Indirect Mesh-Belt Tunnel Oven BKR S

 

 

 

The “indirect” heated oven (Bakerunner) is powered by one or more gas or oil burners, in this way the heated air is moved around in the heating circuit thus transmitting the heat to the final product in the required way.

The baking inside the tunnel happens by means of heat radiation, heat convection (contact with baking surface) and/or heat conduction (Turbolence). The predominance of the one or the other baking type depends on the oven type and on the combination of the baking chambers.

This is a modular oven, as it can be assembled in different styles, depending on how the different types of chambers are combined; moreover, with the available settings the same oven can be adapted to different products. It can be considered as a “UNIVERSAL” oven as the same oven can bake a wide range of products, from bread-rolls to tin-bread, only by means of changing the baking parameters: this peculiarity is not common among all the ovens available today on the market.

 

1. Definition of the oven /the oven project 

An oven is a combination of different types of baking chambers:

- Infeed chamber with steaming unit;
- Neutral baking chamber;
- Burner chamber;
- Turbulence baking chamber.

The sequence and the types of chambers (which are decided during the project definition according to the kind of product to be baked) as well as the available settings allow reaching the desired baking results with a wide operational range.

 

2. Technical features

2.1. Baking profile/Operating of the Oven

The oven is divided in baking zones each with independent regulations, the maximum length of a zone is 6 meters.
The main regulations on the side of the oven are:

- Top heat regulation;
- Bottom heat regulation;
- Baking surface preheating temperature regulation;
- Oven heat regulation at infeed;
- Steam exhaust regulation;
- Steam infeed regulation at oven infeed;
- Hot air circuit blower speed regulation;
- Turbolence blower speed and direction regulation;
- Baking speed regulation;
- Burner flame regulation (only by means of PLC).

During the baking the regulation happens by means of opening or closing the dampers to adjust the amount of heat or steam entering or exiting the heating circuit and by changing the speed and/or temperature parameters on the control panel.

  

2.2. The baking surface

 

Steel mesh. Typical for the baking of bread on trays or in tins, but also for free standing bread. Baking is predominantly performed by means of heat radiation and heat convection (turbulence).

2.3. User Interface/An intelligent oven

From the operator panel the supervisor can manage the baking process completely.

It is possible to put several parameters (SET-points) and verify the actual status (IS); alarms are showed with an explanation and position on the line; the maintenance page advises about maintenance status of the different components; the recipes page can memorize the baking parameters of the different products.

The oven automation level can be increased according to the customer requirements, it is actually possible to manage automatically the baking profile of the oven automatizing the heat-dampers and/or the steam extraction dampers in the different zones; in this way the operator can set up the oven for the different product types simply by choosing the correct recipe on the control panel.

Moreover with this system it is possible to detect the product gap inside the oven and modify the baking conditions accordingly.

The oven is equipped with different sensors, the acquired data allow the operator to verify the progress of the process and even  the baking efficiency. The main sensors are:

• Hot gas temperature at infeed channel;
• Hot gas temperature in the return channel;
• Hot gas temperature at chimneys exit;
• Pressure inside the hot gas circuit;
• Opening of the burner gas flow valve;
• Humidity of baking chambers.

It is clear that by combining some of the data acquired by these sensors and knowing the product hourly output it is possible to determine the energetic efficiency of the oven together with other productivity coefficients.

 

3. Some details

Steaming of the oven

At the oven infeed the steam pipes are steaming from both sides allowing a better distribution of the steam on the width of the baking chamber. The steaming zone is made of stainless steel. Each zone is provided with its independent steam extraction.

 

 

 

 

 

 

 

 

Turbulence

It is a baking area where hot air is blown by a blower directly on the product. The direction of air flow is adjustable (up-down/down-up). The speed of the air is adjustable. The turbulence can be switched off, in that case the baking chamber works as a “neutral” chamber.
The turbulence section is particularly helpful while baking bread in tins or on trays: it allows to overcome the barrier represented by the mold, to quickly equalize the color and even to lower the baking time of the product.

 

 

 

 

 

Hydraulic tensioning of the baking surface

Hydraulic pump for mesh or chain tensioning with programmable oven start and cool down sequence.

 

 

 

 

 

 

 

 

 

Oven driving system

Driving motor controlled by the inverter. The motor can be postponed or epicyclical connected directly to the drive roller.

Automatic tracking device

Mesh tracking device: by means of pneumatic cylinders driven by “feelers” the mesh is constantly guided.

 

 

 

 

 

 

 

 

 

 

Automatic dampers

Hot air and steam dampers can be motorized. The motor positions the dampers to the exact opening position according to the active recipe.
This option is particularly helpful to manage the product gap and avoid the oven overheating (flash heat).

 

 

 

 

 

 

 

Dirt collecting drawers

The oven is equipped with dirt collecting drawers at the infeed and outfeed as well as underneath the baking surface.

Inspection door

The new inspection door design allows a better access inside the oven for cleaning and maintenance purposes.

 

 

 

 

 

 

 

 

 

Extraction blowers

If required forced extraction blowers can be mounted on the hot steam extraction chimneys. They allow controlling of the steam conditions in the chambers and as well as managing  the production gaps in a better way.

 

 

 

 

 

 

 

 

 

Product gap management

The photocell detects the product gap before it arrives to the oven, the software modifies the parameters and follows the gap to the oven discharge.