Chapter 8 - Oven construction: direct gas-fired ovens

Abstract

This chapter explores the main considerations in specifying and constructing a direct gas-fired (DGF) oven. The main considerations are baking chamber materials and dimensions, expansion joints, explosion relief, insulation, inspection doors and cleanout doors. DGF ovens use “ribbon” burners installed above and below the oven band. A gas/air mixture is fed to the burner tube and burns on a special strip of corrugated or woven stainless steel. The gas may be natural gas, town gas (manufactured from coal) or liquid petroleum gas (LPG). 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 and is exhausted through a vertical flue (chimney) to the atmosphere. A description is given for the temperature control zone for each oven zone with details of the equipment: thermocouples and temperature controllers. The main control panel is located at the end of the oven and will contain all the controls and displays for the conveyor drive, band cleaner, tracking and tension, burners off/on and purge cycle, together with safety alarms. The oven zone panels have controls for top and bottom burners, extraction fan and temperature controllers for setting and indication.