CN212275686U - Thermal conductivity detection device - Google Patents

Abstract

The application relates to the technical field of gas detection, in particular to a thermal conductivity detection device. The thermal conductivity detection device comprises a thermal conductivity tank, a heat source and two chamber bodies with the same structure, wherein each chamber body comprises a tank body, a thermosensitive element and a heating body, the tank body and the heating bodies are both arranged in the thermal conductivity tank, and the heat source can heat the heating bodies and the tank body through the thermal conductivity tank. The cell body includes gas flow channel, installation position, and the thermistor sets up in installation position and visits into gas flow channel, and the installation position can also be used for installing the chromatographic column. The thermal elements of the two chambers together form a wheatstone bridge. The thermal conductivity detection device detects through two chamber structure electric bridges with simple structures, and the sensitivity is found to be guaranteed through practice. And the installation position can also be taken into account for the installation of chromatographic column, does not need extra mounting structure, has simplified the structure compared with prior art, and its cost is lower for the enterprise can go daily use and later maintenance with lower cost.

Description

Thermal conductivity detection device

Technical Field

The application relates to the technical field of gas detection, in particular to a thermal conductivity detection device.

Background

The existing thermal conductivity detector generally has the problems of low sensitivity and complex structure, and the imported high-sensitivity thermal conductivity detector has high price, so that the investment cost and the subsequent maintenance cost are increased for enterprises, and the enterprise cost is not favorably reduced.

SUMMERY OF THE UTILITY MODEL

An object of the application is to provide a thermal conductivity detection device, which can improve the problem that the existing thermal conductivity detector has a complicated structure under the condition of ensuring sensitivity.

The embodiment of the application is realized as follows:

the embodiment of the application provides a thermal conductivity detection device, which comprises a thermal conductivity tank, a heat source and two chamber bodies with the same structure, wherein each chamber body comprises a tank body, a thermosensitive element and a heating body;

the cell body comprises a gas flow channel and a mounting position, the thermosensitive element is arranged at the mounting position and extends into the gas flow channel, and the mounting position can also be used for mounting a chromatographic column;

the thermal sensitive elements of the two chamber bodies together form a wheatstone bridge.

The two chamber bodies can be respectively used as a reference pool and a measuring pool, functions can be exchanged without adding an auxiliary structure, the use is convenient, and one heat conduction pool and one heat source can serve the two chamber bodies simultaneously. In addition, the mounting position can be used for mounting a thermosensitive element and a chromatographic column, an additional chromatographic column mounting structure is omitted, the structure of the general thermal conductivity detector is simplified, and resistance change can be accurately detected by forming a Wheatstone bridge, so that the detection sensitivity is guaranteed.

In addition, the thermal conductivity detection apparatus provided in the embodiments of the present application may further have the following additional technical features:

in an optional embodiment of the present application, the thermal conductivity cell includes a copper sheet and a tungsten filament, the copper sheet is disposed on each of upper and lower sides of the tungsten filament, the copper sheet located above the tungsten filament contacts with the cell body, and the copper sheet located below the tungsten filament contacts with the heat source.

The copper sheet has good heat-conducting property, and the tungsten filament enables the heat of the heat source to be transferred to the copper sheet above from the copper sheet below more uniformly, so that the heating degrees of the two chamber bodies are basically kept consistent, and the measurement sensitivity is favorably ensured.

In an optional embodiment of the present application, the thermal conductivity detection apparatus further includes a temperature sensor, and the thermal conductivity cell is connected to the temperature sensor.

The temperature sensor can detect the temperature of the thermal conductivity cell, so that the temperature condition of the cell body arranged on the thermal conductivity cell is known, and the heating power of the heat source is adjusted.

In an alternative embodiment of the present application, the gas flow channels are semi-diffusive flow channels.

In an optional embodiment of the present application, the gas flow channel includes a gas inlet and a gas outlet, and the gas inlet are both connected with the outside through a gas circuit joint.

In an alternative embodiment of the present application, a soap foam flow meter is connected to each of the air outlets of the respective cell bodies of the two cell bodies.

