Refrigeration system

Abstract

The present application relates to the technical field of refrigeration. Provided is a refrigeration system, the refrigeration system comprising a first standby main line and at least two refrigeration units, wherein each refrigeration unit comprises a heat exchange assembly, adjacent two stages of heat exchange assemblies are connected by means of a first line, and a branch where each heat exchange assembly is located is connected in parallel with the first standby main line; at least two first bypass branches are connected between the first standby main line and each first line, the at least two first bypass branches are connected in parallel, and each first bypass branch is provided with at least one first on-off valve; and the section of each first line located between a pair of adjacent first bypass branches is provided with at least one second on-off valve. The refrigeration system can implement online isolation and maintenance of a faulty refrigeration unit.

Description

A refrigeration system

[0001] Cross Reference to Related Applications

[0002] The present application claims priority to the Chinese patent application No. 202422200083.0, filed on September 9, 2024, and entitled "A refrigeration system", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0003] The present application relates to the technical field of refrigeration, and in particular to a refrigeration system. BACKGROUND

[0004] In the related art, multiple refrigeration devices are connected in series, and the temperature difference between the supply water and the return water of the refrigeration system is increased through the step-by-step temperature reduction of the refrigeration devices at different levels, so that the refrigeration system can achieve better refrigeration effect. Although this system can achieve a large temperature difference between the supply water and the return water of the refrigeration system, since the refrigeration devices at different levels are connected in series, if any one refrigeration device fails, the entire refrigeration system cannot operate normally. SUMMARY

[0005] The embodiments of the present application provide a refrigeration system, which can realize online isolation and maintenance of a refrigeration unit when the refrigeration unit fails.

[0006] The application provides a refrigeration system comprising a first standby main pipeline and at least two refrigeration units connected in series, wherein each refrigeration unit comprises a heat exchange assembly, two adjacent heat exchange assemblies are connected through a first pipeline, a water inlet of a first-stage heat exchange assembly is connected with a water inlet of the first standby main pipeline through a water inlet pipeline, and a water outlet of a last-stage heat exchange assembly is connected with a water outlet of the first standby main pipeline through a water outlet pipeline; at least two first bypass branches are connected between the first standby main pipeline and each first pipeline, the at least two first bypass branches are connected in parallel, and at least one first on-off valve is arranged on each first bypass branch; at least one second on-off valve is arranged on a pipeline section between each first pipeline and a pair of adjacent first bypass branches; or at least one first bypass branch is connected between the first standby main pipeline and each first pipeline, at least one first on-off valve is arranged on each first bypass branch, and at least one second on-off valve is arranged on each first pipeline and on both sides of one first bypass branch; a second on-off valve is also arranged on the water inlet pipeline and the water outlet pipeline, and a third on-off valve is arranged on a pipeline section of the first standby main pipeline, which is upstream of the first-stage first bypass branch and downstream of the last-stage first bypass branch. When the scheme is adopted, water discharged from a water outlet of a first heat exchange device can be gradually cooled after passing through each heat exchange assembly, and the cooled water can enter a water inlet of a second heat exchange device for heat exchange, so that a large temperature difference between water supply and return water of the refrigeration system can be realized. When the scheme is adopted, the refrigeration unit with a fault can be isolated online, so that the staff can maintain the fault under the condition that the refrigeration system normally operates.

[0007] In a possible embodiment, two first bypass branches are connected between the first standby main pipeline and each first pipeline; three second on-off valves are arranged on each first pipeline, two of the three second on-off valves are arranged between the corresponding two first bypass branches, and the remaining one of the three second on-off valves is arranged between the first bypass branch and the heat exchange assembly of the previous stage; and a third on-off valve is arranged on a pipeline section of the first standby main pipeline between the two adjacent first bypass branches. When the scheme is adopted, the isolation and online maintenance of the faulty second on-off valve can be realized when the second on-off valve fails.

[0008] In a possible embodiment, two first on-off valves are arranged on each first bypass branch. When the scheme is adopted, the isolation and online maintenance of the faulty first on-off valve and third on-off valve can be realized when the first on-off valve and the third on-off valve fail.

[0009] In a possible embodiment, the refrigeration system comprises a surface air cooler, the water inlet of the first standby main pipeline and the water inlet of the first-stage heat exchange assembly are connected with a water outlet of the surface air cooler, and the water outlet of the first standby main pipeline and the water outlet of the last-stage heat exchange assembly are connected with a water inlet of the surface air cooler.

[0010] In a possible embodiment, the heat exchange component is an evaporator, or the refrigeration unit is a compression refrigeration unit, the compression refrigeration unit comprises an evaporator and an air-cooled condenser, and the heat exchange component is the evaporator.

[0011] In a possible embodiment, the at least two adjacent refrigeration units are compression refrigeration units, the compression refrigeration units comprise evaporators and water-cooled condensers, and the heat exchange component is the evaporator; the two adjacent water-cooled condensers are connected through a second pipeline, the water inlet of the first water-cooled condenser is connected with a third pipeline, and the water outlet of the last water-cooled condenser is connected with a fourth pipeline; the refrigeration system further comprises a second standby main pipeline, and the branch pipelines in which the water-cooled condensers are located are connected in parallel with the second standby main pipeline; at least two second bypass branches are connected between the second standby main pipeline and each second pipeline, the at least two second bypass branches are connected in parallel, at least one fourth on-off valve is arranged on each second bypass branch, and at least one fifth on-off valve is arranged on the pipeline section between each second pipeline and a pair of adjacent second bypass branches; or at least one second bypass branch is connected between the second standby main pipeline and each second pipeline, at least one fourth on-off valve is arranged on each second bypass branch, and at least one fifth on-off valve is arranged on each second pipeline and on both sides of one second bypass branch; the third pipeline and the fourth pipeline are also provided with fifth on-off valves, and a sixth on-off valve is arranged on the pipeline section of the second standby main pipeline, which is located upstream of the first second bypass branch and downstream of the last second bypass branch. When the at least two adjacent refrigeration units are compression refrigeration units with water-cooled condensers, the compression refrigeration unit with the fault can be isolated online, so that the staff can maintain the fault under the condition that the refrigeration system is normally running.

[0012] In a possible embodiment, two second bypass branches are connected between the second standby main pipeline and each second pipeline; three fifth on-off valves are arranged on each second pipeline, two of the three fifth on-off valves are located between the corresponding two second bypass branches, and the remaining one of the three fifth on-off valves is located between the second bypass branch and the previous stage water-cooled condenser; and a sixth on-off valve is arranged on the pipeline section of the second standby main pipeline, which is located between the two adjacent second bypass branches. When the fifth on-off valve fails, the isolation and online maintenance of the faulty fourth on-off valve can be realized.

[0013] In a possible embodiment, two fourth on-off valves are arranged on each second bypass branch. When the fourth on-off valve and the sixth on-off valve fail, the isolation and online maintenance of the faulty fourth on-off valve and the sixth on-off valve can also be realized.

[0014] In a possible embodiment, the refrigeration system comprises a second heat exchanger, the second heat exchanger comprises a first flow channel and a second flow channel which are isolated from each other and are in heat conduction connection, the water inlet of the first standby main pipeline and the water inlet of the first-stage heat exchange assembly are connected with the water outlet of the first flow channel of the second heat exchanger, and the water inlet of the second standby main pipeline and the water inlet of the first-stage water-cooled condenser are connected with the water outlet of the second flow channel of the second heat exchanger.

[0015] In a possible embodiment, the refrigeration system comprises a cooling tower, the water outlet of the second standby main pipeline and the water outlet of the last-stage water-cooled condenser are connected with the water inlet of the cooling tower, and the water outlet of the cooling tower is connected with the water inlet of the second flow channel of the second heat exchanger.

[0016] In a possible embodiment, the refrigeration system comprises a surface cooler, the water inlet of the first flow channel of the second heat exchanger is connected with the water outlet of the surface cooler, and the water outlet of the first standby main pipeline and the water outlet of the last-stage heat exchange assembly are connected with the water inlet of the surface cooler. BRIEF DESCRIPTION OF DRAWINGS

[0017] FIG. 1 is a structural schematic diagram of a refrigeration system;

[0018] FIG. 2a is a structural schematic diagram of a refrigeration system provided by the present application;

[0019] FIG. 2b is a structural schematic diagram of another refrigeration system provided by the present application;

[0020] FIG. 3 is a structural schematic diagram of another refrigeration system provided by the present application;

[0021] FIG. 4a is a schematic diagram of the opening and closing of each on-off valve when H21 of the refrigeration system shown in FIG. 2a fails;

[0022] FIG. 4b is a schematic diagram of the opening and closing of each on-off valve when M21 of the refrigeration system shown in FIG. 2a fails;

[0023] FIG. 4c is a schematic diagram of the opening and closing of each on-off valve when T21 of the refrigeration system shown in FIG. 2a fails;

[0024] FIG. 5a is a schematic diagram of the opening and closing of each on-off valve when H21 of the refrigeration system shown in FIG. 3 fails;

[0025] FIG. 5b is a schematic diagram of the opening and closing of each on-off valve when M21 of the refrigeration system shown in FIG. 3 fails;

[0026] FIG. 5c is a schematic diagram of the opening and closing of each on-off valve when T21 of the refrigeration system shown in FIG. 3 fails;

[0027] FIG. 6a is a schematic diagram of the opening and closing of each on-off valve when H31 located on the first first pipeline downstream of the first-stage heat exchange assembly fails;

[0028] Fig. 6b is a schematic diagram of the opening and closing of each on-off valve when M31 on the first first pipe downstream of the first stage heat exchange assembly fails;

[0029] Fig. 6c is a schematic diagram of the opening and closing of each on-off valve when T31 on the first first pipe downstream of the first stage heat exchange assembly fails;

[0030] Fig. 7a is a schematic diagram of the opening and closing of each on-off valve when H61 on the second first bypass branch 6 fails in the flow direction of water in the first pipe 3;

[0031] Fig. 7b is a schematic diagram of the opening and closing of each on-off valve when H61 on the second first bypass branch fails in the flow direction of water in the first pipe;

[0032] Fig. 7c is a schematic diagram of the opening and closing of each on-off valve when M61 on the first first bypass branch fails in the flow direction of water in the first pipe;

[0033] Fig. 8 is a schematic diagram of the opening and closing of each on-off valve when the second third on-off valve fails in the flow direction of water in the first standby main pipe;

[0034] Fig. 9a is a schematic diagram of the opening and closing of each on-off valve when the refrigeration unit in which the first stage evaporator and the last stage condenser are located fails;

