JPH07167401A - Double pressure type waste heat recovery boiler water supplying apparatus - Google Patents

Abstract

PURPOSE:To prevent deterioration of a high-pressure water supply pump by reducing a change width of a high-pressure water supply pump inlet supply water temperature as much as possible. CONSTITUTION:A double pressure type waste heat recovery boiler water supplying apparatus comprises a high-pressure drum 16 and a low-pressure drum 17 respectively coupled to a high-pressure vaporizer 12 and a low-pressure vaporizer 14, and a high-pressure economizer 18 and a low-pressure economizer 15 for supplying water to the drums 16 and 17, wherein a high-pressure water supply tube 34 is branched from a low-pressure water supply tube 32 of an upstream side of the economizer 15, and water is fed to the economizer 18 through a high-pressure water supply pump 33 connected to the tube 34.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-pressure type exhaust heat recovery boiler water supply apparatus for suppressing the variation range of the inlet temperature of a high pressure water supply pump for supplying water to a high pressure economizer of an exhaust heat recovery boiler.

[0002]

2. Description of the Related Art FIG. 4 is a system diagram of a conventional double pressure type exhaust heat recovery boiler water supply system. As shown in FIG. 4, a high pressure steam superheater 11 and a high pressure evaporator 1 are provided in the double pressure type exhaust heat recovery boiler 1.
2, the high-pressure economizer 13, the low-pressure evaporator 14, and the low-pressure economizer 15 are arranged toward the downstream side of the exhaust gas.

The high pressure evaporator 12 is a high pressure drum 16
The low-pressure evaporator 14 is connected to the low-pressure drum 17, and the low-pressure water supplied to the low-pressure water supply pump 31 is
After the temperature is raised in the low pressure economizer 15 via the low pressure water supply pipe 32,
Water is sent to the low-pressure drum 17 via the low-pressure water supply pipe 32, and is further guided to the low-pressure side of the steam turbine 23 via the low-pressure main steam pipe 22.

On the other hand, the high-pressure feed water passes through the high-pressure feed pipe 34 branched at the outlet of the low-pressure economizer 15, and the high-pressure feed pump 33,
Water is sent to the high-pressure drum 16 via the high-pressure coal economizer 13, further vaporized in the high-pressure evaporator 12, and then superheated in the high-pressure steam superheater 11 to generate high pressure in the steam turbine 23 via the high-pressure main steam pipe 21. Supplied to the side.

The main steam supplied to the steam turbine 23 drives the generator 24 by rotating the steam turbine 23, and then is guided to the condenser 25 to be condensed and liquefied.

Further, in order to prevent low temperature corrosion in the low pressure economizer 15, a part of the high pressure feed water passes through a feed water recirculation pipe 35 branched at the outlet of the high pressure feed pump 33, and a feed water recirculation water control which is a temperature control valve. Recirculate to the cold water supply pipe 32 via valve 36. At this time, the opening degree of the feed water recirculation water control valve 36 is adjusted based on the temperature controller 37 to keep the temperature of the feed water at the inlet of the low pressure economizer 15 constant.

[0007]

By the way, according to the above-mentioned conventional example, since the high pressure feed water is taken out from the outlet of the low pressure economizer 15, the feed water passing through the high pressure feed water pump 33 is not supplied when the exhaust heat recovery boiler 1 is started. Temperature rise in a short time (about 100 ℃
/ Min)

Therefore, the high-pressure water supply pump 33 receives an excessive thermal shock, is damaged by the contact between the stationary part and the rotating part of the high-pressure water supply pump 33, and the pump components are deteriorated at an early stage. There is a problem that the reliability is significantly lowered.

The present invention has been made in consideration of the above-mentioned circumstances, and the double pressure type exhaust heat recovery capable of preventing deterioration of the high-pressure water supply pump by minimizing the change width of the inlet water temperature of the high-pressure water supply pump. It is intended to provide a boiler water supply device.

