Oven

Abstract

The invention relates to an oven with a thermally insulated housing (1) which receives a heat store (2) connected to a charging circuit (4) and a baking space (3) provided above the heat store (2), with a heating circuit comprising a distributor channel (6) and a collector channel (7), the heat exchanger of said heating circuit flowing through the heat store (2), and with heating lines which enclose the baking space (3) transverse to its longitudinal extent and which extend, connected in parallel, between the distributor channel (6) and the collector channel (7). In order to create advantageous heating conditions, it is proposed that the heating circuit is subdivided into a plurality of parallel heating circuit portions (5) distributed over the longitudinal extent of the baking space (3), which heating circuit portions each have, on the side of the collector channel (7), a fan (10) which is flow-connected on the pressure side to the portion of the heat store (2) belonging to the respective heating circuit portion (5), and that the heating lines form, at least in some portions, adjacent tubes (8) with a rectangular cross section.

Description

[0001] oven

[0002] Technical area

[0003] The invention relates to an oven with a heat-insulated housing which accommodates a heat accumulator connected to a charging circuit and a baking chamber provided above the heat accumulator, with a heating circuit comprising a distribution channel and a collecting channel, the heat carrier of which flows through the heat accumulator, and with heating lines which enclose the baking chamber transversely to its longitudinal extent and which run in parallel between the distribution channel and the collecting channel.

[0004] State of the art

[0005] In order to operate an oven with solar energy that meets the heat management requirements placed on ovens for commercial and industrial use, it is known (AT 511 203 B1) to provide a heat accumulator that can be charged by a solar collector in a thermally insulated housing, in which the baking chamber located above the heat accumulator is heated by means of a heating circuit connected to the heat accumulator. For this purpose, the heating lines laid on a fireclay lining are connected in parallel between a distribution line and a collecting line, so that the circulating heat carrier of the heating circuit is heated in heat exchange with the heat accumulator in order to supply the heating lines via the distribution line fed by the heat accumulator. The heated heat carrier flowing through the heating lines heats the fireclay lining of the baking chamber and consequently the baking chamber.The cooled heat transfer medium is returned to the heat storage tank via the collecting line. The heat storage capacity of the fireclay lining is utilized to ensure a largely even heat distribution within the baking chamber, but with the disadvantage that the heat distribution cannot be influenced. While the baking temperature within the baking chamber can be controlled by the flow velocity of the heat transfer medium in the heating lines, this control is comparatively slow due to the heat-storing fireclay lining.

[0006] DE 2213749 A1 also discloses a stove with a baking chamber that can be heated using waste heat from a heat storage unit. For this purpose, a heating circuit is provided that runs over the heat storage unit, which has an air duct surrounding the baking chamber and a fan that circulates the air heated in the storage unit around the baking chamber. However, this known heating circuit does not allow the heating of the baking chamber to be controlled according to a predefined temperature profile.

[0007] DE 1234153 B, which shows a baking oven arranged above a boiler for hot water preparation, can be considered part of the extended state of the art. The boiler is fed with flue gases from a side furnace. A portion of the flue gases drawn in by the boiler and the baking oven is mixed with the hot flue gases from the furnace in a mixing chamber before the flue gases are circulated through the boiler and the baking oven. The flue gases are distributed between the boiler and the baking oven via a control valve.

[0008] DE 2415509 B1 discloses a circulating oven with two hearth groups, each of which has radiators designed as flat hollow bodies extending across the entire width, above and below. This oven is heated by flue gases supplied to the radiators of the lower hearth group via a supply duct and to the radiators of the upper hearth group via ducts connected to the supply duct. A control flap distributes the flue gases between the two hearth groups. Separate fans are provided for the return of the flue gases to the supply duct for each hearth group.A comparable state of the art results from DE 3909365 A1 on the one hand and from DE 102022106372 A1 on the other hand, because only several baking chambers arranged one above the other are heated by means of flue gases from a combustion chamber, which are circulated through heating channels arranged above and below the baking chambers and running in the longitudinal direction of the oven.

[0009] In order to heat different baking chambers differently, according to DE 19546641 A1, the heating ducts of different baking chambers can be supplied with different flue gas quantities via at least one control flap. The baking chambers are not divided into different heating sections.

