JP2002235893A - Air ventilator for water supply system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air ventilator for a water supply system suitable for discharging air in a pipe of an inverted U-bend pipe type. SOLUTION: This air extractor is composed from an evacuating line 9 branching off from an outlet connecting pipe 6 of a heat transfer pipe 2 composing an economizer of a waste heat collecting boiler and connecting to a steam condenser 8. The U-bend heat transfer pipe 2 is evacuated from the evacuating line 9 to ventilate air from the U-bend heat transfer pipe 2, and water is sent into the heat transfer pipe 2 through a water supply stop valve 4 provided in a U-bend heat transfer pipe inlet connecting pipe 3. Thereby, water is sucked and filled even in an upper part of the inverted U-bend heat transfer pipe 2 by a vacuum effect, so that the inverted U-bend heat transfer pipe 2 can be easily filled with water without generating the gathering of air.

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 for a combined cycle power plant, and more particularly to an air vent inside a reverse U-bend tube type heat transfer tube in which a heat transfer tube group of a water supply system has a header only at a lower portion. It concerns the device.

[0002]

2. Description of the Related Art Conventionally, a heat transfer tube group of a water supply system of a waste heat recovery boiler has a structure in which a number of heat transfer tubes are arranged in a grid between an upper header and a lower header. When the heat pipe was filled with water, the air inside the heat transfer pipe could be easily discharged to the atmosphere by opening the air vent valve provided in the upper header.

However, as a heat transfer tube group of a water supply system of a conventional heat recovery steam generator, a heat transfer tube group of an inverted U-bend type having a header only at a lower portion is used.

FIG. 2 shows a schematic configuration diagram of a heat transfer tube group of the inverted U-bend tube type. As shown in FIG. 2, water is supplied from a heat transfer tube inlet connecting pipe 3 to a lower header 1 through a water supply stop valve 4, and the water is supplied from the lower header 1 in a reverse U-bend pipe type heat transfer pipe 2 in parallel. It is introduced into the arranged heat transfer tube group. Feed water is sent from the upper part of the heat transfer pipe outlet connecting pipe 6 to the steam separation drum 5 through the control valve 7. At this time, the heat transfer tube outlet connecting pipe 6
An air release line 10 for releasing air to the air is branched and provided at an upper portion of the heat transfer tube 2 so that the air inside the heat transfer tube 2 can be discharged into the atmosphere when the heat transfer tube 2 is filled with water.

[0005]

In the conventional heat transfer tube group of the reverse U-bend type shown in FIG. 2, when the number of heat transfer tubes 2 becomes several tens to several hundreds, when the heat transfer tubes are filled with water. The air bleeding operation inside the heat transfer tube 2 is a burdensome operation as follows.

[0006] For example, a method is used in which the discharge pressure of the feedwater is increased by increasing the flow rate of the feedwater, and the air inside the heat transfer tube 2 is discharged to the atmosphere by swinging the feedwater in the heat transfer tube 2.
In addition, while increasing the water supply flow rate,
There is a method to cope with this by making the pipe diameter larger than before. Further, when the above two methods cannot be used, there is a method of opening the water supply adjusting valve 7 to release air to the steam separation drum 5.

However, even with the above method, it is difficult to completely extract the air in the air reservoir above the inside of the inverted U-bend heat transfer tube 2. If air remains inside the inverted U-bend heat transfer tube 2, the flow of the internal fluid is hindered during the boiler operation. Since the residual air and the feedwater flow in a mixed state, a water hammer is generated and the flow of the internal fluid is hindered. There are problems such as abnormal temperature rise of the internal fluid and excessive rise of the heat transfer tube temperature. Also, in order to eliminate the upper air pool inside the heat transfer tube 2 by the above-described method, it is necessary to confirm that the water inside the heat transfer tube 2 is full and that a large amount of water and a long time are required for filling the water. There is a problem that it becomes difficult.

[0008] It is an object of the present invention to provide a water supply system air bleeding apparatus that is optimal for discharging air from a pipe of a reverse U-bend pipe type.

[0009]

The above object of the present invention is attained by the following constitution. That is, an air venting device for a water supply system in which one or more water supply pipes each including a pair of lower headers and an inverted U-bend pipe having lower ends connected to the pair of lower headers are connected. Is a water supply system air vent device provided with a vacuum evacuation line branched at the outlet of the water supply system.

At this time, an automatic opening / closing valve is provided in the vacuum evacuation line, and a pressure detector for detecting the internal pressure is provided in the reverse U-bend tube, and the pressure of the automatic opening / closing valve is detected by the pressure detector. By providing a control device for opening / closing control, the automatic opening / closing valve of the evacuation line can be opened / closed according to the detected pressure inside the reverse U-bend tube. Further, a water supply opening / closing valve is provided at an inlet of the water supply system, and the water supply opening / closing valve is linked to an automatic opening / closing valve of the evacuation line and a pressure detector of a reverse U-bend pipe by a control device, so that the water supply opening / closing valve is operated in a reverse direction. It can be filled with no air remaining in the U-bend tube. In addition, if a vacuum line is connected to a device such as a condenser for condensing steam, the inside of which is in a reduced pressure state, vacuum can be easily drawn.

