CN110879159B - High-temperature high-humidity aerosol sampling device and sampling method - Google Patents
High-temperature high-humidity aerosol sampling device and sampling method Download PDFInfo
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- CN110879159B CN110879159B CN201911378029.2A CN201911378029A CN110879159B CN 110879159 B CN110879159 B CN 110879159B CN 201911378029 A CN201911378029 A CN 201911378029A CN 110879159 B CN110879159 B CN 110879159B
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- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/02—Devices for withdrawing samples
- G01N1/10—Devices for withdrawing samples in the liquid or fluent state
Abstract
The invention discloses a high-temperature high-humidity aerosol sampling device and a sampling method, wherein the aerosol sampling device is designed based on a birotor Roots pump, a rotating shaft and a rotor of the aerosol sampling device are both hollow, heat transfer working media are filled at two sides in the rotor, and the heat exchange is carried out between the working media and a low-temperature cooling medium flowing through the center of the rotor through the rotating shaft through the phase change of the working media, so that the contact between the acquired aerosol and the low-temperature cooling medium is avoided, and the effect of efficiently cooling the rotor on the premise of isolating aerosol sample gas is achieved; before sampling, the aerosol sampling device is calibrated, so that accurate quantitative sampling and temperature control can be realized, and the sampling requirement of high-temperature and high-humidity aerosol is met. The invention has simple structure, easy disassembly and assembly and maintenance, flexible and adjustable sampling amount and high sampling precision.
Description
Technical Field
The invention relates to sampling and measurement of particulate matters discharged by boilers, thermal power plants and automobiles, in particular to an aerosol quantitative sampling device which can not damage the appearance and distribution of particulate matters in aerosol under a high-temperature and high-humidity state.
Background
With the increasing demand of thermal energy, a large amount of particles are generated by combustion of combustors such as automobile internal combustion engines, boilers, thermal power plant units and the like during operation, and serious pollution is caused to the atmospheric environment. Because the particulate matter produced by combustion is wrapped by the high-temperature and high-humidity exhaust gas, the temperature of the exhaust gas (belonging to high-temperature and high-humidity aerosol) is reduced, the water in the exhaust gas is condensed to cause the particulate matter to generate coagulation, sedimentation or adhesion loss, and great influence is generated on the rear-end measurement. At present, the means for solving the problem is mainly to directly extract high-temperature high-humidity exhaust gas, dilute the high-temperature high-humidity sample gas by using a large amount of dry pure gas (according to the requirement of GB18352.6-2016, the first-level dilution ratio is 10), and rapidly reduce the humidity and temperature of the sample gas, thereby avoiding the size change and quantity loss of particles caused by water vapor condensation, and simultaneously, the stable operation of the rear-end measuring equipment (mostly optical equipment) is ensured by the reduction of the temperature and the humidity.
The difficulty of the sampler in the dilution process is the quantitative sampling of high-temperature and high-humidity gas. At present, there are two kinds of samplers, one is a more traditional and widely used throttling type sampler, for example, the DI 1000 jet diluter of Dekati corporation in finland, and the basic principle is to utilize the flow characteristic of a reducing nozzle, that is, under a certain back pressure, the air flow below the sound velocity is limited by the nozzle, so as to achieve the purpose of quantitative sampling. The sampler can only sample at a fixed dilution ratio, is greatly influenced by exhaust pressure fluctuation, and is only suitable for an environment with stable exhaust (downstream of exhaust). Another type of sampler is a constant volume pump type sampler in recent years, for example, a 379020A rotary disc diluter of TSI company in the united states, the basic principle of which is to use a disc type rotary heat pump to directly perform constant heat sampling on exhaust gas, so that more flexible sampling flow control can be realized, but the maximum temperature of the exhaust gas is limited below 150 ℃, and the exhaust gas at higher temperature can damage the instrument.
