CN109613181B - A standard generation system for trace gaseous mercury - Google Patents
A standard generation system for trace gaseous mercury Download PDFInfo
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- CN109613181B CN109613181B CN201811437076.5A CN201811437076A CN109613181B CN 109613181 B CN109613181 B CN 109613181B CN 201811437076 A CN201811437076 A CN 201811437076A CN 109613181 B CN109613181 B CN 109613181B
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- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 title claims abstract description 301
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Abstract
本公开涉及一种痕量气态汞标准发生系统，该系统包括用于产生汞蒸气的汞蒸气发生装置；所述汞蒸气发生装置包括用于储存汞和产生汞蒸气的汞储存容器、混合区、以及用于给所述汞储存容器和混合区加热保温的加热保温机构；所述汞储存容器顶部设置有用于蒸发出汞蒸气的顶部开口，所述混合区设置于所述顶部开口上方并与所述顶部开口连通，所述混合区设置有位于底部的载气入口和位于顶部的混合气出口。本公开的系统可以生成量值准确、浓度稳定的痕量汞标准气体。
The present disclosure relates to a standard generation system for trace gaseous mercury, which includes a mercury vapor generating device for generating mercury vapor; the mercury vapor generating device includes a mercury storage container for storing mercury and generating mercury vapor, a mixing zone, and a heating and heat preservation mechanism for heating and maintaining the mercury storage container and the mixing zone; the top of the mercury storage container is provided with a top opening for evaporating mercury vapor, and the mixing zone is arranged above the top opening and is connected with the The top opening is in communication, and the mixing zone is provided with a carrier gas inlet at the bottom and a mixed gas outlet at the top. The system of the present disclosure can generate trace mercury standard gas with accurate quantity and stable concentration.
Description
Technical Field
The disclosure relates to the field of gas monitoring, in particular to a trace gaseous mercury standard generation system.
Background
Mercury is the only liquid metal element at normal temperature, is easy to migrate in the environment, has strong biocompatibility and toxicity, is very easy to be absorbed by human bodies and organisms to further damage the central nervous system of the human bodies, and is the key and priority item in environmental monitoring. Since the industrial revolution, the content of mercury in the global environment has increased more than three times. The mercury in the atmosphere mainly exists in gaseous mercury (> 95%) due to special physical properties (high volatility and low melting point), and is easy to spread and diffuse in a short time, thus seriously affecting the ecological environment and human health. Meanwhile, mercury circulates in nature through phase state conversion, pollutes soil and water sources, and is more serious in harm. Therefore, accurate measurement of the content of gaseous mercury in the atmosphere plays an important role in evaluation of global environmental mercury pollution and environmental protection, and mercury in gas needs to be analyzed in many fields, such as flue gas, landfill, natural gas, coal combustion, scientific research (such as geochemical cycle of mercury), and the like.
China is the world with the most mercury discharge and the most serious mercury pollution, and the atmospheric mercury discharge accounts for 30% -40% of the world, so China faces great pressure in the aspects of mercury pollution control and international convention fulfillment.
At present, a monitoring instrument for gaseous mercury is generally a gas mercury analyzer, and in order to obtain accurate monitoring data, the gas mercury analyzer needs a standard gas of mercury for correction. Gas standard substances are generally filled with a target component at a certain concentration by a gas distribution device, such as a steel cylinder, according to a gravimetric method, and therefore, the steel cylinder generally has a higher filling pressure to ensure that the steel cylinder is filled with a larger amount of standard gas. However, the saturated vapor pressure of mercury is so low that it cannot be filled to a high pressure in the gas cylinder, and thus the conventional gas cylinder cannot provide a sufficient amount of gas. At the same time, the low saturation vapor pressure characteristic of mercury results in lower standard gas concentration values of mercury. In addition, mercury standard gas quantities are not readily stable in many metal cylinders because mercury can amalgam with many metals and is highly adsorptive. Therefore, the way of generating the mercury standard gas by adopting the conventional gas cylinder to fill the mercury standard gas is not mature, and the defects of inaccurate magnitude and unstable concentration of the mercury standard gas exist.
Disclosure of Invention
The purpose of this disclosure is in order to solve the inaccurate, the unstable shortcoming of concentration of the gaseous quantity of mercury standard gas, provides a trace gaseous mercury standard and takes place system.
