JP2000154905A - Steam drain recovering system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steam drain recovering system in which pressure fluctuation in a deaerator is suppressed even when the steam drain is cooled through a combustion air preheater and the temperature thereof is dropped significantly. SOLUTION: Superheated steam and saturated steam are cooled through a combustion air preheater 23 or other preheater to produce liquefied high temperature water which is fed through a drain channel 31 to a deaerator 17. High temperature water from the drain channel 31 is introduced through a branch channel 33 to a condensate tank 15 by means of a switching valve 32 and the temperature of the high temperature water being supplied to the drain channel 31 is measured by means of a temperature sensor 35. When the temperature sensor 35 measures a temperature lower than a preset temperature, a controller 38 operates the switching valve 32 to supply high temperature water from the drain channel 31 to the condensate tank 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for cooling superheated steam and saturated steam by a combustion air preheater or another preheater.
The present invention relates to a steam drain recovery system configured to send high-temperature water liquefied by the cooling to a deaerator through a drain passage.

[0002]

2. Description of the Related Art A steam drain recovery system configured as described above is used to convert high-temperature superheated steam generated by waste heat in a garbage incinerator or high-temperature superheated steam generated in a thermal power plant from high-temperature water ( This is used when collecting steam drain.

[0003]

Taking a garbage incinerator as an example, a large-sized garbage incinerator equipped with a power generation facility has a cycle for driving a steam turbine by generating superheated steam by waste heat of garbage. A combustion air preheater or another air preheater for heating the air sent into the furnace using the heat of the superheated steam is provided, and high-temperature water (steam drain) cooled and liquefied by the combustion air preheater or the like is provided. ) To the deaerator. In addition, the amount of air sent into the furnace is automatically adjusted based on conditions such as the amount of refuse to be incinerated and the temperature in the furnace. For example, the amount of air sent is increased. In this case, the temperature of the high-temperature water (steam drain) liquefied by cooling by the combustion air preheater decreases, and if the amount of air sent in decreases, the temperature of the high-temperature water liquefied by cooling by the combustion air preheater Will be higher. However, since the deaerator stores high-temperature water and steam at a temperature of about 130 to 140 degrees Celsius, if the temperature of the supplied high-temperature water is lower than the high-temperature water stored in the deaerator, This high-temperature water rapidly cools and condenses a part of the steam in the deaerator, and as a result, the pressure in the deaerator partially changes to vibrate the outer wall of the deaerator, a so-called water hammer phenomenon. In addition to generating abnormal noise, the outer wall is easily fatigued by a change in pressure applied to the outer wall, and there is room for improvement in durability. It is known that the water hammer phenomenon appears remarkably when the difference between the temperature in the deaerator and the temperature of the supplied high-temperature water exceeds approximately 50 degrees.

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

[0005]

According to a first aspect of the present invention, as described at the outset, superheated steam and saturated steam are cooled by a combustion air preheater or another preheater, and this cooling is performed. In a steam drain recovery system configured to send high-temperature water liquefied by the drain flow path to a deaerator, a switching valve that guides high-temperature water from the drain flow path to a branch flow path, and the branch flow A condensate tank is provided on the lower side of the road, and a temperature sensor for measuring the temperature of high-temperature water sent to the drain flow path is provided in the drain flow path, and a temperature lower than a preset temperature set in advance by the temperature sensor is provided. The control means for operating the switching valve is provided on the side of sending high-temperature water in the drain flow path to the condensate tank when the measurement is performed. 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. It is as follows.

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

A fourth feature of the present invention is that, as described at the outset, the superheated steam and the saturated steam are cooled by a combustion air preheater or another preheater, and the high-temperature water liquefied by the cooling is cooled. In a steam drain recovery system configured to be sent to a deaerator via a drain flow path, a switching valve that guides high-temperature water from the drain flow path to a branch flow path, and a return valve located downstream of the branch flow path. A water tank is provided, and at least one of a vibration sensor for detecting the vibration of the wall surface of the container of the deaerator and the vibration sensor for detecting the vibration of the wall surface of the container of the condensate tank is provided. When the vibration of the wall surface is detected, 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 the switching valve is sent to send the high-temperature water to the other container. Located that it includes a control means for operating, its action and effects are as follows.

[Action]

According to the first feature, when the temperature sensor measures that the high-temperature water sent to the drain flow path is higher than the set temperature, the control device removes the high-temperature water in the drain flow path from the deaerator. The switching valve is set to send to the drain, and conversely, 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 excessive cooling 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 flow path from the branch flow path to the condensate tank and stop the supply of the high-temperature water to the deaerator. Become.

