Burners adjustable heat-release

Field tests were performed in a full-scale ethylene cracking furnace comprised of multiple floor and wall burners operating at a total heat release of approximately 68.9 MW (235 x 10 Btu/hr). The setup allowed for a sample probe to be inserted at various locations through site ports within the furnace radiant section and crossover section located just before the convection section. The probe length was approximately 3 m (10 ft) long and could be adjusted to various depths within the furnace. The flue gas sample was pulled through a heat traced Teflon tube to a remotely located CEM. 

With an ATP-type burner, the heat release pattern of the flame can be automatically adjusted by the difference in temperatures sensed at two points in the furnace. One of those temperatures also can limit energy inputs so that both ends of the load(s) will be controlled to raise or lower their temperatures together. If ATP-type burners cannot be fitted to spaces that are too narrow, other means (discussed later) must be used to avoid load temperature nonuniformities. This is usually done by designing for no more than a 30°F (16°C) poc temperature drop as the gases pass from one end of the load to the other. 

Using many small burners to utilize the whole wall area is a way to achieve good temperature uniformity. (See figs. 3.4 and 3.5, and sec. 7.4.) There are large burners that can hold the burner wall as hot as the point of conventional maximum heat release. These adjustable thermal profile burners (fig. 6.1) can automatically hold a desired temperature profile by controlling the spin of the products of combustion. Optimum use of furnace space and overall refractory wall radiation usually favors the hottest possible burner wall (maximum flame spin, minimum flame length). In... 

Burners should be about 2.5 ft (0.87 m) apart, above and below the strip. The burners above the strip should be on one side of the furnace and those below the strip on the other side, enhancing circulation velocity. The burners should have a near-flat heat-release pattern (preferably adjustable), providing a temperature profile across the furnace that is practically level. It is important to check the design and the actual operation to make sure that no bottom-row-burner flames impinge on the lowest part of the strip s catenary loop. 

ATP burners = adjustable thermal profile burners, manually or automatically adjustable to change the heat release pattern of the combustion reaction. See section 2.6.)... 

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