Ex-e Immersion Heater, Trace Heating & Control System

  • Client industry of end-user:
    Copper mine in Zambia
    (implemented in conjunction with consulting project engineers in South Africa)
  • Application: Maintain optimal viscosity of gear oils and lubricants of a fuel farm in support of copper mining operation
  • Challenge: Ex-e Zone II T4 area classification
  • Solution: Ex-e rated immersion HFO heater, electrical trace heating, temperature monitoring & control panels
  • Similar solutions: Especially suited for clients across petrochemical-, chemical-, power generation & gas, sugar manufacturing, electrical & automation, metal, mining & mineral processing industries.

Industrial Requirements for custom designed heating system

A fuel farm supporting a copper mining operation is challenged by insufficient flow rates in the distribution system of gear oils and lubricants as the viscosity decreases at lower temperatures.

The client required a complete turnkey heating system to maintain the oil and lubricants between 30-45°C.
Due to the presence of flammable liquids in the area of the tank farm and distribution system, the required system must comply to the Ex-e Zone II T4 area classification.

Engineered to order solution

  • Tank Heating: Ceramic withdrawable immersion heaters
  • Transfer lines: Electrical trace heating cable
  • Temperature monitoring & sensors: 4-20mA puck mounted transmitters, PT100 temperature sensors, Ex thermostat.
  • Control: Custom designed and built control panels - 4kw 230V and 20kW 380V with multiple temperature controllers and DSC fault relays.
The overall turnkey heating solution can be split into 3 sections:
  1. Ex-e Immersion Heaters
  2. Electrical Trace Heating
  3. Control Panels

Ex-e Immersion Heaters

The immersion heaters needed to be certified EX-e Zone 2 T4 to ensure safe heating of oil tanks inside the tank farm.

This design required multiple forms of temperature protection and the use of ex-certified equipment. Strict control of production methods were implemented throughout the design and manufacture stage of the heaters
- supervised by a third party certification authority .

An additional design feature of the immersion heaters is the use of ceramic withdrawable elements, this enable on site replacement of heating elements without the need to remove the immersion heaters from the tank drastically reducing maintenance down time and costs.

Due to strict power limitations the immersion heaters have been designed in a delta configuration to minimize the amount of current used in operation.

Electrical trace heating:
Standard application for heating transfer lines

A parallel electrical trace heating cable was used to maintain the transfer lines in a the hazardous location, temperature control is through unitemp control panels.

Additional over-temperature protection is provided by the self-regulation nature of the heat tracing cable, that decreases the power of the cable as the temperature increases. This ensures that the temperature of the cable never exceeds 85°C.

Centralized control panels
for electrical trace heating and immersion heaters.

Centralized control panels are used to control the immersion heaters, these control panels are located outside the hazardous location in a "safe area" reducing production and installation costs of the panels.

Temperature of the system is controlled by Gefran 600 temperature controllers in conjunction with Unitemp temperature sensors with built in 4-20mA transmitters. A series of interlocks provide additional over temperature and temperature sensor failure protection.




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