1、BSI Standards Publication PD CEN/TR 16885:2015 Liquid petroleum products Investigation on test method for measurement of the oxidation stability of diesel and diesel/FAME blends by Acid Number after ageingPD CEN/TR 16885:2015 PUBLISHED DOCUMENT National foreword This Published Document is the UK imp
2、lementation of CEN/TR 16885:2015. The UK participation in its preparation was entrusted to Technical Committee PTI/13, Petroleum Testing and Terminology. A list of organizations represented on this committee can be obtained on request to its secretary. This publication does not purport to include al
3、l the necessary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2015. Published by BSI Standards Limited 2015 ISBN 978 0 580 90120 1 ICS 75.160.20 Compliance with a British Standard cannot confer immunity from legal obligations. This Pub
4、lished Document was published under the authority of the Standards Policy and Strategy Committee on 30 September 2015. Amendments issued since publication Date Text affectedPD CEN/TR 16885:2015TECHNICAL REPORT RAPPORT TECHNIQUE TECHNISCHER BERICHT CEN/TR 16885 September 2015 ICS 75.160.20 English Ve
5、rsion Liquid petroleum products - Investigation on test method for measurement of the oxidation stability of diesel and diesel/FAME blends by Acid Number after ageing Produits ptroliers liquides - Recherche de la dtermination de la stabilit loxydation du gazole et des mlanges gazole/EMAG par lindice
6、 dacide aprs vieillissement Flssige Minerall-Erzeugnisse - Bericht ber die Bestimmung der Oxidationsstabilitt von Diesel und Diesel/FAME-Mischungen durch Bestimmung der Surezahl nach Verlterung This Technical Report was approved by CEN on 17 August 2015. It has been drawn up by the Technical Committ
7、ee CEN/TC 19. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands,
8、Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels 2015 CEN All rights of e
9、xploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. CEN/TR 16885:2015 EPD CEN/TR 16885:2015 CEN/TR 16885:2015 (E) 2 Contents Page European foreword 3 1 Scope . 4 2 Context and creation of a dedicated subgroup 4 3 Participants in the work 5 4 Meetings of the
10、 subgroup Acid No.“ . 5 5 Main steps of the work item study . 6 5.1 Creation of the NWI . 6 5.2 Test method used . 6 5.3 First Round Robin Test 7 5.4 Improvement of the test method 7 5.5 Pass/fail methodology 8 5.6 Second Round Robin Test . 9 6 Conclusions . 11 7 Acid number determination method ava
11、ilable for lab use 11 8 Acknowledgements 11 Annex A (informative) Test method transcription 12 Annex B (normative) Round Robin Results 20 B.1 October 2010 results . 20 B.2 2012/2013 RRT . 22 Annex C (normative) Pass-/Fail discriminant analysis 25 Bibliography 31 PD CEN/TR 16885:2015 CEN/TR 16885:201
12、5 (E) 3 European foreword This document (CEN/TR 16885:2015) has been prepared by Technical Committee CEN/TC 19 “Gaseous and liquid fuels, lubricants and related products of petroleum, synthetic and biological origin”, the secretariat of which is held by NEN. Attention is drawn to the possibility tha
13、t some of the elements of this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. PD CEN/TR 16885:2015 CEN/TR 16885:2015 (E) 4 1 Scope This Technical Report describes the investigation into the development of
14、a standard test method to determine oxidation stability of diesel fuel and fatty acid methyl ester (FAME) blends in diesel by the use of determining the acid number after ageing at elevated temperature. It provides conclusions following this work that have been discussed by CEN. The result thereof i
15、s that no European Standard has been developed. 2 Context and creation of a dedicated subgroup In case of poor diesel or biodiesel quality, ageing of the fuel in the fuel system under high pressure and temperature (recirculation of fuel, high injector temperature, long storage in the vehicle fuel ta
16、nk) may cause various car problems due to the formation of acidity through oxidation (i.e. deposit of sediments, deposit of lacquer, corrosion, lube oil deterioration). Acidity of the fuel is therefore considered as a relevant parameter to evaluate oxidation stability of the Diesel fuel. Test method
17、s based on the measurement of the acid number (AN) after an ageing step were studied. An ageing test temperature of 115 C which is significantly higher than the test temperature of 95 C applied in EN ISO 12205 1 has been chosen because it better discriminates fuels oxidation stability. Additionally,
18、 it is closer to the temperature range prevailing in fuel systems of current and future engine technologies (i.e. common rail systems). Customer complaints related to fuel degradation linked to oxidation stability in France are shown in Figure 1. Figure 1 Customer complaints linked to fuel degradati
