JPH1182916A - Exhaust heat recovery boiler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the water hammer caused by the drain in releasing the hot banking by providing a heat transfer pipe on the most downstream side in which the fluid constantly flows in the rising direction among a plurality of heat transfer pipes of a superheater. SOLUTION: An exhaust heat recovery boiler 40 preheats the condensate fed from a condenser through a pump, etc., by an economizer, feeds it to a drum, and evaporates it in an evaporator. A superheater inlet connection pipe 41 to lead the saturated steam from a drum 22 is connected to a lower part of a boiler body, a superheater outlet connection pipe 42 to lead the superheated steam is led from an upper part of the boiler body, a heat transfer pipe on the most downstream side in which the fluid constantly flows in the rising direction among one or more heat transfer tubes of a superheater 43, is provided, and a boiler outlet stop valve 44 is arranged on an upper part of the boiler. No water hammer is generated thereby, and damages of a main steam pipe and its support device can be avoided.

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 used for a combined cycle power plant or the like.

[0002]

2. Description of the Related Art Combined cycle power plants are frequently used in recent thermal power plants because of problems such as diversification of high-efficiency operation and operation and shortening of startup time. As a combined cycle power plant already in operation, there is a combination of a gas turbine and a steam turbine, which includes a gas turbine, an exhaust heat recovery boiler, and a steam turbine.

[0003] The exhaust heat recovery boiler uses exhaust heat of a gas turbine as a heat source, feed water from a steam turbine as a heat source, and applies heat to the heat source to generate steam. The generated steam operates a steam turbine to generate power. This waste heat recovery boiler has
A superheater, an evaporator with a drum, and a economizer are arranged along the flow of the exhaust heat, and the feedwater (saturated water) is converted into superheated steam by passing through these heat exchangers.

FIG. 10 shows such an exhaust heat recovery boiler 1.
1 is a system diagram showing a power plant having 0. FIG. In this figure, a gas turbine 11 drives a generator 13 together with a steam turbine 12, and exhaust gas from the gas turbine 11 is recovered by a waste heat recovery boiler main body 14 and discharged from a chimney 15. Has become.

The steam used in the steam turbine 12 becomes water in a condenser 16, and is condensed into a condensate pump 17 and a feed water pump 18.
Thereby, it is sent to the economizer 20 through the economizer inlet stop valve 19. Here, the water preheated by the exhaust gas from the gas turbine is sent to the drum 22 through the water supply control valve 21, and is evaporated in the evaporator 23 to be steam. This steam is further superheated by the superheater 24 to increase energy, and passes through a boiler outlet stop valve 25, a main steam stop valve 26, and a main steam control valve 27,
It is sent to the steam turbine 12 and used for power generation.

By the way, the combined cycle power generation plant uses a so-called DSS (Das) which repeatedly starts and stops every day by taking advantage of the convenience of quick start and stop of the gas turbine.
iryStart Stop) operation. In such an operation, a method called hot banking is used in order to generate steam without delaying the rapid start of the gas turbine at the start of the next day. This hot banking is to keep the exhaust heat recovery boiler in a hot state during plant shutdown and prepare for startup the next morning, close the boiler outlet damper to save residual heat, and preheat It is designed to confine canned water and feedwater to an evaporator with a drum, a economizer, and a water supply line.

In the exhaust heat recovery boiler 10 shown in FIG. 10, when the operation is stopped, the boiler outlet damper 28 is closed and the preheated water is supplied to the economizer inlet stop valve 19 and the water supply control valve 21.
In the economizer 20. The boiler outlet shuts off the boiler outlet stop valve 25 in the evaporator-equipped drum 22 and stands by until the next operation.

[0008]

However, as shown in FIG. 11, the conventional natural circulation type exhaust heat recovery boiler 10 is rational in terms of arrangement when the number of superheater panels is one or odd. As described above, the superheater inlet connecting pipe 29 for guiding the saturated steam coming out of the drum 22 is connected to the panel of the superheater 24 from the upper portion of the exhaust heat recovery boiler main body 14. The superheater outlet connecting pipe 30 for guiding the superheated steam taken out from the panel outlet of the superheater 24 is taken out from the lower part of the exhaust heat recovery boiler main body 14. In such an arrangement, when the boiler outlet stop valve 25 is closed for hot banking, the lower part of the superheater 24 is cooled by natural convection in the exhaust gas passage portion of the boiler main body, and steam in the superheater is drained. Further, as the volume of steam is reduced by draining, saturated steam is further discharged from the drum 22 to the superheater 24.
As a result, the drain A is accumulated from the lower part of the superheater 24 to the boiler outlet stop valve 25 of the superheater outlet connection pipe 30.