[0035] Fig. 9b is a schematic diagram of the opening and closing of each on-off valve when the refrigeration unit in which the second stage evaporator and the second stage condenser are located fails;

[0036] Fig. 9c is a schematic diagram of the opening and closing of each on-off valve when the refrigeration unit in which the last stage evaporator and the first stage condenser are located fails;

[0037] Fig. 10a is a schematic diagram of the opening and closing of each on-off valve when the refrigeration unit in which the first stage evaporator and the last stage condenser are located fails;

[0038] Fig. 10b is a schematic diagram of the opening and closing of each on-off valve when the refrigeration unit in which the second stage evaporator and the second stage condenser are located fails;

[0039] Fig. 10c is a schematic diagram of the opening and closing of each on-off valve when the refrigeration unit in which the last stage evaporator and the first stage condenser are located fails;

[0040] Fig. 11a is a schematic diagram of the opening and closing of each on-off valve when H81 on the first second pipe downstream of the first stage water-cooled condenser fails;

[0041] Fig. 11b is a schematic diagram of the opening and closing of each on-off valve when M81 on the first second pipeline downstream of the first water-cooled condenser fails;

[0042] Fig. 11c is a schematic diagram of the opening and closing of each on-off valve when T81 on the first second pipeline downstream of the first water-cooled condenser fails;

[0043] Fig. 12a is a schematic diagram of the opening and closing of each on-off valve when H301 on the second second bypass branch in the flow direction of water in the second pipeline fails;

[0044] Fig. 12b is a schematic diagram of the opening and closing of each on-off valve when H301 on the second second bypass branch in the flow direction of water in the second pipeline fails;

[0045] Fig. 12c is a schematic diagram of the opening and closing of each on-off valve when M301 on the first second bypass branch 30 in the flow direction of water in the second pipeline 8 fails;

[0046] Fig. 13 is a schematic diagram of the opening and closing of each on-off valve when the second sixth on-off valve in the flow direction of water in the second standby main pipeline fails;

[0047] Fig. 14a is a schematic diagram of the structure of a refrigeration system;

[0048] Fig. 14b is a schematic diagram of the opening and closing of each on-off valve when a certain refrigeration unit fails;

[0049] Fig. 15 is a schematic diagram of the structure of another refrigeration system provided by the present application.

[0050] Reference signs: 1 - first standby main pipeline; 11 - third on-off valve; 2 - refrigeration unit; 21 - heat exchange component; 22 - evaporator; 23 - air-cooled condenser; 24 - water-cooled condenser; 25 - expansion valve; 26 - compressor; 3 - first pipeline; 31 - second on-off valve; 4 - water inlet pipeline; 5 - water outlet pipeline; 6 - first bypass branch; 61 - first on-off valve; 7, 200' - cooling tower; 8 - second pipeline; 81 - fifth on-off valve; 9 - second standby main pipeline; 91 - sixth on-off valve; 10 - third pipeline; 20 - fourth pipeline; 30 - second bypass branch; 301 - fourth on-off valve; 40 - second heat exchanger; 50 - cooling tower; 100' - compression refrigeration unit; 110' - evaporator; 120' - compressor; 130' - condenser; 140' - expansion valve; 300' - circulating pump; 400 - data center. DETAILED DESCRIPTION

[0051] Refrigeration systems are widely used in data centers and industrial plants and many other fields. The structure and principle of a refrigeration system are briefly introduced below. FIG. 1 is a structural schematic diagram of a refrigeration system. As shown in FIG. 1, the refrigeration system includes multiple-stage compression refrigeration units 100' connected in series. Specifically, each compression refrigeration unit includes an evaporator 110', a compressor 120', a condenser 130', and an expansion valve 140'. The evaporator 110' includes a refrigerant flow channel and a cooling water flow channel, the refrigerant flow channel and the cooling water flow channel are isolated from each other, and heat can be transferred between the refrigerant flow channel and the cooling water flow channel. In the same compression refrigeration unit 100', the outlet of the refrigerant flow channel of the evaporator 110' is connected to the inlet of the flow channel of the compressor 120', the outlet of the flow channel of the compressor 120' is connected to the refrigerant inlet of the condenser 130', the refrigerant outlet of the condenser 130' is connected to the fluid inlet of the expansion valve 140', and the fluid outlet of the expansion valve 140' is connected to the inlet of the refrigerant flow channel of the evaporator 110'. Between the compression refrigeration units 100', the water inlet of the chilled water flow channel of the evaporator 110' of the first-stage compression refrigeration unit is connected to the water outlet of the cooling panel 200', the water outlet of the chilled water flow channel of the evaporator 110' of the previous-stage compression refrigeration unit is connected to the water inlet of the chilled water flow channel of the evaporator 110' of the next-stage compression refrigeration unit, and the water outlet of the chilled water flow channel of the evaporator 110' of the last-stage compression refrigeration unit is connected to the water supply port of the cooling panel 200'. In this scheme, if any single point of any compression refrigeration unit fails, the entire refrigeration system cannot operate normally.

[0052] Based on this, the embodiment of the present application provides a refrigeration system, which can realize online isolation and maintenance of a refrigeration unit and ensure normal operation of the refrigeration system when the refrigeration unit fails. In order to make the purpose, technical scheme and advantages of the present application more clear, the present application will be further described in detail below with reference to the drawings.

[0053] The terms used in the following embodiments are only for the purpose of describing specific embodiments and are not intended to be limiting on the present application. As used in the specification and the appended claims of the present application, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0054] Reference in the specification to "one embodiment" or "some embodiments" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. The appearances of the phrase "in one embodiment" or "in some embodiments" in various places in the specification are not necessarily all referring to the same embodiment, although it can. The terms "including," "comprising," "having" and variations thereof are meant to encompass the items listed thereafter and equivalents thereof as well as additional items.

[0055] Fig. 2a is a structural schematic diagram of a refrigeration system provided by the present application. As shown in Fig. 2a, the refrigeration system comprises a first standby main pipeline 1 and at least two refrigeration units 2, and each refrigeration unit 2 is connected in series. Each refrigeration unit 2 comprises a heat exchange assembly 21, two adjacent heat exchange assemblies 21 are connected through a first pipeline 3, and the water inlet of the first heat exchange assembly 21 is connected with the water inlet of the first standby main pipeline 1 through a water inlet pipeline 4, and the water outlet of the last heat exchange assembly 21 is connected with the water outlet of the first standby main pipeline 1 through a water outlet pipeline 5. The water inlet of the first standby main pipeline 1 and the water inlet of the water inlet pipeline 4 are connected with the water outlet of the same first heat exchange device A, and the water outlet of the first standby main pipeline 1 and the water outlet of the water outlet pipeline 5 are connected with the water inlet of the same second heat exchange device B. In a specific implementation, the water inlet of the first standby main pipeline 1 and the water inlet of the water inlet pipeline 4 can be directly connected with the water outlet of the first heat exchange device A (as shown in Fig. 2a), or indirectly connected with the water outlet of the first heat exchange device A through other components. The water outlet of the first standby main pipeline 1 and the water outlet of the water outlet pipeline 5 can be indirectly connected with the water inlet of the second heat exchange device B through a circulating pump 300' and the like. It is not difficult to understand that the first heat exchange device A, the heat exchange assembly 21 and the second heat exchange device B are in the same circulating loop. In this scheme, the water discharged from the water outlet of the first heat exchange device A can be gradually cooled after passing through each heat exchange assembly 21 in turn, and the cooled water can enter the water inlet of the second heat exchange device B for heat exchange, so that a large temperature difference of water supply and return can be realized in the refrigeration system.

[0056] It is worth mentioning that in some embodiments, the first heat exchange device A connected with the first-stage heat exchange assembly 21 and the second heat exchange device B connected with the last-stage heat exchange assembly 21 can be the same heat exchange device, for example, the same heat exchange device is a cooling coil 7 (not labeled in FIG. 2a), specifically, the cooling coil 7 can be a cooling coil 7 that realizes heat exchange between air and water. The water inlet of the first standby main pipeline 1 and the water inlet of the water inlet pipeline 4 are both connected with the water outlet of the cooling coil 7, and the water outlet of the first standby main pipeline 1 and the water outlet of the water outlet pipeline 5 are both connected with the water inlet of the cooling coil 7. In other embodiments, as shown in the refrigeration system in FIG. 2b, the first heat exchange device A of the first-stage heat exchange assembly 21 and the second heat exchange device B of the last-stage heat exchange assembly 21 can also be different heat exchange devices, for example, the first heat exchange device connected with the first-stage heat exchange assembly 21 is a heat exchanger C, and the second heat exchange device connected with the last-stage heat exchange assembly 21 is a cooling coil 7, and the water outlet of the cooling coil 7 is connected with the water inlet of the heat exchanger C. Next, please continue to refer to FIG. 2a and FIG. 2b, and specifically, the first standby main pipeline 1 is connected with at least two first bypass branches 6 between each first pipeline 3, the at least two first bypass branches 6 are connected in parallel between the first standby main pipeline 1 and the corresponding first pipeline 3, and at least one first on-off valve 61 is arranged on each first bypass branch 6. The pipe section of each first pipeline 3 between a pair of adjacent first bypass branches 6 is provided with at least one second on-off valve 31, and the water inlet pipeline 4 and the water outlet pipeline 5 are also provided with at least one second on-off valve 31. The pipe section of the first standby main pipeline 1 upstream of the first-stage first bypass branch 6 and downstream of the last-stage first bypass branch 6 is provided with a third on-off valve 11. Exemplarily, the refrigeration system includes three refrigeration units 2, each refrigeration unit 2 includes a heat exchange assembly 21, two first bypass branches 6 are connected between the first standby main pipeline 1 and each first pipeline 3, one first on-off valve 61 is arranged on each first bypass branch 6, one second on-off valve 31 is arranged on the water inlet pipeline 4, the water outlet pipeline 5, and the pipe section of each first pipeline 3 between a pair of adjacent first bypass branches 6, and one third on-off valve 11 is arranged on the pipe section of the first standby main pipeline 1 upstream of the first-stage first bypass branch 6 and downstream of the last-stage first bypass branch 6.

