Improved steam generator

Abstract

Steam generator (1) for an oven, which includes: at least two groups (G1, G2) of swath irons (2) arranged one behind the other.

Description

[0001] The present invention relates to an improved steam generator for an oven, in particular a rack oven for bakeries, large bakeries or their branches.

[0002] Bakeries, large-scale bakeries, and their branches often use large ovens, such as rack ovens, to bake large quantities of goods. Rack ovens consist, among other things, of a baking chamber into which trolleys (racks) on rollers can be inserted, on which several baking trays can be stacked one above the other.

[0003] These ovens often use steam generators, also known as steam generators or steam generators. These are sprayed with liquid water when heated to generate steam at the start of baking and during any subsequent baking stages.

[0004] Dough pieces, such as yeast dough, that come from a proofing room or cooling chamber have a lower surface temperature than the oven temperature. Water vapor introduced into the baking chamber condenses on the cool surface of the dough pieces, forming a thin film of water. This keeps the surface of the baked goods elastic, allowing the volume and surface area of ​​the dough pieces to increase during baking without the surface tearing or cracking.

[0005] Furthermore, the addition of steam during the baking process, especially for bread, results in crispy crusts, which is desirable for many types of bread. The steam is also responsible for the bread's crust turning brown and developing a certain sheen.

[0006] For example, the prior art includes document AT 390 715 B, which discloses that a baking chamber and a fermentation chamber are supplied with steam via a steam line from a steam generator.

[0007] Document DE 2123186 B2 also discloses an oven with a steam generator, wherein the steam generator consists of steel boxes or pipes into which water is sprayed and which can be heated together with the baking chambers. The steam generator can be operated with a water valve.

[0008] Furthermore, document EP 2 919 587 B1 is known from the prior art. This document discloses an oven with a steam generator, wherein water, which is tested for steam iron, is pressurized with compressed air.

[0009] Typically, steam irons, i.e., parts of the steam generator, are heated by convection in the oven or by radiant heat, and then liquid water is dripped or sprayed onto them. Due to the necessary heating of the water (from the temperature at which it comes out of the tap to the oven temperature) and the enthalpy of vaporization of water, the steam irons cool down after each steaming process (as they transfer heat to the water being vaporized). Therefore, they must be reheated by the radiant heat or convection of the oven before another steaming process can take place. If several steamings are to be carried out per baking process, the baking time may be extended, as the steam irons must first be brought back up to the appropriate temperature after each steam burst before another steaming process can occur.

[0010] It is therefore an object of the present invention to provide an improved steaming apparatus which, compared to the prior art, has a higher performance and with which more steaming processes can be carried out within a certain period of time.

[0011] This problem is solved by a steam generator according to claim 1 and an oven according to claim 10. Further advantageous embodiments of the present invention are the subject of the dependent claims.

[0012] A steam generator according to the invention for an oven comprises at least two groups of steam irons arranged one behind the other.

[0013] The steam generator can, for example, be located in the rear wall of the baking chamber, with two groups of steam irons arranged one behind the other on the rear wall.

[0014] This allows the water to be distributed across more steam irons, as there are more steam irons in the oven compared to a situation where only one group of steam irons (for example, on the back wall) is located. Furthermore, this arrangement is very space-saving, since a group of steam irons is very flat.

[0015] The release of vapors from evaporated water results in less cooling when two groups of vaporizing irons are arranged one behind the other, compared to a single layer of vaporizing irons. Experiments have shown that under normal conditions in a rack furnace, when two or more groups of vaporizing irons are present, they cool down by 50°C to 60°C less when exposed to liquid water compared to a single layer of vaporizing irons.

[0016] This is further enhanced by the fact that the two groups of steam irons are preferably arranged close together – preferably with a distance of no more than 10 cm, more preferably no more than 8 cm, more preferably no more than 5 cm, and more preferably no more than 3 cm. This allows heat to be exchanged between these two groups, primarily through convection and thermal radiation. If one group of steam irons cools down, it is heated not only by the oven air but also by the other group of steam irons. Furthermore, this allows a larger number of steam irons to be heated by a single airflow without the need for redirection. Because the at least two groups of steam irons exchange heat with each other, all steam irons are heated evenly without any heat being transferred to surrounding parts.

[0017] A group of swath irons preferably comprises at least 5 swath irons, more preferably at least 8 swath irons, even more preferably at least 10 swath irons, and even more preferably at least 12 swath irons.