In such a state, when the boiler outlet stop valve 25 is opened at the time of releasing hot banking the next morning, the drum 22
Due to the residual pressure, the drain A accumulated in the lower portion of the superheater 24 is extruded at once, is accelerated, and collides with the elbow of the main steam pipe. For this reason, a water hammer is generated, and there is a risk of damaging the main steam pipe and its supporting device.

[0010] The present invention has been made to solve such a problem, and an object of the present invention is to provide a heat recovery steam generator that can prevent a water hammer due to drainage at the time of releasing hot banking.

[0011]

A first feature of the present invention is as follows.
A boiler body through which exhaust gas passes, a economizer provided inside the boiler body, a drum connected to the economizer, an evaporator connected to the drum and provided inside the boiler body, A superheater connected to the drum and provided inside the boiler body, the superheater having one or more connected heat transfer tubes, and condensing water condensed from the condenser through a pump. The remaining water is heated by the exhaust gas and water is supplied to the drum.The supplied water is evaporated by the evaporator and sent to the superheater.The steam sent to the superheater is superheated by the superheater, and Heat recirculation boiler for supplying exhausted steam to a steam turbine, wherein the most downstream heat transfer tube among one or more heat transfer tubes of the superheater is a heat transfer tube through which fluid always flows in an ascending direction. It is a boiler.

[0012] A second feature of the present invention is that the superheater conducts steam flowing downward from the upper superheater header toward the lower superheater header, and a superheater pipe from the lower superheater header. An exhaust heat recovery boiler having a lower superheater intermediate header connected to both heat transfer tubes for guiding steam flowing upward toward the header.

A third feature of the present invention is a waste heat recovery boiler in which a superheater has a heat transfer tube panel in which an upper superheater header is divided into two and a lower superheater header is integrated.

A fourth feature of the present invention is that a superheater inlet connecting pipe for introducing saturated steam from the drum to the superheater is connected to the superheater from a lower portion of the boiler body, and a superheater outlet for guiding the superheated steam from the superheater to the steam turbine. This is an exhaust heat recovery boiler that takes out the connecting pipe from the upper part of the boiler body to the steam turbine.

[0015] A fifth feature of the present invention is an exhaust heat recovery boiler in which a boiler outlet stop valve provided in a superheater outlet connecting pipe for guiding superheated steam from the superheater to the steam turbine is disposed above the boiler main body.

A sixth feature of the present invention is that a boiler main body through which exhaust gas passes, a economizer provided inside the boiler main body, a drum connected to the economizer, and a drum connected to the drum And an evaporator provided inside the boiler body, and a superheater connected to the drum and provided inside the boiler body, the superheater having one or more connected heat transfer tubes, and a pump provided from the condenser. The condensate conveyed through was conserved by exhaust gas in a economizer to supply water to the drum, and the supplied water was evaporated by an evaporator, then sent to a superheater, and sent to the superheater. This is a natural circulation type exhaust heat boiler that superheats steam with a superheater and supplies the superheated steam to a steam turbine.The exhaust heat recovery boiler has a stop valve provided in a pipe connecting the drum and the superheater. is there.

A seventh feature of the present invention is an exhaust heat recovery boiler in which a stop valve is disposed at an uppermost position on a pipe connecting a drum and a superheater.

An eighth feature of the present invention is that a boiler main body through which exhaust gas passes, a economizer provided inside the boiler main body, a drum connected to the economizer, and a drum connected to the drum And an evaporator provided inside the boiler body, and a superheater connected to the drum and provided inside the boiler body, the superheater having one or more connected heat transfer tubes, and a pump provided from the condenser. The condensate conveyed through was conserved by exhaust gas in a economizer to supply water to the drum, and the supplied water was evaporated by an evaporator, then sent to a superheater, and sent to the superheater. A natural circulation type exhaust heat boiler that superheats steam with a superheater and supplies the superheated steam to a steam turbine, and is located at a lower portion of the boiler and connects to a superheater outlet pipe connecting the superheater and the steam turbine. , Exhaust heat recovery with drain trap Meet in the boiler.

