CN219799113U - Invariable free space's adsorption system - Google Patents
Invariable free space's adsorption system Download PDFInfo
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- CN219799113U CN219799113U CN202320074885.4U CN202320074885U CN219799113U CN 219799113 U CN219799113 U CN 219799113U CN 202320074885 U CN202320074885 U CN 202320074885U CN 219799113 U CN219799113 U CN 219799113U
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- 238000001179 sorption measurement Methods 0.000 title claims abstract description 39
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Abstract
The utility model relates to an adsorption system with constant free space in the technical field of analytical instruments, which comprises a test tube, a standard tube and a control host, wherein the test tube is connected with the standard tube through a pipeline; the device is characterized by also comprising a liquid level balance system and a liquid level detection device; the liquid level balancing system comprises a liquid level balancing block and a lifting device; the lifting device is connected with and controls the liquid level balance block; the control host is connected with the liquid level detection device and the liquid level balance system through communication wires or wireless connection. The utility model realizes accurate measurement of free space and effective control of ambient temperature influencing the free space, and realizes that the whole course of the second free space is not influenced by liquid level and ambient temperature and kept constant, and the first free space is thoroughly consistent with the temperature of the manifold, thereby improving the accuracy and repeatability of the test.
Description
Technical Field
The utility model relates to the technical field of analytical instruments, in particular to an adsorption system with constant free space.
Background
With the rapid development of material science such as nano materials, energy storage materials, catalytic materials and the like, physical adsorption technology is widely applied to analysis of specific surface area, pore size distribution, adsorption performance, separation effect and the like of solid materials, and nitrogen, argon and the like are common analysis gases. In order to control the adsorption process to be carried out step by step, the sample needs to be maintained at the phase inversion temperature of the corresponding analysis gas, for example, when nitrogen is the analysis gas, the sample needs to be soaked in liquid nitrogen, when argon is the analysis gas, the sample needs to be soaked in liquid argon, the pressure is continuously increased or reduced in the whole analysis process, after the adsorption equilibrium state is reached, the adsorption quantity of the sample at constant temperature and different partial pressures is calculated according to a gas equation, and an isotherm is obtained. And then, analyzing the isotherm by adopting different analysis models to obtain the information of the specific surface area, the pore size distribution, the pore volume and the like of the sample.
Physical adsorption, unlike chemisorption, is a nonselective weak adsorption, requiring a longer time for equilibrium to be reached at each partial pressure, whereas isotherms often require data acquisition at multiple partial pressures. The more data are collected, the more accurate the subsequent analysis results are, and the longer the time consumption is. The test tube loaded with the sample has a volume tested at normal temperature, which is a first free space; the resulting volume, tested at the test temperature (often cryogenic), is the second free space, where the test tube is partially submerged under and partially above the cryogenic liquid (e.g., liquid nitrogen, liquid argon). In calculating the adsorption amount of the sample, the effective free space of the test tube needs to be known, and the effective free space is calculated through the first free space and the second free space. Because the analysis process is longer, and the low-temperature liquid in the low-temperature storage device can be gradually volatilized, the liquid level is continuously lowered, so that the second free space is continuously changed, and further, the change of the effective free space is also caused, and thus, a lot of uncertainties are brought to the calculation of the adsorption quantity. In addition, when the first free space and the second free space are tested, the upper ends of the instrument host and the test tube are at room temperature, but the room temperature also changes along with the day and night, the four seasons change, the instrument placement position and other factors continuously change, and the instrument placement position and the low-temperature liquid level change are interwoven with each other, so that the first free space and the second free space also slightly change at any time, and the repeatability and the accuracy of the test are affected.
In order to solve the problem of the influence of the liquid level change on the free space, the prior main technologies are a porous material method and a liquid level constant method, and the two methods need an elevator, a dewar bottle and the like.
The porous material method is to wrap the porous material outside the test tube, lift the dewar to the specified position, and cool the test tube and the porous material with the low temperature liquid in the dewar. The liquid level is lowered due to volatilization of the low-temperature liquid, and the porous material sucks the low-temperature liquid to the highest position of the porous material by utilizing the capillary principle, so that the second free space is unchanged, and the effective free space is unchanged. However, in the practical situation of the method, during the long-time analysis, the liquid level is lowered, the porous material is inevitably separated from the low-temperature liquid more and is exposed on the low-temperature liquid, a temperature difference is formed from top to bottom, the second free space is caused to be smaller and smaller in practice, and the calculated adsorption quantity is caused to be lower. In the whole process, the volume of the test tube immersed in the low-temperature liquid and the volume of the test tube not immersed in the low-temperature liquid are changed continuously, so that even the same molar quantity of gas is caused, the distribution density of the gas in the test tube is changed continuously, and the value of the pressure and the adsorption test result of the sample are affected.
