Magnetic suspension centrifugal water chilling unit with liquid supplied by barrel pump and control method

Abstract

The invention relates to a barrel pump liquid supply magnetic suspension centrifugal water chilling unit and a control method. A low-pressure circulation barrel is arranged in the water chilling unit, and working fluorine pumps in one-to-one correspondence with evaporators are arranged in the water chilling unit. The operation load of the magnetic suspension refrigeration compressor is adjusted according to the relation between the real-time suction pressure P of the water chilling unit and the target pressure set value P0, so that the refrigerating capacity of the water chilling unit is matched with the load of the use side; and when the refrigerating capacity of the water chilling unit is not matched with the load of the use side to cause liquid level fluctuation in the low-pressure circulating barrel, the operation load of the magnetic suspension refrigeration compressor and the operation frequency of the working fluorine pump are cooperatively regulated and controlled to maintain the liquid level stability of the low-pressure circulating barrel. Multi-stage protection logic is provided for the liquid level of the low-pressure circulation barrel, frequent starting and stopping of the magnetic suspension refrigeration compressor caused by frequent triggering of liquid level alarm can be avoided, the service life of equipment is prolonged, liquid impact on the magnetic suspension refrigeration compressor caused by too high liquid level control can be avoided, and fluorine pump cavitation caused by too low liquid level can be avoided.

Description

Technical Field

[0001] The invention relates to a magnetic levitation centrifugal water chiller with liquid supplied by a barrel pump and a control method thereof, belonging to the technical field of magnetic levitation centrifugal water chillers. Background Art

[0002] The barrel pump liquid supply refrigeration system uses a fluorine pump to force circulation multiple times of liquid supply, with the advantages of high heat exchange efficiency, large liquid supply head, and the ability to supply liquid to multiple evaporators at the same time. It is widely used in large cold storage, large air conditioning, food processing and chemical production and other fields.

[0003] At present, the conventional screw or oil centrifugal unit barrel pump liquid supply system contains refrigeration oil. Since the refrigeration oil in the low-pressure circulation barrel is concentrated in the upper layer of the refrigerant and fluctuates greatly with the refrigerant liquid level, the oil return problem of the barrel pump liquid supply system has always been a design difficulty and focus. Inevitably, some refrigeration oil enters the end of the evaporator with the fluorine pump, affecting heat transfer and refrigeration energy efficiency.

[0004] Meanwhile, magnetic levitation centrifugal refrigeration technology has made significant progress in recent years and is widely used in the chiller sector. The core advantage of magnetic levitation centrifugal chillers lies in their compressors' use of magnetic bearing technology, which enables contactless, oil-free suspension of the rotor. This results in completely oil-free operation, extremely low friction losses, smooth operation, low noise, and a wide adjustment range.

[0005] Therefore, there is an urgent need to innovatively combine barrel pump liquid supply technology with oil-free magnetic levitation compression technology to meet the efficient cooling needs of magnetic levitation centrifugal chillers in large-scale cooling scenarios. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention provides a magnetic levitation centrifugal chiller with a barrel pump supply and a control method. Combining the advantages of the oil-free design of the magnetic levitation compressor with the barrel pump supply, the chiller significantly outperforms traditional oil-containing barrel pump refrigeration systems in terms of energy efficiency. Multi-level protection logic is provided for the liquid level in the low-pressure circulating barrel. This not only prevents frequent triggering of liquid level alarms that would cause frequent starts and stops of the magnetic levitation refrigeration compressor, thus extending the life of the equipment, but also prevents liquid hammer in the magnetic levitation refrigeration compressor caused by excessively high liquid levels, and cavitation in the fluorine pump caused by excessively low liquid levels.

[0007] The technical solution of the present invention is:

[0008] On the one hand, the present invention provides a magnetic levitation centrifugal chiller with liquid supplied by a barrel pump, comprising a magnetic levitation refrigeration compressor, a condenser and a low-pressure circulation barrel connected in sequence, the low-pressure circulation barrel is also connected to an evaporation component on the use side, the evaporation component includes an evaporator, a working fluorine pump and a standby fluorine pump, and the working fluorine pump and the evaporator are arranged in a one-to-one correspondence; the liquid refrigerant in the low-pressure circulation barrel is transported to the evaporator through the fluorine pump group.

