Cooling tower and chiller combined cooling system and control method thereof

Abstract

The present application relates to a kind of cooling tower and refrigerating machine combined cooling system and its control method, the system includes heat exchange load, circulating water subsystem and cooling water subsystem, heat exchange load is respectively provided with water inlet end and water outlet end, circulating water subsystem includes cooling tower, water collecting tank, circulating water pump, water inlet pipeline and backwater pipeline, cooling water subsystem includes cold water tank, cold water pump, refrigerating machine, cold water outlet pipeline, cooling water pipeline and cold water backwater pipeline, water inlet pipeline is sequentially communicated cooling tower, water collecting tank, circulating water pump to the water inlet end of heat exchange load, backwater pipeline is communicated with the water outlet end and cooling tower, cold water outlet pipeline is sequentially communicated cold water tank, cold water pump to the inlet end of evaporator, cooling water pipeline is communicated with the outlet end of evaporator and water inlet end, and cold water backwater pipeline is communicated with the water outlet end and cold water tank.Cold water tank, cold water pump to the inlet end of evaporator, cooling water pipeline is communicated with the outlet end of evaporator and water inlet end, and cold water backwater pipeline is communicated with the water outlet end and cold water tank.The present application can switch different operating modes according to the change of ambient wet bulb temperature, realize the best energy-saving effect of cooling system operation.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of cooling system, in particular to a cooling tower and refrigerating machine combined cooling system and a control method thereof. BACKGROUND

[0002] The cooling tower is a device that uses water as a circulating coolant to absorb heat from the system and discharge to the atmosphere to reduce water temperature; its cooling system is completed by the water evaporation process, and the cooling water can be recycled.

[0003] The cooling method of the cooling tower is to spray hot water to the surface of the heat dissipation material and contact with moving air. At this time, heat exchange occurs between hot water and cold air, and part of the hot water is evaporated, that is, the latent heat of evaporation in the evaporated water vapor is discharged to the air, and finally the cooled water falls into the water tank and is transmitted to the heat exchanger by the pump to absorb heat.

[0004] In the circulating system of the refrigerating machine, the compressor sucks in low-temperature and low-pressure refrigerant vapor from the evaporator, and the low-temperature and low-pressure refrigerant vapor is compressed into high-temperature and high-pressure superheated vapor by the compressor, and then is pressed into the condenser to cool at constant pressure and release heat to the cooling medium, and then is cooled into supercooled liquid refrigerant. The liquid refrigerant is throttled into low-pressure liquid refrigerant by the expansion valve, and evaporates in the evaporator to absorb the heat in the air conditioning circulating water (air), thereby cooling the air conditioning circulating water to achieve the purpose of refrigeration, and the low-pressure refrigerant is sucked into the compressor, and the cycle is repeated.

[0005] In industrial production, the cooling tower and the refrigerating machine are widely used in constant temperature control of heat exchange load, and each has advantages and disadvantages. The cooling tower exchanges heat with air and provides cooling water, and the main energy consumption is the fan motor of the cooling tower, which has low power and is relatively energy-saving, but the inlet and outlet water temperature changes with the outdoor air temperature and humidity, so the cooling tower is not suitable for some heat exchange temperature control conditions that require lower or close to the outdoor wet-bulb temperature. The refrigerating machine controls the temperature by connecting the compressor and the temperature sensor, and the inlet and outlet water temperature is relatively constant. Different refrigerating machines with different temperature ranges can be selected according to different working conditions, and the temperature control is relatively reliable. However, the energy consumption of the refrigerating machine is very high, which is not conducive to controlling production cost and energy saving. In view of the above situation, it is necessary to jointly control the cooling tower and the refrigerating machine group, adjust different operating modes according to the change of the environmental wet-bulb temperature, and realize comprehensive energy saving. SUMMARY

[0006] The technical problem to be solved by the present application is to provide a cooling tower and refrigerating machine combined cooling system and a control method thereof, which can switch different operating modes according to the change of the environmental wet-bulb temperature, and realize the best energy-saving effect of the cooling system operation.

