Isolated Detection System and Detection Method for Liquid Nitrogen Liquid Level Height Based on Differential Pressure Calculation

Abstract

This application relates to an isolated detection system and detection method for the liquid nitrogen liquid level height based on differential pressure calculation. By simulating and calculating the air pressure height difference between the liquid bottom and the liquid surface of the liquid nitrogen tank, a differential pressure signal between the return air pipe 3 and the gas measuring pipe is obtained, and the air pressure height difference between the liquid bottom and the liquid surface of the liquid nitrogen tank is calculated based on the pressure formula, so as to obtain the height position of the liquid nitrogen in the liquid nitrogen tank and perform liquid replenishment control. The differential pressure measurement system is completely isolated from the outside of the liquid nitrogen tank, eliminating the extremely harsh environment inside the tank and ensuring the long-term stable operation of the measurement equipment; the high-precision differential pressure measurement unit can accurately measure the liquid nitrogen height within the range of 1 millimeter, with high precision; only by inserting the gas measuring pipe to the lowest position of the liquid level, the detection of the corresponding range can be automatically matched without adding any circuit, and the measuring range is adjustable; it is suitable for the liquid level measurement of any sealed or unsealed tank or even a tankless situation, avoiding the short circuit of internal electronic equipment and being struck by lightning.

Description

Technical Field

[0001] The present disclosure relates to the technical field of cryogenic storage, and in particular, to a differential pressure calculation-based nitrogen liquid level height isolation detection system, a differential pressure calculation-based nitrogen liquid level height isolation detection method, and a nitrogen height detection device. Background Art

[0002] Liquid nitrogen is liquefied from low-temperature nitrogen and rapidly volatilizes into nitrogen at room temperature. Its boiling point is -196°C, so it is generally stored in a tank made of heat-insulating material called a liquid nitrogen tank. The liquid nitrogen in the liquid nitrogen tank has certain dangerous properties, such as low temperature, asphyxiation, and easy expansion and explosion in a closed environment.

[0003] Liquid nitrogen is very important in industry, medicine, and food applications. In fact, in some industries, the application of liquid nitrogen has become indispensable.

[0004] However, there are still the following difficulties in the use of liquid nitrogen in the prior art:

[0005] 1. Liquid nitrogen is stored in a liquid nitrogen tank. However, the temperature of the liquid nitrogen in the tank remains at -196°C for a long time, and at the same time, the tank is filled with liquid nitrogen and nitrogen, which brings difficulties to the measurement of the liquid level height of the liquid nitrogen in the tank. If the amount of liquid nitrogen stored in the tank is small and needs to be refilled, improper control of the filling amount will cause overflow.

[0006] 2. Traditional liquid level measurement sensors cannot withstand low temperatures. When put into liquid nitrogen, due to the low-temperature effect, the sensors will be directly scrapped. Another type called a capacitance liquid level gauge can measure the liquid level height at low temperatures, but it generally has disadvantages such as large errors, low liquid level accuracy, poor resolution, high cost, limited range (0 - 1m), and fixed range (cannot be modified after customization).

[0007] 3. In addition, general liquid level gauges are deployed internally, with inaccurate measurement accuracy, high cost, and limited measured liquid level height. Summary of the Invention

[0008] To solve the above problems, the present application proposes a differential pressure calculation-based nitrogen liquid level height isolation detection system, a differential pressure calculation-based nitrogen liquid level height isolation detection method, and a nitrogen height detection device.

[0009] On the one hand, the present application proposes a differential pressure calculation-based nitrogen liquid level height isolation detection system, including:

[0010] A liquid nitrogen tank 1 for storing liquid nitrogen;

[0011] A gas measuring tube 2 provided on the liquid nitrogen tank 1, one end of which is close to the bottom of the liquid nitrogen tank 1, and the other end is connected to the a end of an air pump 6 through a first pipeline 5;

[0012] The return air pipe 3 is arranged on the liquid nitrogen tank 1, one end of which is close to the top of the liquid nitrogen tank 1, and the other end is connected to the b end of the air pump 6 through the second pipeline 4;

[0013] The air pump 6 is used to form a closed-loop gas path with the return air pipe 3 and the gas measuring pipe 2, and pump the gas in the liquid nitrogen tank 1 to the gas measuring pipe 2 through the return air pipe 3; at the same time, corresponding air pressure signals are respectively provided to the differential pressure measuring unit 7 from its a end and b end;

[0014] The differential pressure measuring unit 7 is used to collect the air pressure signals at the a end and the b end and perform differential pressure calculation, simulate the air pressure height difference between the bottom and the liquid surface of the liquid nitrogen tank 1, obtain the differential pressure value between the return air pipe 3 and the gas measuring pipe 2 and send it to the processing unit;

[0015] The processing unit is used to control the start and stop of the air pump 6 and send corresponding pump signals to the air pump 6; and, according to the differential pressure signal measured by the differential pressure measuring unit 7, calculate the air pressure height difference between the bottom and the liquid surface of the liquid nitrogen tank 1 according to the pressure formula, and output the corresponding liquid level height result to the host computer;

[0016] The air pump 6 and the differential pressure measuring unit 7 are respectively electrically connected to the processing unit;

[0017] The processing unit is communicatively connected to the host computer.