[0010] DE 2829910 A1, in turn, shows the heating of several stacked baking chambers with flue gases from a combustion chamber, whereby each baking chamber can be supplied with the flue gases through a separate flue gas supply duct. To ensure sufficient operation with a single fan, the flue gas supply ducts are controlled by means of control flaps.

[0011] Description of the invention

[0012] The invention is therefore based on the object of designing an oven with a heating circuit connected to a heat accumulator in such a way that the heat extracted from the heat accumulator can be advantageously used for the controlled heating of the baking chamber according to a predeterminable temperature profile.

[0013] Starting with an oven of the type described above, the invention achieves the stated object by dividing the heating circuit into several parallel heating circuit sections distributed along the length of the baking chamber. Each of these sections has a fan on the side of the collecting duct, which is fluidly connected on the pressure side to the section of the heat accumulator associated with the respective heating circuit section. Furthermore, the heating lines form, at least in sections, adjacent tubes with a rectangular cross-section. The division of the heating circuit into several parallel heating circuit sections, each equipped with a fan and each associated with a corresponding section of the heat accumulator, allows for section-by-section controlled heating of the baking chamber in order to easily ensure a predetermined temperature profile within the baking chamber. The heating circuit sections can be controlled independently of one another.

[0014] Since the heating pipes enclosing the baking chamber between the distribution pipe and the collecting pipe are formed from rectangular cross-section pipes that are at least partially flat against one another, the pipe walls facing the baking chamber create continuous heating surfaces that ensure effective heating of the baking chamber. With a suitable selection of materials for the heating pipe pipes, these pipes could themselves form the surface of the baking chamber. However, it is generally more economical for the baking chamber to have a lining covering the heating pipe pipes, so that only temperature resistance and thermal conductivity need to be considered with regard to the pipe material.Stainless steel plates or fireclay plates with a comparatively low plate thickness are particularly suitable as baking chamber lining, because this baking chamber lining only has to meet the requirements placed on a baking chamber surface.

[0015] In order to create simple design requirements for controlling the heat supplied to the baking chamber, the fans can each be connected via a flow duct to a pressurization chamber upstream of the heat accumulator, with bypass lines branching off from the flow ducts into the distribution duct and controllable via a control device. This measure allows the gaseous heat transfer medium flow sucked into the distribution duct to be divided into a heated partial flow that passes through the heat accumulator and an unheated partial flow that bypasses the heat accumulator. These partial flows, which recombine to form the overall flow in the distribution duct, result in a mixed temperature for the combined overall flow depending on the ratio of the partial flows. This enables easy adjustment of the temperature of the heat transfer medium acting on the heating lines without having to control the individual fans.

[0016] If the bypass lines are connected to the flow channels via a control valve, the temperature conditions in each heating circuit section can be controlled independently, providing a particularly simple way to specify a temperature profile in the baking chamber that is tailored to the respective baking process. Simple control flaps can be used as control valves. Depending on their pivoting position, they divide the fan flow into two partial flows: one through the heat accumulator and one bypassing the heat accumulator.

[0017] Brief description of the invention

[0018] The drawing shows an example of the subject matter of the invention.

[0019] Fig. 1 shows an oven according to the invention without heat-insulating housing in a schematic, partially opened plan view,

[0020] Fig. 2 shows the oven according to Fig. 1 in a partially opened side view, Fig. 3 shows a section along the line lll-lll of Fig. 1, but with an indicated heat-insulating housing and

[0021] Fig. 4 shows a section along the line IV-IV of Fig. 3.

[0022] Ways to implement the invention

[0023] A baking oven according to the invention comprises a heat-insulating housing 1 which accommodates a heat accumulator 2 and a baking chamber 3 arranged above the heat accumulator 2. This heat accumulator 2 is connected to a charging circuit 4, indicated by a dash-dotted line in Fig. 3, which is preferably operated using solar energy, for example by solar collectors or photovoltaic panels, although this is not mandatory. The heating circuit supplied by the heat accumulator 2 is divided into several parallel heating circuit sections 5, each of which comprises heating lines in the form of tubes 8 with a rectangular cross-section, which are connected to a distribution channel 6 and a collecting channel 7 and enclose the baking chamber 3 transversely to its longitudinal extent. These usually metallic tubes 8 lie flat against one another and thus form a continuous heating surface with their walls facing the baking chamber 3.The pipes 8 are covered on the side of the heating surface by a baking chamber lining 9 in order to be able to meet the requirements regarding the baking chamber surface in a simple manner.

