阅读说明：本技术 一种用于同时检测烟气中so2、so3的装置及方法 (Be arranged in simultaneous detection flue gas SO2、SO3Apparatus and method of ) 是由 赵耀 王明星 董峰 邓宝永 于 2021-05-28 设计创作，主要内容包括：本发明提供一种用于同时检测烟气中SO-2、SO-3的装置及方法,包括采样系统、反应系统和色谱系统采样系统包括耐高温采样管、烟气管路；反应系统包括氧化反应器、变色反应器及其相应的氧化吸收反应,其中氧化反应器作用于烟气上行管路中的烟气,采用定量的H-2O-2、NaOH、去离子水将烟气中的SO-x转化为SO-4～(2-),变色反应器作用于烟气下行管路中的烟气,采用碘量法准确分析烟气中的SO-2含量,并将SO-x转化为SO-4～(2-)。该方法精度高,重复性好,检测范围宽,0.1mg/Nm～(3)-几万mg/Nm～(3),该分析方法克服原位测量的随机性,偶然性,可同时准确分析烟气中SO-2和SO-3的含量,便于考察烟气中SO-2和SO-3的平衡关系。(The invention provides a method for simultaneously detecting SO in flue gas 2 、SO 3 The device and the method comprise a sampling system, a reaction system and a chromatographic system, wherein the sampling system comprises a high-temperature-resistant sampling pipe and a flue gas pipeline; the reaction system comprises an oxidation reactor, a color-changing reactor and a corresponding oxidation absorption reaction, wherein the oxidation reactor acts on the flue gas in the flue gas ascending pipeline and adopts quantitative H 2 O 2 NaOH and deionized water are used for removing SO in the flue gas x Conversion to SO 4 2‑ The color-changing reactor acts on the flue gas in the flue gas descending pipeline, and the SO in the flue gas is accurately analyzed by an iodometry method 2 In an amount of and adding SO x Conversion to SO 4 2‑ . The method has high precision, good repeatability, wide detection range of 0.1mg/Nm 3 -several tens of thousands mg/Nm 3 The analysis method overcomes the randomness and the contingency of in-situ measurement, and can simultaneously and accurately analyze the SO in the flue gas 2 And SO 3 Content of (2) is convenient for investigating SO in the flue gas 2 And SO 3 The balance relationship of (1).)

1. Be arranged in simultaneous detection flue gas SO₂、SO₃The device is characterized by comprising a sampling system, a reaction system and a chromatographic system; the sampling system comprises a connecting component, a high-temperature-resistant sampling pipe and a flue gas pipeline; the flue gas pipeline is a flue gas ascending pipeline and a flue gas descending pipeline; the reaction system comprises an oxidation reactionA reactor and a color-changing reactor; the chromatographic system is an ion chromatographic system; one end of the high-temperature sampling pipe is connected with the flue, the other end of the high-temperature sampling pipe is connected with a flue gas pipeline through the two-way pipe, a flue gas ascending pipeline is connected with an inlet of the oxidation reactor, a flue gas descending pipeline is connected with an inlet of the color-changing reactor, and an outlet of the oxidation reactor and an outlet of the color-changing reactor are connected with the ion chromatograph.

2. The method of claim 1, wherein said high temperature sampling tube is provided with a filter, a heater, a flue gas power drive and a one-way valve; the flue gas power drive is a flue gas fan and is used for providing pressure required by gas sampling and collection, and if the pressure in the flue is positive pressure, the sampling fan is not needed; the gas pipeline is a flue gas ascending pipeline and a flue gas descending pipeline, and is respectively provided with a pipeline heat preservation and a gas volume flow controller.

3. The method of claim 1, wherein the refractory sampling probe comprises a fume filter, and the filter is a quartz filter configured to filter dust greater than 20 μm.

4. The method of claim 1, wherein the heater is used to heat the flue gas duct, the heating temperature being adjusted between room temperature and 380 ℃ based on the bulk temperature of the flue gas; when the temperature of the flue gas body is more than 380 ℃, the temperature of the heater is set to be 380 ℃, and when the temperature of the flue gas body is less than 380 ℃, the temperature of the heater is set to be the temperature of the flue gas body.

5. The method according to claim 1, characterized in that the up-going flue gas volume flow controller 3 is used to regulate and control the gas instantaneous flow of the flue gas up-going pipe 5; the descending flue gas volume flow controller 4 is used for adjusting and controlling the gas instantaneous flow of the flue gas descending pipeline 6, and the flow speed range is 50-1000 ml/min.

6. Be arranged in simultaneous detection flue gas SO₂、SO₃The method is characterized by comprising three steps of preparing a standard sample, setting parameters and reacting and metering; selecting proper one from flue gas pipelineSampling points, namely inserting a high-temperature-resistant sampling pipe into a flue, and connecting the high-temperature-resistant sampling pipe and the flue in a sealed manner by using a flange for collecting the flue gas to be detected; and opening the fan to introduce the flue gas after the temperature of the flue gas pipeline reaches a set value and solutes in the oxidation reactor and the color-changing reactor are completely dissolved.

7. The method of claim 6, wherein the preparing the standard is based on the estimated SO in the flue gas to be measured_xThe sulfur-fixing agent and the color-changing reactant are respectively filled into the oxidation reactor and the color-changing reactor, the sulfur-fixing agent is the combination of the amounts of NaOH, deoxygenated deionized water and hydrogen peroxide, and the color-changing reactant is the combination of the amounts of NaOH, deoxygenated deionized water and iodine.

8. The method of claim 6, wherein setting parameters includes setting the heating temperature of the flue gas line, the gas volumetric flow controller, the agitation rate based on the bulk temperature of the flue gas; and starting heating and stirring, and opening a flue gas fan to introduce flue gas after the temperature of a flue gas pipeline reaches a set value and solutes in the oxidation reactor and the color-changing reactor are completely dissolved.

