Shutdown control method and control device for large absorption heat pump

Abstract

The invention discloses a shutdown control method and control device for a large absorption heat pump, and the shutdown control method comprises the steps: respectively obtaining pressure data P1 in a generator and pressure data P2 in an absorber after the large absorption heat pump receives a shutdown instruction; calculating a difference value between the pressure data P1 and the pressure data P2 to obtain a pressure difference delta P between the generator and the absorber; adjusting the actual operation frequency of the solution pump based on the pressure difference delta P actual corresponding to the actual lift of the solution pump; when the pressure difference delta P is smaller than or equal to a preset shutdown deviation value, the solution pump is controlled to operate at a low maintenance frequency and used for providing micro-pressure guarantee for solution circulation; and after the solution pump continuously runs for a preset time at the lower maintaining frequency, the solution pump stops running. Smooth and controlled frequency reduction and shutdown of the solution pump in the shutdown process are achieved, and violent vibration and abnormal sound in the shutdown process of a large absorption heat pump are eliminated.

Description

Technical Field

[0001] This invention belongs to the field of heat pump technology, specifically relating to a shutdown control method and control device for a large-scale absorption heat pump. Background Technology

[0002] With rapid urban development, the area and amount of heating provided are continuously increasing. In response to the policy requirements of the "Air Pollution Prevention and Control Action Plan," various regions are gradually phasing out decentralized boiler rooms and instead vigorously developing centralized heating systems centered on combined heat and power (CHP) and regional heat exchange stations. Centralized heating has become the development direction of urban heating and is an effective measure for saving energy and preventing environmental pollution.

[0003] Against this backdrop, lithium bromide absorption heat pump units have shown great application potential in urban centralized heating systems due to their ability to recover and utilize low-potential heat sources (such as industrial waste heat and power plant circulating water) to produce high-temperature heat energy for heating. This technology can not only reduce the overall coal consumption of power plants and improve heating capacity, but also effectively reduce regional carbon dioxide emissions, resulting in significant economic and social benefits.

[0004] However, large absorption heat pump units used in district heating systems are generally enormous, often exceeding ten meters in length and height, posing a significant challenge to the uniformity of heat transfer within the unit. A particularly prominent issue occurs during unit shutdown: despite the design for dilution operation to reduce the solution concentration to a safe level, the temperature and pressure of the solution inside the unit remain at a high level after dilution. When the solution pump providing the circulation power suddenly stops, the circulation power disappears instantly, causing the solution in the high-pressure area to flow violently to the low-pressure area. This can trigger widespread, high-intensity vibrations in the unit, producing a loud, metallic impact sound that severely affects the user experience. Furthermore, the violent pressure fluctuations and solution impact can strain the heat exchange tubes inside the unit, potentially leading to loosening of the connections between the heat exchange tubes and the tube sheet over time, creating a risk of air leakage and affecting the unit's vacuum level and performance. Summary of the Invention

[0005] The purpose of this invention is to provide a shutdown control method and device for large-scale absorption heat pumps, aiming to overcome problems such as uneven heat transfer, unit vibration, and abnormal noise caused by pressure imbalance during shutdown. The core of this invention lies in achieving smooth, controlled frequency reduction and shutdown of the solution pump during the smooth cooling of each cylinder in the large-scale absorption heat pump shutdown process, thereby maintaining internal pressure balance and fundamentally eliminating severe vibration and abnormal noise during shutdown.

[0006] To address the aforementioned problems, a first aspect of the present invention provides a control method for shutting down a large-scale absorption heat pump. The shutdown control method includes: step S1, after the large-scale absorption heat pump receives a shutdown command, acquiring pressure data P1 inside the generator and pressure data P2 inside the absorber, respectively; step S2, calculating the difference between the pressure data P1 and the pressure data P2 to obtain the pressure difference ΔP between the generator and the absorber; and step S3, based on the pressure difference ΔP corresponding to the actual head of the solution pump... 实 Adjust the actual operating frequency of the solution pump, wherein the pressure difference ΔP corresponding to the actual head of the solution pump is... 实 The actual pressure difference between the generator and the absorber is the sum of the pressure difference ΔP and the static pressure difference ΔP. 静 The sum, i.e. ΔP 实 =ΔP+ΔP 静 The static pressure difference is determined by the height difference between the generator and the absorber; in step S4, when the pressure difference ΔP is less than or equal to the preset shutdown deviation value, the solution pump is controlled to operate at a lower maintenance frequency to provide micro-pressure protection for solution circulation; in step S5, after the solution pump has been running at the lower maintenance frequency for a predetermined time, the solution pump is stopped.

