WO2023061248A1 - Form-based test method and apparatus for mercury in flue gas from stationary pollution source in whole process - Google Patents

Abstract

A form-based test method and apparatus for mercury in flue gas having a high concentration of SO2 from a stationary pollution source in a whole process. In the test method, mercury in flue gas is collected by means of an impinger box (30); on the basis of different pollution control nodes, different impinger combinations are used. Components of flue gases in different industries and pollution control nodes are analyzed, and a proper impinger combination mode is selected on the basis of an existing OH method by adjusting the types and concentrations of absorption liquids; thus, the effect of SO2 on adsorption of elemental mercury is reduced to the maximum extent, and the monitoring accuracy is improved; moreover, the post-treatment processes of the absorption liquids are simplified, and the treatment cost is reduced. The test method not only has good consistency and stability, but also is more flexible in monitoring means and more reasonable in cost, and meets requirements of various complex flue gas systems for monitoring mercury in flue gas.

Description

Speciation test method and test device for mercury in flue gas from stationary pollution sources

Cross References to Related Applications

This application claims the priority of the Chinese patent application with the application number 2021111840934 and titled "Method and device for fractal form testing of mercury in the whole process of flue gas from fixed pollution sources" submitted on October 11, 2021, which is incorporated by reference in its entirety into this article.

technical field

This application relates to the technical field of environmental monitoring, and in particular to a method and device for testing the fractal forms of mercury in the high _SO2 flue gas of a fixed pollution source.

Background technique

It is well known that mercury is extremely harmful to the environment and human health. Coal-fired power plants, industrial coal combustion, non-ferrous metal smelting industry, waste incineration, cement industry and other industries are the main sources of flue gas mercury emissions, so it is necessary to strictly monitor mercury in industrial flue gas.

The traditional detection method for mercury in flue gas is "HJ 543-2009 Determination of Mercury in Exhaust Gas from Stationary Pollution Sources by Cold Atomic Absorption Spectrophotometry". The SO ₂ in the gas can compete with mercury to be dissolved in the absorption liquid, which reduces the capture efficiency of the absorption liquid for mercury in the flue gas and affects the accuracy of flue gas mercury monitoring.

The current flue gas mercury detection mainly adopts "Standard Determination Methods for Elemental Mercury, Oxidized Mercury, Particulate Mercury and Total Mercury in Coal-fired Stationary Source Flue Gas" (ASTM standard method D6784-02, referred to as OH method) and "Stationary Source Metal Method for Determination of Emission Standards" (EPA Method 29).

The OH method is based on the three forms of mercury in the industrial flue gas (gaseous elemental mercury Hg ⁰ , gaseous divalent mercury Hg ²⁺ and particulate mercury Hg _p ), and isothermally (120°C) from the flue gas through the probe/filter system. Samples were taken at a constant speed in the channel airflow, and then a series of reactions were carried out in an ice bath, in which Hg _p was captured by the front-end quartz fiber filter paper; Hg ²⁺ was collected by three impact absorption bottles filled with 1mol/L KCl absorption liquid; Hg ⁰ Collected from 1 impingement bottle containing 10% _{H2O2 -5} % _HNO3 absorption solution and 3 impingement bottles _containing 4% _KMnO4 -10% _H2SO4 ; the last absorption bottle Silica gel is installed in it to dry the moisture in the flue gas.

Although the OH method and EPA method 29 have taken into account the interference of SO ₂ in flue gas, the upper limit of the anti-interference concentration for SO ₂ is low, only 0.25% and 0.5% respectively; Industrial flue gas with a high concentration of SO ₂ (>10%) (such as smelting flue gas before acid production in the non-ferrous metal industry) still cannot meet the monitoring requirements for mercury in flue gas from stationary pollution sources.

In addition, for some industrial flue gas with low sulfur content, the OH method and EPA method 29 do not distinguish the differences of flue gas components, and also use 10% hydrogen peroxide as the _SO2 absorption liquid, which increases the workload of neutralization by titration of the absorption liquid in the later stage , the treatment process is relatively cumbersome, which is not conducive to the realization of energy-saving and emission-reduction goals of production enterprises.

Contents of the invention

In order to solve the above problems, this application proposes an improvement to the existing OH method absorbing liquid in combination with the flue gas characteristics of coal-fired power plants, industrial coal-fired, non-ferrous metal smelting industry, waste incineration, cement industry, etc., to meet various complex requirements. Flue gas mercury monitoring requirements for flue gas systems.