[0018] As an optional implementation scheme of the present application, optionally, the differential pressure measuring unit 7 adopts a differential pressure sensor.

[0019] As an optional implementation scheme of the present application, optionally, the differential pressure measuring unit 7 includes:

[0020] The differential pressure acquisition interface is used to collect the air pressure signals at the a end and the b end;

[0021] The 24-bit ADC conversion module is used to perform digital-to-analog conversion on the air pressure signal;

[0022] The processor MCU is used to perform differential pressure calculation on the air pressure signals at the a end and the b end to obtain the corresponding differential pressure value;

[0023] The RS485 communication interface is used to communicate with the processing unit and send the differential pressure signal to the processing unit.

[0024] As an optional implementation scheme of the present application, optionally, it further includes:

[0025] The liquid nitrogen pump 9 is used to replenish liquid nitrogen to the liquid nitrogen tank 1 to a preset liquid level height;

[0026] The liquid nitrogen pump 9 is electrically connected to the processing unit.

[0027] As an alternative embodiment of the present application, optionally, the processing unit is further configured to:

[0028] After the host computer receives the liquid level height result, check the current working attributes of the liquid nitrogen tank 1;

[0029] Identify the preset liquid level height of the liquid nitrogen in the current liquid nitrogen tank 1 from the working attributes of the liquid nitrogen tank 1;

[0030] Determine whether the liquid level height result meets the preset liquid level height:

[0031] If it does not meet, send a liquid injection notice to the processing unit; otherwise, give up;

[0032] After the processing unit receives the liquid injection notice, generate a corresponding liquid nitrogen pump signal and control the start of the liquid nitrogen pump 9:

[0033] Continuously monitor the liquid level height result until the liquid nitrogen supplemented in the liquid nitrogen tank 1 reaches the preset liquid level height, and then turn off the liquid nitrogen pump 9;

[0034] Loop through the above steps.

[0035] As an alternative embodiment of the present application, optionally, the time when the differential pressure measurement unit 7 collects the air pressure signals at ends a and b and performs differential pressure calculation is:

[0036] The air pump 6 is started, and the gas in the liquid nitrogen tank 1 is pumped through the return air pipe 3 to the gas measuring pipe 2 until bubbles start to appear at the bottom of the gas measuring pipe 2.

[0037] As an alternative embodiment of the present application, optionally, it further includes:

[0038] An infrared detector 8, provided on one side of the bottom of the liquid nitrogen tank 1, is configured to monitor the bubble infrared detection signal reflected by the infrared light from the bubbles and send it to the processing unit when bubbles start to appear at the bottom of the gas measuring pipe 2;

[0039] The infrared detector 8 is electrically connected to the processing unit.

[0040] As an alternative embodiment of the present application, optionally, the processing unit is further configured to:

[0041] Record the time t when the bubble infrared detection signal is received;

[0042] Collect the differential pressure value calculated by the differential pressure measurement unit 7 at the time t and calculate the corresponding liquid level height result.

[0043] On the other hand, the present application proposes an isolated detection method for the liquid nitrogen liquid level height based on differential pressure calculation, which is implemented based on the isolated detection system for the liquid nitrogen liquid level height based on differential pressure calculation, and includes the following steps:

[0044] System initialization;

[0045] The processing unit controls the air pump 6 to start, and pumps the gas in the liquid nitrogen tank 1 to the gas measuring tube 2 through the return air pipe 3, and bubbles start to appear at the bottom of the gas measuring tube 2;

[0046] When bubbles start to appear at the bottom of the gas measuring tube 2, the infrared detector 8 monitors the bubble infrared detection signal reflected by the bubbles to the infrared light and sends it to the processing unit;

[0047] The differential pressure measurement unit 7 collects the air pressure signals at the a end and the b end and performs differential pressure calculation to simulate the air pressure height difference between the liquid bottom and the liquid surface of the liquid nitrogen tank 1, obtains the differential pressure value between the return air pipe 3 and the gas measuring tube 2 and sends it to the processing unit;

[0048] The processing unit records the time t when the bubble infrared detection signal is received, collects the differential pressure value calculated by the differential pressure measurement unit 7 at the time t, calculates the corresponding liquid level height result, and outputs the corresponding liquid level height result to the upper computer;

[0049] After receiving the liquid level height result, the upper computer checks the current working attribute of the liquid nitrogen tank 1;

[0050] From the working attributes of the liquid nitrogen tank 1, identify the preset liquid level height of the liquid nitrogen in the current liquid nitrogen tank 1;

[0051] Judge whether the liquid level height result meets the preset liquid level height:

[0052] If not, send a liquid injection notice to the processing unit; otherwise, give up;

[0053] After receiving the liquid injection notice, the processing unit generates a corresponding liquid nitrogen pump signal and controls the liquid nitrogen pump 9 to start:

[0054] Continuously monitor the liquid level height result until the liquid nitrogen supplemented in the liquid nitrogen tank 1 reaches the preset liquid level height, and then turn off the liquid nitrogen pump 9;

[0055] Loop to execute the above steps.

