JP2006177568A - Unit number control device of refrigerator and cool heat supply system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve saving energy and reduction of the operation cost by setting a required minimum refrigerator operation unit number when a cooling water temperature is lowered in winter or in the intermediate time in a unit number control device of a refrigerator operated throughout the year. <P>SOLUTION: A unit number of the refrigerator is varied in accordance with a measured result of a refrigeration load, and a varying standard of the operation unit number is varied by the cooling water temperature. The refrigeration load as the unit number variation standard is varied to the direction which is larger as the cooling water temperature is lowered. Thereby, refrigerator performance increase effect by lowering of the cooling water temperature in the winter or in the intermediate time can be utilized, and the required minimum operation unit number can be set, and operation time of auxiliaries such as the refrigerator, a cooling tower, or a cooling water pump can be reduced. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a cold energy supply system using a plurality of refrigerators and a number control device for refrigerators used in the cold energy supply system.

  Conventionally, as a method of controlling the number of operating heat source units such as refrigerators, the current generation capacity percentage relative to the 100% capacity of the operating heat source unit is checked, and all the operating heat source units are operated at 100% capacity. In this case, a stage increase request for increasing the number of operating heat source units is issued, while the sum of the currently exhibited capabilities of all the heat source units in operation is obtained, and this sum is smaller than a predetermined value. In some cases, there is one that issues a step-down request for reducing the number of operating heat source units (see, for example, Patent Document 1).

  In this prior art, when the return water temperature from the load device is excessive, that is, when the heat source device is a refrigerator, the number of operating heat source devices is forcibly reduced if the return water temperature is lower than a set value. I am doing so. In addition, an increase in the number of operating heat source units is allowed only when the temperature of the outbound water to the load equipment is insufficient, i.e., when the heat source unit is a refrigerator, the outbound water temperature is equal to or higher than a set value. ing.

  As described above, in this prior art, as input information for increasing / decreasing the number of operating heat source units, the generation capacity of the heat source units in operation and their sum, the return water temperature from the load device, or the outgoing water to the load device Temperature is used.

Japanese Patent No. 3306612

  In the conventional refrigerator control device, as described in Patent Document 1, the generation capacity of each refrigerator and the temperature of the chilled water circulating between the chilled water supply side and the load side are used as the input of the number control. . By the way, an electric refrigerator such as a turbo refrigerator or an absorption refrigerator has a characteristic that the maximum generation capacity is increased when the temperature of the cooling water supplied to the refrigerator is lowered from the rated value. For this reason, these refrigerators can cover the cooling load exceeding the rated capacity in the intermediate period or winter season when the cooling water temperature decreases, but the above-mentioned conventional technology does not consider this point. Unnecessarily increasing the number of units in operation during the period was a waste of driving power.

  The increase / decrease in the number of operating units by controlling the number of refrigerators corresponds not only to the refrigerators but also to the number of operating cold water pumps, cooling water pumps and cooling towers attached to the refrigerators. The difference is big.

  The object of the present invention is to set the number of refrigerators in the intermediate period or winter season when the cooling water temperature is lowered to the minimum necessary number reflecting the increase in the capacity of the refrigerator accompanying the decrease in the cooling water temperature. This is to reduce the driving power and cost of the cooling and heating system using the number control device, and to contribute to energy saving and CO2 emission reduction.

  In order to achieve the above object, in the number control device for refrigerators according to the present invention, the number of refrigerators to be operated is determined by the physical quantity related to the cooling load and the temperature of the cooling water passed through each refrigerator. .

  Further, the number control device for refrigerators according to the present invention changes the number of operating refrigerators according to a physical quantity related to a cooling load, and allows the reference for changing the number of operating refrigerators to be passed to each refrigerator. Change according to water temperature. Furthermore, this change reference is changed in a direction in which the reference value for changing the number of operating units is increased when the cooling water temperature is lowered.

  Further, in order to solve the above problems, in the number control device for a refrigerator according to the present invention, the physical quantity related to the cooling load is used to accurately grasp the variation of the cooling load every moment using the exchange heat quantity in the cooling load equipment. It has a simple configuration that uses only the appropriate number control or uses only the chilled water flow rate that is passed through the cooling load facility.