[0009] On the other hand, the present invention also provides a control method for the above-mentioned magnetic levitation centrifugal chiller with liquid supply by a barrel pump, comprising:

[0010] The operating load of the magnetic levitation refrigeration compressor is adjusted according to the relationship between the real-time suction pressure P of the magnetic levitation centrifugal chiller and the target pressure setting value P0, so that the cooling capacity of the chiller matches the cooling load on the user side;

[0011] When the cooling capacity of the chiller does not match the cooling load on the user side, causing the liquid level in the low-pressure circulation barrel to fluctuate, the operating load of the magnetic levitation refrigeration compressor and the operating frequency of the working fluorine pump are coordinated and regulated to maintain the stability of the liquid level in the low-pressure circulation barrel.

[0012] Preferably, according to the present invention, the operating load of the magnetic suspension refrigeration compressor is adjusted according to the relationship between the real-time suction pressure P of the magnetic suspension centrifugal chiller and the target pressure setting value P0, so that the cooling capacity of the chiller matches the cooling load on the user side; comprising:

[0013] When the cooling load on the user side decreases, the real-time suction pressure P is less than the target pressure setting value P0, and the magnetic suspension refrigeration compressor operates at reduced load, so that the cooling capacity of the chiller matches the load on the user side;

[0014] When the cooling load on the user side increases, the real-time suction pressure P is greater than the target pressure setting value P0, and the magnetic suspension refrigeration compressor runs under load, so that the cooling capacity of the chiller matches the load on the user side.

[0015] Preferably, according to the present invention, the frequency of the magnetic levitation refrigeration compressor is adjusted by PID so that the real-time suction pressure P is close to the target pressure setting value P0, that is, the temperature of the refrigerant in the low-pressure circulation barrel is close to the saturation temperature T0 corresponding to the target pressure P0, and the sensor for detecting the real-time suction pressure P is installed on the suction pipeline of the magnetic levitation refrigeration compressor or on the top of the low-pressure circulation barrel.

[0016] According to a preferred embodiment of the present invention, when the cooling capacity of the chiller does not match the cooling load on the user side, it will cause the liquid level in the low-pressure circulation barrel to fluctuate, including:

[0017] When the load on the user side is greater than the cooling capacity of the chiller, the liquid level in the low-pressure circulation barrel will drop.

[0018] When the load on the user side is less than the cooling capacity of the chiller, the liquid level in the low-pressure circulation barrel will rise.

[0019] Preferably, according to the present invention, the coordinated regulation of the operating load of the magnetic levitation refrigeration compressor and the operating frequency of the working fluorine pump to maintain the liquid level stability of the low-pressure circulation barrel includes:

[0020] The maximum liquid level allowed for normal operation of the low-pressure circulation tank is H max , the lowest liquid level is H min , the actual liquid level is H, the pre-adjusted lower limit of the liquid level is H1, and the second pre-adjusted upper limit of the liquid level is H3;

[0021] When H≤H min When H>H1, the PID controller adjusts the frequency of the magnetic suspension refrigeration compressor to make the real-time suction pressure P close to the target pressure setting value P0, the working fluorine pump stops running, and a low liquid level alarm is issued; when H>H1, the low liquid level alarm stops;

[0022] When H min When H≤H1, PID adjusts the frequency of the magnetic suspension refrigeration compressor to make the real-time suction pressure P close to the target pressure setting value P0, and the working fluorine pump is set at the lowest frequency f min run;

[0023] When H1<H≤H3, the magnetic suspension refrigeration compressor continues to run, and the PID adjusts the operating frequency of the working fluorine pump so that the temperature of the evaporator environment is close to the target temperature T s ;

[0024] When H3<H≤H max When the magnetic suspension refrigeration compressor is running at reduced load, the operating frequency of the working fluorine pump is increased;

[0025] When H>H max When the high liquid level alarm is triggered, the magnetic suspension refrigeration compressor stops, and the fluorine pump continues to operate at the highest frequency f max During operation, the liquid level gradually decreases. When the actual liquid level drops to H<H2, the high liquid level alarm stops and the magnetic suspension refrigeration compressor restarts.

