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NEW EQUIPMENT | LUMINIOUS WALL FURNACES
Park Thermal International presents the latest state-of-the-art furnace concept utilizing air to gas mixture which provides the optimum in radiation energy (Luminous Wall) and offers;
* No flame impingement * Faster heating * Faster cooling * More production
Utilizing infrared thermal energy produced through the even ignition of gases over a porous refractory surface, this unique Holden technology is exclusively available from Park Thermal International.
The Holden Luminous Wall investment casting mold firing furnaces are produced in a variety of cycles, sizes and configurations for, , , or operations.
These furnaces provide lower fuel costs, are low maintenance, operate in any plane and are instantly controlled.
NO FLAME IMPINGEMENT - The Luminous Wall burns over its whole surface with very short flames sufficient only to raise the surface of the wall to the radiant stage. The wall, in turn, radiates the energy to the work. The net result, is very uniform heating with no hot spots and no flame impingement on the work.
LOWER FUEL COSTS - Heat normally wasted as wall losses preheats the air-gas mixture. This eliminates wall losses and assures complete combustion, provides a recuperation effect as air/gas is preheated to combustion temperature at the point of combustion. Less heat is lost in exhaust gases. The hot gases of the tiny flames uniformly heat the surface of the Luminous Wall to produce more radiant heat. More of the flames energy is transferred to the work and less heat is lost in the exhaust gases. According to a University of Michigan research report, 98.8% of this energy is radiation. Less heat also is used to heat the furnace because of the low storage capacity of the Luminous Wall furnace. Radiant energy heats only objects, not air, can be focused, reflected and refracted at will.
LOW MAINTENANCE - Luminous Wall panel lifeis excellent even with rapid cycling between room temperature and 2,000°F. All but a thin layer of the panel stays at near room temperature. Most of the panels are not subjected to the thermal expansion and contraction, which causes cracking and spalling of refractory in conventional furnaces. The surface layer of the panels is protected from severe stresses by frequent use of uniqie expension joints.
FASTER - Luminous Wall furnaces come to operating temperature faster, cool faster, have faster response to demands for more or less heat and heat the work faster. Furnace idling is not required, since the furnace comes up to temperature in minutes; 2 to 3 minutes from cold start and cool to touch 3 minutes after the gas valve is closed. The Luminous Wall furnace has very little heat storage because only a very thin layer of the panels are at elevated temperature. This allows the furnace to come to operating temperature in a fraction of the time required for most furnaces and it can be cooled quickly. When furnace temperature or heat input rate must be changed, the furnace responds rapidly and accurately. The user is always in full control of furnace response rather than being subject to the 'flywheel of heat' effect. Work can be heated faster and more uniformly because the Luminous Wall can supply heat as fast as the work can absorb it, and there is more area available for heat transfer. The broad area, uniformly-heated the Luminous Wall allows more of the work area to 'see' the heat source. There are no hot spots to produce local overheating, or cold spots to reduce average heat transfer rate.
ZONING THE FURNACE - The Luminous Wall is frequently divided into a number of sections with each section served by a separate plenum chamber. This allows adjustment or control of the heat distribution in the furnace. An automatice control system can be used for each plenum chamber. Two or more plenum chambers can be grouped into a common automatic control zone and provided with manual adjustment of the heat distribution between the various plenum chambers in a zone. Furnaces also can be zoned vertically as well as horizontally for exceptional uniformity. The easy adjustment of heat distribution in the Luminous Wall is a major advantage both to the user and to the furnace designer. It is relatively inexpensive to make provisions for manual adjustment of the distribution within a major temperature control zone. This reduces the possibility of error in design and makes it easy for the user to change heat distribution for different jobs.
The rapid heating and cooling cycle obtained with the luminous wall furnace results from the immediate proximity of the gas flame to the refractory lining and the fact that the refractory is a good absorber and also a good emitter of radiant energy.
A gas to air mixture regulated by a mixing valve, flows into a plenium chamber (6" - 8" water column) and then through the porous insulating firebrick into the heating chamber. The gas mixture is ignited by a pilot and is burned across the porous refractory surface.
The temperature is controlled by a thermocouple, which actuates a control valve located in the airline. Approximately 60% of the heat produced is in the form of radiant energy. The luminous wall will operate to temperatures of 2,300°F.
The main feature of this furnace is the rapid rate it can be brought to an operating temperature. As an example, a 4" cubed radiant wall furnace firing 2 sides and back wall can be brought from room temperature to a uniform temperature of 2,000°F in less than 10 minutes. The same furnace can be cooled to room temperature in equally as fast.
Thus, three key factors explain the rapid heating and cooling cycle. First, there is a factor of closeness between the gas flame and the panel's surface. Second, the high emissivity of the ceramic lining. And third, the low conductivity of the ceramic panel.
APPLICATION OF LUMINOUS WALL HEATING - As a uniformly heated, wide-area heat source, luminous wall heating can be used in a wide variety of applications, either for direct heating of the work or for heating re-circulating gases in a conventional heat trasnfer system. Luminous (white-yellow) flame will transfer 55 Btu's/hour/square ft./degree difference in temperature as compared to only 10 Btu's for non-Luminous (blue) flame and with as much as 60% improvement in fuel efficiency.
BTU RATING OF THE WALL - The wall is normally applied with an input of 60,000 BTU/hour/square foot of wall. The heat available to the work at a given heat input to the wall will depend on the exhaust gas temperature and the air-gas ratio. In most applications, the Luminous Wall should be controlled and applied so that the furnace temperature does not exceed 2,000°F.
EMISSIONS - The thorough mixing and complete combustion of the air-gas mixture in Luminous Wall firing system is the prime reason for its extraordinary efficencies. But, in parts of the world where air pollution and emissions are of grave concern and the question of exhaust gases has arisen, and in seeking an answer, a remarkeable secondary advantage was discovered. The NOx content of the exhaust gases from a Luminous Wall furnace operated at 1,500°F. during a test conducted by Sidney University, Australia, was only 3.2 PPM. This figure is three to four times lower than furnaces heated by conventional burners. This extremely low NOx content is an added bonus, if air pollution is a concern.
LUMINOUS WALL RADIANT HEAT ADVANTAGES
VERSATILE - Applications unlimited in process engineering fields.
OPERATES IN ANY PLANE - In ovens, furnaces, free standing; panels mount vertivally, horizontally, or special-positioned for conveyorized curing, drying, etc.
INSTANTLY CONTROLLED - Up to working temperatures in minutes; can operate with any gas in industrial use; fuel cost savings 30 to 50%.
YEARS OF SERVICE - Low maintenance.
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