[0007] Further, step S1 specifically includes: after receiving a shutdown command, the large absorption heat pump measures the internal pressure of the generator in real time through the generator pressure sensor to obtain pressure data P1, and at the same time, measures the internal pressure of the absorber in real time through the absorber pressure sensor to obtain pressure data P2.

[0008] Further, step S3 includes: step S31, based on the pressure difference ΔP corresponding to the actual head of the solution pump. 实 Step S32: Calculate the actual operating frequency of the solution pump; Step S33: Based on the calculated actual operating frequency of the solution pump, send a control signal to the solution pump to adjust the actual operating frequency of the solution pump.

[0009] Furthermore, given that the pressure difference corresponding to the actual head of the solution pump, the rated frequency of the solution pump, the rated head of the solution pump, and the pressure difference corresponding to the rated head of the solution pump are all determined, the actual operating frequency of the solution pump is calculated using the following formula: Among them, H 实 H represents the actual head of the solution pump. 额 ΔP is the rated head of the solution pump. 实 ΔP is the pressure difference corresponding to the actual head of the solution pump. 额 f is the pressure difference corresponding to the rated head of the solution pump. 实 f is the actual operating frequency of the solution pump.额 This is the rated frequency of the solution pump.

[0010] Furthermore, the height difference between the generator and the absorber ranges from 5 to 15 meters; the pressure difference ΔP between the generator and the absorber ranges from 0 to 35 kPa, in order to suppress operational oscillations when the large absorption heat pump is shut down.

[0011] Furthermore, in step S5, the predetermined time ranges from 1 to 10 minutes.

[0012] According to another aspect of the present invention, the present invention also provides a control device for the shutdown process of a large-scale absorption heat pump, the control device comprising: a generator pressure sensor for acquiring pressure data P1 inside the generator after the large-scale absorption heat pump receives a shutdown command; an absorber pressure sensor for acquiring pressure data P2 inside the absorber after the large-scale absorption heat pump receives a shutdown command; and a controller electrically connected to the generator pressure sensor, the absorber pressure sensor, and the solution pump, configured to: receive the pressure data P1 and the pressure data P2, and calculate the pressure difference ΔP between them; and calculate the pressure difference ΔP based on the actual head of the solution pump. 实 Calculate the actual operating frequency of the solution pump, where the pressure difference ΔP corresponds to the actual head of the solution pump. 实 The actual pressure difference between the generator and the absorber is the sum of the pressure difference ΔP and the static pressure difference ΔP. 静 The sum, i.e. ΔP 实 =ΔP+ΔP 静 The static pressure difference is determined by the height difference between the generator and the absorber; based on the calculated actual operating frequency of the solution pump, a frequency control signal is sent to the solution pump to adjust the actual operating frequency of the solution pump; after the solution pump has been running at a lower maintenance frequency for a predetermined time, the power supply to the solution pump is cut off to stop its operation; wherein, when the pressure difference ΔP is less than or equal to a preset shutdown deviation value, the solution pump is controlled to run at the lower maintenance frequency to provide micro-pressure protection for solution circulation.

[0013] Furthermore, given that the pressure difference corresponding to the actual head of the solution pump, the rated frequency of the solution pump, the rated head of the solution pump, and the pressure difference corresponding to the rated head of the solution pump are all determined, the controller calculates the actual operating frequency of the solution pump using the following formula: Among them, H 实 H represents the actual head of the solution pump. 额 ΔP is the rated head of the solution pump. 实 ΔP is the pressure difference corresponding to the actual head of the solution pump.额 f is the pressure difference corresponding to the rated head of the solution pump. 实 f is the actual operating frequency of the solution pump. 额 This is the rated frequency of the solution pump.

