JPH10103605A - Number-of-working-fluid-heaters control method for fluid heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a number of working fluid heaters control method to realize responsiveness to stable supply of hot water at a desired temperature and the fluctuation of a load at a further higher level, in a number of working fluid heaters control system for the fluid heaters, such as hot water boilers. SOLUTION: In a number of working fluid heaters control method wherein a plurality of fluid heaters 1 are connected together in parallel, and the fluid heater 1 and a load 7 are connected together through a fluid fed line 8 and a fluid return line 9, and the number of working fluid heaters of the fluid heaters 1 is controlled according to the state of a load 7, a circulation line 4 is arranged at each fluid heater 1 and through circulation of fluid through a circulation line 4, control is performed such that an outflow amount of fluid from each fluid heater 1 is uniformized, and the number of working fluid heaters is regulated based on an average temperature of fluid temperatures at the outlet parts of the fluid heaters 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling a plurality of fluid heaters, in which a plurality of fluid heaters are installed, and the number of operating these fluid heaters is automatically controlled according to a load condition. Here, the fluid heater in the present invention refers to an entire apparatus for heating a fluid, such as a hot water boiler, a heat medium boiler, and an absorption refrigerator.

[0002]

2. Description of the Related Art For example, in hot water supply / heating equipment such as buildings, condominiums and apartment houses, hot water supply and heating are performed using a hot water boiler. In recent years, in order to obtain good quality hot water due to the strengthening of water quality regulations, instead of directly using the hot water obtained by a hot water boiler, this hot water is used as a heat medium and indirectly through a heat exchanger. Some are configured to obtain hot water. In recent years, a so-called number control system has been adopted in which a plurality of small-capacity hot water boilers are installed in place of one large hot water boiler, and the number of hot water boilers operated is changed according to a required load. I have. In this unit control system, one large-capacity hot water boiler is used.
Compared to installing a stand, each hot water boiler can be operated with high efficiency, so it has a remarkable effect on energy saving and has the advantage of excellent responsiveness to load fluctuations. .

In recent years, however, in such a system for controlling the number of hot water boilers, a higher level of responsiveness to load fluctuation, prevention of unnecessary start / stop, and stable supply of hot water at a desired temperature has been required. It is becoming.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a system for controlling the number of fluid heaters such as hot water boilers, in which a stable supply of hot water at a desired temperature and a higher response to fluctuations in load are achieved. An object of the present invention is to provide a unit control method realized at a level.

[0005]

According to the present invention, a plurality of fluid heaters are connected in parallel, and these fluid heaters and a load are connected by a fluid supply line and a fluid return line. A number control method for controlling the number of operating units according to the load situation, wherein a circulation line is provided in each of the fluid heaters, and the fluid is circulated in the circulation line, whereby the fluid from each of the fluid heaters is The above-mentioned problem is solved by controlling the number of operating units based on the average temperature Ta of the fluid temperatures T0 at the outlets of the respective fluid heaters while controlling the outflow amount of the fluid heaters to be uniform.

Further, according to the present invention, a circulation line is provided between each of the fluid heaters and the fluid return line, and the fluid is circulated in the circulation line, so that the fluid is discharged from each of the fluid heaters. The amount of fluid is controlled so as to be uniform, and the fluid temperature T0 at the outlet of each fluid heater is controlled.
The above-mentioned problem is solved by adjusting the number of operating units based on the average temperature Ta.

Further, according to the present invention, all the fluid heaters are connected by a circulation line, and the fluid is circulated in the circulation line, so that the temperatures of the fluids in the respective fluid heaters are made uniform and each fluid heater is heated. The above-mentioned problem is solved by adjusting the number of operating units based on the average temperature Ta of the fluid temperature T0 at the outlet of the machine or based on the supply temperature Tout of the fluid in the fluid supply line.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention installs a plurality of fluid heaters such as a hot water boiler, a heat medium boiler, and an absorption refrigerator, and automatically operates the number of these fluid heaters according to the load condition. The control is performed in the number control system. The control method in the number control system determines the number of operating these fluid heaters according to the load condition and controls each fluid heater. Here, the plurality of fluid heaters are installed in parallel, and these fluid heaters and the load are connected by a fluid supply line and a fluid return line. Therefore, the sum of the flow rates of the fluid from the fluid heater to the fluid supply line and the sum of the flow rates of the fluid flowing from the fluid return line to each fluid heater are the same, regardless of the number of operating fluid heaters. Fluid is circulated through the heater, and the heater is in a hot water state. The number of operating fluid heaters includes, for example, the set temperature of the fluid supplied to the load, the fluid temperature of the fluid supply line, the fluid temperature of the fluid return line, and the maximum temperature of the fluid that can be supplied from each fluid heater. Is determined from the relationship. Further, the fluid heater includes both a device for directly heating the fluid from the fluid return line and supplying the fluid to the fluid supply line, and a device for indirectly heating the fluid from the fluid return line via a heat exchanger.

