Thermal Oil Heaters

Pre-Start Preparation

• Leak/pressure-test piping and heater under the approved procedure; inspect flanges and welds. If hydrostatic testing is used, drain and dry thoroughly before commissioning.
• Fill with the specified thermal oil and vent, dehydrate and degas under the commissioning procedure to remove residual water and air.
• Verify main-loop, bypass, drain and vent valve positions against the system diagram and procedure; not every bypass valve must be closed.
• Verify inlet/outlet temperature sensing, pressure instruments, flow switches and element-surface sensing.
• Check insulation, protective earth and phase sequence; verify safety interlocks.
• Set process temperature and overtemperature/overload protection according to technical documents.

Startup: Circulation Before Heating

• Start the circulation pump first and establish stable flow; inhibit heating with no flow or below the protective threshold.
• Once design flow is established, provide the heating-permissive signal.
• Energise elements; oil flows through the vessel and element bundle, gaining heat through the designed flow path or baffles.
• Deliver hot oil to reactor jackets, vulcanising equipment, dryers or other process users.
• Return cooled oil through the return line to the pump and heater.
• PID control adjusts power using outlet-oil temperature to maintain the target.
• An expansion tank accommodates thermal expansion. Oxidation control depends on cool placement, sealing or nitrogen blanketing as designed; an expansion tank alone does not automatically exclude air.

Operating Monitoring

• Monitor supply/return temperatures, pressure, flow and element-sheath temperature; adjust output for load or return-temperature changes.
• Disconnect heating and alarm on low/no flow or excessive oil/sheath temperature. Continued pump operation depends on the cause, including leakage or pump failure.
• Provide pressure interlocks, relief devices and safe discharge arrangements as designed.
• Vent, sample oil and inspect filters under the maintenance plan to manage coking and ageing.

Shutdown

• Normal shutdown: disconnect heating first, maintain suitable circulation to remove residual heat, and stop the pump at the specified safe temperature. Follow the manual for valve positions and long-term draining/storage.
• Emergency shutdown: leakage, overtemperature, overpressure or pump faults trigger heating isolation and alarms. Decide continued circulation according to the fault; do not restart until resolved.

Flow Overview and Monitoring

Circulation pump → thermal oil heater → process equipment → return oil → pump. Connect the expansion tank to the designated branch, rather than treating it as a main-loop series component.

Monitor outlet temperature, pressure, flow and sheath temperature. Protection includes flow, overtemperature, relief and venting as designed. Follow the delivered manual.

• Chemical processing: reactor jackets, distillation reboilers, tracing, resin synthesis, polyurethane polymerisation, rubber vulcanisation, oil refining, bitumen modification and feedstock preheating.
• Rubber and plastics: extruders, platen vulcanisers, calenders, hot pressing, die-temperature maintenance and drying.
• Composites: hot pressing of carbon-fibre/FRP materials and panel-curing ovens.
• Wood processing: veneer drying, hot presses and bonded-panel forming.
• Food and edible oils: refining, drying and indirect cooking/temperature maintenance; verify hygienic design and prevent thermal-oil contamination.
• Packaging and printing: heated rollers, film stretching and thermal lamination.
• Bitumen and building materials: tank temperature maintenance, tracing, gypsum-board production and suitable concrete-curing heat supply.
• Other duties: mould-temperature control, tank tracing, waste-heat integration and laboratory heat sources.

Oxidising, corrosive or high-hazard duties require specific sealing, material and explosion-protection review.

Selection Parameters

Design Features

• High-temperature heat at relatively low pressure: assess 200–350°C requirements against oil bulk/film limits and system design; this is not a universal rating or replacement for every steam duty.
• PID temperature control: verify accuracy and fluctuation against measurement points, thermal inertia and load.
• Circulating heat transfer: suitable flow paths and surface loading help reduce local overheating and coking.
• Insulation and recirculation: reduce heat losses; efficiency depends on load, insulation and operation.
• Modularity: assess skid integration of heater, pump, expansion tank, filter and controls.
• Protection: confirm flow, oil/sheath temperature, pressure and level safeguards by design.
• Oil and process interfaces: verify mineral/synthetic oil compatibility and process-equipment connections.
• Remote monitoring: optional PLC/DCS interfaces for status, temperature and pressure.

Core Functions

• Continuously heat circulating thermal oil for process equipment.
• Multiple temperature points and PID output control maintain supply temperature.
• Minimum-flow interlock disconnects heating on low/no flow.
• Oil and element-sheath temperature protection alarms and disconnects heating above limits.
• Pressure monitoring and designed relief protection with a verified safe discharge path.
• Operating, fault and alarm signal outputs.
• Expansion volume and optional designed oxidation control, such as nitrogen blanketing.
• Optional filtration removes solids; it does not reverse chemical ageing of the oil.

Parameters and configurations are selection references; final deliverables follow the technical agreement and equipment drawings.