The liquid level constant method is to control the elevator to move up and down through a liquid level sensing system, so that the volume of a test tube immersed in low-temperature liquid is kept unchanged. In the analysis process, when the liquid level descends, the liquid level sensing system cannot contact the liquid level, the elevator slowly lifts the dewar until the liquid level sensor contacts the low-temperature liquid level, and the action is repeatedly performed, so that the second free space is considered to be fixed. In practice, when the dewar is raised, although the volume of the test tube immersed in the cryogenic liquid is unchanged, the portion of the test tube extending into the dewar and not immersed in the cryogenic liquid is gradually increased, and the temperature in the dewar is necessarily lower than room temperature, thereby causing the second free space to be actually increased, and causing the calculated adsorption amount to be higher. In the whole process, although the volume of the test tube immersed in the low-temperature liquid is not changed, the continuous increase of the gas distribution density in the part of the test tube not immersed in the low-temperature liquid also inevitably influences the pressure value and the adsorption test result of the sample.
Both the above two methods have defects, especially the influence of environmental factors on the test result, such as temperature change, the influence of ice particles mixed in the low-temperature liquid on the corresponding saturated vapor pressure, and the like, and no mature method can be solved in the market at present.
Disclosure of Invention
In order to solve the problem that the free space is easily influenced by environmental factors such as liquid level position, room temperature change and the like, realize accurate measurement of the free space and effective control of the environmental temperature influencing the free space, realize that the whole course second free space is not influenced by the liquid level and the environmental temperature and is kept constant, the first free space is thoroughly consistent with the manifold temperature, thereby improving the accuracy and the repeatability of the test, the utility model discloses a constant free space adsorption system, and the technical scheme of the utility model is implemented as follows:
the adsorption system comprises a test tube, a standard tube, a control host, a liquid level balance system and a liquid level detection device, wherein the test tube is connected with the standard tube through a pipeline;
the liquid level balancing system comprises a liquid level balancing block and a lifting device;
the lifting device is connected with and controls the liquid level balance block;
the control host is connected with the liquid level detection device and the liquid level balance system in a communication line or wireless connection mode.
Preferably, the liquid level detection device is selected from one of a detection system, a liquid level floating ball, a radar range finder and a thermometer;
the detection system comprises a blank pipe and a pressure gauge;
the blank pipe is connected with the pressure gauge.
Preferably, the standard tube is arranged inside the heat-insulating shell;
a fan and a radiating fin are arranged in the heat preservation shell, and the radiating fin is connected with the semiconductor peltier.
Preferably, the device further comprises a heat preservation pipe, wherein the heat preservation pipe wraps the test pipe, and the heat preservation pipe is communicated with the heat preservation shell through a pipeline.
Preferably, one ends of the test tube, the liquid level balancing system and the liquid level detecting device are arranged in the low-temperature liquid storage device in the sealed space; the sealed space is connected with the heat preservation shell.
Preferably, a second fan, a second cooling fin and a second semiconductor peltier are arranged in the sealed space.
Preferably, the blank pipe is connected with the standard pipe through a pipeline.
Preferably, the sealing space is provided with a sealing strip and a deflation port, and the sealing strip is attached to a gap of a sealing door of the sealing space;
the air release port is provided with an air release port pressure sensor and an automatic valve;
the automatic valve is controlled by the control host.
The utility model not only can realize the constant whole testing process in the second free space, but also can keep the volume immersed in the low-temperature liquid and the volume not immersed in the low-temperature liquid unchanged, namely if the test tube has constant molar quantity of free gas, the gas density distribution is completely the same, and the change with time is avoided; the external pressure of the low-temperature container, the sample tube and the like is controlled to be positive pressure and stable in temperature, so that the low-temperature liquid can be effectively prevented from being mixed into ice particles, and saturated vapor pressure fluctuation and temperature fluctuation are further ensured to be constant; the method is not only suitable for low pressure, but also can be applied to high pressure test, and the precision of the test result is greatly improved.
Drawings
In order to more clearly illustrate the embodiments of the present utility model or the technical solutions of the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, and it is obvious that the drawings in the following description are only one embodiment of the present utility model, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of an embodiment of the present utility model;
FIG. 2 is a schematic diagram of another embodiment of the present utility model;
FIG. 3 is a schematic diagram of another embodiment of the present utility model;
FIG. 4 is a schematic diagram of another embodiment of the present utility model;
FIG. 5 is a schematic three-dimensional view of an embodiment of a sealed space;
FIG. 6 is a schematic view of an embodiment of a sealed space;
fig. 7 is a schematic structural diagram of another embodiment of the present utility model.