[0018] Preferably, at least two groups of swath irons are arranged next to each other, and preferably two further groups are arranged behind these two groups of swath irons.

[0019] This allows for better distribution of the water, so that the individual steam irons cool down even less.

[0020] Preferably, two groups of swath irons are arranged next to each other, two more groups of swath irons are arranged below them, and behind each group of swath irons, preferably, another group of swath irons is arranged.

[0021] By dividing the system into eight groups of swath irons, water can be distributed even better on each individual swath iron, resulting in each individual swath iron group cooling down even less after a swathing process.

[0022] Preferably, the total weight of all steam irons in a conventionally sized oven is at least 500 kilograms, more preferably at least 600 kilograms, and even more preferably at least 800 kilograms. The steam irons are generally made of steel. Tests have shown that a minimum mass of 600 kilograms for the steam irons results in a particularly advantageous temperature profile, as this minimizes cooling of the steam irons during the steaming process.

[0023] Preferably, a swath inlet channel is provided above the swath irons, which is designed to receive liquid, and this swath inlet channel preferably extends over the entire width and / or depth of all swath irons or swath iron groups.

[0024] This allows for an even better distribution of the liquid water, which is delivered to the steam inlet channel via a water supply device.

[0025] Preferably, at least two passage openings are provided in the swath inlet channel, which are adapted to direct water onto swath irons of the groups located below the swath inlet channel.

[0026] The swath irons themselves preferably also have openings through which liquid water flows from top to bottom over the groups of swath irons and evaporates along the way. A further opening is preferably provided in the swath inlet channel for each group of swath irons. Thus, if there are four groups of swath irons below the swath inlet channel, four openings are provided accordingly.

[0027] Preferably, at least two downpipes are provided at the flue inlet trough, adapted to direct water to the flue irons of the groups not located directly below the flue inlet trough. This is particularly advantageous when at least two groups of flue irons are arranged side by side, with two more groups of flue irons below them, and another group of flue irons behind each group. This ensures that all groups of flue irons receive the same amount of water, resulting in a temperature profile that is as homogeneous as possible across all groups. It also prevents water from evaporating completely on the upper flue irons, leaving none to reach the lower ones. Therefore, water is supplied directly to the lower groups of flue irons from the flue inlet trough.

[0028] Furthermore preferably, the diameter of the at least two downpipes is larger than the diameter of the at least two passage openings - and the at least two downpipes are further preferably located further away from a central axis of the steam inlet channel than the at least two passage openings.

[0029] Advantageously, the water can be supplied via a water supply device in the middle of the steam inlet channel.

[0030] This ensures that the downpipes located further from the center of the flue inlet channel receive the same amount of water as the at least two openings located closer to the center. Since the water entering the flue in the center of the channel first reaches the openings, which have a smaller diameter than the downpipes, a consistent flow of water is maintained to both the downpipes and the openings.

[0031] An oven according to the invention has a burner which is adapted to be heated with oil or gas. It also has a steam generator according to the present invention.

[0032] With an oil / gas burner, temperatures of approximately 900 °C can be reached in the baking chamber (and thus also on the steam irons) (with an electric heater, temperatures of approximately 500 °C can be reached) - in conjunction with the steam apparatus according to the invention, the effect of the shortened heating times of the steam irons is particularly pronounced at the higher temperatures with an oil / gas burner.

[0033] Furthermore, the oven preferably has a ventilation device which is adapted to direct the airflow towards the burner and to direct the heated air into a baking chamber of the oven and to the steam generator.

[0034] Preferably, a flow path is also provided between the steam generator and the baking chamber, which is preferably as short as possible so that steam from the steam generator can reach the baking chamber as quickly as possible.

[0035] Preferred embodiments of the present invention are described in more detail below with reference to the accompanying figures. Fig. Figure 1 shows an isometric view of a steam generator according to the invention. Fig. Figure 2 shows an oven with a corresponding baking chamber. Fig. Figure 3 shows the arrangement of a steam generator in an oven. Fig. Figure 4 shows an isometric view of a steam generator according to the invention, which is arranged on the rear wall of an oven. Fig. Figure 5 shows a flow pattern of water in a steam apparatus according to the invention. Fig. Figure 6 shows a top view of the swath apparatus (although covered), therefore showing a view of the swath inlet channel. Fig. Figure 7 shows a top view of the swath apparatus, with the swath inlet channel removed. Fig. Figure 8 shows a top view of the groups of swath irons, with the swath inlet channel removed here as well.

