RU2527980C1 - Method of sampling high-temperature gases and device for its realisation - Google Patents

Abstract

FIELD: measurement equipment.

SUBSTANCE: method to sample high-temperature gases at temperatures of up to 600°C includes measurement of gas volume pulled via a sampling probe by means of aspiration, and collection of condensate with reduction of the taken sample volume to normal conditions. To produce a representative sample that characterises a source of emission, the flow of high-temperature gases is cooled down to temperature of condensation of vapours of volatile components with account of fuel consumption and modes of engine operation. Aspiration of the sample volume is carried out with pressure difference in the condensate collector and in the flow of spent gases, besides, the flow of sampled high-temperature gas is used to create the "boiling layer" from initiators of condensation of volatile components vapours. At the same time the volume of the taken sample is compared to fuel consumption and mode of engine operation, and condensate is kept in the condensate collector under tight conditions to the start of stagewise investigation of concentration of separate components. The device comprises a sampling probe, a facility to measure the volume of high-temperature gases and a condensate collector. The sampling probe is equipped with a facility to measure temperature of sampled gases, the collector of condensate of spent gases has an external vacuumised heat-shielding shell, between layers of which there is a cryogenic liquid placed, and a facility to measure condensate temperature. Ball-shaped initiators of condensation are made of chemically inert material, which is capable of absorbing water vapours in spent gases composition. The cover of the condensate collector is thermally isolated from the vacuumised heat-shielding shell of the collector of spent gases condensate and nozzles for insertion of the sampling probe and discharge of cryogenically treated gases equipped with valves. At the same time the discharge nozzle is equipped with a filtering element, and the cover of the condensate collector has a control panel interconnected with the facility to measure temperature and gas volume taken for analysis, a level indicator of the cryogenic liquid and the facility to measure temperature of collected condensate.

EFFECT: development of the method and device to take representative samples of high-temperature gases of mobile sources of toxic emissions, which contain condensing elements that require special low-temperature conditions to keep them in the sample before entering them into a measurement device.

2 cl, 1 dwg

Description

The invention relates to methods and devices for sampling exhaust gases of internal combustion engines to analyze the technical condition of a vehicle in terms of the quality of use of motor fuels and its impact on environmental safety.

According to the classification adopted in international standards [GOST 31370-2008 (ISO 10715: 1997) Natural gas. Sampling Guide. M .: Standartinform, 2009], the claimed method and device relate to indirect point sampling with retrograde condensation:

- indirect sampling (indirect sampling) means "sampling in cases where there is no direct connection between the sampled gas and the analytical unit";

- spot sample: “A sample of a certain volume taken from a gas stream in a specific place at a specific time”;

- retrograde condensation: The process, which consists in the fact that "under critical thermodynamic conditions, a liquid is released from the gaseous mixture (isothermal and isobaric condensation)." Retrograde behavior is characteristic of multicomponent mixtures and reflects the non-ideal nature of their phase properties;

- representative sample: A sample extracted from the total volume of a product containing its components in the same proportions in which they are present in the total volume [GOST R 52659-2006 Petroleum and petroleum products. Manual sampling methods. M .: Standartinform, 2007].

Only well-mixed liquids and gases can satisfy this condition. There is no need to ensure representativeness of the sample if the object is sufficiently homogeneous in composition;

- isokinetic sampling (isokinetic sampling): Sampling at a flow rate that ensures the speed (v _n ) and the direction of the dust and gas flow entering the sampling nozzle are the same as the speed (v _s ) and flow direction in the pipe at the sampling points . [GOST R ISO 9096-2006 (ISO 9096: 2003) Emissions of stationary sources. Determination of mass concentration of solid particles by manual gravimetric method. M .: Standartinform, 2006 / [Electronic resource] - Access mode: access date 02.16.2013];

- method of internal filtration: It is used for sampling wet gases, the presence of aggressive components and resins in gases, high adhesive ability of dust, the dust collector is located inside [GOST R 50820-95 Gas cleaning and dust removal equipment. Methods for determining the dust content of gas and dust streams / [Electronic resource] - Access mode: - date of access 02.16.2013].