To achieve the above objects, the present disclosure provides a trace gaseous mercury standards generating system comprising a mercury vapor generating device for generating mercury vapor;
the mercury vapor generating device comprises a mercury storage container for storing mercury and generating mercury vapor, a mixing area and a heating and heat-preserving mechanism for heating and preserving heat of the mercury storage container and the mixing area;
the top of the mercury storage container is provided with a top opening used for evaporating mercury vapor, the mixing area is arranged above the top opening and communicated with the top opening, and the mixing area is provided with a carrier gas inlet positioned at the bottom and a mixed gas outlet positioned at the top.
Optionally, the system further comprises a mercury vapor diluting device for diluting the mercury vapor from the mercury vapor generating device;
the mercury vapor diluting device is provided with a mercury vapor inlet and a mercury vapor outlet, and the mixed gas outlet of the mixing area is communicated with the mercury vapor inlet of the mercury vapor diluting device.
Optionally, the mercury vapor generation device further comprises a mixing sleeve body arranged outside the mercury storage container, and the mixing area is formed between the mixing sleeve body and the mercury storage container;
preferably, the top surface of the mixing zone is formed into a conical surface with the diameter gradually reduced from bottom to top, and the mixed gas outlet of the mixing zone is arranged at the conical tip of the conical surface;
preferably, a carrier gas channel for preheating carrier gas is further arranged in the mixing sleeve body, the carrier gas channel is provided with a gas inlet for introducing carrier gas and a gas outlet for flowing out carrier gas, and the gas outlet of the carrier gas channel is communicated with the carrier gas inlet of the mixing area;
preferably, the carrier gas passage is formed in a U shape;
preferably, the carrier gas channel is multiple;
preferably, the mixing sleeve body comprises an upper mixing sleeve body and a lower mixing sleeve body which are detachably connected, the bottom of the mercury storage container is in contact with the lower mixing sleeve body, the top opening of the mercury storage container extends into the upper mixing sleeve body, and the carrier gas channel is formed in the upper mixing sleeve body and/or is enclosed by the inner wall of the upper mixing sleeve body and the outer wall of the mercury storage container;
preferably, a sealing element is arranged at the joint of the upper mixing sleeve body and the lower mixing sleeve body, the sealing element comprises a sealing ring, and the sealing ring is made of fluororubber or polytetrafluoroethylene;
preferably, the mixed sheath body comprises a metal sheath body and a non-metal coating coated on the inner wall of the metal sheath body to prevent mercury from contacting the metal sheath body.
Optionally, the mercury storage container comprises a lower mercury storage section and an upper mercury evaporation section, the mercury storage section is communicated with the mercury evaporation section, and the top opening is arranged at the top of the mercury evaporation section;
preferably, the mercury storage section and the mercury evaporation section are both tubular and are vertically arranged along the axial direction, the inner diameter of the mercury storage section is larger than that of the mercury evaporation section, and the height of the mercury evaporation section is longer than that of the mercury storage section;
preferably, the material of the mercury storage container comprises one or more selected from glass, quartz, polytetrafluoroethylene, polyethylene, polypropylene, tetrafluoroethylene and hexafluoropropylene;
the heating and heat-preserving mechanism comprises a heat-preserving sleeve body surrounding the outer part of the mixing sleeve body, a heating element and a temperature detection element arranged in the heat-preserving sleeve body;
preferably, the heat-insulating sleeve body comprises an upper heat-insulating sleeve body and a lower heat-insulating sleeve body which are detachably connected, the top of the upper heat-insulating sleeve body is provided with a carrier gas inlet for introducing carrier gas and a gas outlet for flowing out mixed gas, the carrier gas inlet of the upper heat-insulating sleeve body is communicated with the gas inlet of the carrier gas channel, and the gas outlet of the upper heat-insulating sleeve body is communicated with the mixed gas outlet of the mixing area;
preferably, the heating element is a heating belt, a water bath heating device or a wind heating device which are arranged on the periphery of the mixed sleeve body;
preferably, a heat insulation material is filled between the heat insulation sleeve body and the mixed sleeve body;
preferably, the temperature detection piece is arranged in the mercury storage container or the mixing sleeve body;
preferably, the heat-insulating sleeve body is connected with the lower heat-insulating sleeve body through a screw;
preferably, the material of the heat insulating sleeve body comprises metal or polytetrafluoroethylene.