[0007] The application is achieved by providing a cooling tower and refrigerating machine combined cooling system, a fan is arranged on the cooling tower, a compressor, a condenser and an evaporator are respectively arranged in the refrigerating machine, the system comprises a heat exchange load, a circulating water subsystem and a cooling water subsystem, the heat exchange load is respectively provided with an inlet end and an outlet end, the circulating water subsystem comprises the cooling tower, a water collecting tank, a circulating water pump, an inlet pipeline and a return pipeline, the cooling water subsystem comprises a cold water tank, a cold water pump, the refrigerating machine, a cold water outlet pipeline, a cooling water pipeline and a cold water return pipeline, the inlet pipeline is connected in sequence with the outlet end of the cooling tower, the water collecting tank, the circulating water pump and the inlet end of the heat exchange load, the return pipeline connects the outlet end of the heat exchange load with the return end of the cooling tower, the cold water outlet pipeline is connected in sequence with the outlet end of the cold water tank, the cold water pump and the inlet end of the evaporator of the refrigerating machine, the cooling water pipeline connects the outlet end of the evaporator with the inlet end of the heat exchange load, the cold water return pipeline connects the outlet end of the heat exchange load with the inlet end of the cold water tank, the inlet pipeline and the cooling water pipeline are parallel to each other, the return pipeline and the cold water return pipeline are parallel to each other, the inlet end of the condenser is connected with the inlet pipeline through a first pipeline, the outlet end of the condenser is connected with the return end of the cooling tower through a second pipeline; an ambient wet bulb temperature transmitter is arranged on the periphery of the cooling tower, a first temperature sensor is arranged on the inlet pipeline close to the water collecting tank, a first automatic switch valve and a second automatic switch valve are respectively arranged on the first pipeline, the second automatic switch valve is close to the inlet end of the condenser, a third automatic switch valve and a fourth automatic switch valve are respectively arranged on the cold water outlet pipeline, the third automatic switch valve is close to the inlet end of the evaporator, the fourth automatic switch valve is close to the outlet end of the cold water tank, the cold water pump is arranged between the third automatic switch valve and the fourth automatic switch valve, a fifth automatic switch valve is arranged on the inlet pipeline close to the inlet end of the heat exchange load, a sixth automatic switch valve is arranged on the return pipeline close to the outlet end of the heat exchange load, a second temperature sensor and a seventh automatic switch valve are respectively arranged on the cooling water pipeline, a first flow meter is arranged on the pipeline of the inlet end of the heat exchange load, a third temperature sensor is arranged on the pipeline of the outlet end of the heat exchange load, an eighth automatic switch valve is arranged on the cold water return pipeline, a third pipeline is further arranged on the inlet pipeline and connected with the cold water outlet pipeline, one end of the third pipeline is connected to the cold water outlet pipeline between the fourth automatic switch valve and the cold water pump, a ninth automatic switch valve is arranged on the third pipeline, an intermediate connecting pipeline is arranged between the first pipeline and the cold water return pipeline, one end of the intermediate connecting pipeline is connected to the first pipeline between the first automatic switch valve and the second automatic switch valve, a tenth automatic switch valve is arranged on the intermediate connecting pipeline; the control signals of the ambient wet bulb temperature transmitter and the first temperature sensor are respectively configured to be interlocked with the fan, the control signals of the first temperature sensor and the second temperature sensor are respectively configured to be interlocked with the refrigerating machine.

[0008] Further, in the system, one or more cooling towers, circulating water pumps, cold water pumps, refrigerators are set according to the need.

[0009] Further, in the system, four cooling towers, two circulating water pumps, two cold water pumps and one refrigerator are set.

[0010] Further, a first pressure transmitter is further set on the water inlet pipeline, and the control signals of the first pressure transmitter and the circulating water pumps are configured to be interlocked.

[0011] Further, a second pressure transmitter is further set on the cold water outlet pipeline, and the control signals of the second pressure transmitter and the cold water pumps are configured to be interlocked.

[0012] Further, in the system, a circulating water blowdown subsystem is further set, which comprises a blowdown pipeline, a first flowmeter and an adjusting valve set on the blowdown pipeline, and an online turbidity meter, the blowdown pipeline is communicated with the water inlet pipeline, the online turbidity meter is set on the water inlet pipeline, and the control signals of the online turbidity meter and the first flowmeter and the adjusting valve are configured to be interlocked.

[0013] Further, a circulating water makeup subsystem is further set on the water collecting tank, which comprises a circulating water makeup pipeline and a makeup flowmeter set on the circulating water makeup pipeline, and a float valve set on the water collecting tank, the circulating water makeup pipeline is communicated with the water collecting tank.

[0014] Further, a cooling water makeup subsystem is further set on the cold water tank, which comprises a cold water makeup pipeline and a self-control valve set on the cold water makeup pipeline, and a liquid level transmitter set on the cold water tank, the cold water makeup pipeline is communicated with the cold water tank, and a fourth temperature sensor is set on the cold water tank.

[0015] Further, a second flowmeter is set on the pipeline of the water inlet end of the heat exchange load.

[0016] The application is implemented in the following manner, a control method of the cooling tower and refrigerator combined cooling system is provided, which comprises the following steps:

[0017] Step one, when the ambient wet bulb temperature detected by the ambient wet bulb temperature transmitter is less than or equal to the cooling set temperature of the heat exchange load, and the detection cumulative duration exceeds 0.5-2.5h, the system adopts the cooling tower alone to prepare cooling water mode - mode one, at this time, the fifth automatic switch valve and the sixth automatic switch valve are in the open state respectively, the first automatic switch valve, the second automatic switch valve, the third automatic switch valve, the seventh automatic switch valve, the eighth automatic switch valve, the ninth automatic switch valve and the tenth automatic switch valve are in the closed state respectively, the circulating water pump is started, and the refrigerating machine and the cold water pump stop running.

[0018] Step two, when the cooling set temperature of the heat exchange load is less than the ambient wet bulb temperature detected by the ambient wet bulb temperature transmitter, and the ambient wet bulb temperature is less than 3-6℃ higher than the cooling set temperature of the heat exchange load, and the detection cumulative duration exceeds 0.5-2.5h, the system automatically switches to the cooling tower and the refrigerating machine in series to prepare cooling water mode - mode two (a), at this time, the second automatic switch valve, the third automatic switch valve, the seventh automatic switch valve, the ninth automatic switch valve and the tenth automatic switch valve are in the open state respectively, the fifth automatic switch valve and the sixth automatic switch valve are in the closed state respectively, the cold water pump is started, and the compressor of the refrigerating machine is started.