[0026] Preferably, according to the present invention, when H1<H≤H3, the magnetic suspension refrigeration compressor continues to operate, including:

[0027] The low-pressure circulation barrel is also provided with a liquid level gauge, and a liquid level switch is provided in parallel with the liquid level gauge; when H1<H≤H2, H2 represents the first pre-adjusted liquid level upper limit, and H2<H3, PID adjusts the frequency of the magnetic suspension refrigeration compressor so that the real-time suction pressure P is close to the target pressure setting value P0;

[0028] When H2<H≤H3, the magnetic levitation refrigeration compressor operates with reduced load, and the minimum operating load is not less than the high energy efficiency minimum load.

[0029] According to the preferred embodiment of the present invention, when H3<H≤H max When the magnetic suspension refrigeration compressor is running at reduced load, the operating frequency of the working fluorine pump is increased; specifically:

[0030] The magnetic suspension refrigeration compressor operates at high energy efficiency and minimum load, and all working fluorine pumps operate at the highest frequency f max Keep running.

[0031] According to the preferred embodiment of the present invention, the operating frequency of the fluorine pump is adjusted so that the temperature of the environment where the evaporator is located is close to the target temperature T s ,include:

[0032] The chiller consists of N evaporators, and the temperature of the environment where the i-th or j-th evaporator is located is T i or T j , i or j is any integer value from 1 to N;

[0033] During the cooling process of the environment where the evaporator is located:

[0034] |T i -T j |>ΔT max When ΔT max Indicates the maximum acceptable temperature difference between different areas on the user side; for min{T i ,T j The corresponding working fluorine pump operates at a reduced frequency;

[0035] |T i -T j |≤ΔT min When ΔT min Indicates the minimum warning value of the temperature difference between different areas on the user side; PID adjusts the operating frequency of the working fluorine pump;

[0036] During the stabilization of the ambient temperature of the evaporator: adjust the fluorine pump frequency through PID to make T i and T j Close to T s .

[0037] According to the preferred embodiment of the present invention, when the actual liquid level H in the low-pressure circulation barrel is greater than or equal to H b When H max <H b , H b Indicates the high liquid level protection value, which triggers the high liquid level protection shutdown, the magnetic suspension refrigeration compressor stops running, and all working fluorine pumps run at the highest frequency f max Keep running.

[0038] The beneficial effects of the present invention are:

[0039] The present invention provides a magnetic levitation centrifugal chiller with liquid supply by a barrel pump and a control method. The chiller combines the advantages of the oil-free design of the magnetic levitation compressor and the liquid supply by a barrel pump, and the energy efficiency ratio of the chiller is significantly better than that of the traditional unit. A multi-level protection logic is provided for the liquid level of the low-pressure circulation barrel, which can not only avoid the frequent triggering of the liquid level alarm and the frequent start and stop of the magnetic levitation refrigeration compressor, thereby extending the life of the equipment, but also avoid the liquid hammer on the magnetic levitation refrigeration compressor caused by excessively high liquid level control, and the cavitation of the fluorine pump caused by excessively low liquid level. In addition, a working fluorine pump is provided on the user side to supply liquid to the evaporator on demand, and a spare fluorine pump is designed as a redundant design. By adjusting the operating frequency of the working fluorine pump, the temperature difference between the refrigeration areas on the user side is greatly reduced, making the temperature distribution more uniform. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a structural schematic diagram of a magnetic levitation centrifugal chiller with liquid supplied by a barrel pump provided by the present invention.