"Water condensate" means the precipitation of water-containing components, passing from a gas to a liquid state. The formation of water condensate is due to factors such as humidity, pressure, temperature and the concentration of other components, such as sulfuric acid. The impact of these factors varies depending on the humidity of the air entering the engine, the humidity of the dilution air, the ratio of air and fuel in the engine, and the composition of the fuel, including the amount of hydrogen and sulfur in the fuel [Global Technical Regulation No. 11. Introduced into the Global Register on November 12, 2009). "The test procedure for compression ignition engines to be installed on agricultural and forestry tractors and off-road mobile equipment, in relation to the emission of pollutants by these engines" / [Electronic resource] - Access mode: http://www.unce.org/fileadmin / DAM / trans / main / wp29 / wp29wgs / wp29gen / wp239registry / ECE-TRANS-180al lapplr.doc - accessed 02.16.2013].

A known method of cryogenic concentration (capture) of pollutants from the air. It consists in freezing toxic impurities while passing polluted air through a trap with sorbents or inert material (fiberglass, steel or glass balls, etc.) at temperatures substantially lower than the boiling points of the analyzed impurities. The main component (air) passes through the trap without being held in place, and impurities are collected (concentrated, condensed) in the trap [Yu.S. Drugov, A.A. Rodin. Sample preparation in environmental analysis. St. Petersburg, Anatolia, 2002, p. 78-79].

The method is mainly used in gas chromatography for analysis of priority air pollution at ppb-ppt level. Moreover, an excess of condensed water significantly complicates the process of subsequent use of the chromatographic method for determining pollutants [Berezkin V.G., Drugov Y.S. Gas chromatography in air Pollution analysis / Amsterdam, e.a .: Elsevier. 1991]. Moreover, high concentrations of pollutants force researchers to use not the method of "condensation", but the method of "diluting" the sample with sterile air or inert gases.

For the purpose of sampling and preparation for analysis of the exhaust gas composition of internal combustion engines of vehicles, the “Concentration-reducing sampler and method for taking and lowering the concentration of a gas sample” is known [patent RU 2419083 G01 N 1/22, publ.: 05.20.2011, BI No. 14 ]. According to the invention, a cooled inert gas is introduced into the gas stream, designed to cool the gas sample and to dilute it to concentrations that do not affect the accuracy of the measuring instruments. The invention is based on the “full flow dilution” method, which means the process of mixing the total exhaust flow with dilution air before separating the appropriate fraction of the diluted exhaust flow for analysis.

The disadvantage of this technical solution is the impossibility of concentrating in one sample of gases the vapors of volatile components and components in the form of aerosols of mechanical particles.

A device is known comprising a housing with an intake pipe located therein, a trap with a mesh or ceramic filter mounted on the outer surface of the housing at the gas inlet to the intake pipe, a refrigerator and a water trap connected to the pipes with the trap and the refrigerator, the trap and the refrigerator having individual valves for connecting them with nozzles of a water seal [patent RU No. 20111179, publ. 04/15/1994]. At the same time, a sealing device must be welded to the pipeline or to the metal casing of the channel through which the analyzed gases are moving, through which a gas sample is taken, and the sample is delivered to the analyzer using a special water-cooled probe, to which rubber sleeves are connected, inlet and outlet cooling water [Eszhanov I. Investigation of the effect of gas cooling rate on the formation of toxic components in refrigerated probes [Text] / I. Eszhanov, K.E. Arystanbaev // Young scientist. - 2012. - No. 2. - S.15-18].

The disadvantage of this device is its stationarity and the inability to use it in a portable state. In addition, the disadvantage of this device is the presence of a filter located on the surface of the housing of the device, distorting the true phase composition of the exhaust gases in the subsequent gas stream.

A device is known for sampling exhaust gases of a vehicle engine, comprising a sampler connected to an exhaust pipe and by means of an inlet pipe with a selective elastic chamber mounted in a portable device, and a control recording apparatus, characterized in that, in order to simplify the device and speed up the control process the composition of the gases on a moving vehicle in full-scale road conditions, the selective chamber is removable and equipped with a remotely controlled locking element ntom, a portable device provided with a nozzle, the outlet end of which is coplanar with the end of the probe [patent RU №2023250, publ. 11/15/1994].