[0019] Step three, when the ambient wet bulb temperature detected by the ambient wet bulb temperature transmitter is greater than or equal to 3-6℃ higher than the cooling set temperature of the heat exchange load during the operation of mode two (a), and the detection cumulative duration exceeds 0.5-2.5h, it is switched to the cooling tower and the refrigerating machine in parallel to prepare cooling water mode - mode three, at this time, the first automatic switch valve, the fourth automatic switch valve and the eighth automatic switch valve are switched to the open state, the ninth automatic switch valve and the tenth automatic switch valve are switched to the closed state, and the states of other automatic switch valves remain unchanged; the cold water pump and the compressor of the refrigerating machine are still in the running state.

[0020] Step four, when the cooling set temperature of the heat exchange load is less than the ambient wet bulb temperature detected by the ambient wet bulb temperature transmitter, and the ambient wet bulb temperature is less than 3-6℃ higher than the cooling set temperature of the heat exchange load during the operation of mode three, and the detection cumulative duration exceeds 0.5-2.5h, it is switched to mode two (a) operation.

[0021] Step five, when the ambient wet bulb temperature detected by the ambient wet bulb temperature transmitter is less than or equal to the cooling set temperature of the heat exchange load during the operation of mode two (a), it is switched to mode two (b) operation, which is different from mode two (a) only in that the compressor of the refrigerating machine stops running, and the others are the same as mode two (a).

[0022] Step six, when in mode two (b) during the operation, the ambient wet bulb temperature detected by the ambient wet bulb temperature transmitter appears ≤ cooling set temperature of heat exchange load, and the detection cumulative duration exceeds 0.5-2.5h, switch to mode one operation.

[0023] Compared with the prior art, the cooling tower and refrigerating machine combined cooling system and the control method thereof have the following characteristics:

[0024] (1) According to the change of the ambient wet bulb temperature, different operation modes are switched, the system runs stably, and the overall energy-saving effect of the cooling system is realized.

[0025] (2) The fan of the cooling tower, the wet bulb temperature and the cooling tower outlet water temperature are interlocked controlled, so that the efficient operation of the cooling tower and the reduction of power consumption are ensured.

[0026] (3) The system also sets a circulating water blowdown subsystem, so that the water quality of the system is controlled within a certain turbidity range, and the fouling phenomenon of the heat exchanger in the heat exchange load of the system is effectively prevented. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is a principle schematic view of a preferred embodiment of the cooling tower and refrigerating machine combined cooling system of the present application;

[0028] Figure 2 is a corresponding schematic view of the working mode and steps in the control method of the cooling tower and refrigerating machine combined cooling system of the present application;

[0029] Figure 3 is a principle schematic view of mode one in the control method of the cooling tower and refrigerating machine combined cooling system of the present application;

[0030] Figure 4 is a principle schematic view of mode two (a) and mode two (b) in the control method of the cooling tower and refrigerating machine combined cooling system of the present application;

[0031] Figure 5 is a principle schematic view of mode three in the control method of the cooling tower and refrigerating machine combined cooling system of the present application. DETAILED DESCRIPTION

[0032] In order to make the technical problems, technical solutions and beneficial effects of the present application clearer, the present application will be further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application, and are not used to limit the present application.

[0033] Please refer to Figure 1As shown, the preferred embodiment of the cooling tower and refrigeration machine combined cooling system of the present application comprises a heat exchange load 1, a circulating water subsystem 2 and a cooling water subsystem 3. The dashed lines in the figure show the signal control lines, and the solid lines with arrows show the flow direction of the materials (such as circulating water, cold water, cooling water, etc.) in the system. The circulating water flows in the circulating water subsystem 2, and the cold water and cooling water flow in the cooling water subsystem 3.

[0034] The heat exchange load 1 is provided with an inlet end 11 and an outlet end 12 respectively. The circulating water subsystem 2 comprises a cooling tower 21, a collecting tank 22, a circulating water pump 23, an inlet pipe 24 and a return pipe 25. The cooling water subsystem 3 comprises a cold water tank 31, a cold water pump 32, a refrigeration machine 33, a cold water outlet pipe 34, a cooling water pipe 35 and a cold water return pipe 36.

[0035] The inlet pipe 24 is connected in sequence to the outlet end of the cooling tower 21, the collecting tank 22, the circulating water pump 23 and the inlet end 11 of the heat exchange load 1, and the return pipe 25 connects the outlet end 12 of the heat exchange load 1 with the return end of the cooling tower 21. A fan (not shown in the figure) is arranged on the cooling tower 21. A compressor (not shown in the figure), a condenser 37 and an evaporator 38 are arranged in the refrigeration machine 33 respectively.

[0036] The cold water outlet pipe 34 is connected in sequence to the outlet end of the cold water tank 31, the cold water pump 32 and the inlet end of the evaporator 38 of the refrigeration machine 33, the cooling water pipe 35 connects the outlet end of the evaporator 38 with the inlet end 11 of the heat exchange load 1, and the cold water return pipe 36 connects the outlet end 12 of the heat exchange load 1 with the inlet end of the cold water tank 31. The inlet end 11 of the heat exchange load 1 is connected with the inlet pipe 24 and the cooling water pipe 35 respectively, and the outlet end 12 of the heat exchange load 1 is connected with the return pipe 25 and the cold water return pipe 36 respectively. The inlet pipe 24 and the cooling water pipe 35 are connected in parallel with each other, and the return pipe 25 and the cold water return pipe 36 are connected in parallel with each other.

