1、_ SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising there
2、from, is the sole responsibility of the user.” SAE reviews each technical report at least every five years at which time it may be reaffirmed, revised, or cancelled. SAE invites your written comments and suggestions. Copyright 2011 SAE International All rights reserved. No part of this publication m
3、ay be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE. TO PLACE A DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada) Tel: 724-776-4970 (outside USA)
4、 Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org SAE values your input. To provide feedback on this Technical Report, please visit http:/www.sae.org/technical/standards/ARP1256D AEROSPACE RECOMMENDED PRACTICE ARP1256 REV. D Issued 1971-10 Revised 2011-07 Supersedin
5、g ARP1256C Procedure for the Continuous Sampling and Measurement of Gaseous Emissions from Aircraft Turbine Engines RATIONALE Define the set point temperature range of the hydrocarbon analyzer. 1. SCOPE This SAE Aerospace Recommended Practice (ARP) describes the continuous sampling and analysis of g
6、aseous emissions from aircraft gas turbine engines. The measured gas species include carbon monoxide (CO), carbon dioxide (CO2), nitric oxide (NO), nitrogen dioxide (NO2), hydrocarbons (HC) and water vapor (H2O). This ARP excludes engine operating procedures and test modes, and is not intended for i
7、n-flight testing, nor does it apply to engines operating in the afterburning mode. It is recognized that there will probably be major advances in the gas analysis measurement technology. It is not the intent of this ARP to exclude other analysis techniques, but to form the basis of the minimum amoun
8、t of conventional instruments (those in common industry usage over the last fifteen years) required for the analysis of aircraft engine exhaust. It is the responsibility of the analyst to demonstrate the alternative measurement technology has comparable (or better) performance than the techniques de
9、scribed in this ARP. The measurement of other exhaust gas species is beyond the scope of this ARP. It should be noted the measurement of oxygen (O2) is generally accepted as essential for assessing data quality, but is not covered by this ARP. Sulfur dioxide (SO2) is normally not measured using conv
10、entional systems but is calculated from fuel sulfur content. Again this is not covered by this ARP. 2. REFERENCES 2.1 APPLICABLE DOCUMENTS The following publications form a part of this document to the extent specified herein. The latest issue of SAE publications shall apply. The applicable issue of
11、 other publications shall be the issue in effect on the date of the purchase order. In the event of conflict between the text of this document and references cited herein, the text of this document takes precedence. Nothing in this document supersedes applicable laws and regulations unless a specifi
12、c exemption has been obtained. 2.1.1 SAE Publications Available from SAE International, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (inside USA and Canada) or 724-776-4970 (outside USA), www.sae.org. ARP1533 Procedure for the Analysis and Evaluation of Gaseous Emissions from
13、 Aircraft Engines SAE ARP1256D Page 2 of 19 3. SECTIONS This document is divided into the following sections: 4. Definitions and Terminology 5. Equipment 6. Analyzer Routines 7. Calibration Gases 8. System Layout 9. Test Procedure 10. Sampling 11. Information and Data to be Recorded 12. Calculation
14、of Results and Measurement Uncertainty 4. DEFINITIONS AND TERMINOLOGY 4.1 ACCURACY The closeness of agreement between a measured value and a true value. 4.2 AIRCRAFT GAS TURBINE ENGINE Any gas turbine engine used for aircraft propulsion or power generation, including those commonly called turbojet,
15、turbofan, turboprop, or turbo-shaft type engines. 4.3 CALIBRATION GAS A certified and traceable gas mixture of specified and known concentration used for adjustment of the analyzer gain to establish the basis for interpretation of the values of quantities indicated by the measuring instrument and th
16、ose values realized by the calibration gas mixture(s). 4.4 CERTIFIED AND TRACEABLE Documentory evidence awarded to an instrument, process or gas mixture that defines the property of the result of a measurement or the value of a standard whereby it can be related to stated references, usually nationa
17、l or international standards, through an unbroken chain of comparisons all having stated uncertainties. 4.5 CHEMILUMINESCENT DETECTOR (CLD) An instrument specific to Nitric Oxide (NO) that operates by detecting the light emitted when NO is reacted with ozone (O3). The same instrument in a different