The disadvantage of this device is the inability to obtain a representative sample at various engine operating modes and the inability to prevent secondary chemical reactions between the exhaust components of the internal combustion engine, which are inevitable at high temperatures of the exhaust gas of the internal combustion engine.

Known refrigerator device for sampling gas, in which the condensate drain is integral with the refrigerator. Cold junctions of the Peltier elements are fixed on the inside of the hollow cone, and a pipeline for sampling the measuring gas branches off from it. The refrigerator is characterized in that a battery of thermocouples is provided as a current generator consumed by Peltier elements, hot junctions of which are located in the flue gas channel, and cold junctions are in the outer space [Application for the invention of Germany No. 1297902 / [Electronic resource] - Access mode: 189 & chapter = 83 - date of conversion 02.16.2013].

The disadvantage of this device is the inability to collect the exhaust gas condensate of the internal combustion engine for non-stationary sources.

A device for sampling exhaust gases of the engine, allowing sampling on a moving vehicle. The device comprises a sampler equipped with a cooler, a flow meter and a distributor connected to it, a selective chamber, a tracking system connected to the sampler. In this case, the selective chamber is made in the form of a syringe mounted on a distributor and equipped with an electromechanical drive connected to a tracking system, while the syringe rod is frictionally connected to the drive using a rack rod equipped with an electromagnetic rolling drive and pivotally connected to it [UK Patent Application No. 1496173, G01N 1/24, 1977].

A device for sampling dust and gas from a high temperature dust and gas stream containing

condensable components, consisting of a cooled nozzle, a seal and a moving mechanism, characterized in that, in order to preserve the physicochemical properties of the samples taken, the intake nozzle is placed in an airtight capsule with a liquid coolant equipped with a sectioned cooling jacket [patent SU No. 3445214, publ. 01/01/1972].

A disadvantage of the device is the inability to collect the exhaust gas condensate of the internal combustion engine for non-stationary sources.

Of the known methods for sampling high-temperature gases, the closest in number of common essential features is the method of sampling high-temperature gases from gas ducts for measuring concentrations of harmful substances in exhaust emissions at temperatures up to 600 ° C, which consists in measuring the volume of gas drawn through a sampling probe, with the subsequent reduction of the volume of the sample to normal conditions [“PND F 12.1.1-99. Guidelines for sampling in determining the concentrations of harmful substances (gases and vapors) in industrial emissions ”(approved by the RF State Committee for Ecology on March 24, 1999) / [Electronic resource] - Access mode: - accessed date February 16, 2013].

The disadvantages of the method include the impossibility of its use for sampling exhaust gases of internal combustion engines of a moving vehicle. The method does not make it possible to evaluate the fuel efficiency at different operating modes of the internal combustion engine based on an analysis of the ratios of different groups of chemical compounds of the exhaust gas of the internal combustion engine, including highly volatile components, for the sorption of which cryogenic temperatures are required.

Method - an analogue is implemented by a device including: an aspiration device, a sampling probe, absorbers, a condensate collector, means of preventing overflow, a thermometer for measuring temperature and a manometer for measuring pressure in the sampling line ["PND F 12.1.1-99. Guidelines for sampling in determining the concentrations of harmful substances (gases and vapors) in industrial emissions ”(approved by the RF State Committee for Ecology on March 24, 1999) / [Electronic resource] - Access mode: - accessed date February 16, 2013].

The disadvantage of this device is the ability to use only in stationary conditions. At the same time, a cooled sampling probe cannot ensure the safety of components in the sample that condense and remain in the sample only at low temperatures.

The technical result of the invention is the development of a method and device for the selection of representative samples of high-temperature gases from mobile (non-stationary) sources of toxic emissions, which contain condensable components that require special low-temperature conditions to be stored in the sample before they are introduced into the measuring device. Moreover, the method may be applicable for use in the sampling of exhaust gases of internal combustion engines outside the maintenance areas, i.e. in the field, for the subsequent assessment of the technical condition of the vehicle, including an assessment of the environmental hazard of the impact of a complex of chemical factors in the composition of its exhaust gases.