[0057] Obviously, the arrangement of the pipes and valves in the refrigeration system is not limited to the case shown in Figs. 2a and 2b. For example, the arrangement of the pipes and valves in the refrigeration system can also be as shown in Fig. 3. The difference between the refrigeration system shown in Fig. 3 and the refrigeration system shown in Fig. 2a is that in the refrigeration system shown in Fig. 3, at least one first bypass branch 6 is connected between the first standby main pipe 1 and each first pipe 3, at least one first on-off valve 61 is arranged on each first bypass branch 6, and at least one second on-off valve 31 is arranged on each first pipe 3 at both sides of the corresponding first bypass branch. In a specific implementation, as shown in Fig. 3, one first bypass branch 6 is connected between the first standby main pipe 1 and each first pipe 3, one first on-off valve 61 is arranged on each first bypass branch 6, and one second on-off valve 31 is arranged on each first pipe 3 at both sides of the corresponding first bypass branch 6.

[0058] In implementation, the heat exchange assembly 21 of each refrigeration unit 2 can have various forms. For example, the heat exchange assembly 21 can be a first heat exchanger; or the refrigeration unit 2 can be a compression refrigeration unit, which includes an evaporator 22 and an air-cooled condenser 23, and the evaporator 22 is the heat exchange assembly 21. It can be understood that the compression refrigeration unit also includes an expansion valve 25 and a compressor 26, and the specific working principle of the compression refrigeration unit can refer to the prior art, which will not be described here.

[0059] Based on the above, in implementation, the heat exchange assembly 21 of each refrigeration unit 2 in the refrigeration system can have various forms. For example, the heat exchange assembly 21 of each refrigeration unit 2 can be a first heat exchanger; or each refrigeration unit 2 can be a compression refrigeration unit using an air-cooled condenser 23, and the evaporator 22 is the heat exchange assembly 21; or the heat exchange assembly 21 in part of the refrigeration units 2 is a first heat exchanger, and the remaining refrigeration units 2 are compression refrigeration units using an air-cooled condenser 23, and the evaporator 22 is the heat exchange assembly 21. The isolation and maintenance when a fault occurs in a refrigeration unit 2 in the above three cases will be described below with reference to Figs. 4a to 5c. In each figure, the heat exchange assembly 21 in the dashed box represents a heat exchange assembly 21 that has a fault, the on-off valve that is straightly cut off represents a closed on-off valve, and the broken line in the shape of a broken line schematically shows the flow direction of a fluid in the refrigeration system. It should be noted that Figs. 4a to 5c only show the heat exchange assembly 21 of each refrigeration unit 2. For ease of understanding, in the following, the first-level heat exchange assembly 21 is denoted as H21, the second-level heat exchange assembly 21 is denoted as M21, and the third-level heat exchange assembly 21 is denoted as T21, wherein the first-level and the last-level heat exchange assemblies are relative to the flow direction of water in the first pipe. In the flow direction of water in the first pipe, the heat exchange assembly located at the most upstream is the first-level heat exchange assembly, and the heat exchange assembly located at the most downstream is the last-level heat exchange assembly.

[0060] Specifically, Fig. 4a is a schematic diagram of the opening and closing of each shutoff valve when the refrigeration system shown in Fig. 2a has a fault in H21. As shown in Fig. 4a, when H21 has a fault, the two second shutoff valves 31 adjacent to H21 are closed, the first shutoff valve 61 on the first bypass branch 6 closest to H21 is closed, the first shutoff valve 61 on each first bypass branch 6 downstream of the heat exchange assembly 21 next to H21 (i.e., M21), the third shutoff valve 11 on the first standby main pipeline 1 downstream of the last first bypass branch 6 are opened, and the remaining shutoff valves are opened, i.e., the faulty H21 can be isolated online, so that the staff can maintain the faulty H21 under the condition that the refrigeration system is running normally.

[0061] Fig. 4b is a schematic diagram of the opening and closing of each shutoff valve when the refrigeration system shown in Fig. 2a has a fault in M21. As shown in Fig. 4b, when M21 has a fault, the two second shutoff valves 31 adjacent to M21 are closed, the first shutoff valve 61 on each first bypass branch 6 adjacent to M21 is closed, the third shutoff valve 11 on the first standby main pipeline 1 upstream of the first first bypass branch 6 and the third shutoff valve 11 downstream of the last first bypass branch 6 are closed, and the remaining shutoff valves are opened, i.e., the faulty M21 can be isolated online, so that the staff can maintain the faulty M21 under the condition that the refrigeration system is running normally.

[0062] Fig. 4c is a schematic diagram of the opening and closing of each shutoff valve when the refrigeration system shown in Fig. 2a has a fault in T21 (i.e., the last heat exchange assembly 21). As shown in Fig. 4c, when T21 has a fault, the two second shutoff valves 31 adjacent to T21 are closed, the first shutoff valve 61 on each first bypass branch 6 adjacent to T21 is closed, the first shutoff valve 61 on each first bypass branch 6 upstream of the heat exchange assembly 21 next to T21 (i.e., M21) and the third shutoff valve 11 on the first standby main pipeline 1 upstream of the first first bypass branch 6 are closed, and the remaining shutoff valves are opened, i.e., the faulty T21 can be isolated online, so that the staff can maintain the faulty T21 under the condition that the refrigeration system is running normally.

[0063] When the number of refrigeration units 2 in the refrigeration system is greater than or equal to 2, the opening and closing of each shutoff valve when a certain heat exchange assembly 21 has a fault can be deduced from the above three cases, which will not be described one by one here.

[0064] When each refrigeration unit 2 is working normally, the first and third on-off valves 61 and 11 can be closed, and the second on-off valves 31 can be kept open. Of course, when each refrigeration unit 2 is working normally, the opening and closing of the on-off valves are not limited to the above-mentioned situation, as long as the water discharged from the first heat exchange device A can enter the second heat exchange device B through the heat exchange assemblies in sequence.

[0065] Fig. 5a is a schematic diagram of the opening and closing of the on-off valves when the refrigeration system shown in Fig. 3 fails at H21. As shown in Fig. 5a, when H21 fails, the two second on-off valves 31 adjacent to H21 are closed, the first on-off valve 61 on the first bypass branch 6 downstream of the heat exchange assembly 21 (i.e. M21) of the next stage of H21 is closed, the third on-off valve 11 on the first standby main pipeline 1 downstream of the last-stage first bypass branch 6 is closed, and the remaining on-off valves are opened, so that the failed H21 can be isolated online, and the staff can maintain the failed H21 under the condition that the refrigeration system is running normally.

[0066] Fig. 5b is a schematic diagram of the opening and closing of the on-off valves when the refrigeration system shown in Fig. 3 fails at M21. As shown in Fig. 5b, when M21 fails, the two second on-off valves 31 adjacent to M21 are closed, the third on-off valves 11 on the first standby main pipeline 1 upstream of the first-stage first bypass branch 6 and downstream of the last-stage first bypass branch 6 are closed, and the remaining on-off valves are opened, so that the failed M21 can be isolated online, and the staff can maintain the failed M21 under the condition that the refrigeration system is running normally.

[0067] Fig. 5c is a schematic diagram of the opening and closing of the on-off valves when the refrigeration system shown in Fig. 3 fails at T21. As shown in Fig. 5c, when T21 fails, the two second on-off valves 31 adjacent to T21 are closed, the first on-off valve 61 on the first bypass branch 6 upstream of the previous-stage heat exchange assembly 21 (i.e. M21) is closed, and the third on-off valve 11 on the first standby main pipeline 1 upstream of the first-stage first bypass branch 6 is closed, and the remaining on-off valves are opened, so that the failed T21 can be isolated online, and the staff can maintain the failed T21 under the condition that the refrigeration system is running normally.

[0068] When the number of refrigeration units 2 in the refrigeration system is greater than or equal to 2, the opening and closing of the on-off valves when the heat exchange assembly 21 fails can be deduced from the above-mentioned three situations, which will not be described one by one here.

[0069] As can be appreciated, when all the refrigeration units 2 are working normally, the third on-off valves 11 are closed, and the first on-off valves 61 and the second on-off valves 31 are kept open, or the first on-off valves 61 and the third on-off valves 11 are closed, and the second on-off valves 31 are kept open. Of course, when all the refrigeration units 2 are working normally, the on-off valves are not limited to the above-mentioned conditions, as long as the water discharged from the first heat exchange device A can enter the second heat exchange device B through the heat exchange assemblies in sequence.

[0070] In practice, the second on-off valves 31 can also fail. In order to isolate and maintain the failed second on-off valves 31 on-line, as shown in FIG. 6a, in a specific implementation, two first bypass branches 6 are connected between the first standby main pipeline 1 and the first pipelines 3. Each first pipeline 3 is provided with three second on-off valves 31, two of the three second on-off valves 31 are located between the corresponding two first bypass branches 6, and the remaining one of the three second on-off valves 31 is located between the first bypass branch 6 and the preceding heat exchange assembly 21. The first standby main pipeline 1 is provided with a third on-off valve 11 on the pipe section between the adjacent two first bypass branches 6. Of course, there can be more than three second on-off valves 31 on the first pipeline 3, and there can be at least one third on-off valve 11 on the pipe section between the adjacent two first bypass branches 6 of the first standby main pipeline 1.

[0071] The isolation and maintenance of the refrigeration system when a second on-off valve 31 fails will be described below with reference to FIGS. 6a-6c. In the figures, the second on-off valve 31 in the dashed box represents the failed second on-off valve 31, the on-off valve cut off by a straight line represents the closed on-off valve, and the broken line in the shape of a broken line represents the flow direction of the fluid in the refrigeration system. In order to facilitate understanding, in the following text, the second on-off valve 31 located at the most upstream of the three second on-off valves 31 on the first pipeline 3 is denoted as H31, the second on-off valve 31 located at the middle is denoted as M31, and the second on-off valve 31 located at the most downstream is denoted as T31.

[0072] FIG. 6a is a schematic diagram of the opening and closing of the on-off valves when the H31 on the first pipeline 3 downstream of the first heat exchange assembly 21 fails. As shown in FIG. 6a, when the H31 fails, the two second on-off valves 31 adjacent to the H31 are closed, the first on-off valve 61 on the first bypass branch 6 closest to the M31 is closed, and the third on-off valve 11 parallel to the second heat exchange assembly 21 and the third heat exchange assembly 21 is closed, and the remaining on-off valves are opened, that is, the failed H31 can be isolated on-line, so that the staff can maintain the failed H31 under the condition that the refrigeration system is running normally.