[0011] According to the second feature, 80 degrees Celsius to 1 degree Celsius.
When the set temperature set in the range of 30 ° C. is set to 130 ° C. on the high temperature side, the temperature is compared with the temperature in the deaerator where the temperature is maintained at about 130 ° C. to 140 ° C. during normal operation. Since the temperature is substantially the same as the temperature in 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, the temperature difference in the deaerator at 140 degrees Celsius becomes a critical value exceeding approximately 50 degrees of the temperature difference that causes the water hammer phenomenon, so The temperature at which the switching is performed to avoid the hammer phenomenon is reasonable and reasonable.

According to the third feature, for example, when vibration is detected by a vibration sensor provided on the container wall of the deaerator, the temperature of the high-temperature water in the drain flow path 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 the side where the set temperature rises As a result, an appropriate set temperature is obtained in accordance with a temperature change in the deaerator. 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 flow path, the supplied high-temperature water is condensed. It is known that steam once vaporized in the tank vessel radiates heat and contracts, causing a sudden drop in the pressure in the condensate tank vessel to cause a water hammer phenomenon. When the vibration is detected by the vibration sensor provided on the container wall of the container, it can be determined that the temperature of the high-temperature water in the drain flow path has risen significantly compared to the temperature in the condensate tank.
As a result of the set temperature correcting means changing the set temperature to the side where the number of vibrations per unit time decreases, specifically, to the side where the set temperature is reduced, an appropriate set temperature is set in accordance with the temperature change in the condensate tank. Gain.

According to the fourth feature, for example, the initial state of the switching valve is set so that high-temperature water in the drain flow path is sent to the deaerator, and the vibration sensor is provided on the wall surface of the container of the deaerator. However, when vibration is not detected by the vibration sensor, the high temperature water in the drain flow path is maintained to be sent to the deaerator, and when vibration is detected by the vibration sensor, a water hammer phenomenon occurs. Therefore, the control means switches the switching valve to send all or a part of the high-temperature water in the drain passage to the condensate tank side, thereby stopping the vibration of the deaerator. Similarly, the initial state of the switching valve is set so that high-temperature water in the drain flow path is sent to the condensate tank, and the vibration sensor does not detect vibration 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 vibration is detected by the vibration sensor, it can be determined that a water hammer phenomenon has occurred. The vibration of the condensate tank is stopped by switching and sending all or a part of the high-temperature water in the drain flow path to the deaerator side.

[Effects of the Invention] Therefore, even when the temperature of the high-temperature water in the drain passage is not maintained at a constant temperature by being cooled by the combustion air preheater, the flow of the high-temperature water is controlled to control the flow in the deaerator. Thus, a steam drain recovery system capable of preventing the occurrence of the water hammer phenomenon by reducing the pressure fluctuation and improving the durability of the deaerator has been rationally configured (claim 1). Further, by setting the range of the set temperature to a specific value, reasonable control is enabled (claim 2). By providing a vibration sensor, the temperature in the deaerator or the condensate tank The pressure fluctuation can be reduced by setting the set temperature to an appropriate value corresponding to the temperature in the inside (claim 3). Furthermore, a steam drain recovery system that reduces the pressure fluctuation in at least one of the deaerator and the condensate tank and prevents the occurrence of the water hammer phenomenon despite the configuration that does not require a temperature sensor is reasonable. It is configured (claim 4).

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 schematically shows a steam cycle using waste heat of a garbage incinerator. That is, the refuse incinerator performs a process of drying, incineration, and incineration of the refuse input from the hopper 1 in the space 10 of the combustion furnace 2, and exhaust gas generated in the combustion furnace 2 from the flue 3 through a bag filter 3. After being sent to an exhaust gas treatment device 4 having a white smoke prevention device and the like for purification, the exhaust gas is discharged from a chimney 5. In the flue 3, 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 close to the combustion furnace 2, and power is generated by steam from the waste heat boiler 7. It is configured to do so.

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 sump 11. The steam from the steam sump 11 is sent to a steam turbine 13 that drives a generator 12, and the steam turbine 13
The expanded steam discharged from the tank is liquefied by a condenser 14 and sent to a condenser tank 15 which is open to the atmosphere. Further, the water in the condenser tank 15 is sent to a deaerator 17 by a pump 16, After being degassed by the gasifier 17, the gas is sent to the economizer 9 by the pump 18, heated, and then returned to the waste heat boiler 7. The condenser 14 has a vacuum condenser tank 20 for storing the condensed water, condensate from the condenser tank 15, extracts steam from the high-pressure steam reservoir 11, and exhausts the steam turbine 13. A steam extraction condenser 21 for exchanging heat with the steam after expansion from the side, and water condensed by the steam extraction condenser 21 is supplied to the vacuum condenser tank 2.
0, and the bleed steam condenser 2
The condensate led to 1 is recovered in the condensate tank 15 after heat exchange.

