DE102008012395A1 - Oven with air outlet - Google Patents

Abstract

oven (1) with a baking chamber, which with an outlet opening (4) is provided, can escape through the air from the oven, wherein in the region of the outlet opening (4) has a throttle element (7) is arranged, characterized in that the throttle element (7) coupled to a controlled by a control module (9) drive (8) is and that on the side lying to the baking chamber of the throttle element (7) a first pressure sensor (12) is arranged, which with the control module (9) is connected.

Description

The The invention relates to an oven with a baking chamber, which with an outlet opening is provided, through the air the baking chamber can escape, wherein in the region of the outlet opening a Throttle element is arranged. It also relates to a method for operating a baking oven.

ovens usually have a heater on, about the air and / or water vapor as heating medium on the for the baking required temperature (usually considerably over 100 ° C) are heated. The gaseous heating medium, in particular, the steam resulting from caking occurs a certain time through the outlet opening from the oven the oven to the outside. Traditional ovens are designed so that in the outlet a negative pressure of about 0.1 mbar (10 Pa) prevails. This weak negative pressure ensures optimum operating conditions when baking, with the heated and humidified atmosphere for a sufficient period of time dwells in the oven to avoid drying out the baked goods and to achieve reliable cooking.

Originally the train was in the air outlet, d. H. the value the negative pressure relative to the ambient pressure through which Construction of the furnace and the adjoining the air outlet opening Chimney reached. Modern stoves are with an opening to the environment Zugregelklappe provided that at too great pressure over allows the flow of ambient air into the chimney. As a result, the negative pressure at the outlet opening for the heating medium in adaptation to the installation situation of the oven be set to a constant value. Changes by the ambient air the steam significantly changes its physical properties. Especially the energy recoverable from the steam decreases.

task The present invention is to provide the constant baking conditions while avoiding the admixture of ambient air.

These Task is in relation to the invention Oven solved by the throttle element with a is coupled by a control module regulated drive and that on the baking chamber lying side of the throttle element is a first Pressure sensor is arranged, which is connected to the control module. As a throttle element may be used in practice, a throttle valve become.

hereby it allows the negative pressure in the area of the outlet opening for the heating medium from the baking chamber dynamically to regulate. One possible type of regulation is the setting of a constant constant negative pressure of 10 Pa compared to the ambient pressure. This already in the past preferred value can by the Control loop, in which the pressure in the oven or just before the throttle element is determined, be set reliably. The admixture of ambient air, which is the saturation of the vapor in the air Reduces escaping fuel gas and thereby lower the dew point is, is to maintain a constant Unterdurckwertes not required at the outlet.

A need for such a setting arises in particular when the withdrawal conditions are variable behind the outlet opening. In modern bakeries, the heating medium emerging from the baking chamber is often not simply released into the atmosphere. The heating medium can be used for the treatment of warm water or for other heating purposes. To this end, often joins the oven to an energy recovery module. Such an energy recovery module is for example from the German utility model DE 297 09 784 known. Often several ovens in a bakery are connected to a common energy recovery module.

The Energy recovery module usually has a fan on to the reliable transport of the oven leaking heating medium through the energy recovery module to ensure. The negative pressure at the outlet opening So depends on the blower output. If several Ovens are connected in parallel and via a common pipeline for the emerging heating medium with a power recovery module are coupled influence they each other. The flow situation at the outlet Each one of the ovens can depend on from the quantity of hot gases coming from the other ovens and depending on the operating point of the energy recovery module vary greatly. This can cause fluctuations in the negative pressure in the region of the outlet opening of a baking oven thereby revealed that several more, with the same energy recovery module coupled ovens, switched on or off. But there are also fluctuations in the negative pressure at the air outlet openings atmospheric influences, eg. B. Wind, in the opening of the fireplace, possible.

By proposing a pressure measurement in the area lying on the side of the baking chamber in front of the throttle element and a pressure control by adjusting the throttle element as a function of the detected measured value, it is possible to achieve a predetermined constant negative pressure value independently of the operating points of coupled ovens. This is true even if the Oven is not coupled with a power recovery module, but its air outlet is connected directly to the fireplace.

In The practice may be on the outside of the oven Side of the throttle element may be arranged a second pressure sensor, which is connected to the control module. This second pressure sensor essentially measures the ambient pressure and is therefore preferred on the outside of the furnace housing or pipe attached for the exiting heating gas. The second pressure sensor may in practice from the second side of a diaphragm of a differential pressure sensor be formed.

Further It may not be useful in certain applications the ambient pressure but the pressure directly behind the Drosseklappe as reference value. In this case, the immediate static pressure measured behind the throttle valve to the second pressure sensor fed.

The Control module may be configured to be out of the measured value of the second pressure sensor and the measured value of the first pressure sensor a Difference value forms, for the regulation of the drive is used for the throttle element. This differential pressure between ambient pressure and pressure in the region of the air outlet opening is crucial for the flow rate the Heizme medium within the oven and through the air outlet opening therethrough.

