Primary combustor equivalence ratio

One operating concern for a rich combustor is the occurrence of high combustor wall temperatures. In a fuel-rich combustor, air cannot be used to film-cool the walls and other techniques (e.g., fin cooling) must be employed. The temperature rise of the primary combustor coolant was measured and normalized to form a heat flux coefficient which included both convective and radiative heat loads. Figure 7 displays the dependence of this heat flux coefficient on primary combustor equivalence ratio. These data were acquired in tests in which the combustor airflow was kept constant. If convective heat transfer were the dominant mechanism a constant heat flux coefficient of approximately 25 Btu/ft -hr-deg F would be expected. The higher values of heat flux and its convex character indicate that radiative heat transfer was an important mechanism. 

NO Dependence on Primary Combustor Equivalence Ratio for No. 2 Petroleum Distillate Fuel... 

Again the maximum is observed at primary combustor equivalence ratios close to that desired for minimum N0X emission operation. 

N0X Emissions. The nitrogen content in the distillate fuels ranged from 0.0 to 0.75 wt%. The influence of this range on N0X emissions is displayed in Figure 11. The values plotted correspond to the minimal N0X level for each fuel. Since the minima occurred over a small range of primary combustor equivalence ratio (1.5 << >p <1.57) these data also represent operation at constant combustor conditions. As can be observed, the N0X emissions were independent of fuel nitrogen. An... 

With torroidal air flow, combustors will operate without visible smoke when properly developed for a primary-zone equivalence ratio below 1.5. Visible smoke is an air-pollution problem. 

The resulting overall energy balance for the plant at nominal load conditions is shown in Table 3. The primary combustor operates at 760 kPa (7.5 atm) pressure the equivalence ratio is 0.9 the heat loss is about 3.5%. The channel operates in the subsonic mode, in a peak magnetic field of 6 T. AH critical electrical and gas dynamic operating parameters of the channel are within prescribed constraints the magnetic field and electrical loading are tailored to limit the maximum axial electrical field to 2 kV/m, the transverse current density to 0.9 A/cm , and the Hall parameter to 4. The diffuser pressure recovery factor is 0.6. 

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. 

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. 

The first of these approaches uses controlled air addition to provide a fuel rich primary zone followed by fuel lean intermediate and dilution zones within the gas turbine combustor. The fuel rich primary zone, with an equivalence ratio of about 1,4, promotes the conversion of the ammonia contained in the fuel to nitrogen rather than to NO, The intermediate zone conqiletes the combustion of the fuel to achieve low CO emissions at an equivalence ratio near unity, whilst the dilution zone provides the correct temperature profile to suit the inlet to the gas turbine. The primary zone of the combustor is fully iti ingement cooled. This ensures that the local equivalence ratio... 

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