Optionally, the mercury vapor generation device further comprises a first carrier gas source and a first flow controller, the first carrier gas source being in communication with the carrier gas inlet of the mixing zone through the first flow controller;
preferably, the mercury vapor generating device further comprises a first pressure stabilizing device through which the first carrier gas source communicates with the first flow controller;
preferably, the mercury vapor generating device further comprises a first pressure sensor, and the first pressure stabilizing device is communicated with the first flow controller through the first pressure sensor;
preferably, the mercury vapor generating device further comprises a second pressure sensor in communication with the mixture outlet of the mixing zone.
Optionally, the mercury vapor dilution device comprises a second carrier gas source, a second flow controller, and a first line, the second carrier gas source being in communication with the first line through the second flow controller, the first line being in communication with the mixed gas outlet of the mixing zone;
preferably, the first pipeline is provided with a first air outlet and a second air outlet, the first air outlet is provided with a first valve, and the second air outlet is provided with a first back pressure valve;
preferably, the mercury vapor dilution device further comprises a second pressure stabilization device through which the second carrier gas source communicates with the second flow controller;
preferably, the mercury vapor diluting device further comprises a third pressure sensor, and the second pressure stabilizing device is in communication with the second flow controller via the third pressure sensor.
Optionally, the mercury vapor diluting device comprises a second pipeline, a fourth flow controller and a third carrier gas source, wherein the second pipeline is communicated with the first pipeline through the third flow controller, and the second pipeline is communicated with the third carrier gas source through the fourth flow controller;
preferably, the second pipeline is provided with a third air outlet and a fourth air outlet, the third air outlet is communicated with a second valve, and the fourth air outlet is communicated with a second back pressure valve;
preferably, the mercury vapor dilution device further comprises a third pressure stabilization device, the third carrier gas source being in communication with the fourth flow controller through the third pressure stabilization device;
preferably, the mercury vapor diluting device further comprises a fourth pressure sensor, and the third pressure stabilizing device is in communication with the fourth flow controller via the fourth pressure sensor.
Optionally, the mercury vapor diluting device further comprises a plurality of second pipelines, a fourth flow controller and a third carrier gas source, wherein the second pipelines are communicated with the first pipelines and the second pipelines through the third flow controller, and each second pipeline is communicated with the third carrier gas source through the fourth flow controller;
preferably, one or more of the second pipelines is/are provided with a third air outlet and a fourth air outlet, the third air outlet is communicated with a second valve, and the fourth air outlet is communicated with a second back pressure valve;
preferably, the mercury vapor dilution device further comprises a third pressure stabilization device, the third carrier gas source being in communication with the fourth flow controller through the third pressure stabilization device;
preferably, the mercury vapor diluting device further comprises a fourth pressure sensor, and the third pressure stabilizing device is in communication with the fourth flow controller via the fourth pressure sensor.
Optionally, the system further comprises a temperature control device for controlling the temperature of the mercury vapor diluting device and the mercury vapor generating device;
preferably, the temperature control device is an incubator.
Optionally, the material of the second flow controller, the third flow controller, the fourth flow controller, the second pressure stabilizing device, the third pressure stabilizing device, the second pressure sensor, the third pressure sensor, the fourth pressure sensor, the first line, the second line, the first back-pressure valve, the second back-pressure valve, the first valve and the second valve comprises polytetrafluoroethylene, preferably soluble polytetrafluoroethylene.
The disclosed trace mercury standard gas generation system generates mercury standard gas according to diffusion principle, specifically, mercury storage container in mercury vapor generation device generates mercury vapor and fully mixes with carrier gas to obtain initial mercury standard gas, and the initial mercury standard gas is obtained byThe temperature and the pressure of the mercury generating device are controlled, and initial mercury standard gases with different concentrations can be accurately obtained; further, the initial mercury standard gas enters the mercury vapor diluting device to realize multi-stage dilution of the mercury vapor, and trace mercury standard gas with wider concentration range can be further generated according to requirements. The trace mercury standard gas generation system can generate trace mercury standard gas with accurate value and stable concentration, and the concentration range can be 1ng/m3-250ug/m3。
In addition, the carrier gas of the system disclosed by the invention is mixed with the vapor from the top opening of the mercury storage container in the mixing area from bottom to top and further leaves from the mixed gas outlet of the mixing area from bottom to top, so that the carrier gas is effectively prevented from directly sweeping the surface of the mercury in the mercury storage container, the influence of the change of the flow rate and the flow rate of the carrier gas and the like and the change of the storage amount of the mercury in the mercury storage container on the evaporation of the mercury is reduced, and the concentration stability of the mercury standard gas is effectively improved.
