Gasconsult Technologies
LNG Summary
The indicative performance of Gasconsult’s ZR-LNG and ZR-LNG+ processes against competing technologies is provided in the table below. At the highest efficiency end of the market, ZR-LNG+ achieves an efficiency comparable to the dominant DMR (Dual Mixed Refrigerant) and C3MR (Propane pre-cooled Mixed Refrigerant) base load technologies, but with 30-40% less equipment. For conventional mid-scale plants ZR-LNG has a 5-10% higher efficiency and production capacity than the mainstream SMR (Single Mixed Refrigerant) technology but with a 25% lower equipment count. For small-scale plants ZR-LNG has an equivalent equipment count to nitrogen expander technologies but with a significantly higher efficiency and production capacity. These advantages lead to cost, weight and space savings, increased LNG production/revenues and low carbon emissions across the full range of plant capacities.
The lower equipment count, 15% lower footprint and lower weight of the facility is particularly beneficial for FLNG application as it reduces the deck area and weight of the host hull or platform, further reducing capex. Alternatively, the reduced footprint allows installation of additional productive liquefaction capacity on an existing hull/platform, enhancing project economics. Further details on Gasconsult’s FLNG experience, including the winning of the Petronas Technology Challenge 10, is available through the download Gasconsult FLNG.
LNG (ZR-LNG, ZR-LNG+, IHR and IHR+)
ZR-LNG was developed by Gasconsult to provide a simple, lower cost, lower power demand, easier to operate alternative to SMR processes. ZR-LNG, a methane expander-based process, is self-refrigerating, using the feed natural gas as the refrigerant medium.
All equipment for handling, storing and blending refrigerants (including where necessary refrigerant extraction from the feed natural gas) is eliminated. This reduced equipment count provides a significant capital cost saving plus reduced weight and footprint. Independent analysis by a number of industry players has also confirmed a lower power demand than SMR schemes, the traditionally favoured process for mid-scale projects. Typically, ZR-LNG provides a saving of 5 – 10% of power depending on the SMR variant under review. At an LNG sales price of $10 per million BTU a 10% power demand advantage for a 2 million tpa LNG plant provides over $100 million p.a. additional revenues.
Expander-based processes are also easier to operate than SMR schemes as maintaining SMR efficiency at close to design requires ongoing adjustment of the mixed refrigerant composition. Added to improved safety (no liquid hydrocarbon refrigerants), faster start-up (‹12hrs vs 24hrs+), elimination of logistics issues around refrigerant supply, and no refrigerant make up costs, ZR-LNG makes a compelling case for application on mid-scale liquefaction schemes with capacities up to 2 million tpa of LNG per train.
Given the highly competitive power demand of the ZR-LNG process, Gasconsult has, until recently, had limited incentive to further enhance ZR-LNG’s efficiency. However, with the current demand by LNG buyers for low carbon product, the market dynamic has changed. Gasconsult therefore developed an integrated cooling variant of the process called ZR-LNG+ which achieves a power demand comparable to complex base load DMR and C3MR schemes. It achieves this with an equipment count 30/40% less than the base load schemes, providing a significant capital cost reduction.
There are two further variants of ZR-LNG. The IHR (Integrated Heavies Removal) process removes C5+ and aromatics from raw natural gas, avoiding the need to install an upstream NGL recovery unit to prevent freezing and plugging of the main cryogenic exchanger and ancillary equipment. IHR performs the same steps as an NGL unit using the expander and re-compression facilities already existing in the basic ZR-LNG configuration. This saves ~$50 million relative to an upstream expander based NGL recovery unit for a 2 million tpa LNG train. A further recent development is production of high methane content LNG to meet the 99% methane LNG required for the rapidly growing rocket fuel application. To achieve 99% methane conventional LNG technology would involve complex and capital-intensive cryogenic distillation in the processing configuration. Gasconsult’s solution, IHR+, is a minor variant of the IHR process. Cryogenic distillation is avoided, making the new scheme highly competitive for this application.
A full description of Gasconsult’s LNG processes and details of the validation and engineering development work performed by McDermott is available through the ZR-LNG/ZR-LNG+ video located on the Home page; or through the download Gasconsult LNG.
LH2 (OHL)
Gasconsult’s OHL process (Optimised Hydrogen Liquefaction) is a two-stage scheme comprising pre-cooling and liquefaction steps. It was developed to provide the lower power demand and higher capacity required to make a meaningful and economic contribution to the scale of decarbonisation inherent in the energy transition. Liquefaction reduces hydrogen gas volume by a factor of 800, facilitating transportation and distribution. A schematic of OHL is provided to the left.
The process achieves a power demand, including ortho/para conversion, of <7kWh/kg LH2, some 40% lower than current new build practice. Engineering development has established OHL as viable at capacities up to 350 tonnes per day (125,000 tpa).
Refrigerants are readily available and low cost. Pre-cooling can use either natural gas or nitrogen. The liquefaction step uses hydrogen which is integral to the process. There is no requirement for exotic and high-cost neon or helium, or the complexity of mixed hydrocarbon refrigerants. A number of features are patented and contribute to the reduced power demand.
The process has been validated by two engineering studies, one by McDermott, the other by Costain working on behalf of an oil major. The validations covered process design, evaluation of mechanical equipment availability/performance, design safety issues and environmental impact.
Further information on the OHL process and its development is available through the OHL video located on the Home page or through the download Gasconsult LH2.