[0037] The inlet end of the condenser 37 is connected with the inlet pipe 24 through a first pipe 4, and the outlet end of the condenser 37 is connected with the return end of the cooling tower 21 through a second pipe 5. An ambient wet bulb temperature transmitter 26 is arranged on the periphery of the cooling tower. A first temperature sensor 27 is arranged on the inlet pipe 24 close to the collecting tank 22. A first automatic on-off valve 41 and a second automatic on-off valve 42 are arranged on the first pipe 4 respectively, and the second automatic on-off valve 42 is close to the inlet end of the condenser 37. A third automatic on-off valve 43 and a fourth automatic on-off valve 44 are arranged on the cold water outlet pipe 34 respectively, the third automatic on-off valve 43 is close to the inlet end of the evaporator 38, and the fourth automatic on-off valve 44 is close to the outlet end of the cold water tank 31. The cold water pump 32 is arranged between the third automatic on-off valve 43 and the fourth automatic on-off valve 44.

[0038] A fifth automatic switch valve 45 is arranged on the water inlet pipeline 24 near the water inlet end 11 of the heat exchange load 1, a sixth automatic switch valve 46 is arranged on the water return pipeline 25 near the water outlet end 12 of the heat exchange load 1, a second temperature sensor 39 and a seventh automatic switch valve 47 are arranged on the cooling water pipeline 35 respectively, a first flowmeter 28 is arranged on the pipeline of the water inlet end 11 of the heat exchange load 1, and a third temperature sensor 29 is arranged on the pipeline of the water outlet end 12 of the heat exchange load 1. An eighth automatic switch valve 48 is arranged on the cold water return pipeline 36.

[0039] A third pipeline 6 is further arranged on the water inlet pipeline 24 and communicates with the cold water outlet pipeline 34. One end of the third pipeline 6 is connected to the cold water outlet pipeline 34 between the fourth automatic switch valve 44 and the cold water pump 32. A ninth automatic switch valve 49 is arranged on the third pipeline 6, and an intermediate connecting pipeline 7 is arranged between the first pipeline 4 and the cold water return pipeline 36. One end of the intermediate connecting pipeline 7 is connected to the first pipeline 4 between the first automatic switch valve 41 and the second automatic switch valve 42. A tenth automatic switch valve 410 is arranged on the intermediate connecting pipeline 7.

[0040] The control signals of the ambient wet bulb temperature transmitter 26 and the first temperature sensor 27 are respectively configured to be interlocked with the control signals of the fan. The control signals of the first temperature sensor 27 and the second temperature sensor 39 are respectively configured to be interlocked with the control signals of the refrigerating machine 33.

[0041] In the system, one or more cooling towers 21, circulating water pumps 23, cold water pumps 32 and refrigerating machines 33 are arranged as required. In the system of the embodiment, four cooling towers 21, two circulating water pumps 23, two cold water pumps 32 and one refrigerating machine 33 are arranged.

[0042] A first pressure transmitter 210 is further arranged on the water inlet pipeline 24, and the control signals of the first pressure transmitter 210 are respectively configured to be interlocked with the control signals of the circulating water pump 23.

[0043] A second pressure transmitter 310 is further arranged on the cold water outlet pipeline 34, and the control signals of the second pressure transmitter 310 are respectively configured to be interlocked with the control signals of the cold water pump 32.

[0044] In the system, a circulating water blowdown subsystem 8 is further arranged. The circulating water blowdown subsystem 8 comprises a blowdown pipeline 81, a first flowmeter 82 and a regulating valve 83 arranged on the blowdown pipeline 81, and an online turbidimeter 84. The blowdown pipeline 81 communicates with the water inlet pipeline 24. The online turbidimeter 84 is arranged on the water inlet pipeline 24. The control signals of the online turbidimeter 84 and the first flowmeter 82 are respectively configured to be interlocked with the control signals of the regulating valve 83.

[0045] When the on-line turbidity meter 84 detects that the turbidity of the circulating water in the water inlet pipeline 24 is ≥10 mg / L, the regulating valve 83 on the blowdown pipeline 81 is automatically opened, and the blowdown flow is controlled by setting the parameters of the first flow meter 82, and when the turbidity of the circulating water is ≤8 mg / L, the regulating valve 83 on the blowdown pipeline 81 is automatically closed.

[0046] A circulating water replenishing subsystem 9 is further arranged on the collecting tank 22. The circulating water replenishing subsystem 9 comprises a circulating water replenishing pipeline 91 and a replenishing flow meter 92 arranged on the circulating water replenishing pipeline 91, and further comprises a float ball valve 93 arranged on the collecting tank 22, and the circulating water replenishing pipeline 91 is in communication with the collecting tank 22.

[0047] A cooling water replenishing subsystem 10 is further arranged on the cold water tank 31. The cooling water replenishing subsystem 10 comprises a cold water replenishing pipeline 101 and a self-control valve 102 arranged on the cold water replenishing pipeline 101, and further comprises a liquid level transmitter 103 arranged on the cold water tank 31, and the cold water replenishing pipeline 101 is in communication with the cold water tank 31, and a fourth temperature sensor 311 is arranged on the cold water tank 33.

[0048] A second flow meter 13 is arranged on the pipeline of the water inlet end 11 of the heat exchange load 1.

