Natural Gas Heated Conveyor Drying Oven for Continuous Drying of Flow-Line Kick Plates

This oven was developed for a continuous finishing line requiring the drying of hanging kick plates conveyed through the oven on an overhead transport system.

APPLICATION REQUIREMENT

• The equipment had to support a continuous flow-line drying process rather than batch processing.
• The product basis identified in the proposal is kick plates.
• The process basis is drying.
• The conveyor system is customer supplied, with the oven designed to interface with the conveyor openings and mounting locations.

THROUGHPUT / CONVEYANCE REQUIREMENT

• The process basis is 720 lb/hr at 6 ft/min, assuming 2 parts per hook.
• The oven had to support continuous passage of suspended product through a tall vertical work envelope.
• Conveyor inlet and outlet interface points are built into the oven design.
• The GA includes defined 6 in × 6 in conveyor mounting point openings for customer conveyor integration.

WORK CHAMBER / LOAD REQUIREMENT

• Internal work area: 169 in W × 91.5 in D × 145 in H.
• Interior volume: approximately 1,298 cubic feet.
• The oven had to provide enough internal height and width to process hanging parts while preserving adequate airflow passage through the chamber.
• Product positioning and fixturing had to avoid restricting airflow through the oven.

PROCESS REQUIREMENT

• The system had to provide controlled drying performance for continuously moving product.
• Maximum VOC basis: no VOCs allowed.
• Operating temperature range: 230°F to 300°F.
• Maximum temperature: 300°F.
• Required work-area uniformity: ±10°F.

SAFETY REQUIREMENT

• The oven was required to be designed as an NFPA 86 Class A unit.
• The design required exhaust, purge, combustion, flame safeguard, gas-pressure-proving, proof-of-closure, airflow-proving, and high-limit architecture suitable for a conveyorized gas-fired drying oven.
• The GA includes an explosion relief panel, with surrounding clearance required.

UTILITY / SITE REQUIREMENT

• Required electrical service: 460V / 3PH / 60Hz.
• Full load amps: 44.4 A.
• Required fuel: natural gas.
• Gas inlet pressure basis: 1 PSI.
• Gas flow basis: 1,500 CFH.
• Design elevation: less than 1,000 ft above sea level.
• Installation access basis: 12 ft W × 16 ft H dock / door size.

INSTALLATION / SHIPMENT REQUIREMENT

• Approximate shipping weight: 20,000 lb.
• The oven was designed to ship in multiple major sections.
• The GA shows separate lower body, upper body, and heat chamber lifting points.
• Customer installation scope includes unloading, move-in, utility connections, exhaust stack installation, and reassembly of any items removed for shipping.

These thermal process requirements were established from the customer’s need to dry powder-coated hanging kick plates in a continuous conveyorized production environment.

TEMPERATURE CAPABILITY

• Operating range: 230°F to 300°F.
• Maximum operating temperature: 300°F.
• Required work-area temperature uniformity: ±10°F.

PROCESS BASIS

• The thermal process basis is continuous drying.
• Product basis: kick plates.
• Throughput basis: 720 lb/hr at 6 ft/min, assuming 2 parts per hook.
• VOC basis: no VOCs allowed.

HEAT INPUT REQUIREMENT

• Heat source: natural gas.
• Burner arrangement: two Selas PC1-B burners.
• Burner output: 750,000 BTU/hr each.
• Total heat input: 1,500,000 BTU/hr.
• Burner-side regulated pressure basis: 7.0 in. W.c.
• Recommended gas-pressure switch settings: 4 in. W.c. Low and 9 in. W.c. High.
• Gas train design includes double safety shutoff with proof of closure, regulator, low- and high-gas-pressure switches, visual indication, test nipples, and Siemens SQM4 actuator-based modulation.

AIRFLOW DELIVERY REQUIREMENTS

• Required airflow style: full vertical airflow.
• Recirculation fan arrangement: two NYB Dual AK12 air kits.
• Total recirculation airflow basis: 20,250 CFM at 2 in. W.c.
• Recirculation fan motor basis: 10 HP each.
• Recirculation fans are controlled by Allen-Bradley PowerFlex 4M VFDs.

EXHAUST / VENTILATION BASIS

• Exhaust airflow basis: 1,200 CFM at 1 in. W.c.
• Exhaust fan basis: PQ15 exhauster with 1 HP motor.
• The outlet vestibule is exhausted at 100 CFM.
• The remaining 1,100 CFM is pulled from the heat zone.
• Fresh air is pulled from the inlet vestibule to help reduce heat loss at the process openings.
• Burner and fresh-air inlets include MERV 1 or greater filtration.
• The exhaust system supports Class A purge and ventilation requirements for the process.

