Gaseous nitrous acid analyzer

Abstract

The utility model relates to gas monitoring technology, specifically provide gaseous nitrous acid analyzer, including sampling unit, separation unit and analysis unit connected in proper order, gaseous nitrous acid analyzer still includes the absorption unit connected separation unit gas export, the absorption unit includes: the both ends of jar body open, and both ends are inserted upper cover and lower cover respectively, upper cover and lower cover have gas passage respectively, sealing ring is around the outside of jar body radial, and is arranged between jar body and upper cover, and between jar body and lower cover, the filler bag is arranged in jar body, and anhydrous sodium carbonate is filled in the filler bag, the gasket is arranged in the axial direction of jar body, is extruded by upper cover and jar body one end end, and is extruded by lower cover and jar body other end end, the utility model has the advantages such as good airtightness.

Description

Technical Field

[0001] This utility model relates to gas monitoring technology, and in particular to a gaseous nitrous acid analyzer. Background Technology

[0002] The ambient air gaseous nitrous acid analyzer is an analytical instrument used for the automatic monitoring of gaseous nitrous acid (HONO) in ambient air. The sampling absorption unit uses HONO absorbent to absorb HONO from the air. A gas-liquid separation device separates the absorbent containing the HONO from the air and delivers it to the analysis unit for detection. The separated gas is then discharged through a downstream gas mass flow meter (MFC) and a sampling pump. However, this analyzer has some limitations, such as:

[0003] Because HONO absorbent contains a large amount of hydrochloric acid, which is volatile, even if a gas-liquid separation device is used to separate the gas from the hydrochloric acid absorbent, acid mist will still enter the MFC and sampling pump at the end of the gas path. In addition, HONO absorbent contains sulfonamide and nylondiamine hydrochloride. The sampling pump has a large suction force, which can easily draw a small amount of HONO absorbent into the MFC at the end in the form of droplets, forming crystals. Both hydrochloric acid mist and crystals will cause corrosion of the MFC and sampling pump, leading to damage.

[0004] To solve the above-mentioned technical problems, existing technical solutions include:

[0005] 1. Adding a sodium hydroxide absorption unit before the gas-liquid separator to absorb hydrochloric acid mist, but sodium hydroxide droplets still enter the downstream MFC and sampling pump, causing damage to the device.

[0006] 2. Canisters with added packing material in the gas path are used to filter gases. However, existing canister designs all use PTFE gaskets for sealing. To ensure airtightness, the PTFE gaskets used are generally quite thick. Due to the limited deformation of PTFE gaskets, a large amount of force is required to press the canister into the PTFE gasket and deform it to achieve a sealing effect. Due to the requirements of the packing material, the canister material is high borosilicate glass. The end face of the canister cannot guarantee flatness and roughness, which requires extremely high processing precision and has a low yield. Furthermore, the contact surface between the canister and the PTFE gasket is not evenly stressed when the canister is screwed in and tightened. Therefore, canister solutions are often prone to air leakage and cannot be widely used in the gas paths of instruments with high airtightness requirements. Utility Model Content

[0007] To address the shortcomings of the existing technical solutions, this utility model provides a gaseous nitrous acid analyzer.

[0008] The objective of this utility model is achieved through the following technical solution:

[0009] A gaseous nitrous acid analyzer includes a sampling unit, a separation unit, and an analysis unit connected in sequence; the gaseous nitrous acid analyzer further includes an absorption unit connected to the gas outlet of the separation unit, the absorption unit comprising:

[0010] The tank consists of a tank body, an upper cover, and a lower cover. The tank body is open at both ends, and the upper and lower covers are respectively inserted into the tank body. The upper and lower covers each have a gas passage.

[0011] A sealing ring, the sealing ring being arranged around the radially outer side of the tank body and disposed between the tank body and the upper cover, and between the tank body and the lower cover;

[0012] A packing bag and anhydrous sodium carbonate, wherein the packing bag is disposed inside the tank and the anhydrous sodium carbonate is filled in the packing bag;

[0013] A sealing gasket is disposed axially on the tank body and is squeezed by the upper cover and one end of the tank body, and by the lower cover and the other end of the tank body.

