Vapor recovery units (VRUs) – also written vapour recovery in British English – capture and recover hydrocarbon vapors generated during storage, transfer, loading and processing operations. Typical applications include oil terminals, tank farms, refineries, petrochemical facilities, marine loading systems and chemical manufacturing plants.
The adsorption-desorption-absorption process combines activated carbon adsorption with vapor concentration and liquid absorption, so hydrocarbon vapors are separated from process gas streams and recovered for reuse or further processing. System design is based on vapor composition, flow rate, operating pressure, recovery objectives and applicable environmental requirements.
Is a vapor recovery unit the right solution for your facility?
A VRU is the technology of choice when the goal is to recover valuable hydrocarbons instead of destroying them. Common drivers:
- Hydrocarbon vapor from storage tanks, loading racks and process vents must meet VOC emission limits.
- Recovered product can be returned to the process or sold, improving site economics.
- Loading and transfer operations generate intermittent, variable vapor flows that need stable, automated control.
How a vapor recovery unit works: adsorption, desorption, absorption
- Adsorption – Hydrocarbon-containing vapor enters the adsorption vessel and passes through activated carbon media. Organic compounds are retained within the carbon structure while the treated gas exits the system.
- Desorption – Once the adsorption bed approaches saturation, regeneration is initiated using vacuum extraction, steam or another selected desorption method. The concentrated hydrocarbon stream is collected for recovery.
- Absorption – The concentrated vapor stream enters an absorption tower where hydrocarbons contact a circulating absorbent and dissolve into the liquid phase.
- Product recovery – The hydrocarbon-rich absorbent is processed through a separation system to recover usable product, and the regenerated absorbent returns to the absorption loop.
Vapor recovery tower: the absorption stage explained
A vapor recovery tower (absorption column) is the stage where the concentrated hydrocarbon stream is absorbed into a liquid phase. Inside the tower, vapor flows upward through structured or random packing while a circulating absorbent flows downward, maximizing gas-liquid contact. The hydrocarbon-rich absorbent is then sent to the separation system, where the recovered product is separated and the absorbent is recycled. Tower design accounts for vapor composition, flow rate, absorbent selection, pressure drop and recovery efficiency.
Typical technical data
| Parameter | Typical range |
|---|---|
| Inlet vapor concentration | 50 – 500 g/Nm³* |
| Recovery efficiency | Up to 99%* |
| Outlet emission level | Project specific |
| Processing capacity | 50 – 10,000 Nm³/h |
| Control system | PLC-based automation |
| Electrical classification | Project dependent |
*Actual performance depends on vapor composition, operating conditions and system configuration.
Key features
- Hydrocarbon recovery – Captures vapors that would otherwise be emitted, allowing recovered product to return to the process.
- VOC emission reduction – Supports compliance by reducing VOC releases from loading racks, storage tanks and process vents.
- Stable operation under variable conditions – The absorption stage accommodates fluctuations in concentration and flow rate.
- Automated process control – PLC-based controls manage adsorption cycles, regeneration, pressure regulation and monitoring.
- Modular design – Skid-mounted configurations simplify transport, installation and site integration.
Vapor recovery unit design considerations
A properly sized vapor recovery system starts with the operating envelope, not a catalogue box. The design review should cover:
| Design parameter | Why it matters |
|---|---|
| Vapor flow rate | Peak and average vapor volume during loading or tank breathing determines vessel and fan sizing. |
| Composition | Hydrocarbon type, VOC concentration, moisture and oxygen content affect media selection and safety design. |
| Operating mode | Continuous, batch loading, intermittent tank breathing or emergency venting changes cycle design. |
| Recovery target | Product recovery, VOC emission limit and outlet concentration target set the process objective. |
| Safety | Explosion-proof design, LEL monitoring, flame arrestors and pressure control are project-specific. |
Where vapor recovery units are used: oil and gas applications
VRUs are the standard solution for hydrocarbon vapor recovery across the oil and gas value chain:
- Oil terminals and tank farms – recovery of gasoline, diesel, condensate and crude oil vapors from truck, railcar and tank loading operations;
- Refineries and petrochemical facilities – control of hydrocarbon emissions from storage systems, process vents, wastewater treatment units and transfer operations;
- Marine loading operations – recovery of hydrocarbon vapors during loading and unloading of marine vessels;
- Chemical manufacturing – recovery of solvents and organic compounds used in production processes.
Demand for vapor recovery equipment continues to grow with tightening VOC emission regulations at storage and loading facilities worldwide. Facilities that recover product rather than flaring or destroying it improve both compliance and operating economics.
Safety and monitoring
Systems may include gas detection devices, pressure protection systems, flame arrestors, emergency shutdown functions, process interlocks and continuous monitoring instrumentation. Safety features are selected according to project specifications and applicable industry standards.
Equipment scope
A typical VRU package may include activated carbon adsorption vessels, vacuum regeneration system, absorption column, circulation pumps, heat exchangers, vapor-liquid separation equipment, PLC control system and instrumentation and safety devices. Actual scope varies according to project requirements.
Engineering and support services
Services may include process evaluation, system sizing and design, equipment manufacturing, installation and commissioning support, operator training, preventive maintenance programs, and spare parts and technical support. For retrofit, commissioning or maintenance work, see the vapor recovery unit maintenance reference.
VRU vs. thermal oxidation: recover or destroy?
A vapor recovery unit recovers valuable hydrocarbons. Thermal oxidizers and catalytic oxidizers destroy VOCs when recovery is not practical or when destruction is required. The right choice depends on vapor value, composition, flow and emission targets.
Related vapor recovery resources
- Vapor recovery unit design guide
- Oil and gas VRU selection for VOC emissions control
- Refinery and tank terminal vapor control systems
- Marine vapor recovery systems
- Gasoline vapor recovery units
- Petrol station vapour recovery systems (Stage 1 and Stage 2)
- Vapor recovery unit compressor
Frequently asked questions
What does a vapor recovery unit do?
A VRU captures and treats hydrocarbon vapor from tanks, terminals or loading operations using adsorption, condensation, absorption, membrane separation or combined recovery processes, returning recovered product where appropriate.
What data is needed for VRU design?
Vapor flow, composition, concentration, temperature, pressure, operating schedule, safety requirements and emission target are needed.
Is a VRU different from thermal oxidation?
Yes. VRUs focus on recovery of valuable hydrocarbons. Thermal oxidizers or catalytic oxidizers are used when recovery is not practical or when destruction is required.
What is a vapor recovery tower?
A vapor recovery tower is the absorption column where concentrated hydrocarbon vapor contacts a circulating absorbent, dissolving hydrocarbons into the liquid phase for subsequent product recovery.
How does adsorption-desorption-absorption recover product?
Activated carbon adsorbs hydrocarbons from the gas stream; a regeneration step (vacuum or steam) concentrates them; and the absorption tower transfers them into a liquid phase from which usable product is separated.
What recovery efficiency can a VRU achieve?
Recovery efficiency can reach up to 99%, depending on vapor composition, operating conditions and system configuration.
Which industries use vapor recovery units?
Oil terminals, tank farms, refineries, petrochemical facilities, marine loading operations and chemical plants all use VRUs for storage and transfer emissions.
What safety features does a VRU include?
Gas detection, pressure protection, flame arrestors, emergency shutdown, process interlocks and continuous monitoring, selected according to project specifications and applicable standards.
When is a VRU better than a thermal or catalytic oxidizer?
When the hydrocarbon vapor has recovery value and the flow, composition and emission targets favor capture. Oxidizers are preferred when recovery is not practical or destruction is required.
What does a typical VRU package include?
Adsorption vessels, vacuum regeneration, absorption column, circulation pumps, heat exchangers, vapor-liquid separation, PLC control and safety instrumentation. Actual scope varies by project.
What is vapour recovery?
Vapour recovery is the British English spelling of vapor recovery: capturing hydrocarbon vapors from storage, transfer, loading and processing operations so they can be recovered or controlled instead of released to atmosphere.