The soap foam flow meter can accurately measure the flow of the discharged gas, so that an operator can adjust the flow, the flow of the two chambers is ensured to be consistent, and the detection sensitivity is ensured.

In the optional embodiment of this application, installation position detachably is connected with sealed plug screw, when the thermal conductance detection device did not work, sealed plug screw set up in installation position, the during operation of thermal conductance detection device, sealed plug screw is replaced by the chromatographic column.

The sealing plug screw can protect the thermosensitive element when not working, and prevent external impurities from influencing the thermosensitive element, so that the feedback of the thermosensitive element can be accurate when the working is guaranteed.

In an alternative embodiment of the present application, the heat sensitive element is a 100 Ω rhenium tungsten wire.

The rhenium tungsten wire is sensitive in thermal inductance, and the resistance value of 100 omega is convenient to calculate, so that the detection result of the thermal conductivity detection device can be displayed more quickly, and the rhenium tungsten wire is convenient for operators to obtain.

In an optional embodiment of the present application, the heat source includes a base and a heating element, the heating element is disposed above the base, and the thermal conductivity cell is attached to the heating element and located above the heating element.

The base not only can provide the support for whole thermal conductance detection device, can also avoid heating element to cause the influence to the device of being connected with the base.

In an alternative embodiment of the present application, the two chamber bodies are a first chamber body and a second chamber body, respectively, and the gas flow passage of the first chamber body and the gas flow passage of the second chamber body are independent from each other;

or the gas flow channel of the first chamber body is communicated with the gas flow channel of the second chamber body and is controlled to be on and off through a valve, the gas flow channel of the first chamber body can transmit carrier gas to the gas flow channel of the second chamber body, and a sample tube is connected to an inlet of the gas flow channel of the second chamber body to introduce a sample.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained from the drawings without inventive effort.

Fig. 1 is a cross-sectional view of a thermal conductivity detection apparatus provided in an embodiment of the present application.

Icon: 10-a heat conducting pool; 11-copper sheet; 12-tungsten wire; 20-a heat source; 21-a base; 22-a heating element; 23-heating the lead; 31-a pool body; 32-a thermo-sensitive element; 33-a heating body; 34-a gas flow channel; 341-air inlet; 342-an air outlet; 35-gas path joint; 50-a temperature sensor; 51-sensor leads; 60-sealing screw plug; 70-soap scum flow meter.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. The components of the embodiments of the present application, generally described and illustrated in the figures herein, can be arranged and designed in a wide variety of different configurations.

Thus, the following detailed description of the embodiments of the present application, presented in the accompanying drawings, is not intended to limit the scope of the claimed application, but is merely representative of selected embodiments of the application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.

In the description of the present application, it should be noted that the terms "inside", "outside", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings or orientations or positional relationships that the product conventionally places when used, and are only used for convenience of description and simplification of description, but do not indicate or imply that the device or element to which the reference is made must have a specific orientation, be constructed in a specific orientation, and be operated, and thus should not be construed as limiting the present application. Furthermore, the terms "first," "second," and the like are used merely to distinguish one description from another, and are not to be construed as indicating or implying relative importance.

In the description of the present application, it is also to be noted that, unless otherwise explicitly specified or limited, the terms "disposed" and "connected" are to be interpreted broadly, e.g., as being either fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present application can be understood in a specific case by those of ordinary skill in the art.

Examples

Referring to fig. 1, an embodiment of the present application provides a thermal conductivity detection apparatus, which includes a thermal conductivity cell 10, a heat source 20, and two chamber bodies.

Specifically, fig. 1 shows the structure of one chamber, and the structure of the other chamber is the same, and reference may be made to fig. 1. Specifically, the chamber body includes a cell body 31, a thermal sensitive element 32, and a heating body 33, both the cell body 31 and the heating body 33 are disposed in the thermal conductivity cell 10, and the heat source 20 can transfer heat to the heating body 33 and the cell body 31 through the thermal conductivity cell 10.

