JPH1114007A - Reheat steam temperature controller of boiler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a drop of the efficiency of a plant and to prevent the corrosion of an introducing pipe by arranging a heat exchanger that cools steam fed to a reheater by boiler feed water introducing a part of boiler feed water on the inlet side of the reheater. SOLUTION: In case holding reheated steam temperature on the outlet side of a reheater 4 at predetermined temperature is difficult by adjusting the openings of an RH gas damper and an SH gas damper in a boiler 1 with high rate of load fluctuation, the adjustment of the opening of a flow adjusting valve 26 is carried out along with the adjustment of the openings of both dampers. A part of boiler feed water pressurized by a boiler feed pump 20 is introduced from a reheated steam cooling piping 25 to a heat exchanger 27 and steam inside an introducing pipe 8 fed to the reheater 4 by the boiler feed water introduced to the heat exchanger 27 is cooled. Therefore, either of the quantity of the steam in the reheater 4 or the heat energy thrown away to salt water after driving turbines 12 and 13 by condenser 16 is not increased, the efficiency of the plant is not deteriorated and there is no worry of the corrosion of the introducing pipe 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reheat steam temperature control device for a boiler.

[0002]

2. Description of the Related Art Generally, as shown in FIG.
A reheater 4 and a superheater 5 are disposed on a rear heat transfer section 2 connected to a furnace 1a of the first embodiment with a partition wall 3 interposed therebetween. Is provided with an RH gas damper 6 and an SH gas damper 7 for adjusting the amount of combustion gas from the furnace 1a flowing to the reheater 4 and the superheater 5.
By controlling the opening degree of the H gas damper 6 and the SH gas damper 7 to adjust the amount of combustion gas flowing through the reheater 4 and the superheater 5, the reheat steam temperature at the outlet side of the reheater 4 is controlled. It has become.

As shown in FIG. 4, the reheater 4 has an inlet header 4a to which steam as a fluid to be heated is supplied from an inlet pipe 8 connected to both ends, and one end connected to the inlet header 4a. A heat transfer section 4b including a number of heat transfer tubes disposed in the rear heat transfer section 2 of the boiler 1;
The outlet header 4c to which the other end of each heat transfer tube is connected and from which the reheated steam is led out from the outlet tube 9 connected to both ends
The upstream end of the introduction pipe 8 is connected to the high-pressure turbine 1 constituting the steam turbine 10.
1 and a downstream end of the outlet pipe 9 is connected to a steam inlet of a medium-pressure turbine 12 constituting a steam turbine 10, and the reheat steam heated by the reheater 4 causes the steam to flow out. The medium-pressure turbine 12 is driven, and the low-pressure turbine 13 is further driven. The steam outlet of the low-pressure turbine 13 is connected to a boiler water supply system 15 by a pipe 14.

[0004] The boiler water supply system 15 includes a condenser 16 for cooling and condensing steam discharged from the low-pressure turbine 13 with seawater or the like, a condensate pump 17 provided on an outlet side of the condenser 16, A low-pressure feedwater heater 18 for heating the boiler feedwater pressurized by the condensing pump 17; a deaerator 19 for degassing the boiler feedwater heated by the low-pressure feedwater heater 18; And a high-pressure feed water heater 21 for heating the boiler feed water pressurized by the boiler feed pump 20.

[0005] The high pressure feed water heater 21 of the boiler feed system 15 is connected to the economizer of the boiler 1 via a pipe 22, and the superheater 5 of the boiler 1 is connected via a pipe 23. The high pressure turbine 11 is connected to a steam inlet.

In FIG. 4, reference numeral 24 denotes a steam turbine generator connected to the steam turbine 10.

In a boiler 1 as shown in FIGS. 3 and 4, a combustion gas generated by burning fuel in a furnace 1a of the boiler 1 is guided from the furnace 1a to a rear heat transfer section 2 and is subjected to RH. The amount of combustion gas introduced into the reheater 4 and the amount of combustion gas introduced into the superheater 5 are adjusted by adjusting the opening of the gas damper 6 and the SH gas damper 7.