[0049] Please refer to Figures 1 to 5 It is disclosed that the application further discloses a control method of the cooling tower and refrigerating machine combined cooling system as described above, which comprises the following steps:

[0050] Step one: when the ambient wet bulb temperature detected by the ambient wet bulb temperature transmitter 26 is ≤ the cooling set temperature of the heat exchange load 1, and the detection cumulative time length exceeds 0.5-2.5 h, the system adopts the cooling tower 21 alone to prepare cooling water mode - mode one. As shown in the figure. Figure 3 At this time, the fifth automatic switch valve 45 and the sixth automatic switch valve 46 are respectively in the open state, and the first automatic switch valve 41, the second automatic switch valve 42, the third automatic switch valve 43, the seventh automatic switch valve 47, the eighth automatic switch valve 48, the ninth automatic switch valve 49 and the tenth automatic switch valve 410 are respectively in the closed state, the circulating water pump 23 is started, and the refrigerating machine 33 and the cold water pump 32 are stopped. The system only uses the circulating water subsystem 2 and does not use the cooling water subsystem 3.

[0051] In mode one, the circulating water of the circulating water subsystem 2 flows from the water outlet end of the cooling tower 21, passes through the collecting tank 22, the circulating water pump 23 and the heat exchange load 1 in sequence and then returns to the water return end of the cooling tower 21. Alternatively, the circulating water flows through the water inlet pipeline 24, the heat exchange load 1 and the water return pipeline 25 in sequence and then returns to the water return end of the cooling tower 21. The circulating water of the circulating water subsystem 2 exchanges heat with the heat exchange load 1 to reduce the temperature.

[0052] Step two, when the cooling set temperature of heat exchange load 1 < ambient wet-bulb temperature detected by ambient wet-bulb temperature transmitter 26 < 3-6℃ higher than the cooling set temperature of heat exchange load 1, and the detection cumulative duration exceeds 0.5-2.5h, the system automatically switches to cooling tower 21 and refrigerating machine 33 series cooling water preparation mode-mode two (a). As shown in Figure 4 , at this time, second automatic switch valve 4, third automatic switch valve 43, seventh automatic switch valve 47, ninth automatic switch valve 49 and tenth automatic switch valve 410 are respectively in the open state, and fifth automatic switch valve 45 and sixth automatic switch valve 46 are respectively in the closed state. Start cold water pump 32, and start the compressor of refrigerating machine 33.

[0053] In mode two (a), the circulating water of circulating water subsystem 2 flows from the outlet end of cooling tower 21, through water collecting tank 22, circulating water pump 23, cold water pump 32, evaporator 38, and is cooled into cooling water by refrigerating machine 33, and the cooling water flows through heat exchange load 1 to be cooled, and then flows through condenser 37 and returns to the return water end of cooling tower 21. Alternatively, the circulating water flows through water inlet pipeline 24, third pipeline 6, cold water outlet pipeline 34, evaporator 38, cooling water pipeline 35, heat exchange load 1, intermediate connection pipeline 7, first pipeline 4, condenser 37, second pipeline 5, and return water pipeline 25, and then returns to the return water end of cooling tower 21. The heat exchange and cooling of heat exchange load 1 is mainly realized by refrigerating machine 33. The circulating water of circulating water subsystem 2 is in series with chilled water and cold water of cooling water subsystem 3, which is equivalent to that the circulating water of circulating water subsystem 2 is in series in each pipeline in mode two (a).

[0054] Step three, when the ambient wet-bulb temperature detected by ambient wet-bulb temperature transmitter 26 ≥ 3-6℃ higher than the cooling set temperature of heat exchange load 1 during the operation of mode two (a), and the detection cumulative duration exceeds 0.5-2.5h, switch to cooling tower 21 and refrigerating machine 33 parallel cooling water preparation mode-mode three. As shown in Figure 5 , at this time, first automatic switch valve 41, fourth automatic switch valve 44 and eighth automatic switch valve 48 are switched to the open state, ninth automatic switch valve 49 and tenth automatic switch valve 410 are switched to the closed state, and the states of other automatic switch valves remain unchanged. First automatic switch valve 41, second automatic switch valve 42, third automatic switch valve 43, fourth automatic switch valve 44, seventh automatic switch valve 47 and eighth automatic switch valve 48 are respectively in the open state, and fifth automatic switch valve 45, ninth automatic switch valve 49 and tenth automatic switch valve 410 are respectively in the closed state. Cold water pump 32 and the compressor of refrigerating machine 33 are still in the running state.

[0055] In mode three, the circulating water of the circulating water subsystem 2 flows from the outlet of the cooling tower 21, through the water collecting tank 22, the circulating water pump 23, and the condenser 37 in sequence, and is heated to hot water, and the hot water flows back to the inlet of the cooling tower 21. The cold water of the cold water subsystem 3 flows from the outlet of the cold water tank 31, through the cold water pump 32 and the evaporator 38 in sequence, and is cooled to cooling water by the refrigerating machine 33, and the cooling water flows from the outlet of the evaporator 38, through the heat exchange load 1, and back to the inlet of the cold water tank 31. Alternatively, the circulating water flows through the water inlet pipeline 24, the first pipeline 4, the condenser 37, the second pipeline 5, and the water return pipeline 25 in sequence, and flows back to the inlet of the cooling tower 21. The cold water flows through the cold water outlet pipeline 34, the evaporator 38, the cooling water pipeline 35, the heat exchange load 1, and the cold water return pipeline 36 in sequence, and flows back to the inlet of the cold water tank 31. The circulating water and the cold water are operated independently in different subsystems. The circulating water of the circulating water subsystem 2 is further cooled to cooling water by the refrigerating machine 33. The cooling water is used to cool the heat exchange load 1.

