JP3455445B2 - Steam drain recovery system - Google Patents

Description

Detailed Description of the Invention

[0001]

This invention relates to cooling superheated steam and saturated steam with a combustion air preheater or other preheater,
The present invention relates to a steam drain recovery system configured to send liquefied high-temperature water to a deaerator through a drain flow path.

[0002]

2. Description of the Related Art A steam drain recovery system constructed as described above uses a high temperature superheated steam generated from waste heat in a refuse incinerator, or a high temperature superheated steam generated from a thermal power plant to generate high temperature water ( It is used when recovering steam drain).

[0003]

Taking a refuse incinerator as an example, a large refuse incinerator equipped with a power generation facility is provided with a cycle for generating superheated steam by waste heat of refuse and driving a steam turbine. It is equipped with a combustion air preheater or other air preheater for heating the air sent into the furnace using the heat of superheated steam, and liquefied high-temperature water (steam drain) cooled by this combustion air preheater, etc. ) Is also provided with a cycle to send to the deaerator. In addition, the amount of air sent into the furnace is automatically adjusted based on conditions such as the amount of dust to be incinerated and the temperature inside the furnace. For example, the amount of air sent is large. Temperature of the liquefied high-temperature water (steam drain) when cooled by the combustion air preheater becomes low, and the temperature of the liquefied high-temperature water cooled by the combustion air preheater when the amount of air sent in becomes small Becomes higher. However, since the deaerator stores high-temperature water and steam having a temperature of about 130 to 140 degrees Celsius, when the temperature of the supplied high-temperature water is lower than that of the high-temperature water stored in the deaerator. , This high-temperature water causes some vapor to be rapidly cooled and condensed in the deaerator, resulting in partial pressure change in the deaerator and vibration of the outer wall of the deaerator, a so-called water hammer phenomenon. Not only does this cause abnormal noise, but the pressure on the outer wall also causes fatigue in the outer wall, and there is room for improvement in terms of durability. It is known that this water hammer phenomenon remarkably appears when the temperature difference in the deaerator and the temperature difference of the high temperature water supplied exceeds about 50 degrees.

An object of the present invention is to rationally construct a vapor drain recovery system that minimizes pressure fluctuations in the deaerator even when the temperature of high-temperature water is not constant by being cooled by the combustion air preheater. In point.

[0005]

According to a first aspect of the invention (claim 1), the superheated steam and the saturated steam are cooled by a combustion air preheater or another preheater as described at the beginning, and this cooling is carried out. In a steam drain recovery system configured to send liquefied high-temperature water to a deaerator through a drain passage, a switching valve that guides the high-temperature water from the drain passage to a branch passage, and the branch flow A condensate tank is provided on the lower side of the channel, and a temperature sensor for measuring the water temperature of the high-temperature water sent to the drain channel is provided in the drain channel, and a temperature lower than a preset temperature preset by this temperature sensor is set. A control means for operating the switching valve is provided on the side for sending the high-temperature water in the drain passage to the condensate tank when measured, and the operation and effect are as follows.

A second feature of the present invention (claim 2) resides in that in claim 1, the set temperature is set within a range of 80 to 130 degrees Celsius, and the action and effect are as follows. It is as follows.

A third feature of the present invention (claim 3) is that in claim 1, a vibration sensor for detecting vibration of the wall surface of the container of the deaerator or a vibration sensor of the wall surface of the container of the condensate tank. In addition to providing at least one of the vibration sensors, when the vibration of the container wall is detected by the vibration sensor, the set temperature correction means for adjusting the set temperature is provided on the side where the number of vibrations per unit time decreases. And its action and effect are as follows.

A fourth aspect of the present invention (Claim 4) is, as described at the beginning, that superheated steam and saturated steam are cooled by a combustion air preheater or another preheater, and the liquefied high temperature water is cooled by this cooling. In a steam drain recovery system configured to be sent to a deaerator through a drain flow path, a switching valve that guides high-temperature water from the drain flow path to the branch flow path, and a recovery valve to the lower side of the branch flow path. A container provided with a water tank and at least one of a vibration sensor for detecting the vibration of the wall surface of the container of the deaerator and a vibration sensor for detecting the vibration of the wall surface of the container of the condensate tank When the vibration of the wall surface is detected, the switching valve is turned off so that the supply of high-temperature water to the container on the vibration detection side is cut off or reduced so that the number of vibrations per unit time is reduced, and this high-temperature water is sent to the other container. Located that it includes a control means for operating, its action and effects are as follows.