As already mentioned, the control module, the throttle element regulate such that a constant difference value is maintained. The control module, the throttle element but also on a variable Control difference value. For example, at certain times a baking program for certain dough pieces desired be that the baking atmosphere over a longer Period remains unchanged. This can be z. B. immediately after humidifying the oven with superheated steam be the case. When a hot steam billows the oven supplied, it may be advantageous for the baking result be if the high humidity for a possible long period of time. In this case, the rule module can Control throttle element such that the air outlet closed becomes. At other times the baking program can be a particularly fast Exchange of the baking atmosphere may be desired. For example, can a quick change of baking temperature at a certain time promote the baking program. This leaves to achieve that by completely closing the throttle is opened and thereby a maximum train in the air outlet of the Oven is achieved.

When Throttle element may in particular a pivotable throttle or a linearly displaceable slider can be used. throttle are already installed ready installed in pipe sections, where with electric drives and differential pressure measuring devices are provided. The differential pressure measuring devices measure the difference between the pressure immediately in front of the throttle and immediately behind the throttle. The pressure value immediately behind the throttle can however by the flow speed of the Medium in the range of the throttle to be influenced. therefore is preferred for the value of the ambient pressure, an external one To arrange pressure sensor, for example, on the housing of the furnace.

The The invention further relates to a method for operating a baking oven with a baking chamber, which with an outlet opening is provided, can escape through the air from the oven, with a Throttle arranged in the region of the outlet opening becomes.

to Solution of the above-explained object For example, the throttle element may be controlled by a control module Drive to be actuated, and a first pressure sensor, the arranged on the side lying to the baking chamber of the throttle element is, conduct a measurement signal to the control module. The measuring signal can either via a pressure line pneumatically or via a transducer, the detected pressure value in an electrical size converts and electrically transmits an electrical conductor become.

On The basis of the acquired measured value may be any negative pressure in the area of the air outlet opening through the control module be set.

In In practice, a second pressure sensor on the outside the baking chamber side of the throttle element is a measurement signal to the rule module. Preferably, the control module forms from the Measured value of the second pressure sensor and the measured value of the first pressure sensor a difference value used for the control of the drive is used for the throttle element.

As mentioned above, the control module, the throttle element regulate such that a constant difference value is maintained. Alternatively, a variable difference value can be obtained which exceeds the Time of the baking program assumes certain values.

The air exiting through the exit port may be directed to an energy recovery module. The outlet opening of the oven can essentially through the throttle element be sealed tightly. In this way, the negative pressure in the region of the air outlet opening can be set to virtually zero.

A Embodiment of the invention will be described below with reference described on the accompanying drawings. The painting show in:

1 an oven according to the invention with energy recovery module,

2 a sectional front view of the adjoining the outlet opening pipe section in which the throttle element is arranged,

3 a side view of the throttle element 2 ,

In the 1 is a craft oven 1 to recognize, over an exhaust pipe 2 with an energy recovery module 3 is coupled. The oven 1 consists of a thermally insulated wall, which delimits the oven. Other components of the oven 1 such as heater, blower, steam generator, oven control, etc. are not shown in the drawings.

At an upper back corner of the oven 1 is an exit opening 4 arranged, to which a pipe socket 5 followed. Through the pipe socket 5 Can the medium in the oven oven 1 , in particular the heated air and heated water vapor, emerge from the baking chamber. The from the baking chamber through the pipe socket 5 emerging heating medium, in particular the hot steam, is through the exhaust pipe 2 to the energy recovery module 3 passed where heat energy from the gaseous medium is removed via heat exchangers. The thermal energy is used in particular for heating domestic water. For ovens that are heated with oil burners or gas burners, the energy recovery module can also be fed with the burner's hot flue gas. This gas is released from toxins in a flue gas scrubber. Furthermore, it is also deprived of thermal energy for heating service water. As mentioned, the function of such an energy recovery module is, for example, in the German Utility Model DE 297 09 784 U1 described.

On the pipe socket 5 is a pipe section 6 mounted, in which as a throttle element, a throttle valve 7 is included. The pipe section 6 with the throttle 7 is detailed in the 2 and 3 shown. The rotational position of the throttle 7 is powered by an electric drive motor 8th set.

The drive motor 8th is via a flanged control module 9 regulated. The rule module 9 has two signal inputs 10 . 11 on. These signal inputs 10 . 11 Signals can be fed from pressure sensors. The first pressure sensor 12 (please refer 3 ) is in the flow direction in front of the throttle valve 7 arranged. The pressure sensor 12 essentially measures the pressure prevailing at the exit opening of the oven.

The second pressure sensor 13 is via a pressure line 14 connected to the environment. In other words, the second pressure sensor detects 13 the pressure values of the air surrounding the oven. This pressure value is independent of the suction that comes from the energy recovery module 3 over the exhaust pipe 2 in the area behind the throttle 7 is produced. As mentioned above, alternatively, the pressure value directly behind the throttle valve may be supplied to the second pressure sensor.