In the above drawings, each reference numeral indicates:
pm, standard tube pressure sensor; for testing the pressure within a standard tube;
pa, testing a tube pressure sensor; for measuring the pressure in the tube;
pt, bleed port pressure sensor; for detecting the pressure of the sealed space or the vent;
pb, blank tube pressure sensor; for detecting the pressure in the blank tube;
tm, temperature sensor; for detecting the temperature in the insulating shell;
vin, inlet valve; the control standard tube is communicated with or sealed with an external air source;
vout, vacuum pump valve; the control standard pipe is communicated with or sealed with the vacuum pump;
va, test tube valve; the control test tube is communicated with or sealed with the standard tube;
vb, blank pipe valve; the blank tube is controlled to be communicated with or sealed with the standard tube;
1, standard tube;
2, testing a tube;
3, liquid level balance block
4, a liquid level floating ball;
5, lifting the elevator;
6, a dewar bottle;
7, a heat preservation shell;
8, sealing the space;
9, a fan;
10, a heat sink;
11, semiconductor peltier;
12, a second fan;
13, a second heat sink;
14, a second semiconductor peltier;
15, a radar range finder;
16, blank tube;
17, a deflation port;
18, sealing the door;
19, sealing strips;
20, automatic valve;
21, an adsorption instrument host;
22, a thermometer.
Detailed Description
The technical solutions of the present utility model will be clearly and completely described below with reference to the embodiments of the present utility model and the accompanying drawings, and it is obvious that the described embodiments are only some embodiments of the present utility model, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.
Example 1
In a specific embodiment 1, as shown in fig. 1, 5 and 6, a constant free space adsorption system includes a standard tube 1, a test tube 2, a liquid level balance 3, a thermometer 22, a lift motor 5, a dewar 6, a heat insulation shell 7, a sealed space 8, a fan 9, a heat sink 10, a semiconductor peltier 11, a second fan 12, a second heat sink 13 and a second semiconductor peltier 14, and a control host.
The control host is the adsorption instrument host 21, and the structure is common knowledge.
The standard pipe 1 is arranged in the heat-insulating shell 7 and is connected with an external air source and a vacuum pump through pipelines; the pipeline connected with an external air source is provided with an air inlet valve Vin for controlling air to enter, the pipeline connected with a vacuum pump is provided with a vacuum pump valve Vout, and a standard pipe pressure sensor Pm and a temperature sensor Tm are used for monitoring the pressure and the temperature of the standard pipe 1. The fan 9, the radiating fins 10 and the semiconductor peltier 11 are all arranged in the heat-insulating shell 7. The standard tube 1 heats or refrigerates the radiating fins 10 through the semiconductor peltier 11, and then the fan 9 diffuses heat or cool air into the environment where the whole standard tube 1 is located to control the temperature, so that the temperature is kept constant.
The heat preservation shell 7 is connected with the sealing space 8 in a sealing way.
The sealed space 8 is a space formed by the absorber host 21 and the sealing door 18, and the portion is self-contained by the absorber host 21, and is internally provided with the dewar bottle 6 to provide a low-temperature test environment.
The test tube 2, thermometer 22 and liquid level balance 3 are arranged in a dewar 6 in a sealed space 8. The liquid level balance block 3 can be made of foam heat-insulating materials and can be hollow to save materials.
In this embodiment, the second semiconductor peltier 14 heats or cools the second heat sink 13, and then the second fan 12 diffuses the heat or cool air into the sealed space 8, so as to keep the temperature of the tube body portion of the test tube 2 which is not immersed in the low-temperature liquid of the dewar 6 constant.
The test tube 2 is connected with the standard tube 1 through a pipeline, and a test tube valve Va is arranged on the pipeline and used for controlling the test tube 2 to be communicated with or closed off the standard tube 1.
In this embodiment, the liquid level floating ball 4 floats on the liquid level of the low-temperature liquid due to buoyancy, in the testing process, due to volatilization of the low-temperature liquid, when the liquid level descends, the thermometer 22 feeds back the liquid level position to the control host in real time, when the liquid level descends, the control host controls the liquid level balance block 3 to descend for a certain distance, and due to descending of the liquid level balance block 3, the liquid level in the dewar bottle 6 ascends, so that the free space in the whole testing process is constant.
In a preferred embodiment, the sealed space 8 is provided with a sealing strip 19 and a deflation port 17, and the sealing strip 19 is attached to a gap of a sealing door 18 of the sealed space 8;
the air release port 17 is provided with an air release port 17 pressure sensor and an automatic valve 20;
the automatic valve 20 is controlled by the control host.
