Dual-mode cooperative control method for a cryogenic pump

Abstract

The application relates to a dual-mode cooperative control method of a cryogenic pump. The method comprises the following modes: a, operation control mode: adjusting the rotating speed of a refrigerator motor to make the temperature of a primary cold head reach a set value of 65K or 100K; when the rotating speed of the motor is reduced to the lowest limit value and the temperature of the primary cold head is still lower than the set value, a heater arranged on the primary cold head is started to compensate the temperature; b, regeneration control mode: controlling the reverse rotation of the refrigerator motor to make the pump body warm up, and meanwhile, the heater arranged on the primary cold head is started to accelerate the temperature rise of the primary cold head. The purposes include: completely replacing imported high-power heaters to realize the localization and cost reduction of core components of the cryogenic pump; eliminating the excessively large temperature difference between the primary and secondary cold heads in the regeneration process to avoid the abnormality of the equipment caused by the different temperature rises; establishing a staged temperature control mechanism, mainly taking the motor speed regulation as the operation mode and taking the heating compensation as the auxiliary mode, synchronously activating the double actions in the regeneration mode, and improving the system energy efficiency ratio.

Description

Technical Field

[0001] This invention relates to the field of cryogenic pump temperature control technology, and in particular to a dual-mode coordinated control method for cryogenic pumps. Background Technology

[0002] The cryogenic pump cools the primary (65K-100K) and secondary (10K-20K) cold heads to a low temperature using a refrigeration unit, causing gas molecules to condense on the cold surfaces to achieve vacuum pumping. Regeneration refers to the process of shutting down the refrigeration unit and heating up to room temperature to release the condensed gas. Existing regeneration technologies are mainly divided into two categories: Method A: High-power heaters are installed in both the primary and secondary cold heads, with a heater power density of 38W / cm², to accelerate heating. The drawbacks of this method are: the heaters are imported, resulting in high manufacturing costs, high failure rates, and huge energy consumption. Method B: The refrigeration unit motor is reversed to heat the cold heads. The drawbacks of this method are: the secondary heating rate is much faster than the primary, with a maximum temperature difference of 100K. This huge temperature difference can generate thermal stress that may damage the equipment structure or cause it to fail acceptance testing. Furthermore, during temperature control during operation, the motor speed needs to be reduced to achieve the primary temperature target, which may result in excessively low speed and slow heating, failing to meet the customer's production efficiency requirements. Summary of the Invention

[0003] To address the three major drawbacks of existing technologies—high cost of high-power heaters, temperature imbalance between the first and second stage cold heads during regeneration, and poor temperature control stability—this invention aims to provide a dual-mode collaborative control method. Its core objectives include: completely replacing imported high-power heaters and achieving cost reduction through the localization of core components of the cryogenic pump; eliminating excessive temperature differences between the first and second stage cold heads during regeneration, thus preventing equipment failure due to asynchronous temperature rises; and establishing a graded temperature control mechanism, with motor speed regulation as the primary operating mode and heating compensation as a secondary mode, while the regeneration mode simultaneously activates both actions to improve the system's energy efficiency ratio.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: According to one aspect of the present invention, a dual-mode coordinated control method for a cryogenic pump is provided, applicable to a cryogenic pump system including a refrigerator, a primary cold head, a secondary cold head, and a heater, comprising the following modes: a. Operation control mode: Adjust the speed of the refrigeration motor to make the temperature of the first-stage cold head reach the set value of 65K or 100K; when the motor speed drops to the minimum limit and the temperature of the first-stage cold head is still lower than the set value, start the heater set on the first-stage cold head for temperature compensation. b. Regeneration control mode: Controls the refrigerator motor to reverse so that the pump body is heated, and at the same time turns on the heater set on the first-stage cold head to accelerate the heating of the first-stage cold head.

[0005] Optionally, the power density of the heater does not exceed 7 W / cm². This low-power design significantly reduces manufacturing difficulty and cost, and facilitates domestic production.

[0006] Optionally, the minimum limit value is the minimum speed threshold required to maintain stable operation of the refrigeration unit.

[0007] Alternatively, in the operation control mode, the heater is activated only when the motor speed drops to a minimum limit and the temperature of the first-stage cold head is below a set value. This stringent condition ensures that the heater is used solely as a compensation measure after speed regulation failure.

[0008] Optionally, when the heater is started in the operation control mode, its heating power is dynamically adjusted according to the deviation between the real-time temperature of the primary cold head and the set value. This achieves rapid and stable temperature compensation and avoids overshoot.