The cell body 31 comprises a gas flow passage 34 and an installation position, the thermosensitive element 32 is arranged at the installation position and extends into the gas flow passage 34, and the installation position can also be used for installing a chromatographic column; the thermal elements 32 of the two chambers together form a wheatstone bridge. The thermal conductivity detection device further comprises a temperature sensor 50, and the thermal conductivity cell 10 is connected with the temperature sensor 50 and is electrically connected with an external receiving device (such as a workstation or a recorder) through a sensor lead 51. The temperature sensor 50 can detect the temperature of the thermal conductivity cell 10, so as to know the temperature condition of the cell body 31 disposed on the thermal conductivity cell 10, so as to adjust the heating power of the heat source 20.

The gas channel 34 of the present embodiment is a semi-diffusion channel. Under the condition of ensuring that the gas does not flow too fast, the thermosensitive element 32 can be in more sufficient contact with the gas, so that the sensitivity of temperature change sensed by the thermosensitive element 32 in detection is improved. The heat sensitive element 32 used in this embodiment is a 100 Ω rhenium tungsten wire 12. The rhenium tungsten wire 12 is sensitive in thermal inductance, and the resistance value of 100 omega is convenient for external control equipment such as a workstation to calculate, so that the detection result of the thermal conductivity detection device can be displayed more quickly, and the operator can obtain the thermal conductivity detection device conveniently. In cooperation with the gas flow passage 34, the temperature of the heat sensitive element 32 changes faster and more significantly, so that the bridge changes faster and more significantly.

In detail, the gas flow path 34 includes a gas inlet 341 and a gas outlet 342, and both the gas inlet 341 and the gas inlet 341 are connected to the outside through the gas passage connector 35. The outlet 342 of the tank body 31 of each of the two chambers is connected to a soap foam flow meter 70. The soap foam flow meter 70 can accurately measure the flow rate of the discharged gas, so that an operator can adjust the flow rate, the flow rates of the two chambers are consistent, and the detection sensitivity is guaranteed.

Specifically, in this embodiment, the installation site is detachably connected with the sealing plug 60, when the thermal conductivity detection device is not in operation, the sealing plug 60 is disposed at the installation site, and when the thermal conductivity detection device is in operation, the sealing plug 60 is replaced by the chromatographic column. The sealing screw plug 60 can protect the thermosensitive element 32 when not in operation, and prevent external impurities from influencing the thermosensitive element 32, so as to ensure that the feedback of the thermosensitive element 32 can be accurate when in operation.

In the present embodiment, the two chambers are a first chamber and a second chamber, and the gas flow channel 34 of the first chamber and the gas flow channel 34 of the second chamber are independent of each other. When the device is used, the first chamber body is used for introducing pure carrier gas, and the second chamber body is used for introducing the carrier gas and the gas to be detected. Of course, the two chambers can be used as a reference cell and a measurement cell respectively, and the introduced gas can be exchanged. And the functions can be exchanged without adding an auxiliary structure, the use is convenient, and one heat conduction pool 10 and one heat source 20 can serve two chambers at the same time. In addition, the mounting position can be used for mounting the thermosensitive element 32 and also mounting a chromatographic column, an additional chromatographic column mounting structure is omitted, the structure is simplified compared with that of a general thermal conductivity detector, and resistance change can be accurately detected by forming a Wheatstone bridge, so that the detection sensitivity is guaranteed.

Or, the gas channel 34 of the first chamber body is communicated with the gas channel 34 of the second chamber body and is controlled to be on or off by a valve, the gas channel 34 of the first chamber body can transmit carrier gas to the gas channel 34 of the second chamber body, and an exhaust pipe can be further arranged and the valve can be configured. The inlet of the gas channel 34 of the second chamber body is also connected with a sample tube for introducing a sample.

When the carrier gas in the first chamber is constant, the carrier gas can be directly used in the second chamber, the total using amount of the carrier gas is reduced, a certain amount of the carrier gas is discharged in the process of conveying the carrier gas to the second chamber, then the sample gas can be quantitatively supplemented, the amount of the supplemented sample gas is equivalent to the amount of the discharged carrier gas, and the gas flow in the second chamber is ensured to be the same as the gas flow in the first chamber. Accordingly, for on-off control of the pipeline, and setting of objects such as an airflow meter in the pipeline, etc., a person skilled in the art can refer to operations such as general valve control and flow control, and details are not described herein.