[0073] Fig. 6b is a schematic diagram of the opening and closing of each shutoff valve when the M31 on the first first pipeline 3 downstream of the first-stage heat exchange assembly 21 fails. As shown in Fig. 6b, when the M31 fails, the two second shutoff valves 31 adjacent to the M31 are closed, the second shutoff valve 31 upstream of the heat exchange assembly 21 upstream of the M31 is closed, the first shutoff valve 61 on the first bypass branch 6 between the M31 and the adjacent H31 is closed, the third shutoff valve 11 parallel to the second-stage heat exchange assembly 21 and the third-stage heat exchange assembly 21 is closed, and the remaining shutoff valves are opened, so that the failed M31 can be isolated online, and the staff can maintain the failed M31 under the condition that the refrigeration system is operating normally.

[0074] Fig. 6c is a schematic diagram of the opening and closing of each shutoff valve when the T31 on the first first pipeline 3 downstream of the first-stage heat exchange assembly 21 fails. As shown in Fig. 6c, when the T31 fails, the two second shutoff valves 31 adjacent to the T31 are closed, the first shutoff valve 61 on the first bypass branch 6 downstream of the T31 is closed, the third shutoff valve 11 parallel to the first-stage heat exchange assembly 21 and the third-stage heat exchange assembly 21 is closed, and the remaining shutoff valves are opened, so that the failed T31 can be isolated online, and the staff can maintain the failed T31 under the condition that the refrigeration system is operating normally.

[0075] The opening and closing of each shutoff valve when the second shutoff valve 31 on the other first pipeline 3 fails can be set according to the actual situation, which will not be described one by one. In addition, when each refrigeration unit 2 and each shutoff valve are operating normally in the refrigeration system shown in Fig. 6c, the opening and closing of each shutoff valve include but are not limited to: closing each first shutoff valve 61 and each third shutoff valve 11, and keeping each second shutoff valve 31 open.

[0076] In general, when a certain second shutoff valve 31 fails, the two second shutoff valves 31 adjacent to the failed second shutoff valve 31 are closed, and the first shutoff valve 6 on the first bypass branch 6 closest to the failed second shutoff valve 31 is closed. If the failed second shutoff valve 31 is isolated, the compressed refrigeration unit is also isolated, and the third shutoff valve 11 parallel to the isolated compressed refrigeration unit is opened; if the failed second shutoff valve 31 is isolated without isolating a compressed refrigeration unit, the third shutoff valve 11 parallel to the previous compressed refrigeration unit adjacent to the failed second shutoff valve 31 is opened, and the previous compressed refrigeration unit is not opened. The first and last third shutoff valves 11 on the first standby main pipeline 1 are closed, and the third shutoff valve 11 between the adjacent two pairs of first bypass branches 6 is closed.

[0077] In implementation, the first on-off valve 61 can also fail. In order to isolate and maintain the failed first on-off valve 61 when the first on-off valve 61 fails, as shown in FIG. 7a, in a specific implementation, two first on-off valves 61 are arranged on each first bypass branch 6 on the basis of the refrigeration system shown in FIG. 6c. Of course, at least two first on-off valves 61 can be arranged on each first bypass branch 6. The isolation and maintenance of the failed first on-off valve 61 in this scheme will be described below in combination with FIGS. 7a, 7b and 7c. In each figure, the first on-off valve 61 in the dashed box represents the failed first on-off valve 61, the on-off valve cut off by a straight line represents the closed on-off valve, and the broken line in the form of a broken line schematically shows the flow direction of the fluid in the refrigeration system. In order to facilitate understanding, in the following, of the two first on-off valves 61 on the first bypass branch 6, the first on-off valve 61 close to the first pipeline 3 is denoted as H61, and the first on-off valve 61 away from the first pipeline 3 is denoted as M61.

[0078] FIG. 7a is a schematic diagram of one opening and closing condition of each on-off valve when the H61 on the second first bypass branch 6 fails in the flow direction of the water in the first pipeline 3. As shown in FIG. 7a, when the H61 fails, the M61 on the same first bypass branch 6 as the H61 is closed, the first second on-off valve 31 upstream and downstream of the first bypass branch 6 is closed, the third on-off valve 11 parallel to the second-stage heat exchange assembly 21 and the third-stage heat exchange assembly 21 is closed, and the remaining on-off valves are opened, that is, the failed H61 can be isolated online. This enables the staff to maintain the failed H61 under the condition that the refrigeration system operates normally.

[0079] It should be noted that, as shown in FIG. 7a, if the failed first on-off valve 61 is isolated, the third on-off valve 11 parallel to the heat exchange assembly 21 also needs to be opened, and when the heat exchange assembly 21 is an evaporator 22 in a compression refrigeration unit, the compression refrigeration unit is not started. As shown in FIG. 7b, if the failed first on-off valve 61 is isolated, no heat exchange assembly 21 is isolated at the same time, the third on-off valve 11 parallel to the previous-stage heat exchange assembly 21 of the failed first on-off valve 61 needs to be opened, and when the previous-stage heat exchange assembly 21 is an evaporator 22 in a compression refrigeration unit, the compression refrigeration unit is not started. It should be understood that the opening and closing conditions of each on-off valve when the H61 fails are not limited to the above scheme, and other schemes can also be used, as long as the failed H61 can be isolated while the refrigeration system operates normally.

[0080] Fig. 7c is a schematic diagram of the opening and closing of each shutoff valve when M61 in the first bypass branch 6 fails in the flow direction of water in the first pipeline 3. As shown in Fig. 7c, when M61 fails, H61 in the same first bypass branch 6 as M61 is closed, each third shutoff valve 11 is closed, and the remaining shutoff valves are opened. This can isolate the failed M61 online, allowing maintenance of the failed M61 while the refrigeration system is operating normally. It should be understood that the opening and closing of each shutoff valve when M61 fails is not limited to the above scheme, and other schemes can also be used, as long as the failed M61 can be isolated while the refrigeration system is operating normally.

[0081] When the refrigeration system adopts the structure shown in Fig. 7c, the third shutoff valve 11 can also be isolated and maintained online when it fails. For example, as shown in Fig. 8, when the second third shutoff valve 11 fails in the flow direction of water in the first standby main pipeline 1 (i.e., the direction from right to left in the figure), the two first shutoff valves 61 adjacent to the third shutoff valve 11 are closed, each third shutoff valve 11 is closed, and the remaining shutoff valves are opened. This can isolate the failed third shutoff valve 11 online, allowing maintenance of the failed third shutoff valve 11 while the refrigeration system is operating normally. It should be understood that the opening and closing of each shutoff valve when the third shutoff valve 11 fails is not limited to the above scheme, and other schemes can also be used, as long as the failed third shutoff valve 11 can be isolated while the refrigeration system is operating normally.

[0082] When the number of refrigeration units 2 in the refrigeration system is greater than or equal to 2 in other cases, the opening and closing of the remaining shutoff valves when a shutoff valve fails can be inferred from the above cases, which will not be described one by one here.

[0083] In addition to the above-mentioned cases, the heat exchange assembly 21 of each refrigeration unit 2 can also be as follows: each refrigeration unit 2 is a compression refrigeration unit, the compression refrigeration unit comprises an evaporator 22 and a water-cooled condenser 24, the evaporator 22 being the heat exchange assembly 21 of the compression refrigeration unit; or at least two adjacent refrigeration units 2 are compression refrigeration units using water-cooled condensers 24, and the heat exchange assembly 21 of at least one refrigeration unit 2 is a first heat exchanger; or at least two adjacent refrigeration units 2 are compression refrigeration units using water-cooled condensers 24, and at least one refrigeration unit 2 is a compression refrigeration unit using an air-cooled condenser 23. Generally, a compression refrigeration unit is a module, so when one of the components of the compression refrigeration unit fails, the entire compression refrigeration unit needs to be isolated to achieve online maintenance. That is, when the refrigeration unit 2 is a compression refrigeration unit using a water-cooled condenser 24, if the refrigeration unit 2 fails, the water-cooled condenser 24 side of the refrigeration unit 2 also needs to be isolated.

[0084] Specifically, in some embodiments, at least two adjacent refrigeration units 2 are compression refrigeration units, the compression refrigeration unit comprises an evaporator 22 and a water-cooled condenser 24, and the evaporator 22 is the heat exchange assembly 21 of the compression refrigeration unit. It is not difficult to understand that the compression refrigeration unit also comprises a compressor 26 and an expansion valve 25. In order to isolate the refrigeration unit 2 with a failed water-cooled condenser 24 when the refrigeration unit 2 fails, as shown in FIG. 9a, the first and second water-cooled condensers 24 are connected by a second pipeline 8, and the water inlet of the first water-cooled condenser 24 is connected with a third pipeline 10, and the water outlet of the last water-cooled condenser 24 is connected with a fourth pipeline 20. The refrigeration system further comprises a second standby main pipeline 9, and the branch pipelines in which the water-cooled condensers 24 are located are connected in parallel with the second standby main pipeline 9. In practice, the water inlets of the above-mentioned two branch pipelines can be directly or indirectly connected to the water outlet of the same third heat exchange device D, and the water outlets of the above-mentioned two branch pipelines can be directly or indirectly connected to the water inlet of the same fourth heat exchange device E, and the third heat exchange device D, the water-cooled condensers 24 and the fourth heat exchange device E are in the same circulation loop. Exemplarily, the third heat exchange device D is a heat exchanger, and the fourth heat exchange device E is a cooling tower 50. It is not difficult to understand that when the heat exchange assembly 21 of the refrigeration unit 2 is a first heat exchanger, or when the refrigeration unit 2 is a compression refrigeration unit using an air-cooled condenser 23, only the heat exchange assembly 21 side of the refrigeration unit 2 needs to be isolated when the corresponding first heat exchanger or compression refrigeration unit using an air-cooled condenser 23 fails, so that the maintenance of the refrigeration unit 2 with a failure can be achieved. In this embodiment, each refrigeration unit 2 is taken as an example of a compression refrigeration unit using a water-cooled condenser 24 for description.

[0085] Please continue to refer to Figure 9a, in the implementation, the second standby main pipe 9 and each second pipe 8 are connected with at least two second bypass branches 30, the at least two second bypass branches 30 are in parallel, and each second bypass branch 30 is provided with at least one fourth on-off valve 301, each second pipe 8 is located between a pair of adjacent second bypass branches 30, and the third pipe 10 and the fourth pipe 20 are provided with at least one fifth on-off valve 81, and the second standby main pipe 9 is provided with a sixth on-off valve 91 on the pipe section upstream of the first-stage second bypass branch 30 and downstream of the last-stage second bypass branch 30. Obviously, the setting of the pipes and valves in the refrigeration system is not limited to the case shown in Figure 9a. For example, the setting of the pipes and valves in the refrigeration system can also be as shown in Figure 10a, wherein the difference between the refrigeration system shown in Figure 10a and the refrigeration system shown in Figure 9a is that in the refrigeration system shown in Figure 10a, the second standby main pipe 9 and each second pipe 8 are connected with at least one second bypass branch 30, and each second bypass branch 30 is provided with at least one fourth on-off valve 301, and each second pipe 8 is provided with at least one fifth on-off valve 81 on the two sides of one second bypass branch 30.

