JP5538917B2 - Heat source system - Google Patents

Description

  The present invention relates to a heat source system that supplies thermal energy to a heat supply destination using a refrigerator having an evaporator and a condenser.

  In a heat source system using a refrigerator, the operating efficiency of the refrigerator greatly affects the fluctuations in energy consumption of the entire heat source system, so how to efficiently drive the refrigerator, and further provided in the heat source system Various techniques have been developed for how to efficiently drive devices other than refrigerators. For example, as shown in Patent Document 1, a technique is disclosed in which a plurality of refrigerators having different performances with respect to the flow of cold water are connected in series, and the number of refrigerators operated is controlled according to the size of the load. . In this technology, the cooling water supplied to each refrigerator is supplied to each refrigerator, that is, in parallel, unlike the cold water.

  In addition, in a heat source system configured to install multiple chillers in parallel to the load and to be able to supply chilled water from each chiller, the flow rate of chilled water flowing into the chiller is adjusted at the time of maximum load. A technique for improving the efficiency of the system by setting an excessive flow rate state larger than the cold water flow rate is disclosed (see, for example, Patent Document 2). In this technology, by setting the chilled water flow rate to an overflow state, even when the return temperature difference of the chilled water in the refrigerator becomes smaller than a predetermined value, heat can be supplied to the external load up to the upper limit capacity of the refrigerator, Therefore, it is intended to improve the efficiency of the heat source system.

JP-A-5-93550 JP 2004-245560 A JP 2007-198693 A JP-A-8-29011 Japanese Patent Laid-Open No. 10-197098 JP 2006-152823 A Japanese Patent Laid-Open No. 10-239477

  In a heat source system using a refrigerator, in order to improve the system efficiency, it is ideal to maintain the operation state of the refrigerator in which the operation efficiency of the refrigerator itself is good. Depending on the specific configuration of the refrigerator, for example, in a refrigerator having a configuration in which the efficiency increases as the load applied to the refrigerator increases, it is driven at the rated load state (100% load state) that is the maximum load. By continuing this, it is possible to improve the efficiency of the heat source system. However, the load applied to the refrigerator varies depending on the state of heat consumption at the heat supply destination of the actual heat source system, and in many cases, the load is a partial load state that is lower than the rated load state. Therefore, it is difficult to continue driving the refrigerator itself in the best efficiency state.

Here, in a heat source system that employs a configuration in which a plurality of refrigerators are connected in series, conventionally, when the load applied to one refrigerator is in a partial load state, the temperature of the chilled water outlet from the refrigerator is decreased. In general, a technique for increasing the operating efficiency of the refrigerator by increasing the load applied to the refrigerator is generally employed. However, in this method, when the chiller other than the one chiller is viewed, the load on the chiller is reduced, so the heat source system as a whole is placed in a partial load state. As a result, it remains difficult to improve system efficiency as a result.

  In view of the above problems, an object of the present invention is to substantially improve system efficiency in a heat source system employing a configuration in which a plurality of refrigerators are connected in series.

  In the present invention, in order to solve the above-described problems, the heat source system adopts a configuration in which a plurality of refrigerators are connected in series, and each refrigerator is set so that the temperature of the chilled water supplied to the heat supply destination is a predetermined temperature. While controlling, let the flow volume of the cold water which flows into each refrigerator in that case be an overflow state according to the magnitude | size of the load requested | required from the heat supply destination. That is, the refrigerator exerts its effect by increasing the chilled water flow rate according to the change in the temperature drop of the chilled water in each refrigerator (difference between the inlet temperature and the outlet temperature of the chilled water with respect to the evaporator), especially the decrease in the temperature difference. It is intended to maintain the output capacity at a relatively high state, thereby improving the operating efficiency of the refrigerator.

  Specifically, the present invention provides a cooling tower, a refrigerator group formed by including a first refrigerator and a second refrigerator each having an evaporator and a condenser, and cooling water from the cooling tower, Cooling water pipes supplied in series to the condensers of the respective refrigerators of the refrigerator group, a cooling water pump for pumping the cooling water in the cooling water pipes, and evaporation of the respective refrigerators of the refrigerator group A chilled water pipe that supplies chilled water in series and in a direction opposite to the flow direction of the cooling water in the cooling water pipe, and a chilled water pump that pumps the chilled water in the cold water pipe, This is a heat source system that supplies heat energy to the heat supply destination via cold water. The heat source system further includes a load calculation unit that calculates an output load of the refrigerator group based on a heat energy amount that the heat source system should supply to a heat supply destination, the first refrigerator, and the first refrigerator The first refrigerator and the first refrigerator, so that the temperature of the cold water supplied to the heat supply destination via the cold water pipe via the two refrigerators becomes a predetermined supply temperature regardless of the output load calculated by the load calculation unit. As the output load calculated by the first control unit for controlling the second refrigerator and the load calculation unit becomes smaller than the rated output load of the refrigerator group, the flow rate of cold water flowing through the cold water pipe is the rated value. A second control unit that controls the chilled water pump so as to increase the flow rate compared to the rated chilled water flow rate that flows through the chilled water pipe during output load.

  In the refrigerator group provided in the heat source system according to the present invention, the flows of cold water and cooling water are in opposite directions, that is, a counterflow flow is formed. For example, when cold water flows in the order of the evaporator of the first refrigerator and the evaporator of the second refrigerator, the cooling water flows in the order of the condenser of the second refrigerator and the condenser of the first refrigerator. As for the order of the first refrigerator and the second refrigerator in the refrigerator group, for example, in the flow of cold water, either refrigerator may be arranged on the upstream side. The machine is located upstream. In this way, in the refrigerator group in which two refrigerators are connected in series, the flow of cold water and the flow of cooling water become a counter flow, so that between the condenser and the evaporator in each refrigerator. The heat exchange performed can be performed efficiently, and the operating efficiency of the refrigerator can be improved.

  Here, in the heat source system, the load calculation unit calculates the output load that the refrigerator group should bear. In addition, in this specification, the load at the time of the maximum output is referred to as “rated output load” or 100% load for the output load that should be taken by the refrigerator group or the refrigerators included therein, and when the output load is reduced thereafter. The load is expressed as “partial load” or a load expressed in% together with a numerical value corresponding to the degree (for example, “80% load”).

And according to the load calculated in the load calculation part, control of each refrigerator and control of the flow volume of the cold water which flows into each refrigerator are performed. That is, the first control unit controls each refrigerator so that the temperature of the cold water supplied to the heat supply destination through the first refrigerator and the second refrigerator, that is, the refrigerator group, becomes a predetermined supply temperature. Do. This predetermined supply temperature may be a constant temperature at all times, or may be changed as appropriate according to the requirements of the heat supply destination. The important point is that the refrigerator group is controlled by the first control unit so as to supply cold water having a predetermined supply temperature to the heat supply destination.

  And in the heat source system which concerns on this invention, in addition to said 1st control part, the 2nd control part which controls a cold water pump and adjusts a cold water flow volume is provided. When the output load calculated by the load calculation unit is in a partial load state, the second control unit is configured to increase the chilled water flow rate through the chilled water pipe from the rated chilled water flow rate according to the degree of the partial load state. To control. That is, as the amount of decrease in the calculated output load from the rated output load increases, the second control unit controls the chilled water pump so that the chilled water flow rate is increased from the rated chilled water flow rate, in other words, an overflow state. I do. In this state where the chiller group is controlled so that the chilled water temperature supplied by the first control unit becomes a predetermined supply temperature, the second control unit performs overflow control of the chilled water flow rate, so that the load Even if the output load calculated by the calculation unit is in a partial load state, the output that should be borne by each of the refrigerators forming the refrigerator group is in a state suitable for the operation efficiency of the refrigerator (for example, operation by reducing the output) It is possible to avoid a state where the efficiency is reduced. In other words, when the output load is in a partial load state, the amount of work that should be essentially done for the refrigerator group is reduced, but the chilled water flow rate is controlled to an overflow state, resulting in the Reduction in the amount of work to be done can be suppressed. Therefore, even if the output load is in a partial load state, the output that the refrigerator group should bear can be maintained at a relatively high state, thereby avoiding a decrease in operating efficiency of the refrigerators forming the refrigerator group It becomes possible to do.

