CN101865905B - Mercury concentration on-line detection method in smoke gas - Google Patents

Abstract

The invention provides a mercury concentration on-line detection method in smoke gas. The method of the invention comprises the following steps: carrying out on-line sampling in a smoke gas pipeline; firstly, using a water treatment solution for carrying out reaction and dust removal treatment on the smoke gas; then, introducing the treated smoke gas into a Zeeman effect mercury analysis instrument to be measured; and obtaining the total mercury concentration in the smoke gas through respectively measuring and calculating the water-soluble mercury concentration in the water treatment solution, the mercury concentration in the smoke gas after the reaction and dust removal treatment and the mercury concentration in insoluble smoke dust precipitates. The method adopts a method of on-line sampling and on-line test, does not influence the treatment of the actual engineering on the coal-fired smoke gas, and does not need spun gold enrichment preliminary treatment with high cost, so the relevant problems of spun gold enrichment can be eliminated, and the cost is saved. At the same time, the invention avoids the influence of the dust on the Zeeman effect mercury analysis instrument, truly reflects the removal rate on the soluble mercury in the smoke gas in the wet method desulfurization process in coal-fired power plants, and has the directive significance to the demercuration purification of the coal-fired smoke gas in the actual engineering.

Description

The mercury in flue gas concentration on-line detection method

Technical field

The present invention relates to mercury concentration on-line detection method in the power plant soot fume, belong to environmental protection technical field.

Background technology

Mercury is one of the most volatile trace element in the coal, and burning of coal is the main source of mercury in the atmosphere.The mercury content of different regions, Coal rank is different.The research discovery, the average mercury content of coal in China is 0.22mg/Kg.4.16 trillion tons of China's fossil fuel total resources, wherein coal just accounts for 95.6%.For a long time, in the energy production and consumption structure of China, coal is occupied an leading position always, and this general layout will can not change within longer a period of time.The fuel-burning power plant Coal-fired capacity accounts for about 40% of coal consumption amount.Therefore, coal fired power plant becomes maximum mercury pollution source, according to statistics, accounts for 33% of mercury emissions total amount.1978～nineteen ninety-five, the accumulation of Coal Combustion in China mercury emissions reaches 2500t, and annual speedup is 4.8%.Only 2000, China's Mercury Emissions from Coal-Fired Boilers amount reached 273t.Because the time that mercury has hypertoxicity, accumulation property, stop in atmosphere is long, if directly be discharged in the atmosphere, will inevitably bring serious harm to environment and the mankind's health.Therefore, mercury pollution control more and more is subject to people's attention.The emission and control of relevant mercury has become an emerging research field in the coal combustion prevention and cure of pollution.

Mercury in the flue gas mainly contains three kinds of forms: gaseous state nonvalent mercury (Hg ⁰(g)), gaseous state divalence mercury (Hg ²⁺And particle mercury (Hg (p)) (g)).Because Hg ²⁺Compound soluble in water, Hg (p) is easily caught by fly-ash separator, so the mercury of these two kinds of forms is removed than being easier to.And Hg ⁰Fusing point is low, and equilibrium vapour pressure is high, is insoluble in water, is a kind of more high-volatile pollutant, thereby is difficult for being caught by fly-ash separator, and major part enters in the atmosphere with flue gas, is the emphasis of mercury pollution control.Mercury speciation is to mercury removal efficient and select demercuration equipment that material impact is arranged.Therefore, concentration and the form of measuring and analyze mercury in flue gas distribute, and be significant to discharging and the control technology of research mercury.

Because measure the urgency that the form of Mercury In Coal Combustion Flue Gas distributes and needs, the researcher has carried out fruitful work on the one hand at this, has proposed many measuring methods.These methods can be summed up as two large classes: first class is sampling analysis method, wherein can be divided into again liquid adsorption method (EPA method 29 and EPA method 101A etc.), solid adsorbent method (mercury shape absorption method (MESA), MIT solid adsorbent method), harmful element sampling chain (HEST), diffuser screen and anemostat technology, the sample of collecting is used CVAFS again, and INAA and XRF measure; Second largest class is the on-line analysis method, and they are based on AAS, CVAAS, CVAFS and the novel advanced technologies such as chemical microsensor are set up, along with continuous development, these instruments are expected to apply to the mercury in continuous monitoring flue gas and the exhaust, and these class methods are emerging focuses of research.

