Pictures and information from: Baker Pacific Baking Process and Engineering Manual
Direct Gas Fired Ovens
Baker Pacific Direct Gas fired Oven
Moisture from the dough pieces may be extracted from the baking chamber in each zone. The wet air in the baking chamber is drawn into a series of cross ducts at the top of the baking chamber. This wet air then enters the extraction duct running along the top of the baking chamber to the extraction fan entry. The wet air is exhausted through a vertical flue (chimney) to atmosphere.
The amount of air extracted in each zone is controlled by a damper, which may be manually adjusted or by a motorized valve controlled by PLC.
Halifax extraction fan mounted on top of DGF zone
In each zone the air is fed to the air header pipes from an air blower mounted on top of the oven. The air is drawn from the bakery. The air pressure for the burner system is controlled by motorized valves which are regulated by the automatic temperature control system or by a variable speed inverter drive for the fan.
Moro combustion air fan
Indirect radiant Ovens
The fan is located next to the burner (on the right in the picture above). The fan draws the hot gases through the system, distribution ducts, radiant tubes, headers and return ducts.
Extraction and turbulence
In each zone a duct above the band extracts the moist air to the extraction fan. From the fan the wet air enters a duct at the side of the oven where it may be directed to the turbulence duct or to the flue to atmosphere. The system is controlled by dampers.
Oven end extraction hoods
Halifax bi-furcated fan on an oven end hood
The fan extracts hot air from the open end of the baking chamber and exhausts it to atmosphere.
Halifax fans may be purchased from Halifax UK, or from their factory in Shenzhen, China