JP2009036422A - Heat source system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat source system capable of inexpensively controlling the variable flow rate of a primary pump with a very simple structure, improving energy saving effect and cost reduction, and contributing to diversification proposed by ESCO, and excellent in economical efficiency and environmental protection. <P>SOLUTION: A PLC(programmable logic controller) 7 is connected to the primary pump 3a connected to a hot water heat exchanger 1 and a heat pump refrigerator 2 as a controller for controlling the variable flow rate of the primary pump 3a. A flow rate setting part 8 for setting the flow rate of the primary pump 3a and an inverter control part 9 for inverter-controlling the primary pump 3a by an inverter frequency derived from the flow rate value set by the flow rate setting part 8 is assembled in the PCL 7. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a variable flow rate heat source system having a primary pump and a secondary pump, and more particularly to a heat source system that performs variable flow rate control of a primary pump connected to a heat exchanger that is a primary heat source.

  Currently, environmental issues are being taken up from a global perspective, and the ESCO business is known as a business that continuously and comprehensively provides energy saving effects without compromising environmental harmony. In such an ESCO business field, a variable flow rate heat source system has gained high demand, and various proposals have been made (for example, Patent Document 1).

  The variable flow rate heat source system is divided into a primary system and a secondary system, and includes a primary pump and a secondary pump. In this system, the variable flow rate of each pump is controlled according to the load flow rate connected to the secondary system side. Therefore, the conveyance power of both pumps can be optimized, and the energy saving effect is remarkable.

  Here, the variable flow rate heat source system will be described in detail with reference to FIG. As shown in FIG. 3, three secondary pumps 4 are provided on the secondary system side. In the primary system, two hot water heat exchangers 1 and two heat pump refrigerators 2 are installed as heat sources. A primary pump 3 a is connected to each hot water heat exchanger 1, and a primary pump 3 b is connected to each heat pump refrigerator 2. That is, the primary pump 3a is a primary pump of the heat exchanger system, and the primary pump 3b is a primary pump of the heat pump system.

  Further, on the primary system side, a bypass pipe 5 is disposed so as to connect the upstream side of the hot water heat exchanger 1 and the heat pump refrigerator 2 and the downstream side of the primary pump 3. An excessive flow rate (difference between the primary flow rate and the secondary flow rate) is recirculated in the primary system. An electromagnetic flow meter 6 is installed in the bypass pipe 5, and a primary pump control unit 10 that controls the primary pumps 3 a and 3 b is connected to the electromagnetic flow meter 6.

  In the variable flow rate heat source system as described above, the secondary pump 4 captures the load flow rate as pressure, and the variable flow rate of the secondary pump 4 is generally controlled so that this pressure is constant. Is. On the other hand, it is ideal that the primary flow rate of the primary pumps 3a and 3b is controlled to be equal to the load flow rate of the secondary pump 4. This is to further enhance the energy saving effect by minimizing the conveyance power of the primary pumps 3a and 3b.

  However, if the primary flow rate is controlled so as to be always the same as the load flow rate, when the load flow rate increases rapidly, the primary flow rate value cannot follow this and becomes smaller than the load flow rate. In this case, there is a risk that the flow rate flowing to the primary heat source does not reach a predetermined minimum flow rate. In particular, regarding the heat pump refrigerator 2 that is the primary heat source, if the state of the minimum flow rate or less continues, there is a risk of failure stop, which is a serious problem.

  Therefore, the risk that the primary flow rate is lower than the secondary flow rate (load flow rate) must be avoided. In order to stabilize the heat source system, the primary flow rate by the primary pumps 3a and 3b is less than the secondary flow rate by the secondary pump 4. It is necessary to set so that the next flow rate must be exceeded. Specifically, the number of the primary pumps 3a and 3b is controlled so as to be equal to or higher than the flow rate of the secondary pump 4. At this time, since a difference between the primary flow rate and the secondary flow rate (load flow rate) is generated, this becomes the surplus flow rate. The excess flow is recirculated in the primary system via the bypass pipe 5.

  However, as described above, from the viewpoint of enhancing the energy saving effect, it is desirable that the primary flow rate by the primary pumps 3a and 3b is close to the secondary flow rate by the secondary pump 4, and the surplus flow rate has never been reduced. . In order to realize this, it is important to accurately grasp the primary flow rate, and the electromagnetic flow meter 6 is used in the conventional example shown in FIG.

That is, the surplus flow value is strictly measured by the electromagnetic flow meter 6 installed in the bypass pipe 5, and the surplus flow value is made as close to 0 as possible based on the measurement result. The primary pump control unit 10 finely controls the variable flow rates of the primary pumps 3a and 3b so that the value does not become negative.
JP 2002-89935 A

  However, the following problems have been pointed out in the above prior art. That is, in the conventional example shown in FIG. 3, the electromagnetic flow meter 6 is installed in the bypass pipe 5 in order to accurately measure the surplus flow rate. The electromagnetic flow meter 6 is very expensive and the cost is increased. In particular, when the electromagnetic flow meter 6 is added to the existing equipment, the renovation work is very expensive and has become a problem.