In this way it is possible in the area of the outlet opening 4 of the oven 1 to set a constant pressure value with respect to the ambient pressure.

As mentioned, in practice, an energy recovery module 3 several ovens 1 be connected. The throttle 7 allows a constant adjustment of the negative pressure in the area of the outlet opening 4 each one of these furnaces, regardless of the operating parameters of the other furnaces and regardless of the operating parameters of the energy recovery module 3 ,

Will the throttle 7 pivoted into the position perpendicular to the tube axis, the tube cross-section is substantially sealed tight. In this way, in certain phases of the baking program, an exit of the atmosphere in the oven 1 be completely stopped.

Similarly, if necessary, an increased outflow of gases from the oven 1 be promoted by the throttle 7 is pivoted in a pipe axis intersecting plane. This results in a low flow resistance through which z. B. a particularly fast exchange of the atmosphere in the oven oven, z. B. to lower the temperature can be achieved.

It should be noted that the drawings merely illustrate the invention, but do not limit its scope. Instead of the throttle 7 Any suitable throttle element can be used. For example, a slider can be used, which is the cross section of the pipe section 6 more or less covering. Also, as a throttle element a dazzle-like Tube closure can be used, with which the flow cross section can be varied.

In particular for the realization of temporally variable negative pressures in the region of the outlet opening 4 the oven can be the control module 9 be coupled with the control of the oven. The oven control oven gives the control module 9 depending on the baking program different target pressure values. The desired pressure values preferably define differential pressures, ie the value of the negative pressure, that in the region of the outlet opening 4 prevails over the atmosphere surrounding the oven.

1

oven

2

exhaust pipe

3

Energy recovery module

4

outlet opening

5

pipe socket

6

pipe section

7

Throttling element, throttle

8th

drive motor

9

control module

10

signal input

11

signal input

12

first pressure sensor

13

second pressure sensor

14

signal line

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 29709784 U [0007]
• - DE 29709784 U1 [0026]

Claims (14)

Oven ( 1 ) with a baking chamber, which with an outlet opening ( 4 ) is provided, can escape through the air from the oven, wherein in the region of the outlet opening ( 4 ) a throttle element ( 7 ), characterized in that the throttle element ( 7 ) with a through a control module ( 9 ) regulated drive ( 8th ) is coupled and that on the side lying to the baking chamber of the throttle element ( 7 ) a first pressure sensor ( 12 ) arranged with the control module ( 9 ) connected is. Oven ( 1 ) according to claim 2, characterized in that on the lying outside the baking chamber side of the throttle element ( 7 ) a second pressure sensor ( 13 ) arranged with the control module ( 9 ) connected is. Oven ( 1 ) according to claim 2, characterized in that the control module ( 9 ) is configured such that it is derived from the measured value of the second pressure sensor ( 13 ) and the measured value of the first pressure sensor ( 12 ) forms a difference value which is used for controlling the drive ( 8th ) for the throttle element ( 7 ) is used. Oven ( 1 ) according to claim 3, characterized in that the control module ( 9 ) the throttle element ( 7 ) so that a constant difference value is maintained. Oven ( 1 ) according to claim 3, characterized in that the control module ( 9 ) the throttle element ( 7 ) such that a variable difference value is obtained which assumes predetermined values over the time of a baking program. Oven ( 1 ) according to one of the preceding claims, characterized in that the outlet opening ( 4 ) to an energy recovery module ( 3 ) leads. Oven ( 1 ) according to one of the preceding claims, characterized in that the throttle element is a throttle valve ( 7 ) or a slider is. Method for operating a baking oven ( 1 ) with a baking chamber, which with an outlet opening ( 4 ) is provided, can escape through the air from the baking chamber, wherein a throttle element ( 7 ) in the region of the outlet opening ( 4 ), characterized in that the throttle element ( 7 ) with a through a control module ( 9 ) regulated drive ( 8th ) and that a first pressure sensor ( 12 ) on the side of the throttle element lying to the baking chamber ( 7 ) a measurement signal to the control module ( 9 ). Method according to claim 8, characterized in that a second pressure sensor ( 13 ) on the side of the throttle element lying outside the baking chamber ( 7 ) a measurement signal to the control module ( 9 ). Method according to claim 9, characterized in that the control module ( 9 ) from the measured value of the second pressure sensor ( 13 ) and the measured value of the first pressure sensor ( 12 ) forms a difference value which is used for controlling the drive ( 8th ) for the throttle element ( 7 ) is used. Method according to claim 10, characterized in that the control module ( 9 ) the throttle element ( 7 ) so that a constant difference value is maintained. Method according to claim 10, characterized in that the control module ( 9 ) the throttle element ( 7 ) such that a variable difference value is obtained which assumes predetermined values over the time of a baking program. Method according to one of claims 8 to 12, characterized in that through the outlet opening ( 4 ) exiting air to an energy recovery module ( 3 ). Method according to one of claims 8 to 13, characterized in that the outlet opening ( 4 ) through the throttle element ( 7 ) can be sealed substantially.