JP4173981B2 - Secondary pump type heat source variable flow rate control method and secondary pump type heat source system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
This invention relates to a secondary pump system heat source variable flow rate that controls the rotational speed of a primary pump provided as an auxiliary to the heat source device in operation according to the flow rate (load flow rate) of the heat source water returned to the return header. The present invention relates to a control method and a secondary pump type heat source system.
[0002]
[Prior art]
FIG. 4 shows an instrumentation diagram of a conventional secondary pump type heat source system (see, for example, Patent Document 1). In the figure, 1-1 to 1-N are heat source units for generating heat source water, and 2-1 to 2-N are individual units in the circulation path of the heat source water generated by heat source units 1-1 to 1-N. 1 is a primary pump, 3 is a forward header that mixes heat source water from the heat source devices 1-1 to 1-N, 4 is a forward water line, and 5 is forwarded from the forward header 3 via a forward water line 4. A load device (air conditioner) that receives supply of incoming heat source water, 6 is a return water pipe.
[0003]
Reference numeral 7 denotes a return header in which heat is exchanged in the load device 5 and the heat source water sent via the return water pipe 6 is returned. Reference numeral 8 denotes a bypass pipe that connects the forward header 3 and the return header 7. Reference numeral 10 denotes the forward header 3. A water pressure gauge for measuring the water supply pressure PS from the heat source water, 11 is a water temperature sensor for measuring the temperature of the heat source water from the forward header 3 to the load device 5 as the water temperature TS, and 12 is returned to the return header 7. A return water temperature sensor that measures the temperature of the heat source water as the return water temperature TR, 13 is a flow meter that measures the flow rate (load flow rate) F of the heat source water returned to the return header 7, and 14 is a control device.
[0004]
The forward header 3 is composed of a first forward header 3-1 and a second forward header 3-2. Between the forward header 3-1 and the forward header 3-2, the forward header 3-1 Secondary pumps 16-1 to 16-M are provided for pumping the heat source water to the forward header 3-2. Secondary pumps 16-1 to 16-M are provided with inverters 17-1 to 17-M.
[0005]
In this secondary pump type heat source system, the water supplied by the primary pumps 2-1 to 2-N is converted into heat source water by the heat source units 1-1 to 1-N, mixed in the forward header 3, and the forward water pipe. It is supplied to the load device 5 via the path 4. And it heat-exchanges in the load apparatus 5, is returned to the return header 7 via the return water pipe 6, is pumped again by the primary pumps 2-1 to 2-N, and circulates the above path | route. For example, when the heat source devices 1-1 to 1-N are refrigerators, the heat source water is cold water and circulates through the above-described path. When the heat source devices 1-1 to 1-N are heaters, the heat source water is warm water and circulates through the above-described path.
[0006]
The control device 14 monitors the water supply pressure PS of the heat source water from the water supply pressure gauge 10, and controls the number of operating and the number of rotations of the secondary pumps 16-1 to 16-M so that the water supply pressure PS is constant. On the other hand, the current load is expressed as F × (TR−TS) = Q from the water temperature TS from the water temperature sensor 11, the return water temperature TR from the return water temperature sensor 12, and the load flow rate F from the flow meter 13. The amount of heat Q is obtained, and the number of operating heat source devices 1-1 to 1-N is controlled in accordance with the obtained present amount of load heat Q or load flow rate F.
[0007]
For example, according to a predetermined operation order table, the control device 14 operates the heat source unit 1-1 of the designated rank 1 until the load heat quantity Q reaches a predetermined value Q1, and the load heat quantity Q has a predetermined value Q1. If exceeded, in addition to the heat source device 1-1, the operation of the heat source device 1-2 of the designated rank 2 is started. During the operation of the heat source units 1-1 and 1-2, the primary pumps 2-1 and 2-2 provided for the heat source units 1-1 and 1-2 are operated at a rated speed, A constant flow rate is supplied to the forward header 3 respectively. In the case of the load flow rate F, the number of operating heat source devices 1-1 to 1-N can be controlled in the same manner as in the case of the load heat amount Q.
