Heat Transfer Fluid Replacement Precautions
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Questions and Answers

What is the main difference between a hot oil system and a hot water heating system?

  • The fluid chosen in a hot oil system has a higher boiling point than water in a hot water heating system. (correct)
  • Hot oil systems have higher vapor pressure than hot water heating systems.
  • Hot oil systems use water as the thermal fluid while hot water heating systems use oil.
  • Hot oil systems operate at a lower temperature than hot water heating systems.

    • Why are heat transfer fluids like hot oils preferred in high-temperature applications?

  • Due to their low energy efficiency.
  • Because they have high vapor pressure.
  • As they have lower vapor pressure compared to steam. (correct)
  • To maintain high pressures in the system.

    • What issue was faced with the original oils used in heat transfer fluids when the temperature regularly exceeded the stable temperature?

  • They maintained their stable properties.
  • They had higher energy efficiency.
  • They broke down as they became partially oxidized and unstable. (correct)
  • They became more thermally stable.

    • Why are heat exchangers used in hot oil systems?

    <p>To transfer the heat of oil to other fluids.</p> Signup and view all the answers

    How do hot oil systems compare to steam systems under jurisdictional regulations?

    <p>Hot oil systems are registered at a lower level than equivalent steam systems due to lower vapor pressure.</p> Signup and view all the answers

    What is a primary reason for using hot oils as heat transfer fluids over other options?

    <p>Their higher energy efficiency and heat transfer rates initially.</p> Signup and view all the answers

    Why are hot oil systems preferred over steam in many applications?

    <p>Hot oil systems operate at atmospheric or higher pressures.</p> Signup and view all the answers

    What is the main purpose of the expansion tank in a heat transfer fluid system?

    <p>To allow the heat transfer fluid to expand when heated or contract when cooled.</p> Signup and view all the answers

    Why do hot oil systems usually use centrifugal pumps?

    <p>Availability of higher flow rates for enhanced heat transfer.</p> Signup and view all the answers

    What is a disadvantage of using vapor phase heat transfer systems over liquid phase systems?

    <p>Vapor phase systems have a narrower temperature range for control.</p> Signup and view all the answers

    Why do contaminants pose a problem in heat transfer fluid systems?

    <p>Contaminants can lead to blockages, surface spoilage, and impede heat transfer.</p> Signup and view all the answers

    What effect does overheating have on heat transfer fluids?

    <p>Overheating can degrade the fluid and impede heat transfer.</p> Signup and view all the answers

    What equipment allows for expansion and contraction of the hot oil in liquid thermal systems?

    <p>Expansion tank</p> Signup and view all the answers

    What is the primary consideration for selecting the type of HTF (heat transfer fluid) for a process?

    <p>The process temperature requirements</p> Signup and view all the answers

    What issue might arise if an expansion tank in a heat transfer system is not monitored regularly?

    <p>A leak might go undetected</p> Signup and view all the answers

    Why are centrifugal pumps preferred over gear pumps in liquid thermal systems?

    <p>Availability of higher flow rates</p> Signup and view all the answers

    What type of pump is commonly used in liquid thermal systems?

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

    Why are the circulating pumps in liquid thermal systems often water-cooled?

    <p>Due to the high temperature of the thermal fluid</p> Signup and view all the answers

    What is the major equipment in liquid thermal systems that supplies the distribution system?

    <p>Pump</p> Signup and view all the answers

    What is the consequence of not cleaning the system and removing all traces of old heat transfer fluid before recharging with fresh fluid?

    <p>Premature degradation of the new fluid</p> Signup and view all the answers

    In heat transfer fluid systems, what is a potential hazard associated with leaks at high temperatures?

    <p>Production of a potentially flammable mist</p> Signup and view all the answers

    Why are centrifugal pumps preferred in liquid thermal systems over gear pumps?

    <p>Higher flow rates for enhanced heat transfer</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

    What is a key advantage of convection heaters over radiant heaters in HTF systems?

    <p>Higher efficiency</p> Signup and view all the answers

    Why are combination radiant and convection heaters commonly applied in larger units?

    <p>Favorable efficiency</p> Signup and view all the answers

    In a typical up-draft fired heater design, where are the convection tube sections usually located?

    <p>In the breeching</p> Signup and view all the answers

    How are gas burners typically positioned in a horizontal rectangular heater in a direct heater design?

    <p>&quot;Along a center line from front to back on the floor&quot;</p> Signup and view all the answers

    What is the purpose of having a concrete dike surrounding the foundation of the fired heater?

    <p>To prevent hot oil from spreading beyond the immediate area in case of tube rupture</p> Signup and view all the answers

    Why are protective devices necessary in a hot oil system?

    <p>To reduce the risk of fire hazards</p> Signup and view all the answers

    What does a low hot oil flow indicating device aim to prevent?

    <p>Tube failure due to overheating</p> Signup and view all the answers

    Why is it recommended to keep the expansion tank level between 2⁄3 and 3⁄4 full?

    <p>To minimize fluid oxidation inside the tank</p> Signup and view all the answers

    What is the purpose of having an emergency shutdown device/switch in a hot oil system?

    <p>To manually shut down the plant in dangerous situations</p> Signup and view all the answers

    Why are two pumps usually installed in a hot oil system?

    <p>To maintain standby pump at operating temperature</p> Signup and view all the answers

    What happens if the expansion tank level is too high in a hot oil system?

    <p>Risk of fluid oxidation</p> Signup and view all the answers

    Why should a small amount of hot oil flow backwards through the standby pump in a hot oil system?

    <p>To increase mechanical seal lifespan</p> Signup and view all the answers

    What is the function of a high stack temperature indicator in a hot oil system?

    <p>To detect tube failure and combustion hazards</p> Signup and view all the answers

    Why is a pressure/safety relief valve placed downstream of the heater in a hot oil system?

    <p>To release excess pressure and ensure safety</p> Signup and view all the answers

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