Fixed pollution source gaseous and particulate heavy metal collection and detection device and detection method

Abstract

A device and method for collecting and detecting gaseous and particulate heavy metals from stationary pollution sources. There is a problem of adsorption of gaseous heavy metals by fly ash separated by a filter membrane in the prior art. The distortion of basic data will surely affect the correct understanding of the migration, transformation and control laws of heavy metals. The composition of the present invention includes: a convex sampling nozzle (1), which is connected to a cyclone separator (3) above and a coarse ash bin (2) below. One end of a P-shaped connecting elbow (4) is inserted into the top of the cyclone separator, and the other end of the P-shaped connecting elbow is connected to a quartz filter cartridge (6). A filter cover (5) is installed inside the quartz filter cartridge. The quartz filter cartridge is connected to a rotary vane vacuum pump (7) through a pipeline. The rotary vane vacuum pump is connected to a mass flowmeter (8) through a pipeline, and the mass flowmeter is connected to a gas-liquid contact ball (10) through a pipeline. The gas-liquid contact ball is installed at the lower part of an impact bottle (9). The present invention is used for a device for collecting and detecting gaseous and particulate heavy metals from stationary pollution sources.

Description

Technical Field

[0001] The present invention relates to the technical field of environmental protection monitoring and analysis of fixed pollution sources, and particularly relates to a device and a method for collecting and detecting gaseous and particulate heavy metals in fixed pollution sources. Background Art

[0002] Heavy metals such as arsenic and mercury pose a serious threat to ecological environments such as water, atmosphere, and soil, affecting the ecological environment and human health. A large amount of research work has been carried out on the emission, migration, transformation, sedimentation, and control of relevant heavy metals and their compounds. Arsenic and mercury are highly volatile toxic heavy metal elements widely present in coal. A large amount of coal combustion in China is one of the main anthropogenic emission sources of arsenic and mercury. Therefore, it is crucial to control the emission of heavy metals during coal combustion. The national standard GB20475 Classification of the Content of Harmful Elements in Coal strictly classifies arsenic and mercury, and GB7562 Coal for Pulverized Coal-Fired Boilers also restricts the use of arsenic and mercury contents. During the coal combustion process, heavy metals such as arsenic and mercury are released in high-temperature areas and are easily adsorbed on fly ash particles as the flue gas cools down. The occurrence states include gaseous and particulate states. Since heavy metals are easily adsorbed on fly ash, it is difficult to avoid the adsorption of a large amount of gaseous heavy metals on fly ash during the sample collection process, resulting in the concentration of gaseous heavy metals monitored in fixed pollution sources being lower than that of particulate heavy metals.

[0003] Currently, there is no environmental protection monitoring system at home and abroad that can effectively avoid the adsorption of heavy metals by fly ash. Some documents and patents have proposed methods for filtering and isolating fly ash, but there are problems with the adsorption of gaseous heavy metals by the fly ash isolated by the filter membrane in related devices. The distortion of basic data will inevitably affect the correct understanding of the migration, transformation, and control laws of heavy metals. Therefore, it is urgent to develop a monitoring system for the concentrations of gaseous and particulate heavy metals in fixed pollution sources to solve the above problems. Based on the above analysis, in the existing technical field, there is no solution that can solve the problem of distorted monitoring data of gaseous and particulate heavy metals in fixed pollution sources. Summary of the Invention

[0004] The purpose of the present invention is to provide a device and a method for collecting and detecting gaseous and particulate heavy metals in fixed pollution sources. This structure and method can efficiently separate gaseous and particulate heavy metal samples in fixed pollution sources to ensure the accuracy and reliability of the monitoring data of gaseous and particulate heavy metals in fixed pollution sources.

[0005] The above purpose is achieved by the following technical solutions:

[0006] A device for collecting and detecting gaseous and particulate heavy metals from stationary pollution sources, comprising: a convex sampling nozzle, the upper part of the convex sampling nozzle is connected to a cyclone separator, and the lower part is connected to a coarse ash bin. One end of a P-shaped connecting elbow is inserted into the top of the cyclone separator, and the other end of the P-shaped connecting elbow is connected to a quartz filter cartridge. A filter cover is installed inside the quartz filter cartridge. The quartz filter cartridge is connected to a rotary vane vacuum pump through a pipeline. The rotary vane vacuum pump is connected to a mass flow meter through a pipeline. The mass flow meter is connected to a gas-liquid contact ball through a pipeline. The gas-liquid contact ball is installed at the lower part of an impact bottle.

