Radiant wall oven and process for generating infrared radiation having a nonuniform emission distribution

A radiant wall structure for radiating substantially infrared energy and having a nonuniform temperature distribution, comprising:

• a radiant emitting wall having an exterior radiant energy emitting surface and an interior surface and having a lower portion and an upper portion;
• a second wall spaced outwardly a distance from said radiant emitting wall for defining a combustion chamber therebetween, said second wall having an interior radiant emitting surface and an exterior surface;
• and
• an elongated linear burner for delivering heated gas through said combustion chamber, said elongated linear burner being disposed within said combustion chamber and having a burner combustion surface residing in close proximity to a lower portion of said radiant emitting wall so that said lower portion of said radiant emitting wall receives energy from radiation from said burner combustion surface in addition to energy from the interior radiant emitting surface and from convective heat transfer from the products of combustion and so that said upper portion of said radiant emitting wall receives energy from primarily radiation from said interior radiant emitting surface and convection from said linear burner.

A modular oven for heating products via infrared radiation, comprising:

• (a) a first radiant wall module and a second radiant wall module being spaced apart and connected via a top panel and a bottom panel to form a throughway for heating said products passed therethrough along an axis;
• (b) said first and second radiant wall modules each comprising:
• (1) a radiant emitting wall having an exterior radiant energy emitting surface and an interior surface, said radiant emitting wall being continuously curved about said axis;
• (2) a second wall spaced outwardly from said radiant emitting wall for defining a combustion chamber therebetween, said second wall having an interior radiant emitting surface and an exterior surface;
• and
• (3) heating means for delivering heated gas through said combustion chamber, said heating means being disposed within said combustion chamber and having a burner combustion surface disposed adjacent to a lower portion of said radiant emitting wall so that said radiant emitting wall receives energy by radiation from said interior radiant emitting surface and convection and radiation from said burner means.

A process for radiating substantially infrared energy from an emitting surface, with a nonuniform temperature distribution, comprising the steps of:

• forming a radiant emitting wall, with a continuous curvature about an axis, having an exterior radiant energy emitting surface and an interior surface and having lower and upper portions;
• disposing a second wall spaced a distance from said radiant emitting wall for defining a combustion chamber therebetween, said second wall having an interior radiant emitting surface and an exterior surface;
• and
• delivering heated gas through said combustion chamber from a heating means disposed within said combustion chamber by burning products of combustion surface residing adjacent to one of said portions of said radiant emitting wall;
• and
• positioning said burner combustion surface a prescribed distance from said interior surface of said radiant emitting wall so that said radiant emitting wall exhibits nonuniform temperature distribution wherein said one of said portions of said radiant emitting surface is maintained at a higher temperature than said upper portion.

A process for radiating substantially infrared energy with a nonuniform temperature distribution from an emitting surface, comprising the steps of:

• providing a heating apparatus having (i) a radiant emitting wall with an exterior radiant energy emitting surface and an interior surface, said radiant emitting wall having two portions, (ii) a second wall spaced outwardly from said radiant emitting wall for defining a chamber therebetween, said second wall having an interior radiant emitting surface and an exterior surface, and (iii) a heating means within said combustion chamber, said heating means having a heating source adjacent to one of said portions of said radiant emitting wall;
• emitting heat nonuniformly from said exterior radiant energy emitting surface so that said one of said portions of said radiant emitting surface is maintained at a higher temperature than the other of said portions;
• insulating said exterior wall of said second wall for causing said second wall to be heated to a temperature higher than said radiant emitting wall so that an appreciable amount of radiant energy is radiated from said interior radiant emitting surface when said chamber is heated;
• and
• directing radiant and convective heat from said heating source and radiant heat from said interior radiant emitting surface against said one of said portions of said radiant emitting wall;
• directing radiant heat from said interior radiant emitting surface and convective heat from said heating means against the other of said portions of said radiant emitting surface, so that one of said portions emits substantially more radiant energy than the other of said portions;
• and
• regulating said conductive heat for maintaining a prescribed difference in temperature between said portions.

A process for radiating substantially infrared energy with a nonuniform temperature distribution from an emitting surface, comprising the steps of:

• providing a heating apparatus having (i) a radiant emitting wall with an exterior radiant energy emitting surface and an interior surface, said radiant emitting wall having two portions, (ii) a second wall spaced outwardly from said radiant emitting wall for defining a combustion chamber therebetween, said second wall having an interior radiant emitting surface and an exterior surface, and (iii) a heating means within said combustion chamber, said heating means having a burner combustion surface adjacent to one of said portions of said radiant emitting wall;
• emitting heat nonuniformly from said exterior radiant energy emitting surface so that said one of said portions of said radiant emitting surface is maintained at a higher temperature than the other of said portions;
• and
• varying the position of said burner combustion surface relative to said one of said portions of said radiant emitting wall so as to change the nonuniform temperature distribution of said radiant emitting wall.