[0056] Step four, when the cooling set temperature of the heat exchange load 1 is lower than the ambient wet-bulb temperature detected by the ambient wet-bulb temperature transmitter 26, which is higher than the cooling set temperature of the heat exchange load 1 by 3-6°C, and the detection time exceeds 0.5-2.5h during the operation in mode three, the operation is switched to mode two (a), as shown in FIG. 4B. At this time, the ninth automatic on-off valve 49 and the tenth automatic on-off valve 410 are switched to the open state, the first automatic on-off valve 41, the fourth automatic on-off valve 44, and the eighth automatic on-off valve 48 are switched to the closed state, and the states of the other automatic on-off valves remain unchanged. The cold water pump 32 and the compressor of the refrigerating machine 33 remain in the running state. Figure 4

[0057] Step five, when the ambient wet-bulb temperature detected by the ambient wet-bulb temperature transmitter 26 is less than or equal to the cooling set temperature of the heat exchange load 1 during the operation in mode two (a), the operation is switched to mode two (b), as shown in FIG. 4C. The difference between this mode and mode two (a) is that the compressor of the refrigerating machine 33 stops running, and the other aspects are the same as mode two (a). Figure 4

[0058] Step six, when the ambient wet-bulb temperature detected by the ambient wet-bulb temperature transmitter 26 is less than or equal to the cooling set temperature of the heat exchange load 1, and the detection time exceeds 0.5-2.5h during the operation in mode two (b), the operation is switched to mode one, as shown in FIG. 4D. Figure 3 ​​As shown in the figure. At this time, the cold water pump 32, the third automatic switch valve 43 and the sixth automatic switch valve 46 are stopped and switched to the closed state respectively. The second automatic switch valve 42, the third automatic switch valve 43, the seventh automatic switch valve 47, the ninth automatic switch valve 49 and the tenth automatic switch valve 410 are switched to the closed state respectively, the cooling tower 21 is in the cooling water preparation mode alone, and the refrigerating machine 33 is stopped.

[0059] The effect of the cooling tower and refrigerating machine combined cooling system and the control method thereof of the present application will be further illustrated in combination with specific examples.

[0060] Example 1

[0061] The first embodiment of the control method of the cooling tower and refrigerating machine combined cooling system of the present application, which takes the erythritol fermentation process as the heat exchange load 1. Since the erythritol fermentation process generates heat, cooling water is needed to take away the generated heat, and the cooling set temperature is 20℃, so that the fermentation temperature is stably controlled at 30℃. The control method of the cooling tower and refrigerating machine combined cooling system of Example 1 comprises the following steps:

[0062] When the winter ambient wet-bulb temperature is low, the ambient wet-bulb temperature detected by the ambient wet-bulb temperature transmitter 26 is below 20℃, and the running mode one is adopted, as shown in the figure, i.e. the cooling tower 21 is in the cooling water preparation mode alone, and the refrigerating machine 33 is stopped. The fifth automatic switch valve 45 and the sixth automatic switch valve 46 are opened, and the first automatic switch valve 41, the second automatic switch valve 42, the third automatic switch valve 43, the seventh automatic switch valve 47, the eighth automatic switch valve 48, the ninth automatic switch valve 49 and the tenth automatic switch valve 410 are closed. The circulating water pump 23 is started, and the refrigerating machine 33 and the cold water pump 32 are stopped. Figure 3 Because the control signal interlocking is set, when the first temperature sensor 27 shows that the detected ambient wet-bulb temperature is 5℃ or more, the fan of the cooling tower 21 is started and runs, the first pressure transmitter 210 is set at 0.3MPa and is interlocked with the circulating water pump 23, and by adjusting the cooling water amount of the circulating water pump 23, the temperature of the outlet end of the heat exchange load 1 of the erythritol fermentation process is stably controlled at 30℃.

[0063] Example 2

[0064] The second embodiment of the control method of the cooling tower and refrigerating machine combined cooling system of the present application, which has the same setting of the heat exchange load 1 as that of Example 1. The control method of the cooling tower and refrigerating machine combined cooling system of Example 2 comprises the following steps:

[0065]

[0066] ​When 20℃ < the ambient wet-bulb temperature detected by the ambient wet-bulb temperature transmitter 26 < 24℃, and the cumulative detection time > 1.5h, the system switches from operating mode one to operating mode two (a). For example... Figure 4 As shown, the second automatic switch valve 4, the third automatic switch valve 43, the seventh automatic switch valve 47, the ninth automatic switch valve 49 and the tenth automatic switch valve 410 are opened in sequence, and the fifth automatic switch valve 45 and the sixth automatic switch valve 46 are closed in sequence. Then the chilled water pump 32 is started, and the compressor of the chiller 33 is started, that is, the cooling tower 21 and the chiller 33 are connected in series to prepare cooling water (the compressor of the chiller 33 is running).

[0067] When the first temperature sensor 27 displays a value 4°C higher than the wet-bulb temperature of the detection environment, the fan of the cooling tower 21 starts running, the first pressure transmitter 210 is set to 0.3MPa and interlocked with the circulating water pump 23, the second temperature sensor 39 is set to 20°C and interlocked with the compressor of the refrigeration unit 33, and by adjusting the cooling water volume of the circulating water pump 23, the temperature at the outlet of the heat exchange load 1 of the erythritol fermentation process is stably controlled at 30°C.