[0010]

In order to solve the above-mentioned problems, the first aspect of the present invention is to connect a high-pressure evaporator and a low-pressure evaporator to a high-pressure drum and a low-pressure drum, respectively.
In a compound pressure heat recovery steam boiler water supply device that supplies water to these drums through a high-pressure economizer and a low-pressure economizer, respectively, a high-pressure water pipe is branched from a low-pressure water pipe upstream of the low-pressure economizer. It is characterized in that water is supplied to the high-pressure coal economizer via a high-pressure water supply pump connected to the high-pressure water supply pipe.

According to a second aspect of the present invention, a branch pipe is provided at an optimum temperature position at the outlet of the high pressure economizer according to the first aspect, and a high pressure water supply pipe is provided through the branch pipe to a low pressure water supply pipe upstream of the high pressure water supply pipe branch point. It is characterized in that a part of is recycled.

According to a third aspect of the present invention, a branch pipe is provided at the outlet of the low pressure economizer according to the first aspect, and a low pressure water supply upstream of the branch point of the high pressure water supply pipe is provided via a water supply recirculation pump connected to the branch pipe. It is characterized in that a part of the low-pressure feed water is recirculated to the pipe.

According to a fourth aspect of the present invention, the amount of high-pressure feed water and the amount of low-pressure feed water are adjusted in the recirculation pipe line according to the second or third aspect to keep the feed water temperature at the inlet of the high-pressure economizer and the low-pressure economizer constant. It is characterized in that means for controlling is provided.

According to a fifth aspect of the present invention, in the high-pressure water feed pump according to the first aspect, the minimum flow pipes are branched from the high pressure economizer inlet and outlet, respectively, to provide stop valves, and these stop valves are set to the operating state of the unit. It is characterized in that it is switched depending on the situation.

In claim 6, claim 1, 2, 4 or 5
The described high-pressure economizer includes a high-pressure primary economizer and a high-pressure secondary economizer, and the steam high-pressure primary economizer is arranged in parallel with the low-pressure economizer with respect to the exhaust gas.

According to the present invention, a high pressure evaporator and a low pressure evaporator are connected to a high pressure drum and a low pressure drum, respectively, and a double pressure type discharge for supplying water to these drums via the high pressure economizer and the low pressure economizer, respectively. In the heat recovery boiler water supply device, on the upstream side of the high pressure economizer and the low pressure economizer,
In addition, a water supply pump is installed in the condensate pipe on the downstream side of the condensate pump,
The discharge water of the water supply pump is sent to the high-pressure drum through the high-pressure economizer, while the extracted water in the intermediate stage of the water supply pump is sent to the low-pressure drum through the low-pressure economizer.

According to the present invention, a branch pipe is provided at the optimum temperature location at the outlet of the low-pressure economizer according to claim 7, and a part of the low-pressure feed water is fed to the condensate pipe upstream of the water feed pump via this branch pipe. It is characterized by being recycled.

According to a ninth aspect of the present invention, the recirculation pipe line according to the seventh or eighth aspect is provided with means for adjusting the amount of recirculated water to control the feed water temperature at the feed water pump inlet at a constant level. And

In a tenth aspect, the high-pressure economizer according to claim 7, 8 or 9 comprises a high-pressure primary economizer and a high-pressure secondary economizer, and the high-pressure primary economizer is a low-pressure economizer for exhaust gas. It is characterized by being placed in parallel with the charcoal ware.

[0020]

In the first aspect of the present invention having the above-mentioned structure, the high pressure water supply pipe is branched from the low pressure water supply pipe on the upstream side of the low pressure economizer, and the high pressure water supply pump is connected to the high pressure water supply pipe. By supplying water to the economizer, it is possible to prevent deterioration of the high-pressure water supply pump without giving an excessive thermal shock to the high-pressure water supply pump.

In the second aspect, a branch pipe is provided at the optimum temperature location at the outlet of the high-pressure economizer, and a part of the high-pressure feed water is recycled to the low-pressure feed pipe upstream of the branch point of the high-pressure water feed pipe through this branch pipe. By circulating, it is possible to prevent low temperature corrosion in the low pressure economizer and the high pressure economizer.

