Vapor recovery system design starts with the vapor source, gas composition and operating conditions. A vapor recovery unit (VRU) can capture hydrocarbon vapors from storage tanks, truck loading, marine terminals, refineries and process vents so the product can be recovered instead of released or sent to flare.
What information is needed for VRU design?
A preliminary design should include minimum and maximum vapor flow, vapor composition, molecular weight, inlet pressure, temperature, oxygen content, liquid carryover risk, operating hours and the required recovery target. For tank vapor recovery, the breathing and working losses of the tank are also important. For truck loading vapor control, the loading rate and the connection arrangement affect peak flow and pressure control.
- Vapor composition and expected condensable components
- Normal, minimum and peak flow rate
- Inlet pressure, temperature and allowable pressure drop
- Storage tank size, product type and loading schedule
- Recovered-product specification and emission target
Common vapor recovery methods
Compression
A vapor recovery compressor package raises vapor pressure so the stream can be returned to a process, fuel system or sales-gas line. Compressor selection must consider turndown, liquid protection, discharge pressure, anti-surge control and hazardous-area requirements.
Condensation
Condensation cools the vapor stream to recover heavier hydrocarbons. It is useful when the vapor contains a recoverable product with a suitable dew point. A separator and liquid management system are normally required.
Adsorption
Carbon-bed adsorption can polish hydrocarbon vapors and support high recovery performance. The design should account for bed capacity, regeneration method, temperature rise, humidity and possible contaminants.
Combined VRU-CA systems
Condensation plus adsorption can be used when the vapor composition and recovery target require more than one treatment step. The final process is selected from the gas analysis and project economics.
VRU safety and controls
A complete vapor recovery unit includes pressure control, gas detection, emergency shutdown, flame and ignition protection where applicable, explosion-proof instrumentation, liquid carryover protection and PLC/HMI monitoring. The system should be reviewed against the site hazardous-area classification and applicable local requirements.
VRU applications
Typical applications include oil tank vapor recovery, gasoline vapor recovery, refinery and terminal vapor control, marine vapor recovery, truck loading vapor recovery and oilfield vapor recovery. Each application has a different flow pattern and operating pressure, so a standard package should be checked against the actual process data.
Related PollutionCtrl Solutions
For routine VOC destruction after recovery, compare a thermal oxidizer, regenerative thermal oxidizer or catalytic oxidizer. See the oil and gas vapor recovery unit product page for equipment options.
Request a preliminary VRU design
Send the gas composition, flow range, inlet pressure and temperature, storage or loading conditions, operating hours and recovery target. PollutionCtrl can recommend a vapor recovery system configuration and prepare a preliminary technical and commercial proposal through the contact page.