[0008]
[Patent Document 1]
Japanese Unexamined Patent Publication No. 2002-89935 (page 4-6, FIG. 1)
[0009]
[Problems to be solved by the invention]
However, in the conventional secondary pump type heat source system described above, the heat source water having a constant flow rate regardless of the load flow rate F supplied to the load device 5 by the primary pump 2 provided for the heat source device 1 in operation. As a result, surplus heat source water flows through the bypass pipe 8 and waste of the conveyance power by the primary pump 2 has occurred.
[0010]
Note that the flow rate Fb of the heat source water flowing through the bypass pipe 8 is monitored, and the rotation speed of the primary pump 2 provided for the heat source machine 1 in operation is controlled so that the flow rate Fb approaches zero. Can be considered. However, for this purpose, a flow meter must be newly installed in the bypass line 8. In the existing secondary pump type heat source system, it is difficult to install a flow meter in the bypass line 8, and there is also a problem that initial cost is required when newly installing the flow meter.
[0011]
The present invention has been made in order to solve such problems. The object of the present invention is to transfer the flow rate flowing through the bypass line close to zero without newly providing a flow meter in the bypass line. It is an object of the present invention to provide a secondary pump type heat source variable flow rate control method and a secondary pump type heat source system that can save power and save energy.
[0012]
[Means for Solving the Problems]
In order to achieve such an object, the present invention uses an existing flow meter provided for obtaining the load heat quantity in the above-described secondary pump heat source system, and the load flow rate measured by this flow meter. The apportioning flow rate Fi per unit of heat source currently operating is obtained from F, and the rotation speed of the primary pump provided for the heat source unit currently operating is controlled according to the apportioning flow rate Fi. It is a thing. The apportioning flow rate Fi can be obtained by dividing the load flow rate F by the number n of operating heat source devices if the rating of the primary pump of each heat source device is the same. Moreover, what is necessary is just to weight with the rating of each pump, when the ratings of the primary pump of a heat source machine differ.
[0013]
According to this invention, the rotation speed of the primary pump provided with respect to the heat source machine currently operated according to the proportional distribution flow Fi is controlled. At this time, by controlling the number of rotations of the primary pump so that heat source water having a proportional flow rate Fi is output from the operating heat source unit, the total flow rate of the heat source water output from the operating heat source unit is loaded. It becomes equal to the flow rate F, and the flow rate of the heat source water flowing through the bypass pipe becomes zero.
[0014]
In the present invention, when the apportioning flow rate Fi is smaller than the minimum passing flow rate FGmin determined in advance for the heat source machine, the control value corresponding to the minimum passing flow rate is set as the lower limit value, and the The number of revolutions of the primary pump provided for the currently operating heat source unit is controlled. By doing so, it becomes possible to prevent the amount of heat source water output from the operating heat source unit from falling below the minimum passing flow rate FGmin, and there is a possibility of an operation that may occur due to falling below the minimum passing flow rate FGmin. It becomes possible to prevent abnormal stop of the heat source machine inside. In this case, the sum of the flow rates of the heat source water output from the operating heat source machine is larger than the load flow rate F, but the difference is slight and flows through the bypass pipeline as an excess.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is an instrumentation diagram of a secondary pump type heat source system used for implementing a secondary pump type heat source variable flow rate control method according to the present invention. 4, the same reference numerals as those in FIG. 4 denote the same or equivalent components as those described with reference to FIG. 4, and the description thereof will be omitted.
[0016]
In this embodiment, the primary pumps 2-1 to 2-N are provided with inverters 15-1 to 15-N, and an inverter output (INV output) is given to the inverters 15-1 to 15-N from the control device 14A. The rotation speeds of the primary pumps 2-1 to 2-N are controlled.
[0017]
The control device 14A is realized by hardware including a processor and a storage device, and a program that realizes various functions in cooperation with the hardware. The control device 14A has a heat source variable flow rate control function as one of its characteristic functions.
[0018]
[Control of the number of operating units]
The control device 14A monitors the water supply pressure PS of the heat source water from the water supply pressure gauge 11, and controls the number of operating and the number of rotations of the secondary pumps 15-1 to 15-M so that the water supply pressure PS is constant. On the other hand, the current load is expressed as F × (TR−TS) = Q from the water temperature TS from the water temperature sensor 11, the return water temperature TR from the return water temperature sensor 12, and the load flow rate F from the flow meter 13. The amount of heat Q is obtained, and the number of operating heat source devices 1-1 to 1-N is controlled in accordance with the obtained present amount of load heat Q or load flow rate F.