[0086] In this scheme, when each refrigeration unit 2 is normally working, the two third on-off valves 11 on the first standby main pipe 1 are closed, and the remaining on-off valves are in the normally open state. The two sixth on-off valves 91 on the second standby main pipe 9 are closed, and the remaining on-off valves are in the normally open state. Of course, the first on-off valve 61 and the fourth on-off valve 301 can also be closed, as long as the water entering the first-stage evaporator 22 can pass through each lower-stage evaporator 22 in turn, and the water entering the first-stage condenser can pass through each lower-stage condenser in turn. The first-stage evaporator 22 and the last-stage evaporator 22 are relative to the flow direction of the water in the first pipe 3, and the first-stage condenser and the last-stage condenser are relative to the flow direction of the water in the second pipe 8. According to different specific settings, the flow direction of the water in the first pipe 3 can be the same as or opposite to the flow direction of the water in the second pipe 8. Therefore, the condenser in the refrigeration unit 2 where the first-stage evaporator 22 is located can be the first-stage condenser or the last-stage condenser. Exemplarily, in Figures 9c and 10a, the condenser in the refrigeration unit 2 where the first-stage evaporator 22 is located is the last-stage condenser, and the condenser in the refrigeration unit 2 where the last-stage evaporator 22 is located is the first-stage condenser.

[0087] The isolation and maintenance of the evaporator side and the condenser side when the refrigeration unit 2 fails will be described below in combination with Figures 9a-10c, wherein in each figure, the refrigeration unit 2 in the dashed box represents the refrigeration unit 2 that fails, the on-off valve that is cut off by a straight line represents the closed on-off valve, and the broken line in the shape of a broken line schematically shows the flow direction of a section of the corresponding evaporator side or condenser side fluid in the refrigeration system.

[0088] As shown in Fig. 9a, the refrigeration system comprises three compression refrigeration units connected in series. When the first evaporator 22 and the last condenser of the refrigeration unit 2 fail, on the evaporator side, the two second shut-off valves 31 adjacent to the first evaporator 22 are closed, the first shut-off valve 61 on the first bypass branch 6 adjacent to the first evaporator 22 is closed, the first shut-off valves 61 on the first bypass branches 6 downstream of the first evaporator 22 and the second evaporator 22 are closed, the third shut-off valve 11 on the first standby main pipeline 1 upstream of the last first bypass branch 6 is opened, and the remaining shut-off valves are opened, so that the first evaporator 22 can be isolated on line. On the condenser side, the two fifth shut-off valves 81 adjacent to the last condenser are closed, the fourth shut-off valve 301 on the second bypass branch 30 adjacent to the last condenser is closed, the fourth shut-off valves 301 on the second bypass branches 30 upstream of the first condenser and the second condenser are closed, the sixth shut-off valve 91 on the second standby main pipeline 9 downstream of the first second bypass branch 30 is opened, and the remaining shut-off valves are opened, so that the last condenser can be isolated on line, thereby enabling the staff to maintain the refrigeration unit 2 under normal operation of the refrigeration system.

[0089] As shown in Fig. 9b, when the second evaporator 22 and the second condenser of the refrigeration unit 2 fail, on the evaporator side, the two second shut-off valves 31 adjacent to the second evaporator 22 are closed, the first shut-off valves 61 on the two first bypass branches 6 adjacent to the second evaporator 22 are closed, the third shut-off valves 11 on the first standby main pipeline 1 upstream of the first first bypass branch 6 and downstream of the last first bypass branch 6 are closed, and the remaining shut-off valves are opened, so that the second evaporator 22 can be isolated on line. On the condenser side, the two fifth shut-off valves 81 adjacent to the second condenser are closed, the fourth shut-off valves 301 on the two second bypass branches 30 adjacent to the second condenser are closed, the sixth shut-off valves 91 on the second standby main pipeline 9 upstream of the first second bypass branch 30 and downstream of the last second bypass branch 30 are closed, and the remaining shut-off valves are opened, so that the second condenser can be isolated on line, thereby enabling the staff to maintain the refrigeration unit 2 under normal operation of the refrigeration system.

[0090] As shown in Fig. 9c, when the last evaporator 22 and the first condenser of the refrigeration unit 2 fail, on the evaporator side, the two second shutoff valves 31 adjacent to the last evaporator 22 are closed, the first shutoff valve 61 on the first bypass branch 6 adjacent to the last evaporator 22 is closed, the first shutoff valves 61 on the first bypass branches 6 upstream of the evaporator 22 (i.e. the second evaporator 22) of the last evaporator 22 are closed, the third shutoff valve 11 on the first standby main pipeline 1 downstream of the last first bypass branch 6 is closed, and the remaining shutoff valves are opened, so that the last evaporator 22 of the refrigeration unit 2 can be isolated on line, and the maintenance of the refrigeration unit 2 can be performed under the condition that the refrigeration system is running normally. On the condenser side, the two fifth shutoff valves 81 adjacent to the first condenser are closed, the fourth shutoff valve 301 on the second bypass branch 30 of the first condenser is closed, the fourth shutoff valves 301 on the second bypass branches 30 downstream of the condenser (i.e. the second condenser) of the first condenser are closed, the sixth shutoff valve 91 on the second standby main pipeline 9 downstream of the last second bypass branch 30 is closed, and the remaining shutoff valves are opened, so that the first condenser of the refrigeration unit 2 can be isolated on line, and the maintenance of the refrigeration unit 2 can be performed under the condition that the refrigeration system is running normally.

[0091] As shown in Fig. 10a, the refrigeration system comprises three compression refrigeration units in series, when the first evaporator 22 and the last condenser of the refrigeration unit 2 fail, on the evaporator side, the two second shutoff valves 31 adjacent to the first evaporator 22 are closed, the first shutoff valve 61 on the first bypass branch 6 downstream of the evaporator 22 (i.e. the second evaporator 22) of the first evaporator 22 is closed, the third shutoff valve 11 on the first standby main pipeline 1 downstream of the last first bypass branch 6 is closed, and the remaining shutoff valves are opened, so that the first evaporator 22 of the refrigeration unit 2 can be isolated on line, and the maintenance of the refrigeration unit 2 can be performed under the condition that the refrigeration system is running normally. On the condenser side, the two fifth shutoff valves 81 adjacent to the last evaporator 22 are closed, the fourth shutoff valve 301 on the second bypass branch 30 upstream of the condenser (i.e. the second condenser) of the last evaporator 22 is closed, the sixth shutoff valve 91 on the second standby main pipeline 9 upstream of the first second bypass branch 30 is closed, and the remaining shutoff valves are opened, so that the last condenser of the refrigeration unit 2 can be isolated on line, and the maintenance of the refrigeration unit 2 can be performed under the condition that the refrigeration system is running normally.

[0092] As shown in Fig. 10b, when the second stage evaporator 22 and the second stage condenser of the refrigeration unit 2 fail, on the evaporator side, the two second shutoff valves 31 adjacent to the second stage evaporator 22 are closed, the third shutoff valve 11 on the first standby main pipeline 1 upstream of the first stage first bypass branch 6 and downstream of the last stage first bypass branch 6 is closed, and the rest of the shutoff valves are opened, so that the failed second stage evaporator 22 can be isolated online. On the condenser side, the two fifth shutoff valves 81 adjacent to the second stage condenser are closed, the sixth shutoff valve 91 on the second standby main pipeline 9 upstream of the first stage second bypass branch 30 and downstream of the last stage second bypass branch 30 is closed, and the rest of the shutoff valves are opened, so that the failed condenser can be isolated online, thereby enabling the staff to maintain the failed refrigeration unit 2 under the condition that the refrigeration system is running normally.

[0093] As shown in Fig. 10c, when the last stage evaporator 22 and the first stage condenser of the refrigeration unit 2 fail, on the evaporator side, the two second shutoff valves 31 adjacent to the last stage evaporator 22 are closed, the first shutoff valve 61 on the first bypass branch 6 upstream of the previous stage evaporator 22 (i.e. the second stage evaporator 22) and the third shutoff valve 11 on the first standby main pipeline 1 upstream of the first stage first bypass branch 6 are closed, and the rest of the shutoff valves are opened, so that the failed evaporator 22 can be isolated online. On the condenser side, the two fifth shutoff valves 81 adjacent to the first stage condenser are closed, the fourth shutoff valve 301 on the second bypass branch 30 downstream of the condenser of the next stage of the first stage condenser (i.e. the second stage condenser) and the sixth shutoff valve 91 on the second standby main pipeline 9 downstream of the last stage second bypass branch 30 are closed, and the rest of the shutoff valves are opened, so that the failed first stage condenser can be isolated online, thereby enabling the staff to maintain the failed refrigeration unit 2 under the condition that the refrigeration system is running normally.

[0094] When the number of compression refrigeration units with water-cooled condenser 24 in the refrigeration system is greater than or equal to 2, the opening and closing of the shutoff valves when the compression refrigeration unit fails can be inferred from the above-mentioned cases, which will not be described one by one here.

[0095] It should be understood that the arrangement of the evaporator side and condenser side pipes and on-off valves is not limited to the above-mentioned combination, and other combination directions can also be adopted, for example, the evaporator side pipe and on-off valve adopts the structure of the evaporator side pipe and on-off valve in Fig. 9c, the condenser side pipe and on-off valve adopts the structure of the condenser side pipe and on-off valve in Fig. 10a; or, the evaporator side pipe and on-off valve adopts the structure of the evaporator side pipe and on-off valve in Fig. 10a, the condenser side pipe and on-off valve adopts the structure of the condenser side pipe and on-off valve in Fig. 9c; or, the evaporator side pipe and on-off valve adopts the structure in Fig. 8, the condenser side pipe and on-off valve adopts the structure of the condenser side pipe and on-off valve in Fig. 9c or Fig. 10a, and so on. In each of the above cases, the opening and closing of the on-off valves in the case of a specific fault can be deduced from the foregoing and will not be described one by one here.