In the above number control method, in the invention according to the first aspect, each fluid heater is provided with a circulation line for circulating a fluid inside each fluid heater, and each fluid heater is provided with a circulation line from each fluid heater to the fluid supply line. The flow rate in the circulation line is controlled so that the flow rate is uniform. By making the flow rate from each fluid heater uniform, the fluid temperature in the fluid supply line becomes the average temperature Ta of the fluid temperature T0 at the outlet of each fluid heater. Therefore, by adjusting the number of operating units based on the average temperature Ta, an appropriate number of operating units can be obtained.

The reasons for making the flow rate uniform in each fluid heater as described above are as follows. In the number control system, when a part of the fluid heater is operating, in the operating fluid heater, the low-temperature fluid from the fluid return line flows into the fluid supply line after being heated, but is stopped. Flows into the fluid supply line at a low temperature. In the fluid heater during operation, the temperature of the fluid becomes high and the viscosity, specific gravity, and the like decrease. Here, if measures are not taken to equalize the fluid flow rates from the fluid heaters as described above, the flow rate to the fluid supply line in the operating fluid heaters is reduced due to the decrease in viscosity or specific gravity. The fluid flowing through the fluid supply line has the above-mentioned average temperature T because the flow rate increases and the flow rate of the stopped fluid heater decreases.
It will be hotter than a. That is, a fluid having a temperature higher than the set value of the fluid temperature is supplied to the fluid supply line.

Further, in the invention according to the first aspect, in each fluid heater, the internal fluid is circulated by the circulation line, so that the temperature of the fluid in each fluid heater is averaged. Therefore, when the number of operating fluid heaters changes, the overshoot and undershoot of the fluid temperature due to the difference between the amount of heat held by the fluid heater and the actual amount of heat predicted on the control side is prevented, and the load following ability is improved.

Next, in the invention according to claim 2, each of the fluid heaters is provided with a circulation line for circulating the internal fluid between the fluid heater and the fluid return line, and each fluid heater is connected to a fluid supply line. The flow rate in the circulation line is controlled so that the flow rate becomes uniform. Further, the number of operating units is adjusted based on the average temperature Ta of the fluid temperature at the outlet of each fluid heater. Also in the invention according to the second aspect, by making the flow rate from each fluid heater uniform, the fluid temperature in the fluid supply line becomes the average temperature Ta of the fluid temperature at the outlet of each fluid heater. Therefore, by adjusting the number of operating units based on the average temperature Ta, an appropriate number of operating units can be obtained.

Further, in the invention according to the second aspect, in each fluid heater, when the internal fluid is circulated between the fluid return line and the internal fluid by the circulation line, the connection form of the circulation line is the outlet of the fluid heater. A circulation line is connected between the fluid heater and the fluid return line, and a circulation line is connected between the inlet side of the fluid heater and the fluid return line. The former adjusts the flow rate from the fluid heater to the fluid supply line, thereby equalizing the fluid flow rate from each fluid heater, and the latter adjusts the flow rate from the fluid return line to the fluid heater. By doing so, the fluid flow rate from each fluid heater is made uniform.

According to the first and second aspects of the present invention, when the fluid heater supplies the fluid to be heated directly to the fluid supply path, a circulation line is provided to the fluid heater itself. Connect. On the other hand, in the case of heating the fluid to be heated from the fluid return path via the heat exchanger,
A circulation line is connected to a heat exchanger connected to the fluid heater.

