(26f) LNG as a Source of Clean Energy

The Liquefied Natural Gas (LNG) industry has gone through a dramatic changes over the years. It is now becoming an annual industry of over 100 million metric tons per annum and is closely related to the combined cycle gas turbine power generation and LNG has now becoming the source of clean energy for the household, the industry and the transporation. This paper intends to present the recent deveopments in the baseload LNG plant liquefaction technology and to discuss what are the considerations for the LNG receiving terminals.

The baseload LNG technology used to rely heavily on Air Products propane-precooled mixed refrigeartion process. Over 85% of the present day baseload LNG plant is based on this technology. However, recent trends have made the competitions quite more intersting. The ConocoPhillips Optimized Cascade Cycle is being revitalized and used to build several plants. The Shell Double Mixed Refrigerant process is being used to some newer plants. The Linde/Statoil Mixed Fluid Cascade process is being used in the Snohvit plant and may be used in more application. Actually, the Linde spiral wound heat exchanger has been used in several plants where Air Products spiral wound heat exchangers were dominating.

Larger baseload LNG plants also push forward technology development in equipment. Aeroderivative gas turbines are going to be used, and the single Frame-9 gas turbines. Air Products has developed a nitrogen expander combined AP-X process. The use of liquid expanders are common place these days. The LNG plants of 7 to 8 million metric tons per annum are being built. Electric motors of the larger size are now being considered in the all electric driven LNG plants to cut down the grrenhouse gas emissons. CO2 is being considered to be reinjected to underground aquafers in the Snohvit and the Gorgon LNG plants.

The considerations of the LNG receiving terminals have also generated new ideas and thinking. The energy integration withe neighboring facilities is considered as necessary. Larger plant for the future also requires the consideratoions of designing the plants with future expansions in mind. These are reflected in the facilities, LNG storage tanks and the marine facilities. Also the environmental and energy efficiency considerations are affecting the use of the submerged combustion vaporizers and the use of LNG for power generation inside the receiving terminal.