[0014] Furthermore, the height difference between the generator and the absorber ranges from 5 to 15 meters; the pressure difference ΔP between the generator and the absorber ranges from 0 to 35 kPa, in order to suppress operational oscillations when the large absorption heat pump is shut down.

[0015] Furthermore, the predetermined time ranges from 1 to 10 minutes.

[0016] This invention provides a control method for smooth shutdown of a large absorption heat pump. The basic principle is as follows: after the large heat pump receives a shutdown command, the pressure values ​​inside the generator and absorber are monitored in real time. Based on the pressure difference between them, the actual operating frequency of the solution pump is dynamically adjusted to complete a gradual shutdown process from "active adjustment" to "micro-pressure maintenance" and finally to "safe stop". This maintains the internal pressure balance of the unit and ensures equipment safety.

[0017] (III) Beneficial Effects The above-described technical solution of the present invention has the following beneficial technical effects: 1. By smoothly reducing the frequency of the solution pump instead of abruptly stopping it, the instantaneous loss of circulating power is avoided, thereby fundamentally preventing the huge, knocking-like impact sound and unit vibration caused by the violent flow of high-pressure solution to low-pressure parts.

[0018] 2. This method effectively maintains the heat transfer uniformity inside the unit during shutdown, avoids the "uneven heating and cooling" and "thermal expansion and contraction" phenomena of different metal materials in the same cylinder caused by solution backflow, eliminates the resulting internal structural stress and tension, protects key connection parts such as heat exchange tubes and tube sheets, prevents them from loosening due to long-term vibration, and extends the service life of the unit.

[0019] 3. By providing a "micro-pressure protection" phase, a smooth transition of internal operating conditions of large absorption heat pump units is ensured, reducing the risk of operational failures caused by uncontrolled shutdown processes leading to seal failure of key connection parts of the unit, thereby improving the reliability and safety of the entire heat pump system.

[0020] 4. Feedback control is based on real-time pressure difference, and frequency calculation is performed using the similarity law of pumps. This makes the control process accurate and adaptable to different system operating conditions and equipment parameters, with strong versatility and stable control effect. Attached Figure Description

[0021] Figure 1This is a flowchart of a shutdown control method for a large absorption heat pump according to an embodiment of the present invention; Figure 2 This is a structural diagram of a large absorption heat pump solution loop in a specific embodiment of the present invention; Figure 3 This is a graph showing the relationship between the pressure difference of the solution pump and the operating frequency in a specific embodiment of the present invention; Figure 4 This is a graph showing the relationship between the pressure difference at the operating point a of the solution pump and the operating frequency in a specific embodiment of the present invention.

[0022] Figure label: A: Generator; B: Absorber; C: Solution pump; D: Throttling device; T1: Generator pressure sensor; T2: Absorber pressure sensor; 1: Dilute solution inlet; 2: Concentrated solution outlet; 3: External heat source interface; 4: Generator pressure guide hole; 5: Concentrated solution inlet; 6: Dilute solution outlet; 7: Heated medium interface; 8: Absorber pressure guide hole. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and the accompanying drawings. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention.

[0024] Before describing the present invention, the derivation process of the relevant formulas needs to be explained.

[0025] The similarity rate of the water pumps is: H1 / H2=(n1 / n2) 2 Where H1 and H2 are different pump heads, and n1 and n2 are the pump motor speeds corresponding to the pump heads H1 and H2, respectively; the relationship between pump motor speed and frequency is: n = 60f / q, where n is the pump motor speed, 60 is the number of seconds per minute, f is the frequency, and q is the number of pole pairs of the rotating magnetic field of the pump motor. Based on the pump similarity rate and the relationship between pump motor speed and frequency, the relationship between the pump head and operating frequency of the same pump motor can be calculated. Substituting the relationship between pump motor speed and frequency into the pump similarity rate, we get: H1 / H2 = [(60f1 / p) / (60f2 / p)] 2 =(f1 / f2) 2 Furthermore, since H1 / H2 = ΔP1 / ΔP2, we can conclude that: H1 / H2 = ΔP1 / ΔP2 = (f1 / f2) 2 Wherein, when the pump head is H1, the actual pressure difference corresponding to the pump is ΔP1, and the actual operating frequency corresponding to the pump is f1; when the pump head is H2, the actual pressure difference corresponding to the pump is ΔP2, and the actual operating frequency corresponding to the pump is f2.