The problem is solved in that in the known method of sampling high-temperature gases at temperatures up to 600 ° C, including measuring the volume of gas drawn through a sampling probe by aspiration and collecting condensate with the volume of the sample taken to normal conditions according to the invention to obtain a representative sample characterizing the source emissions, the flow of high-temperature gases is cooled to the condensation temperature of the vapor of volatile components, taking into account fuel consumption and engine operating conditions, while m the suction of the sample volume is carried out by the pressure drop in the condensate collector and in the exhaust gas stream, and a “fluidized bed” is created from the condensing initiators of the vapor of the volatile components by the high-temperature gas stream, while the volume of the sample taken is compared with the fuel consumption and engine operating mode, and the condensate is stored in a condensate collector in sealed conditions before the start of a phased study of the concentration of individual components, as well as the fact that the device for implementing the method consists from a sampling probe, a means of measuring the volume of high-temperature gases, a condensate collector, according to the invention, the sampling probe is equipped with a means for measuring the temperature of the sampled gases, the condensate collector of the exhaust gases has an external evacuated heat-shielding shell, between the layers of which there is a cryogenic liquid and a means for measuring the temperature of the condensate, while the condensation initiators spherical shape made of chemically inert material with the ability to absorb water vapor the composition of the exhaust gases; moreover, the lid of the condensate collector has thermal isolation with the evacuated heat-shielding shell of the condensate of the exhaust gas and the inlet of the inlet of the sampling probe and the outlet of cryogenic treated gases equipped with valves, while the outlet pipe is equipped with a filter element, and the lid of the condensate collector has a control panel interconnected with a temperature measuring means and the volume of gas sampled for analysis by a cryogenic liquid level gauge and means for measuring the temperature of the collected condensate.

The design of the condensate collection device is shown in the drawing.

The inventive method is implemented by the following actions:

1. Before starting work, a cryogenic liquid, for example liquid air, is poured into the cryogenic liquid tank, which cools the walls of the cylindrical tank of the condensate collector to low temperatures.

2. In order to register the parameters of indirect point sampling with retrograde condensation of the majority of vehicle exhaust gas composition ingredients, the processor is tuned to the engine operating mode, the initial temperature parameters of the walls of the condensate collector are recorded and the meter of the flow rate of the sampled gas is reset to zero.

3. Into the exhaust pipe of the vehicle without touching the walls of the exhaust pipe, i.e. coaxially, a sampling probe is introduced at a distance of 300 mm from the nozzle cut.

4. The portion of the hot exhaust gas of the internal combustion engine, taken into account by the volume counter, injected through the sampling probe by the pressure of the main exhaust gas stream of the engine into the cavity of the condensate collector, is cooled to the dew point of most ingredients of the exhaust gas composition, which condense and adsorb on the walls of the condensate collector, on the surface of the droplet eliminator and on mechanical objects located at the bottom of the condensate collector, and contributing to the condensation of the vapor of the exhaust gases of the internal combustion engine, which accumulate at the bottom of the condensate collection.

5. The sampling is terminated by a strong-willed decision. An alarm to complete the sampling of gas for analysis is the processor’s testimony about a rise in condensate temperature above minus 120 ° C or a critical drop in the level of a cryogenic liquid tank.

6. The sampling stops with the removal of the sampling probe from the pipe of the vehicle, which is automatically accompanied by the closing of the valves of the inlet and outlet openings in the lid of the condensate collector.

7. The sample taken in condensed form, together with the device ensuring its conservation at a given temperature, is sent to the place of analysis of gaseous, liquid, and solid (residual) fractions of the sample taken out when the sample is heated.

8. At the end of the analytical work, the cavity of the condensate collector, removed from the cylindrical casing of the device and freed from condensate, is subjected to cleaning by heating with hot water and treatment with degreasing liquids, for example acetone [GOST 2768-84 “Technical Acetone. Specifications "], followed by drying by pumping hot air.

