Furnace induction system

Claim 1

An induction system for injection of a treated combustion gas into the combustion zone of a furnace having a combustion chamber, a fuel burner within the combustion chamber and a source of air having a pressure greater than the pressure within the combustion chamber during firing, the system comprising an air flow line extending from the source of air to the combustion chamber and having an end opening into the combustion chamber adjacent the combustion zone; a bubble chamber for bubbling air through a liquid to form a treated output gas, the bubble chamber including an inlet port and an outlet port; a venturi located within the air flow line adjacent the end of the line opening into the combustion chamber, the venturi including an inlet port, an outlet port and a low-pressure port, the inlet and outlet ports both located within the air flow line with the outlet port located closely adjacent the end of the line opening into the combustion zone so that air flows from the source through the venturi and into the combustion zone; a flow control device located in said line upstream of the venturi operable to restrict the flow of air through the line and venturi to the combustion chamber; and a gas flow line connecting the outlet port of the bubble chamber with the low-pressure port of the venturi whereby the flow of air from the source and through the venturi lowers the pressure at the low pressure port and pressure-draws the treated output gas from the bubble chamber into the venturi to mix nonmechanically with the flow of air delivered to the combustion zone and thereby improve combustion.