CN113008818B - Method for measuring acid mist content in sulfuric acid production tail gas - Google Patents
Method for measuring acid mist content in sulfuric acid production tail gas Download PDFInfo
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Abstract
The invention provides a method for measuring the content of acid mist in tail gas in sulfuric acid production, which comprises the following steps: sampling, sample preparation and measurement, drawing a standard curve and calculating a result; through constant-speed sampling, dilute alkali solution is used for absorbing acid mist in tail gas generated in sulfuric acid production, sulfate ions in sample solution react with barium chloride under a neutral condition to generate barium sulfate white precipitate to form turbid liquid, hydrochloric acid solution is added into the sample solution, sulfur dioxide and barium chloride in the tail gas can be effectively removed to generate barium sulfate white precipitate, the influence of interference on the result is caused, and then the absorbance of the tail gas is measured. The sulfate ion concentration and the absorbance have a good linear relation in a certain range, and the content of the sulfate in the sample is determined by setting a standard curve and comparing the measured absorbance of the sample solution with the standard curve. The determination method is simple and convenient, has low cost and high accuracy, uses simple and easily-obtained equipment, and is convenient for small and medium-sized chemical enterprises to apply.
Description
Technical Field
The invention belongs to the technical field of sulfuric acid mist detection, and particularly relates to a method for determining the content of acid mist in tail gas in sulfuric acid production.
Background
In the production process of sulfuric acid, tail gas usually contains acid mist, the main component in the acid mist is sulfuric acid liquid drops, and the current technology for detecting the content of the acid mist in the tail gas in the production of sulfuric acid comprises two technologies: barium chromate spectrophotometry and ion chromatography.
The problems of the barium chromate spectrophotometry are mainly that: 1. the operation procedure of the barium chromate spectrophotometry is complicated; 2. the sulfuric acid mist and barium chromate form a series of yellow substances for colorimetry, but ions of other elements such as calcium, magnesium, zirconium and the like react with chromate to generate yellow or orange substances, and serious interference is generated in coexistence, so that the accuracy is reduced.
The ion chromatography uses an ion chromatograph for measurement, the ion chromatograph is a large-scale precise instrument and is expensive, and many basic-level production enterprises do not have the condition, so that the improvement of the acid mist emission treatment technology is limited.
Therefore, there is a need to provide an improved solution to the above-mentioned deficiencies of the prior art.
Disclosure of Invention
The invention aims to provide a method for measuring the content of acid mist in tail gas from sulfuric acid production, which aims to solve the problems of low accuracy and high cost of the conventional method for measuring the content of acid mist in tail gas from sulfuric acid production.
In order to achieve the above purpose, the invention provides the following technical scheme:
a method for measuring the content of acid mist in tail gas generated in sulfuric acid production comprises the following steps:
step one, sampling;
collecting and absorbing tail gas generated in the production of sulfuric acid by a sampling device, wherein the sampling device comprises an absorption bottle, alkaline solution is filled in the absorption bottle, the tail gas generated in the production of sulfuric acid is introduced into the absorption bottle at a constant speed, and a first absorption liquid is obtained after constant-speed sampling for a period of time;
step two, sample preparation and measurement;
transferring the first absorption liquid prepared in the step one into a first container, adding a hydrochloric acid solution to adjust the pH value to be neutral, adding water to a constant volume, and shaking up to obtain a second absorption liquid;
absorbing part or all of the second absorption liquid into a second constant volume container, adding a stabilizer, a hydrochloric acid solution and a barium chloride solution, then adding water to dilute and constant volume, shaking up, standing at room temperature to obtain a sample solution, and measuring the absorbance of the sample solution by using a spectrophotometer;
step three, drawing a standard curve;
respectively measuring sulfate standard solutions with different volumes into a plurality of third constant volume containers, adding the stabilizer, the hydrochloric acid solution and the barium chloride solution into each third constant volume container, then adding water to constant volume and shaking up, standing at room temperature to obtain a reference standard solution, measuring the absorbance of different reference standard solutions by using a spectrophotometer, and drawing a standard curve by taking the absorbance as a vertical coordinate and the content of sulfate as a horizontal coordinate;
step four, calculating a result;
and (3) comparing the absorbance of the sample solution measured in the step (II) with the standard curve obtained in the step (III) to obtain the mass of the sulfate ions in the sample solution, further calculating and obtaining the mass of the sulfate ions in the first absorption liquid, and finally calculating the content of the acid mist in the sulfuric acid production tail gas according to a formula.
