JP7382811B2 - Heat exchanger - Google Patents

Description

The present disclosure relates to heat exchangers.

Patent Document 1 discloses a heat exchanger configured to heat LNG, which is a fluid to be heated, by heat exchange with steam. In order to bring the LNG temperature closer to the target temperature, the heat exchanger adjusts the liquid level (liquid level height) of the condensed water in the heat exchanger based on the deviation between the steam pressure in the heat exchanger and the set value. configured to control.

Japanese Patent Application Publication No. 9-143484

By the way, for example, when the temperature of the heated fluid is lower than a set value and it is necessary to promote heat exchange between the steam and the heated fluid, control is performed to increase the steam pressure and lower the liquid level. Generally, the response speed of steam pressure is much faster than the response speed of liquid level to fluctuations in the temperature of the heated fluid to be controlled. Therefore, after the steam pressure reaches the target value, the liquid level reaches the target value with a delay.

When the steam pressure reaches the target value, sufficient heat exchange is performed between the steam and the fluid to be heated, so that by the time the liquid level reaches the target value, the heat exchange becomes excessive. Therefore, the temperature of the heated fluid ends up exceeding the target value. In this case, control is performed to lower the steam pressure and raise the liquid level, but after the steam pressure reaches the target value, the liquid level reaches the target value with a delay. Since heat exchange between the steam and the fluid to be heated is suppressed when the steam pressure reaches the target value, the heat exchange becomes insufficient by the time the liquid level reaches the target value. Therefore, the temperature of the heated fluid falls below the target value. That is, hunting may occur in the temperature of the heated fluid to be controlled.

Therefore, the present disclosure describes a heat exchanger that can stably control the temperature of a heated fluid.

Example 1. A heat exchanger according to one example of the present disclosure includes a main body container, a supply section configured to supply steam to the main body container, and a level configured to be able to adjust the liquid level of a liquid in the main body container. An adjustment section, a heat transfer tube that is arranged vertically across the main container and configured to allow the fluid to be heated to flow therethrough, and measures the pressure inside the main container. a pressure measuring section configured to measure the temperature of the heated fluid flowing downstream of the main container of the heat transfer tube, and a temperature measuring section configured to measure the temperature of the heated fluid flowing downstream of the main container, and the liquid level of the liquid in the main container. The device includes a level measurement section configured to measure a level, and a control section. The control unit is configured to set a target pressure, which is a target value of the pressure inside the main container, based on the output of the temperature measurement unit, and to control the supply unit so that the pressure measured by the pressure measurement unit approaches the target pressure. and setting a target level, which is a target value of the liquid level in the main container, based on a comparison between the output of the temperature measuring part and a predetermined threshold value, and controlling the liquid level measured by the level measuring part. Controlling the level adjustment unit so that the level approaches the target level, and changing the target level until a predetermined time elapses when the level adjustment unit is controlled to change the liquid level in the main container. is configured to prohibit and execute.

In this case, the pressure within the main body container is continuously controlled to follow the target pressure set based on the output of the temperature measuring section. On the other hand, the liquid level in the main container is controlled to follow the target level that is set based on the comparison between the output of the temperature measurement section and a predetermined threshold. As a result of the comparison, the liquid level will not change unless the target level is changed. Moreover, when the target level is changed, the target level is not changed again until a predetermined period of time has passed. That is, since the liquid level is changed stepwise under certain conditions, hunting is less likely to occur in the temperature of the heated fluid to be controlled. Therefore, the temperature of the heated fluid is controlled to a predetermined target temperature by controlling the pressure in the main container, which has a relatively fast response speed, and by controlling the liquid level in the main container, which has a relatively slow response speed. It becomes possible to stably control the temperature of the fluid to be heated.

Example 2. In the heat exchanger of Example 1, setting the target level includes setting the target level to a larger value when the output of the temperature measuring section is below a predetermined lower limit value, and controlling the level adjusting section. This may include supplying the liquid into the main container so that the liquid level measured by the level measuring section approaches a target level. If the output of the temperature measurement section is below a predetermined lower limit value, even though the temperature of the heated fluid is higher than the target temperature, the temperature of the heated fluid may be lowered sufficiently by controlling the pressure inside the main container. This means that it has not been completed. Therefore, by setting the target level to a larger value and increasing the liquid level, the surface area of the heat exchanger tube in contact with the steam in the main container becomes smaller. Therefore, it becomes difficult for heat exchange to occur between the steam and the fluid to be heated, so it is possible to effectively lower the temperature of the fluid to be heated.

Example 3. In the heat exchanger of Example 2, the fact that the output of the temperature measuring section is below the predetermined lower limit value may include that the output of the temperature measuring section is continuously below the predetermined lower limit value for a predetermined period of time. In this case, the target level will not be changed in a situation where the output of the temperature measurement section suddenly becomes low for a short period of time. Therefore, it becomes possible to control the temperature of the heated fluid more stably.

Example 4. In any of the heat exchangers of Examples 1 to 3, setting the target level includes setting the target level to a smaller value when the output of the temperature measurement unit exceeds a predetermined upper limit value, Controlling the level adjustment section may include discharging the liquid from within the main container so that the liquid level measured by the level measurement section approaches a target level. If the output of the temperature measurement unit exceeds a predetermined upper limit, even though the temperature of the heated fluid is lower than the target temperature, it is possible to raise the temperature of the heated fluid sufficiently by controlling the pressure inside the main container. This means that it has not been completed. Therefore, by setting the target level to a smaller value and lowering the liquid level, the surface area of the heat exchanger tube that comes into contact with the steam in the main container increases. Therefore, heat exchange easily occurs between the steam and the fluid to be heated, so that the temperature of the fluid to be heated can be effectively raised.

Example 5. In the heat exchanger of Example 4, the fact that the output of the temperature measuring section exceeds the predetermined upper limit may include that the output of the temperature measuring section exceeds the predetermined upper limit for a predetermined period of time. In this case, the target level will not be changed in a situation where the output of the temperature measurement section suddenly increases for a short period of time. Therefore, it becomes possible to control the temperature of the heated fluid more stably.

Example 6. In any of the heat exchangers of Examples 1 to 5, setting the target level may include setting the target level only if the control unit is allowed to change the setting of the target level. good. In this case, for example, it becomes possible to cope with a situation where the liquid level is manually controlled based on the operator's judgment.