The birotor roots pump is used for conveying gas in a conventional environment (the temperature is not more than 50 ℃), and for high-temperature gas, in order to avoid high-temperature expansion and seizure of a rotor in rotation, the rotor is cooled by spraying water into a stator cavity or using circulating oil to cool the rotor (wet cooling) or external circulating air (dry cooling); however, both of these cooling methods bring the coolant into direct contact with the gas being transported (collected), destroying the composition of the gas, and particularly damaging effects may be caused when collecting aerosols containing particulate matter. At present, a sampler for quantitatively collecting high-temperature and high-humidity aerosol by adopting rotary machinery is not seen.
Disclosure of Invention
The invention aims to provide a high-temperature high-humidity aerosol sampling device and a sampling method.
In order to achieve the purpose, the invention adopts the following technical scheme:
a rotary aerosol quantitative sampling device comprises a hollow stator, a sample inlet and a sample outlet which are arranged on the hollow stator, and a plurality of hollow rotors which are arranged in the hollow stator and used for moving high-temperature (or high-humidity) aerosol from the sample inlet to the sample outlet through the residual space in the hollow stator; a cavity and a heat transfer working medium capable of generating phase change are arranged in the hollow rotor, the heat transfer working medium is located on the outer side of the cavity, and a low-temperature cooling medium is arranged in the cavity.
Preferably, the hollow rotor is provided with a liquid inlet hole, and a degassing plug for controlling the injection and discharge of the heat transfer working medium is arranged in the liquid inlet hole.
Preferably, the degassing plug comprises a lifting cylinder, a connecting pipe connected with an opening of the lifting cylinder, and a flow guide hole and a closing head which are arranged on the closing end surface of the lifting cylinder, wherein the flow guide hole and the closing head are matched with a step surface in the liquid inlet hole.
Preferably, the hollow rotor is provided with a hollow rotating shaft penetrating through the center of the hollow rotor, the low-temperature cooling medium flows axially inside the hollow rotating shaft, and the heat transfer working medium is disposed in a plurality of mutually independent spaces (between the outer wall surface of the hollow rotating shaft and the inner wall surface of the hollow rotor) partitioned by the hollow rotating shaft inside the hollow rotor.
Preferably, the number of the hollow rotors is two, and the hollow rotors are matched with each other in synchronous rotation by adopting a rotor profile of the roots pump and are respectively matched with the inner wall of the hollow stator.
Preferably, the sampling device further comprises a sensor for detecting the temperature and/or pressure of the gas at the sample inlet, so as to obtain the state of the sample gas.
The method for quantitatively sampling the aerosol by using the rotary aerosol quantitative sampling device comprises the following steps:
connecting the sample inlet to an exhaust passage of a certain burner; the hollow rotor arranged in the hollow stator is rotated, so that high-temperature aerosol with a certain volume in the exhaust passage is moved to the sample outlet from the sample inlet through the residual space in the hollow stator, and the sampling of the exhaust passage is realized; in sampling, the heat transfer working medium is utilized to carry out phase change on a heat absorption interface and a heat release interface, wherein the heat absorption interface of the heat transfer working medium is a part or all of the wall surface of the hollow rotor, which is in contact with the aerosol, the heat release interface of the heat transfer working medium is the wall surface of the cavity, and meanwhile, the rotating speed of the hollow rotor and the flow of the low-temperature cooling medium introduced into the cavity are adjusted according to the gas pressure and the gas temperature collected from the sample inlet, so that the sampling amount is kept to be constant in the sampling process (namely the flow of the sampled gas is kept to be constant).
Preferably, the number of the hollow rotors is two, the two hollow rotors are respectively driven by one hollow rotating shaft, the two hollow rotors synchronously rotate through the rotor profile of the double-rotor roots pump, and in sampling, the low-temperature cooling medium continuously flows through the centers of the corresponding hollow rotors through the hollow rotating shafts.
Preferably, before sampling, a heat transfer working medium (generally, a working medium with good evaporability and large latent heat of vaporization is selected so as to absorb/release heat as efficiently as possible during phase change) is determined according to the sampling working condition, and the heat transfer working medium (liquid phase change working medium) with a certain volume is injected after the hollow rotor is vacuumized (the vacuumization can reduce the air pressure outside the cavity and is more beneficial to the evaporation of the working medium).