In the method for measuring the content of the acid mist in the tail gas of the sulfuric acid production, preferably, the sampling device further comprises a sampling pipe, a flow meter and a vacuum pump;
the input end of the absorption bottle is communicated with one end of a sampling pipe through a pipeline, the other end of the sampling pipe extends into an air source pipeline, and the air source pipeline is used for circulating sulfuric acid production tail gas;
the flow meter is arranged on the pipeline and used for metering and controlling the flow of the sulfuric acid production tail gas introduced into the absorption bottle;
the vacuum pump is communicated with the output end of the absorption bottle and is used for keeping the interior of the absorption bottle in a negative pressure state;
preferably, the flow meter is a wet gas flow meter, and a thermometer is arranged in the flow meter.
In the method for measuring the acid mist content in the tail gas from the sulfuric acid production as described above, preferably, in the third step, a first blank solution is further prepared, the first blank solution is different from the control standard solution in that a sulfate standard solution is not added, and the first blank solution is used for adjusting the zero point of the spectrophotometer;
preferably, the concentration of the standard solution of sulfate is 0.1mg/ml.
In the method for determining the content of acid mist in tail gas from sulfuric acid production as described above, preferably, in the second step, a second blank solution is further prepared, and the second blank solution is different from the sample solution in that no tail gas from sulfuric acid production is introduced into the sample solution, and the second blank solution is used for eliminating the influence of sulfate ions contained in the used reagent; the second blank solution was measured for absorbance using a spectrophotometer.
In the method for measuring the acid mist content in the tail gas from the sulfuric acid production, preferably, the formula in the fourth step is as follows:
wherein the content of acid mist in the tail gas of the X-sulfuric acid production is SO 4 -2 In terms of mass fraction of (2), unit mg/m 3 ；
m-the mass of sulfate radicals in the first absorption liquid, in mg;
v- - - -sample volume in ml;
t-sampling time in units of min;
r-flow rate of a flow meter in L/min;
p- -temperature coefficient, the ratio of the volume of 1mol of gas at different temperatures to the volume at standard conditions.
In the method for measuring the content of acid mist in the tail gas from sulfuric acid production, preferably, the stabilizer is a mixed solution of glycerol and ethanol, and the volume ratio of the glycerol to the ethanol is 1.
In the method for measuring the content of the acid mist in the tail gas in the sulfuric acid production, preferably, the concentration of the barium chloride solution is 100g/L;
the hydrochloric acid solution is obtained by mixing concentrated hydrochloric acid and water according to the volume ratio of 1;
the concentration of the alkaline solution is 0.1mol/L.
In the method for measuring the content of the acid mist in the sulfuric acid production tail gas, preferably, in the first step, the sulfuric acid production tail gas is introduced into the absorption bottle at a constant rate of 1.5-3.5L/min, and the constant-speed sampling time is 20-40 min.
In the method for measuring the content of acid mist in the tail gas from the production of sulfuric acid, preferably, in the second step, 5 to 10ml of the stabilizer and 10 to 20ml of the hydrochloric acid solution are added into every 10ml of the second absorption solution; the barium chloride solution is added in an amount to enable complete precipitation of sulfate ions.
In the method for measuring the content of the acid mist in the tail gas of the sulfuric acid production, preferably, the adding amount of the stabilizer, the hydrochloric acid solution and the barium chloride solution in the third step is the same as the volume in the second step.
Compared with the closest prior art, the technical scheme provided by the invention has the following excellent effects:
the method for measuring the content of the acid mist in the tail gas in the sulfuric acid production comprises the steps of sampling at a constant speed, absorbing the acid mist in the tail gas in the sulfuric acid production by using a dilute alkali solution, reacting sulfate ions in a sample solution with barium chloride under a neutral condition to generate a white barium sulfate precipitate, forming a suspension, and measuring the absorbance of the suspension. The concentration of sulfate ions and the absorbance have a good linear relation in a certain range, and the content of the sulfate ions in the sample is determined by setting a standard curve and comparing the measured absorbance of the sample solution with the standard curve.
