A method includes firing a first burner into a furnace process chamber in a first initial condition, firing a second burner into the process chamber in a second initial condition, and measuring temperature at each of an array of locations in the process chamber. The first burner is adjusted to a first adjusted condition while the second burner is being fired at the second initial condition, and a resulting first temperature change is measured at each of the locations. The second burner is adjusted to a second adjusted condition while the first burner is being fired at the first initial condition, and a resulting second temperature change is measured at each of the locations. The measured first and second temperature changes are recorded as reference data for adjusting burner conditions to adjust temperatures at each of the locations. The method can thus be used to improve temperature uniformity throughout the array of locations.

The dry oxygen content in the exhaust of an industrial furnace may be controlled to 1% or less by determining one or more of: the temperature of: each or a group of one or more burner (flame); one or more section of the radiant walls adjacent (e.g., within 5 feet of the burner); the temperature gradient across the process coils; the combustion products of one or more burners; the mass flow rate or the volume flow rate of air to each burner (e.g., the pressure drop across the variable forced air aperture

ii) comparing the result to said target value; and
iii) adjusting either a) the opening of the variable forced air aperture; or b) adjusting the mass flow rate or the volume flow rate of air from said one or more fans.

The dry oxygen content in the exhaust of an industrial furnace may be controlled to 1% or less by determining one or more of: the temperature of: each or a group of one or more burner (flame); one or more section of the radiant walls adjacent (e.g., within 5 feet of the burner); the temperature gradient across the process coils; the combustion products of one or more burners; the mass flow rate or the volume flow rate of air to each burner (e.g., the pressure drop across the variable forced air aperture ii) comparing the result to said target value; and iii) adjusting either a) the opening of the variable forced air aperture; or b) adjusting the mass flow rate or the volume flow rate of air from said one or more fans.

An integrated aluminum melting and holding system is provided. The system includes, in combination, a hearth for receiving and melting a charge of aluminum pieces, a holding chamber for maintaining the elevated temperature for casting, and a well to allow removal of the molten aluminum for delivery to a casting station. The hearth includes a combustion chamber having a fuel burner section communicating with the hearth for burning hydrocarbon fuel with air to produce effluent hot gases in the burner section for circulation through the hearth for melting the aluminum pieces. The holding chamber receives molten aluminum from the hearth. The holding chamber has at least a substantial portion positioned below a substantial portion of the hearth. The holding chamber includes at least one immersion heater in contact with the molten aluminum. The holding chamber further includes a lid configured to contact the molten aluminum disposed within the holding chamber. The open top well is in fluid communication with the holding chamber for receiving the molten aluminum.