  When the heat source system is applied to the ESCO business, the increase in cost extends the cost recovery period due to the energy-saving effect, and the economic efficiency decreases as a whole. In recent years when the ESCO business has become active, it has been requested to expand the scope of ESCO proposals, and the development of a heat source system that can freely select a balance between energy saving effect and cost has been desired.

  The present invention has been proposed in view of such a situation, and an object of the present invention is to implement variable flow rate control of a primary pump at a low cost with an extremely simple configuration, and to improve energy saving effect and cost reduction. At the same time, it is to provide an economical and environmentally friendly heat source system that can contribute to the diversification of ESCO proposals.

  In order to achieve the above object, the present invention provides a heat source system including a primary pump and a secondary pump having variable flow rates, and including at least a heat exchanger as a heat source of a primary system connected to the primary pump. Based on the load flow rate of the secondary pump, the flow rate value setting means for setting the flow rate value that the primary pump supplies to the heat exchanger, and the flow rate value is proportional to the inverter frequency at the rated flow rate, Inverter frequency is determined from the flow rate value set by the flow rate value setting means, and inverter control means for controlling the flow rate of the primary pump connected to the heat exchanger based on the inverter frequency is provided. It is said.

  In the heat exchanger as the primary system heat source, the outlet side temperature becomes unstable when the minimum flow rate is interrupted. In other words, even if the heat exchanger has a minimum flow rate, the outlet side temperature only becomes unstable. That is, it is not necessary to strictly control the flow rate as compared with a heat source such as a heat pump that may cause a failure unless the minimum flow rate is reached.

  Therefore, in the present invention, the flow rate value setting means sets the flow rate value of the primary pump of the heat exchanger system based on the load flow rate of the secondary pump, and determines the inverter frequency from the flow rate value set by the inverter control means. Therefore, variable flow control can be performed for the primary pump of the heat exchanger system by inverter control based on the inverter frequency.

  According to the present invention as described above, the flow rate value of the primary pump of the heat exchanger system can be set based on the load flow rate of the secondary pump, and the variable flow rate control of the primary pump can be performed at this set flow rate value. Without using expensive measuring means such as an electromagnetic flow meter, variable flow control of the primary pump can be performed inexpensively and reliably, thereby improving energy saving effect and reducing costs, and diversifying ESCO proposals As a result, we were able to provide an economical and environmentally friendly heat source system.

[Configuration of Representative Embodiment]
Hereinafter, the best mode for carrying out the present invention (hereinafter referred to as “embodiment”) will be specifically described with reference to FIG. FIG. 1 is a configuration diagram of the present embodiment. The same members as those in the prior art shown in FIG.

  As shown in FIG. 1, a PLC (programmable logic controller) 7 is connected to the primary pump 3a and the heat pump refrigerator 2 connected to the hot water heat exchanger 1 as a control device for controlling the variable flow rate of the primary pump 3a. Has been. The PLC 7 includes a flow rate value setting unit 8 that sets the flow rate value of the primary pump 3a, and an inverter control unit 9 that controls the primary pump 3a with an inverter frequency derived from the flow rate value set by the flow rate value setting unit 8. It has been incorporated. The primary pump 3a is provided with an inverter frequency input unit 3c for inputting an inverter frequency from the inverter control unit 9.

  In the PLC 7, the flow rate setting unit 8 is a part that subtracts the rated flow rate of the heat pump refrigerator 2 from the load flow rate of the secondary pump 4 and sets the flow rate value that the primary pump 3 a supplies to the hot water heat exchanger 1. In this embodiment, since there are two hot water heat exchangers 1, the flow rate value obtained by further reducing the subtraction result to ½ is the set value for each hot water heat exchanger 1. In addition, regarding the heat pump refrigerator 2 that may break down when the minimum flow rate is interrupted, the primary flow rate is set as the rated flow rate, not the variable flow rate control.

  The inverter control unit 9 assumes that the flow rate value of the hot water heat exchanger 1 is proportional to the inverter frequency at the rated flow rate, and carries a flow rate-Hz characteristic (see the graph in FIG. 2) by a program as a linear relationship with each other. Based on this program, the inverter frequency corresponding to the flow rate value of the primary pump 3a set by the flow rate value setting unit 8 is determined, and the inverter frequency is input to the inverter frequency input unit 3c of the primary pump 3a. When input, the primary pump 3a performs inverter control.