  Preferably, in the heat source system, in the first refrigerator and the second refrigerator, a difference between an inlet temperature of cold water flowing into an evaporator of each refrigerator and an outlet temperature of cold water flowing out of the evaporator The output capacity of each of the first refrigerator and the second refrigerator determined based on a certain temperature difference and a flow rate of the cold water flowing through the cold water pipe controlled by the second control unit is the refrigerator group. The second control unit may be configured to determine a flow rate of chilled water flowing through the chilled water pipe so that the output capacity of the first chiller and the second chiller at the rated output load is the same. Good. By configuring in this way, even if the output load calculated by the load calculation unit is in a partial load state, the output to be carried by the refrigerator group is maintained at the output capacity at the rated output load. The operating efficiency of the aircraft group can be maintained at the operating efficiency at the rated output load. Generally, the operating efficiency of the refrigerator is the best at the rated output load. Therefore, according to the above configuration, the operating efficiency of the refrigerator group is the best even when the output load is in a partial load state. Can be maintained.

  Thus, in the heat source system that employs a configuration in which two refrigerators are connected in series, the operation efficiency of the refrigerator group is improved by including the first control unit and the second control unit. As a result, the system efficiency of the entire system is improved.

  Here, in the heat source system described above, a cooling water return bypass pipe that connects the outgoing pipe to the refrigerator group in the cooling water pipe and the return pipe from the refrigerator group without passing through the refrigerator group. And a set temperature of the cooling water flowing through the cooling water pipe based on at least the outside air temperature of the heat source system, and a flow rate of the cooling water flowing through the cooling water return bypass pipe is controlled based on the set temperature of the cooling water You may comprise so that the 3rd control part to perform may be further provided. In this way, the third control unit can adjust the cooling water temperature by controlling the cooling water flow rate or the cooling tower fan that flows through the cooling water return bypass pipe based on the outside air temperature, and as a result, the efficiency of the heat source system can be improved. It becomes possible to optimize. In particular, the heat source system according to the present invention includes a refrigerator group in which two refrigerators are connected in series, and when the number of operating refrigerators fluctuates as will be described later, Compared to the case of parallel connection, the outlet temperature of the cooling water can be lowered, which greatly contributes to the efficiency of the heat source system.

  Here, in the heat source system up to the above, in the flow of the cold water in the cold water pipe, the cold water bypass means for bypassing the cold water so as not to flow into the evaporator of the first refrigerator, and the load calculation unit calculates the cold water. When the output load is equal to or lower than the predetermined output load, the operation of the first refrigerator is stopped, and the cold water is supplied to the evaporator of the second refrigerator in the flow of cold water in the cold water pipe by the cold water bypass means. And a refrigerator operation control unit that supplies only the refrigerant. According to this configuration, when the output load is equal to or lower than the predetermined output load, the operation of the first refrigerator among the refrigerators connected in series in the refrigerator group is stopped and the cold water is stopped. The flow path is controlled so as not to flow into the flow path. The predetermined output load is a threshold load that is an upper limit of an output load that can be handled only by the remaining second refrigerator when the operation of the first refrigerator included in the refrigerator group is stopped. Therefore, the refrigerator operation control unit stops the operation of the first refrigerator and bypasses the cold water, thereby making the load on the second refrigerator as high as possible and reducing its operating efficiency. In addition to avoiding this, it is possible to reduce the pressure loss of the chilled water pump that occurs during pumping of chilled water, that is, to reduce the resistance due to the evaporator of the chiller by bypassing the stopped chiller and flowing cold water. System efficiency can be improved.

  Further, in the heat source system, when the operation of the first refrigerator is stopped by the refrigerator operation control unit, the stopped first refrigerator is temporarily in operation. The second refrigerator may be configured to output in an overload state that is larger than the load at the rated output load so that the second refrigerator is also responsible for the output that is sometimes required. By operating the second refrigerator in an overloaded state while the first refrigerator is stopped, the operating efficiency of the second refrigerator that is operating can be improved as compared with the rated output load. The operation of the second refrigerator in an overload state is preferably performed in a range that does not affect the normal operation of the second refrigerator.

  Further, when the second refrigerator is operating in an overload state, the second control unit flows through the cold water pipe when the operation of the first refrigerator is stopped by the refrigerator operation control unit. The cold water flow rate to be supplied to the second refrigerator may be the rated cold water flow rate. On the other hand, when the temperature of the cooling water supplied to the second refrigerator via the cooling water pipe exceeds a predetermined rated cooling water temperature corresponding to the rated cold water flow rate, the second control unit What is necessary is just to let the cold water flow volume which should flow through piping and be supplied to said 2nd refrigerator be a flow volume smaller than the said rated cold water flow volume. That is, when the cooling water temperature exceeds the rated cooling water temperature, it is considered that there is little room for operation in an overload state in the second refrigerator. Reduce the load on the machine.

  In the heat source system described above, when the cooling water flow in the cooling water pipe further includes cooling water bypass means for bypassing the cooling water so as not to flow into the condenser of the first refrigerator, the refrigerator When stopping the operation of the first refrigerator, the operation control unit may supply the cooling water only to the condenser of the second refrigerator in the cooling water pipe by the cooling water bypass unit. With this configuration, along with the stoppage of the operation of the first refrigerator, the bypass of the cooling water is performed in addition to the bypass of the cold water. As a result, it is possible to reduce the pressure loss of the cooling water pump that is generated when the cooling water is pumped, that is, to reduce the resistance of the condenser of the refrigerator, thereby improving the system efficiency.

  In the heat source system described above, the predetermined output load may be adjusted based on a temperature of cooling water supplied to the second refrigerator via the cooling water pipe. That is, the value of the predetermined output load, which is a criterion for performing the independent operation of the second refrigerator, is changed in association with the cooling water temperature that determines the possibility of operation in the overload state of the second refrigerator. Thus, the operation of the efficient heat source system can be flexibly realized.

  In the heat source system up to the above, the output capacities of the first refrigerator and the second refrigerator may be the same, and the refrigerator group is a refrigerator having different output capacities based on the heat supply capacity of the heat source system. It may be configured. When the refrigerator group is formed with the same refrigerator as in the former, there is an advantage that maintenance of the heat source system becomes easy.

  Here, it is also possible to grasp the heat source system according to the present invention from the side of the arrangement of the heat source system in the building. That is, the heat source system according to the present invention is focused on the configuration employing a refrigerator group in which two refrigerators are connected in series. The refrigerator group and the corresponding chilled water pump and chilled water pump are combined into a single compartment for accommodation formed in the building.

  Specifically, the present invention provides a cooling tower, a refrigerator group formed including a first refrigerator and a second refrigerator each having an evaporator and a condenser, and cooling water from the cooling tower, Cooling water pipes that are supplied in series to the condensers of the respective refrigerators of the refrigerator group, a cooling water pump that pumps the cooling water in the cooling water pipes, and an evaporator that each of the refrigerators of the refrigerator group has A chilled water pipe for supplying chilled water in series and in a flow direction opposite to the flow direction of the chilled water in the cooling water pipe, and a chilled water pump for pumping chilled water in the chilled water pipe, In a heat source system for supplying heat energy to a supply destination via cold water, a minimum installation for accommodating a configuration of the heat source system defined by a plurality of support members that support a plant building in which the heat source system is installed A plurality of drawings are provided in the plant building, and the chiller group and the chilled water pump and the chilled water pump corresponding to the chiller group are accommodated inside each of the plurality of minimum installation sections. Adopt the configuration.

  Thus, in the heat source system according to the present invention, the distance between the support members that demarcate the minimum installation section by accommodating the refrigerator group, the chilled water pump, and the cooling water pump in the minimum installation section is the same as that of the conventional installation. Compared with a system widely used in the system, a single refrigerator, a corresponding cold water pump, and a cooling water pump are arranged between the support members. Preferably, the distance between the support members in the minimum installation section is about 10 m to 11 m. By adopting a relatively wide support member interval in this way, the heat source system can be accommodated in a compact manner, the size of the plant building itself that accommodates the entire heat source system can be reduced, and the structural strength problem caused by widening the support member interval Is less likely to manifest. On the other hand, since the refrigerator group, the chilled water pump, and the chilled water pump can be arranged densely, the piping distance can be shortened, which greatly contributes to the efficiency of the heat source system.

