GB2285739A

GB2285739A - Cooking oven vapour generator with blown burner

Info

Publication number: GB2285739A
Application number: GB9500750A
Authority: GB
Inventors: Mangina Franco Tassan
Original assignee: Zanussi Grandi Impianti SpA
Current assignee: Electrolux Zanussi Grandi Impianti SpA
Priority date: 1994-01-17
Filing date: 1995-01-16
Publication date: 1995-07-26
Also published as: ITPN940001U1; FR2715030A1; FR2715030B1; IT235007Y1; ITPN940001V0; ES1029911U; ES1029911Y; DE29500595U1; GB9500750D0

Abstract

The vapour generator of a cooking oven comprises a heat exchanger through which pass the combustion products from a blown gas burner (13) disposed in a position corresponding to a first end (12) of a combustion chamber (9). A second end (15) of the combustion chamber which is opposite to the first end (12) is connected to an outlet (11) by way of a collector (16) and tubes (10), in such a way that the combustion products flow from the blown burner (13) to the outlet (11), passing through the combustion chamber (9, 10) in a unidirectional mode. A turbulence generator (18) may be provided in the combustion chamber. <IMAGE>

Description

COOKING OVEN HAVING A VAPOUR GENERATOR WITH A BLOWN BURNER This invention relates to a vapour cooking oven, in particular of professional type, provided with an improved vapour generator of the type comprising a blown burner.

As is known cooling ovens of the above-mentioned type essentially comprise a casing which primarily accommodates a chamber or compartment for cooking the food and a vapour generator. The latter is capable of producing aqueous vapour at elevated temperature which is passed into the interior of the cooking compartment for processing the food. In particular the vapour is produced in the generator by means of a boiler containing water which is heated through a heat exchanger in which the combustion products from a gas burner of blown type are caused to flow. Such a heat exchanger generally comprises a combustion chamber associated with the burner, and a series of tubes for carrying the fumes from the combustion chamber to an outlet.

Normally the combustion chamber is substantially in the form of a cylinder with its axis horizontal, with one end open and an opposite end closed. The open end of the combustion chamber, at which the blown burner is axially disposed, communicates with the inlets of the tubes for the fumes, while the opposite end which is preferably curved is capable of deflecting through 1800 the flow of the burnt gases produced by the blown burner. In the combustion chamber therefore the burnt gases circulate with a flow which extends centrally from the burner to the abovementioned opposite wall, from which the gases flow back again towards the opposite end, and thus towards the tubes of the heat exchanger, with a substantially peripheral flow which surrounds the central flow in counter-flow relationship.That composite circulation of the combustion products requires the use of a combustion chamber which is of relatively large diameter, which in turn results in an undesirably large amount of space being occupied by the entire vapour generator, and thus the cooking oven.

In addition the above-mentioned reversal in the flow of the combustion products causes overheating of the burner and the adjacent support wall so that it is necessary to use expensive heat insulation and/or cooling means in order to minimise the damage to the various components including possible electronic and/or electromechanical control devices. In conclusion therefore the structure of the vapour generator is undesirably complicated.

The main aim of the present invention is that of providing a compact cooking oven, in particular with a vapour generator of a particularly simple and economical structure.

According to the present invention, there is provided a cooking oven comprising a cooking compartment capable of receiving water vapour from a vapour generator, the vapour generator comprising a boiler for water which can be heated by means of a heat exchanger through which pass the combustion products from a gas burner of blown type, said heat exchanger comprising a combustion chamber and a series of tubes which connect the combustion chamber to an outlet, the combustion chamber having a first end at which the blown burner is disposed, wherein the combustion chamber has a second end opposite to said first end, connected to said tubes by collector means in such a way that the combustion products flow from the blown burner to the outlet by passing in a unidirectional mode through the combustion chamber.

The features and advantages of the invention will be clearly apparent from the following description given solely by way of non-limiting example with reference to the accompanying drawings in which: Figure 1 is diagrammatic plan view in section of a cooling oven according to the invention; and Figure 2 is a diagrammatic view in longitudinal section of a preferred embodiment of the vapour generator provided in the oven shown in figure 1.

With reference to the drawings the cooking oven primarily comprises a casing 3 provided with a door 4 by means of which it is possible to gain access to a cooking chamber or compartment 5. The casing 3 also accommodates a vapour generator 6 having an outlet 7 for the vapour which communicates with the interior of the cooking compartment 5.

In particular the vapour generator 6 comprises a boiler 8 which is partially filled with water and from the top of which extends the outlet 7 for the water vapour. In known manner (not shown) the boiler 8 is preferably provided with suitable water connections for the feed of water, and with control means for automatically maintaining the level of the water in the boiler above a predetermined safety level.

The water in the boiler 8 can be heated by way of a heat exchanger which primarily comprises a combustion chamber 9 and a plurality of tubes 10 for carrying towards an outlet 11 the combustion products coming from the chamber 9. The combustion chamber 9 is formed by a substantially cylindrical tube which extends horizontally over the bottom of the vapour generator. The tube 9 has a first open end 12, at which is disposed a gas burner 13 of blown type, which for example is associated in per se known manner with a suitable blower 14.

In accordance with the invention the end 15 of the tube 9, which is opposite to the end 12, is connected to the tubes 10 and thus to the outlet 11 by means of a collector or manifold 16 or the like. On the other hand the end 12 of the combustion chamber 9 is in direct communication only with a chamber 17 which is separate from the outlet 11 and which accommodates the burner 13 and which is put under pressure by the blower 14.

Consequently the combustion products flow from the burner 13 to the outlet 11 by passing unidirectionally through the entire heat exchanger, in particular the combustion chamber 9. More precisely the combustion products flow along the combustion chamber 9, the collector 16, the tubes 10 and the outlet 11.

As has also been experimentally verified the unidirectional flow of the burnt gases along the combustion chamber makes it possible to design the latter with a flow section in respect of the tube 9 that is substantially reduced in comparison with the conventional constructions involving a flow reversal. Advantageously therefore the diameter of the combustion chamber 9 can be correspondingly reduced, thus reducing the overall dimensions of the entire vapour generator 6.

In addition since the combustion products in the chamber 9 are not diverted towards the burner 13, the latter and the adjacent components are subjected to relatively reduced thermal stresses. That results in enhanced reliability of the components which in addition do not require particular measures to be taken for thermal insulation thereof.

The general mode of operation of the cooking oven is substantially conventional and is not described in detail herein. It will be appreciated that the described oven may be the subject of many modifications which fall within the scope of the invention. For example the cooking compartment 5 may be of the per se known type for combined cooking of food with vapour and with forced convection.

In addition the interior of the combustion chamber 9 preferably accommodates turbulence-generating means 18 which are known per se and which are capable of suitably regulating the phenomenon of combustion in the chamber 9, minimising the emissions of noxious gases to the outlet 11.

Claims

1. A cooking oven comprising a cooking compartment capable of receiving water vapour from a vapour generator, the vapour generator comprising a boiler for water which can be heated by means of a heat exchanger through which pass the combustion products from a gas burner of blown type, said heat exchanger comprising a combustion chamber and a series of tubes which connect the combustion chamber to an outlet, the combustion chamber having a first end at which the blown burner is disposed, wherein the combustion chamber has a second end opposite to said first end, connected to said tubes by collector means in such a way that the combustion products flow from the blown burner to the outlet by passing in a unidirectional mode through the combustion chamber.

2. A cooking oven according to claim 1, wherein turbulence-generating means are accommodated in the combustion chamber.

3. A cooking oven constructed and arranged to operate substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.