Example 7. In any of the heat exchangers of Examples 1 to 6, the control unit controls the supply unit and It may be further configured to stop the level adjustment section. If the output of the temperature measurement section is below a predetermined minimum value, the temperature of the heated fluid can be lowered sufficiently by controlling the pressure inside the main container, even though the temperature of the heated fluid is higher than the target temperature. It means not being able to do that. Moreover, since the target level is set to a predetermined maximum value, it is not possible to increase the liquid level to suppress heat exchange between the fluid to be heated and the steam. Therefore, by stopping the supply section and the level adjustment section, heat exchange between the heated fluid and the steam in the heat exchanger is also stopped. That is, if the fluid to be heated is sufficiently heated before entering the heat exchanger, the heat exchanger enters the standby state. Therefore, unnecessary heat exchange between the heat exchanger and the fluid to be heated can be suppressed.

Example 8. In the heat exchanger of Example 7, the fact that the output of the temperature measurement section is equal to or less than the predetermined minimum value may include that the output of the temperature measurement section remains equal to or less than the predetermined minimum value for a predetermined period of time. In this case, in a situation where the output of the temperature measurement section suddenly becomes low for a short period of time, the heat exchanger does not shift to the standby state. Therefore, it becomes possible to control the temperature of the heated fluid more stably.

Example 9. In the heat exchanger of Example 7 or Example 8, the supply section and the level adjustment section may be stopped only when automatic control of the supply section and the level adjustment section by the control section is permitted. It may include stopping. In this case, for example, it is possible to manually put the heat exchanger on standby based on the operator's judgment, or to cope with situations where it is not desirable to put the heat exchanger on standby.

Example 10. In any of the heat exchangers of Examples 7 to 9, the control section controls the supply section and the level adjustment section when the supply section and the level adjustment section are stopped and the output of the temperature measurement section exceeds a predetermined starting value. It may be configured to further change the setting to allow automatic control of the adjustment unit. When the heat exchanger is in a standby state, if the output of the temperature measuring section exceeds a predetermined activation value, it means that the temperature of the heated fluid has become lower than the target temperature. Therefore, by restarting the automatic control of the supply section and the level adjustment section that were stopped in the standby state, heat exchange can be performed between the heat exchanger and the heated fluid. Therefore, it is possible to automatically start the heat exchanger based on the comparison between the output of the temperature measuring section and the predetermined starting value.

Example 11. In the heat exchanger of Example 10, the fact that the output of the temperature measuring section exceeds the predetermined starting value may include that the output of the temperature measuring section continues to exceed the predetermined starting value for a predetermined period of time. In this case, activation of the heat exchanger is avoided in a situation where the output of the temperature measurement section suddenly exceeds the activation value for a short period of time. Therefore, it is possible to prevent the activation of the heat exchanger and the transition to the standby state from being repeated in a short period of time.

Example 12. The heat exchanger according to any one of Examples 1 to 11 further includes an air supply section configured to supply air into the main container, and the control section is configured to supply air into the main container when the activation signal is input. controlling the air supply to introduce air into the body; and subsequent to controlling the air supply, controlling the supply to supply steam into the main vessel; may have been done. In this case, when the heat exchanger is started up, air is supplied to the main vessel, and then steam is supplied to the main vessel. Therefore, since the steam is mixed with air within the main body container, even if the steam is supplied into the main body container which has been cooled due to the stoppage of the heat exchanger, the steam is difficult to condense rapidly. Therefore, it is possible to suppress the occurrence of water hammer.

Example 13. In the heat exchanger of Example 12, controlling the air supply unit means supplying air so as to introduce air into the main body container when the temperature of the heated fluid measured by the temperature measurement unit is lower than a predetermined temperature. It may also include controlling the parts. When the temperature of the heated fluid measured by the temperature measuring section is lower than the predetermined temperature, it is estimated that the temperature of the liquid in the main body container in the heat exchanger immediately before startup is also at a similar low temperature. Therefore, in such a case, by supplying air into the main body container before steam, it is possible to effectively suppress the occurrence of water hammer.

Example 14. In the heat exchanger of Example 12 or Example 13, the control unit further controls the level adjustment unit to discharge at least a portion of the liquid in the main body container from the main body container when the activation signal is input. may be configured to execute. In this case, since the liquid that causes water hammer is discharged from the main container, it is possible to more effectively suppress the occurrence of water hammer.

Example 15. The heat exchanger of any of Examples 12 to 14 allows exhaust from the main container until the main container is filled with steam, and allows exhaust from the main container when the main container is filled with steam. It may further include an exhaust section configured to stop. In this case, when steam is supplied into the main container to which air is supplied, a mixed gas of steam and air is initially exhausted from the main container via the exhaust section. Thereafter, when more steam is supplied into the main body container, the replacement of air with steam progresses, the inside of the main body container is filled with steam, and exhaustion from the main body container is stopped. Therefore, it becomes possible to automatically stop the exhaust from the main body container by the exhaust section.

Example 16. In the heat exchanger of any of Examples 12 to 15, the air supply section may include a supply section configured to supply air or steam from the boiler into the main vessel. When the boiler is in operation, steam generated by the boiler is supplied into the main container by the supply section. On the other hand, immediately after the boiler is started together with the heat exchanger, steam is not generated in the boiler, so air in the boiler is supplied into the main body container by the supply section. That is, it becomes possible to supply air and steam into the main container, respectively, using one supply section.

According to the heat exchanger according to the present disclosure, it is possible to stably control the temperature of the heated fluid.

FIG. 1 is a schematic diagram showing an example of a hot water supply system. FIG. 2 is a block diagram showing the heat exchanger. FIG. 3 is a schematic diagram showing the hardware configuration of the controller. FIG. 4 is a flowchart for explaining liquid level increase control. FIG. 5 is a flowchart for explaining liquid level lowering control. FIG. 6 is a flowchart for explaining standby control. FIG. 7 is a flowchart for explaining control for returning from a standby state. FIG. 8 is a flowchart for explaining water hammer prevention control.

An example of an embodiment according to the present disclosure will be described in more detail below with reference to the drawings. In the following description, the same elements or elements having the same function will be denoted by the same reference numerals, and redundant description will be omitted.

