A compact aerosol neutralizer

Abstract

The application discloses a small aerosol neutralizer, which comprises an aerosol inlet piece, a neutralization cavity, a neutralization source, a sealing end cover and a sealing ring, the aerosol inlet piece is provided with an air inlet and an expansion port connected with the air inlet, the upper end of the neutralization cavity is provided with an air outlet, the aerosol inlet piece and the lower end of the neutralization cavity are connected together through the sealing ring, the upper end of the neutralization cavity and the sealing end cover are connected together through the sealing ring, and the neutralization source is evenly arranged on the upper end of the neutralization cavity and is made of americium (Am-241). The small aerosol neutralizer is a bipolar charger, can efficiently neutralize aerosols and reaches a charge balance state. The small aerosol neutralizer has stable charge proportion, small volume and long service life, and is suitable for occasions such as low-concentration particulate matter particle size distribution measurement in atmospheric environment.

Description

Technical Field

[0001] The invention belongs to the technical field of environmental monitoring, and in particular relates to a small aerosol neutralizer. Background Art

[0002] When measuring atmospheric particulate matter, a particle size distribution instrument can measure atmospheric particulate matter in real time, obtaining the number concentration of particles of varying sizes. A particle size distribution instrument typically consists of three components: a charging unit, a screening unit, and a measurement unit. The charging unit ensures that the aerosol entering the measurement system reaches a state of charge equilibrium or a known charge distribution, which is then used for data inversion by the instrument.

[0003] Common charging units include soft X-ray neutralizers, high-voltage discharge neutralizers, and radioactive source neutralizers. The source of a soft X-ray neutralizer is expensive and has a relatively short service life. High-voltage discharge neutralizers are affected by the oxidation and contamination of the high-voltage discharge needle, and their charging efficiency is easily unstable and they are prone to produce ozone. The radioactive sources commonly used in radioactive source neutralizers have a high source strength and are rarely used in China. For americium (Am-241), the State Environmental Protection Administration issued the "Announcement on the Issuance of the Radioactive Source Classification Method" in 2005, which limited the Class IV source of Am-241 to ≥6E8 Bq and the Class V source to ≥1E4 Bq. However, the exemption value for Am-241 used in fixed smoke alarms is 1E5 Bq.

[0004] When measuring the particle size distribution of 10nm-1000nm particles in the atmospheric environment, there are two main characteristics. First, the aerosol flow rate is relatively small, with a common value of 0.3L / min. Second, the atmospheric particle number concentration is less than 1E6# / cc, which is an aerosol with a small flow rate and low particle concentration. Currently, there is no small, low-radiation intensity aerosol neutralizer suitable for occasions such as measuring the particle size distribution of low-concentration particles in the atmospheric environment. Summary of the Invention

[0005] The purpose of the present invention is to design a small aerosol neutralizer, which uses low-dose-rate americium as the neutralization source of the neutralizer and can efficiently neutralize aerosols with small flow rates and low particle concentrations.

[0006] The technical solution of the present invention is a small aerosol neutralizer, including an aerosol inlet piece, a neutralization cavity, a neutralization source, a sealing end cover and a sealing ring. The aerosol inlet piece is provided with an air inlet and an expansion port connected thereto, the upper end of the neutralization cavity is provided with an air outlet, the aerosol inlet piece and the lower end of the neutralization cavity are connected together by a sealing ring, the upper end of the neutralization cavity and the sealing end cover are connected together by a sealing ring, and the neutralization source uses americium and is evenly distributed at the upper end of the neutralization cavity.

[0007] The expansion angle of the expansion opening of the aerosol inlet piece is 20°-90°.

[0008] The inner diameter of the neutralization cavity is 12-60 mm, the length is 30-50 mm, and the material of the neutralization cavity is metal.

[0009] The neutralization source is a single piece or several pieces of americium (Am-241).

[0010] The total radioactivity of the americium is 2.5E4 Bq-1E5 Bq.

[0011] The gas flow rate passing through the small aerosol neutralizer is 0.1-0.6 L / min.

[0012] The number concentration of gas particles passing through the small aerosol neutralizer is: 0-3E6# / cc.

[0013] The small aerosol neutralizer provided by the present invention has the following advantages:

[0014] 1. The small aerosol neutralizer provided by the present invention is a bipolar charger that can efficiently neutralize aerosols with small flow rates and low particle number concentrations to achieve a charge balance state.