In the third aspect, a branch pipe is provided at the outlet of the low-pressure economizer, and the low-pressure feed water is supplied to the low-pressure feed pipe upstream of the branch point of the high-pressure feed pipe via the feed water recirculation pump connected to the branch pipe. By recirculating a part, low temperature corrosion in a low pressure economizer and a high pressure economizer can be prevented.

In claim 4, the recirculation pipe is provided with means for adjusting the amounts of the high-pressure feed water and the low-pressure feed water to control the feed water temperature at the inlets of the high-pressure economizer and the low-pressure economizer at a constant level. As a result, the inlet feed water temperature of the low-pressure economizer and the high-pressure economizer is always kept constant.

According to a fifth aspect of the present invention, in the high-pressure feed pump, the minimum flow pipe is branched from the inlet and the outlet of the high-pressure economizer to provide stop valves, and these stop valves are switched according to the operating state of the unit. A smooth start-up can be realized during warm-up start-up.

In claim 6, the high-pressure economizer comprises a high-pressure primary economizer and a high-pressure secondary economizer, and the high-pressure primary economizer is arranged in parallel with the low-pressure economizer with respect to the exhaust gas.
The heat collection efficiency in the high-pressure primary economizer and the low-pressure economizer can be increased.

According to a seventh aspect of the present invention, a water supply pump is provided in the condensate pipe upstream of the high pressure economizer and the low pressure economizer and downstream of the condensate pump, and the discharge water of the water supply pump is supplied to the high pressure economizer. Water is sent to the high-pressure drum through the low-pressure economizer while water is being sent to the low-pressure drum through the low-pressure economizer, while preventing the water-supply pump from deteriorating without giving an excessive thermal shock. it can.

In claim 8, a branch pipe is provided at an optimum temperature location at the outlet of the low-pressure economizer, and a part of the low-pressure feed water is recirculated to the condensate pipe on the upstream side of the water feed pump through the branch pipe. Thereby, low temperature corrosion in the low pressure economizer and the high pressure economizer can be prevented.

In the ninth aspect of the present invention, the recirculation pipe is provided with means for adjusting the amount of recirculated water to control the feed water temperature at the inlet of the feed water pump at a constant level. The inlet water temperature of the coal heater is always kept constant.

In the tenth aspect, the high-pressure economizer includes a high-pressure primary economizer and a high-pressure secondary economizer, and the high-pressure primary economizer is arranged in parallel with the low-pressure economizer with respect to exhaust gas. The heat collection efficiency in the high-pressure primary economizer and the low-pressure economizer can be increased.

[0030]

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

FIG. 1 is a system diagram showing a first embodiment of a compound pressure type exhaust heat recovery boiler water supply system according to the present invention. Note that the same or corresponding portions as those of the conventional configuration will be described using the same reference numerals. In FIG. 1, a high pressure steam superheater 11, a high pressure evaporator 12, a high pressure secondary economizer 13a, a low pressure evaporator 14, a low pressure economizer 15, and a high pressure primary economizer 18 are provided in the double pressure type exhaust heat recovery boiler 1. Are arranged toward the downstream side of the exhaust gas.

The high-pressure evaporator 12 is a high-pressure drum 16
The low-pressure evaporator 14 is connected to the low-pressure drum 17, and the low-pressure water supplied to the low-pressure water supply pump 31 is
After being heated in the low-pressure economizer 15 via the low-pressure feed pump outlet check valve 42 and the low-pressure feed pipe 32, the low-pressure steam generated in the low-pressure evaporator 14 is passed through the low-pressure drum 17 and the low-pressure main steam pipe 22.
To the low pressure side of the steam turbine 23.

On the other hand, the high-pressure feed water passes through a pipe branching from the low-pressure feed pipe 32 downstream of the low-pressure feed pump outlet check valve 42 and upstream of the low-pressure economizer 15, and the high-pressure feed pump 33.
And is guided from the high-pressure water supply pump 33 to the high-pressure primary economizer 18 through the high-pressure water supply pipe 34 connected to the high-pressure water supply flow meter 41.