[0036] In Fig. Figure 1 shows a swath-forming apparatus according to the invention. It can be seen that eight groups G11, G12, G13, G14 (collectively G1), G21, G22, G23, G24 (collectively G2) of swath irons are arranged, with two groups of swath irons always arranged one behind the other (of the rear groups, only groups G22 and G24 are shown here). Above the swath irons is a swath inlet trough 3, which is connected to the lower four groups G13, G23 (not shown here), G14 and G24 by an injection pipe 4a (not shown here), 4b (not shown here), 4c and 4d, respectively. Water can thus flow directly from the swath inlet trough 3 to the lower groups of swath irons G13, G14, G23, G24.

[0037] Fig. Figure 2 shows a front view of an oven B. A baking chamber R is visible, which can be closed with a door T. A cover A is located on the rear wall of the oven B, which covers the steam generator 1 (not shown here).

[0038] In Fig. Figure 3 shows a view in which oven B is also shown from the front, but the cover A (not shown here) has been removed. Several steam irons 2 are present, arranged in groups G11, G12, G13, and G14. The groups G21, G22, G23, and G24 behind them are not visible in this illustration.

[0039] Fig. Figure 4 shows an isometric partial view of the steam generator 1, located in oven B (not shown in its entirety). This illustration clearly shows that behind steam generator group G11 is another group, G21, and behind steam generator group G13 is another group, G23. Steam generator groups G12 and G14 are also visible, but the groups G22 and G24 behind them are not shown in this illustration. Above steam generator groups G11, G12, G21, and G22 is a steam inlet channel 3, in the center of which is a water supply device 5 through which water can be introduced into the steam inlet channel 3. Next to the steam generators of groups G11 and G21 are the downpipes 4a and 4d, which are intended to supply steam generator groups G13 and G23 with water, respectively.This ensures that water from the swath inlet channel also directly supplies the four lower swath iron groups G12, G14, G23 and G24 (group G24 not shown in this view).

[0040] Fig. Figure 5 shows another partial view of the swath apparatus 1 from the front. Here, the flow path of the water is particularly evident. Water is fed into the swath inlet trough 3 via the water supply device 5 and flows directly onto the swath irons of the two groups G11 and G12. Two downpipes 4a and 4c are also shown, which supply the swath iron groups G13 and G14 with water. Further downpipes are also provided for the swath iron groups G23 and G24 (not shown here), but these are not depicted in this view.

[0041] Fig. Figure 6 shows an isometric view from above of an oven B according to the present invention. The swath apparatus 1 is only partially visible here – some swath irons 2 are visible. However, the swath inlet trough 3 is shown in more detail from above, with a water supply device 5 in its center. Water outlet openings 6a, 6b, 6c, and 6d are also shown, designed to drip water onto the swath irons below. Furthermore, downpipes 4a, 4b, 4c, and 4d are provided for the lower groups of swath irons (not shown here). These downpipes are located further from the center of the swath inlet trough 3 and also have a larger diameter compared to the openings 6a, 6b, 6c, and 6d – these are intended to direct water onto the swath irons below.

[0042] Fig. Figure 7 shows a top view of an oven B according to the invention, although the steam inlet channel is not shown. The arrangement of several steam irons 2, 2', 2'' and 2''' is clearly visible, all arranged at the same height. Further steam irons 2'''' and 2''''' are visible below. Next to the steam irons 2, 2', 2'' and 2''', downpipes 4a, 4b, 4c and 4d are provided, which are intended to direct water to the steam iron groups below. It is evident that each of the steam irons 2, 2', 2'' and 2''', as well as 2'''' and 2''''', has a through-opening 7, 7', 7'', 7'''' and 7'''''.Water can thus flow from one steam iron to the next, and the opening of the lower steam iron is positioned on the opposite side, so that a flow is established across the entire surface of all steam irons 2, 2', 2'', 2''', 2'''', and 2'''''', allowing for evaporation. This ensures that all steam irons 2, 2', 2'', 2''', 2'''', and 2''''' are exposed to water and can therefore achieve their evaporation effect. This results in a very homogeneous temperature distribution and minimal cooling during the steaming process, so that the steam irons 2, 2', 2'', 2''', 2'''', and 2''''' can be quickly brought back up to operating temperature.

