EP4357681A1 - Dampfbackofen und verfahren zur überwachung des kalkniveaus in einem dampfbackofen - Google Patents

Dampfbackofen und verfahren zur überwachung des kalkniveaus in einem dampfbackofen Download PDF

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Publication number
EP4357681A1
EP4357681A1 EP23204011.3A EP23204011A EP4357681A1 EP 4357681 A1 EP4357681 A1 EP 4357681A1 EP 23204011 A EP23204011 A EP 23204011A EP 4357681 A1 EP4357681 A1 EP 4357681A1
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EP
European Patent Office
Prior art keywords
boiler
switch
steam
temperature
limescale
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP23204011.3A
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English (en)
French (fr)
Inventor
Matteo FORNACCIARI
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Smeg SpA
Original Assignee
Smeg SpA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Smeg SpA filed Critical Smeg SpA
Publication of EP4357681A1 publication Critical patent/EP4357681A1/de
Pending legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24C—DOMESTIC STOVES OR RANGES ; DETAILS OF DOMESTIC STOVES OR RANGES, OF GENERAL APPLICATION
    • F24C15/00—Details
    • F24C15/32—Arrangements of ducts for hot gases, e.g. in or around baking ovens
    • F24C15/322—Arrangements of ducts for hot gases, e.g. in or around baking ovens with forced circulation
    • F24C15/327—Arrangements of ducts for hot gases, e.g. in or around baking ovens with forced circulation with air moisturising
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
    • F22B1/00—Methods of steam generation characterised by form of heating method
    • F22B1/28—Methods of steam generation characterised by form of heating method in boilers heated electrically
    • F22B1/284—Methods of steam generation characterised by form of heating method in boilers heated electrically with water in reservoirs
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
    • F22B37/00—Component parts or details of steam boilers
    • F22B37/02—Component parts or details of steam boilers applicable to more than one kind or type of steam boiler
    • F22B37/48—Devices for removing water, salt, or sludge from boilers; Arrangements of cleaning apparatus in boilers; Combinations thereof with boilers