Preferably, the vacuumizing is completed through the degassing plug, the degassing plug is placed into the liquid inlet hole through rotation when the vacuum heat-transfer device is used, the cavity is vacuumized through the degassing plug, and heat-transfer working media are injected.
Preferably, before the vacuum pumping, the degassing plug is incompletely pressed into (for example, screwed into) the liquid inlet hole on the hollow rotor by using a screw thread, a channel of the liquid inlet hole is kept smooth, a vacuum pump is used for pumping gas (for example, air) in a corresponding space (outside the cavity) of the hollow rotor through the liquid inlet hole, the vacuum pump is closed when the required vacuum degree is reached, and a quantitative heat transfer working medium (liquid) is injected; then pressing the degassing plug into the bottom end of the liquid inlet hole until the degassing plug presses the end face of the sealing gasket positioned at the bottom of the liquid inlet hole, so that the liquid inlet hole is closed; and finally, removing external pipelines (such as a vacuum pump and the like) connected to the degassing plug, and finishing the vacuumizing of the hollow rotor and the injection of the heat transfer working medium.
Preferably, the sampling device needs to be calibrated before use, and the flow of the sampling device comprises sampling amount (sampling gas flow) and low-temperature cooling medium flow; by changing the rotation speed (rotation speed) of the hollow rotor, the sampling amount can be changed, theoretically, the rotation speed of the hollow rotor is in direct proportion to the sampling rate, but due to the existence of gaps in the sampling device (for example, based on the matching relationship of the rotor and the stator of the roots pump), the leakage amount of the gaps can be different due to different rotation speeds and gas pressures, and therefore the sampling amount of the sampling device with different rotation speeds and gas pressures needs to be calibrated. Meanwhile, the volume change (generally referred to as thermal expansion) of the sampling device at different rotating speeds for gases with different sampling flow rates and temperatures needs to be tested, so as to calibrate the flow rate of the required low-temperature cooling medium.
Preferably, a rotating speed-pressure-flow table is obtained according to calibration, and the rotating speed of the rotor is controlled, so that the sampling amount is controlled; in addition, the flow of the low-temperature cooling medium can be controlled according to a temperature-gas flow-cooling medium flow table.
Preferably, pure dry gas for removing particles can be introduced before and after sampling each time, and the inner wall surface of the sampling device is purged and cleaned.
The invention has the following beneficial effects:
the sampling device of the invention takes a rotary machine (such as a roots pump) capable of conveying fluid as a body, adopts the hollow rotor, and utilizes the phase change of the working medium in the hollow rotor to exchange heat with the low-temperature cooling medium, thereby avoiding the contact of the collected aerosol and the low-temperature cooling medium, achieving the effect of efficiently cooling the rotor on the premise of isolating the aerosol sample gas, preventing the rotor from being clamped with a stator or other rotors due to high-temperature expansion, and ensuring that the sampling device can stably collect the high-temperature and high-humidity aerosol. The sampling device has simple and compact structure and high sampling precision.
Furthermore, the invention can flexibly control the sampling amount and accurately control the flow of the low-temperature cooling medium according to the calibration result table, and can avoid the problem that the sample gas near the surface of the rotor is condensed because of the over-low temperature of the rotor caused by the over-high cooling medium.
Drawings
FIG. 1 is a schematic structural diagram of a sampling apparatus according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of the operation of the sampling device shown in FIG. 1;
fig. 3 is a schematic structural view of a rotating body, in which: (a) is appearance, (b) is cross-sectional view;
fig. 4 is a schematic structural view of the degassing plug, wherein: (a) The state is vacuum pumping and liquid feeding (phase change material), and (b) is a sealed state;
in the figure: 1. the vacuum degassing device comprises a sample inlet, 2. A stator, 3. A rotating body, 4. A sample outlet, 5. A rotating shaft cavity, 6. A stator cavity, 7. A rotating body cavity, 8. A liquid inlet hole, 9. A temperature and pressure sensor, 10. A rotating shaft, 11. A first sealing washer, 12. A separating compression ring, 13. A three-way valve, 14. A liquid inlet degassing pipe, 15. A vacuum degassing plug, 16. A second sealing washer, 17. A rotor outer surface, 18. A reverse wire, 19. A first positive wire, 20. A second positive wire and 21. A rotor inner surface.