[Heat source variable flow control]
The control device 14A obtains a prorated flow rate Fi by dividing the load flow rate F measured by the flow meter 13 by the number n of operating heat source units that are currently operating (step 201 shown in FIG. 2).
[0019]
Then, an INV output corresponding to the apportioned flow Fi obtained in step 201 is obtained with reference to a table (INV output table) showing the relationship between the apportioned flow and INV output prepared in advance (step 202).
[0020]
In this embodiment, a unique INV output table is prepared for each of the primary pumps 2-1 to 2-N, and the primary pump 2 provided for the heat source unit 1 in operation is provided. For each, an INV output corresponding to the prorated flow rate Fi is obtained by referring to its own INV table.
[0021]
FIG. 3 shows an example of the INV output table. This INV output table TA1 is prepared for the primary pump 2-1, for example. Similar INV output tables TA2 to TAN are prepared for the primary pumps 2-2 to 2-N. These INV output tables TA1 to TAN are created based on actually measured values and set in the control device 14A.
[0022]
[Create INV output table]
In this secondary pump heat source system, the piping resistance of the secondary pump 16 varies depending on the load due to a temperature control two-way valve (not shown) provided in the load device 5. Since there is no primary pipe that is provided with the pump 15 that changes the resistance unlike a two-way valve, the pipe resistance of the primary pump 15 is almost constant regardless of load fluctuations. From this, there is a proportional relationship between the pump speed of the primary pump 15 and the flow rate.
[0023]
Based on the proportional relationship between the pump speed and the flow rate, the secondary pump heat source system creates the INV output table as follows. Explaining with the INV output table TA1 shown in FIG. 3, a flow meter for investigation (not shown) such as an ultrasonic flow meter is set in the pipe (primary pipe) provided with the primary pump 2-1. To do. The primary pump 2-1 is operated with the pump discharge valve (not shown) for flow rate adjustment fully opened and the INV output set to 100%.
[0024]
The flow rate measured by the survey flowmeter is monitored, and if the flow rate exceeds the rated water volume, the INV output is lowered so that the rated water volume is reached. The INV output at this time is recorded as the upper limit value INVmax of the INV output with respect to the proportional flow rate Fi. Next, the INV output is lowered by about 5 to 10%, and the flow rate measured by the flow meter for investigation at that time is recorded in correspondence with the INV output.
[0025]
A minimum passage flow rate FG1min is determined for the heat source device 1-1. If the passage flow rate FG1 of the heat source device 1-1 is lower than the minimum passage flow rate FG1min, the heat source device 1-1 in operation may be abnormally stopped. Therefore, the INV output at which the flow rate measured by the flow meter for investigation becomes the minimum passing flow rate FG1min of the heat source device 1-1 is investigated, and the INV output at this time is recorded as the lower limit value INVmin of the INV output with respect to the apportioned flow rate Fi. .
[0026]
The INV output table TA1 is created from the INVmax recorded in this way, INVmin, and the flow rate for the INV output at intervals of 5 to 10% between INVmax and INVmin. Similarly, the INV output tables TA2 to TAN are created for the primary pumps 2-2 to 2-N.
[0027]
The control device 14A obtains the INV output corresponding to the apportioned flow Fi obtained in step 202, that is, the INV output obtained for each of the primary pumps 2 provided for the heat source unit 1 in operation. 2 is provided to the inverter 15 provided for 2 (step 203). Thereby, the rotation speed of the primary pump 2 provided with respect to the heat-source equipment 1 in operation is controlled according to the INV output from 14 A of control apparatuses, and apportioning flow amount Fi of each of the heat-source equipment 1 in operation is controlled. Heat source water is output.
[0028]
In this case, the total flow rate of the heat source water output from the operating heat source unit 1 is equal to the load flow rate F. Therefore, the flow rate Fb of the heat source water flowing through the bypass pipe 8 becomes zero, so that conveyance power is not wasted and energy saving is achieved. Further, since it is not necessary to monitor the flow rate Fb of the heat source water flowing through the bypass pipe 8, it is not necessary to newly install a flow meter in the bypass pipe 8.
