Hydrogen content, combustor

Of course, there is no methane at exit from the PO reactor, and no oxygen. The hydrogen content is quite high, over 15% and comparable to that in Lloyd s example of the steam/TCR cycle, but the CO content is also nearly 8%. It is interesting to note that the calculated equilibrium concentrations of these combustible products from the reactor are reduced through the PO turbine (because of the fall in temperature) before they are supplied to the gas turbine combustor where they are fully combusted, but it is more likely that the concentrations would be frozen near the entry values. 

Use of SRC-II distillates in stationary gas combustion turbines is also of significant interest. The low levels of trace metals and inorganics suggest minimal difficulty in regard to turbine blade erosion or corrosion. The higher radiant heat effect on the combustor walls caused by the lower hydrogen content... 

Smoke emissions did depend on fuel properties and ranged between a SAE Smoke Number of 20 to 45 at baseload operation. Indication of increased smoke and liner heating with reduced fuel hydrogen content was observed, although the indicated trends were not as consistent as those for lean combustors. 

The average heat flux coefficient to the primary combustor wall is plotted for the fuels in Figure 9. The results in general displayed a convex character as was observed with NO. 2 fuel. The level of the heat transfer coefficient and its convex trend indicates the importance of radiative heat transfer for these fuels. The maximum value of the coefficient for SCR-II fuel exceeded the maximum for other fuels by 30%. The hydrogen content of SCR-II was less than that for the other fuels tested which apparently resulted in a more intense radiating medium. 

The staged combustor data have been normalized at a primary equivalence ratio of 1.55 for alltest fuels (Figure 16). The fractional increase in heat flux is generally consistent with the lean combustor temperature parameter data presented by Westinghouse ( 3). As with the correlation of the rich-lean smoke data, the heat flux parameter does not display a unique correlation to fuel hydrogen content. 

Primary combustor heat load increased with hydrogen deficient fuels, and maximized near values of heat flux with fuel hydrogen content for the water-cooled, staged combustor was consistent with air-cooled, lean combustor data. 

In order to reduce the oxygen potential of the above gas still further it is necessary to increase the hydrogen content. This can be done by producing an initially richer gas by reducing the air-to-fuel ratio in the combustor and so, after drying and stripping, the gas contains extra H2 and CO. Alternatively, steam may be added to the stripped gas when, on reheating, the reaction H2O + CO = H2 + CO2 occurs over a catalyst. The H2O and CO2 are once more removed as described above. 

The presence of calcium as the oxide, as well as other oxides, in relatively high concentrations in MSW combustor ash makes the ash susceptible to hydration and/or cementation reactions with subsequent swelhng. The presence of elemental aluminum in the ash when combined with water can also result in the formation of hydrogen gas. In addition, the high oxide (salt) content also suggests that ash could be corrosive if placed in contact with metal structures, and that it would likely interfere with curing and strength development if used in Portland cement concrete. 

Subsequently, a meso-scaled combined reformer/catalytic combustor with 10-kW power output was realised by GM/OPEL, which was not presented in detail. For this bigger reactor, the carbon monoxide content of the reformate increased, as expected, with increasing reformer outlet temperature from 0.5% at 250 °C to 2% at 300 °C. Increasing the residence time increased the carbon monoxide concentration of the reformate due to the reverse water-gas shift reaction. Increasing the S/C ratio from 1.2 to 1.8 at a 300 °C reaction temperature increased the hydrogen concentration in the reformate slightly from 72 to 73% and decreased the carbon monoxide content from 1.5 to 1.0%, which originated from the beneficial effect of steam addition on the equilibrium of the water-gas shift reaction. 

---