High-precision low-temperature gaseous heavy metal generating device and method

Abstract

The application provides a high-precision low-temperature gaseous heavy metal generating device and method, and belongs to the field of pollutant control.The device comprises an atomization unit, a gasification unit and a dilution and cooling unit, wherein the atomization unit is connected with the gasification unit, the gasification unit is connected with the dilution and cooling unit, the dilution and cooling unit comprises a dilution assembly and a cooling assembly, the dilution assembly is arranged between the gasification unit and the cooling assembly, and the cooling assembly is used for heat exchange and cooling of the gaseous heavy metal sent by the dilution assembly.The dilution and cooling unit is additionally arranged behind the gasification unit, the gaseous heavy metal can be diluted, cooled and heat-exchanged according to the target temperature, the condensation of the heavy metal in the cooling process is effectively avoided, the temperature of the gaseous heavy metal is accurately controlled, the low-temperature heavy metal gas is generated, the dilution and cooling process can effectively reduce the concentration of the heavy metal, and therefore, the constant trace heavy metal gas is provided, and the device is suitable for various low-temperature environments and low-concentration environments.

Description

Technical Field

[0001] This invention belongs to the field of pollutant control, and more specifically, relates to a high-precision low-temperature gaseous heavy metal generating device and method. Background Technology

[0002] During coal combustion, trace heavy metals such as arsenic, selenium, lead, and mercury are gasified at high temperatures in the furnace and released into the flue gas as gaseous heavy metals. After undergoing a series of complex chemical and physical changes, they are released into the environment. Heavy metal pollution causes irreversible damage to human health and the ecological environment, and the cumulative and non-degradable nature of heavy metals further enhances their harm to human health. While there is considerable research on heavy metal emissions during coal combustion both domestically and internationally, in actual coal-fired power plants, heavy metal release varies significantly depending on the type of coal and combustion conditions, leading to unstable heavy metal concentrations in flue gas. This further results in an unclear pattern for enhanced heavy metal removal in coal-fired power plants, making targeted regulation and enhanced capture of heavy metals in flue gas quite difficult.

[0003] Traditional heavy metal generation systems are mainly used for gas source generation in online heavy metal detection systems, gas source generation for heavy metal adsorption platforms, and other necessary gaseous heavy metal experimental platform construction. Among existing devices, there are many reports on devices for generating mercury and divalent mercury standard gases. CN205210052U discloses a heavy metal standard gas generation device that uses two reagent supply systems to vaporize and then mix, simultaneously generating heavy metal ion standards and heavy metal element standard gases, improving equipment versatility. CN111735916A discloses a system and working method for generating elemental mercury and divalent mercury standard gases in the field of gaseous mercury monitoring and analysis technology, using a gradient evaporation chamber to generate mercury standard gases of different concentrations. CN111495282A discloses a device and method for generating gaseous ionic mercury, using a heater to vaporize a mercuric chloride solution. CN109490131A discloses a real-time testing system for gaseous heavy metal generation-adsorption experiments, using a balance to directly heat and volatilize solid standards, and determining the gaseous heavy metal concentration by the weight loss rate of the solid sample.

[0004] Currently, reports on heavy metal generation devices only describe how the process occurs. For low-temperature operating environments, such as the development of low-temperature denitrification catalysts to combat heavy metal poisoning and the development of low-temperature heavy metal adsorbents, as well as the low-temperature intake requirements for heavy metal gas source detection equipment, none of the published patents address subsequent anti-condensation and cooling measures. The low-temperature generation of gaseous heavy metals is thus neglected. Furthermore, for the direct sublimation method for solids, precisely and consistently feeding trace amounts of heavy metals at extremely low concentrations is a significant challenge. For the indirect vaporization method for solutions, currently reported inventions all employ mechanical atomization for heavy metal solution atomization. When the flow rate of the heavy metal liquid to be atomized is small, mechanical atomization is inefficient and unstable. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a high-precision low-temperature gaseous heavy metal generating device and method, which aims to solve the problem that existing heavy metal generating devices are only suitable for high-temperature environments and cannot achieve constant micro-level feeding of heavy metals.