[0096] Fig. 11a is a schematic structural diagram of a refrigeration system provided by the present application. As shown in Fig. 11a, in a specific implementation, the second standby main pipe 9 is connected with each second pipe 8 through two second bypass branches 30; each second pipe 8 is provided with three fifth on-off valves 81, two of the three fifth on-off valves 81 are located between the corresponding two second bypass branches 30, and the remaining one of the three fifth on-off valves 81 is located between the two second bypass branches 30 and the preceding water-cooled condenser 24; the second standby main pipe 9 located on the pipe section between the adjacent two second bypass branches 30 is provided with a sixth on-off valve 91. Of course, at least three fifth on-off valves 81 can be provided on the second pipe 8, and at least one sixth on-off valve 91 can be provided on the pipe section between the adjacent two second bypass branches 30 of the second standby main pipe 9. When this scheme is adopted, the fault fifth on-off valve 81 can also be isolated when the condenser side fifth on-off valve 81 fails. The opening and closing of the valves when the evaporator side fails can be referred to the foregoing and will not be described here. The opening and closing of the valves when the condenser side fifth on-off valve 81 fails will be briefly described below in combination with Figs. 11a-11c. In each of the figures, the fifth on-off valve 81 in the dashed box represents the fault fifth on-off valve 81, the on-off valve cut off by the straight line represents the closed on-off valve, and the broken line in the shape of a broken line schematically shows the flow direction of the fluid in the refrigeration system. In order to facilitate understanding, in the following, of the three fifth on-off valves 81 on the second pipe 8, the fifth on-off valve 81 located at the most upstream is denoted as H81, the fifth on-off valve 81 located at the middle is denoted as M81, and the fifth on-off valve 81 located at the most downstream is denoted as T81.

[0097] Fig. 11a is a schematic diagram of the opening and closing of each shutoff valve when the H81 on the first second pipeline 8 downstream of the first water-cooled condenser 24 fails. As shown in Fig. 11a, when the H81 fails, the two fifth shutoff valves 81 adjacent to the H81 are closed, the fourth shutoff valve 301 on the second bypass branch 30 closest to the H81 is closed, the sixth shutoff valve 91 parallel to the second water-cooled condenser 24 and the third water-cooled condenser 24 is closed, and the remaining shutoff valves are opened, so that the failed H81 can be isolated online, and the staff can maintain the failed H81 under the condition that the refrigeration system is running normally.

[0098] Fig. 11b is a schematic diagram of the opening and closing of each shutoff valve when the M81 on the first second pipeline 8 downstream of the first water-cooled condenser 24 fails. As shown in Fig. 11b, when the M81 fails, the two fifth shutoff valves 81 adjacent to the M81 are closed, the fifth shutoff valve 81 upstream of the water-cooled condenser 24 upstream of the M81 is closed, the fourth shutoff valve 301 on the second bypass branch 30 between the H81 and the M81 is closed, the sixth shutoff valve 91 parallel to the second water-cooled condenser 24 and the third water-cooled condenser 24 is closed, and the remaining shutoff valves are opened, so that the failed M81 can be isolated online, and the staff can maintain the failed M81 under the condition that the refrigeration system is running normally. Of course, when the M81 fails, the opening and closing of each shutoff valve in the refrigeration system can also adopt other schemes, which are not listed one by one here.

[0099] Fig. 11c is a schematic diagram of the opening and closing of each shutoff valve when the T81 on the first second pipeline 8 downstream of the first water-cooled condenser 24 fails. As shown in Fig. 11c, when the T81 fails, the two fifth shutoff valves 81 adjacent to the T81 are closed, the fourth shutoff valve 301 on the first second bypass branch 30 downstream of the T81 is closed, and the sixth shutoff valve 91 parallel to the first water-cooled condenser 24 and the third water-cooled condenser 24 is closed, and the remaining shutoff valves are opened, so that the failed T81 can be isolated online, and the staff can maintain the failed T81 under the condition that the refrigeration system is running normally. When the T81 fails, the opening and closing of each shutoff valve in the refrigeration system can also adopt other schemes, which are not listed one by one here.

[0100] When the fifth shutoff valve 81 on the other second pipeline 8 fails, the opening and closing of each shutoff valve can be set according to the actual situation, which is not described one by one here. In addition, when each refrigeration unit 2 and each shutoff valve in the refrigeration system shown in Fig. 11c are working normally, the opening and closing strategy of each shutoff valve includes but is not limited to: closing each first shutoff valve 61, third shutoff valve 11, fourth shutoff valve 301 and each sixth shutoff valve 91, and keeping the remaining shutoff valves open.

[0101] Fig. 12a is a schematic diagram of a refrigeration system according to the present application. The refrigeration system shown in Fig. 12a is different from the refrigeration system shown in Fig. 11c in that two fourth on-off valves 301 are provided on each second bypass branch 30. Of course, at least two fourth on-off valves 301 can be provided on each second bypass branch 30. With this scheme, the isolation and on-line maintenance of the faulty fourth on-off valve 301 can also be realized when the fourth on-off valve 301 fails. The isolation and maintenance of the faulty fourth on-off valve 301 in this scheme will be described below in connection with Fig. 12a, Fig. 12b and Fig. 12c. In each figure, the fourth on-off valve 301 in the dashed box represents the faulty fourth on-off valve 301, the on-off valve cut off by the straight line represents the closed on-off valve, and the broken line in the zigzag shape schematically shows the flow direction of the fluid in the refrigeration system. For the sake of convenience, the two fourth on-off valves 301 on the second bypass branch 30 will be referred to as H301 and M301 in the following description, wherein H301 is the fourth on-off valve 301 close to the second pipeline 8 and M301 is the fourth on-off valve 301 far away from the second pipeline 8.

[0102] Fig. 12a is a schematic diagram of the opening and closing of the on-off valves when the H301 on the second bypass branch 30 fails in the flow direction of the water in the second pipeline 8. As shown in Fig. 12a, when the H301 fails, the M301 on the same second bypass branch 30 as the H301 is closed, the first fifth on-off valve 81 upstream and downstream of the second bypass branch 30 is closed, the sixth on-off valve 91 parallel to the first water-cooled condenser 24 and the third water-cooled condenser 24 is closed, and the remaining on-off valves are opened. That is, the fifth on-off valve 81 closest to the faulty fourth on-off valve 301 upstream and downstream is closed, the other fourth on-off valve 301 on the second bypass branch 30 where the faulty fourth on-off valve 301 is located is closed, the sixth on-off valve 91 parallel to the first water-cooled condenser 24 and the third water-cooled condenser 24 is closed, and the remaining on-off valves are opened, so that the faulty H301 can be isolated on-line. This enables the maintenance of the faulty H301 under the condition that the refrigeration system is operating normally.

[0103] It should be noted that, as shown in Fig. 12a, if the fourth on-off valve 301 isolating the fault is also isolating the water-cooled condenser 24, the sixth on-off valve 91 in parallel with the water-cooled condenser 24 needs to be opened, and the compression refrigeration unit not in operation. As shown in Fig. 12b, if the fourth on-off valve 301 isolating the fault is not isolating the water-cooled condenser 24, the sixth on-off valve 91 in parallel with the water-cooled condenser 24 needs to be opened, and the compression refrigeration unit not in operation. It should be understood that, when the H301 fails, the opening and closing of the on-off valves are not limited to the above-mentioned scheme, and other schemes can also be used as long as the refrigeration system can be ensured to operate normally and the H301 fails to be isolated.

[0104] Fig. 12c is a schematic diagram of the opening and closing of the on-off valves when the M301 in the first second bypass branch 30 fails in the flow direction of the water in the second pipeline 8. As shown in Fig. 12c, when the M301 fails, the H301 in the same second bypass branch 30 as the M301 is closed, and each sixth on-off valve 91 is closed, and the remaining on-off valves are opened, so that the M301 fails to be isolated online, and the staff can maintain the M301 under the condition that the refrigeration system operates normally. It should be understood that, when the M301 fails, the opening and closing of the on-off valves are not limited to the above-mentioned scheme, and other schemes can also be used as long as the refrigeration system can be ensured to operate normally and the M301 fails to be isolated.

[0105] When the refrigeration system adopts the structure shown in Fig. 12c, the sixth on-off valve 91 can also be isolated online and maintained when the sixth on-off valve 91 fails. As shown in Fig. 13, when the second sixth on-off valve 91 fails in the flow direction of the water in the second standby main pipeline 9 (that is, the direction from left to right in the figure), the two fourth on-off valves 301 adjacent to the sixth on-off valve 91 are closed, and each sixth on-off valve 91 is closed, and the remaining on-off valves are opened, so that the sixth on-off valve 91 fails to be isolated online, and the staff can maintain the sixth on-off valve 91 under the condition that the refrigeration system operates normally. It should be understood that, when the sixth on-off valve 91 fails, the opening and closing of the on-off valves are not limited to the above-mentioned scheme, and other schemes can also be used as long as the refrigeration system can be ensured to operate normally and the sixth on-off valve 91 fails to be isolated.

[0106] It should be understood that each on-off valve mentioned in the present application can be a manual valve or an electrically controlled valve.

[0107] Fig. 14a is a structural schematic diagram of a refrigeration system. As shown in Fig. 14a, the refrigeration system comprises a second heat exchanger 40, the second heat exchanger 40 comprising a first flow channel and a second flow channel which are isolated from each other and are in heat conduction connection. The water inlet of the first standby main pipeline 1 and the water inlet of the first-stage heat exchange assembly 21 are connected to the water outlet of the first flow channel of the second heat exchanger 40. The water inlet of the second standby main pipeline 9 and the water inlet of the first-stage water-cooled condenser 24 are connected to the water outlet of the second flow channel of the second heat exchanger 40. Exemplarily, the refrigeration system comprises a cooling tower 50, the water outlet of the second standby main pipeline 9 and the water outlet of the last-stage water-cooled condenser 24 are connected to the water inlet of the cooling tower 50, and the water outlet of the cooling tower 50 is connected to the water inlet of the second flow channel of the second heat exchanger 40. The refrigeration system further comprises a surface cooler 7, the water inlet of the first flow channel of the second heat exchanger 40 is connected to the water outlet of the surface cooler 7, and the water outlet of the first standby main pipeline 1 and the water outlet of the last-stage heat exchange assembly 21 are connected to the water inlet of the surface cooler 7. The surface cooler 7 can be arranged in a data center 400 or an industrial plant which needs refrigeration, so as to realize refrigeration of the corresponding data center 400 or the industrial plant.