A device that implements the inventive method has a metal heat-resistant sampling probe 1, made, for example, in the form of a cylindrical stainless steel tube inserted into the pipe 2 of the exhaust pipe of the exhaust source, and means for measuring the volume 3 of the sample taken, connected to the control panel 4 located on the cover 5 of the cylindrical device 6, made in a portable design, which houses a condensate collector 7 in the form of a cylindrical container made of cold-resistant and gas-tight metal, in the cavity of which a droplet eliminator 8, for example, of a mesh type, located across the cavity of the condensate collector 7, is placed on the bottom of which there are freely condensing initiators for 9 vapors of the internal combustion engine exhaust gases, for example, in the form of KSMG silica granules [GOST 3956-76 “Technical silica gel. Specifications ”], while the walls of the condensate collector 7 are in contact with the walls of the tank 10 containing cryogenic liquid, such as liquid air, and the walls of the tank 10 with cryogenic liquid have a heat-insulated and evacuated outer shell 11, and the upper wall of the condensate collector 7 has a removable heat-insulated lid 5, equipped with thermal junctions 12, made, for example, of fluoroplastic, at the points of contact of the cover 5 with the end edges of the tank with cryogenic liquid 10, as well as at the points of passage of the nozzle 13 for filling the tank 10 with cryogenic liquid, the upper parts of the inlet pipe 14 of the sampling probe 1 and the outlet pipe 15 for the treated air from the condensate collector 7 are insulated, and the lid 5 on the inner surface has a reflective heat shield 16, mirror type, made, for example, of metal foil with a reflection coefficient of at least 0.9; moreover, the holes in the cover 5 for the inlet pipes 14 and the exhaust gas outlet 15 from the condensate collector 7 are provided with valves 17 that automatically operate after the extraction of the sampling probe 1; the control panel 4 located on the outer surface of the cover 5 is interconnected with the level sensors 18 of the cryogenic liquid in the tank of the cryogenic liquid 10, with a condensate temperature measuring sensor 19 in the condensate collector 7 and with an exhaust gas volume measuring device 3, for example, an ultrasonic non-contact type selected for analysis, which excludes the possibility of its metrological failure due to the sticking of viscous substances in the composition of the exhaust gases; wherein the outlet pipe 15 in the lid 5 of the condensate collector contains a retrievable coarse mesh type filter holder 20 with an aerosol trap 21, for example, AFA-KhP-8 type, which, due to its electrostatic properties, can trap “mist” aerosols with particles of 0.01-2.0 μm, and the input pipe 14 and the output pipe 15 are equipped with removable transport plugs 22.

The method is as follows. When sampling, we used suction devices of various types, which are an essential sign of analogues of the claimed technical solution. It turned out that the pressure of the exhaust gas flow transferred to the sampling probe, combined with the pressure drop in the condensate cavity of the collector due to mass condensation of the exhaust gas vapor, makes the use of an aspirator unnecessary. The flow of exhaust gases with a temperature of 300-500 ° C (the actual temperature of the exhaust gas of the internal combustion engine in the vehicle nozzle) to obtain a representative sample characterizing the composition of the exhaust gases at a given engine operation at a given fuel consumption and at a given air-fuel ratio (a), t. e. regardless of atmospheric pressure and ambient temperature, through a sampling probe 1, introduced into the pipe 2 of the exhaust pipe, enters the cooled cavity of the condensate collector 7, which has a much larger cross-section than the cross-section of the sampling probe 1, which leads to the loss of space velocity measured means for measuring a volume of 3, component of not more than 100 l / min, is in contact with the cooled walls of the condensate collector 7, a mesh droplet eliminator 8 and with spherical vapor condensation initiators 9, made for example, from KSMG silica gel with an absorbing capacity of 9–20% to absorb water vapors, which make up 4–8% of the ICE exhaust gas composition, there is a sharp cooling and multiple swirls of the flow, which contributes to the formation of a “fluidized bed” from spherical vapor condensation initiators 9 , which creates the conditions for the condensation of the constituent elements of the exhaust gas engine; the gas flow, which has lost kinetic energy, once again, but now passes from the bottom up through the droplet eliminator 8, is filtered from aerosols in the filter 21 and is removed through the outlet pipe 15 in the cover 5 of the condensate collector.