[Configuration of hot water supply system]
The configuration of the hot water supply system 1 will be described with reference to FIGS. 1 to 3. The hot water supply system 1 is configured to generate electricity, recover exhaust heat generated by the electricity generation, and generate high-temperature water using the recovered heat. The hot water supply system 1 includes a boiler 2, customer facilities 3, and a heat exchanger 10, as shown in FIG.

The boiler 2 may be, for example, a cogeneration system using a gas turbine power generation system and/or a gas engine power generation system. Steam generated during the process of power generation in the boiler 2 is supplied to the heat exchanger 10.

The customer facility 3 is configured to supply water or low-temperature water (heated fluid) to the heat exchanger 10 and to supply hot water with high-temperature water generated by heat exchange with steam. The consumer facility 3 includes heat exchanger tubes 3a configured to allow water to flow therethrough. When water or low-temperature water is introduced into the upper part of the main body container 11 (described later) through the heat transfer tube 3a, it exchanges heat with the steam in the main body container 11 in the process of flowing downward and becomes high-temperature water. It is discharged from the bottom towards the customer facility 3.

The heat exchanger 10 includes a main body container 11, a tank 12 (level adjustment section), a pump 13 (level adjustment section), a thermometer 14 (temperature measurement section), a pressure gauge 15 (pressure measurement section), and a water level control section. It includes a total of 16 (level measuring section), pipes D1 to D5, valves V1 to V4, and a controller Ctr (control section).

The main body container 11 is configured such that steam or air can be introduced from the boiler 2 through a pipe D1 (supply section, air supply section). The main body container 11 may be configured to be able to store condensed water obtained by condensing steam introduced from the boiler 2. A heat transfer tube 3a is attached to the main body container 11 so as to penetrate through the main body container 11. The portion of the heat exchanger tube 3a that penetrates inside the main container 11 may vertically traverse the inside of the main container 11.

The tank 12 is configured to be able to temporarily store condensed water discharged from the main body container 11 through the pipe D2 (level adjustment section). The pump 13 operates based on a control signal from the controller Ctr, and is configured to supply condensed water in the tank 12 to the main container 11 through a pipe D3 (level adjustment section).

The thermometer 14 is configured to measure the temperature of high-temperature water flowing downstream of the main body container 11 in the heat transfer tube 3a. The thermometer 14 is configured to transmit measured temperature data to the controller Ctr.

The pressure gauge 15 is configured to measure the pressure inside the main container 11. The pressure gauge 15 is configured to transmit measured pressure data to the controller Ctr.

The water level gauge 16 is configured to measure the liquid level of condensed water in the main body container 11 (height from the bottom wall of the main body container 11 to the liquid level of the condensed water). The water level gauge 16 is configured to transmit measured water level data to the controller Ctr.

Piping D1 connects between boiler 2 and main container 11. A valve V1 (supply section, air supply section) configured to be openable and closable based on an operation signal from the controller Ctr is provided in the middle of the pipe D1. When the boiler 2 is in operation, the pipe D1 is configured to supply steam generated in the boiler 2 to the main container 11 in response to opening and closing of the valve V1. When the boiler 2 is stopped or started, the pipe D1 is configured to supply air within the boiler 2 to the main container 11 in response to opening and closing of the valve V1.

When the supply amount of steam increases and the pressure inside the main body container 11 becomes high, the steam temperature becomes high, so that heat exchange between the steam and the water flowing through the heat exchanger tubes 3a is promoted. On the other hand, when the supply amount of steam decreases and the pressure inside the main body container 11 becomes low, the steam temperature decreases, so that heat exchange between the steam and the water flowing through the heat exchanger tubes 3a is suppressed. That is, by controlling the opening degree of the valve V1 by the controller Ctr, the temperature of the obtained high temperature water can be controlled.

Piping D2 connects main container 11 and tank 12. A valve V2 (level adjustment section) whose opening degree can be changed based on an operation signal from the controller Ctr is provided in the middle of the pipe D2. The pipe D2 is configured to store condensed water in the main body container 11 or to supply condensed water in the main body container 11 to the tank 12, depending on the opening degree of the valve V2.

When the condensed water in the main container 11 is discharged into the tank 12 by partially or completely opening the valve V2, the liquid level in the main container 11 decreases. Therefore, the area exposed from the condensed water among the heat exchanger tubes 3a vertically traversing the inside of the main body container 11 increases, so that heat exchange between the steam and the water flowing through the heat exchanger tubes 3a is promoted. Note that "partial opening of the valve V2" herein includes a state in which the opening degree of the valve V2 is gradually increasing in the process of the valve V2 transitioning from the closed state to the open state.

When the condensed water in the main container 11 is stored in the tank 12 by partially or completely closing the valve V2, the liquid level in the main container 11 rises. Therefore, the area of the heat exchanger tubes 3a vertically extending inside the main body container 11 that is exposed from the condensed water is reduced, so that heat exchange between the steam and the water flowing through the heat exchanger tubes 3a is suppressed. Note that "partial closure of valve V2" herein includes a state in which the degree of opening of valve V2 is gradually decreasing in the process of transition of valve V2 from an open state to a closed state.

Piping D3 connects between tank 12 and main container 11. Piping D3 may be configured to supply condensed water in tank 12 to main body container 11 according to the operation of pump 13. In this case, when the condensed water in the tank 12 is supplied to the main container 11 by the operation of the pump 13, the liquid level in the main container 11 rises. Therefore, the area of the heat exchanger tubes 3a vertically extending inside the main body container 11 that is exposed from the condensed water is reduced, so that heat exchange between the steam and the water flowing through the heat exchanger tubes 3a is suppressed.

In this way, the controller Ctr controls the opening degree of the valve V2 and the operation of the pump 13, thereby controlling the temperature of the obtained high temperature water.

The upstream end of the pipe D4 may be connected to the tank 12. The downstream end of the pipe D4 may be connected to, for example, drainage equipment. A valve V3 configured to be openable and closable based on an operation signal from the controller Ctr may be provided in the middle of the pipe D4. Piping D4 may be configured to discharge condensed water in tank 12 to the outside of heat exchanger 10 in response to opening and closing of valve V3.