Detailed Description
The invention is described in detail below with reference to the figures and examples. The examples are given solely for the purpose of illustration and are not intended to limit the scope of the invention.
Referring to fig. 1, 2 and 3, the invention designs a high-temperature and high-humidity aerosol sampling device based on a birotor roots pump, and the sampling device comprises a rotating body 3, a stator 2 and a rotating shaft 10, wherein the three parts are made of aluminum alloy.
The stator 2 is a pump shell of the roots pump, two rotating bodies 3 with involute profiles are arranged in the stator 2, the interiors of the rotating bodies 3 (namely rotors) are hollow, a rotating shaft 10 penetrates through the rotating bodies 3 along the centers of the rotating bodies 3 and is fixed on non-matching surfaces on two sides of the rotating bodies 3, a cavity (namely a rotating shaft cavity 5) with a circular section is formed in the rotating shaft 10 along the axial direction, and two mutually independent rotating body cavities 7 are formed in the rotating bodies 3 in the space on two sides of the rotating shaft cavity 5 in a symmetrical distribution manner; the wall surface (specifically located on the non-matching surface) of each rotating body cavity 7 is provided with a liquid inlet hole 8 (4 in the sampling device, which is also used as a deaeration hole), and a cavity inside the rotor (namely the rotating body cavities 7 on two sides of the rotating shaft cavity 5) is filled with a liquid phase-change material (heat transfer working medium).
A sample inlet 1 and a sample outlet 4 which are used for communicating the interior of the stator 2 with an external sampling pipeline are arranged on the stator 2, and a temperature pressure sensor 9 is arranged on the wall surface of the sampling pipeline at the position of the sample inlet 1. There are gaps between the stator 2 and the rotors and between the two rotors which are in co-operation, the dimensions a and B of which should be as small as possible (e.g. 0.1-0.2 mm) to ensure a relatively good seal within the sampling device.
The rotating shafts 10 on the two rotating bodies 3 can drive the two rotating bodies 3 to synchronously rotate (the rotating directions are the same) under the drive of an external motor, so that the two rotating bodies 3 periodically move along the surface (the matching end surface) where the molded line is located and the inner wall of the stator cavity 2, namely, the end surfaces of the two rotating bodies 3 are always kept close to each other when the two rotating bodies 3 synchronously rotate, thereby always keeping a plurality of relatively sealed cavities (namely, the stator cavity 6) in the stator 2, and along with the rotation of the rotating bodies 3, the plurality of relatively sealed cavities move along with the rotation of the rotating bodies, thereby conveying gas from the sample inlet 1 to the sample outlet 4 and completing quantitative sampling. Because the inside of the rotating shaft 10 is hollow, when the sampling device runs (particularly when high-temperature and high-humidity aerosol is collected), low-temperature cooling medium (such as water or air) can flow through the inside of the rotating shaft 10 (namely the rotating shaft cavity 5), and heat exchange is carried out between the phase change of the heat transfer working medium in the rotating body cavity 7 and the low-temperature cooling medium flowing through the center of the rotor through the rotating shaft 10, so that the aerosol in the stator cavity 6 is prevented from contacting with the low-temperature cooling medium, and the effect of efficiently cooling the rotating body 3 on the premise of isolating the aerosol sample gas is achieved.
