the combustion gas is recovered when passing through the feedwater heater, so the heat transfer tubes of the economizer and the feedwater heater The heat exchange rate can be improved without increasing the heat transfer area.

Further, a return pipe for returning a part of the boiler feed water supplied from the deaerator to the deaerator is provided. The return pipe is connected in the middle of the return pipe and attached to an exhaust pipe. A feed water heater is provided for heating a part of the boiler feed water, and a boiler feed line is provided for supplying the remaining part of the boiler feed water supplied from the deaerator to the steam generator, and steam is used. A branch steam line is provided to extract a part of the steam used in the section to the deaerator, and a boiler feed line is connected in the middle of this branch steam line to preheat the boiler feed water. Since the vessel was provided,
The boiler feedwater is heated by the preheater to easily generate steam to improve the efficiency of the steam cycle, and since the heat recovery of the combustion gas is performed only by the feedwater heater, the temperature difference between the combustion gas and the boiler feedwater is large. Therefore, the heat exchange rate is improved.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a boiler facility according to an embodiment of the present invention will be described with reference to the drawings. First, a first embodiment of the present invention will be described with reference to FIGS.

The boiler equipment 1 according to the first embodiment of the present invention utilizes the heat energy of the combustion gas 2 generated when the waste is incinerated for power generation. A steam generator 5 attached to the passage 3 and heated by the combustion gas 2 to turn the boiler feedwater 4 into steam 4a; and a steam connected to a steam feed side of the steam generator 5 via a steam pipe 6 A condensing unit 11 connected to the steam using unit 7 through an air guide line 8 to condense the used steam 4a into condensate 10; A deaerator 13 connected to the water feed side via a condensing pipe 12 to deaerate the condensate 10;
An economizer 15 is provided in the exhaust pipe 3 while being connected in the middle of a boiler feed pipe 14 connecting the steam generator 3 and the steam generator 5.

In the middle of the steam line 6, a branch steam line 16 for extracting a part of the steam generated in the steam generating section 5 to the deaerator 13 is connected. A condensate water supply pump 17 is connected in the middle of the condensate conduit 12 and connects to the deaerator 13 and the economizer 15, that is, the boiler feed line 14, that is, the boiler feed line ( In the middle of 14A, the boiler feed pump 1
8 are connected.

The steam generator 5 of the economizer 15
Boiler feed line (hereinafter referred to as "second feed line") 1
4B, a return pipe 2 for returning a part of the boiler feed water 4 after the heat exchange (hereinafter referred to as “circulating water 4A”) to the deaerator 13
0 is connected, and a pressure control valve 21 is attached in the middle of the return pipe 20.

The economizer 15 has a main body 22 connected in the middle of the exhaust pipe 3 and a main body 22 connected between the first water supply pipe 14A and the second water supply pipe 14B.
And a heat transfer tube 23 provided therein.

In the above configuration, the combustion gas 2 generated when the waste is incinerated passes through the exhaust pipe 3 toward the outlet. By the way, the boiler feed water 4 supplied to the steam generation unit 5 after being heated as described later absorbs heat from the combustion gas 2 to become steam 4a, and passes through the steam pipe 6 to the steam use unit 7. At this time, work is performed on the steam use unit 7. Further, a part of the steam 4a passing through the steam pipe 6 is extracted to the branch steam pipe 16 on the way to the steam use part 7 and supplied to the deaerator 13, and is supplied to the deaerator 1 as the branch steam 4a.
3 used to heat.

On the other hand, the steam 4a that has worked for the steam use section 7 passes through the air guide line 8 by the driving of the condensate water supply pump 17, is condensed by the condenser 11 and becomes the condensate 10, and subsequently Through the condenser line 12, it reaches the deaerator 13.

Then, the steam 4a extracted to the deaerator 13
The condensate 10 is deaerated by the deaerator 13 to become the boiler feedwater 4, supplied to the first feedwater pipe 14 </ b> A by driving the boiler feedwater pump 18, and subsequently reaches the heat transfer pipe 23 of the economizer 15.

