DynMcDermott Petroleum Operations and DOE
In 1992, the U.S. department of Energy found that crude oil stored in the Strategic Petroleum Reserve's salt domes had increased vapor pressure (greater than atmospheric) due to methane from the salt formation, nitrogen from cavern integrity testing, and geothermal heating by the surrounding formation. The stored oil became a "boiling stock" where excess gas bubbles would strip out heavier hydrocarbons at the atmospheric pressure conditions of discharge. Bench testing indicated that, upon release from the reserve, a substantial portion of the lighter oil fractions would be stripped and volatilize creating a large emission of VOCs, HAPs, and hydrogen sulfide (H2S).DynMcDermott developed a prevention solution combining crude oil degassing and cooling. This involved treating and blending the oil inventory at each storage site before draw down. A degas plant (mobile) was used to heat the oil to remove excess gas, recover the majority of propane and heavier fractions, and cool the liquids for return to the inventory. Some of the excess methane fueled the heating/cooling process while the rest was incinerated. The vapor project commenced on 7/29/95 at the West Hackberry facility, proceeded then to the Bayou Choctaw, and continued on to the Big Hill facility in Texas.
The same equipment was reused at all three sites. The waste methane was used as a fuel source, and even the degas foundations were reused when the plant was disassembled. The 500 gallons of ethylene glycol used to dry the oil, and the 800 gallons of diethanolamine used to remove H2S and CO2 were regenerated and reused.
This project prevented approximately 8,000 tons of VOC, 70 tons of H2S, and 59 tons of HAP emissions to air.
Details of ReductionsSource: LDEQ