[0011]

The air in the inverted U-bend pipe is extracted by connecting the vacuum evacuation line to a vacuum evacuation device such as a condenser. As a result, the inside of the inverted U-bend tube is in a vacuum state, so that water is sucked in at the time of filling with water, and no air remains on the upper portion of the inverted U-bend tube.

[0012] Further, the automatic on-off valve provided in the evacuation line is controlled to open and close according to the detection value of the pressure detector for detecting the pressure in the reverse U-bend pipe, and / or provided at the inlet of the water supply system. By controlling the opening / closing valve for water supply to open / close, it is possible to automatically fill up the water while keeping a state in which no air remains in the reverse U-bend pipe.

[0013]

Embodiments of the present invention will be described below with reference to FIG. FIG. 1 shows an air venting device in a water supply system in a reverse U-bend heat transfer pipe 2 of a economizer of a waste heat recovery boiler.

A plurality of inverted U-bend heat transfer pipes 2 (only a plurality of heat transfer pipes 2 constitute the economizer) in the exhaust heat recovery boiler and in the vicinity thereof in the vicinity of the economizer. ), A heat transfer pipe inlet connecting pipe 3 for guiding water supply to the reverse U-bend heat transfer pipe 2, a water supply stop valve 4 provided in the heat transfer pipe inlet connecting pipe 3, and an outlet water of the reverse U-bend heat transfer pipe 2 to a brackish water separation drum. There are provided a heat transfer tube outlet connecting pipe 6 to be sent to the steam turbine 5, a control valve 7 for adjusting a flow rate of water supplied to the brackish water separation drum 5, and the like.

The air venting device branches off from the outlet connecting pipe 6 of the heat transfer pipe 2 constituting the economizer of the exhaust heat recovery boiler and is connected to the condenser 8
And a vacuum line 9 connected to the condenser 8. After evacuating the inside of the U-bend heat transfer tube 2 by evacuating the inside of the reverse U-bend heat transfer tube 2 from the evacuation line 9, the air is removed through the water supply stop valve 4 provided in the reverse U-bend heat transfer tube inlet connecting pipe 3. When the water is supplied to the inside of the heat transfer tube 2, the water is sucked into the upper portion of the reverse U-bend heat transfer tube 2 by the vacuum effect and is filled. In this manner, the inside of the reverse U-bend heat transfer tube 2 can be easily filled with water without generating air pockets in the upper portion of the reverse U-bend heat transfer tube 2.

Further, an automatic opening / closing valve 11 is connected to the evacuation line 9.
By providing a pressure detector 12 for detecting the pressure inside the heat transfer tube 2 and these control devices 13, it is possible to confirm the completion of the air removal inside the heat transfer tube 2 by evacuation and the completion of filling with water (full water). It can be easily performed, and the completion of the air bleeding inside the heat transfer tube 2 and the filling with water can be easily automated by linking the automatic on-off valve 11 and the evacuation.

Since the evacuation line 9 is connected to the condenser 8 for condensing steam used for power generation by a steam turbine or the like, the condenser 8 is easily inverted by the condenser 8 in which the internal pressure is reduced. The inside of the direction U bend heat transfer tube 2 can be evacuated.

When the control device 13 can also control the opening and closing of the regulating valve 7 provided in the heat transfer pipe outlet connecting pipe 6, the control of the amount of water supplied to the brackish water separation drum 5 and the release of air from the heat transfer pipe 2 Can be linked to control.

[0019]

According to the present invention, the inside of the inverted U-bend tube can be easily filled with water by evacuating the inside of the tube.

[Brief description of the drawings]

FIG. 1 is a system diagram showing an embodiment of an air vent device in a water supply system according to the present invention.

FIG. 2 is a system diagram showing an air venting device in a water supply system according to the related art.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 Lower header 2 Reverse U-bend heat transfer tube 3 Heat transfer tube inlet connection tube 4 Water supply stop valve 5 Steam separation drum 6 Heat transfer tube outlet connection tube 7 Control valve 8 Condenser 9 Vacuum line 10 Air release line 11 Automatic open / close valve 12 Pressure detector 13 Control device

Claims (5)

[Claims] 1. An air venting device for a water supply system, wherein one or more water supply pipes each including a pair of lower headers and an inverted U-bend pipe having lower ends connected to the pair of lower headers are connected to each other, An air venting device for a water supply system, wherein a vacuum line is branched and provided at an outlet of the water supply system. 2. An automatic opening / closing valve is provided in a vacuum evacuation line, and a pressure detector for detecting an internal pressure is provided in a reverse U-bend pipe, and the opening / closing control of the automatic opening / closing valve is performed by detecting the pressure of the pressure detector. The air vent device for a water supply system according to claim 1, further comprising a control device that performs the following. 3. A water supply on-off valve is provided at an inlet of the water supply system, and a control device for interlocking the water supply on-off valve with an automatic on-off valve of the evacuation line and a pressure detector of a reverse U-bend pipe is provided. 3. The air vent device for a water supply system according to claim 2, wherein: 4. The reverse U-bend pipe constitutes a economizer provided in a flue gas passage, and an outlet of the water supply system is provided with a water supply pipe and a brackish water separation drum connected to the water supply pipe. 2. The air vent device for a water supply system according to claim 1, wherein a vacuum evacuation line is provided branching from the water supply pipe. 5. The air vent device for a water supply system according to claim 4, wherein said vacuum line is connected to a condenser for converting steam into water.