Before the sampling device is assembled, a vacuum degassing plug 15 (installed in the liquid inlet hole 8) shown in fig. 4 is needed to be used for vacuumizing and injecting liquid (filling heat transfer working medium) into the rotary body cavity 7. The liquid inlet hole 8 is a three-section stepped through hole, the aperture of two sections (an expansion section and a thread section) close to one side of the outer surface 17 (the outer wall of the non-matching surface of the rotating body 3) of the rotor is larger, the vacuum degassing plug 15 is convenient to install and embed, and the aperture of one section (a contraction section) close to one side of the inner surface 21 (the inner wall of the non-matching surface of the rotating body 3) of the rotor is smaller, so that the opening and closing of the liquid inlet hole 8 are convenient to control. The main body of the vacuum degassing plug 15 is a cylinder, a plurality of axial flow guide holes are formed in the closed end face of the cylinder, so that liquid can flow in and gas can flow out conveniently, the part of the closed end face surrounded by the axial flow guide holes is opposite to the contraction section of the liquid inlet hole 8 (a seal head is formed), and therefore the liquid inlet hole 8 (the contraction section of the liquid inlet hole) can be closed by the closed end face and a second sealing washer 16 located at the joint of the contraction section and the thread section. The lateral wall processing of barrel has external screw thread (second positive silk 20), can cooperate with the 8 screw thread sections in feed liquor hole to can control the closed end face of barrel and compress tightly (seal the opening that the rotatory body chamber one end was kept away from to 8 shrink sections in feed liquor hole) or separate with second seal ring 16 (open the opening that the rotatory body chamber one end was kept away from to 8 shrink sections in feed liquor hole). The opening terminal surface of barrel is processed there is the joint pipe fitting, and the joint pipe fitting has internal thread (anti-screw 18) and external screw thread (first positive screw 19), and the joint pipe fitting internal diameter slightly is lighter than the barrel, and the joint pipe fitting passes through bottom ring support to be fixed on the barrel opening, and the joint pipe fitting can inlay to the biggest liquid inlet hole 8 in aperture's expansion section when the closed end face of barrel compresses tightly second seal ring 16, and the joint pipe fitting top is located below the rotor surface 17.
The vacuum pumping and liquid injection operation comprises the following specific steps:
(1) The upper part of the vacuum degassing plug 15 (a first positive wire 19 of a joint pipe fitting) is screwed into the lower end of the liquid inlet degassing pipe 14, the outer side of the liquid inlet degassing pipe 14 is sleeved with a separation pressing ring 12 (which can be positioned by an annular support body at the bottom of the joint pipe fitting), and the upper end of the liquid inlet degassing pipe 14 is provided with a three-way valve 13 which is screwed to ensure that the liquid inlet degassing pipe 14 is tightly contacted with a first sealing washer 11 (which is positioned between the annular support body and the liquid inlet degassing pipe) without leaking gas.
(2) The vacuum degassing plug 15 connected with the three-way valve 13 is screwed into the liquid inlet hole 8, so that a certain gap is formed between the bottom (the closed end face) of the vacuum degassing plug 15 and the second sealing washer 16, degassing and liquid inlet are smooth, and the second sealing washer 16 is made of polytetrafluoroethylene due to higher operating environment temperature, which is shown in fig. 4a.
(3) One end (air exhaust end) of the three-way valve 13 is connected with a vacuum pump, one end (liquid inlet end) is connected with an injector filled with heat transfer working medium (liquid), the volume of the liquid in the injector needs to be determined by advance, the filling amount is generally controlled to be 55-65% of the volume of any rotating body cavity 7, the sampling device can collect gas with higher temperature and humidity, and the corresponding heat transfer working medium is selected according to different sample gas temperatures, for example, when the sample gas temperature exceeds 200 ℃, liquid naphthalene can be selected as the heat transfer working medium and injected into the rotating body cavity 7. After the preparation is finished, the air suction end is opened, the vacuum pump is used for vacuumizing until the air pressure in the rotary body cavity 7 is reduced to 5-10 multiplied by 10 -2 After Pa, the air exhaust end is closed, the liquid inlet end is opened, and at the moment, the heat transfer working medium in the injector is automatically injected into the rotating body cavity 7 under the difference of internal pressure and external pressure. After the injection is finished, the liquid inlet end is quickly closed, and the vacuum degassing plug 15 is downwards rotated to the bottomThe part is in close contact with the second sealing washer 16 to ensure that it is airtight.