[0056] On the other hand, the present application also proposes a liquid nitrogen height detection device, including:

[0057] A processor;

[0058] A memory for storing instructions executable by the processor;

[0059] Among them, when the processor is configured to execute the executable instructions, the described isolation type detection method for the liquid nitrogen liquid level height based on differential pressure calculation is implemented.

[0060] Technical effects of the present invention:

[0061] This application obtains the differential pressure signal between the return air pipe 3 and the gas measuring pipe 2 by simulating and calculating the air pressure height difference between the bottom and the liquid surface of the liquid nitrogen tank 1, and calculates the air pressure height difference between the bottom and the liquid surface of the liquid nitrogen tank 1 based on the pressure formula, so as to obtain the height position of the liquid nitrogen in the liquid nitrogen tank 1 and perform liquid supplement control, and has the following advantages:

[0062] 1. Good stability: The differential pressure measurement unit, the processing unit, the air pump, etc. are completely isolated from the outside of the liquid nitrogen tank, eliminating the extremely harsh environment inside the tank body and ensuring the long-term stable operation of the measuring equipment.

[0063] 2. High precision: Different from the traditional contact type capacitance acquisition equipment, which has the disadvantages of low precision, low repeatability, and low resolution, the high-precision differential pressure measurement unit can accurately measure the liquid nitrogen height within the range of 1 millimeter.

[0064] 3. Adjustable range: Just insert the gas measuring pipe to the lowest liquid level, and it can automatically match the detection within the corresponding range without adding any circuits.

[0065] 4. Strong adaptability: It can adapt to the liquid level measurement of any sealed or unsealed tank body or even without a tank body, and can also adapt to the liquid level measurement of liquid ammonia, liquid hydrogen, liquid helium, liquid argon, etc., as well as various corrosive liquids. Avoid short circuits of internal electronic equipment and being struck by lightning.

[0066] According to the following detailed description of the exemplary embodiments with reference to the accompanying drawings, other features and aspects of the present disclosure will become clear. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] The accompanying drawings included in the specification and constituting a part of the specification show the exemplary embodiments, features and aspects of the present disclosure together with the specification, and are used to explain the principles of the present disclosure.

[0068] Figure 1 It is shown as a schematic diagram of the implementation process of the present invention;

[0069] Figure 2 It is shown as an application system of the present invention;

[0070] Figure 3 It is shown as a schematic diagram of the composition structure of the present invention;

[0071] Figure 4 It is shown as an application schematic diagram of the liquid nitrogen height detection device of the present invention DETAILED DESCRIPTION OF THE EMBODIMENTS

[0072] Various exemplary embodiments, features, and aspects of the present disclosure will be described in detail below with reference to the accompanying drawings. Like reference numerals in the drawings denote elements having the same or similar functions. Although various aspects of the embodiments are shown in the drawings, the drawings are not necessarily drawn to scale unless otherwise specified.

[0073] As used herein, the term "exemplary" means "serving as an example, embodiment, or illustration". Any embodiment described herein as "exemplary" is not necessarily to be construed as superior or better than other embodiments.

[0074] In addition, for a better description of the present disclosure, numerous specific details are given in the following detailed description. Those skilled in the art should understand that the present disclosure can be implemented without some specific details. In some instances, well-known means, elements, and circuits have not been described in detail so as to highlight the gist of the present disclosure.

[0075] In this application, "liquid nitrogen" is used as the medium for height calculation. In practical applications, media such as liquid hydrogen and liquid helium can also be applied to the calculation.

[0076] Embodiment 1

[0077] As Figure 1 shown, on the one hand, the present application provides an isolation-type detection system for the liquid nitrogen liquid level height based on differential pressure calculation, including:

[0078] A liquid nitrogen tank 1 for storing liquid nitrogen;

[0079] A gas measuring tube 2 is provided on the liquid nitrogen tank 1, one end of which is close to the bottom of the liquid nitrogen tank 1, and the other end is connected to the a end of a gas pump 6 through a first pipeline 5;

[0080] A return air pipe 3 is provided on the liquid nitrogen tank 1, one end of which is close to the top of the liquid nitrogen tank 1, and the other end is connected to the b end of the gas pump 6 through a second pipeline 4;

[0081] A gas pump 6 is used to form a closed-loop gas path with the return air pipe 3 and the gas measuring tube 2, and pump the gas in the liquid nitrogen tank 1 to the gas measuring tube 2 through the return air pipe 3; at the same time, corresponding air pressure signals are respectively provided to the differential pressure measurement unit 7 from its a end and b end;

[0082] A differential pressure measurement unit 7 is used to collect the air pressure signals at the a end and the b end and perform differential pressure calculation, simulate the air pressure height difference between the liquid bottom and the liquid surface of the liquid nitrogen tank 1, obtain the pressure difference value between the return air pipe 3 and the gas measuring tube 2, and send it to the processing unit;

[0083] A processing unit is used to control the start and stop of the air pump 6 and send corresponding pump signals to the air pump 6; and, according to the pressure difference signal measured by the pressure difference measurement unit 7, calculate the air pressure height difference between the liquid bottom and the liquid surface of the liquid nitrogen tank 1 according to the pressure formula, and output the corresponding liquid level height result to the host computer;

[0084] The air pump 6 and the pressure difference measurement unit 7 are respectively electrically connected to the processing unit;

[0085] The processing unit is communicatively connected to the host computer.