18、measurement mode, can be used to analyse Oxides of Nitrogen (NOx) by catalytically converting the NOx to NO. The difference between this NOx and the original NO measurement is assumed to be Nitrogen Dioxode (NO2). 4.6 CONCENTRATION The volume fraction of the component of interest in the gas mixture
19、expressed as volume percentage or as parts per million by volume (ppmv). SAE ARP1256D Page 3 of 194.7 CONTINUOUS SAMPLING The presentation of a flowing sample to a gas analyzer so as to obtain a continuous measurement of concentration of the components of interest. 4.8 FLAME IONIZATION DETECTOR (FID
20、) A hydrogen-air diffusion flame detector that produces a signal nominally proportional to the mass-flow rate of hydrocarbons entering the flame, and generally assumed responsive to the number of carbon ions dissociated from the hydrocarbons entering the flame. 4.9 FUEL/AIR RATIO The mass rate of fu
21、el flow to the engine divided by the mass rate of dry airflow through the engine. 4.10 GAS DIVIDER A certified and traceable device that mixes a calibration gas with a diluent gas in precise fractions to produce a range of gas concentrations with which to demonstrate analyzer linearity. Gas dividers
22、 are commercially available and include gas mixing pumps, capillary and sonic nozzle type devices. Gas dividers are generally more accurate than a range of calibration gases to demonstrate analyzer linearity, and help reduce calibration gas cylinder inventory. 4.11 GASEOUS EMISSIONS The gas phase co
23、mponents in the exhaust stream of an aircraft gas turbine engine that for the purposes of this ARP are restricted to the measured carbon monoxide, carbon dioxide, nitric oxide, nitrogen dioxide and hydrocarbon gases. 4.12 INTERFERENCE Analyzer response due to presence of components other than the ga
24、s (or vapor) that is to be measured. 4.13 LINEARITY The response from an instrument described by the best mathematical straight-line between an instrument zero and full scale, for a given analyzer range.4.14 NOISE Analyzer noise has a frequency of 0.5 Hz or greater, and can be regular or irregular v
25、ariations in instrument output not associated with characteristics of the sample to which the analyzer is responding. Instrument output variations with a frequency less than 0.5 Hz are not considered noise, but shall be accounted for in the analyzer drift and resolution characteristics. 4.15 NOx Oxi
26、des of nitrogen, calculated from the sum of the measured values of nitric oxide (NO) and nitrogen dioxide (NO2).4.16 NONDISPERSIVE INFRARED ANALYZER (NDIR) An analyzer that selectively measures specific components by absorption of infrared energy. 4.17 PARTS PER MILLION (ppmv) The unit volume concen
27、tration of a gas per million unit volumes of the gas mixture of which it is a part. Note also that in the context of the measurements of this procedure, “volume concentration (or volume fraction)” and “molar concentration (or mole fraction)” are synonymous. SAE ARP1256D Page 4 of 19 4.18 PARTS PER M
28、ILLION CARBON (ppmC) The mole fraction of hydrocarbon multiplied by 106. Thus, 1 ppm of methane (CH4) is indicated as 1 ppmC. To convert ppm concentration of any hydrocarbon to an equivalent ppmC value, multiply ppm concentration by the number of carbon atoms per molecule of the gas. For example, 1
29、ppm propane (C3H8) translates as 3 ppmC hydrocarbon 1 ppm hexane (C6H14) as 6 ppmC hydrocarbon. 4.19 PRECISION The closeness of agreement between independent test results obtained under stipulated conditions. For the purposes of this ARP measurements are performed upon a given, invariant sample in s
30、hort-term repetitions of the measurement, with no intervening analyzer adjustment, in the normal working environment of the analyzer. 4.20 RESOLUTION The smallest possible change in output from an analytical instrument that can be produced and detected. 4.21 RESPONSE The change in analyzer reading,
31、digital or analog output that occurs with change in sample concentration. Also, the output signal corresponding to a given sample concentration. 4.22 SAMPLING PROBE The device placed in the engine exhaust plume, used to extract a representative sample. 4.23 SPAN GAS A certified and traceable gas mix
32、ture to be used for routine verification and adjustment of analyzer response. 4.24 SPAN DRIFT The time related change in response of the analyzer in repetition of a span gas measurement determined over a stated period of unattended operation, performed in the normal operating environment of the inst
33、rument, under similar conditions of flow and pressure as that employed on test. The span drift of an analyzer between times 1 and 2, is calculated from (span 2 zero 2) (span 1 zero 1). 4.25 TEST SEQUENCE A series of functionally related conditions in which the test operation without interruption pro
34、gresses systematically from one mode to another. 4.26 HYDROCARBONS The sum of all hydrocarbon compounds of all classes and molecular weights as measured by an instrument incorporating a flame ionization type detector (FID). Hydrocarbons are sometimes referred to as total hydrocarbons (THC) or unburn