(4) And (3) pressing down the separation compression ring 12 to ensure that the vacuum degassing plug 15 cannot rotate, and simultaneously upwards screwing the liquid inlet degassing pipe 14 until the liquid inlet degassing pipe 14 and a vacuum pump connected with the liquid inlet degassing pipe are removed, and then removing the separation compression ring 12. Referring to fig. 4b, the vacuum degassing plug 15 is completely screwed into the liquid inlet hole 8, so that the vacuum degassing plug 15 does not protrude out of the wall surface of the rotating body 3, thereby avoiding interference of the rotation of the rotor and the gas flow in the stator cavity 6 and ensuring the stability of the sample gas state.
(5) If the vacuum-pumping or the working medium replacement is needed at the later stage, a reverse-thread nut needs to be screwed into the opening of the vacuum degassing plug 15 (specifically, the reverse thread 18 in the connector pipe fitting) and is continuously screwed, so that the vacuum degassing plug 15 can be screwed out.
After the sampling device is assembled with reference to fig. 1, the sampling device can be connected to the exhaust passage of the burner to be sampled by using an external sampling pipe. Referring to fig. 2, when the sampling device is used, due to the gravity, the thickness distribution of the liquid film on the wall surface of the rotating body cavity 7 is not uniform (the position close to the ground is thicker, and the position far from the ground is thinner), so that the sampling device must be placed perpendicular to the ground (the center of the rotating shaft is parallel to the ground), the sample inlet 1 is far from the ground, the sample outlet 4 is close to the ground, and the sample inlet 1 and the sample outlet 4 cannot be inverted up and down or placed horizontally (the center of the rotating shaft is perpendicular to the ground when placed horizontally). When the placement direction of the device (refer to the positions of the sample inlet 1 and the sample outlet 4 in fig. 2) is fixed, the rotation direction of the rotation shaft 10 is also fixed (the rotors are all counterclockwise in fig. 2).
As shown in fig. 2, taking sampling of high-temperature and high-humidity aerosol as an example, the working flow of the sampling device is as follows: according to the roots pump principle, the two rotors 3 are driven synchronously by the respective rotating shafts 10 to form a moving cavity (stator cavity 6) in the stator, and the sample gas (as high-temperature and high-humidity aerosol sample gas) entering from the sample inlet 1 is driven to move quantitatively to the sample outlet 4. In the process of the rotation of the rotor, liquid naphthalene in the rotating cavity 7 is thrown to the wall far away from the rotating shaft cavity 5 due to centrifugal force to form a uniform liquid film, the temperature of the wall is easily and rapidly increased due to sample gas (namely, the wall can be called as a hot end wall), the liquid naphthalene rapidly absorbs heat of the wall through boiling evaporation and forms gas naphthalene to be distributed in the rotating cavity 7, low temperature medium can continuously flow in the rotating shaft cavity 5, so that the temperature near the wall of the rotating shaft cavity 5 is low, the gas naphthalene close to the wall can be condensed into liquid and release heat, and the liquid naphthalene flows to the hot end wall under the action of the rotation of the rotating body 3 (centrifugal force), and a heat exchange cycle is formed. By repeating this operation, the temperature of the wall surface of the rotor chamber 7 is not excessively high, and the gaps between the rotors 3 and the stator 2 are kept stable, so that high sampling accuracy can be maintained.
The thermodynamic experiment result shows that the sampling device can aim at the temperature of 150-400 ℃ and the absolute humidity of 10-16 g/m 3 The aerosol can be stably sampled (the temperature of a cooling medium is 0-5 ℃), and the sampling device has small temperature difference between gas at a sample inlet and a sample outlet and strong adaptability to the pressure change of the sample inlet, so that the high-precision quantitative sampling can be performed on high-temperature and high-humidity exhaust gas of an automobile internal combustion engine, a thermal power plant unit and a boiler.
