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EP-4525623-B1 - METHOD FOR CONTROLLING A TUNNEL OVEN AND TUNNEL OVEN WITH FLOW CONTROL

EP4525623B1EP 4525623 B1EP4525623 B1EP 4525623B1EP-4525623-B1

Inventors

  • VEROUDEN, FRANCISCUS QUIRINUS FREDRIK
  • VAN WEZEL, MICHEL MARTINUS WILLEM
  • REULING, Mathijs Cornelis Theodorus
  • KOKKOTI, Maria

Dates

Publication Date
20260506
Application Date
20230515

Claims (15)

  1. A tunnel oven (1) for the preparation of food product, in particular dough products, wherein the tunnel oven comprises: a tunnel oven entrance (5), a tunnel oven exit (6) and a baking zone (3') inside said tunnel oven between the tunnel oven entrance and the tunnel oven exit, a transport device (7) configured for transporting food products (9) through the tunnel oven entrance, the backing zone and the tunnel oven exit, a heating source arranged for providing heat to food products in the baking zone, a pretreatment zone (4') arranged between the baking zone and the tunnel oven entrance, wherein the pretreatment zone comprises an injector (10) configured for injecting a pretreatment agent into the pretreatment zone, an air exhaust (2) configured for extracting air from the baking zone, wherein the air exhaust comprises a flow regulator (15, 18), characterized in that the air exhaust further comprises a sensor (16, 16', 16'') for detecting the presence and/or an amount of pretreatment agent in the air exhaust, and wherein the tunnel oven further comprises a control device (17) configured for receiving a signal from the sensor, and configured for controlling the flow regulator in the air exhaust based on said signal.
  2. The tunnel oven according to claim 1, wherein the flow regulator comprises an exhauster, preferably a motor-driven fan (15), and/or a regulating valve (18).
  3. The tunnel oven according to claim 1 or 2, wherein the sensor is arranged in a duct (20) of the air exhaust, between the flow regulator and a connecting opening of said duct into the baking zone.
  4. The tunnel oven according to claim 1, 2 or 3, wherein the sensor comprises a dew point sensor, a humidity sensor and/or a combination of a wet-bulb temperature sensor and a dry-bulb temperature sensor.
  5. The tunnel oven according to any one of the claims 1 - 4, wherein the pretreatment zone (4') comprises an air resistance inducing unit configured for providing a resistance against air flow from the tunnel oven entrance, through the pretreatment zone, towards the baking zone.
  6. The tunnel oven according to claim 5, wherein the pretreatment zone comprises a bottom wall, a top wall and two side walls which surround a part of the transport device that is configured for transporting the food products through the pretreatment zone of the tunnel oven, wherein the air resistance inducing unit comprises at least one baffle or curtain (41, 41', 42), wherein said at least one baffle or curtain is arranged to extend in a direction substantially perpendicular to a transport direction of the transport device, preferably wherein said at least one baffle or curtain is connected to said top wall, and wherein said at least one curtain extends from the top wall towards said part of the transport device.
  7. The tunnel oven according to claim 6, wherein said at least one baffle or curtain comprises a cut-out (53) at the side facing away from the top wall, wherein the curtain part adjacent to said cut-out reaches to a position near or touching an upper side of the transport device.
  8. The tunnel oven according to claim 7, wherein said cut-out in said at least one baffle or curtain is configured to allow a substantially un-obstructed passage of the dough products and/or holders (8) for the dough products, such as baking tins, and/or wherein said cut-out is configured such that a gap between an edge the at least one curtain in the cut-out and the upper side of said transport device is in a range of 80 - 140 mm.
  9. The tunnel oven according to any one of the claims 6, 7 or 8, wherein said at least one curtain comprises multiple strips (44) which are arranged adjacently in the direction substantially perpendicular to the transport direction of the transport device, preferably wherein a width of two or more strips of said multiple strips is substantially the same in the direction substantially perpendicular to the transport direction of the transport device.
  10. The tunnel oven according to any one of the claims 6 - 9, wherein said at least one curtain comprises a series of cuts (47) which extend in a substantially vertical direction and wherein said cuts are arranged spaced apart in a direction substantially perpendicular to the transport direction of the transport device, preferably wherein a distance between adjacent cuts of said series of cuts in the a direction substantially perpendicular to the transport direction of the transport device, is substantially the same.
  11. The tunnel oven according to any one of the claims 5 - 10, wherein said air resistance inducing unit, comprises a plurality of baffles or curtains (41, 41', 42) arranged inside said pretreatment zone, wherein said plurality of curtains are arranged spaced apart in a direction from the tunnel oven entrance and towards the baking zone.
  12. The tunnel oven according to any one of the claims 5 - 11, wherein said bottom wall is provided with one or more baffles (42), wherein said one or more baffles are connected to the bottom wall with a proximal end thereof, wherein a distal end of said one or more baffles, opposite to the proximal end, is arranged near to a bottom side of said part of the transport device, preferably wherein a distance between the bottom side of said part of the transport device and the distal end of the one or more baffles is in a range of 10 - 50 mm.
  13. A method for controlling a tunnel oven according to any one of the claims 1 - 12, wherein the method comprises the steps of: - sending a signal that corresponds to a dew point, temperature and/or humidity of the air inside the air exhaust from the sensor (16) to the control device (17); - controlling the flow regulator (15, 18) in the air exhaust (2) by means of the control device, wherein said controlling is based on said signal.
  14. The method according to claim 13, wherein the control device compares the signal with a threshold value, and when the signal is larger than the threshold value, the control device controls the flow regulator for reducing an air flow in the air exhaust, and/or wherein the flow regulator comprises a motor-driven fan (15), and wherein the step of controlling the flow regulator comprises a step of adjusting a rotational speed of the fan and/or a pitch of the blades of the fan, and/or wherein the flow regulator comprises a regulating valve (18) comprising a valve opening, and wherein the step of controlling the flow regulator comprises a step of adjusting the valve opening.
  15. Computer-readable medium having computer-executable instructions adapted to cause a computer of a control device of a tunnel oven according to any one of the claims 1 - 12 to perform the method according to claim 13 or 14.

