A vapor recovery unit for truck loading and tank farms captures hydrocarbon vapors displaced during loading, unloading, storage tank breathing, and product transfer. The recovered vapor can be condensed, adsorbed, absorbed, compressed, or separated by membrane technology depending on vapor composition, flow rate, pressure, and recovery target.
For petroleum terminals, chemical tank farms, and loading racks, vapor recovery reduces product loss, odor complaints, VOC emissions, and safety risks.
Main vapor sources
Typical sources include:
- Truck loading racks
- Storage tank breathing vents
- Tank farm transfer operations
- Ship and terminal loading systems
- Railcar loading
- Gasoline, crude oil, condensate, naphtha, and solvent storage
VRU process selection
| Process | Best use case | Notes |
|---|---|---|
| Condensation | High hydrocarbon concentration | Recovers liquid product but needs refrigeration |
| Activated carbon adsorption | Gasoline vapor and low to medium VOC load | Often used in terminal vapor recovery |
| Absorption | Hydrocarbon vapor with suitable absorbent oil | Can integrate with plant process |
| Membrane separation | Hydrocarbon-air separation | Often combined with compression or adsorption |
| Combustion or oxidation | Vapor destruction instead of recovery | Used when recovery is not economical |
Key design questions
Before selecting a vapor recovery unit, confirm:
- What product is handled?
- What is the vapor composition?
- What are the maximum and average flow rates?
- Is the source continuous or intermittent?
- What is the inlet pressure?
- Is oxygen present?
- What recovery efficiency is required?
- Are explosion-proof standards required?
Truck loading vapor recovery
During truck loading, displaced vapor exits the truck tank and returns through the vapor line. The VRU must handle peak loading flow, pressure fluctuation, and possible liquid carryover. Flame arresters, pressure control, emergency shutdown, and grounding should be considered in the system design.
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FAQ
What does a vapor recovery unit do?
A vapor recovery unit captures VOC or hydrocarbon vapor from tanks, loading racks, or process vents and either recovers the vapor as product or sends it to a safe control process.
Is VRU used for truck loading?
Yes. Truck loading is one of the common vapor recovery applications because vapor is displaced from the tank during filling.
What is the difference between vapor recovery and vapor combustion?
Vapor recovery aims to recover hydrocarbons as usable product. Vapor combustion or oxidation destroys the vapor when recovery is not practical.
