JPH06229503A - Waste heat recovery boiler device - Google Patents

Abstract

PURPOSE:To provide a waste heat recovery boiler with a feed water outlet distributing pipe wherein a steam-water mixed flow generated at an economizer outlet pipe at a low load of the boiler does not cause an unstable state in the control of water level and pressure of a drum so that a stable operation can be performed. CONSTITUTION:In a waste heat recovery boiler device, flow control valves 11, 12 are provided respectively in feed water pipe lines of the outlets of economizers 7, 4 and a feed water distributing pipe 22 wherein a horizontal cyclone 23 is coupled with a distribution tray 24 is provided in each of the feed water outlets for introducing steam-water mixed fluid into each steam drum 5, 8 through the flow control valve from the economizer. Consequently, steam flows out from the left and right of the outlet of the cyclone 23 into the steam drum and water falls down to the water surface of the drum through a large number of holes 26 in the bottom of the tray 24.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust heat recovery boiler apparatus which is one of the components of a combined cycle power plant, and is particularly operated in a state where steaming occurs inside the economizer or at the economizer outlet. The present invention relates to an exhaust heat recovery boiler device.

[0002]

2. Description of the Related Art A conventional technique for suppressing steaming in a economizer will be described with reference to FIG. Figure 5
It is a block diagram of the exhaust heat recovery boiler apparatus which provided the flow control valve in the exit of the coal-saving device disclosed by 3521 gazette. In the figure, an exhaust heat recovery boiler device is a high-pressure boiler system consisting of a high-pressure superheater 2, a high-pressure evaporator 3, a high-pressure economizer 4 and a high-pressure steam drum 5, which are sequentially provided in a flow path of a gas turbine exhaust gas 1, and a low-pressure boiler system. The low pressure boiler system is composed of an evaporator 6, a low pressure economizer 7, and a low pressure steam drum 8. The low pressure economizer 7 is provided with a water supply piping system 7A having a low pressure water supply pump 9.

Further, the high pressure economizer 4 is provided with a high pressure water supply piping system 4A having a high pressure water supply pump 10 branched from a pipe from the low pressure economizer 7 to the low pressure steam drum 8. A low-pressure feed water control valve 11 and a high-pressure feed water control valve 12 are provided in the pipe from the low-pressure economizer 7 to the low-pressure steam drum 8 and in the pipe from the high-pressure economizer 4 to the high-pressure steam drum 5, respectively. Since the pressure in the economizer can be maintained higher than the pressure in the steam drum by these water supply control valves, steaming in the economizer can be suppressed. A denitration device 13 is installed between the high pressure evaporator 3 and the high pressure economizer 4, where nitrogen oxides in the gas turbine exhaust gas are removed.

FIG. 6 is a sectional view of a conventionally known steam drum 14. As shown in the figure, can water 1 in the steam drum 14
5 flows into the evaporator through the downcomer 16 and immediately starts to evaporate, flows in a state where steam and water coexist, that is, in the state of a gas-water mixed fluid, and passes through the rising pipe 17 and the inner shell 18. Flow into the cyclone separator 19, where it is separated into water and steam, the steam is sent to the superheater through the steam pipe 20, and the water is sent into the canned water 15 in the steam drum 14.

On the other hand, the water supply from the economizer is distributed in the steam drum 14 from the steam drum water supply inlet through the water supply inner pipe 21 installed in the can water. When the low temperature water is concentratedly supplied to one place in the body of the steam drum 14, the temperature of the boiler water in the vicinity is lowered, and the expansion of the body and the pipe becomes uneven, causing distortion or water leakage. In order to prevent this, the water supply inner pipe 21 is used. As the water supply inner pipe 21, a long steel pipe provided with a large number of small holes is used, and the water supply is distributed over a wide range in the barrel of the steam drum 14 from these small holes.

