CN1995956A - Method and device for detecting SO3 content in flue gas - Google Patents

Abstract

The invention relates to the inspection method and sampling device for the SO3 content of the smoke released by thermal power plant boiler. The sampling device comprises the dust remover, sampling tube, spiral collecting tube and drawing device, with the dust remover at the input end of the sampling tube whose output connected with the input of the spiral collection tube, with the input and output ends of the spiral collection tube on the spiral, and the output connected with the drawing device through hoses. It collects SO3 of the smoke to the spiral collection tube, getting SO42 sample solution after treatment, with arsenazo III as the color developing agent, dropping with barium acetate solution to get the density of SO3. It is accurate, quick, and reliable, with every possible means to avoid heat waste due to improving acid dew point corrosion.

Description

SO in the flue gas 3Content detecting method and device thereof

Technical field

The present invention relates to the detection method of power plant boiler smoke components, particularly SO in the power plant boiler flue gas ₃Content detecting method and device thereof.

Background technology

The sulfurous fuel burning back of thermal power plant generates SO ₂And SO ₃National sulfur dioxide (SO2) emissions total amount was 2,549 ten thousand tons in 2005, exceeded 80% of atmospheric environment capacity, the sulfur dioxide (SO2) emissions total amount reaches the first in the world, wherein about half from the discharging of thermal power plant, cause acid rain district area to cover 1/3rd of area.And sulfur dioxide (SO2) emissions are to cause China's air environmental pollution and the increasing main cause of acid rain.The effective way that solves at present sulfur dioxide pollution is flue gas desulfurization, and limestone-gypsum wet desulphurization technology is at the most widely used the most ripe general desulfur technology of China.In practical sulphur removal engineering debug and day-to-day operation, all to test the desulfuration efficiency of flue gas, this just relates to measures SO in the flue gas ₂And SO ₃Content.SO ₂Can detect by general flue gas analyzer.

Still find no SO in the test boiler smoke at present ₃Method, and the flue gas analyzer that is widely used in fume component analysis is not analyzed SO ₃This function of content, this mainly is because SO ₃The moisture that absorbs in the flue gas can react generation sulfuric acid droplet rapidly, and this just may cause SO ₃In being transferred to the apparatus measures terminal procedures, can condensing and stick to and cause sampling error on the instrument transmission pipeline and instrument is produced strong corrosion with the sulfuric acid mist form.

SO in the flue gas ₃Though content seldom because SO ₃Very easily combine and form sulfuric acid vapor with water vapour in the flue gas.The adiabatic condensation temperature of sulfuric acid vapor is called acid dew point in the flue gas.Sulfuric acid vapor is lower than at wall temperature on the heating surface of acid dew point and condenses, and can cause heavy corrosion to heating surface or sweetener, and this claims, is acid dew piont corrosion.SO in the flue gas ₃Content the more, acid dew-point temperature is just high more, easy more the corrosion, the corrosion scope is wide more also serious more.The acid dew point of flue gas can reach 140～160 ℃, even higher.Power plant has to improve exhaust gas temperature for avoiding acid dew piont corrosion, has wasted a large amount of thermals source.For better solving the acid dew piont corrosion problem, power plant usually will test SO in the flue gas during operation ₃Content.Therefore, seek SO in a kind of test flue gas ₃Content detecting method and device are extremely important.

Measure SOx, SO in the flue gas ₃Content generally is to be translated into SO ₄ ^2-Pass through to analyze SO behind the sample solution ₄ ^2-Content comes indirect determination SOx, SO ₃Content.Prior art is measured SO ₄ ^2-The method of content has BaSO usually ₄Gravimetric method and EDTA back titration.

