CN111307744A - Device for measuring mercury in flue gas - Google Patents
Device for measuring mercury in flue gas Download PDFInfo
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- CN111307744A CN111307744A CN202010253876.2A CN202010253876A CN111307744A CN 111307744 A CN111307744 A CN 111307744A CN 202010253876 A CN202010253876 A CN 202010253876A CN 111307744 A CN111307744 A CN 111307744A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/3103—Atomic absorption analysis
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/02—Devices for withdrawing samples
- G01N1/22—Devices for withdrawing samples in the gaseous state
- G01N1/2247—Sampling from a flowing stream of gas
- G01N1/2258—Sampling from a flowing stream of gas in a stack or chimney
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
- G01N1/34—Purifying; Cleaning
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
- G01N1/38—Diluting, dispersing or mixing samples
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
- G01N1/40—Concentrating samples
- G01N1/4044—Concentrating samples by chemical techniques; Digestion; Chemical decomposition
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/3103—Atomic absorption analysis
- G01N2021/3107—Cold vapor, e.g. determination of Hg
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Abstract
The invention discloses a device for measuring mercury in flue gas, which comprises: the sampling unit is used for sampling the mercury-containing flue gas; the reaction unit is used for processing the mercury-containing flue gas and outputting the mercury-containing flue gas only containing elemental mercury; and the measuring unit is used for detecting elemental mercury in the mercury-containing flue gas output by the reaction unit. The invention provides a real-time online device for measuring mercury in flue gas, which solves the problems of high cost and complex operation of the existing scheme, and provides a solution for reaction unit adsorption, catalytic efficiency verification, high-concentration flue gas mercury measurement and the like in the flue gas mercury online monitoring process.
Description
Technical Field
The invention belongs to the field of chemical measurement, and particularly relates to a device for measuring mercury in flue gas.
Background
Mercury is a chemical substance with serious physiological toxicity, and can enter human body through respiration, skin contact, diet, mother and infant heredity, etc., and cause harm to human health. In addition, after entering the atmosphere, although the retention time of oxidized mercury and granular mercury is only a few days, elemental mercury can stay in the atmosphere for more than 1 year, and ultra-long distance transportation is realized. Relevant researches show that the current mercury pollution condition in China is serious, and the proportion of mercury emission in the coal burning process accounting for the total amount of artificial mercury emission is large. Accurate monitoring of mercury emission concentration and morphology in flue gas is an important prerequisite for mercury removal control, and selection of an appropriate measurement method is one of the keys for accurate determination of mercury in flue gas.
The existing on-line monitoring technology is mainly developed based on the cold vapor atomic absorption method, the cold vapor atomic fluorescence method, the Zeeman modulation atomic absorption method, the emerging chemical microsensor and other technologies. The nitrogen oxides, hydrogen chloride gas, sulfur dioxide and the like in the flue gas in the mainstream cold vapor atomic absorption method can influence the mercury measuring precision of the method and corrode a mercury measuring device, a gold filter is usually used for reacting with mercury to generate gold amalgam before entering a detector, and the gold amalgam is heated after a period of time and is carried into the detector by inert carrier gas.
Disclosure of Invention
In view of the above-mentioned drawbacks of the prior art, it is an object of the present invention to provide a device for measuring mercury in flue gas, which solves at least one of the problems of the prior art.
To achieve the above and other related objects, the present invention provides an apparatus for measuring mercury in flue gas, comprising:
the sampling unit is used for sampling the mercury-containing flue gas;
the reaction unit is used for converting oxidized mercury in the mercury-containing flue gas into elemental mercury and outputting the mercury-containing flue gas only containing the elemental mercury;
and the measuring unit is used for detecting elemental mercury in the mercury-containing flue gas output by the reaction unit.
Optionally, the method further comprises: and the neutralizing unit is used for removing acidic substances in the mercury-containing flue gas.
Optionally, the method further comprises: and the water removal unit is used for cooling and dehumidifying the flue gas output by the reaction unit.
Optionally, the method further comprises: and the dilution unit is used for diluting the high-concentration sample gas.
Optionally, the method further comprises: and the purging unit is used for purging the reaction unit.
Optionally, the method further comprises: and the calibration unit is used for generating oxidized mercury standard gas to calibrate the reaction unit and the measurement unit.