[Operation]

According to the first feature, when the temperature sensor measures that the temperature of the high temperature water sent to the drain passage is higher than the set temperature, the controller degass the high temperature water in the drain passage. The temperature sensor measures that the temperature of the high temperature water sent to the drain passage is lower than the set temperature as a result of being excessively cooled by the combustion air preheater. In this case, the control means performs the switching operation of the switching valve to send the high temperature water in the drain passage to the condensate tank from the branch passage and stop the supply of high temperature water to the deaerator. Become.

According to the second feature described above, 80 degrees Celsius to 1 degree Celsius.
When the high temperature side is set to 130 degrees Celsius as the set temperature set in the range of 30 degrees, the temperature is maintained at 130 degrees Celsius to 140 degrees Celsius during normal operation and compared with the temperature in the deaerator. Since the temperature is substantially the same as the temperature inside the deaerator, the water hammer phenomenon can be reliably avoided. or,
When the temperature is set to 80 degrees Celsius on the low temperature side, when the temperature in the deaerator is 140 degrees Celsius, the water temperature becomes a critical value that exceeds the temperature difference of about 50 degrees that causes the water hammer phenomenon. The temperature at which switching is performed in order to avoid the hammer phenomenon is reasonable and rational.

According to the third characteristic, for example, when vibration is detected by the vibration sensor provided on the wall surface of the container of the deaerator, the high temperature water in the drain passage is compared with the temperature in the deaerator. Since it can be determined that the temperature has dropped significantly and the water hammer phenomenon has occurred, the set temperature correction means changes the set temperature to the side where the number of vibrations per unit time decreases, specifically, to the side that raises the set temperature. As a result, an appropriate set temperature can be obtained according to the temperature change in the deaerator. Moreover, the temperature in the condensate tank is about 80 degrees Celsius, and when high temperature water exceeding 140 degrees Celsius is supplied to the condensate tank from the drain passage, the supplied high temperature water is condensed. It is known that the vapor once vaporized in the container of the tank is radiatively contracted and the pressure in a part of the container of the condensate tank is drastically reduced to cause a water hammer phenomenon. When vibration is detected by the vibration sensor provided on the container wall surface, it can be determined that the temperature of the high-temperature water in the drain passage is significantly higher than the temperature in the condensate tank.
As a result of changing the set temperature to the side where the number of vibrations per unit time is reduced by the set temperature correction means, more specifically, the side where the set temperature is lowered, the set temperature is adjusted to an appropriate set temperature according to the temperature change in the condensate tank. You will get it.

According to the fourth feature, for example, the initial state of the switching valve is set so as to send the high temperature water in the drain passage to the deaerator, and the vibration sensor is provided on the wall surface of the deaerator container. When the vibration sensor does not detect vibration, the high temperature water in the drain passage is maintained in the state of being sent to the deaerator, and when the vibration sensor detects the occurrence of vibration, a water hammer phenomenon occurs. Therefore, the control means switches the switching valve to send the whole amount or part of the high temperature water in the drain passage to the side of the condensate tank to stop the vibration of the deaerator. Similarly, the initial state of the switching valve is set so as to send the high temperature water in the drain passage to the condensate tank, and the vibration sensor is not detected with the vibration sensor provided on the wall surface of the container of the condensate tank. In this case, the high temperature water in the drain flow path is sent to the condensate tank, and when the vibration sensor detects the occurrence of vibration, it can be determined that the water hammer phenomenon is occurring, so the control means switches the switching valve. By switching and sending all or part of the high temperature water in the drain passage to the deaerator side, the vibration of the condensate tank is stopped.

[Effects of the Invention] Therefore, even if the temperature of the hot water in the drain passage is not maintained at a constant temperature by being cooled by the combustion air preheater, the flow of the hot water is controlled to control the inside of the deaerator. That is, the steam drain recovery system was rationally configured to reduce the pressure fluctuation and prevent the occurrence of the water hammer phenomenon and at the same time improve the durability of the deaerator (Claim 1). Further, by setting the range of the set temperature to a specific value, it becomes possible to perform control without difficulty (claim 2), and by providing a vibration sensor, the temperature inside the deaerator or the condensate tank The set temperature can be set to an appropriate value corresponding to the internal temperature to reduce the pressure fluctuations (claim 3). Furthermore, although the structure does not require a temperature sensor, a steam drain recovery system that reduces the pressure fluctuation in at least one of the deaerator and the condensate tank to prevent the occurrence of the water hammer phenomenon is rational. It is configured (Claim 4).