Next, according to the third and fourth aspects of the present invention, all the fluid heaters are connected by a circulation line, and the fluid is circulated in the circulation line, thereby reducing the temperature of the fluid in the fluid heater. It is uniform. By making the temperatures of the fluids in all the fluid heaters uniform in this manner, the temperature inside all the fluid heaters is made uniform regardless of whether the operation is stopped or in operation. Therefore, the above-mentioned flow rate problem does not matter, and the supply temperature Tout of the fluid in the fluid supply line becomes the fluid temperature at the outlet of each fluid heater. In this state, in the invention according to claim 3,
In the invention according to the fourth aspect, the number of operating units can be appropriately determined by adjusting the number of operating units based on the fluid temperature T0 at the outlet of the fluid heater based on the supply temperature Tout of the fluid in the fluid supply line. . In addition, in each fluid heater, the fluid temperature in each fluid heater averages as described above. Therefore, when the number of operating fluid heaters changes, the fluid temperature is prevented from overshooting or undershooting, and the load following ability is improved.

According to the third and fourth aspects of the present invention, when the fluid heater supplies the fluid to be heated directly to the fluid supply path, the fluid heaters circulate between the fluid heater main bodies. Connect with a line. On the other hand, in the case of heating the fluid to be heated from the fluid return path via the heat exchanger, the heat exchangers connected to the fluid heater are connected by a circulation line.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for controlling the number of fluid heaters according to the present invention will be described below with reference to FIG. In the first embodiment shown in FIG. 1, the invention according to claim 1 of the present invention is applied to a number control system using a hot water boiler of a type in which hot water is directly taken out of a can body.

In FIG. 1, each of the hot water boilers 1 uses a once-through hot water boiler for the boiler body 2. In FIG. 1, only the hot water boiler 1 at the left end in the drawing schematically shows the boiler main body 2 (the same applies to the following drawings showing examples). A circulation line 4 is connected to the boiler body 2. The circulation line 4 connects the outlet side and the inlet side of the fluid of the boiler main body 2, and the circulation pump 3 is connected in the middle thereof. Further, the boiler main body 2 is provided with a heating means (not shown). The heating means is controlled by a control device on the hot water boiler 1 side or a unit control device 20 described later.
Is controlled by

Each hot water boiler 1 has an outlet pipe 5 and an inlet pipe 6.
The outlet pipe 5 and the inlet pipe 6 of each hot water boiler 1 are connected to a fluid supply line 8 extending toward a load 7.
And a fluid return line 9 from the load 7.
Further, a main circulation pump 1 for circulating fluid between each hot water boiler 1 and the load 7 is provided in the fluid return line 9.
0 is provided. The main circulation pump 10 may be connected to the fluid supply line 8 side. Here, the load 7 is a heat exchanger for heating or hot water supply. Therefore, in this number control system, the fluid (hot water) from each hot water boiler 1 is supplied to the load 7 from each outlet pipe 5 via the fluid supply line 8, and from the fluid return line 9 via each inlet pipe 6. It is configured to flow into each hot water boiler 1 again.

A first temperature detector 11 for detecting the fluid temperature T0 at the outlet of each hot water boiler 1 is connected to the outlet pipe 5 of each hot water boiler 1. Further, a flow detector 14 for detecting a flow rate Q1 from the fluid return line 9 to each hot water boiler 1 is provided at the inlet pipe 6 of each hot water boiler 1.
Is connected. The reason why the flow rate detector 14 is attached to the inlet pipe 6 is that the temperature of the fluid from the fluid return line 9 is constant in each hot water boiler 1 and the influence of the temperature on the flow rate detector 14 (fluid density) , Viscosity, etc.) are the same, so that the flow rate of each hot water boiler 1 can be measured under the same conditions. Of course, the flow detector 14 may be attached to the outlet pipe 5 side. Further, a second temperature detector 12 for detecting a fluid temperature Tin from the load 7 is connected to the fluid return line 9.

