Volatile organic compounds (VOCs) become incidental emissions for a variety of reasons; as components of multi-component ‘waste’ streams, from incineration, in manufacturing due to evaporation of solvents (e.g. degreasing, printing, painting, air stripping, laminating); and when vapors from volatile liquids are generated and displaced during bulk transfer from storage to receiving tanks. Whether from terminal to on-road tanker, on-road tanker to on-site storage tank, or dispenser to consumer, vapor emissions can and do escape into the atmosphere. Without controls, vapor emissions may result in substantial cost due to product or raw material losses, fines due to regulatory compliance issues, and health and safety concerns.Solution
Most VOC emissions control systems either burn (i.e., thermal incineration, catalytic oxidation) or adsorb (i.e. carbon) vapors that would otherwise escape to the atmosphere.
Thermal oxidation is used in a wide variety of industries, from mixed-waste incinerators to custom designed oxidizers perched on the roof of a manufacturing plant. Catalytic oxidation is frequently used for air stripping, paint spray booths, and temporary pollution remediation systems.
Several large carbon manufacturers offer complete carbon delivery and recycling services to users with relatively dilute process streams. Some processes use chemical absorption (e.g. amine absorption in natural gas sweetening) to remove selected gases from a stream.
Refrigeration and cryogenic systems are sometimes used to chill vapor streams until the desired vapor condenses as a liquid and can be recovered. Typically, these systems entail high capital and operating costs.
Over the past twenty years, a number of specialized gas separation membranes have been commercially developed to process VOCs. These appear to be particularly useful in a number of situations: when VOC loads occur at irregular intervals of short and varied duration or over a wide range of concentrations; when product recycling and recovery is desirable; when incineration is undesirable; when adsorption will not work; and when cryogenics is too expensive.Benefits
CMS membrane systems can separate air from VOCs, venting the air to the atmosphere while controlling and recycling the larger VOC molecules. Storage tanks and vessels can be controlled and kept under slight vacuum relative to the atmosphere, virtually eliminating fugitive and vent emissions from the system.Features of systems containing CMS gas separation membrane systems
CMS fluoropolymer membranes operate by permeating and venting clean air to the atmosphere, while retaining and recycling gasoline vapors to the storage tank. Essentially no emissions occur with power or system failures.
CMS membrane cartridges for controlling gasoline vapor emissions from underground storage tanks are designed to operate in vapor processors certified to meet California Air Resources Board (CARB) standards for preventing gasoline vapor emissions to the atmosphere.
System performance measurements showed total gasoline vapor emissions to be less than 30% of
the allowed maximum.
If you have a process where you wish to control and recycle valuable volatile organic compounds or separate them from air, click on Contact Us at the top/bottom of the page today for an evaluation of CMS gas separations membranes in your specific application.