![]() ![]() Air registers located below the burner and at the outlet of the air blower are devices with movable flaps or vanes that control the shape and pattern of the flame, whether it spreads out or even swirls around. The burner tile is made of high temperature refractory and is where the flame is contained. Some furnaces have side fired burners, such as in train locomotives. ![]() The burner in the vertical, cylindrical furnace as above, is located in the floor and fires upward. ![]() While designing the radiant coil, care is taken so that provision for expansion (in hot conditions) is kept. Material of these supports is generally high alloy steel. These are supported from the radiant side walls or hanging from the radiant roof. Radiant coil materials vary from carbon steel for low temperature services to high alloy steels for high temperature services. The radiant coils and bends are housed in the radiant box. They can be single pass or multi pass depending upon the process-side pressure drop allowed. The radiant coil absorbs heat through radiation. This is a series of tubes horizontal/ vertical hairpin type connected at ends (with 180° bends) or helical in construction. Flame impingement happens when the flame touches the tubes and causes small isolated spots of very high temperature. The sightglass at the top allows personnel to see the flame shape and pattern from above and visually inspect if flame impingement is occurring. The crossover piping is normally located outside so that the temperature can be monitored and the efficiency of the convection section can be calculated. A crossover is the tube that connects from the convection section outlet to the radiant section inlet. The area of the radiant section just before flue gas enters the shield section and into the convection section called the bridgezone. The first three tube rows in the bottom of the convection section and at the top of the radiant section is an area of bare tubes (without fins) and are known as the shield section ("shock tubes"), so named because they are still exposed to plenty of radiation from the firebox and they also act to shield the convection section tubes, which are normally of less resistant material from the high temperatures in the firebox. Heat transfer takes place by convection here, and the tubes are finned to increase heat transfer. The convection section is located above the radiant section where it is cooler to recover additional heat. This heated fluid is then circulated round the whole plant to heat exchangers to be used wherever heat is needed instead of directly heating the product line as the product or material may be volatile or prone to cracking at the furnace temperature.)Ĭomponents Radiant section Industries also use their furnaces to heat a secondary fluid with special additives like anti- rust and high heat transfer efficiency. After the flue gas leaves the firebox, most furnace designs include a convection section where more heat is recovered before venting to the atmosphere through the flue gas stack. The gases from the combustion are known as flue gas. The fluid to be heated passes through the tubes and is thus heated to the desired temperature. In this chamber where combustion takes place, the heat is transferred mainly by radiation to tubes around the fire in the chamber. The flames heat up the tubes, which in turn heat the fluid inside in the first part of the furnace known as the radiant section or firebox. Burners can also be floor mounted, wall mounted or roof mounted depending on design. There can be more than one burner in a particular furnace which can be arranged in cells which heat a particular set of tubes. Schematic diagram of an industrial process furnaceįuel flows into the burner and is burnt with air provided from an air blower. Industrial furnaces are used in applications such as chemical reactions, cremation, oil refining, and glasswork. Types of industrial furnaces include batch ovens, vacuum furnaces, and solar furnaces. 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). ![]() The residual heat will exit the furnace as flue gas. Heat is generated by an industrial furnace by mixing fuel with air or oxygen, or from electrical energy. Furnace designs vary as to its function, heating duty, type of fuel and method of introducing combustion air. They are used to provide heat for a process or can serve as reactor which provides heats of reaction. An industrial chamber furnace, used to heat steel billets for open-die forgingĪn industrial furnace, also known as a direct heater or a direct fired heater, is a device used to provide heat for an industrial process, typically higher than 400 degrees Celsius. ![]()
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