Jet impingement recuperator

Claim 2

A controlled atmosphere radiant tube heating device comprising a fuel burner means, air intake means for injection of combustion air into the burner means, a radiant tube heated by combustion products from the burner means, an exhaust tube for conducting combustion products from the radiant tube, a length of the wall of the exhaust tube forming a heat exchange surface on each side thereof, an outer tube concentric with and surrounding the exhaust tube forming an exterior conduit for confining a flow of combustion air adjacent the heat exchange surface, means for directing the flow of combustion air into the exterior conduit at an inlet end thereof, means for directing the flow of combustion air from the exterior conduit at an outlet end thereof to the burner means, baffle means interior of the exhaust tube, the baffle means having openings therein for directing jets of combustion products onto said length of the wall, the openings having hydraulic diameters not less than one-eighth inch and not greater than one-half inch, the ratio of separation of centers of mass of the openings to the hydraulic diameter of the openings being not less than two or more than seven.

Claim 3

A radiant tube heat exchanger as defined in claim 1 wherein the exterior conduit contains second baffle means having openings therein for directing jets of the combustion air onto the heat exchange surface.

Claim 4

A radiant tube heat exchanger as defined in claim 1 wherein the ratio of the separation of an opening in the baffle means from the heat exchange surface to the hydraulic diameter of the opening is not less than one or greater than four.

Claim 5

A radiant tube heat exchanger as defined in claim 1 wherein the spatial pattern of the openings in the baffle means is diamond shaped.

Claim 6

A radiant tube heat exchanger as defined in claim 2 wherein the second baffle means comprises a plurality of sections aligned such that one end of each section is closer than the other end to the inlet end of the exterior conduit, and wherein for each section one end is fixedly attached to either the exhaust tube or the outer tube while the other end of each section comprises thermAlly expansible means for sealingly engaging the wall of the other tube means.

Claim 7

A radiant tube heat exchanger as defined in claim 5 adapted for laminar flow in the exterior conduit and a low pressure drop from the inlet end to the outlet end thereof wherein the second baffle means in the exterior conduit comprises not more than eight annular baffle plates dividing the exterior conduit into a series of annular plenum chambers, the plenum chambers and the openings in the baffle plates constituting the sole passage for the flow of combustion air through the exterior conduit.

Claim 8

A radiant tube heat exchanger as defined in claim 6 wherein an optimal ratio of the separation of an opening in the second baffle means from the heat exchange surface to the hydraulic diameter of such an opening is not less than one or greater than three.

Claim 9

A radiant tube heat exchanger as defined in claim 6 wherein an optimal hydraulic diameter of the openings in the second baffle means is not less than one-sixteenth inch or greater than one-fourth inch.

Claim 10

A radiant tube heat exchanger as defined in claim 6 wherein an optimal ratio of a distance between centers of the openings in the second baffle means to the hydraulic diameter of such an opening in the second baffle means is not less than two or greater than six.

Claim 11

A radiant tube heat exchanger as defined in claim 6 wherein an optimal spatial pattern of the openings in the second baffle means is diamond shaped.

Claim 12

A radiant tube heat exchanger as defined in claim 6 wherein the openings in the first said baffle means are substantially circular in shape.

Claim 13

A radiant tube heat exchanger as defined in claim 6 wherein the openings in the second baffle means are substantially circular in shape.

Claim 14

A radiant tube heat exchanger as defined in claim 1 wherein said baffle means comprises a series of baffles; further comprising a rod extending centrally through each baffle in the series and attached thereto for enabling the extraction as a unit of the series of baffles from the exhaust tube, thermally expansible sealing means on each baffle in the series of baffles along the portion thereof facing the injection end of the exhaust tube for sealingly engaging the heat exchange surface only in response to temperature above a predetermined temperature.

Claim 15

A controlled atmosphere radiant tube heating device comprising a fuel burner means having a heat output between 100, 000 and 800,000 BTU/hr., air intake means for injection of combustion air into the burner means, an enclosure adapted to confine a controlled atmosphere, a radiant tube within the enclosure, the radiant tube confining and being heated by combustion products from the burner means, an exhaust tube for conducting combustion products from the radiant tube, a length of the wall of the exhaust tube forming a heat exchange surface on each side thereof, an outer tube concentric with and surrounding the exhaust tube forming an exterior conduit for confining a flow of combustion air adjacent the heat exchange surface, means for directing the flow of combustion air into the exterior conduit at an inlet end thereof, means for directing the flow of combustion air from the exterior conduit at an outlet end thereof to the burner means, baffle means interior of the exhaust tube for producing a pressure drop not substantially greater than 0.1 inch of water across the exhaust tube, the baffle means having openings therein for directing jets of combustion products onto said length of the wall, the openings having hydraulic diameters not less than one-eighth inch and not greater than one-half inch, the ratio of separation of centers of mass of the openings to the hydraulic diameter of the openings being not less than two or more than seven, each baffle opening being separated from the adjacent heat exchange surface by a distance not less than the hydraulic diameter of the opening or more than 4 times the hydraulic diameter of the opening.

Claim 16

A controlled atmosphere radiant tube heating device comprising a fuel burner means having a heat output between 100, 000 and 800,000 BTU/hr., air intake means for injection of combustion air into the burner means, an enclosure adapted to confine a controlled atmosphere, a radiant tube within the enclosure, the radiant tube confining and being heated by combustion products from the burner means, an exhaust tube for conducting combustion products from the radiant tube, a length of the wall of the exhaust tube forming a heat exchange surface on each side thereof, an outer tube concentric with and surrounding the exhaust tube forming an exterior conduit for confining a flow of combustion air adjacent the heat exchange surface, means for directing the flow of combustion air into the exterior conduit at an inlet end thereof, means for directing the flow of combustion air from the exterior conduit at an outlet end thereof to the burner means, baffle means interior of the exhaust tube for producing a pressure drop not substantially greater than 0.1 inch of water across the exhaust tube, the baffle means having openings therein for directing jets of combustion products onto said length of the wall, the openings having hydraulic diameters not less than one-eighth inch and not greater than one-half inch, the ratio of separation of centers of mass of the openings to the hydraulic diameter of the openings being not less than two or more than seven, each baffle opening being separated from the adjacent heat exchange surface by a distance not less than the hydraulic diameter of the opening or more than 4 times the hydraulic diameter of the opening.

Claim 17

A radiant tube heat exchanger as defined in claim 14 wherein the exterior conduit contains second baffle means having openings therein for directing jets of the combustion air onto the heat exchange surface.

Claim 18

A radiant tube heat exchanger as defined in claim 15 wherein the second baffle means comprises a plurality of sections aligned such that one end of each section is closer than the other end to the inlet end of the exterior conduit, and wherein for each section one end is fixedly attached to either the exhaust tube or the outer tube while the other end of each section comprises thermally expansible means for sealingly engaging the wall of the other tube means.