CN102580448B - Gas filter device - Google Patents

Abstract

The invention relates to the technical field of filtering equipment, in particular to a filtering device for sampling gas at the end of human breath. It includes: a filter cavity and a water storage cavity connected to it, the filter cavity is arranged perpendicular to the horizontal plane and communicated with the water storage cavity, the filter cavity includes: an air inlet channel, a gas-liquid separation cavity, an air outlet channel and The drainage channel, the inlet channel is arranged at the beginning of the gas-liquid separation chamber, the air outlet channel and the drainage channel are arranged at the end of the gas-liquid separation chamber, and the drainage channel is connected with the water storage chamber; it is characterized in that , the gas-liquid separation chamber is provided with a hydrophobic membrane, and the cavity gas route of the gas-liquid separation chamber is arranged horizontally or downwardly from the beginning to the end. The gas filtering device of the present invention can perform single-way pumping, improves the reliability and convenience of use of the bypass gas sampling system, promotes the integration and miniaturization of the system, and has better compatibility and good airflow performance.

Description

A gas filter

technical field

The invention relates to the technical field of breath detection equipment, in particular to a filter device for sampling gas at the end of human breath .

Background technique

In the medical field, there are application requirements for the measurement and analysis of human end-breathing gas, such as ETCO2 (end-tidal carbon dioxide monitoring) module and anesthesia module. The more common application method is the side-flow type, that is, the end-breathing gas of the human body is sampled through a nasal tube or a mask, and transported to the test module in the machine through a microtube for measurement and analysis. The side-flow sampling gas is alternately the gas exhaled by the human body and the air inhaled by the human body with the respiration of the human body: the gas exhaled by the human body is a gas with a saturated humidity of 37°C, which contains more water vapor, and there is a possibility of condensation in the microtube transportation; The gas will contain a certain amount of dust. If the above impurities accumulate in the gas path of the test module, it will seriously affect the test accuracy of the sensor in the module and cause damage to the gas pump. Therefore, for side-flow gas detection devices, they must be dried and filtered before entering the test module.

In order to solve the above problems, it is necessary to use a gas filter device to dry and filter the gas; the original gas filter device is a degassing filter device structure based on condensation technology, that is, a larger cavity is designed in the microtube as a gas-liquid separation chamber. When the flow rate and pressure of the gas decrease sharply at this place, water vapor will condense and form a humidity gradient under the action of gravity. The upper part of the cavity is dry gas, while the lower part contains more condensed droplets. At this time, the dry gas in the upper part of the chamber is pumped to the module for testing, and a second pumping is required to remove the water vapor accumulated in the lower part of the chamber to maintain the sustainable operation of the gas-liquid separation chamber. The second way of pumping air will enter the water storage chamber of the degassing filter device, where condensed water will accumulate and store; the degassing filter device with this structure is not thorough enough to remove water, and at the same time, the isodiametry of the airflow is greatly damaged, which affects the waveform quality , and it is difficult to effectively filter the dust in the sampled gas.

In order to solve the above problems, existing gas filtration devices generally adopt the technology of filtering and removing water based on PTFE hydrophobic membrane, which has a good effect of filtering water vapor and can also take into account dust filtering. Currently, the degassing filtering device based on PTFE hydrophobic membrane technology, The gas-liquid separation chamber is separated by a PTFE hydrophobic membrane. In order to reduce the dead zone of the gas path, the space of the gas-liquid separation chamber is usually small, and it is necessary to use the traditional two-way pumping technology to assist drainage. In order to protect the rear end of the second pumping gas path, the second The two-way air extraction is also protected by PTFE filtration. The core of this degassing filter device is the design of the gas-liquid separation chamber.

The gas-liquid separation chamber using PTFE hydrophobic membrane gas filter device can be divided into pipeline-type gas-liquid separation chamber design and disc-shaped gas-liquid separation chamber design from the structure.