[0008] Here, the boiler 1
The boiler feedwater supplied to the economizer is heated by the combustion gas in the economizer and vaporized when passing through the economizer and passing through the furnace wall tube of the furnace 1a of the boiler 1. Is introduced into the superheater 5 and becomes superheated steam in the superheater 5. The superheated steam is introduced from the superheater 5 to the high-pressure turbine 11 of the steam turbine 10 via the pipe 23, and the high-pressure turbine 11 is driven. You.

The steam after driving the high-pressure turbine 11 is introduced into the reheater 4 through the introduction pipe 8, and the reheater 4
Is heated to form reheated steam, and the reheated steam is introduced into the intermediate pressure turbine 12 through the outlet pipe 9, the intermediate pressure turbine 12 is driven, and the steam after driving the intermediate pressure turbine 12 is It is led to the low pressure turbine 13 and the low pressure turbine 13 is driven.

The steam after driving the low-pressure turbine 13 is cooled and condensed with seawater or the like in a condenser 16 of a boiler water supply system 15 and is returned to the boiler feedwater. After being heated in the heater 18, it is degassed in the deaerator 19, and the boiler feedwater degassed in the deaerator 19 is supplied to a boiler feed pump 20.
The pressure is raised to the high pressure feed water heater 21, heated in the high pressure feed water heater 21, and supplied again to the economizer of the boiler 1.

In this way, the steam turbine 10 is driven by the steam, and power is generated by the steam turbine generator 24 connected to the steam turbine 10.

In the boiler 1 having a high load change rate, the reheat steam temperature at the outlet side of the reheater 4 can be adjusted to a predetermined value only by adjusting the opening of the RH gas damper 6 and the SH gas damper 7 as described above. Since it is difficult to maintain the temperature, recently, in combination with the opening degree adjustment of the RH gas damper 6 and the SH gas damper 7, as shown in FIG. As shown, a spray pipe 25 'for directly spraying a part of the boiler feedwater pressurized by the boiler feed pump 20 is connected, and the opening of a flow control valve 26' provided in the middle of the spray pipe 25 'is adjusted. By adjusting, the required amount of boiler feedwater is sprayed directly into the introduction pipe 8 as needed, and the steam supplied to the reheater 4 is cooled by the boiler feedwater.

[0013]

However, as described above, a part of the boiler feed water is directly sprayed into the inlet pipe 8 on the inlet side of the reheater 4 to cool the steam supplied to the reheater 4. In this case, the amount of steam in the reheater 4 increases, and after driving the medium pressure turbine 12 and the low pressure turbine 13, the condenser 1
6, the amount of heat discarded into the seawater increases, and the plant efficiency decreases. On the other hand, the inside of the introduction pipe 8 has a disadvantage that it is easily eroded by water droplets due to spraying.

In view of the above, the present invention can cool the steam supplied to the reheater without directly spraying a part of the boiler feedwater into the inlet pipe on the inlet side of the reheater, and can improve the plant efficiency. It is an object of the present invention to provide a reheat steam temperature control device for a boiler capable of preventing the reduction of the temperature and the erosion of the introduction pipe.

[0015]

According to a first aspect of the present invention, a part of a boiler feedwater pressurized by a boiler feedwater pump is introduced into an inlet of a reheater and supplied to the reheater by the boiler feedwater. The present invention relates to a reheat steam temperature control device for a boiler, wherein a heat exchanger capable of cooling steam is installed.

According to the second invention, a part of the boiler feed water pressurized by the condensing pump is introduced into the inlet of the reheater, and the steam supplied to the reheater can be cooled by the boiler feed water. The present invention relates to a reheat steam temperature control device for a boiler, in which a heat exchanger is installed.

According to the above means, the following effects can be obtained.

In the first invention, the reheat steam temperature at the outlet side of the reheater is maintained at a predetermined temperature only by adjusting the opening of the RH gas damper and the SH gas damper in the boiler having a high load change rate. When it is difficult to perform the heat exchange, when a part of the boiler feed water pressurized by the boiler feed pump is introduced into the heat exchanger in combination with the opening adjustment of the RH gas damper and the SH gas damper, The steam in the inlet pipe supplied to the reheater is cooled by the boiler feedwater introduced into the reheater, whereby the reheat steam temperature at the outlet side of the reheater is controlled to a required temperature. In this way, it is possible to cool the steam supplied to the reheater in a non-contact manner without directly spraying a part of the boiler feedwater into the introduction pipe on the inlet side of the reheater, and the amount of steam in the reheater Medium without increasing Without increasing the amount of heat will be discarded into the seawater in the condenser after driving the turbine and the low-pressure turbine, the plant efficiency is not reduced, eliminated worry about introducing tube is eroded by water droplets due to spraying.