[0108] The refrigeration system provided by the present application is described in detail below in combination with FIG. 14a. As shown in FIG. 14a, the refrigeration system includes three compression refrigeration units connected in series, a second heat exchanger 40, an air-water surface cooler 7 and a cooling tower 50. On the evaporator side, the water outlet of the air-water surface cooler 7 is connected to the water inlet of the first flow channel of the second heat exchanger 40 (i.e. the water inlet of the secondary side), the water outlet of the first flow channel of the second heat exchanger 40 is connected to the water inlet of the evaporator 22 through the water inlet pipeline 4, the evaporators 22 are connected in series through the corresponding first pipelines 3, and the water outlet of the last evaporator 22 is connected to the water inlet of the air-water surface cooler 7 through the water outlet pipeline 5 and the circulating pump 300'. The first standby main pipeline 1 is connected in parallel with the branch in which the evaporator 22 is located, that is, the water inlet of the first standby main pipeline 1 is connected to the water outlet of the first flow channel of the second heat exchanger 40, and the water outlet of the first standby main pipeline 1 is also connected to the water inlet of the air-water surface cooler 7 through the circulating pump 300'. In order to improve the reliability of the refrigeration system, the water outlet of the first standby main pipeline 1 is connected to the water inlet of the air-water surface cooler 7 through at least two parallel circulating pumps 300' and corresponding pipelines after being combined with the water outlet of the water outlet pipeline 5. The air-water surface cooler 7 is used to cool the data center 400 or the corresponding industrial plant. Further, two first bypass branches 6 are connected between the first standby main pipeline 1 and each first pipeline 3, and two first on-off valves 61 are arranged on each first bypass branch 6. Three second on-off valves 31 are arranged on each first pipeline 3, two of the three second on-off valves 31 are arranged between the corresponding two first bypass branches 6, and the remaining one of the three second on-off valves 31 is arranged between the first bypass branch 6 and the previous heat exchange assembly 21. The third on-off valve 11 is arranged on the pipeline section between the first standby main pipeline 1 and the two adjacent first bypass branches 6.

[0109] On the condenser side, two adjacent water-cooled condensers 24 are connected by the second pipe 8, and the inlet of the first water-cooled condenser 24 is connected with the third pipe 10, and the outlet of the last water-cooled condenser 24 is connected with the fourth pipe 20. The branch with the water-cooled condensers 24 is connected in parallel with the second backup main pipe 9, and the inlet of the second backup main pipe 9 and the inlet of the third pipe 10 are connected with the outlet of the second flow passage of the second heat exchanger 40 (i.e. the outlet of the primary side), and the outlet of the second backup main pipe 9 and the outlet of the fourth pipe 20 are connected with the inlet of the cooling tower 50. The outlet of the cooling tower 50 is connected with the inlet of the second flow passage of the second heat exchanger 40 through at least two circulating pumps 300' in parallel. The second backup main pipe 9 is connected with each second pipe 8 through two second bypass branches 30 in parallel, and each second bypass branch 30 is provided with two fourth on-off valves 301. The pipe section of each second pipe 8 between a pair of adjacent second bypass branches 30 is provided with two fifth on-off valves 81, and the pipe section of each second pipe 8 upstream of the corresponding two second bypass branches 30 is also provided with a fifth on-off valve 81. The pipe section of the second backup main pipe 9 between adjacent second bypass branches 30 is provided with a sixth on-off valve 91.

[0110] When each refrigeration unit 2 is normally operated in the refrigeration system shown in FIG. 14a, the first and last third on-off valves 11 on the first backup main pipe 1 are closed, the third on-off valves 11 between adjacent two pairs of first bypass branches 6 are closed, and the remaining on-off valves are opened. The first and last sixth on-off valves 91 on the second backup main pipe 9 are closed, the sixth on-off valves 91 between adjacent two pairs of second bypass branches 30 are closed, and the remaining on-off valves are opened. Among them, a pair of first bypass branches 6 refers to two first bypass branches 6 connected to the same first pipe 3, and a pair of second bypass branches refers to two second bypass branches 30 connected to the same second pipe 8.

[0111] Please refer to FIG. 14b, when a certain refrigeration unit 2 fails, on the evaporator side of the failed refrigeration unit 2, the second on-off valves 31 on both sides of the evaporator 22 are closed, the third on-off valve 11 connected in parallel with the evaporator 22 is opened, and the remaining on-off valves remain in the same state as when normally operated, i.e. the evaporator 22 of the failed refrigeration unit 2 can be isolated. On the condenser side of the failed refrigeration unit 2, the fifth on-off valves 81 on both sides of the condenser are closed, the sixth on-off valve 91 connected in parallel with the condenser is opened, and the remaining on-off valves remain in the same state as when normally operated, i.e. the condenser of the failed refrigeration unit 2 can be isolated.

[0112] Please refer to Fig. 6c, when a second shutoff valve 31 fails, the two second shutoff valves 31 closest to the second shutoff valve 31 are closed, and the first shutoff valve 61 on the first bypass branch 6 closest to the second shutoff valve 31 is closed. If the second shutoff valve 31 is isolated, the refrigeration unit 2 is also isolated, the third shutoff valve 11 in parallel with the isolated refrigeration unit 2 is opened, and the isolated refrigeration unit 2 is not started. If the second shutoff valve 31 is isolated, the refrigeration unit 2 is not isolated, the third shutoff valve 11 in parallel with the refrigeration unit 2 closest to the second shutoff valve 31 is opened, and the refrigeration unit 2 is not started. The states of the remaining shutoff valves remain the same as when the refrigeration system is normally operated.

[0113] Please refer to Fig. 7a, when a first shutoff valve 61 far from the first standby main pipeline 1 fails, the two second shutoff valves 31 closest to the first shutoff valve 61 are closed, and the other first shutoff valve 61 on the same first bypass branch 6 as the first shutoff valve 61 is closed. If the first shutoff valve 61 fails, the refrigeration unit 2 is also isolated, the third shutoff valve 11 in parallel with the isolated refrigeration unit 2 is opened, and the isolated refrigeration unit 2 is not started. If the first shutoff valve 61 fails, the refrigeration unit 2 is not isolated, the third shutoff valve 11 in parallel with the refrigeration unit 2 closest to the first shutoff valve 61 is opened, and the refrigeration unit 2 is not started. The states of the remaining shutoff valves remain the same as when the refrigeration system is normally operated, that is, the isolation and maintenance of the failed first shutoff valve 61 can be realized on the basis of normal operation of the refrigeration system.

[0114] Please refer to Fig. 7c, when a first shutoff valve 61 close to the first standby main pipeline 1 fails, the two third shutoff valves 11 closest to the first shutoff valve 61 are closed, and the other first shutoff valve 61 on the same first bypass branch 6 as the first shutoff valve 61 is closed. The states of the remaining shutoff valves remain the same as when the refrigeration system is normally operated. Thus, the isolation and maintenance of the failed first shutoff valve 61 can be realized on the basis of normal operation of the refrigeration system.

[0115] Please refer to Fig. 8, when a third shutoff valve 11 fails, the two third shutoff valves 11 closest to the third shutoff valve 11 are closed, and the first shutoff valves 61 on the two first bypass branches 6 closest to the first standby main pipeline 1 and adjacent to the third shutoff valve 11 are closed. The states of the remaining shutoff valves remain the same as when the refrigeration system is normally operated. Thus, the isolation and maintenance of the failed third shutoff valve 11 can be realized on the basis of normal operation of the refrigeration system.

[0116] Please refer to Fig. 11c, when a fifth shutoff valve 81 fails, the two fifth shutoff valves 81 closest to the fifth shutoff valve 81 are closed, and the fourth shutoff valve 301 on the second bypass branch 30 closest to the fifth shutoff valve 81 is closed. If the refrigeration unit 2 is isolated at the same time as the fifth shutoff valve 81 is isolated, the sixth shutoff valve 91 in parallel with the isolated refrigeration unit 2 is opened, and the isolated refrigeration unit 2 is not started. Please refer to Fig. 11b, if the refrigeration unit 2 is not isolated at the same time as the fifth shutoff valve 81 is isolated, the sixth shutoff valve 91 in parallel with the refrigeration unit 2 before the fifth shutoff valve 81 is opened, and the refrigeration unit 2 before the fifth shutoff valve 81 is not started. The states of the rest of the shutoff valves remain the same as when the refrigeration system is operating normally.

[0117] Please refer to Fig. 12a, when a fourth shutoff valve 301 far from the second standby main pipeline 9 fails, the fifth shutoff valves 81 closest to the fourth shutoff valve 301 on the left and right sides are closed, and the other fourth shutoff valve 301 on the same second bypass branch 30 as the fourth shutoff valve 301 is closed. If the refrigeration unit 2 is isolated at the same time as the failed fourth shutoff valve 301 is isolated, the sixth shutoff valve 91 in parallel with the isolated refrigeration unit 2 is opened, and the isolated refrigeration unit 2 is not started. Please refer to Fig. 12b, if the refrigeration unit 2 is not isolated at the same time as the failed fourth shutoff valve 301 is isolated, the sixth shutoff valve 91 in parallel with the refrigeration unit 2 before the failed fourth shutoff valve 301 is opened, and the refrigeration unit 2 before the failed fourth shutoff valve 301 is not started. The states of the rest of the shutoff valves remain the same as when the refrigeration system is operating normally. Thus, the isolation and maintenance of the failed fourth shutoff valve 301 can be realized on the basis of the normal operation of the refrigeration system.

[0118] Please refer to Fig. 12c, when a fourth shutoff valve 301 close to the second standby main pipeline 9 fails, the sixth shutoff valves 91 closest to the fourth shutoff valve 301 on the left and right sides are closed, and the other fourth shutoff valve 301 on the same second bypass branch 30 as the fourth shutoff valve 301 is closed. The states of the rest of the shutoff valves remain the same as when the refrigeration system is operating normally, i.e., the isolation and maintenance of the failed fourth shutoff valve 301 can be realized on the basis of the normal operation of the refrigeration system.

[0119] Please refer to Fig. 13, when a sixth shutoff valve 91 fails, the sixth shutoff valves 91 adjacent to the failed sixth shutoff valve 91 on the left and right sides are closed, and the fourth shutoff valves 301 on the two second bypass branches 30 adjacent to the second standby main pipeline 9 and adjacent to the failed sixth shutoff valve 91 are closed. The states of the rest of the shutoff valves remain the same as when the refrigeration system is operating normally. Thus, the isolation and maintenance of the failed sixth shutoff valve 91 can be realized on the basis of the normal operation of the refrigeration system.