[0006] To achieve the above objectives, according to one aspect of the present invention, a high-precision low-temperature gaseous heavy metal generating device is provided, the device comprising an atomization unit, a vaporization unit, and a dilution and cooling unit, wherein:

[0007] The atomizing unit is connected to the vaporization unit and is used to atomize the heavy metal solution to obtain heavy metal droplets, which are then sent into the vaporization unit by a carrier gas.

[0008] The vaporization unit is connected to the dilution and cooling unit and is used to vaporize heavy metal droplets to obtain gaseous heavy metals, which are then sent into the dilution and cooling unit by a carrier gas.

[0009] The dilution and cooling unit includes a dilution component and a cooling component. The dilution component is located between the vaporization unit and the cooling component and is used to provide dilution gas for the gaseous heavy metals to dilute and cool them. The cooling component is used to exchange heat and cool the gaseous heavy metals fed into the dilution component. During operation, if the original carrier gas volume of the gaseous heavy metals sent out by the vaporization unit is greater than or equal to the minimum carrier gas volume at the target temperature, no dilution and cooling is performed, and the gaseous heavy metals are directly sent into the cooling component for heat exchange and cooling to obtain high-precision low-temperature gaseous heavy metals. If the original carrier gas volume of the gaseous heavy metals sent out by the vaporization unit is less than the minimum carrier gas volume at the target temperature, the gaseous heavy metals are first diluted and cooled by the dilution component, and then sent into the cooling component for heat exchange and cooling to obtain gaseous heavy metals at the target temperature.

[0010] As a further preferred embodiment, the dilution and cooling unit contains 1 to 3 groups of dilution components, with each group of dilution components connected in sequence to perform multi-stage dilution of the gaseous heavy metal.

[0011] As a further preferred embodiment, when performing dilution and cooling, it is determined whether the ratio of the original carrier gas volume to the minimum carrier gas volume is greater than a preset value. If so, a first-stage dilution is performed; if not, a multi-stage dilution is performed. The preset value is 1:10 to 1:20.

[0012] As a further preferred embodiment, the dilution assembly includes a dilution gas source, a mixer, a first heat tracing device, a first flow meter, a first pressure gauge, and a first thermometer. The dilution gas source is connected to the mixer via a first gas supply pipe to provide dilution gas. The inlet of the mixer is connected to a vaporization unit or a previous-stage mixer, and its outlet is connected to a next-stage mixer or a cooling assembly to provide a space for mixing gaseous heavy metals with the dilution gas. The first heat tracing device is located outside the first gas supply pipe to control the temperature of the dilution gas. The first flow meter, the first pressure gauge, and the first thermometer are located on the first gas supply pipe to measure the flow rate, pressure, and temperature of the dilution gas, respectively.

[0013] As a further preferred embodiment, the cooling component includes a heat exchanger, a second flow meter, and cooling water. The heat exchanger is connected to the cooling water through the second flow meter to form a circulation loop, thereby utilizing the cooling water to exchange heat and cool the gaseous heavy metals.

[0014] As a further preferred embodiment, the gasification unit is connected to the dilution assembly via a second gas supply pipe. A second heat tracing device is provided on the outside of the second gas supply pipe for heat preservation of the gaseous heavy metals. At the same time, a third flow meter, a second pressure gauge, and a second thermometer are also provided on the second gas supply pipe for measuring the flow rate, pressure, and temperature of the gaseous heavy metals, respectively.

[0015] According to another aspect of the present invention, a method for generating high-precision low-temperature gaseous heavy metals using the above-mentioned high-precision low-temperature gaseous heavy metal generator is provided, the method specifically comprising:

[0016] S1 atomizes the heavy metal solution to obtain heavy metal droplets;

[0017] S2 carrier gas carries heavy metal droplets into the gasification unit and is gasified to obtain gaseous heavy metals.

[0018] S3 determines whether the original carrier gas volume of the gaseous heavy metal is less than the minimum carrier gas volume at the target temperature. If yes, proceed to step S4; otherwise, proceed to step S5.

[0019] S4. Diluting gas is introduced into the gaseous heavy metal to dilute and cool it down, and then the process proceeds to step S5.

