Sheldon H. D. Lee

Sulfur removal from diesel fuel-contaminated methanol

Methanol is considered to be a potential on-board fuel for fuel cell-powered vehicles. In current distribution systems for liquid fuels used in the transportation sector, commodity methanol can occasionally become contaminated with the sulfur in diesel fuel or gasoline. This sulfur would poison the catalytic materials used in fuel reformers for fuel cells. We tested the removal of this sulfur by means of ten activated carbons (AC) that are commercially available. Tests were conducted with methanol doped with 1 vol.% grade D-2 diesel fuel containing 0.29% sulfur, which was present essentially as 33-35 wt.% benzothiophenes (BTs) and 65-67 wt.% dibenzothiophenes (DBT). In general, coconut shell-based carbons activated by high-temperature steam were more effective at sulfur removal than coal-based carbons. Equilibrium sorption data showed linear increase in sulfur capture with the increase of sulfur concentration in methanol. Both types of carbons had similar breakthrough characteristics, with the dynamic sorption capacity of each being about one-third of its equilibrium sorption capacity. Results of this study suggest that a fixed-bed sorber of granular AC can be used, such as in refueling stations, for the removal of sulfur in diesel fuel-contaminated methanol.

Alkali-vapor emission from PFBC of Illinois coals

Abstract Two Illinois Herrin No. 6 coals and one Illinois Springfield No. 5 coal were combusted in a laboratory-scale PFBC/alkali sorber facility with a bed of Tymochtee dolomite at temperatures ranging from 910 to 950°C and a system pressure of 9.2alm absolute. Alkali vapor emission )Na and K( from combustion was determined by analytical activated-bauxite sorber bed technique. The test results showed that sodium is the major alkali-vapor species present in the PFBC flue gas of these coals and that there is a positive linear relationship between the level or sodium-vapor emission with both Na and CI contents in the coals. This suggests that the sodium-vapor emission from these coals is a result of direct vaporization of NaCI present in the coals. The measured alkali-vapor concentration )Na + K( ranges 67 to 90 ppbW and is more than 2.5 times greater than the allowable alkali limit of 24ppb for an industrial gas turbine. It is concluded that utilizing these coals in the PFBC for power generation may requir...

Partial oxidation reformer development for fuel cell vehicles

A bench-scale partial oxidation reformer that is compact (1.8 L) and light-weight has been demonstrated with methanol fuel. The hydrogen output from the reactor had a lower heating value of 12 kW. The gas contained over 50% hydrogen and less than 1% carbon monoxide. A novel class of catalyst materials has been identified which is able to convert various hydrocarbons, including gasoline, to a hydrogen-rich product gas. Tested in a micro-reactor with gasoline and oxygen at 760/spl deg/C, these catalysts yielded a product gas containing over 60% hydrogen.

Removal of Alkali Vapors by a Fixed Granular-Bed Sorber Using Activated Bauxite as a Sorbent

Studies have been conducted to develop a fixed granular-bed sorber for the removal of alkali vapors in a pressurized fluidized-bed combustion (PFBC) combined-cycle system. A laboratory-scale pressurized alkali-vapor sorption test unit was used to characterize activated bauxite, the most effective sorbent identified earlier, for its alkali vapor sorption capability in a gas stream with temperature (≤900°C), pressure (10 atm absolute), and composition closely simulating the actual PFBC flue gas. A scale-up of laboratory tests is being conducted in a 15.2-cm-dia (6-in.-dia) PFBC system to demonstrate the granular-bed sorber concept. The NaCl-vapor sorption chemistry of activated bauxite is described. The extent of alkali-vapor evolution from the activated bauxite bed itself is discussed, along with an evaluation of the significance of its alkali vapor contribution to a downstream gas turbine. Details of the design of a high-temperature/high-pressure alkali sorber system for the demonstration of the sorber are presented.Copyright