Among them, the main feature of the pipeline-type gas-liquid separation chamber is that the gas-liquid separation chamber is in the shape of a narrow and long pipe, and the PTFE hydrophobic membrane is divided into a front chamber and a rear chamber in the pipe by longitudinal cut intervals. The airway is located at the end of the back cavity of the pipeline, and the drain, that is, the second suction channel, is located at the end of the front cavity, so that a larger PTFE use area can be realized in a limited volume, and at the same time, it has better air flow equal diameter, which greatly reduces Effect of degassing filter on gas test waveform. Common pipeline-type gas-liquid separation chambers can be used: ring-shaped pipeline structure, spiral pipeline; the manufacturing process of pipeline-type gas-liquid separation chamber structure is relatively simple, but there are problems such as poor air flow isotropy and poor waveform quality.

The disc-shaped gas-liquid separation chamber design is adopted, and its main feature is that the gas-liquid separation chamber is dish-shaped, and the PTFE hydrophobic membrane is longitudinally cut and spaced in the pipeline to divide it into a front chamber and a rear chamber, and the front chamber is connected to the inlet channel and the drain channel That is, the second suction channel, the back cavity is connected to the suction channel, and the position of the cavity is not strictly restricted.

The degassing filter devices adopting the above-mentioned structure of the gas-liquid separation chamber adopt a double-way pumping design, and the gas flow of the two-way pumping needs to maintain a certain ratio, which requires the ETCO2 module to also support the double-way pumping and to filter with the gas The air resistance characteristics of the device are strictly matched, which puts forward high requirements on the precision of the module; on the one hand, this increases the manufacturing cost of the module, and at the same time limits the compatibility of the module with the gas filter device, corresponding to the above gas filter device The back-end test modules can only be applied to the gas filter device; in addition, the module and the gas filter device also need two detachable gas circuit connections, which put forward high requirements on the airtightness and reliability of the entire system. This restricts the integration and miniaturization of the bypass gas sampling system .

Contents of the invention

In view of the above problems, the present invention provides a gas filter device with better compatibility and good air flow performance, single-way pumping and high reliability.

The purpose of the present invention is achieved through the following technical solutions: The present invention provides a gas filter device, comprising: a filter cavity and a water storage cavity connected thereto, the filter cavity is arranged perpendicular to the horizontal plane and communicates with the water storage cavity , the filter chamber includes: an air inlet channel, a gas-liquid separation chamber, an air outlet channel and a drainage channel connected to each other, the inlet channel is arranged at the beginning of the gas-liquid separation chamber, and the air outlet channel and the drainage channel are arranged at the gas-liquid separation chamber. At the end of the separation chamber, the drainage channel communicates with the water storage chamber; wherein, the gas-liquid separation chamber is provided with a hydrophobic membrane, and the air path of the gas-liquid separation chamber is horizontal or horizontal from the beginning to the end. Downtrend layout.

As an improvement, the gas-liquid separation chamber is vertically arranged, and its cavity is in the shape of a pipeline. The gas-liquid separation chamber includes: a first cavity and a second cavity separated by a hydrophobic membrane, and the beginning of the first cavity It is connected with the inlet channel, its end is connected with the drain channel, and the end of the second cavity is connected with the air outlet channel; both the beginning and the end of the gas-liquid separation chamber are provided with rectifying sections.

Further, the first cavity and the second cavity of the gas-liquid separation chamber are arranged staggered at the beginning and end, the beginning of the first cavity is partially sealed to form an air intake rectifying section, and the end of the second cavity is partially staggered Sealing forms an air pumping and rectifying section; the drainage channel and the water storage chamber are vertically arranged.

On the basis of the above mechanism, the cross section of the first cavity is rectangular, the cross section of the second cavity is arc-shaped, the inner diameter of the air intake channel is consistent with that of the air extraction channel, and the rectification section of the air intake and the exhaust air The air rectification section has rigid side walls.

Further, the air inlet channel and the air extraction channel are in vertical communication with the gas-liquid separation chamber respectively.