A ninth feature of the present invention is that a boiler main body through which exhaust gas passes, a economizer provided inside the boiler main body, a drum connected to the economizer, and a drum connected to the drum And an evaporator provided inside the boiler body, and a superheater connected to the drum and provided inside the boiler body, the superheater having one or more connected heat transfer tubes, and a pump provided from the condenser. The condensate conveyed through was conserved by exhaust gas in a economizer to supply water to the drum, and the supplied water was evaporated by an evaporator, then sent to a superheater, and sent to the superheater. A natural circulation type exhaust heat boiler that superheats steam with a superheater and supplies the superheated steam to a steam turbine, and is located at a lower portion of the boiler and connects to a superheater outlet pipe connecting the superheater and the steam turbine. Waste heat recovery boiler with drain valve Over.

A tenth feature of the present invention is that a boiler main body through which exhaust gas passes, a economizer provided inside the boiler main body, a drum connected to the economizer,
An evaporator connected to the drum and provided inside the boiler main body; and a superheater connected to the drum and provided inside the boiler main body. The superheater has one or more connected heat transfer tubes. The condensate sent from the water pump via the pump is preheated by exhaust gas in the economizer and supplied to the drum, and the supplied water is evaporated by the evaporator and then sent to the superheater.
A natural circulation type exhaust heat boiler that superheats the steam sent to the superheater with a superheater and supplies the superheated steam to a steam turbine, wherein a boiler outlet pipe connects the superheater and the steam turbine. The exhaust heat recovery boiler further includes a boiler outlet stop valve, a bypass line provided in the boiler outlet stop valve, and a stop valve provided in the bypass line.

An eleventh feature of the present invention is an exhaust heat recovery boiler in which a drain valve according to a ninth feature of the present invention is provided to the exhaust heat recovery boiler according to the sixth feature of the present invention.

A twelfth feature of the present invention is an exhaust heat recovery boiler in which a waste heat recovery boiler according to a sixth feature of the present invention is provided with a bypass line according to a tenth feature of the present invention.

The thirteenth feature of the present invention is the eleventh feature of the present invention.
An exhaust heat recovery boiler provided with a bypass line according to a tenth aspect of the present invention in the exhaust heat recovery boiler which is the characteristic of the present invention.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an exhaust heat recovery boiler according to the present invention will be described with reference to the accompanying drawings. The same components as those of the conventional example are denoted by the same reference numerals, and description thereof is omitted.

FIG. 1 is a view schematically showing a waste heat recovery boiler according to a first embodiment of the present invention, and FIG. 2 is a view showing a superheater of the waste heat recovery boiler. The exhaust heat recovery boiler 40 is configured to heat the condensate sent from the condenser via a pump or the like, heat the condensate, feed the water to the drum, evaporate the evaporator, and then use the superheater to remove the steam. In a natural circulation type waste heat recovery boiler that overheats and supplies steam to a steam turbine,
Superheater inlet connection pipe 4 that guides saturated steam from drum 22
1 is connected from the lower part of the boiler main body 14, the superheater outlet connecting pipe 42 for leading the superheated steam is taken out from the upper part of the boiler main body 14, the final panel of the superheater 43 is always a rising flow panel, and the boiler outlet stop valve 44 is provided at the upper part of the boiler. By arranging, the drain A generated during hot banking is moved into the main steam pipe 45 so that a water hammer is not generated when hot banking is released.

In the exhaust heat recovery boiler 40, natural convection cooling in the exhaust gas passage 46 of the exhaust heat recovery boiler 40 causes the lower portion of the superheater 43 to be closed when the boiler outlet stop valve 44 is closed during hot-banking operation. Even if steam drain A is generated, the outlet of the superheater 43 is taken out from the upper part of the exhaust heat recovery boiler main body 14 and the boiler outlet stop valve 44 is arranged at the upper part of the boiler main body 14, so that the boiler outlet stop valve 44 A steam layer B can be inserted between the heater A and the drain A of the superheater 43. Thereby, when opening the boiler outlet stop valve 44 when the boiler is released from banking, the steam B in the superheater 43 is first sent to the main steam pipe 45, and the steam B in the upper part of the superheater 43 is discharged. When the portion is filled in the main steam pipe 45, the movement of the superheater drain A ends, so that no water hammer is generated, and the problem of breakage of the main steam pipe 45 and its supporting device can be avoided.