[0015] 2. The small aerosol neutralizer provided by the present invention has a stable charge ratio, a small size, and a long service life, and is suitable for occasions such as measuring the particle size distribution of low-concentration particulate matter in the atmospheric environment.

[0016] 3. The small aerosol neutralizer provided by the present invention is well sealed, and the total radioactivity of low-dose-rate americium is lower than the exemption value of Am-241 for use in fixed smoke alarms as stipulated by the State Environmental Protection Administration, making it an extremely low-hazard source. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the cross-sectional structure of a small aerosol neutralizer.

[0018] Figure 2 Schematic diagram of the neutralization source layout structure.

[0019] Figure 3 Ion concentration plots generated for a multi-chip neutralization source

[0020] Description of the reference numerals in the accompanying drawings:

[0021] 1. Aerosol inlet; 2. Neutralization chamber; 3. Neutralization source; 4. Sealing end cap; 5. Sealing ring; 6. Air inlet; 7. Expansion port; 8. Air outlet; DETAILED DESCRIPTION

[0022] To make the purpose, technical solutions and advantages of the present invention more clear, the technical solutions in the embodiments of the present invention will be described in more detail below with reference to the accompanying drawings in the embodiments of the present invention. It should be emphasized that the following description is merely exemplary and is not intended to limit the scope of the present invention and its application.

[0023] Example

[0024] A small aerosol neutralizer described in this embodiment Figure 1 、 Figure 2 and Figure 3 shown.

[0025] The small aerosol neutralizer described in this embodiment includes an aerosol inlet 1, a neutralization chamber 2, a neutralization source 3, a sealed end cap 4, and a sealing ring 5. The aerosol inlet 1 has an air inlet 6 and an expansion port 7 connected thereto. The upper end of the neutralization chamber 2 has an air outlet 8. The aerosol inlet 1 and the lower end of the neutralization chamber 2 are connected via the sealing ring 5. The upper end of the neutralization chamber 2 and the sealed end cap 4 are also connected via the sealing ring 5. The neutralization source 3 uses americium at a low dose rate and is evenly distributed at the upper end of the neutralization chamber 2. The air outlet 8 can also be located above the sealing end cap 4.

[0026] The expansion angle of the expansion opening 7 of the aerosol inlet piece 1 is 20°-90°.

[0027] The inner diameter of the neutralization cavity 2 is 12-60 mm, and the length is 30-50 mm. The neutralization cavity 2 is made of metal or other conductive materials.

[0028] The neutralization source 3 is a single piece or several pieces of americium (Am-241). The shape of the americium can be flake or columnar.

[0029] The total radioactivity of the americium is 2.5E4 Bq-1E5 Bq.

[0030] The gas flow rate passing through the small aerosol neutralizer is 0.1-0.6 L / min.

[0031] The concentration of gas particles passing through the small aerosol neutralizer is: 0-3E6# / cc (# / cc means particles per cubic centimeter).

[0032] The following is a further description of the principle, working process and specific implementation of a small aerosol neutralizer with reference to the accompanying drawings:

[0033] Figure 1 This is a schematic cross-sectional structural diagram of a small aerosol neutralizer, which includes an aerosol inlet 1, a neutralization cavity 2, a neutralization source 3, a sealing end cover 4 and a sealing ring 5.

[0034] The specific implementation is described below.

[0035] The aerosol inlet 1 is made of stainless steel, with a 1 / 4-inch straight tube air inlet 6 at one end and a diffuser 7 at the other. Aerosol enters the aerosol neutralizer through a hose or ferrule connected to the 1 / 4-inch straight tube air inlet 6. The aerosol slowly expands in the diffuser 7 area at an angle ranging from 20° to 90°, preferably 30°, until it reaches the same inner diameter as the neutralization chamber 2. A sealing ring 5 seals the aerosol inlet 1 and the neutralization chamber 2.

[0036] The neutralization chamber 2 is a stainless steel metal part. The internal cavity is a hollow cavity with a diameter of 30 mm and a length of 40 mm. The end face is provided with evenly distributed disc-shaped low-dose rate americium 3. Americium produces a large number of α particles during the decay process. Under the action of the α particles, the aerosol gradually reaches a charge equilibrium state. An aerosol outlet 8 is left on the upper side of the neutralization chamber 2. The outer diameter of the straight tube of the outlet 8 is 1 / 4 inch. The neutralized aerosol flows out from this port for use by other downstream units.

