Steam drain recovery system and waste treatment facility equipped therewith

Abstract

This invention provides a steam condensate recovery system that can suppress the occurrence of water hammer due to stagnant steam condensate. [Solution] The steam drain recovery system 70 recovers steam drain discharged from the heat exchanger 50 and comprises a first flow path 73 through which the steam drain discharged from the heat exchanger 50 flows, a second flow path 74 and a third flow path 75 branching off from the same branching point B on the first flow path 73, a deaerator 72 connected to the second flow path 74, a condensate tank 71 connected to the third flow path 75 at a lower level than the deaerator 72, and a switching unit 77 that switches the opening and closing of at least the second flow path 74. The switching unit 77 is positioned at approximately the same level as the inlet 721 of the deaerator 72 that receives the steam drain flowing through the second flow path 74.

Description

Technical Field

[0001] The present invention relates to a steam drain recovery system for recovering steam drains formed by condensation of steam in a heat exchanger.

Background Art

[0002] In waste treatment facilities, it is known to heat-exchange the steam generated in a waste heat boiler with the combustion air supplied into the furnace during the operation of an incinerator, and to recover the discharged steam drain into the waste heat boiler via a deaerator (Patent Document 1). The recovery system described in Patent Document 1 is configured such that the destination of the steam drain discharged from the heat exchanger (combustion air preheater) where heat exchange is performed can be switched between a deaerator and a condensate tank according to its temperature, and by switching the destination of the steam drain having a temperature lower than the set temperature to the condensate tank, it is intended to prevent the water hammer phenomenon that occurs when low-temperature steam drain is sent into the deaerator.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a waste treatment facility equipped with a recovery system as shown in Patent Document 1, the deaerator is usually installed at a high position, while the condensate tank is installed at a low position. Therefore, the flow path through which the steam drain discharged from the heat exchanger flows may branch into a deaerator-side flow path and a condensate tank-side flow path at a position lower than the deaerator but higher than the condensate tank. In this case, the switching valve that switches the opening and closing of the deaerator-side flow path is generally installed near the branching point of the flow path (in Patent Document 1, a three-way valve is installed at the branching point as the switching valve). As a result, the switching valve may be positioned at a lower height level than the steam drain inlet of the deaerator, and consequently, there may be an upward-rising section in the section between the switching valve and the deaerator inlet of the deaerator-side flow path.

[0005] In such a recovery system, when the destination of the steam condensate discharged from the heat exchanger is switched to the condensate tank (i.e., the deaerator-side flow path is switched to a closed state), the steam condensate accumulates in the riser section of the deaerator-side flow path. This accumulated steam condensate is then sent to the deaerator when the deaerator-side flow path is switched back to an open state. However, during accumulation in the riser section, the temperature of the accumulated steam condensate can drop to a temperature below which it can cause water hammer in the deaerator. In other words, conventional recovery systems still have a risk of water hammer occurring when low-temperature accumulated steam condensate is sent to the deaerator, and there was still room for improvement.

[0006] This invention has been made in view of the above-described circumstances, and aims to provide a steam drain recovery system that can suppress the occurrence of water hammer due to stagnant steam drain, and a waste treatment facility equipped therewith. [Means for solving the problem]

[0007] The steam drain recovery system according to the present invention, which achieves the above-mentioned objective, recovers steam drain discharged from a heat exchanger. A first channel through which steam drain discharged from the heat exchanger flows, The second and third channels branch off from the same branching point on the first channel, A degasser connected to the second flow path, A condensate tank connected to the third flow path at a level lower than the deaerator, It comprises at least a switching unit that switches the opening and closing of the second flow path, The switching section is characterized in that it is positioned at approximately the same level as the inlet of the deaerator that receives the steam drain flowing through the second flow path.

[0008] In the steam drain recovery system with the above configuration, there is no rising section in the section between the switching section and the inlet of the deaerator in the second flow path connected to the deaerator, due to the difference in level between the switching section and the inlet. Therefore, steam drain accumulated in the rising section does not enter the deaerator at a low temperature. In other words, with the above configuration, the occurrence of water hammer due to stagnant steam drain can be suppressed.