9. The method of claim 6, wherein the reacting comprises recording the time t at which the flue gas is pumped₁And the time t when the color of the color-changing reactor is disappeared and the introduction of the flue gas is stopped₂Analyzing SO in solution in oxidation reactor and color-changing reactor by ion chromatographic system₄ ^2-Concentration c of₁、c₂(mg/L); respectively calculating SO in the flue gas according to the following formula₂、SO₃Concentration (mg/Nm)³)。

Wherein m is_IMg is the mass of iodine in the color change reactor; m_IIs the relative atomic mass of iodine; t is t₁、t₂Respectively the starting time and the ending time of the introduction of the flue gas, min; v is the volume flow rate of the flue gas, ml/min; t is_{Sign board}Is the temperature at standard conditions of flue gas, DEG C; t is_{Is provided with}The temperature of the flue gas in the flue gas heater is DEG C; c_SO2Is SO in flue gas₂Content of (1), mg/Nm³；c₁、c₂SO in an oxidation reactor and a color-changing reactor respectively₄ ^2-Concentration of (2), mg/L; v is the volume of solution in the oxidation reactor or color change reactor, ml.

Technical Field

The invention belongs to the technical field of flue gas treatment, and particularly relates to a method for simultaneously detecting SO in flue gas₂、SO₃The apparatus and method of (1).

Background

The sulfur oxides produced during the combustion of industrial fossil fuels are mainly SO₂And a small amount of SO₃It is a serious pollutant. Taking coal-fired power plant as an example, SO in high-temperature flue gas₂In an amount of several hundred to several thousand ppm, SO₃In an amount of about SO₂0.5-5.0% of SO_xThe pollution-free environment-friendly type acid rain water is extremely harmful to human bodies, is a main reason for forming acid rain, and is one of important sources of PM2.5 in the atmosphere. The existing desulfurization method can effectively remove SO₂The removal efficiency can reach 98 percent, but for SO₃The removal efficiency is low.

SO₃Is nonpolar molecule, is colorless transparent oily liquid at normal temperature, and has strong pungent taste. When the temperature of the flue gas is reduced to below about 300 ℃, SO contained in the flue gas₃The gas combines with the water vapor to form sulfuric acid. Sulfuric acid has a higher boiling point, thereby causing the flue gas to have a higher acid dew point. When the concentration of the sulfuric acid in the flue gas is 1-50ppm, the dew point of the flue gas is about 110-160 ℃. SO in flue gas_xNot only causes the corrosion of the equipment such as a heat exchanger of a waste heat boiler, but also can escape NH with excessive ammonia₃Reaction to form NH₄HSO_xAnd the like, which causes the blockage of the air preheater and the inactivation of the SCR catalyst and seriously affects the denitration efficiency of the SCR catalyst. In addition, SO produced by the combustion of industrial fossil fuels₃Not only acidic smoke plume is caused, but also blue or yellow smoke plume is formed during discharge, the turbidity of the smoke plume discharged from a chimney is increased, and the landscape is damaged.

In order to reduce the corrosion of combustion equipment, reduce the emission of acid gas and quantitatively evaluate the effects of different auxiliaries and flue gas treatment facilities, the demand for SO in flue gas is high₂、SO₃The concentration and its equilibrium relationship are measured accurately. Due to SO₃Very active in chemical property, very easy to be absorbed by water and adsorbed on the surface of various materials, and SO₃Very low concentration in flue gas and susceptible to SO₂Measuring influence, therefore SO₃Detection techniques have been difficult problems.

Traditional flue gas analyzer can not distinguish SO₂And SO₃Only, isCan detect SO in flue gas_xAnd (4) concentration. Due to SO₃Specific and lower concentration of existing SO₃Basically, the measurement method is to first sample the flue gas and then further analyze the content of the flue gas. Mainly comprises an isopropanol solution absorption-precipitation titration method and a controlled condensation method. Isopropanol solution absorption-precipitation titration method adopts 80% isopropanol water solution to treat SO₃High solubility to SO₂The characteristic of extremely low solubility, and the absorption of SO in flue gas₃And H₂SO₄It is dissolved and converted to SO₄ ^2-Then using H₂O₂Absorbing SO in flue gas₂Likewise converted to SO₄ ^2-Finally, use Ba²⁺Titration of the solution to determine SO in the solution₄ ^2-Content of SO in the flue gas₃Concentration and ratio of (c). Since isopropanol often contains peroxidized species, a portion of the SO will be removed₂Oxidation, the measurement results may be high. The control condensation method has more interference factors in the detection process, larger measurement error and incapability of ensuring the stability and repeatability of measurement.

Patent CN107515280A discloses a continuous online detection method and device for sulfur trioxide in flue gas, which is based on SO in flue gas₃Analysis of SO in flue gas by stoichiometric reaction with solid salt particles₃The solid salt particles are NaCl and FeS. When NaCl is sampled, the temperature of the reaction needs to be accurately controlled to ensure that the reactant SO is present₃And a fixed stoichiometric ratio of the reaction product HCl; when FeS is used, the reaction product has H₂S (highly toxic) and H₂S inevitably will react with SO_xA redox reaction occurs. Patent CN103472061A discloses an on-line detection device and method for sulfur trioxide in flue gas, which adopts a condensation method to carry out on SO in the flue gas₃Condensed and separated from the bulk of the gas phase, and the converted SO is analyzed by specific absorption peak detection of the light wave of the Ba salt precipitate or colored ions₃Further calculating the SO in the flue gas₃The content of (a). The method has the defects that the adopted condensation temperature is 60-80 ℃, and the method cannot ensure SO in the flue gas₃Is completely retained in the coiled pipe, easily causes analysis errors, and is not suitable for low SO₃Content of flue gas.