Additional features and advantages of the disclosure will be set forth in the detailed description which follows.
Drawings
The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and together with the description serve to explain the disclosure without limiting the disclosure. In the drawings:
fig. 1 is a schematic structural view of one embodiment of a mercury vapor generation device provided by the present disclosure.
Figure 2 is a schematic diagram of the structure of one embodiment of a trace mercury standard gas generation system provided by the present disclosure.
Description of the reference numerals
10 mixing zone 11 first carrier gas source
15 first pressure stabilizing device 16 first pressure sensor 17 first flow controller
18 second pressure sensor 100 mercury vapor generating device
2 an upper insulating sleeve body 21 and a lower insulating sleeve body 22
212 second carrier gas source 213 third carrier gas source 219 first valve
220 second pressure stabilizer 221 third pressure sensor
223 third flow controller 224 first backpressure valve 225 second valve
226 second flow controller 227 third pressure sensor 228 fourth flow controller
229 third pressure stabilizer 230 second backpressure valve 234 temperature control device
300 first pipeline 301 second pipeline
5 mercury storage container 51 open-topped 52 mercury storage section
53 mercury evaporation section
6 temperature detecting piece
7 mixing jacket 71, upper mixing jacket 72 and lower mixing jacket
8 carrier gas channel
Detailed Description
The following detailed description of specific embodiments of the present disclosure is provided in connection with the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present disclosure, are given by way of illustration and explanation only, not limitation.
In the present disclosure, where not otherwise stated, the use of directional words such as "upper and lower" generally refer to the directions in which the trace mercury standard gas generation systems of the present disclosure are normally used.
As shown in fig. 1, the present disclosure provides a trace gaseous mercury standards generation system that includes a mercury vapor generation device 100 for generating mercury vapor;
the mercury vapor generation device 100 comprises a mercury storage container 5 for storing mercury and generating mercury vapor, a mixing area 10 and a heating and heat-preserving mechanism for heating and preserving heat of the mercury storage container 5 and the mixing area 10;
the top of the mercury storage container 5 is provided with a top opening 51 for evaporating mercury vapor, the mixing zone 10 is arranged above the top opening 51 and communicates with the top opening 51, and the mixing zone 10 is provided with a carrier gas inlet at the bottom and a mixed gas outlet at the top.
Mercury is in a liquid state at normal temperature, the characteristics of low saturated vapor pressure determine that mercury is easy to evaporate to generate mercury vapor, the generation rate of mercury vapor is influenced by factors such as temperature and the like, and is also related by factors such as carrier gas flow, flow rate, contact area of carrier gas and liquid mercury, so that the concentration of mercury vapor is changed along with the change of factors such as carrier gas flow, flow rate change and liquid mercury storage change, and the stability of the concentration of generated mercury standard gas is influenced. The method has the advantages that the distance between the mercury evaporation process and the mixing process of the mercury vapor and the carrier gas is increased from the aspect of ensuring the accuracy and stability of the generation quantity value of the mercury standard gas, the instability of the generation rate of the gaseous mercury caused by directly blowing the liquid mercury liquid surface by the carrier gas is reduced, and the concentration stability of the mercury standard gas is improved. The mercury storage container 5 stores mercury, mercury vapor is generated under the heating action of the heating and heat-preserving mechanism with the set temperature, mixed gas with certain concentration is generated after the mercury vapor and carrier gas are mixed in the mixing area 10, and the mixed gas is sent out from a mixed gas outlet at the top of the mixing area. The system disclosed by the invention can stably and accurately generate the trace mercury standard gas.
As depicted in fig. 2, the system may further include a mercury vapor dilution device 200 for diluting mercury vapor from the mercury vapor generation device 100 in accordance with the present disclosure;
the mercury vapor diluting device 200 may be provided with a mercury vapor inlet and a mercury vapor outlet, and the mixed gas outlet of the mixing zone 10 may be in communication with the mercury vapor inlet of the mercury vapor diluting device 200. The mercury vapor diluting device 200 further dilutes the mixed gas from the mercury generating device 100 to obtain a trace mercury standard gas with a wider concentration range.
