AERODYNAMIC CONSTITUTION OF OPEN-HEARTH FURNACE (II)

FEATURES OF FLOW IN TYPICAL DESIGNS

Abstract

Flow patterns in semi-Venturi, Maerz and the single air-uptake design with the single oil burner were studied by means of water models.
Essential flow pattern in the furnace chamber seems to be same in any design. Almost whole central cross-section of chamber is covered with a pair of (JL-shaped) vortices flowing, as Halliday and Philip pointed out in gas-fired Maerz design, upwards along the back and front walls, inwards along the ceiling and downwards at the center of the furnace.
In the vertical section along the furnace center line, the flow forms a large recirculation, as Halliday and Philip showed in gas-fired semi-Venturi design. The lower part of this recirculation consists of the main furnace flow and the upper part a return flow under the ceiling.
The return flow runs against the new air flow under the incoming end of the ceiling and makes the air flow down toward the burner jet to promote mixing of fuel and air.
Differences of flow patterns among these designs exist in the mechanism of mixing at the incoming end. Double air-uptakes, producing JL-shaped air flow, promote mixing at the upper surface of the burner jet. The sigle air-uptake adds mixing under the burner jet.
The fact suggests the fitness of single air-uptake design to the oil fired open-hearth furnace.