[0026] Figure 1 This is a flowchart of a shutdown control method for a large absorption heat pump according to an embodiment of the present invention. The following is in conjunction with... Figures 2 to 4 To illustrate the specific implementation process of the present invention, in some embodiments, the shutdown control method includes: step S1, after the large absorption heat pump receives a shutdown command, acquiring pressure data P1 inside generator A and pressure data P2 inside absorber B respectively; step S2, calculating the difference between pressure data P1 and pressure data P2 to obtain the pressure difference ΔP between generator A and absorber B; step S3, based on the pressure difference ΔP corresponding to the actual head of solution pump C. 实 Adjust the operating frequency of solution pump C, where the pressure difference ΔP corresponds to the actual head of solution pump C. 实 The actual pressure difference between the generator and the absorber is the sum of the pressure difference ΔP and the static pressure difference ΔP. 静 The sum, i.e. ΔP 实 =ΔP+ΔP 静 The static pressure difference is determined by the height difference between generator A and absorber B; in step S4, when the pressure difference ΔP is less than or equal to the preset shutdown deviation value, the solution pump C is controlled to run at a lower maintenance frequency to provide micro-pressure protection for solution circulation; in step S5, after the solution pump C runs continuously at a lower maintenance frequency for 1-10 minutes, the solution pump C is stopped.

[0027] Reference Figure 2 , Figure 2 This is a structural diagram of a large-scale absorption heat pump solution loop according to a specific embodiment of the present invention. The large-scale absorption heat pump solution loop structure includes a generator A, an absorber B, a solution pump C, a throttling device D, a generator pressure sensor T1, and an absorber pressure sensor T2. Generator A is provided with a dilute solution inlet 1, a concentrated solution outlet 2, an external heat source interface 3, and a generator pressure guide hole 4. Absorber B is provided with a concentrated solution inlet 5, a dilute solution outlet 6, a heated medium interface 7, and an absorber pressure guide hole 8. The concentrated solution outlet 2 of generator A is connected to the inlet of throttling device D, and the outlet of throttling device D is connected to the concentrated solution inlet 5 of absorber B. The dilute solution outlet 6 of absorber B is connected to the inlet of solution pump C, and the outlet of solution pump C is connected to the dilute solution inlet 1 of generator A via a check valve. Generator pressure sensor T1 is connected to generator A via a pressure guide pipe, and absorber pressure sensor T2 is connected to absorber B via a pressure guide pipe. The solution in generator A is concentrated by an external heat source, becoming a concentrated liquid. This concentrated solution is then depressurized by a throttling device D and enters absorber B. In absorber B, the concentrated solution absorbs refrigerant vapor and becomes a dilute liquid. The dilute liquid in absorber B is drawn by solution pump C, its pressure increased, and it flows through a check valve into generator A. In absorber A, it again absorbs heat from the external heat source and is concentrated back into a concentrated solution.

[0028] In some embodiments, in step S1, after the large absorption heat pump receives a shutdown command, the external heat source for generator A is interrupted, and the unit enters a dilution operation process. The dilution process has low requirements for controlling the liquid level in generator A, and its purpose is to cool, depressurize, and reduce the concentration of generator A, and further reduce the concentration of the concentrated solution in generator A. At this time, generator A is still in a high temperature and high pressure state, while absorber B is in a low temperature and low pressure state. The internal pressure values ​​of generator A and absorber B are measured in real time by generator pressure sensor T1 and absorber pressure sensor T2, thereby obtaining the internal pressure data P1 of generator A and the internal pressure data P2 of absorber B. In step S2, based on the internal pressure data P1 of generator A and the internal pressure data P2 of absorber B, the difference between pressure data P1 and pressure data P2 is calculated to obtain the pressure difference ΔP between the generator and absorber.

[0029] In some embodiments, step S3 includes: step S31, based on the pressure difference ΔP corresponding to the actual head of the solution pump C. 实 Step S32: Calculate the actual operating frequency of solution pump C; Step S33: Based on the calculated actual operating frequency of solution pump C, send a control signal to solution pump C to adjust the operating frequency of solution pump C.

