At the end of this module, you will be able to:
- State the purpose of an NCG system
- Describe the makeup of a typical concentrated non- condensable gas stream
- Identify and describe the typical sources of NCGs
- Differentiate between the two methods used to safely convey NCGs
- Identify and describe the major equipment and components of a CNCG system
- List the conditions needed for incineration of NCGs
- List the possible NCG incineration locations within a mill
- Identify and describe safety hazards and safety design features of a CNCG system
The following key questions are answered in this module:
What is the upper explosive limit of a flammable gas and air mixture?
It is the gas to air ratio above which the mixture will not burn.
What are NCGs?
NCGs are Non-Condensable gases. They are compounds which have boiling points above the temperature of most mill water cooling systems.
What is flame speed?
Flame speed is the rate at which a front will propagate through a flammable mixture.
How are steam ejectors used in an NCG system?
Steam ejectors pull NCGs through the system and discharge them to an incineration point.
How do flame arrestors stop a flame?
Flame arrestors absorb heat and cool a flammable mixture to below it's ignition temperature.
Below is a transcript of the video sample provided for this module:
One of the greatest dangers involved with transportation of flammable gases like NCGs is that an ignition might occur. An ignition within the piping system can result in a flame front that accelerates rapidly and generates high pressures. Flame arrestors are usually installed in CNCG piping close to the sources of gas and near the incineration points. These prevent a flame front from entering or leaving the collection piping.
Use the additional resources and links below to learn more about this topic: