JPS6321097B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pump control device designed to minimize the operating time of a pump in a building in a district heating and cooling system.

In a district heating and cooling system, an agreement is made between the heat source water supplier and the consumer so that the temperature and pressure of the heat source water at the delivery point will be within a predetermined range. For example, for the supply pressure, the reference value P ₀ ±0.5
Kg/cm ² , that is, in the range of (P ₀ −0.5) and (P ₀ +0.5) (P ₀ is a fixed value), and for the return pressure, the reference value P _r ±0.5Kg/cm ² , that is, (P _r −0.5) and P _r
+0.5) (P _r is an immovable value, P _r <P _p ). For this reason, the installed capacity of a building (load side) is usually calculated on the basis that heat source water at a pressure of (P _r −0.5) is returned at a pressure of (P _r +0.5). In other words, the installed capacity is calculated based on the worst-case conditions. However, if normal operation is controlled based on this worst-case condition, it is clear that pressure loss will occur. In other words, there are times when pumps in buildings are operated unnecessarily.

The present invention provides a device that minimizes the power of pumps in buildings in such district heating and cooling systems. That is, the present invention provides a building with a district heating and cooling system that supplies heat source water with a pressure within a predetermined range from an outgoing pipe of local piping to a load side circuit in a building, and returns heat source water with a pressure within a predetermined range to a return pipe of the local piping. In the side piping system, a bypass pipe is provided to bypass the pump installed in this piping system, a valve is attached to this bypass pipe, and a means for detecting the total flow rate of the piping system (flow meter 7 in the embodiment described later), Differential pressure detection means (supply side differential pressure transmitter 8) between the supply pressure from the local piping and the return pressure to the local piping, the total flow rate detection means (flow meter 7) and the differential pressure detection means (supply side differential pressure transmitter 8), a means (subtractor 14) for comparing both detected values (for example, both are current values) of the transmitter 8), and selection of whether to start or stop the pump and to open or close the valve according to the comparison result of the comparing means. The present invention provides an in-building pump control device for a district heating and cooling system, characterized in that it is provided with means for performing control. DESCRIPTION OF THE PREFERRED EMBODIMENTS The apparatus of the present invention will be specifically described below with reference to embodiments shown in the drawings.

FIG. 1 is a system diagram of the present invention showing a low-rise portion in which building-side pipes having a load group 3 are connected to outgoing pipes 1 and return pipes 2 of regional piping. In the present invention, a bypass pipe 5 is provided to bypass the in-building pump 4,
A valve 6 (Bata valve) is installed in this bypass pipe 5, and the opening/closing of this valve 6 and switching of the pump 4 are performed by cascade control of a flow meter 7 and a supply side differential pressure transmitter 8. ing. In FIG. 1, reference numeral 9 denotes a load side pressure regulating valve, and by controlling the opening degree of this regulating valve 9, the heat source water is returned to the local return pipe 2 at the aforementioned predetermined pressure. In other words, the in-building outbound pipe 10 and the return pipe 11
A load-side differential pressure transmitter 1 that detects the differential pressure in the pipe between
The differential pressure signal of 2 is adjusted by the load-side differential pressure regulator 13 to control the opening of the regulating valve 9, and is returned to the regional return pipe 2 as a pressure within a specified range. At that time, flow meter 7
and the signal from the supply side differential pressure transmitter 8 are sent to the subtractor 14, the load flow rate reading value is cascaded by the reading value of the receiving and return pressure difference, and the ON/OFF signal of the pump 4 is sent to the monitor switch 15. is given, and at the same time, the valve 6 is controlled to close and open. An example of this control is shown in FIG. As shown in FIG. 5, in the flow rate reading section, the current value (mA) corresponding to the flow rate is sent from the flow meter 7 to the subtractor 14, and in the receiving/return pressure difference reading section, the current value (mA) corresponding to the flow rate is sent from the supply side differential pressure transmitter 8. The current value (mA) corresponding to the differential pressure is sent to the subtracter 14, and the subtracter 14 determines which side of the pump OFF threshold line A and the pump ON threshold line B the current values are on. to judge. For example, if the reading of the receiving/returning pressure difference is 3.8Kg/cm ² and the reading of the flow rate is 3.3m ³ /min, the corresponding detected current values will be lower than the pump OFF threshold line A. Since it will be located on the right side of the figure, give the monitor switch 15 a signal to turn off the pump. That is, when the acceptance and return pressure difference is equal to or higher than a predetermined value for a certain flow rate, the pump 4 is stopped and the valve 6 is closed.
Return it as open. On the other hand, when the total flow rate on the load side increases and a large detected value is sent from the flow meter 7, the detected current value of the differential pressure transmitter 8 at that time is higher than the preset pump ON threshold line B. When it comes to the left side, a pump ON signal is given to the monitor switch 15, and at the same time, the valve 6 is closed. In this way, the total flow rate on the load side is detected as a current value by the flowmeter 7, and at the same time, the difference in reception and return pressure of the local piping is detected as a current value by the differential pressure transmitter 8. By comparing and calculating the detected values and selectively controlling the start/stop of the pump and the opening/closing control of the bypass pipe valve 6 based on the comparison, operation of the pump can be stopped when the return pressure is unnecessarily high. . In addition, in Figure 1, 1
Reference numeral 6 indicates a receiving valve, 17 a return valve, 18 a high-rise outbound pipe, and 19 a high-rise return pipe.