[0009] In the steam drain recovery system according to the present invention, the switching unit is preferably located near the inlet of the deaerator.

[0010] With the above configuration, the section between the switching section and the deaerator inlet can be made as short as possible, thereby preventing steam condensate from accumulating in that section. This further suppresses the occurrence of water hammer due to accumulating steam condensate.

[0011] In the steam drain recovery system according to the present invention, The second flow path is connected to the branching position and the inlet of the deaerator and has a lateral guide section that guides the steam drain laterally. The third flow path preferably has a downward-facing section connected to the branching position and guiding the steam drain downward, and a lateral-facing section connected to the downstream end of the downward-facing section and the condensate tank and guiding the steam drain laterally.

[0012] With the above configuration, since neither the second nor the third flow path has a rising section, the steam drain can be efficiently flowed to the deaerator and condensate tank. Furthermore, if the second flow path guides the steam drain laterally, the steam drain is less likely to accumulate, thus further suppressing the occurrence of water hammer caused by stagnant steam drain.

[0013] In the steam drain recovery system according to the present invention, The first flow path is connected to the heat exchanger and includes a rising section that guides the steam drain upward, It has a downward-facing section connected to the downstream end of the rising section, which guides the steam drain downward, The aforementioned branching point is preferably located in the aforementioned downward section.

[0014] If there are obstacles such as devices or structures between the heat exchanger installation area and the deaerator and condensate tank installation area, it may be difficult to extend the first flow path in a straight line to the deaerator and condensate tank installation area due to layout constraints imposed by these obstacles. Therefore, by configuring the first flow path to have rising and falling sections (i.e., in a torii gate shape), it is possible to extend the first flow path while avoiding obstacles, as described above, while suppressing the occurrence of water hammer due to stagnant steam drain.

[0015] In the steam drain recovery system according to the present invention, it is preferable that the inlet of the deaerator is positioned at a higher level than the steam drain outlet from which the steam drain of the heat exchanger is discharged.

[0016] According to the above configuration, it is possible to prevent the accumulation of condensed water from the steam drain in the second channel.

[0017] In the steam drain recovery system according to the present invention, it is preferable that the condensate tank is arranged such that the inlet for receiving the steam drain flowing through the third flow path is located at a lower level than the steam drain outlet from which the steam drain of the heat exchanger is discharged.

[0018] According to the above configuration, the steam drain discharged from the heat exchanger can be efficiently flowed to the condensate tank by utilizing its own weight.

[0019] In the steam drain recovery system according to the present invention, The switching unit is a second flow path switching unit constituted by an on-off valve disposed on the second flow path, It is preferable to further include a third flow path switching unit constituted by an on-off valve disposed on the third flow path.

[0020] Since the second flow path switching unit and the third flow path switching unit are constituted by separate on-off valves, the arrangement positions of the switching units on each flow path can be freely set. For example, by disposing the second flow path switching unit closer to the inlet of the deaerator, the section between the switching unit and the inlet of the deaerator can be shortened to avoid the steam drain staying in the section.

[0021] In the steam drain recovery system according to the present invention, it is preferable that the switching unit also switches the opening and closing of the third flow path and is constituted by a three-way valve disposed at the branching position.

[0022] According to the above configuration, it is possible to realize the opening and closing of the second flow path and the third flow path with a simpler configuration.

[0023] In the steam drain recovery system according to the present invention, it is preferable to further include a control unit that controls the switching unit based on the measurement result of a temperature sensor that measures the temperature of the steam drain flowing through the first flow path.

[0024] According to the above configuration, when the steam drain discharged from the heat exchanger and having a temperature below that which can cause a water hammer phenomenon in the deaerator is discharged, by switching the destination of the steam drain to the condensate tank, the occurrence of the water hammer phenomenon can be avoided.

[0025] The garbage treatment equipment according to the present invention for achieving the above object is Incinerators for burning waste, A waste heat boiler that generates steam using the waste heat from the incinerator, A combustion air preheater, which serves as a heat exchanger for exchanging heat between the steam generated in the waste heat boiler and the combustion air supplied to the incinerator, A steam drain recovery system according to claim 1 or 2, comprising: The water stored in the condensate tank is supplied to the deaerator via the flow path. The water deaerated in the deaerator is supplied to the waste heat boiler via a flow path.