Referring to fig. 1, in detail, the thermal conductivity cell 10 of the present embodiment includes a copper sheet 11 and a tungsten filament 12, the upper and lower sides of the tungsten filament 12 are respectively provided with the copper sheet 11, the copper sheet 11 located above the tungsten filament 12 contacts with the cell body 31, and the copper sheet 11 located below the tungsten filament 12 contacts with the heat source 20. The copper sheets 11 have good heat conducting performance, and the tungsten wires 12 enable the heat of the heat source 20 to be transferred to the copper sheets 11 above from the copper sheets 11 below more uniformly, so that the heating degrees of the two chambers are kept consistent basically, and the measurement sensitivity is favorably ensured.

The heat source 20 of the present embodiment includes a base 21 and a heating element 22, and the heating element 22 is disposed above the base 21 and electrically connected to the outside through a heating wire 23. Thermal conductivity cell 10 is attached to heating element 22 and positioned above heating element 22. Base 21 not only can provide support for the whole thermal conductivity detection device, but also can avoid heating element 22 from influencing the devices connected with base 21.

The principle of the embodiment is as follows:

taking the scheme that the gas paths of the two chamber bodies are independent respectively as an example, the chromatographic column is arranged at the installation position, the carrier gas is opened, the output pressure is adjusted to 0.04Mpa, the adjusting valves of the two carrier gases on the instrument are adjusted to proper values, and the flow rates of the two carrier gases are equal. Setting the heating temperature, setting the current value to be 0-200mA and the increment to be 1mA after determining that the carrier gas is introduced into the gas paths in the two chambers, and then opening the bridge flow switch.

Furthermore, hydrogen or helium or nitrogen can be used as a carrier gas, only a carrier gas flow passes through the first chamber, a simple carrier gas passes through the second chamber, and the carrier gas carrying the sample gas passes through the second chamber after stabilization. The flow rate of the two paths can be set to 50ml/min, and whether the corresponding flow rate requirement is met or not can be determined through the soap foam flow meter 70. It should be noted that the gas is introduced first and then the power is applied to avoid the residual gas in the piping from oxidizing the rhenium tungsten wire 12, and the carrier gas may be introduced first for 30 minutes and then the bridging flow is applied.

When only one carrier gas with the same flow rate and the same kind passes through both chambers, the bridge is in an equilibrium state because the resistance values of the thermistors 32 are equal and the currents flowing through the thermistors are also the same, and at this time, the thermal conductivity cell 10 outputs only one straight line (i.e., a base line) close to the zero point. Under the temperature isolation of heating body 33, the temperature of the inside cavity of heating body 33 is difficult to receive the outside temperature influence, and the stability of the temperature of the heat conduction of guarantee cell body 31 does benefit to the final testing result of guarantee reliably.

After the baseline is determined, the carrier gas with the sample starts to be introduced into the second chamber body, the chromatographic column can separate different gases in the sample, and the temperature and the resistance value of the thermosensitive element 32 in the second chamber body are changed due to the fact that the thermal conductivity coefficients of the components of the sample are different from the thermal conductivity coefficient of the carrier gas. Under the condition of constant current, the difference between the output value of the thermal conductivity cell 10 and the initial baseline is recorded by an external workstation or a recorder, and the difference generated by different components is different, so that a peak-shaped curve, namely the chromatographic peak of the sample can be obtained.

Through the process, the components of the gas of the ceramic factory can be effectively and quickly detected, the detection sensitivity is high, the result is reliable, and a user is helped to know the conditions of the gas in production, such as which components are contained, the amount of the components and the like according to the chromatographic peak.

Since the change in resistance can directly affect the balance of the bridge after the bridge is formed, the change in resistance can be detected quickly. The heat conduction pool 10 is uniform in heat transfer, and the heating body 33 is used for blocking the influence of external temperature, so that the temperature of the pool body 31 can be kept constant basically, and in combination with the sensitive sensing of the 100 omega rhenium tungsten wire 12 on temperature change, the detection sensitivity is high overall, and the resistance value of the detected change is reliable detection data. The whole device has simple structure and low corresponding cost, so that the detection cost of the components of the gas in the ceramic factory is reduced, and the device is beneficial to being used by enterprises of the type and other production enterprises needing gas detection.