[0014] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0015] 1. The absorption unit replaces the conventional sodium hydroxide absorption method, thereby effectively removing hydrochloric acid mist and absorbent droplets, improving the removal efficiency of hydrochloric acid mist while avoiding the introduction of other corrosive liquids or chemical reagents;

[0016] 2. The absorption unit adopts radial and axial sealing, which has good airtightness and low requirements for the consistency of tank processing. This design can meet the needs of tanks of different materials, with low processing cost, high yield, and easy installation and disassembly.

[0017] 3. PTFE material with a pore size of 0.2μm is used as the packing bag. Anhydrous sodium carbonate is filled into the packing bag, which can not only prevent the tank lid from being unable to be opened after the anhydrous sodium carbonate absorbs and clumps, but also filter the anhydrous sodium carbonate particles.

[0018] 4. The sealing gasket is pressed tightly against the filter membrane to ensure that the sealing gasket can be reused when the tank is disassembled and the packing is replaced;

[0019] 5. Anhydrous sodium carbonate and PTFE filter membranes are used as consumables, which are easy to replace, reduce the difficulty of maintenance and disassembly, protect back-end components, and extend the life of the instrument. Attached Figure Description

[0020] The disclosure of this utility model will become more readily understood with reference to the accompanying drawings. It will be readily understood by those skilled in the art that these drawings are merely illustrative of the technical solutions of this utility model and are not intended to limit the scope of protection of this utility model. In the drawings:

[0021] Figure 1This is a schematic diagram of the absorption unit according to Embodiment 1 of this utility model.

[0022] In the attached diagram, 11-tank body, 21-upper cover, 22-lower cover, 31-sealing ring, 32-sealing gasket, 41-compression nut, 42-filter membrane, 43-non-woven fabric. Detailed Implementation

[0023] Figure 1 The following description illustrates optional embodiments of the present invention to teach those skilled in the art how to implement and reproduce it. For the purpose of teaching the technical solutions of the present invention, some conventional aspects have been simplified or omitted. Those skilled in the art should understand that variations or substitutions derived from these embodiments will be within the scope of the present invention. Those skilled in the art should understand that the following features can be combined in various ways to form multiple variations of the present invention. Therefore, the present invention is not limited to the following optional embodiments, but is defined only by the claims and their equivalents.

[0024] Example 1

[0025] This embodiment of a gaseous nitrous acid analyzer includes:

[0026] The sampling unit, separation unit, and analysis unit are connected in sequence, and these units are all existing technologies in this field.

[0027] The absorption unit connected to the gas outlet of the separation unit, such as... Figure 1 As shown, the absorption unit includes:

[0028] The tank body 11 has openings at both ends, and the upper cover 21 and the lower cover 22 are inserted into the two ends respectively. The upper cover 21 and the lower cover 22 each have a gas passage.

[0029] The sealing ring 31 surrounds the outer radial side of the tank body 11 and is disposed between the tank body 11 and the upper cover 21, and between the tank body 11 and the lower cover 22, thereby achieving radial sealing.

[0030] A packing bag is placed inside the tank 11, and anhydrous sodium carbonate is filled in the packing bag to remove hydrochloric acid from the gas.

[0031] The sealing gasket 32 ​​is positioned axially on the tank body 11 and is squeezed by the upper cover 21 and one end of the tank body 11, as well as by the lower cover 22 and the other end of the tank body 11, thereby achieving axial sealing.

[0032] To further achieve better axial sealing, the absorption unit also includes:

[0033] A clamping nut 41 is disposed between the upper cover 21 and the sealing gasket 32, and between the lower cover 22 and the sealing gasket 32. The upper cover 21 and the lower cover 22 each have a groove for accommodating the nut 41.

[0034] To further prevent the packing packing from being blocked, the absorption unit also includes:

[0035] The filter membrane 42 is disposed between the clamping nut 41 and the sealing gasket 32 ​​to block the packing pack.

[0036] Example 2

[0037] Application example of the gaseous nitrous acid analyzer according to Embodiment 1 of this utility model.

[0038] In this application example, the analyzer includes a sampling unit, a separation unit, and an analysis unit connected in sequence. The separation unit uses a gas-liquid separator. The gas outlet is connected in sequence to the absorption unit, the mass flow meter, and the sampling pump, while the liquid outlet is connected to the analysis unit.