[0068] Example 3

[0069] The third embodiment of the control method for the combined cooling tower and chiller cooling system of the present invention has the same heat exchange load 1 setting as in embodiment 1. The control method for the combined cooling tower and chiller cooling system in embodiment 3 includes the following steps:

[0070] If the ambient wet-bulb temperature is ≤20℃ during operation in Mode 2 (a), the system will switch to Mode 2 (b). Figure 4 As shown, the compressor of the refrigeration unit 33 stops running, while the opening and closing of other automatic switching valves remain unchanged. After the compressor stops running, the interlock with the second temperature sensor 39 is automatically disconnected. By adjusting the cooling water flow rate of the circulating water pump 23, the temperature at the outlet of the heat exchange load 1 in the erythritol fermentation process is stably controlled at 30°C.

[0071] Example 4

[0072] The fourth embodiment of the control method for the combined cooling tower and chiller cooling system of the present invention has the same heat exchange load 1 setting as in embodiment 1. The control method for the combined cooling tower and chiller cooling system in embodiment 4 includes the following steps:

[0073] When the ambient wet-bulb temperature is ≥24℃ and the cumulative detection time exceeds 1.5h during operation in Mode 2(a), the system switches to Mode 3. For example... Figure 5As shown, the cooling tower 21 and the refrigerator 33 are operated independently, and the refrigerator 33 independently prepares cooling water mode. The first automatic switch valve 41, the fourth automatic switch valve 44 and the eighth automatic switch valve 48 are opened in turn, and the ninth automatic switch valve 49 and the tenth automatic switch valve 410 are closed. When the first temperature sensor 27 shows that the detected ambient wet-bulb temperature is higher than 3℃, the fan of the cooling tower 21 is started to operate, the first pressure transmitter 210 is set to 0.3MPa and is interlocked with the circulating water pump 23, the set value of the second temperature sensor 39 is 20℃ and is interlocked with the compressor of the refrigerator 33 for control, and the temperature of the outlet end of the heat exchange load 1 of the erythritol fermentation process is stably controlled at 30℃ by adjusting the cooling water amount of the circulating water pump 23.

[0074] In a 30,000-ton-per-year erythritol production line, the cooling tower and the refrigerator combined cooling system of the present application is configured, the cooling tower 21 is configured to have a flow of 3000m³ / h, an inlet water temperature of 36℃ / 31℃, two refrigerators 33 are configured in the system, wherein the flow is 1200m³ / h, the refrigerating capacity is 7000kw, and the inlet and outlet water temperatures are 25℃ / 20℃. Compared with the traditional independent operation mode of the cooling tower 21 and the refrigerator 33, the system of the present application can save 1.4 million degrees of electric energy per year, and according to the calculation of 0.8 yuan / degree, 1.12 million yuan of electricity fee can be saved per year.