The upstream end of the pipe D5 (exhaust section) is connected to the main body container 11. The downstream end of the pipe D5 is open to the outside of the heat exchanger 10, for example. A valve V4 (exhaust part) is provided in the middle of the pipe D5. Piping D5 is configured to discharge gas (steam, air, etc.) inside main container 11 to the outside of main container 11 in response to opening and closing of valve V4. The valve V4 is configured to allow exhaust from the main container 11 until the main container 11 is filled with steam, and to stop the exhaust from the main container 11 when the main container 11 is filled with steam. You can leave it there. The valve V4 may be a valve that automatically opens and closes depending on the temperature difference between steam and air, for example. The valve V4 may be, for example, a bimetal steam air vent or a balanced pressure steam air vent.

As shown in FIG. 2, the controller Ctr includes, as functional modules, a temperature control section M1 (temperature measurement section), a pressure control section M2 (pressure measurement section), a water level control section M3 (level measurement section), and a stop control section M1 (temperature measurement section). It includes a control section M4 and a startup control section M5. These functional modules merely divide the functions of the controller Ctr into a plurality of modules for convenience, and do not necessarily mean that the hardware constituting the controller Ctr is divided into such modules. Each functional module is not limited to being realized by executing a program, but may be realized by a dedicated electric circuit (for example, a logic circuit) or an integrated circuit (ASIC: application specific integrated circuit) that integrates the same. It's okay.

The temperature control section M1 performs calculation based on the difference εT between the temperature T of the high temperature water measured by the thermometer 14 and the target temperature T0 of the high temperature water, and sends the result to the pressure control section M2 and the water level control section M3. is configured to print. For example, the temperature control unit M1 may be configured to perform a PID calculation based on the difference εT and output the result. The value output by the temperature control section M1 may be, for example, any value between 0% and 100%.

The pressure control section M2 is configured to set a target pressure P0, which is a target value of the pressure within the main body container 11, based on the output uT from the temperature control section M1. The pressure control unit M2 may be configured to, for example, refer to a table in which the output uT and the target pressure P0 are associated with each other and set the target pressure P0 according to the output uT. In the table, for example, 0.1 MPa may be associated as the target pressure P0 with a predetermined value of the output uT between 0% and 10%. In the table, 0.25 MPa may be associated as the target pressure P0 with a predetermined value of the output uT between 10% and 70%. In the table, 0.3 MPa may be associated as the target pressure P0 with a predetermined value of the output uT between 70% and 100%.

The pressure control unit M2 calculates based on the difference εP between the pressure P in the main body container 11 measured by the pressure gauge 15 and the target pressure P0, and controls the opening degree of the valve V1 based on the result. It is composed of For example, the pressure control unit M2 may be configured to perform a PID calculation based on the difference εP and output the result. That is, with the control of the valve V1 by the pressure control section M2, the pressure P inside the main body container 11 is controlled so as to approach the target pressure P0.

The water level control section M3 is configured to set a target level L0, which is a target value of the liquid level, based on the output uT from the temperature control section M1.

The water level control unit M3 may be configured to set the target level L0 to a larger value, for example, when the output uT falls below a predetermined lower limit value. At this time, the water level control unit M3 may be configured to set the target level L0 to a larger value when the output uT remains below a predetermined lower limit value for a predetermined period of time. The lower limit value of the output uT here may be, for example, about 10%. The predetermined time here may be, for example, about 2 minutes to 3 minutes.

For example, the water level control unit M3 may be configured to set the target level L0 to a smaller value when the output uT exceeds a predetermined upper limit value. At this time, the water level control unit M3 may be configured to set the target level L0 to a smaller value when the output uT exceeds a predetermined upper limit value for a predetermined period of time. The upper limit value of the output uT here may be, for example, about 90%. The predetermined time here may be, for example, about 2 minutes to 3 minutes.

The target level L0 may change continuously according to changes in the output uT, or may change stepwise according to changes in the output uT. When the target level L0 changes in stages, the target level L0 may be switched between, for example, 3 to 5 stages. In the following, a case where the target level L0 changes in three stages from level 1 to level 3 will be explained as an example. For example, when the height of the main container 11 is about 50 cm, level 1 may be set to 35 cm, level 2 may be set to 40 cm, and level 3 may be set to 45 cm.

The water level control unit M3 may be configured not to change the target level L0 until a predetermined time has elapsed since the previous change in the target level L0. The predetermined time here may be longer than the time required to change the liquid level L measured by the water level gauge 16 to the target level L0, or may be longer than the time required to change the liquid level L by one step. The time may be longer than the time required for. The predetermined time may be, for example, about 2 minutes to 3 minutes.

The water level control unit M3 may be configured to set the target level L0 based on the output uT only when the controller Ctr is allowed to change the setting of the target level L0. Whether or not to allow the setting change of the target level L0 by the controller Ctr may be set manually based on the operator's judgment, or may be set automatically in the process of controlling the heat exchanger 10 by the controller Ctr. It's okay.

The water level control unit M3 may be configured not to set the target level L0 to a larger value when the liquid level L measured by the water level gauge 16 is the maximum value (level 3). The water level control unit M3 may be configured not to set the target level L0 to a smaller value when the liquid level L measured by the water level gauge 16 is the minimum value (level 1).

The water level control unit M3 performs calculation based on the difference εL between the liquid level L measured by the water level gauge 16 and the target level L0, and based on the result, the opening degree of the valve V2 and/or the operation of the pump 13. is configured to control. The water level control unit M3 may be configured, for example, to perform a PID calculation based on the difference εL and output the result. That is, as the water level controller M3 controls the valve V2 and/or the pump 13, the liquid level L in the main container 11 is controlled to approach the target level L0.

The stop control section M4 is configured to close the valves V1 and V2 based on the output uT from the temperature control section M1 and the liquid level L measured by the water level gauge 16. When the valves V1 and V2 are closed by the stop control unit M4, the heat exchanger 10 enters a standby state. The stop control unit M4 may be configured to close the valves V1 and V2, for example, when the output uT is below a predetermined minimum value and the liquid level L is at a maximum value (level 3). . At this time, the stop control unit M4 closes the valves V1 and V2 when the output uT is below a predetermined minimum value for a predetermined period of time and the liquid level L is at the maximum value (level 3). may be configured. The lowest value of the output uT here may be, for example, about 0% to 5%. The predetermined time here may be, for example, about 2 minutes to 3 minutes.