[0041] For example, 1. Evaporator, 2. Working fluorine pump, 3. Standby fluorine pump, 4. Magnetic levitation refrigeration compressor, 5. Low-pressure circulation barrel, 6. Condenser, 7. Liquid level gauge, 8. Liquid level switch. DETAILED DESCRIPTION

[0042] Several embodiments of the present application will be disclosed below with diagrams to clearly and completely describe the technical solution of the present invention, which constitute a part of the present application. The drawings in the specification are used to provide a further understanding of the present invention. The schematic embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0043] It should be noted that the terms "first", "second" and similar terms used in this application do not indicate any order, quantity or importance, but are only used to distinguish different components. In addition, in various embodiments of the present disclosure, the same or similar reference numerals represent the same or similar components.

[0044] In the present invention, unless otherwise specified or limited, the terms "connection" and "fixation" should be understood in a broad sense. For example, "connection" can refer to a fixed connection, a detachable connection, or an integral connection, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0045] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in this field can implement it. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0046] Example 1

[0047] This embodiment provides a magnetic suspension centrifugal chiller with a barrel pump supplying liquid, such as Figure 1 As shown, it includes a magnetic levitation refrigeration compressor 4, a condenser 6 and a low-pressure circulation barrel 5 connected in sequence. The low-pressure circulation barrel 5 is also connected to the evaporation component on the use side. The evaporation component includes an evaporator 1, a working fluorine pump 2 and a standby fluorine pump 3, and the working fluorine pump 2 is arranged in a one-to-one correspondence with the evaporator 1; the working fluorine pump 2 adjusts the liquid supply to the evaporator 1 by adjusting the operating frequency; the gas refrigerant above the low-pressure circulation barrel 5 is sucked and compressed by the magnetic levitation refrigeration compressor 4, enters the condenser 6, condenses into liquid refrigerant, and is then transported to the low-pressure circulation barrel 5; the liquid refrigerant in the low-pressure circulation barrel 5 is transported to the evaporator 1 through the fluorine pump group.

[0048] Example 2

[0049] This embodiment provides a control method for the magnetic levitation centrifugal chiller with a barrel pump supplying liquid as described in Example 1, including:

[0050] The operating load of the magnetic suspension refrigeration compressor 4 is adjusted according to the relationship between the real-time suction pressure P of the magnetic suspension centrifugal chiller and the target pressure setting value P0, so that the cooling capacity of the chiller matches the cooling load on the user side;

[0051] When the cooling capacity of the chiller does not match the cooling load on the user side, causing the liquid level in the low-pressure circulation barrel 5 to fluctuate, the operating load of the magnetic levitation refrigeration compressor 4 and the operating frequency of the working fluorine pump 2 are coordinated and regulated to maintain the liquid level in the low-pressure circulation barrel 5 stable.

[0052] The form of the evaporator 1 is not limited to a cold radiator, an air cooler or a flooded evaporator. Different forms of evaporators have different control details, but the core control method is the same as above.

[0053] Example 3

[0054] This embodiment provides a control method for a magnetic levitation centrifugal chiller supplied with liquid by a barrel pump. The difference from the second embodiment is that:

[0055] The operation load of the magnetic suspension refrigeration compressor 4 is adjusted according to the relationship between the real-time suction pressure P of the magnetic suspension centrifugal chiller and the target pressure setting value P0, so that the cooling capacity of the chiller matches the cooling load on the user side; including:

[0056] When the cooling load on the user side decreases, the real-time suction pressure P is less than the target pressure setting value P0, and the magnetic suspension refrigeration compressor 4 operates at reduced load, so that the cooling capacity of the chiller matches the load on the user side;

[0057] When the cooling load on the user side increases, the real-time suction pressure P is greater than the target pressure setting value P0, and the magnetic suspension refrigeration compressor 4 is loaded and operated, so that the cooling capacity of the chiller matches the load on the user side.

[0058] Example 4

[0059] This embodiment provides a control method for a magnetic levitation centrifugal chiller with a barrel pump supplying liquid. The difference from the embodiment 3 is that:

[0060] The frequency of the magnetic levitation refrigeration compressor 4 is adjusted by PID so that the real-time suction pressure P is close to the target pressure setting value P0, that is, the temperature of the refrigerant in the low-pressure circulation barrel 5 is close to the saturation temperature T0 corresponding to the target pressure P0. The sensor for detecting the real-time suction pressure P is installed on the suction pipeline of the magnetic levitation refrigeration compressor 4 or on the top of the low-pressure circulation barrel 5.