Multiplicity of sampling corresponds to 100 l of the selected sample; an alarm signal to the end of the sample is the temperature indicator of the collected condensate, approaching minus 120 ° C, which is the critical temperature of adsorption of the most volatile components of the exhaust gas composition of engines running on hydrocarbon fuel, while the fuel consumption at the time of sampling at this engine operating mode is taken from the on-board computer.

At the end of sampling, the sampling probe 1 is removed from the input pipe 14 of the cover 5 of the condensate collector 7, which leads to the closure of the valves 17 in the holes of the cover 5 of the condensate collector 7, ensuring thermal stability of the sample in the cavity of the condensate collector 7 along with its thermally insulated outer walls 11. To exclude external the contaminants, the nozzles 14 and 15 are protected by transport plugs 22. In this case, the nozzle 23, ensuring the coaxial location of the sampling probe 1 in the lumen of the nozzle 2 of the vehicle, It is a C nozzle 2 and degreased with acetone to remove impurities. After completion of sampling, the sampling probe 1 is placed in a plastic bag and sent to the laboratory for extraction of deposits.

A sample of exhaust gases of an internal combustion engine of an emission source, taken according to the present method and stored at temperatures up to minus 120 ° C, followed by gradual heating in laboratory conditions allows to separate from the sample by phased target extraction groups of ingredients that require different temperature heating modes for desorption, and measure concentrations of up to 40 types of ingredients, gaseous products of incomplete combustion of hydrocarbon fuels, crankcase gases and products of their interaction And particulate matter, including soot and mineral metal salts (sulfates, nitrates, phosphates); moreover, the filter 20, placed in the filter holder 21, installed in the outlet pipe 15, allows to capture almost all aerosols in the flow of the exhaust gas sample of the internal combustion engine at a sampling speed of not more than 100 l / min.

The analysis of the prior art made it possible to establish that the applicant has not found a prototype characterized by features identical to all the essential features of the claimed invention, therefore, the proposed technical solution meets the criterion of "novelty." Comparison of the essential features of the developed device with the features of known solutions gives reason to believe that the proposed technical solution meets the criteria of "inventive step" and "industrial applicability".

Claims (2)

1. A method of sampling high-temperature gases at temperatures up to 600 ° C, including measuring the volume of gas drawn through a sampling probe by aspiration, and collecting condensate to bring the volume of the sample to normal conditions, characterized in that to obtain a representative sample characterizing the source of emissions , the flow of high-temperature gases is cooled to the condensation temperature of the vapor of volatile components, taking into account fuel consumption and engine operating conditions, while the aspiration of the sample volume is carried out It is determined by the pressure drop in the condensate collector and in the exhaust gas stream, and a “fluidized bed” is created from the condensation initiators of the vapor of volatile components by the flow of the selected high-temperature gas, while the volume of the sample taken is compared with the fuel consumption and the engine operating mode, and the condensate is stored in the condensate collector in tight conditions before the start of a phased study of the concentration of individual components. 2. The device for implementing the method according to claim 1, consisting of a sampling probe, means for measuring the volume of high-temperature gases, a condensate collector, characterized in that the sampling probe is equipped with means for measuring the temperature of the sampled gases, the exhaust gas condensate collector has an external evacuated heat-shielding shell, between the layers which contains a cryogenic liquid, and a means for measuring the temperature of the condensate, while the ball-shaped condensation initiators are made of chemically inert m a material with the ability to absorb water vapor from the exhaust gas composition, the condensate collector cover being thermally isolated with the evacuated heat shield of the exhaust gas condensate collector and the inlet of the sampling probe and the outlet of cryogenically treated gases equipped with valves, while the outlet nozzle is equipped with a filter element, and the cover condensate collector has a control panel, interconnected with a means of measuring the temperature and volume of gas taken for analysis, ogenic fluid and a means of measuring the temperature of the collected condensate.

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