A vital safety mechanism in industrial plants, flares stacks are used to burn off flammable gases released by pressure relief valves, avoiding unplanned pressure build-ups and disposing of excess gases. They are also used for the planned combustion of gases over short periods during plant start-ups or shut-downs.
A flare stack is an elevated vertical stack or chimney, and steam-assisted flaring of the associated gas occurs at the top of this structure to control the Combustion Efficiency( CE), a percentage that represents the number of molecules of the compound destroyed by incineration relative to the amount that entered the system. In an efficient flare system, the CE should be 98 % or higher.
Combustion of the vent gas is much more environmentally responsible than simply releasing the gas into the air. For example, if methane is burnt, the products are CO 2 and water, which are much less harmful than releasing methane itself.
Flares are active all the time, with a continuous release of gas being burned off at the flare stack. When this mix of stream and hydrocarbons is correct, the flame is clean and no harmful emissions escape into the atmosphere.
In steam-assisted flares, the ratio of steam to vent gas is critical. Understeaming leads to an inefficient process, while over-steaming can be a cause of incomplete combustion, and visible smoke is a clear sign of pollutants being released into the atmosphere.
Recently, the United States has been a leader in the field of studying flare stack emissions, with the most recent performance tests of steam-assisted flares by Marathon Petroleum in Detroit.
While there are obvious commercial benefits in keeping the process as efficient as possible, these studies are also driven by a desire to stay ahead of impending changes to US Environmental Protection Agency( EPA) regulations.
Based on the latest industry-scale flare tests, the EPA has proposed revisions to the flare exit velocity limit and introduced new metrics for flare operation under refinery Most Achievable Control Technology( MACT) regulations. MACT standards were developed by the EPA to reduce the effects of hazardous air pollutants generated by industry.
The major implication of the proposed rules is the requirement for flare monitoring, which the EPA estimates will cost the industry $ 147 million in capital investment for flare monitoring infrastructure.
The SpectraScan 2400 / H2Scan system is so reliable it can be used as a benchmark to determine the performance of GC / calorimeter analyzers.
FLARE SYSTEM
Servomex’ s system, comprising the SERVOTOUGH SpectraScan 2400 and the SERVOTOUGH H2Scan working in combination, gives a continuous reading with a good compositional measurement.
It measures 14 components, with an overall BTU value and individual component values.
Flare Tip
Pilots
Steam or Air-Assist
Molecular Seal
SERVOTOUGH SpectraScan 2400 H2Scan
Flare Stack
Waste gas from process
Purge
Get advice from the experts: sales @ servomex. com |
Knockout Drum |
Flare Header |
Liquid Seal |
|
|
|
P09 |