CN111624057A - Gaseous mercury enrichment device - Google Patents

Abstract

The invention discloses a gaseous mercury enrichment device, which comprises a filter membrane clamp, a sampling pump and a silver filter membrane; the silver filtering membrane is arranged in the filtering membrane clamp, one end of the filtering membrane clamp is communicated with the air inlet, and the other end of the filtering membrane clamp is communicated with the sampling pump. The enrichment device of the gaseous mercury aims at solving the problem that the traditional method can not enrich the granular mercury in a gas sample, and better realizes the complete enrichment of the gaseous total mercury.

Description

A kind of enrichment device for gaseous mercury

technical field

The invention belongs to the technical field of atmospheric monitoring, and in particular relates to a gaseous mercury enrichment device.

Background technique

Mercury is a toxic heavy metal element that is liquid at room temperature, and can volatilize into the ambient atmosphere and stay in the atmosphere for a long time (usually six months to two years), so that the mercury in the atmosphere can diffuse and grow with the airflow. Migration and transport over distance. The sources of mercury in the atmosphere are mainly man-made emissions and natural discharge processes. Man-made emissions mainly include the combustion of coal, petroleum, and biomass fuels, as well as industrial production activities such as mining and smelting of metal minerals, and cement production. Natural emissions processes include volcanoes, geothermal, soil and surface releases such as water bodies. Changes in gaseous mercury concentration can reflect the intensity of mercury emissions from industrial activities, regional atmospheric mercury distribution and transport laws, and can also analyze the source of atmospheric mercury and evaluate the pollution degree of atmospheric mercury. In addition, long-term exposure to the atmospheric environment with a mercury concentration exceeding 50 ng/m ³ is considered to cause damage to the human body. However, the concentration of gaseous mercury is very low, with gaseous mercury generally in the nanogram per cubic meter (ng/m ³ ) level, and gaseous reactive mercury and particulate mercury in the picogram per cubic meter (pg/m ³ ) level. Therefore, the measurement of gaseous mercury is very challenging, and it needs to be accurately enriched to a certain amount to meet the detection limit and requirements of the detector.

The traditional gaseous mercury measurement is to first extract the sample gas, then pass through a filter membrane that can remove PM2.5, and then pass through an enrichment tube filled with gold-plated quartz sand particles or pure gold particles, so as to enrich the mercury in the sample gas to gold. Above the particles, the desorption enrichment tube is then heated, and the thermally decomposed elemental mercury is brought into the atomic fluorescence or atomic absorption detector through the carrier gas (high-purity argon) to analyze the mercury content. As a result, particulate mercury (usually adsorbed on PM2.5 aerosols) is not enriched into the sample gas, so that the final measured mercury concentration does not contain particulate mercury.

At present, the research and development of gaseous mercury measurement technology in China is still relatively small, especially for the measurement of atmospheric samples with low mercury content (below 2ng/m ³ ), there is no particularly mature technology. In addition, the current international atmospheric mercury pre-concentration technology is still a traditional method, which has not changed in the past ten years. The traditional gold enrichment tube is difficult to clean after being polluted by atmospheric particles, so it is necessary to remove the particles larger than PM2.5 before enrichment, and the cost is high, and the replacement cost is high once passivation.

In view of this, it is urgent for those skilled in the art to provide a gaseous mercury enrichment device to solve the problem that the traditional method cannot enrich the particulate mercury in the gas sample.

SUMMARY OF THE INVENTION

(1) Technical problems to be solved

The technical problem to be solved by the present invention is that the traditional method cannot enrich the particulate mercury in the gas sample, so that the enrichment of the gaseous total mercury can be better achieved.

(2) Technical solutions

The invention provides a gaseous mercury enrichment device, comprising a filter membrane clip, a sampling pump and a silver filter membrane; the silver filter membrane is arranged in the filter membrane clip, and one end of the filter membrane clip is connected to an air inlet The other end of the filter membrane clamp is communicated with the sampling pump.

Further, the silver filter membrane is stacked in two layers in the filter membrane holder.

Further, the pore size of the silver filter membrane is less than 2 μm.

Further, the filter membrane clip includes a filter membrane pressure ring and a filter membrane support net; a boss is arranged inside the filter membrane pressure ring, and the filter membrane support net is provided with a fixing ring that is adapted to the boss. , and the filter membrane support net is provided with an air channel.

