LEWCO, Inc. recently manufactured two custom fuel-fired conveyor ovens for an equipment integrator. The ovens are used for drying various parts and have a maximum operating temperature of 250°F. With the numerous lanes throughout the workspace, this is one of the more unique conveyor ovens LEWCO has completed.
The ovens feature a single, direct-fired, natural gas heater-box with a capacity of 1,500,000 BTU’s/HR. The ovens are equipped with a 15,000 CFM circulation fan delivering uniform horizontal airflow throughout the workspace. Due to the NFPA Class A rated requirement, a 4,050 CFM exhaust fan is included. Both fans include air proving circuits that are electrically interlocked with the heating circuit.
An LEL monitor is included to continuously monitor the percentage LEL of the exhausted airstream. Audible and visual alarms with a programmable alarm setpoint on the controller alert operators of dangerous conditions. The first level of the alarm alerts the operators, and if the percentage LEL continues to rise and reaches a second alarm point, the oven burner will automatically shut down, however all the fans will continue to operate to ventilate the system. Powered exhaust hoods are included on the entrance and exit openings of the ovens to help minimize the airflow escaping into the plant. Each hood includes a one horsepower exhaust fan.
The ovens are equipped with a Programmable Logic Controller (PLC) which incorporates temperature control, safety, and motion abilities into a single controller. A Eurotherm 3216 temperature controller with a redundant high-limit controller provide precise temperature control and over-temperature protection. Burner sequencing, ignition, and flame monitoring is provided by Siemens flame safeguard.
The ovens are part of a fully automated robotic manufacturing cell. LEWCO’s applications and design team worked with the integrator to develop the unique multi-level, multi-conveyor design to meet the customer’s requirements.