NGL Extraction Plants
Pyramid E&C delivers compact modular NGL extraction plants worldwide supported by our global after sales service network. These plants have several advantages:
- Flexibility to operate in ethane rejection mode
- The pre-engineered modular packages with minimized footprint help easy transportation and quicker installation
- Higher NGL recovery
- Lower power requirement
- Rapid installation and re-deployment of plant mitigate long term project risks
The process comprises of following steps:
Inlet Separation Skid (Feed Gas Conditioning)
Feed gas is to first pass through a coalescing filter/separator designed to remove solid particles and liquid droplets that may carry over from upstream processes. If gas is sour, it is treated in gas sweetening unit for removal of acid gas compounds in an absorption process. Then feed stream is compressed, unless it is already at the required pressure.
Gas is dried to avoid ice and hydrate formation in the cryogenic section of the process, the water content of the gas is reduced to an acceptable level through adsorption in molecular sieve desiccant beds. Downstream of the adsorption beds, the gas passes through a dust filter to remove any particulate carryover before subsequent processing. The regeneration of molecular sieve beds is achieved by heated gas.
Feed Cooling & Separation
Dehydrated gas flows into the cold section of the process, where cooling of inlet gas takes place by exchanging heat with the cold residue gas in a brazed aluminum plate-fin heat exchanger. Condensed liquid is separated from gas in cold separator. The liquid from cold separator is sent to lower section of demethanizer column. Gas from the cold separator is partially sent to turbo expander and remaining gas flows through reflux exchanger. The expansion of gas cools it further and results in additional condensation.
The cold gas from expander is sent to the de-methanizer column. Cooled gas from reflux exchanger is expanded via J-T valve and send to reflux separator. Liquid from the bottom of reflux separator is sent to de-methanizer column. All cooled gas and liquid streams are fed to de-methanizer column. The cold streams are fed to column at different sections column depending on temperatures.
The expansion turbine used in the process can also be configured to recompress the gaseous methane effluent, which ultimately results in lower energy costs.
The NGL plant produces liquid rich in C2, C3, C4 and higher hydrocarbons from bottom and a residual gas from top of demethanizer. NGL’s are fractionated into ethane, propane, butane and C5+ in tailor-made processing plants as per specific requirements of the regional markets and customers.