[0120] Fig. 15 is a structural schematic diagram of another refrigeration system provided by the present application. The refrigeration system shown in Fig. 15 is different from the refrigeration system shown in Fig. 14b in that each refrigeration unit 2 is a compression refrigeration unit using an air-cooled condenser 23, and the condenser side has only condensers and no connection between the condensers. The water inlet of the water inlet pipeline 4 and the water inlet of the first backup main pipeline 1 are connected to the water outlet of the cooling coil 7, and the water outlet of the water outlet pipeline 5 and the water outlet of the first backup main pipeline 1 are connected to the water inlet of the cooling coil 7. In this scheme, when the refrigeration unit 2 and each on-off valve fail, the opening and closing conditions of each on-off valve in the refrigeration system can refer to the opening and closing conditions of each on-off valve on the evaporator side of the refrigeration system shown in Fig. 14b when the same failure occurs, and this will not be specifically described here.

[0121] Obviously, those skilled in the art can make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application also intends to include these modifications and variations.

Claims

A refrigeration system characterized by The first standby main pipeline and at least two refrigeration units connected in series, wherein each of the refrigeration units comprises a heat exchange assembly, two adjacent levels of the heat exchange assemblies are connected through a first pipeline, a water inlet of a first level of the heat exchange assemblies is connected with a water inlet of the first standby main pipeline through a water inlet pipeline, and a water outlet of a last level of the heat exchange assemblies is connected with a water outlet of the first standby main pipeline through a water outlet pipeline; At least two first bypass branches are connected between the first standby main pipeline and each of the first pipelines, the at least two first bypass branches are in parallel, and at least one first on-off valve is arranged on each of the first bypass branches; at least one second on-off valve is arranged on a pipeline section between each of the first pipelines and a pair of adjacent first bypass branches; or at least one first bypass branch is connected between the first standby main pipeline and each of the first pipelines, at least one first on-off valve is arranged on each of the first bypass branches, and at least one second on-off valve is arranged on each of the first pipelines and on both sides of one of the first bypass branches; Second on-off valves are arranged on the water inlet pipeline and the water outlet pipeline, and third on-off valves are arranged on pipeline sections of the first standby main pipeline, upstream of the first bypass branch of the first level and downstream of the first bypass branch of the last level. The refrigeration system of claim 1 wherein, Two first bypass branches are connected between the first standby main pipeline and each of the first pipelines; three second on-off valves are arranged on each of the first pipelines, two of the three second on-off valves are arranged between the corresponding two first bypass branches, and the remaining one of the three second on-off valves is arranged between the first bypass branch and the heat exchange assembly of the previous level; Third on-off valves are arranged on pipeline sections of the first standby main pipeline between adjacent two first bypass branches. The refrigeration system of claim 2 wherein, Two first on-off valves are arranged on each of the first bypass branches. The refrigeration system of claim 1 wherein, The water inlet of the first standby main pipeline and the water inlet of the heat exchange assembly of the first level are connected with a water outlet of a surface cooler, and the water outlet of the first standby main pipeline and the water outlet of the heat exchange assembly of the last level are connected with a water inlet of the surface cooler. The refrigeration system according to any one of claims 1 to 4, characterized in that The heat exchange assembly is a first heat exchanger, or the refrigeration unit is a compression type refrigeration unit, the compression type refrigeration unit comprises an evaporator and an air-cooled condenser, and the heat exchange assembly is the evaporator. The refrigeration system of claim 1 wherein, At least two adjacent refrigeration units are compression type refrigeration units, the compression type refrigeration units comprise evaporators and water-cooled condensers, the heat exchange assemblies are the evaporators, two adjacent levels of the water-cooled condensers are connected through a second pipeline, a water inlet of a first level of the water-cooled condensers is connected with a third pipeline, and a water outlet of a last level of the water-cooled condensers is connected with a fourth pipeline; the refrigeration system further comprises a second standby main pipeline, and branches in which the water-cooled condensers are located are connected in parallel with the second standby main pipeline. The second standby main pipeline is connected with each of the second pipelines via at least two second bypass branches, the at least two second bypass branches are in parallel, at least one fourth on-off valve is arranged on each of the second bypass branches, and at least one fifth on-off valve is arranged on a pipeline section between a pair of adjacent second bypass branches of each of the second pipelines; or, the second standby main pipeline is connected with each of the second pipelines via at least one second bypass branch, at least one fourth on-off valve is arranged on each of the second bypass branches, and at least one fifth on-off valve is arranged on each of the second pipelines and on both sides of one of the second bypass branches; The third pipeline and the fourth pipeline are also provided with fifth on-off valves, and a sixth on-off valve is arranged on a pipeline section of the second standby main pipeline, upstream of the first-stage second bypass branch and downstream of the last-stage second bypass branch. The refrigeration system of claim 6 wherein The second standby main pipeline is connected with each of the second pipelines via two second bypass branches; each of the second pipelines is provided with three fifth on-off valves, two of the three fifth on-off valves are arranged between corresponding two second bypass branches, and the remaining one of the three fifth on-off valves is arranged between the second bypass branch and the preceding-stage water-cooled condenser; The second standby main pipeline is provided with a sixth on-off valve on a pipeline section between adjacent two second bypass branches. The refrigeration system of claim 7 wherein Each of the second bypass branches is provided with two fourth on-off valves. The refrigeration system of claim 6 wherein The second heat exchanger comprises a first flow channel and a second flow channel which are isolated from each other and in thermal connection, the water inlet of the first standby main pipeline and the water inlet of the first-stage heat exchange assembly are connected with a water outlet of the first flow channel of the second heat exchanger, and the water inlet of the second standby main pipeline and the water inlet of the last-stage water-cooled condenser are connected with a water outlet of the second flow channel of the second heat exchanger. The refrigeration system of claim 9 wherein, The second standby main pipeline is connected with each of the second pipelines via at least two second bypass branches, the at least two second bypass branches are in parallel, at least one fourth on-off valve is arranged on each of the second bypass branches, and at least one fifth on-off valve is arranged on a pipeline section between a pair of adjacent second bypass branches of each of the second pipelines; or, the second standby main pipeline is connected with each of the second pipelines via at least one second bypass branch, at least one fourth on-off valve is arranged on each of the second bypass branches, and at least one fifth on-off valve is arranged on each of the second pipelines and on both sides of one of the second bypass branches; The refrigeration system of claim 9 wherein The third pipeline and the fourth pipeline are also provided with fifth on-off valves, and a sixth on-off valve is arranged on a pipeline section of the second standby main pipeline, upstream of the first-stage second bypass branch and downstream of the last-stage second bypass branch. The second standby main pipeline is connected with each of the second pipelines via two second bypass branches; each of the second pipelines is provided with three fifth on-off valves, two of the three fifth on-off valves are arranged between corresponding two second bypass branches, and the remaining one of the three fifth on-off valves is arranged between the second bypass branch and the preceding-stage water-cooled condenser; The second standby main pipeline is provided with a sixth on-off valve on a pipeline section between adjacent two second bypass branches. Each of the second bypass branches is provided with two fourth on-off valves. The second heat exchanger comprises a first flow channel and a second flow channel which are isolated from each other and in thermal connection, the water inlet of the first standby main pipeline and the water inlet of the first-stage heat exchange assembly are connected with a water outlet of the first flow channel of the second heat exchanger, and the water inlet of the second standby main pipeline and the water inlet of the last-stage water-cooled condenser are connected with a water outlet of the second flow channel of the second heat exchanger. The second standby main pipeline is connected with each of the second pipelines via at least two second bypass branches, the at least two second bypass branches are in parallel, at least one fourth on-off valve is arranged on each of the second bypass branches, and at least one fifth on-off valve is arranged on a pipeline section between a pair of adjacent second bypass branches of each of the second pipelines; or, the second standby main pipeline is connected with each of the second pipelines via at least one second bypass branch, at least one fourth on-off valve is arranged on each of the second bypass branches, and at least one fifth on-off valve is arranged on each of the second pipelines and on both sides of one of the second bypass branches; The third pipeline and the fourth pipeline are also provided with fifth on-off valves, and a sixth on-off valve is arranged on a pipeline section of the second standby main pipeline, upstream of the first-stage second bypass branch and downstream of the last-stage second bypass branch. The second standby main pipeline is connected with each of the second pipelines via two second bypass branches; each of the second pipelines is provided with three fifth on-off valves, two of the three fifth on-off valves are arranged between corresponding two second bypass branches, and the remaining one of the three fifth on-off valves is arranged between the second bypass branch and the preceding-stage water-cooled condenser; The second standby main pipeline is provided with a sixth on-off valve on a pipeline section between adjacent two second bypass branches. Each of the second bypass branches is provided with two fourth on-off valves. The second heat exchanger comprises a first flow channel and a second flow channel which are isolated from each other and in thermal connection, the water inlet of the first standby main pipeline and the water inlet of the first-stage heat exchange assembly are connected with a water outlet of the first flow channel of the second heat exchanger, and the water inlet of the second standby main pipeline and the water inlet of the last-stage water-cooled condenser are connected with a water outlet of the second flow channel of the second heat exchanger. The second standby main pipeline is connected with each of the second pipelines via at least two second bypass branches, the at least two second bypass branches are in parallel, at least one fourth on-off valve is arranged on each of the second bypass branches, and at least one fifth on-off valve is arranged on a pipeline section between a pair of adjacent second bypass branches of each of the second pipelines; or, the second standby main pipeline is connected with each of the second pipelines via at least one second bypass branch, at least one fourth on-off valve is arranged on each of the second bypass branches, and at least one fifth on-off valve is arranged on each of the second pipelines and on both sides of one of the second bypass branches; The third pipeline and the fourth pipeline are also provided with fifth on-off valves, and a sixth on-off valve is arranged on a pipeline section of the second standby main pipeline, upstream of the first-stage second bypass branch and downstream of the last-stage second bypass branch. The second standby main pipeline is connected with each of the second pipelines via two second bypass branches; each of the second pipelines is provided with three fifth on-off valves, two of the three fifth on-off valves are arranged between corresponding two second bypass branches, and the remaining one of the three fifth on-off valves is arranged between the second bypass branch and the preceding-stage water-cooled condenser; The second standby main pipeline is provided with a sixth on-off valve on a pipeline section between adjacent two second bypass branches. Each of the second bypass branches is provided with two fourth on-off valves. The second heat exchanger comprises a first flow channel and a second flow channel which are isolated from each other and in thermal connection, the water inlet of the first standby main pipeline and the water inlet of the first-stage heat exchange assembly are connected with a water outlet of the first flow channel of the second heat exchanger, and the water inlet of the second standby main pipeline and the water inlet of the last-stage water-cooled condenser are connected with a water outlet of the second flow channel of the second heat exchanger.

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