RU2662763C1 - Method of toxic impurities average concentrations in the aircraft pressurized cabins air estimation and in the air coming from the gas turbine engines compressors, and device for its implementation - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: group of inventions relates to the field of samples production and preparation for the materials in the gaseous state study and analysis. Toxic impurities average concentrations in the aircraft pressurized cabins air and air coming from the gas turbine engines compressors estimation method, includes the cabin or from the engine flange air sampling by its pumping through the sampler cartridges with sorbent followed by the gas chromatographic analysis on the different selectivity and polarity towers to identify the impurities components, wherein the cabin or from the engine flange air sampling is performed in accordance with the sampling isokinetic principle, for this purpose it is sequentially passed into two samplers, at that, the first sampler with heavy vapors and low dynamic resistance aerosol particles sorbent-filter is used in the aspiration mode and performing the toxic impurities sampling at the air pumping flow rate commensurate with the air flow rate during respiration, then the passed through it air sample is pressurized under excess pressure into the second sampler through the concentrator tube with high dynamic resistance sorbent to absorb the light vapors, at that, the process is cyclically repeated throughout the flight, which reduces the error caused by the light components part irreversible adsorption on the light vapors sampling vessel inner surface, amount of pumped through the samplers air will be equal to the multiplied by the number of cycles sub-piston space total volume, and is reduced to normal conditions, taking into account of the flight average cabin air temperature and pressure or in the air taken from the GTE (according to the on-board sensors readings). Also disclosed is the flight average impurities samples sampling device in the aircraft pressurized cabin air and in the air coming from the gas turbine engines compressors.

EFFECT: enabling increase in the cabins pollution assessment reliability due to the strict adherence to the air sampling isokinetic principle.

3 cl, 1 dwg

Description

Technical field

The invention relates to the field of preparation and preparation of samples for research and analysis of materials in a gaseous state, and in particular to methods for estimating average concentrations of toxic impurities in flight in the pressurized cabin of aircrafts and in air coming from compressors of gas turbine engines, and a device for assessing air purity of the pressurized cabin aircraft and air coming from compressors of gas turbine engines for the content of decomposition products of lubricating oils and can be used for charging water and certification tests of aviation equipment for compliance with the requirements of §25.831 according to aviation rules AP-25 in terms of checking the quality of breathing to passengers and crew from the air conditioning system taken from gas turbine engines, SanPiN 2.5.1.2423-08 and GN 2.2.5.1313-03-03 . They can also be used in assessing the purity of air sampled from gas turbine engines in flying laboratories.

State of the art

The main source of air pollution in aircraft cabs is the removal of lubricating oil from the front engine mounts with its subsequent complete or partial decomposition in the gas turbine compressor path (depending on its operating mode). A complex mixture containing, according to LII, TsIAM, GOSNIIGA and NIIAKM, vapors and aerosols of lubricating oil, vapors of aliphatic hydrocarbons, acrolein, formaldehyde, phenol, cresols, acetic acid, benzene, tricresyl phosphate (if it is in the oil formulation, as well as in this case and dioctyl sebacinate), ethyl, propyl, butyl, and isobutyl alcohols, acetone, toluene, xylenes, oxide and nitrogen dioxide, oxide and carbon dioxide, comes from the air conditioning system (SCR) into the aircraft cabin. In order to assess the concentration of all these impurities in the air of aircraft cabins at different stages of flight, it is necessary to carry out the selection and analysis of a large number of air samples. In this case, it is mainly a question of assessing the non-exceeding of critical parameters (maximum permissible concentrations - MPC), and as a result, the overall level of air pollution in the aircraft cabin is estimated very poorly, despite the large number of flight air samples taken. At the same time, the average concentration over flight does not practically determine.

Meanwhile, the air impurities of the aircraft cabins not only affect the crew’s condition, but also when they accumulate adversely affect various technical devices that consume air taken from the gas turbine engine, in particular, ozone converter catalysts are poisoned by sulfur and phosphorus compounds, and zeolites included in the composition of oxygen production plants can irreversibly adsorb polar organic compounds (alcohols, acids, phenol and cresols), which will lead to their inability to separate oxygen and nitrogen from the air. Therefore, knowledge of the average concentrations of cabin air impurities per flight is necessary, even if they cannot have a significant effect on the crew and passengers (concentration levels below 0.5 MPC do not require an accurate assessment according to sanitary standards).

To do this, it is proposed to change the selection procedure for the proposed method.