A radiant wall structure for radiating substantially infrared energy for drying or curing coatings on the surfaces of objects comprising:

• (a) a first radiant emitting wall having a radiant emitting outer surface and a radiant absorbing inner surface, said first radiant emitting wall having a length in a longitudinal direction;
• (b) a second wall spaced from said radiant absorbing inner surface of said first radiant emitting wall for defining therebetween a chamber, said second wall having an interior radiant emitting surface, said inner radiant absorbing surface of said first wall and said inner radiant emitting surface of said second wall being in opposed relationship to each other;
• (c) a gaseous burner for delivering heated gases into said chamber for heating by convection said inner emitting surface of said second wall and said radiant absorbing surface of said first wall, said burner being located within the lower portion of said chamber and extending substantially the length of said first radiant emitting wall;
• said burner, when lighted, emitting infrared radiant energy to said absorbing surface of said first wall and to said inner radiant absorbing surface of said second wall;
• (d) insulation for said second wall for restricting the loss of heat to the exterior of said second wall sufficiently for the average temperature of said radiant emitting surface of said second wall to appreciably exceed the average temperature of said first radiant emitting wall thereby transfering radiant energy from inner emitting surface to said radiant absorbing surface of said first radiant emitting wall;
• (e) the average fixed emission intensity, for a specific energy input between the lower and upper segments of the wall being dependent on the distance from the combustion surface of the burner and said first emitting wall;
• (f) the energy input to said gaseous burner, at an equilibrium temperature of the first radiant emitting wall averaging between about 3,000 BTUH and about 35,000 BTUH per foot of said first emitting radiant wall in its longitudinal direction;
• (g) means for supporting an object sufficiently located with respect to said first radiant emitting wall, that surfaces of said object absorb radiant emission from said first radiant emitting wall;
• (h) the heat delivered from said second wall to said first wall by radiation being between about 30% and 70% of the total heat delivered to said first wall;
• and
• (i) said gaseous burner heating said radiant emitter of said second wall for generating infrared heat, said second wall being so positioned with respect to said first wall and said gaseous burner being so located that said infrared heat is directly by the emitting surface of said second wall toward said infrared absorbing surface of said first wall, said first wall and said burner being so positioned that increments of said first wall are heated to radiate at different temperatures.

An oven for drying coatings on successive objects, comprising:

• a pair of spaced, opposed, inner walls defining a central heating zone through which said successive objects are passed from one end portion of said zone to the other end portion of said zone along a substantially linear path of travel;
• a floor between said opposed walls and over which said objects are passed;
• a top for said heating zone;
• outer walls respectively outwardly of said opposed walls for defining, with said walls, heating chambers on opposite sides of said central heating zone;
• said opposed walls having opposed inner infrared emitting surfaces facing said path of travel of said objects, and opposed walls having outer infrared absorbing surfaces;
• said outer walls having infrared emitting surfaces respectively opposite to said infrared absorbing surfaces;
• said outer walls having outer surfaces outwardly of said infrared emitting surfaces of said outer walls;
• insulation for said outer surfaces of said outer walls for appreciably restricting heat loss from said chambers through said outer walls;
• linear burners disposed in said chambers for generating hot gases along the length of said chambers, for heating said inner walls and said outer walls, said hot gases heating said outer walls to average temperatures substantially higher than the average temperature of said outer walls and sufficiently for said infrared emitting surface of said outer walls to emit appreciable amounts of infrared heat toward said infrared absorbing surfaces of said inner walls for thereby heating said inner walls sufficiently for said infrared surfaces of said inner walls to emit infrared radiation toward said path of travel of said objects, the majority of such infrared radiation emitted toward said path of travel of said objects being at wave lengths of five microns or greater;
• the position of said linear burner being approximately parallel to said path of travel of said objects and being at a prescribed height and position in said chambers, such that the convection heating by said hot gases and the radiation generated by said infrared emitting surfaces of said outer walls will heat one of the longitudinal increments of said inner walls to greater extents than other of the longitudinal increments of said wall whereby greater amounts of infrared heat are generated by said one of said longitudinal increments.