Gas Processing

Merpro designs and builds a range of highly effective gas processing packages.  These can either be for gas scrubbing or gas stripping, as the examples below illustrate.

How it works

Gas Scrubbing – In this particular example, the feed gas to the plant is suction-controlled and passes through suction scrubbers to the compressors.  With a high compression ratio, discharge gas requires cooling and is passed through freestanding air coolers, each of which incorporates automatic louvres for outlet temperature control.  The gas finally passes through discharge scrubbers before being exported through high-accuracy flow meters with temperature and pressure correction.

 

Gas Scrubber Packages - Siemens/NAOC, Nigeria

High performance vane packs within the suction and discharge scrubbers ensure that the dry gas is of a high enough quality for LNG manufacture.  As for the instrumentation for monitoring and control of the gas, this was engineered and procured by Merpro, working in close collaboration with the compressor manufacturers’ engineers to achieve a fully integrated, compatible system of compressor control.

For gas scrubbing applications, Merpro typically provides the suction scrubbers, discharge scrubbers, discharge gas air coolers, flow control valves and ESD valves.

Gas Stripping

Stripping columns are designed to remove 80% of oxylene using air as a stripping gas.  Fresh water enters the top of the first column where it’s distributed over the packing.  The fresh water is then contacted with a counter current air stream, which enters at the base of the packing section.  The air exits from the top of the vessel and is routed to a safe vent whilst the water collects in the bottom of the vessel.  The first column is operated at a slightly higher pressure than the second column in order to provide enough head to distribute the water into the top of the second column.  The water entering the top of the second column is again contacted with a counter current air stream.  The air again exits from the top of the vessel and the water collects in the bottom of the vessel.

The operating pressure of the first column is controlled by a level control valve in the air outlet.  This is set to ensure that there’s sufficient head to lift fresh water to the second column, which is operating at atmospheric pressure and discharging to the water pump skid.  The level of this vessel is controlled with a LCV installed on the pump discharge, which monitors the differential pressure across the packing controls the airflow through each column.

For gas stripping applications, Merpro typically provides the stripping columns, air blowers and water discharge pumps.

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