Patent GB-707750-A (GB)
Title: Improvements in or relating to baking ovens
Inventor: WARRINGTON JAMES IRVINE DUDLEY
IPC: A21B1/48
Filed: 1951-06-14
Abstract: 707,750. Bakers' ovens. BAKER PERKINS, Ltd., May 30, 1952 [June 14, 1951], No. 14086/51. Class 51 (2) A baking oven of the travelling conveyer type having indirect heating means within the baking chamber located both above and below the run of the conveyer comprises means for abstracting some of the oven atmosphere from the baking chamber and redistributing it to the chamber through orifices located above the heating means above the conveyer run and below the heating means below the conveyer run to discharge therethrough over substantially the whole area of the run of the conveyer lying between the heating means. The heating of the oven shown is effected by upper and lower sets 9, 10 of radiant heating tubes 13 the sets 10 below the conveyer 2 being inclined as shown in Fig. 2 whilst the sets 9 are inclined in the opposite direction, i.e. upwardly towards the left side of Fig. 2. Heated gases from a transversely located heater tube 15 containing a heating element, e.g. a gas or oil burner are fed to headers 11 via a manifold 14 and after passing through the tubes 13 are led through headers 12 to manifolds 16 which are coupled to a duct 17 which conveys the gases back to the tube 15, circulation being maintained by a fan 18 in known manner. Oven atmosphere is withdrawn from the baking chamber 1 through a series of ducts 20 extending along both sides of the chamber and connecting via longitudinal manifolds 21 and associated headers 22 to a chamber 23 at the top of the oven which contains a fan 24 for circulating the atmosphere, i.e. air, through the redistribution system. This system comprises a duct connecting the chamber 23 to a transverse duct 25 which extends across the top of the oven and has damper controlled outets in its floor these outlets allowing the hot air to enter boxes 27 which are located above the upper heating sets 9 and cover substantially the whole area of the upper surface of the conveyer run 2. The boxes are provided with orifices which direct the air downwardly on to the goods being baked. The duct 25 connects, via a passage 28, with vertical manifolds 29 disposed on each side of the oven these manifolds being joined at their lower ends by a transverse duct which has provided in its floor damper controlled outlets communicating with boxes 30 which are similar to those at 27 but are located under the lower heating sets 10 and cover substantially the whole area of the under surface of the run 2. These boxes are provided with orifices for directing the air upwardly. The orifices in the boxes 27, 30 may be merely apertures or may be equipped with vertical, Fig. 5B, or inclined nozzles. In a modified form of oven the tubes 13 are not inclined but are parallel to the direction of feed of the conveyer 2 the orifices in the boxes 27, 30 being inclined and not disposed transversely of the oven in a straight line as is shown in Fig. 2. The gases passing through the tubes 13 need not necessarily be recirculated but may be discharged to atmosphere. Although Fig. 1 shows headers 11 abutting, alternatively the relative positions of headers 11, 12, of adjacent sets 9 or 10, may be such that the header 12 of one set is adjacent the header 11 of the next set so that the heated gases flow through the tubes 13 in the same direction. In an alternative oven heating arrangement the heating tubes 13 may themselves contain heating elements, for example electric heating elements, the leads for which are accommodated in tubes similar to headers 11, 12. Further heating medium circulated to and from the tubes 13 via headers 11, 12, may be a suitable liquid such as oil. As a further alternative gas burners can be located in the headers themselves for heating the medium circulated through the heater tubes. Specifications 391,128 and 555,947 are referred to.