[0030] In some embodiments, the height difference between generator A and absorber B ranges from 5 to 15 meters, and the pressure difference ΔP between generator A and absorber B ranges from 0 to 35 kPa, to suppress operational oscillations during dilution in large absorption heat pumps. The height difference of 5 to 15 meters is set to achieve an optimal balance between system stability, equipment efficiency, and economy. The lower limit of 5 meters is specifically to differentiate smaller units, which are smaller in size and easier to shut down stably; while the upper limit of 15 meters matches the maximum design load of the system, preventing the need to increase unit strength due to pursuing excessively high head, which would lead to a significant increase in cost. Furthermore, the mechanical strength of the unit is limited, as it cannot support units exceeding 15 meters in height. This defines the safe and efficient operating range of the pump. The pressure difference ΔP between generator A and absorber B, ranging from 0 to 35 kPa, is determined based on the saturation pressure difference corresponding to the operating temperatures of generator A and absorber B. The lower limit of this range prevents the control system from becoming overly sensitive due to excessively small deviations, prevents the pump frequency from oscillating frequently due to minor pressure fluctuations, and protects the equipment's lifespan. The upper limit (35 kPa) prevents the system from becoming sluggish due to excessive deviations, ensuring pressure control accuracy and energy-saving effects. This "buffer zone" allows the system to operate smoothly and save energy effectively.

[0031] In some embodiments, given that the pressure difference corresponding to the actual head of the solution pump C, the rated frequency of the solution pump C, the rated head of the solution pump C, and the pressure difference corresponding to the rated head of the solution pump C are all determined, the actual operating frequency of the solution pump C is calculated using the following formula: Among them, H 实 H represents the actual head of the solution pump C. 额 ΔP is the rated head of solution pump C. 实 ΔP represents the pressure difference corresponding to the actual head of solution pump C. 额 f is the pressure difference corresponding to the rated head of solution pump C. 实 f is the actual operating frequency of solution pump C. 额 The rated frequency of solution pump C is given.

[0032] In some embodiments, in step S5, the value of the predetermined time ranges from 1 to 10 minutes.

[0033] In one specific embodiment, generator A is located above absorber B at a higher position, with a height difference of 10 meters between generator A and absorber B, i.e., a static pressure difference of 98 kPa (ΔP) between generator A and absorber B. 静 During operation of a large absorption heat pump unit, generator A is heated by an external heat source, raising its temperature to 130°C and concentration to 63%, corresponding to a high-concentration solution saturation pressure of 34.5 kPa. Absorber B has a temperature of 50°C and a concentration of 56%, with a lower saturation pressure of approximately 1.9 kPa. The operating pressure difference between generator A and absorber B is 32.6 kPa (ΔP). Adding the hydrostatic pressure difference of the liquid column, the actual pressure difference between generator A and absorber B (i.e., the pressure difference ΔP corresponding to the actual head of solution pump C) is calculated. 实 The pressure difference is 130.6 kPa. To ensure normal solution circulation under such a large pressure difference, sufficient power is required. Therefore, a solution pump C with a head > 13.3 mH2O is needed to provide sufficient lifting capacity to deliver the solution from absorber B to the higher generator A. In this specific embodiment, the preset shutdown deviation value of ΔP is 5 kPa, meaning that when ΔP ≤ 5 kPa, the solution pump operates at a lower maintenance frequency. The rated frequency f of the selected solution pump C is... 额 For 50Hz, the corresponding rated head H 额 The value is 15.3 mH2O. The pressure conversion relationship is 1 kgf / cm² = 98 kPa = 10 mH2O, therefore the rated head H is... 额 The corresponding pressure difference ΔP 额 The pressure is 15.3 × 9.8 = 150 kPa, which is the head H. 额 At the rated frequency f 额The corresponding pressure difference is 150 kPa. The actual pressure difference ΔP between generator A and absorber B can be calculated using the formula below. 实 The frequency f corresponding to multiple values 实 The specific formula is as follows: Among them, H 实 H represents the actual head of the solution pump C. 额 ΔP is the rated head of solution pump C. 实 ΔP represents the pressure difference corresponding to the actual head of solution pump C. 额 f is the pressure difference corresponding to the rated head of solution pump C. 实 f is the actual operating frequency of solution pump C. 额 Let be the rated frequency of solution pump C. From this, the pressure difference ΔP corresponding to the actual head of solution pump C can be obtained. 实 (The actual pressure difference between the generator and the absorber) and the actual operating frequency f of the solution pump C 实 The corresponding relationship table is used to send control signals to solution pump C to adjust the actual operating frequency of solution pump C. For details, please refer to Table 1.

