39 Questions
What is a fundamental difference between a hot oil system and a hot water heating system?
Hot oil systems use a fluid with a higher boiling point than water.
Why are heat transfer fluids (HTF) preferred in high temperature process applications?
To exhibit lower vapor pressure than steam.
What led to the breakdown of the original oils used in heat transfer systems?
Regular exposure to high temperatures above their stability range.
In what type of applications are heat transfer fluids (HTF) mainly used?
High-temperature process applications preferring low pressures.
How do hot oil systems create and maintain the required circulation of oil?
By employing internal coils and a pump for circulation.
Why might hot oil systems be registered at a lower level than equivalent operational steam systems under jurisdictional regulations?
As a result of their preference for low-pressure operation.
Why is it important for the pump to be located sufficiently below the expansion tank?
To prevent cavitation in the pump suction
Why are centrifugal pumps preferred over gear pumps in liquid thermal systems?
They offer higher flow rates
Why are circulating pumps in liquid thermal systems often water-cooled?
Due to the high temperature of the thermal fluid
What is a common purpose of auxiliary equipment like piping, valves, and pumps in liquid thermal systems?
To facilitate the distribution of hot oil
Which major equipment is central to the return system of liquid thermal systems?
Motorized pump
What is one key advantage of using heat transfer fluids (HTFs) over steam?
Low system pressures
In a vapor-based heat transfer system, what is the role of the saturated gas?
It serves as the heat transfer medium
What is the purpose of the expansion tank in a heat transfer fluid system?
To allow for fluid expansion or contraction
Why are centrifugal pumps typically preferred in liquid thermal systems?
For availability of higher flow rates
What is the main issue caused by overheating and contamination of heat transfer fluids?
Blockage of pipes and valves
Why do heat transfer fluids degrade over time in elevated temperatures?
As a result of oxidation
What is the main function of the condensed HTF in a vapor phase heat transfer system?
To exchange latent heat
Why are liquid-based heat transfer systems less expensive than vapor-based systems?
For their lower overall complexity
What factor influences the choice of HTF for a process requiring high temperatures?
The specified process temperature range
Why is monitoring the level of the expansion tank important in a thermal fluid system?
To accommodate fluid expansion/contraction
Why is it important to remove all traces of old fluid before recharging with fresh fluid in heat transfer systems?
To prevent premature degradation of the new fluid
What hazard is associated with leaks from a heat transfer fluid system?
Potential for explosion due to flammable mist
Why are centrifugal pumps preferred over gear pumps in heat transfer fluid systems?
They allow for higher flow rates
What is the efficiency range of radiant heaters commonly used in heat transfer fluid systems?
40-50%
Which section of a typical fired heater design contains the combustion gases flowing across the tubes?
Convection section
What purpose does the refractory brick serve in a fired heater design?
To contain heat inside the furnace
What potential hazard is introduced by using a hydrocarbon fluid in a heat transfer system?
Burn hazard to personnel
Why is it crucial for liquid thermal systems to have an expansion tank?
To allow for expansion and contraction of the hot oil
What is the purpose of having both radiant and convection tube sections in a fired heater design?
To achieve favorable efficiency levels
Why are most heat transfer fluid systems operated above the flashpoints of the fluids used?
To enhance ignition hazards
Why are hot oil systems provided with automatic shutdown devices or 'interlocks'?
To reduce the risk of major property damage and workplace injuries.
What is the function of a low hot oil flow indicating device in a hot oil system?
To monitor a minimum hot oil flow through the pump.
Why is it important to monitor the expansion tank level daily in a hot oil system?
In case of a leak, to keep the system full.
What is the function of having two hot oil pumps with one operating and the other on standby?
To ensure continuous operation and provide backup in case of failure.
Why is it recommended to leave the suction valve of the standby pump open all the time?
To maintain the standby pump at operating temperature.
What is the purpose of a burner flame failure device in a hot oil system?
To shut off fuel to the burner in case of a flame out situation.
Why is it essential for a pressure/safety relief valve to be located downstream of the heater?
To allow thermal fluid expansion when heated.
What is the main purpose of an expansion (or surge) tank in a hot oil system?
To allow thermal fluid expansion when heated or contract when cooled.
Learn about the importance of replacing degraded heat transfer fluid properly to avoid premature degradation of the new fluid. Discover the narrow operating range for efficient operation and tube wall life preservation.
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