[0007] For the device for collecting and detecting gaseous and particulate heavy metals from stationary pollution sources, an exhaust port is installed above the impact bottle. The outer part of the convex sampling nozzle is conical, and its inner part is a cylindrical channel structure. The P-shaped connecting elbow is a semi-circular curved streamline structure. The outer surface of the gas-liquid contact ball has a group of round holes and is evenly arranged.

[0008] For the device for collecting and detecting gaseous and particulate heavy metals from stationary pollution sources, the convex sampling nozzle, the cyclone separator, the P-shaped connecting elbow, and the quartz filter cartridge are fixed inside the source flue wall.

[0009] A device for collecting and detecting gaseous and particulate heavy metals from stationary pollution sources and a detection method, the method comprising the following steps:

[0010] First, the flue gas in the cyclone separator enters at a constant speed. The lower end of the cyclone separator is connected to a coarse ash bin for receiving the cut large-particle fly ash. That is, the large-particle fly ash rotates and sinks into the coarse ash bin under the action of centrifugal force and gravity. One end of the P-shaped connecting elbow is inserted into the cyclone separator, and the other end is connected to a quartz filter cartridge for filtering small-particle fly ash. The convex sampling nozzle is selected according to the flue gas flow rate and the matching inner diameter size specification to ensure isokinetic sampling. According to the calculation result of the convex sampling nozzle, the convex sampling nozzle, the cyclone separator, the P-shaped connecting elbow, the quartz filter cartridge, and the filter cover are fixed inside the source flue wall to ensure the representativeness of the large-particle fly ash and small-particle fly ash samples. The impact bottle is filled with a specified concentration of hydrogen peroxide and nitric acid solution to react with and absorb the gaseous heavy metals in the flue gas;

[0011] The formula for selecting the inner diameter D of the convex sampling nozzle is:

[0012]

[0013] Among them, Q S is the sample collection flow rate, V S is the sample collection flow rate;

[0014]

[0015] Among them, K P is the correction coefficient of the velocity measuring pitot tube, Pa , P d are the dynamic pressure and static pressure of the flue gas respectively, and M S is the molecular weight of the flue gas from the stationary source, and T S is the temperature of the flue gas from the stationary source, and B a is the atmospheric pressure;

[0016] The convex sampling nozzle faces the flue gas flow direction vertically. The flue gas from the stationary source enters the cyclone separator at the same speed. Large particulate fly ash in the flue gas rotates and sinks under the action of centrifugal force and gravity and enters the coarse ash bin. The mass of the large particulate fly ash sample collected in the coarse ash bin is M1, which is used for the analysis of heavy metal content in fly ash;

[0017] The flue gas from which large particulate fly ash has been removed enters the P-type connecting elbow and then enters the quartz filter cartridge to filter small particulate fly ash. The mass of the sample used for the analysis of heavy metal content is M2, which is used for the analysis of heavy metal content in fly ash.

[0018] Beneficial effects:

[0019] 1. The present invention is a device and its detection method for collecting and detecting gaseous and particulate heavy metals from stationary pollution sources. This structure and method can efficiently separate gaseous and particulate heavy metal samples from stationary pollution sources, ensuring the accuracy and reliability of the monitoring data of gaseous and particulate heavy metals from stationary pollution sources. Specifically, two-stage fly ash filtration is adopted to avoid the adsorption of a large amount of gaseous heavy metals on fly ash, resulting in distorted monitoring data, and improve the representativeness of monitoring data of heavy metals in different forms, with the advantages of high accuracy, etc.

[0020] The present invention has the function of two-stage fly ash filtration, which can efficiently separate gaseous and particulate heavy metal samples from stationary pollution sources, avoid the adsorption of a large amount of gaseous heavy metals on fly ash, resulting in distorted monitoring data, and improve the representativeness and reliability of monitoring data of heavy metals in different forms from stationary pollution sources. It is a stable monitoring system for gaseous and particulate heavy metals from stationary pollution sources, with the advantage of high accuracy.

[0021] The P-type connecting elbow of the present invention adopts a semi-circular curved streamline structure, aiming to prevent the coagulation or fragmentation of small fly ash particles, connect the quartz filter cartridge at the other end, and filter small particulate fly ash through the built-in filter cover as a sample for heavy metal content analysis. The structure is simple and practical.