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an outline of a steam cycle using waste heat of a refuse incinerator. That is, the refuse incinerator performs a process of drying, incinerating, and ashing the dust introduced from the hopper 1 in the space 10 of the combustion furnace 2, and the exhaust gas generated in the combustion furnace 2 from the flue 3 to the bag filter. After being sent to the exhaust gas treatment device 4 having a white smoke prevention device or the like for purification, the exhaust gas is discharged from the chimney 5. Further, a soot blowing device 6, a waste heat boiler 7, a steam superheater 8 and a economizer 9 are arranged in this order from the side closer to the combustion furnace 2 in the flue 3, and the steam from the waste heat boiler 7 is used to generate electricity. Is configured to do.

That is, in the steam cycle for power generation using the waste heat of the combustion furnace 2, the steam generated in the waste heat boiler 7 is heated by the steam heater 8 and then guided to the high pressure steam reservoir 11, The steam from the steam sump 11 is sent to the steam turbine 13 that drives the generator 12, and the steam turbine 13
The expanded steam discharged from the tank is liquefied in the condenser 14 and sent to the open-air type condensate tank 15, and the water in the condensate tank 15 is sent to the deaerator 17 by the pump 16 and the deaerator 17 is discharged. After being deaerated by the vaporizer 17, it is sent by the pump 18 to the economizer 9 for heating and then returned to the waste heat boiler 7. The condenser 14 is provided with a vacuum condensate tank 20 for storing the condensed water, and the condensed water from the condensate tank 15 and the extraction steam from the high-pressure steam reservoir 11 and the exhaust of the steam turbine 13 are also provided. A steam extraction steam condenser 21 for exchanging heat with the steam after expansion from the side is provided, and the water condensed by the steam extraction steam condenser 21 is a vacuum condensation water tank 2
0, the extraction steam condenser 2 from the vacuum condenser tank 20
The condensate led to 1 is collected in the condensate tank 15 after heat exchange.

Further, as shown in the figure, the high pressure steam reservoir 11
, A degasifier 17 via a combustion air preheater 23 for heating the air from the blower 22 with the heat of the steam from the high-pressure steam reservoir 11,
Alternatively, a path leading to the condensate tank 15 (this path will be described later in detail), steam from the high-pressure steam reservoir 11 is guided to the low-pressure steam reservoir 25 via the pressure reducing valve 24, and further air sent to a greenhouse or the like. Via the heat exchanger 26 for raising the temperature, to the condensate tank 15, the path from the high-pressure steam reservoir 11 to the deaerator 17, and the steam from the high-pressure steam reservoir 11 via the pressure reducing valve 27. After the temperature is lowered by the heat exchanger 28 in the condensate tank 15, each path leading to the condensate tank 15 is formed.

Only the liquefied high temperature water (steam drain) cooled by the combustion air preheater 23 and liquefied by the drain trap 30 is sent to the drain passage 31, and this high temperature water is drained. The path is formed so as to be sent to the deaerator 17 via the switching valve 32 provided in 31. Further, the branch flow passage 33 is formed in a state of branching from the drain flow passage 31 via the switching valve 32,
The condensate tank 15 communicates with the lower side of the branch channel 33. In this steam cycle, the water temperature in the container of the deaerator 17 is maintained at about 130 to 140 degrees Celsius, and the water temperature in the container of the condensate tank 15 is about 80 degrees Celsius (100 degrees Celsius because it is open to the atmosphere. The temperature of the high-temperature water sent to the drain passage 31 changes depending on the amount of air sent to the combustion air preheater 23. The temperature is not constant. From this, for example, when high-temperature water having a temperature lower than 80 degrees Celsius is supplied to the deaerator 17, a part of the vapor in the container of the deaerator 17 is rapidly cooled by the supplied high-temperature water. Condensation causes the pressure in the container of the deaerator 17 to drop sharply in a short time, resulting in a so-called water hammer phenomenon. For the same reason as this, the condensate tank When high-temperature hot water having a temperature higher than 140 degrees Celsius is supplied to the drain passage 31 from the drain flow passage 31, the supplied high-temperature water once vaporized in the container of the condensate tank 15 dissipates heat and shrinks. As a result of abruptly lowering the pressure inside the water tank 15, the so-called water hammer phenomenon occurs. In order to eliminate this inconvenience, in this steam cycle system, control is performed to automatically switch the switching valve 32 based on the temperature of the high temperature water sent to the drain passage 31, and the container of the deaerator 17 and the condensate water are also controlled. A control system that corrects the control when a water hammer phenomenon occurs in the container of the tank 15 is provided, and the configuration and control operation will be described below.