Domestic requirements for the cleanliness of the air supplied for ventilation of the premises for the crew and passengers are regulated in the Aviation Rules, part 25, “Airworthiness Standards of Transport Aircraft” AP-25. In accordance with §25.831, along with the requirement that the ventilation system supply a sufficient amount of air (a) that does not contain “harmful and dangerous concentrations of gases and vapors” (b), the need to ensure the following conditions has been established:

- MPC of toxic impurities, mg / m ³ , (d *):

- fuel vapor - 300;

- vapors and aerosol of mineral oils - 5;

- vapors and aerosol of synthetic oils - 2;

- acrolein - 0.2;

- formaldehyde - 0.5;

- phenol - 0.3;

- benzene - 5;

- tricresyl phosphate - 0.5;

- dioctyl sebacinate - 5.0;

- nitrogen oxides - 5.

Known methods for sampling air into gas syringes, followed by gas chromatographic analysis. Here, the number of samples at one point will be equal to the number of normalized components, which leads to a huge total number of samples. Many similar methods are described in the handbook of physico-chemical methods for studying environmental objects edited by G.I. Aranovich, publishing house "Shipbuilding", Leningrad, 1979, p. 166-211.

The closest in technical essence to the invention is the technique described in the report of FSUE LII them. M.M. Gromov No. 170-06-111. “Development of a methodology for determining the concentrations of toxic impurities in the air of aircraft cabins and assessing the sources of its pollution in accordance with the requirements of AP-25 and international regulatory documents.” Here, to evaluate the airborne cabin air content of several dozen organic impurities, it is proposed to take only 3 to 5 air samples in parallel by aspiration through cartridges with a sorbent by connecting a vacuum container or aspirator to the free end, followed by gas chromatographic analysis on columns of different selectivity and polarity. For engines, similar methods are described in MU 1.1.258-99. “Methodical instructions. Gas turbine aviation engines. The procedure for sampling and gas chromatographic analysis of air samples from an engine compressor during bench tests. ” NIISU, 1999.

The disadvantage of this method is that all these samples must be continuously taken in flight, which is often expensive and difficult, and at the end of the flight program it may turn out that it is not enough for a complete calculation of the average concentrations of the samples taken (large intervals between samplings). In addition, since selection is made by the aspiration method (maximum pressure drop is 1 atm), the pumping speed through typical concentrators is 0.1-0.2 l / min, which is 2 orders of magnitude less than the air flow during breathing (18-25 l / min), then selection cannot be called isokinetic. The dynamic resistance of concentrators can be reduced only by decreasing the weight of the sorbent in them, which will lead to a breakthrough of a number of volatile toxic components (formaldehyde, acrolein, acetaldehyde, acetone, benzene). Therefore, to determine the average concentration in the air of an aircraft cockpit per flight, hubs must often be changed (up to 100 units per flight). The pumping speed is already low, and due to the principle of isokineticity it cannot be reduced to reduce the number of samplers.

Known devices for sampling and storing air samples in the form of glass ungraded gas pipettes with two one-way valves, made in accordance with GOST 18954-73 "Glass apparatus and pipettes for sampling and storage of gas samples."

Similar devices are in the form of cans described in ASTM (2001): Standard Test Method for Determination of Volatile Organic Chemicals in Atmospheres (Canister Sampling Methodology), West Conshohocken, PA, American Society for Testing and Materials (ASTM Standard D5466-01 ) ". In this case, the canister with a shut-off valve is used either pre-evacuated, or the selection is made by gas exchange (purging the canister with a large amount of air).

Various versions of such devices (sampling into gas pipettes, plastic bags, etc.) are suitable only for sampling air for the content of weakly adsorbed gases, and according to Russian airspace standards, the content of high-boiling compounds (oil, kerosene, tricresyl phosphate and etc.).

The well-known "Complex of sampling air", patent for invention No. 2494366, comprising a housing consisting of interconnected vertical panels on which there are samplers with adsorption bags having concentrators, electromagnetic valves, filters - moisture separators, temperature and pressure sensors, a sampling collector installed in front of the GTE subject, a diffuser with nozzles, a vacuum pump and a control panel. However, this complex is used only for bench tests of engines.