In view of the foregoing, it is directed to the analysis of SO in flue gases₂/SO₃In terms of content, numerous patents are basically characterized by on-line analysis, simple structure, process automation and the like, but generally lack of solid SO₂/SO₃Analytical theory basis, therefore for the detection of SO in flue gases₂/SO₃The accuracy of the content was unsatisfactory.

Disclosure of Invention

The invention aims to provide a method for simultaneously detecting SO in flue gas₂、SO₃The apparatus and method of (1). The method has high precision, good repeatability, wide detection range of 0.1mg/Nm³-several tens of thousands mg/Nm³The analysis method is established on the strict theoretical basis, overcomes the randomness and the contingency of in-situ measurement, and can simultaneously and accurately analyze the SO in the flue gas₂And SO₃Content of (2) is convenient for investigating SO in the flue gas₂And SO₃The balance relationship of (1).

The technical scheme of the invention is as follows:

be arranged in simultaneous detection flue gas SO₂、SO₃The device comprises a sampling system, a reaction system and a chromatographic system; the sampling system comprises a connecting component, a high-temperature-resistant sampling pipe 2 and a flue gas pipeline; the connecting component is a flange or other connection; the flue gas pipeline comprises a flue gas ascending pipeline 5 and a flue gas descending pipeline 6; the reaction system comprises an oxidation reactor and a color-changing reactor, wherein the oxidation reactor and the color-changing reactor are internally provided with stirring devices; the chromatographic system is an ion chromatograph; one end of the high-temperature sampling pipe 2 is connected with the flue, the other end of the high-temperature sampling pipe is connected with a flue gas pipeline through the two-way pipe, a flue gas ascending pipeline 5 is connected with an inlet of the oxidation reactor, a flue gas descending pipeline 6 is connected with an inlet of the color-changing reactor, and an outlet of the oxidation reactor and an outlet of the color-changing reactor are connected with the ion chromatograph.

The high-temperature sampling pipe is provided with a filter, a heater, a smoke power drive and a one-way valve; the heater is used for heating and insulating a flue gas pipeline; the one-way valve only allows the flue gas to enter the reaction system from the flue; the flue gas power drive is a flue gas fan and is used for providing pressure required by gas sampling and collection, and if the pressure in the flue is positive pressure, the sampling fan is not needed; the flue gas pipeline is a flue gas ascending pipeline 5 and a flue gas descending pipeline 6, and is respectively provided with a pipeline heat preservation and a gas volume flow controller.

The high-temperature-resistant sampling probe is provided with a flue gas filter, and the filter is a quartz filter and is used for filtering out dust larger than 20 micrometers.

The heater is used for heating a flue gas pipeline, and the heating temperature is adjusted at the room temperature to 380 ℃ according to the temperature of the flue gas body; when the temperature of the flue gas body is more than 380 ℃, the temperature of the heater is set to be 380 ℃, and when the temperature of the flue gas body is less than 380 ℃, the temperature of the heater is set to be the temperature of the flue gas body.

The flue gas volume flow controller 3 is used for adjusting and controlling the instantaneous gas flow of the flue gas descending pipeline 6; the flue gas volume flow controller 4 is used for adjusting and controlling the gas instantaneous flow of the flue gas ascending pipeline 5, and the flow speed range is 50-1000 ml/min.

The invention is used for simultaneously detecting SO in flue gas₂、SO₃The method comprises three steps of preparing a standard sample, setting parameters and reacting and metering; selecting a proper sampling point on a flue gas pipeline, inserting a high-temperature-resistant sampling pipe into the flue, and connecting the sampling pipe and the flue in a sealing manner by using a flange for collecting flue gas to be detected; and opening the fan to introduce the flue gas after the temperature of the flue gas pipeline reaches a set value and solutes in the oxidation reactor and the color-changing reactor are completely dissolved.

The standard sample preparation is based on the estimated SO in the flue gas to be measured_xThe sulfur-fixing agent and the color-changing reactant are respectively filled into the oxidation reactor and the color-changing reactor, the sulfur-fixing agent is the combination of the amounts of NaOH, deoxygenated deionized water and hydrogen peroxide, and the color-changing reactant is the combination of the amounts of NaOH, deoxygenated deionized water and iodine.

The set parameters comprise the heating temperature, the gas volume flow controller and the stirring speed of the flue gas pipeline with the set temperature according to the temperature of the flue gas body; and starting heating and stirring, and opening a flue gas fan to introduce flue gas after the temperature of a flue gas pipeline reaches a set value and solutes in the oxidation reactor and the color-changing reactor are completely dissolved.

The reaction metering comprises recording the time t of pumping smoke₁And the time t when the color of the color-changing reactor is disappeared and the introduction of the flue gas is stopped₂Analyzing SO in solution in oxidation reactor and color-changing reactor by ion chromatographic system₄ ^2-Concentration c of₁、 c₂(mg/L); respectively calculating SO in the flue gas according to the following formula₂、SO₃Concentration (mg/Nm)³)。

Wherein m is_IMg is the mass of iodine in the color change reactor; m_IIs the relative atomic mass of iodine; t is t₁、t₂Respectively the starting time and the ending time of the introduction of the flue gas, min; v is the volume flow rate of the flue gas, ml/min; t is_{Sign board}Is the temperature at standard conditions of flue gas, DEG C; t is_{Is provided with}The temperature of the flue gas in the flue gas heater is DEG C; c_SO2Is SO in flue gas₂Content of (1), mg/Nm³；c₁、 c₂SO in an oxidation reactor and a color-changing reactor respectively₄ ^2-Concentration of (2), mg/L; v is the volume of solution in the oxidation reactor or color change reactor, ml.