According to the invention, the hydrochloric acid solution is added into the sample solution, so that the influence of interference on the result caused by barium sulfite white precipitate generated by sulfur dioxide and barium chloride in tail gas can be effectively eliminated; the invention is also provided with a second blank solution, which can eliminate the influence of the sulfate ions contained in the used reagent participating in the reaction on the test result.
The determination method can well overcome the defects of the prior art, is simple and convenient, has low cost and high accuracy, uses simple and easily-obtained equipment, is convenient for application of small and medium-sized chemical enterprises, and can play a role in promoting environmental protection, energy conservation and clean production.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. Wherein:
fig. 1 is a schematic structural diagram of a collecting device of the method for measuring the content of acid mist in sulfuric acid production tail gas according to the embodiment of the invention.
In the figure: 1. an absorption bottle; 2. a flow rate meter; 3. a sampling tube; 4. a gas source conduit; 5. a vacuum pump; 6. and (3) alkaline solution.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived from the embodiments of the present invention by a person skilled in the art, are within the scope of the present invention.
The present invention will be described in detail with reference to examples. It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.
The method for measuring the content of the acid mist in the sulfuric acid production tail gas comprises the steps of sampling at a constant speed, absorbing the acid mist in the sulfuric acid production tail gas in the gas by using a dilute alkali solution, reacting sulfate ions in a sample solution with a barium chloride solution under a neutral condition to generate a white barium sulfate precipitate, forming a suspension, and measuring the absorbance of the suspension. The sulfate ion concentration and the absorbance have a good linear relation in a certain range, and the content of sulfate radicals in a sample is determined by setting a standard curve and comparing the measured absorbance with the standard curve.
Because the tail gas may contain sulfur dioxide gas, the sulfur dioxide and barium chloride generate barium sulfite white precipitate which can affect the determination of absorbance, hydrochloric acid solution is added into the sample solution, barium sulfite is dissolved in hydrochloric acid, and barium sulfate is not dissolved, so that the influence of the sulfur dioxide in the tail gas on the interference of the result can be effectively eliminated; the invention is also provided with a blank solution, which can eliminate the influence of the sulfate ions contained in the used reagent participating in the reaction on the test result.
As shown in figure 1, the method for measuring the acid mist content in the tail gas in the sulfuric acid production provided by the invention comprises the following steps:
step one, sampling;
the tail gas generated in the production of the sulfuric acid is collected and absorbed by a sampling device, the sampling device comprises an absorption bottle 1, an alkaline solution 6 is filled in the absorption bottle 1, the tail gas generated in the production of the sulfuric acid is introduced into the absorption bottle 1 at a constant speed, and a first absorption liquid is obtained after constant-speed sampling for a period of time.
In the specific embodiment of the invention, in the first step, the sulfuric acid production tail gas is introduced into the absorption bottle 1 at a constant rate of 1.5-3.5L/min (such as 1.6L/min, 1.8L/min, 2.0L/min, 2.2L/min, 2.4L/min, 2.6L/min, 2.8L/min, 3.0L/min, 3.2L/min and 3.4L/min), and the constant-speed sampling time is 20-40 min (such as 22min, 24min, 26min, 28min, 30min, 32min, 34min, 36min and 38 min). Preferably, the absorption bottle 1 is a 721G porous glass plate absorption bottle. The sampling rate is preferably 2.5L/min; if the sampling rate is too fast, bubbles in the absorption bottle 1 are too fast, detected components in tail gas generated in the sulfuric acid production run away after being absorbed in time, and the result is low; if the sampling rate is too slow, the sampling time must be extended, which results in reduced operating efficiency, and therefore a sampling rate suitable for selection is within the scope of the present application.
The sampling time and the sampling rate are matched, and the accuracy and the representativeness of the sample gas are reduced when too few samples are sampled; too much sampling is needed, and the content of the measured substance in the sample can be ensured to be in a linear range by measuring after dilution, otherwise, the measurement error is increased.
The alkaline solution 6 is a sodium hydroxide solution or a potassium hydroxide solution, and the concentration of the alkaline solution 6 is 0.1mol/L standard solution. The alkaline solution 6 added into the absorption bottle 1 can completely absorb the collected sulfuric acid production tail gas, namely, the pH value of the first absorption liquid is ensured to be alkaline.
In a specific embodiment of the present invention, the sampling device further comprises a sampling tube 3, an anemometer 2 and a vacuum pump 5.