In the existing detection technique, the detection method of mercury in flue gas content mainly be by absorption method with the absorption of the mercury in the flue gas after, then adopt the high temperature pyrolytic cracking (HTP) desorption after, measure by the mercury detecting instrument again; Perhaps directly by the mixed solution of configuration dilute sulfuric acid and potassium permanganate, by oxidizing process mercury all in the flue gas is dissolved in the mixed liquor, then uses mercury analyzing and testing measuring apparatus.Above-mentioned two kinds of methods can't realize the online detection of mercury in flue gas concentration, and testing process is complicated, and error is larger, and more important is to analyze large flow coal-fired flue-gas.

Summary of the invention

For the prior art above shortcomings, the object of the present invention is to provide that a kind of detection method is simple, cost is low, method highly sensitive, that mercury in flue gas concentration is detected online, in order to utilize testing result to instruct that the demercuration to coal-fired flue-gas purifies in the Practical Project.

The object of the present invention is achieved like this: a kind of mercury in flue gas concentration on-line detection method comprises the steps:

(1) online sampling from flue, the flue gas of control sampling passes into water treatment solution in the graduated vessels and beginning timing with the flow velocity of α L/min; Flue gas after water treatment solution reaction and dust removal process passes into the Zeeman effect mercury analyzer again, for detection of mercury content wherein; Described α value is 20～30; The measuring accuracy of described graduated vessels is 1ml, and the water treatment solution volume in the graduated vessels is 20～50L; The accuracy of detection of described Zeeman effect mercury analyzer is 1ng/m ³

Described water treatment solution is a kind of in the following solution:

1. in deionized water, add the solution that the 1mol/L sodium acetate solution is regulated pH value to 3.8～4.2;

2. percentage by weight is 10% CaCO ₃Solution;

(2) the beginning timing reacted stable after 3～6 minutes, and then supernatant 50ml was got at every interval in 10 minutes from water treatment solution, detected the mercury concentration of the supernatant of getting, and detecting step is as follows:

The 50ml supernatant that takes out is placed beaker, then add 10%H ₂SO ₄And 4%KMnO ₄1: 1 by volume mixed solution 10ml, solution is measured in conduct after fully mixing; Utilize mercury analyzer to detect water-soluble attitude mercury concentration ρ in the described mensuration solution ₁', unit is ug/L; The mercury concentration ρ of the 50ml supernatant that obtains from water treatment solution, getting through conversion ₁, unit is ug/L;

(3) read the actual volume V of water treatment solution in the graduated vessels, calculate the before this mercury concentration difference DELTA ρ of adjacent twice supernatant of getting from water treatment solution ₁, unit is ug/L; Then, calculate water-soluble attitude mercury concentration Λ in the flue gas with following formula ₁, unit is ug/m ³:

${\mathrm{\Λ}}_1=\frac{{\mathrm{\Δ\ρ}}_1\×V}{10\mathrm{\α}}\×1000;$

(4) read the detected value of Zeeman effect mercury analyzer, draw the mercury concentration Λ in the flue gas after water treatment solution reaction and dust removal process ₂, unit is ug/m ³

(5) all deposits in the water treatment solution are extracted in beginning timing after 2 hours, and with washed with de-ionized water twice, the mass M of the accurate described deposit of weighing after drying, and unit is g;

(6) accurately take by weighing the 10g deposit as the precipitation sample, adding deionized water 20ml fully mixes, then by hydro-extractor high speed centrifugation 5min, remove and add again deionized water 20ml after the supernatant and fully mix, high speed centrifugation 5min again, remove supernatant, the precipitation sample of remainder is transferred in the quartz boat, utilize mercury analyzer to detect mercury concentration ρ in the precipitation sample ₃, the ng/g of unit; Then calculate the mercurous concentration Λ of indissoluble flue dust in the flue gas with following formula ₃, unit is ug/m ³:

${\mathrm{\Λ}}_3=\frac{{\mathrm{\ρ}}_3\×M}{120\mathrm{\α}};$

(7) summation draws the total mercury concentration Λ in the flue gas _Always, the ug/m of unit ³:

Λ _Always=Λ ₁+ Λ ₂+ Λ ₃

Compared to existing technology, the present invention has following beneficial effect:

1, online sampling, on-line testing does not affect the combustion Practical Project to the processing of coal-fired flue-gas;

2, do not need to carry out the spun gold enrichment pre-treatment of cost costliness, therefore can eliminate the relevant issues of spun gold enrichment, and save cost;

3, the present invention utilizes first water treatment solution that flue gas is reacted and dust removal process, again the flue gas after processing being passed into the Zeeman effect mercury analyzer measures, not only avoided the impact of dust on the Zeeman effect mercury analyzer, also truly reflected in the coal-burning power plant process of wet desulphurization for the clearance of soluble mercury in the flue gas, purified for the demercuration of coal-fired flue-gas in the Practical Project and have directive significance.

Embodiment

Below in conjunction with embodiment the present invention is described in further detail.

Embodiment one:

The present embodiment is the opening bypass conduit road in the coal-fired flue-gas pipeline of Si Chuandu city coal field, with the gas sampled flow velocity in the gas flow-control by-pass line, utilize the mercury concentration in the inventive method on-line testing Si Chuandu city coal field coal-fired flue-gas, concrete testing procedure is as follows:

(1) by by-pass line online sampling from flue, the flue gas of control sampling passes into 20L water treatment solution in the graduated vessels with the flow velocity of 20L/min, reacts and dust removal process, begins simultaneously timing, and timing this moment is 0; Water treatment solution in the graduated vessels is to add the solution that the 1mol/L sodium acetate solution is regulated pH value to 3.8～4.2 in deionized water.Then, again the flue gas after water treatment solution reaction and dust removal process is passed into the Zeeman effect mercury analyzer, for detection of mercury content wherein; The accuracy of detection of Zeeman effect mercury analyzer is 1ng/m ³

(2) the beginning timing was reacted stable after 3 minutes.When timing is 5 minutes, from water treatment solution, get supernatant 50ml for the first time and place beaker, then add 10%H ₂SO ₄And 4%KMnO ₄1: 1 by volume mixed solution 10ml fully mixes rear as measuring for the first time solution; The RA-915+ type mercury analyzer and the fluid sample analysis annex RP-91 (also can adopt other mercury analyzer of technology maturation) thereof that utilize Russian Lumex company to produce detect and obtain measuring for the first time water-soluble attitude mercury concentration ρ in the solution _1,1' be 4.58 * 10 ^-3Ug/L; Owing to measure the total 60ml of solution for the first time, and the supernatant of getting for the first time being 50ml, therefore converts 4.58 * 10 from water treatment solution ^-3Ug/L * 60ml ÷ 50ml, the mercury concentration ρ in the 50ml supernatant that obtains from water treatment solution, getting for the first time _1,1Be about 5.5 * 10 ^-3Ug/L;

After 10 minutes, be i.e. when timing is 15 minutes, from water treatment solution, gets supernatant 50ml for the second time again and place beaker, add 10%H ₂SO ₄And 4%KMnO ₄1: 1 by volume mixed solution 10ml fully mixes rear as measuring for the second time solution; With RA-915+ type mercury analyzer and the fluid sample analysis annex RP-91 (also can adopt other mercury analyzer of technology maturation) thereof that Russian Lumex company produces, detect and obtain measuring for the second time water-soluble attitude mercury concentration ρ in the solution _1,2' be 20.50 * 10 ^-3Ug/L; Convert 20.50 * 10 ^-3Ug/L * 60ml ÷ 50ml, the mercury concentration ρ in the 50ml supernatant that obtains from water treatment solution, getting for the second time _1,2Be about 24.6 * 10 ^-3Ug/L.

(3) the actual volume V that reads water treatment solution in the graduated vessels is 19.9L, before this mercury concentration difference DELTA ρ of adjacent twice supernatant of getting from water treatment solution ₁=ρ _1,2-ρ _1,1=19.1 * 10 ^-3Then ug/L calculates water-soluble attitude mercury concentration Λ in the flue gas with following formula ₁, unit is ug/m ³:

${\mathrm{\Λ}}_1=\frac{{\mathrm{\Δ\ρ}}_1\×V}{10\min \×20L/\min }\×1000=\frac{19.1\×{10}^{-3}\mathrm{ug}/L\×19.9L}{10\min \×20L/\min }\×1000\≈1.9\mathrm{ug}/m^3.$

(4) read the detected value of Zeeman effect mercury analyzer, draw the mercury concentration Λ in the flue gas after water treatment solution reaction and dust removal process ₂Be 3.8ug/m ³

(5) all deposits in the water treatment solution are extracted in beginning timing after 2 hours, and with washed with de-ionized water twice, the mass M of the accurate described deposit of weighing is 32.0g after drying.