Further, as shown in FIG.
The deaerator 17 via a passage for guiding the steam from the soot blower 6 to the soot blowing device 6 and 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 in detail later), the vapor from the high-pressure vapor reservoir 11 is guided to the low-pressure vapor reservoir 25 via the pressure reducing valve 24, and further, air sent to a greenhouse or the like. A path leading to the condensate tank 15 via the heat exchanger 26 for raising the temperature, a path leading the steam from the high-pressure steam reservoir 11 to the deaerator 17, and a steam from the high-pressure steam reservoir 11 via the pressure reducing valve 27. After the temperature is reduced by the heat exchanger 28 in the condensate tank 15, respective paths leading to the condensate tank 15 are formed.

Only the high-temperature water (steam drain) cooled and liquefied by the combustion air preheater 23 is liquefied by the drain trap 30 and sent to the drain passage 31. The path is formed so as to be sent to the deaerator 17 via a switching valve 32 interposed in 31. Further, a branch flow path 33 is formed in a state of branching from the drain flow path 31 via the switching valve 32,
The condensate tank 15 communicates with the lower side of the branch flow path 33. In this steam cycle, the water temperature in the vessel of the deaerator 17 is maintained at about 130 to 140 degrees Celsius, and the water temperature in the vessel of the condensate recovery 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 flow path 31 varies depending on the amount of air sent to the combustion air preheater 23. The temperature is not constant. From this, for example, when low-temperature high-temperature water lower than 80 degrees Celsius is supplied to the deaerator 17, part of the steam in the container of the deaerator 17 is rapidly cooled by the supplied high-temperature water. As a result of condensation, the pressure in the container of the deaerator 17 rapidly drops in a short time, which causes a so-called water hammer phenomenon. When high-temperature water having a high temperature of more than 140 degrees Celsius is supplied from the drain passage 31 to the cooling water 15, the supplied high-temperature water is vaporized and shrunk in the vessel of the condensate tank 15 to radiate heat. As a result of abruptly reducing the pressure in the container of the water tank 15, a so-called water hammer phenomenon occurs. In order to solve this inconvenience, in this steam cycle system, control for automatically switching the switching valve 32 based on the temperature of the high-temperature water sent to the drain passage 31 is performed, and the container of the deaerator 17 and the condensate A control system for correcting the control when the water hammer phenomenon occurs in the container of the tank 15 is provided. The configuration and control operation will be described below.

As shown in FIG. 2, there is provided an electric actuator 34 such as an electric motor for switching the switching valve 32, and a temperature sensor for measuring the temperature of high-temperature water in the drent flow path 31 on the upper side of the switching valve 32. 35, a first vibration sensor 36 for electrically detecting vibration on the wall of the container of the deaerator 17, and a second vibration sensor 37 for electrically detecting vibration on the wall 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 flowchart of FIG. 3, the control mode of the control device 38 is set. When the control device 38 starts the control, the set temperature is set to 90 degrees Celsius, and the switching valve 32 is set to the deaerator 17 After performing initialization to operate the electric actuator 34 so as to communicate with the
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 electric actuator 34 connects the switching valve 32 to the deaerator 17. (If it is already in communication with the deaerator 17, the state is maintained). Further, when 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 the electric actuator 34 is already in communication with the condensate tank 15, the state is maintained) (#
101 to # 106 steps). In this control, 80 degrees Celsius
Any value in 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 set to the set temperature (90 degrees Celsius).
Is set to a predetermined width between the high temperature side and the low temperature side (a value such that the switching valve 32 is not frequently switched at the time of control), and the measured value of the temperature sensor 35 is higher than the temperature range of the dead zone. Supplies the high-temperature water from the drain passage 31 to the deaerator 17 because there is no risk of occurrence of the water hammer phenomenon, and when the measured value of the temperature sensor 35 is lower than the temperature range of the dead zone, Since a phenomenon may occur, high-temperature water from the drain passage 31 is supplied to the condensate tank 15.

Next, when it is detected that vibration has occurred in the container of the deaerator 17 based on a signal from the first vibration sensor 36, the set temperature is changed to a value higher by a predetermined value, and the second temperature is changed.
When it is detected that vibration has occurred in the container of the condensate tank 15 based on a signal from the vibration sensor 37, control is performed to change the set temperature to a lower value by a predetermined value, and until these controls are reset. The process is repeated and continued (steps # 107 to # 111). In this control,
For example, when it is detected that vibration due to the water hammer phenomenon occurs in the container of the deaerator 17, it is determined that the temperature of the supplied high-temperature water is relatively lower than the temperature of the deaerator 17. Since this is the cause, by performing the process of increasing the set temperature, after this process, the temperature of the high-temperature water is determined to be low in step # 105 and sent to the condensate tank 15, so that the vibration is eliminated. Similarly, the condensate tank 1
When it is detected that the vibration due to the water hammer phenomenon occurs in the container 5, 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 processing, the temperature of the high-temperature water is determined to be high in step # 103, and is sent to the deaerator 17, so that the vibration is eliminated. In this processing, # 107 to # 107
The set temperature correction means is constituted by 110 steps.