Optionally, the method further comprises: and the air extraction unit is used for extracting the mercury-containing flue gas in the flue to the sampling unit.
Optionally, the measuring unit detects elemental mercury in the mercury-containing flue gas output by the reaction unit based on a cold vapor atomic absorption spectrophotometry principle.
Optionally, the sampling unit comprises a probe, a probe head and a heat tracing band, one end of the probe head is inserted into the flue and is vertical to the flow direction of the flue gas, and the other end of the probe head is connected with the probe head for collecting the sample gas; one end of the heat tracing band is connected with the probe, and the other end of the heat tracing band is connected with the switching unit for transmitting the sample gas, and the heat tracing band, the probe and the switching unit are horizontally connected.
As described above, the device for measuring mercury in flue gas of the present invention has the following beneficial effects:
the invention can solve the defects of the traditional technology by combining the reaction unit, the water removal unit and the measurement unit of the cold vapor atomic absorption spectroscopy principle, is innovatively provided with the dilution unit and the purging unit, can simultaneously measure the mercury with large concentration and purge the pollution of the reaction unit by using a set of device, is provided with the reaction unit self-detection device, can observe the consumption condition of the filler in the reaction unit in real time on the premise of not opening the reaction unit, is provided with the neutralization unit, can remove the excessive acidic substances in the flue gas, is provided with the calibration unit, and can simultaneously verify the efficiency of the reaction unit and the range attenuation of the mercury detector.
Drawings
FIG. 1 is a schematic view of an apparatus for measuring mercury in flue gas according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a sampling unit according to an embodiment of the present invention.
Detailed Description
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It is to be noted that the features in the following embodiments and examples may be combined with each other without conflict.
It should be noted that the drawings provided in the following embodiments are only for illustrating the basic idea of the present invention, and the components related to the present invention are only shown in the drawings rather than drawn according to the number, shape and size of the components in actual implementation, and the type, quantity and proportion of the components in actual implementation may be changed freely, and the layout of the components may be more complicated.
The invention provides a device for measuring mercury in flue gas, which comprises:
the sampling unit 7 is used for sampling the mercury-containing flue gas;
the reaction unit 9 is used for converting oxidized mercury in the mercury-containing flue gas into elemental mercury and outputting the mercury-containing flue gas only containing the elemental mercury;
and the measuring unit 5 is used for detecting elemental mercury in the mercury-containing flue gas output by the reaction unit.
The reaction unit is used for converting oxidized mercury in the mercury-containing flue gas into elemental mercury.
It should be noted that, in the embodiment, the mercury-containing flue gas containing only elemental mercury means that mercury in the flue gas exists only in an elemental state, and does not contain oxidized mercury; of course, the flue gas may also include other types of gases in addition to elemental mercury.
The invention provides a real-time online device for measuring mercury in flue gas, which solves the problems of high cost and complex operation of the existing scheme, and provides a solution for reaction unit adsorption, catalytic efficiency verification, high-concentration flue gas mercury measurement and the like in the flue gas mercury online monitoring process.
The reaction unit is composed of potassium hydroxide filled on silicon carbide in a square stainless steel cavity, needs to be heated to 300 ℃ for use, is provided with a self-verification function, and is added with a PH color development device after the cavity, so that when gas coming out of the reaction unit shows acidity, the catalysis effect is proved to be invalid, and the filler needs to be replaced in time.
In this embodiment, the measuring unit is a mercury detector, and elemental mercury detection is performed on the mercury-containing flue gas output by the reaction unit based on the principle of cold vapor atomic absorption spectrophotometry. The mercury detector using the principle does not need expensive gold amalgam and carrier gas.
In one embodiment, the apparatus further comprises: and the air extraction unit 6 is used for extracting the mercury-containing flue gas in the flue 1 to the sampling unit. Negative pressure is created in the pipeline through the air extraction unit, the flue gas is extracted to the rear end for measurement, and the air extraction unit can adopt a miniature air extraction pump and the like. As shown in fig. 2, the sampling unit comprises a probe, a probe head and a heat tracing band, one end of the probe is inserted into the flue and is vertical to the flow direction of the flue gas, and the other end of the probe is connected with the probe head for collecting the sample gas; the probe is connected with the flue through a flange and is used as a medium for connecting the probe and the heat tracing band to transmit sample gas; one end of the heat tracing band is connected with the probe, and the other end is connected with the switching unit for transmitting the sample gas, and the heat tracing band, the probe and the switching unit are horizontally connected.