[Operational effects of this embodiment]
The operational effects of the present embodiment having the above-described configuration are as follows. First, the flow rate value setting unit 8 subtracts the rated flow rate of the heat pump refrigerator 2 from the load flow rate of the secondary pump 4 to set the flow rate value of the primary pump 3a of the heat exchanger 1 system. Then, the inverter control unit 9 calculates the inverter frequency from the flow rate value set by the flow rate setting unit 8 based on the flow rate-Hz characteristic shown in the graph of FIG. 2, and the inverter frequency input unit 3c inputs this inverter frequency. The primary pump 3a can inverter-control the variable flow rate.

  If the load flow rate of the secondary pump 4 increases, the difference between the load flow rate of the secondary pump 4 and the rated flow rate of the heat pump refrigerator 2 increases, so the flow rate setting of the primary pump 3a derived from the subtraction result of both The value gets bigger. Therefore, as the set value increases, the inverter frequency also increases, and the primary pump 3a performs inverter control so as to increase the variable flow rate.

  On the contrary, when the load flow rate of the secondary pump 4 decreases, the difference between the load flow rate of the secondary pump 4 and the rated flow rate of the heat pump refrigerator 2 becomes small, and the flow rate of the primary pump 3a derived from the subtraction result of both. The set value becomes smaller. Therefore, as the set value decreases, the inverter frequency also decreases, and the primary pump 3a performs inverter control so as to reduce the variable flow rate.

  Although the outlet side temperature becomes unstable when the minimum flow rate is interrupted, the hot water heat exchanger 1 can maintain the outlet side temperature by flowing about 20% of the rated flow rate empirically. Therefore, as in this embodiment, even if the value obtained by subtracting the rated flow rate of the heat pump refrigerator 2 from the load flow rate of the secondary pump 4 is set as the flow rate value, it is possible to obtain a flow rate value with sufficient accuracy. It is.

  According to the present embodiment as described above, it is not necessary to perform flow rate measurement with the expensive electromagnetic flow meter 6 in the variable flow rate control of the primary pump 3a of the hot water heat exchanger 1 system. Thereby, a significant cost reduction is realized. Moreover, in this embodiment, since inverter control of the primary pump 3a is performed by the inverter control unit 9, the load factor of the primary pump 3a is greatly reduced, and energy consumption related to the conveyance power can be saved. Thereby, it becomes possible to exhibit the outstanding energy saving effect. In addition, since the primary flow rate of the primary pumps 3a and 3b is not likely to be lower than the secondary flow rate of the secondary pump 4, the heat source system can be stabilized.

  As described above, in the present embodiment, the energy saving effect and cost reduction can be promoted as described above, so that it is possible to expand the selection range of the effect and cost for energy saving. Therefore, diversification of ESCO proposals can be realized and it can contribute to quality improvement of ESCO business.

  In this embodiment, the flow rate value setting unit 8 and the inverter control unit 9 are realized by the PLC 7. However, since the program of the PLC 7 is reusable, once the program is constructed, the control unit alone can be used. Delivery is also possible, and excellent economy can be demonstrated.

  Further, the present invention is not limited to the above-described embodiment, and the configuration and the number of arrangement of each member can be changed as appropriate. For example, the present invention can be applied not only to a heat source system but also to a cold source system, and a heat source for flowing a rated flow rate includes a vapor compression refrigerator as well as a heat pump.

The block diagram of typical embodiment which concerns on this invention. The graph which shows the flow volume-Hz characteristic in this embodiment. The block diagram of the conventional heat source system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Hot water heat exchanger 2 ... Heat pump refrigerator 3a, 3b ... Primary pump 3c ... Inverter frequency input part 4 ... Secondary pump 5 ... Bypass piping 6 ... Electromagnetic flow meter 7 ... PLC
8 ... Flow value setting unit 9 ... Inverter control unit 10 ... Primary pump control unit

Claims (3)

In a heat source system provided with a primary pump and a secondary pump with variable flow rates, and having at least a heat exchanger as a heat source of a primary system connected to the primary pump,
Based on the load flow rate of the secondary pump, a flow rate value setting means that sets the flow rate value that the primary pump supplies to the heat exchanger;
Assuming that the flow rate value is proportional to the inverter frequency at the rated flow rate, the inverter frequency is determined from the flow rate value set by the flow rate value setting means, and the heat exchanger connected to the heat exchanger based on the inverter frequency A heat source system comprising: inverter control means for controlling the flow rate of the primary pump by inverter.   The heat source system according to claim 1, wherein the flow value setting unit and the inverter control unit are realized by a programmable logic controller. A rated flow heat source having a rated flow rate from the primary pump as a primary heat source connected to the primary pump;
The flow rate setting means is configured to set a subtraction result obtained by subtracting a rated flow rate of the rated flow rate heat source from a load flow rate of the secondary pump as a flow rate value supplied to the heat exchanger by the primary pump. The heat source system according to claim 1 or 2.

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