EMISSIONS REDUCTION
VAPOR RECOVERY UNITS
Vapor Recovery Units (VRUs) recover vent gases from hydrocarbon storage tanks for their reusal. This significantly reduces the release of hydrocarbons into the atmosphere, leading to a smaller carbon footprint.
Methane (CH4) has a forty-times higher greenhouse effect than carbon dioxide (CO2), which makes it a highly polluting molecule.
The most common source of this type of venting is crude oil atmospheric storage tanks, single or in batteries, and in crude oil treatment plants. Depending on process conditions, the recovered gas can be sent directly to the pipeline, used as a fuel, or reinjected into the refining process.
VRUs have a low environmental impact and reduce the overall carbon footprint of the facility.
Flargent together with their partners AGIRA supply vapor recovery units with lubricated vane or screw compressors. All VRUs are delivered completely skidded, with all the necessary components for their correct automated operation (PLC, HMI, motor, scrubbers, air cooler, etc.).
VAPOR RECOVERY TOWERS
When the available pressure in the storage tank vapor vents is in the low range, it is common practice to install a vapor recovery tower (VRT) near the crude oil or fuel storage tank. This acts as a buffer and seals off the recovered vapors. The VRT has an inlet for liquids, which undergo a pressure drop that causes them to flash. The recovered gas exits through the top of the VRT and circulates to the Vapor Recovering Unit (VRU), while the level of liquids is controlled by the gas pressure within the tower.
The diameter and height are defined according to process conditions and tank volume. VRTs guarantee the following benefits:
– Allow the VRU compressor to work in a more favorable range of suction pressures.
– Increase the safety of the VRU processes and prevent the formation of explosive mixtures of vented vapors and O2.
LOW-EMISSION COMBUSTORS
Skid-mounted combustors are used for controlled burning of potentially dangerous vapors. They are used to avoid the venting of vapors to the atmosphere; for example, in the event of a failure of a vapor recovery unit (VRU), a scheduled plant stoppage or for maintenance.
Methane has a forty-times higher greenhouse effect than carbon dioxide; which makes it a highly polluting molecule. For this reason, when a VRU is out of commission or when recovery costs are high, a controlled burning equipment is installed, which is highly efficient in destroying these unwanted molecules. This equipment, commonly known as "CRU" (combustor recovery unit), consists of a main liquid separator and an encapsulated combustor equipped with low-emission, low-pressure burners, mounted on a skid. Another typical example is associating a combustor with a stripping gas recovery unit in a TEG (triethylene glycol) gas dehydration process.
This final disposal solution has a low environmental impact and reduces the carbon footprint of the facility.
BTEX REMOVAL
If BTEX (benzene, toluene, ethylbenzene, and xylene) is present in the gas, unwanted organic BTEX compounds may be absorbed during processes, such as gas dehydration with TEG (triethylene glycol) and amine gas-sweetening units.
BTEXs belong to a broad category of harmful air pollutants. Benzene is a recognized carcinogen causing blood disorders and having adverse effects on the central nervous system and the reproductive system. Toluene can affect the reproductive system and the central nervous system, while ethylbenzene and xylene can be harmful for the respiratory and neurological systems.
In a TEG dehydration unit, the absorbed BTEX is vented along with water vapor at the top of the regenerator column.
Flargent designs skid-mounted equipment to avoid top-of-the-column vapors being released to the atmosphere, directing them to a BTEX emissions capture unit. There, they undergo a partial condensation, and the remaining vapors are sent to a combustor to be burned. This breaks down a large number of molecules and transforms them into CO2 and H20. In turn, condensed liquid hydrocarbons are collected and disposed of by mixing them with crude oil or a condensate stream, which lowers the cost of regenerating the bed and helps meet health and environment goals.
