Deaeration and Boiler Feedwater Systems

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What is the main purpose of using deaerators in boiler feedwater systems?

To reduce the temperature of water in boilers
To remove dissolved gases from the feedwater (correct)
To prevent the formation of steam in the boiler
To increase the solubility of dissolved gases in water

How does an increase in temperature affect the solubility of dissolved gases in water?

It changes the type of dissolved gases in water
It increases the solubility of dissolved gases
It decreases the solubility of dissolved gases (correct)
It has no effect on the solubility of dissolved gases

What role does steam flow play in deaerator operation?

It ensures efficient mixing to support gas scrubbing (correct)
It increases the solubility of dissolved gases in water
It reduces the surface area of the water
It decreases the residence time of water in the deaerator

How does the use of trays contribute to the efficiency of a deaerator?

It increases the surface area of the water (A) Signup and view all the answers

What happens to dissolved gases when water is heated to just below its saturation temperature in a deaerator?

They come out of solution and are vented (C) Signup and view all the answers

What is the main problem caused by dissolved gases coming out of solution at high temperatures in boilers?

Corrosion (D) Signup and view all the answers

What are the two basic deaerator configurations mentioned in the text?

Tray type and spray type (C) Signup and view all the answers

What is the purpose of cascading water down several trays in a deaerator?

To increase the surface area of the water and promote greater water-steam contact (B) Signup and view all the answers

What is the function of spray nozzles in a spray-type deaerator?

To break up the inlet water into small particles to promote water-steam contact (C) Signup and view all the answers

In a tray-type deaerator, how is the water flow broken up for the deaeration process?

By trickling down over a series of trays (D) Signup and view all the answers

What is the purpose of a safety valve in a deaerator?

To release excess pressure from the system (B) Signup and view all the answers

What happens to the released gases and remaining steam in a tray-type deaerator?

They pass to the internal vent condenser where most of the steam is condensed and gases are vented to atmosphere (C) Signup and view all the answers

What is a bubbling tray deaerator designed to achieve?

Agitation and intimate contact between steam and water for deaeration (D) Signup and view all the answers

What is unique about a combination deaerator?

It combines both spray and tray principles in the deaeration process (B) Signup and view all the answers

How does a combination deaerator handle released gases and remaining steam?

They pass through the incoming water spray on their way to the vent opening, causing most of the steam that is being carried with the gases to condense. (B) Signup and view all the answers

Deaeration and Boiler Feedwater Systems

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