[0006]

In such an exhaust heat recovery boiler apparatus, the temperature of the feed water passing through the economizer may become higher than the saturation temperature corresponding to the drum pressure when the boiler has a low load. When water is introduced into the steam drum 14 in such a case, steaming occurs, and there is a problem that the stability of the water level control of the steam drum 14 is impaired. Further, since the steam cooled by the low-temperature water in the steam drum 14 rapidly condenses to cause the water hammer phenomenon, there is a problem that stability of steam control and structural strength problems occur. Further, there is a problem that steam is mixed into the downcomer 16 and the water circulation characteristic of the evaporator is deteriorated, so that the boiler efficiency is reduced.

The present invention has been made in order to solve the above problems, and an object of the present invention is to control a drum water level control and a pressure control in which a steam-water mixed fluid generated in a coal economizer outlet pipe section when a boiler has a low load. Without causing instability,
An object is to provide an exhaust heat recovery boiler device having a water supply outlet distribution pipe that enables stable operation.

[0008]

In order to achieve the above object, an exhaust heat recovery boiler apparatus of the present invention comprises a economizer, a steam drum, and a water supply pipe for supplying water to the steam drum via the economizer. In a boiler device provided with a flow control valve in the water supply piping system at the outlet of the economizer, at the water supply outlet part for introducing a steam-water mixed fluid from the economizer into the steam drum via the flow control valve. The water supply outlet distribution pipe that combines a horizontal cyclone and a distribution tray is provided.

[0009]

[Operation] When steaming occurs at the outlet of the economizer during start-up or during low load operation such as partial load operation, steam is provided by installing a water supply outlet distribution pipe consisting of a horizontal cyclone and a distribution tray at the water supply outlet. The steam-water mixed fluid flowing into the drum is easily separated into steam and water in the horizontal cyclone portion of the water supply outlet distribution pipe. The steam flows into the steam drum from the left and right of the horizontal cyclone outlet, and the water drops toward the water surface of the drum through many holes at the bottom of the separation tray. The water supply is sufficiently distributed in the axial direction of the steam drum by the large number of holes, and the distance of the water supply drop is small, so that the water surface in the drum is not disturbed by the water supply drop. Thus, even if steaming occurs at the outlet of the economizer, since the water supply outlet in the steam drum is not installed in the can water, water hammer does not occur, and an unstable state of water level control does not occur.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings. FIG. 1 is a perspective view of a water supply outlet distribution pipe which is one of the constituent elements of the present invention. As shown in FIG. 1, the water supply outlet distribution pipe 22 is an integration of a horizontal cyclone 23 and a distribution tray 24. As shown in the figure, the horizontal cyclone 23 is installed in the water supply introduction pipe 25, and the distribution tray 24 is provided on the left and right of the horizontal cyclone 23. It is provided. The water supply introduction pipe 25 flowing into the drum is attached in a tangential direction of the horizontal cyclone 23. On the other hand, a large number of small holes 26 are provided at the bottom of the distribution tray 24.
Although the sectional shape of the distribution tray 24 is shown as a semicircle in the drawing, it is not limited to a semicircle, and may be a rectangle or a triangle.

FIG. 2 is a vertical sectional view of the steam drum portion of the exhaust heat recovery boiler apparatus having the water supply outlet distribution pipe of FIG. Since it is exactly the same whether it is applied to the high-pressure steam drum or the low-pressure evaporator, an example in which the feedwater outlet distribution pipe 22 is applied to the steam drum 14 is shown here for easy understanding.

In general, a water supply introducing pipe 25 from a water supply regulating valve is connected to the lateral portion of the body barrel, and the water supply is introduced into the steam drum 14 from the water supply introducing pipe 25, and a water supply outlet portion installed in the steam drum 14 is connected. It is led to the pipe 22. In addition to the water supply outlet distribution pipe 22 inside the steam drum 14, vapor is supplied from a downcomer pipe 16 for supplying water to the evaporator, an ascending pipe 17 into which a mixed fluid of steam and feed water evaporated in the evaporator flows, and the mixed fluid. A cyclone separator 19 for separating, a steam pipe 20 for sending the steam separated by the cyclone separator 19 to a superheater, etc. are installed.