The concrete description is as follows:

the method is used for simultaneously detecting SO in flue gas₂、SO₃The device comprises a sampling system, a reaction system and a chromatographic system; the sampling system comprises a high-temperature-resistant sampling pipe and a flue gas pipeline, wherein a filter, a heater, a flue gas power drive and a one-way valve are arranged in the high-temperature sampling pipe; the flue gas pipeline is a flue gas ascending pipeline 5 and a flue gas descending pipeline 6 which are respectively provided withPipeline heat preservation, gas volume flow controller. The flue gas power drive is a flue gas fan and is used for providing pressure required by gas sampling and collecting, and if the pressure in the flue is positive pressure, the sampling fan is not needed. The reaction system comprises an oxidation reactor and a color-changing reactor, wherein the oxidation reactor is used for reacting the flue gas medium in the flue gas ascending pipeline 5 to remove SO in the flue gas_xWith SO₄ ^2-The form of (1) is fixed; the color-changing reactor is used for the reaction of the flue gas medium in the flue gas descending pipeline 6 and is used for quantifying SO in the flue gas₂The content of (A); the chromatographic system is an ion chromatograph and can accurately analyze SO in the solution₄ ^2-And (4) content.

The high-temperature-resistant sampling probe is provided with a flue gas filter, and the filter is a quartz cotton filter and is used for filtering dust larger than 20 microns. The heater is used for heating a flue gas pipeline, so that measurement errors caused by flue gas condensation are avoided, and the heating temperature can be adjusted at the room temperature of 380 ℃ according to the temperature of a flue gas body. When the temperature of the flue gas body is more than 380 ℃, the temperature of the heater is set to be 380 ℃, and when the temperature of the flue gas body is less than 380 ℃, the temperature of the heater is set to be the temperature of the flue gas body. The gas volume flow controller 3 is used for adjusting and controlling the gas instantaneous flow of the flue gas in the flue gas downlink pipeline 6; the gas flow controller 4 is used for adjusting and controlling the gas instantaneous flow of the flue gas in the flue gas ascending pipeline 5, and the flow speed ranges from 50ml/min to 1000 ml/min.

The oxidation reactor and the color-changing reactor are made of quartz products, are resistant to high temperature, are internally provided with stirring devices, have the volume of 500ml, and have the stirring speed of 50-200 r/min; the flue gas enters an oxidation reactor and a color-changing reactor from the bottom part in two ways; sampling system, reaction system and chromatographic system connect gradually, the connected mode is that 2 one end of high temperature sampling pipe connects the flue, and the other end is through two-way connection flue gas pipeline, and the oxidation reactor entry is connected to flue gas upward pipeline 5, and the reactor entry that discolours is connected to flue gas downward pipeline 6, and oxidation reactor export and the reactor export that discolours are connected with an ion chromatogram respectively.

In the invention, SO in flue gas is detected₂、SO₃The method comprises preparing standard sample and setting parametersAnd reaction metering, specifically comprising selecting a proper sampling point on a flue gas pipeline, inserting a high-temperature-resistant sampling pipe into the flue, and connecting the sampling pipe with a flange in a closed manner for collecting the flue gas to be detected. And opening the fan to introduce the flue gas after the temperature of the flue gas pipeline reaches a set value and solutes in the oxidation reactor and the color-changing reactor are completely dissolved.

The preparation standard sample is prepared by preparing an oxidation sulfur fixing agent and a color-changing reactant, and the oxidation sulfur fixing agent and the color-changing reactant are respectively filled into an oxidation reactor and a color-changing reactor, wherein the oxidation sulfur fixing agent is a combination of the amounts of NaOH, deoxygenated deionized water and hydrogen peroxide, and the color-changing reactant is a combination of the amounts of NaOH, deoxygenated deionized water and iodine (containing starch).

The standard sample preparation is based on the estimated SO in the flue gas to be measured_xThe content (see the standard sample preparation table) is determined according to the following formula 1, and the amount of iodine in the color-changing reactant is determined according to the SO in the following chemical reaction formula 2₂And H₂O₂Determination of H in sulfur-fixing agent by using NaOH metering relation₂O₂Quality of NaOH, ensuring H₂O₂Excess NaOH, SO according to the following reaction equation 3₂And N_aThe amount of the color-changing reactant is determined by the metering relation of OH, and the excess of NaOH is ensured. The amount of the deoxidized deionized water is more than or equal to a proper value of 50ml, so that NaOH, iodine and other substances are dissolved.

Wherein M is_SO2Is SO₂Molecular weight of (1), M_I2Is the molecular weight of iodine.

Standard sample preparing table

The set parameters comprise the heating temperature of the flue gas pipeline with the set temperature according to the temperature of the flue gas body; setting a flue gas volume flow controller and setting a stirring speed; opening a fan to introduce the flue gas after the temperature of the flue gas pipeline reaches a set value and solutes in the oxidation reactor and the color-changing reactor are completely dissolved; the reaction metering comprises recording the volume V of solution in the oxidation reactor and the color-changing reactor, the mass m of iodine in the color-changing reactor, recording the volume flow V of flue gas, and recording the time t of pumping the flue gas₁When the blue color of the color-changing reactor disappears (does not change within 1-2 min), the smoke gas is stopped to be introduced at the time t₂Analyzing SO in solution in oxidation reactor and color-changing reactor by ion chromatographic system₄ ^2-Concentration c of₁、c₂(mg/L)。

The color-changing reactor is filled with a color-changing reactant (containing a small amount of starch) to perform the following oxidation reaction, SO as to calculate SO in the flue gas₂The content of (a).