[0020] S5 performs heat exchange to cool gaseous heavy metals in order to obtain gaseous heavy metals at the target temperature.

[0021] As a further preferred embodiment, when performing dilution and cooling, it is determined whether the ratio of the original carrier gas volume to the minimum carrier gas volume is greater than a preset value. If so, a first-stage dilution is performed; if not, a multi-stage dilution is performed. The preset value is 1:10 to 1:20.

[0022] In summary, the technical solutions conceived by this invention have the following beneficial effects compared with the prior art:

[0023] 1. This invention adds a dilution and cooling unit after the gasification unit, which can dilute and cool gaseous heavy metals according to the target temperature, thereby effectively avoiding the condensation of heavy metals during the cooling process and achieving precise control of the temperature of gaseous heavy metals. This enables the generation of low-temperature heavy metal gas, and the dilution and cooling process can effectively reduce the concentration of heavy metals, thereby providing a constant trace amount of heavy metal gas. It is suitable for various low-temperature and low-concentration environments and has a wide range of applications.

[0024] 2. In particular, by optimizing the number of dilution components, the present invention can achieve multi-stage dilution of gaseous heavy metals, effectively avoiding heat waste and reducing the heavy metal loss rate;

[0025] 3. At the same time, by comparing the difference between the original carrier gas volume and the minimum carrier gas volume, the present invention can determine the number of dilutions, thereby achieving precise control of the concentration of heavy metals generated. This greatly reduces the energy waste caused by heating excess carrier gas and avoids the problem of concentration deviation caused by insufficient carrier gas volume leading to the condensation of gaseous heavy metals in the pipeline. Thus, it can adapt to the generation of various heavy metals. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the high-precision low-temperature gaseous heavy metal generator provided in an embodiment of the present invention;

[0027] Figure 2 This is a schematic flowchart of the high-precision low-temperature gaseous heavy metal generation method provided in the embodiments of the present invention;

[0028] Figure 3 This is a graph showing the concentration and recovery rate of SeO2 in an embodiment of the present invention.

[0029] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0030] 1-Heavy metal solution, 2-Pump, 3-Atomization unit, 4-Carrier gas assembly, 5-Vaporization unit, 6-Second heat tracing device, 7-Third flow meter, 8-Second pressure gauge, 9-Second thermometer, 10-Mixer, 11-First thermometer, 12-First pressure gauge, 13-First flow meter, 14-First heat tracing device, 15-Dilution gas source, 16-Heat exchanger, 17-Second flow meter, 19-Frequency converter, 19-Cooling water, 20-High-precision low-temperature gaseous heavy metal. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0032] like Figure 1 As shown, according to one aspect of the present invention, a high-precision low-temperature gaseous heavy metal generating device is provided. The device includes an atomization unit 3, a vaporization unit 5, and a dilution and cooling unit, wherein:

[0033] One side of the atomizing unit 3 is connected to the heavy metal solution 1 via the pump 2, and the other side is connected to the vaporization unit 5. It is used to atomize the heavy metal solution to obtain heavy metal droplets and send them into the vaporization unit 5 via a carrier gas.

[0034] The vaporization unit 5 is connected to the dilution and cooling unit and is used to vaporize heavy metal droplets to obtain gaseous heavy metals, which are then sent into the dilution and cooling unit by a carrier gas.

[0035] The dilution and cooling unit includes a dilution component and a cooling component. The dilution component is located between the vaporization unit 5 and the cooling component, and is used to provide dilution gas to the gaseous heavy metals for dilution and cooling. The cooling component is used to exchange heat and cool the gaseous heavy metals fed into the dilution component. During operation, if the initial carrier gas volume Q0 of the gaseous heavy metals delivered by the vaporization unit 5 is greater than or equal to the minimum carrier gas volume Q at the target temperature... min If dilution and cooling are not performed, the gaseous heavy metal is directly fed into the cooling component for heat exchange and cooling to obtain high-precision low-temperature gaseous heavy metal; if the original carrier gas volume Q0 of the gaseous heavy metal sent out by the vaporization unit 5 is less than the minimum carrier gas volume Q at the target temperature. min The gaseous heavy metals are first diluted and cooled using a dilution component, and then sent to a cooling component for heat exchange and cooling to obtain gaseous heavy metals at the target temperature.