[0026] By configuring the waste treatment facility as described above, the occurrence of water hammer can be avoided, as mentioned previously. [Brief explanation of the drawing]

[0027] [Figure 1] This figure shows the schematic configuration of the waste treatment facility according to the present invention. [Figure 2] This figure shows a schematic configuration of the first embodiment of a steam drain recovery system in a waste treatment facility. [Figure 3] This figure shows a schematic configuration of the first embodiment of the steam drain recovery system. [Figure 4] This figure shows a schematic configuration of a second embodiment of the steam drain recovery system. [Figure 5] This figure shows a schematic configuration of the first modified example of the third embodiment of the steam drain recovery system. [Figure 6] This figure shows a schematic configuration of a second modified example of the second embodiment of the steam drain recovery system. [Figure 7] This figure shows a schematic configuration of another example of a waste disposal facility. [Figure 8] This figure shows a schematic configuration of another example of a waste disposal facility. [Modes for carrying out the invention]

[0028] Hereinafter, embodiments of the steam drain recovery system and waste treatment equipment equipped therewith according to the present invention will be described with reference to the drawings. Note that the steam drain recovery system according to the present invention is applicable not only to waste treatment equipment but also to any equipment that needs to recover steam drain discharged from a heat exchanger into a boiler.

[0029] [Configuration of waste disposal facilities] As shown in Figure 1, the waste treatment facility 1 comprises a waste incinerator 10, a waste heat boiler 20, a dust collector 30, a chimney 40, a combustion air preheater 50, a turbine 60, and a steam drain recovery system 70.

[0030] In the waste incinerator 10, the waste that is fed in is incinerated, and the exhaust gas generated by the incineration is supplied from the waste incinerator to the waste heat boiler 20. In the waste heat boiler 20, the heat from the exhaust gas is used to heat water and generate steam. The generated steam is stored in a steam reservoir (not shown). Meanwhile, the exhaust gas that leaves the waste heat boiler 20 is passed through a dust collector 30, which consists of a bag filter and the like, to remove solid components such as dust and fine particles. The exhaust gas that leaves the dust collector 30 is released into the atmosphere through a chimney 40.

[0031] A portion of the steam stored in the steam reservoir is supplied to the combustion air preheater 50. In the combustion air preheater 50, heat exchange takes place between the steam and air from a blower (not shown), and the heated air, heated by the heat exchange with the steam, is blown into the waste incinerator 10 as air for waste combustion. Meanwhile, the steam condensate discharged from the combustion air preheater 50 is sent to the steam condensate recovery system 70 for recovery. The remaining steam stored in the steam reservoir is supplied to the turbine 60 that drives the generator. The steam that passes through the turbine 60 is cooled by a condenser (not shown) to become steam condensate, which is then sent to the steam condensate recovery system 70 for recovery.

[0032] [Configuration of the steam drain recovery system] <First Embodiment> As shown in Figure 2, in the first embodiment, the steam drain recovery system 70 includes a condensate tank 71, a deaerator 72, first to fourth flow paths 73 to 76, a switching unit 77, and a control device 78.

[0033] The condensate tank 71 stores steam drain supplied from the combustion air preheater 50 via the first flow path 73 and the third flow path 75, which will be described later, and steam drain supplied from the turbine 60 side via a flow path not shown. The condensate tank 71 is positioned such that the inlet 711 that receives steam drain from the combustion air preheater 50 is located at a lower level than the steam drain outlet 51 of the combustion air preheater 50. For example, the combustion air preheater 50 may be located at a height equivalent to the second floor of the waste treatment facility 1, while the condensate tank 71 may be located at a height equivalent to the first floor, but this is not limited to this. The steam drain from the turbine 60 side is supplied to the condensate tank 71 either via another condensate tank not shown or directly.