[0024] The individual parallel heating circuit sections 5 are each provided with a fan 10, which is fluidly connected to the collecting duct 7 on the suction side and pressurizes a flow duct 11 on the pressure side, which is connected to a pressurization chamber 12 upstream of the heat accumulator 2. Via the pressurization chamber 12, the gaseous heat transfer medium is distributed to the sections of the heat accumulator 2 corresponding to the heating circuit sections 5, so that the heat transfer medium flowing through the heat accumulator 2 is heated and fed to the distribution duct 6 at an appropriate temperature in order to heat the baking chamber 3 to the desired baking temperature using the pipes 8 of the heating lines and to maintain it at this temperature or to ensure a predetermined temperature profile.

[0025] To control the temperature of the heat transfer medium in the distribution channel 6, a bypass line 13 branches off from the flow channel 11 of the heating circuit sections 5 in the area of ​​the admission chamber 12, which bypass line opens into the distribution channel 6 and can be controlled by a control device 14, so that by the position of the control device 14 the heat transfer medium flow of the individual heating circuit sections 5 can be divided into a portion 16 flowing through the heat accumulator 2 through channels 15 and a portion 17 bypassing the heat accumulator 2, which portion is mixed back into the portion 16 flowing through the heat accumulator 2 after the heat accumulator 2 in the area of ​​the distribution channel 6, as can be seen from Fig. 3.

[0026] Depending on the distribution, a predetermined temperature can be set for the heat transfer medium flowing through the pipes 8, whereby the full heating capacity of the heat storage unit 2 can be utilized when the bypass line 13 is closed. When the heat storage unit 2 is blocked and the bypass line 13 is open, the heat transfer medium conveyed in the circuit is not heated. Due to these measures, the flow velocity of the heat transfer medium flowing through the pipes 8 does not need to be changed to control the temperature, so the fans 10 can operate at a constant speed at a favorable operating point.

[0027] Control valves, in particular control flaps 18, can be used as the control device 14. According to Fig. 4, a common control flap 18 is indicated for all heating circuit sections 5, which creates simple design requirements. However, if the bypass lines 13 are each connected to the flow channels 11 via a flow valve, it is possible to set a predeterminable temperature profile across the length of the baking chamber 3 in order to accommodate specific baking requirements.

[0028] In the illustrated embodiment, the heat accumulator 2 is made of a particularly suitable concrete, through which the channels 15 for the gaseous heat transfer medium run in a meandering pattern. However, the invention is not limited to this embodiment, because the essential point is to provide a heat accumulator with sufficient heat capacity to adequately heat the baking chamber 3. Particularly simple manufacturing conditions for a suitable heat accumulator are achieved by using sand as the heat accumulator. The sand block forming the heat accumulator is interspersed with corresponding channels for the heat transfer medium, with the connection conditions remaining essentially the same.

Claims

Patent claims 1. Baking oven with a thermally insulated housing (1) which accommodates a heat accumulator (2) connected to a charging circuit (4) and a baking chamber (3) provided above the heat accumulator (2), with a heating circuit comprising a distribution channel (6) and a collecting channel (7), the heat transfer medium of which flows through the heat accumulator (2), and with heating lines enclosing the baking chamber (3) transversely to its longitudinal extent, which run in parallel between the distribution channel (6) and the collecting channel (7), characterized in that the heating circuit is divided into several parallel heating circuit sections (5) distributed over the longitudinal extent of the baking chamber (3), each of which has a fan (10) on the side of the collecting channel (7) which is fluidly connected on the pressure side to the section of the heat accumulator (2) belonging to the respective heating circuit section (5), and in that the heating lines at least in sections comprise tubes (8) which are adjacent to one another and have a rectangular cross-section form.

2. Baking oven according to claim 1, characterized in that the baking chamber (3) has a baking chamber lining (9) covering the pipes (8) of the heating lines.

3. Baking oven according to claim 1 or 2, characterized in that the fans (10) are each connected by a flow channel (11) to a loading chamber (12) arranged upstream of the heat accumulator (2) and that bypass lines (13) branch off from the flow channels (11) opening into the distribution channel (6) and controllable via a control device (14).

4. Baking oven according to claim 3, characterized in that the bypass lines (13) are each connected to the flow channels (11) by a control valve.

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