(6) accurately take by weighing the 10g deposit as the precipitation sample, add deionized water 20ml and fully mix, then by hydro-extractor high speed centrifugation 5min, remove and add again deionized water 20ml after the supernatant and fully mix, high speed centrifugation 5min again, ultracentrifugal speed is 3500 to turn/min; Then remove supernatant, the precipitation sample of remainder is transferred in the quartz boat, the RA-915+ type mercury analyzer and the solid sample test accessories RP-91C (also can adopt other mercury analyzer of technology maturation) thereof that utilize Russian Lumex company to produce detect and are precipitated mercury concentration ρ in the sample ₃Be 90ng/g; Then calculate the mercurous concentration Λ of indissoluble flue dust in the flue gas with following formula ₃, the ug/m of unit ³:

${\mathrm{\Λ}}_3=\frac{{\mathrm{\ρ}}_3\×M}{120\mathrm{\α}}=\frac{90\mathrm{ng}/g\×32g}{120\min \×20L/\min }=1.2\mathrm{ng}/L=1.2\mathrm{ug}/m^3.$

(7) summation draws the total mercury concentration Λ in the flue gas _Always:

Λ _Always=Λ ₁+ Λ ₂+ Λ ₃=1.9ug/m ³+ 3.8ug/m ³+ 1.2ug/m ³=6.9ug/m ³

The online detection learns that the mercury concentration in the Si Chuandu city coal field coal-fired flue-gas is 6.9ug/m thus ³

Embodiment two:

The present embodiment is the opening bypass conduit road in the coal-fired flue-gas pipeline in Qijiang County, Chongqing City pine algae ore deposit, with the gas sampled flow velocity in the gas flow-control by-pass line, utilize the mercury concentration in the coal-fired flue-gas of the inventive method on-line testing Qijiang County, Chongqing City pine algae ore deposit, concrete testing procedure is as follows:

(1) by by-pass line online sampling from flue, the flue gas of control sampling passes into 50L water treatment solution in the graduated vessels with the flow velocity of 30L/min, reacts and dust removal process, begins simultaneously timing, and timing this moment is 0; Water treatment solution in the graduated vessels is that percentage by weight is 10% CaCO ₃Solution.Then, again the flue gas after water treatment solution reaction and dust removal process is passed into the Zeeman effect mercury analyzer, for detection of mercury content wherein; The accuracy of detection of Zeeman effect mercury analyzer is 1ng/m ³

(2) the beginning timing was reacted stable after 5 minutes.When timing is 11 minutes, from water treatment solution, get supernatant 50ml for the first time and place beaker, then add 10%H ₂SO ₄And 4%KMnO ₄1: 1 by volume mixed solution 10ml fully mixes rear as measuring for the first time solution; The RA-915+ type mercury analyzer and the fluid sample analysis annex RP-91 (also can adopt other mercury analyzer of technology maturation) thereof that utilize Russian Lumex company to produce detect and obtain measuring for the first time water-soluble attitude mercury concentration ρ in the solution _1,1' be 9.75 * 10 ^-3Ug/L; Owing to measure the total 60ml of solution for the first time, and the supernatant of getting for the first time being 50ml, therefore converts 9.75 * 10 from water treatment solution ^-3Ug/L * 60ml ÷ 50ml, the mercury concentration ρ in the 50ml supernatant that obtains from water treatment solution, getting for the first time _1,1Be about 11.7 * 10 ^-3Ug/L.