In the testing process, as the sealed space 8 is sealed, the low-temperature liquid volatilizes into gas and then diffuses into the sealed space 8, the traditional sealing door 18 has poor effect and is easy to leak gas, so that external air can enter the sealed space 8, water vapor in the air is frozen at the upper end of the dewar bottle 6 at low temperature, and the temperature and the testing result are affected. The sealing strip 19 has the function of enhancing the sealing effect, so that when the low-temperature liquid volatilizes, more gas exists in the sealed space 8, the pressure in the sealed space 8 rises and is higher than the external environment pressure, and water vapor in the air is prevented from entering the opening of the dewar 6 to freeze. When the pressure sensor Pt at the air discharge port detects that the pressure in the sealed space 8 exceeds a set value, the control host controls the automatic valve 20 to be opened, the air leaks outwards, and the pressure in the sealed space 8 is reduced, so that the pressure is maintained in a normal range in the whole testing process.
The test procedure of this example is as follows:
1. the adsorption apparatus is first started up, and the temperature of the standard tube 1 is kept constant at a target temperature, for example, 45 ℃;
2. vacuumizing the test tube 2 filled with the sample (at the moment, the test tube 2 is not placed in the Dewar bottle 6), heating or refrigerating the second cooling fin 13 through the second semiconductor Peltier 14, and diffusing heat or cold air into the sealed space 8 through the second fan 12 so as to adjust the temperature of the test tube 2 to be the same as that of the standard tube 1;
3, performing a first free space test on the test tube 2 at the target temperature, and marking as Vfs_ST;
4. raising the dewar 6 containing the cryogenic liquid until the sample in the test tube 2 is immersed in the cryogenic liquid, and then fixing the position of the dewar 6;
5. the pressure in the sealed space 8 is detected by the pressure sensor Pt of the air release port, the opening and closing of the air release port 17 is controlled by the automatic valve 20 to realize that the pressure in the sealed door 18 is stable to be positive pressure, meanwhile, the second semiconductor Peltier 14 is used for heating or refrigerating the second radiating fins 13, and then the second fan 12 is used for diffusing heat or cold air into the sealed space 8 to keep the temperature of the tube body of the test tube 2 which is not soaked by the low-temperature liquid stable within a set temperature.
6. Testing a second free space, denoted vfs_at;
the effective free space Vfs of test tube 2 (which is a conventional technique in the art) can be calculated from the values of vfs_st and vfs_at.
In step 6, the control host adjusts the liquid level (the liquid level balance block 3 is driven to rise and fall by controlling the rising and falling motor 5) and the temperature (the second radiating fin 13 is heated or cooled by the second semiconductor peltier 14, and then the heat or cold air is diffused into the sealed space 8 by the second fan 12) in real time according to the liquid level change and the temperature change in the sealed space 8.
The present embodiment has not been developed as to how the effective free space Vfs of the test tube 2 can be calculated by temperature and pressure as is conventional in the art.
In relation to step 2, there is also a method of coating the test tube 2 with a heat-insulating jacket and connecting the heat-insulating jacket with the heat-insulating case 7. Thus, the temperature of the test tube 2 in the insulating sleeve is the same as that of the standard tube 1 in the insulating shell 7, and the temperature is controlled by the insulating sleeve in a conventional technology.
Example 2
In a specific embodiment 2, as shown in fig. 2, 5 and 6, a constant free space adsorption system includes a standard tube 1, a test tube 2, a liquid level balance 3, a radar rangefinder 15, a lift motor 5, a dewar 6, a heat retaining shell 7, a sealed space 8, a blower 9, a heat sink 10, a semiconductor peltier 11, a second blower 12, a second heat sink 13 and a second semiconductor peltier 14.
The standard pipe 1 is arranged in the heat-insulating shell 7 and is connected with an external air source and a vacuum pump through pipelines; the pipeline connected with an external air source is provided with an air inlet valve Vin for controlling air to enter, the pipeline connected with a vacuum pump is provided with a vacuum pump valve Vout, and a standard pipe pressure sensor Pm and a temperature sensor Tm are used for monitoring the pressure and the temperature of the standard pipe 1. The fan 9, the radiating fins 10 and the semiconductor peltier 11 are all arranged in the heat-insulating shell 7. The standard tube 1 heats or refrigerates the radiating fins 10 through the semiconductor peltier 11, and then the fan 9 diffuses heat or cool air into the environment where the whole standard tube 1 is located to control the temperature, so that the temperature is kept constant.
The heat preservation shell 7 is connected with the sealing space 8 in a sealing way.
The sealed space 8 is a space formed by the absorber host 21 and the sealing door 18, and the portion is self-contained by the absorber host 21, and is internally provided with the dewar bottle 6 to provide a low-temperature test environment.
The test tube 2, the radar range finder 15 and the liquid level balance 3 are arranged in the dewar 6 in the sealed space 8.