In the second aspect of the present invention, in the boiler having a high load change rate, the reheat steam temperature on the outlet side of the reheater is adjusted to a predetermined temperature by merely adjusting the opening of the RH gas damper and the SH gas damper. When it is difficult to maintain the pressure in the boiler feed water, a part of the boiler feed water pressurized by the condensate pump is introduced into the heat exchanger in combination with the opening adjustment of the RH gas damper and the SH gas damper. The steam in the inlet pipe supplied to the reheater is cooled by the boiler feedwater introduced to the heat exchanger, whereby the reheat steam temperature at the outlet side of the reheater is controlled to a required temperature, and as a result, It is possible to cool the steam supplied to the reheater in a non-contact manner without directly spraying a part of the boiler feedwater into the inlet pipe on the inlet side of the reheater, as in the past. Medium pressure without increasing steam volume Without increasing the amount of heat will be discarded into the seawater in the condenser of the turbine and the low-pressure turbine after driving, the plant efficiency is not reduced, eliminated worry about introducing tube is eroded by water droplets due to spraying.

[0020]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an example of an embodiment of the present invention. In the figure, the parts denoted by the same reference numerals as those in FIGS. 3 and 4 represent the same parts, and the basic structure is shown in FIGS. This embodiment is similar to the conventional one shown in FIG. 4, but the feature of this embodiment is that, as shown in FIG. 1, the pressure is increased by the boiler feed pump 20 in the middle of the introduction pipe 8 on the inlet side of the reheater 4. A part of the boiler feedwater is introduced from a reheat steam cooling pipe 25 and a heat exchanger 27 capable of cooling steam supplied to the reheater 4 by the boiler feedwater is provided.

The boiler feed pump 20 is usually
Since a multistage pump is used, a part of the boiler feedwater is taken out from the middle stage to the reheat steam cooling pipe 25, while a flow control valve is provided in the middle of the reheat steam cooling pipe 25. The boiler feed water introduced from the reheat steam cooling pipe 25 to the heat exchanger 27 is returned to the inlet side of the boiler feed pump 20 via a return pipe 28.

Next, the operation of the illustrated example will be described.

In the boiler 1 having a high load change rate, FIG.
RH gas damper 6 and SH gas damper 7 as shown in FIG.
If it is difficult to maintain the reheat steam temperature at the outlet side of the reheater 4 at a predetermined temperature simply by adjusting the opening of the RH gas damper 6 and the SH gas damper 7, When the opening degree of the flow control valve 26 is adjusted in combination with the adjustment, a part of the boiler feed water pressurized by the boiler feed pump 20 is introduced from the reheat steam cooling pipe 25 to the heat exchanger 27, and The steam in the introduction pipe 8 supplied to the reheater 4 is cooled by the boiler feedwater introduced into the heat exchanger 27, whereby the reheat steam temperature at the outlet side of the reheater 4 is controlled to a required temperature. Is done. The boiler feed water introduced from the reheat steam cooling pipe 25 to the heat exchanger 27 is returned to the inlet side of the boiler feed pump 20 via a return pipe 28.

As a result, the steam supplied to the reheater 4 is cooled in a non-contact manner without directly spraying a part of the boiler feed water into the introduction pipe 8 on the inlet side of the reheater 4 as in the prior art. The amount of steam in the reheater 4 does not increase, and the amount of heat that is discarded into seawater in the condenser 16 after driving the medium-pressure turbine 12 and the low-pressure turbine 13 does not increase. Does not decrease and the introduction pipe 8
There is no need to worry about erosion due to water droplets caused by spraying.

In this way, the steam supplied to the reheater 4 can be cooled without directly spraying a part of the boiler feedwater into the introduction pipe 8 on the inlet side of the reheater 4, thereby lowering the plant efficiency and introducing the steam. Erosion of the tube 8 can be prevented.