It should be noted that, in the whole air extraction process, the whole process needs to be kept at a temperature of more than 180 degrees or at a corresponding acid dew point to prevent the aggregation on the pipeline, and the material needs to be selected from PFA material/grade stainless steel of more than 316L.
In one embodiment, the apparatus further comprises: and the neutralizing unit is used for removing acidic substances in the mercury-containing flue gas. Under the condition that the acid concentration in the sample gas is too high, a trace amount of strong base reagent such as sodium hydroxide or potassium hydroxide solution is added into the flue gas through a peristaltic pump to neutralize acidic substances such as sulfur dioxide and the like in the sample gas so as to prevent the acidic substances from influencing the catalytic efficiency of the reaction unit.
In one embodiment, the apparatus further comprises: and the water removal unit 4 is used for cooling and dehumidifying the flue gas output by the reaction unit. After the dewatering unit is used, the rear-end pipeline and the measuring unit can be prevented from being polluted, and the measuring precision is improved. In addition, the water removal unit can also remove residual partial acidic substances. The dewatering unit can be a condensing device such as a condenser.
In one embodiment, the apparatus further comprises: and the dilution unit is used for diluting the high-concentration sample gas. The dilution unit is essentially a gas-carrying generator, the carrier gas can be nitrogen and the gas-carrying quantity is adjusted by using a mass flow controller, and outlets are arranged at two ends, one end of the carrier gas is connected with the sampling unit, the other end of the carrier gas is connected with the reaction unit, the dilution action principle is that the carrier gas with the same air suction quantity as the rear-end flow path can be introduced into the flue gas under the condition of overhigh mercury content in the flue gas, so that the sample gas is diluted, the measured elemental mercury content is displayed twice, and the actual value of the high-concentration mercury-containing flue gas can be obtained under the condition of not losing the precision of the measurement unit. The control (on or off) of the dilution unit may be via a PLC module or other control unit.
In one embodiment, the apparatus further comprises: and the purging unit is used for purging the reaction unit. The purging unit is also a gas-carrying generator in nature, and has the action principle that after normal sampling is carried out for a period of time, a part of elemental mercury is adsorbed and slowly desorbed in the reaction unit due to the existence of filling materials, and the purging unit is started to purge the part of elemental mercury to the outside of the reaction unit in the time of stopping sampling, so that the purity of a flow path is ensured and the subsequent measurement is not interfered. Control (on or off) of the purge unit may be via a PLC module or other control unit.
In an embodiment, the purge unit and the dilution unit may be the same device, such as the dilution/purge unit 3.
In one embodiment, the apparatus further comprises: and the calibration unit is used for generating oxidized mercury standard gas to calibrate the reaction unit and the measurement unit. The calibration unit adds the mercuric chloride standard liquid with fixed concentration into the evaporator through the peristaltic pump, the mercuric chloride standard liquid is vaporized through the evaporator, the mercuric chloride standard liquid is mixed with the carrier gas according to a certain proportion to generate oxidized mercury standard gas with corresponding concentration, the oxidized mercury standard gas enters the reaction unit to be converted into elemental mercury standard gas with known concentration, and the elemental mercury standard gas is compared with theoretical concentration after a measurement value is output by the measurement unit, so that the verification of the catalytic efficiency of the reaction unit and the calibration of the range attenuation of the measurement unit are realized.
In one embodiment, the apparatus may further comprise a switching unit 8 connecting the sampling unit, the calibration unit, the reaction unit and the neutralization unit. The switching unit can be a three-way valve, and a valve core of the three-way valve is made of PFA materials and is kept at a temperature of more than 180 degrees to prevent mercury from being adsorbed in the process.