[0034] The deaerator 72 deaerates the steam drain supplied from the combustion air preheater 50 via the first channel 73 and the second channel 74, which will be described later, and the water supplied from the condensate tank 71 via the fourth channel 75. The deaerator 72 is positioned such that the inlet 721 that receives the steam drain from the combustion air preheater 50 is at a higher level than the steam drain outlet 51 of the combustion air preheater 50. For example, the deaerator 72 may be positioned at a height equivalent to the third or fourth floor of the waste treatment facility 1, while the combustion air preheater 50 is located at a height equivalent to the second floor and the condensate tank 71 is located at a height equivalent to the first floor. However, this is not limited to this. In this embodiment, a heating deaerator 72 that uses steam supplied from a steam reservoir to perform deaeration is employed, but it is not limited to this, and a chemical deaerator that uses chemicals to perform deaeration may also be employed. The water deaerated by the deaerator 72 is supplied to the waste heat boiler 20 as feedwater.

[0035] The first channel 73 is a channel through which steam drain discharged from the combustion air preheater 50 flows, and its upstream end is connected to the steam drain outlet (not shown) in the combustion air preheater 50. The first channel 73 is provided with a temperature sensor S for measuring the temperature of the steam drain, and the temperature measured by the temperature sensor S is transmitted as a signal to the control device 78. In this embodiment, the first channel 73 is configured to have only a lateral guide section 731 that guides the steam drain laterally, and therefore the downstream end of the first channel 73 is located at a level lower than the deaerator 72 and higher than the condensate tank 71.

[0036] From the same branching point B on the first channel 73 (the downstream end of the first channel 73 in this embodiment), the second channel 74 and the third channel 75 branch off and extend. The second channel 74 is a channel that sends steam drain from the first channel 73 to the deaerator 72. In this embodiment, the second channel 74 is configured to have a rising section 741 connected to the branching point B of the first channel 73 that guides the steam drain upward, and a lateral section 742 connected to the downstream end of the rising section 741 and the inlet 721 of the deaerator 72 that guides the steam drain laterally. However, the second channel 74 only needs to be able to send steam drain to the deaerator 72 and is not limited to the above configuration.

[0037] The third channel 75 is a channel that sends steam drain from the first channel 73 to the condensate tank 71. In this embodiment, the third channel 75 is connected to the branching position B of the first channel 73 and has a downward-facing section 751 that guides the steam drain downward, and a lateral-flow section 752 that is connected to the downstream end of the downward-facing section 751 and the inlet 711 of the condensate tank 71 and guides the steam drain laterally. Similarly, the third channel 75 only needs to be able to send steam drain to the condensate tank 71 and is not limited to the above configuration.

[0038] The fourth channel 76 is connected to the condensate tank 71 and the deaerator 72, and a pump P on the fourth channel 76 sends water from the condensate tank 71 to the deaerator 72 via the fourth channel 76. The fourth channel 76 only needs to be able to send water from the condensate tank 71 to the deaerator 72, and its specific configuration is not particularly limited.

[0039] The switching unit 77 and the control device 78 are for switching the destination of the steam drain discharged from the combustion air preheater 50 between the condensate tank 71 and the deaerator 72. In this embodiment, the steam drain recovery system 70 has a second flow path switching unit 77A as the switching unit 77, which switches the opening and closing of the second flow path 74, and a third flow path switching unit 77B that switches the opening and closing of the third flow path 75. The second flow path switching unit 77A is composed of an on-off valve (for example, a motor valve) positioned on the lateral section 742 of the second flow path 74 so as to be at approximately the same level as the inlet 721 of the deaerator 72. On the other hand, the third flow path switching unit 77B is composed of an on-off valve (for example, a motor valve) positioned at an arbitrary position on the third flow path 75 (downward section 751 in the figure). The control device 78 is connected to the second flow path switching unit 77A and the third flow path switching unit 77B, and controls its operation based on the measurement result of the temperature sensor S, as will be described below.

[0040] The amount of air supplied to the combustion air preheater 50 is automatically adjusted based on conditions such as the amount of waste to be incinerated and the temperature inside the furnace. For example, when starting up a furnace at a low internal temperature or when the amount of waste to be incinerated increases, the amount of air supplied to the combustion air preheater 50 is increased so that the amount of heated air blown into the furnace increases. On the other hand, when the internal temperature of the furnace rises to a temperature at which the self-combustion of waste is maintained or when the amount of waste to be incinerated decreases, less heated air is needed to be blown into the furnace, so the amount of air supplied to the combustion air preheater 50 is reduced. As a result, the temperature of the steam condensate formed by heat exchange with the air changes according to the amount of air.