Further, the sampling pump is a vacuum pump.

Further, one end of the filter membrane holder is communicated with the air inlet through a first connecting pipe.

Further, the other end of the filter membrane clamp is communicated with the sampling pump through a second connecting pipe.

Further, the enrichment device for gaseous mercury also includes a volumetric flowmeter, the volumetric flowmeter is a gas mass flowmeter, and the volumetric flowmeter is connected to the outlet of the sampling pump through a third connecting pipe. .

(3) Beneficial effects

The above-mentioned technical scheme of the present invention has the following advantages:

The invention provides a filter membrane clip, a sampling pump and a silver filter membrane; the silver filter membrane is arranged in the filter membrane clip, one end of the filter membrane clip is communicated with the air inlet, the other end of the filter membrane clip is communicated with the sampling pump, and the air intake There is no need to add a PM2.5 filter membrane, so that the particulate mercury in the gas sample can be enriched on the silver filter membrane or on the silver filter membrane to meet the enrichment of elemental mercury, active mercury and particulate mercury in the gas sample. Complete enrichment of total mercury in the sample is achieved.

Description of drawings

1 is a schematic structural diagram of a gaseous mercury enrichment device provided in an embodiment of the present invention;

2 is a cross-sectional view of the structure of a filter membrane holder in the enrichment device for gaseous mercury provided in an embodiment of the present invention;

FIG. 3 is a schematic structural diagram of a filter membrane holder of a filter membrane holder in a gaseous mercury enrichment device provided in an embodiment of the present invention.

In the picture:

1. Membrane clip; 11. Membrane pressure ring; 111, Boss; 12, Membrane support net; 121, Fixing ring;

122. Air channel; 2. Sampling pump; 3. Silver filter membrane; 4. Air inlet; 5. Positive displacement flowmeter;

601, the first connecting pipe; 602, the second connecting pipe; 603, the third connecting pipe.

Detailed ways

The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and embodiments. The following examples are intended to illustrate the present invention, but not to limit the scope of the present invention.

In the description of the present invention, it should be understood that the terms "center", "portrait", "horizontal", "top", "bottom", "front", "rear", "left", "right", "vertical" The orientation or positional relationship indicated by "straight", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplification It is described, rather than indicated or implied, that the device or element referred to must have a particular orientation, be constructed and operate in a particular orientation, and therefore should not be construed as limiting the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed to indicate or imply relative importance.

In the description of the present invention, it should be noted that the terms "installed", "connected" and "connected" should be understood in a broad sense, unless otherwise expressly specified and limited, for example, it may be a fixed connection or a detachable connection Connection, or integral connection; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through an intermediate medium, can be internal communication between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood in specific situations.

At present, the pre-concentration of atmospheric mercury at home and abroad mainly uses a certain amount of pure gold particles or quartz sand gold-plated particles to be filled in a quartz tube, and then one end of the quartz tube (air inlet) is linked to the PM2.5 filter head, and the other One end (the gas outlet) is linked to a suction pump, through which the gas sample is drawn through the gold particles, thereby enriching the mercury in the gas sample onto the gold particles. Finally, a high temperature is generated after the heating wire is energized, and the mercury enriched by gold particles is thermally decomposed into elemental mercury, which is then loaded into the mercury detector through the carrier gas to analyze the content.

It has the following problems:

(1) The particle size of the gold particles needs to be in a suitable range. After the gold particles with too large particle size are filled into the quartz tube, the gap between the particles will be relatively large, and the gas sample will be easier to penetrate, resulting in a decrease in the enrichment efficiency. When the gold particles with too small particle size are filled into the quartz tube, the gap between the particles is too small, which will make it difficult for the airflow to pass through, thereby increasing the load of the air pump;

(2) The method of filling gold particles can only enrich gas samples, and it is difficult for liquid samples to pass through, and it is very easy to cause passivation of gold particles, thereby reducing the absorption efficiency of mercury;

(3) The method of filling gold particles must add a PM2.5 filter membrane before entering the gas sample to remove the large particles in the gas, otherwise the particles will enter the gaps of the gold particles and accumulate, causing the gold particles to passivate and block the gas. road;

