Process Description of ZR-LNG
The patented Gasconsult ZR-LNG (Zero Refrigerant LNG) process is highly differentiated; unlike competing processes it uses no external refrigerants, using the natural gas feed as the refrigerant medium in an optimised system of expanders. This eliminates refrigerant storage and transfer systems and the process equipment used to extract refrigerant components from the feed gas as required for mixed and multi-refrigerant cycles. This reduces equipment count, capital cost and footprint.
An indication of the relative simplicity and efficiency of ZR-LNG compared to mixed and multi refrigerant cycles is provided in the table below.
|Process||Total Equipment Count Single train IBL + OBL||Power Demand kWh/tonne LNG|
|C3MR/DMR – Cascade||64-68||280-310|
In terms of power demand ZR-LNG represents a reduction of 15-25% relative to the triple and dual nitrogen expander processes respectively.
In addition to its low power demand and reduced equipment count a further set of advantages stems from the Zero Refrigerant concept:
- There are no refrigerant logistics issues in remote or offshore locations. Shipments of light and heavy hydrocarbons; and segregated storage to facilitate blending a mixed refrigerant are not required; and absolute security of refrigerant supply is also assured
- There are no propane or other liquid hydrocarbon refrigerants – a major safety plus relative to mixed refrigerant schemes, particularly for FLNG where personnel exit options are limited
- Single phase refrigerant makes the system motion tolerant and well suited to FLNG
- Reduced footprint from the absence of refrigerant infrastructure and simpler C5+ removal makes the system particularly suited to FLNG
- Several operational benefits relative to mixed refrigerant schemes
- no refrigerant make-up cost
- no composition adjustments
- shorter start-up time
- reduced flaring
A full description of the process is available through the video located on the Home page.