The boiler feed water 4 is heated by absorbing heat from the combustion gas 2 while passing through the heat transfer tube 23, and a certain amount of the heated boiler feed water 4 is converted into a steam generating part. 5 is supplied. On the other hand, the heat transfer tube 23
The combustion gas 2 that has given heat to the boiler feedwater 4 that has passed through is cooled to a predetermined temperature (190 ° to 200 °) and discharged from the outlet of the exhaust pipe 3.

Then, a part of the boiler feed water 4 that has passed through the heat transfer tube 23 reaches the return pipe 20 and is returned to the deaerator 13. Thereafter, the steam is deaerated together with the steam 4a and the condensate 10 extracted to the deaerator 13, passes through the first water supply pipe 14 </ b> A, reaches the heat transfer pipe 23, and is heated by the combustion gas 2.

Here, the following Table 1 shows a comparison of the heat transfer area of the heat transfer tube 23 required in the conventional example and the present invention, or a comparison of the quality of the heat exchange rate.

[0025]

[Table 1]

That is, in the conventional example and the present inventions 1, 2, and 3, the amount of combustion gas passing through the return pipe 20, the gas temperature at the economizer inlet, and the water supply temperature at the economizer inlet are fixed. Circulating water volume, economizer 15
(Since the amount of boiler supplied to the steam generator 5 is constant, the amount of circulating water 4A can be increased regardless of the amount of boiler supplied.)

The unit of the combustion gas amount is m ³ / h, the unit of the gas temperature and the supply water temperature is ° C., the unit of the circulating water amount is m ³ , the unit of the boiler supply water amount is m ³ , and the heat transfer of the heat transfer tube 23 The unit of area is
a m ^2.

In Table 1, for example, the boiler feedwater 4 is entirely supplied to the steam generator 5 (the amount of circulating water is 0) as in the conventional example, and the economizer using the circulating water 4A as in the first embodiment of the present invention. In comparison with the case where the boiler water supply amount to the boiler 15 is increased, the water supply temperature at the outlet of the economizer is the present invention 1
It can be seen that the heat exchange rate is improved by this, and that the heat transfer area of the heat transfer tube 23 can be made smaller with the present invention 1.

According to the second aspect of the present invention, in which the amount of circulating water is increased as compared with the first aspect of the present invention, even if the heat transfer area of the heat transfer tube 23 is further reduced, the water supply temperature at the economizer outlet becomes the same as that of the first aspect of the present invention. It can be seen that the heat exchange rate was good.

In the third embodiment, the heat transfer area of the heat transfer tube 23 is equal to that of the conventional example. According to the third embodiment, the gas temperature at the outlet of the economizer is lower than that of the first and second embodiments. (190 ° C.).

As described above, a part of the boiler feed water 4 that has passed through the economizer 15 (its heat transfer tube 23) is returned to the deaerator 13 and supplied to the economizer 15 again. By increasing the amount of boiler feed water 4
5 is suppressed, and the temperature difference between the combustion gas 2 and the boiler feedwater 4 is kept large, so that the heat in the economizer 15 is increased without increasing the heat transfer area of the heat transfer tube 23. The exchange rate can be improved, and the size of the economizer 15 can be prevented.

The boiler feedwater 4 returned to the deaerator 13 is decompressed by the deaerator 13, so that the economizer 15
Flash steam is generated in accordance with the amount of heat heated in the above. Therefore, the amount of steam 4a for heating the deaerator 13 can be reduced, and the amount of steam 4a sent to the steam use unit 7 can be increased accordingly. Thus, the steam 4a can be used effectively.

Next, a second embodiment of the present invention will be described with reference to FIG. The boiler equipment 1 according to the second embodiment of the present invention is provided with a steam generation unit 5 attached to an exhaust pipe 3 of the combustion gas 2 and heated by the combustion gas 2 to turn the boiler feed water 4 into steam 4a. A steam use section 7 connected to a steam feed side of the steam generation section 5 via a steam pipe 6 and a steam 4a used after being connected to the steam use section 7 via an air guide pipe 8 to condense. A condenser 11 for condensing water and a condenser line 1 on the condensate feed side of the condenser 11.
A deaerator 13 for deaeration of the condensate 10 which is connected through the second exhaust pipe 2 and a boiler water supply line 14 connecting the deaerator 13 and the steam generator 5, and an exhaust pipe And an economizer 15 provided on the road 3.