[0034] Furthermore, based on the data in Table 1, a curve can be plotted showing the relationship between the pressure difference corresponding to the actual head of solution pump C and the actual operating frequency of solution pump C. Figure 3 , Figure 3 This is a graph showing the relationship between the pressure difference and operating frequency of the solution pump in a specific embodiment of the invention, providing precise engineering basis for variable frequency control and energy-saving optimization. It experimentally verifies that the pressure difference and frequency (speed) of the solution pump follow a square law relationship, thus serving as a "map" for system control: when the process requires a specific pressure difference, the controller can quickly match the optimal operating frequency accordingly. Simultaneously, it also serves as a benchmark for performance monitoring and fault diagnosis; if the actual operating point deviates from this curve, it can promptly warn of system anomalies (such as blockage or wear), ensuring that the system always operates in a highly efficient and reliable state.

[0035] Table 1 When the external heat source is interrupted, the pressure difference between generator A and absorber B is at its maximum. At this time, solution pump C operates at 50Hz. As solution pump C feeds the low-temperature solution from absorber B into generator A, the high-temperature solution in generator A mixes with a portion of the low-temperature solution, causing the temperature and pressure of the solution in generator A to gradually decrease. Solution pump C then operates according to... Figure 3The operating frequency is adjusted in real time based on the relationship curve between the pressure difference and the operating frequency. The output head is precisely matched to the pressure difference between generator A and absorber B, thereby reducing the temperature of the generator solution at an appropriate rate. After a period of operation, the temperature of generator A decreases, and the pressure also decreases accordingly. The actual pressure difference between generator A and absorber B (ΔP) 实 The pressure dropped to 103 kPa (specifically, ΔP). 实 =ΔP+ΔP 静 , where ΔP 静 When the pressure difference is 98 kPa and ΔP = 5 kPa, there is almost only a height difference (static pressure difference ΔP) between generator A and absorber B. 静 The pressure difference is caused by the liquid level in the heat pump C, but not by the liquid level in the heat pump chamber. However, it is still necessary to maintain a low pressure for solution circulation. Therefore, in actual operation, a low-frequency threshold can be preset for the solution pump C to ensure solution flow. For example, in this embodiment, after the solution pump C frequency is reduced to 20Hz (20Hz is the preset low-frequency threshold for solution pump C), the solution pump C continues to run at 20Hz to ensure continuous solution circulation and prevent backflow of solution from the high-pressure and high-temperature parts of the generator to the low-pressure parts. The solution pump C runs continuously for 1 minute. After the running time is reached, the solution pump C stops operating, and the entire heat pump completes the shutdown process. (At this time, 20Hz is the preset low-frequency threshold for solution pump C). In one specific embodiment, see Figure 4 , Figure 4 This is a graph showing the relationship between the pressure difference at the operating point a of the solution pump and the operating frequency in a specific embodiment of the present invention. The rated frequency f of the selected solution pump C is shown below. 额 For 50Hz, the corresponding rated head H 额 The value is 15.3 mH2O. The pressure conversion relationship is 1 kgf / cm² = 98 kPa = 10 mH2O, therefore the rated head H is... 额 The corresponding pressure difference ΔP 额 The pressure is 15.3 × 9.8 = 150 kPa, which is the head H. 额 At the rated frequency, this corresponds to a pressure difference of 150 kPa. The actual pressure difference ΔP between generator A and absorber B... 实 When the pressure is 128 kPa (i.e., when the solution pump C is at operating point a), the specific operating frequency f of the solution pump C is... 实 The following calculation can be used to obtain the result: 128 / 150 = (f 实 / 50) 2 The operating frequency f of solution pump C 实 =46.18Hz.