[0061] The target temperature of the environment where evaporator group 1 is located is T S The target temperature of the refrigerant in the low-pressure circulation barrel 5 is T0, which is the temperature corresponding to the saturation pressure P0; the heat exchange temperature difference between the target temperature of the refrigerant in the low-pressure circulation barrel 5 and the environment where the evaporator 1 group is located is represented by ΔT, ΔT = T S -T0. To ensure good cooling effect and economy of the refrigeration system, ΔT is usually set at around 5°C.

[0062] Example 5

[0063] This embodiment provides a control method for a magnetic levitation centrifugal chiller supplied with liquid by a barrel pump. The difference from the second embodiment is that:

[0064] When the cooling capacity of the chiller does not match the cooling load on the user side, it will cause the liquid level in the low-pressure circulation barrel 5 to fluctuate, including:

[0065] When the load on the user side is greater than the cooling capacity of the chiller, the liquid level in the low-pressure circulation barrel 5 will drop.

[0066] When the load on the user side is less than the cooling capacity of the chiller, the liquid level in the low-pressure circulation barrel 5 will rise.

[0067] The low-pressure circulation barrel 5 has a large volume, which can greatly alleviate the fluctuation of the liquid level in the low-pressure circulation barrel 5 when the user side load does not match the refrigeration capacity of the unit, avoid frequent triggering of the liquid level alarm and causing frequent start and stop of the magnetic levitation refrigeration compressor 4 and the fluorine pump, and extend the life of the equipment.

[0068] Example 6

[0069] This embodiment provides a control method for a magnetic levitation centrifugal chiller supplied with liquid by a barrel pump. The difference from the second embodiment is that:

[0070] The coordinated regulation of the operating load of the magnetic suspension refrigeration compressor 4 and the operating frequency of the working fluorine pump 2 to maintain the liquid level stability of the low-pressure circulation barrel 5 includes:

[0071] The low-pressure circulation barrel 5 is also provided with a liquid level gauge 7, and the liquid level gauge 7 is provided with a liquid level switch 8 in parallel; the maximum liquid level allowed for normal operation of the low-pressure circulation barrel 5 is H max , the lowest liquid level is H min , the actual liquid level is H, the pre-adjusted lower limit of the liquid level is H1, and the second pre-adjusted upper limit of the liquid level is H3;

[0072] When H≤H min When the working fluorine pump 2 has the risk of cavitation, the PID adjusts the frequency of the magnetic suspension refrigeration compressor 4 so that the real-time suction pressure P is close to the target pressure setting value P0, the working fluorine pump 2 stops running, and a low liquid level alarm is issued; the purpose is to increase the liquid level of the low-pressure circulation barrel 5. When H>H1, the low liquid level alarm stops;

[0073] When H min When H≤H1, PID adjusts the frequency of the magnetic suspension refrigeration compressor 4 so that the real-time suction pressure P is close to the target pressure setting value P0, and the working fluorine pump 2 is set at the lowest frequency f min Operation; minimum frequency f min The purpose is to ensure the minimum cooling capacity of the working fluorine pump 2 while raising the liquid level of the low-pressure circulation barrel 5.

[0074] When H1<H≤H3, the magnetic suspension refrigeration compressor 4 continues to operate, and the PID adjusts the operating frequency of the working fluorine pump 2 so that the temperature of the environment where the evaporator 1 is located is close to the target temperature T s ;

[0075] When H3<H≤H max When the magnetic suspension refrigeration compressor 4 is running at reduced load, the operating frequency of the working fluorine pump 2 is increased;

[0076] When H>H max When the magnetic suspension refrigeration compressor 4 has the risk of sucking liquid, a high liquid level alarm is issued, the magnetic suspension refrigeration compressor 4 is shut down, and the working fluorine pump 2 continues to operate at the highest frequency f max During operation, the liquid level gradually decreases. When the actual liquid level drops to H<H2, the high liquid level alarm stops and the magnetic suspension refrigeration compressor 4 restarts.

