What Every Energy Engineer Needs to Know Understanding about the Thermodynamics of Natural Gas Liquefication Systems Part 3B.
In the earlier courses, the basics of thermodynamics were covered and applied to a single-component (pure substance) refrigerant system. The car air conditioner was used as a basis for understanding the vapor compression, pressure let down, and evaporation cooling system. Later, the same concepts were applied to zeotropic mixed refrigerants, which expanded the temperature range for which liquefied natural gas could be made. It was shown that when the feed gas to an LNG plant was pretreated and cooled to -260 F, LNG could efficiently be produced and stored.
Another type of liquefaction system was explained in section 1 of 3. This was the open expansion type of liquefaction system. This system used high-pressure gas from the pipeline to power a liquefaction system by expanding the gas through expanders which produced work. The work from the expanders was used to drive compressors which compressed the gas to be liquefied and expanded to even higher pressures.
In this section, the focus will be solely on the conceptual evaluation of a nitrogen expansion system. Then nitrogen expansion LNG liquefier is not the most efficient liquefaction process, but it is considered the easiest to operate, and it lends itself well to making LNG near its tank saturation temperature, which greatly lessens boil-off management problems. Many of the newer small-scale liquefiers, like those for peak shaving plants, use the nitrogen expansion process. This process has increased in efficiency over recent decades as manufacturing processes have improved, making the expanders and compressors more efficient, thus making the operating cost of this process more cost-effective.
** Mechanical Engineering and Process Engineering ** Dr. Vitale is a graduate of NYU Tandon School of Engineering (formerly NY Polytechnic University) with a B.S., M.S., and Ph.D. in Mechanical Engineering and an M.S. in Civil Engineering. He has been licensed as a P.E. in 6 states and keeps his P.E. licenses active in New York, Pennsylvania, and New Mexico. Dr. Vitale has worked in the natural gas and LNG industry for over 50 years. In 2004 he retired as Vice President and Chief Engineer over Gas Engineering and 28 Production facilities for KeySpan Energy across New York City, Long Island, Rhode Island, Massachusetts, and New Hampshire. During his employment with KeySpan, he often taught Thermodynamics, Heat Transfer, Fluid Dynamics, and other energy courses at NY Polytechnic University. From 2004 to the present, Dr. Vitale has focused on consulting for the Gas Industry with a specialty in training the industry’s human resources on how to make safety and reliability their major focus through understanding the technologies. More than half of Dr. Vitale’s consulting has been focused on training Liquefied Natural Gas (LNG) Operating personnel on generic and site-specific operations of their plants. Dr. Vitale has generated and delivered training materials for import terminals, export terminals, peak shavers, and portable LNG facilities. His courses have been both open-enrollment and plant-specific. He has trained clients in the U.S., Canada, Mexico, South America, Europe, Mid-East, and China. Dr. Vitale has also provided expert testimony for justifying asset (pipeline and service) replacement programs and new facilities (LNG or pipeline or compressors) for system reinforcements to meet the peak-day demands of the industry’s customers. Dr. Vitale’s passion is to train Gas Operators on their gas systems' safe, reliable, and efficient operation and develop a continuous learning culture.