  In the heat source system, in the minimum installation section, in order to make the height from the floor surface of the chilled water pipe equal to the height of the refrigerator group, the chilled water is supplied to the heat supply destination or the heat supply. You may employ | adopt the structure which installs the cold water collecting pipe for collect | recovering cold water from the tip in a pit area | region lower than the floor surface in which the said refrigerator group is installed. With this configuration, it becomes easy to shorten the piping and ensure the safety at the time of piping construction.

  In a heat source system that employs a configuration in which a plurality of refrigerators are connected in series, it is possible to substantially improve system efficiency.

It is a figure showing a schematic structure of a heat source system concerning the present invention. It is a figure which shows the change of the cold water temperature and the cooling water temperature in the two refrigerators connected in series provided in the heat-source system shown in FIG. It is a figure which shows the set value of the cold water temperature and the cold water flow rate according to the output load of a system performed in the heat source system which concerns on this invention. It is a figure which shows the setting value of the chilled water temperature and the chilled water flow rate according to the output load of a system performed in the conventional heat source system. It is a flowchart of the operation control of the refrigerator performed with the heat source system which concerns on this invention. It is a figure which shows the operation efficiency in a refrigerator when the refrigerator operation control shown in FIG. 5 is performed. It is a figure which shows the comparison result of the system efficiency of the heat source system which concerns on this invention, and the conventional heat source system. It is a 1st figure which shows the design aspect of the plant equipment which stores the conventional heat source system. It is a 2nd figure which shows the design aspect of the plant equipment which stores the conventional heat source system. It is a 3rd figure which shows the design aspect of the plant equipment which stores the conventional heat source system. It is a 1st figure which shows the design aspect of the plant equipment which stores the heat source system which concerns on this invention. It is a 2nd figure which shows the design aspect of the plant equipment which stores the heat-source system which concerns on this invention. It is a figure which shows an example of arrangement | positioning of a 40,000 Rt plant which employ | adopted the heat source system which concerns on this invention.

  The heat source system according to the present invention will be described below with reference to the drawings. In addition, the structure of the following embodiment is an illustration and this invention is not limited to the structure of this embodiment. In addition, Rt (refrigerating ton), which is a unit representing the refrigerating capacity of the refrigerator used in this specification, is “transition of 2000 pounds (about 906 kg) of water at 0 ° C. to ice at 0 ° C. in 24 hours. The refrigerating capacity of the refrigerator is defined as 1Rt, and 1Rt = 3024kcal / h = 3516W.

  FIG. 1 is a diagram showing a schematic configuration of a heat source system 1 according to the present invention. The heat source system 1 is a system that supplies heat energy to an external load (not shown) using a refrigerator as a heat source via cold water that is a heat medium. The heat source system shown in FIG. 1 includes a refrigerator group composed of two refrigerators 3 and 4 having the same refrigerating capacity. Each refrigerator includes evaporators 3a and 4a and a condenser 3b, 4b, cold water is supplied to each evaporator, and cooling water is supplied to each condenser, so that heat is exchanged between the cold water and the cooling water. In the heat source system 1, the refrigerators 3 and 4 included in the refrigerator group are connected in series, and a so-called counter flow state is formed in which the flows of cold water and cooling water are opposite to each other. The heat source system 1 shown in FIG. 1 includes one refrigeration group, but a configuration that increases the refrigeration capacity of the heat source system 1 by providing a plurality of refrigeration groups in parallel with each other is adopted. May be.

  Therefore, first, focusing on the flow of the cold water, details of the flow path of the cold water will be described. A refrigerator group is installed on a chilled water pipe 12 that connects between a forward header 11 that supplies chilled water to a heat supply destination and a return header 10 from which the chilled water used at the heat supply is returned. In this flow, the evaporator 3 a of the refrigerator 3 is positioned upstream of the evaporator 4 a of the refrigerator 4. That is, the cold water returned to the return header 10 is first supplied to the refrigerator 3 and then supplied to the refrigerator 4, and then supplied from the forward header 11 to the heat supply destination. At this time, the primary chilled water pump 5 is installed on the chilled water pipe 12 between the return header 10 and the refrigerator 3 in order to pump the chilled water, and the secondary chilled water pump 6 is further placed on the forward header 11. is set up. In this way, two sets of chilled water pumps are provided in the chilled water flow path, so that the flow rate of the chilled water can be controlled, and the chilled water is properly pumped between the heat supply destination and the refrigerator group. Can be done.

  Furthermore, a cold water bypass pipe 13 is installed for the cold water pipe 12 so that the cold water can be bypassed and supplied to the refrigerator 4 so that the cold water does not flow into the refrigerator 3. The cold water intake port of the cold water bypass pipe 13 is located on the downstream side of the primary cold water pump 5, and the cold water outlet is located on the cold water pipe 12 between the refrigerator 3 and the refrigerator 4. Then, in order to adjust the cold water supply to the refrigerator 3 via the cold water bypass pipe 13, flow rate adjusting valves 16 and 18 are provided on the cold water pipe 12 immediately before the refrigerator 3 and the cold water bypass pipe 13, respectively. It has been.

  Further, the heat source system 1 includes, as auxiliary equipment related to the flow of cold water, a water temperature meter 14 for detecting the cold water temperature on the return header 10, a flow meter 15 for detecting the cold water flow rate, and cold water on the cold water pipe 12. A water temperature meter 17 for detecting the temperature, a flow meter 19 for detecting the cold water flow rate, a water temperature meter 20 for detecting the cold water temperature on the forward header 11, and a flow meter 21 for detecting the cold water flow rate are provided. ing. In addition, an inter-header bypass pipe 22 that bypasses the cold water from the return header 10 to the forward header 11 without passing through the refrigerator group is also provided.

  Next, focusing on the flow of the cooling water, details of the flow path of the cooling water will be described. The heat source system 1 includes a cooling water forward pipe 30 that sends cooling water from the cooling tower 2 that radiates cooling water to the refrigerator group, and a cooling water return pipe 32 that returns the cooling water from the refrigerator group to the cooling tower 2. Further, the cooling water pipe 31 is connected between the refrigerators in the refrigerator group. And in the flow of the cooling water in the cooling water pipe 31, the condenser 4 b of the refrigerator 4 is located upstream from the condenser 3 b of the refrigerator 3. That is, the cooling water from the cooling tower 2 is first supplied to the refrigerator 4 and then supplied to the refrigerator 3, and then returned to the cooling tower 2 for heat dissipation. At this time, in order to pump the cooling water, the cooling water pump 7 is installed on the cooling water forward pipe 30 to control the flow rate of the cooling water. A cooling water return pipe 30 and a cooling water return pipe 32 are directly connected, and a cooling water return bypass pipe 39 is provided to prevent the cooling water from flowing into the refrigerator 3 and the refrigerator 4. A flow rate adjustment valve 38 capable of adjusting the flow rate of the flowing cooling water is provided on the pipe 39.

  Further, a cooling water bypass pipe 33 is provided for the cooling water pipe 31 so that the cooling water from the refrigerator 4 can be bypassed so that the cooling water does not flow into the refrigerator 3. The cooling water intake port of the cooling water bypass pipe 33 is located on the cooling water pipe 31 between the refrigerator 3 and the refrigerator 4, and the cooling water outlet is downstream of the condenser 3 b of the refrigerator 3. Located in. In order to adjust the cooling supply to the refrigerator 3 via the cooling water bypass pipe 33, the flow rate adjusting valves 35 and 36 are respectively provided on the cooling water pipe 31 immediately before the refrigerator 3 and the cooling water bypass pipe 33. It is provided above.