FIG. 3 is a horizontal sectional view of the steam drum having the water supply outlet distribution pipe of FIG. As shown in the figure, the water supply is performed by a water supply introduction pipe 25 provided in the lateral portion of the steam drum 14.
From the water supply outlet distribution pipe 22. The water supply outlet distribution pipe 22 is installed horizontally long in the axial direction of the steam drum 14. Inside the steam drum 14, in addition to the water supply outlet distribution pipe 22, a downcomer 16 for supplying water to the evaporator, a cyclone separator 19 for separating steam and water from a mixed fluid of steam and water generated in the evaporator, and the like are installed. Has been done.

Next, the operation of this embodiment will be described.
In FIG. 1, the steam-water mixed fluid flowing into the steam drum from the economizer is separated into steam and water at the horizontal cyclone 23, and the steam enters the space of the steam drum from the left and right steam outlets of the horizontal cyclone 23. leak. On the other hand, the water separated by the horizontal cyclone 23 flows into the distribution trays 24 provided on the left and right of the horizontal cyclone 23, and is sent to the can water portion below the steam drum through a large number of small holes 26 provided at the bottom of the distribution tray 24. Be done.

The operating water level in the steam drum 14 is normally set at NWL (NORMAL WATER L) because of the installation position of the cyclone separator 19 on the evaporator side.
EVEL), but the water level operation control range is H
WL (HIGH WATER LEVEL) and LWL (LOW WATER LEVEL)
Between). And HHWL (HIGH HIGH WATER LEVEL) and LLWL which give the trip signal of the plant to the part which exceeded each level of HWL and LWL.
There is (LOW LOW WATER LEVEL).

The mounting position of the water supply outlet distribution pipe 22 is set such that the upper surface of the distribution tray 24 of the water supply outlet distribution pipe 22 is at the position of HHWL or a position slightly above HHWL. If installed in this portion, the distribution tray 24 will not be submerged in the can water, and therefore the separation characteristics of the horizontal cyclone 23 will not be affected. Further, the water supply from the economizer, which is distributed from the large number of small holes of the distribution tray 24 into the canned water in the steam drum 14, does not drop into the canned water from a high position. When the water level is below the water level, the feed water will flow into the can water without dropping, and the water level of the steam drum 14 will not be disturbed.

However, in the structure of the water supply outlet distribution pipe shown in FIG. 1, depending on the shape of the distribution tray and the mounting position, the water supply may drop into the water in the drum can through a number of small holes at the bottom in normal NWL operation. In this case, the distance over which the water supply falls is short, but there is a possibility that it will be entrained by the steam floating in the steam drum during the fall.
Therefore, as shown in FIG. 4, a large number of water supply distribution discharge pipes 28 are provided at the bottom of the distribution tray 24, and the outlet of the water supply distribution discharge pipe 28 is located above the boiler can water in any operating water level state. If it is installed so that it does not go out, the water supply will not disturb the water level of the steam drum.

Further, as shown in FIG. 3, the inlet of the water supply outlet distribution pipe 22 is a horizontal cyclone 23, where water and steam are separated. The steam flows out from the steam outlet of the horizontal cyclone 23 into the steam drum 14, and the water is sent to the distribution trays 24 provided on the left and right of the horizontal cyclone 23, and a large number of small holes 26 provided at the bottom of the distribution tray 24. It is sent into canned water. In this figure, the distribution trays 24 are installed on the left and right of the horizontal cyclone 23 of the water supply outlet distribution pipe 22, but the water supply introduction pipes 25 are provided in the main body cylinder on the end plate 27 side of the steam drum 14 or the end plate 27. In this case, the distribution tray 24 does not need to be installed on the left and right of the horizontal cyclone 23, but may be installed on only one side.

As described above, by providing the water supply outlet distribution pipe 22 including the horizontal cyclone 23 and the distribution tray 24, the steam component of the steam-water mixed fluid generated by steaming in the economizer can be stored in the can in the steam drum. Since the water does not flow into the water, the problem of impairing the stability of the water level control of the steam drum 14 is solved, and the steam cooled by the low temperature water in the steam drum 14 is rapidly condensed to cause the water hammer phenomenon. Since it does not occur, and further, vapor does not mix in the downcomer 16 and the water circulation characteristic of the evaporator is deteriorated, so that the problem of lowering boiler efficiency is solved.

