JP2006220363A - 1 pump heat source equipment - Google Patents

Abstract

[PROBLEMS] To reduce power consumption by optimizing the operation of a heat medium pump and a heat medium device in accordance with an external load, and at the same time, ensuring a water flow rate of the heat source device and avoiding instability.
SOLUTION: The heat pumps 3A to 3C can change the pump head, the flow meter 10 for measuring the circulation flow rate of the external load device 5, and the flow meter 11 for measuring the water flow rate of the heat source devices 2A to 2C. And a differential pressure gauge 12 that measures the differential pressure across the bypass valve 9 and controls the heads of the heat medium pumps 3A to 3C based on the circulation flow rate, and the water flow rate of the heat source device is bypassed. Controlled by the opening of the valve 9, the bypass valve opening is corrected so as to cancel the influence of the frequency change of the heat medium pumps 3A to 3C, and the heating medium pump 3A is canceled so as to cancel the influence of the bypass valve opening change. And a control device 15 that suppresses mutual interference by modifying the frequency of ˜3C.
[Selection] Figure 1

Description

  The present invention relates to a one-pump heat source facility used as a heat source supply system such as a district cooling and heating facility, or a heat source supply system such as a factory or a general building.

  As an increase / decrease stage control system for a one-pump heat source facility including a plurality of heat source device groups such as a refrigerator and a water heater, the one shown in FIG. 6 is known.

  The heat source system 50 includes first to third heat source devices 51A to 51C that heat or cool the heat medium, and each heat medium pump 52A to 52C that pumps the heat medium heated or cooled by each of the heat sources 51A to 51C. A feed header 53 that collects the heat medium pumped by the heat medium pumps 52A to 52C and sends it to the external load device 54, and a return header 55 that distributes the heat medium returned from the external load device 54 to the heat source devices 51A to 51C. The bypass header 56 connecting the feed header 53 and the return header 55 is provided. As a device for operation control, the pressure difference (ΔP) of the heat medium between the bypass valve 57 for adjusting the flow rate of the heat medium flowing through the bypass path 56 and the feed header 53 and the return header 55 is measured. Differential pressure gauge 58, thermometer 59 for detecting the temperature of the heat medium (outgoing water temperature TS) sent to the external load device 54, and temperature of the heat medium flowing into the heat source devices 51A to 51C (heat source device inflow temperature TI) , A flow meter 61 that measures the flow rate of the heat medium returned to the return header 55, and a control device 62 that controls the heat source devices 51A to 51C and the opening degree of the bypass valve 57.

  In the heat source facility 50, the heat medium pumped by the heat medium pumps 52A to 52C is cooled or heated by the heat source devices 51A to 51C, mixed in the feed header 53, and sent to the external load device 54 via the outgoing water pipeline. Supplied. And after heat exchange in the external load apparatus 54, it returns to the return header 55 via a return water pipe, is pumped by the heat medium pumps 52A-52C again, and circulates. In this heat medium circulation control, the control device 62 monitors the differential pressure (ΔP) between the feed header 53 and the return header 55, and the degree of opening of the bypass valve 57 so as to keep this differential pressure ΔP constant. That is, the flow rate of the heat medium flowing through the bypass path 56 is controlled, and the number of operating heat source devices 51A to 51C and the heat medium pumps 52A to 52C is controlled according to the load flow rate measured by the flow meter 61 (Patent Documents 1 to 5 below). (See 3 etc.).

  In the increase / decrease stage control of the heat source devices 51A to 51C, for example, one heat source device 51A and one corresponding heat medium pump 52A are operated first. The heat medium pump 52A is operated at a rated flow rate. In this state, for example, the heat medium is cooled to 5 ° C. in the heat source device 51 </ b> A, is heat-exchanged by the external load device 54, becomes a heat medium of 14 ° C., and is returned to the return header 55.

Thereafter, as the amount of heat required from the external load device 54 increases, the second heat source device 51B and the corresponding heat medium pump 52B are operated at a stage where the step increase threshold is exceeded. Furthermore, by operating the third heat source device 51C and the corresponding heat medium pump 52C at a stage where the step increase threshold is exceeded, the load heat amount increase / decrease of the external load device 54 is accommodated.
JP 2000-18683 A JP 2004-184052 A JP 2004-245560 A

  However, in the one-pump system heat source facility, the heat medium pumps 52A to 52C are operated at their ratings and the discharge pressure is kept constant, so that the flow rate in the heat source devices 51A to 51C is secured and destabilized (hunting, etc.) Therefore, there is a problem that the pump power cannot be reduced even at a small load.