The test method for flue gas mercury in the whole process of fixed pollution sources proposed in this application collects flue gas mercury through impact absorption bottle boxes; and uses different combinations of absorption bottles based on different pollution control nodes:

For flue gas sampling points where the SO ₂ concentration is less than 20%, the absorption bottle combination is: 3 bottles of 1.5mol/L KOH absorption solution + 1 bottle of 10% H ₂ O ₂ -HNO ₃ absorption solution + 3 bottles of 4% KMnO ₄ -10% H ₂ SO ₄ + 1 bottle of silica gel; conventional process flue gas in industries such as coal burning, waste incineration, cement, etc., its components are complex, and the concentration of SO ₂ usually does not exceed 20%. Through this combination of absorption liquids, it can Effective monitoring of flue gas mercury at the full-process emission nodes of such conventional process flue gas.

For flue gas sampling points where the mass concentration of _SO2 is less than 15% and mercury monitoring in different forms is required, the absorption bottle combination is: 1 bottle of 1mol/L KCl absorption solution + 2 bottles of 1.5mol/L KOH absorption solution + 1 bottle of 10 %H ₂ O ₂ -HNO ₃ absorption solution + 3 bottles of 4% KMnO ₄ -10% H ₂ SO ₄ + 1 bottle of silica gel. The smelting flue gas before acid production in the non-ferrous metal industry needs to be monitored by different forms of mercury and the concentration of SO ₂ is relatively high (>10%). Using this combination of absorption liquids can minimize the competition of SO ₂ for the absorption liquid, which is conducive to improving the flue gas. The absorption efficiency of atmospheric mercury.

For flue gas sampling points with SO ₂ concentration < 250ppm, the absorption bottle combination is: 3 bottles of 1mol/L KCl absorption solution + 1 bottle of 1% H ₂ O ₂ -HNO ₃ absorption solution + 3 bottles of 4% KMnO ₄ - 10% _H2SO4 + ₁ bottle of silica gel. The concentration of SO ₂ in flue gas after desulfurization in industries such as coal combustion, garbage incineration, and cement is relatively low. This combination of absorption liquid can be simple and resistant to low concentration SO ₂ , thereby simplifying the subsequent treatment process of the absorption liquid. Reduce processing costs.

In this application, through the analysis of flue gas components and pollution control nodes in different industries, and on the basis of the existing OH method, by adjusting the type and concentration of the absorption liquid, the combination of the above-mentioned absorption bottles is obtained, thereby reducing the impact of SO ₂ on elemental mercury to the greatest extent. The influence of adsorption improves the monitoring accuracy, and at the same time simplifies the post-treatment process of the absorption liquid and reduces the treatment cost.

Compared with the existing OH method, the test method described in this application not only has good consistency and stability, but also has more flexible monitoring means and more reasonable cost, which meets the flue gas mercury monitoring requirements of various complex flue gas systems.

Further, the concentration of the KOH absorption solution is 1.3-1.7 mol/L, preferably 1.5-1.6 mol/L. Studies have shown that by controlling the molar concentration of the KOH absorption solution within this range, it can fully absorb SO ₂ .

Further, the mass ratio of H ₂ O ₂ and HNO ₃ in the H ₂ O ₂ -HNO ₃ absorption solution is 1:1; studies have shown that by controlling the compounding of H ₂ O ₂ and HNO ₃ in this ratio, the Ensure sufficient _SO2 adsorption. Preferably, the mass concentration of H ₂ O ₂ and HNO ₃ is 10-12%, so as to fully absorb SO ₂ without interfering with the oxidative absorption of elemental mercury.

As one of the specific implementations of the present application, for the monitoring of flue gas mercury before acid production in the non-ferrous metal smelting industry, the combination of the absorption bottles is: 1 bottle of 100ml 1mol/L KCl absorption solution + 2 bottles of 100ml 1.5mol/L KOH absorption liquid + 1 bottle of 100ml 10% H ₂ O ₂ -HNO ₃ absorption solution + 3 bottles of 100ml 4% KMnO ₄ -10% H ₂ SO ₄ + 1 bottle of silica gel.

As another specific embodiment of the present application, for the collection of flue gas mercury in the whole process of flue gas from fixed sources in conventional industries, the combination of the absorption bottles is: use 3 bottles of 100ml 1.5mol/L KOH absorption solution + 1 bottle of 100ml 10% H ₂ O ₂ -HNO ₃ absorption solution + 3 bottles of 100ml 4% KMnO ₄ -10% H ₂ SO ₄ + 1 bottle of silica gel.