The aspirator for air sampling TU 64-1-862-77, model 822, is produced by the Leningrad association of enterprises of medical equipment "Krasnogvardeets" (Leningrad, P-22, Instrumental, 3). The device consists of an electric motor, a small air pump (flow rate inducer) and several rotameters (flow indicators). The device allows you to simultaneously take two samples for dust (aerosols) with a space velocity of up to 20 l / min and two samples for gases (vapors) with a space velocity of up to 1 l / min. However, the maximum pressure drop during selection by such devices is not more than 1 atm (actually 0.2-0.3 atm). The speed of pumping by such devices through a cartridge with a sorbent (concentrator) is not more than 0.1 l / min, and when using tightly packed tubes with a small cross section (recommended for sampling and subsequent analysis on a capillary chromatographic column without dumping part of the sample), it may be less than 0, 01 l / min, which does not meet the requirement of isokinetics. Oil aerosol with impurities adsorbed on its surface - the main air pollutant of aircraft cabins - will not get into the sampler at low pumping speeds.

Closest to the proposed device is a manual sampler, patent RU No. 89701, publ. December 10, 2009, the trade name is NP-3M (hereinafter referred to as NP-3M), intended for the collection of single samples of gas-air mixtures for the purpose of subsequent determination of their chemical composition in accordance with GOST 51712-2001, GOST 12.1.014-84, GOST 51945-2002. The manual NP-3M sampler pump is an original development of Crismas + CJSC and is produced according to KRMF.418311.002TU.

This device contains: a cylindrical body with a non-return valve, a risk stem and a handle, a piston with a rubber seal, a cover covering the over-piston space. This sampler pump does not have the disadvantages of the previous one. With periodic pumping of cabin air through a tube with a sorbent (concentrator), you can take an average sample for the flight. However, the disadvantages of such a device include manual drive, which requires the constant presence of an operator on board the aircraft, which is impossible for the engine at all, and the maximum pressure drop here is 1 atm. This will not be enough to maintain isokinetics when pumping air through concentrator tubes with high dynamic resistance. The real difference in air pressure to ensure pumping through such tubes should be 5-10 atm, which is unattainable when using the suction method, regardless of the design of the aspirator.

The present invention aims to achieve a technical result, which consists in increasing the reliability of the assessment of pollution of cabins due to the exact observance of the principle of isokinetic sampling of air.

Salient features

To obtain the specified technical result in the proposed method for estimating average flight concentrations of toxic impurities in the air of the pressurized cabin of aircraft and in the air coming from compressors of gas turbine engines, including sampling the cabin air or from the engine flange by pumping it through the sampler cartridges with a sorbent, s subsequent gas chromatographic analysis on columns of different selectivity and polarity to identify impurity components, cabin air sampling or from the engine flange is carried out in compliance with the principle of isokinetic selection. For this, the sampling is carried out sequentially in two samplers, while the first sampler with a sorbent filter of heavy vapors and aerosol particles with low dynamic resistance is used in the aspiration mode, and toxic impurities are sampled with an air flow rate comparable with the air flow rate during breathing. Then the air sample passed through it is forced under excessive pressure into the second sampler through a concentrator tube with a sorbent with high dynamic resistance to absorb light vapors. Moreover, the process is cyclically repeated throughout the flight. The amount of air pumped through the samplers will be equal to the total volume of the sub-piston space, multiplied by the number of cycles, and reduced to normal conditions, taking into account the average flight temperature and air pressure in the cabin or taken from the gas turbine engine (as indicated by the on-board sensors).

To achieve the named technical result in the proposed device for taking an average air flight sample in the cockpit and from aircraft gas turbine engines, containing a cylindrical body of the sampler with an inlet for sampling with a check valve installed inside it with a risk stem and a piston with rubber seal , in addition, an internal piston limiter is located inside the housing. In the over-piston space, a tensile spring is rigidly fixed to the housing wall and to the piston. An additional branch pipe is installed on the body, to which a small section concentrator tube is connected with a sorbent located inside and configured to provide high dynamic resistance to air, and a large section concentrator tube with a fiberglass-like material located inside is connected to a nozzle equipped with a non-return valve. The stem shank is equipped with a protrusion and a fixed guide rail with teeth, an end switch is installed at the end of the housing, made with the ability to actuate and turn off the electric drive when the shank protrusion touches it. An additional housing is mounted on the stem of the stem, in which the electric actuator of the stem is mounted, made in the form of an electric motor with a gearbox and a flexible shaft for transmitting rotation to the axis of fastening of the gear wheel, which engages with the gear rack on the rod. A spring is located on the axis of the gear wheel mounting. In this case, the axis of the gear wheel is made in the form of an electromagnet electrically connected to a control panel (PU), operating according to a push-pull sampling circuit in each cycle, a cycle counter, with an electric motor, a power source, with a limit switch, providing:

- at the beginning of each cycle, the possibility, when the electromagnet is off, turning on the engine and translating with the piston in the sampler, creating a predetermined pressure in the sub-piston space;

- the possibility in a minute of applying voltage to the electromagnet to separate the gear from contact with the teeth of the rack using a spring and releasing the rod.

