阅读说明：本技术 一种气体中汞的检测系统和检测方法 (Detection system and detection method for mercury in gas ) 是由 敖小强 杨露露 于 2019-10-21 设计创作，主要内容包括：本发明涉及气体中汞的检测系统和检测方法。检测系统包括光源、双光束生成装置、测量池、参比池、汞吸附装置；双光束生成装置将光源发出的单光束分成平行的第一光束和第二光束,第一光束通过第一光路射向参比池,第二光束通过第二光路射向测量池；汞吸附装置用于吸附除去汞；测量池的出气口和汞吸附装置的进气口之间通过第一气路连接,汞吸附装置的出气口和参比池的进气口之间通过第二气路连接。本申请提出的气体中汞的检测系统,不需要增加背景气去除装置,无需测定背景气的组分,且不需要昂贵的贵金属材料作为汞吸附剂,进而提高了抗气体干扰的能力,降低了设备成本,能够用于现场实时检测过程,适用范围较广泛。(The invention relates to a detection system and a detection method for mercury in gas. The detection system comprises a light source, a double-beam generation device, a measurement pool, a reference pool and a mercury adsorption device; the double-beam generating device divides a single beam emitted by the light source into a first beam and a second beam which are parallel, the first beam is emitted to the reference cell through a first light path, and the second beam is emitted to the measuring cell through a second light path; the mercury adsorption device is used for adsorbing and removing mercury; the gas outlet of the measuring pool is connected with the gas inlet of the mercury adsorption device through a first gas path, and the gas outlet of the mercury adsorption device is connected with the gas inlet of the reference pool through a second gas path. The application provides a detection system of mercury in gas need not increase background gas remove device, need not to survey the component of background gas, and does not need expensive noble metal material as mercury adsorbent, and then has improved the ability of anti gaseous interference, has reduced equipment cost, can be used for on-the-spot real-time detection process, and application scope is more extensive.)

1. The system for detecting the mercury in the gas is characterized by comprising a light source, a double-beam generating device, a measuring cell, a reference cell and a mercury adsorbing device;

the double-beam generating device divides a single beam emitted by the light source into a first beam and a second beam which are parallel, the first beam is emitted to the reference cell through a first light path, and the second beam is emitted to the measuring cell through a second light path;

the measuring tank, the reference tank and the mercury adsorption device are provided with an air inlet and an air outlet;

the mercury adsorption device is used for adsorbing and removing mercury;

the gas outlet of the measuring cell is connected with the gas inlet of the mercury adsorption device through a first gas path, and the gas outlet of the mercury adsorption device is connected with the gas inlet of the reference cell through a second gas path.

2. The system for detecting mercury in a gas of claim 1, wherein the dual beam generating device comprises a half-mirror and a mirror;

the semi-transparent semi-reflecting mirror receives the single beam from the light source to form transmitted light and reflected light; the transmitted light is used as the first light beam and penetrates through the semi-transparent and semi-reflective mirror to be emitted to the reference cell, and the reflected light is reflected by the reflective mirror to be emitted to the measuring cell as the second light beam.

3. The system for detecting mercury in a gas according to claim 1, wherein iodinated activated carbon is disposed in the mercury adsorbing means.

4. A system for the detection of mercury in a gas according to claim 1, characterized in that it further comprises detection means for detecting a gas concentration signal in the outgoing beam of the reference cell and a gas concentration signal in the outgoing beam of the measurement cell.

5. The system according to claim 4, wherein the detection means comprises a first detector, a second detector, a differential means;

the first detector is used for sensing a gas concentration signal in the emergent light beam of the reference cell, and the second detector is used for sensing a gas concentration signal in the emergent light beam of the measuring cell;

and the first detector and the second detector are both connected to the differentiating device.

6. A method for detecting mercury in a gas using the detection system of any one of claims 1-5, the method comprising:

after the double-beam generating device divides the single beam emitted by the light source into the first beam and the second beam which are parallel, the first beam is emitted to the reference cell, and the second beam is emitted to the measuring cell;

and sending the gas to be detected into the measuring cell to absorb the second light beam, removing mercury in the gas to be detected through the mercury adsorption device, and then sending the gas to the reference cell to absorb the first light beam.