FIG. 2 shows another embodiment of the present invention. In the drawing, the portions denoted by the same reference numerals as those in FIG. 1 represent the same components. A part of the feedwater is introduced from the reheat steam cooling pipe 25 to the heat exchanger 27 and returned to the inlet side of the condensate pump 17 via the return pipe 28.

In the example shown in FIG. 2, in the boiler 1 having a high load change rate, the RH gas damper 6 shown in FIG.
If it is difficult to maintain the reheat steam temperature at the outlet side of the reheater 4 at a predetermined temperature only by adjusting the opening degree of the SH gas damper 7 and the SH gas damper 7, When the opening degree of the flow control valve 26 is adjusted in combination with the opening degree adjustment, part of the boiler feedwater pressurized by the condensing pump 17 is transferred from the reheat steam cooling pipe 25 to the heat exchanger 27. The steam in the introduction pipe 8 supplied to the reheater 4 is cooled by the boiler feedwater introduced and introduced into the heat exchanger 27, whereby the reheat steam temperature at the outlet side of the reheater 4 is reduced. It is controlled to the required temperature. The boiler feed water introduced from the reheat steam cooling pipe 25 to the heat exchanger 27 is returned to the inlet side of the condensate pump 17 via the return pipe 28.

As a result, in the example shown in FIG.
As in the example shown in FIG. 1, the steam supplied to the reheater 4 is cooled in a non-contact manner without spraying a part of the boiler feedwater directly into the introduction pipe 8 on the inlet side of the reheater 4 as in the related art. The amount of steam in the reheater 4 does not increase, and the amount of heat that is discarded into seawater in the condenser 16 after driving the medium-pressure turbine 12 and the low-pressure turbine 13 does not increase.
The plant efficiency does not decrease, and there is no fear that the inside of the introduction pipe 8 is eroded by water droplets due to spraying.

In the example shown in FIG. 2, the temperature of the boiler feed water supplied from the condensate pump 17 is lower than the temperature of the boiler feed water supplied from the boiler feed pump 20. In some cases, the capacity of the heat exchanger 27 can be slightly reduced.

Thus, in the case of the example shown in FIG.
As in the case of the example shown in FIG. 1, the steam supplied to the reheater 4 can be cooled without directly spraying a part of the boiler feedwater into the introduction pipe 8 on the inlet side of the reheater 4, and the plant efficiency can be reduced. It is possible to prevent the lowering and erosion of the introduction tube 8.

The reheat steam temperature control apparatus for a boiler according to the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present invention. is there. Further, the reheat steam is cooled, that is, the side where the reheater outlet steam temperature is lowered is taken as an example. However, it is also possible to control the reheater outlet steam temperature to increase by reducing the cooling amount. Further, since the present invention is independent of gas, it can be used in combination with a boiler that controls the reheat steam temperature by increasing or decreasing the amount of recirculated gas in the boiler.

[0033]

As described above, according to the reheat steam temperature control apparatus for a boiler of the present invention, a portion of the boiler feedwater is reheated without directly spraying into the inlet pipe at the inlet of the reheater. The steam supplied to the vessel can be cooled, and an excellent effect of reducing the efficiency of the plant and preventing erosion of the inlet pipe can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an example of an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of another example of an embodiment of the present invention.

FIG. 3 is an overall schematic configuration diagram of a boiler.

FIG. 4 is a schematic configuration diagram of a conventional example.

[Explanation of symbols]

 Reference Signs List 1 boiler 4 reheater 8 introduction pipe 17 condensate pump 20 boiler feed pump

Claims (2)

[Claims] 1. A heat exchanger is provided on the inlet side of a reheater, in which a portion of boiler feedwater pressurized by a boiler feedwater pump is introduced and steam supplied to the reheater by the boiler feedwater can be cooled. A reheat steam temperature control device for a boiler, characterized in that: 2. A heat exchanger is provided on the inlet side of the reheater, in which a part of the boiler feedwater pressurized by the condensate pump is introduced and the steam supplied to the reheater by the boiler feedwater can be cooled. A reheat steam temperature control device for a boiler, characterized in that: