HYDROCARBON AND VOC VAPOUR RECOVERY TO REDUCE EMISSIONS AND RETURN PRODUCT TO THE SYSTEM
The VRUs capture vapours of hydrocarbons and volatile organic compounds (VOCs) generated during loading, unloading, storage, tank breathing and process ventilation. Unlike a VCU combustion solution, a VRU recovers product and returns it to the system, reducing emissions, venting and economic losses.
In PREMATECNICA we design and integrate VRUs adapted to the type of vapour, range of flow rates, available pressure, composition while maintaining safety requirements, operation and environmental compliance.
WHEN TO CHOOSE A VRU
A VRU is appropriate when the facility needs to reduce hydrocarbon emissions and recover vapour as a product rather than destroying it by combustion. Compared to a VCU, the logic of a VRU is economic and environmental: capture vapours, limit explosive atmospheres and return the recovered hydrocarbon to the tank, line or corresponding system, without generating direct CO2 emissions.
It is useful in fuel terminals, loading and unloading operations, tank breathing, gasoline, crude oil, naphtha and other volatile hydrocarbons, where vapour losses are an environmental problem and a loss of product.
OPERATION AND PRINCIPLE OF RECOVERY
A Vapour Recovery Unit captures the vapour moved or emitted from tanks, pipelines or loading systems and feeds it into a process where the hydrocarbon is separated from the carrier gas. The main technology used is PSA with alternating activated carbon beds, comprising two alternating beds: one adsorbs hydrocarbons whilst the other is regenerated.
For regeneration the system uses vacuum pumps to desorb retained compounds. The recovered gas is then condensed and returned to the plant. The goal is not only to reduce VOC, but to transform an emission into a useful stream and with energy or commercial value.
MAIN COMPONENTS OF THE SYSTEM
A VRU usually includes vapour capture, flame arresters, adsorbent beds, a vacuum or compression system, an absorption tower, a hydrocarbon pumping system, instrumentation, automation and safe operating logic. Additionally, if extra pressure is needed for the gas to be treated, a fan suitable for indoor ATEX zones can be installed.”
DESIGN AND SELECTION CRITERIA
A VRU should be defined from the type of vapour, hydrocarbon concentration, flow rate, pressure available at suction, carried liquid, variability and value of recoverable product. Line geometry, slopes, liquid traps and maintenance of a closed system without oxygen input should also be considered.
To properly size, it is advisable to start from real data: flow rates, gas analysis, pressure profiles and operating scenarios. A design based only on nominal values can compromise recovery, availability or compliance.
PERFORMANCE AND VALUE RECOVERY
A key advantage of a VRU recovery system is that, as well as reducing VOCs, it recovers economic value from vapours that would otherwise be vented or destroyed. Lost vapour is not just an emission: it can also represent lost product, energy and profit.
PREMATECNICA DESIGNS AND IMPLEMENTS YOUR VRU
Each VRU requires a specific design basis. In PREMATECNICA we analyse vapour composition, flow rate, source and destination pressure, continuity of operation, risk of condensation, product type and recovery logic. From this basis we define the appropriate technology and its integration, including capture, separation, adsorption or compression, control and instrumentation.
Our approach combines process criteria, product recovery, industrial safety and emissions control, paying attention to equipment selection and maintenance ease.
