High Temperature Hot Water Plants Flashcards
At what temp dose a HTWH start at?
177°c - 350°f
What temp do MTHW systems operate at?
121°c-170°c 250°f- 350°f
What specifications are HTHW BOILERS set to?
ASME Section 1
What boiler type is used for HTHW service?
Water tube boiler
Where is the return water directed
Feed water regulator
Three advantages to using steam boilers for HTHW systems?
a) existing HP plants can be readily converted
b) HTHW and steam systems cab be operated from the same boiler.
c) temp loss of system pressure does not immediately affect steam boiler operation.
How is circulation accomplished in a HTHW generator?
Thermal currents flow from the circulating pumps
Which gas is preferred in pressurized expansion drum
Nitrogen
Why is compressed air not used
Oxygen adversely affects system components.
Dose water or stem have more thermal capacity by volume
Water
Why is a manual vent needed
To vent air
What is the minimum designation grade pipe used for a HTHW system
A54 GRADE A
How is the expansion drum set using a steam pad for pressurization
Horizontally
What temperature are HTHW systems usually limited too
232°c-450°f
What two gasses are used to pressurize a HTHW system
Steam nitrogen
What type of vent is used on a HTHW SYSTEM
Manual
How dose the HTHW boiler differ from HP steam boiler
Boiler nozzle
How is LP steam created in a HTHW system
Immersion generator
Why is the system pressure maintained above saturation temp of water
So HTHW will not flash
Why can smaller diameter lines be used for HTHW systems
HTHW has a higher thermal capacity
Why is the expansion drum elevated when using a steam pad for pressurization
To prevent cavitation In the pumps
All boilers for HTHW systems are designed in accordance with ASME Section 1
True
What is one similarity in steam boiler design used for HTHW installation that is shared with other types of high pressure steam boilers
They are usually of a welded construction
How is the circulation of water achieved on a high temp hot water generator
Circulation is achieved by a combination of thermal currents and flow from the circulating pumps
What are two advantages of HTHW system over steam
Less water treatment is required and there is less internal corrosion because less make up water