As shown in fig. 1, the mercury vapor generating device 100 may further include a mixing sheath 7 disposed outside the mercury storage container 5, a mixing area 10 is formed between the mixing sheath 7 and the mercury storage container 5, and the carrier gas and the mercury vapor generated from the mercury storage container 5 are mixed in the mixing area to form a mixed gas with a constant concentration.
In an embodiment, as shown in fig. 1, the top surface of the mixing area 10 may be formed as a conical surface with a diameter gradually decreasing from bottom to top, and the mixed gas outlet of the mixing area 10 may be disposed at the conical tip of the conical surface, and the conical surface may reduce the flow dead angle of the mixed gas and prevent mercury from being adsorbed on the inner wall of the mixing sleeve 7, so as to ensure that the mixed gas smoothly passes through the mixed gas outlet, thereby facilitating quantitative generation of the trace mercury standard gas with accurate concentration and stable quantity.
In one embodiment, as shown in fig. 1, a carrier gas channel 8 for preheating the carrier gas may be further disposed in the mixing sleeve body 7, the carrier gas channel 8 is provided with a gas inlet for introducing the carrier gas and a gas outlet for flowing out the carrier gas, and the gas outlet of the carrier gas channel 8 is communicated with the carrier gas inlet of the mixing area 10. Further, the carrier gas channel 8 can be formed into a U shape, and the U-shaped carrier gas channel 8 can effectively transfer the heat of the mixing sleeve body 7 to the carrier gas to realize preheating of the carrier gas, so that the temperature difference between the carrier gas and mercury vapor can be effectively reduced, the temperature of the mixing area 10 and the mixed gas is kept constant, and the generation of the trace mercury standard gas with stable content is facilitated; more preferably, the carrier gas channel 8 may be a plurality of channels, and each carrier gas channel may independently introduce the carrier gas, so that the carrier gas is dispersed into the mixing zone 10 to more efficiently achieve carrier gas preheating and promote uniform mixing.
To facilitate maintenance and replacement of the mercury storage container 5 inside the mercury vapor generation device 100, as shown in fig. 1, the mixing jacket 7 may include an upper mixing jacket 71 and a lower mixing jacket 72 that are detachably connected, the bottom of the mercury storage container 5 may contact the lower mixing jacket 72, the top opening of the mercury storage container 5 extends into the upper mixing jacket 71, and the carrier gas channel 8 may be formed in the upper mixing jacket 71 and/or be enclosed by the inner wall of the upper mixing jacket 71 and the outer wall of the mercury storage container 5. The mixed sleeve body 7 can be made of a material with good heat conductivity, preferably, the mixed sleeve body 7 can include a metal sleeve body and a non-metal coating coated on the inner wall of the metal sleeve body to prevent mercury from contacting with the metal sleeve body, the non-metal coating can prevent mercury from contacting with the metal sleeve body to react, and the adsorption amount of mercury is significantly reduced, wherein the metal sleeve body and the non-metal coating can be materials conventionally used by those skilled in the art, and are not described herein again.
In order to avoid the escape of mercury vapor, a better closed environment is formed to accurately and stably generate the trace mercury standard gas, a sealing element is further arranged at the joint of the upper mixing sleeve body 71 and the lower mixing sleeve body 72, the sealing element can be a sealing ring, and the sealing ring can be made of a material which does not react with mercury vapor, such as fluororubber or polytetrafluoroethylene.
According to the present disclosure, as shown in fig. 1, the mercury storage container 5 may further include a mercury storage section 52 located below and a mercury evaporation section 53 located above, the mercury storage section 52 is communicated with the mercury evaporation section 53, and the top opening 51 is disposed at the top of the mercury evaporation section 53, and the mercury evaporation section 53 is disposed to further reduce the influence of the carrier gas on the mercury evaporation process in the mercury storage section 52, and improve the stability of the mercury vapor concentration.