(1) gravimetric method is with barium chloride solution sulfate radical to be precipitated as barium sulphate, after filtration weighing deposit B aSO after washing and the 800 ℃ of calcinations ₄The method of weight.The advantage of gravimetric method be accuracy than higher, but that shortcoming is an analytical cycle is oversize, complex operation, the controlled condition of each step requires very high, and analyst's operative skill is had relatively high expectations, in case grasp badly, the result has than mistake.Such as: use BaCl ₂Solution precipitation SO ₄ ^2-The time, BaCl ₂Easily and BaSO ₄Form co-precipitation and be wrapped in BaSO ₄Cause measurement result bigger than normal in the precipitation.Be wrapped in the precipitation with chloride form for reducing chlorion, be to BaSO ₄Wash, number of times that washes with water and water yield control are bad, can make small part BaSO ₄Dissolving causes measurement result less than normal.BaSO ₄Must in acid solution, precipitate, the one, under alkaline environment, generate Ba (OH) when avoiding the pH value high ₂Precipitation and BaSO ₄Thereby co-precipitation causes error, the 2nd, and BaSO in acid solution ₄The particle of precipitation is bigger, be easy to filter and washing, but acidity is excessive, BaSO ₄Solubleness can increase, thereby the acidity condition of BaSO4 precipitation is wayward, acidity control is the improper result that easily causes have than mistake.In addition, it is consuming time very long that this method is measured process, as, BaSO ₄Being deposited in when still aging generally needs 4～6 hours, BaSO ₄The calcination that is deposited in 800 ℃ needs 1～2 hour, and the filtration of barium sulfate precipitate and wash time are also very long, and this method can not satisfy the requirement of desulfurization project scene to the quick needs of data.

(2) the EDTA back titration is to SO ₄ ^2-Add excessive BaCl in the sample liquid ₂-MgCl ₂Solution is treated BaSO ₄After precipitation is complete, in the ammonia buffered environment, be indicator, with EDTA standard solution titration residue Ba with the eriochrome black T ²⁺-Mg ²⁺, indirect determination SO ₄ ^2-Content.This method is fairly simple with respect to the gravimetric method operation, but also has deficiency, as: Ba ²⁺Excessive what are very big to result's influence, work as Ba ²⁺Excessive when too many, EDTA is not with Ba ²⁺Before the complexing, eriochrome black T is with regard to too early variable color, Guo Sheng Ba subsequently fully ²⁺Combine with eriochrome black T once more, make terminal point very not obvious, cause analytical error.Especially sulfate radical content fluctuates when big in sample, Ba ²⁺What excessive very difficult grasps in practical operation can cause the result to have than mistake.BaCl ₂-MgCl ₂Mixed solution is stable inadequately, often forms Mg (OH) after placement a period of time because of solution acidic is not enough ₂Flocculent deposit, but, can make BaSO again if increase mixed liquor acidity ₄The solubleness increase causes measurement result on the low side.

Summary of the invention

The purpose of this invention is to provide and a kind ofly can accurately detect SO in the flue gas ₃Content detecting method and device thereof.

The concrete technical scheme that this device adopts is as follows: the sampling apparatus of sulfuric anhydride in a kind of flue gas, it is characterized in that: it comprises dedusting mechanism (1), sampling pipe (2), spiral collection tube (3) and aspirating mechanism (4), wherein dedusting mechanism (1) is installed in the inlet end of sampling pipe (2), the endpiece of this sampling pipe (2) is connected by the import of pipeline with spiral collection tube (3), the import and export of described spiral collection tube (3) all is positioned at spiral upper end, and its outlet communicates with described aspirating mechanism (4) by silica gel hose (5).

The present invention provides power by aspirating mechanism, during use, sampling pipe is inserted in the thieff hatch at flue middle part, sampling pipe is fixed on the thieff hatch place by flange, under the effect of aspirating mechanism, the partial fume in the flue is drawn in the sampling pipe, and enters in the spiral collection tube through sampling pipe, the spiral collection tube is the glass chemistry goods, utilizes the centrifugal force that produces in spiral pipe in the flue gas aspiration procedure will be the SO of droplet shape ₃Be collected in the spiral pipe, in order to analyzing.

The present invention can be to the SO in the flue gas ₃Sample, for analyzing SO in the flue gas ₃Content, thereby can accurately analyze SO in the flue gas ₃Content, be convenient to the coal-burning power plant and take appropriate measures, control flue gas in SO ₃Content, to reduce acid dew piont corrosion, avoid reducing acid dew piont corrosion and causing the thermal source waste for improving exhaust gas temperature to flue and equipment.

Above-mentioned dedusting mechanism is made of dust removal head, absorbent cotton filtering bodies and iron wire, wherein dust removal head is a through-pipe structure, in the procephalic pipe of dedusting the absorbent cotton filtering bodies is housed, spacing by the iron wire of dust removal head front port, the rear end of dust removal head is threaded with described sampling pipe by joint.The absorbent cotton filtering bodies can prevent that dust from entering impact analysis result in the spiral collection tube.Connection of thread seals with sealant tape, to prevent smoke spillage; And protect joint screw thread with heat resistant adhesive tape.