As an improvement, the chamber body of the gas-liquid separation chamber is in the shape of a serpentine pipe, and the air outlet passage is provided with a protective filter element.

As another improvement, horizontal sections are provided at the beginning and middle of the gas-liquid separation chamber.

As yet another improvement, the end section of the first cavity is an arc-shaped descending section.

As an improvement, the cavity of the gas-liquid separation chamber is in the shape of a "W"-shaped pipe, and the gas-liquid separation chamber has a straight pipe section inclined downward.

The gas path of the gas-liquid separation cavity of the gas filter device of the present invention is arranged in a horizontal or downward trend from the beginning to the end, the gas-liquid separation cavity is always meandering downward, and the liquid droplets condensed in the front cavity of the gas-liquid separation cavity Under the action of airflow and its own gravity, it continuously flows to the end of the pipeline. The closer to the end, the more dominant the effect of gravity, and finally accumulates at the end of the front cavity of the gas-liquid separation chamber. Here it directly leads to the water storage chamber, and the liquid droplets will flow into the water storage chamber under the action of gravity. The gas filtering device of the present invention can perform single-way pumping, improves the reliability and convenience of use of the bypass gas sampling system, promotes the integration and miniaturization of the system, and has better compatibility and good airflow performance. At the same time, the gas-liquid separation chamber of the present invention is designed with air flow rectification in the front and rear intake and extraction channels, which effectively avoids the impact of high-speed air flow on the hydrophobic membrane and reduces turbulent flow.

Description of drawings

For ease of illustration, the present invention is described in detail by the following preferred embodiments and accompanying drawings.

Fig. 1 is a schematic diagram of the gas circuit principle of the present invention;

Fig. 2 is a schematic structural view of a serpentine pipeline type gas-liquid separation chamber without a hydrophobic membrane installed in the present invention;

Fig. 3 is a schematic diagram of the structure of the serpentine pipeline type gas-liquid separation chamber of the present invention after the hydrophobic membrane is installed;

Fig. 4 is a cross-sectional view of the serpentine pipeline gas-liquid separation chamber according to the direction A-A in Fig. 3 of the present invention;

Fig. 5 is a structural schematic diagram of another embodiment of the present invention;

Fig. 6 is a structural schematic diagram of a preferred embodiment of the present invention;

Fig. 7 is a comparison of rise time between the filter device of the present invention and the existing filter device.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

Please refer to Fig. 1 to Fig. 4, the present invention provides a kind of gas filtering device, comprising: including filter chamber and water storage chamber 5, filter chamber includes pipeline-shaped gas-liquid separation chamber, inlet channel 2, outlet channel 3, drain channel 4 , to protect the filter element 6 and the hydrophobic membrane 7. The gas-liquid separation chamber is connected with the air inlet channel 2, the air outlet channel 3 and the drain channel 4, the drain channel 4 is connected with the water storage chamber 5, the protective filter element 6 is arranged in the air outlet channel 3, and the hydrophobic membrane 7 is arranged in the gas-liquid separation chamber In this embodiment, the gas-liquid separation chamber is vertically arranged, and the gas-liquid separation chamber is always in a horizontal or descending process from the beginning to the end, and there is no lifting section.

The gas-liquid separation chamber is divided into a first chamber 1a and a second chamber 1b by a hydrophobic membrane 7 . The beginning of the first cavity 1 a is connected to the air intake channel 2 , and the end is connected to the drain channel 4 . As shown in the cross-section in Figure 4, the first cavity 1a is a square cross-section, because there will be water droplets flowing in it, and the water vapor flow rate in the cavity, especially the beginning of the first cavity 1a, is relatively high, especially the front end of the front cavity. If there is a cavity turning, the water vapor in the cavity will act on the side wall of the cavity with a very high steering acceleration, and the design is square to slow down the impact of water vapor on the hydrophobic membrane. The second cavity 1b is only connected to the air outlet 3 at the end of the pipeline, and its cross section is an arc-shaped cross-section, because the flow in the back cavity is clean gas that has been dried, and the arc-shaped cross-section can effectively improve the isometric flow of the gas. At the same time reduce the gas low velocity area.