The part of the test tube 2 which is not immersed in the low-temperature liquid of the dewar 6 heats or refrigerates the second radiating fins 13 through the second semiconductor Peltier 14, and then the heat or cold air is diffused into the sealed space 8 through the second fan 12, so that the temperature of the part of the test tube 2 which is not immersed in the low-temperature liquid of the dewar 6 is kept constant.
The test tube 2 is connected with the standard tube 1 through a pipeline, and a test tube valve Va is arranged on the pipeline and used for communicating or isolating the test tube 2 with the standard tube 1.
In this embodiment, the radar range finder 15 is fixed on the inner wall of the sealed space 8, in the testing process, because the low-temperature liquid volatilizes, the liquid level descends, the radar range finder 15 detects the liquid level and changes, the position of the liquid level is fed back to the control host in real time, when the liquid level descends, the control host controls the liquid level balance block 3 to descend for a certain distance, and the liquid level in the dewar bottle 6 ascends due to the descent of the liquid level balance block 3, so that the constancy of the free space in the whole testing process is realized.
In a preferred embodiment, the sealed space 8 is provided with a sealing strip 19 and a deflation port 17, and the sealing strip 19 is attached to a gap of a sealing door 18 of the sealed space 8;
the air release port 17 is provided with an air release port pressure sensor Pt and an automatic valve 20;
the automatic valve 20 is controlled by the control host.
In the testing process, as the sealed space 8 is sealed, the low-temperature liquid volatilizes into gas and then diffuses into the sealed space 8, the traditional sealing door 18 has poor effect and is easy to leak gas, so that external air can enter the sealed space 8, water vapor in the air is frozen at the upper end of the dewar bottle 6 at low temperature, and the temperature and the testing result are affected. The sealing strip 19 has the function of enhancing the sealing effect, so that when the low-temperature liquid volatilizes, more gas exists in the sealed space 8, the pressure in the sealed space 8 rises and is higher than the external environment pressure, and water vapor in the air is prevented from entering the opening of the dewar 6 to freeze. When the pressure sensor Pt at the air discharge port detects that the pressure in the sealed space 8 exceeds a set value, the control host controls the automatic valve 20 to be opened, the air leaks outwards, and the pressure in the sealed space 8 is reduced, so that the pressure is maintained in a normal range in the whole testing process.
The test procedure of this example is as follows:
1. the adsorption apparatus is first started up, and the temperature of the standard tube 1 is kept constant at a target temperature, for example, 45 ℃;
2. vacuumizing the test tube 2 filled with the sample (at the moment, the test tube 2 is not placed in the Dewar bottle 6), heating or refrigerating the second cooling fin 13 through the second semiconductor Peltier 14, and diffusing heat or cold air into the sealed space 8 through the second fan 12 so as to adjust the temperature of the test tube 2 to be the same as that of the standard tube 1;
3, performing a first free space test on the test tube 2 at the target temperature, and marking as Vfs_ST;
4. raising the dewar 6 containing the cryogenic liquid until the sample in the test tube 2 is immersed in the cryogenic liquid, and then fixing the position of the dewar 6;
5. the pressure in the sealed space 8 is detected by the pressure sensor Pt of the air release port, the opening and closing of the air release port 17 is controlled by the automatic valve 20 to realize that the pressure in the sealed door 18 is stable to be positive pressure, meanwhile, the second semiconductor Peltier 14 is used for heating or refrigerating the second radiating fins 13, and then the second fan 12 is used for diffusing heat or cold air into the sealed space 8 to keep the temperature of the tube body of the test tube 2 which is not soaked by the low-temperature liquid stable within a set temperature.
6. Testing a second free space, denoted vfs_at;
the effective free space Vfs of the test tube 2 can be calculated from the values of vfs_st and vfs_at.
In step 6, the control host adjusts the liquid level (the liquid level balance block 3 is driven to rise and fall by controlling the rising and falling motor 5) and the temperature (the second radiating fin 13 is heated or cooled by the second semiconductor peltier 14, and then the heat or cold air is diffused into the sealed space 8 by the second fan 12) in real time according to the liquid level change and the temperature change in the sealed space 8.
Example 3
In a specific embodiment 3, as shown in fig. 3, 5 and 6, a constant free space adsorption system includes a standard tube 1, a test tube 2, a liquid level balance 3, a blank tube 16, a lift motor 5, a dewar 6, a heat insulation shell 7, a sealed space 8, a fan 9, a heat sink 10, a semiconductor peltier 11, a second fan 12, a second heat sink 13 and a second semiconductor peltier 14.