As another specific embodiment of the present application, for the monitoring of flue gas mercury after desulfurization of fixed pollution sources, the combination of the absorption bottles is: use 3 bottles of 100ml 1mol/L KCl absorption solution + 1 bottle of 100ml 1%H ₂ O ₂ -HNO ₃ absorption solutions + 3 bottles of 100ml 4% KMnO ₄ -10% H ₂ SO ₄ + 1 bottle of silica gel.

The present application also provides a testing device for mercury in the flue gas of a fixed pollution source, including an impact absorption bottle box; the impact absorption bottle box adopts the above-mentioned corresponding absorption bottle combination based on different pollution control nodes. By selecting a specific combination of absorption bottles, the influence of SO ₂ on the accuracy of flue gas mercury monitoring in the whole process can be minimized, while the post-treatment process of the absorption liquid can be simplified and the treatment cost can be reduced.

Further, the test device also includes a constant temperature sampling pipe, a constant temperature filter unit, a metering unit, power and control equipment; each equipment unit is connected by a Teflon tube, and all sampling joints are made of 304 stainless steel to improve the test device. corrosion resistance.

Further, the temperature of the thermostatic sampling bong is controlled at 125±5° C. to prevent condensation of water vapor in the flue gas and make it difficult for the mercury in the flue gas to completely enter the sampling collection system.

The constant temperature sampling smoke gun includes a sampling gun and a lining. When the flue gas temperature is higher than 200°C, the lining material is quartz or borosilicate glass; when the flue gas temperature is lower than 200°C, the lining material can be polytetrafluoroethylene.

The thermostatic sampling bong also includes a pitot tube and a sampling mouthpiece to ensure constant velocity sampling.

Further, the temperature of the constant temperature filter unit is controlled at 125±5° C., which is used to collect fly ash and capture particulate mercury.

The constant temperature filter unit is a filter or a quartz filter cartridge containing a quartz fiber filter membrane, which is used to intercept particulate matter in the exhaust gas; when the concentration of particulate matter in the flue gas exceeds 100mg/ ^m3 , the preferred filter unit is a quartz filter cartridge, or The front end of the filter is provided with a cyclone separator.

Further, the metering unit includes a thermocouple and a dry gas flowmeter for recording the temperature before the meter and the volume of the sampled flue gas.

Further, the power and regulation equipment includes a vacuum degree control device and a sampling pump, which are used to control the vacuum degree of the Pitot tube to achieve the purpose of constant-speed sampling.

The beneficial effects of the application are as follows:

This application aims at the characteristics of flue gas components of fixed pollution sources in different industries and pollution control nodes, and obtains a series of absorption liquid combination methods by adjusting the type and concentration of the absorption liquid to meet the monitoring requirements of the entire process discharge nodes of various complex flue gas systems; at the same time Through the combination selection of different absorption liquids, the flue gas mercury collection method is more flexible, the subsequent treatment arrangement of the absorption liquid is more reasonable, and the goal of energy saving and emission reduction of industrial flue gas is realized.

In addition, this application adopts corrosion-resistant stainless steel sampling joints to reduce the corrosion loss of high-concentration _SO2 on equipment.

Description of drawings

Fig. 1 is a schematic structural diagram of the flue gas mercury speciation testing device for the whole process of fixed pollution sources provided by the present application.

Figure 2 is a schematic diagram of the comparison between the test results of the full-process flue gas mercury speciation test method for fixed pollution sources provided by the present application and the test results of the OH method.

Figure 3 is a schematic diagram of the comparison between the test results of the high-concentration (>10%) full-process flue gas mercury speciation test method provided by the application and the test results of the traditional test method HJ 543-2009.

Fig. 4 is the test result of the whole-process flue gas mercury speciation test method for fixing various pollution sources provided by the present application.

Detailed ways

The following examples are used to illustrate the present application, but not to limit the scope of the present application.

Example 1

This embodiment provides a fractal form testing device for flue gas mercury in the whole process of a fixed pollution source, as shown in Figure 1, including:

Thermostatic sampling gun 10 (101 thermocouple, 102 sampling nozzle, 103 pitot tube, 104 pressure gauge and 105 high-sprayed silicon glass or quartz sampling liner);

Constant temperature filtration unit (constant temperature filter box) 20 (201 heating box, 202 membrane holder, 203 quartz filter membrane, the diameter of the filter membrane is 83mm, and the blocking efficiency of particles with a particle size greater than 0.3μm is not less than 99.95%);

Impact absorption bottle box 30;

Metering unit 40 (401 thermocouple, check valve 402 and dry gas meter 403);

Power and regulation equipment unit 50 (vacuum gauge 501, main valve 502 and vacuum pump 503).