[0036] Furthermore, for small-capacity gaseous heavy metal generators (flow rate <1L / min), pump 2 is preferably a peristaltic pump, syringe pump, or other micro-pump, and the atomization unit is preferably an ultrasonic atomizer. The material for the heavy metal solution storage tank and atomization chamber of the ultrasonic atomizer is preferably polytetrafluoroethylene (PTFE). For large-capacity gaseous heavy metal generators, pump 2 is preferably a centrifugal pump, reciprocating pump, or mixed-flow pump, and the atomization unit is preferably a mechanical atomizer. Hydraulic sprayers, pneumatic sprayers, thermal sprayers, centrifugal sprayers, and electrostatic sprayers can also be used. The material for the atomization chamber in a mechanical atomizer is preferably PTFE. During operation, the heavy metal concentration and pump flow rate are determined based on the carrier gas volume and the required gaseous heavy metal concentration to ensure the stability of the generated gaseous heavy metal concentration.

[0037] Furthermore, the atomizing unit 3 is connected to the carrier gas assembly 4, which is used to introduce carrier gas to carry the atomized heavy metal droplets into the vaporization unit 5. The carrier gas assembly 4 consists of a gas source and a carrier gas pipeline. The carrier gas is preferably an inert gas, nitrogen. When the heavy metal is in a stable oxidation state, such as HgO, SeO2, As2O5, PbSO4, etc., an air pump can be used to directly pump air as the carrier gas source.

[0038] Furthermore, the gasification unit 5 can be composed of one or more components such as a tubular furnace, a heating cavity, and heating tubes. The heating temperature is adjustable from 0 to 1500℃. Different gasification temperatures are suitable for heavy metals with different sublimation temperatures, such as HgCl2 (300℃), SeO2 (350℃), As2O3 (600℃), and PbSO4 (1100℃). The heating power of the gasification unit 5 is determined by the heat absorption of the carrier gas, the latent heat of vaporization of the atomized droplets, and the heat absorption of water vapor and heavy metal gases. The tubular furnace, heating cavity, and heating tubes are preferably made of quartz lining and stainless steel outer shell to avoid physicochemical reactions between the heavy metal droplets and the metal materials during gasification, which would affect the heavy metal gas recovery rate. The heating method for the gasification unit 5 is preferably resistance wire heating, with the resistance wire installed in the stainless steel outer shell. Temperature control elements are used to control the temperature of the gasification unit 5, ensuring that different types of heavy metals are fully gasified.

[0039] Furthermore, the dilution and cooling unit contains 1 to 3 groups of dilution components, which are connected sequentially to perform multi-stage dilution of gaseous heavy metals. Each group of dilution components includes a dilution gas source 15, a mixer 10, a first heat tracing device 14, a first flow meter 13, a first pressure gauge 12, and a first thermometer 11. The dilution gas source 15 is connected to the mixer 10 through a first gas supply pipe to provide dilution gas. The inlet of the mixer 10 is connected to the vaporization unit 5 or the previous stage mixer 10, and its outlet is connected to the next stage mixer 10 or the cooling component to provide a place for mixing gaseous heavy metals with dilution gas. The first heat tracing device 14 is located outside the first gas supply pipe to control the temperature of the dilution gas. The first flow meter 13, the first pressure gauge 12, and the first thermometer 11 are located on the first gas supply pipe to measure the flow rate, pressure, and temperature of the dilution gas, respectively. The mixer 10 is preferably a static mixer lined with polytetrafluoroethylene, including but not limited to SK series static mixers, SV series static mixers, SX series static mixers, and SD series static mixers. The cooling component includes a heat exchanger 16, a second flow meter 17, cooling water 19, and a frequency converter 18. The heat exchanger 16 is connected to the cooling water 19 through the second flow meter 17 to form a circulation loop, and the frequency converter 18 is used to regulate the cooling water flow to achieve precise temperature control with low energy consumption. Then, the cooling water 19 is used to exchange heat and cool the gaseous heavy metals to obtain high-precision low-temperature heavy metal gas 20.