Above-mentioned sampling pipe is made of interior pipe, electric heating thermal insulation band and outer tube, and the electric heating thermal insulation band also wraps up on inner pipe between interior pipe and outer tube.The electric heating thermal insulation band is tied up on inner pipe with the heat resistant adhesive tape compartment of terrain, carries out heated at constant temperature by temperature controller, is used for the insulation of flue gas, prevent flue gas Yin Wendu in sampling process reduce condense in in the pipe, avoided sampling error and to the corrosion of sampling pipe.

Above-mentioned aspirating mechanism is formed by connecting by pipeline successively by first Drexel bottle, vacuum pump, second Drexel bottle and wet gas meter, on the pipeline between first Drexel bottle and the vacuum pump barometric damper is housed.Wet gas meter is used to measure the flue gas volume of sampling; Drexel bottle reduces the water cut in the flue gas with the condensation in Drexel bottle of the moisture in the flue gas, has corrosive contaminant gases and just can't be trapped in vacuum pump and the wet gas meter, plays the protection instrument and avoids corroding; Two Drexel bottles play the B-grade condensation effect; The speed of progressively regulating the suction flue gas when control damper is used to begin to sample is with the protection wet gas meter.

Beneficial effect of the present invention have modern design, simple in structure, implement characteristics such as easy, it can be to the SO in the flue gas ₃Sample, so that accurately analyze SO in the flue gas ₃Content, be convenient to the coal-burning power plant and take corresponding measure, control flue gas in SO ₃Content, to reduce acid dew piont corrosion, avoid reducing acid dew piont corrosion and causing the thermal source waste for improving exhaust gas temperature to flue and equipment.Simultaneously, the absorbing mechanism with other substitutes with the spiral collection tube, also can be used for measuring the content of other materials such as moisture in the flue gas, SOx, HCl, HF, and usable range is very extensive.If with containing hydrogen peroxide (H ₂O ₂) the smoke absorption bottle replace the spiral collection tube described in the present invention to gather flue gas, detection method then of the present invention and device are equally applicable to that SOx (comprises SO in the flue gas ₂And SO ₃) detection of total content.

SO in the flue gas of the present invention ₃The concrete technical scheme of content detecting method is as follows: SO in a kind of flue gas ₃Content detecting method may further comprise the steps:

(1) SO ₃Sample collecting: the sampling apparatus that utilizes the described sulfuric anhydride of claim 1 is with the SO in the flue gas ₃Be collected in the spiral pipe (3), step is as follows:

A checks the impermeability of aspirating mechanism (4), confirms air tight;

B is connected the endpiece of spiral collection tube (3) with aspirating mechanism (4), the inlet end with spiral collection tube (3) is connected with sampling pipe (2) by wireway again;

C carries out the water-bath heating with spiral collection tube (3), and water is fluidized state;

D opens electric heating thermal insulation band (22) power supply preheating 5～10min;

E inserts sampling pipe (2) in the thieff hatch at flue middle part, is fixed on the thieff hatch place with ring flange;

F opens vacuum pump (42), opens barometric damper, and vacuum pump (42) pumping velocity is transferred to maximum, begins sampling, the initial reading V of wet gas meter when record gas meter temperature t ℃ and sampling beginning ₁,

G closes vacuum pump (42) when gathering about 300L flue gas, stop sampling, record gas meter termination reading V ₂, the exhaust gas volumn V=V that obtains gathering ₁-V ₂

H takes off being connected of spiral collection tube (3) inlet end and endpiece, and the entrance and exit end with one section silicone tube connection spiral collection tube (3) prevents SO ₃Leak, in order to analyzing;

I repeating step (f)～(h) is gathered three samples altogether, and measurement result is the mean value of three sample result;

(2) SO ₄ ^2-Sample solution preparation: add distilled water flushing spiral collection tube from spiral collection tube (3) endpiece, wash 3～5 times, washing fluid is all gone in the 250ml volumetric flask, be settled to 250ml and shake up as sample solution;

(3) SO ₄ ^2-Sample solution is analyzed:

A concentration is the preparation of the barium acetate solution of 0.005mol/L:

The volumetric flask of 1L is placed on the filtration stand, and taking by weighing the 1.1g molecular formula is Ba (CH ₃COO) ₂H ₂The barium acetate of O, 0.4g molecular formula are Pb (CH ₃COO) ₂3H ₂The lead acetate of O is transferred in the volumetric flask, add 800ml isopropyl alcohol and 3ml acetate and shake up, add the dissolving of 100ml shaking water 10min accelerating solid, constant volume is to 1L, the barium acetate solution for preparing left standstill solid was fully dissolved in 10～24 hours, the accurate concentration that needs to demarcate barium acetate solution before the titration is C _Ba ²⁺

It is v that b accurately pipettes volume with transfer pipet ₀SO ₄ ^2-Sample solution is in conical flask, in the volume ratio of isopropyl alcohol and sample solution is that 4: 1 ratio adds isopropyl alcohol, add concentration again and form the faintly acid buffer solution of PH 〉=3 greater than 99% acetate and barium acetate solution, arsenazo-III indicator that to add 3～5 concentration be 0.2g/100ml is in SO ₄ ^2-Shake up in the sample solution, this moment, solution presented rose; With demarcating good concentration is C _Ba ²⁺Barium acetate solution titration SO ₄ ^2-Sample solution to hyacinthine and in 1 minute no longer variable color be titration end-point, the barium acetate solution volume aml that record consumes;

C substitutes SO with distilled water ₄ ^2-Sample solution is done blank assay, consumes barium acetate solution volume bml;

(4) with the SO in the data substitution formula calculating flue gas ₃Content

$C=\frac{(a-b)*{\mathrm{<figure-callout\; id="2"\; label="C\; Ba"\; filenames="A20061009538900191.png"\; state="\{\{state\}\}">C</figure-callout>}}_{{\mathrm{Ba}}^{}}*(250/V_0)*(1/1000)*22.4*{10}^6}{V*\left(\frac{273.15}{273.15+t}\right)*\left(\frac{P_a+P_m-P_v}{101.325}\right)}$

Wherein: C-SO ₃Concentration, ppm

The volume of the barium acetate solution that a-titration sample liquid is consumed, ml

The volume of the barium acetate solution that b-titration blank solution is consumed, ml

C _Ba ²⁺The demarcation concentration of-barium acetate solution, mol/L

v ₀The volume of-minute sample thief liquid, ml

The exhaust gas volumn that V-gathers, L

T-wet gas meter temperature, ℃

P _a-atmospheric pressure, kPa

P _m-wet gas meter pressure, kPa

P _vWater saturation vapour pressure in the time of-t ℃, kPa

Wet gas meter pressure P in the formula _mBe since the suction velocity of flue gas when very fast at the inner pressure that forms of gas meter, measure SO ₃The time, general value 0.1kPa, P _vBe the saturated vapor pressure of water in the time of t ℃ in the gas meter, ℃ can check in saturated vapour pressure under the relevant temperature according to the temperature t of water in the gas meter.

SO in the sample solution ₄ ^2-Concentration is fit to titration when 0.1～5mg/10ml.If the sample solution concentration of preparation is higher than this value, suitably titration again after the dilution; Sample concentration is during less than 0.5mg/10ml, and is more accurate with the micro type buret titration, or titration again behind the evaporation and concentration sample solution.

The barium acetate solution concentration that reply prepares before titration is demarcated and is obtained its accurate concentration, and method is as follows:

1. prepare 0.05mol/L Na ₂CO ₃Reference solution

Accurately weighing is through 270-300 ℃ of benchmark natrium carbonicum calcinatum (Na that is dried to constant weight ₂CO ₃) 5.3000g is dissolved in distilled water and (removes CO through boiling ₂) in, be settled in the volumetric flask of 1L.

2. prepare 0.05mol/L H ₂SO ₄Solution

Measure the 2.78ml concentrated sulphuric acid and put into 300ml water, dilute constant volume again to 1L.

3. use 0.05mol/L Na ₂CO ₃Reference solution is demarcated 0.05mol/L H ₂SO ₄Solution

(1) accurately measures 10ml 0.05mol/L Na ₂CO ₃Reference solution adds 100ml water and stirs on magnetic stirring apparatus in conical flask;

(2) add 10～15 of bromcresol green-methyl red mixed indicators (0.3g bromcresol green and 0.2g methyl red are dissolved in 400ml 95% ethanol), it is green that solution is.

(3) use 0.05mol/L H ₂SO ₄Titration to pink is a terminal point, consumes H ₂SO ₄Solution v ₅Ml.Do blank assay simultaneously, consume H ₂SO ₄Solution v ₆Ml.