As shown in Figure 2, the first cavity 1a and the second cavity 1b of the gas-liquid separation chamber of the present invention are staggered by a certain distance at the beginning and end, and the beginning of the first cavity 1a is partially sealed to form an air inlet rectifying section 8, The end of the second cavity 1b is staggered and partially sealed to form the air extraction rectification section 9, the intake rectification section 8 and the air extraction rectification section 9 are rigid side walls; at the beginning of the gas-liquid separation cavity, the second cavity 1b is larger than the first cavity 1a is short, avoiding the connection between the first cavity 1a and the air inlet 2; and at the end, the first cavity 1a is shorter than the second cavity 1b, also avoiding the second cavity 1b and the suction Road 3 Junction. In the present invention, both the air intake channel 2 and the air extraction channel 3 are in vertical communication with the gas-liquid separation lumen, and the inner diameters of the air intake channel 2 and the air extraction channel 3 are consistent, while the first cavity 1a and the second cavity 1b The cross-sectional area is also very close to the above-mentioned air passage, and combined with the gas rectification section, the gas in the gas filter device of the present invention basically maintains an isometric flow.

Firstly, the exhaled gas sample enters the first chamber 1a of the gas-liquid separation chamber through the air inlet channel 2. When the high-speed airflow turns sharply at the connection point, the airflow will be very violently turbulent. The main flow direction is parallel to the hydrophobic membrane 7, which not only avoids the impact on the flexible hydrophobic membrane 7, but also maintains a good equidistant flow of the airflow in the gas-liquid separation chamber, and the airflow turbulence zone and dead zone are reduced to a certain extent; then, The sampling gas flows along the first cavity 1a to the end and flows through the hydrophobic membrane 7 to the second cavity 1b. The gas in the first cavity 1a is continuously reduced while the water vapor remains unchanged, so that the air flow in the cavity is further to the rear end. The lower the speed, the higher the humidity. And the drying gas in the second cavity 1 b is more and more, so that the air flow speed is faster as it moves toward the rear end. Finally, at the end of the gas-liquid separation chamber, there is no stable air flow in the first chamber 1a, and water vapor and liquid droplets accumulate here, and flow into the water storage chamber 5 through the drainage channel 4 under the action of their own gravity for storage. The filtered dry gas in the second cavity 1b has the highest velocity and is drawn out through the air outlet. Simultaneously, the protective filter element 6 is set in the air outlet channel 3 of the present invention, and it will be blocked when it encounters water vapor. If catastrophic damage occurs to the gas-liquid separation chamber and water vapor is sucked into the outlet channel 3, the protective filter element will effectively block the closed pipeline to prevent water vapor from entering the back-end module and causing damage.

Fig. 5 is another embodiment of the present invention, the gas-liquid separation chamber of this kind is in a shape similar to W, and the gas-liquid separation chamber has a straight pipe section 10 that is inclined downward, so that a longer gas flow can be achieved in a smaller elevation. The length of the liquid separation chamber.

Fig. 6 is the best embodiment of the present invention. The whole gas-liquid separation chamber meanders downwards in a serpentine shape. We design a horizontal pipe section 10 at the beginning and middle of the gas-liquid separation chamber. At the same time, the entire chamber is concentrated in a circle within a diameter of 16mm to facilitate manufacturing and realize A longer cavity in a smaller elevation ensures sufficient PTFE hydrophobic membrane filtration area. According to our research, the first cavity 1a of the gas-liquid separation chamber has a higher air velocity in the initial section and the middle section, which is enough to drive the liquid to move backward. And middle section is designed with horizontal section 10 so that the lengthening distance design of gas filtering device. However, the air velocity in the end section of the first cavity 1a is relatively low. In this embodiment, it is designed as an arc-shaped descending section 11 to make more use of gravity to assist drainage. At the same time, the centrifugal effect of the airflow in the arc-shaped section causes water vapor to accumulate in the pipeline. On the side wall, it is convenient to concentrate the flow, and finally the water vapor will gather at the end of the first cavity 1 a and flow into the drainage channel 4 .