[0077] In addition, when any one of the working fluorine pumps 2 fails, the standby fluorine pump 3 is started and controlled using the control method of the failed working fluorine pump 2 .

[0078] Example 7

[0079] This embodiment provides a control method for a magnetic levitation centrifugal chiller with a barrel pump supplying liquid. The difference from the embodiment 6 is that:

[0080] When H1<H≤H3, the magnetic suspension refrigeration compressor 4 continues to operate, and the PID adjusts the operating frequency of the working fluorine pump 2 so that the temperature of the environment where the evaporator 1 is located is close to the target temperature T s ;include:

[0081] When H1<H≤H2, H2 represents the first pre-adjusted liquid level upper limit, and H2<H3, PID adjusts the frequency of the magnetic suspension refrigeration compressor 4 so that the real-time suction pressure P is close to the target pressure setting value P0; PID adjusts the operating frequency of the working fluorine pump 2 so that the temperature of the environment where the evaporator 1 is located is close to the target temperature T s ;

[0082] When H2<H≤H3, the magnetic levitation refrigeration compressor 4 operates at a reduced load, and the minimum operating load is not less than the high-efficiency minimum load, thereby maintaining the high refrigeration energy efficiency of the magnetic levitation refrigeration compressor 4. The high-efficiency minimum load of the magnetic levitation centrifugal chiller varies according to the design of the magnetic levitation centrifugal chiller and is generally around 30%. The PID adjusts the operating frequency of the working fluorine pump 2 so that the temperature of the environment where the evaporator 1 is located is close to the target temperature T s .

[0083] Example 8

[0084] This embodiment provides a control method for a magnetic levitation centrifugal chiller with a barrel pump supplying liquid. The difference from the embodiment 6 is that:

[0085] When H3<H≤H max When the magnetic suspension refrigeration compressor 4 is running at reduced load, the operating frequency of the working fluorine pump 2 is increased; specifically:

[0086] The magnetic suspension refrigeration compressor 4 operates at a high energy efficiency and minimum load, and all working fluorine pumps 2 operate at the highest frequency f max Continue to operate. To maintain high cooling energy efficiency of the chiller, avoid entering a low-load, low-efficiency operating state.

[0087] Example 9

[0088] This embodiment provides a control method for a magnetic levitation centrifugal chiller with a barrel pump supplying liquid. The difference from the embodiment 6 is that:

[0089] The operating frequency of the working fluorine pump 2 is adjusted so that the temperature of the environment where the evaporator 1 is located is close to the target temperature T s ,include:

[0090] The chiller includes N evaporators 1, and the temperature of the environment where the i-th or j-th evaporator 1 is located is T i or T j , i or j is any integer value from 1 to N;

[0091] During the cooling process of the environment where evaporator 1 is located, the cooling load on the user side fluctuates greatly, such as during the loading and unloading stages of the cold storage.

[0092] |T i -T j |>ΔT max When ΔT max Indicates the maximum acceptable temperature difference between different areas on the user side; for min{T i ,T j The corresponding working fluorine pump 2 is operated at a reduced frequency; in this case, manual intervention is introduced to ensure the temperature consistency of different areas where the evaporators 1 are located, and PID adjustment is not used temporarily.

[0093] It should be noted that for large-scale cold places with high requirements for temperature uniformity, the above design is carried out to avoid excessive differences in temperature drops in different areas during the cooling process, resulting in uneven temperature distribution.

[0094] |T i -T j |≤ΔT min When ΔT min Indicates the minimum warning value of the temperature difference between different areas on the user side; PID adjusts the operating frequency of the working fluorine pump 2; ΔT min and ΔT max The design can avoid frequent switching of PID regulation.