[0075] The above only describes the preferred embodiments of the present application, and is not used to limit the present application, and any modification, equivalent replacement and improvement within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A control method for a combined cooling tower and chiller cooling system, wherein a fan is installed on the cooling tower, and a compressor, a condenser, and an evaporator are respectively installed in the chiller, characterized in that, The combined cooling tower and chiller cooling system includes a heat exchange load, a circulating water subsystem, and a cooling water subsystem. The heat exchange load is equipped with an inlet and an outlet. The circulating water subsystem includes a cooling tower, a collection tank, a circulating water pump, an inlet pipe, and a return pipe. The cooling water subsystem includes a cold water tank, a cold water pump, a chiller, a cold water outlet pipe, a cooling water pipe, and a cold water return pipe. The inlet pipe connects sequentially to the outlet of the cooling tower, the collection tank, the circulating water pump, and the inlet of the heat exchange load. The return pipe connects the outlet of the heat exchange load to the return of the cooling tower. The cold water outlet pipe connects sequentially to the outlet of the cold water tank, the cold water pump, and the inlet of the chiller's evaporator. The cooling water pipeline connects the evaporator outlet to the heat exchange load inlet, and the chilled water return pipeline connects the heat exchange load outlet to the chilled water tank inlet. The inlet pipeline and cooling water pipeline are connected in parallel, as are the return pipeline and chilled water return pipeline. The condenser inlet is connected to the inlet pipeline via a first pipeline, and the condenser outlet is connected to the cooling tower return pipeline via a second pipeline. An ambient wet-bulb temperature transmitter is installed around the cooling tower. A first temperature sensor is installed on the inlet pipeline near the water collection tank. A first automatic on / off valve and a second automatic on / off valve are installed on the first pipeline, with the second automatic on / off valve located near the condenser inlet. A second automatic on / off valve is installed on the chilled water outlet pipeline. A third and a fourth automatic switching valve are located. The third automatic switching valve is near the inlet of the evaporator, and the fourth automatic switching valve is near the outlet of the chilled water tank. The chilled water pump is positioned between the third and fourth automatic switching valves. A fifth automatic switching valve is installed on the inlet pipe near the heat exchange load, and a sixth automatic switching valve is installed on the return pipe near the outlet of the heat exchange load. A second temperature sensor and a seventh automatic switching valve are installed on the cooling water pipes. A first flow meter is installed on the inlet pipe of the heat exchange load, and a third temperature sensor is installed on the outlet pipe of the heat exchange load. An eighth automatic switching valve is installed on the chilled water return pipe. Additionally, a third automatic switching valve is installed on the inlet pipe. A third pipeline is connected to the cold water outlet pipeline. One end of the third pipeline is connected to the cold water outlet pipeline between the fourth automatic switch valve and the cold water pump. A ninth automatic switch valve is installed on the third pipeline. An intermediate connecting pipeline is installed between the first pipeline and the cold water return pipeline. One end of the intermediate connecting pipeline is connected to the first pipeline between the first automatic switch valve and the second automatic switch valve. A tenth automatic switch valve is installed on the intermediate connecting pipeline. The control signals of the ambient wet-bulb temperature transmitter and the first temperature sensor are configured to be interlocked with the fan. The control signals of the first temperature sensor and the second temperature sensor are configured to be interlocked with the refrigeration unit. The control method includes the following steps: Step 1: When the ambient wet-bulb temperature detected by the ambient wet-bulb temperature transmitter is less than or equal to the cooling set temperature of the heat exchange load, and the cumulative detection time exceeds 0.5~2.5h, the system adopts the cooling tower-only cooling water preparation mode—Mode 1. At this time, the fifth and sixth automatic switching valves are in the open state, while the first, second, third, seventh, eighth, ninth, and tenth automatic switching valves are in the closed state. The circulating water pump is started, while the chiller and the cold water pump stop running. Step 2: When the cooling set temperature of the heat exchange load is less than the ambient wet-bulb temperature detected by the ambient wet-bulb temperature transmitter, and is 3°C to 6°C higher than the cooling set temperature of the heat exchange load, and the cumulative detection time exceeds 0.5 to 2.5 hours, the system automatically switches to the cooling tower and chiller series cooling water preparation mode—Mode 2 (a). At this time, the second, third, seventh, ninth, and tenth automatic switching valves are in the open state, and the fifth and sixth automatic switching valves are in the closed state. The chilled water pump is started, and the chiller compressor is started. Step 3: When the ambient wet-bulb temperature detected by the ambient wet-bulb temperature transmitter is ≥ 3℃~6℃ higher than the cooling set temperature of the heat exchange load during the operation of Mode 2(a), and the cumulative detection time exceeds 0.5~2.5h, switch to the parallel cooling tower and chiller cooling water preparation mode—Mode 3. At this time, the first, fourth, and eighth automatic switching valves are switched to the open state, the ninth and tenth automatic switching valves are switched to the closed state, and the states of other automatic switching valves remain unchanged; the chilled water pump and the chiller compressor are still running. Step 4: When the cooling set temperature of the heat exchange load is less than the ambient wet bulb temperature detected by the ambient wet bulb temperature transmitter during operation in mode 3, and the cumulative detection time exceeds 0.5 to 2.5 hours, switch to mode 2 (a) operation. Step 5: When the ambient wet-bulb temperature detected by the ambient wet-bulb temperature transmitter is less than or equal to the cooling set temperature of the heat exchange load during operation in Mode 2 (a), switch to Mode 2 (b) operation. The only difference between this mode and Mode 2 (a) is that the compressor of the refrigeration unit stops running. Everything else is the same as Mode 2 (a). Step 6: When the ambient wet-bulb temperature detected by the ambient wet-bulb temperature transmitter is less than or equal to the cooling set temperature of the heat exchange load during operation in Mode 2 (b), and the cumulative detection time exceeds 0.5~2.5h, switch to Mode 1 operation.

2. The control method for the combined cooling tower and chiller cooling system as described in claim 1, characterized in that, In the system, one or more cooling towers, circulating water pumps, chilled water pumps, and chillers are provided as needed.

3. The control method for the combined cooling tower and chiller cooling system as described in claim 2, characterized in that, The system includes four cooling towers, two circulating water pumps, two chilled water pumps, and one refrigeration unit.

4. The control method for the combined cooling tower and chiller cooling system as described in claim 3, characterized in that, A first pressure transmitter is also installed on the water inlet pipeline, and the control signal of the first pressure transmitter is configured to be interlocked with the control signal of the circulating water pump.

5. The control method for the combined cooling tower and chiller cooling system as described in claim 3, characterized in that, A second pressure transmitter is also installed on the cold water outlet pipeline, and the control signal of the second pressure transmitter is configured to be interlocked with the control signal of the cold water pump.

6. The control method for the combined cooling tower and chiller cooling system as described in claim 1, characterized in that, The system also includes a circulating water sewage discharge subsystem, which includes a sewage discharge pipeline and a first flow meter and a regulating valve installed on the sewage discharge pipeline. It also includes an online turbidity meter. The sewage discharge pipeline is connected to the inlet pipeline. The online turbidity meter is installed on the inlet pipeline. The control signals of the online turbidity meter and the first flow meter are respectively configured to be interlocked with the regulating valve.

7. The control method for the combined cooling tower and chiller cooling system as described in claim 1, characterized in that, A circulating water replenishment subsystem is also provided on the water collection tank. The circulating water replenishment subsystem includes a circulating water replenishment pipeline and a replenishment flow meter installed on the circulating water replenishment pipeline. It also includes a float valve installed on the water collection tank. The circulating water replenishment pipeline is connected to the water collection tank.

8. The control method for the combined cooling tower and chiller cooling system as described in claim 1, characterized in that, A cooling water replenishment subsystem is also provided on the cold water tank. The cooling water replenishment subsystem includes a cold water replenishment pipeline and an automatic control valve installed on the cold water replenishment pipeline. It also includes a level transmitter installed on the cold water tank. The cold water replenishment pipeline is connected to the cold water tank. A fourth temperature sensor is installed on the cold water tank.

9. The control method for the combined cooling tower and chiller cooling system as described in claim 1, characterized in that, A second flow meter is installed on the pipeline at the inlet end of the heat exchange load.

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