  Furthermore, in the heat source system 1, as auxiliary equipment related to the flow of the cooling water, a water temperature gauge 34 for detecting the cooling water temperature on the cooling water forward pipe 30, and the temperature of the outside air used for heat radiation of the cooling water in the cooling tower An outside air thermometer (wet bulb thermometer) 37 for detecting the above is provided.

  The heat source system 1 is provided with a control unit 40 for controlling the system. The control unit 40 is electrically connected to each component of the heat source system 1 (the refrigerators 3 and 4, each pump, each flow rate adjustment valve, and the like), and is electrically connected to each auxiliary device included in the heat source system 1. By being connected, acquisition of information necessary for heat supply to the heat supply destination and various processes are executed. Various processes performed by the control unit 40 are realized by a computer program executed on the computer including a CPU, a memory, a hard disk, and the like, details of which will be described later.

As shown in FIG. 1, in the heat source system 1, in the refrigerator group, the refrigerator 3 and the refrigerator 4 are connected in series, and the flow of cold water and cooling water is in a counterflow state. Forming. In the heat source system 1 that employs the series connection of the refrigerators and the formation of the counterflow state as in the present invention, the system efficiency is higher than the case of the parallel connection of the refrigerators generally employed in the conventional heat source system. Improved. Therefore, improvement of system efficiency in the heat source system 1 will be described with reference to FIG.

  FIG. 2 shows the transition of the cooling water temperature and the cooling water temperature necessary for explaining the system efficiency of the heat source system 1 in the two cases (a) and (b). In both cases (a) and (b), the load required for the heat source system 1 is a rated load state, that is, a 100% load state. Case (b) shows the transition of the chilled water temperature and the like under conditions where the outside air temperature (wet bulb) is 3 ° C. higher than case (a).

  First, the case (a) will be described. The cold water temperature (cold water inlet temperature) before flowing into the evaporator 3a of the refrigerator 3 is 13.4 ° C., and the cold water temperature (cold water outlet temperature) immediately after coming out of the evaporator 3a. Is 8.9 ° C. Thereafter, the cold water is sent to the evaporator 4a of the refrigerator 4, and the cold water temperature (cold water outlet temperature) immediately after leaving the evaporator 4a becomes 4.4 ° C. On the other hand, the flow of the cooling water is opposite to that of the cold water, and the cooling water temperature (cooling water inlet temperature) before flowing into the condenser 4b of the refrigerator 4 is 32.0 ° C., and the cooling water comes out of the condenser 4b. The cooling water temperature immediately after (cooling water outlet temperature) is 35.0 ° C. Thereafter, the cooling water is sent to the condenser 3b of the refrigerator 3, and the cooling water temperature (cooling water outlet temperature) immediately after coming out of the condenser 3b is 38.0 ° C. From the above, the temperature difference between the cooling water outlet temperature and the cooling water outlet temperature in each refrigerator included in the refrigerator group employed in the heat source system 1 is 29.1 ° C. for the refrigerator 3 and 30.6 ° C. for the refrigerator 4. The average is 29.9 ° C.

  On the other hand, in a heat source system that employs a parallel connection of conventional refrigerators, when the chilled water temperature and the chilled water temperature are changed in the same manner as described above, the chilled water inlet temperature is changed in one chiller as shown in FIG. Is 13.4 ° C, the chilled water outlet temperature is 4.4 ° C, the cooling water inlet temperature is 32.0 ° C, and the cooling water outlet temperature is 38.0 ° C. As a result, the temperature difference between the cooling water outlet temperature and the cooling water outlet temperature is 33.6 ° C. for one refrigerator.

  Here, when the temperature difference in the heat source system 1 according to the present invention is compared with the temperature difference in the heat source system adopting the conventional parallel connection, the former is about 11% smaller. This means that the operating efficiency is improved by about 11% over the conventional heat source system. That is, like the heat source system 1, it is possible to greatly improve the operating efficiency of the refrigerator by connecting two refrigerators in series and placing the flow of cold water and cooling water in a counter flow state. I understand that.

  This is the same even when the outdoor wet bulb temperature (WB) is high as in the case (b). In case (b), the average temperature difference of each refrigerator in the heat source system 1 is 32.9 ° C, and the temperature difference of the refrigerator in the conventional heat source system is 36.6 ° C, so the former temperature difference is more It can be seen that the system efficiency is about 10% smaller than the heat source system 1 by about 10%.

As described above, the heat source system 1 according to the present invention has a configuration in which the system efficiency is improved as compared with the conventional one. Even in such a configuration, an output request is made to the heat source system 1. When the load (generally referred to as “output load” or “load factor” is expressed in the present embodiment as “output load”) in a partial load state, Since the operation state of each refrigerator is in a state where it cannot be operated with high efficiency, that is, each refrigerator is operated in a partial load state, there remains room for improving the system efficiency. For example, when the output load of the heat source system is a partial load of about 99% to 50%, one of the refrigerators 3 and 4 must be operated in a partial load state, and the output load is 70%. If it is about -50%, a refrigerator that is in a partial load state cannot cope with an underload output, so the operation of the refrigerator has to be switched on / off substantially. In operation control, a reduction in system efficiency of the heat source system 1 is inevitable.

Therefore, the operation control of the refrigerator in the heat source system 1 when the output load of the heat source system 1 is in a partial load state will be described with reference to FIGS. FIG. 3 is a diagram showing the transition of the operating conditions of each refrigerator in the heat source system 1 according to the present invention, and FIG. 4 is the transition of the operating conditions of the refrigerator as a comparison target of the operating conditions shown in FIG. FIG. As shown in FIG. 3, when the output load of the heat source system 1 is in the rated output load state (100% load state), as shown in the case (a) of FIG. The cold water inlet temperature of the refrigerator 3 is 13.4 ° C., and the cold water outlet temperature is 8.9 ° C. For the refrigerator 4 located on the downstream side, the cold water inlet temperature is 8.9 ° C., and the cold water outlet temperature is 4.4 ° C. And since these refrigerators are connected in series, the flow volume of the cold water which flows through both refrigerators is the same amount of 1680 m < ³ > / h. With the output capacity and flow rate in each refrigerator in this 100% load state as reference values, the ratio of the output capacity and flow rate of each refrigerator in each load state is hereinafter referred to as “output capacity ratio” and “flow rate ratio”. Calculate as The output capacity of each refrigerator is a value calculated based on the product of the difference between the cold water inlet temperature and the outlet temperature and the flow rate. In addition, the notation of the operating conditions in FIG. 4 is in accordance with the notation of FIG.

  Here, the operating condition of the refrigerator shown in FIG. 4 is that when the hardware configuration of the system is a series connection of two refrigerators and a counter flow state of cold water and cooling water as shown in FIG. As the output load of the chiller decreases from the 100% load state, the chilled water outlet temperature of each chiller decreases to the system output load while the temperature of the chilled water supplied from the chiller group to the heat supply destination is maintained at 4.4 ° C. This is an operating condition that is reduced in proportion to. That is, it is an operating condition in which the partial load state of the output load of the system and the partial load state of the refrigerator 3 and the refrigerator 4 are interlocked, and is a commonly performed control, as will be described later. This is a case where the control for setting the chilled water flow rate to an overflow state as shown in FIG. 3 or the control for bypassing the chilled water to one refrigerator is not performed. Under the operating conditions shown in FIG. 4, the flow rate of the cold water flowing through the refrigerator 3 and the refrigerator 4 is the same as the flow rate of the cold water in the 100% load state regardless of the fluctuation of the operation state of the system.

  Hereinafter, transition of the operating conditions of the refrigerator in the heat source system 1 according to the present invention will be described in comparison with the comparative example shown in FIG. In the heat source system 1, when the output load of the system is 90% to 70%, which is a partial load state, while maintaining the temperature of the cold water supplied to the heat supply destination at a predetermined supply temperature (4.4 ° C), The chilled water outlet temperature of the refrigerator is decreased in proportion to the decrease in the output load of the system. For example, although the operating temperature difference in the refrigerator 3 is 4.5 ° C. at 100% load, the cold water outlet temperature is adjusted to be 4.05 ° C. at 90% load. Therefore, the value of the chilled water outlet temperature of each refrigerator is the same as the operating condition shown in FIG.