Definitions

  • the present invention relates to a steam oven for cooking food and a method for controlling the level of limescale in a steam oven for cooking food.
  • the technical field of reference of the present invention thus pertains to (domestic and professional) ovens for cooking or heating food.
  • ovens supplement so-called traditional cooking processes with steam cooking processes.
  • Such ovens comprise a steam generation device comprising a boiler to generate steam, and a water/steam circuit comprising ducts to feed water to the boiler and additional ducts to feed the steam to the cooking chamber.
  • the steam generation device is emptied and, after a predefined number of cycles of use, a signal of the need for descaling is emitted.
  • the present invention relates to a steam oven comprising a cooking chamber, a steam generation device and a monitoring system; wherein the steam generation device is configured to generate steam to be fed into the cooking chamber and comprises a boiler and at least one auxiliary tank, which is in communication with the boiler to feed, in use, water to the boiler; the monitoring system being configured to monitor the level of limescale in the steam generation device and comprising a temperature sensor coupled to the boiler and a monitoring device configured to store at least one temperature value detected by the temperature sensor each time the steam function of the oven is activated, to compare the at least one acquired temperature value with a limescale threshold value, and to signal the need for descaling when the at least one temperature value detected by the temperature sensor is greater than the limescale threshold value.
  • the present invention relates to a method for controlling the level of limescale in a steam oven as claimed in claim 14.
  • the reference number 1 indicates a steam oven comprising a muffle 2 that defines a cooking chamber 3 (partially visible), a door 4, a steam generation device 5 (schematically represented) and a monitoring system 6 (visible in Figures 2-4 ).
  • the steam generation device 5 comprises a boiler 8, a main tank 9 for water storage, an auxiliary tank 10 communicating with the boiler 8, a supply line 12 provided with a supply pump 13 and configured to feed water to the main tank 9 from a water inlet (not illustrated for simplicity), a discharge line 15 provided with a discharge pump 16 and configured to empty the main tank 9 and/or the auxiliary tank 10 and discharge the withdrawn water towards the water inlet, a supply/discharge regulating device 18 (preferably defined by a three-way valve arranged along the supply line 12 and connected to the discharge line 15), and a connecting valve 20, which regulates the connection between the main tank 9 and the auxiliary tank 10.
  • a supply/discharge regulating device 18 preferably defined by a three-way valve arranged along the supply line 12 and connected to the discharge line 15
  • a connecting valve 20 which regulates the connection between the main tank 9 and the auxiliary tank 10.
  • the monitoring system 6 comprises a temperature sensor 22 and a monitoring device 24.
  • the temperature sensor 22 is an NTC probe made of a sintered semiconductor material that exhibits a large resistive variation in response to a small temperature variation.
  • the temperature sensor 22 is coupled to the boiler 8.
  • the temperature sensor 22 is coupled externally to the boiler 8.
  • the main tank 9 is provided with a level sensor (not illustrated for simplicity) able to measure the water level.
  • the temperature sensor 22 and the level sensor of the main tank 9 are configured to detect data and feed it to the monitoring device 24.
  • the monitoring device 24 calculates, based on the measurement of the level of water present in the main tank 9, the amount of water necessary to complete the steam cooking process based on the parameters set by the user (e.g., function, temperature, time). In other words, if there is already water in the main tank 9, the monitoring device 24 calculates the amount of water to be fed to the main tank 9 in addition to the water already present.
  • the monitoring device 24 activates the regulating device 18 in "supply” mode and activates the supply pump 13 until the level of water supplied into the main tank 9 reaches the calculated value (see the supply configuration in Figure 2 ).
  • the boiler 8 During the steam cooking process, the boiler 8 generates steam and discharges it into the cooking chamber 2 by means of an injection duct 25.
  • the boiler 8 is regulated by the monitoring system 6 and performs, in sequence, switch-on and switch-off cycles controlled by the monitoring device 24.
  • the monitoring device 24 adjusts the connecting valve 20 to perform a refilling of the auxiliary tank 10 by making a part of the water flow from the main tank 9 to the auxiliary tank 10 (see the refilling configuration of Figure 3 ).
  • the connecting value 20 is preferably a regulating solenoid valve, whose opening/closing and adjustment is controlled by the monitoring device 24.
  • the boiler 8 is reactivated and continues to carry out switch-on and switch-off cycles until the temperature detected by the temperature sensor 22 again exceeds the dry boiler threshold Temp s , which causes a new refilling operation to start. In other words, reaching a temperature value equal to the "dry boiler threshold Temp s " is indicative of a complete consumption of the water in the auxiliary tank 10.
  • the monitoring device 24 activates the regulating device 18 in "supply” mode and activates the supply pump 13 until the level of water supplied in the main tank 9 reaches the calculated value (see the supply configuration of Figure 2 ).
  • the user can perform a new steam cooking process, using the water left over from the previous cooking process, or empty the main tank 9 and the auxiliary tank 10 through activation of the discharge pump 16 and activation of the regulating device 18 in "discharge” mode (see configuration of Figure 4 ).
  • the monitoring device 24 is also configured to determine, based on at least one temperature value detected by the temperature sensor 22 in the boiler 8, the need to descale the boiler 8 and/or the entire steam generation device 5.
  • the monitoring device 24 is configured to capture the temperature values detected by the temperature sensor 22 with a certain sampling frequency.
  • the monitoring device 24 is configured to store the maximum temperature Temp max reached in the boiler 8 during a switch-on-switch-off cycle of a "water consumption period" TC.
  • a switch-on-switch-off cycle is to be understood as the time that elapses between one switch-on event of the boiler 8 and the next.