[0037] The sealing end cover 4 and the neutralization chamber 2 are sealed by a sealing ring 5, and a sealing ring is placed between the neutralization source 3 and the sealing end cover 4 for extrusion and fixation.

[0038] Figure 2 The figure shows the arrangement of the neutralization source 3, which is composed of four single-chip neutralization sources 3. In actual application, the number of neutralization sources 3 used can be comprehensively considered based on the particle concentration in the measured use environment and the dose rate of the single-chip neutralization source.

[0039] Figure 3 This is a graph of ion concentrations produced by multiple neutralization sources (ion sources). The radioactivity of each source is approximately 2.5E4 Bq. As the number of sources used increases, the total radioactivity increases. When four sources are used, the maximum ion concentration produced is 1.9E6 ions per cubic centimeter.

[0040] The small aerosol neutralizer provided by the present invention is a bipolar neutralizer that can electrically neutralize charged particles in the aerosol, eliminating static electricity and facilitating subsequent particle size distribution measurements. Neutralization source 3 uses a single or multiple pieces of low-dose-rate americium with a total radioactivity of 2.5E4 Bq to 1E5 Bq. The applicable aerosol flow rate is 0.1-0.6 L / min. Under conditions of 1E5 Bq activity and an aerosol flow rate of 0.1 L / min, the number concentration of neutralizable particles is 0-3E6 # / cc. Under the same aerosol flow rate conditions, an increase in total radioactivity will increase the number concentration of neutralizable particles. Under the same total radioactivity conditions, an increase in aerosol flow rate will shorten the residence time of particles in the cavity, and the upper limit of the number concentration of neutralizable particles will be reduced.

[0041] Low-dose-rate americium radiation sources are considered extremely low-hazard sources due to their low dose rate. Americium has a half-life of 432.2 years, maintaining a stable charging efficiency for a long period of time. Americium radiation sources are alpha radiators, and during their decay process, they produce a large number of alpha particles, which can effectively neutralize aerosols within the cavity. Because alpha particles travel a very short distance in air, approximately 40 mm, they primarily irradiate internally, and, if properly sealed, pose negligible harm to the human body. Therefore, the present invention uses low-dose-rate americium as the neutralization source in a small neutralizer, making it well-suited for applications such as measuring the particle size distribution of low-concentration particulate matter ranging from 10 nm to 1000 nm in atmospheric environments.

[0042] The small aerosol neutralizer provided by the present invention can efficiently neutralize aerosols to achieve a charge equilibrium state. This small aerosol neutralizer has a stable charge ratio, a small size, and a long lifespan, making it suitable for applications such as measuring the particle size distribution of low-concentration particulate matter in atmospheric environments.

[0043] Finally, it should be noted that the above embodiments are intended only to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art will appreciate that modifications may be made to the technical solutions described in the above embodiments, or that some of the technical features may be replaced with equivalents; such modifications or replacements do not deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A small aerosol neutralizer, characterized by: The invention comprises an aerosol inlet, a neutralization cavity, a neutralization source, a sealing end cap and a sealing ring. The aerosol inlet is provided with an air inlet and an expansion port connected thereto. The upper end of the neutralization cavity is provided with an air outlet. The aerosol inlet is connected to the lower end of the neutralization cavity via a sealing ring. The upper end of the neutralization cavity is connected to the sealing end cap via a sealing ring. The neutralization cavity is made of metal. The neutralization source is uniformly arranged at the upper end of the neutralization cavity. The neutralization source is a single piece or several pieces of americium Am-241. Under the conditions of an activity of 1E5 Bq and an aerosol flow rate of 0.1 L / min, the americium Am-241 can neutralize a particle number concentration of 0-3E6# / cc. Under the conditions of the same total radioactivity, the aerosol flow rate increases and the residence time of the particles in the cavity is shortened.

2. A small aerosol neutralizer according to claim 1, characterized in that: The expansion angle of the expansion opening of the aerosol inlet piece is 20°-90°.

3. The small aerosol neutralizer according to claim 1, characterized in that: The inner diameter of the neutralization cavity is 12-60 mm and the length is 30-50 mm.

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