In this number control system, the number of operating hot water boilers 1 and the like are determined by the number control device 20, and control is performed as if one hot water boiler is operating. The number of operating units is determined, for example, from the relationship between the set temperature of the fluid supplied to the load, the fluid temperature Tin of the fluid return line 9, the maximum temperature of the fluid that can be supplied from each fluid heater, and the like. In this way, the number control device 20 determines the number of hot water boilers 1 to be started according to the status of the load 7.
Priorities for stopping are set in advance, and starting and stopping are performed according to the priorities. Further, the number control device 20 detects the fluid temperature T0 at the outlet pipe 5 of each of the hot water boilers 1 by the first temperature detector 11 and calculates an average temperature Ta of the hot water temperatures of all the hot water boilers 1, and calculates this value. , The number of operating hot water boilers 1 is adjusted, and each hot water boiler 1 is started or stopped. Here, the hot water boiler 1 after startup is controlled by the respective control devices (or the number control device 20) as described above. This control is performed based on the fluid temperature T0 by the first temperature detector 11.

In the unit control system configured as described above, after the system is started, the circulation pump 3 of each hot water boiler 1 is operated and the fluid is circulated in the boiler main body 2 regardless of whether the respective hot water boilers 1 are operating or stopped. Thus, the fluid flow rate Q1 flowing out of each outlet pipe 5 is controlled to be constant. This control is performed by the flow detector 1 attached to each outlet pipe 5.
The operation is performed by adjusting the operation amount of each circulation pump 3 by the number control device 20 based on the flow rate detection signal from the control unit 4. Further, the control may be performed by a circulation pump control device 25 different from the number control device 20. With this control, the fluid flow rate Q1 from each hot water boiler 1 to the fluid supply line 8
Are the same regardless of whether the hot water boiler 1 is operating or stopped. Here, the reason why the fluid flow rate is changed by the circulation line 4 is as follows. That is, if the amount of circulation through the circulation line 4 increases, the flow velocity in the boiler main body 2 increases, and the pressure loss increases. By making the fluid flow rate Q1 from each hot water boiler 1 uniform, the fluid temperature Tout in the fluid supply line 8 becomes the average temperature T0 of the fluid temperature T0 at the outlet of each hot water boiler 1.
a. Therefore, the number control device 20 can appropriately determine the number of operating units by adjusting the number of operating units based on the average temperature Ta.

The reason for making the fluid flow rate Q1 uniform in each hot water boiler 1 is as follows. That is, in such a number control system, when a part of the hot water boiler 1 is operating, the low temperature fluid from the fluid return line 9 becomes high temperature in the operating hot water boiler 1 and the fluid supply line 8 However, in the stopped hot water boiler 1, it flows into the fluid supply line 8 at a low temperature.
In the hot water boiler 1 during operation, the temperature of the fluid becomes high, and the viscosity, specific gravity, and the like decrease. Here, if no measures are taken to make the fluid flow rate Q1 from each hot water boiler 1 uniform, as described above, the hot water boiler 1 during the operation will have a fluid supply line due to the decrease in viscosity and specific gravity. 8, the flow rate Q1 of the warm water boiler 1 during operation is reduced accordingly. Therefore, simply averaging the fluid temperature T0 at the outlet of each hot water boiler 1 as described above results in the fluid temperature Tout in the fluid supply line 8.
Becomes higher than the average temperature Ta. That is, a fluid having a temperature higher than the set value of the fluid temperature is supplied to the fluid supply line.

Further, the number control device 20
A case where the number of operating hot water boilers 1 changes will be described. First, in the case of increasing the number of operating units, in the hot water boiler 1 switched from the stopped state to the started state, the fluid in the boiler 1 is rapidly heated, and the fluid temperature rises. However, by circulating the fluid inside the boiler body 2 through the circulation line 4, the fluid flow rate Q1 is controlled to be uniform, and the temperature of the fluid in the boiler body 2 is averaged. Become Therefore, in the fluid supply line 8, an excessive rise in temperature does not occur, and it is possible to prevent the fluid temperature from overshooting when the number of operating hot water boilers 1 increases. On the other hand, when the number of operating units is reduced, in the hot water boiler 1 that has been switched from the operating state to the stop state, the low-temperature fluid from the fluid return line 9 tries to flow out of the outlet pipe 5 instead of the high-temperature fluid so far. Accordingly, the flow rate also tends to decrease. However, by circulating the fluid inside the boiler body 2 as described above, the fluid flow rate Q1
Is controlled to be uniform, and the temperature of the fluid in the boiler body 2 is averaged. Therefore, in the fluid supply line 8, an excessive temperature drop does not occur, and it is possible to prevent an undershoot of the fluid temperature when the number of operating hot water boilers 1 is reduced. As described above, according to the number control method of the present invention, appropriate temperature control can be performed, overshoot and undershoot are prevented, and load followability is improved.