  • the switch-on-switch-off cycle comprises the period in which the boiler is switched on (ON time) and the period in which the boiler is switched off between two consecutive switch-on events (OFF time).
  • the switch-on-switch-off cycle is visible as a temperature oscillation from a minimum to a maximum.
  • "Water consumption period" TC is to be understood as the time of complete consumption of the water in the auxiliary tank 10 (by reaching the dry boiler threshold temperature Temps).
  • the water consumption period TC is the time that elapses between the conclusion of the operations of refilling/filling the auxiliary tank 10 and the reaching of the dry boiler threshold temperature Temps.
  • the steam cooking process thus consists of a number of water consumption periods TC interspersed by tank filling periods TR.
  • the diagram in Figure 5 shows the evolution of the temperature detected by the sensor 22 and the activation signal of the connecting valve 20 (variable between 0 and 1).
  • the activation signal of the regulating valve 20 is at zero, and there is an oscillation of the temperature due to the succession of switch-on and switch-off cycles of the boiler 8.
  • the evaluation of the temperature for the purpose of determining the limescale level is preferably carried out as of the third switch-on-switch-off cycle of the boiler 8 while taking into account the maximum temperature reached during said cycle.
  • the first cycles (at least the first two and preferably the first three) have a substantially similar duration.
  • the duration of the switch-on and switch-off cycles can vary according to the steam intensity required by the user. As of the third cycle, however, there is a stabilization of the oscillation values of the temperature.
  • the steam intensity related to the cooking requirements of the user can have a significant impact on the evolution of the temperature.
  • the control algorithm after the boiler 8 has been refilled and until the detection of the temperature useful for the purposes of the evaluation, carries out similar switch-on and switch-off cycles of substantially the same duration; only after the detection of the maximum temperature does the steam generation continue, adapting itself to the cooking process required by the user (by prolonging or reducing the duration of the switch-on and switch-off cycles). This setting causes limited deviations relative to the standard approach and does not compromise the final result of the cooking process.
  • the maximum temperature is detected in a switch-on and switch-off cycle comprised between the 4th and 6th cycles.
  • the monitoring device 24 detects an abnormal condition and signals the need for descaling (condition reached at the 4 th water consumption period TC4 in the example shown in Figure 5 ) .
  • the monitoring device 24 does not generate any signals and the switch-on and switch-off cycles continue normally.
  • the maximum temperature Temp max is influenced by the presence of limescale deposits.
  • the limescale threshold value Teal is defined a priori taking into account the desired performance and functional aspects of the product, which must be guaranteed.
  • the limescale threshold value Tcal must be lower than the dry boiler threshold value Temp s ; otherwise, the functional aspect of the system is compromised.
  • the limescale threshold value Tcal must be sufficiently lower than the dry boiler threshold value Temp s so that the monitoring system 6 can take advantage of a sufficient space of time to alert the user of the need for descaling before the steam generation device 5 is no longer usable.
  • the limescale threshold value Teal cannot be too much lower than the dry boiler threshold value Temp s either, because that would mean excessively reducing the operating hours of the system before descaling.
  • the difference between the dry boiler threshold Temp s and the limescale threshold Teal is comprised between 8°C and 12°C and is preferably 10°C.
  • the monitoring device 24 is configured to signal the need for descaling when the maximum temperature Temp max reached in the boiler 8 in a defined cycle of a "water consumption period" TC is greater than or equal to a limescale threshold value Teal.
  • the monitoring device 24 and the steam generation device 5 are functionally still operational.
  • the monitoring device 24 provides a "soft" signal to the user, alerting him or her that the time to descale the steam generation device 5 is approaching, but potentially allowing him or her to carry out further steam cooking processes.
  • the monitoring device 24 detects that the dry boiler threshold temperature Temp s is reached in a very short period of time (indicatively less than 30% of the expected time of duration of the water consumption period TC), the overheating of the boiler 8 is not due to the absence of water, but to a massive presence of limescale. In this case, the monitoring device 24 generates an alarm signal that imposes the descaling of the steam generation device 5 by preventing further steam cooking processes from being carried out. In such a case, the signal is thus of a "hard” type and prevents the use of the steam generation device 5.
  • the monitoring system 6 is configured to determine an indication of the limescaling status as well and to provide, in real time, limescaling data to the user as an information parameter.
  • the formula highlighted above has its basis in the fact that the maximum temperature reached by the boiler 8 in the presence of water and during the various heating steps tends to increase in proportion to the presence of limescale deposited on the walls of the boiler 8 and in the fact that the time of consumption of a certain fixed amount of water tends to remain independent of the amount of limescale deposited inside the boiler 8.
  • FIG. 6 illustrates a diagram of the evolution of the temperature in a succession of cooking process cycles.
  • Each cooking cycle comprises n water consumption periods TC, and each water consumption period TCn comprises a plurality of switch-on-switch-off cycles.
  • the maximum temperature detected at the nth cycle Temp max (TCn) is the maximum temperature detected in the boiler 8 in the third switch-on-switch-off cycle comprised in a respective n-th water consumption period TCn.
  • the limescale threshold Teal is reached at the water consumption period TC1, TC2, TC3, TC4 of the 6th cooking process.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Cookers (AREA)
EP23204011.3A 2022-10-19 2023-10-17 Dampfbackofen und verfahren zur überwachung des kalkniveaus in einem dampfbackofen Pending EP4357681A1 (de)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
IT202200021585 2022-10-19

