Heat Transfer Fluid Replacement Precautions
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Questions and Answers

What is the purpose of locating the pump below the expansion tank?

  • To cool down the thermal fluid
  • To enhance heat transfer in the system
  • To increase the flow rate of the pump
  • To prevent cavitation in the pump suction (correct)
  • Why are centrifugal pumps the preferred type in liquid thermal systems?

  • Because they cool down the thermal fluid efficiently
  • Because they are more compact than other types of pumps
  • Because they provide higher flow rates (correct)
  • Because they require less maintenance
  • What is a common auxiliary equipment found in liquid thermal systems?

  • Thermal insulation
  • Electric heaters
  • Pneumatic cylinders
  • Valves (correct)
  • Why are circulating pumps in liquid thermal systems often water-cooled?

    <p>To prevent overheating of the system</p> Signup and view all the answers

    Which major equipment plays a central role in the return system of liquid thermal systems?

    <p>Motorized pump</p> Signup and view all the answers

    What is the main purpose of a hot oil system in a plant?

    <p>To transfer heat from a central source to different plant areas</p> Signup and view all the answers

    How do heat transfer fluids used in hot oil systems differ from steam?

    <p>Heat transfer fluids run at a lower temperature than steam.</p> Signup and view all the answers

    Why are high temperature process applications preferred with heat transfer fluids like hot oils?

    <p>Because they can handle high temperatures without breaking down.</p> Signup and view all the answers

    What led to the breakdown of the original oils used in heat transfer fluids?

    <p>Getting partially oxidized and thermally unstable</p> Signup and view all the answers

    Why are hot oil systems often registered at lower levels than equivalent steam systems?

    <p>Because of the lower vapor pressure and lower regulatory requirements</p> Signup and view all the answers

    What is a fundamental difference between hot oil systems and hot water heating systems?

    <p>Hot oil systems operate at lower pressures than hot water heating systems.</p> Signup and view all the answers

    What is the consequence of not cleaning the system before recharging it with fresh heat transfer fluid?

    <p>Decrease in tube wall life</p> Signup and view all the answers

    What is the main reason why exposed piping systems using heat transfer fluid pose a burn hazard to personnel?

    <p>High operating temperature of the piping</p> Signup and view all the answers

    Which pump type is considered preferable in liquid thermal systems due to higher flow rates?

    <p>Centrifugal pump</p> Signup and view all the answers

    What is the typical efficiency range for radiant heaters used in heat transfer fluid systems?

    <p>40–50%</p> Signup and view all the answers

    In a combination radiant and convection heater, where does heat transfer occur?

    <p>By both radiation and conduction</p> Signup and view all the answers

    What is a key reason why a concrete dike surrounds the foundation of the fired heater?

    <p>To prevent hot oil spills</p> Signup and view all the answers

    What is a key advantage of using heat transfer fluids (HTFs) over steam?

    <p>Low system pressures</p> Signup and view all the answers

    In a vapour-based heat transfer system, what does the saturated gas function as?

    <p>Heat transfer medium</p> Signup and view all the answers

    Why are liquid thermal systems preferred to use centrifugal pumps?

    <p>Centrifugal pumps offer higher flow rates</p> Signup and view all the answers

    What can cause blockage of pipes and valves in a heat transfer system?

    <p>Sedimentation from solids</p> Signup and view all the answers

    Why are vapour heat transfer systems generally considered more expensive and complex than liquid systems?

    <p>Higher heat transfer rates and temperatures</p> Signup and view all the answers

    Which type of heat transfer fluid is typically used for very high process temperatures over 400°C?

    <p>Molten salts</p> Signup and view all the answers

    Why is the expansion tank critical for the operation of a heat transfer system?

    <p>To allow fluid to expand or contract with temperature changes</p> Signup and view all the answers

    What can cause corrosion issues within a heat transfer system?

    <p>Cleaning fluids left in the system at start-up</p> Signup and view all the answers

    How do vapour phase heat transfer systems differ from liquid systems?

    <p>They have higher operating temperatures.</p> Signup and view all the answers

    What happens to heat transfer fluids over time in elevated temperatures?

    <p>They have an increasing potential to deteriorate.</p> Signup and view all the answers

    What is the purpose of the expansion tank in a hot oil system?

    <p>To accommodate thermal expansion and contraction of the fluid</p> Signup and view all the answers

    Why is a low hot oil flow indicating device installed in the outlet line from the heater?

    <p>To detect an overheating situation and prevent tube failure</p> Signup and view all the answers

    What is the main function of a burner flame failure device in a hot oil system?

    <p>To shut off fuel to the burner in case of flame out</p> Signup and view all the answers

    Why is a high stack temperature indicator important in a hot oil system?

    <p>To signal a tube failure and overheating in the furnace space</p> Signup and view all the answers

    What role does an emergency shutdown device play in a hot oil system?

    <p>Manually shutting down the plant in case of equipment malfunction or danger</p> Signup and view all the answers

    Why is it recommended to leave the suction valve of the standby pump open all the time?

    <p>To allow hot oil to flow backwards and maintain pump temperature</p> Signup and view all the answers

    What happens if any of the protective devices in a hot oil system senses a malfunction?

    <p>The automatic gas shut-off valves close, cutting off fuel supply to burners</p> Signup and view all the answers

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