  Moreover, in the said heat source apparatus 51A-51C, when it is a predetermined heat-medium temperature difference (in the said example, 9 degreeC), the maximum capability is exhibited. In practice, however, a phenomenon occurs in which the temperature difference between the return and return of water decreases, especially at a small load. This drop in the return temperature difference is due to excessive cold water flowing into the external load device 54 due to excessive opening of the valve or excessive pressure, insufficient air volume passing through the external load device 54, heat exchange, etc. May occur when the vessel is deteriorated, or it may be caused by the provision of a terminal bypass that bypasses the external load device 54, or an increase in the flow rate of the heat medium flowing through the bypass pipe 56. Although the heat medium pumps 52A to 52C are operating at a rated speed due to a decrease in the temperature difference between the return and return of the heat medium, the heat source devices 51A to 51C are operated with their own cooling ability reduced. It will be in the state which is doing. In this state, when the amount of heat required by the external load device 54 increases, the steps to the second and third heat source devices 51B and 51C are increased even though the first heat source device 51A is in the throttle operation. It was supposed to be done. That is, before each heat source device 51A exhibits its maximum capacity, unnecessary stages are added to the second and third heat source devices 51B and 51C, and an uneconomic operation is performed.

  Therefore, the main problem of the present invention is to reduce the power consumption by optimizing the operation of the heat medium pump and the heat medium device according to the external load, and at the same time, ensure the water flow rate of the heat source device and destabilize it. Is to provide a one-pump heat source facility.

In order to solve the above-mentioned problem, as the present invention according to claim 1, one or a plurality of heat source devices for cooling or heating the heat medium, and a heat medium cooled or heated provided corresponding to each heat source device A heat medium pump for pumping, a feed header for collecting the heat medium from the heat source device, an external load device to which the heat medium is supplied from the feed header, and a heat medium exchanged by the external load device are returned. A return header that is distributed to each heat source device, a bypass passage that connects the feed header portion or the vicinity thereof and the return header portion or the vicinity thereof, and a bypass valve that adjusts the flow rate of the heat medium flowing through the bypass passage. In one-pump heat source equipment,
The heat pump can change the pump head by frequency control, a flow meter for measuring a circulating flow rate circulating through the external load device, and a flow meter for measuring the water flow rate of the heat source device, A differential pressure gauge that measures the differential pressure across the bypass valve, and
In addition, the pump head is controlled by changing the frequency of the heat medium pump based on the circulating flow rate, and the amount of water passing through the heat source device is controlled by the opening of the bypass valve, and further bypassed to cancel the influence of the frequency change of the heat medium pump. And a controller for controlling the mutual interference to be suppressed by correcting the frequency of the heat medium pump so as to cancel the influence of the change of the bypass valve opening while correcting the valve opening. A one-pump heat source facility is provided.

  In the present invention according to the first aspect, the pump head can be changed by frequency control (the number of rotations) of a heat medium pump that has been operated at a rating. When the flow rate is reduced, the pump discharge pressure is lowered to prevent a drop in the return temperature difference and to reduce the pump power. On the other hand, if the predetermined amount of water flow is not ensured in the heat source device, instability such as hunting is caused. Therefore, the bypass valve is controlled so that the water flow amount of the heat source device is constant. At this time, the effect of changing the pump head and the effect of changing the opening of the bypass valve interfere with each other. Therefore, when the pump head changes, the operation to cancel the influence is corrected to the bypass valve opening. . In addition, when the bypass valve opening changes, the operation that cancels the influence is corrected to the pump operating frequency to suppress mutual interference, secure the water flow rate of the heat source equipment, and stabilize the operating state .

  As the present invention according to claim 2, the control for suppressing the mutual interference is based on the basic characteristics of the heat medium pump and the bypass valve, on condition that the bypass valve flow rate or the bypass valve differential pressure is constant. The one-pump heat source facility according to claim 1, wherein the non-interference control model is obtained from the relationship between the operation frequency and the opening degree of the bypass valve.