[0086] In this solution, by simulating and calculating the air pressure height difference between the liquid bottom and the liquid surface of the liquid nitrogen tank 1, the pressure difference signal between the return air pipe 3 and the gas measuring pipe 2 is obtained, and the air pressure height difference between the liquid bottom and the liquid surface of the liquid nitrogen tank 1 is calculated based on the pressure formula, so as to obtain the height position of the liquid nitrogen in the liquid nitrogen tank 1 and perform liquid supplement control.

[0087] The liquid pressure calculation formula is p = ρgh.

[0088] (1) p---pressure, unit: Pascal (Pa)

[0089] (2) ρ---liquid density, unit: kilogram per cubic meter (kg / m3)

[0090] (3) g---acceleration due to gravity, g = 9.8 N / kg

[0091] (4) h---depth, unit: meter (m)

[0092] In this embodiment, the measured is the air pressure difference, which needs to be converted into the corresponding pressure difference δp, and then the corresponding depth difference is calculated. The calculation of the pressure difference δp can be performed by the processing unit according to the preset unit value (calculated by unifying the unit area because the dual interfaces of the used pressure difference sensor are of the same size).

[0093] This solution can send the detected liquid level height value to the host computer system, record the liquid level value by the system, and judge the liquid supplement height. When the liquid level is too low, the required temperature of the sample is not enough, to avoid sample deterioration, compensation is needed immediately (the system presets the liquid level height threshold).

[0094] Combined with the attached Figure 1 As shown, the devices such as the pressure difference measurement unit, the processing unit, and the air pump of this solution are completely isolated from the outside of the liquid nitrogen tank, eliminating the extremely harsh environment inside the tank body, and ensuring the long-term stable operation of the measuring equipment.

[0095] In this solution, the gas measuring tube and the gas return tube are respectively used for gas conduction. The gas measuring tube is pumped by an air pump, and the nitrogen gas in the gas return tube is pumped into the gas measuring tube and discharged from the bottom. Due to the height difference between the gas measuring tube and the gas return tube, there is a pressure difference for the air pressure at both ends (one inlet and one outlet) of the air pump ab. The liquid level height is calculated according to the pressure difference and the pressure formula.

[0096] The air pump is a diaphragm air pump. Both ends ab of the air pump are respectively connected to the pressure difference acquisition interfaces of the pressure difference measurement unit. The pressure difference acquisition interfaces have two ports at the same time, which can be respectively connected to the ab ends, measure the air pressures in the gas return tube and the gas measuring tube at the same time, and further perform digital-to-analog ADC conversion and calculation to generate corresponding differential pressure signals. After being processed by the processing unit, the differential pressure signals generate corresponding liquid nitrogen height liquid level values and are reported to the upper computer for recording and liquid supplement judgment.

[0097] In this solution, the gas return tube can adopt a rubber gas tube, and the gas measuring tube inside the liquid nitrogen tank can adopt an aluminum tube. When setting and installing, the bottoms of the two tubes only need to contact the top and bottom of the liquid nitrogen tank respectively (the installation height of the gas return tube can be installed according to the preset height, and this height can be used as a reference value for subsequent processing units to calculate the liquid level height difference).

[0098] In order to avoid the airtight contact between the gas measuring tube and the bottom of the liquid nitrogen tank, which may cause unsmooth exhaust, several V-shaped wedge-shaped openings can be set at the bottom of the gas measuring tube to facilitate exhaust.

[0099] In addition, the pressure difference is actually the difference between the liquid surface pressure and the air pressure at the air outlet at the bottom of the gas measuring tube. However, generally, there is a certain gap space and height between the bottom of the gas measuring tube and the bottom of the tank for exhaust. Therefore, for the actual liquid level height processed from the liquid level height calculated by the air pressure difference, the reserved height δh between the gas measuring tube and the inner bottom surface of the tank should also be compensated.

[0100] Therefore, δh can be pre-configured in the processing unit. After the processing unit calculates the air pressure height difference between the liquid bottom and the liquid surface of the liquid nitrogen tank 1 according to the pressure formula, add δh as the final liquid level height and then report it to the upper computer to accurately determine the liquid level height.

[0101] When in use, the processing unit outputs a pump start signal to start the air pump, pumps the nitrogen gas extracted from the gas return tube into the gas measuring tube until bubbles emerge from the bottom of the gas measuring tube (stop pumping when bubbles emerge, and the purpose of emerging bubbles is for compensation); stop the pump start signal to turn off the air pump and wait for the pipeline air pressure to stabilize; the processing unit samples the differential pressure signal between the gas return tube and the gas measuring tube in the pipeline (such as 0.01 mpa) and converts it into a pressure value; according to the pressure formula P = ρgh, the liquid nitrogen liquid level height h = P / ρg. Since the known liquid nitrogen density is 0.81 g / cm3, substitute the pressure value into the formula to output the liquid level result and report it to the upper computer.