The input end of the absorption bottle 1 is communicated with one end of a sampling pipe 3 through a pipeline, the other end of the sampling pipe 3 extends into an air source pipeline 4, and the air source pipeline 4 is used for circulating sulfuric acid production tail gas; the flow meter 2 is arranged on a pipeline connected between the input end of the absorption bottle 1 and the sampling pipe 3, and the flow meter 2 is used for metering and controlling the flow of the input sulfuric acid production tail gas; vacuum pump 5 communicates with the output of absorption bottle 1 for keep negative pressure state in making absorption bottle 1, so that sampling device can gather the sulphuric acid production tail gas in the air supply pipeline 4 in absorption bottle 1 smoothly.
Preferably, the flow meter 2 is a wet gas flow meter, and a thermometer is provided in the flow meter 2.
Still preferably, the position where the other end of the sampling tube 3 extends into the air source pipeline 4 is in the area where the radius from the central point of the air source pipeline 4 is 2/3, and the reason why the sampling tube 3 extends into the air source pipeline 4 is that: if the sampling pipe 3 is close to the pipe wall, condensate and other impurities can be collected, and the accuracy of the measuring result is influenced.
Step two, sample preparation and measurement;
transferring the first absorption liquid prepared in the step one into a first container, adding a hydrochloric acid solution to adjust the pH value to be neutral, adding water to a constant volume, and shaking up to obtain a second absorption liquid;
and (3) sucking part or all of the second absorption liquid into a second constant volume container, adding a stabilizer, a hydrochloric acid solution and a barium chloride solution, then adding water for diluting, constant volume and shaking up, standing at room temperature to obtain a sample solution, and measuring the absorbance of the sample solution by using a spectrophotometer.
This step may also be: and (3) absorbing part or all of the second absorption liquid into a second constant volume container, adding a stabilizer and a hydrochloric acid solution, then adding water for dilution and constant volume, shaking up, pouring into the container containing the barium chloride solution, shaking and standing to obtain a sample solution, and finally measuring the absorbance of the sample solution by using a spectrophotometer.
In a specific example of the present invention, the absorbance of the solution was measured at a wavelength of 450nm using a 2cm cuvette.
In the specific embodiment of the invention, the concentration of the barium chloride solution is 100g/L; the hydrochloric acid solution is obtained by mixing concentrated hydrochloric acid and water according to the volume ratio of 1. The concentrated hydrochloric acid in the application is commercially available hydrochloric acid with the concentration of 36-38% by mass.
The stabilizer is a mixed solution of glycerol and ethanol, and the volume ratio of the glycerol to the ethanol is 1. The barium sulfate forms white suspension instead of colored solution, and the stabilizer can achieve good stabilizing effect after being added, so that the determination requirement can be met. The mixed solution of glycerol and ethanol belongs to a neutral solution, does not react with a measured object, does not interfere with measurement, the volume ratio of the glycerol to the ethanol is controlled to be 1.
In the second step, 5-10ml (such as 6ml, 7ml, 8ml, 9ml and 10 ml) of stabilizing agent and 10-20 ml (such as 11ml, 12ml, 13ml, 14ml, 15ml, 16ml, 17ml, 18ml and 19 ml) of hydrochloric acid solution are added into every 10ml of second absorption liquid; the barium chloride solution is added in an amount to enable complete precipitation of sulfate ions. The excessive addition of the stabilizer can increase the viscosity of the solution, which causes the phenomenon of uneven suspension of the barium sulfate, and the excessive addition of the hydrochloric acid solution can affect the acidity of the solution, which can affect the measurement result. The adding amount of the stabilizer and the hydrochloric acid solution is matched with the volume of the second constant volume container and is increased or decreased in proportion to the volume of the second constant volume container, for example, 5ml of the stabilizer and 10ml of the hydrochloric acid solution can be added into a 50ml volumetric flask; in a 100ml volumetric flask, 10ml of stabilizer and 20ml of hydrochloric acid solution can be added.
