Technology is all well and good, but if the economics aren’t there, the technology will fail. A DOE funded report titled Distributed Hydrogen Fueling Systems Analysis provides hard numbers comparing various gasoline desulfurization technologies. Couched in the context of the movement toward a hydrogen economy powered by fuel cells, it is somewhat dated … and yet, the problem of commercializing deep desulfurization of gasoline persists.
To quote from the document …
“While gasoline is widely available in the industrialized nations, we expect that a new fuel cell grade of gasoline might be required to support fuel cell vehicles should onboard gasoline processors be developed. Therefore the oil industry might have to make new investments to reduce if not eliminate sulfur or other compounds that might damage or impair the performance of fuel processor or fuel cell catalysts. Another option would be to produce a new fuel such as synthetic gasoline, naphtha, diesel fuel or dimethylether (DME) made from natural gas – the “gas-to-liquids” pathway. These synfuels would contain negligible sulfur, and might also be used as a clean diesel substitute for compression ignition engines. “
The report also is useful for succinct descriptions and comparisons of the various technologies on the market …
“Mobil Octgain 125, Exxon Scanfining, and IFP Prime-G are similar in that they are fixed bed reactor technologies. They differ in approach in that the Octgain 125 process permits saturation of olefins, but recovers octane through isomerization and alkylation reactions within the process reactor, whereas Scanfining and Prime G reduce the severity of temperature and pressure and use catalyst selectivity to minimize octane loss. Where deep desulfurization is required, octane loss would be more extensive with certain of the technologies presented in Figure 31, resulting in higher processing costs than are presented here. The improved Octgain 220 is similar in approach to Octgain 125, but reduces costs by reducing the severity of processing conditions. However, its application is not intended for very high sulfur streams where deep sulfur conversion is required. CD-Tech uses a twin catalytic distillation reactor to proportionate more extensive hydrotreating to the heavier fraction of the FCC naphtha stream. The Black and Veatch adsorption process (IRVAD) uses twin reactor columns with a regenerable alumina adsorbent that is transported circuitously though the adsorber column and the regenerator column. The sulfur heteroatom-containing molecules are scavenged in the adsorber and released in the regenerator in a hydrogen environment. Black and Veatch claim negligible hydrogen consumption with a zero to moderate increase in octane value of the product. It should be noted, however, that the Black and Veatch (IRVAD) adsorption technology produces a ~10,000 ppm S heavy product stream that would also require desulfurization or further processing prior to blending in other product streams. These additional costs were not included, but may be important. In contrast, the Phillips S-Zorb process, which is also a proprietary adsorbent technology, combines desulfurization and adsorption in a single reactor. The adsorbent is regenerated with air and reactivated with hydrogen prior to recycling back to the adsorbing reactor. There is no high sulfur product stream for S-Zorb.
“Mathpro has published two reports estimating the cost of low sulfur gasoline for U.S. refineries in PADDs 1-3. One such study was funded by the American Petroleum Institute (API) estimating the cost of 40 ppm S gasoline based on CDTech and Mobil Octgain 220 used in a notional refinery representing those in PADDs 1-3. (Mathpro-1999a). Their cost estimate for sulfur reduction was 2.25¢/gal for CDTech and 2.6¢/gal for Octgain 220. The EPA reviewed their results adding an incremental cost to achieve 30-ppm standard (2.65¢/gal average) adjusting for 7% ROI before taxes results in 2.2¢/gal. The EPA reviewed several other studies and used the same models to make incremental adjustments for the 30 ppm S standard with updated processing cost numbers and the same capital recovery factors. The studies included the National Petrochemical and Refiners Association (NPRA) funded Mathpro study (Mathpro-1998), the Association of International Automobile Manufacturers (AIAM) funded Mathpro study (Mathpro-1999b), and the Oak Ridge National Laboratories (ORNL) DOE study for mid capacity refinery (Oak Ridge-1999). Finally, Mustang Engineers and Constructors, Inc. published an estimate of ultra low sulfur gasoline (Lamb-2000). The EPAadjusted desulfurization costs are summarized in Tables 21 and 22 below. The fuel costs to the consumer are calculated based on 12,500 miles per year, with the fuel cost present value assuming 7% discount factor for consumer purchasing. “
The report was prepared for DOE in 2001 by Directed Technologies (http://www.directedtechnologies.com/)
View the entire document at: www.ecosoul.org/files/knowledge/downloads/30535bk.pdf
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