19、on in France PD CEN/TR 16885:2015 CEN/TR 16885:2015 (E) 5 A test method based on the change of the acid no. of a fuel during ageing, Delta AN, was evaluated in CEN/TC 19/JWG1 FAME Test methods in 2008. In the Delta AN method, the fuel is aged at 115 C for 16 h by passing a stream of oxygen through t
20、he fuel using the oxidation cell of EN ISO 12205. The acid number of the fuel before ageing is subtracted from the acid number of the aged fuel. The results of Round Robin tests made on the Delta AN method led to the conclusion that the Delta AN test method, although discriminative, exhibits a preci
21、sion not enough robust ; this test method needed some analytical improvements. A draft report about the test results applying the Delta AN method performed in 2008 was presented to CEN/TC 19/JWG1 in January, 2011. Further work concerning the improvement of the Delta AN test method was carried out in
22、 France in 2009. A new test method based on the measurement of the acid number of the fuel after ageing was developed. Based on the results of a cross check test, it was decided at the JWG1 meeting on September 4, 2009, that additional work would be necessary concerning the robustness and precision
23、of the new method. As such work being not covered by the CEN/TC 19 mandate to JWG1, it was proposed that experts continue the improvement work and issue a proposal for a NWI to WG 24. Based on the results of the work of the French experts the continuation of the work was accepted by WG24 in March 20
24、10. JWG1 started the work, creating a dedicated subgroup for this preliminary new work item (PNWI). 3 Participants in the work Several European experts were active within this project, represented by one or more member(s) participating in the meetings. The memberships are listed in Table 1. Table 1
25、Members of the Subgroup Acid No.“ Company Country Members PSA France P. Jestin TOTAL France S. Duperrier; P. Manuelli; P. Pestiaux; A. Vincent; A. Gandubert SHELL Germany M. Schmidt Deutsche BP Germany W. Strojek Neste Oil Finland M. Kuronen IFPEN France L. Pidol OMV Austria W. Koliander ADM Germany
26、 J. Groos; J. Fischer ASG Germany T. Wilharm Metrohm Switzerland C. Haider; U. Loyall SGS Germany, France M. Kulikowski; D. Juillet 4 Meetings of the subgroup Acid No.“ The members of the group have been working on the assessment of the oxidation stability of diesel and diesel/FAME blends by determi
27、nation of the acid value after ageing from beginning of 2010 to mid-2014. The meetings are listed in Table 2. This work have been reported and discussed within JWG1 at each session. The main orientations and action plans have systematically been validated by JWG1. PD CEN/TR 16885:2015 CEN/TR 16885:2
28、015 (E) 6 Table 2 Meetings of the Subgroup Acid No.“ Meeting Date and location Meeting 1 April 27, 2010 Conference call Meeting 2 July 07, 2010 Meeting 3 January 14, 2011 Meeting 4 May 24, 2011 PSA Peugeot Citron Paris Call conference July 25, 2011 Conference call Meeting 5 September 02, 2011 IFPEN
29、Rueil Meeting 6 March 22, 2012 PSA Peugeot Citron La Garenne Colombes Meeting 7 November 13, 2013 TOTAL Paris La Dfense 5 Main steps of the work item study 5.1 Creation of the NWI The first meeting of the group took place in April, 2010. The scope was presented to the members: the objective was to i
30、mprove the precision of the new acid number test method applicable to diesel fuels from B0 to B10. In that context, some adjustments were made on the test method protocol and it was decided to run first a cross-check test. Necessary improvements based on the outcome of the study should be implemente
31、d to the method. A Round Robin test should finally be conducted in order to develop the precision of the method. 5.2 Test method used The method used has been developed to be applicable to diesel fuels from B0 to B10. The main analytical parameters are listed hereafter and the full description of th
32、e test method is given in Annex A. Sample amount: (10 0,2) g; Heating bath temperature: (115 0,2) C 1 ; Oxygen rate: (1 0,1) L/h; Running time for fuel oxidation: 16 h 5 min; Maximal time between the end of oxidation step and the AN measurement: 4 h. 1The fuel was aged either in an oil bath or an he
33、ating bath as applied in the Rancimat equipment PD CEN/TR 16885:2015 CEN/TR 16885:2015 (E) 7 5.3 First Round Robin Test A RT was run in October, 2010 to assess the precision of the proposed new AN method on both colorimetric and potentiometric determination of the AN. Nine samples were used for the
34、RRT: 3 B0, 4 B7 and 2 B10. Samples were representative for the European Market, some containing cetane improver (content between 100 and 1000 ppm), CFPP additives and/or lubricity additives. Thirteen labs out of fourteen participants have returned their results on time: ten labs have performed color