THERMAL INSTRUMENTATION / CONTROL BASIS

• Primary temperature controller: WATLOW F4T.
• Thermocouple type: Type J.
• Separate high-limit protection is provided for:
• Combustion chamber #1
• Work area #1
• Combustion chamber #2
• Work area #2
• The F4T configuration includes:
• Two work-area temperature inputs
• Two 4–20 mA heat outputs
• Fan shutdown output
• Disable-burners output
• Combustion blower alarm / post-run output when a burner is off and oven temperature is above 150°F

SAFETY / CLASSIFICATION BASIS

• Oven classification basis: NFPA 86 Class A.
• Dual-burner safety architecture includes Dungs flame safeguard controls, airflow switches, gas pressure switches, proof-of-closure logic, purge sequencing, and high-limit protection.
• The sequence of operation starts the exhaust fan first, then the recirculation fans, then enables burner purge and lightoff.
• If any safe operating condition is not met, the burners are disabled.
• The wiring package instructs that fans are not to be shut down when the oven is above 250°F.

To deliver the customer and thermal process requirements for this oven, Precision Quincy developed the following equipment concept and architecture.

OVERALL CONCEPT

• One natural-gas-heated conveyor drying oven.
• Designed for continuous flow-line drying of hanging kick plates.
• The oven interfaces with a customer-supplied overhead conveyor.
• Conveyor inlet and outlet openings, vestibules, and mounting-point provisions are built into the oven design.
• The architecture combines a tall work chamber, vertical airflow, Class A safety hardware, and a shipping-friendly sectional structure for field installation.

HEATING ARCHITECTURE

• Heat source: natural gas.
• Burner arrangement: two Selas PC1-B burners.
• Individual burner output: 750,000 BTU/hr.
• Total heat input: 1,500,000 BTU/hr.
• Gas train components include double safety shutoff valves with proof of closure, regulator, high- and low-pressure switches, test nipples, visual valve position indication, and actuator-based modulation.
• Burner gas control valve actuators: Siemens SQM4.
• Burner flame safety controls: Dungs MPA4112 series.
• Separate combustion blowers are provided for each burner.

AIRFLOW / RECIRCULATION ARCHITECTURE

• Airflow pattern: full vertical airflow.
• Recirculation fan concept:
• Two NYB Dual AK12 air kits
• 10,125 CFM at 2 in. W.c. Each
• 10 HP motor each
• Allen-Bradley PowerFlex 4M VFDs
• Exhaust fan concept:
• PQ15 exhauster
• 1,200 CFM at 1 in. W.c.
• 1 HP motor
• The exhaust system supports Class A ventilation and purge requirements.
• Vestibule-based fresh-air handling is used to help reduce heat loss at the conveyor openings.
• The internal airflow pattern is shown on the GA as full vertical airflow through the work chamber.

CHAMBER / CONSTRUCTION ARCHITECTURE

• Internal work chamber: 169 in W × 91.5 in D × 145 in H.
• Interior volume: approximately 1,298 cubic feet.
• Construction style: tongue-and-groove interlocking insulated panel oven with structural steel reinforcement.
• Wall thickness: 6 inches.
• Insulation: 6-inch, 6 lb density mineral wool.
• Floor: 3-inch insulated floor.
• Interior material: unpainted aluminized steel.
• Exterior finish: RAL 9003 Signal White.
• Heat chamber location: top-mounted dual heat chamber arrangement.
• The GA shows a sectional design with upper body, lower body, and heat chamber lifting provisions for shipment and installation.

DOOR / ACCESS ARCHITECTURE

• Main access doors: two 42 in × 110 in access doors on the oven body.
• Heat chamber access doors: two 20 in × 24 in access doors.
• Conveyor openings: approximately 14 in W × 122 in H.
• Vestibule opening size: approximately 14 in W × 125.37 in H.
• Vestibule width: 22.5 in.
• Internal vestibule geometry extends down into the oven to help isolate the process openings from the main heated work area.

CONTROLS ARCHITECTURE

• Primary temperature controller: WATLOW F4T.
• Thermocouple type: Type J.
• Independent excess-temperature controllers are provided for:
• Combustion chamber #1
• Work area #1
• Combustion chamber #2
• Work area #2
• Main control enclosure: 46 in × 46 in × 12 in NEMA 1 enclosure.
• Panel type: UL 508A open industrial control panel.
• Reserved remote-I/O space: 12 in × 12 in minimum.
• Spare panel space with DIN rail: 8 in × 10 in.
• Burner junction boxes: two 16 in × 16 in × 6 in NEMA 1 enclosures.
• The front panel includes operator controls and indication for exhaust fan, recirculation fans, burner #1, burner #2, purging, flame safety faults, and flame safety resets.

SAFETY / COMPLIANCE ARCHITECTURE

• Oven classification: NFPA 86 Class A.
• Applicable standards shown on the electrical documents: NFPA 79, NFPA 86, UL 508A.
• Burner safety hardware includes flame safeguards, gas pressure switches, proof-of-closure devices, ignition transformers, and combustion-airflow proving.
• The GA includes an explosion relief panel with a required clear area.
• The wiring package lists an SCCR of 5,000 A.

SHIPPING / INSTALLATION ARCHITECTURE

• Approximate shipping weight: 20,000 lb.
• Shipping access basis: 12 ft × 16 ft dock / door size.
• The oven was designed to ship partially assembled.
• Customer installation planning must account for vestibules, exhaust ducting, conveyor mounting, and point-of-use clearance.