Fuel rich sulfur capture

The objective of this research was to determine the parameters important to high temperature sulfidation of calcium oxide under realistic fuel rich combustion conditions and determine the fate of this fuel rich sulfur capture when the sorbent entered a fuel lean zone. The experiments were conducted in a refractory lined, natural gas furnace operated fuel rich in the top portion and fuel lean in the bottom portion. Gas phase fuel rich and fuel lean sulfur capture measurements were made simultaneously as a function of rich sulfur concentration (500 to 3000 ppm), molar Ca/S ratio (1 to 4), fuel rich stoichiometric ratio (SR = 0.65 and 0.75), sorbent injection temperature (1120 to 1045 {dollar}spcirc{dollar}C), quench rate (250 to 500 {dollar}spcirc{dollar}C/sec), residence time (0.30 to 0.65 sec), and sorbent type (Marblehead hydrate and Fredonia carbonate and their respective precalcines). The fuel rich sulfur species H{dollar}sb2{dollar}S and COS were analyzed at 30 second intervals by a gas chromatograph equipped with a flame photometric detector (GC-FPD) and an automatic sampling system. Fuel lean SO{dollar}sb2{dollar} was monitored continuously with an ultraviolet analyzer.; Calcium utilization in the fuel rich zone demonstrated a strong positive dependence on sulfur concentration and a negative dependence on Ca/S. The raw hydrate out performed the raw carbonate and high levels of rich capture were reduced in the lean zone.; Analysis of the data obtained with the sized 3-10 {dollar}mu{dollar}m precalcined sorbents showed the same strong dependence on sulfur concentration and Ca/S but with both precalcines, the high capture obtained in the rich zone was retained in the lean zone. Calcination conditions in the fuel rich zone may influence the retention of sulfur capture in the fuel lean zone. The carbonate derived precalcine (c-CaO) and the hydrate derived precalcine (h-CaO) were comparable in sulfur capture ability but N{dollar}sb2{dollar} porosimetry measurements made on sulfided solids samples taken from the furnace revealed that the pore size distribution (PSD) of c-CaO did not change with conversion while the PSD of h-CaO showed the expected decrease in pore volume.; A distributed pore model was extended to handle quenched temperature profiles, reversible reactions and a special case of constant PSD. For h-CaO, the model accurately predicts the dependence of H{dollar}sb2{dollar}S concentration and Ca/S as well as the PSD development. Good agreement was also achieved for the c-CaO using the constant PSD case.