[0041] Since high-temperature steam (for example, about 130°C to 140°C) is stored in the deaerator 72, if steam condensate below a predetermined temperature (for example, about 80°C) is supplied to the deaerator 72, the steam will cool and its volume will rapidly decrease, which can cause a water hammer phenomenon. Therefore, when the temperature of the steam condensate measured by the temperature sensor S on the first flow path 73 falls below 80°C while steam condensate is being supplied to the deaerator 72, the control device 78 controls the operation of the second flow path switching unit 77A and the third flow path switching unit 77B so that the second flow path 74 is closed and the third flow path 75 is open. As a result, the low-temperature steam condensate that may cause a water hammer phenomenon is sent to the condensate tank 71 via the first flow path 73 and the third flow path 75. On the other hand, if the temperature of the steam drain measured by the temperature sensor S exceeds 90°C while the steam drain is being supplied to the condensate tank 71, the control device 78 controls the operation of the second flow path switching unit 77A and the third flow path switching unit 77B so that the second flow path 74 opens and the third flow path 75 closes. As a result, the high-temperature steam drain, which is not likely to cause water hammer, is sent to the deaerator 72 via the first flow path 73 and the second flow path 74.

[0042] If the second flow path switching unit 77A is positioned at a lower level than the inlet 721 of the deaerator 72 (on the riser portion 741 of the second flow path 74 in this embodiment), a riser portion (in this embodiment, the portion of the riser portion 741 downstream of the second flow path switching unit 77A) exists in the section between the second flow path switching unit 77A and the inlet 721 due to the difference in level between the second flow path switching unit 77A and the inlet 721. When the destination of the steam drain discharged from the combustion air preheater 50 is switched to the condensate tank 71, high-temperature steam drain will accumulate in this riser portion. In this case, when the destination of the steam drain discharged from the combustion air preheater 50 is subsequently switched back to the deaerator 72, there is a problem that a water hammer phenomenon occurs when steam drain whose temperature has fallen below 80°C due to heat dissipation is sent to the deaerator 72.

[0043] In contrast, in this embodiment, where the second flow path switching section 77A is positioned at approximately the same level as the inlet 721 of the deaerator 72, there is no rising section caused by the difference in level between the second flow path switching section 77A and the inlet 721. Therefore, steam condensate is less likely to accumulate, and the occurrence of the water hammer phenomenon described above can be suppressed.

[0044] <Second Embodiment> The steam drain recovery system of this embodiment has a configuration that is generally the same as that of the first embodiment, except for the first flow path 73, the second flow path 74, and the third flow path 75, and a description of the same configuration will be omitted below.

[0045] In this embodiment, as shown in Figure 3, the first flow path 73 is configured to have, in addition to the horizontal section 731, a rising section 732 connected to the downstream end of the horizontal section 731 to guide the steam drain upward, a horizontal section 733 connected to the downstream end of the rising section 732 to guide the steam drain laterally, and a downward section 734 connected to the downstream end of the horizontal section 733 to guide the steam drain downward. The upstream end of the rising section 732 of the first flow path 73 extends to a level higher than the deaerator 72 (for example, a height equivalent to the 6th floor of the waste treatment facility 1), and the downstream end of the downward section 734 of the first flow path 73 extends to approximately the same level as the inlet 721 of the deaerator 72. In other words, the second flow path 74 and the third flow path 75 branch off and extend from branching position B, which is approximately the same level as the inlet 721 of the deaerator 72. Accordingly, the second flow path 74 is configured to have only a horizontal section 742 that guides the steam drain laterally. The first channel 73 may be configured to have a channel section that extends in an arc shape and opens downwards, instead of the lateral channel section 733. In this case, the rising section 732, the lateral channel section 733, and the descending section 734 of the first channel 73 form an inverted U-shaped channel.

