There has been a recent focus on proper design of upstream storage tank control systems by EPA and state air quality regulators. Numerous operators throughout the US have seen multi-million dollar settlements for under designing upstream oil and gas tank vapor control systems. Under-designed systems release methane and other hydrocarbons directly to the atmosphere a violation of air quality regulations and air quality permits. EPA requires a design assessment of control systems on most new upstream storage tanks that is certified by Qualified Professional Engineer under 40 CFR 60 Subpart OOOOa. This same language is proposed to be adopted by Pennsylvania Department of Environmental Protection. EPA has also released an audit protocol for control system design for new owners of upstream facilities. The primary issue is that many upstream vapor control systems are designed assuming they receive a steady flow of oil and water. In reality most storage tanks receive slugs of liquids from separators upstream of the tanks. When the oil or water slug flashes it can overwhelm vapor control systems and result in over pressure of the storage tanks. This presentation will discuss the issue in depth, as well as proper design tools and techniques for these types of vapor control systems including a dynamic approach.
Primary Author / Conference Presenter:
James Van Horne
Senior Engineer
SLR International Corporation
Fort Collins, Colorado, USA