It should be noted that the flow rate (i.e., the sampling amount) and the thermal state change of the sample gas may cause the volume of the metal parts of the sampling device to change, thereby causing the gaps between the rotor and between the rotor and the stator to change. Therefore, the sampling device needs to carry out flow calibration before use, and the flow calibration comprises measurement calibration of sampling amount and control calibration of cooling medium flow in the rotating shaft cavity. The measurement of the sampling quantity and the control of the cooling medium flow are related, and the specific relation is as follows: in the heat exchange process of the low-temperature cooling medium flowing through the hollow rotating shaft 10, the flow of the low-temperature cooling medium is mainly controlled by considering the flow and the temperature of the high-temperature sample gas; the high-temperature sample gas flow is greatly influenced by the rotating speed of the rotating shaft 10 and the pressure of the sample gas entering the stator (the two factors, namely the rotating speed and the pressure, influence the gap leakage), so that three measurable data, namely the rotating speed of the rotating shaft (namely the rotating speed of the rotor), the pressure of the sample gas and the temperature of the sample gas (the pressure and the temperature of the sample gas can be acquired by the temperature and pressure sensor 9 at the sample inlet 1), need to be considered when the cooling medium flow is controlled; wherein the rotating shaft speed and the sample gas pressure can be combined into a secondary table for querying or calculating (e.g. interpolating) the sample gas flow, which also solves the control problem of the sampling amount (i.e. can be used for setting the rotating shaft speed at a given sampling amount).
Therefore, before the sampling device is used, gases with different temperatures and different pressures need to be introduced into the sample inlet of the sampling device, and the sampling amount, the temperature and the flow of the cooling medium of the sampling device are calibrated under different working conditions (including the rotating speed of the rotating shaft), so that a table is filled. By flow calibration, the flow control of the cooling medium is realized by using a table which is nested with a secondary table and can be used for inquiry or interpolation calculation, thereby ensuring the sampling precision and the normal operation of the device.
It should be noted that, the sampling device may be introduced with pure dry gas (e.g., dry high-purity nitrogen gas, dry and clean gas after gas generator or air filtration) without particles before and after each use to purge and clean the walls of the sampling device that are in contact with the gas, so as to remove particles, liquid drops, etc. that may adhere to the walls, prevent corrosion of the interior of the sampling device, and reduce adverse effects of residual contaminants on subsequent sampling.
Compared with the prior art, the invention has the following characteristics:
(1) The high-temperature and high-humidity aerosol sampling device has a simple and compact structure, is convenient to clean, disassemble and maintain, is portable and can be installed and used in a narrow position (for example, a vehicle-mounted position);
(2) The sampling device has a self-cooling function, effectively reduces the temperature of the rotor, can ensure the normal operation of a rotating member in a high-temperature environment, and is suitable for the collection work of high-temperature gas;
(3) The self-cooling medium of the sampling device is completely separated from the sample gas, and the components of the sample gas cannot be influenced;
(4) The sampling device provided by the invention utilizes the designed degassing plug and the vacuumizing and liquid injection method, and can better meet the collection work of high-temperature gas under different working conditions by replacing the phase change working medium in the rotating body cavity, changing the vacuum degree in the rotating body cavity and the like according to the change of environmental conditions;
(5) The sampling device provided by the invention can improve the sampling precision and reduce the cooling medium conveying and cooling energy consumption by using the temperature and pressure sensor and early calibration, so that the sampling device can run stably with high precision under different working conditions, and the sampling is more flexible (the sampling of high-temperature gas with different flow requirements can be realized by adjusting the speed of the rotating shaft).