Example 2

This embodiment provides a morphological testing method for mercury in the flue gas of a fixed pollution source, including: sampling, filtering, collecting, measuring, and regulating the flue gas using the testing device described in Example 1;

Among them, the collection adopts the impact absorption bottle box; different combinations of absorption bottles are used based on different pollution control nodes; among them:

(1) Conventional process flue gas refers to process flue gas in fixed pollution sources such as coal burning, cement, incineration, etc. The process refers to the process before and after denitrification, desulfurization, and dust removal of flue gas; Compositional features of _SO2 .

(2) The smelting flue gas before the colored acid production has the composition characteristics of high concentration SO ₂ .

(3) The tail gas after desulfurization has the composition characteristics of lower concentration SO ₂ .

The combinations of the absorbing solutions are shown in Table 1.

Table 1

Experimental example 1

Taking the whole process flue gas at the kiln tail of a cement factory as an example, the mercury concentration in the flue gas was tested using the test method described in this application and the OH method.

The flue gas at the kiln tail has complex components. Based on this, the combination of absorbing liquid corresponding to the flue gas in the conventional process in Table 1 is selected for testing, namely: 3 bottles of 100ml 1.5mol/L KOH absorbing liquid + 1 bottle of 100ml 10% H ₂ O ₂ -HNO ₃ absorption solution + 3 bottles of 100ml 4% KMnO ₄ -10% H ₂ SO ₄ + 1 bottle of silica gel.

The conventional absorption solution for OH method: 3 bottles of 100ml 1mol/L KCl absorption solution + 1 bottle of 100ml 10% H ₂ O ₂ -5% HNO ₃ absorption solution + 3 bottles of 100ml 4% KMnO ₄ -10% H ₂ SO ₄ + 1 bottle of silicone.

The result is shown in Figure 2:

The 6 groups of results tested by OH method range from 65.4μg/m ³ to 1374.4μg/m ³ ;

The 6 groups of results tested by the method described in this application range from 57.3 μg/m ³ to 1346.5 μg/m ³ , and the relative deviation fluctuates within 2.0% to 19.5%.

As can be seen from the test results, the test results of the method described in the present application have better consistency and stability with the test results of the OH method, indicating that the test results of the method described in the present application have better test performance.

Experimental example 2

Taking high-concentration _SO2 (>10%) flue gas before desulfurization in the non-ferrous metal smelting industry as an example, the mercury concentration in the flue gas was tested by using the test method described in this application and the traditional detection method HJ 543-2009, and at the same time Quality estimates.

The composition of the flue gas before desulfurization has the characteristics of high concentration of SO ₂ (>10%) and the need to monitor the different forms of mercury. Based on this, the combination of absorbing liquids corresponding to the smelting flue gas before the colored acid production in Table 1 was selected for testing, that is, using 1 bottle of 100ml 1mol/L KCl absorption solution + 2 bottles of 100ml 1.5mol/L KOH absorption solution + 1 bottle of 100ml 10% H ₂ O ₂ -HNO ₃ absorption solution + 3 bottles of 100ml 4% KMnO ₄ -10% H ₂ SO ₄ + 1 bottle of silicone.

The result is shown in Figure 3:

The test result (6122 μg/Nm ³ ) of the method described in this application is similar to the mass estimation result (6319 μg/Nm ³ ), and much higher than the test result (2123 μg/Nm ³ ) of the traditional detection method HJ 543-2009.

Experimental example 3

Use the method described in this application to conduct a full-process on-site test of the mercury emission concentration before and after dust removal of industrial flue gas in typical industries;

Table 2 summarizes the measured data of mercury and its compounds in coal-fired power plants, industrial boilers, non-ferrous metal smelting industry, cement industry and waste incineration plants, as well as the particulate mercury Hg _p , gaseous divalent mercury Hg ²⁺ , and gaseous elemental mercury in the laboratory. Relative standard deviation of mercury Hg ⁰ .

Table 2 The monitoring results of the whole process of fixed source flue gas in the whole industry

It can be seen from Table 2 that the method described in this application can meet the mercury speciation monitoring results of the whole industry and the whole process, which shows that this standard method has good adaptability.

Experimental example 4

Use the method described in this application to test the mercury concentration in the industrial flue gas of 47 enterprises, including 23 coal-fired power plants, 7 industrial boiler coal-fired plants, 5 waste incineration plants, 5 cement plants, and 5 non-ferrous metal smelting plants factory and 2 iron and steel plants, covering almost all current stationary source flue gas mercury emission industries.

