Electric Thermal Oil Heater 80 kW Manufactured by PT Indira Mitra Boiler

PT Indira Mitra Boiler specializes in the design, fabrication, installation, and commissioning of industrial heating systems, including steam boilers, Thermal Oil Heaters, hot-water boilers, electric boilers, and burner systems.

The 80 kW Electric Thermal Oil Heater is designed for industrial processes requiring stable and accurate temperature control without combustion, fuel storage, exhaust gas, or a chimney.

Electric Thermal Oil Heater Case Study

A manufacturing company required an indirect heating system for a production process. The existing heating method produced an unstable temperature and required frequent operator supervision.

The customer requested a system with the following characteristics:

• Clean operation without combustion gases.
• Accurate process-temperature control.
• Automatic operation.
• Compact installation.
• Low noise.
• No chimney or burner.
• Easy integration with existing production equipment.
• Complete electrical and thermal safety protection.

Based on these requirements, PT Indira Mitra Boiler proposed an 80 kW Electric Thermal Oil Heater.

Proposed Technical Specification

The final operating temperature must be adjusted to the thermal-oil specification, heater design, pump selection, and process requirements.

Capacity Conversion

The thermal capacity is converted using:

$$1\text{ kW}\approx 860\text{ kcal/h}$$

Therefore:

$$80\times 860=68,800\text{ kcal/h}$$

The heater provides approximately 68,800 kcal/h of thermal energy at full electrical load.

System Components

The proposed Electric Thermal Oil Heater consists of the following main components:

• Heater vessel or heating chamber.
• Industrial electric heating elements.
• High-temperature circulation pump.
• Expansion tank.
• Thermal-oil piping.
• Isolation and drain valves.
• Temperature sensors.
• Pressure gauge.
• Flow-protection device.
• Electrical control panel.
• Thermal insulation and metal cladding.
• Automatic safety interlocks.

Electric Heating Elements

Industrial electric heating elements convert electrical energy directly into heat. The elements are installed inside the heater chamber, where heat is transferred to the circulating thermal oil.

To improve temperature control, the total heating capacity can be divided into several stages. For example, an 80 kW heater may use four heating stages of 20 kW each.

This arrangement provides several operational benefits:

• More stable temperature control.
• Reduced switching frequency.
• Lower temperature overshoot.
• Flexible response to changing process loads.
• Easier maintenance of individual heating stages.
• Reduced electrical loading during start-up.

Thyristor or SCR control can also be used when the process requires finer and continuously variable power regulation.

Thermal-Oil Circulation System

A high-temperature circulation pump transfers heated thermal oil from the heater to the process equipment. After releasing its heat through a coil, jacket, or heat exchanger, the oil returns to the heater.

The circulation pump must be selected based on:

• Required thermal-oil flow.
• Total piping length.
• Heater pressure drop.
• Process-equipment pressure drop.
• Number of valves and fittings.
• Thermal-oil viscosity.
• Operating temperature.
• Installation elevation.

Sufficient circulation must be maintained whenever the heating elements are energized. Low flow can cause excessive surface temperature, thermal-oil degradation, and damage to the heating elements.

Electrical Power Requirement

At full load, the heating elements consume approximately 80 kWh for every hour of continuous operation.

The circulation pump and control system create an additional electrical load. For example, if the pump motor and auxiliary components consume 5 kW, the estimated total connected load becomes:

$$80+5=85\text{ kW}$$

The required electrical current can be estimated using:

I=3​×V×PFP​

Using an 80 kW heater load, a 400 V supply, and a power factor of approximately 1.0 for resistive elements:

I=1.732×40080,000​ $$I\approx 115.5\text{ A}$$

The electrical panel, cable, circuit breaker, contactor, and busbar must therefore be selected with an appropriate engineering and safety margin. The pump and auxiliary loads must be calculated separately.

Automatic Control Panel

The control panel acts as the central operating and safety system. It can be equipped with:

• Main circuit breaker.
• Heater contactors or thyristor controller.
• Circulation-pump motor starter.
• Overload protection.
• Digital temperature controller.
• Inlet and outlet temperature indicators.
• High-temperature limiter.
• Phase-failure relay.
• Phase-sequence protection.
• Voltmeter and ammeter.
• Automatic and manual selector switches.
• Emergency-stop button.
• Pilot lamps.
• Audible alarm.
• PLC and HMI as optional features.