In a preferred embodiment, as shown in fig. 1, the mercury storage section 52 and the mercury evaporation section 53 are both tubular and vertically arranged along the axial direction, the inner diameter of the mercury storage section 52 is larger than that of the mercury evaporation section 53, and the height of the mercury evaporation section 53 is longer than that of the mercury storage section 52. Wherein, the ratio of the inner diameter of the mercury storage section 52 to the inner diameter of the mercury evaporation section 53 can be (1.1-100) to 1, preferably (2-10): 1, the ratio of the height of the mercury evaporation section 53 to the height of the mercury storage section 52 may be (1.1-100):1, preferably (10-50): 1. the mercury vapor generated by heating the stored mercury in the mercury storage section 52 is diffused into the mixing area 10 through the elongated tubular mercury evaporation section 53 by diffusion, so that the instability of mercury volatilization caused by direct purging of the mercury liquid surface by the carrier gas can be effectively avoided, and the trace mercury standard gas with accurate concentration and stable quantity value can be quantitatively generated, wherein the length (or height) of the mercury evaporation section 53 can be more than 3 centimeters, the ratio of the length to the inner diameter can be more than 3:1, and the length of the inner diameter can be 0.001 meter to 0.02 meter, preferably 0.001 meter to 0.006 meter.
In order to avoid the amalgam reaction of mercury with the storage vessel 5 and reduce the amount of mercury adsorbed, the material of the mercury storage vessel 5 may preferably be non-metallic, for example comprising one or more selected from glass, quartz, polytetrafluoroethylene, polyethylene, polypropylene, tetrafluoroethylene and hexafluoropropylene.
The heating and heat-insulating mechanism can comprise a heat-insulating sleeve body 2 which is surrounded outside the mixed sleeve body 7, a heating element and a temperature detection element 6 which are arranged in the heat-insulating sleeve body 2. Preferably, the temperature detecting element 6 may be disposed in the mercury storage container 5 or in the mixing sleeve 7, and more preferably, the temperature detecting element 6 may be a temperature sensor disposed at the bottom of the mixing sleeve 7, for example, disposed in a hole formed at the bottom of the mixing sleeve 7, so as to prevent the temperature detecting element 6 from directly contacting and reacting with mercury or adsorbing, which affects the stability of the generated trace mercury standard gas.
The heating element of the present disclosure is well known to those skilled in the art, and may be, for example, a heating tape, a water bath heating device or a wind heating device disposed on the outer periphery of the mixed sheath body 7, for example, when the heating tape is a heating tape, the heating tape may be tightly wound on the outer wall of the mixed zone 10, in order to avoid being affected by the change of the ambient temperature, and further improve the heat insulation performance of the heat insulation sheath body 2, the heat insulation sheath body 2 and the mixed sheath body 7 may be filled with a heat insulation material, and the heat insulation material may include glass wool and/or foam plastic.
In order to facilitate the disassembly and replacement of the mercury vapor storage container and the mixing sleeve body 7 inside the thermal insulation sleeve body 2, the convenience and flexibility of the system use are improved, the thermal insulation sleeve body 2 can comprise an upper thermal insulation sleeve body 21 and a lower thermal insulation sleeve body 22 which are detachably connected, wherein preferably, the upper thermal insulation sleeve body 21 and the lower thermal insulation sleeve body 22 can be in screw connection, flange connection or clamping connection, and the material of the thermal insulation sleeve body 2 can comprise metal or polytetrafluoroethylene.
In one embodiment, the top of the upper thermal insulation sleeve body 21 is provided with a carrier gas inlet for introducing carrier gas and a gas outlet for flowing out mixed gas, the carrier gas inlet of the upper thermal insulation sleeve body 21 is communicated with the gas inlet of the carrier gas channel 8, and the gas outlet of the upper thermal insulation sleeve body 21 is communicated with the mixed gas outlet of the mixing area 10. Specifically, the carrier gas inlet of the upper insulating sleeve body 21 is communicated with the gas inlet of the carrier gas channel 8 through a pipeline, the gas outlet of the upper insulating sleeve body 21 is communicated with the mixed gas outlet of the mixing area 10 through a pipeline, so as to ensure that the carrier gas and the mercury standard gas can smoothly enter and exit the mercury vapor generating device 100, and the pipeline can be a hose made of polytetrafluoroethylene and the like.