[0040] When performing dilution and cooling, compare the original carrier gas volume Q0 with the minimum carrier gas volume Q. min If the difference is greater than a preset value, then a first-stage dilution is performed, that is, dilution gas with a temperature of T1 and a flow rate of Q1 is introduced into mixer 10, where T1 < T0 and Q1 ≥ Q. min -Q0; If not, in order to avoid energy waste, multi-stage dilution is required, and the preset value is preferably 1:10 to 1:20.

[0041] When performing multi-stage dilution, ensure that the dilution ratio of each stage is less than a preset value, preferably 1:10 to 1:20. The specific dilution process is as follows: First, perform a primary dilution by introducing a dilution gas at temperature T1 and flow rate Q1 into mixer 10. The carrier gas volume of the gaseous heavy metals after the primary dilution is Q. mix1 The temperature is T mix1 In Q mix1 The minimum condensation temperature of heavy metals is determined as T based on their saturated vapor pressure. min2 The temperature is T2 (T2≥T) min2 The secondary carrier gas with a flow rate of Q2 is mixed with the gaseous heavy metals diluted in the first stage for dilution and cooling. The carrier gas volume of the gaseous heavy metals after the secondary dilution is Q. mix2 The temperature is T mix2 This process continues until the carrier gas volume Q of the gaseous heavy metal after N-level dilution is reached. mixN The lowest condensation temperature T of gaseous heavy metals, determined by the saturated vapor pressure of the gaseous heavy metals. minN Below the target temperature, the material is directly fed into the cooling component for heat exchange and cooling, thereby obtaining low-temperature gaseous heavy metals with a fixed concentration and a low heavy metal loss rate.

[0042] Furthermore, the vaporization unit 5 is connected to the dilution component through the second air supply pipe. The second air supply pipe is equipped with a second heat tracing device 6 on its outer side for heat preservation of gaseous heavy metals. At the same time, the second air supply pipe is also equipped with a third flow meter 7, a second pressure gauge 8, and a second thermometer 9 for measuring the flow rate, pressure, and temperature of gaseous heavy metals, respectively.

[0043] like Figure 2 As shown, according to another aspect of the present invention, a method for generating high-precision low-temperature gaseous heavy metals using the above-mentioned high-precision low-temperature gaseous heavy metal generator is provided, the method specifically comprising:

[0044] S1 pumps the heavy metal solution into the atomization unit for atomization to obtain heavy metal droplets;

[0045] S2 uses a carrier gas to carry heavy metal droplets into the gasification unit and gasify them to obtain gaseous heavy metals.

[0046] S3 determines whether the original carrier gas volume of the gaseous heavy metal is less than the minimum carrier gas volume at the target temperature. If yes, proceed to step S4; otherwise, proceed to step S5.

[0047] S4. Diluting gas is introduced into the gaseous heavy metal to dilute and cool it down, and then the process proceeds to step S5.

[0048] S5 performs heat exchange to cool gaseous heavy metals in order to obtain gaseous heavy metals at the target temperature.

[0049] When performing dilution and cooling, compare the original carrier gas volume Q0 with the minimum carrier gas volume Q. min If the difference is greater than a preset value, then a first-stage dilution is performed, that is, dilution gas with a temperature of T1 and a flow rate of Q1 is introduced into mixer 10, where T1 < T0 and Q1 ≥ Q. min -Q0; If not, in order to avoid energy waste, multi-stage dilution is required, and the preset value is preferably 1:10 to 1:20.

[0050] When performing multi-stage dilution, ensure that the dilution ratio of each stage is less than a preset value, preferably 1:10 to 1:20. The specific dilution process is as follows: First, perform a primary dilution by introducing a dilution gas at temperature T1 and flow rate Q1 into mixer 10. The carrier gas volume of the gaseous heavy metals after the primary dilution is Q. mix1 The temperature is T mix1 In Q mix1 The minimum condensation temperature of heavy metals is determined as T based on their saturated vapor pressure. min2 The temperature is T2 (T2≥T) min2 The secondary carrier gas with a flow rate of Q2 is mixed with the gaseous heavy metals diluted in the first stage for dilution and cooling. The carrier gas volume of the gaseous heavy metals after the secondary dilution is Q. mix2 The temperature is T mix2 This process continues until the carrier gas volume Q of the gaseous heavy metal after N-level dilution is reached. mixN The lowest condensation temperature T of gaseous heavy metals, determined by the saturated vapor pressure of the gaseous heavy metals. minN Below the target temperature, the material is directly fed into the cooling component for heat exchange and cooling, thereby obtaining low-temperature gaseous heavy metals with a fixed concentration and a low heavy metal loss rate.

