34 Questions
What is the purpose of locating the pump below the expansion tank?
To prevent cavitation in the pump suction
Why are centrifugal pumps the preferred type in liquid thermal systems?
Because they provide higher flow rates
What is a common auxiliary equipment found in liquid thermal systems?
Valves
Why are circulating pumps in liquid thermal systems often water-cooled?
To prevent overheating of the system
Which major equipment plays a central role in the return system of liquid thermal systems?
Motorized pump
What is the main purpose of a hot oil system in a plant?
To transfer heat from a central source to different plant areas
How do heat transfer fluids used in hot oil systems differ from steam?
Heat transfer fluids run at a lower temperature than steam.
Why are high temperature process applications preferred with heat transfer fluids like hot oils?
Because they can handle high temperatures without breaking down.
What led to the breakdown of the original oils used in heat transfer fluids?
Getting partially oxidized and thermally unstable
Why are hot oil systems often registered at lower levels than equivalent steam systems?
Because of the lower vapor pressure and lower regulatory requirements
What is a fundamental difference between hot oil systems and hot water heating systems?
Hot oil systems operate at lower pressures than hot water heating systems.
What is the consequence of not cleaning the system before recharging it with fresh heat transfer fluid?
Decrease in tube wall life
What is the main reason why exposed piping systems using heat transfer fluid pose a burn hazard to personnel?
High operating temperature of the piping
Which pump type is considered preferable in liquid thermal systems due to higher flow rates?
Centrifugal pump
What is the typical efficiency range for radiant heaters used in heat transfer fluid systems?
40–50%
In a combination radiant and convection heater, where does heat transfer occur?
By both radiation and conduction
What is a key reason why a concrete dike surrounds the foundation of the fired heater?
To prevent hot oil spills
What is a key advantage of using heat transfer fluids (HTFs) over steam?
Low system pressures
In a vapour-based heat transfer system, what does the saturated gas function as?
Heat transfer medium
Why are liquid thermal systems preferred to use centrifugal pumps?
Centrifugal pumps offer higher flow rates
What can cause blockage of pipes and valves in a heat transfer system?
Sedimentation from solids
Why are vapour heat transfer systems generally considered more expensive and complex than liquid systems?
Higher heat transfer rates and temperatures
Which type of heat transfer fluid is typically used for very high process temperatures over 400°C?
Molten salts
Why is the expansion tank critical for the operation of a heat transfer system?
To allow fluid to expand or contract with temperature changes
What can cause corrosion issues within a heat transfer system?
Cleaning fluids left in the system at start-up
How do vapour phase heat transfer systems differ from liquid systems?
They have higher operating temperatures.
What happens to heat transfer fluids over time in elevated temperatures?
They have an increasing potential to deteriorate.
What is the purpose of the expansion tank in a hot oil system?
To accommodate thermal expansion and contraction of the fluid
Why is a low hot oil flow indicating device installed in the outlet line from the heater?
To detect an overheating situation and prevent tube failure
What is the main function of a burner flame failure device in a hot oil system?
To shut off fuel to the burner in case of flame out
Why is a high stack temperature indicator important in a hot oil system?
To signal a tube failure and overheating in the furnace space
What role does an emergency shutdown device play in a hot oil system?
Manually shutting down the plant in case of equipment malfunction or danger
Why is it recommended to leave the suction valve of the standby pump open all the time?
To allow hot oil to flow backwards and maintain pump temperature
What happens if any of the protective devices in a hot oil system senses a malfunction?
The automatic gas shut-off valves close, cutting off fuel supply to burners
Learn about the importance of cleaning the system and removing old fluid before replacing degraded heat transfer fluid. Understand the narrow operating range to prevent premature degradation and decrease in tube wall life.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
