Carbon Retrofit Unit – Retrofit of Existing Active Carbon Recovery Systems

Operators frequently face the following difficulties with existing vapour recovery units based on active carbon adsorption technology: More capacity is required e.g. due to increased transshipment Performance loss of the carbon beds due to accumulation of heavy or aromatic hydrocarbons or contamination by impurities e.g. sulphuric components
The performance of the existing unit is not efficient enough to meet the required emission level
New product vapours have a negative impact on the active carbon or cannot be adsorbed and must be separated before entering the adsorbers


Safety risks related to potentially dangerous exothermic reactions
The BORSIG Carbon Retrofit Unit mainly consists of the membrane unit, a vacuum pump and an optional blower installed upstream from the existing active carbon unit.
A substantial mass flow of hydrocarbons bypasses the adsorber vessels and directly enters the existing absorption system (scrubber). The vapour stream from the scrubber is fed to the membrane unit where it is separated into two streams. The stream passing through the membrane material is highly enriched with hydrocarbons and directly returned to the scrubber. The light hydrocarbon stream, rejected by the membrane, enters the existing adsorber vessels.

The benefits:

Considerable reduction of hydrocarbon mass flow to the carbon bed adsorbers
Increased adsorption performance and process debottlenecking
Increased safety of the carbon VRU due to reduction of exothermic reactions in the carbon beds
Substantially increased capacity of the retrofitted system
Increased efficiency and lower emission level
Pre-assembled, skid-mounted design
Low maintenance
Reduced specific power consumption
Easy and cost effective integration with only minor modifications of existing active-carbon unit