As shown in FIG. 2, to accurately control the carrier gas flow, the mercury vapor generation device 100 may further include a first carrier gas source 11 and a first flow controlThe first carrier gas source 11 may be in communication with the carrier gas inlet of the mixing zone 10 via a first flow controller 17, as shown in block 17. The first carrier gas source 11 may be a gas cylinder, and the carrier gas supplied by the first carrier gas source may be N2One or more of Ar and He, the carrier gas flow may be controlled by adjusting the opening of the cylinder valve by observing an indication on a first flow controller, which may be a mass flow controller.
Further, in order to control the pressure of the carrier gas sent by the first carrier gas source 11 and make the carrier gas have a stable pressure, the mercury vapor generating device 100 may further include a first pressure stabilizing device 15, and the first carrier gas source 11 is communicated with the first flow controller 17 through the first pressure stabilizing device 15, which is well known to those skilled in the art, for example, the first pressure stabilizing device 15 may be a high-precision pressure regulating valve or the like.
In one embodiment, the mercury vapor generating device 100 may further include a first pressure sensor 16, the first pressure stabilizing device 15 is communicated with the first flow controller 17 through the first pressure sensor 16, the first pressure sensor 16 is used for monitoring the stability of the pressure provided by the pressure stabilizing device 15, so as to have an indirect feedback regulation effect on the pressure stabilizing device 15, and the first pressure sensor 16 may be one of a gauge pressure sensor, a differential pressure sensor and an absolute pressure sensor; more preferably, the mercury vapor generation device 100 may further include a second pressure sensor 18, the second pressure sensor 18 is communicated with the mixed gas outlet of the mixing area 10, the temperature and the pressure in the mercury vapor generation device 100 jointly affect the concentration of the trace mercury standard gas, the second pressure sensor 18 is used for monitoring the stability of the pressure in the mercury vapor generation device 100, and the second pressure sensor 18 may be the same as or different from the first pressure sensor 16, and the details of the disclosure are omitted.
In accordance with the present disclosure, as shown in fig. 2, the mercury vapor dilution device 200 can include a second carrier gas source 212, a second flow controller 226, and a first line 300, the second carrier gas source 212 being in communication with the first line 300 through the second flow controller 226, the first line 300 being in communication with the mixture outlet of the mixing zone 10. The carrier gas provided by the second carrier gas source 212 may be the same as or different from the carrier gas provided by the first carrier gas source 11, which is not described in detail in this disclosure, and the second flow controller 226 may be a mass flow controller. The mixed gas from mixing zone 10 may be further diluted by the carrier gas from second carrier gas source 212.
In a preferred embodiment, the first line 300 may be provided with a first gas outlet for sending out mercury standard gas, on which a first valve 219 may be provided, and a second gas outlet for controlling the stabilization of the gas pressure in the first line, on which a first back pressure valve 224 is provided. Wherein, the first valve 219 may be an on-off valve, and if the concentration of the trace mercury standard gas meets the requirement, the on-off valve is opened to discharge the trace mercury standard gas; the first backpressure valve 224 may be to stabilize the pressure of the first line 300 in the event that the first line 300 is not pressure stable.
In one embodiment, the mercury vapor diluting device 200 may further include a second pressure stabilizing device 220, the second carrier gas source 212 is in communication with the second flow controller 226 through the second pressure stabilizing device 220, and the second pressure stabilizing device 220 may be the same as or different from the first pressure stabilizing device 15, and the details of the disclosure are not repeated.
In one embodiment, the mercury vapor diluting device 200 may further include a third pressure sensor 221, the second pressure stabilizing device 220 is in communication with the second flow controller 226 through the third pressure sensor 221, and the third pressure sensor 221 may be the same as or different from the first pressure sensor 16, and the details of the disclosure are not repeated.
The mercury vapor generated by the mercury vapor generation device 100 may be subjected to one or more mercury dilution treatments as needed to obtain a trace mercury standard gas with a wider concentration range. Specifically, as shown in fig. 2, the mercury vapor diluting device 200 may include a second pipeline 301, a fourth flow controller 228, and a third carrier gas source 213, where the second pipeline 301 is communicated with the first pipeline through the third flow controller 223, the second pipeline 301 is communicated with the third carrier gas source 213 through the fourth flow controller 228, where the third flow controller 223 and the fourth flow controller 228 may be mass flow controllers, and the carrier gas provided by the third carrier gas source 213 may be the same as or different from the carrier gas provided by the third carrier gas source 213, which is not described in detail in this disclosure.