Further, the feed water heated by the high pressure primary economizer 18 passes through the high pressure water supply pipe 34 and the high pressure secondary economizer 13
The temperature is further raised at a and is guided to the high-pressure drum 16. The feed water that is not vaporized from the high-pressure drum 16 is the high-pressure evaporator 1
It is guided to No. 2 where it is vaporized into high pressure steam. This high-pressure steam passes through the high-pressure drum 16 and the high-pressure steam superheater 11
Is sent to the high pressure side of the steam turbine 23 through the high pressure steam pipe 21.

The main steam supplied to the steam turbine 23 through the high pressure steam pipe 21 and the low pressure main steam pipe 22 is
The steam turbine 23 is rotationally driven to perform work, and a generator 24 connected to the steam turbine 23 is driven. The steam that has worked in the steam turbine 23 is guided to the condenser 25 where it is condensed and liquefied.

In order to prevent low-temperature corrosion in the low-pressure economizer 15 and the high-pressure primary economizer 18, high-pressure water is supplied from the high-pressure feed pipe 34 at a location where the optimum temperature on the downstream side of the high-pressure primary economizer 18 can be obtained. A part of the water supply is branched, and this water supply is circulated through the water supply recirculation pipe 35 to the low pressure water supply pipe 32 on the downstream side of the low pressure water supply pump outlet check valve 42 and on the upstream side of the branch point of the high pressure water supply pipe 34, Water recirculation water control valve 3 which is a temperature control valve whose opening is controlled based on the temperature controller 37
6, the inlet feed water temperature of the high-pressure primary economizer 18 and the low-pressure economizer 15 is adjusted so as to always maintain a constant temperature (about 50 ° C.).

Further, the water supply from the outlet of the high-pressure primary economizer 18 passes through a water supply recirculation pipe 35 branched from the high-pressure water supply pipe 34, a minimum flow pipe 38 which also serves as a minimum flow of the high-pressure water supply pump 33, and further, High pressure primary economizer outlet minimum flow stop valve 44, minimum flow control valve 3
By recovering the water to the condenser 25 after passing through 9, the amount of water supply can ensure the required amount of recirculation.

The high pressure water supply pipe 33 at the outlet of the high pressure water supply pump 33 and at the inlet of the high pressure primary coal economizer 18 is branched from a high pressure water supply pump minimum flow pipe 46. It is connected to the upstream side of the minimum flow control valve 39 via the flow stop valve 45.

Therefore, only when the unit is warmed up and started,
Close the high pressure primary economizer outlet minimum flow stop valve 44,
By opening the high-pressure primary economizer inlet minimum flow stop valve 45, the high-pressure primary economizer 18 is activated during warm-up startup.
The high-temperature water staying inside is not replaced with the cold water from the condenser 25, whereby smooth startup can be realized. The opening of the minimum flow control valve 39 is controlled by outputting the measurement result of the high pressure feed water flow meter 41 to the flow rate controller 40.

Next, the operation of this embodiment will be described.

The high pressure economizer is divided into a high pressure primary economizer 18 and a high pressure secondary economizer 13a. By disposing the high pressure primary economizer 18 in parallel with the low pressure economizer 15 with respect to the exhaust gas. The heat collection efficiency in the high pressure primary economizer 18 and the low pressure economizer 15 can be increased, and the optimum temperature of the feed water recirculation water can be selected.

By the way, since the amount of water supplied through the high-pressure primary economizer 18 greatly changes depending on the required recirculation amount,
When the recirculation amount is small, the heat recovery rate in the high-pressure primary economizer 18 decreases, and the exhaust gas temperature on the downstream side rises.
It is necessary to set the design temperature of the flue, chimney, etc. located on the downstream side to a high temperature, and the high temperature gas is released into the atmosphere, which causes an adverse effect on the environment.