In the second step, a second blank solution is also provided, and the difference between the second blank solution and the sample solution is that the sample solution is not introduced with sulfuric acid production tail gas, and the other components are the same as the components of the sample solution, namely the preparation method of the second blank solution is completely the same as the preparation steps and methods of the sample solution except that the sulfuric acid production tail gas is not introduced in the first step. The second blank solution is used for eliminating the influence of sulfate ions contained in the used reagent; the second blank solution was measured for absorbance using a spectrophotometer. And subtracting the absorbance measured by the second blank solution from the sulfate ion content measured by the absorbance measured by the sample solution to obtain the sulfate ion content, namely the accurate sulfate ion content in the actual sample solution. The second blank solution is arranged to improve the accuracy of the measurement result.
Step three, drawing a standard curve;
respectively measuring sulfate standard solutions with different volumes in a plurality of third constant volume containers, adding a stabilizer, a hydrochloric acid solution and a barium chloride solution into each third constant volume container, then adding water to constant volume and shaking up, standing at room temperature to obtain a reference standard solution, measuring the absorbance of different reference standard solutions by using a spectrophotometer, and drawing a standard curve by taking the absorbance as a vertical coordinate and the content of sulfate as a horizontal coordinate.
In a specific embodiment of the invention, the concentration of the standard solution of sulfate is 0.1mg/ml.
Preferably, the addition amount of the stabilizer, the hydrochloric acid solution and the barium chloride solution in the third step is the same as the volume in the second step, so that the influence of other factors on the test can be reduced, and the accuracy of the measurement result is improved.
In the third step, a first blank solution is further provided, the first blank solution is different from the reference standard solution in that a sulfate standard solution is not added, and other steps and methods are the same as those of the reference standard solution, and the first blank solution is used for adjusting the zero point of the spectrophotometer.
Step four, calculating results;
and (3) comparing the absorbance of the sample solution measured in the step (II) with the standard curve obtained in the step (III) to obtain the content of sulfate ions in the sample solution in the step (II), calculating and obtaining the mass of the sulfate ions in the first absorption liquid according to the proportional relation between the absorbed second absorption liquid and all the second absorption liquids which are added with hydrochloric acid and adjusted to be neutral, and finally calculating the content of acid mist in the tail gas in the sulfuric acid production according to a formula.
In the embodiment of the present invention, the formula in step four is:
wherein the content of acid mist in the tail gas of the X-sulfuric acid production is SO 4 -2 In terms of mass fraction of (1), unit mg/m 3 ；
m-the mass of sulfate radical in the first absorption liquid, in mg;
v- - - -sample volume in ml;
t-sampling time in units of min;
r-flow rate of a flow meter in L/min;
p- -temperature coefficient, the ratio of the volume of 1mol of gas at different temperatures to the volume at standard conditions.
The hydrochloric acid solution in the following examples was obtained by mixing concentrated hydrochloric acid with water in a volume ratio of 1.
Example 1
The method for measuring the content of acid mist in the tail gas in the sulfuric acid production provided by the embodiment comprises the following steps:
firstly, filling an absorption bottle of a glass sand core (a porous glass plate) with about 75ml and 0.1mol/L sodium hydroxide standard solution, connecting the absorption bottle with a wet gas flow velocity meter, simultaneously tightly connecting the absorption bottle with a sampling pipe, extending the sampling pipe into a position with the diameter of 1/3-1/2 of the diameter of a gas source pipeline, connecting a vacuum pump, and enabling pipeline gas to pass through sampling devices such as the absorption bottle and the like at the speed of 2.5L/min to sample for 30min at a constant speed.
And step two, taking down the absorption bottle, pouring the absorption liquid in the absorption bottle into a 100ml volumetric flask, washing the absorption bottle with a small amount of water for 2-3 times, wherein the amount of water used for each time is not more than 10ml, adding the washing liquid into the volumetric flask, adjusting the washing liquid to be neutral by using a hydrochloric acid solution, fixing the water to a certain volume by using water, and shaking up to obtain the sample absorption liquid.
Sucking 5-10ml sample absorption liquid into 50ml volumetric flask, adding 5ml glycerol-ethanol mixed solution for removing SO 2 For the interference, 10ml of hydrochloric acid solution is added, diluted to the mark with water and shaken up. Carefully pour into a beaker containing 3ml of 100g/L barium chloride solution and shake for 2min. Standing at room temperature for 10min, and measuring absorbance of the solution at wavelength of 450nm with a 2cm cuvette.
And simultaneously performing a blank test to obtain a second blank solution.