  However, in the heat source system 1 according to the present invention, the chilled water flow rate is increased in inverse proportion to the decrease in the output load of the system so as to be in an overflow state. This overflow state means that the amount is increased compared to the flow rate in the 100% load state. Thus, in the partial load state where the output load of the heat source system 1 is 90% to 70%, the chilled water outlet temperature of each chiller is lowered and the chilled water flow rate is increased. The capacity ratio is maintained at 100%. For reference, since the chilled water flow rate is constant in the operating conditions shown in FIG. 4, the output capacity ratio of each refrigerator is decreased in conjunction with a decrease in the output load of the system. Can be seen to be very different. In the heat source system 1, the primary chilled water pump 5 is installed in the chilled water pipe 12 and the secondary chilled water pump 6 is installed in the forward header 11, so that it is possible to appropriately cope with an increase in the chilled water flow rate. . However, in this case, care should be taken so that the primary flow rate does not exceed the flow rate of the secondary pump 6.

Thus, the output load of the heat source system 1 is 90% to 90% by setting the cold water flow rate to an overflow state.
In the partial load state of 70%, it is possible to avoid operating each refrigerator of the refrigerator group in the partial load state. In addition, when the output load of the heat source system 1 is in a partial load state, it is preferable to adjust the chilled water flow rate so that the output capacity of each refrigerator is 100%, but at least the chilled water flow rate is 100% in the load state. The chilled water flow rate may be adjusted so as to bring the output capacity of each refrigerator closer to 100% by increasing the flow rate more than the flow rate.

  Next, the operating conditions of each refrigerator when the output load of the heat source system 1 is further reduced to a partial load state of about 60% will be described. In general, when the output load of the heat source system 1 is reduced to about 60%, the ambient wet bulb temperature taken in by the cooling tower 2 of the heat source system 1 in the intermediate period, night, winter, etc. in Japan, and in the Middle East region, Africa, etc. in the dry season is relatively high. Often times are low. In view of this point, in the heat source system 1, when the partial load state of about 60% is reached, it is expected that the temperature of the cooling water supplied to each refrigerator will be relatively low, and the refrigerator is overloaded. It is considered that it is possible to operate in a state (that is, a load state that requires an output capacity higher than that in a 100% load state).

  Specifically, as shown in FIG. 3, when the output load of the heat source system 1 is about 60%, the operation of the refrigerator 3 positioned on the upstream side in the flow of cold water is stopped. At the same time, the flow rate adjusting valves 16 and 18 are ON / OFF controlled so that the flow of cold water bypasses the evaporator 3a and flows into the cold water bypass pipe 13 so that the cold water does not flow into the evaporator 3a of the refrigerator 3. Is done. As a result, the cold water that has returned to the return header 10 bypasses the refrigerator 3 and is supplied to the refrigerator 4 and then supplied from the forward header 11 to the heat supply destination. In this state, in the operating refrigerator 4, the cold water inlet temperature corresponding to the 60% load state is set as shown in FIG. 3 (the cold water outlet temperature is set to a predetermined supply temperature of 4.4 ° C.). The flow rate is set in the same manner as the flow rate when the output load of the heat source system 1 is 100% load. As a result, since the refrigerator 4 bears the load that the refrigerator 3 should originally bear, the output capacity ratio becomes 120%. In the refrigerator 4, extremely efficient operation can be realized by utilizing the remaining capacity of the refrigerator's refrigerating capacity (that is, work in a range exceeding the output capacity ratio of 100%) caused by the decrease in the cooling water temperature.

  In addition, when the outside air wet bulb temperature fluctuates to such an extent that the operation of the refrigerator 4 in the overload state cannot be realized, the output capacity ratio of the refrigerator 4 is reduced to about 100% by reducing the cold water flow rate. adjust. Thereby, the influence of the outside air wet bulb temperature which fluctuates every moment can be eased. At this time, the operation stop state is maintained for the refrigerator 3 whose operation is stopped.

  Thus, when the heat source system 1 is in a partial load state of about 60%, the number of operating refrigerators is reduced, and the operating capacity of the operating refrigerator is at least about 100%, preferably Is operated in an overload state (for example, the output capacity ratio is about 120%), which greatly contributes to improving the system efficiency of the heat source system 1. In the comparative example shown in FIG. 4, since the two refrigerators are both operated at a partial load of 60%, the system efficiency in the case shown in FIG. 4 is worse than the case shown in FIG. Is clear.

  As described above, in the heat source system 1, even when the output load is in a partial load state, the operation control for improving the efficiency of the entire system is performed by appropriately adjusting the operation state of the refrigerator included therein. Done. Therefore, the operation control of the refrigerator will be described in more detail based on FIG. FIG. 5 is a flowchart of the refrigerator operation control executed by the control unit 40. Details of each process will be described below.

First, in S101, the output load PL of the heat source system 1 is calculated in response to a request from the heat supply destination. Specifically, the value obtained by multiplying the detection value of the return water temperature meter 14 and the detection value of the flow meter 15 is subtracted from the value obtained by multiplying the detection value of the return water temperature meter 20 and the detection value of the flow meter 21. The output load PL is calculated based on the value corresponding to the amount of heat energy that the heat source system 1 should supply to the heat supply destination. Since the calculation is a process that has been performed conventionally, a detailed description thereof will be omitted. The heat energy to be supplied may be calculated using a calorimeter that automatically calculates the amount of heat inside the device instead of multiplying the detected values of the water temperature meter and the flow meter. . Note that the output load PL of the heat source system 1 in the present embodiment is the cold water inlet of the evaporator 3 a of the refrigerator 3 (upstream of the cold water intake port of the cold water bypass pipe 13) and the cold water outlet of the evaporator 4 a of the refrigerator 4. It is defined as a value obtained by multiplying the temperature difference by the flow rate of cold water flowing therethrough. When the process of S101 ends, the process proceeds to S102.

  In S102, the optimum cooling water temperature that is the optimum temperature of the cooling water supplied from the cooling tower 2 to the refrigerator 4 is calculated based on the detection result of the outside air thermometer 37, and the cooling water at the optimum cooling water temperature is calculated. An instruction is given to the cooling tower 2 so that the supply is possible, and the opening degree of the flow rate adjustment valve 38 is adjusted based on the optimum cooling water temperature, so that the flow rate of the cooling water flowing through the cooling water return bypass pipe 39 Is controlled. The optimum cooling water temperature is also a value set as the cooling water inlet temperature of the refrigerator 4, and therefore, the processing after S105, S107, and S112, which will be described later, is the supply of the cooling water that is the optimum cooling water temperature. Is the premise. The optimum cooling water temperature is calculated according to a predetermined optimization method so that the efficiency of the heat source system 1 is improved based on the outside air temperature of the heat source system 1. In general, the optimum cooling water temperature is reduced as the outside air temperature decreases. The temperature is calculated as a lower value. When the process of S102 ends, the process proceeds to S103.

  In S103, it is determined whether or not the output load PL calculated in S101 belongs to a range of 100% ≧ PL> 60%. That is, it is determined whether or not the output load PL is in a state where the operation control should be performed in the 90% to 70% partial load state shown in FIG. If an affirmative determination is made in S103, the processing after S105 is performed, and if a negative determination is made, the processing after S104 is performed. In S104, it is determined whether or not the output load PL calculated in S101 belongs to a range of 60% ≧ PL> 50%. That is, it is determined whether or not the output load PL is in a state where the operation control should be performed in the 60% partial load state shown in FIG. If an affirmative determination is made in S104, the processing after S107 is performed, and if a negative determination is made, the processing after S112 is performed. Each process will be described below.

  First, the process after S105 after affirmation determination by S103 is demonstrated. In S105, the cold water outlet temperature of the refrigerator 3 on the upstream side in the flow of cold water is set according to the calculated value of the output load PL. That is, the temperature of the chilled water outlet temperature of the refrigerator 3 is set as in the partial load state where the output load PL shown in FIG. 3 is 90% to 70%. For example, when the output load PL is 90%, 80%, and 70%, they are set to 8.45 ° C., 8.0 ° C., and 7.55 ° C., respectively. Note that the outlet temperature of the refrigerator 4 is maintained at a predetermined supply temperature (4.4 ° C.) in the present embodiment. When the process of S105 ends, the process proceeds to S106.