[0022] Multiple round holes are provided on the gas-liquid contact ball of the present invention and are evenly arranged. This structure can increase the mass transfer between the flue gas and the solution, ensure the full reaction of heavy metals in the flue gas with the absorbent solution, and arrange the vane vacuum pump forward to extract samples from the stationary source to prevent the liquid from flowing back and being sucked back due to negative pressure at the stationary source.

[0023] The thin wall of the air inlet of the convex sampling nozzle adopted by the present invention can avoid the disturbance of the flue gas and ensure the sampling representativeness. Description of the drawings

[0024] Appendix Figure 1 is the structural schematic diagram of the present invention.

[0025] Appendix Figure 2 is the appendix Figure 1 structural schematic diagram of the convex sampling nozzle.

[0026] Wherein: 1, convex sampling nozzle; 2, coarse ash bin; 3, cyclone separator; 4, P-shaped connecting elbow; 5, filter cover; 6, quartz filter cartridge; 7, rotary vane vacuum pump; 8, mass flowmeter; 9, impinger; 10, gas-liquid contact ball; 11, exhaust port; 12, flue wall. Detailed implementation manners

[0027] Embodiment 1:

[0028] A device for collecting and detecting gaseous and particulate heavy metals from stationary pollution sources, which comprises: a convex sampling nozzle 1, the upper part of the convex sampling nozzle is connected to a cyclone separator 3, and the lower part is connected to a coarse ash bin 2. One end of a P-shaped connecting elbow 4 is inserted into the top of the cyclone separator. The other end of the P-shaped connecting elbow is connected to a quartz filter cartridge 6. A filter cover 5 is installed inside the quartz filter cartridge. The quartz filter cartridge is connected to a rotary vane vacuum pump 7 through a pipeline. The rotary vane vacuum pump is connected to a mass flowmeter 8 through a pipeline. The mass flowmeter is connected to a gas-liquid contact ball 10 through a pipeline. The gas-liquid contact ball is installed at the lower part of an impinger 9.

[0029] Embodiment 2:

[0030] For the device for collecting and detecting gaseous and particulate heavy metals from stationary pollution sources according to Embodiment 1, an exhaust port 11 is installed above the impinger. The outer part of the convex sampling nozzle is conical, and its inner part is a cylindrical channel structure. The P-shaped connecting elbow is a semi-circular curved streamline structure. The outer surface of the gas-liquid contact ball has a group of round holes and is evenly arranged.

[0031] Embodiment 3:

[0032] For the device for collecting and detecting gaseous and particulate heavy metals from stationary pollution sources according to Embodiment 2, the convex sampling nozzle, the cyclone separator, the P-shaped connecting elbow, and the quartz filter cartridge are fixed inside a source flue wall 12.

[0033] Embodiment 4:

[0034] For the detection method of the device for collecting and detecting gaseous and particulate heavy metals from stationary pollution sources according to Embodiments 1-3, the method comprises the following steps:

[0035] First, the flue gas enters the cyclone separator at a constant speed. The lower end of the cyclone separator is connected to a coarse ash bin that receives the large particulate fly ash cut off. That is, the large particulate fly ash rotates and sinks under the action of centrifugal force and gravity into the coarse ash bin. One end of the P-shaped connecting elbow is inserted into the cyclone separator, and the other end is connected to a quartz filter cartridge for filtering small particulate fly ash. The convex sampling nozzle, according to the flue gas flow rate and supporting inner diameter size specifications, ensures isokinetic sampling. It is selected based on the calculation results of the convex sampling nozzle. The convex sampling nozzle, cyclone separator, P-shaped connecting elbow, quartz filter cartridge, and filter hood are fixed inside the wall of the fixed source flue to ensure that the samples of large particulate fly ash and small particulate fly ash are representative. The impinger contains a specified concentration of hydrogen peroxide and nitric acid solution to react with and absorb the gaseous heavy metals in the flue gas;

[0036] The formula for selecting the inner diameter D of the convex sampling nozzle is:

[0037]

[0038] Among them, Q S is the sample collection flow rate, and V S is the sample collection flow rate;

[0039]

[0040] Among them, K P is the correction coefficient of the velocity measuring pitot tube, and P a , P d are the dynamic pressure and static pressure of the flue gas respectively. M S is the molecular weight of the fixed source flue gas, T S is the temperature of the fixed source flue gas, and B a is the atmospheric pressure;

[0041] The convex sampling nozzle vertically faces the flue gas flow direction. The fixed source flue gas enters the cyclone separator at a constant speed. The large particulate fly ash in the flue gas rotates and sinks under the action of centrifugal force and gravity into the coarse ash bin. The mass of the large particulate fly ash sample collected in the coarse ash bin is M1, which is used for the analysis of the heavy metal content in the fly ash;