  Furthermore, in order to solve the above-described problems, the cold energy supply system according to the present invention includes the number control device as described above.

  Moreover, the cooling power supply system according to the present invention includes a plurality of water-cooled refrigerators, a cold water pump and a cooling water pump provided corresponding to each of the refrigerators, as a configuration for solving the above problems, A temperature sensor for measuring the temperature of the cooling water supplied to at least one of the refrigerators is provided, and a temperature sensor is provided for increasing or decreasing the number of operating refrigerators depending on the state of the cooling load. Are connected to the number control device.

  According to the present invention, it is possible to reflect the change in the cooling water temperature in the unit control, and to effectively use the effect of increasing the capacity of the refrigerator when the cooling water temperature is lowered. Therefore, it is possible to contribute to energy saving and CO2 emission reduction.

  An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is an overall view of a cold energy supply system according to the present invention. FIG. 2 is a diagram showing the number control method in the number control device for refrigerators according to the present invention when the cooling water temperature is rated (a) and when the cooling water temperature is lowered (b). Further, FIG. 3 is a diagram in which the relationship between the deviation of the cooling water temperature from the rated value of the cooling water temperature, which is the basis of the present invention, to the low temperature side and the maximum refrigeration capacity of the refrigerator is obtained from the cycle simulation result of the turbo refrigerator.

  As shown in FIG. 1, the cold energy supply system includes refrigerators R1, R2, and R3 that generate cold, cold water pumps P11, P21, and P31 that send cold water to each of these refrigerators, and a cold water line when each refrigerator is stopped. Cooling water valves V1, V2, V3 to be shut off, cooling water pumps P12, P22, P32 for supplying cooling water from a cooling tower (not shown) to each refrigerator, and a cooling water temperature sensor T1 for measuring the temperature of the supplied cooling water , T2, T3, chilled water headers 20 and 25, chilled water flow rate sensor F for measuring the flow rate and temperature of chilled water supplied to the cooling load 30, chilled water temperature sensors T4 and T5, and a unit control device for determining the number of operating refrigerators 40. One cooling tower is provided for each refrigerator.

  During the operation of the cold heat supply system, the number control device determines the number of refrigerators to be operated based on the signals from the cold water flow rate sensor F, the cold water temperature sensors T4 and T5, and the signals from the cooling water temperature sensors T1, T2, and T3. An operation signal or a stop signal is output to each of the refrigerators R1, R2, and R3.

  Here, the operation of each refrigerator of the refrigerator when receiving the operation signal or the stop signal will be described using the refrigerator R1 as an example. When the operation signal is received in the refrigerator R1, the operation of the refrigerator main body is started and the cooling water pump P11, the cooling water pump P12, and further the cooling water pump P12 connected to the cooling tower (not shown) are connected via the cooling water pipe. The cold water valve V <b> 1 is opened to supply cold water to the cold water header 20 and the refrigeration load 30.

  In addition, when the stop signal is received in the refrigerator R1, the operation of the refrigerator main body is stopped and the cooling water pump P11, the cooling water pump P12, and the cooling water pump P12 are connected to the cooling tower (not shown) connected via the cooling water pipe. The operation is stopped, the cold water valve V1 is closed, and the supply of cold water to the refrigeration load 30 or the like is stopped.

  The cold water supplied to the refrigeration load 30 is supplied with cold heat to the refrigeration load to rise in temperature, and is led again to the suction side of the chilled water pumps P11, P21, and P31 via the chilled water flow rate sensor F and the chilled water header 25. At this time, when the refrigerator R1 is in operation, the cold water led to the suction side of the cold water pump P11 is cooled again by the refrigerator R1 and sent to the refrigeration load 30.

Next, the number control method in the number control device 40 will be described with reference to FIGS. The number control device 40 calculates the exchange heat quantity Q from the physical quantity related to the refrigeration load 30, and sets the number of operating refrigerators based on the result. The physical quantities related to the refrigerator load are the chilled water flow rate Vw measured by the chilled water flow rate sensor F, the load system inlet chilled water temperature Twi measured by the chilled water temperature sensor T4, and the load system outlet chilled water temperature measured by the chilled water temperature sensor T5. Two. Using these, the exchange heat quantity Q is calculated by the equation (1).
Q = Vw × ρw × cpw × (Two−Twi) (Equation 1)
Where ρw is the density of cold water and cpw is the specific heat capacity of cold water.