Therefore, in this embodiment, the high pressure primary economizer 18 is used.
In order to secure the minimum amount of water passing through the high-pressure primary coal economizer 18, the high-pressure primary coal economizer 18 has a high-pressure water supply pipe 34, a water supply recirculation pipe 35, a minimum flow pipe 38, a high-pressure primary economizer outlet minimum flow stop valve 44. , And minimum flow control valve 3
By recovering the water to the condenser 25 after passing through 9, the amount of water supply can ensure the required amount of recirculation.

Further, by closing the high pressure primary economizer outlet minimum flow stop valve 44 and opening the high pressure primary economizer inlet minimum flow stop valve 45 only when the unit is warmed up, the high pressure primary coalescer is opened at warm air startup. A smooth start-up can be realized without replacing the high temperature water staying in the charcoal unit 18 with the cold water from the condenser 25.

Then, in an operating state other than the warm-up start-up,
The same effect can be obtained by always closing the high pressure primary coal economizer inlet minimum flow stop valve 45 and keeping the high pressure primary coal economizer outlet minimum flow stop valve 44 open.

As described above, according to this embodiment, the temperature of the feed water flowing into the high pressure feed pump 33 is always a constant temperature (about 5).
(0 ° C.) and the temperature rise rate can be controlled by adjusting the opening of the feed water recirculation water control valve 36, which is a temperature control valve even at the time of startup, so the high pressure feed pump 33
It is possible to provide a highly reliable double pressure type exhaust heat recovery boiler water supply device without giving an excessive thermal shock to the.

FIG. 2 is a system diagram showing a second embodiment of the compound pressure type exhaust heat recovery boiler water supply system according to the present invention. The same parts as those of the first embodiment described above will be designated by the same reference numerals. The same applies to each of the following examples.

The low-pressure feed water whose pressure has been raised by the low-pressure feed pump 31 is sent to the low-pressure drum 17 via the low-pressure feed pump outlet check valve 42, the low-pressure feed water flow meter 41 and the low-pressure economizer 15.

On the other hand, the high-pressure feed water is branched from the low-pressure feed pipe 32 on the downstream side of the low-pressure feed pump outlet check valve 42 and on the upstream side of the low-pressure economizer 15, and the high-pressure feed pump 33 and the high-pressure primary economizer 18 are connected. Through the high pressure water supply pipe 34, and further to the high pressure drum 16 via the high pressure secondary economizer 13a.

In order to prevent low temperature corrosion in the low pressure economizer 15 and the high pressure primary economizer 18, a part of the low pressure feed water is branched from the low pressure feed pipe 32 on the downstream side of the low pressure economizer 15, By circulating through the water supply recirculation pipe 35 to which the water supply recirculation pump 43 is connected, to the low pressure water supply pipe 32 on the downstream side of the low pressure water supply pump outlet check valve 42 and on the upstream side of the branch point with the high pressure water supply pipe 34, The feed water recirculation water control valve 36 adjusts the inlet feed water temperature of the high pressure primary economizer 18 and the low pressure economizer 15 so as to always maintain a constant temperature (about 50 ° C.).

Further, in order to prevent the exhaust gas temperature at the outlet of the exhaust heat recovery boiler 1 from rising, a minimum flow pipe 38 is branched from the feed water recirculation pipe 35 at the outlet of the feed water recirculation pump 43, and a minimum flow control valve 39 is provided. By connecting the condenser 25 with the condenser 25, the required minimum flow rate of the low pressure economizer 15 and the minimum flow of the feed water recirculation pump 43 can be secured.

In this embodiment, as in the above embodiment,
The high-pressure primary economizer 18 is arranged in parallel with the low-pressure economizer 15 for the exhaust gas. The other structure and operation are the same as those of the above-mentioned embodiment, and the explanation thereof is omitted.

FIG. 3 is a system diagram showing a third embodiment of the compound pressure type exhaust heat recovery boiler water supply system according to the present invention. In the present embodiment, a water supply pump 52 is provided in the condensate pipe 51 upstream of the high pressure primary economizer 18 and the low pressure economizer 15, and downstream of the condensate pump 50.