After 10 minutes, be i.e. when timing is 21 minutes, from water treatment solution, gets supernatant 50ml for the second time again and place beaker, add 10%H ₂SO ₄And 4%KMnO ₄1: 1 by volume mixed solution 10ml fully mixes rear as measuring for the second time solution; With RA-915+ type mercury analyzer and the fluid sample analysis annex RP-91 (also can adopt other mercury analyzer of technology maturation) thereof that Russian Lumex company produces, detect and obtain measuring for the second time water-soluble attitude mercury concentration ρ in the solution ₁₂' be 22.25 * 10 ^-3Ug/L; Convert 22.25 * 10 ^-3Ug/L * 60ml ÷ 50ml, the mercury concentration ρ in the 50ml supernatant that obtains from water treatment solution, getting for the second time _1,2Be about 26.7 * 10 ^-3Ug/L.

(3) the actual volume V that reads water treatment solution in the graduated vessels is 49.9L, before this mercury concentration difference DELTA ρ of adjacent twice supernatant of getting from water treatment solution ₁=ρ _1,2-ρ _1,1=15.0 * 10 ^-3Then ug/L calculates water-soluble attitude mercury concentration Λ in the flue gas with following formula ₁, unit is ug/m ³:

${\mathrm{\Λ}}_1=\frac{{\mathrm{\Δ\ρ}}_1\×V}{10\mathrm{\α}}\×1000=\frac{15.0\×{10}^{-3}\mathrm{ug}/L\×49.9L}{10\min \×30L/\min }\×1000\≈2.5\mathrm{ug}/m^3.$

(4) read the detected value of Zeeman effect mercury analyzer, draw the mercury concentration Λ in the flue gas after water treatment solution reaction and dust removal process ₂Be 5.1ug/m ³

(5) all deposits in the water treatment solution are extracted in beginning timing after 2 hours, and with washed with de-ionized water twice, the mass M of the accurate described deposit of weighing is 56.3g after drying.

(6) accurately take by weighing the 10g deposit as the precipitation sample, add deionized water 20ml and fully mix, then by hydro-extractor high speed centrifugation 5min, remove and add again deionized water 20ml after the supernatant and fully mix, high speed centrifugation 5min again, ultracentrifugal speed is 5000 to turn/min; Then remove supernatant, the precipitation sample of remainder is transferred in the quartz boat, the RA-915+ type mercury analyzer and the solid sample test accessories RP-91C (also can adopt other mercury analyzer of technology maturation) thereof that utilize Russian Lumex company to produce detect and are precipitated mercury concentration ρ in the sample ₃Be 128ng/g; Then calculate the mercurous concentration Λ of indissoluble flue dust in the flue gas with following formula ₃, the ug/m of unit ³:

${\mathrm{\Λ}}_3=\frac{{\mathrm{\ρ}}_3\×M}{120\mathrm{\α}}=\frac{128\mathrm{ng}/g\×56.3g}{120\min \×30L/\min }\×2.0\mathrm{ng}/L=2.0\mathrm{ug}/m^3.$

(7) summation draws the total mercury concentration Λ in the flue gas _Always:

Λ _Always=Λ ₁+ Λ ₂+ Λ ₃=2.5ug/m ³+ 5.1ug/m ³+ 2.0ug/m ³=9.6ug/m ³

Online detection learns that the mercury concentration in the coal-fired flue-gas of Qijiang County, Chongqing City pine algae ore deposit is 9.6ug/m thus ³

Utilize the inventive method, the coal-fired flue-gas that a plurality of coal fields such as colliery are newly won in Si Chuandu city, Qijiang County, Chongqing City pine algae ore deposit, Qinglong (Blue Dragon) Temple colliery, Yongchuan, Chongqing, Yongchuan, Chongqing has carried out mercury concentration and has detected online, and it is as shown in the table that each detects data:

The inventive method does not need to carry out the spun gold enrichment pre-treatment of cost costliness, therefore can eliminate the relevant issues of spun gold enrichment, saves cost.The inventive method has adopted the high Zeeman effect mercury analyzer of measuring accuracy to measure mercury in flue gas concentration, but owing to having a large amount of dust in the flue gas, if directly measure flue gas with the Zeeman effect mercury analyzer, dust can have a strong impact on the precision of measuring the Zeeman effect mercury analyzer.Therefore, the present invention utilizes first water treatment solution that flue gas is reacted and dust removal process, again the flue gas after processing is passed into the Zeeman effect mercury analyzer and measures.Like this, not only avoided the impact of dust on the Zeeman effect mercury analyzer, reflected truly that also process of wet desulphurization has directive significance for the clearance of soluble mercury in the flue gas for Practical Project in the coal-burning power plant.Simultaneously, the Zeeman effect mercury analyzer has adopted Zeeman background calibration technology, has realized the glitch-free highly sensitive detection of sample compound.And the online sampling of the inventive method is tested, and the integrated testability process only needs 2 hours consuming time, has realized the online detection to Mercury In Coal Combustion Flue Gas content.(needed 2 hours just can obtain net result, be referred to as on-line testing? perhaps, can say because be online sampling, so be referred to as on-line testing.)