The inner surface of the sampler body is made of Teflon or has a Teflon coating to reduce the adsorption of impurities. If the selection comes from the engine, the hubs are placed in protective housings.

The invention is illustrated in the drawing, which shows:

in FIG. 1 is a diagram of a device for implementing the proposed method, side view.

To clarify the essence of the inventions in FIG. 1 shows a device for sampling an average air flight per flight in aircraft cockpits and from aircraft gas turbine engines.

The proposed method is carried out in the following sequence.

Air samples are taken from the cabin or from the engine flange by pumping it through cartridges with a sorbent - a filter of heavy vapors and aerosol particles with low dynamic resistance in the aspiration mode with an air flow rate comparable with the air flow during breathing, and an air sample passing through it containing light decomposition products of oil - aldehydes, ketones, alcohols, are then forced under excessive pressure through a concentrator with a sorbent with high dynamic resistance and the amount of sorbent for absorption eeniya light vapors. The analysis accuracy is improved due to the observance of the principle of isokinetic sampling, which is carried out sequentially in two samplers. The process is cyclically repeated throughout the flight, which reduces the error arising from the irreversible adsorption of part of the light components on the inner surface of the sample tank of light vapor. Then, gas chromatographic analysis is carried out on columns of different selectivity and polarity to identify impurity components. Due to the use of the principle of isokinetic sampling, the time of the flight experiment to assess the air purity of the cabin of an aircraft or in a nacelle is significantly reduced by reducing the total number of air samples taken in flight required to calculate the average concentration of harmful impurities in the air per flight by applying a 2-stage sampling, implemented in one device.

The proposed device (Fig. 1) contains a cylindrical body 1 with an inlet pipe 2, a check valve 3 with a rod 4 located inside with risks and a piston 5 with a rubber seal. Inside the housing, an internal limiter 6 is made, and a spring 7 working in tension is rigidly fixed to the wall of the housing and the piston in the nadporshny space. An additional pipe 8 is installed on the housing, to which a small section concentrator tube 9 is attached with an adsorbent located inside and configured to provide high dynamic resistance to air, and a large section 10 concentrator tube is connected to a nozzle 2 equipped with a non-return valve, and a fibrous material of the type inside glass wool. Additionally, the stem of the stem 4 is equipped with a fixed rail with teeth 11 on the stem 4 and the protrusion 19, an end switch 20 is installed on the end of the housing 20. An additional housing 22 is mounted on the stem of the stem, in which the electric drive 13 of the stem is installed in the form of an electric motor with a gearbox and a flexible shaft 14 for transmission rotation on the axis of fastening of the gear wheel, which engages with the teeth of the rack 11 on the rod 4, and an electric drive with gear in the form of a gear wheel 12 and a flexible drive shaft 14 on the axis of the fastening 16 of the gear wheel 12, pressed against nike 11 spring 15, placed on the axis of the gear 16 of the gear wheel, while the axis of the gear 16 is made in the form of an electromagnet with an armature 17, electrically connected to the control panel (PU) 18, operating on a push-pull circuit for sampling in each cycle, cycle counter, PU is associated with an electric motor, cycle counter, power source 21, with a limit switch 20.

The device operates as follows.

Before the flight, the device is completed (Fig. 1) with absorbers. A large cross-section tube 10 with fibrous material is connected to the nozzle with a non-return valve 3 for sampling at the moment of retraction of the piston and subsequent analysis for oil aerosol, and to an additional nozzle 8 is connected a concentrator tube 9 for sampling under pressure (at the time of the piston release) with sorbent and with a small inner diameter. The device is placed inside the aircraft cabin or in a nacelle, providing air access from the engine to the samplers. If the selection comes from the engine, then the hubs are placed in protective tubes. At the beginning of the flight, the control panel 18 is turned on. It turns on the motor drive 14 with the gearbox 13. At the same time, the piston 5 moves inside the housing 1, stretching the spring 7 until the limit switch 20 actuates when the protrusion of the rod 4 is pressed on it. Upon the signal of the limit switch, the control panel turns off the engine and in one minute (the waiting time can be adjusted on the control panel) applies voltage to the electromagnet 17, the retracting axis 16 of the gear wheel 12, releasing the rod 4 with the piston 5. The rod 4 by the spring 7 returns the piston 5 to the stop 6. During this minute, the pressure of the air drawn through the valve 3, the pipe 2 and the crown tube with large air diameters from the under-piston space are equalized. This tube has a small dynamic resistance and pumping air through the tube 9 with a high resistance practically does not occur. At the end of this stage, the electromagnet 17 is turned off, and the motor with the drive is turned on, the rotating gear 12 is returned by spring 15 to contact the teeth of the rack 11, and the piston 5, moving, increases the pressure to a predetermined value in the sub-piston space of the housing 1. In this case, the check valve 3 does not release air through the tube 10, and all the air under pressure and with increasing temperature due to compression through the nozzle 8 is squeezed out through the tube 9 with a sorbent with high dynamic resistance until the end switch 20 is activated, then the cycle repeats.

