With the growing demand and increasing price for natural gas in the United States, Europe and Asia, the transport of liquefied natural gas (LNG) via ocean tankers is increasing in demand. This process involves cooling the natural gas to -260oF (-162 oC), so that it is liquefied and loaded efficiently and transported via tanker. At the receiving end, the LNG must be reheated back to a gaseous state. The amount of heat required to vaporize the LNG in a typical 1 billion ft3/day plant is approximately 850 million BTU per hour. In most cases, this heat is delivered through burning natural gas in high efficiency vaporizers, consuming between 1.5 percent to 2.5 percent of the terminal's total throughput.
SPX Cooling Technologies, Overland Park, Kansas, has developed vaporization systems that use heat from the atmosphere working in parallel with gas combustion units. In these applications, the amount of natural gas required has been reduced by 60 to 90 percent on an annual basis. The heating tower design allows maximum atmospheric heat transfer while optimizing footprint and electrical power consumption.
A recent installation was designed to handle the heating load requirement of 1 billion ft3/day for a terminal in the U.S. Gulf area. SPX Cooling Technologies installed a 12-fan-cell tower with 10-meter fans, equipped with 250-hp motors, that delivers 90 percent of the annual heat load. Each cell measures 54' by 54' and delivers enough heat to vaporize 83.3 million ft3/day of natural gas. Performance predictions are based on the U.S. Gulf area's annual weather conditions.