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15 Cards in this Set

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  • Back

What does the Anhydrous Amonia tank use as a means to pressure up?

Vaporizer Skid

What pressure does the Amonia tank normally run at?

Approximately 55 - 75 psi. The vaporizers are used to heat and pressure up the tank.

What are the reliefs set at on the Anhydrous Amonia NH3 tank? On the liquid lines? Why are these different?

Tank - 275 psi

Line - 400 psi

This is due to thermal expansion, there are reliefs on the liquid lines anywhere it can be isolated from the tank.

What special precautions must be taken when bleeding off sections of NH3 piping?

NH3 should be bled into a bucket of water and not to atmosphere.

What is considered a high temperature downstream of the vaporizer heaters? When will the trip?

Alarm 110° F

Trip 114° F

What actions would you take on high pressure and/or temperature in the Anhydrous NH3 tank?

Ensure the vaporizers are turning off. If temperature downstream of the heaters should shut off automatically at 114F if not shut off manually. This could be a sign of water in the vaporizers or tank and the temperature switch is malfunctioning.

What actions would you take on low pressure in the Anhydrous Amonia tank?

Check vaporizers and breakers. Check regulators.

What pressure would be considered acceptable at the inlet on the SCR Skids?

41-65 psi (typically regulated to 42 psi)

What is the temperature permissive for placing the Amonia injection in service?

>500° F SCR inlet Gas temp

Explain the aux operators actions in the event of a total loss of the NH3 system?

Work with the control room and see if there is anything that can be checked in the field. If the loss is due to a regulator failure then the regulators will need to be swapped using caution not to trip the excess flow valve.

What would cause the offload valve to go closed and not allow them to open?

Amonia detector in alarm or tank high level.

When should an offload be stopped to avoid hitting the high level lockout?

75% or 10,000 gallons because the lockout will trip at 10,200 and there needs to be room to blow the lines out.

Why should you open the valves slowly when swapping Anhydrous Amonia regulators?

It could trip the excess flow valve causing a loss of flow of the Amonia system to the units.

At the NH3 storage tank and Amonia gas warning will initiate at ____ ppm and reset at ____ ppm. An alarm will initiate at ____ ppm and reset at ____ ppm.



Amonia = TWA ____ ppm, STEL ____ ppm.