The control panel can also provide signals to the customer’s central control system.

Safety Interlock System

The heating elements must not operate until the circulation pump has started and adequate thermal-oil flow has been confirmed.

Recommended safety interlocks include:

• Low thermal-oil flow protection.
• High outlet-temperature shutdown.
• Independent overtemperature limiter.
• Circulation-pump overload protection.
• Low expansion-tank level alarm.
• Phase-failure and phase-reversal protection.
• Heater-element short-circuit protection.
• Emergency shutdown.
• Abnormal pressure alarm.
• Sensor-failure protection.

If the circulation pump stops during operation, the system must disconnect the heating elements immediately.

Expansion Tank Function

The expansion tank accommodates the increase in thermal-oil volume as the temperature rises. It also helps remove trapped air and maintain stable suction conditions for the circulation pump.

The tank must provide sufficient space for:

• Thermal expansion.
• Operating reserve.
• Air separation.
• Safe filling and draining.
• Thermal-oil level monitoring.

The expansion tank should be positioned and designed to keep the oil surface temperature relatively low, thereby reducing oxidation.

Estimated Heating-Time Example

The following example assumes that 1,000 kg of thermal oil must be heated from 30°C to 200°C.

Assumptions:

• Thermal-oil mass: 1,000 kg.
• Average specific heat: 0.50 kcal/kg°C.
• Temperature increase: 170°C.
• Heater capacity: 68,800 kcal/h.
• Heat-loss allowance: 15%.

The basic heat requirement is:

Q=m×Cp​×ΔT $$Q=1,000\times 0.50\times 170$$ $$Q=85,000\text{ kcal}$$

Including 15% heat loss:

Qtotal​=85,000×1.15 Qtotal​=97,750 kcal

The estimated heating time is:

t=68,80097,750​ $$t\approx 1.42\text{ hours}$$

The theoretical heat-up time is approximately 1 hour and 25 minutes. Actual heating time may be longer because the heater must also warm the piping, process equipment, insulation, and product.

Commissioning Procedure

The commissioning process includes:

1. Inspecting the heater, piping, valves, pump, and electrical connections.
2. Filling the installation with the recommended thermal oil.
3. Venting trapped air from the system.
4. Starting the circulation pump without energizing the heaters.
5. Checking pump rotation, flow, pressure, and leakage.
6. Testing all alarms and safety interlocks.
7. Energizing the heating elements gradually.
8. Increasing the thermal-oil temperature in controlled stages.
9. Removing residual moisture from the system.
10. Confirming the temperature-controller setting.
11. Recording current, voltage, temperature, pressure, and flow.
12. Providing operational training to the customer’s personnel.

The initial temperature must be increased gradually, particularly if the piping or thermal oil contains residual moisture.

Results and Operational Benefits

After installation and commissioning, the 80 kW Electric Thermal Oil Heater provides the following benefits:

• Stable process temperature.
• Accurate automatic control.
• Clean operation without fuel combustion.
• No chimney requirement.
• No fuel tank, gas train, or fuel pump.
• Low operating noise.
• Reduced routine burner maintenance.
• Easy integration with production equipment.
• High electrical-to-heat conversion efficiency at the heater.
• Improved working conditions around the heating system.

Electric Heater Versus Fuel-Fired Heater

Conclusion

The 80 kW Electric Thermal Oil Heater manufactured by PT Indira Mitra Boiler is suitable for industrial processes requiring clean, reliable, and accurately controlled indirect heating.

Its compact construction, automatic control system, staged electrical heating,.

Its compact construction, automatic circulation-pump interlock, and comprehensive safety devices make it suitable for reactors, mixing tanks, dryers, hot presses, food-processing equipment, chemical processes, and other industrial applications.

PT Indira Mitra Boiler provides engineering, fabrication, installation, commissioning, operator training, maintenance, and after-sales support for Electric Thermal Oil Heaters and industrial boiler systems.