  In S106, the chilled water flow rate flowing through the refrigerator 3 and the refrigerator 4 is increased to an overflow state according to the calculated value of the output load PL. That is, the flow rate ratio is set as in the partial load state where the output load PL shown in FIG. 3 is 90% to 70%. For example, when the output load PL is 90%, 80%, and 70%, the flow rate ratio is increased to 111%, 125%, and 143%, respectively.

  According to such processing of S105 and S106, if the output load PL of the heat source system 1 falls below 100% and exceeds 60%, the output capacity ratio of the refrigerator 3 and the refrigerator 4 is 100%. Since the operation is performed in a state, the operation efficiency of each refrigerator can be maintained relatively high regardless of the value of the output load PL. In particular, the improvement of the operation efficiency of the refrigerator is remarkable compared with the conventional operation control that reduces the load on the refrigerator according to the decrease of the output load PL, and the efficiency as the heat source system 1 is also good. To be improved.

  Next, the process after S107 after affirmation determination by S104 is demonstrated. In S107, the temperature of the cooling water supplied to the refrigerator group is the overload operation of the refrigerator 4 shown in FIG. 3 (that is, the operation in which only the refrigerator 4 is operated while the operation of the refrigerator 3 is stopped). It is determined whether the temperature falls within a possible temperature range. The cooling water temperature is a value detected by the water temperature gauge 34 after the opening degree of the flow rate adjustment valve 38 is adjusted so as to be the optimum cooling water temperature in S102. As described above, in order to perform the overload operation of the refrigerator 4, the refrigerator 4 needs to be placed in an environment where the overload operation can be performed. As an example, the refrigerator 4 is supplied to the refrigerator 4. The cooling water is required to be lower than the cooling water temperature assumed in the 100% load state (that is, the rated cooling water temperature). When the cooling water temperature is lower than the rated cooling water temperature, the refrigerator 4 can safely operate in an overload state that is equal to or higher than the assumed rated load (100% load) state. Therefore, if an affirmative determination is made in S107, the processing after S108 is performed, in which the operation control in the partial load state of 60% shown based on FIG. 3 is executed. If a negative determination is made in S107, the refrigerator 3 cannot be stopped and the refrigerator 4 cannot be overloaded, so that the processing from S105 onward is performed.

  Here, in S108, the operation of the refrigerator 3 is stopped to perform the overload operation of the refrigerator 4. At the same time, as described above, the flow path adjusting valves 16 and 18 are controlled so that the cold water does not flow into the refrigerator 3 as described above. Similarly, the flow path of the cooling water is switched so that the cooling water does not flow into the refrigerator 3 that is not operating. Specifically, the flow path adjustment valves 35 and 36 are controlled so that the cooling water flows through the cooling water bypass pipe 33 and bypasses the refrigerator 3. As described above, in the heat source system 1, the cold water and the cooling water are supplied only to the refrigerator 4, and only the refrigerator 4 is operated, and the above-described overload operation is started. When the process of S108 ends, the process proceeds to S109.

  In S109, a hunting prevention process is performed so that hunting that repeats re-operation and re-stop of the refrigerator that has been stopped in the process of S108 does not occur. Hunting is likely to occur when the value of the output load PL is close to the threshold value, and impairs the stability of the heat source system 1. Therefore, as the hunting prevention process, when the operation of the refrigerator 3 is stopped in S108, a process of prohibiting the re-operation of the refrigerator 3 for a certain period is performed. In addition, the cooling water temperature can be relatively stabilized by the process of setting the cooling water temperature in S102 to the optimum cooling water temperature, and as a result, the hunting prevention process can be easily performed. When the process of S109 ends, the process proceeds to S110.

  In S110, it is determined whether or not the temperature of the cold water supplied from the refrigerator 4 to the heat supply destination is maintained at a predetermined supply temperature (4.4 ° C.) in a state where the refrigerator 4 is overloaded. The This determination is to determine whether or not the cooling water temperature has risen due to fluctuations in the outside air wet bulb temperature and the refrigerator 4 can no longer realize a predetermined overload operation. That is, when cold water supply at a predetermined supply temperature cannot be performed, the refrigerator is in a state where a predetermined overload operation cannot be realized, and if the state is continued, the refrigerator 4 may be adversely affected. Therefore, if a negative determination is made in S110, the process proceeds to S111, the cold water flow rate is narrowed so that the output capacity ratio of the refrigerator 4 is about 100%, and if an affirmative determination is made in S110, the process of S111 is not performed. . As described above, since the cooling water temperature can be relatively stabilized by the process of setting the cooling water temperature in S102 to the optimum cooling water temperature, fluctuations in the cooling water temperature can be suppressed to be small. If the determination result of S110 is hunted due to a large fluctuation of the chilled water temperature, the efficiency of the heat source system 1 may be adversely affected. However, the process of S102 and the process of S111 associated therewith are accurately performed by the process of S102. Is possible.

According to such processing of S107 to S111, the number of operating refrigerators can be reduced, and the output capacity ratio of operating refrigerators can be set to 100% or more, preferably an overload state. The operation of the refrigerator 4 is realized with extremely high efficiency. Further, by bypassing the refrigerator 3 that is not in operation in the flow of cold water and cooling water, it becomes possible to reduce the pressure loss of each pump that occurs during the pumping of cold water and cooling water. The efficiency will be further improved.

  Next, the processes after S112 after the negative determination in S104 will be described. The negative determination in S104 means that the output load PL of the heat source system 1 is 50% or less. Therefore, in S112, the operation of the refrigerator 3 is stopped as in S108, and the flow rate adjusting valves 16, 18, 35, and 36 are controlled so that the cold water and the cooling water flow around the refrigerator 3. When the process of S112 ends, the process proceeds to S113. In S113, the chiller 4 in the operating state is increased to the overflow state in accordance with the calculated value of the output load PL with respect to the refrigerator 4 in the operating state substantially in the same manner as S106. The output capacity ratio is 100%.

  According to such processes of S112 and S113, the number of operating refrigerators can be reduced, and the operating efficiency of the operating refrigerator 4 can be maintained relatively high. Moreover, in the flow of chilled water and cooling water, the refrigeration machine 3 that is not operating is bypassed, so that it is possible to reduce the pressure loss that occurs when pumping the chilled water and cooling water, and the efficiency of the heat source system 1 is as follows. This will be further improved.

  When the processing of S101 to S113 is completed, whether or not to continue the operation of the heat source system 1 is determined in S114. About the continuation of the said operation | movement, it is judged whether the stop command from the central monitoring board which manages the heat-source system 1 etc. exists. If an affirmative determination is made here, the processing from S101 is performed again, and if a negative determination is made, the refrigerator operation control shown in FIG. 5 is terminated. In the above-described refrigerator operation control, the threshold value of the output load of the heat source system 1 that forcibly reduces the number of operating refrigerators (that is, the process of S112 is performed) is 50%, but this value is not necessarily fixed. It doesn't have to be a value. Preferably, when the cooling water temperature is equal to or higher than a predetermined temperature due to the outside air wet bulb temperature, the operation of the refrigerator 3 is set not to stop even when the output load PL is 50%. Further, the threshold value of the output load PL for forcibly reducing the number of operating refrigerators may be varied according to the value of the cooling water temperature.

  FIG. 6 shows an example of the power consumption rate (kW / Rt) of each refrigerator when the refrigerator operation control is performed. As can be seen from this, as the cooling water temperature rises, the power consumption rate rises and the operating efficiency of the refrigerator tends to decline. However, even if the output load PL of the heat source system 1 varies in the range of 20% to 100%, the power consumption rate of the refrigerator can be maintained at a value close to the power consumption rate at 100% load. This means that according to the refrigerator operation control, the operation efficiency of the refrigerator group can be maintained in a relatively high state regardless of the output load PL of the heat source system 1. In FIG. 6, a region surrounded by a thick line represents the power consumption rate of the refrigerator 4 when the operation of the refrigerator 3 is stopped and only the refrigerator 4 is operating.