At the end of the flight, the control panel turns off. From the counter of cycles on it readings are taken. The amount of air pumped through the samplers will be equal to the total volume of the sub-piston space, multiplied by the number of cycles, and reduced to normal conditions, taking into account the average temperature and pressure of the cabin air for the flight or in the air taken from the turbine engine (as indicated by the on-board sensors). Hubs 10 and 9 are sent for chromatographic analysis according to GOSTR ISO 16017.1-2007 (tube 10 - analysis for oil and its additives, tube 9 - analysis for volatile organic impurities.

Claims (5)

1. A method for estimating average flight concentrations of toxic impurities in the pressurized cabin of aircrafts or in air coming from compressors of gas turbine engines, including taking air samples from the cabin or from the engine flange by pumping it through the sampler cartridges with a sorbent, followed by gas chromatographic analysis on different columns selectivity and polarity for identifying impurity components, characterized in that the sampling of the cabin air or from the engine flange is carried out in compliance m of the principle of isokinetic sampling, for this it is carried out sequentially in two samplers, while the first sampler with a sorbent filter of heavy vapors and aerosol particles with low dynamic resistance is used in the aspiration mode and toxic impurities are sampled with an air flow rate comparable with the flow rate air during breathing, then the air sample passed through it is forced under excessive pressure into the second sampler through a concentrator tube with a sorbent with a large dyn resistance to absorption of light vapor, while the process is cyclically repeated throughout the flight, which reduces the error arising from the irreversible adsorption of part of the light components on the inner surface of the sample tank of light vapor, the amount of air pumped through the samplers will be equal to the total volume of the under-piston space, multiplied by the number of cycles, and is reduced to normal conditions, taking into account the average temperature and pressure of the cabin air for the flight or in the air taken t TBG as indicated by onboard sensors. 2. A device for sampling airborne samples of airborne impurities in the pressurized cabin of an aircraft or in air coming from gas turbine engine compressors, comprising a cylindrical sampler body with an inlet for sampling air, a non-return valve installed in it, with a risk stem located inside the body and a piston with a rubber seal, characterized in that in addition to the inside of the housing there is an internal piston movement limiter, and in the above-piston space to the housing wall and to the piston the tensile spring is firmly fixed, an additional nozzle is installed on the housing, to which a concentrator tube is connected with a sorbent located inside and configured to provide high dynamic resistance to air, and a concentrator tube with a fibrous material located inside is connected to a nozzle equipped with a non-return valve glass wool, the stem of the stem is equipped with a protrusion and a fixed guide rail with teeth, an end switch is installed at the end of the housing, With the ability to actuate and deactivate the electric drive when the shank protrusion touches it, an additional housing is mounted on the stem shank, in which the electric actuator of the stem is installed, made in the form of an electric motor with a gearbox and a flexible shaft for transmitting rotation to the axis of the gearwheel, which engages with the gear a rail on a rod equipped with a spring placed on the axis of the gear wheel attachment, while the axis is made in the form of an electromagnet electrically connected to a control panel (PU), functioning according to the push-pull sampling scheme in each cycle and associated with the cycle counter, electric motor, power source, with limit switch, providing: - at the beginning of each cycle, the possibility, when the electromagnet is turned off, of turning on the engine and translational movement of the piston in the sampler, which creates a predetermined pressure in the sub-piston space; - the possibility in a minute of applying voltage to the electromagnet of the separation of the gear from contact with the teeth of the rack, the release of the rod. 3. A device for sampling an average air flight over a flight according to claim 2, characterized in that if the sampling comes from the engine, the hubs are placed in protective casings.

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