As described above, in the present invention, the combustion air preheater 2
In addition to the conventional configuration in which high-temperature water (steam drain) cooled in 3 is sent only to the deaerator 17, a switching valve 32 is provided so that the high-temperature water can also be sent to the condensate tank 15. By providing a control device 38 for switching the switching valve 32 based on a comparison between the temperature of the high-temperature water and the set temperature,
This enables automatic control to avoid the occurrence of the 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 in the deaerator changes, the deaerator 17 and the condensate tank 1
5, when the water hammer phenomenon occurs, the set temperature is corrected to change the set temperature to an optimum value, thereby enabling automatic control. According to the present invention, the switching valve 35 can be operated based only on the measurement result of the temperature sensor 35 without using the vibration sensor, and the container of the deaerator 2 and the condensate tank It is also possible to provide a vibration sensor in only one of the 15 containers.

[Other Embodiments] The present invention can be configured as follows in addition to the above-described embodiment. In this alternative embodiment, hardware is configured by removing the temperature sensor 35 from the control configuration of the above-described embodiment (the hardware is not shown. Common control symbols are assigned), 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, after performing the initialization for operating the electric actuator 34 so as to connect the switching valve 32 to the side of the deaerator 17, the first vibration sensor When it is detected that vibration has occurred 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. When the vibration of the container of the condensate tank 15 is detected on the basis of the signal of the above, the electric actuator 34 is driven to connect the switching valve 32 to the deaerator 17 (# 201 to # 201). # 206 step). That is, in this alternative embodiment, not only the temperature sensor used in the above embodiment is not required, but also the flow path is switched after detecting the vibration, so that there is no mistake in selecting the flow path. ing. In this control, instead of the control operation of supplying the entire amount of the high-temperature water to one side, the supply amount of the high-temperature water to the side where the vibration is generated is reduced, and the supply of the high-temperature water to the other side is started. It is also possible to set and implement a control mode.

[Brief description of the drawings]

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

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

FIG. 3 is a flowchart of a 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 path 35 Temperature sensor 36, 37 Vibration sensor 38 Control means

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yukinori Hirai 2-47, Shikitsu Higashi 1-chome, Naniwa-ku, Osaka-shi, Osaka (72) Inventor Shinichi Segawa Higashi-ichi Shikitsu, Naniwa-ku, Osaka, Osaka No. 2-47 Kubota Corporation

Claims (4)

[Claims] A superheated steam and a saturated steam are cooled by a combustion air preheater (23) or another preheater, and the high-temperature water liquefied by the cooling is removed via a drain passage (31) to a deaerator (17). Steam recovery system configured to send high-temperature water from the drain flow path (31) to the branch flow path (3).
A switching valve (32) leading to 3) 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 flow path (31) is provided in the drain flow path (31);
When the temperature measured by the temperature sensor (35) is lower than a preset temperature, the control valve (32) is operated to send high-temperature water in the drain flow path (31) to the condensate tank (15). A steam drain recovery system comprising means (38). 2. The steam drain recovery system according to claim 1, wherein the set temperature is set in a range of 80 to 130 degrees Celsius. 3. A vibration sensor (36) for detecting vibration of a wall surface of a container of the deaerator (17), or a vibration sensor (3) for detecting vibration of a wall surface of a container of the condensate tank (15).
And a set temperature correcting means for adjusting the set temperature on the side where the number of vibrations per unit time is reduced when the vibration sensor detects vibration of the container wall surface. 2. The steam drain recovery system according to 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 the cooling is degassed through a drain passage (31). Steam recovery system configured to send high-temperature water from the drain flow path (31) to the branch flow path (3).
A switching valve (32) leading to 3) 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 a wall surface of the container of the deaerator (17), or a wall surface of the container of the condensate tank (15) At least one of a vibration sensor (37) for detecting the vibration of the container, and when the vibration sensor detects the vibration of the container wall surface, the high-temperature water is supplied to the container on the vibration detection side so that the number of vibrations per unit time is reduced. A steam drain recovery system comprising control means (38) for shutting off or reducing the supply and operating said switching valve (32) to send this hot water to the other vessel.