Publications (1)

Publication Number Publication Date
EP4357681A1 true EP4357681A1 (de) 2024-04-24

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ID=85017739

Family Applications (1)

Application Number Title Priority Date Filing Date
EP23204011.3A Pending EP4357681A1 (de) 2022-10-19 2023-10-17 Dampfbackofen und verfahren zur überwachung des kalkniveaus in einem dampfbackofen

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Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4281636A (en) * 1979-06-07 1981-08-04 Vegh Elmer S Steam processor
EP1166698B1 (de) * 2000-06-28 2003-04-23 V-Zug AG Boiler und Dampfgargerät mit einem derartigen Boiler
EP2048444B1 (de) * 2007-10-09 2016-02-24 Miele & Cie. KG Verfahren zur Reinigung eines Systems, bestehend aus einem Tank und einem Durchlauferhitzer
EP2461107B1 (de) * 2010-12-06 2016-09-14 Miele & Cie. KG Verfahren zum Betreiben eines Gargerätes
US20160316516A1 (en) * 2015-04-21 2016-10-27 E.G.O. Elektro-Geraetebau Gmbh Heating device for heating liquids, evaporator for an electric cooking appliance and method for operating a heating device
WO2019185321A1 (de) * 2018-03-29 2019-10-03 BSH Hausgeräte GmbH Haushalts-dampfbehandlungsgerät
CN217274087U (zh) * 2022-02-15 2022-08-23 宁波方太厨具有限公司 一种锅炉

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4281636A (en) * 1979-06-07 1981-08-04 Vegh Elmer S Steam processor
EP1166698B1 (de) * 2000-06-28 2003-04-23 V-Zug AG Boiler und Dampfgargerät mit einem derartigen Boiler
EP2048444B1 (de) * 2007-10-09 2016-02-24 Miele & Cie. KG Verfahren zur Reinigung eines Systems, bestehend aus einem Tank und einem Durchlauferhitzer
EP2461107B1 (de) * 2010-12-06 2016-09-14 Miele & Cie. KG Verfahren zum Betreiben eines Gargerätes
US20160316516A1 (en) * 2015-04-21 2016-10-27 E.G.O. Elektro-Geraetebau Gmbh Heating device for heating liquids, evaporator for an electric cooking appliance and method for operating a heating device
WO2019185321A1 (de) * 2018-03-29 2019-10-03 BSH Hausgeräte GmbH Haushalts-dampfbehandlungsgerät
CN217274087U (zh) * 2022-02-15 2022-08-23 宁波方太厨具有限公司 一种锅炉

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