[0009] Alternatively, the heater may be located only in the first-stage cold head. This single-stage heating design simplifies the structure, reduces costs, and avoids the potential for failure or interference with cryogenic operation that could result from installing a heater in the second-stage cold head.

[0010] Optionally, in the regenerative control mode, the motor reversal and the heater start-up are synchronized.

[0011] Alternatively, in the operation control mode, the primary cooling head temperature can be controlled by adjusting the motor speed.

[0012] Optionally, the heater's power is configured to meet only the temperature compensation requirements of the primary cold head in the operating control mode. It does not need to reach the high power levels of conventional regenerative heaters. Optionally, in the regeneration control mode, the heater is turned on so that the temperature difference between the primary and secondary cold heads is less than 10K.

[0013] The advantages of this invention are: 1. By abandoning imported high-power heaters, domestic low-power-density heaters are used only in the first-stage cold head, reducing power density by more than 82%, which significantly reduces manufacturing and maintenance costs.

[0014] 2. In regenerative mode, the motor reverses and is activated synchronously with the primary heater. The dual heat sources work together to powerfully accelerate the heating of the primary cold head, resulting in a significant temperature reduction compared to the traditional method B, effectively avoiding thermal stress damage and equipment defects.

[0015] 3. The energy-saving operation mode prioritizes speed and uses compensation as a supplementary strategy to maximize the utilization of the refrigeration cycle efficiency; the regeneration mode mainly relies on the motor reversing to heat up, supplemented by a low-power heater, and the energy consumption of a single regeneration is much lower.

[0016] 4. The low-power heater operates at a low temperature and has a low failure rate; the secondary cold head has no heater, eliminating related failure risks.

[0017] 5. The operating mode mainly relies on higher speed adjustment and rarely needs to work at the lowest speed. Therefore, the stringent requirements for the refrigeration unit to maintain ultra-low temperature and high cooling power at extremely low speeds are relaxed, which improves the manufacturing qualification rate of the refrigeration unit and reduces costs. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a flowchart illustrating the control logic of the operation control mode described in this invention. Figure 2 This is a flowchart of the regeneration control mode described in this invention. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Example 1

[0022] like Figure 1 and Figure 2 As shown, a dual-mode coordinated control method for a cryogenic pump is applied to a cryogenic pump system including a refrigerator, a primary cold head, a secondary cold head, and a heater installed only on the primary cold head, including the following modes: a. Operation control mode: Adjust the speed of the refrigeration unit motor to make the temperature of the first-stage cold head reach the set value of 65K; when the motor speed drops to the minimum limit and the temperature of the first-stage cold head is still lower than the set value, start the heater installed on the first-stage cold head for temperature compensation. b. Regeneration control mode: Controls the refrigerator motor to reverse so that the pump body is heated, and at the same time turns on the heater set on the first-stage cold head to accelerate the heating of the first-stage cold head.

[0023] The minimum limit value refers to the minimum safe speed at which the refrigeration unit can operate stably and avoid faults such as surge or poor lubrication. Its value can be obtained from the technical parameters provided by the refrigeration unit manufacturer, experimental tests, or preset according to the refrigeration unit model.

[0024] The control unit synchronously sends a motor reverse control signal and a heater start signal, with the start-up time interval between the two being less than 1 second.

[0025] In specific applications, the first-stage cold head temperature needs to be maintained at 65K, the chiller speed range is 40-120rpm, and the minimum speed is 40rpm. Only the first-stage cold head is equipped with a heater, with a heater power density of 3W / cm³ and a power of 40W.

[0026] Operating control mode: Initial speed 115 rpm, first-stage temperature 61 K, speed reduced to the minimum limit of 40 rpm, temperature rises to 64.5 K, below the set value of 65 K; due to the speed reaching the minimum limit and the temperature being too low, heater temperature compensation is performed. After 30 seconds of compensation, the temperature stabilizes at 65 K, and the second-stage cold head temperature stabilizes at 15 K. The speed priority strategy significantly reduces daily energy consumption compared to the frequent use of the heater in the traditional A method.

[0027] Regeneration control mode: Simultaneous execution of motor reversal and heater start-up, motor speed -95rpm, heater power 40W; maximum temperature difference between primary and secondary stages 8K, regeneration time shortened from 22 minutes to 14 minutes.

[0028] In this embodiment, in the operation control mode, the heater is activated only when the motor speed drops to the minimum limit and the temperature of the first-stage cold head is below the set value. This condition ensures that the heater is only used as a compensation measure after speed regulation fails.

[0029] In this embodiment, when the heater is started in the operation control mode, its heating power is dynamically adjusted according to the deviation between the real-time temperature of the primary cold head and the set value. This achieves rapid and stable temperature compensation and avoids overshoot.