(4) The method of filling gold particles is difficult to clean and activate after the absorption efficiency is reduced. It requires multiple pickling and cleaning of organic reagents, and then repeatedly tests whether the absorption efficiency reaches the standard;

(5) The method of filling gold particles can only enrich the elemental mercury and active mercury in the gas sample, and the particulate mercury is filtered out by PM2.5, so the analysis is not the real total mercury;

(6) The production and filling process requirements of gold particles are relatively high. At present, there is no such process in China. At the same time, aerodynamic testing is required, and the amount of filling is relatively large to meet the requirements of high mercury enrichment efficiency. Such a cost is very expensive, usually an imported mercury enrichment tube filled with gold particles costs more than 10,000 yuan.

According to an embodiment of the present invention, a gaseous mercury enrichment device is provided. As shown in FIG. 1 , it includes a filter membrane holder 1, a sampling pump 2 and a silver filter membrane 3; the silver filter membrane 3 is arranged in the filter membrane holder 1 and filters One end of the membrane clamp 1 is communicated with the air inlet 4 , and the other end of the filter membrane clamp 1 is communicated with the sampling pump 2 .

In this embodiment, the sampling pump 2 passes the gas or liquid sample through the silver filter membrane 3 at a certain flow rate, so that the mercury in the sample is completely enriched on the silver filter membrane 3, and the enrichment method of the silver filter membrane 3 is adopted, The air inlet does not need to add a PM2.5 filter membrane, so that the particulate mercury in the gas sample can be enriched on the silver film or on the silver film, which can meet the enrichment of elemental mercury, active mercury and particulate mercury in the sample, so that the real mercury can be enriched. It realizes the complete enrichment of total mercury in the sample, solves the problem that the traditional method cannot enrich the particulate mercury in the gas sample, and truly realizes the test of gaseous total mercury.

In some optional embodiments, the silver filter membrane 3 is stacked in two layers in the filter membrane holder 1 . The replacement of silver filter membrane 3 is relatively simple, not as complicated and cumbersome as gold particle filling, the specification and dosage are relatively easy to determine, no complicated aerodynamic test is required, and the double-layer membrane enrichment can be effective and meet the enrichment efficiency of mercury .

In some optional embodiments, the pore size of the silver filter membrane 3 is less than 2.5 μm. Specifically, the pore size of the silver filter membrane 3 may be less than 2 μm, so that no additional PM2.5 filter membrane is required at the air inlet 4, which is beneficial to enrichment of particulate mercury in the sample.

In some optional embodiments, as shown in Figures 2-3, the filter membrane holder 1 includes a filter membrane pressure ring 11 and a filter membrane support net 12; the filter membrane pressure ring 11 is provided with a boss 111 inside, and the filter membrane support net 12 is provided with a fixing ring 121 matched with the boss 111, and an air channel 122 is provided on the filter membrane support net 12.

In this embodiment, the filter membrane holder 1 has a simple structure, simple operation, and strong practicability, which overcomes the disadvantages of the traditional filter membrane holder, which is inconvenient to hold the filter membrane and sample loss, saves the time for replacing the filter membrane, and improves the measurement accuracy. At the same time, the special structure design of the filter membrane pressure ring 11 and the filter membrane support net 12 avoids the filter membrane deformation, vibration and damage that are easy to occur when the gas passes through the filter membrane.

Specifically, the air channels 122 evenly distributed in the filter membrane support net 12, the air channels 122 are square or circular in shape, and the number is generally 2-2000, and all the end surfaces are flat and maintained at the same height, A flat filter membrane support surface is formed, and its function is to hold the filter membrane 12; the function of the air channel 122 is to flow in and out air.

In some optional embodiments, the sampling pump 2 is a vacuum pump. The structure of the vacuum pump is simple and compact, and the suction force is large.

In some optional embodiments, one end of the filter membrane holder 1 is communicated with the air inlet 4 through the first connecting pipe 601 . The first connecting pipe 601 connects the filter holder 1 and the air inlet 4 to ensure that the air sample flows into the filter holder 1 to adsorb the mercury therein.

In some optional embodiments, the other end of the filter cartridge 1 is communicated with the sampling pump 2 through the second connecting pipe 602 . The second connecting pipe 602 connects the filter holder 1 and the sampling pump 2 to ensure that a suction force is provided for the device to allow the air sample to flow into the filter holder 1 .