  Note that the refrigeration load 30 in the present embodiment is such that the resistance of the internal chilled water system changes as the refrigeration load amount increases or decreases. Accordingly, the chilled water flow rate detected by the chilled water flow rate sensor F also changes as the refrigeration load amount increases or decreases.

  In general, the number control of a plurality of refrigerators is performed by the method shown in FIG. FIG. 2 shows the change standards L1, L2, L3, and L4 of the number of operating refrigerators by taking the exchange heat quantity Q of the refrigeration load calculated on the horizontal axis and the operating number of refrigerators on the vertical axis.

  When the refrigeration load is large and exceeds the reference value L4, such as when starting the cold supply system, the number of operating refrigerators is three. Similarly, at the time of start-up or the like, when L2 or more and L4 or less, two units are operated. Furthermore, when it is L2 or less, one unit is operated. If the exchange heat quantity decreases and becomes smaller than the reference value L3 while operating with three units, the number of operating refrigerators is changed to two. Thereafter, when the exchange heat quantity further decreases and becomes smaller than the reference value L1, the number of operating refrigerators is one. On the contrary, when the two units are operated, if the exchange heat quantity increases again and becomes larger than L4, the number of units operated becomes three units. When the number of operating units is one and the amount of exchange heat increases and becomes larger than the reference value L2, the number of operating units is two. As described above, the reference refrigeration load is set to a different value depending on whether the number of operating units is increased or decreased.

  In this embodiment, the number control device 40 adds the cooling water temperature measured by the cooling water temperature sensors T1, T2, T3 in addition to the above-described cooling water flow rate F, the load system inlet cold water temperature T4, and the load system outlet cold water temperature T5. Use to calculate the number of operating refrigerators. For this calculation, the detected temperature of the cooling water corresponding to the operating chiller among T1, T2, and T3 is used, and when a plurality of chillers are operating, it corresponds to the operating chiller. Use the highest cooling water temperature.

The number control device 40 controls the number of refrigerators according to predetermined reference values L1 to L4 as shown in FIG. 2A when the coolant temperature Ts is a rated value T0, for example, 32 ° C. In this embodiment, the values of the refrigeration loads L1 to L4 are 80%, 90%, 160%, and 180%, respectively. When the cooling water temperature deviates from the rated value and becomes low, the deviation ΔTcw = T0−Ts where the cooling water temperature Ts is lower than the rated value is used, and the reference values L1 to L4 are expressed by the equation 2 as the reference value L1. Correct to '~ L4'. This correction detects whether or not the cooling water temperature is lower than the rated value at a predetermined timing (for example, at an interval of 30 minutes). To change.
L1 ′ = L1 × (1 + kΔTcw)
L2 ′ = L2 × (1 + kΔTcw)
L3 ′ = L3 × (1 + kΔTcw)
L4 ′ = L4 × (1 + kΔTcw) (Equation 2)
However, k is a constant.

  Accordingly, when the cooling water temperature is lowered and ΔTcw is increased, the number control method is corrected as shown in FIG. At this time, as shown below, the number of operating refrigerators increases the time during which the refrigerator is operated with a smaller number than in the case of FIG.

  When the amount of heat exchanged at the refrigeration load 30 decreases when the refrigerator is operated with three units, the number of refrigerators is reduced to two when the reference value L3 is reached in FIG. In FIG. 2B used in the present embodiment, the number of units is reduced when reaching L3 ′ larger than L3, so the number of operating units decreases earlier than in the case of FIG. Accordingly, the time required for operating the three refrigerators is shortened, and the time required for operating the two refrigerators is increased.

  In addition, when the amount of exchange heat at the refrigeration load 30 increases when the refrigerator is operated with two units, in FIG. 2A, when the reference value L4 is reached, the number of refrigerators is increased to three. On the other hand, in FIG. 2B used in the present embodiment, the number of units is increased when L4 ′ larger than L4 is reached, so that the number of operating units increases later than in the case of FIG. In this case as well, the time for operating the three refrigerators is shortened, and the time for operating the two refrigerators is increased.