[0030] In this embodiment, in the operation control mode, the temperature control of the primary cooling head is achieved by adjusting the motor speed.

[0031] In this embodiment, in the regeneration control mode, the motor reversal and the heater activation are synchronized. Upon receiving the regeneration command, the control unit simultaneously sends a motor reversal control signal and a heater activation signal.

[0032] In this embodiment, in the regeneration control mode, the heater is turned on so that the temperature difference between the first-stage cold head and the second-stage cold head is less than 10K.

[0033] In this embodiment, the heater is only located in the first-stage cold head. This single-stage heating design simplifies the structure, reduces costs, and avoids the potential for failure or interference with cryogenic operation that might result from installing a heater in the second-stage cold head.

[0034] Example 2

[0035] like Figure 1 and Figure 2As shown, a dual-mode coordinated control method for cryogenic pumps is applied to a cryogenic pump system including a refrigerator, a primary cold head, a secondary cold head, and a heater, and includes the following modes: a. Operation control mode: Adjust the speed of the refrigeration motor to make the temperature of the first-stage cold head reach the set value of 65K or 100K; when the motor speed drops to the minimum limit and the temperature of the first-stage cold head is still lower than the set value, start the heater set on the first-stage cold head for temperature compensation. b. Regeneration control mode: Controls the refrigerator motor to reverse so that the pump body is heated, and at the same time turns on the heater set on the first-stage cold head to accelerate the heating of the first-stage cold head.

[0036] The minimum limit value refers to the minimum safe speed at which the refrigeration unit can operate stably and avoid faults such as surge or poor lubrication. Its value can be obtained from the technical parameters provided by the refrigeration unit manufacturer, experimental tests, or preset according to the refrigeration unit model.

[0037] The control unit synchronously sends a motor reverse control signal and a heater start signal, with the start-up time interval between the two being less than 1 second.

[0038] For specific applications, the chiller speed range is 40-120 rpm, with a minimum limit of 40 rpm. Only one stage has a heater installed, with a heater power of 40W.

[0039] Operating mode: When a process gas leak occurs, the first-stage temperature drops sharply from 100K to 92K, and the rotation speed is already at the minimum limit of 40rpm. The heater compensates with 40W heating, and the temperature rises back to 99.8K within 6 seconds and stabilizes at 100K within 10 seconds.

[0040] Regeneration mode: The motor reverses at -95 rpm, and the first-stage heater operates at 40W power, with both operating synchronously. The maximum temperature difference during the entire regeneration process is 8.5K, and the regeneration time is 24 minutes.

[0041] In this embodiment, when the heater is started in the operation control mode, its heating power is dynamically adjusted according to the deviation between the real-time temperature of the first-stage cold head and the set value.

[0042] In this embodiment, the power configuration of the heater is only to meet the temperature compensation requirements of the first-stage cold head in the operation control mode.

[0043] In this embodiment, in the regeneration control mode, the heater is turned on so that the temperature difference between the first-stage cold head and the second-stage cold head is less than 10K.

[0044] In this embodiment, the heater is only located in the first-stage cold head. This single-stage heating design simplifies the structure, reduces costs, and avoids the potential for failure or interference with cryogenic operation that might result from installing a heater in the second-stage cold head.

[0045] Example 3

[0046] like Figure 1 and Figure 2 As shown, a dual-mode coordinated control method for cryogenic pumps is applied to a cryogenic pump system including a refrigerator, a primary cold head, a secondary cold head, and a heater, and includes the following modes: a. Operation control mode: Adjust the speed of the refrigeration motor to make the temperature of the first-stage cold head reach the set value of 65K or 100K; when the motor speed drops to the minimum limit and the temperature of the first-stage cold head is still lower than the set value, start the heater set on the first-stage cold head for temperature compensation. b. Regeneration control mode: Controls the refrigerator motor to reverse so that the pump body is heated, and at the same time turns on the heater set on the first-stage cold head to accelerate the heating of the first-stage cold head.

[0047] The minimum limit value refers to the minimum safe speed at which the refrigeration unit can operate stably and avoid faults such as surge or poor lubrication. Its value can be obtained from the technical parameters provided by the refrigeration unit manufacturer, experimental tests, or preset according to the refrigeration unit model.

[0048] The control unit synchronously sends a motor reverse control signal and a heater start signal, with the start-up time interval between the two being less than 1 second.

[0049] For specific applications, a 100K first-stage and a 15K second-stage bistable system is required. The system configuration is as follows: the chiller speed range is 40-120rpm, with a minimum limit of 40rpm. Only the first-stage cold head is equipped with a heater, and the power density is 4.5W / cm².

