ASTM: Gasoline Today and Tomorrow – An Executive Report

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Octane Week | ASTM: Gasoline Today and Tomorrow - An Executive Report (from p15) in ASTM and thus their greater voting power, Subcommittee D02.A leaders wisely garnered support around a 4 ppm spec and brought the issue to closure last week. “Weʼve got a number, 4 ppm, and we have test methods. Thatʼs a great accomplishment,” said Ben Bonazza, D02 Committee chairman. Refining and auto groups will now try to move the specification limit lower. Most of the ethanol that is produced and marketed in the U.S. can easily meet the 4 ppm spec, our source told us. It is only the occasional batch of domestic ethanol and some imported material than can have trouble meeting the new specification. Will the spec move lower? Maybe, but not now. “The current specification is a triumph of testing and compromise, and deserves support”, our source continued. “But anything that will reduce the levels of impurities in refining fuel feedstocks is good. And ethanol producers are doing the right thing. They are working with refiners to facilitate the use of their product.” – Carol Cole Busy ASTM Agenda Includes Debates On DI, Ethanol Sulfates From the June 13, 2005 edition. ASTM members gathering in Pittsburgh, Pa., in June 2005 will be facing an agenda full of gasoline quality issues, some familiar, some new. The D02 Committee on Petroleum Products will investigate particulate contamination in gasoline and diesel to determine whether a retail spec should be set. Committee members also will delve into the issue of ethanol sulfate content, now that individual refiners are setting their own specs to control sulfates. Ethanol is creeping into ASTM discussions more frequently. As the fuels industry prepares for a possible renewable fuels standard, which will mandate substantially more ethanol use, questions about the additiveʼs quality and blending traits become increasingly important. Some ASTM members are concerned that the ASTM Subcommittee Wrestles With DI Change; Retail Spec Proposed existing Distillation Index (DI) equation needs an ethanol term. The current T10, T50 and T90 terms do not adequately reflect a blendʼs distillation when ethanol is present, they say. CRC test results will be evaluated in an effort to determine whether an ethanol term is needed. Committee members also will return to more familiar territory, such as whether to apply the test DI at the retail level rather than at the refinery, where it is currently applied. DI is the only ASTM specification that is not applied at retail. Silver corrosion is also on the ASTM agenda. The emergency test method that was adopted last year will be reviewed, and members will evaluate whether more round robin testing is needed before a permanent test method is selected. – Carol Cole Coverage of the ASTM Subcommittee meeting appeared in the July 5, 2005 issue. Adding an ethanol term to the ASTM Driveability Index (DI) equation will more accurately reflect the effect of ethanol on gasoline cold-start and warm-up driveability, supporters of the change said. An ethanol term is not needed and will make gasoline more costly to produce, opponents countered. This controversial issue was to be “balloted” to determine whether members of ASTMʼs D- 02.A gasoline subcommittee support the change. ASTM considered adding an ethanol term to DI for years, and various offsets had been discussed. The Coordinating Research Council (CRC) has participated in the effort to quantify the impact of ethanol on fuels and vehicle operation. Early CRC studies showed that equal DI, ethanol blends generally have been shown not to perform as well. The latest CRC research indicated an offset for ethanol was needed in the DI equation, said Driveability Task Group Chairman Win Gardner of ExxonMobil. “CRC data supports the addition (continued on p17) 16 February 2007
Octane Week | ASTM: Gasoline Today and Tomorrow - An Executive Report (from p16) of an offset,” he told ASTM members meeting in Pittsburgh. “The DI change addresses a technical issue that arose out of CRC studies. The secondary aspect, to have it apply at retail, grew out of state positions in the past.” The most recent CRC study, completed in 2004, was “probably the best cold-start driveability program run,” said Task Group member Lew Gibbs of Chevron. Vehicles were screened for responsiveness, raters were trained and calibrated and procedural changes were made to the program. “The result showed a high degree of statistical correlation between driveability and an adjusted DI index.” In contrast, previous CRC tests included older cars and a larger ethanol offset, Gibbs explained. “The latest test had the best representation of modern vehicles on the road,” he told Octane Week. After meeting in Naperville, Ill., to discuss the results, Task Group members determined to propose balloting a DI change to the entire group. Specific Proposal Language The proposal to be balloted was as follows: Change Table 1, footnote C, to read “Driveability Index (DI) = 1.5 T10 + 3.0 T50 + 1.0 T90 + 1.33 o C (2.4 o F) * Ethanol Volume% where T10 = distillation temperature, o C ( o F) at 10% evaporated, T50 = distillation temperature, o C ( o F) at 50% evaporated, and T90 = distillation temperature, o C ( o F) at 90% evaporated.” Change footnote D with the following: “During spring and fall transitions into and out of the federal vapor pressure control period, the Driveability Index requirement of the volatility class specified in Table 4 is waived so long as the DI meets that of the volatility class corresponding to the measured vapor pressure of the retail sample.” Refiners might have to tighten the base fuel properties in order to accommodate DI with an ethanol offset. A 2.4ºF *10 vol% translates to a 24-point more stringent spec. Task Group members expressed concern about the impact on conventional gasoline. At that time, refiners did not know whether ethanol would be added to CG downstream of the refinery, which would create a noncomplying blend. But as Gibbs pointed out, when ethanol is added at 10 vol%, it lowers the 10% and 50% evaporated points, which in turn, lowers DI about 60 points, on average. The ethanol adjustment for 10 vol% is only about 24 points. Since the upward adjustment is smaller than the downward blending effect, the blends will always be in compliance, he said. A 24-point more stringent spec will mean additional manufacturing costs for refiners, one fuels industry representative said. “This is going to cost more to produce,” said Bob Schaefer of BP. The DI change is coming at a time when refineries are running at maximum, Schaefer pointed out. In the future, refiners will have to make additional amounts of low-Rvp fuels due to the implementation of the U.S. EPAʼs 8-hour ozone standard. That will probably lead to fuel quality changes. “States will need emissions reductions, and fuels will be on the list.” Schaefer observed that the latest CRC study utilized a fuel set of 10 fuels, eight of which had a DI in excess of the current ASTM maximum of 1250. “The majority of the fuel set contains fuels that are non-compliant,” he noted. A correlation was developed between the effect observed on high-DI fuels and applied to the on-spec fuels. CRCʼs research was “good science” Schaefer said, “but the application of the correlation would not be good science.” Testing a broad range of fuels is common at CRC. Two of the test fuels had DIs below the 1250 maximum and four were around 1265, Chevronʼs Gibbs countered. Previous tests included fuels with DI as low as 1160, and they showed an offset for ethanol was needed. “We expanded the envelope to get a scale so you can see an effect. Thatʼs common practice and accepted good science. “The relationship between the adjusted DI and driveability demerits was linear on a log basis, indicating applicability at lower DI levels,” Gibbs said. “Members of the auto, oil and ethanol industry all agree that this offset has applicability.” (continued on p18) February 2007 17
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