[0102] The processing unit can be a processor such as a CPU or a single-chip microcomputer, which can be connected to the corresponding device through its own communication port and communicate with the host computer. Similarly, the host computer can also send various notification signals / instructions to the processing unit, such as the sampling control instruction manually input by the user or the instruction to perform sampling according to the preset sampling program and frequency. Just notify the processing unit to execute, and automatic sampling can be achieved. Knowing the liquid nitrogen height at the preset time point is convenient for matching the working properties of the liquid nitrogen tank.

[0103] High precision: Different from traditional contact capacitive acquisition devices with low precision, low repeatability, and low resolution, the high-precision differential pressure measurement unit can accurately measure the liquid nitrogen height within the range of 1 millimeter;

[0104] Adjustable range: Just insert the gas measuring tube into the lowest level of the liquid level, and it can automatically match the detection of the corresponding range without adding any circuits.

[0105] As described above Figure 2 As shown in the figure, as an optional implementation of the present application, optionally, the differential pressure measurement unit 7 includes:

[0106] A differential pressure acquisition interface for acquiring the air pressure signals at the a end and the b end;

[0107] A 24-bit ADC conversion module for performing digital-to-analog conversion on the air pressure signal;

[0108] A processor MCU for calculating the differential pressure of the air pressure signals at the a end and the b end to obtain the corresponding differential pressure value;

[0109] An RS485 communication interface for communicating with the processing unit and sending the differential pressure signal to the processing unit.

[0110] The differential pressure measurement unit, the processing unit, the air pump, etc. are completely isolated from the outside of the liquid nitrogen tank, eliminating the extremely harsh environment inside the tank and ensuring the long-term stable operation of the measurement equipment.

[0111] The differential pressure measurement unit 7 uses a differential pressure sensor, which has two ports and can be respectively connected to the ab ends of the air pump to simulate the acquisition of the air pressure in the return air pipe and the gas measuring pipe.

[0112] The differential pressure acquisition interface can acquire the air pressure signals at the ab ends, automatically perform differential calculation to generate the corresponding differential air pressure analog signal, and perform digital-to-analog conversion by the ADC conversion module to generate the corresponding digital signal. After further processing the converted digital signal by the processor MCU, the corresponding differential pressure value is generated and reported to the host computer through the RS485 communication interface.

[0113] The differential pressure measurement unit 7 can perform a one-time conversion on the input differential air pressure, which is convenient to apply. It can be specifically understood in combination with existing differential sensors.

[0114] In this solution, the differential sensor can also perform temperature compensation. A temperature sensor can be set in the air pump (just connect it to the processor MCU) to detect the nitrogen temperature and give corresponding differential pressure compensation values. For specific compensation, the embedded program in the processor MCU can perform automatic compensation calculations, and the administrator can input the compensation relationship between the corresponding temperature and differential pressure in advance. The processor MCU performs differential pressure compensation calculations based on the real-time monitored temperature value, and after summing the differential pressure values, sends them to the processing unit to achieve temperature compensation.

[0115] As Figure 3 shown, as an optional implementation of this application, optionally, it further includes:

[0116] A liquid nitrogen pump 9 for replenishing liquid nitrogen to the liquid nitrogen tank 1 to a preset liquid level height;

[0117] The liquid nitrogen pump 9 is electrically connected to the processing unit.

[0118] As an optional implementation of this application, optionally, the processing unit is further used for:

[0119] After the host computer receives the liquid level height result, check the current working attributes of the liquid nitrogen tank 1;

[0120] Identify the preset liquid level height of the liquid nitrogen in the current liquid nitrogen tank 1 from the working attributes of the liquid nitrogen tank 1;

[0121] Judge whether the liquid level height result meets the preset liquid level height:

[0122] If it does not meet, send a liquid injection notice to the processing unit; otherwise, give up;

[0123] After the processing unit receives the liquid injection notice, generate a corresponding liquid nitrogen pump signal and control the liquid nitrogen pump 9 to start:

[0124] Continuously monitor the liquid level height result until the liquid nitrogen in the liquid nitrogen tank 1 is replenished to the preset liquid level height, and then turn off the liquid nitrogen pump 9;

[0125] Loop and execute the above steps.

[0126] In this solution, a liquid nitrogen pump is arranged beside the liquid nitrogen tank, and the liquid nitrogen pump is controlled by the processing unit. When the host computer determines that the liquid nitrogen height in the liquid nitrogen tank is insufficient, it is determined that liquid replenishment is required. Then, the processing unit controls the liquid nitrogen pump to pump the corresponding amount of liquid nitrogen from the liquid nitrogen storage to the liquid nitrogen tank to replenish the liquid nitrogen in the liquid nitrogen tank to the preset liquid level height.