[0036] This invention also provides a shutdown control device for a large absorption heat pump. See [link to related document]. Figures 1 to 4In some embodiments, the control device for the solution pump in the large absorption heat pump includes: a generator pressure sensor T1, used to acquire pressure data P1 inside generator A after the large absorption heat pump receives a shutdown command; an absorber pressure sensor T2, used to acquire pressure data P2 inside absorber B after the large absorption heat pump receives a shutdown command; and a controller, electrically connected to the generator pressure sensor T1, the absorber pressure sensor T2, and the solution pump C, configured to: receive pressure data P1 and pressure data P2, calculate the pressure difference ΔP between them; and calculate the pressure difference ΔP based on the actual head of the solution pump C. 实 Calculate the actual operating frequency of solution pump C, where the pressure difference ΔP corresponds to the actual head of solution pump C. 实 The actual pressure difference between generator A and absorber B is the sum of the pressure difference ΔP and the static pressure difference ΔP. 静 The sum, i.e. ΔP 实 =ΔP+ΔP 静 The static pressure difference is determined by the height difference between generator A and absorber B. Based on the calculated actual operating frequency of solution pump C, the controller sends a frequency control signal to solution pump C to adjust its operating frequency. After the solution pump runs at a low maintenance frequency for 1-10 minutes, the power supply to the solution pump is cut off to stop it. When the pressure difference ΔP is less than or equal to the preset shutdown deviation value, solution pump C is controlled to run at a low maintenance frequency to provide micro-pressure protection for solution circulation.

[0037] In some embodiments, given that the pressure difference corresponding to the actual head of solution pump C, the rated frequency of solution pump C, the rated head of solution pump C, and the pressure difference corresponding to the rated head of solution pump C are all determined, the controller calculates the actual operating frequency of solution pump C using the following formula: Among them, H 实 H represents the actual head of the solution pump C. 额 ΔP is the rated head of solution pump C. 实 ΔP represents the pressure difference corresponding to the actual head of solution pump C. 额 f is the pressure difference corresponding to the rated head of solution pump C. 实 f is the actual operating frequency of solution pump C. 额 The rated frequency of solution pump C is given.

[0038] In some embodiments, the height difference between generator A and absorber B ranges from 5 to 15 meters, and the pressure difference ΔP between generator A and absorber B ranges from 0 to 35 kPa, in order to suppress operational oscillations when a large absorption heat pump is shut down.

[0039] For the principles, implementation details, and beneficial effects of this shutdown control device, please refer to the preceding text. Figures 1 to 4 The description of the shutdown control method for large absorption heat pumps shown is not repeated here.

[0040] It should be understood that the term "and / or" in this article is merely a description of the relationship between related objects. For example, A and / or B indicates that there are three possible relationships: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this article indicates that the related objects before and after it are in an "or" relationship.

[0041] It should be noted that the sequence number of each step in this embodiment does not represent a limitation on the execution order of each step.

[0042] It should be understood that the specific embodiments described above are merely illustrative or explanatory of the principles of the invention and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of the invention should be included within the protection scope of the invention. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

Claims

1. A shutdown control method for a large absorption heat pump, characterized in that, include: Step S1: After the large absorption heat pump receives the shutdown command, acquire the pressure data P1 inside the generator and the pressure data P2 inside the absorber respectively. Step S2: Calculate the difference between the pressure data P1 and the pressure data P2 to obtain the pressure difference ΔP between the generator and the absorber; Step S3, based on the pressure difference ΔP corresponding to the actual head of the solution pump. 实 Adjust the actual operating frequency of the solution pump, wherein the pressure difference ΔP corresponding to the actual head of the solution pump is... 实 The actual pressure difference between the generator and the absorber is the sum of the pressure difference ΔP and the static pressure difference ΔP. 静 The sum, i.e. ΔP 实 =ΔP+ΔP 静 The static pressure difference is determined by the height difference between the generator and the absorber; Step S4: When the pressure difference ΔP is less than or equal to the preset shutdown deviation value, the solution pump is controlled to operate at a lower maintenance frequency to provide micro-pressure protection for solution circulation. Step S5: After the solution pump has been running at the lower maintenance frequency for a predetermined period of time, the solution pump is stopped.