The standard pipe 1 is arranged in the heat-insulating shell 7 and is connected with an external air source and a vacuum pump through pipelines; the pipeline connected with an external air source is provided with an air inlet valve Vin for controlling air to enter, the pipeline connected with a vacuum pump is provided with a vacuum pump valve Vout, and a standard pipe pressure sensor Pm and a temperature sensor Tm are used for monitoring the pressure and the temperature of the standard pipe 1. The fan 9, the radiating fins 10 and the semiconductor peltier 11 are all arranged in the heat-insulating shell 7. The standard tube 1 heats or refrigerates the radiating fins 10 through the semiconductor peltier 11, and then the fan 9 diffuses heat or cool air into the environment where the whole standard tube 1 is located to control the temperature, so that the temperature is kept constant.
The heat preservation shell 7 is connected with the sealing space 8 in a sealing way.
The sealed space 8 is a space formed by the absorber host 21 and the sealing door 18, and the portion is self-contained by the absorber host 21, and is internally provided with the dewar bottle 6 to provide a low-temperature test environment.
The test tube 2, blank tube 16 and liquid level balance 3 are disposed in a dewar 6 within a sealed space 8.
In this embodiment 3, the second semiconductor peltier 14 heats or cools the second heat sink 13, and the second fan 12 diffuses the heat or cool air into the sealed space 8, so as to keep the temperature of the part of the test tube 2 not immersed in the low-temperature liquid in the dewar 6 constant.
The blank tube 16 is immersed in the cryogenic liquid in the dewar 6 as in the test tube 2, but no sample is contained in the blank tube 16, and a blank tube pressure sensor Pb is connected to the blank tube 16. The pressure of the blank tube 16 detected by the blank tube pressure sensor Pb changes due to volatilization of the low-temperature liquid and liquid level drop, at the moment, the control host controls the liquid level balance block 3 to drop for a distance, the liquid level in the dewar bottle 6 rises due to the drop of the liquid level balance block 3, the pressure of the blank tube 16 detected by the blank tube pressure sensor Pb returns to an initial value, and when the reading detected by the blank tube pressure sensor Pb is consistent with the initial reading, the liquid level of the low-temperature liquid can be considered to rise to an initial stage, so that the free space is constant in the whole test process. The test tube 2 is connected with the standard tube 1 through a pipeline, and a test tube valve Va is arranged on the pipeline and used for communicating or isolating the test tube 2 with the standard tube 1.
In a preferred embodiment, the sealed space 8 is provided with a sealing strip 19 and a deflation port 17, and the sealing strip 19 is attached to a gap of a sealing door 18 of the sealed space 8;
the air release port 17 is provided with an air release port pressure sensor Pt and an automatic valve 20;
the automatic valve 20 is controlled by the control host.
In the testing process, as the sealed space 8 is sealed, the low-temperature liquid volatilizes into gas and then diffuses into the sealed space 8, the traditional sealing door 18 has poor effect and is easy to leak gas, so that external air can enter the sealed space 8, water vapor in the air is frozen at the upper end of the dewar bottle 6 at low temperature, and the temperature and the testing result are affected. The sealing strip 19 has the function of enhancing the sealing effect, so that when the low-temperature liquid volatilizes, more gas exists in the sealed space 8, the pressure in the sealed space 8 rises and is higher than the external environment pressure, and water vapor in the air is prevented from entering the opening of the dewar 6 to freeze. When the pressure sensor Pt at the air discharge port detects that the pressure in the sealed space 8 exceeds a set value, the control host controls the automatic valve 20 to be opened, the air leaks outwards, and the pressure in the sealed space 8 is reduced, so that the pressure is maintained in a normal range in the whole testing process.
The test procedure of this example is as follows:
1. the adsorption apparatus is first started up, and the temperature of the standard tube 1 is kept constant at a target temperature, for example, 45 ℃;
2. vacuumizing the test tube 2 filled with the sample (at the moment, the test tube 2 is not placed in the Dewar bottle 6), heating or refrigerating the second cooling fin 13 through the second semiconductor Peltier 14, and diffusing heat or cold air into the sealed space 8 through the second fan 12 so as to adjust the temperature of the test tube 2 to be the same as that of the standard tube 1;
3, performing a first free space test on the test tube 2 at the target temperature, and marking as Vfs_ST;
4. raising the dewar 6 containing the cryogenic liquid until the sample in the test tube 2 is immersed in the cryogenic liquid, and then fixing the position of the dewar 6;
5. the pressure in the sealed space 8 is detected by the pressure sensor Pt of the air release port, the opening and closing of the air release port 17 is controlled by the automatic valve 20 to realize that the pressure in the sealed door 18 is stable to be positive pressure, meanwhile, the second semiconductor Peltier 14 is used for heating or refrigerating the second radiating fins 13, and then the second fan 12 is used for diffusing heat or cold air into the sealed space 8 to keep the temperature of the tube body of the test tube 2 which is not soaked by the low-temperature liquid stable within a set temperature, such as 25 ℃;
6. testing a second free space, denoted vfs_at;
the effective free space Vfs of the test tube 2 can be calculated from the values of vfs_st and vfs_at.