  Further, since the same operation is performed when switching the number of operating refrigerators between two and one, the time required for operating the two refrigerators is shortened, and the time required for operating the one refrigerator is reduced. To increase.

  Next, it will be described with reference to FIG. 3 that the refrigeration capacity of the cold energy supply system does not become insufficient when the correction shown in Equation 2 is performed. FIG. 3 shows the maximum refrigeration capacity of the centrifugal chiller with respect to the temperature deviation from the rated value of the cooling water temperature to the centrifugal chiller to the side where the cooling water temperature decreases, with reference to the case where the temperature deviation of the cooling water is zero. . The plot in the figure is the analysis result by the cycle simulation of the centrifugal chiller, and the solid line is the case where the maximum refrigeration capacity of the centrifugal chiller is increased by 1% per 1 ° C. temperature deviation.

  As shown in FIG. 3, the maximum refrigeration capacity of the centrifugal chiller increases with the temperature deviation of the cooling water, and the rate of increase is larger than when the temperature deviation is 1% per 1 ° C. Therefore, when the model targeted in FIG. 3 is used as a refrigerator, the value of the constant k in Equation 2 is set to 0.01 (1% / ° C.), so that it is possible to cool even if the reference values L1 ′ to L4 ′ are used. Supply capability is satisfied.

  For example, when the rated value of the cooling water temperature is 32 ° C. and the cooling water temperature during operation is 22 ° C., ΔTcw in Equation 2 is 10 ° C., and k = 0.01, so the reference values L1 ′ to L4 ′ are respectively L1 to L4 are multiplied by 1.1. At this time, since the maximum refrigeration capacity of the refrigerator is 1.1 times or more of the rated value from FIG. 3, the capacity of the refrigerator does not become insufficient even if the reference value for changing the number is multiplied by 1.1.

  On the contrary, when the cooling water temperature becomes higher than the reference value, ΔTcw becomes a negative value, and the reference value is changed to a lower direction.

  As described above, in this embodiment, the number control with high accuracy can be performed based on the calculation result of the exchange heat quantity, and the minimum necessary amount is always obtained by utilizing the increase in the capacity of the refrigerator when the cooling water temperature decreases as shown in FIG. Since a limited number of operating units can be set, it is possible to save energy compared to the case where the reference values L1 to L4 are fixed and the number of units is controlled in the operating pattern of FIG. As described above, since the chilled water pump, the cooling water pump and the cooling tower corresponding to each chiller are started and stopped simultaneously with the start and stop of the chiller, this energy saving effect is very large.

  In the present embodiment, the reference values L1 to L4 for changing the number of units are determined for the exchange heat quantity Q in the refrigeration load 30, but the flow rate of chilled water flowing through the refrigeration load 30 varies with the refrigeration load quantity, that is, the exchange heat quantity ( For example, when the refrigeration load 30 is a half load, the chilled water flow rate is reduced to about half). Therefore, these reference values may be determined with respect to the chilled water flow rate measured by the chilled water flow rate sensor F. In this case, there is an advantage that the calculation shown in Equation 1 is not necessary and there is no influence on the number control when the chilled water temperature sensors T4 and T5 fail. That is, the physical quantity related to the refrigeration load in this case is only the cold water flow rate.

  Further, as shown in FIG. 4, the number control device 40 may calculate the number of operating units from both the cold water flow rate and the load-side exchange heat amount, and set the larger number as the actual operating number. In this case, it is possible to control the number of units with high accuracy based on the calculation result of the exchange heat amount, and even when the chilled water temperature sensors T4 and T5 break down, the number of units is controlled based on the chilled water flow rate. Can be supplied. In this case, only the chilled water flow rate, the load inlet chilled water temperature, and the load outlet chilled water temperature are used as physical quantities related to the refrigeration load.