As shown in FIG. 2, an electric actuator 34 such as an electric motor for switching the switching valve 32 is provided, and a temperature sensor for measuring the temperature of the high temperature water in the drain passage 31 on the upper side of the switching valve 32. 35, a first vibration sensor 36 that electrically detects vibration on the wall surface of the container of the deaerator 17, and a second vibration sensor 37 that electrically detects vibration on the wall surface of the container of the condensate tank 15 And a control device 38 as control means for controlling the electric actuator 34 of the switching valve based on signals from these sensors 35, 36, 37.

As shown in the flow chart of FIG. 3, the control mode of the control device 38 is set, and when the control device 38 starts control, the set temperature is set to 90 degrees Celsius and the switching valve 32 is set to the deaerator 17. After initializing to operate the electric actuator 34 so as to communicate with the side,
When the measured value of the temperature sensor 35 is input and the measured value is higher than the dead zone determined based on the set temperature, the switching valve 32 is connected to the deaerator 17 so that the electric actuator 34 Is controlled (if it is already in communication with the deaerator 17, that state is maintained), and if the measured value of the temperature sensor 35 is lower than the dead zone determined based on the set temperature, , The electric actuator 34 is controlled so that the switching valve 32 communicates with the condensate tank 15 (if it has already communicated with the condensate tank 15, the state is maintained) (#
101- # 106 steps). With this control, 80 degrees Celsius
Any value within the range of degrees to 130 degrees may be set as the initial value of the set temperature, and the width of the dead zone is the set temperature (90 degrees Celsius).
When the measured value of the temperature sensor 35 is higher than the dead zone temperature range, a predetermined width (a value at which the switching valve 32 is not frequently switched during control) is determined on the high temperature side and the low temperature side with reference to Since there is no risk of the water hammer phenomenon, the high temperature water from the drain passage 31 is supplied to the deaerator 17, and if the measured value of the temperature sensor 35 is lower than the dead zone temperature range, the water hammer Since a phenomenon may occur, the high temperature water from the drain passage 31 is supplied to the condensate tank 15.

Next, when it is detected that the container of the deaerator 17 is vibrating based on the signal from the first vibration sensor 36, the set temperature is changed to a higher value by a predetermined value, and the second temperature is changed.
When it is detected that the container of the condensate tank 15 is vibrating based on the signal from the vibration sensor 37, control is performed to change the set temperature to a value lower by a predetermined value, and until these controls are reset. It is repeated and continues (steps # 107 to # 111). With this control,
For example, when it is detected that vibration due to the water hammer phenomenon occurs in the container of the deaerator 17, the temperature of the supplied high-temperature water is relatively lower than the temperature in the deaerator 17. Since this is the cause, by performing the process of increasing the set temperature, the temperature of the high temperature water is determined to be low in step # 105 after this process, and the high temperature water is sent to the condensate tank 15 to eliminate the vibration. Similarly to this, condensate tank 1
When it is detected that vibration due to the water hammer phenomenon occurs in the container of No. 5, it is because the temperature of the supplied high temperature water is relatively high compared to the temperature in the condensate tank 15, By performing the process of lowering the set temperature,
After this process, the temperature of the hot water is determined to be high in step # 103, and the hot water is sent to the deaerator 17, so that the vibration is eliminated. Also, in this processing, # 107- #
The set temperature correction means is composed of 110 steps.

As described above, according to the present invention, the combustion air preheater 2 is used.
In addition to the conventional structure configured to send high-temperature water (steam drain) cooled in 3 to only the deaerator 17, a switching valve 32 is provided so that this high-temperature water can also be sent to the condensate tank 15. By providing the control device 38 for switching the switching valve 32 based on the comparison between the temperature of the high temperature water and the set temperature,
It is possible to automatically control the occurrence of a water hammer phenomenon in the container of the deaerator 17 in advance.
Furthermore, even if this automatic control is performed, for example, when the temperature inside the deaerator changes, the deaerator 17 and the condensate tank 1
When the water hammer phenomenon occurs in any one of No. 5, the set temperature is corrected to change the set temperature to an optimum value and the automatic control can be performed. In the present invention, the switching valve 35 can be operated based on only the measurement result of the temperature sensor 35 without using the vibration sensor, and the container of the deaerator 2 and the condensate tank can be configured. It is also possible to implement it by providing a vibration sensor only in any one of the 15 containers.

