US1961143A - Oven heated by convection - Google Patents

Description

June 5, 1934- c, L. GEHNRICH OVEN HEATED BY coNvEcTIoN Filed May 6, 1931 2 Sheets-Sheet l t v T anni lian INVENTOR A oRNEY 2 sheets-sheet .Filed May 6`, 1951 l NVENTOR Patented June 5, 1934i OVEN HEATED BY CONVECTION charles L. Gehnrich, Elmhurst, N Y. Application May 6, 1931, Serial No. 535,438

4 Claims.

My invention relates to heat processing ovens of the type heated by convection; that is, ovens of the type in which circulating air first absorbs heat from a heater and then imparts it to thearticles to be heat processed.

Htherto ovens of this type were constructed as two separate units, the one being the heating unit and the other the processing unit. These units were ordinarily connected to each other by pipes or ducts which provided for a circulation of the heated air between the two. This construction requires considerable space exterior to the oven and, by reason of its elaborate nature, is expensive. There are, moreover, several mechanical disadvantages attending this construction. Chief among these is its low efficiency caused by the loss .of heat byradiation occasioned during the passage of the hot air and gas between the two units. Furthermore, in such a construction, in order to keep the size of the heater within practical limits and at the same time to supply suic'ient high temperature air to completely heat the processing unit, it is necessary t'o use relatively high temperature heating units and small fans of high velocity. This results in excessive disintegration of parts used in the generating and transferring of the hot air and gases.

It is an object of my invention to provide a heat f generating unit and a processing unit as `integral parts of a single structure thereby decreasing the cost of construction, the amount of exterior space required and the cost of maintenance of equipment.

A further object of my invention is to divide such an oven construction into two main sections, one being the heat generating compartment and the other being the processing compartment, and to further divide the heatgenerating compartment into two sections, the onebeing the combustion section and the other being the expansion or mixing' section. The provision of this expansion or mixing section is' very important for the reason that when the hot gases are given a chance to expand before reaching the processing compartment, a lower temperature differential be? tween the heat ,generating chamber and process--y ing chamber is obtained.

It is a further object of my invention to so con-l nect the heat generating compartment with the processing compartment that the loss of heat by radiation from the air and gasses passing from one compartment to the other is reduced to a practical minimum, thereby imparting a. high efcincy to the entirel apparatus. This connectioni according to the preferred form of my in- .partment that the air and gases returning from.

vention, covers the entire length of the wall sepap rating the two compartments.

This construction, in connection withy the low velocity of heating gases possible in my apparatus, practically `eliminates the possibility of the formation of heat pockets in the processing compartment.

Another object of my invention is to so construct the combustion sectionof the heating comthe processing compartment pass on all sides of the refractory bodies comprising the combustion section thereby efficiently preventing overheating and consequent disintegration of these bodies.

These and further objects-and advantages of my invention will be apparent from the following detailed description of the accompanying drawings in which-- Fig. 1 represents a vertical longitudinal section along the line A-A of Fig. 2.

Fig. 2 represents a plan viewv of the oven with a portion of the top wall broken away.

Fig. 3 represents a vertical transverse section of the same along the line X-X of Fig. 1 with the blower equipment removed.

Fig. 4 represents a vertical longitudinal section of a modied form of the heat generating compartment.

Referring to the drawings in detail, 1 designates a processing compartment provided with a door 2 for the insertion and removal of the material to be treated. This material is placed on the rack 3 which may be stationary or removable in any known manner. The inner end wall` 4 of the heat generating chamber in the modication shown in Figs. l to 3 inclusive is mounted on I-beams or equivalent structural elements 5 in such a way as to leave a space between its lower end and the floor. This wall is of such dimensions that` an additional space is left betweenits 95 upper end and the top wall of the oven. In small ovens this wall may be mounted on hinges to form a door and in large ovens a door may be mounted in said wall in order to provide access to the heating chamber for repair work. Mounted along the top edge of wall 4 is a vertically movable cross-piece 6 which may be adjusted to control the ow of air and gas from the heat generating compartment over the top of said wall. 'Ihe space 7 enclosed by wall 4, wall 8 and the side walls of the heat processing compartment constitutes the heat generating chamber and the expansion chamber. Mounted on I-beams 5 is a grate 9 which may be used as a support for solid fuel of any type or for gas or oil jets. Spaced partment.

inclusive.

pass on both sides of walls 10 and 12.