Both the front end and the rear end of the gas-liquid separation chamber in this embodiment are designed with rectification sections. Wherein the end of the second cavity 1b is slightly tilted, which can more effectively avoid the misinhalation of liquid.

As shown in Figure 7, under the same situation and pumping rate, the gas filter device of the present invention is compared with the rise time of the existing gas filter device. This parameter is an important evaluation index of the performance of the gas filter device. Next, test the concentration rise time of the higher concentration CO2 gas flowing through the gas filter device. It can be seen from the figure that when the waveform rise reaches 100%, the present invention consumes the least time, followed by the traditional two-way suction pipeline type gas-liquid separation chamber solution, and finally the traditional disc-shaped gas-liquid separation chamber solution; at the same time In the present invention, the rising amount of the waveform is the largest. At the same time, the long-term air extraction test shows that the gas filter device of the present invention can continue to operate until the water storage chamber is full.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should be included in the protection of the present invention. within range .

Claims (8)

1. A gas filtering device, comprising: a filter cavity and a water storage cavity communicated with it, the filter cavity is arranged perpendicular to the horizontal plane and communicated with the water storage cavity, the filter cavity comprises: an air inlet channel communicated with each other, A gas-liquid separation chamber, an air outlet and a drainage channel, the inlet channel is arranged at the beginning of the gas-liquid separation chamber, the air outlet channel and the drainage channel are arranged at the end of the gas-liquid separation chamber, the drainage channel and the storage The water cavity is connected; it is characterized in that a hydrophobic membrane is arranged in the gas-liquid separation cavity, and the cavity gas route of the gas-liquid separation cavity is arranged horizontally or downwardly from the beginning to the end; the gas-liquid separation cavity includes a The hydrophobic membrane separates the first cavity and the second cavity, the beginning of the first cavity is connected with the air inlet, the end of the first cavity is connected with the drain, and the end of the second cavity is connected with the The air outlets are connected to each other, the gas-liquid separation chamber is vertically arranged, and its cavity is in the shape of a pipe, and rectification sections are provided at the beginning and end of the gas-liquid separation chamber. 2. The filter device according to claim 1, characterized in that, the first cavity and the second cavity of the gas-liquid separation chamber are arranged alternately at the beginning and end, and the beginning ends of the first cavity are staggered and partially sealed An air intake rectifying section is formed, and the end of the second cavity is staggered and partially sealed to form an air extraction rectifying section; the drainage channel and the water storage chamber are vertically arranged. 3. The filtering device according to claim 2, wherein the cross section of the first cavity is rectangular, the cross section of the second cavity is arc-shaped, and the inner diameters of the air inlet and outlet are consistent. Both the air intake rectification section and the air extraction rectification section have rigid side walls. 4 . The filter device according to claim 3 , wherein the air inlet channel and the air outlet channel are in vertical communication with the gas-liquid separation chamber, respectively. 5 . The filtering device according to claim 4 , wherein the chamber body of the gas-liquid separation chamber is in the shape of a serpentine pipe, and the air outlet channel is provided with a protective filter element. 6 . 6. The filter device according to claim 5, characterized in that, horizontal sections are provided at the beginning and middle of the gas-liquid separation chamber. 7. The filtering device according to claim 6, characterized in that, the end section of the first cavity is an arc-shaped descending section. 8 . The filter device according to claim 1 , wherein the body of the gas-liquid separation chamber is in the shape of a "W"-shaped pipe, and the gas-liquid separation chamber has a straight pipe section inclined downward.

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