JPH05322105A - Device for heating feedwater for boiler - Google Patents

Abstract

PURPOSE:To raise the temperature of the feedwater at the outlet of a low- pressure feedwater heater at the start of the operation so as to reduce the difference from the temperature of the feedwater at the outlet of a deaerator. CONSTITUTION:A bypass 31 connecting a deaerator 5 and a low-pressure feedwater heater 4 is provided. At the start of the operation, the feedwater (condensate) heated at a deaerator 5 is in part passed through the bypass 31 and a pressure-regulating valve 33 and fed to the low-pressure feedwater heater 4 and, after heating the feedwater passing through this low-pressure feedwater heater 4, returned to a condenser 1 through a line 32. Instead of the feedwater in the deaerator, the steam or drain in a steam separator 10 can in part be fed to the low-pressure feedwater heater 4 at the start of the operation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a boiler feed water heating apparatus, and more particularly to a boiler feed water heating apparatus capable of reducing the feed water temperature difference between the inlet and outlet of a deaerator at startup.

[0002]

2. Description of the Related Art Conventionally, as a boiler feed water heating apparatus in a power generation plant for business use, there is one as shown in FIG. That is, a low-pressure feed water heater 4, a deaerator 5, and high-pressure feed water heaters 6, 7, and 8 are sequentially installed in the water supply system from the condenser 1 to the boiler economizer 2 and the water cooling wall 3 to extract the turbine 9 In the operating range in which can be used (during normal load operation), the low-pressure feed water heater 4 and the high-pressure feed water heaters 6, 7, and 8 also perform heat exchange between turbine extraction air and feed water (condensate) to improve plant efficiency. I am trying.

At the time of startup, the steam separator 10
The steam and the drain are used to heat the high-pressure feed water only, and the heat of the steam and the drain is exchanged with the feed water. After exchanging heat with the gas, it is led to the steam separator 10, and then the deaerator 5 and high-pressure feed water heater 6, 7, 8
Except for steam and drain used for heat exchange, the water is recovered in the condenser 1, heat is exchanged with seawater in the condenser 1, and again,
The cycle is such that the condensate pump 11, the condensate booter pump 12, and the low-pressure feed water heater 4 are passed to the deaerator 5, and the high-pressure feed water heaters 6, 7, and 8.

In FIG. 4, 13 is a primary superheater,
14 is a secondary superheater, 15 is a feed water pump, 16 is a deaerator recirculation pump, 17 is a high pressure feed water heater heating steam valve, 18 is a deaerator heating drain valve, 19 is a deaerator heating steam valve, 20 Is a steam / water separator pressure adjusting valve, 21 is a steam / water separator level adjusting valve, 22 is a condensate recirculation valve, and 23 is a deaerator water level adjusting valve.

[0005]

By the way, in the above-mentioned prior art, there is no heat source for heating the feed water passing through the low-pressure feed water heater 4 up to the operating region where heat exchange with the extraction air of the turbine 9 is possible. Therefore, the temperature difference between the feed water in the deaerator 5 heated by the steam and drain of the steam separator 10 and the feed water at the outlet of the low-pressure feed water heater 4, that is, the difference in the feed water temperature at the deaerator inlet / outlet tends to be too large. There is.

Therefore, conventionally, in order to reduce the difference in the feed water temperature at the inlet / outlet of the deaerator, a part of the feed water at the outlet of the deaerator 5 is sent to the outlet side of the low pressure feed water heater 4 by the deaerator recirculation pump 16. It is circulated so that the difference in feed water temperature between the inlet and outlet of the deaerator is reduced.

However, in such a procedure, the heat of the fluid heated through the boiler main body (coal saver 2, water cooling wall 3) only heats the deaerator 5 and the high pressure feed water heaters 6, 7, 8. However, there is a problem that the efficiency is poor when viewed from the whole plant.

The present invention has been made in order to solve the problems of the prior art, and at the time of start-up, the temperature of the low-pressure feed water heater outlet feed water is controlled by utilizing the heat source from the deaerator or the steam separator. The purpose of the present invention is to provide a boiler feedwater heating device that reduces the feedwater temperature difference between the inlet and outlet of the deaerator, reduces the power for recirculating the deaerator, and improves the efficiency at plant startup. And

[0009]

In order to solve the above problems, the present invention provides a low pressure feed water heater, a deaerator and a high pressure feed water heater sequentially in a water supply system from a condenser to a boiler, In the deaerator, in the boiler feed water heating device in which the feed water is heated by the steam and drain from the steam separator, a part of the feed water heated by the deaerator at startup or the steam of the steam separator Alternatively, a bypass line for supplying a part of the drain to the low-pressure feed water heater is provided.

[0010]

According to the above means, at startup, a part of the feed water heated by the deaerator, or a part of the steam or drain of the steam separator is supplied to the low pressure feed water heater through the bypass line, The feed water passing through the low-pressure feed water heater is heated, whereby the low-pressure feed water heater outlet feed water temperature rises, and the difference from the deaerator outlet feed water temperature decreases.