And step three, respectively measuring 0, 0.2, 0.4, 0.6, 0.8, 1.0ml and 0.1mg/ml sulfate standard solution, respectively adding 10ml hydrochloric acid solution into a 50ml volumetric flask, shaking up, then adding 5ml glycerol-ethanol mixed solution, shaking up, adding water to a constant volume to a scale, shaking up, carefully transferring into a beaker containing 3ml barium chloride solution at a speed of 100g/L, shaking up for 2min at a speed of 2 r/s, and standing for 10min. While the first blank solution was set.
The zero point of a spectrophotometer is adjusted by a first blank solution in a 2cm cuvette at the wavelength of 450nm, the absorbances of different sulfate solutions added are respectively measured, a standard curve is drawn by taking the absorbances as the ordinate and the sulfate content (mg) in the solution as the abscissa, and the data in the curve is shown in table 1.
TABLE 1 Linear relationship of sulfate radical content to absorbance
As can be seen from Table 1, the sulfate ion concentration and the absorbance have a good linear relationship, and can be applied to colorimetric determination.
Accuracy verification
After a certain period of time (stable production state) is sampled for multiple times, the measurement result of measuring the acid mist content in the tail gas in the sulfuric acid production by using the method is compared with environmental protection monitoring data, and the measurement result is well consistent with the environmental protection monitoring data. See tables 2 and 3.
TABLE 2 comparison of results of acid mist content in continuously sampled tail gas in the same time period with on-line data of environmental protection monitoring
TABLE 3 acid mist content multiple determination results in tail gas from sulfuric acid production at different times
As can be seen from tables 2 and 3, no matter continuous sampling is performed in the same time period or sampling is performed at any time in different time periods, the barium sulfate turbidimetry method for measuring the acid mist content in the sulfuric acid production tail gas can be well matched with the environmental protection monitoring data.
Precision verification
The precision was verified by repeated measurements on the same sample, the results are shown in table 4.
TABLE 4 acid mist content parallel determination of samples
As can be seen from Table 4, when the same sample is subjected to multiple parallel measurements, the relative error of the data is less than 0.2%, the precision is high, and the measurement method provided by the invention has the advantages of good repeatability and high reliability.
In conclusion: the method for measuring the content of the acid mist in the sulfuric acid production tail gas comprises the steps of sampling at a constant speed, absorbing the acid mist in the sulfuric acid production tail gas in the gas by using a dilute alkali solution, reacting sulfate ions in a sample solution with barium chloride under a neutral condition to generate a barium sulfate white precipitate, forming a suspension, and measuring the absorbance of the suspension. The sulfate ion concentration and the absorbance have a good linear relation in a certain range, and the content of sulfate radicals in a sample is determined by setting a standard curve and comparing the measured absorbance with the standard curve. Because most of sulfate is soluble in water, only barium sulfate is hardly soluble in water and insoluble in acid, interference is easy to eliminate by adopting a barium sulfate turbidimetry method, and the accuracy is high.
The hydrochloric acid solution is added into the sample solution, so that the influence of interference on the result caused by white barium sulfite precipitation generated by sulfur dioxide and barium chloride in the tail gas can be effectively eliminated; the invention is also provided with a blank solution, which can eliminate the influence of the sulfate ions contained in the used reagent participating in the reaction on the test result.
