June 16, 2024
VAPOR RECOVERY UNITS

VAPOR RECOVERY UNITS: REDUCING FUGITIVE EMISSIONS & INCREASING EFFICIENCY

What are Vapor Recovery Units?

A vapor recovery unit (VRU) is a vapor control device used to capture hydrocarbon vapors that would otherwise emit during transferring operations at bulk terminals, refineries and chemical plants. They are commonly used at petroleum product, crude oil and chemical liquid storage tanks as well as during cargo tank loading/unloading at marine terminals.

How do VRUs Work?

A Vapor Recovery Units operates by recovering hydrocarbon vapors displaced during filling operations. When a gasoline truck pulls up to unload fuel into an underground storage tank, vapors will be displaced and rise up out of the tank. The VRU uses a blower or compressor to draw these vapors through pipes back into the fuel truck before they escape into the air. It then returns the captured vapors into the storage tank or transports them to further processing. This closed-loop vapor handling enables flexfuel transfer and storage while minimizing emissions.

Types of Vapor Recovery Units Systems

There are different types of VRU systems used depending on the process:

– Balance VRUs:
Used for balanced vapor/liquid transfer operations like marine vessel loading. They have equal vapor and liquid flow rates to achieve near zero emissions.

– Boosted VRUs:
Utilize a blower to overcome pressure drops in the vapor handling system during transfer. Required for higher throughput operations.

– Scrubbed VRUs: Incorporate absorption technology like carbon adsorption units to further reduce residual vapor emissions below regulatory thresholds.

Benefits of Vapor Recovery

By capturing displaced vapors, VRUs provide significant air quality and compliance benefits compared to uncontrolled venting:

– Reduce VOC and HAP Emissions:
VRUs can achieve 90-98% control of smog-forming VOC and hazardous air pollutant emissions. This lowers a facility’s environmental impact.

– Compliance with Regulations:
Installation of a VRU helps terminals and refineries meet stringent state and federal air emission standards for volatile petroleum liquids.

– Fuel Conservation:
Recovering vapors returns usable product back into storage tanks instead of letting it escape as waste. This improves operational efficiency.

– Odor Reduction: Since odorous hydrocarbon vapors are contained rather than vented, surrounding communities experience less unpleasant smells from transfer operations.

Design Considerations for Effective VRUs

When specifying a VRU system, factors like the following must be considered to ensure optimum performance:

– Vapor/Liquid Flow Rates: Sized appropriately to match maximum projected throughput. Underpowered units can’t keep up during peak operations.

– Piping Layout: Continuous downhill piping routes vapors efficiently without traps or deadlegs where condensate can accumulate.

– controls/ Instrumentation: Automated controls monitor system operation and deactivate transfer if recovery is compromised.

– Maintenance Access:
Designed for easy access to internal components like fans, filters for regular preventive maintenance and inspections.

– Fail-Safe Mechanisms: Include features like emergency vents that safely relieve overpressure while maintaining most capture possible.

With proper design and operation, Vapor Recovery Units systems provide petroleum and chemical facilities a cost-effective method to manage vapors responsibly while increasing throughput capacity and regulatory compliance. Their widespread use has noticeably improved community air quality near industrial areas that handle volatile fuels and chemicals.

*Note:
1. Source: Coherent Market Insights, Public sources, Desk research
2. We have leveraged AI tools to mine information and compile it