FIG. 3 shows a superheater heat transfer tube panel 51 used in the second embodiment of the exhaust heat recovery boiler according to the present invention.
FIG. 4 is a schematic structural view of a superheater heat transfer tube panel 51.
It is an enlarged view of the lower part of FIG. This exhaust heat recovery boiler 50
One superheater heat transfer tube panel 51 is arranged so as to be orthogonal to the gas flow direction, and a heat transfer tube (hereinafter, referred to as a heat transfer tube) that guides steam flowing downward from the upper superheater inlet header 52 to the lower superheater intermediate header 53. Both a downflow heat transfer tube 54) and a heat transfer tube (hereinafter referred to as an upflow heat transfer tube 56) that guides steam flowing upward from the lower superheater intermediate header 53 toward the upper superheater outlet header 55 are connected. A middle superheater header 53 is disposed so that drain generated during hot banking is not moved into the main steam pipe 57 so that a water hammer is not generated when hot banking is released. In this exhaust heat recovery boiler 50, even if steam drain occurs in the superheater heat transfer tube panel 51 due to natural convection cooling in the exhaust heat recovery boiler exhaust gas passage 58, the steam drain is generated by the downflow heat transfer tube 54 and the ascending flow heat transfer tube 56. A U-shaped seal can be formed.
Thereby, the filling of the superheater drain stops near the upper superheater outlet header 55, and it becomes difficult for the superheater drain to move into the main steam pipe 57. Therefore, it is possible to prevent the occurrence of a water hammer at the time of releasing the hot banking, and it is possible to avoid a problem of damage to the main steam pipe and its supporting device.

FIG. 5 is a schematic structural view of a superheater heat transfer tube panel 61 showing a third embodiment of the exhaust heat recovery boiler according to the present invention. In this exhaust heat recovery boiler, one superheater heat transfer tube panel 61 is arranged in the gas flow direction, the upper superheater header 62 is divided into two, and the lower superheater middle header 63 is integrated, which is generated during hot banking. By preventing the drain from flowing into the main steam pipe, a countermeasure is taken to prevent water hammer from being generated when hot banking is released. In this exhaust heat recovery boiler, even if a steam drain occurs in the superheater heat transfer tube panel 61 due to natural convection cooling in the exhaust heat recovery boiler exhaust gas passage, the upper superheater header 62 is divided into two parts so that the upper superheater The header has both functions of an inlet header 64 and an outlet header 65, and is composed of a heat transfer tube group 66 for guiding steam flowing downward and a heat transfer tube group 67 for guiding steam flowing upward.
A seal can be formed. As a result, the filling of the superheater drain stops near the outlet header 65, and it becomes difficult for the superheater drain to move to the main steam pipe 68. Therefore, water hammer does not occur when hot banking is released,
The problem of breakage of the main steam pipe and its supporting device can be avoided.

FIG. 6 is a schematic system diagram showing a fourth embodiment of an exhaust heat recovery boiler according to the present invention. In the exhaust heat recovery boiler 70, a stop valve 72 is disposed at the uppermost portion on a communication pipe 71 connecting the drum 22 and the superheater 24, so that harmful superheater drain is not accumulated when hot banking is released.

In the waste heat recovery boiler 70, the condensate sent from the condenser via the pump is preheated by the economizer, supplied to the drum and evaporated by the evaporator, and then evaporated by the superheater. In a natural circulation type exhaust heat recovery boiler that superheats steam and supplies the steam to a steam turbine, a stop valve 72 is provided at an uppermost portion on a communication pipe 71 connecting the drum 22 and the superheater 24. Therefore, if the stop valve 72 is closed during hot banking, even if steam drain A is generated below the superheater 24 due to natural convection cooling in the exhaust gas passage portion 46 of the exhaust heat recovery boiler, steam due to drainage is generated. It is possible to prevent the saturated steam from being drawn into the superheater 24 from the drum 22 due to the volume reduction of the drum 22. Therefore, it is possible to prevent a large amount of drain generated from the lower portion of the superheater 24 to the downstream side. Also, a small amount of drain generated by condensation of the vapor in the superheater 24 can be discharged during banking by the drain trap 73 installed in the superheater outlet pipe 30 located below the boiler. As a result, no harmful drain is generated during banking, so that when the boiler is released from banking, no water hammer is generated due to the movement of the drain, and the problem of damage to the main steam pipe and its supporting device can be avoided. .

