Patent GB-1256720-A (GB)
IPC: A21B3/04
Filed: 1968-12-16
Abstract: 1,256,720. Bakers ovens. J. O. BONGARD. 16 Dec., 1968 [19 Dec., 1967], No. 59792/68. Heading A2A. A bakers or similar oven is heated by a plurality of closed steam-filled tubes each of which, in addition to circulating through the oven, includes a lower loop portion of annular form surrounding a cylindrical heat source which comprises a heat deflecting baffle adapted to be rotatable about the axis of the source, the baffle being so constructed that the amount of heat supplied to each loop can be regulated in accordance with the rotational position of the baffle. As shown, there are two heat sources 7, 8 and two sets of closed tubes 2<SP>1</SP>, 2<SP>2</SP>, 2<SP>3</SP> &c and 3<SP>1</SP>, 3<SP>2</SP>, 3<SP>3</SP> &c the former tubes having lower loops surrounding the source 7 while the latter tubes have lower loops surrounding the source 8. A space exists between each set of lower loops and the respective source excepting over an approximately 90 degree arc where there is located a heat deflecting baffle 14<SP>1</SP>, 14<SP>2</SP>, respectively, formed integrally with the respective source. Gases from burners 11<SP>1</SP>, 11<SP>2</SP> positioned at one end of each of the cylindrical sources are thus able to pass through the sources and return over their outer surfaces, to flues situated above the burners, excepting that they are excluded by the baffle from the arc in which the baffle is located. The maximum transfer of heat to the tube is effected when the baffles are in the position shown in Fig. 2, since the gases cannot reach the tangential portions of tube leaving the loops anyway, owing to screening baffles 13<SP>1</SP>, 13<SP>2</SP>, and the whole of the substantially annular portion of the loop is exposed to the returning gases. Rotation of the source in either direction reduces the heat transfer. By forming the deflecting baffles 14<SP>1</SP>, 14<SP>2</SP> helically, as shown in Fig. 1 where the amount of helical twist is shown to be equal to the arcuate extent of the baffle, i.e. approximately 90 degrees, the distribution of heat between the front and back of the oven can be varied by rotation of the heat sources either separately or together, the former enabling a different distribution to be obtained in the tubes 2<SP>1</SP>, 2<SP>2</SP>, 2<SP>3</SP> &c traversing the tops of three oven chambers 4<SP>1</SP>, 4<SP>2</SP>, 4<SP>3</SP> from that obtained in the bottoms of these chambers. Chambers 4<SP>1</SP> and 4<SP>3</SP> each have a cooking slab 5<SP>1</SP>, 5<SP>3</SP>, respectively, while the chamber 4<SP>2</SP> has an endless conveyer 6 for continuous baking. A moist atmosphere is maintained in each of the chambers by water channels 16<SP>1</SP>-16<SP>6</SP> which receive heat from the vertical portions of the closed tubes to evaporate the water. Water is supplied to the channels by pipes 17<SP>1</SP>-17<SP>6</SP> at a rate sufficient to maintain the desired atmosphere and keep the sides of the oven chamber relatively cool so that the loaves (or other products being baked) near the oven sides are not baked to a greater extent than those nearer the middle of the oven chambers.