[0011]

Embodiments of the present invention will be described in detail below with reference to FIGS. In addition, in FIGS.
The same parts as those shown in FIG. 4 are designated by the same reference numerals, and the duplicated description will be omitted.

FIG. 1 shows a first embodiment of the present invention. According to this embodiment, the bypass line 31 connecting the deaerator 5 and the low-pressure feed water heater 4 is provided, and the deaerator 5 is activated at the time of starting.
A part of the feed water heated in the above is supplied to the low pressure feed water heater 4 through the bypass line 31.
After heating the feed water passing through, it is returned to the condenser 1 through the line 32. Therefore, the outlet feed water temperature of the low-pressure feed water heater 4 rises and the difference from the outlet feed water temperature of the deaerator 5 becomes small. Therefore, a part of the deaerator outlet feed water is supplied by the deaerator recirculation pump 16 to the low-pressure feed water. It is not necessary to circulate to the outlet side of the heater 4.

The bypass line 31 is provided with a low pressure feed water heater pressure adjusting valve 33 to adjust the feed water pressure when the feed water of the deaerator 5 enters the low pressure feed water heater 4. ..

Next, FIG. 2 shows a second embodiment of the present invention.
According to the present embodiment, a bypass line 41 is provided that connects the middle portion of the line 40 that supplies the steam of the steam separator 10 to the deaerator 5 and the low-pressure feed water heater 4, and at the time of startup,
A part of the steam supplied from the steam separator 10 to the deaerator 5 is supplied to the low pressure feed water heater 4 through the bypass line 41, and after heating the feed water passing through the low pressure feed water heater 4, the line 42 It is designed to be returned to the condenser 1 through. Therefore, like the first embodiment described above,
Since the outlet feed water temperature of the low-pressure feed water heater 4 rises and the difference from the outlet feed water temperature of the deaerator 5 becomes small, a part of the deaerator outlet feed water is supplied to the low-pressure feed water heater by the deaerator recirculation pump 16. No need to circulate to the outlet side of No. 4.

The bypass line 41 is provided with a low pressure feed water heater pressure adjusting valve 43, and the steam separator 1 is provided.
The steam pressure when 0 steam enters the low pressure feed water heater 4 is adjusted.

Next, FIG. 3 shows a third embodiment of the present invention.
According to this embodiment, the drain of the steam separator 10 is connected to the condenser 1
A bypass line 51 is provided that connects the middle part of the line 50 for returning to the low pressure feed water heater 4 and at the time of startup, part of the drain returned from the steam separator 10 to the condenser 1 is the bypass line 51. Is supplied to the low-pressure feed water heater 4 through the line, the feed water passing through the low-pressure feed water heater 4 is heated, and then returned to the condenser 1 through the line 52. Therefore, as in the first and second embodiments described above, the outlet feed water temperature of the low-pressure feed water heater 4 rises and the difference from the outlet feed water temperature of the deaerator 5 becomes small, so that the deaerator outlet feed water It is not necessary to circulate a part of the deaerator recirculation pump 16 to the outlet side of the low-pressure feed water heater 4.

The bypass line 51 is provided with a low-pressure feed water heater pressure adjusting valve 53, and the steam separator 1 is provided.
The drain pressure when the drain of 0 enters the low-pressure feed water heater 4 is adjusted.

[0018]

As described above, according to the present invention, in the boiler feed water heating apparatus, at startup, a part of the feed water heated by the deaerator, or a part of the steam or drain of the steam separator. Is supplied to the low-pressure feed water heater through the bypass line to heat the feed water passing through the low-pressure feed water heater, thereby raising the low-pressure feed water heater outlet feed water temperature and reducing the difference from the deaerator outlet feed water temperature. Therefore, it is not necessary to circulate a part of the deaerator outlet feed water to the outlet side of the low-pressure feed water heater by the deaerator recirculation pump, reducing the deaerator recirculation power and starting the plant. There is an effect that the efficiency of can be improved.

[Brief description of drawings]

FIG. 1 is a system diagram of a boiler feedwater heating apparatus according to an embodiment of the present invention when a power generation plant is activated.

FIG. 2 is a system diagram showing another embodiment of the boiler feedwater heating apparatus according to the present invention when the power plant is started.

FIG. 3 is a system diagram when a power plant is started, showing still another embodiment of the boiler feed water heating apparatus according to the present invention.

FIG. 4 is a system diagram showing a conventional boiler feedwater heating device when a power generation plant is started.

[Explanation of symbols]

 1 Condenser 2 Boiler economizer 3 Boiler water cooling wall 4 Low-pressure feed water heater 5 Deaerator 6, 7, 8 High-pressure feed water heater 10 Steam-water separator 31, 41, 51 Bypass line

Claims (1)

[Claims] 1. A low-pressure feed water heater, a deaerator, and a high-pressure feed water heater are sequentially installed in a water supply system from a condenser to a boiler, and in the deaerator, the feed water is heated by steam and a drain from a steam separator. In the boiler feed water heating device configured to do, a bypass line for supplying a part of the feed water heated by the deaerator at startup, or a part of the steam or drain of the steam separator to the low pressure feed water heater. A boiler feed water heating device characterized by being provided.