[0046] In this embodiment, since the first flow path 73 is configured in a torii gate shape, if there is an obstacle between the area where the combustion air preheater 50 is located and the area where the condensate tank 71 and deaerator 72 are located, it is possible to extend the first flow path 73 while avoiding the obstacle. Furthermore, since the second flow path 74 is configured without a rising section, steam condensate is less likely to accumulate in the second flow path 74, and the occurrence of water hammer due to accumulated steam condensate can be further suppressed.

[0047] <Third Embodiment> The steam drain recovery system of this embodiment has a configuration that is substantially the same as that of the first embodiment, except for the deaerator 72 and the second flow path 74, and a description of the same configuration will be omitted below.

[0048] In this embodiment, as shown in Figure 4, the deaerator 72 is positioned such that its inlet 721 is located at approximately the same level as the combustion air preheater 50. Accordingly, the second flow path 74 is configured to have only a lateral channel 742 that guides the steam drain laterally.

[0049] In this embodiment as well, since steam condensate is less likely to accumulate in the second flow path 74, the occurrence of water hammer due to accumulated steam condensate can be further suppressed. Also, since the inlet 721 of the combustion air preheater 50 and the combustion air preheater 50 are located at approximately the same level, high-temperature steam condensate from the combustion air preheater 50 can be efficiently sent to the deaerator 72.

[0050] <First modified example of the second embodiment> The steam drain recovery system of this embodiment has a configuration that is generally the same as that of the second embodiment, except for the second flow path switching section 77A, and a description of the same configuration will be omitted below.

[0051] In this embodiment, as shown in Figure 5, the second flow path switching unit 77A is positioned in the second flow path 74 near the inlet 721 of the deaerator 72, specifically immediately before the inlet 721, and more specifically, at a position where the length of the section between the second flow path switching unit 77A and the inlet 721 is 2000 mm or less.

[0052] In this embodiment, the section between the second flow path switching section 77A and the inlet 721 of the deaerator 72 is shortened, so that steam condensate does not accumulate in this section, and as a result, the occurrence of water hammer due to accumulated steam condensate can be further suppressed. This modified example is not limited to the second embodiment, but can also be applied to the first embodiment shown in Figure 2 and the third embodiment shown in Figure 4.

[0053] <Second modified example of the second embodiment> The steam drain recovery system of this embodiment has a configuration that is generally the same as that of the second embodiment, except for the switching unit 77, and a description of the same configuration will be omitted below.

[0054] In this embodiment, as shown in Figure 6, the switching unit 77 switches the opening and closing of both the second flow path 74 and the third flow path 75, and is configured by a three-way valve (motor valve as an example) located at branch position B. This makes it possible to open and close the second flow path 74 and the third flow path 75 with a simpler configuration. Note that this modified example is not limited to the second embodiment, but can also be applied to the third embodiment shown in Figure 4.

[0055] [Other embodiments of waste disposal equipment] The waste treatment facility 1 in the embodiment shown in Figure 1 is configured to recover steam drain discharged from the combustion air preheater 50 using a steam drain recovery system 70. However, the waste treatment facility 1 according to the present invention is not limited to this. As an example, as shown in Figure 7, the waste treatment facility 1 may be equipped with a white smoke prevention air heater 80 as a heat exchanger that performs heat exchange using the heat of steam generated in the waste heat boiler 20.

[0056] In the white smoke prevention air heater 80, heat exchange takes place between air from a blower (not shown) and steam. The heated air, heated by the heat exchange with the steam, is mixed with the exhaust gas before it is released from the chimney 40. When the temperature of the exhaust gas released from the chimney 40 drops, the moisture contained in the exhaust gas condenses and becomes visible as white smoke. However, by mixing heated air with the exhaust gas before it is released from the chimney 40 to raise its temperature, the generation of white smoke can be prevented. The steam condensate formed by heat dissipation in the white smoke prevention air heater 80 is sent to the steam condensate recovery system 70 and recovered as described above.