  As described above in detail, according to the present invention, the operation of the heat medium pump and the heat medium device is optimized for the external load, and at the same time, the power consumption is reduced, and the water flow rate of the heat source device is ensured. Stabilization can be avoided.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[Configuration of heat source equipment]
A one-pump heat source facility 1 shown in FIG. 1 is provided corresponding to a plurality of heat source devices 2A to 2C for cooling or heating a heat medium and each of the heat source devices 2A to 2C, and a heat medium that pumps the heat medium. Pumps 3 </ b> A to 3 </ b> C, a feed header 4 that collects the heat medium from the heat source devices 2 </ b> A to 2 </ b> C, an external load device 5 that is supplied with the heat medium from the feed header 4, and an air conditioning load provided in the external load device 5 The heating medium exchanged by the control valve 6 and the external load device 5 is returned, the return header 7 distributed to each of the heat source devices 2A to 2C, the feed header portion 4 or the vicinity thereof, and the return header portion 7 or the A bypass path 8 connecting the vicinity and a bypass valve 9 for adjusting the flow rate of the heat medium flowing through the bypass path 8 are provided. For this control, the heat medium pumps 3A to 3C are pumped by frequency control. The head can be changed And a flow meter 10 for measuring the circulation flow rate circulating through the external load device 5, a flow meter 11 for measuring the water flow rate of the heat source devices 2A to 2C, and the bypass valve 9 A differential pressure gauge 12 for measuring the differential pressure, a thermometer 13 for measuring the temperature of the outgoing water, a thermometer 14 for measuring the inflow temperature of the heat source equipment, and a heat medium pump based on the measured values by these measuring instruments A control device 15 that performs frequency control of 3A to 3C, opening degree control of the bypass valve 9 and the like is provided. In addition, you may make it provide the terminal bypass circuit 16 which bypasses the said external load apparatus 5 as shown with a broken line in FIG.

  Specifically, as shown in FIG. 5, the control device 15 increases the discharge pressure (lift) based on the circulating flow rate of the heat medium based on the request from the external load device 5 as shown in FIG. 5. As described above, the pump head is adjusted by proportionally controlling the frequency (rotational speed) of the heat medium pumps 3A to 3C so that the discharge pressure (lift) is reduced when the required circulation flow rate is reduced. As a result, when the external load device 5 is lightly loaded, the pump head is lowered by lowering the pump operating frequency to prevent the low-temperature forward chilled water from entering the return header 7 without heat exchange and reducing the pump power. Plan.

  Further, the opening degree of the bypass valve 9 is controlled in order to suppress the change in the water flow rate of the heat source device due to the change in the pump head. At this time, since the change in the pump head (pump operating frequency) and the change in the opening degree of the bypass valve are in an interfering relationship with each other, the bypass valve is designed to cancel the influence of the frequency change in the heat medium pumps 3A to 3C. 9 is corrected, and the frequency of the heat medium pumps 3 </ b> A to 3 </ b> C is corrected so as to suppress the mutual interference so as to cancel the influence of the change in the opening of the bypass valve 9.

  The control for suppressing the mutual interference in the control device 15 is based on the basic characteristic of the heat medium pumps 3A to 3C and the basic characteristic of the bypass valve 9 on the condition that the bypass valve flow rate or the bypass valve differential pressure is constant. The following non-interference model (part 1) and non-interference model (part 2) obtained from the relationship between the operation frequency of the pumps 3A to 3C and the opening degree of the bypass valve 9 are assumed to be executed.

[Non-interference control model]
Hereinafter, the non-interference control model (part 1) for correcting the opening degree of the bypass valve 9 so as to cancel the influence of the frequency change of the heat medium pumps 3A to 3C, and the influence of the opening degree change of the bypass valve 9 are canceled out. The non-interference control model (part 2) for correcting the frequency of the heat medium pumps 3A to 3C will be described in detail.

(1) Non-interference control model (1)
The non-interference control model (part 1) corrects the opening degree of the bypass valve 9 so that the bypass flow rate does not change even when the bypass valve differential pressure changes.

  First, the following expressions (1) to (3) are established as basic characteristics of the heat medium pump 3.

  The following equation (1) is established as a relational expression between the pump head and the operating frequency.

  Next, the following equation (2) is established as a relational expression between the pump flow rate and the pump operation frequency.

  Further, the following equation (3) is established as a relational expression between the pump head and the bypass valve differential pressure.

The pump head fluctuation range (dP _n = P _n −P _n−1 ) after changing the operating frequency is expressed by the following expression (4) from the above expressions (1) and (3) (see FIG. 3).

  After the operation frequency is changed, not only the pump head but also the flow rate fluctuates, but it is assumed that the fluctuation range is small and can be ignored.

Therefore, the bypass valve differential pressure (Pb _n ) after changing the operating frequency is expressed by the following equation (5).

  Next, a valve opening is calculated in which the bypass flow rate (Qb) does not vary even if the bypass valve differential pressure varies.

  The relationship among the flow rate (Qb) of the bypass valve, the valve opening characteristic (Cv), and the valve differential pressure (Pb) is expressed by the following equation (6).