[Other Embodiments] The present invention can be configured as follows in addition to the above-described embodiments. In this another embodiment, the temperature sensor 35 is removed from the control configuration of the above-described embodiment to configure hardware (the hardware is not shown. Common reference numerals are attached), and the control mode is set as follows. That is, as shown in the flowchart of FIG. 4, when the control device 38 starts the control, the first vibration sensor is activated after the electric actuator 34 is initialized so that the switching valve 32 communicates with the deaerator 17. When it is detected that vibration is occurring in the container of the deaerator 17 based on the signal from 36, the electric actuator 34 is driven to make the switching valve 32 communicate with the condensate tank 15, and the second vibration sensor 37 When it is detected that the container of the condensate tank 15 is vibrating on the basis of the signal of # 1, the electric actuator 34 is driven to make the switching valve 32 communicate with the deaerator 17 (# 201 to # 201). # 206 step). That is, in this other embodiment, not only the temperature sensor used in the above-mentioned embodiment is not required, but also the flow path is switched after detecting the vibration, so that the selection of the flow path is correct. ing. Then, in this control, instead of the control operation of supplying the entire amount of high-temperature water to one side, the amount of high-temperature water supplied to the side where vibration is generated is reduced and the supply of high-temperature water to the other side is started. It is also possible to set and implement a control mode.

[Brief description of drawings]

FIG. 1 is a diagram showing a steam cycle of a refuse incinerator.

FIG. 2 is a block circuit diagram of a control system.

FIG. 3 is a flowchart of control operation

FIG. 4 is a flowchart of a control operation according to another embodiment.

[Explanation of symbols]

15 Condensate tank 17 Deaerator 23 Combustion air preheater 31 Drain flow path 32 switching valve 33 branch flow paths 35 Temperature sensor 36,37 Vibration sensor 38 Control means

─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Shinichi Segawa 1-247 Shikitsuhigashi, Naniwa-ku, Osaka City, Osaka Prefecture Kubota Co., Ltd. (56) Reference JP-A-4-334506 (JP, A) Actual Kaihei 4-92108 (JP, U) Actual Kaihei 3-30002 (JP, U) Actual Kai 63-5207 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) F22D 11 / 00

Claims (4)

(57) [Claims] 1. Superheated steam and saturated steam are cooled by a combustion air preheater (23) or another preheater, and high temperature water liquefied by this cooling is degassed (17) through a drain flow path (31). A steam drain recovery system configured to send the high temperature water from the drain channel (31) to the branch channel (3).
3), the switching valve (32) and the branch flow path (3)
3) A condensate tank (15) is provided on the lower side, and a temperature sensor (35) for measuring the temperature of high-temperature water sent to the drain passage (31) is provided in the drain passage (31),
When the temperature sensor (35) measures a temperature lower than a preset temperature, control for operating the switching valve (32) on the side of sending the high temperature water in the drain passage (31) to the condensate tank (15). A vapor drain recovery system comprising means (38). 2. The steam drain recovery system according to claim 1, wherein the set temperature is set within a range of 80 to 130 degrees Celsius. 3. A vibration sensor (36) for detecting vibration of the wall surface of the container of the deaerator (17) or a vibration sensor (3) for detecting vibration of the wall surface of the container of the condensate tank (15).
7. At least one of 7) is provided, and when the vibration sensor detects vibration of the container wall surface, a set temperature correction means for adjusting the set temperature is provided on the side where the number of vibrations per unit time decreases. 1. The steam drain recovery system described in 1. 4. The superheated steam and the saturated steam are cooled by a combustion air preheater (23) or another preheater, and the high temperature water liquefied by this cooling is deaerator (17) through a drain flow path (31). A steam drain recovery system configured to send the high temperature water from the drain channel (31) to the branch channel (3).
3), the switching valve (32) and the branch flow path (3)
3) A condensate tank (15) is provided on the lower side, and a vibration sensor (36) for detecting vibration of the wall surface of the container of the deaerator (17), or the wall surface of the container of the condensate tank (15). At least one of the vibration sensors (37) for detecting the vibration of the container is provided, and when the vibration sensor detects the vibration of the container wall surface, the high-temperature water for the container on the vibration detection side is reduced so that the number of vibrations per unit time is reduced. A vapor drain recovery system comprising control means (38) for operating the switching valve (32) to shut off or reduce the supply and send this hot water to the other vessel.