Combustors combustion chamber design

The laboratory furnace, illustrated in Figure 1, has been described in detail elsewhere (19). The combustion chamber design is similar to that of Pershing and Wendt (20). It consists of a vertical cylinder 1.0 m long and 0.2 m inside diameter cast from alumina refractory cement. A series of convective heat exchangers, also 1.0 m long and 0.2 m inside diameter, are mounted directly below the combustor. The combustor is fired at a rate of 8 to 12 Kw, providing a residence time of 1 to 2 seconds in the combustion chamber. 

Suppose fuel droplets of various sizes are formed at one end of a combustor and move with the gas through the combustor at a velocity of 30m/s. It is known that the 50-pm droplets completely vaporize in 5 ms. It is desired to vaporize completely each droplet of 100 pm and less before they exit the combustion chamber. What is the minimum length of the combustion chamber allowable in design to achieve this goal ... 

In this study, measurements of the combustion temperature, radiation intensity, combustion products particle size distribution, and combustion efficiency have been made for combustion of aluminum particles with steam in a small-scale atmospheric dump combustor. This data will be useful for designers of combustion chambers for burning of aluminum powder with steam. 

For testing, the Mod 2 burner is housed within a heavily walled pressure vessel which also serves as a plenum chamber for the preheated inlet air supply. See Ref. 16 for a description of the test facility. The burner assembly is shown schematically in Figure 2 and is designed to use 100% of the air flow in the combustion process. Thus, air film cooling and air dilution which are normally used in an engine combustor are omitted. In this way, combustion effects from air injection are avoided for the concept evaluation. The cylindrical combustion chamber is water cooled, as are the sonic exhaust nozzle and gas sample probe. 

The second part of the test rig consists of a combustion air preheater, a specially designed LCV gas burner, a flue gas cooler and a pressure control valve. The LCV gas combustor is situated in a water cooled pressure vessel. This swirl-diffusion combustor has a centric position in the ceramic combustion chamber. From the central symmetry axis of the burner to the outer wall the gas flows are in annular spaces whereby in the inner annulus primary air is added with swirl to the LCV gas and in the outer annulus secondary air is added. 

In addition to APCD, metal emissions from waste combustors can be minimized by 1) limiting the metal content of the waste feed via source control 2) designing and operating the combustion process to minimize metal vaporization and 3) designing and operating the primary combustion chamber to minimize fly-ash carryover. From a practical standpoint, the second method is likely to be the most difficult to implement because the objective of the incineration process is to burn all the combustible waste completely and avoid PIC formation, both of which require the use of high temperatures. Therefore, the most-reliable methods of limiting metal emissions are source control and efficient use of APCD. 

A modification of the pulverised coal plant has a combustion chamber in the form of a cyclone. Molten slag is collected on the walls of the chamber and flows downwards and out of the bottom through a specially designed port. The design is generally known as a "slagging combustor" or "cyclone combustor". 

The pulse combustor is a combustion chamber with no moving parts operating on either gas or fine coal. The chamber and exit tube are designed in a manner which results in a self-sustaining, periodic combnstion process. The frequency of the resonance varies with chamber size and exit tube length. The exit tnbe of the pulse combustor is immersed in the fluidized bed. The raw coal is pneumatically separated with the coal fines carried to the pulse combustor and the coarse coal to the fluidized-bed combustor via a screw feeder. 

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