[0050] Operating mode: After initial cooling, the first stage temperature is about 95K. The speed drops from 115rpm to 40rpm, and the first stage temperature reaches 98.4K. After the heater compensation is activated, the first stage temperature stabilizes at 100K. The second stage cold head has no heater intervention and naturally stabilizes at 15K.

[0051] Regeneration Mode: Simultaneous motor reversal and heater startup are executed, with a motor speed of -95 rpm, heater power of 40W, and a maximum temperature difference of 6K between the first and second stages. Regeneration time is approximately 26 minutes. Compared to the traditional Method B, the regeneration time is reduced by 35%.

[0052] In this embodiment, the minimum limit value is the minimum speed threshold for maintaining stable operation of the refrigerator.

[0053] In this embodiment, in the operation control mode, the temperature control of the primary cooling head is achieved by adjusting the motor speed.

[0054] In this embodiment, the heater is only located in the first-stage cold head. This single-stage heating design simplifies the structure, reduces costs, and avoids the potential for failure or interference with cryogenic operation that might result from installing a heater in the second-stage cold head.

[0055] Supplementary explanation of the technical principles of this invention: The principle behind the effectiveness of regeneration temperature difference control: During regeneration, the primary cooling head receives two main heat sources: 1. Compression heat and frictional heat generated by the reverse refrigeration cycle driven by the motor, transferred through the refrigerant and mechanical structure; 2. Direct radiative / conductive heat from the primary heater. The simultaneous action of these two heat sources significantly increases the heat input power of the primary cooling head, thereby greatly improving its heating rate. This makes the heating rate of the primary stage as close as possible to that of the secondary stage, effectively reducing the temperature difference between them. A heater with a power density ≤7W / cm² can provide sufficient auxiliary heat power to achieve this balance.

[0056] The energy-saving basis of the speed-priority strategy: The refrigeration efficiency of the chiller is relatively high within its normal operating speed range. This method prioritizes temperature control by adjusting the speed during operation, typically at higher or medium speeds, which is more energy-efficient than using a heater for temperature compensation. The heater is only activated when the speed drops to the minimum limit and still does not meet the target, and its power is configured to be low according to the compensation needs, minimizing the use of high-energy-consuming electric heating.

[0057] Basis for determining the minimum limit: The minimum limit is the lower speed limit set to ensure the safe and reliable operation of the refrigeration unit. Too low a speed may lead to: insufficient refrigerant flow, causing a decrease in refrigeration power; and insufficient motor torque, resulting in unstable operation. This value can be obtained from the manufacturer's technical manual, through speed reduction testing under specific loads, or preset according to the refrigeration unit model.

[0058] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A dual-mode coordinated control method for a cryogenic pump, applied to a cryogenic pump system including a refrigerator, a primary cold head, a secondary cold head, and a heater, characterized in that, Includes the following modes: a. Operation control mode: Adjust the speed of the refrigeration motor to make the temperature of the first-stage cold head reach the set value of 65K or 100K; when the motor speed drops to the minimum limit and the temperature of the first-stage cold head is still lower than the set value, start the heater installed on the first-stage cold head for temperature compensation. b. Regeneration control mode: Control the refrigerator motor to reverse so that the pump body is heated, and at the same time turn on the heater set on the first-stage cold head to accelerate the heating of the first-stage cold head; The heater is only located in the first-stage cold head.

2. The method according to claim 1, characterized in that: The power density of the heater does not exceed 7 W / cm.

3. The method according to claim 1, characterized in that: The minimum limit value is the minimum speed threshold required to maintain stable operation of the refrigeration unit.

4. The method according to claim 1, characterized in that: In the operation control mode, the heater is activated only when the motor speed drops to the minimum limit and the temperature of the first-stage cold head is lower than the set value.

5. The method according to claim 4, characterized in that: When the heater is started in the operation control mode, its heating power is dynamically adjusted according to the deviation between the real-time temperature of the first-stage cold head and the set value.

6. The method according to claim 1, characterized in that: In regenerative control mode, the motor reversal and the heater start-up are synchronized.

7. The method according to claim 1, characterized in that: In the operation control mode, the temperature control of the primary cooling head is achieved by adjusting the motor speed first.

8. The method according to claim 1, characterized in that: The power configuration of the heater is only sufficient to meet the temperature compensation requirements of the primary cold head in the operation control mode.

9. The method according to claim 1, characterized in that: In regeneration control mode, the heater is turned on so that the temperature difference between the primary and secondary cold heads is less than 10K.

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