The oxidation reactor is filled with an oxidation sulfur-fixing agent (N)_aOH excess) in which SO is first generated_xAbsorption reaction and oxidation reaction, aiming at removing SO in the flue gas_XCompletely fixed in sulfuric acid ions. The following reactions mainly occur, with equilibrium constants > 10⁵Belonging to the typical irreversible reaction, can completely fix SO_xIn the sulfate salt.

According to the stoichiometric ratio of the above reaction, nSO₄ ^2-With nSO_x1:1, SO detected by ion chromatography₄ ^2-The total SO introduced into the flue gas is calculated and calculated_xThe amount of (c). Respectively calculating SO in the flue gas according to the following formula₂、SO₃Concentration (mg/Nm)³)。

Wherein m is_IMg is the mass of iodine in the color change reactor; m_IIs the relative atomic mass of iodine; t is t₁、t₂Respectively the starting time and the ending time of the introduction of the flue gas, min; v is the volume flow rate of the flue gas, ml/min; t is_{Sign board}Is the temperature at standard conditions of flue gas, DEG C; t is_{Is provided with}The temperature of the flue gas heated in the flue gas is DEG C; c_SO2Is SO in flue gas₂Content of (1), mg/Nm³；c₁、c₂SO in an oxidation reactor and a color-changing reactor respectively₄ ^2-Concentration of (2), mg/L; v is the volume of solution in the oxidation reactor or color change reactor, ml.

The invention provides a method for simultaneously detecting SO in flue gas₂、SO₃In which the oxidation reactor acts on the flue gas in the flue gas ascending pipeline, using a fixed quantity of H₂O₂NaOH and deionized water are used for removing SO in the flue gas_xConversion to SO₄ ^2-The color-changing reactor acts on the flue gas in the flue gas descending pipeline, and the SO in the flue gas is accurately analyzed by an iodometry method₂In an amount of and adding SO_xConversion to SO₄ ^2-. Determination of SO in solution by chromatographic system₄ ^2-Concentration and calculation of total SO in flue gas_xThe content is finally calculated by adopting a differential subtraction method to obtain SO in the flue gas₃The measurement of the two flue gases can be carried out simultaneously, the measurement result is accurate, and SO is reduced₂The influence of (c). The method has high precision, good repeatability, wide detection range of 0.1mg/Nm³-several tens of thousands mg/Nm³The analysis method is established on the strict theoretical basis, overcomes the randomness and the contingency of in-situ measurement, and can simultaneously and accurately analyze the SO in the flue gas₂And SO₃Content of (2) is convenient for investigating SO in the flue gas₂And SO₃The balance relationship of (1). The invention adopts an indirect method to avoid the problem of small amount of SO₃Direct measurement, and the adoption of an alkali liquor system can avoid the escape of ammonia from NH₃The interference of reducing gas ensures SO₃The accuracy of the analysis results.

Drawings

FIG. 1: is used for simultaneously detecting SO in flue gas₂、SO₃Schematic diagram of the apparatus of (1).

FIG. 2: is a schematic diagram of a high temperature resistant sampling tube.

Wherein A-the sampling system; b-reaction system; c-chromatographic system; 1-flue; 2-high temperature resistant sampling tube; 3-ascending flue gas volume flow controller; 4-volume flow controller of downward flue gas; 5-flue gas ascending pipeline; 6-flue gas descending pipeline; 7-oxidation reactor; 8-color change reactor; 9-stirrer; 10-chromatograph; 11-a filter; 12-a flange; 13-a heater; 14-flue gas power drive; 15-one-way valve.

Detailed Description

In order to make the objects and advantages of the present invention more apparent, the following detailed description of the steps for carrying out the present invention is provided in conjunction with examples. The ovens referred to in the experiments, i.e. the electrically heated constant temperature forced air drying ovens (containing inert gas systems), precision metering pumps (lecean 3000), level gauges, controllers, liquid-liquid separation and other related terms, are not limiting to the invention, are for the purpose of describing particular embodiments only, are not intended to limit the invention and should not be construed as being limited to the embodiments set forth herein.

The device is shown in figures 1 and 2: the device comprises a sampling system A, a reaction system B and a chromatographic system C; the sampling system comprises a connecting component, a high-temperature-resistant sampling pipe 2 and a flue gas pipeline; the connecting component is connected by a flange 12 or other connecting modes; the flue gas pipeline comprises a flue gas ascending pipeline 5 and a flue gas descending pipeline 6; the reaction system comprises an oxidation reactor 7 and a color-changing reactor 8, wherein stirrers 9 are arranged in the reactors; the chromatographic system is an ion chromatograph 10; one end of a high-temperature sampling pipe 2 is connected with a flue 1, the other end of the high-temperature sampling pipe is connected with a flue gas pipeline through a two-way pipe, a flue gas ascending pipeline 5 is connected with an inlet of an oxidation reactor, a flue gas descending pipeline 6 is connected with an inlet of a color-changing reactor, and an outlet of the oxidation reactor and an outlet of the color-changing reactor are connected with an ion chromatographic phase. The high-temperature sampling pipe is provided with a filter 11, a heater 13, a smoke power drive 14 and a one-way valve 15; the flue gas power drive is a flue gas fan and is used for providing pressure required by gas sampling and collection, and if the pressure in the flue is positive pressure, the sampling fan is not needed; the gas pipeline is a flue gas ascending pipeline 5 and a flue gas descending pipeline 6, and the pipeline heat preservation and gas volume flow controller are respectively arranged. The gas volume flow controller 3 is used for adjusting and controlling the gas instantaneous flow of the flue gas in the flue gas downlink pipeline 6; the gas flow controller 4 is used for adjusting and controlling the gas instantaneous flow of the flue gas in the flue gas ascending pipeline 5.