[0127] Specifically, the host computer can, according to the working attributes of the current liquid nitrogen tank, for example, if the current liquid nitrogen tank is a storage device for hospital medical sample tubes, it should reach the corresponding preset liquid level height. The host computer can manage the working states and attributes of each liquid nitrogen tank and supervise the liquid level height of each liquid nitrogen tank in the background. If the liquid nitrogen level height of the current liquid nitrogen tank is lower than the preset liquid level height value, it is determined that the current liquid nitrogen tank needs to be refilled. Thus, the host computer can send a liquid injection notice to the processing unit, and the processing unit controls the liquid nitrogen pump to start and begin to refill the liquid nitrogen tank. During the refilling process, according to the above system, units such as the air pump continue to work, perform differential pressure measurement and differential pressure calculation, and real-time feedback to the processing unit to inform the liquid level height after refilling in the liquid nitrogen tank. When the processing unit monitors that the liquid level height reaches the preset liquid level height, the liquid nitrogen pump is turned off.

[0128] Therefore, this solution can perform intelligent control of the liquid level height of the liquid nitrogen tank in the background, without manual operation and intervention, and achieve intelligent management.

[0129] As an alternative implementation of the present application, optionally, the time when the differential pressure measurement unit 7 collects the air pressure signals at the a end and the b end and performs differential pressure calculation is:

[0130] The air pump 6 is started, and the gas in the liquid nitrogen tank 1 is pumped through the return air pipe 3 to the gas measuring pipe 2 until bubbles start to emerge from the bottom of the gas measuring pipe 2.

[0131] As Figure 3 shown, as an alternative implementation of the present application, optionally, further includes:

[0132] An infrared detector 8, disposed on one side of the bottom of the liquid nitrogen tank 1, is used to monitor the bubble infrared detection signal reflected by the bubbles and send it to the processing unit when bubbles start to emerge from the bottom of the gas measuring pipe 2;

[0133] The infrared detector 8 is electrically connected to the processing unit.

[0134] As an alternative implementation of the present application, optionally, the processing unit is further used for:

[0135] Recording the time t when the bubble infrared detection signal is received;

[0136] Collecting the differential pressure value calculated by the differential pressure measurement unit 7 at the time t and calculating the corresponding liquid level height result.

[0137] In order to accurately calculate the air pressure difference in the return air pipe and the gas measuring pipe, the time for the differential pressure measurement unit to perform differential pressure calculation is particularly important. It is necessary to measure the data when bubbles start to emerge from the gas measuring pipe to achieve better measurement accuracy.

[0138] To monitor this time point, this solution uses an infrared monitor (composed of an infrared emitter, a receiver, etc.). The infrared monitor continuously monitors the bottom of the liquid nitrogen tank by infrared. When bubbles start to appear at the bottom of the manometer tube, the bubbles reflect the infrared light emitted by the infrared detector. The reflected infrared detection signal of the bubbles will be received by the receiver of the infrared detector and sent to the processing unit through a data line. After the processing unit receives the infrared feedback signal, it records the time t at this moment, collects the differential pressure signal calculated by the differential pressure measurement unit (real-time calculation) at time t, and calculates the corresponding liquid level height result (using the pressure formula, and other values can be pre-configured). Through infrared detection feedback, the time of the bubbles can be accurately monitored, enabling the processing unit to calculate the corresponding air pressure height difference based on the differential pressure value when the bubbles start to appear, thereby improving the calculation accuracy of the liquid level height.

[0139] Obviously, those skilled in the art should understand that to implement all or part of the processes in the above embodiments, it can be completed by instructing relevant hardware through a computer program. The program can be stored in a computer-readable storage medium. When the program is executed, it can include the processes of the above control embodiments. Those skilled in the art can understand that to implement all or part of the processes in the above embodiments, it can be completed by instructing relevant hardware through a computer program. The program can be stored in a computer-readable storage medium. When the program is executed, it can include the processes of the above control embodiments. Among them, the storage medium can be a magnetic disk, an optical disc, a read-only memory (ROM), a random access memory (RAM), a flash memory, a hard disk drive (HDD), or a solid-state drive (SSD), etc.; the storage medium can also include a combination of the above types of memories.

[0140] Embodiment 2

[0141] Based on the implementation principle of Embodiment 1, on the other hand, this application proposes an isolated detection method for the liquid nitrogen level height based on differential pressure calculation, which is implemented based on the isolated detection system for the liquid nitrogen level height based on differential pressure calculation, and includes the following steps:

[0142] System initialization;

[0143] The processing unit controls the air pump 6 to start, and pumps the gas in the liquid nitrogen tank 1 to the manometer tube 2 through the return pipe 3, and bubbles start to appear at the bottom of the manometer tube 2;

[0144] The infrared detector 8 monitors the infrared detection signal of the bubbles reflected by the infrared light when the bubbling starts at the bottom of the gas measuring tube 2 and sends it to the processing unit;

[0145] The differential pressure measurement unit 7 collects the air pressure signals at ends a and b, calculates the differential pressure, simulates the air pressure height difference between the liquid bottom and the liquid surface of the liquid nitrogen tank 1, obtains the differential pressure value between the return air pipe 3 and the gas measuring tube 2, and sends it to the processing unit;

[0146] The processing unit records the time t when it receives the infrared detection signal of the bubbles, collects the differential pressure value calculated by the differential pressure measurement unit 7 at the time t, calculates the corresponding liquid level height result, and outputs the corresponding liquid level height result to the host computer;

[0147] After receiving the liquid level height result, the host computer checks the current working attribute of the liquid nitrogen tank 1;

[0148] From the working attributes of the liquid nitrogen tank 1, identify the preset liquid level height of the liquid nitrogen in the current liquid nitrogen tank 1;

[0149] Judge whether the liquid level height result meets the preset liquid level height:

[0150] If it does not meet, send a liquid injection notice to the processing unit; otherwise, give up;

[0151] After receiving the liquid injection notice, the processing unit generates a corresponding liquid nitrogen pump signal and controls the start of the liquid nitrogen pump 9:

[0152] Continuously monitor the liquid level height result until the liquid nitrogen supplemented in the liquid nitrogen tank 1 reaches the preset liquid level height, and then turn off the liquid nitrogen pump 9;

[0153] Loop to execute the above steps.