  FIG. 7 shows a comparison result of the system efficiency between the heat source system 1 in which the operation control of the refrigerator is performed and other heat source systems. For each control method shown in FIG. 7, the chilled water overflow control mainly corresponds to the processing of S106 in the refrigerator operation control, and the refrigerator operation stop control is mainly S108 in the refrigerator operation control. It corresponds to the processing of. The secondary chilled water pump variable flow rate control is to adjust the pumping capacity of the secondary chilled water pump 6 to control the chilled water flow rate, which is a conventional control. The cooling water temperature optimization control corresponds to the process of S102 in the refrigerator operation control.

In Fig. 7, NO.1 is the measured value of power consumption in a normal district cooling plant (heat source system) with refrigerators connected in parallel in the Middle East, and the cooling water temperature is operated to a low level of around 25.0 ° C. Is. In FIG. 7, the energy saving rates of district cooling plants under various conditions are compared with the power consumption of No. 1 as a reference. NO.2 is a simulation of the case where the cooling water temperature optimization control is performed by connecting the refrigerators in parallel, and the efficiency is improved by 1% compared to NO.1.

  NO.3 is a case where the refrigerators are connected in series as in the heat source system 1 according to the present invention, but the case where the chilled water overflow control, the chiller operation stop control, and the cooling water temperature optimization control are not adopted. It is a simulation. The efficiency improvement rate in this case was 5% compared to NO.1. NO.4 is a simulation of the case where the coolant temperature optimization control is further adopted for NO.3, 10% for the standard NO.1, and 5% for comparison with NO.3. Plays an improvement in energy consumption. That is, by adopting the cooling water temperature optimization control in the mode of serial connection of the refrigerators, it is possible to obtain an energy saving effect that is about twice that of the conventional mode of parallel connection of refrigerators. In addition, NO.5 is a simulation of the case where chilled water overflow control, refrigerator operation stop control, and cooling water temperature optimization control are adopted with respect to NO.3. In this case, 14% improvement in energy consumption compared to standard No. 1 and 4% improvement in energy consumption compared to NO.4.

  Here, the effect of the cooling water temperature optimization control in the embodiment in which the refrigerators are connected in series as in the present invention will be described more specifically. In the conventional refrigerator parallel connection, the cooling water temperature is 32.0 ° C. at the inlet of the refrigerator and 38.0 ° C. at the outlet, as shown in FIG. In general, the lower limit value of the cooling water inlet temperature (that is, the lower limit temperature of the cooling water within the adjustable range by the cooling water temperature optimization control, the same shall apply hereinafter) for preventing the chiller main unit from stopping the alarm is about 22.0 ° C. The hourly outlet temperature is 28.0 ° C with 6.0deg ° C of the rated temperature difference. This condition does not change even when the number of refrigerators to be operated with a small load is reduced.

  On the other hand, in the heat source system 1 according to the present invention, the cooling water temperature of the refrigerator 4 is 32.0 ° C. at the inlet and 35.0 ° C. at the outlet, as shown in FIG. In this case as well, the lower limit value of the cooling water inlet temperature is similarly about 22.0 ° C. Therefore, if the number of operating refrigerators is one by the refrigerator operation stop control, if the lower limit value of the cooling water inlet temperature is about 22.0 ° C, the outlet temperature is 25.0 ° C with the rated temperature difference of 3.0deg ° C added. Thus, it can be operated 3.0 ° C lower than the conventional 28.0 ° C. In other words, under an operating situation where the load is reduced and the number of operating refrigerators is one, the cooling water temperature can always be lowered by about 3.0 ° C. compared to the conventional method. Therefore, the temperature drop ratio when the chilled water outlet temperature is 4.4 ° C. is 20.6 / 23.6 = 0.87, which can increase the efficiency of the refrigerator main body by about 13%. From the above, it can be said that the contribution to the improvement of the system efficiency of the refrigerator operation stop control and the cooling water temperature optimization control in the heat source system 1 according to the present invention is extremely remarkable as compared with the prior art.

<Arrangement of heat source system 1>
Next, a specific arrangement of the heat source system 1 according to the present invention will be described with reference to FIGS. In the present embodiment, the following description is made on the assumption that the heat source system 1 is constructed in the United Arab Emirates as described above, but there is no intention to limit the area to which the present invention is applied to the area. .

When the heat source system 1 according to the present invention is used for district cooling in the United Arab Emirates, it is considered that 20000 Rt to 40000 Rt is required as the cooling capacity of the entire system. If it is set to about 2000 Rt to 2500 Rt, the heat source system 1 needs 8 to 20 refrigerators. Here, reference will be made to plant construction for actually constructing the heat source system 1. Generally, a plant building for a heat source system is often constructed as a plant-dedicated building, and conventionally, there are many examples in which the distance between pillars of a building is about 6 to 7.5 m as shown in FIG. FIG. 8 is a diagram schematically showing a conventional arrangement and a column position of a plant building when eight refrigerators are installed in the heat source system.

Conventionally, the plant facility designer (that is, the designer of the heat source system 1 itself) and the plant building architect are often different. Therefore, only the main specifications of the plant, such as the area, required floor height, design load, etc. required for installation of the main equipment of the heat source system such as the refrigerator and cooling tower are transmitted from the plant equipment designer to the building designer. Therefore, it can be said that the design of the plant building and the arrangement of the refrigerators are not necessarily in an appropriate state because the building designer performs the building design according to the value so as to ensure the necessary strength as the plant building. There wasn't. Therefore, the above column spacing of 6 to 7.5 m is also the value of the column spacing obtained when the design load of the plant building floor is 2.0 to 3.0 ton / m ² which is generally adopted, and there is a heat source there. Correlation between system components (such as refrigerators) is not considered.

  Therefore, in the conventional architectural design of a plant building, a mode in which one refrigerator is installed in one column span as shown in FIG. In addition, in the aspect of connecting the chillers that have been widely spread from the past in parallel to the heat supply destination, each chiller requires a chilled water pump for chilled water circulation and a chilled water pump for cooling water circulation, From the viewpoint of securing these pump installation areas and securing the space for maintenance such as tube replacement of pumps and refrigerators, it is considered that the limit is to install one refrigerator in one span of the pillar.

  In the conventional plant building design, as shown in FIG. 9, pipes for cold water and cooling water, collecting pipes where each pipe gathers (forward header, return header, etc.), cables distributed to refrigerators, etc. Is generally laid in the upper space of the refrigerator having a relatively large space. With respect to the collecting pipe, when the refrigeration capacity of the heat source system is about 20000 Rt, the diameter is about 900 to 1000 mm. Therefore, it is considered that the above-mentioned upper space having a space margin is widely used. When using the upper space in this way, the maintenance position of piping-related equipment (for example, control valves, etc.) is located at a high location, increasing the work load during maintenance and ensuring the safety of workers. You have to be very careful.

  Furthermore, in order to realize the arrangement of the pipes and the like shown in FIG. That is, in order to lay pipes and the like in the upper space of the refrigerator, as shown in FIG. 10, heavy objects such as pipes, headers and supporting H-shaped steel are lifted by a chain block or a portal hydraulic lifter. It is necessary to pay close attention to ensuring safety at that time. Thus, in the design of the conventional plant building, it is considered that the configuration is not necessarily optimal for arranging the heat source system.

  Then, about the heat source system 1 which concerns on this invention, paying attention to the point that it becomes the structure which connects two refrigerators in series and forms a refrigerator group, the plant building which stores the said heat source system 1 This structure is the structure shown in FIG. In this case, the column span is 10 to 11 m longer than the conventional one. And two refrigerators which comprise the refrigerator group of the heat-source system 1 are arrange | positioned in 1 division defined by four pillars arrange | positioned at the space | interval. At the same time, a chilled water pump and a chilled water pump corresponding to the refrigerator group are also arranged in the one section. That is, in the heat source system 1, a chilled water pump (primary chilled water pump 5 shown in FIG. 1) and a cooling water pump (cooling water pump 7 shown in FIG. 1) are installed for one refrigerator group. The pump and the refrigerator group are grouped together, and are configured to be accommodated in the one section formed by the column span set relatively wide. Therefore, the heat source system 1 shown in FIG. 11 is a system in which four groups of refrigerators in which two refrigerators are connected in series are connected in parallel.