7. The detection method according to claim 6, wherein the dual-beam generation device comprises a half-mirror and a mirror;

and a single light beam emitted by the light source passes through the semi-transparent semi-reflective mirror to obtain transmitted light and reflected light, the transmitted light is used as the first light beam and directly emitted to the reference cell, and the reflected light is reflected by the reflecting mirror and then emitted to the measuring cell as the second light beam.

8. The detection method according to claim 6, wherein iodinated activated carbon is provided in the mercury adsorption device to remove mercury in the gas to be detected.

9. The detection method according to claim 6, further comprising:

and detecting gas concentration signals in the light beams emitted by the measuring cell and the reference cell by using a detection device to obtain the concentration of mercury in the gas to be detected.

10. The detection method according to claim 9, wherein the detection device comprises a first detector, a second detector, and a differential device, and detecting the gas concentration signals in the light beams emitted from the measurement cell and the reference cell using the detection device to obtain the concentration of mercury in the gas to be detected comprises:

and detecting a first gas concentration signal in the emergent beam of the reference cell by adopting the first detector, detecting a second gas concentration signal in the emergent beam of the measuring cell by adopting the second detector, and carrying out differential processing on the first gas concentration signal and the second gas concentration signal by adopting the differential device to obtain the concentration of mercury in the gas to be measured.

Technical Field

The invention relates to a mercury detection system, in particular to a detection system and a detection method capable of eliminating the interference of background gas in gas to detect mercury in the gas.

Background

Mercury, which is a trace heavy metal pollutant in the environment, is difficult to discharge after entering human bodies, and can be converted into methyl mercury under the action of organisms, so that extremely strong biological toxicity is generated. Due to the accumulation of mercury in organisms, mercury is gradually enriched to the high end along the food chain, and the health of human beings is finally affected.

The emission of mercury into a body of water can severely contaminate the local environment. Elemental mercury (Hg)⁰) The emission into the atmosphere can be transported over long distances around the territory and the world with the atmospheric circulation and settle to some areas far from pollution sources, resulting in increased mercury or methyl mercury content in the organism, causing immeasurable health damage and economic losses.

Mercury has become a greenhouse gas and persistent organic, yet another attractive global chemical pollutant. At present, the pollution and control problem of mercury has become a new hotspot and a prophetic research field of global environmental problems.

For stationary pollution source flue gas, the composition is very complex, including water, SO₂、NH₃、NO_xVOCs, etc. Especially SO₂The presence of VOCs has a greater impact on mercury detection. Since, the wavelength used for mercury detection is typically 253.7nm, while SO₂VOCs also have some absorption at this wavelength, which can interfere with the detection of mercury. To address this problem, there are currently mainly several solutions:

(1) by adopting the CVAFS method, only mercury can generate certain fluorescent signals, so that the interference of other components in the smoke can be effectively avoided, and the CVAFS method has high selectivity. However, in the method, argon is required to be used as a protective gas, and usually, mercury in flue gas needs to be enriched first, and then, argon is used as a carrier gas to be sent into a gas chamber for analysis, so that real-time online analysis cannot be realized.

By adopting the ZAAS method, because the detection wavelength is split into two wavelengths, one of which contains concentration signals of mercury and interference gas, and the other contains only signals of the interference gas, the interference of other gases in the flue gas can be effectively reduced through the data processing process.

Using UV-DOAS method, by detecting other interfering gases such AS SO₂The concentration of mercury is corrected to obtain a detection result of the mercury concentration. However, this method requires specifying the type and interfering components of the background gas when applied on site, and is limited in applicability.

(2) The flue gas is pretreated, other components in the flue gas are filtered, only the mercury in the flue gas is reserved, the interference of other components can be eliminated, the detection requirement on a mercury analyzer is reduced, and the catalyst material needs to be replaced regularly. However, the pretreatment process increases the cost of the apparatus, resulting in a more complicated apparatus structure.

Disclosure of Invention

In view of the problems in the prior art, the application aims to provide a detection system and a detection method for mercury in gas, which can be used for on-line continuous measurement, laboratory analysis, on-site emergency mercury monitoring and the like of mercury in a gas sample to be detected, and are convenient to use and high in accuracy.

