Burner Design Factors

In the work reported here the coil and the fire box were simulated simultaneously by means of an optimized computer package in which the design of the radiant section of the furnace is an extension and refinement of Hottel s zone method (3 ). In this paper the approach is applied to the simulation of an industrial ethane cracking furnace. The only adaptable parameter left in the simulation model is a burner design factor, namely the fraction of the heat generated in the burner that is transferred to the burner cup. The parameter is determined by matching the exit conver s ion. 

There are many factors fhaf go info fhe design of a burner. This section briefly considers some of the important factors that are taken into account for a particular type of burner. These factors affecf fhings like... 

There are several aspects of geometry that may be important in industrial combustion testing. One important geometrical factor is the burner design. Burner... 

The usable range of unburnt gas velocities depends on the interaction of several factors. If the velocity is too high, the flame may blow off, or flow within the burner may exceed the Reynolds criterion and become turbulent. If too low, the flame will either flash back, with wide burner tubes, or be extinguished if the tubes are below the extinction diameter. Each factor depends on the burner design, and on the flame composition, but the overall result is not too restrictive, particularly for... 

The size consistency of the coal being dried and the velocity of the gases through the bed are the major factors determining the air pollution potential of the plant. Emissions from dryers in coal-cleaning plants consist mainly of entrained coal fines and VOCs released from the coal, in addition to the standard combustion products [69]. A typical composition of the combustion products emitted from dryers is shown in Table 53.14. Sulfur oxides vary with the sulfur content of the coal, while the other emissions are a function of the burner design and excess air. Total emissions depend on the amount of energy required to dry the coal to the desired level. 

Furthermore factors such as stoichiometric value, heat load and design of the burner as well as the combustion chamber have a significant impact on the emission of pollutant gases. Depending on the reaction of a combustion system to a changing equivalence ratio decisions can be made how to minimize the pollutant emissions by adapting the flow rate of air or gas. A combustion control system based on monitoring the CO fraction in the flue gas could thus be considered. 

Apart from the primary air ratio, the ionization current depends on various other factors, such as differences in heat load, fuel gas composition, voltage supply of the probe, design of the burner, the position of the electrodes and also different temperatures of solids in the combustion chamber. All these disturbing fac-... 

As regards actual combustion of jet fuels, the two critical combustion factors are fuel volatility and hydrogen/carbon ratio. As might be expected, fuels that are too heavy for the spray system and for the combustor design do not burn as well as more volatile fuels. Low hydrogen/carbon ratios also interfere with combustion efficiency, even though straight aromatics have been handled in specially adapted burners (5). 

This program will create a hierarchy of data bases to represent the critical combustion phenomena which have been observed to control combustor operation. These elements will be developed into a base of information which may be used to design and evaluate the thermal efficiency and pollutant output of burners in combination with furnaces and boilers. Existing experimental data and new data to fill existing gaps will be factored into models so that a more complete understanding of combustor operation will result. 

This project will identify the constraints that prevent existing fuel processors from reaching rated capacity in 30 seconds or less. A fundamental technical barrier is the thermal mass of the catalysts and stmctural materials. Reductions in thermal mass require improvements in catalyst materials and effective heat transfer. Other limiting factors are related to auxiliary equipment and process design, such as available gas blowers and burners, the fuel injection system, sensor response, and hot gas distribution within the processor. 

For example, suppose we wish to test a burner using a full factorial design in four factors. However, we only... 

The combustion roar associated with flares typically peaks at a frequency of approximately 63 Hz while combustion roar associated with burners can vary in the 200-500 Hz range. Burner noise can have a spectrum shape and amplitude that can vary with many factors. Several of these factors include the internal shape of the furnace, the design of the burner muffler, plenum and tile, the acoustic properties of the furnace lining, the transmission of the noise into the fuel supply piping, and the transmissive and reflective characteristics of the furnace walls and stack. 

The literature describes a number of proposed ways of dissociating the elements of interest from their chemical bonds, but at present, with very few exceptions, the dissociation is always achieved by burning the sample in a flame. The design of the burner is one of the critical factors of atomic absorption instrumentation, and a great deal of eflFort has been devoted to it. 

The design of the premix burner shown in Figure 10 also presents a number of other advantages and disadvantages as compared with the total consumption type. The flame is not very luminous, and flicker and turbulence are quite low, so that for many elements the flame contributes no apparent noise to the output (Figure 8). Furthermore, there is rather little dependence of absorption upon sample flow rate. This is of benefit in two ways. First, the length of sample capillary, and its depth of immersion in the solution, are not very critical, so that samples can be aspirated from any vessel. For total consumption burners, by contrast, Petri dishes or very small sample containers are often recommended. Second, viscosity interferences caused by variations in sample concentration are minimized, though not eliminated. In the Perkin-Elmer burner, when the sample flow rate is cut by a factor of 2, absorption is reduced by approximately 4%. 

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