Simultaneously detecting SO in flue gas₂、SO₃The method comprises three steps of preparing a standard sample, setting parameters and reacting and metering; selecting a proper sampling point on a flue gas pipeline, inserting a high-temperature-resistant sampling pipe into the flue, and connecting the sampling pipe and the flue in a sealing manner by using a flange for collecting flue gas to be detected; when the temperature of the flue gas pipeline reaches a set value and the oxidation reaction is carried outAfter the solutes in the reactor and the color-changing reactor are completely dissolved, the fan is opened to introduce the flue gas.

The preparation standard sample is prepared by preparing an oxidation sulfur fixing agent and a color-changing reactant, and the oxidation sulfur fixing agent and the color-changing reactant are respectively filled into an oxidation reactor and a color-changing reactor, wherein the oxidation sulfur fixing agent is the combination of the amounts of NaOH, deoxygenated deionized water and hydrogen peroxide, and the color-changing reactant is N_aThe combination of the amounts of OH, oxygen-depleted deionized water, and iodine (starch-containing). (see the following preparation standard sample table for details) the preparation standard sample is the standard sample according to the estimated SO in the smoke to be detected_xContent (see table), determining the amount of iodine in the color-changing reactant according to the following formula 1, and SO in the following chemical reaction formula 2₂And H₂O₂Determination of H in sulfur-fixing agent by using NaOH metering relation₂O₂Quality of NaOH, ensuring H₂O₂Excess NaOH, SO according to the following reaction equation 3₂And N_aThe amount of the color-changing reactant is determined by the metering relation of OH, and the excess of NaOH is ensured. The amount of the deoxidized deionized water is more than or equal to a proper value of 50ml, so that NaOH, iodine and other substances are dissolved.

Standard sample preparing table

Example 1

The temperature of certain catalytic regeneration flue gas is 500 ℃. Before sampling, a proper sampling point needs to be selected on a flue gas pipeline, a sampling port with the diameter DN40 is arranged on the sampling point, and a standard gas sampling probe is inserted into a flue and is connected in a flange sealing manner for collecting the flue gas to be detected. N for gas pump₂A reverse purging cleaning pipeline and a filter (the filter prevents solid particles in the flue gas from entering a detection system) are opened to heat and preheat a flue gas sampling pipeline, and the temperature is set to 380 ℃.

Arranged in a flue gas ascending pipeline 5 and a flue gas descending pipeline 6The gas volume flow meter is 300ml/min, and can estimate SO in the flue gas_xLess than 500mg/Nm³50.0ml of deoxygenated deionized water, 8.0mg of hydrogen peroxide (analytically pure) and 18.0mgN are added into an oxidation reactor 7_aOH (analytical purity). To the color change reactor 8 was added 50.0ml of deoxygenated deionized water, 10.0mg iodine (analytical grade), 36mg NaOH (analytical grade) and 1d starch solution. The stirring was turned on and the stirring rate was set at 100 r/min.

And when the temperature of the sampled flue gas pipeline rises to 380 ℃, and the reagents in the oxidation reactor 7 and the color-changing reactor 8 are completely dissolved, opening the exhaust fan, and pumping the flue gas into the oxidation reactor 7 and the color-changing reactor 8 for reaction and quantification. When the blue color in the color-changing reactor is cooled down (no color change occurs within 1 min), the exhaust fan is stopped, and the time delta t for introducing the smoke is recorded as 7.5 min.

The volume V/ml ═ Deltat/min ═ 300ml/min ═ 7.5 ═ 300 ═ 2.25L of the smoke at 400 DEG C

Wherein SO₂Amount of substance(s) n₁The mass m was 10.0mg/(126.9mg/mmol × 2) ═ 0.0394mmol₁Is composed of

2.52 mg. Can calculate the SO in the flue gas under the condition of 400 DEG C₂Has a concentration of 1120.0mg/m³Converted to 2769.2 mg/Nm³. Ion chromatography for respectively detecting SO of solution in oxidation reactor and color-changing reactor₄ ^2-The content was 109.5mg/L and 108.0mg/L, and the average value was 108.8 mg/L. Total SO_xIn an amount of 0.057mmol of the substance (b), wherein SO₂The amount of substance(s) n1 is 0.055mmol, SO can be calculated by differential subtraction₃The amount of substances (b) is 0.0015mmol, SO that the flue gas contains SO₃Has a concentration of 132.3mg/Nm³See table one, about 5% conversion.

Watch 1

Example 2 the flue gas temperature of a certain economizer was 300 ℃. Before sampling, a proper sampling point needs to be selected on a flue gas pipeline, a sampling port with the diameter DN40 is arranged on the sampling point, and a standard gas sampling probe is inserted into a flue and is connected in a flange sealing manner for collecting the flue gas to be detected. N for gas pump₂And (2) reversely purging and cleaning the pipeline and the filter, (the filter prevents solid particles in the flue gas from entering a detection system) opening a pipeline for heating, preheating and sampling the flue gas, and setting the temperature at 300 ℃.

The gas volume flow meters in the flue gas ascending pipeline 5 and the flue gas descending pipeline 6 are set to be 200ml/min, SO that SO in the flue gas can be estimated_xAt 500-1000mg/Nm³In the range, 100.0ml of deoxygenated deionized water, 16.0mg of hydrogen peroxide (analytical grade), 36.0mg of NaOH (analytical grade) were added to the oxidation reactor. 100.0ml of deoxygenated deionized water, 20.0mg of iodine (analytically pure) and 76mgN were added to the color change reactor_aOH (analytical grade) and 1d starch solution. The stirring was turned on and the stirring rate was set at 150 r/min.

And when the temperature of the sampled flue gas pipeline rises to 300 ℃, and NaOH in the reactor is completely dissolved, opening the exhaust fan, and pumping the flue gas into the reactor for reaction and quantification.