By designing the plant building shown in FIG. 11, the refrigerator can be stored compactly in the building, in other words, equipment such as the refrigerator can be centrally arranged, so that it is shown in FIG. 8. Compared to conventional building design, the required construction length of piping and the number of joints that connect the piping can be reduced, and the length of power cables for refrigerators, etc., and the amount of cable laying work are reduced. Can also be realized. Moreover, in the present Example, since two refrigerators are connected in series, the length of piping around the equipment can be reduced. Here, reducing the construction length of the piping also leads to a reduction in pressure loss at the time of pumping by the chilled water pump or the chilled water pump, thereby promoting improvement in efficiency of the heat source system 1.

In addition, as shown in Fig. 11, a new building configuration is required, such as increasing the slab thickness or increasing the slab thickness in the plant building by expanding the column span as compared with the conventional structure. It becomes. However, in consideration of the total floor area required for installing the refrigerator constituting the heat source system 1, in the form shown in FIG. 8 which is a conventional design form, 16 sections are required for installing the eight refrigerators. In the form shown in FIG. 11, which is the design form of the present invention, six sections are required. Compared with the area itself, the conventional design form requires 900 m ^2, but the design form of the present invention can reduce the required area to 600 m ² . Therefore, since the size of the plant building itself can be reduced, the structural strength required for the building is increased. However, there is a possibility that the necessity of a new building configuration that is required can be offset.

  For laying pipes, headers, etc., as shown in FIG. 12, a pit for laying pipes is constructed on the floor, and pipes, headers, etc. are laid there. Therefore, the laying position of piping or the like is a position close to the floor surface where the refrigerator is installed. This eliminates the need for heavy lifting work, and the piping and the refrigerator are installed at a height close to the piping, reducing the length of piping and the amount of piping and cable laying. Can be planned.

  In such a pit construction for pipe laying, as described above, a space for the pit construction can be secured more easily by expanding the column span of the plant building. Also, by constructing a pipe pit and lowering pipes and headers to the floor level, the floor height for storing the heat source system can be made lower than before (in the example shown in FIG. Are compressed). For this reason, since it can be roughly offset by the floor surface popping out by the piping laying pit and the compression of the floor height, it is possible to avoid the height of the plant building from becoming higher by adopting the configuration shown in FIG.

  Further, by adopting the expansion of the column span and the construction of the pipe laying pit, which is the design aspect of the plant building according to the present invention, the refrigerator, the pipe, the header, etc. can be arranged in a plane as shown in FIG. Therefore, the dimensions between the refrigerator and the header can be accurately measured. As a result, it is possible to increase the processing accuracy of the prefab at the processing plant for piping and the like, and the manufacturing processing plant of the plant building, thereby reducing the loss rate and shortening the construction period of the plant equipment.

DESCRIPTION OF SYMBOLS 1 ... Heat source system 2 ... Cooling tower 3, 4 ... Refrigerator 3a, 4a ... Evaporator 3b, 4b ... Condenser 5 ... Primary chilled water pump 6・ ・ ・ ・ Secondary cold water pump 7 ・ ・ ・ ・ Cooling water pump 10 ・ ・ ・ ・ Return header 11 ・ ・ ・ ・ Out header 12 ・ ・ ・ ・ Cold water piping 13 ・ ・ ・ ・ Cool water bypass piping 30 ・ ・ ・ ・Cooling water forward piping 31 ... Cooling water piping 32 ... Cooling water return piping 33 ... Cooling water bypass piping 40 ... Control unit

Claims (9)

A cooling tower,
A refrigerator group formed including a first refrigerator and a second refrigerator each having an evaporator and a condenser;
A cooling water pipe for supplying cooling water from the cooling tower in series to a condenser included in each refrigerator of the refrigerator group;
A cooling water pump for pumping cooling water in the cooling water pipe;
A chilled water pipe for supplying chilled water in series to the flow direction opposite to the flow direction of the cooling water in the cooling water pipe, with respect to the evaporator of each chiller of the chiller group;
A cold water pump that pumps cold water in the cold water pipe, and a heat source system that supplies heat energy to the heat supply destination via cold water,
The heat source system includes:
A load calculating unit that calculates an output load of the refrigerator group based on a heat energy amount that the heat source system should supply to a heat supply destination;
The temperature of the cold water supplied to the heat supply destination via the cold water pipe via the first refrigerator and the second refrigerator is set to a predetermined supply temperature regardless of the output load calculated by the load calculation unit. A first control unit for controlling the first refrigerator and the second refrigerator;
As the output load calculated by the load calculation unit becomes smaller than the rated output load of the refrigerator group, the chilled water flow rate flowing through the chilled water piping is compared with the rated chilled water flow rate flowing through the chilled water piping at the rated output load. A second control unit for controlling the cold water pump to increase the amount;
A heat source system further comprising: In the first refrigerator and the second refrigerator, a temperature difference that is a difference between an inlet temperature of cold water flowing into an evaporator included in each refrigerator and an outlet temperature of cold water flowing out of the evaporator, and the second refrigerator The respective output capacities of the first refrigerator and the second refrigerator, which are determined based on the flow rate of the cold water flowing through the cold water pipe controlled by the control unit, are the first capacity at the rated output load of the refrigerator group. The second control unit determines the flow rate of cold water flowing through the cold water pipe so that the output capacity of the single refrigerator and the second refrigerator is the same.
The heat source system according to claim 1. A cooling water return bypass pipe for connecting the outgoing pipe to the refrigerator group in the cooling water pipe and the return pipe from the refrigerator group without passing through the refrigerator group;
Calculating a set temperature of cooling water flowing through the cooling water pipe based on at least an outside temperature of the heat source system, and controlling a flow rate of cooling water flowing through the cooling water return bypass pipe based on the set temperature of the cooling water; Three control units;
The heat source system according to claim 1, further comprising: In cold water flow in the cold water pipe, cold water bypass means for bypassing the cold water so as not to flow into the evaporator of the first refrigerator,
When the output load calculated by the load calculation unit is equal to or lower than a predetermined output load, the operation of the first refrigerator is stopped, and cold water is supplied to the second cold water in the cold water flow in the cold water pipe by the cold water bypass means. A refrigerator operation control unit that supplies only to the evaporator of the refrigerator, and
The heat source system according to any one of claims 1 to 3. When the operation of the first refrigerator is stopped by the refrigerator operation control unit, the first control unit also outputs the output that should be taken when the stopped first refrigerator is in an operating state. As the second refrigerator bears, the second refrigerator is output in an overload state larger than the load at the rated output load,
The heat source system according to claim 4. When the operation of the first refrigerator is stopped by the refrigerator operation control unit, the second control unit determines a flow rate of cold water to be supplied to the second refrigerator through the cold water pipe and the rated cold water flow rate. And
The heat source system according to claim 5. In the flow of cooling water in the cooling water pipe, further comprising a cooling water bypass means for bypassing the cooling water so as not to flow into the condenser of the first refrigerator,
The refrigerator operation control unit supplies cooling water only to the condenser of the second refrigerator in the cooling water pipe by the cooling water bypass means when the operation of the first refrigerator is stopped,
The heat source system according to any one of claims 4 to 6. The second control unit flows through the cooling water pipe when the temperature of the cooling water supplied to the second refrigerator via the cooling water pipe exceeds a predetermined rated cooling water temperature corresponding to the rated cold water flow rate. The cold water flow rate to be supplied to the second refrigerator is a flow rate smaller than the rated cold water flow rate,
The heat source system according to claim 5. The predetermined output load is adjusted based on a temperature of cooling water supplied to the second refrigerator through the cooling water pipe.
The heat source system according to any one of claims 4 to 8.

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