The discharge water of the water supply pump 52 is sent to the high pressure drum 16 through the high pressure water supply pipe 34, the high pressure primary economizer 18, the high pressure water supply pipe 34, and the high pressure secondary economizer 13a, while the intermediate stage of the water supply pump 52. The low pressure water supply pipe 3
2. Water is supplied to the low-pressure drum 17 through the low-pressure economizer 15 and the low-pressure water supply pipe 32.

That is, the condensate water whose pressure has been increased by the condensate pump 50 is sent to the water supply pump 52 via the condensate check valve 53 and the condensate pipe 51, and after being further pressurized, the water supply pump 52.
From the discharge side of the high-pressure feed pipe 34 to the high-pressure primary economizer 18
Be guided to.

Further, the feed water heated by the high pressure primary economizer 18 passes through the high pressure water supply pipe 34 and the high pressure secondary economizer 13
The temperature is further raised at a and is guided to the high-pressure drum 16. The feed water that is not vaporized from the high-pressure drum 16 is the high-pressure evaporator 1
It is guided to No. 2 where it is vaporized into high pressure steam. This high-pressure steam passes through the high-pressure drum 16 and the high-pressure steam superheater 11
Is sent to the high pressure side of the steam turbine 23 through the high pressure steam pipe 21.

On the other hand, the low-pressure feed water extracted from the intermediate stage of the feed water pump 52 passes through the low-pressure feed pipe 32 and the low-pressure economizer 15
After the temperature is raised by, it is guided to the low-pressure drum 17. The low-pressure steam generated in the low-pressure evaporator 14 connected to the low-pressure drum 17 is supplied from the low-pressure main steam pipe 22 to the low-pressure side of the steam turbine 23.

The main steam supplied to the steam turbine 23 through the high pressure steam pipe 21 and the low pressure main steam pipe 22 is
As in the case of the first embodiment, the steam turbine 23 is driven to rotate to perform work, and the generator 2 connected to the steam turbine 23.
4 is driven. The steam that has worked in the steam turbine 23 is guided to the condenser 25 where it is condensed and liquefied.

In order to prevent low temperature corrosion in the low pressure economizer 15 and the high pressure primary economizer 18, a part of the low pressure feed water is branched from the low pressure feed pipe 32 on the downstream side of the low pressure economizer 15, This feed water is circulated through the feed water recirculation pipe 35 to the condensate pipe 51 on the downstream side of the condensate check valve 53, and the feed water recirculation water control valve which is a temperature control valve whose opening is controlled based on the temperature controller 37. The inlet water temperature of the high-pressure primary economizer 18 and the low-pressure economizer 15 is adjusted by 36 so as to always maintain a constant temperature (about 50 ° C.).

Next, the operation of this embodiment will be described.

The high pressure economizer is divided into a high pressure primary economizer 18 and a high pressure secondary economizer 13a. By disposing the high pressure primary economizer 18 in parallel with the low pressure economizer 15 with respect to the exhaust gas. The heat collection efficiency in the high pressure primary economizer 18 and the low pressure economizer 15 can be increased.

Further, according to this embodiment, the water supply pump 52
The temperature of the feed water flowing into is constantly maintained at a constant temperature (about 50 ° C.), and the rate of temperature rise is controlled by adjusting the opening degree of the feed water recirculation water control valve 36, which is a temperature control valve even at the time of startup. Since it can be controlled, it is possible to provide a highly reliable double pressure type exhaust heat recovery boiler water supply apparatus without giving an excessive thermal shock to the water supply pump 52.

[0063]

As described above, according to the first aspect of the present invention.
According to the above, the high-pressure water supply pipe is branched from the low-pressure water supply pipe on the upstream side of the low-pressure economizer, and the high-pressure water pump is connected to the high-pressure water pipe to supply water to the high-pressure economizer, thereby It is possible to prevent deterioration of the high-pressure water supply pump without giving an excessive thermal shock, and to greatly improve the reliability of the device.

According to the second aspect, a branch pipe is provided at the optimum temperature location at the outlet of the high-pressure economizer, and a part of the high-pressure feed water is supplied to the low-pressure feed pipe upstream of the branch point of the high-pressure water feed pipe through this branch pipe. By recirculating, it is possible to prevent low-temperature corrosion in the low-pressure economizer and the high-pressure economizer, and to extend the service life.

