Mixing combustor

Liquid fuel is injected through a pressure-atomizing or an air-blast nozzle. This spray is sheared by air streams into laminae and droplets that vaporize and bum. Because the atomization process is so important for subsequent mixing and burning, fuel-injector design is as critical as fuel properties. Figure 5 is a schematic of the processes occurring in a typical combustor. 

Combustors All gas turbine combustors perform the same function They increase the temperature of the high-pressure gas at constant pressure. The gas turbine combustor uses veiy little of its air (10 percent) in the combustion process. The rest of the air is used for cooling and mixing. The air from the compressor must be diffused before it enters the combustor. The velocity leaving the compressor is about 400-500 ft/sec (130-164 m/sec), and the velocity in the combustor must be maintained at about 10-30 ft/sec (3-10 iTi/sec). Even at these low velocities, care must be taken to avoid the flame to be carried downstream. To ensure this, a baffle creates an eddy region that stabi-hzes the flame and produces continuous ignition. The loss of pressure in a combustor is a major problem, since it affecls both the fuel consumption and power output. Total pressure loss is in the range of 2-8 percent this loss is the same as the decrease in compressor efficiency. 

All gas turbine combustors perform the same function, they increase the temperature of the high-pressure gas. The gas turbine combustor uses very little of its air (10%) in the combustion process. The rest of the air is used for cooling and mixing. New combustors are also circulating steam for cooling purpose. The air from the compressor must be diffused before it enters the... 

After combustion, the rich burning mixture leaves the combustion zone and flows between the rows of air jets entering the liner. Each jet entrains air and burning fuel and carries it toward the combustor axis, forming torroidal recirculation patterns around each jet that result in intensive turbulence and mixing throughout the combustor. 

Length. Combustor length must be sufficient to provide for flame stabilization, combustion, and mixing with dilution air. The typical value of the length-to-diameter ratio for liners ranges from three to six. Ratios for casing range from two to four. 

It is necessary to modify the edge of the hole in various ways to reduce these stress concentrations. Some methods of modification are priming, plunging, and standard radiusing and polishing methods. In the Dry Low NOx Combustors, especially in the lean pre-mix chambers, pressure fluctuations can set up very high vibrations, which lead to major failures. 

The reformer feeds and combustor air flow in a counter current manner as shown in Fig. 2. In order to transfer heat to the reformer evenly throughout the interface between reformer and combustor, the combustor is designed to feed the fuel through the holes distributed over the combustor. In this manner, the feed will mix with air incrementally and generate heat throughout the combustor plate evenly. The combustor plate is packed with a Pd catalyst and the reformer uses a Ni/Al203 catalyst. 

In this paper we attempt a preliminary investigation on the feasibility of catalytic combustion of CO/ H2 mixtures over mixed oxide catalysts and a comparison in this respect of perovskite and hexaaluminate type catalysts The catalysts have been characterized and tested in the combustion of CO, H2 and CH4 (as reference fuel). The catalytic tests have been carried out on powder materials and the results have been scaled up by means of a mathematical model of the catalyst section of the Hybrid Combustor. 

Heavy fuel oil feedstock is delivered into the suction of metering-type ram pumps which feed it via a steam preheater into the combustor of a refractory-lined flame reactor. The feedstock must be heated to 200°C in the preheater to ensure efficient atomisation in the combustor. A mixture of oxygen and steam is also fed to the combustor, the oxygen being preheated in a separate steam preheater to 210°C before being mixed with the reactant steam. 

One discouraging problem is the decrease in reactor or combustor performance when a pilot plant is scaled up to a larger commercial plant. These problems can be related to poor gas flow patterns, undesirable solid mixing patterns and physical operating problems (Matsen, 1985). In the synthol CFB reactors constructed in South Africa, first scale-up from the pilot plant increased the gas throughput by a factor of 500. Shingles and McDonald (1988) describe the severe problems initially encountered and their resolution. 

In some scaled up fluidized bed combustors, the lower combustion zone has been divided into two separate subsections, sometimes referred to as a pant leg design, to provide better mixing of fuel and sorbent in a smaller effective cross section and reduce the potential maldistribution problems in the scaled up plant. 

Farrell, P. A., Hydrodynamic Scaling and Solids Mixing in Pressurized Fluidized Bed Combustors, Ph.D. Thesis, Massachusetts Institute of Technology (1996)... 

C3H8 is burned with 10 times the stoichiometric air in a steady flow process. The reaction is complete, forming C02 and H20. The fuel and air are mixed at 400 °C before entering the combustor. The combustor is adiabatic. Specific heats are all constant, cp = 1 J/g. 

The combination of the fuel cell and turbine operates by using the rejected thermal energy and residual fuel from a fuel cell to drive the gas turbine. The fuel cell exhaust gases are mixed and burned, raising the turbine inlet temperature while replacing the conventional combustor of the gas turbine. Use of a recuperator, a metallic gas-to-gas heat exchanger, transfers heat from the gas turbine exhaust to the fuel and air used in the fuel cell. 

Columbus, Ohio incident, 10, 158-159 Combining. See Mixing Combustion with air, screening methods, intentional chemistry, 40-il Combustor, worked examples, 120,122-124, 125... 

Water-reactive materials, screening methods, 47,49-50, 51 Worked examples, 119-134 combustor, 120, 122-124,125 intentional chemistry, 119-120,121 mixing, 128,130-132 oxygen system, 133-134 physical processing, 128,129 repackaging, 124,126-127... 

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