Demonstration of Hydrogen Use in Steam and Air-Assisted Flares

Approximately 80% of flare operators in the U.S. use steam- or air-assisted flares. Since these assisted flare operators do not have the option of hydrogen-fueled compliance like non-assisted flares, many plants currently add natural gas to their flare streams to meet the EPA's 300 Btu/scf minimum requirement. As natural gas prices and pricing volatility have increased over the past decade, flare operational costs have at times become both unacceptably high and unpredictable. Offering multiple compliance methods for steam- and air-assisted flares would be of great value to flare operators in the United States. To this end, Praxair conducted a test program at its flare testing facility to validate the use of hydrogen fuel in steam- and air-assisted flares. Project testing goals, included proving that the use of hydrogen in steam- and air-assisted flares resulted in:

• 98% or greater destruction of waste stream hydrocarbons
• A stable flame
• No visible emissions (i.e. smoke)

The flare operating conditions that met the requirements above for hydrogen use in assisted flares were documented via an equation that correlates hydrogen volume percent in the flare gas to flare exit velocity. These results and the details of the operation and execution of Praxair's flare testing are presented here.
Potential far-reaching benefits of this project include:

• Lower flare operating costs
• Decreased natural gas consumption in assisted flares
• Lower projected environmental emissions from assisted flares

Praxair believes the results of this testing are sufficient to justify extending current EPA regulations to include the use of hydrogen as an approved compliance mechanism for steam- and air-assisted flares. The data generated from Praxair's testing has been submitted to the EPA for possible inclusion in its flaring regulations.