Description

BACKGROUND The invention relates to a tunnel oven for the preparation of food products, in particular for baking dough product. Furthermore, the invention relates to a method for controlling a tunnel oven for the preparation of food products, in particular for baking dough products. For the preparation of food products, in particular dough products, in an industrial setting, use is made of large elongated ovens with an open entrance on one end and an open exit on the opposite end of the elongated oven. Such ovens are more commonly referred to as tunnel ovens. In these tunnel ovens, food products are continuously conveyed through the tunnel oven during which the food products are baked and/or cooked as the food products travel along the length of the tunnel oven. In particular for baking dough products such as bread, rolls, buns, baguettes, Parisian bread, round breads, ciabatta, pizza bottoms, pancakes, pastries, etc., the preparation requires an addition of a pretreatment agent, such as moisture, to the food products before they are baked and/or cooked. This addition of moisture is usually achieved by exposing the food products to steam in a pretreatment zone just after the entrance of the tunnel oven, such that the food products travel through the pretreatment zone before entering a baking chamber of the tunnel oven. Furthermore, tunnel ovens are commonly provided with an exhaust, commonly arranged in a part of the tunnel oven close to the exit, in order to extract gasses and/or moisture from the baking chamber. A disadvantage of the known tunnel ovens is, that together with the gasses and/or moisture extracted from the tunnel oven via the exhaust, a considerable amount of energy is also extracted out of the tunnel oven. In order to increase the energy efficiency of a tunnel oven, heat exchangers can be installed in the duct of the exhaust to reclaim part of the heat energy in the extracted gasses. In addition or alternatively, excess steam in the oven which would be extracted from the tunnel oven via the exhaust, may at least partially be recovered and after appropriate treatment with respect to pressure and temperature, may be recirculated as fresh steam in the pretreatment zone. Known tunnel ovens are described in SU 1163819 A, US 4,569,658 A and DE 2 201 884 A1. SUMMARY OF THE INVENTION It is an object of the present invention to provide a novel and alternative method for controlling a tunnel oven, and a tunnel oven comprising a flow control for providing a reduced energy consumption. According to a first aspect, the present invention provides a tunnel oven for the preparation of food product, in particular dough products, wherein the tunnel oven comprises: a tunnel oven entrance, a tunnel oven exit and a baking zone inside said tunnel oven between the tunnel oven entrance and the tunnel oven exit,a transport device configured for transporting food products through the tunnel oven entrance, the backing zone and the tunnel oven exit,a heating source arranged for providing heat to food products in the baking zone,a pretreatment zone, arranged between the baking zone and the tunnel oven entrance, wherein the pretreatment zone comprises an injector configured for injecting a pretreatment agent into the pretreatment zone,an air exhaust configured for extracting air from the baking zone, wherein the air exhaust comprises a flow regulator and a sensor for detecting the presence and/or an amount of pretreatment agent in the air exhaust, anda control device configured for receiving a signal from said sensor, and configured for controlling the flow regulator in the air exhaust based on said signal. In stead of or in addition to reclaiming at least part of the energy in the gasses and/or steam extracted from the tunnel oven, the present invention aims to reduce the amount of gasses and/or steam extracted from the tunnel oven, by providing a flow regulator and a sensor in the air exhaust and controlling the flow regulator based on a signal from said sensor. It is noted that during operation of the known tunnel ovens, the combination of an open entrance and an open exit of the tunnel oven, and the extraction of gasses and/or moisture via the exhaust, results in a draft of ambient air through both the entrance and exit in order to replace the air extracted from the baking chamber via the exhaust. The draft via the entrance and the pretreatment zone, takes along some of the pretreatment agent, such as steam, from the pretreatment zone, into the baking zone, which pretreatment agent is then also present in the air extracted from the baking zone via the air exhaust and is detected by the sensor. The present invention is based on the insight that, when an amount of pretreatment agent is detected in the air extracted from the baking zone via the air exhaust, the rate of extraction of air via the air exhaust can be reduced by controlling the flow regulator in the air exhaust. A reduced air flow out the air exhaust also r