[0029]
As can be understood from the above description, in the present embodiment, the flow meter 13 for obtaining the load heat quantity Q is used, and the proportional flow rate Fi is obtained based on the load flow rate F measured by the flow meter 13. Therefore, it is not necessary to newly provide a flow meter in the bypass conduit 8, and the initial cost can be suppressed as much as possible to save energy.
[0030]
[When load flow F is small]
In this embodiment, when the load flow rate F is small, the proportional flow rate Fi obtained by dividing the load flow rate F by the number n of the heat source units 1 in operation is also small. In this case, taking the INV output to the inverter 15-1 as an example, the INV output to the inverter 15-1 is equal to or less than INVmin even if the prorated flow rate Fi is lower than the minimum passing flow rate FG1min of the heat source unit 1-1. There is no. That is, as can be seen from the inverter output table TA1 shown in FIG. 2, the INV output to the inverter 15-1 is held at INVmin, which is a control value corresponding to the minimum passing flow rate FG1min, in the range of the proportional flow rate Fi ≦ FG1min. .
[0031]
Therefore, even if the load flow rate F decreases and the apportioning flow rate Fi becomes smaller than the minimum passing flow rate FG1min of the heat source device 1-1, there is no problem that the operating heat source device 1-1 is abnormally stopped. . The same applies to the other heat source units 1 in operation. In this case, the total flow rate of the heat source water output from the operating heat source unit 1 is larger than the load flow rate F, but the difference is slight and flows through the bypass line 8 as a surplus. Absent.
[0032]
In this embodiment, the following auxiliary logics (1) and (2) are provided as auxiliary logic for variable flow rate control.
(1) Forced rated flow operation when the heat source unit is stopped When the heat source unit is stopped, the primary pump is forcibly returned to the rated operation for a certain time (about the remaining operation time).
(2) Limiting the inverter control speed If the pump water amount is fluctuated earlier than the capacity control of the heat source unit, the capacity control may not catch up with the water amount change and an accident such as freezing may occur in the heat source unit. For this reason, the speed of the inverter control of the primary pump is limited by a change rate limit function or the like.
[0033]
【The invention's effect】
As is clear from the above description, according to the present invention, an existing flow meter provided for obtaining the load heat quantity is diverted, and the heat source currently operated from the load flow rate F measured by the flow meter. Since the apportioned flow rate Fi per unit is obtained and the rotation speed of the primary pump provided for the currently operating heat source device is controlled in accordance with the apportioned flow rate Fi, the operating heat source By controlling the number of revolutions of the primary pump so that heat source water with a proportional flow rate Fi is output from the machine, the total flow rate of heat source water output from the heat source machine in operation is made equal to the load flow rate F, and bypass Without newly providing a flow meter in the pipe line, the flow rate of the heat source water flowing through the bypass pipe line can be made close to zero, thereby eliminating waste of conveyance power and saving energy.
[0034]
Further, when the apportioning flow rate Fi is smaller than the predetermined minimum flow rate FGmin for the heat source unit, the control value corresponding to the minimum flow rate is set as the lower limit value, and the current operation is performed according to the lower limit value. The amount of heat source water output from the operating heat source unit is controlled to be less than the minimum passing flow rate FGmin by controlling the rotation speed of the primary pump provided for the existing heat source unit. The machine can be prevented from stopping abnormally. In this case, the total flow rate of the heat source water output from the operating heat source unit is larger than the flow rate F of the heat source water returned to the return header, but the difference is slight, and the bypass pipe line is used as an excess. There is no problem because it flows.
[Brief description of the drawings]
FIG. 1 is an instrumentation diagram of a secondary pump type heat source system used for implementing a secondary pump type heat source variable flow rate control method according to the present invention.
FIG. 2 is a flowchart for explaining a heat source variable flow rate control function provided in the control device of the secondary pump type heat source system.
FIG. 3 is a diagram showing an example of an INV output table set in the control device of the secondary pump heat source system.
FIG. 4 is an instrumentation diagram of a conventional secondary pump heat source system.