[0043] Fig. Figure 8 is another top view of the groups of swath irons (similar to in Figure 8). Fig.7), where the inlet channel has again been removed. Here, the path of the oven's circulating air becomes particularly evident; it flows from a side wall S to the steam generator 1, and is then directed into the baking chamber through a perforated plate L (ventilation device).

[0044] The present invention is not limited to the embodiments shown.

[0045] Other geometric arrangements of the swath irons are also possible; there can also be more than eight groups of swath irons. An asymmetrical arrangement of the swath iron groups would also be possible, for example, an arrangement of six swath iron groups, with two in a first row and one in a second row. In this case, two swath iron groups are again arranged one behind the other.

[0046] The water distribution can also be done differently; for example, the swath iron groups could be sprayed by separate spray nozzles. Reference symbol list 1 steam generator 2, 2', 2'', 2''', 2'''', 2'''' Swath iron 3. Steam intake channel 4a-d downpipe 5 Water supply device 6a-d Water outlet opening 7, 7', 7'', 7''', 7'''', 7'''' Passage opening B oven A cover T Door of oven R Backraum R Backraum L ventilation system G11 Group 1 G12 Group 2 G13 Group 3 G14 Group 4 G21 Group 5 G22 Group 6 G23 Group 7 G24 Group 8

Claims

[1] Steam generator (1) for an oven, comprising: at least two groups (G1, G2) of swath irons (2) arranged one behind the other. [2] Swath apparatus (1) according to claim 1, wherein the at least two groups (G1, G2) of swath irons (2) are arranged with a distance of a maximum of 10 cm, preferably a maximum of 8 cm, further preferably a maximum of 5 cm, and even more preferably a maximum of 3 cm from each other. [3] Swath apparatus (1) according to claim 1 or 2, wherein at least two groups (G11, G12) of swath irons (2) are arranged side by side, and at least two further groups (G21, G22) are arranged behind them. [4] Swath apparatus (1) according to one of the preceding claims, wherein at least two groups (G11, G12) of swath irons (2) are arranged side by side, at least two further groups (G13, G14) of swath irons are arranged below them, and behind each group (G11, G12, G13, G14) of swath irons (2) a further group (G21, G22, G23, G24) of swath irons (2) is arranged. [5] Swath apparatus (1) according to one of the preceding claims, wherein the total weight of all swath irons (2) is at least 500 kg, preferably at least 600 kg, more preferably at least 800 kg. [6] Swath apparatus (1) according to one of the preceding claims, wherein a swath inlet channel (3) is provided above the swath irons (2), which is designed to receive liquid, wherein the swath inlet channel (3) preferably extends over the entire width and / or depth of all swath irons (2). [7] Swath apparatus (1) according to claim 6, wherein at least two passage openings (7, 7') are provided in the swath inlet channel (3) which are adapted to direct water onto swath irons (2, 2' ,2'', 2''') of the groups (G11, G12, G21, G22) located below the swath inlet channel (3). [8] Swath apparatus (1) according to claim 6 or 7 relating to claim 4, wherein at least two downpipes (4a, 4b, 4c, 4d) are provided at the swath inlet channel (3) which are adapted to direct water onto swath irons (2, 2', 2'', 2''') of the groups (G13, G14, G23, G24) not located directly under the swath inlet channel (3). [9] A steam generator (1) according to claims 7 and 8, configured such that water can be supplied through a water supply device (5) in the center of the steam inlet channel (3), and wherein the at least two downpipes (4a, 4b, 4c, 4d) are located at a greater distance from a central axis of the steam inlet channel (3) than the at least two passage openings (7, 7'), wherein the diameter of the at least two downpipes (4a, 4b, 4c, 4d) is larger than the diameter of the at least two passage openings (7, 7'). [10] Oven (B) comprising a burner adapted to be heated with oil or gas or electricity and a steam apparatus (1) according to any one of claims 1 to 9. [11] Oven (B) according to claim 10, further comprising a ventilation device (L) which is adapted to direct air towards the burner and to direct the heated air into a baking chamber (R) of the oven (B) and to the steam apparatus (1). [12] Oven (B) according to claim 10 or 11, wherein a flow path is provided between the steam apparatus (1) and the baking chamber (R).

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