(4) calculate H ₂SO ₄Accurate solution concentration c ₂

c ₂＝0.05×10/(v ₅-v ₆)

Wherein: v ₅-titration Na ₂CO ₃The H that consumes during reference solution ₂SO ₄Liquor capacity, ml

v ₆The H that consumes when-titration is blank ₂SO ₄Liquor capacity, ml

4. use H ₂SO ₄The standardization of solution barium acetate solution

(1) accurately measures 10ml H ₂SO ₄Solution is in conical flask;

(2) adding 40ml isopropyl alcohol and 1ml acetate shakes up;

(3) add 3～5 arsenazos-III indicator (0.2g/100ml) and shake up, solution is rose;

(4) with barium acetate solution titration sulfuric acid solution to hyacinthine and in 1 minute no longer variable color be terminal point, consume barium acetate solution v ₃Ml.Do blank assay simultaneously, consume barium acetate solution v ₄Ml.

(5) calculate the barium acetate solution concentration C _Ba2+:

C _Ba2+＝c ₂×10/(v ₃-v ₄)

Wherein: v ₃The volume of the barium acetate solution that consumes during-titration sulfuric acid solution, ml

v ₄The volume of the barium acetate solution that consumes when-titration is blank, ml

SO of the present invention ₃The beneficial effect of detection method be that sampling is safe and reliable, simple to operate, analysis result more accurately and reliably, measure quick, easy and simple to handle.

Description of drawings

Fig. 1 is a structural representation of the present invention

Specific embodiment:

One, below in conjunction with accompanying drawing device of the present invention is described further:

As shown in Figure 1, the present invention is made of dedusting mechanism 1, sampling pipe 2, spiral collection tube 3 and aspirating mechanism 4 four major parts.Dedusting mechanism 1 comprises dust removal head 11, absorbent cotton filtering bodies 12 and iron wire 13, and wherein dust removal head 11 is a through-pipe structure, and absorbent cotton filtering bodies 12 in the pipe of dust removal head 11 front portions is spacing by the iron wire 13 of dust removal head 11 front ports.Sampling pipe 2 is made of interior pipe 21, electric heating thermal insulation band 22 and outer tube 23, tie up on interior pipe 21 electric heating thermal insulation band 22 usefulness heat resistant adhesive tape compartment of terrains, insert together then in the outer tube 23, outer tube 23 is threaded by the rear end of joint 6 with dust removal head 11, and pipe 21 communicates with dust removal head 11 in making.

Spiral collection tube 3 be import and export all in the screw type through-pipe structure of upper end, its import is connected with the outlet of interior pipe 21 by wireway 8.Aspirating mechanism 4 is made up of parts such as first Drexel bottle 41, vacuum pump 42, second Drexel bottle 43 and wet gas meters 44, wherein the import of first Drexel bottle 41 is connected with the outlet of spiral collection tube 3 by silica gel hose 5, the outlet of first Drexel bottle 41 is joined by the silica gel hose 9 and the import of vacuum pump 42, on this silica gel hose 9 barometric damper 7 is housed; The outlet of vacuum pump 42 is connected with the inlet hose of second Drexel bottle 43, and the outlet of second Drexel bottle 43 communicates with wet gas meter 44 by silica gel hose.

The present invention is work like this: earlier sampling pipe 2 is inserted in the thieff hatch at flue middle part, be fixed on the thieff hatch place with ring flange.Open vacuum pump 42, open barometric damper 7, vacuum pump 42 pumping velocities are transferred to maximum, begin sampling, write down the initial reading of wet gas meter 44 simultaneously.When gathering required exhaust gas volumn, close vacuum pump 42, stop sampling, the termination reading of record gas meter 44.Take off being connected of spiral collection tube 3 inlet ends and endpiece at last, the entrance and exit end with one section silicone tube connection spiral collection tube prevents SO ₃Leak, in order to analyzing.