FIGS. 7, 8, and 9 show fifth, sixth, and seventh embodiments of the exhaust heat recovery boiler according to the present invention, respectively. These exhaust heat recovery boilers are examples in which three exhaust heat recovery circuits of low pressure, medium pressure, and high pressure are provided in parallel.

An exhaust heat recovery boiler 80 shown in FIG. 7 has a low-pressure pump 81 as a low-pressure circuit, and supplies water from a condenser. A low-pressure economizer 82 is connected to the low-pressure pump 81, and a low-pressure steam drum 83 is connected to the low-pressure economizer 82. A low-pressure superheater inlet pipe 84 is connected to the low-pressure steam drum 83, and a low-pressure superheater 85 is connected to the low-pressure superheater inlet pipe 84.
Is connected. A low-pressure superheater outlet pipe 86 is connected to the low-pressure superheater 85, and a low-pressure superheater outlet stop valve 87 is connected to the low-pressure superheater outlet pipe 86.

Similarly, the medium pressure pump 8
8, medium pressure economizer 89, medium pressure steam drum 90, medium pressure superheater inlet pipe 91, medium pressure superheater 92, medium pressure superheater outlet pipe 9
3. The intermediate pressure superheater outlet stop valve 94 is connected in this order.

Similarly, the high-pressure circuit includes a high-pressure pump 95, a high-pressure economizer 96, a high-pressure steam drum 97, a high-pressure superheater inlet pipe 98, a high-pressure superheater 99, a high-pressure superheater outlet pipe 100, and a high-pressure superheater outlet. The stop valve 101 is connected in this order. Further, the low pressure superheater inlet pipe 84, the medium pressure superheater inlet pipe 91, and the high pressure superheater inlet pipe 98 are provided with stop valves 102, 103, and 104, respectively.

In such a configuration, the low pressure pump 81
Is heated by the low-pressure economizer 82, becomes steam on the low-pressure steam drum 83, is further heated by the low-pressure superheater 85, and is supplied as superheated steam. The same applies to the intermediate voltage circuit and the high voltage circuit.

Hot banking is performed in such an exhaust heat recovery boiler, and each superheater outlet stop valve 87, 9
4 and 101, each superheater 85, 92, 99, each superheater inlet pipe 84, 91, 98, each superheater outlet pipe 86, 9 by natural convection in the exhaust gas passage of the boiler body.
3,100 is cooled. For this reason, the internal vapor is condensed to form a drain, and the internal pressure is reduced. However, in this exhaust heat recovery boiler, stop valves 102, 103,
104, each superheater 85, 92, 9
Even if the air pressure in 9 falls, the saturated water of each steam drum is not newly drawn. Therefore, it is possible to prevent a situation in which drainage due to vapor condensation occurs continuously and a large amount of drain is accumulated in this portion.

In this case, the stop valves 102, 103,
Without 104, the continuous withdrawal and vaporization of saturated water from the drum would reduce the drum pressure, and would have no meaning in hot banking to maintain the exhaust heat recovery boiler at a high temperature. However, in the exhaust heat recovery boiler 80, the stop valve 102 and the like can prevent the continuous intake of the saturated water and prevent the pressure of the steam drum from lowering, so that effective hot banking can be performed.

In the exhaust heat recovery boiler 110 shown in FIG. 8, each superheater outlet stop valve 8 is connected to each steam drum 83, 90, 97.
Superheater drain valves 111, 112, and 113 are installed at the bottom of the steam system to 7, 94, and 101.

By keeping the superheater drain valves 111, 112, 113 closed during the period of stopping the exhaust heat recovery boiler, the superheater outlet stop valves 87, 94, 101 from the steam drums 83, 90, 97 are closed. Drain generated by natural cooling in the steam system stays in the steam system as it is. For this reason, the drain level in the vapor system gradually increases, and the surface area of the vapor phase decreases. As a result, the rate of drainage by natural cooling also decreases, and finally, when drainage flows to the respective superheater inlet pipes 84, 91, 98, drainage stops. This makes it possible to minimize the amount of drainage during the period during which the exhaust heat recovery boiler is stopped, and more effective hot banking can be performed because the exhaust heat recovery boiler is maintained at a high temperature.