The determination method can well overcome the defects of the prior art, is simple and convenient, has low cost and high accuracy, uses simple and easily-obtained equipment, is convenient for application of small and medium-sized chemical enterprises, and can play a role in promoting environmental protection, energy conservation and clean production.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made to the present invention by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (7)
1. The method for measuring the content of the acid mist in the tail gas generated in the production of the sulfuric acid is characterized by comprising the following steps of:
step one, sampling;
collecting and absorbing tail gas generated in the production of sulfuric acid by a sampling device, wherein the sampling device comprises an absorption bottle, alkaline solution is filled in the absorption bottle, the tail gas generated in the production of sulfuric acid is introduced into the absorption bottle at a constant speed, and a first absorption liquid is obtained after constant-speed sampling for a period of time;
step two, sample preparation and measurement;
transferring the first absorption liquid prepared in the step one into a first container with a certain volume, adding a hydrochloric acid solution to adjust the PH to be neutral, adding water to a certain volume, and shaking up to obtain a second absorption liquid;
absorbing part or all of the second absorption liquid into a second constant volume container, adding a stabilizer, a hydrochloric acid solution and a barium chloride solution, then adding water to dilute and constant volume, shaking up, standing at room temperature to obtain a sample solution, and measuring the absorbance of the sample solution by using a spectrophotometer;
step three, drawing a standard curve;
respectively measuring sulfate standard solutions with different volumes in a plurality of third constant volume containers, adding the stabilizer, the hydrochloric acid solution and the barium chloride solution into each third constant volume container, then adding water to constant volume and shaking up, standing at room temperature to obtain a reference standard solution, measuring the absorbance of different reference standard solutions by using a spectrophotometer, and drawing a standard curve by taking the absorbance as a vertical coordinate and the content of sulfate as a horizontal coordinate;
step four, calculating a result;
comparing the absorbance of the sample solution measured in the step two with the standard curve obtained in the step three to obtain the mass of sulfate ions in the sample solution, further calculating and obtaining the mass of the sulfate ions in the first absorption solution, and finally calculating the content of acid mist in the sulfuric acid production tail gas according to a formula;
the sampling device also comprises a sampling pipe, an anemometer and a vacuum pump; the flow meter is a wet gas flow meter, and a thermometer is arranged in the flow meter;
the stabilizer is a mixed solution of glycerol and ethanol, and the volume ratio of the glycerol to the ethanol is 1;
in the second step, 5-10ml of stabilizing agent and 10-20 ml of hydrochloric acid solution are added into every 10ml of second absorption liquid;
in the first step, the tail gas generated in the production of sulfuric acid is introduced into an absorption bottle at a constant rate of 1.5-3.5L/min, and the constant-speed sampling time is 20-40 min;
the input end of the absorption bottle is communicated with one end of a sampling pipe through a pipeline, the other end of the sampling pipe extends into an air source pipeline, and the air source pipeline is used for circulating sulfuric acid production tail gas;
the position where the other end of the sampling pipe extends into the air source pipeline is located in the area which is 2/3 of the radius away from the central point of the air source pipeline;
the formula in the fourth step is as follows:
wherein the content of acid mist in the tail gas of the X-sulfuric acid production is SO 4 -2 In terms of mass fraction of (1), unit mg/m 3 ；
m-the mass of sulfate radicals in the first absorption liquid, in mg;
v- - - -sample volume in ml;
t-sampling time in units of min;
r-flow rate of a flow meter in L/min;
p- -temperature coefficient, the ratio of the volume of 1mol of gas at different temperatures to the volume at standard conditions.
2. The method for measuring the acid mist content in the tail gas of the sulfuric acid production according to claim 1,
the flow meter is arranged on the pipeline and used for metering and controlling the flow of the sulfuric acid production tail gas introduced into the absorption bottle;
the vacuum pump is communicated with the output end of the absorption bottle and is used for keeping the inside of the absorption bottle in a negative pressure state.
3. The method for measuring the acid mist content in the tail gas in the sulfuric acid production as claimed in claim 1, wherein in the third step, a first blank solution is prepared, the first blank solution is different from the control standard solution in that a sulfate standard solution is not added, and the first blank solution is used for adjusting the zero point of the spectrophotometer;
the concentration of the standard sulfate solution is 0.1mg/ml.
4. The method for measuring the acid mist content in the sulfuric acid production tail gas as claimed in claim 3, wherein, in the second step, a second blank solution is prepared, the second blank solution is different from the sample solution in that the sulfuric acid production tail gas is not introduced into the sample solution, and the second blank solution is used for eliminating the influence of sulfate ions contained in the used reagent; the second blank solution was measured for absorbance using a spectrophotometer.
5. The method for measuring the content of the acid mist in the tail gas generated in the sulfuric acid production according to any one of claims 1 to 4, wherein the concentration of the barium chloride solution is 100g/L;
the hydrochloric acid solution is obtained by mixing concentrated hydrochloric acid and water according to the volume ratio of 1;
the concentration of the alkaline solution is 0.1mol/L.
6. The method for measuring the acid mist content in the sulfuric acid production tail gas as claimed in claim 1, wherein the barium chloride solution is added in an amount capable of completely precipitating sulfate ions.
7. The method for measuring the acid mist content in the tail gas in the sulfuric acid production as claimed in claim 6, wherein the adding amount of the stabilizer, the hydrochloric acid solution and the barium chloride solution in the third step is the same as the volume in the second step.
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