Industrial furnaces are enclosed devices that can create heat by burning fuel. They can also function as reactors that deliver heat. Industrial furnaces are made from high-temperature resistant materials and they are designed to withstand and hold highly heated process material. Like industrial ovens, industrial furnaces can serve a wide range of industrial tasks such as baking, aging, annealing, soldering, firing, melting, treating, drying, and curing, etc.
Furnaces can help to separate metals from ores and refine: oils, liquids, and chemicals through the heat provided to the fractional distillation columns. Depending upon the kind of fuel used and the usage of the heat created, there are various types of industrial furnaces available such as: top and bottom loading, charring, tube, box or muffle, conveyor belt, walk-in and truck-in, etc. The hot-air and hot-water furnaces burn fuel within an inner wall in a building complex, and direct the hot air and water to rooms. Electric furnaces are extensively used in the production of steel alloys and for the manufacture of high-speed tools. An electric arc or electric current, created through resistive elements is used to create heat in such furnaces.
Even though furnaces can perform different jobs and they can run on various types of fuel, most of them consist of the same principle parts. Fuel enters into a burner where flames are used to heat up tubes and then heat a fluid inside which is known as the radiant section. Then, in something called the firebox, combustion takes place and the heat is transferred by radiation to tubes around the fire. This hot liquid travels through the tubes and gets to a certain temperature which creates a gas known as flue gas. When this gas leaves the firebox a convection section of the furnace recovers more heat before it vents out through a stack.
In the radiant part of the furnace the tubes can be vertical or horizontal, depending on the nature of the furnace, and they can either be in the middle of the unit or on the walls. These tubes are usually made of steel and are separated from the furnace's insulation in order for radiation to be evenly reflected off of the tubes. In the convection section of the furnace, which is located above the radiant section, the tubes are finned to increase the heat transfer, while the burner is situated at the base of the furnace to provide the fire which heats the furnace.
The appropriate process temperature, the tube's length and breadth, and the pressure range are important considerations while selecting an industrial furnace.