System for improving the flow of gases to a combustion chamber of a coke oven or the like

An industrial gas-fired system such as a coke oven, said system including a heating flue and ducts having a vertical portion and an obliquely-rising duct portion for conducting a flow of combustion gases into said heating flue, recuperative waste-heat recovery means receiving waste gases for preheating said combustion gases which comprise air when heating by combustion of rich gas and comprise air and lean gas when heating by combustion of lean gas, said combustion gases being introduced through said ducts from outlets of said waste-heat recovery means into a heating flue, said system including the combination therewith of wedge-shaped refractory bricks each having at least one oblique surface, each brick being supported within a vertical portion of a duct and having vertical bores, the vertical portion of each duct having an increased diameter and extending to the base of the flue, each brick having a rectangular cross section with vertical sides abutting the inner walls of the duct so that the said oblique surface extends at the bottom of the brick toward the mouth of the obliquely-rising duct portion, the sum of the cross-sectional areas of said cylindrical bores being within the range of 0.75 to 1.5 times the cross section of the gas-flow portion of the obliquely-rising duct portion.