A return pipe 2 for returning a part of the boiler feed water 4 supplied from the deaerator 13 to the deaerator 13 again.
5 is provided in the exhaust pipe 3 and connected to the middle of the return pipe 25 for heating a part of the boiler feed water 4 (hereinafter referred to as “circulating water 4A”).
The feed water heater 26 is disposed downstream of the exhaust pipe 3 with respect to the steam generating section 5 and the return pipe 25 is provided.
A pressure control valve 27 is provided on the side of the deaerator 13.

The feed water heater 26 is composed of a heater body 28 disposed in the exhaust pipe 3 and a heat transfer pipe 30 connected to the return pipe 25 and housed in the heater body 28. It is configured.

The economizer 15 includes an economizer main body 22 disposed in the middle of the exhaust pipe 3 and the boiler feed pipe 1.
4 and a heat transfer tube 23 provided inside the economizer body 22.

In the middle of the steam line 6, a branch steam line 16 for extracting a part of the steam generated in the steam generating section 5 to the deaerator 13 is connected. A condensate water supply pump 17 is connected in the middle of the condensate line 12, and a boiler water supply pump 18 is connected in the middle of a boiler water supply line 14 connecting the deaerator 13 and the economizer 15. , Return pipe 2
In the middle of 5, a circulating water pump 31 is connected.

In the above configuration, the combustion gas 2 generated when the waste is incinerated passes through the exhaust pipe 3 toward the discharge port. By the way, the boiler feed water 4 supplied to the steam generation unit 5 after being heated as described later absorbs heat from the combustion gas 2 to become steam 4a, and passes through the steam pipe 6 to the steam use unit 7. At this time, work is performed on the steam use unit 7. Further, a part of the steam 4a passing through the steam pipe 6 is extracted to the branch steam pipe 16 on the way to the steam use part 7 and supplied to the deaerator 13, and is supplied to the deaerator 1 as the branch steam 4a.
3 used to heat.

On the other hand, the steam 4a that has worked for the steam use section 7 passes through the air guide line 8 by the drive of the condensate water supply pump 17, is condensed in the condenser 11 and becomes the condensate 10, and subsequently. Through the condenser line 12, it reaches the deaerator 13.

Then, the steam 4a extracted to the deaerator 13
The condensate 10 is degassed by the deaerator 13 to become the boiler feed water 4, and a certain amount of the boiler feed water 4 is supplied to the boiler feed line 14 by driving the boiler feed pump 18, The heat transfer tube 23 is reached.

The boiler feedwater 4 is heated by absorbing heat from the combustion gas 2 while passing through the heat transfer tube 23, and the heated boiler feedwater 4 is supplied to the steam generator 5. By the way, a part of the boiler feedwater 4 supplied from the deaerator 13 to the steam generator 5 is driven by the circulating water pump 31.
The circulating water 4A is supplied to the feed water heater 26 through the return pipe 25, passes through the heat transfer pipe 30, and is returned to the deaerator 13 again. The circulating water 4A is deaerated together with the steam 4a extracted to the deaerator 13 and the condensate 10.

The circulating water 4A is heated by absorbing heat from the combustion gas 2 when passing through the heat transfer tube 30 of the feed water heater 26 in the same manner as the boiler feed water 4. It leads to the bronchus 13. On the other hand, the combustion gas 2 whose temperature has been lowered by the economizer 15 passes through the feed water heater 26 to give heat to the circulating water 4A and is cooled to a predetermined temperature, and is discharged from the outlet of the exhaust pipe 3. You.

Here, a comparison between the heat transfer areas of the heat transfer tubes 23 and 30 required in the conventional example and the second embodiment of the present invention is described.
It is shown in the following (Table 2).

[0044]

[Table 2]

In Table 2 below, for example, Conventional Example 3
When comparing the gas temperature at the outlet of the economizer in the conventional example 3 with the gas temperature at the outlet of the feed water heater, the economizer 15 of the present invention 4 is compared.
The conventional example 3 in which the total area of the heat transfer tube 23 and the total heat transfer area of the heat transfer tube 30 of the feed water heater 26 is only an economizer is provided.
Approximately 80% of the total.