  In the case of linear characteristics, the flow coefficient when the arbitrary bypass valve is opened is expressed by the following equation (7).

  When the above equation (6) is solved for the bypass valve flow rate (Qb), the bypass valve flow rate Qb after changing the operating frequency is expressed by the following equation (8).

  The bypass valve flow rate (Qb) before changing the operating frequency is expressed by the following equation (9).

  Accordingly, since the bypass valve flow rate (Qb) does not change, the following equation (10) is established from the above equations (7) to (9).

When the above equation (10) is solved for σ _n , the following equation (11) is obtained.

  Therefore, the opening degree σn of the bypass valve 9 that cancels the influence of the change of the pump operation frequency can be obtained by the above equation (11).

(2) Non-interference control model (2)
The non-interference control model (part 2) corrects the pump operation frequency so that the bypass valve differential pressure Pb does not change even when the bypass flow rate Qb changes.

  First, when the bypass valve differential pressure Pb after the bypass valve opening change is solved using the above equation (6), the following equation (12) is obtained.

  Therefore, the bypass valve differential pressure Pb before the bypass valve opening change is expressed by the following equation (13).

  Since the bypass valve differential pressure Pb does not change, the following equation (14) is established from the above equations (7), (12), and (13).

Bypass flow rate Qb _n after bypass valve opening changes, the following equation from the above equation (14) (15).

Further, the fluctuation range (dQb _n = Qb _n −Qb _n−1 ) of the bypass flow rate after changing the bypass valve opening is expressed by the following equation (16).

When the pump flow rate before changing the bypass valve is Q _n-1 and the pump flow rate after changing the bypass valve opening is Q _n , the following equation (17) is established (see FIG. 4).

After changing the bypass valve opening, not only the pump flow but also the head fluctuates, but the fluctuation range is small, so assuming that it can be ignored, the basic characteristic equation of the pump (3) and (17) The pump operating frequency INV _n after the bypass valve opening change is _expressed by the following equation (18).

Therefore, the pump operating frequency INV _n that cancels the influence of the change in the bypass valve opening can be obtained by the above equation (18).

It is a block diagram of 1 pump system heat source equipment 1 concerning the present invention. It is a conceptual diagram of a non-interference control model. It is a pump head fluctuation state figure of a non-interference control model (the 1). It is a bypass flow rate fluctuation | variation state figure of a non-interference control model (the 2). It is a correlation conceptual diagram of a pump head and flow volume. It is a block diagram of the conventional 1 pump system heat source equipment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... 1 pump system heat source equipment, 2A-2C ... Heat source equipment, 3A-3C ... Heat medium pump, 4 ... Feed header, 5 ... External load equipment, 6 ... Air-conditioning load control valve, 7 ... Return header, 8 ... Bypass path , 9: Bypass valve, 10.11 ... Flow meter, 12 ... Differential pressure gauge, 13.14 ... Thermometer, 15 ... Control device

Claims (2)

One or a plurality of heat source devices that cool or heat the heat medium, a heat medium pump that is provided corresponding to each heat source device, and that pumps the cooled or heated heat medium, and the heat medium from the heat source device are aggregated A feed header, an external load device to which a heat medium is supplied from the feed header, a heat header exchanged by the external load device and a return header distributed to each heat source device, and the feed header unit or In a one-pump heat source facility comprising a bypass path connecting the vicinity thereof and the return header portion or the vicinity thereof, and a bypass valve for adjusting the flow rate of the heat medium flowing through the bypass path,
The heat pump can change the pump head by frequency control, and the flow meter for measuring the circulation flow rate circulating through the external load device, the flow meter for measuring the water flow rate of the heat source device, A differential pressure gauge that measures the differential pressure across the bypass valve, and
In addition, the pump head is controlled by changing the frequency of the heat medium pump based on the circulating flow rate, and the amount of water passing through the heat source device is controlled by the opening of the bypass valve, and further bypassed to cancel the influence of the frequency change of the heat medium pump. And a controller for controlling the mutual interference to be suppressed by correcting the frequency of the heat medium pump so as to cancel the influence of the bypass valve opening change while correcting the valve opening. 1 pump heat source equipment. The control for suppressing the mutual interference is based on the basic characteristics of the heat medium pump and the bypass valve, on the condition that the bypass valve flow rate or the bypass valve differential pressure is constant, the operating frequency of the heat medium pump and the bypass valve opening. The one-pump heat source facility according to claim 1, wherein the non-interference control model is obtained from the relationship.

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