Opening intothe heat generatingsection is an air inlet 13 in the form of an adjustable opening-'- The portion of the heat generating chamber above the combustion section constitutes an expansion chamber. This expansion, chamber may be of any size. l

Extending above the expansion chamber and communicating therewith is a blower 14 which also communicates with the processing compartment. That end of theblower which is connected :to the baking compartment is joined to a duct 15 which opens into the processing ycompartment at the end opposite the heat generating section. This arrangement provides for a complete circulation of the air and gases in the processing com- Passing from the processing section is an exhaust pipe 16 which removes such air and gases from said processing compartment as may be necessary by nature'of the process. Exhaust through said pipe may be proportionately controlled by ymeans of a damper 17.

The operation of my device shown -in Figs. 1 to 3 is relatively simple. At the beginning of the processing operation, the `blower is started, the source of heat turned on and the damper 17 adjusted. -The heated air passes` into the processing compartment. through the duct 15 and circulates therethrough. If it be desired to pass all thev circulating air and gases through the combustion chambentne opening at the upper end of wall 4 can be closed bythe cross-piece 6. While the exhaust pipe is open, fresh air continuously enters through the air inlet 13 to compensate for the amount `o1 air expelled through the pipe 16. After the exhaust pipe has been closed, however, the amount of air entering the Vair-inlet 13 is automatically reduced and the system soon reaches an equilibrium at which only a small amount of fresh air enters at each cycle of the heated air and gas.-

` In the embodiment shown in Fig. 4, the blower 14 is replaced by a fan 14! which is mounted in an opening in wall I4. This construction, while it more completely eliminates the small losses by radiation which 'accompany thev use of the blower, does not permit 'of the adjustlrnt of the amount'of circulating gas which passes through the combustion chamber on each cycle such as is possible with the apparatus shown in Figs. 1 to 3 In the embodiment shown in Fig. 4, in other words, all the circulating air and gas passes through the combustion chamber on each cycle.

Having thus described the nature and object of my invention and havingillustratted the preferred "embodiments ofthe same, which embodiments are 1,961,143 from the sides of this grate are refractory walls illustrative of the nature of rather than the scope of my invention, what I claim as new and desire to secure by Letters Patent is:

1. An oven comprising a heat-processing compartment, a heat-generating compartment, a separating wall between saidicompartments having its lower` and upper ends spaced from the bottom and top of said oven'respectively, a combustion chamber at the lower portion of said heatgenerating compartment spaced from the floor of -said -oven whereby gases from said processing compartment can pass underneath said separating wall and through said combustion chamber and an adjustable cross-piece at the upper end of said wall for adjusting the size of the space between said wall and the top of said oven thereby regulating the amount of gas passing underneath said wall.

-2. An oven comprising a heat-processing compartment, a heat-generating compartment, a separating wall between said compartments, a combustion chamber at the lower portion of said heat-generating compartment comprising a grate spaced from the floor of said oven and refractory walls mounted adjacent said grate in spaced relation thereto and in spaced relation to the wall of the oven, said separating wall, and each other and agas passage in the lower end of said separating wall below said combustion chamber whereby gases from said processing compartment can pass through said separating wall through said grate and on all sides of said refractory walls.

3. An oven comprising a heat-processing compartment, a heat-generating compartment, a separating wall between said compartments having its lower portion spaced from the oor of said oven and a combustion chamber at the lower portion of said heat-generating compartment comprising a grate spaced from the floor of said oven and refractory walls mounted adjacent said 115 grate and in spaced relation thereto and in spaced relation to the wall of the oven, said separating wall andv each other, whereby gases from said processing compartment can pass underneath said separating wall, through said grate and on all sides of said refractory walls.

4. An oven comprising a heat-processing compartment, a heat-generating compartment, a separating wall-between said compartments hav- 125 ing its lower end spaced from the fioor of said oven and a combustion chamber at the lower portion of said heat-generating compartment comprising a grate spaced from the floor of said oven and refractory walls mounted adjacent said grate and in spaced relation thereto and in spaced relation to the wall of the oven, said separating wall and each other, whereby gases from said processing compartment can pass underneath said separating wall, through said grate and on all sides of said refractory walls and means at the upper end of said separating wall for regulating; the amount of gas passing underneath saidv wall.

CHARLES L. GEHNRICH.

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