What is the difference between vapour recovery and vapor recovery?
There is no technical difference – vapour (UK) and vapor (US) recovery are the same technology, spelled differently by region. Both capture and recover hydrocarbon vapors from tanks, terminals and loading operations.
What is a vapour recovery system for truck loading?
A truck loading vapour recovery system captures hydrocarbon vapors displaced during road tanker loading at terminals and tank farms. Vapor is collected through the loading arm, then recovered by adsorption, absorption or condensation before the loading rack.
What is a fuel tanker vapour recovery system?
Fuel tanker vapour recovery covers both sides of the delivery chain: vapor return during tanker loading at terminals, and Stage 1 vapour balance when a tanker unloads at a service station. Industrial terminal systems are our VRU equipment; station-side Stage 1 systems are explained in our petrol station vapour recovery guide.
What is a petrol vapour recovery system?
A petrol (gasoline) vapour recovery system captures petrol vapors from storage tanks, loading racks and dispensing operations. At terminals and tank farms, VRUs recover the vapors; at service stations, Stage 1 and Stage 2 systems control delivery and refuelling emissions.
What is a benzene vapour recovery system?
A benzene vapour recovery system captures benzene-containing vapors from chemical, petrochemical and fuel handling operations. Benzene is a regulated VOC with health concerns, so vapor control and recovery are important at storage and loading facilities.
What is a vapour recovery system on oil tankers?
Marine loading vapour recovery systems capture hydrocarbon vapors displaced during loading and unloading of oil tankers and other vessels at terminals. See our marine vapour recovery systems for loading terminals.
How often should a vapour recovery system be tested?
Testing frequency depends on jurisdiction and system type. Regulated facilities require periodic performance and leak testing – for example, filling station vapour recovery systems are typically inspected at least annually, and industrial terminal VRUs should follow the maintenance and compliance plan for the site.
Does a vapour recovery system have to be tested?
Yes, where vapour recovery is required for compliance. Regulators require proof that the system captures and recovers vapor effectively, through pressure tests, leak checks and performance verification on a defined schedule.
What is a vapour recovery compressor?
Some vapour recovery systems use a compressor to boost recovered vapor pressure before condensation or absorption, improving liquid recovery. Compressor selection, like valve and fitting selection, is part of the system design review.
Where can I find a vapour recovery system PDF?
Download the PollutionCtrl product brochure PDF below for an overview of our oil and gas vapor recovery units, RTO, thermal oxidizer and catalytic oxidizer systems.
What is Stage 1 and Stage 2 vapour recovery?
Stage 1 vapour recovery controls emissions when fuel is delivered from a tanker into station storage tanks, and Stage 2 controls emissions during vehicle refuelling at the pump. See our petrol station vapour recovery guide for details.
What does VRU stand for?
VRU stands for vapor recovery unit (vapour recovery unit in British English) – the equipment that captures hydrocarbon vapors from storage, transfer and loading operations.
What is a VRU?
A VRU is a vapor recovery unit: a system that captures and recovers hydrocarbon vapors from tanks, terminals and loading racks, typically using adsorption, absorption or condensation, so product is recovered instead of emitted.
Can a vapor recovery unit handle natural gas and oilfield applications?
Yes. VRUs are used on natural gas and crude oil systems for tank battery vapor recovery, condensate handling and wellhead tank emissions, recovering hydrocarbons that would otherwise be vented.
What is a vapor recovery unit for storage tanks?
A tank VRU captures the vapors displaced during tank filling and normal breathing losses, returning recovered product or directing vapor to treatment, supporting tank farm VOC compliance.
What is driving the vapor recovery units market?
Demand for vapor recovery units is driven by VOC emission regulations for storage and loading operations at terminals, tank farms, refineries and marine facilities, plus the value of recovered product.
What is vapor recovery tower design?
Vapor recovery tower design covers packing type and height, liquid circulation rate, absorbent selection, pressure drop and materials, sized for the vapor flow and recovery target.
What is a vapor recovery unit process flow diagram (PFD)?
