Processing of Primary Fischer-Tropsch Products - University of Alberta

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7.2.2 LTFT naphtha fuel performance Excluding the SR fuel, all these LTFT naphthas can be regarded as paraffinic. This suggested evaluating them as possible distillates. The Cetane numbers for the HT SR and the SSPD fuels are marginally below typical values found in commercial diesel. As expected, being more isomerised, that of the HX naphtha was even lower. The SR naphtha contains significant levels of both olefins and alcohols that reduced its Cetane number and it was decided not to test this fuel in the Cetane machine. The emissions and specific fuel consumption tests were carried out at the Sasol Oil R&D facilities [77]. A commercial summer grade diesel fuel produced at a South African oil refinery was also tested for comparison purposes under identical conditions. The same standard diesel fuel engine settings were used for all fuels. The results from the engine test are shown in Table 15. It is evident from their composition that these LTFT naphthas that they are far from being compatible with that high octane naphthas usable in gasoline blends. Table 15 Diesel engine and emissions performance of the Sasol SPD naphthas Sasol FT Naphtha SR HT SR HX SSPD Engine Mercedes Benz 407T Test condition 1 400 rpm Load 553 Nm BSFC (Brake Specific Fuel Consumption), g/kWh 216.4 206.2 201.5 CO emissions, g/kWh 0.87 0.79 1.03 CO2 emissions, g/kWh 668.1 676.1 698.9 Hydrocarbon emissions, g/kWh 0.398 0.373 0.445 NOx, emissions g/kWh 13.59 12.55 12.47 Bosch Smoke Number 0.32 0.37 0.31 South African Diesel 206.8 216.8 0.83 1.11 670.1 700.9 0.301 0.138 12.55 16.99 0.37 0.67 7.2.3 LTFT naphtha as a blending component Petroleum refiners producing diesel fuels for cold weather specifications usually change the boiling points of their fuels to improve their cold flow characteristics, making them compatible with low temperature operation. This results in lower production volumes, not only of diesel fuels but also of other light products. The characteristics of the Sasol synthetic naphthas suggested its possible use in blends with diesel fuels suitable for low temperature operation. 525
526 60.0 . . : . . . i i ! i i i . . o . . . ' .... : 9 : : : ; :" : : : : i ,,.o ......... i:::-i ....... ~ '!': : : : :i: : ...... i ......... ! ......... ! ......... i .......... i ........ ! " : : "'$ i i " i o ~ :: ! :: ~,,.. !crve! :: ~ 0.80 40.0 Cetane l~umbe~, i i :: i :: "'- i , , , . . , . , : : : : : : : : i i i ~ ! i i : , , , , , . , 35.0 ; ; ; ; ; ; ; ; 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% Sasol SPD Naphtha-Diesel Blend, % vol. Figure 13 Sasol SPD TM Naphtha-Diesel blend- Cetane number & CFPP 090 ....... i .......... i .......... i ........... ! ........... i ........ i .......... T .......... ,o 70 o.85 ......... i ......... :. .... ::--~-: ........ " ......... .: ......... i ......... -: ......... 4 .......... ~ ........ 60 100% -10 o -2o .~- .,=, -3o _~ ,.=, .,=, -40 N 40 ~ g ~, 0.75 20 0.70 0 0.65 -20 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Sasol SPD Naphtha-Diesel Blend, % vol. Figure 14 Sasol SPD TM Naphtha-Diesel blend- specific Gravity & Flash Point Blends of Sasol SPD TM naphtha with conventional diesels would meet winter grade fuel specifications [77, 87]. The quality of the final product will depend on the fraction of naphtha included in-the blend, as shown in Figs 13 and 14. As an additional benefit, this practice would help maintaining the production volumes of jet fuel. Maximising jet fuel recovery, while maintaining diesel volumes, should translate into better economic results for most oil refineries. All -50 50 10 -10
Page 1 and 2: Studies in Surface Science and Cata
Page 3 and 4: 484 Cold separation .~~"~ Condensat
Page 5 and 6: 486 Chemical production at the Moss
Page 7 and 8: 488 Table 1 Research octane value (
Page 9 and 10: 490 cannot be used with FT products
Page 11 and 12: 492 an attractive refining option f
Page 13 and 14: 494 pose a serious refining problem
Page 15 and 16: 496 offset by the higher capital co
Page 17 and 18: 498 technology that can be used to
Page 19 and 20: 500 includes conventional petroleum
Page 21 and 22: 502 environmental footprint refers
Page 23 and 24: 504 option depending on the scale o
Page 25 and 26: 506 yielding a much higher selectiv
Page 27 and 28: 508 conditions are significantly le
Page 29 and 30: 510 protonated on the acidic cartie
Page 31 and 32: ~ .I Condensat, i ,~ ~l Cond,nsate
Page 33 and 34: 514 product upgrading unit is compa
Page 35 and 36: 516 broad terms, the information re
Page 37 and 38: 518 7.1.1 LTFT diesel as a blending
Page 39 and 40: 520 component e.g. biodiesel and/or
Page 41 and 42: 522 A comparison of the characteris
Page 43: 524 100 -[ ........................
Page 47 and 48: 528 of hydrocarbon products, the pr
Page 49 and 50: 530 [41 ] F.D. Rossini, Chemical th
Page 51: 532 [83] J.A. Tilton, W.M. Smith an

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