[0042] The flue gas from which the large particulate fly ash has been removed enters the P-shaped connecting elbow and then enters the quartz filter cartridge to filter the small particulate fly ash. The mass of the sample used for the analysis of the heavy metal content is M2, which is used for the analysis of the heavy metal content in the fly ash;

[0043] The mass flowmeter corrects the sampled volume to the standard state V b ;

[0044] The content of particulate heavy metals is calculated by the following formula:

[0045]

[0046] Among them, H1 is the heavy metal content in the large particulate fly ash, and H2 is the heavy metal content in the small particulate fly ash;

[0047] The gaseous heavy metal content is calculated by the following formula:

[0048]

[0049] where V is the volume of the absorbing solution in the impinger bottle, y is the heavy metal content of the absorbing solution; V b is the sampling volume at standard conditions.

Claims

1. A method for collecting and detecting gaseous and particulate heavy metals from stationary pollution sources, characterized in that: The method includes the following steps: First, the flue gas enters the cyclone separator at a constant speed. The lower end of the cyclone separator is connected to a coarse ash bin for collecting the cut large-particle fly ash. That is, the large-particle fly ash rotates and sinks under the action of centrifugal force and gravity into the coarse ash bin. One end of the P-shaped connecting elbow is inserted into the cyclone separator, and the other end is connected to a quartz filter cartridge for filtering small-particle fly ash. The convex sampling nozzle is selected according to the flue gas flow rate and the matching inner diameter size specification to ensure isokinetic sampling. According to the calculation result of the convex sampling nozzle, the convex sampling nozzle, cyclone separator, P-shaped connecting elbow, quartz filter cartridge and filter hood are fixed inside the wall of the fixed-source flue duct to ensure the representativeness of the large-particle fly ash and small-particle fly ash samples. The impinger contains a specified concentration of hydrogen peroxide and nitric acid solution to react with and absorb the gaseous heavy metals in the flue gas; The formula for selecting the inner diameter D of the convex sampling nozzle is: Among them, Q S is the sample collection flow rate, and V S is the sample collection flow velocity; Among them, K P is the correction coefficient of the velocity measuring pitot tube, P a , P d are respectively the dynamic pressure and static pressure of the flue gas, M S is the molecular weight of the flue gas from the stationary source, T S is the temperature of the flue gas from the stationary source, B a is the atmospheric pressure; The convex sampling nozzle vertically faces the flue gas flow direction. The fixed-source flue gas enters the cyclone separator at a constant speed. The large-particle fly ash in the flue gas rotates and sinks under the action of centrifugal force and gravity into the coarse ash bin. The mass of the large-particle fly ash sample collected in the coarse ash bin is M1, which is used for analyzing the heavy metal content in the fly ash; The flue gas from which the large-particle fly ash has been removed enters the P-shaped connecting elbow and then enters the quartz filter cartridge to filter the small-particle fly ash. The mass of the sample used for analyzing the heavy metal content is M2, which is used for analyzing the heavy metal content in the fly ash.

2. The method for collecting and detecting gaseous and particulate heavy metals from stationary pollution sources according to claim 1, characterized in that: The upper part of the convex sampling nozzle is connected to the cyclone separator, and its lower part is connected to the coarse ash bin. One end of the P-shaped connecting elbow is inserted into the top of the cyclone separator, and the other end of the P-shaped connecting elbow is connected to the quartz filter cartridge. A filter hood is installed inside the quartz filter cartridge. The quartz filter cartridge is connected to a rotary vane vacuum pump through a pipeline. The rotary vane vacuum pump is connected to a mass flow meter through a pipeline. The mass flow meter is connected to a gas-liquid contact ball through a pipeline. The gas-liquid contact ball is installed at the lower part of the impinger.

3. The method for collecting and detecting gaseous and particulate heavy metals from stationary pollution sources according to claim 2, wherein: An exhaust port is installed above the impinger. The outer part of the convex sampling nozzle is conical, and its inner part is a cylindrical channel structure. The P-shaped connecting elbow is a semi-circular curved streamline structure. The outer surface of the gas-liquid contact ball has a group of round holes and is evenly arranged.

4. The fixed pollution source gaseous and particulate heavy metal collection and detection device according to claim 2 or 3, characterized in that: The convex sampling nozzle, the cyclone separator, the P-shaped connecting elbow, and the quartz filter cartridge are fixed inside the wall of the source flue duct.

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