The stop control unit M4 closes the valves V1 and V2 based on the output uT and the liquid level L measured by the water level gauge 16 only when automatic closing of the valves V1 and V2 by the controller Ctr is permitted. may be configured to close. Whether or not to allow automatic closing of the valves V1 and V2 by the controller Ctr may be manually set based on the operator's judgment.

The activation control section M5 is configured to open the valve V1 based on the output uT from the temperature control section M1 when the valves V1 and V2 are closed (standby state). The activation control unit M5 may be configured to open the valve V1, for example, when the output uT exceeds a predetermined activation value. At this time, the activation control unit M5 may be configured to open the valve V1 when the output uT continues to exceed a predetermined activation value for a predetermined period of time. The starting value of the output uT here may be, for example, about 5% to 10%. The predetermined time here may be, for example, about 10 seconds to 1 minute, or about 30 seconds.

The activation control unit M5 may be configured to open the valve V1 based on the temperature T of the high temperature water measured by the thermometer 14. The activation control unit M5 is configured to open the valve V1 based on the output uT from the temperature control unit M1, for example, when the temperature T of the high temperature water measured by the thermometer 14 is lower than a predetermined temperature. You can leave it there. The predetermined temperature here may be, for example, 60° C. or lower.

The activation control unit M5 may be configured to also control the valve V2 when opening the valve V1. For example, the activation control unit M5 may be configured to discharge at least a portion of the condensed water in the main body container 11 to the tank 12 by controlling the valve V2.

The hardware of the controller Ctr may be configured by, for example, one or more control computers. The controller Ctr may include, for example, a circuit Ctr1 shown in FIG. 3 as a hardware configuration. The circuit Ctr1 may be composed of electric circuit elements (circuitry). Specifically, the circuit Ctr1 includes a processor Ctr2 (control unit), a memory Ctr3 (storage unit), a storage Ctr4 (storage unit), and an input/output port Ctr5. The processor Ctr2 executes programs in cooperation with at least one of the memory Ctr3 and the storage Ctr4, and inputs and outputs signals via the input/output port Ctr5, thereby configuring each of the above-mentioned functional modules. The input/output port Ctr5 is connected between the processor Ctr2, the memory Ctr3, and the storage Ctr4, and each part of the heat exchanger 10 (for example, the pump 13, the thermometer 14, the pressure gauge 15, the water level gauge 16, and the valves V1 to V3). Performs signal input/output.

The heat exchanger 10 may include, for example, one controller Ctr, or a controller group (control unit) including a plurality of controllers Ctr. When the heat exchanger 10 includes a controller group, each of the above functional modules may be realized by one or more controllers Ctr. When the controller Ctr is composed of a plurality of computers (circuit Ctr1), each of the above functional modules may be realized by one or more computers (circuit Ctr1). When the controller Ctr includes a plurality of processors Ctr2, each of the above functional modules may be implemented by one or more processors Ctr2.

[Liquid level rise control]
Next, with reference to FIG. 4, the control by which the water level control unit M3 automatically raises the liquid level L (liquid level increase control) will be described. While the liquid level increase control is being executed, the pressure control section M2 continues to control the pressure P in the main body container 11 (pressure control).

First, the water level control unit M3 executes step S11. In step S11, the water level control unit M3 determines whether the output uT has fallen below a predetermined lower limit value (eg, 10%) for a predetermined period of time (eg, 2 to 3 minutes). If the output uT is greater than or equal to the predetermined lower limit, or if the time during which the output uT is below the predetermined lower limit is shorter than the predetermined time (NO in step S11), the water level control unit M3 repeats step S11. Execute.

On the other hand, if the output uT remains below the predetermined lower limit value for a predetermined period of time (YES in step S11), the water level control unit M3 executes step S12. In step S12, the water level control unit M3 determines whether a predetermined time (for example, 2 to 3 minutes) has elapsed since the previous change in the target level L0. If the predetermined time has not passed since the previous change in the target level L0 (NO in step S12), the water level control unit M3 executes step S11 again.

On the other hand, if the predetermined time has elapsed since the previous change in the target level L0 (YES in step S12), the water level control unit M3 executes step S13. In step S13, the water level control unit M3 determines whether the current liquid level L measured by the water level gauge 16 is not the maximum value (for example, level 3). If the current liquid level L is the maximum value (NO in step S13), the water level control unit M3 executes step S11 again.

On the other hand, if the current liquid level L is not the maximum value (YES in step S13), the water level control unit M3 executes step S14. In step S14, the water level control unit M3 determines whether or not the controller Ctr is allowed to change the setting of the target level L0. If the setting change of the target level L0 by the controller Ctr is not permitted (NO in step S14), the water level control unit M3 executes step S11 again.

On the other hand, if the setting change of the target level L0 by the controller Ctr is permitted (YES in step S14), the water level control unit M3 executes step S15. In step S15, the water level control unit M3 sets the target level L0 to a larger value. For example, if the current target level L0 is level 1, the target level L0 may be changed to level 2, which is one level higher. If the current target level L0 is level 2, the target level L0 may be changed to level 3, which is one level higher.

Next, the water level control unit M3 executes step S16. In step S16, the water level control unit M3 controls the opening degree of the valve V2 and/or the operation of the pump 13 so that the liquid level L in the main body container 11 approaches the target level L0. When the liquid level L in the main body container 11 reaches the target level L0, the liquid level increase control ends.

[Liquid level lowering control]
Next, with reference to FIG. 5, the control by which the water level control unit M3 automatically lowers the liquid level L (liquid level lowering control) will be described. While the liquid level lowering control is being executed, the pressure control section M2 continues to control the pressure P in the main body container 11 (pressure control).

First, the water level control unit M3 executes step S21. In step S21, the water level control unit M3 determines whether the output uT has continuously exceeded a predetermined upper limit value (eg, 90%) for a predetermined period of time (eg, 2 to 3 minutes). If the output uT is less than or equal to the predetermined upper limit, or if the time during which the output uT exceeds the predetermined upper limit is shorter than the predetermined time (NO in step S11), the water level control unit M3 repeats step S21. Execute.