Also, in the fifth invention, the amount of circulating water (the amount of water supplied to the feed water heater 26) is increased as compared with the fourth invention, and the total heat transfer area is smaller than in the fourth invention. The present invention 6 is a case where the total heat transfer area is set to the same level as that of the conventional example 2, and the gas temperature (1
73 ° C.) can be further reduced, and it can be seen that the heat exchange rate is improved.

As described above, the feed water heater 26 different from the economizer 15 is disposed on the exhaust gas downstream side of the exhaust pipe 3 with respect to the steam generator 5, and is supplied from the deaerator 13 to the steam generator 5. A part of the boiler feed water 4 is supplied to the feed water heater 26 as circulating water 4A, and the circulating water 4A that has passed through the heat transfer tube 30 is returned to the deaerator 13 so that the heat transfer tube of the economizer 15 is used. 23 and heat transfer tube 3 of feed water heater 26
The heat exchange rate can be improved by the economizer 15 and the feed water heater 26 without increasing the heat transfer area of the zero, and thus the economizer 15 can be prevented from being enlarged.

Next, a third embodiment of the present invention will be described with reference to FIG. 3. In the second embodiment, one feed water heater 26 is provided. The form is, apart from the economizer 15, two feed water heaters 35 and 36 on the exhaust downstream side of the exhaust pipe 3 with respect to the steam generator 5.
The feed water heaters 35 and 36 are connected in the middle of return pipes 37 and 38 for returning the circulating water 4A supplied from the deaerator 13 to the deaerator 13 again. In addition,
Each feedwater heater 35, 36 is provided with a feedwater heater body 40, 41.
And heat transfer tubes 42 and 43.

The other configuration is the same as that of the second embodiment and will not be described. In the third embodiment, as in the second embodiment, the economizer can be used without increasing the heat transfer area of the heat transfer tubes 23 of the economizer 15 and the heat transfer tubes 42, 43 of the feed water heaters 35, 36. 15 and the feed water heaters 35 and 36 can improve the heat exchange rate, and can prevent the economizer 15 from being enlarged.

Next, a fourth embodiment of the present invention will be described with reference to FIG. In the fourth embodiment, a branch steam line for extracting a part of the steam generated in the steam generator 5 in the middle of the economizer 15 and the steam line 6 to the deaerator 13 in the configuration of the second embodiment. 16 is omitted.

A boiler feed line 45 for supplying a part of the boiler feed water 4 supplied from the deaerator 13 to the steam generator 5 is provided.
A first branch steam line 46 for bleeding a part of a to the deaerator 13 is provided, and the boiler feedwater 4 is supplied from the deaerator 13 to the steam generator 5 in the middle of the branch steam line 46. A preheater 48 is provided for preheating the boiler feedwater 4 by connecting a boiler feedwater line 47 to the first branch steam line 46.
Apart from this, a second branch steam line 50 for extracting a part of the steam 4 a used in the steam using section 7 to the deaerator 13 is provided.

A boiler feed pump 51 is connected in the middle of the boiler feed line 47. The other configuration is the same as the configuration of the second embodiment, and a description thereof will be omitted.

According to the fourth embodiment, a part of the steam 4a used in the steam using section 7 is bled to the deaerator 13 without being condensed in the condenser 11, and degassed in the middle of the deaeration. Since the boiler feedwater 4 supplied to the steam generator 5 from the steam generator 13 is heated by the preheater 48, the efficiency of the steam cycle can be improved, and the feedwater heater 26 is provided without the economizer. The temperature difference between the combustion gas 2 and the circulating water 4A is large, so that the heat exchange rate can be improved without increasing the heat transfer area of the heat transfer tube 30 of the feed water heater 26.

[0054]

As is apparent from the above description, the present invention is provided with an economizer connected in the middle of a boiler water supply line connecting a deaerator and a steam generator and attached to an exhaust line. Since a return pipe for returning a part of the boiler feed water after heat exchange to the deaerator is connected to the boiler feed pipe on the steam generator side of this economizer, a part of the boiler feed water that has passed through the economizer The temperature of the boiler feedwater passing through the economizer is suppressed by increasing the amount of boiler feedwater passing through the economizer by returning the air to the deaerator to reduce the temperature of the combustion gas and boiler feedwater passing through the exhaust pipe. The difference is kept large, so that the heat exchange rate can be improved without increasing the heat transfer area of the heat transfer tube of the economizer, and the economizer can be prevented from being enlarged.