  In the above embodiment, the reference values L1 to L4 for the number control are corrected and changed according to the cooling water temperature, but this may be the outside air temperature or humidity that is the controlling factor of the cooling water temperature. In this case, since the change in the outside air condition that causes the cooling water temperature change can be directly reflected in the number control, the reference value for the number control can be changed prior to the change in the cooling water temperature. Therefore, there is an advantage that a lack of refrigerating capacity can be avoided particularly when the outside air temperature and the cooling water temperature are increased. Even when the refrigerator is air-cooled, it is effective to change the unit control reference value according to the outside air condition.

It is a block diagram of the cold-power supply system concerning one Example of this invention. It is a figure showing the change method of the unit control reference in this invention. It is a figure showing the freezer maximum capacity at the time of cooling water temperature fall. It is a figure showing the number control method concerning the other Example of this invention.

Explanation of symbols

R1, R2, R3 ... Refrigerator, P11, P21, P31 ... Cold water pump, P12, P22, P32 ... Cooling water pump, V1, V2, V3 ... Cold water valve, T1, T2, T3 ... Cooling water temperature sensor, T4, T5 ... Chilled water temperature sensor, F ... Chilled water flow sensor, 20, 25 ... Chilled water header, 30 ... Cooling load, 40 ... Number control device, L1-L4 ... Reference value for changing the number of operating units when cooling water temperature is rated, L1 '- L4 '... A reference value for changing the number of operating units when the cooling water temperature drops.

Claims (11)

  In the number control device for water-cooled refrigerators, the operating number of the refrigerators is determined by a physical quantity related to a cooling load and a temperature of cooling water passed through each refrigerator. Number control device.   A number control unit for a refrigerator that changes the number of operating units of a plurality of refrigerators according to a physical quantity related to a cooling load and a temperature of cooling water that is passed through each refrigerator. A number control device for a refrigerator, wherein a reference value to be changed is changed according to a temperature of the cooling water. In the number control apparatus of the refrigerator of Claim 2,
The change of the reference value of the number of operating units of the refrigerator is changed to a direction in which the reference value is increased in proportion to a deviation in a direction in which the temperature of the cooling water decreases from the rated value. Unit control device. In the number control apparatus of the refrigerator in any one of Claim 1 to 3,
The apparatus for controlling the number of refrigerators, wherein the temperature of the cooling water is an inlet temperature of cooling water in any of the operating refrigerators. In the number control apparatus of the refrigerator of Claim 4,
A refrigerator control device for a refrigerator, wherein a refrigerator to be measured for cooling water temperature used for number control is a refrigerator having the highest priority in the number control. In the number control apparatus of the refrigerator of Claim 2,
The reference number of the number of operating refrigerators is changed by using the temperature or humidity of the outside air instead of the cooling water temperature.   The number control device for a refrigerator according to any one of claims 1 to 6, wherein the physical quantity related to the cooling load is an exchange heat amount in the cooling load facility.   The number control apparatus for a refrigerator according to any one of claims 1 to 6, wherein the physical quantity related to the cooling load is a flow rate of cold water passed through the cooling load facility. apparatus.   The number control apparatus of the refrigerators in any one of Claim 1 to 6 WHEREIN: The physical quantity relevant to the said cooling load is the cold water flow volume passed through to a cooling load installation, and the exchange heat amount in a cooling load installation, The said cold water A number control unit for a refrigerator, wherein the number of operating units is determined from the flow rate and the exchange heat quantity, and the larger number of these units is set as the actual number of operating units. In a cooling / heating supply system comprising a plurality of water-cooled refrigerators and a number control device for adjusting the cooling capacity by changing the number of operating refrigerators,
The number control device changes a reference value for determining the number of operating units of the plurality of refrigerators based on a temperature of cooling water passed through the plurality of refrigerators. A plurality of water-cooled refrigerators, a chilled water pump and a cooling water pump provided corresponding to each of the refrigerators, and a number control device that increases or decreases the number of operating the refrigerators depending on the state of the cooling load. In the cold energy supply system,
A temperature sensor for measuring the temperature of cooling water supplied to at least one of the refrigerators is provided, and the output from the temperature sensor is input to the number control device and the number of units is changed based on the detection value of the temperature sensor. The cooling / heating supply system characterized by changing the reference value of

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