Here, the load 7 is a heat exchanger for heating or hot water supply. However, when a load such as a hot water supply faucet or a shower which takes out hot water out of the system is used, the load 7 is used. A water supply line is connected to the fluid return line 9 to supply fluid taken out of the system. In this case, the fluid from each hot water boiler 1 is supplied to the load 7 from each outlet pipe 5 through the fluid supply line 8, and the insufficient fluid is supplied from the fluid return line 9 after being supplied from the water supply line. It becomes the structure which flows into each hot water boiler 1 again through each inlet pipe 6.

Next, a second embodiment of the method for controlling the number of fluid heaters according to the present invention will be described with reference to FIG. As in the first embodiment, the second embodiment shown in FIG. 2 is applied to a unit control system using a hot water boiler of a type in which hot water is directly taken out from a can body. In the second embodiment, each hot water boiler 1 is provided with a circulating line 4 for circulating the fluid inside the respective hot water boilers with a fluid return line 9, and a fluid supply line 8 is provided from each hot water boiler 1.
The flow rate in the circulation line 4 is controlled so that the flow rate to the circulation line becomes uniform. The adjustment of the number of operating units is performed based on the average fluid temperature Ta at the outlet of each hot water boiler 1, as in the first embodiment. Also in the second embodiment, by making the flow rate from each fluid heater uniform, the fluid temperature in the fluid supply line becomes the average fluid temperature Ta at the outlet of each fluid heater. Therefore, by adjusting the number of operating units based on the average temperature Ta, an appropriate number of operating units can be obtained. In the second embodiment, the circulation line 4 is connected between the outlet side of the boiler main body 2 of the hot water boiler 1 and the fluid return line 9, and by circulating the fluid in the circulation line 4, The flow rate from the hot water boiler 1 to the fluid supply line 8 is adjusted. Here, in this case, when the fluid temperature in the fluid return line 9 is used for control, the second temperature detector 12 for that purpose is connected downstream of the junction of the circulation line 4, and Preferably, it is not affected by the incoming hot fluid.

Next, a third embodiment of the method for controlling the number of fluid heaters according to the present invention will be described with reference to FIG. The third embodiment shown in FIG. 3 is applied to a unit control system using a hot water boiler of a type in which hot water is directly taken out of a can body, similarly to the second embodiment. In the third embodiment, the circulation line 4 is connected between the inlet side of the boiler main body 2 of the hot water boiler 1 and the fluid return line 9, and by circulating the fluid in the circulation line 4, The flow rate from the fluid return line 9 to the hot water boiler 1 is adjusted to make the flow rate to the fluid supply line 8 uniform. The operation and effect of the third embodiment are the same as those of the above-described second embodiment, and thus will not be described. Here, in the third embodiment, when the temperature of the fluid in the fluid return line 9 is used for control, a second temperature detector 12 for that purpose is connected to the fluid return line 9. Since the fluid flowing into the return line 9 is a low-temperature fluid at the inlet side of the boiler main body 2, there is no restriction on the connection location of the second temperature detector 12.

Here, in the first to third embodiments,
Although the flow rate of each hot water boiler 1 is directly detected by the flow rate detector 14, the temperature of the fluid is detected by the first temperature detector 11 at the outlet pipe 5 of the hot water boiler 1 instead. Can also determine the flow rate.
That is, if the change in the viscosity or specific gravity of the fluid is grasped according to the temperature, the buoyancy of the fluid and the pressure loss in the hot water boiler based on the temperature change can be obtained.

Next, a fourth embodiment of the method for controlling the number of fluid heaters according to the present invention will be described with reference to FIG. As in the first embodiment, the fourth embodiment shown in FIG. 4 is applied to a unit control system using a hot water boiler of a type in which hot water is directly taken out from a can body.