On the other hand, if the output uT continues to exceed the predetermined upper limit value for a predetermined period of time (YES in step S21), the water level control unit M3 executes step S22. In step S22, the water level control unit M3 determines whether a predetermined time (for example, 2 to 3 minutes) has elapsed since the previous change in the target level L0. If the predetermined time has not elapsed since the previous change in the target level L0 (NO in step S22), the water level control unit M3 executes step S21 again.

On the other hand, if the predetermined time has elapsed since the previous change in the target level L0 (NO in step S22), the water level control unit M3 executes step S23. In step S23, the water level control unit M3 determines whether the current liquid level L measured by the water level gauge 16 is not the minimum value (for example, level 1). If the current liquid level L is the minimum value (NO in step S23), the water level control unit M3 executes step S21 again.

On the other hand, if the current liquid level L is not the minimum value (YES in step S23), the water level control unit M3 executes step S24. In step S24, the water level control unit M3 determines whether the setting change of the target level L0 by the controller Ctr is permitted. If the setting change of the target level L0 by the controller Ctr is not permitted (NO in step S24), the water level control unit M3 executes step S21 again.

On the other hand, if the setting change of the target level L0 by the controller Ctr is permitted (YES in step S24), the water level control unit M3 executes step S25. In step S25, the water level control unit M3 sets the target level L0 to a smaller value. For example, if the current target level L0 is level 2, the target level L0 may be changed to level 1, which is one level smaller. If the current target level L0 is level 3, the target level L0 may be changed to level 2, which is one level smaller.

Next, the water level control unit M3 executes step S26. In step S26, the water level control unit M3 controls the opening degree of the valve V2 and/or the operation of the pump 13 so that the liquid level L in the main body container 11 approaches the target level L0. When the liquid level L in the main body container 11 reaches the target level L0, the liquid level lowering control ends.

[Standby control]
Next, with reference to FIG. 6, the control by which the stop control unit M4 puts the heat exchanger 10 into a standby state (standby control) will be described.

First, the stop control unit M4 executes step S31. In step S31, the stop control unit M4 determines whether or not the output uT remains below a predetermined minimum value (eg, 0% to 5%) for a predetermined period of time (eg, 2 to 3 minutes). If the output uT exceeds the predetermined minimum value, or if the time during which the output uT is below the predetermined minimum value is shorter than the predetermined time (NO in step S11), the stop control unit M4 executes step S31 again. .

On the other hand, if the output uT remains below the predetermined minimum value for a predetermined period of time (YES in step S31), the stop control unit M4 executes step S32. In step S32, the stop control unit M4 determines whether a predetermined time (for example, 2 to 3 minutes) has elapsed since the previous change in the target level L0. If the predetermined time has not passed since the previous change in the target level L0 (NO in step S32), the stop control unit M4 executes step S31 again.

On the other hand, if the predetermined time has passed since the previous change in the target level L0 (YES in step S32), the stop control unit M4 executes step S33. In step S33, the stop control unit M4 determines whether the current liquid level L measured by the water level gauge 16 is the maximum value (for example, level 3). If the current liquid level L is not the maximum value (NO in step S33), the stop control unit M4 executes step S31 again.

On the other hand, if the current liquid level L is the maximum value (YES in step S33), the stop control unit M4 executes step S34. In step S34, the stop control unit M4 determines whether automatic closing of the valves V1 and V2 by the controller Ctr is permitted. If automatic closing of the valves V1 and V2 by the controller Ctr is not permitted (NO in step S34), the stop control unit M4 executes step S31 again.

On the other hand, if automatic closing of the valves V1 and V2 by the controller Ctr is permitted (YES in step S34), the stop control unit M4 executes step S35. In step S35, the stop control unit M4 closes the valves V1 and V2. As a result, heat exchange in the heat exchanger 10 is stopped, the heat exchanger 10 enters the standby state, and the standby control ends.

[Return control from standby state]
Next, with reference to FIG. 7, the control by which the activation control unit M5 causes the heat exchanger 10 to return from the standby state (return control) will be described.

First, the activation control unit M5 executes step S41. In step S41, the activation control unit M5 determines whether the heat exchanger 10 is in a standby state (whether the valves V1 and V2 are closed by the controller Ctr). If the heat exchanger 10 is not in the standby state (NO in step S41), the activation control unit M5 executes step S41 again.

On the other hand, when the heat exchanger 10 is in the standby state (YES in step S41), the startup control unit M5 controls the output uT to maintain a predetermined startup value (for example, 5% to 10%) for a predetermined period of time (for example, 10 seconds to 10%). 1 minute) Determine whether you have consistently exceeded the target. If the output uT is less than or equal to the predetermined startup value, or if the time during which the output uT exceeds the predetermined startup value is shorter than the predetermined time (NO in step S42), the startup control unit M5 executes step S41 again. do.

On the other hand, if the output uT continues to exceed the predetermined activation value for a predetermined period of time (YES in step S42), the activation control unit M5 executes step S43. In step S43, the activation control unit M5 executes water hammer prevention control. The water hammer prevention control will be explained later.

Next, the activation control unit M5 executes step S44. In step S44, the activation control unit M5 allows the controller Ctr to change the setting of the target level L0. This enables pressure control by the pressure control section M2 and liquid level control by the water level control section M3, and the return control is completed.

[Water hammer prevention control]
Next, with reference to FIG. 8, water hammer prevention control by the startup control unit M5 when the heat exchanger 10 is started (including returning from the standby state) will be described.

First, the activation control unit M5 executes step S51. In step S51, the activation control unit M5 determines whether the temperature T of the high temperature water measured by the thermometer 14 is lower than a predetermined temperature (for example, 60° C.). If the temperature T is equal to or higher than the predetermined temperature (NO in step S51), the activation control unit M5 ends the water hammer prevention control.

On the other hand, if the temperature T is lower than the predetermined temperature (YES in step S51), the activation control unit M5 executes step S52. In step S52, the activation control unit M5 opens the valve V2. As a result, at least a portion of the condensed water in the main body container 11 is discharged into the tank 12.

Next, the activation control unit M5 executes step S53. In step S53, the activation control unit M5 opens the valve V1. When the heat exchanger 10 is started, the boiler 2 has also just been started, so when the valve V1 is opened, air instead of steam is supplied from the boiler 2 to the main container 11. Thereafter, steam is generated in the boiler 2 over time, and only steam is supplied to the main container 11. In this process, the mixed gas of steam and air is discharged from the main container 11 via the pipe D5 and the valve V4 until the main container 11 is filled with steam. Thereafter, when the main body container 11 is filled with steam, the valve V4 is automatically closed, and the water hammer prevention control is ended.