35、ed hydrocarbons (UHC). Hydrocarbons are referenced against a propane (C3H8) span gas, but reported as methane (CH4) equivalent. The final hydrocarbon emission index result (see the latest revision of ARP1533) is expressed as CH.where “. ” is the hydrogen to carbon ratio of the fuel, reflecting the c
36、omposition of the hydrocarbons in the exhaust. 4.27 UNCERTAINTY An estimate attached to a test result which characterizes the range of values within which the true value is asserted to lie or a parameter associated with the result of a measurement that characterize the dispersion of the values that
37、could reasonably be attributed to the quantity subjected to measurement. An estimate of uncertainty incorporates what is known about both random and systematic effects on the measurement process, and is probably the most appropiate way of expressing the accuracy of results. SAE ARP1256D Page 5 of 19
38、4.28 ZERO DRIFT Time-related deviation of analyzer output from the zero set point in repetition of a zero gas measurement determined over a stated period of unattended operation, performed in the normal operating environment of the instrument, under similar conditions of flow and pressure as that em
39、ployed on test. 4.29 ZERO GAS A certified and traceable gas used in establishing the zero or null response point of a calibration curve for a given analyzer range. The zero gas is typically high purity nitrogen or air, depending on the type of instrument. 5. EQUIPMENT Precautions: The performance sp
40、ecifications indicated are typical of those analyzers offered by major manufacturers and are generally related to analyzer full scale reading. Error at part scale may be a significantly greater percentage of reading. Typically:errorionSpecificatvaluetmeasuremenRangetmeasuremeninError u (Eq. 1) For e
41、xample, for a measurement at 20% of full scale, the error in measurement may be 5 x specification error (quoted as percent of full scale). The relevance and importance of such increases must be considered when preparing to make measurements. If better performance is necessary, then appropriate preca
42、utions must be taken. The calculation of the gaseous results from the measured concentration data is described in the latest version of ARP1533. This document describes how to apply interference coefficents to the measured data to determine the final results and how to calculate humidity from the me
43、asured dew/frost point temperatures. 5.1 Carbon Monoxide and Carbon Dioxide Analyzers Nondispersive infrared (NDIR) analyzers shall be used for the continuous monitoring of carbon monoxide (CO) and carbon dioxide (CO2) in the turbine exhaust. NDIR analyzers operate on the principle of absorption of
44、infrared radiation in a frequency band specific to the gaseous component of interest within the sample cell. The transmitted radiation is measured by a suitable detector and compared with that received when there is no specific gas component absorption. This differential absorption generates an elec
45、trical signal proportional to the concentration of absorbing gas in the sample cell. This signal is amplified, often linearized, and continuously displayed. 5.1.1 Analyzer Performance Specifications Zero Drift - Less than 1% of full scale in 1 hour. Span Drift - Less than 1% of full scale in 1 hour.
46、 Noise - Less than 1% of full scale. Resolution - Better than 0.5% of full scale. Precision - CO: Better than 1% of full scale for all ranges - CO2:Better than 1% of full scale for all ranges. Linearity - Response shall be linear within 1% of full scale, when instrument output is linearized. Total R
47、ange - Typically CO: 0 to 1000 ppm and CO2: 0 to 10% in appropriate ranges. NOTE: Full scale applies to the range selected for measurement. SAE ARP1256D Page 6 of 195.1.2 NDIR Cells All NDIR analyzers shall be equipped with cells of suitable length to measure concentrations within the required range
48、. 5.1.3 If CO and CO2samples are analyzed “wet, the sample cells shall be maintained at a constant temperature not less than 323 K (50 C, 122 F). An optional water removal device is permitted ahead of the CO and CO2analyzers. If such a device is used, then the sample cells shall be maintained at a c
49、onstant temperature at least 10 K (10 C, 18 F) above the sample dew point. If the sample is dried, a “dry” to “wet” correction of the measured values must be made (see Section 11). The dew point temperature of the sample exiting the drier shall be measured to ensure the following: a. The sample dew point temperature exiting the drier is stable and meets the criteria above. b. The correct dry to wet correction is
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