In step 6, the control host adjusts the stability of the liquid level (the liquid level balance block 3 is driven to rise and fall by controlling the lifting motor 5) and the temperature (the second radiating fin 13 is heated or refrigerated by the second semiconductor peltier 14, and then the heat or cold air is diffused into the sealed space 8 by the second fan 12) in real time according to the liquid level change and the temperature change in the sealed space 8.
The present embodiment has not been developed as to how the effective free space Vfs of the test tube 2 can be calculated by temperature and pressure as is conventional in the art.
In this embodiment, the blank tube 16 is optionally connected to the standard tube 1 through a pipeline, and a blank tube valve Vb is disposed on the pipeline to control the opening and closing, as shown in fig. 4.
In some tests, it may be desirable to measure the adsorption of multiple samples simultaneously, and at this time, the blank tube is filled with samples and used as a test tube.
The specific selection of the test tubes 2 or the blank tubes 16 may be selected according to actual requirements, and the present embodiment is not limited.
Example 4
In a specific embodiment 4, as shown in fig. 5, 6 and 7, a constant free space adsorption system includes a standard tube 1, a test tube 2, a liquid level balance 3, a thermometer 22, a lift motor 5, a dewar 6, a heat-retaining shell 7, a sealed space 8, a fan 9, a heat sink 10, a semiconductor peltier 11, a second fan 12, a second heat sink 13 and a second semiconductor peltier 14, and a control host.
The control host is the adsorption instrument host 21, and the structure is common knowledge.
The standard pipe 1 is arranged in the heat-insulating shell 7 and is connected with an external air source and a vacuum pump through pipelines; the pipeline connected with an external air source is provided with an air inlet valve Vin for controlling air to enter, the pipeline connected with a vacuum pump is provided with a vacuum pump valve Vout, and a standard pipe pressure sensor Pm and a temperature sensor Tm are used for monitoring the pressure and the temperature of the standard pipe 1. The fan 9, the radiating fins 10 and the semiconductor peltier 11 are all arranged in the heat-insulating shell 7. The standard tube 1 heats or refrigerates the radiating fins 10 through the semiconductor peltier 11, and then the fan 9 diffuses heat or cool air into the environment where the whole standard tube 1 is located to control the temperature, so that the temperature is kept constant.
The heat preservation shell 7 is connected with the sealing space 8 in a sealing way.
The sealed space 8 is a space formed by the absorber host 21 and the sealing door 18, and the portion is self-contained by the absorber host 21, and is internally provided with the dewar bottle 6 to provide a low-temperature test environment.
The test tube 2, thermometer 22 and liquid level balance 3 are arranged in a dewar 6 in a sealed space 8. The liquid level balance block 3 can be made of foam heat-insulating materials and can be hollow to save materials.
In this embodiment, the second semiconductor peltier 14 heats or cools the second heat sink 13, and then the second fan 12 diffuses the heat or cool air into the sealed space 8, so as to keep the temperature of the tube body portion of the test tube 2 which is not immersed in the low-temperature liquid of the dewar 6 constant.
The test tube 2 is connected with the standard tube 1 through a pipeline, and a test tube valve Va is arranged on the pipeline and used for controlling the test tube 2 to be communicated with or closed off the standard tube 1.
In this embodiment, the bottom measuring structure of the thermometer 22 is in contact with the liquid surface, but not deep. When the low-temperature liquid volatilizes to cause the liquid level to drop, and the temperature measuring structure breaks away from the liquid level, the reading of the thermometer 22 can change, at the moment, the control host controls the liquid level balance block 3 to drop for a certain distance, the liquid level in the dewar bottle 6 rises due to the drop of the liquid level balance block 3, the bottom temperature measuring structure of the thermometer 22 is contacted with the liquid level again, and at the moment, the reading of the thermometer 22 returns to the initial value again, so that the constancy of free space in the whole testing process is realized.
In a preferred embodiment, the sealed space 8 is provided with a sealing strip 19 and a deflation port 17, and the sealing strip 19 is attached to a gap of a sealing door 18 of the sealed space 8;
the air release port 17 is provided with an air release port 17 pressure sensor and an automatic valve 20;
the automatic valve 20 is controlled by the control host.
