Gas enters the unit at high pressure and flows into molecular sieve dehydration beds for removal of water before flowing into the main cryogenic processing system.
First, the dry gas flows through a high efficiency brazed aluminium heat exchanger for pre-cooling.
Liquid product flows into an accumulator before being pumped into the pipeline through a series of booster and high-pressure pumps.
When the application demands, a mechanical refrigeration system may be provided for additional heat removal prior to preliminary separation of heavier hydrocarbons.
Liquids from the separator are directed to the de-methanizer tower while a portion of the gas flows through the expanding side of a turbo-expander/re-compressor.
Overhead gas from the demethanizer is boosted in the compressing section of the turbo expander/ re-compressor before flowing to the residue compression and into the sales pipeline.
The remaining gas is sub-cooled utilizing de-methanizer overhead vapor in another brazed aluminium heat exchanger to provide reflux to the tower.
The de-methanizer tower provides highly effective separation between methane and heavier hydrocarbons by utilizing the cryogenic temperatures in the top sections to drive heavier components to the bottom of the tower.
A re-boiler is provided to supply hot vapor forcing the methane overhead and to meet liquid product specifications for methane or ethane content.
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Enerflex has a dedicated engineering and design team, resources and fabrication capabilities in its Houston, Texas facility to supply complete cryogenic processing facilities for deep-cut liquids extraction. Systems are engineered to dry and recover natural gas liquids (NGLs) for natural gas feedstock flow rates of 30 to 200 mmscfd utilizing the Recycle-Split-Vapor (RSV) process, or the Gas Subcooled Process (GSP) depending on desired recovery rates. The facilities use turbo-expanders to achieve an ultra-low temperature of -150°F allowing recovery rates of 95+% of the inlet stream’s ethane, 99.8+% of propane and 100% of the butane . The cryogenic plants use a modular design for ease of transport and field assembly and feature fully digitized controls and interfaces for operating flexibility. Enerflex also provides multi-train facilities and complete turnkey solutions including field construction and installation.
Enerflex’s standard design for cryogenic plants includes inlet dehydration using molecular sieve equipment, cryogenic gas processing system, and turbo-expander/re-compressor skid. The flexibility of additional options such as a hot oil system, pipeline pumps, amine treating, inlet and residue compression, and refrigeration equipment to meet specific application demands are available. Enerflex adheres to ASME code for piping and vessels, AISC for structural steel, NEC for electrical and ISA for instrumentation.
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