[0051] This invention can accurately generate different types of low-temperature gaseous heavy metals with a recovery rate of approximately 90%. It effectively avoids the problems of condensation of gaseous heavy metals on the wall surface and low recovery rate at low temperatures, achieving high-precision generation of low-temperature gaseous heavy metals. This invention overcomes the shortcomings of existing technologies, which can only generate single heavy metals, only generate high-temperature gaseous heavy metals, and cannot generate trace amounts of gaseous heavy metals. It is applicable to the development of low-temperature heavy metal adsorbents, the study of low-temperature gaseous heavy metal conversion mechanisms, the development of low-temperature denitration catalysts to combat heavy metal poisoning, and the development of low-temperature heavy metal adsorbents. Its application scenarios have great market potential and provide a new approach to the generation of low-temperature gaseous heavy metals.

[0052] The technical solution provided by the present invention will be further described below with reference to specific embodiments.

[0053] Taking a high-precision, low-temperature gaseous heavy metal generator with a flue gas temperature of 120℃ as a specific example, with a flue gas volume requirement of 30,000 Nm³, this can be illustrated by... 3 In the flue gas duct, the required concentration of SeO2 added is 50–150 μg / Nm³. 3 .

[0054] According to the saturated vapor pressure of SeO2, the required concentration of SeO2 in flue gas is 150 μg / Nm³. 3 The minimum uncooled carrier gas quantity for SeO2 at 120℃ is 100 Nm³. 3 / h, that is, when the flue gas volume requirement is 30000 Nm³ 3 Under the condition of / h, the minimum carrier gas quantity of SeO2 is 100Nm³. 3 Only when heavy metals are generated and sent into the flue can they not condense.

[0055] Solid SeO2 is dissolved in water to prepare 10% H2SeO3, which is then introduced into an ultrasonic nebulizer at a rate of 15 ml / h to 45 ml / h, with nitrogen carrier gas at 1 Nm³. 3 / h carries the atomized droplets into a tubular furnace for high-temperature vaporization at a temperature of 400℃;

[0056] According to the saturated vapor pressure of SeO2, 1 Nm 3 Under the conditions of / h flue gas volume and steam flow rate generated by superimposed water evaporation, the lowest non-condensing temperature of SeO2 is 240℃;

[0057] Since two-stage dilution of SeO2 is sufficient to meet the requirements, but to ensure thorough mixing in both stages, the first-stage dilution temperature is set at 240℃, and the flow rate is selected as 1 / 5 of the maximum flow rate, which is 20 Nm³. 3 / h; Secondary dilution temperature is 120℃, flow rate is 100Nm³ / h. 3 / h. After secondary dilution, the flue gas enters the cooling unit to control the temperature at 120℃. Experimental results and SeO2 recovery rate are shown in [link to experimental data]. Figure 3The recovery rate of heavy metals in low-temperature SeO2 is about 90%.

[0058] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A high-precision low-temperature gaseous heavy metal generator, characterized in that, The device includes an atomizing unit (3), a vaporizing unit (5), and a dilution and cooling unit, wherein: The atomizing unit (3) is connected to the vaporizing unit (5) and is used to atomize the heavy metal solution to obtain heavy metal droplets and send them into the vaporizing unit (5) through a carrier gas. The vaporization unit (5) is connected to the dilution and cooling unit and is used to vaporize heavy metal droplets to obtain gaseous heavy metals and send them into the dilution and cooling unit through a carrier gas. The dilution and cooling unit includes a dilution component and a cooling component. The dilution component is located between the vaporization unit (5) and the cooling component and is used to provide dilution gas for the gaseous heavy metal to dilute and cool it. The cooling component is used to exchange heat and cool the gaseous heavy metal fed into the dilution component. During operation, if the original carrier gas volume of the gaseous heavy metal sent out by the vaporization unit (5) is greater than or equal to the minimum carrier gas volume of the target temperature, no dilution and cooling is performed, and the gaseous heavy metal is directly sent into the cooling component for heat exchange and cooling to obtain high-precision low-temperature gaseous heavy metal. If the original carrier gas volume of the gaseous heavy metal sent out by the vaporization unit (5) is less than the minimum carrier gas volume of the target temperature, the gaseous heavy metal is first diluted and cooled by the dilution component, and then sent into the cooling component for heat exchange and cooling to obtain gaseous heavy metal at the target temperature.