[0039] like Figure 1 As shown, the upper cover 21 has a gas flow channel extending along its central axis. The lower cover 22 has a gas flow channel extending along its central axis and a gas passage extending in a direction perpendicular to the central axis. A circular groove is provided axially in the lower cover 22, and non-woven fabric 43 and a clamping nut 41 are disposed in the groove. A PTFE filter membrane 42 and a PTFE sealing gasket 32 ​​are disposed between the end face of the lower cover 22 and the end face of the tank body 11. The PTFE filter membrane 42 and the PTFE sealing gasket 32 ​​(with a thickness of 0.4 mm) are pressed between the lower cover 22 and the tank body 11 to achieve an axial seal. Similarly, the upper cover 21 and the tank body 11 adopt the same structure.

[0040] The inner walls of the lower cover 22 and the upper cover 21 each have annular grooves. The fluororubber sealing ring 31 is set in the annular groove and is squeezed between the lower cover 22 and the outer radial side of the tank body 11. The radial compression of the sealing ring 31 is 10%-15%, thereby achieving radial sealing.

[0041] Anhydrous sodium carbonate is filled into a PTFE packing bag with a pore size of 0.2μm. The packing bag is placed inside the tank 11 to remove hydrochloric acid from the gas.

[0042] During operation, the absorption unit effectively absorbs hydrochloric acid mist and small droplets of HONO absorbent liquid in the gas, protecting the downstream gas mass flow meter and sampling pump from corrosion by hydrochloric acid mist, and preventing crystallization due to the adhesion of HONO absorbent liquid. The anhydrous sodium carbonate packing and filter membrane 42 in the absorption unit are replaced every 3 months.

[0043] The instrument equipped with the updated absorption unit has been in field use for over two years. In contrast, existing instruments without this absorption unit require replacement of the MFC and sampling pump every six months on average. Therefore, the application of this absorption unit not only effectively extends the lifespan of the devices but also significantly reduces instrument maintenance costs.

Claims

1. A gaseous nitrous acid analyzer, comprising a sampling unit, a separation unit, and an analysis unit connected in sequence; characterized in that, The gaseous nitrous acid analyzer further includes an absorption unit connected to the gas outlet of the separation unit, the absorption unit comprising: The tank consists of a tank body, an upper cover, and a lower cover. The tank body is open at both ends, and the upper and lower covers are respectively inserted into the tank body. The upper and lower covers each have a gas passage. A sealing ring, the sealing ring being arranged around the radially outer side of the tank body and disposed between the tank body and the upper cover, and between the tank body and the lower cover; A packing bag and anhydrous sodium carbonate, wherein the packing bag is disposed inside the tank and the anhydrous sodium carbonate is filled in the packing bag; A sealing gasket is disposed axially on the tank body and is squeezed by the upper cover and one end of the tank body, and by the lower cover and the other end of the tank body.

2. The gaseous nitrous acid analyzer according to claim 1, characterized in that, The absorption unit further includes: A clamping nut is provided between the upper cover and the sealing gasket, and between the lower cover and the sealing gasket, wherein the upper cover and the lower cover each have a groove for receiving the nut.

3. The gaseous nitrous acid analyzer according to claim 2, characterized in that, The absorption unit further includes: A filter membrane is disposed between the compression nut and the sealing gasket to block the packing pack.

4. The gaseous nitrous acid analyzer according to claim 2, characterized in that, The absorption unit further includes: A nonwoven fabric is disposed between the clamping nut and the upper cover, and between the clamping nut and the lower cover.

5. The gaseous nitrous acid analyzer according to claim 3, characterized in that, The sealing ring is made of fluororubber, and the packing pack, filter membrane and sealing gasket are made of PTFE.

6. The gaseous nitrous acid analyzer according to claim 1, characterized in that, The analyzer also includes: A flow meter and a sampling pump are provided, which are located downstream of the absorption unit.

7. The gaseous nitrous acid analyzer according to claim 1, characterized in that, The inner walls of the upper and lower covers have annular grooves to accommodate the sealing ring.

8. The gaseous nitrous acid analyzer according to claim 1, characterized in that, The deformation of the sealing ring is 10%-15%, and the thickness of the sealing gasket is no more than 0.5mm.

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