The application provides a detection system for mercury in gas, which comprises a light source, a double-beam generation device, a measurement pool, a reference pool and a mercury adsorption device;

the double-beam generating device divides a single beam emitted by the light source into a first beam and a second beam which are parallel, the first beam is emitted to the reference cell through a first light path, and the second beam is emitted to the measuring cell through a second light path;

the measuring tank, the reference tank and the mercury adsorption device are provided with an air inlet and an air outlet;

the mercury adsorption device is used for adsorbing and removing mercury;

the gas outlet of the measuring cell is connected with the gas inlet of the mercury adsorption device through a first gas path, and the gas outlet of the mercury adsorption device is connected with the gas inlet of the reference cell through a second gas path.

As an alternative embodiment of the present application, the dual beam generating device includes a half mirror and a mirror;

the semi-transparent semi-reflecting mirror receives the single beam from the light source to form transmitted light and reflected light; the transmitted light is used as the first light beam and penetrates through the semi-transparent and semi-reflective mirror to be emitted to the reference cell, and the reflected light is reflected by the reflective mirror to be emitted to the measuring cell as the second light beam.

As an optional embodiment of the present application, iodinated activated carbon is disposed in the mercury adsorption device.

Further, the detection system further comprises a detection device for detecting a gas concentration signal in the outgoing beam of the reference cell and a gas concentration signal in the outgoing beam of the measurement cell.

As an optional embodiment of the present application, the detection device includes a first detector, a second detector, and a difference device;

the first detector is used for sensing a gas concentration signal in the emergent light beam of the reference cell, and the second detector is used for sensing a gas concentration signal in the emergent light beam of the measuring cell;

and the first detector and the second detector are both connected to the differentiating device.

The application also provides a detection method for detecting mercury in gas by using the detection system, and the detection method comprises the following steps:

after the double-beam generating device divides the single beam emitted by the light source into the first beam and the second beam which are parallel, the first beam is emitted to the reference cell, and the second beam is emitted to the measuring cell;

and sending the gas to be detected into the measuring cell to absorb the second light beam, removing mercury in the gas to be detected through the mercury adsorption device, and then sending the gas to the reference cell to absorb the first light beam.

As an alternative embodiment of the present application, the dual beam generating device includes a half mirror and a mirror;

and a single light beam emitted by the light source passes through the semi-transparent semi-reflective mirror to obtain transmitted light and reflected light, the transmitted light is used as the first light beam and directly emitted to the reference cell, and the reflected light is reflected by the reflecting mirror and then emitted to the measuring cell as the second light beam.

As an optional embodiment of the present application, iodinated activated carbon is disposed in the mercury adsorption device, and is used for removing mercury in the gas to be detected.

Further, the detection method further comprises:

and detecting gas concentration signals in the light beams emitted by the measuring cell and the reference cell by using a detection device to obtain the concentration of mercury in the gas to be detected.

As an optional embodiment of the present application, the detecting device includes a first detector, a second detector, and a differential device, and detecting the gas concentration signals in the light beams emitted from the measuring cell and the reference cell by using the detecting device to obtain the concentration of mercury in the gas to be detected includes:

and detecting a first gas concentration signal in the emergent beam of the reference cell by adopting the first detector, detecting a second gas concentration signal in the emergent beam of the measuring cell by adopting the second detector, and carrying out differential processing on the first gas concentration signal and the second gas concentration signal by adopting the differential device to obtain the concentration of mercury in the gas to be measured.

In the detection system of mercury in gas that this application provided, need not increase background gas remove device, need not to survey the component of background gas, and need not expensive noble metal material as mercury adsorbent, and then improved this detection system anti gas interference's ability, reduced equipment cost, can be used for on-the-spot real-time detection process, application scope is more extensive.

Drawings

Fig. 1 is a schematic structural diagram of a system for detecting mercury in a gas according to the present disclosure.

Fig. 2 is a schematic structural diagram of a system for detecting mercury in a gas according to one embodiment of the present disclosure.

Detailed Description

The following detailed description of the present invention, taken in conjunction with the accompanying drawings and examples, is provided to enable the invention and its various aspects and advantages to be better understood. However, the specific embodiments and examples described below are for illustrative purposes only and are not limiting of the invention.