[Explanation of symbols]
1 (1-1 to 1-N) ... heat source machine, 2 (2-1 to 2-N) ... primary pump, 3 ... forward header, 3-1 ... first forward header, 3-2 ... second Outgoing header, 4 ... Outbound water pipe, 5 ... Load equipment (air conditioner), 6 ... Return water pipe, 7 ... Return header, 8 ... Bypass pipe, 10 ... Water pressure gauge, 11 ... Outbound water temperature sensor, 12 ... Return water temperature sensor, 13 ... Flow meter, 14A ... Control device, 15 (15-1 to 15-N) ... Inverter, 16 (16-1 to 16-M) ... Secondary pump, 17 (17-1 to 17) 17-M). Inverter.

Claims (4)

First to N-th (N ≧ 2) heat source units for generating heat source water, and first to N-th primary pumps provided as an auxiliary unit for the first to N-th heat source units, A first forward header that mixes the heat source water from the first to Nth heat source units, and one or more secondary pumps that pump the heat source water from the first forward header to the second forward header; The load device that receives the supply of heat source water from the second forward header, the return header to which the heat source water heat-exchanged in the load device is returned, and the first forward header and the return header are communicated with each other. A bypass pipe, an outward water temperature sensor that measures the temperature of the heat source water from the second forward header to the load device as the forward water temperature, and a temperature of the heat source water that is returned to the return header as the return water temperature Return water temperature sensor and the flow rate of the heat source water returned to the return header as load flow rate A flow meter to be measured, a forward water temperature measured by the forward water temperature sensor, a return water temperature measured by the return water temperature sensor, a load flow rate measured by the flow meter, or a load measured by the flow meter In a secondary pump heat source system comprising a control device that determines a current load heat quantity based on a flow rate and controls the number of operating heat source units based on the obtained current load heat quantity,
From the flow rate of the heat source water measured by the flow meter, obtain a prorated flow rate per unit of the heat source that is currently operating,
A secondary pump type heat source variable flow rate control method, characterized in that the number of revolutions of the primary pump provided for the heat source machine that is currently operating is controlled in accordance with the proportional flow rate. In the secondary pump type heat source variable flow rate control method according to claim 1,
When the apportioned flow rate is smaller than a predetermined minimum flow rate for the heat source unit, a control value corresponding to the minimum flow rate is set as a lower limit value, and the heat source currently operated according to the lower limit value A secondary pump type heat source variable flow rate control method, characterized in that the number of revolutions of the primary pump provided for the machine is controlled. First to N-th (N ≧ 2) heat source units for generating heat source water, and first to N-th primary pumps provided as an auxiliary unit for the first to N-th heat source units, A first forward header that mixes the heat source water from the first to Nth heat source units, and one or more secondary pumps that pump the heat source water from the first forward header to the second forward header; The load device that receives the supply of heat source water from the second forward header, the return header to which the heat source water heat-exchanged in the load device is returned, and the first forward header and the return header are communicated with each other. A bypass pipe, an outward water temperature sensor that measures the temperature of the heat source water from the second forward header to the load device as the forward water temperature, and a temperature of the heat source water that is returned to the return header as the return water temperature Return water temperature sensor and the flow rate of the heat source water returned to the return header as load flow rate A flow meter to be measured, a forward water temperature measured by the forward water temperature sensor, a return water temperature measured by the return water temperature sensor, a load flow rate measured by the flow meter, or a load measured by the flow meter In a secondary pump heat source system comprising a control device that determines a current load heat quantity based on a flow rate and controls the number of operating heat source units based on the obtained current load heat quantity,
An apportioning flow rate calculating means for obtaining an apportioning flow rate per unit of the heat source that is currently operated from the load flow rate measured by the flow meter;
Control means for controlling the rotational speed of the primary pump provided for the heat source machine that is currently operated according to the apportioned flow rate calculated by the apportioned flow rate calculating means. Secondary pump heat source system. In the secondary pump type heat source system according to claim 3,
When the apportioning flow rate is smaller than a predetermined minimum passage flow rate for the heat source device, the control means replaces the apportioning flow rate with the minimum passage flow rate, and for the heat source device that is currently operating. The secondary pump type heat source system characterized by controlling the rotation speed of the primary pump provided.

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