The patent application involves the incorporation of ammonium absorption chiller proven technology in the pre-cooling stage of the gas liquefaction process in LNG production plants.
LNGI is applying for specific patent protection in several countries, including Australia, in which it proposes producing and selling LNG.
LNGI, a subsidiary of Australian company Liquefied Natural Gas Ltd, has completed the “International Preliminary Examination” phase in relation to its International Patent Application PCT/AU2003/001623 (IPA).
“The International Preliminary Examination Report, issued by the Australian Patent Office, has determined that all the claims in the International Patent Application [IPA] satisfied the three assessed benchmarks of novelty, inventive steps and industrial applicability,” Liquefied Natural Gas Ltd said in a statement.
The ammonia absorption – mixed refrigerant (AA-MR) process, as covered by the IPA, was reviewed by an independent technical expert, US gas processing company Twister BV, which .
found that the AA-MR process as proposed by LNGI was technically feasible
Conventional LNG production processes generate vast quantities of waste heat with only a third of the energy from fuel being converted into useful compressive power required for the refrigeration process and much of the energy being lost to atmosphere. This makes these processes thermally inefficient and generates vast quantities of greenhouse gases.
Twister BV found that the process offered a significant improvement in efficiency over conventional LNG processes results as most waste heat from gas turbine drives would be recovered rather than being lost to atmosphere.
The vast majority of large-scale LNG projects use the propane/mixed refrigerant (C3-MR) cycle with gas turbines for the main compressor drives. Thermal efficiency and greenhouse emissions can be improved by about 25% each by using ammonia absorption technology to replace the propane refrigeration system, according to Liquefied Natural Gas Ltd.
The company claimed that high-level cost comparisons indicated that 25-30% savings on the cost of the MCR compression system and the refrigeration system could be achieved.
“The review undertaken by Twister BV demonstrates the potential of ammonia absorption technology in the production of LNG,” , said managing director Maurice Brand.
“This has considerable benefits for the LNG industry worldwide as companies strive to reduce costs, improve efficiency and minimise production of greenhouse gases.
“For the 700tpd LNG plant proposed by LNGI to be located at Mtwara Port in Tanzania, the plant efficiency is approximately 10 kW/tonne per day (tpd). For a conventional single mixed refrigeration process, the efficiency is 16 kW/tpd, so the AA-MR process is 38% better.”
Liquefied Natural Gas Ltd aimed to be at the forefront of LNG processing, storage and transportation technologies and to position itself as a globally efficient and competitively priced supplier of LNG in the small-to-medium sized LNG production capacity range, said Brand.