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About Industrial Furnaces
Industrial furnaces are an enclosed structure that
produces heat for industrial purposes. They are made with several kinds
of heat resistant (refractory) elements to withstand long term use. The
enclosed space holds the materials, gas or air being heated until the
desired temperature is reached. Industrial furnaces can come with varying
temperature control options or set for a single temperature, depending
on the process for which the furnace will be used. Industrial furnaces
commonly have one of the following atmospheres: air or oxidizing, inert,
reducing, salt bath and vacuum. Over temperature protections, service
or entry holes, three-zone or multi-zone, view ports, computer interface
and application software are some of the features available on these
furnaces. Heat sources can be infrared or radiant, natural gas, induction,
conduction, electrical or dielectric.
Industrial furnace designers produce furnaces that are used for various
heat treatments of materials. Heat treating adds billions of dollars
per year in value to metal products, especially steel and nonferrous
products, by imparting specific properties to the parts. These properties
are critical to the proper function of the parts. Basically, heat treating
involves three steps. The part is first heated to a specified temperature
up to 2400.25ºF. It is then held at that temperature for the required
amount of time, which may be as little as a few seconds or as much as
60 hours. Finally, the parts are cooled either in the furnace or by quenching
methods, which quickly cool the parts.
While industrial furnaces are similar to industrial
ovens, they usually
have higher temperature capacities than ovens, as well as differing uses.
Industrial furnace designers create industrial furnaces that can be used
to heat air or gas as part of a process or heating system; ovens typically
cannot. Industrial furnaces can be used to alter or simply heat the material
involved. Other uses for industrial furnaces include ageing, annealing,
atmosphere control and sterilization. It is important to consider the
temperature requirements, pressure involved and makeup of the material
when looking for industrial furnaces. The internal width, length and
height of the furnace are factors that are determined by industrial furnace
designers and the size of parts or materials to be processed.
The steel industry, among others, uses high-temperature, natural gas-fired
furnaces, which produce large amounts of nitrous oxide (NOx) per unit
of processed material. To meet increasingly stringent emissions regulations,
oscillating combustion technology has been developed and is continuing
to be improved. This technology provides efficiency, productivity and
reduced NOx emission from all types of industrial furnaces. A valve is
used to oscillate the fuel flow rate to the burner. Oscillation creates
fuel-rich and fuel-lean zones within the flame that retard the formation
of NOx, increasing heat transfer to the load. Another project is underway
to reduce NOx emissions and carefully control flame temperatures of natural-gas
furnaces with flame image sensing techniques. Flame data will be collected
with either fiber-optic detectors or spectrometers and video cameras.
The data will be used to develop control strategies for the most efficient
control of these furnaces.
Featured
Articles
(PDF)
http://www.epa.gov/epaoswer/hotline/training/bif.pdf
Types of Industrial Ovens
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use hydrogen to protect materials from oxidation, relieving the residual
stresses produced during the processing of steel strips, tubes and rods.
The hydrogen also has high heat transfer properties that aid in the
reduction of production cycles.
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heat treat one load at a time. Batch furnaces are used in applications
in which large parts and complex alloy grades must be treated.
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are continuous-type furnaces that move parts using a mesh-type or cast-link
belt.
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are large towers or cylinders that have a heat resistant lining and
force gusts of hot air and gases up through the furnace load.
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are batch-type furnaces that are used for lower stress-relieving ranges.
Car furnaces utilize a car on rails for entering and exiting the furnace
area.
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are heat-treating furnaces through which materials continuously enter
one door and are discharged through another.
- are continuous-type furnaces in which the parts are
conveyed through a tunnel-like heating area on hooks or fixtures, in
order to minimize distortion.
- are machines that use electricity to heat.
- , used to melt glass, have burner ports and the checkers
on the same end. While end port regenerative furnaces are initially
energy efficient, the checker volume eventually decreases through plugging,
resulting in the gradual decrease of melting efficiency over the life
of the furnace.
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burn gas to create heat.
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(http://www.industrial-ovens.net)
heat the material and cool it to bring it to a desired point for increased
strength, ageing or manipulation.
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use combined electrical resistance and hysteresis losses to heat metal
by exposing it to the varying magnetic field around a coil-carrying
alternating current.
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are continuous-type furnaces in which parts are charged into the furnace
in containers on a periodic basis. These containers are pushed against
a line of containers that have already been heated, advancing the containers
towards the discharge end of the furnace, where they are put into use.
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are a type of continuous furnace that utilize an internal screw to advance
the parts, giving good control of the retention time within the heated
chamber.
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are a type of continuous furnace that advances the parts along the hearth
using a reciprocating shaker motion.
- , used to melt glass, have burner ports on opposite ends
and incorporate a greater checker volume than the end port regenerative
furnace, resulting in higher pull rates.
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heat materials below their melting point to make them more dense or
compact and solid, which can lead to shrinkage.
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are furnaces in which stock is charged and removed in batches through
a slot or opening.
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are airtight and use low atmospheric pressure as the atmosphere for
heating.
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