In some optional embodiments, the enrichment device for gaseous mercury further includes a volumetric flowmeter 5, wherein the volumetric flowmeter 5 is a gas mass flowmeter, and the volumetric flowmeter 5 is connected to the outlet of the sampling pump 2 through a third connection Pipe 603 is connected. Among them, the positive displacement flowmeter 5 is used to record the total flow of the gas.

With the entry into force and implementation of the International Mercury Convention "Minamata Convention", the global demand for mercury analysis and testing is growing, and the traditional enrichment method for mercury in gas samples has not been improved since its invention in the 1980s. With the promotion of the application of mercury analysis instruments in China in recent years and the increase in testing requirements, more comprehensive and effective mercury enrichment methods and technologies should be adopted in the future. It also minimizes the production cost of mercury enrichment tubes used in mercury analyzers.

Compared with the traditional gaseous mercury enrichment device, the gaseous mercury enrichment device provided in the embodiment of the present invention has the following advantages:

(1) Use a silver filter membrane with a pore size of less than 2 microns, and the air inlet does not need to add a PM2.5 filter membrane, so that the particulate mercury in the gas sample can be enriched on the silver membrane or on the gas sample The enrichment of elemental mercury, active mercury and particulate mercury, so as to truly realize the complete enrichment of total mercury in the sample;

(2) The replacement of the silver filter membrane is relatively simple, not as complicated and cumbersome as gold particle filling, the specification and dosage are relatively easy to determine, and complex aerodynamic tests are not required, and the double-layer membrane enrichment can be effective and meet the enrichment of mercury. set efficiency;

(3) After the passivation and absorption efficiency of the silver filter membrane become low, the cleaning and activation method is simpler than that of the enrichment tube filled with gold particles, and the silver filter membrane can be directly removed for cleaning and purification, and the operation is more convenient;

(4) The price of silver is much lower than that of gold, the production process and cost of silver film are relatively low, and it is generally easier to buy in the market, thereby greatly reducing the cost of mercury enrichment tubes;

(5) The mercury enrichment method using the silver filter membrane can enrich the mercury in the liquid sample in addition to the enrichment of the mercury in the gas sample, thereby expanding the application scope of the embodiment of the present invention.

The above are only the preferred embodiments of the present invention. It should be pointed out that for those skilled in the art, without departing from the technical principles of the present invention, several improvements and modifications can also be made. These improvements and modifications It should also be regarded as the protection scope of the present invention.

Claims (8)

1. The gaseous mercury enrichment device is characterized by comprising a filter membrane clamp (1), a sampling pump (2) and a silver filter membrane (3); the silver filtering membrane (3) is arranged in the filtering membrane clamp (1), one end of the filtering membrane clamp (1) is communicated with the air inlet (4), and the other end of the filtering membrane clamp (1) is communicated with the sampling pump (2).

2. The gaseous mercury enrichment device of claim 1, wherein the silver filter membrane (3) is stacked in two layers within the filter membrane holder (1).

3. The gaseous mercury enrichment device of claim 1 or 2, wherein the pore size of the silver filter membrane (3) is less than 2_μm。

4. The gaseous mercury enrichment device of claim 1, wherein the filter membrane holder (1) comprises a filter membrane pressure ring (11) and a filter membrane carrier web (12); the filter membrane clamping ring is characterized in that a boss (111) is arranged on the inner side of the filter membrane clamping ring (11), the filter membrane supporting net (12) is provided with a fixing ring (121) matched with the boss (111), and an air channel (122) is arranged on the filter membrane supporting net (12).

5. The gaseous mercury enrichment device of claim 1, wherein the sampling pump (2) is a vacuum pump.

6. The gaseous mercury enrichment device of claim 1, wherein one end of the filter membrane holder (1) is in communication with the gas inlet (4) via a first connecting conduit (601).

7. The gaseous mercury enrichment device of claim 1, wherein the other end of the filter membrane holder (1) is in communication with the sampling pump (2) via a second connection conduit (602).

8. The gaseous mercury enrichment device of claim 1, further comprising a volumetric flow meter (5), wherein the volumetric flow meter (5) is a gas mass flow meter, and the volumetric flow meter (5) is connected to the outlet of the sampling pump (2) through a third connecting pipe (603).

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