[Effect]
According to the above example, the pressure P within the main body container 11 is continuously controlled to follow the target pressure P0 set based on the output of the temperature control section M1. On the other hand, the liquid level L in the main body container 11 is controlled to follow the target level L0, which is set based on the comparison between the output of the temperature control section M1 and a predetermined threshold. As a result of the comparison between the output and the predetermined threshold, the liquid level L will not change unless the target level L0 is changed. Moreover, when the target level L0 is changed, the target level L0 is not changed again until a predetermined period of time has passed. That is, since the liquid level L is changed stepwise under certain conditions, hunting is less likely to occur in the temperature T of the high temperature water. Therefore, the temperature T of the high-temperature water is brought to a predetermined target temperature T0 by controlling the pressure P in the main container 11, which has a relatively fast response speed, and by controlling the liquid level L in the main container 11, which has a relatively slow response speed. Even in the case of controlling, it is possible to stably control the temperature T of the high-temperature water.

According to the above example, when the output of the temperature control section M1 falls below a predetermined lower limit value, the target level L0 is set to a larger value. By setting the target level L0 to a larger value and increasing the liquid level L, the surface area of the heat transfer tubes 3a in contact with the steam in the main container 11 becomes smaller. Therefore, it becomes difficult for heat exchange to occur between the steam and the water flowing through the heat transfer tubes 3a, so it is possible to effectively lower the temperature T of the high-temperature water.

According to the above example, when the output of the temperature control unit M1 remains below the predetermined lower limit value for a predetermined period of time, the target level L0 is set to a larger value. Therefore, in a situation where the output of the temperature control section M1 suddenly becomes low for a short period of time, the target level L0 will not be changed. Therefore, it becomes possible to control the temperature T of the high temperature water more stably.

According to the above example, when the output of the temperature control section M1 exceeds the predetermined upper limit value, the target level L0 is set to a smaller value. By setting the target level L0 to a smaller value and lowering the liquid level L, the surface area of the heat transfer tubes 3a that comes into contact with the steam in the main container 11 increases. Therefore, heat exchange is likely to occur between the steam and the water flowing through the heat transfer tubes 3a, making it possible to effectively raise the temperature T of the high-temperature water.

According to the above example, when the output of the temperature control section M1 exceeds the predetermined upper limit value for a predetermined period of time, the target level L0 is set to a smaller value. Therefore, in a situation where the output of the temperature control section M1 suddenly increases for a short period of time, the target level L0 will not be changed. Therefore, it becomes possible to control the temperature T of the high temperature water more stably.

According to the above example, the target level L0 can be changed by the water level control unit M3 only when the controller Ctr is allowed to change the setting of the target level L0. Therefore, for example, it becomes possible to cope with a situation where the liquid level L is manually controlled based on the operator's judgment.

According to the above example, the target level L0 is set to a predetermined maximum value, and the valves V1 and V2 are closed when the output of the temperature control section M1 becomes equal to or less than a predetermined minimum value. Therefore, when the water flowing through the heat exchanger tubes 3a is sufficiently heated before entering the heat exchanger 10, the heat exchanger 10 enters the standby state. Therefore, it becomes possible to suppress unnecessary heat exchange between the heat exchanger 10 and the water flowing through the heat exchanger tubes 3a.

According to the above example, the valves V1 and V2 are closed when the output of the temperature control section M1 remains below the predetermined minimum value for a predetermined period of time. Therefore, in a situation where the output of the temperature control section M1 suddenly becomes low for a short period of time, the heat exchanger 10 does not shift to the standby state. Therefore, it becomes possible to more stably control the correspondence between the temperature T of the high temperature water and the target pressure P0.

According to the above example, the valves V1 and V2 can be closed by the stop control unit M4 only when automatic closing of the valves V1 and V2 by the controller Ctr is permitted. Therefore, for example, it is possible to manually put the heat exchanger 10 on standby based on the operator's judgment, or to cope with a situation where it is not desired to put the heat exchanger 10 on standby.

According to the above example, when the heat exchanger 10 is in the standby state and the output of the temperature control section M1 exceeds a predetermined activation value, the setting is changed to allow automatic control of the valves V1 and V2. Therefore, it becomes possible to automatically start the heat exchanger 10 based on a comparison between the output of the temperature control section M1 and a predetermined starting value.

According to the above example, when the output of the temperature control section M1 continues to exceed the predetermined starting value for a predetermined period of time, the setting is changed to allow automatic control of the valves V1 and V2. Therefore, in a situation where the output of the temperature control section M1 suddenly exceeds the activation value for a short period of time, activation of the heat exchanger 10 is avoided. Therefore, it is possible to prevent the activation of the heat exchanger 10 and the transition to the standby state from being repeated in a short period of time.

According to the above example, when the heat exchanger 10 is started (including returning from the standby state), air is first introduced into the main body container 11, and then steam is supplied. Therefore, since the steam is mixed with air in the main body container 11, even if steam is supplied into the main body container 11, which has been cooled due to the stoppage of the heat exchanger 10, the steam is difficult to condense rapidly. Therefore, it is possible to suppress the occurrence of water hammer.

According to the above example, air is supplied into the main body container 11 when the temperature T of the high temperature water measured by the thermometer 14 is lower than the predetermined temperature. Therefore, air is supplied into the main container 11 in a situation where water hammer is likely to occur. Therefore, it is possible to effectively suppress the occurrence of water hammer.

According to the above example, the valve V2 is controlled to discharge at least a portion of the condensed water in the main body container 11 from the main container 11 when the heat exchanger 10 is started (including returning from the standby state). ing. Therefore, condensed water that causes water hammer to occur is discharged from the main body container 11, making it possible to more effectively suppress the occurrence of water hammer.

According to the above example, the heat exchanger 10 allows exhaust from the main container 11 until the main container 11 is filled with steam, and when the main container 11 is filled with steam, the heat exchanger 10 allows the exhaust from the main container 11. includes a valve V4 configured to stop exhaustion of the air. Therefore, when steam is supplied into the main body container 11 to which air is supplied, a mixed gas of steam and air is initially discharged from the main body container 11 via the valve V4. After that, when more steam is supplied into the main body container 11, the exchange of air and steam progresses, the inside of the main body container 11 is filled with steam, and the valve V4 is closed. Therefore, it becomes possible to automatically stop the exhaust from the main body container 11 by the valve V4.

