Industrial furnace

Furnace designs vary as to its function, heating duty, type of fuel and method of introducing combustion air.

Heat is generated by an industrial furnace by mixing fuel with air or oxygen, or from electrical energy.

[1] These are designed as per international codes and standards the most common of which are ISO 13705 (Petroleum and natural gas industries — Fired heaters for general refinery service) / American Petroleum Institute (API) Standard 560 (Fired Heater for General Refinery Service).

Industrial furnaces are used in applications such as chemical reactions, cremation, oil refining, and glasswork.

Tubes can be vertical or horizontal, placed along the refractory wall, in the middle, etc., or arranged in cells.

The crossover piping is normally located outside so that the temperature can be monitored and the efficiency of the convection section can be calculated.

This is a series of tubes horizontal/ vertical hairpin type connected at ends (with 180° bends) or helical in construction.

Most pilot flames nowadays are lit by an ignition transformer (much like a car's spark plugs).

Using a pilot flame for lighting the furnace increases safety and ease compared to using a manual ignition method (like a match).

Sootblowers utilize flowing media such as water, air or steam to remove deposits from the tubes.

The flue gas stack is a cylindrical structure at the top of all the heat transfer chambers.

The breeching directly below it collects the flue gas and brings it up high into the atmosphere where it will not endanger personnel.

The stack damper contained within works like a butterfly valve and regulates draft (pressure difference between air intake and air exit) in the furnace, which is what pulls the flue gas through the convection section.

The floor of the furnace are normally castable type refractories while those on the walls are nailed or glued in place.

Ceramic fibre is commonly used for the roof and wall of the furnace and is graded by its density and then its maximum temperature rating.

Design of pillars and entire foundation is done based on the load bearing capacity of soil and seismic conditions prevailing in the area.

The normal size of the access door is 600x400 mm, which is sufficient for movement of people/ material into and out of the heater.

During operation the access doors are properly bolted using leak proof high temperature gaskets.