The test results show that the mercury emissions of each enterprise have not been found to exceed the emission standards. The specific data are shown in Figure 4, which is consistent with the actual emission detection results. It shows that the test method described in this application meets the monitoring requirements of the discharge nodes in the whole process of various complex flue gas systems.

Claims (10)

1. A test method for flue gas mercury in the whole process of fixed pollution sources, which collects flue gas mercury through impact absorption bottle boxes; different combinations of absorption bottles are used based on different pollution control nodes:

   For flue gas sampling points where the SO ₂ concentration is less than 20%, the absorption bottle combination is: 3 bottles of 1.5mol/L KOH absorption solution + 1 bottle of 10% H ₂ O ₂ -HNO ₃ absorption solution + 3 bottles of 4% KMnO ₄ -10% H ₂ SO ₄ + 1 bottle of silica gel;

   For flue gas sampling points where the mass concentration of _SO2 is less than 15% and mercury monitoring by form is required, the absorption bottle combination is: 1 bottle of 1mol/L KCl absorption solution + 2 bottles of 1.5mol/L KOH absorption solution + 1 bottle of 10% H ₂ O ₂ -HNO ₃ absorption solution + 3 bottles of 4% KMnO ₄ -10% H ₂ SO ₄ + 1 bottle of silica gel;

   For flue gas sampling points with SO ₂ concentration < 250ppm, including sampling points after desulfurization in all industries, the absorption bottle combination is: 3 bottles of 1mol/L KCl absorption solution + 1 bottle of 1% H ₂ O ₂ -HNO ₃ Absorption solution + 3 bottles of 4% KMnO ₄ -10% H ₂ SO ₄ + 1 bottle of silica gel.
2. The test method according to claim 1, wherein the concentration of the KOH absorbing liquid is 1.3-1.7mol/L; preferably 1.5-1.6mol/L.
3. The test method according to _{claim 1 or 2, wherein the mass ratio of H2O2 and HNO3 in the H2O2 - HNO3} absorption liquid is 1:1;

   Preferably, the mass concentration of H ₂ O ₂ and HNO ₃ is 10-12%.
4. The test method according to claim 3, wherein the absorption bottle combination is: 1 bottle of 100ml 1mol/L KCl absorption solution + 2 bottles of 100ml 1.5mol/L KOH absorption solution + 1 bottle of 100ml 10% H ₂ O ₂ -HNO ₃ absorption solution + 3 bottles of 100ml 4% KMnO ₄ -10% H ₂ SO ₄ + 1 bottle of silica gel.
5. The test method according to claim 3, wherein the absorption bottle combination is: 3 bottles of 100ml 1.5mol/L KOH absorption solution + 1 bottle of 100ml 10% H ₂ O ₂ -HNO ₃ absorption solution + 3 bottles of 100ml 4 %KMnO ₄ -10%H ₂ SO ₄ +1 bottle of silica gel.
6. The test method according to claim 3, wherein the absorption bottle _combination is: 3 bottles of 100ml 1mol/LKCl absorption solution+1 bottle of 100ml 1% _H2O2 - _HNO3 absorption solution+3 bottles of 100ml 4%KMnO ₄ -10% H ₂ SO ₄ +1 bottle of silica gel.
7. A testing device for flue gas mercury in the whole process of fixed pollution sources, including an impact absorbing bottle box; the impact absorbing bottle box adopts the absorbing bottle combination described in any one of claims 1-6 based on different pollution control nodes.
8. The test device according to claim 7, wherein the test device further comprises a constant temperature sampling pipe, a constant temperature filter unit, a metering unit, power and control equipment;

   Each equipment unit is connected by pipeline;

   All sampling joints are made of stainless steel, preferably 304 stainless steel.
9. The testing device according to claim 8, wherein the temperature of the thermostatic sampling pipe is controlled at 125±5°C;

   The constant temperature sampling bong includes a sampling gun and a lining; when the flue gas temperature is higher than 200°C, the lining material is quartz or borosilicate glass; when the flue gas temperature is lower than 200°C, the lining material is polytetrafluoroethylene vinyl;

   The thermostatic sampling bong also includes a pitot tube and a sampling cigarette holder;

   The metering unit includes a thermocouple and a dry gas flow meter;

   The power and regulation equipment includes vacuum degree control equipment and sampling pump.
10. The testing device according to claim 8 or 9, wherein the temperature of the constant temperature filter unit is controlled at 125±5°C;

    The constant temperature filter unit is a filter or a quartz filter cartridge containing a quartz fiber filter membrane; when the concentration of particulate matter in the flue gas exceeds 100mg/ ^m3 , the constant temperature filter unit is a quartz filter cartridge, or at the front end of the filter Set up the cyclone separator.

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