Two, SO in certain coal-fired plant flue gas ₃The detection of content

1.SO ₃Sample collecting

SO ₃The sample collecting step is as follows: according to Fig. 1, tie up the electric heating thermal insulation band on inner pipe with the heat resistant adhesive tape compartment of terrain (1), inserts in the outer tube together then; (2) connect dedusting mechanism and sampling pipe; (3) each parts such as first Drexel bottle, vacuum pump, second Drexel bottle and wet gas meter with aspirating mechanism are connected successively; (4) impermeability of inspection aspirating mechanism is confirmed air tight; (5) endpiece with the spiral collection tube is connected with aspirating mechanism, and the inlet end with the spiral collection tube is connected with sampling pipe by wireway again; (6) the spiral collection tube is put into electrical heating kettle water-bath heating, water is fluidized state; (7) open the charged source preheating of electric heating thermal insulation 8min; (8) sampling pipe is inserted in the thieff hatch at flue middle part, be fixed on the thieff hatch place with ring flange; (9) open vacuum pump, open barometric damper, the vacuum pump pumping velocity is transferred to maximum, begin sampling, the initial reading V of wet gas meter when record gas meter temperature t=13 ℃ and sampling beginning ₁(L); (10) when gathering the 300L flue gas, close vacuum pump, stop sampling, the record gas meter stops reading V ₂(L), calculate the exhaust gas volumn V=V of actual acquisition ₁One V ₂=300L; (11) take off being connected of spiral collection tube inlet end and endpiece, the entrance and exit end with one section silicone tube connection spiral collection tube prevents SO ₃Leak, in order to analyzing; (12) repeating step (9)～(11) are gathered three samples altogether, analyze according to the following steps again:

2.SO ₄ ^2-The preparation of sample solution

Add the distilled water flushing spiral pipe from spiral collection tube endpiece, wash three times, washing fluid is all gone in the 250ml volumetric flask, be settled to 250ml and shake up as sample solution.

3.SO ₄ ^2-The analysis of sample solution, concrete steps are as follows:

3.1 reagent preparation

(1) arsenazo III solution: 0.2g/100ml is as developer.

Get the 0.2g arsenazo III and be dissolved in 100ml water, stirring is fully dissolved it on magnetic stirring apparatus, filters then, filtrate is moved in the brown bottle preserve.

(2) barium acetate solution: 0.005mol/L makes volumetric soiutions.

The volumetric flask of 1L is placed on the filtration stand, takes by weighing 1.1g barium acetate (Ba (CH ₃COO) ₂H ₂O), 0.4g lead acetate (Pb (CH ₃COO) ₂3H ₂O) be transferred in the volumetric flask, add 800ml isopropyl alcohol and 3ml acetate and shake up, add the dissolving of 100ml shaking water 10min accelerating solid, constant volume is to 1L.The barium acetate solution for preparing left standstill solid was fully dissolved in 10～24 hours; The accurate concentration calibration of demarcating barium acetate solution before the titration is C _Ba ²⁺=0.00569mol/L;

(3) acetate: concentration is greater than 99%.

Effect is to form buffer solution with barium acetate solution, is Ba ²⁺Provide the weakly acidic condition of pH 〉=3 with the complexing chromogenic reaction of arsenazo III.

(4) isopropyl alcohol: analyze pure.

Effect: Ba ²⁺Must in 80% isopropyl alcohol weakly acidic condition, carry out with the complexing chromogenic reaction of arsenazo III.The isopropyl alcohol that adds and the volume ratio of sample solution are 4: 1.

3.2 titration

(1) accurately pipettes 10ml SO with transfer pipet ₄ ^2-Sample solution adds 40ml isopropyl alcohol, 1ml acetate and 3～5 arsenazo-III indicator in SO in the 300ml conical flask ₄ ^2-Shake up in the sample solution, this moment, solution presented rose.

(2) demarcating good concentration with preparation in advance is C _Ba ²⁺=0.00569mol/L barium acetate solution titration SO ₄ ^2-Sample solution to hyacinthine and in 1 minute no longer variable color be titration end-point, the barium acetate solution volume a=2.07ml that record consumes.Acutely shake conical flask during titration.

(3) substitute SO with distilled water ₄ ^2-Sample solution (1), (2) is set by step done blank assay, consumes barium acetate solution volume b=0.05ml.