FIG. 2 is a circuit diagram of a device suitable for smoothly controlling the opening of the load-side pressure regulating valve 9 when switching between bypass operation and pump operation, including a relay circuit 20, ratio bias 21, and constant current generator. Vessel 2
2, pressure indicating regulator 23, isolator 24,
The low selector 25 is incorporated into an automatic control panel using a circuit as shown in the figure. To explain this control mode, the relay 20 during bypass operation
In this case, the contact b that receives the signal from the flowmeter 7 via the ratio bias 21 and the contact a of the constant current generator 22 are closed, and the constant current generator 22 and the low selector 25 are closed.
are connected. Since the constant current generator 22 always outputs the maximum value of the signal current (for example, 20 mA), the low selector 25
Signal from 3 (e.g. 4-20mA range, 4mA
The opening of the regulating valve 9 is 0% at 20mA, and the opening of the regulating valve 9 is 0% at 20mA.
100%) is passed. Next, when switching from this bypass operation to pump operation, the opening degree of the regulating valve 9 at the time of this switching (just before) should be close to 100%, so the current signal is also 20 mA in the previous example. Near. When the switching signal is received here, the relay 20 closes the contacts b and c for a predetermined time (about 3 seconds depending on the timer setting). As a result, the lower one of the signal from the flow regulator 7 and the signal from the pressure indicating regulator 23 is selected, and the regulating valve 9 is throttled. This signal is simultaneously input to the controller 23 with external feedback, and the output from this controller 23 is also input to the flowmeter 7.
It has come to replace the signal from here,
The contacts a to c of the relay 20 are closed, and the controller 23
is controlled by the signal from the differential pressure transmitter 12. Figure 3 shows the fluctuations in the input signal of the regulating valve 9 and the fluctuations in the differential pressure (differential pressure in the return pipe) when switching from bypass operation to pump operation when this control is not performed. shows a similar situation when this control is performed, and it can be seen that the range of fluctuation is significantly relaxed when this control is applied. That is, in this control, since the opening degree of the valve 9 after the pump is turned on is taken into consideration in advance and instantaneous control is forcibly applied from the outside, fluctuations in the load differential pressure can be minimized.

In this way, the present invention makes it possible to smoothly bypass control the unnecessarily high return pressure caused by conventional pump operation in district heating and cooling systems without causing pressure fluctuations within the system. The present invention provides an energy-saving system that achieves power reduction by shortening pump drive time.

[Brief explanation of drawings]

Fig. 1 is an equipment layout system diagram of the device of the present invention, Fig. 2 is a control circuit diagram, Fig. 3 is a differential pressure fluctuation diagram when the control according to the present invention is not performed, and Fig. 4 is a diagram when the control according to the present invention is performed. Figure 5 shows an example of the control operation of the subtractor for outputting ON/OFF signals to the pump based on the total flow rate on the load side and the difference in reception/return pressure in the local piping. 1... Regional outgoing pipe, 2... Regional return pipe, 3... Load, 4... Pump, 5... Bypass pipe, 6... Bypass valve, 7... Flow meter, 8... Supply side differential pressure transmission device, 9... Load side pressure regulating valve, 12... Load side differential pressure regulator, 13, 23... Load side differential pressure regulator, 1
4...Subtractor, 15...Monitor switch, 20
...Relay, 21...Ratio bias, 22...
Constant current source, 24... Isolator, 25...
Low selector.

Claims (1)

[Claims] 1. In the building-side piping system of a district heating and cooling system that supplies heat source water with a pressure within a specified range from the outgoing pipe of the local piping to the load side circuit in the building, and returns the heat source water with a pressure within the specified range to the return pipe of the local piping. A bypass pipe is provided to bypass the pump installed in this piping system, a valve is attached to this bypass pipe, and a means for detecting the total flow rate of the piping system, supply pressure from the local piping and return pressure to the local piping is installed. a means for comparing the detected values of the total flow rate detecting means and the differential pressure detecting means, and a means for starting/stopping the pump and opening/closing the valve according to the comparison result of the comparing means. An in-building pump control device for a district heating and cooling system, characterized by comprising means for performing selective control.