[0154] For the above steps and specific interactions, please refer to Embodiment 1 for understanding and operation, and this embodiment will not be elaborated here.

[0155] Each module or step of the above-mentioned invention of the present invention can be implemented by a general-purpose computing system. They can be concentrated on a single computing system or distributed on a network composed of multiple computing systems. Optionally, they can be implemented by program codes executable by the computing system. Thus, they can be stored in the storage system and executed by the computing system, or they can be separately made into individual integrated circuit modules, or multiple modules or steps among them can be made into a single integrated circuit module to implement. In this way, the present invention is not limited to any specific combination of hardware and software.

[0156] Embodiment 3

[0157] As Figure 4As shown, furthermore, on the other hand, the present application also proposes a liquid nitrogen height detection device, including:

[0158] A processor;

[0159] A memory for storing executable instructions of the processor;

[0160] Wherein, when the processor is configured to execute the executable instructions, it implements the above-mentioned isolation type detection method for liquid nitrogen liquid level height based on differential pressure calculation.

[0161] The liquid nitrogen height detection device in the embodiment of the present disclosure includes a processor and a memory for storing executable instructions of the processor. Wherein, the processor is configured to implement the isolation type detection method for liquid nitrogen liquid level height based on differential pressure calculation described in the previous Embodiment 2 when executing the executable instructions.

[0162] Here, it should be noted that the number of processors can be one or more. At the same time, in the liquid nitrogen height detection device of the embodiment of the present disclosure, an input system and an output system can also be included. Wherein, the processor, the memory, the input system and the output system can be connected through a bus or in other ways, which is not specifically limited here.

[0163] As a computer-readable storage medium, the memory can be used to store software programs, computer-executable programs and various modules, such as: the programs or modules corresponding to the isolation type detection method for liquid nitrogen liquid level height based on differential pressure calculation in the embodiment of the present disclosure. The processor executes various functional applications and data processing of the liquid nitrogen height detection device by running the software programs or modules stored in the memory.

[0164] The input system can be used to receive input numbers or signals. Among them, the signal can be a key signal related to the user settings and function control of the device / terminal / server. The output system can include display devices such as a display screen.

[0165] The above has described the embodiments of the present disclosure. The above description is exemplary and not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations are obvious to those of ordinary skill in the art in the technical field without departing from the scope and spirit of the described embodiments. The selection of the terms used herein is intended to best explain the principles of the embodiments, practical applications or improvements to the technology in the market, or to enable other ordinary skill in the art in the technical field to understand the embodiments disclosed herein.

Claims

1. A liquid nitrogen level height isolation detection method based on differential pressure calculation, characterized in that: The steps include: System initialization; The processing unit controls the air pump (6) to start, and pumps the gas in the liquid nitrogen tank (1) to the gas measuring pipe (2) through the gas return pipe (3), and bubbles begin to appear at the bottom of the gas measuring pipe (2); When bubbles begin to form at the bottom of the gas measuring tube (2), the infrared detector (8) monitors the bubble infrared detection signal reflected by the bubbles to the infrared light and sends it to the processing unit; The pressure difference measurement unit (7) collects the air pressure signals at the end a and the end b and performs differential pressure calculation, simulates the air pressure height difference between the liquid bottom and the liquid surface of the liquid nitrogen tank (1), obtains the pressure difference value between the return air pipe (3) and the air measuring pipe (2), and sends it to the processing unit; The processing unit records the time t when the bubble infrared detection signal is received, collects the pressure difference value calculated by the pressure difference measurement unit (7) at the time t, calculates the corresponding liquid level height result, and outputs the corresponding liquid level height result to the host computer; After receiving the liquid level height result, the host computer checks the current working properties of the liquid nitrogen tank (1); Identifying a preset liquid level height of the liquid nitrogen in the liquid nitrogen tank (1) from the working properties of the liquid nitrogen tank (1); Determine whether the liquid level height result meets the preset liquid level height: If not satisfied, a liquid injection notification is sent to the processing unit; otherwise, the process is abandoned; After receiving the liquid injection notification, the processing unit generates a corresponding liquid nitrogen pump signal and controls the liquid nitrogen pump (9) to start: Continuously monitoring the liquid level height result until the liquid nitrogen added to the liquid nitrogen tank (1) reaches a preset liquid level height, and then shutting down the liquid nitrogen pump (9); Execute the above steps repeatedly.