If the stagnant drain is left as it is in the exhaust heat recovery boiler startup process, when the superheater outlet stop valves 87, 94, and 101 are opened, the stagnant drain is discharged from the superheater outlet stop valves 87, 94, and 101. 101, there is a possibility that water flows into the downstream side and causes water hammer in the downstream side pipe and water retention to the steam turbine further downstream. For this reason, during the start-up process of the exhaust heat recovery boiler, each superheater outlet stop valve 8
Before opening 7, 94, 101, each superheater outlet stop valve 87,
It is necessary to reliably discharge the drain on the upstream side of 94, 101. That is, in the start-up process of the exhaust heat recovery boiler, the respective superheater drain valves 111, 112, 113 are opened before the respective superheater outlet stop valves 87, 94, 101 are opened to drain the drain. The timing of the closing operation of the superheater drain valves 111, 112, and 113 is determined according to each of the steam drums 83, 90, and 97.
By performing this when the differential pressure in each superheater outlet pipe reaches 0 or reaches a set differential pressure, the water hammer can be suppressed. In addition, as a method of measuring the closing timing of each superheater drain valve, in addition to the method using the difference between the temperature of the steam section of each steam drum and the temperature of each superheater outlet pipe, the valve closing operation of each superheater drain valve is performed by a timer. The same effect can be obtained.

The exhaust heat recovery boiler 120 shown in FIG. 9 is provided with pipes (bypass pipes) 121, 122, 123 connecting upstream and downstream of each of the superheater outlet stop valves 87, 94, 101. After the exhaust heat recovery boiler is started, the bypass pipes 121, 122, 12 of the superheater outlet stop valves 87, 94, 101 are provided.
The upstream and downstream sides of the superheater outlet stop valves 87, 94, and 101 are gradually equalized by controlling the degree of opening of the control valves 124, 125, and 126 disposed in the control valve 3. Equalization completed or
When the pressure difference becomes equal to or lower than the set differential pressure, each superheater outlet stop valve 87, 9
The water hammer can be prevented by performing the opening operation of the 4,101.

Each superheater outlet stop valve 87, 94, 1
01 at the slightly open position, and the superheater outlet stop valve 8
When the upstream and downstream pressures of 7, 94, 101 are equalized and become equal to or less than the set differential pressure, each superheater outlet stop valve 87, 94, 1
Even if 01 is fully opened, the same effect as above can be obtained.

[0043]

As described above, according to the exhaust heat recovery boiler of the present invention, since the final panel of the superheater is always a rising flow panel, the outlet of the superheater is located above the exhaust heat recovery boiler. And a boiler outlet stop valve can be placed on top of the boiler. Therefore, when the boiler outlet stop valve is closed during shutdown for hot banking, even if steam is generated in the lower part of the superheater due to natural convection cooling in the exhaust heat recovery boiler exhaust gas passage, the boiler outlet stop valve and the overheat A vapor layer can be formed with the drain in the vessel. As a result, when the boiler outlet stop valve is opened when the banking of the boiler is released, steam in the superheater is first sent to the main steam pipe, and a part of the upper steam layer in the superheater is removed from the main steam pipe. The transfer of the superheater drain is completed when the water is charged.
Therefore, no water hammer is generated, and the problem of breakage of the main steam pipe and its supporting device can be avoided.

Further, according to the exhaust heat recovery boiler of the present invention, since the stop valve is provided on the connecting pipe connecting the drum and the superheater, if this valve is closed during hot banking, the exhaust heat can be recovered. Even if steam drains occur in the lower part of the superheater due to natural convection cooling in the exhaust gas passage of the recovery boiler, it prevents the saturated steam from being continuously drawn from the drum to the superheater due to the reduction in the volume of steam due to drainage. be able to. Therefore, a large amount of drain can be prevented from accumulating from the lower part of the superheater to the boiler outlet stop valve, and a water hammer can be avoided. In addition, by closing the stop valve during hot banking, it is possible to prevent a decrease in drum pressure due to continuous drawing of saturated water from the drum and a decrease in drum temperature due to continuous evaporation of saturated water. Can be. Therefore, the exhaust heat recovery boiler can be maintained at a high temperature, and the purpose of hot banking can be achieved.

Further, according to the exhaust heat recovery boiler of the present invention, since the drain trap is provided at the outlet pipe of the superheater located at the lower part of the boiler, a small amount of drain generated by the condensation of the steam in the superheater can be removed. Can be discharged during banking. Therefore, water hammer at the time of hot banking cancellation can be prevented,
The problem of breakage of the main steam pipe and its supporting device can be avoided.