[0095] During the process of evaporator 1’s ambient temperature being stable, the cooling load fluctuation on the user side is small, such as the cold storage stage in the cold storage; the fluorine pump frequency is adjusted by PID to make T i and T j Close to T s ; T and T j Close to T s It can be understood as: T i =T s ±0.5℃, T j =T s ±0.5℃; an independent closed-loop PID is set for the evaporator 1 circuit corresponding to each fluorine pump.

[0096] Example 10

[0097] This embodiment provides a control method for a magnetic levitation centrifugal chiller with a barrel pump supplying liquid. The difference from the embodiment 6 is that:

[0098] Due to reasons such as liquid level sensor failure, when H>H max When the high liquid level alarm is not triggered, the magnetic suspension refrigeration compressor 4 continues to run and the liquid level continues to rise. In order to avoid the above situation, when the actual liquid level H in the low pressure circulation barrel 5 is greater than or equal to H b When H max <H b , H b Indicates high liquid level protection value, then trigger the liquid level switch 8, perform high liquid level protection shutdown, magnetic suspension refrigeration compressor 4 stops running, all working fluorine pumps 2 at the highest frequency f max Continue to run. If the high liquid level protection shutdown occurs, the cause of the fault must be checked on site and then manually reset.

[0099] The foregoing description shows and describes preferred embodiments of the present application. However, as previously mentioned, it should be understood that the present application is not limited to the form disclosed herein and should not be construed as excluding other embodiments. Rather, the present application may be used in various other combinations, modifications, and environments, and may be modified within the contemplation of the present invention through the teachings above or through techniques or knowledge in the relevant field. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present application shall be within the scope of protection of the appended claims.

Claims

1. A magnetic levitation centrifugal chiller with a barrel pump supplying liquid, characterized in that: It includes a magnetic levitation refrigeration compressor, a condenser and a low-pressure circulation barrel connected in sequence. The low-pressure circulation barrel is also connected to the evaporation component on the use side. The evaporation component includes an evaporator, a working fluorine pump and a standby fluorine pump, and the working fluorine pump and the evaporator are arranged in a one-to-one correspondence; the liquid refrigerant in the low-pressure circulation barrel is transported to the evaporator through the fluorine pump group.

2. The control method of the chiller according to claim 1, characterized in that: include: The operating load of the magnetic levitation refrigeration compressor is adjusted according to the relationship between the real-time suction pressure P of the magnetic levitation centrifugal chiller and the target pressure setting value P0, so that the cooling capacity of the chiller matches the cooling load on the user side; When the cooling capacity of the chiller does not match the cooling load on the user side, causing the liquid level in the low-pressure circulation barrel to fluctuate, the operating load of the magnetic levitation refrigeration compressor and the operating frequency of the working fluorine pump are coordinated and regulated to maintain the stability of the liquid level in the low-pressure circulation barrel.

3. The control method of the chiller according to claim 2, characterized in that: The operating load of the magnetic suspension refrigeration compressor is adjusted according to the relationship between the real-time suction pressure P of the magnetic suspension centrifugal chiller and the target pressure setting value P0, so that the cooling capacity of the chiller matches the cooling load on the user side; include: When the cooling load on the user side decreases, the real-time suction pressure P is less than the target pressure setting value P0, and the magnetic suspension refrigeration compressor operates at reduced load, so that the cooling capacity of the chiller matches the load on the user side; When the cooling load on the user side increases, the real-time suction pressure P is greater than the target pressure setting value P0, and the magnetic suspension refrigeration compressor runs under load, so that the cooling capacity of the chiller matches the load on the user side.

4. The control method of the chiller according to claim 3, characterized in that: The frequency of the magnetic levitation refrigeration compressor is adjusted by PID so that the real-time suction pressure P is close to the target pressure setting value P0, that is, the temperature of the refrigerant in the low-pressure circulation barrel is close to the saturation temperature T0 corresponding to the target pressure P0. The sensor for detecting the real-time suction pressure P is installed on the suction pipeline of the magnetic levitation refrigeration compressor or on the top of the low-pressure circulation barrel.

