Purge Gas & Reduction Systems
What is Purge Gas?
Purge gas (or "purge flow") is required to prevent air impingement in the process header where there is little or no process flow going to the flare (as in the case of a dedicated intermittent or ESD flare). If air should enter the flare stack, a release of process gas could result in a combustible mixture present within the flare in a restricted zone. The ignition of this air/gas mixture can result in an explosion and cause severe equipment damage.
Purge gas is used to prevent two possible situations:
- Flame ingress into the flare stack in low flow applications;
- Oxygen concentrations in the stack from exceeding approximately 6% which could allow the ingress of the flame front.
How can I reduce my consumption of Purge Gas?
A velocity seal works by increasing the velocity of the waste gas inside the flare temporarily to push the air flowing down along the sides of the stack out.
99% of Tornado Customers prefer to use velocity seals over molecular seals to avoid the following problems:
- Freezing in the Stack;
- Large Pressure Drops Associated with Molecular Seals;
- Possible Damage that can be done to Molecular Seals due to too high a pressure from an emergency flaring application;
The molecular seal works by using the lighter than air waste gas/purge gas to force the air out at the middle of the seal or heavier than air waste gas/purge gas to force the air out at the bottom of the seal.