[0057] As another example, as shown in Figure 8, the waste treatment facility 1 may be equipped with an exhaust gas recirculation heater 90 as a heat exchanger that uses the heat of steam generated in the waste heat boiler 20 to perform heat exchange. In the exhaust gas recirculation heater 90, heat exchange takes place between the exhaust gas that has left the dust collector 30 and the steam, and the heated exhaust gas heated by the heat exchange with the steam is blown into the waste incinerator 10. The blown-in of heated exhaust gas promotes the mixing of combustion gases in the furnace and forms a reducing atmosphere, thereby suppressing the generation of NOx. The steam drain formed by condensation due to heat dissipation in the exhaust gas recirculation heater 90 is sent to the steam drain recovery system 70 and recovered as described above.

[0058] Although not shown in the diagram, the waste treatment facility 1 may be configured to include at least two of the following: a combustion air preheater 50, a white smoke prevention air heater 80, and an exhaust gas recirculation heater 90. [Explanation of Symbols]

[0059] 1: Processing equipment 10: Incinerator 20: Waste heat boiler 30: Dust collector 40: Chimney 50: Combustion air preheater 51: Steam drain outlet 60: Turbine 70: Steam drain recovery system 71: Condensate tank 711: Inlet 72: Deaeration device 721: Inlet 73: First channel 731: Horizontal pull section 732: Standing section 733: Horizontal pull section 734: Downward slope 74:Second flow path 741: Standing section 742: Horizontal pull section 75: Third flow path 751: Downward slope 752: Horizontal pull section 76:Fourth channel 77: Switching section 77A: Second flow path switching section 77B: Third channel switching section 78: Control device 80: White smoke prevention air heater 90: Exhaust gas recirculation heater B: Branching point P: Pump S: Temperature sensor

Claims

1. A steam drain recovery system for recovering steam drain discharged from a heat exchanger, A first channel through which steam drain discharged from the heat exchanger flows, The second and third channels branch off from the same branching point on the first channel, A degasser connected to the second flow path, A condensate tank connected to the third flow path at a level lower than the deaerator, It comprises at least a switching unit that switches the opening and closing of the second flow path, The switching section is located at approximately the same level as the inlet of the deaerator that receives the steam drain flowing through the second flow path, in a steam drain recovery system.

2. The steam drain recovery system according to claim 1, wherein the switching unit is located near the inlet of the deaerator.

3. The second flow path is connected to the branching position and the inlet of the deaerator and has a lateral guide section that guides the steam drain laterally. The steam drain recovery system according to claim 1 or 2, wherein the third flow path has a downward-facing section connected to the branching position and guiding the steam drain downward, and a lateral-flow section connected to the downstream end of the downward-facing section and the condensate tank and guiding the steam drain laterally.

4. The first flow path is connected to the heat exchanger and includes a rising section that guides the steam drain upward, It has a downward-facing section connected to the downstream end of the rising section, which guides the steam drain downward, The steam drain recovery system according to claim 1 or 2, wherein the branching position is located in the downward section.

5. The steam drain recovery system according to claim 1 or 2, wherein the inlet of the deaerator is positioned at a higher level than the steam drain outlet from which the steam drain of the heat exchanger is discharged.

6. The steam drain recovery system according to claim 1 or 2, wherein the condensate tank is arranged such that the inlet for receiving steam drain flowing through the third flow path is located at a lower level than the steam drain outlet from which the steam drain of the heat exchanger is discharged.

7. The switching section is a second flow path switching section, which is composed of an on / off valve arranged on the second flow path. The steam drain recovery system according to claim 1 or 2, further comprising a third flow path switching section configured by an on / off valve arranged on the third flow path.

8. The steam drain recovery system according to claim 1 or 2, wherein the switching unit also switches the opening and closing of the third flow path and is composed of a three-way valve located at the branching position.

9. The steam drain recovery system according to claim 1 or 2, further comprising a control unit that controls the switching unit based on the measurement result of a temperature sensor that measures the temperature of the steam drain flowing through the first flow path.

10. Incinerators for burning waste, A waste heat boiler that generates steam using the waste heat from the incinerator, A combustion air preheater, which serves as a heat exchanger for exchanging heat between the steam generated in the waste heat boiler and the combustion air supplied to the incinerator, A steam drain recovery system according to claim 1 or 2, comprising: The water stored in the condensate tank is supplied to the deaerator via the flow path. A waste treatment facility in which water deaerated in the deaerator is supplied to the waste heat boiler via a flow path.

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