In one embodiment, the switching unit, the sampling unit, the calibration unit, the reaction unit and the neutralization unit can be controlled to be turned on, turned off and switched by one control unit 2. The control unit is used for controlling the opening direction of the three-way valve and further switching the measurement state, controlling the opening and closing of the neutralization unit and further controlling the addition of a strong base reagent into the sample gas, controlling the timing opening of the calibration unit and further calibrating the reaction unit and the measurement unit, controlling the opening of the dilution unit/purging unit and further opening the high-concentration dilution of the flue gas or the purging of the reaction unit, and the control unit can select a PLC module or other control units.
It will be apparent to those skilled in the art that, for convenience and brevity of description, only the above-mentioned division of the functional units and modules is illustrated, and in practical applications, the above-mentioned function distribution may be performed by different functional units and modules according to needs, that is, the internal structure of the apparatus is divided into different functional units or modules to perform all or part of the above-mentioned functions. Each functional unit and module in the embodiments may be integrated in one processing unit, or each unit may exist alone physically, or two or more units are integrated in one unit, and the integrated unit may be implemented in a form of hardware, or in a form of software functional unit. In addition, specific names of the functional units and modules are only for convenience of distinguishing from each other, and are not used for limiting the protection scope of the present application. The specific working processes of the units and modules in the system may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.
In the above embodiments, the descriptions of the respective embodiments have respective emphasis, and reference may be made to the related descriptions of other embodiments for parts that are not described or illustrated in a certain embodiment.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.
Claims (9)
1. An apparatus for measuring mercury in flue gas, comprising:
the sampling unit is used for sampling the mercury-containing flue gas;
the reaction unit is used for converting oxidized mercury in the mercury-containing flue gas into elemental mercury and outputting the mercury-containing flue gas only containing the elemental mercury;
and the measuring unit is used for detecting elemental mercury in the mercury-containing flue gas output by the reaction unit.
2. The apparatus for measuring mercury in flue gas according to claim 1, further comprising: and the neutralizing unit is used for removing acidic substances in the mercury-containing flue gas.
3. The apparatus for measuring mercury in flue gas according to claim 1, further comprising: and the water removal unit is used for cooling and dehumidifying the flue gas output by the reaction unit.
4. The apparatus for measuring mercury in flue gas according to claim 1, further comprising: and the dilution unit is used for diluting the high-concentration sample gas.
5. The apparatus for measuring mercury in flue gas according to claim 1, further comprising: and the purging unit is used for purging the reaction unit.
6. The apparatus for measuring mercury in flue gas according to claim 1, further comprising: and the calibration unit is used for generating oxidized mercury standard gas to calibrate the reaction unit and the measurement unit.
7. The apparatus for measuring mercury in flue gas according to claim 1, further comprising: and the air extraction unit is used for extracting the mercury-containing flue gas in the flue to the sampling unit.
8. The device for measuring mercury in flue gas according to claim 1, wherein the measuring unit detects elemental mercury in the mercury-containing flue gas output by the reaction unit based on cold vapor atomic absorption spectrophotometry.
9. The device for measuring mercury in flue gas according to claim 1, wherein the sampling unit comprises a probe, a probe head and a heat tracing band, one end of the probe head is inserted into the flue to be vertical to the flow direction of flue gas, and the other end of the probe head is connected with the probe head for collecting sample gas; one end of the heat tracing band is connected with the probe, and the other end of the heat tracing band is connected with the switching unit for transmitting the sample gas, and the heat tracing band, the probe and the switching unit are horizontally connected.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010253876.2A CN111307744A (en) | 2020-04-02 | 2020-04-02 | Device for measuring mercury in flue gas |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010253876.2A CN111307744A (en) | 2020-04-02 | 2020-04-02 | Device for measuring mercury in flue gas |
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| CN111307744A true CN111307744A (en) | 2020-06-19 |
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| CN202010253876.2A Pending CN111307744A (en) | 2020-04-02 | 2020-04-02 | Device for measuring mercury in flue gas |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113959792A (en) * | 2021-10-25 | 2022-01-21 | 西安热工研究院有限公司 | Device and method for measuring mercury in flue gas based on low-temperature plasma pyrolysis |
-
2020
- 2020-04-02 CN CN202010253876.2A patent/CN111307744A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113959792A (en) * | 2021-10-25 | 2022-01-21 | 西安热工研究院有限公司 | Device and method for measuring mercury in flue gas based on low-temperature plasma pyrolysis |
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