The terms "connected" and "connected" as used herein, unless otherwise expressly specified or limited, are to be construed broadly, as meaning either directly or through an intermediate. In the description of the present application, it is to be understood that the directions or positional relationships indicated by "upper", "lower", "front", "rear", "left", "right", "top", "bottom", and the like are based on the directions or positional relationships shown in the drawings, and are only for convenience of description and simplification of description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and thus, should not be construed as limiting the present application.

Fig. 1 is a schematic structural diagram of a system for detecting mercury in a gas according to the present disclosure. The detection system for detecting mercury in a gas comprises a light source 10, a dual-beam generating device 20, a measuring cell 30, a mercury adsorbing device 40 and a reference cell 50.

The dual beam generating device 20 is capable of receiving a single beam from the light source 10 and splitting the beam into two parallel beams, a first beam and a second beam. Wherein the first light beam is directed into the reference cell 50 via a first light path. The second beam is directed through a second optical path into the measuring cell 30.

The measuring cell 30, the mercury adsorption device 40 and the reference cell 50 are all provided with an air inlet and an air outlet.

The mercury adsorption device 40 is used for adsorbing and removing mercury in the gas to be detected, and other components in the gas to be detected are not removed. Further, the mercury adsorption device 40 is provided with a heating component, and the adsorption reaction in the mercury adsorption device 40 can only adsorb and remove mercury in the gas to be detected without removing other components by controlling the heating temperature.

The measuring cell 30, the mercury adsorption device 40 and the reference cell 50 are connected in sequence. Specifically, the air outlet of the measuring cell 30 is connected to the air inlet of the mercury adsorbing device 40 through a first air path. The gas outlet of the mercury adsorption device 40 is connected with the gas inlet of the reference cell 50 through a second gas path.

Since the mercury adsorption device 40 can only remove mercury from the gas to be measured, but does not remove other components from the gas to be measured, the concentration value of mercury in the gas to be measured can be obtained according to the signal difference between the gas concentrations in the light beams emitted from the measurement cell 30 and the reference cell 50.

In some embodiments of the present application, the mercury adsorbing means 40 is filled with iodinated activated carbon. Iodinated activated carbon is inexpensive and easy to prepare. The iodized activated carbon can form stable HgI with elemental mercury₂HgI at a temperature of 90 ℃ to 110 ℃₂Can exist in a stable state. Iodinated activated carbon to water and SO₂And the adsorption of VOCs is physical adsorption which mainly depends on the aperture of active carbon, and the adsorption performance is reduced along with the rise of temperature. Iodination of activated carbon to water and SO at a temperature of 90-110 DEG C₂And the adsorption of VOCs is very weak. Alternatively, the temperature of the mercury adsorbing device 40 is controlled to be 100 ℃.

In other embodiments of the present application, the mercury adsorption device 40 may be filled with other kinds of mercury adsorbents according to different production requirements, and accordingly, the temperature in the mercury adsorption device 40 needs to be controlled at different values.

Furthermore, the mercury adsorption device 40 only removes mercury in the gas to be measured, so that the gas fed into the reference cell 50 does not contain mercury, but the gas to be measured fed into the measurement cell 30 contains mercury, and the other gas components except for mercury in the gas in the reference cell 50 and the gas in the measurement cell 30 are the same, so that the signal difference value of the gas concentrations in the emitted light beams of the reference cell 50 and the measurement cell 30 is the concentration value of mercury in the gas to be measured.

Further, the detection system further comprises a detection device 60. The detection means 60 are used to detect the gas concentration signals in the light beams emitted by the measurement cell 30 and the reference cell 50.

As shown in fig. 2, in one embodiment of the present application, the dual beam generating device 20 includes a half mirror 21 and a reflecting mirror 22. The half mirror 21 can receive a single light beam from the light source 10, and the single light beam forms perpendicular transmitted light and reflected light after passing through the half mirror 21. The transmitted light is transmitted as a first light beam directly through the half mirror 21 and then emitted to the reference cell 50. The reflected light is further reflected by the mirror 22 and then emitted as a second light beam to the measuring cell 30.

Alternatively, in the present embodiment, the reflection surface of the half mirror 21 and the reflection surface of the reflection mirror 22 are arranged in parallel with each other, so that parallel double beams are formed.