When the blue color in the color-changing reactor is cooled down (no color change occurs within 1 min), the exhaust fan is stopped, and the time delta t for introducing the smoke is recorded as 20 min. The volume V/ml ═ Deltat/min ═ 200ml/min ═ 20 ═ 200 ═ 4.00L of the smoke at 300 DEG C

Wherein SO₂The amount of substance (n 1) was 20.0mg/(126.9mg/mmol × 2) ═ 0.0788mmol, and the mass m1 was 5.04 mg. Can calculate the SO in the flue gas at 300 DEG C₂The concentration of (2) was 1260.0mg/m3, which was converted to 2643.9mg/Nm 3.

Ion chromatography for respectively detecting SO of solution in oxidation reactor and color-changing reactor₄ ^2-The content was 109.5mg/L and 108.0mg/L, and the average value was 108.8 mg/L. Total SO_xIn an amount of 0.057mmol of the substance (b), wherein SO₂The amount of substance(s) n1 is 0.055mmol, SO can be calculated by differential subtraction₃The amount of substances (b) is 0.0015mmol, SO that the flue gas contains SO₃Has a concentration of 132.3mg/Nm³In the tableTwo, about 1.25% conversion.

Watch two

Example 3 the stack flue gas temperature was 50 ℃. Before sampling, a proper sampling point is selected on a flue gas pipeline, a sampling port with the diameter DN40 is arranged at the sampling point, and a standard gas sampling probe is inserted into a flue and is in closed connection. N for gas pump₂The back purge cleans the line and filter (the filter prevents solid particles in the flue gas from entering the detection system).

And opening a heating preheating sampling flue gas pipeline, and setting the temperature to be 50 ℃. Setting the gas volume flow meter in the flue gas ascending pipeline 5 and the flue gas descending pipeline 6 to be 500ml/min, adopting the scheme 1, adding 50.0ml of deoxygenated deionized water, 8.0mg of hydrogen peroxide (analytically pure) and 18.0mgN into the oxidation reactor_aOH (analytical purity). 50.0ml of deoxygenated deionized water, 10.0mg of iodine (analytical grade), 36mg of NaOH (analytical grade) and 1d of starch solution were added to the color change reactor. The stirring was turned on and the stirring rate was set at 100 r/min.

And when the temperature of the sampled flue gas pipeline rises to 50 ℃ and NaOH in the reactor is completely dissolved, opening the exhaust fan, and pumping the flue gas into the reactor for reaction and quantification. When the blue color in the color-changing reactor is cooled down (no color change occurs within 1 min), the exhaust fan is stopped, and the time delta t for introducing the smoke is recorded as 30 min.

The volume V/ml ═ Deltat/min ═ 500ml/min ═ 30 ═ 500 ═ 15.00L of the smoke at 50 ℃

Wherein SO₂The amount of substance(s) n1 was 10.0mg/(126.9mg/mmol × 2) ═ 0.0394mmol, and the mass m1 was 2.52 mg. Can calculate the SO in the flue gas at 50 DEG C₂The concentration of (b) was 1260.0mg/m3, which was 2643.9mg/Nm in terms of conversion³。

Ion chromatography for respectively detecting SO of solution in oxidation reactor and color-changing reactor₄ ^2-The content was 39.0mg/L, 39.0mg/L, and the average value was 39.0 mg/L. Total SO_xIn an amount of 0.0406mmol of the substance(s) in which SO₂Of (2)The amount of (b) n1 is 0.0394mmol, and SO can be calculated by subtraction₃The amount of substances (b) is 0.0013mmol, SO that the flue gas contains SO₃Has a concentration of 3.94mg/Nm³See table three, about 3.07% conversion.

Watch III

Example 4 the high temperature economizer temperature for a coal combustion flue gas was 320 c. Before sampling, a proper sampling point needs to be selected on a flue gas pipeline, a sampling port with the diameter DN40 is arranged on the sampling point, and a standard gas sampling probe is inserted into a flue and is connected in a flange sealing manner for collecting the flue gas to be detected. N for gas pump₂And (2) reversely purging and cleaning the pipeline and the filter, (the filter prevents solid particles in the flue gas from entering a detection system) opening a pipeline for heating and preheating the sampled flue gas, and the temperature is set to be 320 ℃.

The gas volume flow meters in the flue gas ascending pipeline 5 and the flue gas descending pipeline 6 are set to be 100ml/min, SO that SO in the flue gas can be estimated_xAt 1000-1500mg/Nm³In the range, 150.0ml of deoxygenated deionized water, 24.0mg of hydrogen peroxide (analytically pure) and 55.0mg of N are added into an oxidation reactor_aOH (analytical purity). 150.0ml of deoxygenated deionized water, 30.0mg of iodine (analytically pure) and 110mgN were added to the color change reactor_aOH (analytical grade) and 1d starch solution. The stirring was turned on and the stirring rate was set at 100 r/min.

And when the temperature of the sampled flue gas pipeline rises to 320 ℃, and NaOH in the reactor is completely dissolved, opening the exhaust fan, and pumping the flue gas into the reactor for reaction and quantification.

When the blue color in the color-changing reactor is cooled down (no color change occurs within 1 min), the exhaust fan is stopped, and the time delta t for introducing the smoke is recorded as 30 min. Volume V/ml ═ Δ t/min ═ 100ml/min ═ 30 ═ 100 ═ 3.00L of smoke at 320 DEG C

Wherein SO₂The amount of substance n1 is 30.0mg/(126.9mg/mmol 2) ═ 0.1183mmol, the mass m1 is

7.57 mg. Can calculate the SO in the flue gas at 320 DEG C₂Has a concentration of 1260.0mg/m³Converted to 5485.51mg/Nm³。

Ion chromatography for respectively detecting SO of solution in oxidation reactor and color-changing reactor₄ ^2-The content was 80.0mg/L, 84.2mg/L, and the average value was 82.1 mg/L. The total SOx mass was 0.1283mmol, where SO₂The amount of substance(s) n1 is 0.1183mmol, SO can be calculated by subtraction₃The amount of substances (b) is 0.01mmol, SO that the flue gas contains SO₃The concentration of (A) is 579.71mg/Nm³See table four, about 7.80% conversion.