Next, the effect of the water supply pipe 14 according to this embodiment will be described. As already explained, if the water supply is introduced into the drum with steaming inside the economizer, in the case of the conventional water supply inner pipe, the inner pipe is submerged in the can water, so steam bubbles are also submerged. Since it flows into the water, water hammer due to rapid condensation and unstable water level control occur.

On the other hand, in the present embodiment, when steaming occurs at the outlet of the economizer at the time of start-up or low load operation such as partial load operation state, steam and water are easily discharged in the horizontal cyclone part of the water supply outlet distribution pipe. The steam then flows into the steam drum from the left and right of the horizontal cyclone outlet, and the water drops from the numerous holes in the lower part of the separation tray toward the water surface of the drum. The water supply is well distributed in the axial direction of the steam drum by means of the numerous holes, so that the water supply does not disturb the water surface in the drum. Thus, even if steaming occurs at the outlet of the economizer, since the water outlet of the steam drum is not installed in the can water, water hammer does not occur and the water level control does not become unstable.

Even in a normal operation state where steaming does not occur, the shape of the distribution tray is designed so that all the water supply does not drop from the holes at the bottom of the distribution tray of the water supply outlet distribution pipe and overflow from the upper part of the distribution tray. decide.

The above embodiment is applied to the double pressure type exhaust heat recovery boiler for a combined cycle power plant, but the present invention is not limited to this, and can be similarly applied to other boiler devices. it can.

[0024]

As described above, according to the present invention,
It is possible to reliably prevent unstable water level control and water hammer in the steam drum due to steaming at the outlet of the economizer, such as during low-load operation of the exhaust heat recovery boiler system, and to prevent a decrease in boiler efficiency. You can

[Brief description of drawings]

FIG. 1 is a perspective view of a water supply outlet distribution pipe according to the present invention.

FIG. 2 is a vertical cross-sectional view of a steam drum portion of an exhaust heat recovery boiler apparatus having a water supply outlet distribution pipe of FIG.

FIG. 3 is a horizontal sectional view of a steam drum having a water supply outlet distribution pipe of FIG.

FIG. 4 is a perspective view of another water supply outlet distribution pipe according to the present invention.

FIG. 5 is a configuration diagram of a conventional exhaust heat recovery boiler device.

FIG. 6 is a vertical cross-sectional view of a conventional steam drum unit.

[Explanation of symbols]

1 ... Gas turbine exhaust gas, 2 ... High pressure superheater, 3 ... High pressure evaporator, 4 ... High pressure economizer, 5 ... High pressure steam drum, 6 ... Low pressure evaporator, 7 ... Low pressure economizer, 8 ... Low pressure steam drum, 9 ... Low pressure water supply pump, 10 ... High pressure water supply pump, 11 ... Low pressure water supply control valve, 12 ... High pressure water supply control valve, 13 ... Denitration device, 14
... Steam drum, 15 ... Can water, 16 ... Precipitation pipe, 17 ... Rise pipe, 18 ... Inner shell, 19 ... Cyclone separator, 20 ...
Steam pipe, 21 ... Water supply inner pipe, 22 ... Water supply outlet distribution pipe, 23
... horizontal cyclone, 24 ... distribution tray, 25 ... water supply introduction pipe, 26 ... small hole, 27 ... end plate, 28 ... water supply distribution discharge pipe.

Claims (1)

[Claims] 1. A boiler apparatus comprising a economizer, a steam drum, and a water supply pipe for supplying water to the steam drum via the economizer, and a flow control valve is provided in a water supply pipe system at the exit of the economizer. The exhaust heat characterized in that a water supply outlet distribution pipe in which a horizontal cyclone and a distribution tray are combined is provided at a water supply outlet for introducing a steam-mixed fluid into the steam drum from the economizer via the flow rate control valve. Recovery boiler device.