In different embodiments of the present application, two points emitted by the light source 10 can be collected simultaneously, so as to obtain a first light beam and a second light beam which have consistent and parallel light intensity.

Further, as shown in fig. 2, the detecting device 60 includes a first detector 61, a second detector 62 and a difference device 63.

Wherein the first detector 61 is arranged to sense a gas concentration signal in the light beam emitted from the reference cell 50. The second detector 62 is used to sense a gas concentration signal in the output beam of the cell 30. Further, the first detector 61 and the second detector 62 are both connected to a differencing device 63. And the difference device 63 performs difference processing on the signal values of the concentrations of the two gases to obtain the concentration value of mercury in the gas to be detected.

Furthermore, the detection system and the principle based on the application can also be used for the determination of other elements, and also belong to the protection scope of the application.

In view of the above-mentioned system for detecting mercury in a gas, the present application also provides a method for detecting mercury in a gas, the method comprising:

the dual beam generating device 20 splits the single beam emitted by the light source 10 into a first beam and a second beam which are parallel to each other. Wherein a first beam is directed to the reference cell 50 and a second beam is directed to the measurement cell 30.

The gas to be measured is fed through the gas inlet of the measuring cell 30, the second light beam therein is absorbed, and then the gas is fed into the mercury adsorption device 40 through the gas outlet of the measuring cell 30 and the gas inlet of the mercury adsorption device 40. After the mercury in the gas to be measured is removed by the mercury adsorption device 40, the gas to be measured is sent into the reference cell 50 through the gas inlet of the reference cell 50, and the first light beam in the gas to be measured is absorbed.

Therefore, for the first light beam and the second light beam with the same light intensity, after the gas to be measured in the measuring cell 30 and the gas without mercury in the reference cell 50 respectively absorb the light beams with the same light intensity, the concentration value of mercury in the gas to be measured can be obtained by detecting the difference of absorbance according to the lambert-beer law.

Alternatively, a single light beam emitted from the light source 10 is processed by the half mirror 21 to obtain mutually perpendicular transmitted light and reflected light. The transmitted light is directly emitted to the reference cell 50 as a first light beam, and the reflected light is emitted to the measuring cell 30 as a second light beam after being reflected by the reflecting mirror 22.

Optionally, the mercury adsorption device 40 is filled with iodinated activated carbon for removing mercury from the gas to be measured. When the mercury adsorption device 40 works, the heating part in the mercury adsorption device 40 is heated to the temperature of 90-110 ℃, and at the moment, mercury in the gas to be detected and iodinated activated carbon can form a stable HgI₂. Moreover, at the temperature of 90-110 ℃, the iodinated activated carbon can not adsorb water and SO in the gas to be measured₂VOCs and the like. Optionally, the temperature in the mercury adsorption unit is controlled to be 100 ℃.

Further, the detection method of the present application further includes: the gas concentration signals in the light beams emitted from the measuring cell 30 and the reference cell 50 are detected by the detecting device 60, and the difference between the two gas concentration signals is the concentration of mercury in the gas to be detected.

Alternatively, a first detector 61 may be used to detect a first gas concentration signal in the beam exiting the reference cell 50 and a second detector 62 may be used to detect a second gas concentration signal in the beam exiting the measurement cell 30. Then, the difference device 63 is used to perform difference processing on the first gas concentration signal and the second gas concentration signal, so as to obtain the concentration of mercury in the gas to be detected.

As an alternative embodiment of the present application, the detection method of the present application employs a cold atomic absorption method, and the measurement of the mercury concentration is performed by using the absorption of mercury at a wavelength of 253.7 nm.

As an optional implementation manner of the application, the detection system and the detection method of the application are used for determining the concentration of mercury in the flue gas of the ambient air and the fixed pollution source, and can solve the problem of interference of background gas on a measurement result in the existing on-line monitoring process of mercury in the flue gas of the fixed pollution source, improve the accuracy of the measurement result and the convenience of operation, reduce the cost of the detection process, and reduce the manual maintenance time and the maintenance times.

Finally, it should be noted that: it should be understood that the above examples are only for clearly illustrating the present invention and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications of the invention may be made without departing from the scope of the invention.