5. The control method of the chiller according to claim 2, characterized in that: When the cooling capacity of the chiller does not match the cooling load on the user side, it will cause the liquid level in the low-pressure circulation barrel to fluctuate, including: When the load on the user side is greater than the cooling capacity of the chiller, the liquid level in the low-pressure circulation barrel will drop. When the load on the user side is less than the cooling capacity of the chiller, the liquid level in the low-pressure circulation barrel will rise.

6. The control method of the chiller according to claim 2, characterized in that: The coordinated regulation of the operating load of the magnetic levitation refrigeration compressor and the operating frequency of the working fluorine pump to maintain the liquid level stability of the low-pressure circulation barrel includes: The maximum liquid level allowed for normal operation of the low-pressure circulation tank is H max , the lowest liquid level is H min , the actual liquid level is H, the pre-adjusted lower limit of the liquid level is H1, and the second pre-adjusted upper limit of the liquid level is H3; When H≤H min When H>H1, the PID controller adjusts the frequency of the magnetic suspension refrigeration compressor to make the real-time suction pressure P close to the target pressure setting value P0, the working fluorine pump stops running, and a low liquid level alarm is issued; when H>H1, the low liquid level alarm stops; When H min When H≤H1, PID adjusts the frequency of the magnetic suspension refrigeration compressor to make the real-time suction pressure P close to the target pressure setting value P0, and the working fluorine pump is set at the lowest frequency f min run; When H1<H≤H3, the magnetic suspension refrigeration compressor continues to run, and the PID adjusts the operating frequency of the working fluorine pump so that the temperature of the evaporator environment is close to the target temperature T s ; When H3<H≤H max When the magnetic suspension refrigeration compressor is running at reduced load, the operating frequency of the working fluorine pump is increased; When H>H max When the high liquid level alarm is triggered, the magnetic suspension refrigeration compressor stops, and the fluorine pump continues to operate at the highest frequency f max During operation, the liquid level gradually decreases. When the actual liquid level drops to H<H2, the high liquid level alarm stops and the magnetic suspension refrigeration compressor restarts.

7. The control method of the chiller according to claim 6, characterized in that: When H1<H≤H3, the magnetic suspension refrigeration compressor continues to operate, including: When H1<H≤H2, H2 represents the first pre-adjusted liquid level upper limit, and H2<H3, PID adjusts the frequency of the magnetic suspension refrigeration compressor so that the real-time suction pressure P is close to the target pressure setting value P0; When H2<H≤H3, the magnetic levitation refrigeration compressor operates with reduced load, and the minimum operating load is not less than the high energy efficiency minimum load.

8. The control method of the chiller according to claim 6, characterized in that: When H3<H≤H max When the magnetic suspension refrigeration compressor is running at reduced load, the operating frequency of the working fluorine pump is increased; specifically: The magnetic suspension refrigeration compressor operates at high energy efficiency and minimum load, and all working fluorine pumps operate at the highest frequency f max Keep running.

9. The control method for a chiller according to claim 6, characterized in that: The operating frequency of the working fluorine pump is adjusted so that the temperature of the environment where the evaporator is located is close to the target temperature T s ,include: The chiller consists of N evaporators, and the temperature of the environment where the i-th or j-th evaporator is located is T i or T j , i or j is any integer value from 1 to N; During the cooling process of the environment where the evaporator is located: |T i -T j |>ΔT max When ΔT max Indicates the maximum acceptable temperature difference between different areas on the user side; for min{T i ,T j The corresponding working fluorine pump operates at a reduced frequency; |T i -T j |≤ΔT min When ΔT min Indicates the minimum warning value of the temperature difference between different areas on the user side; PID adjusts the operating frequency of the working fluorine pump; During the stabilization of the ambient temperature of the evaporator: adjust the fluorine pump frequency through PID to make T i and T j Close to T s .

10. The control method of a chiller according to claim 6, characterized in that: When the actual liquid level in the low-pressure circulation barrel H≥H b When H max <H b , H b Indicates the high liquid level protection value, which triggers the high liquid level protection shutdown, the magnetic suspension refrigeration compressor stops running, and all working fluorine pumps run at the highest frequency f max Keep running.

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