Further, an economizer connected to the middle of the boiler feed pipe connecting the deaerator and the steam generator and attached to the exhaust pipe is provided, and one of the boiler feed water supplied from the deaerator is provided. A return pipe is provided for returning the part to the deaerator again, and a feedwater heater for heating a part of the boiler feedwater provided in the exhaust pipe and connected in the middle of the return pipe is provided. Therefore, by recovering the heat of the combustion gas with an economizer and recovering the heat of the combustion gas with a feedwater heater, the heat transfer tubes of the economizer and the feedwater heater can be compared with the case where only the economizer is installed. The heat exchange rate can be improved without increasing the heat transfer area.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a boiler facility showing a first embodiment of the present invention.

FIG. 2 is an overall configuration diagram of a boiler facility showing a second embodiment of the present invention.

FIG. 3 is an overall configuration diagram of a boiler facility according to a third embodiment of the present invention.

FIG. 4 is an overall configuration diagram of a boiler facility according to a fourth embodiment of the present invention.

FIG. 5 is an overall configuration diagram of a conventional boiler facility.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Boiler equipment 2 Combustion gas 3 Exhaust pipe 4 Boiler feed water 4a Steam 4A Circulating water 5 Steam generating part 6 Steam pipe 7 Steam using part 8 Air guide pipe 10 Condenser 11 Condenser 12 Condenser pipe 13 Deaerator 14 Boiler water supply line 14A First water supply line 14B Second water supply line 15 Economizer 16 Branch steam line 17 Condensate water supply pump 18 Boiler water supply pump 20 Return line 21 Pressure control valve 22 Main body 23 Heat transfer tube

Claims (4)

[Claims] 1. A steam generator for heating boiler feed water into steam by heating a combustion gas, a steam using unit connected to a steam feed side of the steam generating unit via a steam pipe, and a steam using unit. And a condenser for condensing used steam to make it condensed, and a condensate feed side of this condenser connected via a condensate line to degas condensate And an economizer connected in the middle of a boiler water supply pipe connecting the deaerator and the steam generating section and attached to an exhaust pipe, and the boiler on the steam generating section side of the economizer. A boiler facility, wherein a return pipe for returning a part of the boiler feed water after heat exchange to the deaerator is connected to the water supply pipe. 2. A steam generating section which is heated by a combustion gas to convert boiler feed water into steam, a steam using section connected to a steam feed side of the steam generating section via a steam pipe, and a steam using section. And a condenser for condensing used steam to make it condensed, and a condensate feed side of this condenser connected via a condensate line to degas condensate Boiler feed water supplied from the deaerator, comprising: a deaerator, and an economizer connected in the middle of a boiler water supply pipe connecting the deaerator and the steam generation section and attached to an exhaust pipe. A return pipe for returning a part of the boiler to the deaerator again is provided, and a feedwater heater for heating a part of the boiler feedwater provided in the exhaust pipe and connected in the middle of the return pipe is provided. Boiler equipment characterized by being provided. 3. The boiler equipment according to claim 2, wherein a plurality of feed water heaters are attached to the exhaust pipe. 4. A steam generating section for heating the boiler feed water into steam by the combustion gas, a steam using section connected to a steam feed side of the steam generating section via a steam pipe, and a steam using section. And a condenser for condensing used steam to make it condensed, and a condensate feed side of this condenser connected via a condensate line to degas condensate A return pipe is provided for returning a part of the boiler feedwater supplied from the deaerator to the deaerator again.The return pipe is connected in the middle of the return pipe and connected to the exhaust pipe. A feed water heater is provided for heating a part of the boiler feed water, and a boiler feed line is provided for supplying the remaining part of the boiler feed water supplied from the deaerator to the steam generator. ,
A branch steam line is provided for extracting a part of the steam used in the steam using section to the deaerator, and a boiler feed line is connected in the middle of the branch steam line to heat the boiler feed water. Boiler equipment provided with a preheater.