According to the third aspect, a branch pipe is provided at the outlet of the low-pressure economizer, and a low pressure is supplied to the low-pressure feed pipe upstream of the branch point of the high-pressure feed pipe via the feed water recirculation pump connected to this branch pipe. By recirculating a part of the feed water, it is possible to prevent low temperature corrosion in the low pressure economizer and the high pressure economizer, and it is possible to extend the service life.

According to the fourth aspect, the recirculation pipe is provided with means for adjusting the amounts of the high pressure feed water and the low pressure feed water to control the feed water temperatures at the high pressure economizer and the low pressure economizer inlet to be constant. As a result, the inlet feed water temperature of the low-pressure economizer and the high-pressure economizer is always kept constant.

According to the fifth aspect of the present invention, in the high-pressure feed pump, the minimum flow pipes are branched from the inlet and the outlet of the high-pressure economizer to provide stop valves, and these stop valves are switched according to the operating state of the unit. As a result, a smooth start-up can be realized during warm-up start-up.

According to claim 6, the high pressure economizer comprises a high pressure primary economizer and a high pressure secondary economizer, and the steam high pressure primary economizer is arranged in parallel with the low pressure economizer with respect to the exhaust gas. As a result, the heat collection efficiency in the high-pressure primary economizer and the low-pressure economizer can be increased.

According to the seventh aspect, by disposing the water supply pump on the upstream side of the high pressure economizer and the low pressure economizer, it is possible to prevent the deterioration of the water supply pump and to greatly improve the reliability of the apparatus. In addition to being able to improve, it is possible to provide water supply having an optimum pressure for water supply recirculation by extracting low-pressure water supply from the intermediate stage of the water supply pump.

According to claim 8, a branch pipe is provided at the optimum temperature location at the outlet of the low pressure economizer, and a part of the low pressure feed water is recirculated to the condensate pipe on the upstream side of the water feed pump through this branch pipe. As a result, it is possible to prevent low-temperature corrosion in the low-pressure economizer and the high-pressure economizer, and to extend the service life.

According to the ninth aspect of the present invention, the recirculation pipe is provided with means for adjusting the amount of recirculated water to control the feed water temperature at the inlet of the feed water pump at a constant level. No more thermal shock.

According to claim 10, the high-pressure economizer comprises a high-pressure primary economizer and a high-pressure secondary economizer, and the high-pressure primary economizer is arranged in parallel with the low-pressure economizer with respect to exhaust gas. As a result, the heat collection efficiency in the high-pressure primary economizer and the low-pressure economizer can be increased.

[Brief description of drawings]

FIG. 1 is a system diagram showing a first embodiment of a compound pressure type exhaust heat recovery boiler water supply device according to the present invention.

FIG. 2 is a system diagram showing a second embodiment of the compound pressure type exhaust heat recovery boiler water supply device according to the present invention.

FIG. 3 is a system diagram showing a third embodiment of a multi-pressure type exhaust heat recovery boiler water supply device according to the present invention.

FIG. 4 is a system diagram showing a conventional double pressure type exhaust heat recovery boiler water supply device.

[Explanation of symbols]

 1 Double Pressure Type Exhaust Heat Recovery Boiler 11 High Pressure Steam Superheater 12 High Pressure Evaporator 13a High Pressure Secondary Economizer 14 Low Pressure Evaporator 15 Low Pressure Economizer 16 High Pressure Drum 17 Low Pressure Drum 18 High Pressure Primary Economizer 31 Low Pressure Water Pump 32 Low Pressure Water Supply Pipe 33 High pressure water supply pump 34 High pressure water supply pipe 35 Water supply recirculation pipe 36 Water supply recirculation water control valve 37 Temperature controller 38 Minimum flow pipe 39 Minimum flow control valve 40 Flow controller 41 High pressure water supply flow meter 42 Low pressure water supply pump outlet check valve 43 Water supply recirculation pump 44 High pressure primary economizer outlet minimum flow stop valve 45 High pressure primary economizer inlet minimum flow stop valve 46 High pressure water supply pump minimum flow pipe 50 Condensate pump 51 Condensate pipe 52 Water supply pump 53 Condensate check valve

