38 Questions
What is the fundamental difference between a hot oil system and a hot water heating system?
The boiling point of the fluid used
Why are heat transfer fluids (HTF), especially hot oils, preferred in high temperature process applications?
As they exhibit much lower vapor pressure than steam
What was a significant drawback of the original oils used as heat transfer fluids?
Stability issues at temperatures beyond rated levels
Why are hot oil systems often registered at lower levels than equivalent steam systems under jurisdictional regulations?
Because of the lower vapor pressure of heat transfer fluids
What component is responsible for creating and maintaining the required circulation in a hot oil system?
Pump
In what applications are heat transfer fluids, especially hot oils, widely used?
Petroleum refining
Why should the pump be located below the expansion tank?
To provide necessary static head and avoid cavitation
Why are centrifugal pumps preferred over gear pumps in liquid thermal systems?
Due to higher flow rates for enhanced heat transfer
What is a common method of cooling the circulating pumps in thermal systems?
Water-cooling
Which equipment is central to the return system in thermal plants?
Motorized pump
What are some auxiliary equipment typically found in thermal systems?
Piping, valves, and pumps
What is the main advantage of using a heat transfer fluid system over steam?
Simple circuit; no blow downs, steam traps, or condensate return systems
Why is the choice of heat transfer fluid (HTF) crucial for a high process temperature vapor system?
Due to limited fluid options at temperatures over 400°C
What is the main function of the expansion tank in a heat transfer fluid system?
To keep the system full in case of a leak
What is the main difference between a vapour phase heat transfer system and a liquid thermal system?
Vapour systems generate HTF vapour at higher temperatures but lower pressures
What may cause blockage of pipes and valves in heat transfer fluid systems?
Sedimentation from solids
Why are liquid thermal systems preferred to use centrifugal pumps over gear pumps?
Centrifugal pumps provide higher flow rates for enhanced heat transfer
Which type of pump is the most preferable in liquid thermal systems due to the availability of higher flow rates?
Centrifugal pump
What is the main reason for incorporating an expansion tank in a heat transfer fluid system?
To allow for expansion and contraction of the heat transfer fluid
What is the main difference between radiant and convection heaters used in heat transfer fluid systems?
Radiant heaters involve combustion gases flowing across tube surfaces
Why is it crucial to clean the system thoroughly before recharging it with fresh heat transfer fluid?
To prevent premature degradation of the new fluid
What type of potential hazards are associated with heat transfer fluid systems?
Fire and explosion hazards
What is the primary function of an expansion tank in a liquid thermal system?
To allow for expansion and contraction of the hot oil
Why are fired heaters typically lined with refractory brick and insulating material?
To prevent overheating of the metal skin
What is the main advantage of using a combination radiant and convection heater in heat transfer fluid systems?
Higher efficiency levels
Why does leaked hot oil pose a serious hazard in heat transfer fluid systems?
'High' potential for serious accidents
'Exposed piping systems are extremely hot' represents what type of hazard?
'Physical hazard'
'Liquid thermal systems consist of a pump, fired heater, and expansion tank' highlights what key component?
Expansion tank
What is the purpose of an expansion tank in a hot oil system?
To allow thermal fluid to expand or contract
Why are multiple burners in a heater not required to all be lit?
To ensure continuous heating even if some fail
What is the purpose of a burner flame failure device in a hot oil system?
To detect and shut off fuel if there is no flame
Why is a low hot oil flow indicating device essential in a hot oil system?
To avoid hot oil coking and degradation
What does a high stack temperature indicator in a hot oil system signify?
Tube failure resulting in oil spray into the furnace
What function does an emergency shutdown device serve in a hot oil system?
To shut down the plant in case of danger or malfunction
Why are two hot oil pumps usually installed in a hot oil system?
To maintain a standby pump for backup
What role does a pressure/safety relief valve play in a hot oil system?
To release pressure downstream of the heater
'Allowing a small amount of hot oil to flow backwards through the pump via a small bypass line' is recommended for what purpose in a hot oil system?
To maintain standby pump at operating temperature
What is one reason why an expansion tank should be monitored daily in a hot oil system?
To keep track of thermal fluid expansion and contraction
Test your knowledge on the importance of proper maintenance when replacing degraded heat transfer fluid to prevent premature degradation. Learn about the narrow operating range for efficient operation and tube wall life. This quiz will help you understand the essential steps to take for optimal system performance.
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