4. SO in the calculating flue gas ₃Content

$C=\frac{(a-b)<figure-callout\; id="2"\; label="*\; C\; Ba"\; filenames="A20061009538900191.png"\; state="\{\{state\}\}">*</figure-callout>C_{{\mathrm{Ba}}^{}}{{}^{2+}}_{}*(250/V_0)*(1/1000)*22.4*{10}^6}{V*\left(\frac{273.15}{273.15+t}\right)*\left(\frac{P_a+P_m-P_v}{101.325}\right)}$

Wherein: C-SO ₃Concentration, ppm

The volume of the barium acetate solution that a-titration sample liquid is consumed, ml

The volume of the barium acetate solution that b-titration blank solution is consumed, ml

C _Ba ²⁺The demarcation concentration of-barium acetate solution, mol/L

v ₀The volume of-minute sample thief liquid, ml

The exhaust gas volumn that V-gathers, L

T-wet gas meter temperature, ℃

P _a-atmospheric pressure, kPa

P _m-wet gas meter pressure, kPa

P _vWater saturation vapour pressure in the time of-t ℃, kPa

Institute's column data first SO among the top embodiment for gathering ₃The sample determination data, with each formula above the number pick substitutions, a=2.07ml wherein, b=0.05ml, C _Ba ²⁺=0.00569mol/L, v ₀=10ml, V=300L, t=13 ℃, P _a=101.32kPa, P _m=0.1kPa, P _v=1.50kPa calculates first SO ₃The concentration of sample is 22.8ppm.When difference, be engraved in same position and gather two samples again, try to achieve second, the 3rd SO ₃The concentration of sample is respectively 20.9ppm, 19.2ppm (seeing Table 1).To three sample SO ₃Concentration is averaged and is promptly obtained SO in the flue gas ₃Content is 21.0ppm.

SO in certain coal-fired plant flue gas of table 1 ₃Determination data and result

The barium acetate concentration C Ba 2+：0.00569mol/L								Atmospheric pressure: 101.32kPa
											Testing location	Measuring point	Time	Gather flue gas volume V	The gas meter temperature t	Saturated vapour pressure P v	Analyze experiment value			?SO 3Concentration
Divide the amount of getting v 0	Titration value a	Blank value b		Mean value
					L	℃	kPa	ml	ml	ml							ppm	ppm
The desulfurizer inlet	C-3	10:00	300	13.0										1.50	10	2.07			0.05	22.8	21.0
					C-3	10:16	300	13.0	1.50	10	1.90	0.05	20.9
	C-3	10:48	300	12.5										1.45	10	1.75	0.05	19.2

Divide the amount of getting: the SO that from 250 milliliters of volumetric flasks, pipettes when being titration ₄ ^2-The volume of sample solution.

Claims (5)

1, the sampling apparatus of sulfuric anhydride in a kind of flue gas, it is characterized in that: it comprises dedusting mechanism (1), sampling pipe (2), spiral collection tube (3) and aspirating mechanism (4), wherein dedusting mechanism (1) is installed in the inlet end of sampling pipe (2), the endpiece of this sampling pipe (2) is connected by the import of pipeline with spiral collection tube (3), the import and export of described spiral collection tube (3) all is positioned at spiral upper end, and its outlet communicates with described aspirating mechanism (4) by silica gel hose (5).

2, the sampling apparatus of sulfuric anhydride in the flue gas according to claim 1, it is characterized in that: described dedusting mechanism (1) is made of dust removal head (11), absorbent cotton filtering bodies (12) and iron wire (13), wherein dust removal head (11) is a through-pipe structure, in the pipe of dust removal head (11) front portion, absorbent cotton filtering bodies (12) is housed, iron wire (13) by dust removal head (11) front port is spacing, and the rear end of dust removal head (11) is threaded with described sampling pipe (2) by joint (6).

3, the sampling apparatus of sulfuric anhydride in the flue gas according to claim 1, it is characterized in that: described sampling pipe (2) is made of interior pipe (21), electric heating thermal insulation band (22) and outer tube (23), and electric heating thermal insulation band (22) is positioned between pipe (21) and the outer tube (23) and is wrapped on the pipe (21).

4, the sampling apparatus of sulfuric anhydride in the flue gas according to claim 1, it is characterized in that: described aspirating mechanism (4) is formed by connecting by pipeline successively by first Drexel bottle (41), vacuum pump (42), second Drexel bottle (43) and wet gas meter (44), on the pipeline between first Drexel bottle (41) and the vacuum pump (42) barometric damper (7) is housed.