35、imetric determination (oil bath and Rancimat bath according to EN 15751 2 ) and eleven labs have performed potentiometric determination (oil bath and Rancimat bath according to EN 15751). The results of this RRT are given in Annex B. The RRT results led to the following comments: Even if there was a
36、 discrimination between “good” and “bad” products, results were worse than expected, in particular for the potentiometric version. When the dispersion of results with the potentiometric method was discussed, all participants agreed that experimental parameters were perhaps not optimized and that it
37、was necessary to work on it (electrode system, solvent, dynamic titration, etc.). “Home-made” diesels, meaning diesels formulated by blending “good” and “bad” B0 or B7 in order to reach certain AN target, seemed to have a strange behaviour. Even if the formulated products seemed to be homogeneous, t
38、he results obtained by the labs were really different and the statistical distribution of results indicated strong issues. There were some difficulties of being more precise on very good samples (AN 0,1 mg KOH/g). For non acidic samples, the resulting precision is poor due to the precision of colori
39、metric titration (in test method ISO 6618 3 the reproducibility is 0,04 mg KOH/g for samples with AN 0,1 mg KOH/g). No impact of Rancimat bath compared to oil bath was observed, no bias was observed. Thus this RRT pointed out that the method could not be used in the current state to be submitted for
40、 standardization. It was decided to continue the work to understand potentiometric results, to identify what could have an influence on the results dispersion and thus improving the method (work on experimental parameters, propose a few tests to assess the new parameters, ). In parallel, the group m
41、embers have decided to ask CEN/TC 19/WG 36 (statisticians) how a pass/fail test could be established, as this method could be considered as such. All the details about this RRT are available in the internal document “Round Robin Study Report 2010-831” of CEN/TC 19. 5.4 Improvement of the test method
42、 In order to improve the potentiometric titration test method, the participants of the first RRT were asked for detailed information of settings and conditions of their instruments. While there was no significant difference on the equipment (brand of device, software, electrode system, analytical pa
43、rameters), the way of detection of the equivalent point was not the same for all participants. Indeed, the determination of the equivalent point can be automatically or manually done and some labs used the point corresponding to the pH 11 aqueous buffer. In parallel, several tests were performed by
44、TOTAL to estimate the impact of various analytical parameters. Based on these results, some improvements were found to optimize the titration step: a) Set all titration program parameters as proposed; b) Use the colorimetric solvent and add indicator solution (to follow the solution colour change, e
45、specially for blank titration); c) Perform a manual (re)check on equivalent point for each titration; d) Do NOT use the point corresponding to the pH 11 aqueous buffer (to define the KOH sample volume). PD CEN/TR 16885:2015 CEN/TR 16885:2015 (E) 8 At that stage of the study, the group decided organi
46、zing a new RRT with a well-defined measurement parameters for this RRT in order to minimize the variations from one lab to another. Nevertheless, all the experts agreed on the fact that the critical part of the test lies in the ageing step more than in the acid number determination. 5.5 Pass/fail me
47、thodology The results obtained during the first RRT showed that it would be very difficult to propose a method with “classical” precision according to EN ISO 4259 4 (r and R versus acid number). Indeed, the acid numbers measured on the RRT samples were not evenly distributed. The AN were either low
48、or high and the samples formed two separate populations that can be considered as “good” samples and “bad” samples. By consequence, the members of the Subgroup proposed to use the preliminary tests on 44 B0 to B10 samples, conducted in August 2011, for the development of a Pass/Fail method. This mod
49、el, developed in close cooperation with WG 36 experts, is based on General Discriminant Analysis (GDA). GDA applies the methods of the general linear model to the discriminant function analysis problem. It is a strong tool for detecting the variables that allow to discriminate between different groups, and for classifying samples into different groups with an accuracy better than chance. In the two-group case, discriminant function analysis can be thought of as a special kind of multiple regression. If w