In the testing process, as the sealed space 8 is sealed, the low-temperature liquid volatilizes into gas and then diffuses into the sealed space 8, the traditional sealing door 18 has poor effect and is easy to leak gas, so that external air can enter the sealed space 8, water vapor in the air is frozen at the upper end of the dewar bottle 6 at low temperature, and the temperature and the testing result are affected. The sealing strip 19 has the function of enhancing the sealing effect, so that when the low-temperature liquid volatilizes, more gas exists in the sealed space 8, the pressure in the sealed space 8 rises and is higher than the external environment pressure, and water vapor in the air is prevented from entering the opening of the dewar 6 to freeze. When the pressure sensor Pt at the air discharge port detects that the pressure in the sealed space 8 exceeds a set value, the control host controls the automatic valve 20 to be opened, the air leaks outwards, and the pressure in the sealed space 8 is reduced, so that the pressure is maintained in a normal range in the whole testing process.
The test procedure of this example is as follows:
1. the adsorption apparatus is first started up, and the temperature of the standard tube 1 is kept constant at a target temperature, for example, 45 ℃;
2. vacuumizing the test tube 2 filled with the sample (at the moment, the test tube 2 is not placed in the Dewar bottle 6), heating or refrigerating the second cooling fin 13 through the second semiconductor Peltier 14, and diffusing heat or cold air into the sealed space 8 through the second fan 12 so as to adjust the temperature of the test tube 2 to be the same as that of the standard tube 1;
3, performing a first free space test on the test tube 2 at the target temperature, and marking as Vfs_ST;
4. raising the dewar 6 containing the cryogenic liquid until the sample in the test tube 2 is immersed in the cryogenic liquid, and then fixing the position of the dewar 6;
5. the pressure in the sealed space 8 is detected by the pressure sensor Pt of the air release port, the opening and closing of the air release port 17 is controlled by the automatic valve 20 to realize that the pressure in the sealed door 18 is stable to be positive pressure, meanwhile, the second semiconductor Peltier 14 is used for heating or refrigerating the second radiating fins 13, and then the second fan 12 is used for diffusing heat or cold air into the sealed space 8 to keep the temperature of the tube body of the test tube 2 which is not soaked by the low-temperature liquid stable within a set temperature.
6. Testing a second free space, denoted vfs_at;
the effective free space Vfs of the test tube 2 can be calculated from the values of vfs_st and vfs_at.
In step 6, the control host adjusts the liquid level (the liquid level balance block 3 is driven to rise and fall by controlling the rising and falling motor 5) and the temperature (the second radiating fin 13 is heated or cooled by the second semiconductor peltier 14, and then the heat or cold air is diffused into the sealed space 8 by the second fan 12) in real time according to the liquid level change and the temperature change in the sealed space 8.
The present embodiment has not been developed as to how the effective free space Vfs of the test tube 2 can be calculated by temperature and pressure as is conventional in the art.
In relation to step 2, there is also a method of coating the test tube 2 with a heat-insulating jacket and connecting the heat-insulating jacket with the heat-insulating case 7. Thus, the temperature of the test tube 2 in the insulating sleeve is the same as that of the standard tube 1 in the insulating shell 7, and the temperature is controlled by the insulating sleeve in a conventional technology.
Claims (8)
1. The adsorption system with constant free space comprises a test tube, a standard tube and a control host, wherein the test tube is connected with the standard tube through a pipeline; the device is characterized by also comprising a liquid level balance system and a liquid level detection device;
the liquid level balancing system comprises a liquid level balancing block and a lifting device;
the lifting device is connected with and controls the liquid level balance block;
the control host is connected with the liquid level detection device and the liquid level balance system in a communication line or wireless connection mode.
2. The constant free space adsorption system of claim 1, wherein said liquid level detection device is selected from the group consisting of a detection system, a liquid level float, a radar rangefinder, and a thermometer;
the detection system comprises a blank pipe and a pressure gauge;
the blank pipe is connected with the pressure gauge.
3. A constant free space adsorption system according to claim 2 wherein said standard tube is disposed inside a thermal enclosure;
a fan and a radiating fin are arranged in the heat preservation shell, and the radiating fin is connected with the semiconductor peltier.
4. A constant free space adsorption system according to claim 3 and also comprising a thermal insulation tube surrounding said test tube, said thermal insulation tube being in communication with the thermal insulation shell through a conduit.
5. A constant free space adsorption system according to claim 3 wherein one end of the test tube, level balancing system and level detecting device are disposed within the cryogenic liquid storage means of the sealed space; the sealed space is connected with the heat preservation shell.
6. The constant free space adsorption system of claim 5, wherein a second fan, a second heat sink and a second semiconductor peltier are disposed within the sealed space.
7. The constant free space adsorption system according to claim 6, wherein said blank tube is connected to said standard tube by tubing.
8. The constant free space adsorption system according to claim 7, wherein the sealed space is provided with a sealing strip and a deflation port, and the sealing strip is attached to a gap of a sealing door of the sealed space;
the air release port is provided with an air release port pressure sensor and an automatic valve;
the automatic valve is controlled by the control host.
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