5, SO in a kind of flue gas ₃Content detecting method may further comprise the steps:

(1) SO ₃Sample collecting: the sampling apparatus that utilizes the described sulfuric anhydride of claim 1 is with the SO in the flue gas ₃Be collected in the spiral pipe (3), step is as follows:

A checks the impermeability of aspirating mechanism (4), confirms air tight;

B is connected the endpiece of spiral collection tube (3) with aspirating mechanism (4), the inlet end with spiral collection tube (3) is connected with sampling pipe (2) by wireway again;

C carries out the water-bath heating with spiral collection tube (3), and water is fluidized state;

D opens electric heating thermal insulation band (22) power supply preheating 5～10min;

E inserts sampling pipe (2) in the thieff hatch at flue middle part, is fixed on the thieff hatch place with ring flange;

F opens vacuum pump (42), opens barometric damper, and vacuum pump (42) pumping velocity is transferred to maximum, begins sampling, the initial reading V of wet gas meter when record gas meter temperature t ℃ and sampling beginning ₁,

G closes vacuum pump (42) when gathering about 300L flue gas, stop sampling, record gas meter termination reading V ₂, the exhaust gas volumn V=V that obtains gathering ₁-V ₂

H takes off being connected of spiral collection tube (3) inlet end and endpiece, and the entrance and exit end with one section silicone tube connection spiral collection tube (3) prevents SO ₃Leak, in order to analyzing;

I repeating step (f)～(h) is gathered three samples altogether, and measurement result is the mean value of three sample result;

(2) SO ₄ ^2-Sample solution preparation: add distilled water flushing spiral collection tube from spiral collection tube (3) endpiece, wash 3～5 times, washing fluid is all gone in the 250ml volumetric flask, be settled to 250ml and shake up as sample solution;

(3) SO ₄ ^2-Sample solution is analyzed:

A concentration is the preparation of the barium acetate solution of 0.005mol/L:

The volumetric flask of 1L is placed on the filtration stand, and taking by weighing the 1.1g molecular formula is Ba (CH ₃COO) ₂H ₂The barium acetate of O, 0.4g molecular formula are Pb (CH ₃COO) ₂3H ₂The lead acetate of O is transferred in the volumetric flask, add 800ml isopropyl alcohol and 3ml acetate and shake up, add the dissolving of 100ml shaking water 10min accelerating solid, constant volume is to 1L, the barium acetate solution for preparing left standstill solid was fully dissolved in 10～24 hours, the accurate concentration that needs to demarcate barium acetate solution before the titration is C _Ba ²⁺

It is v that b accurately pipettes volume with transfer pipet ₀SO ₄ ^2-Sample solution is in conical flask, in the volume ratio of isopropyl alcohol and sample solution is that 4: 1 ratio adds isopropyl alcohol, add concentration again and form the faintly acid buffer solution of PH 〉=3 greater than 99% acetate and barium acetate solution, arsenazo-III indicator that to add 3～5 concentration be 0.2g/100ml is in SO ₄ ^2-Shake up in the sample solution, this moment, solution presented rose; With demarcating good concentration is C _Ba ²⁺Barium acetate solution titration SO ₄ ^2-Sample solution to hyacinthine and in 1 minute no longer variable color be titration end-point, the barium acetate solution volume aml that record consumes;

C replaces SO with distilled water ₄ ^2-Sample solution is done blank assay, consumes barium acetate solution volume bml;

(4) with the SO in the data substitution formula calculating flue gas ₃Content

$C=\frac{(a-b)*C_{{\mathrm{Ba}}^{2+}}*(250/V_0)*(1/1000)*22.4*{10}^6}{V*\left(\frac{273.15}{273.15+t}\right)*\left(\frac{P_a+P_m-P_v}{101.325}\right)}$

Wherein: C-SO ₃Concentration, ppm

The volume of the barium acetate solution that a-titration sample liquid is consumed, ml

The volume of the barium acetate solution that b-titration blank solution is consumed, ml

C _Ba ²⁺The demarcation concentration of-barium acetate solution, mol/L

v ₀The volume of-minute sample thief liquid, ml

The exhaust gas volumn that V-gathers, L

T-wet gas meter temperature, ℃

P _a-atmospheric pressure, kPa

P _m-wet gas meter pressure, kPa

P _vWater saturation vapour pressure in the time of-t ℃, kPa

Wet gas meter pressure P in the formula _mBe since the suction velocity of flue gas when very fast at the inner pressure that forms of gas meter, measure SO ₃The time, general value 0.1kPa, P _vBe the saturated vapor pressure of water in the time of t ℃ in the gas meter, ℃ can check in saturated vapour pressure under the relevant temperature according to the temperature t of water in the gas meter.

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