CN101865905A - 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

Mercury concentration on-line detection method in the flue gas

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, different coals is different.Discover that 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 in 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, Chinese coal-fired mercury emissions accumulation reaches 2500t, and annual speedup is 4.8%.Only 2000, the coal-fired mercury emission of China 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 human beings'health.Therefore, mercury pollution control more and more is subject to people's attention.The discharging of relevant mercury and control have 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 the equilibrium vapour pressure height 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.The form of mercury distributes to mercury removal efficient and selects demercuration equipment that material impact is arranged.Therefore, concentration and the form of measuring and analyze mercury in the flue gas distribute, and be significant to the discharging and the control technology of research mercury.

Because measure the urgency that the form of mercury in the coal-fired 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 big classes: first class is a sampling analysis method, wherein can be divided into 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 again, 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 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, in the flue gas detection method of mercury content mainly be by absorption method with the absorption of the mercury in the flue gas after, adopt the high temperature pyrolytic cracking (HTP) desorption then after, measure by the mercury detecting instrument again; Perhaps, mercury all in the flue gas is dissolved in the mixed liquor, uses mercury analyzing and testing measuring apparatus then by oxidizing process directly by the mixed solution of configuration dilute sulfuric acid and potassium permanganate.Above-mentioned two kinds of methods can't realize the online detection of mercury concentration in the flue gas, and the testing process complexity, and error is bigger, and more important is to analyze big flow coal-fired flue-gas.

Summary of the invention

At 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, highly sensitive, mercury concentration in the flue gas is carried out on-line detection method, so that utilize testing result to instruct that the demercuration to coal-fired flue-gas purifies in the actual engineering.

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

(1) online sampling from flue, the flue gas of control sampling feeds water treatment solution in the graduated vessels with the flow velocity of α L/min, and picks up counting; Flue gas after water treatment solution reaction and dust removal process feeds the Zeeman effect mercury analyzer again, is used to detect 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) picked up counting 3～6 minutes after, react stable, supernatant 50ml was got at every then interval in 10 minutes from water treatment solution, detect the mercury concentration of the supernatant of getting, the detection step is as follows:

The 50ml supernatant that takes out is placed beaker, add 10%H then ₂SO ₄And 4%KMnO ₄1: 1 by volume mixed solution 10ml fully mixes the back as measuring solution; 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 being got through conversion ₁, unit is ug/L;

(3) read the actual volume V of water treatment solution in the graduated vessels, calculate the mercury concentration difference DELTA ρ of adjacent before this 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) picked up counting 2 hours after, extract all deposits in the water treatment solution, and with washed with de-ionized water twice, the mass M of the accurate described deposit of weighing after drying, 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 deionized water 20ml again 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; Calculate the mercurous concentration Λ of indissoluble flue dust in the flue gas with following formula then 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 influence the processing of the actual engineering of combustion to 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 water treatment solution that flue gas is reacted and dust removal process earlier, again the flue gas after handling being fed the Zeeman effect mercury analyzer measures, not only avoided the influence of dust to 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 actual engineering and have directive significance.

Embodiment

Below in conjunction with embodiment the present invention is done to describe in further detail.

Embodiment one:

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 reacts and dust removal process with the 20L water treatment solution in the flow velocity feeding graduated vessels of 20L/min, picks up counting simultaneously, 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 fed the Zeeman effect mercury analyzer, be used to detect mercury content wherein; The accuracy of detection of Zeeman effect mercury analyzer is 1ng/m ³

(2) picked up counting 3 minutes after, react stable.When timing is 5 minutes, from water treatment solution, get supernatant 50ml for the first time and place beaker, add 10%H then ₂SO ₄And 4%KMnO ₄1: 1 by volume mixed solution 10ml fully mixes the back 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 being got for the first time is 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, being got 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 the back 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, being got 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, the mercury concentration difference DELTA ρ of adjacent before this twice supernatant of getting from water treatment solution ₁=ρ _1,2-ρ _1,1=19.1 * 10 ^-3Ug/L calculates water-soluble attitude mercury concentration Λ in the flue gas with following formula then 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) picked up counting 2 hours after, extract all deposits in the water treatment solution, 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,, remove and add deionized water 20ml again after the supernatant and fully mix then by hydro-extractor high speed centrifugation 5min, high speed centrifugation 5min again, ultracentrifugal speed is 3500 commentaries on classics/min; Remove supernatant then, 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 obtain precipitating mercury concentration ρ in the sample ₃Be 90ng/g; Calculate the mercurous concentration Λ of indissoluble flue dust in the flue gas with following formula then 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

