Jet-stirred combustor

The global rates were determined by direct comparison of predictions, using selected sets of rates, with the near adiabatic data obtained from the Exxon Jet-Stirred Combustor (12). The particular set of rate parameters resulting from this process are given... 

Detailed comparisons for near adiabatic combustion of isooctane are shown in Figures 3 and 4. Figure 3 shows temperature and Figure 4 shows CO, CO2, O2 and unburned hydrocarbons as functions of equivalence ratio. The quality of these comparisons is very good and is similar to that obtained for the toluene experiments. Soot was not observed to form in measurable quantities for iso-octane mixtures which could be stably burned in the Jet-Stirred Combustor. 

Although the prediction of N0X emissions under lean and stoichiometric combustion with the extended Zeldovich mechanism is adequate for certain applications, predictive methods for fuels containing bound nitrogen and for rich combustion conditions require substantial improvement. However, the early studies of Fenimore (13, 14) demonstrated the potential importance of HCN and NH type species in fuel-nitrogen interactions. To illustrate the critical importance of the coupling of nitrogenous species reactions in rich combustion, predictions of NO emissions from rich iso-octane combustion in a jet-stirred combustor are shown in Table III. C2 hydrocarbon fragmentation and oxidation creates... 

Quasiglobal kinetics models, which have previously been shown to represent lean and stoichiometric combustion of a variety of hydrocarbon fuels, have been extended to represent lean and rich combustion of toluene and iso-octane. The model predicts the thermal state of the flow and emissions of CO, soot, and N0X. The thermal state of the flow and the stable species were shown to be accurately predicted for jet-stirred combustor experiments. For rich combustion, hydrocarbon intermediates and soot are additional combustion products. The global reactions and rates were developed to represent near-adiabatic jet-stirred combustor data and were then verified by comparison to the near iso-thermal jet-stirred combustor data. N0X emissions behavior was investigated with the quasiglobal kinetics model to represent rich combustion... 

Engleman, V. S. Bartok, W. Longwell, J. P. Edelman, R. B. "Experimental and Theoretical Studies of N0X Formation in a Jet-Stirred Combustor" Fourteenth Symposium (International) on Combustion, 1973, 755-765. 

A Study ot Fuel Nitrogen Conversion in Jet-Stirred Combustors... 

In this paper we report on factors which affect the conversion of fuel nitrogen to TFN in laboratory jet-stirred combustors which serve to simulate the primary zone in a gas turbine. The independent variables in the experiments were fuel type (aliphatic isooctane vs. aromatic toluene), equivalence ratio (fuel-to-oxygen ratio of combustor feed divided by stoichiometric fuel-to-oxygen ratio), average gas residence time in the combustor, and method of fuel injection into the combustor (prevaporized and premixed with air vs. direct liquid spray). Combustion temperature was kept constant at about 1900K in all experiments. Pyridine, C5,H5N, was added to the fuels to provide a fuel-nitrogen concentration of one percent by weight. 

Data from the present set of experiments suggest that the conversion of fuel nitrogen to TFN in jet-stirred combustors depends upon the equivalence ratio and average residence time of gases within the combustor, the fuel type and certain physical characteristics of the combustors. However, the effects of these primary variables on fuel nitrogen conversion appear to be related to their effects on the concentrations of unburned hydrocarbons and soot in the exhaust gases. These effects and their relationships to unburned hydrocarbon and soot concentrations are discussed below. 

As part of the experimental phase of the program, Esso Research and Engineering (2i) is conducting combustion studies under a variety of conditions. The initial work (23) utilized a modification of the Longwell-Weiss reactor (24), termed a jet-stirred combustor (Figure 3). This... 

EPA is presently in the process of extending this work (21) by conducting detailed fiame probing on premixed and difiFusion flames in an axisymetric laboratory furnace burning CO, H2, methane, and propane. The premixed burner and jet-stirred combustor data will be used in conjunction with detailed, finite rate plug flow and well stirred analyses to determine the chemistry of thermal NO, formation during gaseous combustion. 

Gas sparged chemical reactors are designed and used in many different geometries. These reactors are usually continuous in gas, and batch or continuous in liquid. Some of the geometries in use are bubble columns, pipe and static mixer reactors, stirred vessels, packed columns, tray columns, spray columns, jet loop reactors, and venturi ejector reactors. Design equations for each geometry are based on correlations and simpUfying assumptions, such as uniform kLa in the stirred vessel. Other gas-Uquid reactors include spray columns and spray combustors. 

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