In the fourth embodiment, all the hot water boilers 1 are connected by a circulation line 4, and the fluid in the whole hot water boiler 1 is circulated by the circulation line 4. Specifically, the upper part of the boiler main body 2 of the first hot water boiler 1 (the hot water boiler on the left side in FIG. 4) and the lower part of the boiler main body 2 of the second hot water boiler 1 are connected by a circulation line 4, and this circulation is performed. A circulation pump 3 for supplying canned water from the first hot water boiler 1 to the second hot water boiler 1 is connected to the line 4. Similarly, the other hot water boilers 1 are sequentially connected by the circulation line 4. Then, the upper part of the boiler main body 2 of the last hot water boiler (the third hot water boiler in the fourth embodiment) 1 is connected to the lower part of the boiler main body 2 of the first hot water boiler 1. Then, during the operation of the system, the circulation pump 3 is operated to circulate the canned water in the whole hot water boiler 1. The control of the circulation pump 3 may be performed by the number controller 20 or may be configured to be manually operated when the system is started. According to this configuration, the fluid temperature inside the entire hot water boiler 1 is made uniform regardless of whether the hot water boilers 1 are stopped or in operation, so that the fluid temperature Tout flowing through the fluid supply line 8 becomes It becomes equal to the fluid temperature T0 of the outlet pipe 5 of the boiler 1. In addition, the above-mentioned flow rate problem does not matter.

In the number control device 20 of the fourth embodiment, the number of operating hot water boilers 1 is adjusted by the third temperature detector 13 attached to the fluid supply line 8 so that the supply temperature of the fluid as the whole system is adjusted. Tout is detected, and the operation is performed based on the supply temperature Tout. Alternatively, the number of operating units is adjusted based on the fluid temperature T0 at the outlet pipe 5 of the hot water boiler 1 instead of the fluid supply temperature Tout.

According to the fourth embodiment, each hot water boiler 1
The fluid temperatures T0 in the outlet pipes 5 are all uniform, and naturally the average temperature Ta of the fluid temperatures in the outlet pipes 5 is Ta.
Is substantially equal to the fluid temperature T0. Also,
This fluid temperature T0 is substantially equal to the supply temperature Tout of the fluid in the fluid supply line 8. Therefore, in the fourth embodiment, if the fluid temperature T0 at the outlet pipe 5 of each of the hot water boilers 1 or the supply temperature Tout of the fluid in the fluid supply line 8 is detected, the number of operating units can be appropriately determined based on the detected value. Can be determined.

In the fourth embodiment, the whole hot water boiler 1
The temperature of the fluid in each of the hot water boilers 1 is also averaged. That is, the fluid in the stopped hot water boiler 1 is heated by the hot water boiler 1 in operation. Therefore, each hot water boiler 1
The rise in the temperature of the hot water and the change of the tapping temperature become smooth, and the interval between start and stop in each hot water boiler 1 becomes longer, so that each of the above-mentioned overshoots and undershoots also decreases. Further, as described above, this number control device 2
With 0, even when the number of operating hot water boilers 1 changes, overshoot and undershoot can be prevented, and load following performance can be improved.

Here, the number control system in each of the above embodiments is applied to a number control system using a hot water boiler of a type in which hot water is directly taken out from a can body. Using a hot water boiler of the type that supplies hot water via a vacuum (or decompression type)
Various types of fluid heaters, such as those using a hot water boiler, can be used. Further, the number control system of each of the above embodiments is provided with three hot water boilers.
The number of installations is not limited to three, but may be any number as long as it is a plurality.

[0035]

As described above, according to the method of controlling the number of fluid heaters according to the first aspect of the present invention, each fluid heater is provided with a circulation line for circulating a fluid inside the fluid heater. By controlling the flow rate in the circulation line so that the flow rate from each fluid heater to the fluid supply line becomes uniform, the fluid temperature in the fluid supply line becomes the average temperature of the fluid temperature at the outlet of each fluid heater. Therefore, the number of operating units can be appropriately determined by adjusting the number of operating units based on the average temperature Ta. Further, in the invention according to claim 1, in each fluid heater, the temperature of the fluid in each fluid heater is averaged by circulating the internal fluid by the circulation line, so that the number of operating fluid heaters varies. Overshoot and undershoot of the fluid temperature at the time can be prevented, and the load following ability can be improved.

