Indirect Stoneplate Tunnel Oven BKR G
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
Granite stone. Typical for the baking of free standing bread with high water content and clear “artisan” character. Baking is predominantly performed by means of heat radiation and heat conduction from the stone baking surface.
The stone, for its physical characteristics (specific heat per kilogram) releases the heat to the product consistently and for a long time, the spot temperature under the pizza dough does not drop during the baking time and this allows, apart from better quality, a lower baking time.
The stone facilitates the building of the crust resulting in a product with higher humidity.
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 the 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.
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 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).
Automatic oil device for the stone plate oven chain
Programmable automatic oil device with a cogwheel and oil distribution pump. The wheel couples with the chain, in this way the oiling point is always met.
Infrared sensor to read the stone plate temperature at oven infeed
An infrared sensor at oven infeed measures the temperature of the baking surface and allows the operator to “find” the ideal temperature at oven infeed.
Dirt collecting drawers
The oven is equipped with dirt collecting drawers at the infeed and outfeed as well as underneath the baking surface.
Motorized brush
A motorized brush cleans the baking surface and is especially useful for the granite stone cleaning.
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.
Oven in-feed and out-feed
The manufacturing of the stone plate ovens led to the construction of innovative systems to transfer the products to and from the oven surface. The conveyor at oven discharge, for instance, has a double movement: there is a gear motor that keeps the band running and another one moving the pick-up nose horizontally, thus following the stone plate polygonal profile at the oven out-feed.