Flame-less infrared heater

Abstract

A heating apparatus including a housing having a radiant energy output side and an oppositely disposed burner side. The radiant energy output side includes at least one re-radiating surface. Disposed within the housing proximate the burner side and having a burner outlet facing the radiant energy output side is a burner. At least one concave reflector is disposed around the burner and is oriented to reflect heat from said burner toward said radiant energy output side of said housing.

Description

[0001] 1. Field of the Invention[0002] This invention relates to a high-temperature, non-catalytic, flame-less infrared heater having a burner and a re-radiating surface proportioned to operate the heater at approximately 700.degree. F. to 1500.degree. F. The heater is particularly useful in low to moderate temperature heating applications in which direct contact with a flame is to be avoided and can be used in place of conventional low-to-medium flux gas-fired infrared radiant heaters, catalytic heaters and electrical heaters.[0003] 2. Description of the Prior Art[0004] Thermoforming is a process which uses heat and pressure and / or vacuum to form parts from an extruded sheet of thermoplastic. In the process of thermoforming, plastic is drawn from large rolls, heated to its softening temperature, and then formed into a desired shape using an aluminum forming tool. The plastic is then cut into individual containers, stacked, inspected, counted, boxed and shipped. The heating section ...

AI Technical Summary

Benefits of technology

[0013] It is yet another object of this invention to provide a heating apparatus that bridges the gap between low flux catalytic and electric heaters and high flux ceramic and metal fiber heaters.

[0015] In accordance with one particularly preferred embodiment of this invention, the burner outlet comprises a convex surface suitable for sustaining combustion of a mixture of fuel and oxidant. In this fashion, radiant energy generated by the burner is transmitted in a radial manner toward the re-radiating surface in contrast to conventional burners with a burner outlet comprising a substantially flat combustion surface in which the radiant energy is transmitted only in a direction substantially perpendicular to the plane of the combustion surface. To provide uniformity in the distribution of radiant energy on the re-radiating surface, the re-radiating surface is preferably constructed of a sintered metal fiber web. In comparison to conventional infrared heating systems in which the re-radiating surface is constructed of a mesh, such as a wire mesh, whereby the products of combustion generated by the burner pass through the mesh screen substantially unimpeded, resulting in non-uniform distribution of heat from the combustion products to the re-radiating surface, a sintered metal fiber web, although porous, is substantially more dense than the mesh of conventional systems, thereby increasing the residence time of the combustion products generated by the burner within the housing, resulting in substantially uniform distribution of heat from the re-radiating surface.

Problems solved by technology

The primary reason for not using gas-fired infrared is due to operating temperature and control limitations of available gas heaters.

Electric heaters are intrinsically expensive to operate while catalytic heaters, in addition to being expensive, produce high concentrations of unburned hydrocarbons and carbon monoxide.

In addition, a glowing flame is very prominent over the mesh as a result of which the heat flux distribution is highly irregular and non-uniform, particularly for larger scale heaters with large re-radiating surfaces.

In comparison to conventional infrared heating systems in which the re-radiating surface is constructed of a mesh, such as a wire mesh, whereby the products of combustion generated by the burner pass through the mesh screen substantially unimpeded, resulting in non-uniform distribution of heat from the combustion products to the re-radiating surface, a sintered metal fiber web, although porous, is substantially more dense than the mesh of conventional systems, thereby increasing the residence time of the combustion products generated by the burner within the housing, resulting in substantially uniform distribution of heat from the re-radiating surface.

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