Next, in the invention according to claim 2, each of the fluid heaters is provided with a circulation line for circulating the internal fluid between the fluid heater and the fluid return line, and each fluid heater is connected to the fluid supply line. The flow rate in the circulation line is controlled so that the flow rate becomes uniform. Further, by adjusting the number of operating units based on the average temperature Ta of the fluid temperature at the outlet of each fluid heater, the fluid temperature in the fluid supply line is equal to the average temperature Ta of the fluid temperature at the outlet of each fluid heater. Become. Therefore, by adjusting the number of operating units based on the average temperature Ta, an appropriate number of operating units can be obtained.

Further, according to the method for controlling the number of fluid heaters according to the third and fourth aspects of the present invention, all the fluid heaters are connected by a circulation line, and the fluid is circulated in the circulation line. Thus, the temperature inside all the fluid heaters is made uniform regardless of whether the apparatus is stopped or in operation, so that the above-mentioned flow rate problem is not relevant. Since the fluid temperature at the outlet of the machine is T1, the supply temperature Tou of the fluid in the fluid supply line
In the invention according to claim 4 based on t, the number of operating units can be appropriately determined by adjusting the number of operating units based on the fluid temperature T0 at the outlet of the fluid heater. Moreover, as described above, in each fluid heater, the fluid temperature in each fluid heater is averaged, thereby preventing overshoot and undershoot of the fluid temperature when the number of operating fluid heaters changes. Thus, the load followability can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram for explaining a specific first embodiment of a method for controlling the number of fluid heaters according to claim 1 of the present invention.

FIG. 2 is a schematic configuration diagram for explaining a second specific example of the method for controlling the number of fluid heaters according to the second embodiment of the present invention.

FIG. 3 is a schematic configuration diagram for explaining a third specific example of the method for controlling the number of fluid heaters according to a second embodiment of the present invention;

FIG. 4 is a schematic configuration diagram for explaining a fourth specific example of the method for controlling the number of fluid heaters according to claims 3 and 4 of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hot water boiler (fluid heater) 3 Circulation pump 4 Circulation line 7 Load 8 Fluid supply line 9 Fluid return line 20 Unit control device

Claims (4)

[Claims] 1. A plurality of fluid heaters 1 are connected in parallel, the fluid heaters 1 and a load 7 are connected by a fluid supply line 8 and a fluid return line 9, and the number of operating the fluid heaters 1 Is controlled in accordance with the condition of the load 7 by providing a circulation line 4 in each of the fluid heaters 1 and circulating a fluid in the circulation line 4 to thereby control each of the fluid heaters 1. The number of operating fluid heaters is controlled based on the average temperature Ta of the fluid temperature T0 at the outlet of each fluid heater 1 while controlling the amount of fluid flowing out of the fluid heaters to be uniform. Control method. 2. A plurality of fluid heaters 1 are connected in parallel, and these fluid heaters 1 and a load 7 are connected by a fluid supply line 8 and a fluid return line 9; In accordance with the condition of the load 7, wherein a circulation line 4 is provided between each of the fluid heaters 1 and the fluid return line 9, and a fluid is circulated in the circulation line 4. By controlling this, the outflow of fluid from each fluid heater 1 is controlled to be uniform,
A method of controlling the number of fluid heaters, wherein the number of operating fluid heaters is adjusted based on the average temperature Ta of the fluid temperature T0 at the outlet of each fluid heater. 3. A plurality of fluid heaters 1 are connected in parallel, these fluid heaters 1 and a load 7 are connected by a fluid supply line 8 and a fluid return line 9, and the number of operating fluid heaters 1 Is controlled in accordance with the condition of the load 7, wherein all the fluid heaters 1 are connected by a circulation line 4, and the fluid is circulated in the circulation line 4. The temperature of the fluid inside the fluid heater 1 is made uniform, and the fluid temperature T at the outlet of each fluid heater 1 is increased.
A method for controlling the number of fluid heaters, wherein the number of operating units is adjusted based on an average temperature Ta of zero. 4. A plurality of fluid heaters 1 are connected in parallel, these fluid heaters 1 and a load 7 are connected by a fluid supply line 8 and a fluid return line 9, and the number of operating the fluid heaters 1 Is controlled in accordance with the condition of the load 7, wherein all the fluid heaters 1 are connected by a circulation line 4, and the fluid is circulated in the circulation line 4. The fluid supply temperature T in the fluid supply line 8
A method for controlling the number of fluid heaters, wherein the number of operating units is adjusted based on out.