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

Embodiment two:

Present embodiment is the opening bypass conduit road in the coal-fired flue-gas pipeline in Chongqing Qijiang 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 Qijiang pine algae ore deposit, the inventive method on-line testing Chongqing, concrete testing procedure is as follows:

(1) by by-pass line online sampling from flue, the flue gas of control sampling reacts and dust removal process with the 50L water treatment solution in the flow velocity feeding graduated vessels of 30L/min, picks up counting simultaneously, 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 fed the Zeeman effect mercury analyzer, be used to detect mercury content wherein; The accuracy of detection of Zeeman effect mercury analyzer is 1ng/m ³

(2) picked up counting 5 minutes after, react stable.When timing is 11 minutes, from water treatment solution, get supernatant 50ml for the first time and place beaker, add 10%H then ₂SO ₄And 4%KMnO ₄1: 1 by volume mixed solution 10ml fully mixes the back 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 being got for the first time is 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, being got 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 the back 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, being got 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, the mercury concentration difference DELTA ρ of adjacent before this twice supernatant of getting from water treatment solution ₁=ρ _1,2-ρ _1,1=15.0 * 10 ^-3Ug/L calculates water-soluble attitude mercury concentration Λ in the flue gas with following formula then 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) picked up counting 2 hours after, extract all deposits in the water treatment solution, 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,, remove and add deionized water 20ml again after the supernatant and fully mix then by hydro-extractor high speed centrifugation 5min, high speed centrifugation 5min again, ultracentrifugal speed is 5000 commentaries on classics/min; Remove supernatant then, 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 obtain precipitating mercury concentration ρ in the sample ₃Be 128ng/g; Calculate the mercurous concentration Λ of indissoluble flue dust in the flue gas with following formula then 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 thus detection learns that the mercury concentration in the coal-fired flue-gas of Qijiang pine algae ore deposit, Chongqing is 9.6ug/m ³

Utilize the inventive method, the coal-fired flue-gas that Si Chuandu city, Chongqing Qijiang pine algae ore deposit, Qinglong (Blue Dragon) Temple colliery, Yongchuan, Chongqing, Yongchuan, Chongqing is newly won a plurality of coal fields such as colliery has carried out the online detection of mercury concentration, 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 concentration in the flue gas, but owing to have 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 water treatment solution that flue gas is reacted and dust removal process earlier, again the flue gas after handling is fed the Zeeman effect mercury analyzer and measures.Like this, not only avoided the influence of dust, reflected truly that also process of wet desulphurization has directive significance for the clearance of soluble mercury in the flue gas for actual engineering in the coal-burning power plant the Zeeman effect mercury analyzer.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 content in the coal-fired flue-gas.(needed 2 hours just can obtain net result, be referred to as on-line testing? perhaps, we 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 the present invention is had been described in detail with reference to preferred embodiment, 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 the 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. mercury concentration on-line detection method in the flue gas is characterized in that comprising the steps:

(1) online sampling from flue, the flue gas of control sampling feeds water treatment solution in the graduated vessels with the flow velocity of α L/min, and picks up counting; Flue gas after water treatment solution reaction and dust removal process feeds the Zeeman effect mercury analyzer again, is used to detect 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) picked up counting 3～6 minutes after, react stable, supernatant 50ml was got at every then interval in 10 minutes from water treatment solution, detect the mercury concentration of the supernatant of getting, the detection step is as follows:

The 50ml supernatant that takes out is placed beaker, add 10%H then ₂SO ₄And 4%KMnO ₄1: 1 by volume mixed solution 10ml fully mixes the back as measuring solution; 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 being got through conversion ₁, unit is ug/L;

(3) read the actual volume V of water treatment solution in the graduated vessels, calculate the mercury concentration difference DELTA ρ of adjacent before this 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) picked up counting 2 hours after, extract all deposits in the water treatment solution, and with washed with de-ionized water twice, the mass M of the accurate described deposit of weighing after drying, 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 deionized water 20ml again 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; Calculate the mercurous concentration Λ of indissoluble flue dust in the flue gas with following formula then 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