2. The high-precision low-temperature gaseous heavy metal generator as described in claim 1, characterized in that, The dilution and cooling unit contains 1 to 3 groups of dilution components, which are connected in sequence to perform multi-stage dilution of the gaseous heavy metal.

3. The high-precision low-temperature gaseous heavy metal generator as described in claim 1, characterized in that, When performing dilution and cooling, it is determined whether the ratio of the original carrier gas volume to the minimum carrier gas volume is greater than a preset value. If so, a first-stage dilution is performed; otherwise, a multi-stage dilution is performed. The preset value is 1:10 to 1:

20.

4. The high-precision low-temperature gaseous heavy metal generator as described in claim 1, characterized in that, The dilution assembly includes a dilution gas source (15), a mixer (10), a first heat tracing device (14), a first flow meter (13), a first pressure gauge (12), and a first thermometer (11). The dilution gas source (15) is connected to the mixer (10) through a first gas supply pipe to provide dilution gas. The inlet of the mixer (10) is connected to the vaporization unit (5) or the previous stage mixer (10), and its outlet is connected to the next stage mixer (10) or the cooling assembly to provide a place for mixing gaseous heavy metals with dilution gas. The first heat tracing device (14) is located outside the first gas supply pipe to control the temperature of the dilution gas. The first flow meter (13), the first pressure gauge (12), and the first thermometer (11) are located on the first gas supply pipe to measure the flow rate, pressure, and temperature of the dilution gas, respectively.

5. The high-precision low-temperature gaseous heavy metal generator as described in claim 1, characterized in that, The cooling component includes a heat exchanger (16), a second flow meter (17), and cooling water (19). The heat exchanger (16) is connected to the cooling water (19) through the second flow meter (17) to form a circulation loop, thereby using the cooling water (19) to exchange heat and cool the gaseous heavy metal.

6. The high-precision low-temperature gaseous heavy metal generator as described in claim 1, characterized in that, The vaporization unit (5) is connected to the dilution component through the second gas supply pipe. A second heat tracing device (6) is provided on the outside of the second gas supply pipe to keep the gaseous heavy metals warm. At the same time, a third flow meter (7), a second pressure gauge (8), and a second thermometer (9) are also provided on the second gas supply pipe to measure the flow rate, pressure, and temperature of the gaseous heavy metals, respectively.

7. A method for generating high-precision low-temperature gaseous heavy metals using the high-precision low-temperature gaseous heavy metal generator as described in any one of claims 1 to 6, characterized in that, The method is as follows: S1 atomizes the heavy metal solution to obtain heavy metal droplets; S2 carrier gas carries heavy metal droplets into the gasification unit and is gasified to obtain gaseous heavy metals. S3 determines whether the original carrier gas volume of the gaseous heavy metal is less than the minimum carrier gas volume at the target temperature. If yes, proceed to step S4; otherwise, proceed to step S5. S4. Diluting gas is introduced into the gaseous heavy metal to dilute and cool it down, and then the process proceeds to step S5. S5 performs heat exchange to cool gaseous heavy metals in order to obtain gaseous heavy metals at the target temperature.

8. The high-precision low-temperature gaseous heavy metal generation method as described in claim 7, characterized in that, When performing dilution and cooling, it is determined whether the ratio of the original carrier gas volume to the minimum carrier gas volume is greater than a preset value. If so, a first-stage dilution is performed; otherwise, a multi-stage dilution is performed. The preset value is 1:10 to 1:20.

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