2. The shutdown control method according to claim 1, wherein, Step S1 specifically includes: After receiving a shutdown command, the large absorption heat pump measures the internal pressure of the generator in real time through the generator pressure sensor to obtain pressure data P1. At the same time, it measures the internal pressure of the absorber in real time through the absorber pressure sensor to obtain pressure data P2.

3. The shutdown control method according to claim 2, wherein, Step S3 includes: Step S31, based on the pressure difference ΔP corresponding to the actual head of the solution pump. 实 Calculate the actual operating frequency of the solution pump; Step S32: Based on the calculated actual operating frequency of the solution pump, a control signal is sent to the solution pump to adjust the actual operating frequency of the solution pump.

4. The shutdown control method according to any one of claims 1 to 3, wherein, Given that the pressure difference corresponding to the actual head of the solution pump, the rated frequency of the solution pump, the rated head of the solution pump, and the pressure difference corresponding to the rated head of the solution pump are all determined, the actual operating frequency of the solution pump is calculated using the following formula: Among them, H 实 H represents the actual head of the solution pump. 额 ΔP is the rated head of the solution pump. 实 ΔP is the pressure difference corresponding to the actual head of the solution pump. 额 f is the pressure difference corresponding to the rated head of the solution pump. 实 f is the actual operating frequency of the solution pump. 额 This is the rated frequency of the solution pump.

5. The shutdown control method according to any one of claims 1 to 4, wherein, The height difference between the generator and the absorber ranges from 5 to 15 meters; the pressure difference ΔP between the generator and the absorber ranges from 0 to 35 kPa, which is used to suppress operational oscillations when the large absorption heat pump is shut down.

6. The shutdown control method according to any one of claims 1 to 5, wherein, In step S5, the predetermined time ranges from 1 to 10 minutes.

7. A shutdown control device for a large absorption heat pump, characterized in that, include: A generator pressure sensor is used to acquire the internal pressure data P1 of the generator after a large absorption heat pump receives a shutdown command. An absorber pressure sensor is used to acquire the internal pressure data P2 of the absorber after a large absorption heat pump receives a shutdown command. The controller, electrically connected to the generator pressure sensor, the absorber pressure sensor, and the solution pump, is configured as follows: Receive the pressure data P1 and pressure data P2, and calculate the pressure difference ΔP between them; Based on the pressure difference ΔP corresponding to the actual head of the solution pump 实 Calculate the actual operating frequency of the solution pump, where the pressure difference ΔP corresponds to the actual head of the solution pump. 实 The actual pressure difference between the generator and the absorber is the sum of the pressure difference ΔP and the static pressure difference ΔP. 静 The sum, i.e. ΔP 实 =ΔP+ΔP 静 The static pressure difference is determined by the height difference between the generator and the absorber; Based on the calculated actual operating frequency of the solution pump, a frequency control signal is sent to the solution pump to adjust the actual operating frequency of the solution pump; After the solution pump has been running at a low sustaining frequency for a predetermined period of time, the power supply to the solution pump is cut off to stop its operation. Specifically, when the pressure difference ΔP is less than or equal to the preset shutdown deviation value, the solution pump is controlled to operate at the lower maintenance frequency to provide micro-pressure protection for solution circulation.

8. The shutdown control device according to claim 7, wherein, Given that the pressure difference corresponding to the actual head of the solution pump, the rated frequency of the solution pump, the rated head of the solution pump, and the pressure difference corresponding to the rated head of the solution pump are all determined, the controller calculates the actual operating frequency of the solution pump using the following formula: Among them, H 实 H represents the actual head of the solution pump. 额 ΔP is the rated head of the solution pump. 实 ΔP is the pressure difference corresponding to the actual head of the solution pump. 额 f is the pressure difference corresponding to the rated head of the solution pump. 实 f is the actual operating frequency of the solution pump. 额 This is the rated frequency of the solution pump.

9. The shutdown control device according to claim 7 or 8, wherein, The height difference between the generator and the absorber ranges from 5 to 15 meters; the pressure difference ΔP between the generator and the absorber ranges from 0 to 35 kPa, which is used to suppress operational oscillations when the large absorption heat pump is shut down.

10. The shutdown control device according to any one of claims 7 to 9, wherein the predetermined time ranges from 1 to 10 minutes.

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