A vapor recovery unit PFD shows the process flow: vapor inlet, adsorption vessels, desorption/regeneration loop, absorption tower and product recovery, with major equipment and control points. The diagram is the basis for system design and P&ID development.
What is the purpose of a vapor recovery unit?
The purpose of a VRU is to capture hydrocarbon vapors from storage, transfer and loading operations, recover valuable product, and reduce VOC emissions to meet compliance targets.
Where can I buy a vapor recovery unit?
PollutionCtrl supplies vapor recovery units worldwide. Send your vapor flow, composition, recovery target and site requirements for a system recommendation and quotation.
What is a vapor recovery system P&ID?
A vapor recovery system P&ID (piping and instrumentation diagram) shows vessels, pumps, valves, instruments and safety devices with their interconnections, and is developed from the process flow diagram for engineering and construction.
What is a vapor recovery system on a tanker or tank truck?
Tanker and tank truck loading operations use vapor recovery systems that capture the hydrocarbon vapors displaced during loading, returning them for recovery at the terminal. See our marine vapor recovery page for vessel loading.
What is a vapor recovery system at a gas station?
At a service station, vapor recovery uses Stage 1 and Stage 2 systems to capture petrol vapors during delivery and refuelling. See our petrol station vapour recovery guide for details.
What are vapor recovery tower internals?
Vapor recovery tower internals include packing or trays, liquid distributors, and mist eliminators that maximize gas-liquid contact in the absorption stage for efficient hydrocarbon recovery.
Do you supply vapor recovery compression for oilfield applications in Texas?
Yes. PollutionCtrl supplies vapor recovery systems for oilfield and gas applications, including tank battery and wellhead vapor recovery. Contact us with your site parameters for a feasibility review, wherever the project is located.
What is the cost of a vapor recovery unit?
Vapor recovery unit cost depends on vapor flow, composition, recovery target, configuration (adsorption, absorption or condensation), materials and project scope. Send your parameters for a preliminary budget estimate.
What is a vapor recovery unit compressor?
A vapor recovery unit compressor boosts recovered vapor pressure so hydrocarbons can be condensed or absorbed into liquid product. Compressor selection depends on vapor flow, composition and recovery pressure.
What is the vapor recovery unit working principle?
A VRU captures hydrocarbon vapor from tanks or loading operations, concentrates it by adsorption or compression, and recovers it as liquid through condensation or absorption – reducing emissions while returning product.
What is a vapor recovery unit manufacturer?
A vapor recovery unit manufacturer designs and builds VRU equipment for oil and gas, chemical and marine applications. PollutionCtrl is a VRU manufacturer with custom system design, fabrication and commissioning.
What is a gas vapor recovery system?
A gas vapor recovery system captures hydrocarbon vapors from natural gas and oil operations, including tank batteries, wellheads and loading racks, recovering product instead of venting it.
What are VRU units?
VRU units (vapor recovery units) are packaged systems that capture and recover hydrocarbon vapors from tanks, terminals and loading operations; the terms VRU unit, vapor unit and vapor recovery unit are used interchangeably.
What is a vapor recovery device?
A vapor recovery device is equipment that captures hydrocarbon vapors during storage, transfer or loading – for example a VRU, vapor balance system, nozzle or adsorption unit – to reduce VOC emissions.
What is a vapor recovery unit for natural gas?
A natural gas vapor recovery unit captures condensate and hydrocarbon vapors from natural gas storage and wellhead operations, typically using compression and condensation to recover product.
Request a project evaluation
Selection of a vapor recovery system requires evaluation of vapor composition, flow rate, recovery targets, operating conditions and site requirements. Send your project parameters and we will recommend a practical system and configuration.
Download the PollutionCtrl product brochure (PDF) for an overview of oil and gas vapor recovery units and related VOC control systems.
What is a VRU for oil and gas?
A VRU for oil and gas is a vapor recovery unit that captures hydrocarbon vapors from oil and gas storage, tank batteries and loading operations, including vapour recovery unit oil and gas applications, recovering product instead of venting it.