Further, according to the exhaust heat recovery boiler of the present invention, since the drain valve is provided in the superheater outlet pipe located at the lower part of the boiler, the drain valve is closed while the exhaust heat recovery boiler is stopped. In addition, the drain generated by natural cooling can be retained in the steam system as it is. Therefore, as the drain level in the steam system gradually increases and the surface area of the vapor phase decreases, the rate of drainage also decreases, and eventually drainage stops when drainage flows to the superheater inlet pipe. I do. For this reason, it is possible to suppress and minimize the increase in the amount of drainage during the stoppage period of the exhaust heat recovery boiler. Therefore, it is possible to prevent the drum from being reduced in pressure and lowering the temperature by continuous vaporization of the saturated water, and to maintain the high temperature state, thereby enabling effective hot banking. Further, by opening the drain valve before the exhaust heat recovery boiler is started, the stored drain can be discharged, so that water hammer can be prevented.

According to the exhaust heat recovery boiler of the present invention, since the boiler outlet stop valve is provided with the bypass line and the bypass line is provided with the stop valve, it is provided in the bypass pipe after the exhaust heat recovery boiler is started. Control the opening of the stop valve, gradually reduce the difference between the upstream pressure and the downstream pressure of the superheater outlet stop valve and equalize the pressure. Water hammer can be prevented by opening the container outlet stop valve.

[Brief description of the drawings]

FIG. 1 is a schematic system diagram showing an exhaust heat recovery boiler according to a first embodiment of the present invention.

FIG. 2 is an enlarged view of a portion viewed from a direction indicated by II-II in FIG.

FIG. 3 is a view showing a superheater heat transfer tube panel of an exhaust heat recovery boiler according to a second embodiment of the present invention.

FIG. 4 is an enlarged view of a portion viewed from a direction indicated by a line IV-IV in FIG. 3;

FIG. 5 is a view showing a superheater heat transfer tube panel of an exhaust heat recovery boiler according to a third embodiment of the present invention.

FIG. 6 is a schematic structural view showing an exhaust heat recovery boiler according to a fourth embodiment of the present invention.

FIG. 7 is a schematic structural view showing an exhaust heat recovery boiler according to a fifth embodiment of the present invention.

FIG. 8 is a schematic structural view showing an exhaust heat recovery boiler according to a sixth embodiment of the present invention.

FIG. 9 is a schematic structural view showing an exhaust heat recovery boiler according to a seventh embodiment of the present invention.

FIG. 10 is a schematic system diagram showing an example of a conventional exhaust heat recovery boiler.

FIG. 11 is a schematic diagram showing drain generated by the exhaust heat recovery boiler during hot banking.

[Explanation of symbols]

 REFERENCE SIGNS LIST 12 steam turbine 14 boiler main body 16 condenser 20 energy saving device 22 drum 23 evaporator 24 superheater 52 upper superheater inlet header 53 lower superheater intermediate header 54 downflow heat transfer pipe 55 upper superheater outlet header 56 upflow transmission Heat pipe 41 Superheater inlet connecting pipe 42 Superheater outlet connecting pipe 44, 87, 94, 101 Boiler outlet stop valve 73 Drain trap 102, 103, 104 Stop valve 111, 112, 113 Drain valve 121, 122, 123 Bypass pipe 124, 125, 126 control valve

Claims (13)