According to the above example, when the boiler 2 is in operation, steam generated by the boiler 2 is supplied into the main body container 11 through the pipe D1 and the valve V1. On the other hand, immediately after the boiler 2 is started together with the heat exchanger 10, steam is not generated in the boiler 2, so air in the boiler 2 is supplied into the main body container 11 through the pipe D1 and the valve V1. That is, it becomes possible to supply air and steam to the main container 11, respectively, without separately providing a mechanism for supplying air to the main container 11 in the main container 11.

[Modified example]
The disclosure herein should be considered to be illustrative in all respects and not restrictive. Various omissions, substitutions, changes, etc. may be made to the above examples without departing from the scope and gist of the claims.

Valve V4 may be opened or closed based on a control signal from controller Ctr.

Air may be supplied to the main body container 11 from an air source different from the boiler 2 through a pipe different from the pipe D1.

DESCRIPTION OF SYMBOLS 1...Hot water supply system, 2...Boiler, 3...Customer facility, 10...Heat exchanger, 11...Main container, 12...Tank (level adjustment part), 13...Pump (level adjustment part), 14...Thermometer ( Temperature measurement section), 15... Pressure gauge (pressure measurement section), 16... Water level gauge (level measurement section), Ctr... Controller (control section), D1... Piping (supply section, air supply section), D2, D3... Piping (Level adjustment part), D5...Piping (exhaust part), M1...Temperature control part (temperature measurement part), M2...Pressure control part (pressure measurement part), M3...Water level control part (level measurement part), V1...Valve (supply section, air supply section), V2...valve (level adjustment section), V4...valve (exhaust section).

Claims (16)

A main container,
a supply section configured to supply steam to the main container;
a level adjustment section configured to be able to adjust the level of the liquid in the main body container;
a heat exchanger tube that is arranged to penetrate the main body container so as to vertically traverse the inside of the main body container, and is configured to allow a fluid to be heated to flow therethrough;
a pressure measuring unit configured to measure the pressure within the main body container;
a temperature measuring section configured to measure the temperature of a heated fluid flowing downstream of the main body container of the heat transfer tube;
a level measuring section configured to measure the liquid level of the liquid in the main container;
It is equipped with a control section,
The control unit includes:
Calculations are performed based on the difference between the temperature measured by the temperature measurement unit and a target temperature of the heated fluid flowing downstream of the main body container in the heat transfer tube, and an output value that is the result is output. to do and
setting a target pressure that is a target value of the pressure in the main body container based on the output value ;
controlling the supply unit so that the pressure measured by the pressure measurement unit approaches the target pressure;
Setting a target level that is a target value of the liquid level in the main body container based on a comparison between the output value and a predetermined threshold;
controlling the level adjusting unit so that the liquid level measured by the level measuring unit approaches the target level;
When the level adjustment unit is controlled to change the liquid level in the main body container, the target level is prohibited from changing until a predetermined time period has elapsed. Heat exchanger. Setting the target level includes setting the target level to a larger value when the output value is below a predetermined lower limit value,
The heat exchanger according to claim 1, wherein controlling the level adjustment section includes supplying the liquid into the main body container so that the liquid level measured by the level measurement section approaches the target level. vessel. The heat exchanger according to claim 2, wherein the output value falling below a predetermined lower limit means that the output value continues to fall below the predetermined lower limit for a predetermined period of time. Setting the target level includes setting the target level to a smaller value when the output value exceeds a predetermined upper limit value,
Any one of claims 1 to 3, wherein controlling the level adjusting section includes discharging the liquid from within the main body container so that the liquid level measured by the level measuring section approaches the target level. The heat exchanger according to paragraph 1. The heat exchanger according to claim 4, wherein the output value exceeding a predetermined upper limit means that the output value continuously exceeds the predetermined upper limit for a predetermined period of time. According to any one of claims 1 to 5, setting the target level includes setting the target level only when the control unit is allowed to change the setting of the target level. heat exchanger. The control unit is further configured to stop the supply unit and the level adjustment unit when the target level is set to a predetermined maximum value and the output value becomes equal to or less than a predetermined minimum value. The heat exchanger according to any one of claims 1 to 6, wherein the heat exchanger is configured as follows. 8. The heat exchanger according to claim 7, wherein the output value being less than or equal to a predetermined minimum value means that the output value is continuously less than or equal to the predetermined minimum value for a predetermined period of time. Stopping the supply section and the level adjustment section means stopping the supply section and the level adjustment section only when automatic control of the supply section and the level adjustment section by the control section is permitted. The heat exchanger according to claim 7 or 8, comprising: The control unit changes the setting to allow automatic control of the supply unit and the level adjustment unit when the supply unit and the level adjustment unit are stopped and the output value exceeds a predetermined starting value. A heat exchanger according to any one of claims 7 to 9, further configured to perform the following. The heat exchanger according to claim 10, wherein the output value exceeding a predetermined starting value means that the output value continuously exceeds the predetermined starting value for a predetermined period of time. further comprising an air supply section configured to supply air into the main container,
The control unit includes:
controlling the air supply unit to introduce air into the main body container when a start signal is input;
12. The method according to any one of claims 1 to 11, further configured to, subsequent to controlling the air supply, control the supply to supply steam into the main container. Heat exchanger as described in Section. Controlling the air supply unit includes controlling the air supply unit to introduce air into the main body container when the temperature of the heated fluid measured by the temperature measurement unit is lower than a predetermined temperature. 13. The heat exchanger according to claim 12, comprising: The control unit is configured to further control the level adjustment unit to discharge at least a portion of the liquid in the main body container from the main body container when an activation signal is input. The heat exchanger according to claim 12 or 13. An exhaust section configured to allow exhaust from the main container until the main container is filled with steam, and to stop evacuation from the main container when the main container is filled with steam. A heat exchanger according to any one of claims 12 to 14, further comprising: The heat exchanger according to any one of claims 12 to 15, wherein the air supply section includes the supply section configured to supply air or steam from a boiler into the main body vessel.

Images