Explanation is at last, above embodiment is only unrestricted in order to technical scheme of the present invention to be described, although with reference to preferred embodiment the present invention is had been described in detail, those of ordinary skill in the art is to be understood that, can make amendment or be equal to replacement technical scheme of the present invention, and not breaking away from aim and the scope of technical solution of the present invention, it all should be encompassed in the middle of the claim scope of the present invention.

Claims (1)

1. a mercury in flue gas concentration on-line detection method is characterized in that comprising the steps:

(1) online sampling from flue, the flue gas of control sampling passes into water treatment solution in the graduated vessels and beginning timing with the flow velocity of α L/min; Flue gas after water treatment solution reaction and dust removal process passes into the Zeeman effect mercury analyzer again, for detection of mercury content wherein;

Described α value is 20～30; The measuring accuracy of described graduated vessels is 1ml, and the water treatment solution volume in the graduated vessels is 20～50L; The accuracy of detection of described Zeeman effect mercury analyzer is 1ng/m ³

Described water treatment solution is a kind of in the following solution:

1. in deionized water, add the solution that the 1mol/L sodium acetate solution is regulated pH value to 3.8～4.2;

2. percentage by weight is 10% CaCO ₃Solution;

(2) the beginning timing reacted stable after 3～6 minutes, and then supernatant 50ml was got at every interval in 10 minutes from water treatment solution, detected the mercury concentration of the supernatant of getting, and detecting step is as follows:

The 50ml supernatant that takes out is placed beaker, then add 10%H ₂SO ₄And 4%KMnO ₄1: 1 by volume mixed solution 10ml, solution is measured in conduct after fully mixing; Utilize the second mercury analyzer to detect water-soluble attitude mercury concentration ρ in the described mensuration solution ₁', unit is ug/L; The mercury concentration ρ of the 50ml supernatant that obtains from water treatment solution, getting through conversion ₁, unit is ug/L;

(3) read the actual volume V of water treatment solution in the graduated vessels, calculate the before this mercury concentration difference DELTA ρ of adjacent twice supernatant of getting from water treatment solution ₁, unit is ug/L; Then, calculate water-soluble attitude mercury concentration Λ in the flue gas with following formula ₁, unit is ug/m ³:

${\mathrm{\Λ}}_1=\frac{{\mathrm{\Δ\ρ}}_1\×V}{10\mathrm{\α}}\×1000;$

(4) read the detected value of Zeeman effect mercury analyzer, draw the mercury concentration Λ in the flue gas after water treatment solution reaction and dust removal process ₂, unit is ug/m ³

(5) all deposits in the water treatment solution are extracted in beginning timing after 2 hours, and with washed with de-ionized water twice, the mass M of the accurate described deposit of weighing after drying, and unit is g;

(6) accurately take by weighing the 10g deposit as the precipitation sample, adding deionized water 20ml fully mixes, then by hydro-extractor high speed centrifugation 5min, remove and add again deionized water 20ml after the supernatant and fully mix, high speed centrifugation 5min again, remove supernatant, the precipitation sample of remainder is transferred in the quartz boat, utilize the second mercury analyzer to detect mercury concentration ρ in the precipitation sample ₃, the ng/g of unit; Then calculate the mercurous concentration Λ of indissoluble flue dust in the flue gas with following formula ₃, unit is ug/m ³:

${\mathrm{\Λ}}_3=\frac{{\mathrm{\ρ}}_3\×M}{120\mathrm{\α}};$

(7) summation draws the total mercury concentration Λ in the flue gas _Always, the ug/m of unit ³:

Λ _Always=Λ ₁+ Λ ₂+ Λ ₃