2. A liquid nitrogen level height isolation detection system based on differential pressure calculation, used to implement the liquid nitrogen level height isolation detection method based on differential pressure calculation as claimed in claim 1, characterized in that: include: Liquid nitrogen tank (1), used for storing liquid nitrogen; A gas measuring pipe (2) is arranged on the liquid nitrogen tank (1), one end of which is close to the bottom of the liquid nitrogen tank (1) and the other end of which is connected to the end a of the gas pump (6) through a first pipeline (5); An air return pipe (3) is arranged on the liquid nitrogen tank (1), one end of which is close to the top of the liquid nitrogen tank (1) and the other end of which is connected to the end b of the air pump (6) through a second pipeline (4); An air pump (6) is used to form a closed-loop gas circuit with the gas return pipe (3) and the gas measuring pipe (2), and pump the gas in the liquid nitrogen tank (1) to the gas measuring pipe (2) through the gas return pipe (3); and simultaneously provide corresponding gas pressure signals to the differential pressure measuring unit (7) from its end a and end b respectively; A pressure difference measuring unit (7) is used to collect air pressure signals at ends a and b and perform differential pressure calculation, simulate the air pressure height difference between the liquid bottom and the liquid surface of the liquid nitrogen tank (1), obtain the pressure difference between the return air pipe (3) and the air measuring pipe (2), and send it to the processing unit; a processing unit, used to control the start and stop of the air pump (6), send a corresponding pump signal to the air pump (6); and calculate the air pressure height difference between the liquid bottom and the liquid surface of the liquid nitrogen tank (1) according to the pressure difference signal measured by the pressure difference measuring unit (7) according to the pressure formula, and output the corresponding liquid level height result to the host computer; The air pump (6) and the pressure difference measuring unit (7) are electrically connected to the processing unit respectively; The processing unit is communicatively connected with the host computer.

3. The liquid nitrogen level height isolation detection system based on differential pressure calculation according to claim 2 is characterized in that: The differential pressure measuring unit (7) adopts a differential pressure sensor.

4. The liquid nitrogen level height isolation detection system based on differential pressure calculation according to claim 2 is characterized in that: The differential pressure measuring unit (7) comprises: Differential pressure acquisition interface, used to collect air pressure signals at end a and end b; A 24-bit ADC conversion module, used for performing digital-to-analog conversion on the air pressure signal; The processor MCU is used to calculate the differential pressure of the air pressure signals at the end a and the end b to obtain the corresponding pressure difference value; The RS485 communication interface is used to communicate with the processing unit and send the pressure difference signal to the processing unit.

5. The liquid nitrogen level height isolation detection system based on differential pressure calculation according to claim 2 is characterized in that: Also includes: A liquid nitrogen pump (9), used for replenishing liquid nitrogen into the liquid nitrogen tank (1) to a preset liquid level height; The liquid nitrogen pump (9) is electrically connected to the processing unit.

6. The liquid nitrogen level height isolation detection system based on differential pressure calculation according to claim 5 is characterized in that: The processing unit is further used for: After the host computer receives the liquid level height result, checking the current working properties of the liquid nitrogen tank (1); Identifying a preset liquid level height of the liquid nitrogen in the liquid nitrogen tank (1) from the working properties of the liquid nitrogen tank (1); Determine whether the liquid level height result meets the preset liquid level height: If not satisfied, a liquid injection notification is sent to the processing unit; otherwise, the process is abandoned; After receiving the liquid injection notification, the processing unit generates a corresponding liquid nitrogen pump signal and controls the liquid nitrogen pump (9) to start: Continuously monitoring the liquid level height result until the liquid nitrogen added to the liquid nitrogen tank (1) reaches a preset liquid level height, and then shutting down the liquid nitrogen pump (9); Execute the above steps repeatedly.

7. The liquid nitrogen level height isolation detection system based on differential pressure calculation according to claim 2 is characterized in that: The time for the pressure difference measurement unit (7) to collect the air pressure signals at end a and end b and calculate the pressure difference is: The air pump (6) is started to pump the gas in the liquid nitrogen tank (1) to the gas measuring tube (2) through the gas return pipe (3) until bubbles begin to appear at the bottom of the gas measuring tube (2).

8. The liquid nitrogen level height isolation detection system based on differential pressure calculation according to claim 7 is characterized in that: Also includes: an infrared detector (8), arranged at one side of the bottom of the liquid nitrogen tank (1), for monitoring, when bubbling begins at the bottom of the gas measuring tube (2), a bubble infrared detection signal reflected by the bubble to infrared light and sending the signal to the processing unit; The infrared detector (8) is electrically connected to the processing unit.

9. The liquid nitrogen level height isolation detection system based on differential pressure calculation according to claim 8, characterized in that: The processing unit is further used for: Record the time t when the bubble infrared detection signal is received; The pressure difference value calculated by the pressure difference measuring unit (7) at the time t is collected, and the corresponding liquid level height result is calculated.

10. Liquid nitrogen height detection equipment, characterized in that, include: processor; a memory for storing processor-executable instructions; Wherein, the processor is configured to implement the liquid nitrogen level height isolation detection method based on differential pressure calculation as described in claim 1 when executing the executable instructions.

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