The sensitivity can be calculated with reference to the following formula:

S＝AFC/W(mv·ml/mg)；

in the formula: s represents sensitivity (mv. ml/mg);

a represents the sample peak area (mv. min);

w represents the amount of sample (mg);

FC represents the calibrated carrier gas flow rate (ml/min).

Through above formula, can calculate the detectivity of the thermal conductance detection device of this embodiment, the same detection is carried out to the product that the rethread existing sensitivity is high, and the contrast finds that the detectivity of this application can compare favourably with the sensitivity of the higher detection product of current price.

It should be noted that the carrier gas is turned off when the temperature of the heating body 33 and also the temperature of the thermal conductivity cell 10 are reduced to below 80 ℃. And the heating body 33 also needs to be cooled to below 60 ℃ to take down the chromatographic column, so as to avoid damaging the thermal conductivity detection device, prolong the service life and avoid personal injury.

Certainly, under the condition of meeting the analysis sensitivity, the low bridge current is set as much as possible for use, so that the stability of the instrument is facilitated, and the service life of the thermal conductivity detection device is prolonged.

In summary, the thermal conductivity detection device of the present application detects through two simple-structured chamber structure bridges, and it is found through practice that the sensitivity is guaranteed. And the installation position can also be taken into account for the installation of chromatographic column, does not need extra mounting structure, has simplified the structure compared with prior art, and its cost is lower for the enterprise can go daily use and later maintenance with lower cost.

The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims (10)

1. A thermal conductivity detection device is characterized by comprising a thermal conductivity tank, a heat source and two chamber bodies with the same structure, wherein each chamber body comprises a tank body, a thermosensitive element and a heating body;

the cell body comprises a gas flow channel and a mounting position, the thermosensitive element is arranged at the mounting position and extends into the gas flow channel, and the mounting position can also be used for mounting a chromatographic column;

the thermal sensitive elements of the two chamber bodies together form a wheatstone bridge.

2. The thermal conductivity detection device of claim 1, wherein the thermal conductivity cell comprises a copper sheet and a tungsten filament, the copper sheet is disposed on the upper side and the lower side of the tungsten filament, the copper sheet above the tungsten filament contacts the cell body, and the copper sheet below the tungsten filament contacts the heat source.

3. The thermal conductivity detection device of claim 1, further comprising a temperature sensor, wherein the thermal conductivity cell is coupled to the temperature sensor.

4. The thermal conductivity detection device of claim 1, wherein the gas flow channel is a semi-diffusive flow channel.

5. The thermal conductivity detection device of claim 1, wherein the gas flow channel comprises a gas inlet and a gas outlet, and the gas inlet are both connected with the outside through a gas circuit joint.

6. The thermal conductivity detection device of claim 5, wherein a soap foam flow meter is connected to each of the air outlets of the cell body of each of the two chamber bodies.

7. The thermal conductivity detection device of claim 1, wherein the mounting site is detachably connected with a sealing plug screw, the sealing plug screw is disposed at the mounting site when the thermal conductivity detection device is not in operation, and the sealing plug screw is replaced by the chromatographic column when the thermal conductivity detection device is in operation.

8. The thermal conductivity detection device of claim 1, wherein the thermal sensitive element is 100 Ω rhenium tungsten wire.

9. The thermal conductivity detection device of claim 1, wherein the heat source comprises a base and a heating element disposed above the base, and the thermal conductivity cell is attached to and above the heating element.

10. The thermal conductivity detection device of claim 1, wherein the two chamber bodies are a first chamber body and a second chamber body, respectively, and the gas flow passage of the first chamber body and the gas flow passage of the second chamber body are independent from each other;

or the gas flow channel of the first chamber body is communicated with the gas flow channel of the second chamber body and is controlled to be on and off through a valve, the gas flow channel of the first chamber body can transmit carrier gas to the gas flow channel of the second chamber body, and a sample tube is connected to an inlet of the gas flow channel of the second chamber body to introduce a sample.

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