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Show BURNER P E R F O R M A N C E REQUIREMENTS Fora burner to be of any practical value in today's real industrial world, certain process, mechanical and environmental standards have to be met or exceeded at an economic cost. NOx emissions are only one of many other priority considerations. For example, fired heaters and boilers require burner systems with satisfactory flame patterns and heat transfer profiles, efficient fuel utilization - including the possible use of combustion air preheat, good controllability, low maintenance, high reliability, excellent safety, large capacities, robust construction, minimal noise - particulates - hydrocarbons - CO - SOx and NOx. Fortunately in most cases these requirements are complimentary to good overall burner design. In a few cases, a design or operating feature can be used to cancel out an otherwise detrimental requirement. But in rare cases, an engineering compromise has to be struck based on priorities. DESCRIPTION OF LOW NOx HIGH VELOCITY COMBUSTOR For more than 15 years, a type of combustor has been commercially available using a toroidal vortex internal mixing pattern, two stage air system and high exit velocity flame. It has been applied to industrial air heaters, refinery furnaces and special boilers. Even in its original form, it was an inherently low nitrous oxides producer, but with one or two minor changes, it incorporates all of the desirable NOx depressant design features known at this time without sacrificing or compromising process efficiency. Refer to figure 1 • Liquid fuel at a suitable viscosity is brought to the oil gun under pressure where it is finely divided by compressed gas (usually air) or steam in a compound mechanical/bifluid tip atomizer. If gaseous fuel is used instead of, or in combination with liquid, it is sprayed out of an annular nozzle with similar flow characteristics to the oil gun. The fuel is immediately entrained in an energetic 13/10 |