[Claims] 1. A boiler body through which exhaust gas passes, a boiler provided inside the boiler body, a drum connected to the boiler, and a boom connected to the drum and provided inside the boiler body. And a superheater connected to the drum and provided inside the boiler body, wherein the superheater has one or more connected heat transfer tubes, and is connected to the condenser via a pump. The condensed water conveyed is preheated by exhaust gas in the economizer and supplied to the drum, and the supplied water is evaporated in the evaporator and then sent to the superheater and sent to the superheater. In the natural circulation type exhaust heat boiler, which superheats the heated steam in the superheater and supplies the superheated steam to the steam turbine, the most downstream heat transfer tube among the one or more heat transfer tubes of the superheater is always used. Heat transfer tube through which fluid flows upward An exhaust heat recovery boiler, characterized in that: 2. The exhaust heat recovery boiler according to claim 1, wherein the superheater is a heat transfer tube for guiding steam flowing downward from an upper superheater header to a lower superheater header, and a lower superheater pipe. An exhaust heat recovery boiler comprising a lower superheater intermediate header connected to both a heat transfer pipe for guiding steam flowing upward from the heater toward the upper superheater header. 3. The exhaust heat recovery boiler according to claim 1, wherein said superheater has a heat transfer tube panel in which an upper superheater header is divided into two and a lower superheater header is integrated. Waste heat recovery boiler. 4. The exhaust heat recovery boiler according to claim 1, wherein a superheater inlet connecting pipe for introducing saturated steam from the drum to the superheater is connected to the superheater from a lower portion of the boiler main body, and the superheater is connected to the superheater. An exhaust heat recovery boiler, wherein a superheater outlet connecting pipe that guides superheated steam to a steam turbine is taken out from an upper portion of the boiler main body to the steam turbine. 5. The exhaust heat recovery boiler according to claim 1, wherein a boiler outlet stop valve provided in a superheater outlet connecting pipe for guiding superheated steam from the superheater to the steam turbine is provided.
An exhaust heat recovery boiler disposed above the boiler body. 6. A boiler body through which exhaust gas passes, a boiler provided inside the boiler body, a drum connected to the boiler, and a boom connected to the drum and provided inside the boiler body. And a superheater connected to the drum and provided inside the boiler body, wherein the superheater has one or more connected heat transfer tubes, and is connected to the condenser via a pump. The condensed water conveyed is preheated by exhaust gas in the economizer and supplied to the drum, and the supplied water is evaporated in the evaporator and then sent to the superheater and sent to the superheater. In a natural circulation type exhaust heat boiler that superheats the heated steam in the superheater and supplies the superheated steam to a steam turbine, wherein a stop valve is provided in a pipe connecting the drum and the superheater. Waste heat recovery boiler. 7. The exhaust heat recovery boiler according to claim 6, wherein the stop valve is disposed at an uppermost position on a pipe connecting the drum and the superheater. Recovery boiler. 8. A boiler body through which exhaust gas passes, a boiler provided inside the boiler body, a drum connected to the boiler, and a boom connected to the drum and provided inside the boiler body. And a superheater connected to the drum and provided inside the boiler body, wherein the superheater has one or more connected heat transfer tubes, and is connected to the condenser via a pump. The condensed water conveyed is preheated by exhaust gas in the economizer and supplied to the drum, and the supplied water is evaporated in the evaporator and then sent to the superheater and sent to the superheater. In the natural circulation type exhaust heat boiler, which superheats the heated steam in the superheater and supplies the superheated steam to the steam turbine, a superheater outlet located below the boiler and connecting the superheater to the steam turbine Drain in piping An exhaust heat recovery boiler comprising a trap. 9. A boiler body through which exhaust gas passes, a economizer provided inside the boiler body, a drum connected to the economizer, and a boom connected to the drum and provided inside the boiler body. And a superheater connected to the drum and provided inside the boiler body, wherein the superheater has one or more connected heat transfer tubes, and is connected to the condenser via a pump. The condensed water conveyed is preheated by exhaust gas in the economizer and supplied to the drum, and the supplied water is evaporated in the evaporator and then sent to the superheater and sent to the superheater. In the natural circulation type exhaust heat boiler, which superheats the heated steam in the superheater and supplies the superheated steam to the steam turbine, a superheater outlet located below the boiler and connecting the superheater to the steam turbine Drain in piping An exhaust heat recovery boiler comprising a valve. 10. A boiler main body through which exhaust gas passes, a economizer provided inside the boiler main body, a drum connected to the economizer, and provided inside the boiler main body connected to the drum And a superheater connected to the drum and provided inside the boiler body, wherein the superheater has one or more connected heat transfer tubes, and is connected to the condenser via a pump. The condensed water conveyed is preheated by exhaust gas in the economizer and supplied to the drum, and the supplied water is evaporated in the evaporator and then sent to the superheater and sent to the superheater. A natural circulation type exhaust heat boiler that superheats the heated steam in the superheater and supplies the superheated steam to a steam turbine, wherein a boiler outlet stop is connected to a boiler outlet pipe connecting the superheater and the steam turbine. Set valve A boiler outlet stop valve provided with a bypass line, and the bypass line provided with a stop valve. 11. An exhaust heat recovery boiler according to claim 6,
An exhaust heat recovery boiler further comprising the drain valve according to claim 9. 12. An exhaust heat recovery boiler according to claim 6,
An exhaust heat recovery boiler further comprising the bypass line according to claim 10. 13. An exhaust heat recovery boiler according to claim 11, further comprising a bypass line according to claim 10.