Watch four

Example 5 the flue gas temperature before a certain denitration reactor was 380 ℃. Before sampling, a proper sampling point needs to be selected on a flue gas pipeline, a sampling port with the diameter DN40 is arranged on the sampling point, and a standard gas sampling probe is inserted into a flue and is connected in a flange sealing manner for collecting the flue gas to be detected. N for gas pump₂And (2) reversely purging and cleaning the pipeline and the filter, (the filter prevents solid particles in the flue gas from entering a detection system) opening a pipeline for heating, preheating and sampling the flue gas, and setting the temperature at 380 ℃.

The gas volume flow meters in the flue gas ascending pipeline 5 and the flue gas descending pipeline 6 are set to be 200ml/min, SO that SO in the flue gas can be estimated_xAt 1500-³In the range, 200.0ml of deoxygenated deionized water, 32.0mg of hydrogen peroxide (analytically pure) and 70.0mg of N are added into an oxidation reactor_aOH (analytical purity). 200.0ml of deoxygenated deionized water, 50.0mg of iodine (analytically pure) and 140mgN were added to the color change reactor_aOH (analytical grade) and 1d starch solution. The stirring was turned on and the stirring rate was set at 100 r/min.

And when the temperature of the sampled flue gas pipeline rises to 380 ℃ and NaOH in the reactor is completely dissolved, opening the exhaust fan, and pumping the flue gas into the reactor for reaction and quantification. When the blue color in the color-changing reactor is cooled down (no color change occurs within 1 min), the exhaust fan is stopped, and the time delta t for introducing the smoke is recorded as 60 min.

The volume V/ml ═ Deltat/min ═ 200ml/min ═ 60 ═ 200 ═ 12.00L of the smoke at 380 deg.C

Wherein SO₂The amount of substance n1 is 50.0mg/(126.9mg/mmol 2) ═ 0.1970mmol, the mass m1 is

12.61 mg. Can calculate the SO in the flue gas under the condition of 380 DEG C₂Has a concentration of 1050.83mg/m³Converted to 2511.95mg/Nm³。

Ion chromatography for respectively detecting SO of solution in oxidation reactor and color-changing reactor₄ ^2-The content was 97.00mg/L and 96.95mg/L, and the average value was 96.98 mg/L. Total SO_xThe amount of substance (b) is 0.2020mmol, where SO₂The amount of substance(s) n1 is 0.1970mmol, SO can be calculated by subtraction₃The amount of substances (a) is 0.005mmol, SO that the flue gas contains SO₃Has a concentration of 79.68mg/Nm³See table five, conversion of about 2.47%.

Watch five

Example 6 certain FCC regeneration flue gas exit temperatures were 550 ℃. Before sampling, a proper sampling point needs to be selected on a flue gas pipeline, a sampling port with the diameter DN40 is arranged on the sampling point, and a standard gas sampling probe is inserted into a flue and is connected in a flange sealing manner for collecting the flue gas to be detected. N for gas pump₂And (2) reversely purging and cleaning the pipeline and the filter, (the filter prevents solid particles in the flue gas from entering a detection system) opening a pipeline for heating, preheating and sampling the flue gas, and setting the temperature at 380 ℃.

The gas volume flow meters in the flue gas ascending pipeline 5 and the flue gas descending pipeline 6 are set to be 50ml/min, SO that SO in the flue gas can be estimated_xAt > 2500mg/Nm³In the range, 300.0ml of deoxygenated deionized water, 44.0mg of hydrogen peroxide (analytical grade), 100.0mg of NaOH (analytical grade) were added to the oxidation reactor. 300.0ml of deoxygenated deionized water, 70.0mg of iodine (analytical grade), 200mg of NaOH (analytical grade) and 1d of starch solution were added to the color change reactor. The stirring was turned on and the stirring rate was set at 200 r/min.

And when the temperature of the sampled flue gas pipeline rises to 380 ℃ and NaOH in the reactor is completely dissolved, opening the exhaust fan, and pumping the flue gas into the reactor for reaction and quantification. When the blue color in the color-changing reactor is cooled down (no color change occurs within 1 min), the exhaust fan is stopped, and the time delta t for introducing the smoke is recorded as 300 min.

The volume V/ml of the smoke at 550 ℃ ═ Deltat/min ═ 50ml/min ═ 300 ═ 50 ═ 15.00L

Wherein SO₂The amount of substance n1 is 70.0mg/(126.9mg/mmol 2) ═ 0.2758mmol, the mass m1 is

17.65 mg. Can calculate the SO in the flue gas at the temperature of 550 DEG C₂The concentration of (2) was 1176.67mg/m3, which was converted to 3544.18mg/Nm 3.

Ion chromatography for respectively detecting SO of solution in oxidation reactor and color-changing reactor₄ ^2-The content was 90.00mg/L and 90.02mg/L, and the average value was 90.01 mg/L. The total SOx mass was 0.2813mmol, where SO₂The amount of substance(s) n1 is 0.2758mmol, SO can be calculated by subtraction₃The amount of substances (2) is 0.0055mmol, SO the flue gas contains SO₃The concentration of (A) is 88.35mg/Nm³See table six, about 1.96% conversion.

Watch six