Combustors pressure drop

Establishing a criterion for blowoff during opposed-jet stabilization is difficult owing to the sensitivity of the recirculation region formed to its stoichiometry. This stoichiometry is well defined only if the main stream and opposed jet compositions are the same. Since the combustor pressure drop is of the same order as that found with bluff bodies [76], the utility of this means of stabilization is questionable. 

Twin-Fluid Air-Blast Atomizer. Twin-fluid atomizers can be divided into internal and external mixing systems. Atomization occurs by passing a high-velocity gas stream over a liquid sheet or by mixing in the form of a Y jet. The gas stream is usually air although steam has been used to improve the injection characteristics of heavy viscous fuels. The air stream is usually derived from the main air flow to the combustor, thus utihzing a portion of the combustor pressure drop. 

The combustor is designed to operate at a pressure of 600 kPa (6 atm) with 1867 K preheated air. First stage heat loss of the 250 MW combustor is about 4.3% and the total heat loss is about 6%. The relative pressure drop is 3%. More complete discussions of the design and scale-up of the combustor are available (75). 

High-pressure loss in a gas turbine combustor would result in excess specific fuel consumption and thus should be avoided. When (j> = 0.237 and p = 8 ppcm, the porous layers created an additional pressure drop of about 150 Pa for one 2.5-centimeter-thick porous layer and about 300 Pa for a 5.1-centimeter-thick foam. The loss of efficiency due to the pressure drop is estimated as 0.086% for 2.50-centimeter-thick insert and 0.17% for 5.1-centimeter-thick insert. 

A sooting flame with high CO and UHC emissions was observed for the baseline case without a porous insert in the combustor. With the inserts in place, NOj emission was reduced, but little change was found for CO and UHC emissions. During the experiments with one porous layer placed at L/D = 1.1 the pressure drop through the insert increased slowly to about 800 Pa gas temperatures decreased by up to 600 K downstream of the inserts. 

The operation of this pilot plant combustor is similar to that of the Type B fast fluidized bed in Chapter 3, Section II. Figure 16 (Li et al, 1991) shows the axial profiles of bed voidage for different gas velocities and total pressure drops across the fast fluidized combustor, demonstrating the... 

To avoid high-pressure drop and clogging problems in randomly packed micro-structured reactors, multichannel reactors with catalytically active walls were proposed. The main problem is how to deposit a uniform catalyst layer in the microchannels. The thickness and porosity of the catalyst layer should also be enough to guarantee an adequate surface area. It is also possible to use methods of in situ growth of an oxide layer (e.g., by anodic oxidation of a metal substrate [169]) to form a washcoat of sufficient thickness to deposit an active component (metal particles). Suzuki et al. [170] have used this method to prepare Pt supported on nanoporous alumina obtained by anodic oxidation and integrate it into a microcatalytic combustor. Zeolite-coated microchannel reactors could be also prepared and they demonstrate higher productivity per mass of catalyst than conventional packed beds [171]. Also, a MSR where the microchannels are coated by a carbon layer, could be prepared [172]. 

Catalysts in thin-wall honeycomb form offer the advantages of low pressure drop, high geometric surface area, and short diffusion distance as compared to conventional pellets and beads in fixed bed reactors (1). Active zeolite catalysts may be extruded in the form of a honeycomb structure or they may be washcoated on ceramic honeycomb substrates. The latter technique has been widely used in automotive emissions control (2), woodstove combustors (3), control of volatile organic emissions from organic solvents (4), ozone abatement in jet aircraft passenger cabins (5), and N0x abatement... 

The research was conducted in a cold-flow combustor test rig simulating the exact geometry of the hot combustion rig. This test rig (Fig. 10.1) is set up vertically. The air is introduced at the bottom and is conditioned through an air conditioning section which is composed of perforated cone, screens, and honeycomb is settled in 3.8-inch diameter circular chamber is fed into TARS and then exits to the atmosphere. The pressure drop across TARS is 4%. The TARS features three separate airflow passages and independent liquid fuel supply lines that can be controlled separately (Fig. 10.2). 

Edwards What is the pressure drop associated with a porous matrix inserted in the realistic combustor ... 

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