Claims (5)
1. A rotary aerosol quantitative sampling device is characterized in that: the sampling device comprises a hollow stator (2), a sample inlet (1) and a sample outlet (4) which are arranged on the hollow stator (2), and a plurality of hollow rotors which are arranged in the hollow stator (2) and used for moving aerosol from the sample inlet (1) to the sample outlet (4) through the residual space in the hollow stator (2); a cavity and a heat transfer working medium which is positioned outside the cavity and can be subjected to phase change are arranged in the hollow rotor, a cooling medium is arranged in the cavity, a heat absorption interface of the heat transfer working medium is a part or all of the wall surface of the hollow rotor, which is in contact with the aerosol, and a heat release interface of the heat transfer working medium is the wall surface of the cavity;
gaps which move in a matching mode are reserved between the hollow stator and the hollow rotor and between the hollow rotors, the hollow rotors move periodically along the matching end faces between the hollow stators and the inner wall of the hollow stator, so that a plurality of relatively sealed cavities are kept in the hollow stator all the time, and the relatively sealed cavities move along with the rotation of the hollow rotors, so that gas can be conveyed from the sample inlet to the sample outlet; the phase change of the heat transfer working medium outside the hollow cavity of the hollow rotor is utilized to exchange heat with the cooling medium in the hollow cavity, so that the stability of the gap is kept, and higher sampling precision can be kept;
a liquid inlet hole (8) is formed in the hollow rotor, and a degassing plug used for controlling the injection and discharge of the heat transfer working medium is arranged in the liquid inlet hole (8);
the degassing plug comprises a lifting cylinder, a connecting pipe connected with an opening of the lifting cylinder, and a flow guide hole and a sealing head which are arranged on the sealing end surface of the lifting cylinder, wherein the flow guide hole and the sealing head are matched with a step surface positioned in the liquid inlet hole (8), so that the liquid inlet hole can be sealed by the sealing end surface and a second sealing washer positioned on the step surface;
the connecting pipe fitting can be embedded into the liquid inlet hole when the second sealing washer is pressed on the closed end face of the lifting cylinder, and the top of the connecting pipe fitting is positioned below the surface of the hollow rotor;
the number of the hollow rotors is two, and the hollow rotors are mutually matched in synchronous rotation by adopting the rotor profiles of the double-rotor roots pump and are respectively matched with the inner wall of the hollow stator (2);
the sampling device also comprises a sensor for detecting the temperature and/or pressure of the gas at the sample inlet (1);
controlling the rotating speed of the hollow rotor according to a table of hollow rotor rotating speed, sample inlet pressure and sample inlet flow obtained by pre-calibration, thereby controlling the gas flow in the sampling process; and controlling the flow of the cooling medium according to a table of injection port temperature-gas flow-cooling medium flow obtained by pre-calibration.
2. A rotary aerosol quantitative sampling device according to claim 1, wherein: the hollow rotor is provided with a hollow rotating shaft (10) penetrating through the center of the hollow rotor, the cooling medium flows inside the hollow rotating shaft (10), and the heat transfer working medium is arranged between the outer wall surface of the hollow rotating shaft (10) and the inner wall surface of the hollow rotor.
3. A method of quantitatively sampling an aerosol with a rotary aerosol quantitative sampling device according to claim 1, wherein: the method comprises the following steps:
connecting the sample inlet (1) to an exhaust passage of a certain burner; the hollow rotor arranged in the hollow stator (2) is rotated, so that aerosol with a certain volume in the exhaust passage is moved to the sample outlet (4) from the sample inlet (1) through the residual space in the hollow stator (2), and the sampling of the exhaust passage is realized; in sampling, the heat transfer working medium is utilized to perform phase change heat absorption and phase change heat release on a corresponding interface, and meanwhile, the rotating speed of the hollow rotor is adjusted according to the gas pressure collected from the sample inlet (1) so that the sampling amount is kept constant in the sampling process.
4. The method of claim 3, wherein: the number of the hollow rotors is two, the two hollow rotors are respectively driven by one hollow rotating shaft (10), the two hollow rotors synchronously rotate through the rotor profile of the double-rotor roots pump, and the cooling medium flows through the centers of the corresponding hollow rotors through the hollow rotating shafts (10).
5. The method of claim 3, wherein: before sampling, the degassing plug is arranged in a liquid inlet hole (8) on the hollow rotor, and the hollow rotor is vacuumized by the degassing plug and then the heat transfer working medium with a certain volume is injected into the hollow rotor through the degassing plug.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN201911378029.2A CN110879159B (en) | 2019-12-27 | 2019-12-27 | High-temperature high-humidity aerosol sampling device and sampling method |
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| CN201911378029.2A CN110879159B (en) | 2019-12-27 | 2019-12-27 | High-temperature high-humidity aerosol sampling device and sampling method |
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| CN116878979B (en) * | 2023-09-06 | 2023-11-14 | 启东市恒盛仪表设备有限公司 | Self-cooled industrial gas sampler |
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