Preferably, the second pipeline 301 is provided with a third air outlet and a fourth air outlet, the third air outlet is communicated with a second valve 225, the fourth air outlet is communicated with a second backpressure valve 230, wherein the second valve 225 may be an on-off valve, and the functions of the second valve and the second backpressure valve are similar to those of the first valve and the first backpressure valve, which is not repeated in this disclosure.
In one embodiment, the mercury vapor dilution device 200 further includes a third pressure stabilization device 229, and the third carrier gas source 213 is in communication with the fourth flow controller 228 via the third pressure stabilization device 229, wherein the third pressure stabilization device 229 may be the same as or different from the first pressure stabilization device 15, and the details of the disclosure are not repeated.
In one embodiment, the mercury vapor diluting device 200 further includes a fourth pressure sensor 227, the third pressure stabilizer 229 is in communication with the fourth flow controller 228 via the fourth pressure sensor 227, and the fourth pressure sensor 227 may be the same as or different from the first pressure sensor, and the details of the disclosure are not repeated.
Further to accurately obtain a lower concentration of the trace mercury standard gas, according to the present disclosure, as shown in fig. 2, the mercury vapor diluting device 200 may include a plurality of second lines 301, fourth flow controllers 228, and third carrier gas sources 213, and each of the second lines 301 and 300 and the second lines 301 and 301 may be communicated through the third flow controllers 223, and each of the second lines 301 is communicated through the fourth flow controllers 228 to the third carrier gas sources 213.
In one embodiment, one or more second lines 301 are provided with a third air outlet in communication with a second valve 225 and a fourth air outlet in communication with a second backpressure valve 230.
In one embodiment, the mercury vapor diluting device 200 further comprises a third pressure stabilizing device 229, the third carrier gas source 213 is in communication with the fourth flow controller 228 via the third pressure stabilizing device 229, and the pressure stabilizing device 229 may be the same as or different from the first pressure stabilizing device 15, and the details of the disclosure are not repeated.
In one embodiment, the mercury vapor diluting device 200 further includes a fourth pressure sensor 227, the third pressure stabilizing device 229 is in communication with the fourth flow controller 228 via the fourth pressure sensor 227, and the fourth pressure sensor 227 may be the same as or different from the first pressure sensor 16, and the details of the disclosure are not repeated.
According to the present disclosure, as shown in fig. 2, the system may further include a temperature control device 234 for controlling the temperature of the mercury vapor diluting device 200 and the mercury vapor generating device 100; preferably, the temperature control device 234 can be an incubator as known to those skilled in the art to reduce the influence of temperature changes of the external environment on the temperature of the system of the present disclosure, and one or more components of the system of the present disclosure can be disposed in the temperature control device as required by those skilled in the art.
To avoid affecting the trace mercury standard gas concentration, stability of the quantity due to mercury adsorption and loss of mercury by the amalgam reaction, the materials of the second flow controller 220, the third flow controller 223, the fourth flow controller 228, the second pressure stabilization device 220, the third pressure stabilization device 229, the second pressure sensor 18, the third pressure sensor 221, the fourth pressure sensor 227, the first line 300, the second line 301, the first back-pressure valve 224, the second back-pressure valve 230, the first valve 219, and the second valve 225 may comprise polytetrafluoroethylene, preferably soluble polytetrafluoroethylene. Further preferably, the material (e.g., pipeline) of the direct contact part of the flow controller, the pressure stabilizer, the pressure sensor, the back pressure valve and the valve with the mercury vapor may be polytetrafluoroethylene, preferably soluble polytetrafluoroethylene.
The preferred embodiments of the present disclosure are described in detail with reference to the accompanying drawings, however, the present disclosure is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present disclosure within the technical idea of the present disclosure, and these simple modifications all belong to the protection scope of the present disclosure.
It should be noted that, in the foregoing embodiments, various features described in the above embodiments may be combined in any suitable manner, and in order to avoid unnecessary repetition, various combinations that are possible in the present disclosure are not described again.
In addition, any combination of various embodiments of the present disclosure may be made, and the same should be considered as the disclosure of the present disclosure, as long as it does not depart from the spirit of the present disclosure.
Claims (33)
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