Roplex adds Rosemount analysers for VRUs

Southampton, UK -- Roplex Engineering, a supplier of vapour recovery units (VRUs), is employing Rosemount Analytical analysers from Emerson Process Management to monitor the effectiveness of its devices at fuel loading facilities.

When empty tankers arrive for refuelling, they are full of air saturated with vapour, up to 40% by volume. As the tanker is filled, the expelled vapour is collected and fed to a VRU where the hydrocarbons are removed before the air is vented to atmosphere.

VRUs have long been installed on petrol tanker loading terminals in line with legislation limiting hydrocarbon emissions. The devices typically have two scrubbers both containing activated carbon; one adsorbs the hydrocarbons and then, once saturated, the beds switch and the hydrocarbons removed and returned to liquid form.

Roplex requires the analysers to detect carbon monoxide in the gas exiting the adsorber bed, as the gas is an early indication of a potentially dangerous upset condition. A second measurement, of butane, is made on the final vent-to-atmosphere to ensure that the VRU is working effectively.

“A prime consideration for these applications is accuracy and reliability,” said John Robson, managing director of Southampton-based Roplex. “We used to purchase cheaper analysers with electrochemical sensors, but we find that the X-STREAM’s proven infrared technology provides a superior solution.”

X-STREAM analysers use non-dispersive infrared, UV spectroscopy, as well as paramagnetic and thermal conductivity detectors to detect oxygen, carbon monoxide, carbon dioxide, hydrogen, or other gases.