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Minoru Yamada 4-4, 2 Suehiro-cho, Tsurumi-ku, Yokohama-shi, Kanagawa Toshiba Keihin Office

Claims (10)

[Claims] 1. A double-pressure exhaust heat recovery boiler in which a high-pressure drum and a low-pressure evaporator are connected to a high-pressure drum and a low-pressure drum, respectively, and water is supplied to these drums via the high-pressure economizer and the low-pressure economizer, respectively. In the water supply device, a high-pressure water supply pipe is branched from a low-pressure water supply pipe on the upstream side of the low-pressure coal economizer, and water is supplied to the high-pressure economizer via a high-pressure water supply pump connected to the high-pressure water economizer. Compound pressure exhaust heat recovery boiler water supply device. 2. A branch pipe is provided at an optimum temperature location at the outlet of the high-pressure economizer, and a part of the high-pressure feed water is recirculated to the low-pressure feed pipe upstream of the branch point of the high-pressure water feed pipe through this branch pipe. The double pressure type exhaust heat recovery boiler water supply apparatus according to claim 1, wherein 3. A branch pipe is provided at the outlet of the low pressure economizer,
2. The multi-pressure exhaust heat according to claim 1, wherein a part of the low-pressure feed water is recirculated to the low-pressure feed pipe upstream of the branch point of the high-pressure feed pipe through the feed water recirculation pump connected to this branch pipe. Recovery boiler water supply device. 4. The recirculation pipe line is provided with means for adjusting the amounts of high-pressure feed water and low-pressure feed water to control the feed water temperature at the inlets of the high-pressure economizer and the low-pressure economizer at a constant level. The compound pressure exhaust heat recovery boiler water supply device according to claim 2 or 3. 5. The high-pressure feed pump is characterized in that minimum flow pipes are branched from an inlet and an outlet of the high-pressure economizer, respectively, to provide stop valves, and these stop valves are switched according to an operating state of the unit. The compound pressure exhaust heat recovery boiler water supply device according to claim 1. 6. The high-pressure economizer comprises a high-pressure primary economizer and a high-pressure secondary economizer, and the steam high-pressure primary economizer is arranged in parallel with the low-pressure economizer with respect to exhaust gas. The compound pressure type exhaust heat recovery boiler water supply device according to claim 1, 2, 4 or 5. 7. A high pressure evaporator and a low pressure evaporator are respectively connected to a high pressure drum and a low pressure drum, and a double pressure type exhaust heat recovery boiler for supplying water to these drums via the high pressure economizer and the low pressure economizer, respectively. In the water supply device, a water supply pump is provided in the condensate pipe on the upstream side of the high-pressure economizer and the low-pressure economizer and on the downstream side of the condensate pump, and the discharge water of the water supply pump is passed through the high-pressure economizer to the high-pressure drum. A double pressure exhaust heat recovery boiler water supply device, characterized in that, while water is being sent to the low pressure drum, the extracted water in the intermediate stage of the water supply pump is sent to the low pressure drum through the low pressure economizer. 8. A branch pipe is provided at an optimum temperature location at the outlet of the low-pressure economizer, and a part of the low-pressure feed water is recirculated to the condensate pipe on the upstream side of the feed pump via the branch pipe. The multi-pressure type exhaust heat recovery boiler water supply device according to claim 7. 9. The recirculation pipe line is provided with means for adjusting the amount of recirculation water to control the feed water temperature at the feed water pump inlet at a constant level. Pressure type exhaust heat recovery boiler water supply device. 10. The high-pressure economizer comprises a high-pressure primary economizer and a high-pressure secondary economizer, and the high-pressure primary economizer is arranged in parallel with the low-pressure economizer with respect to exhaust gas. The compound pressure type exhaust heat recovery boiler water supply device according to claim 7, 8 or 9.