LNG Vaporizer Utilizing Vacuum Steam Condensing
This report concerns the field test results of a new type of peak-shaving LNG vaporizer (VSV) whose heat source is vacuum steam. The VSV utilizes the condensation latent heat of vacuum steam to vaporize and superheat LNG within heat transfer tubes. Prior to the field test, water and liquified nitrogen (LN2) were used as the medium for the heated fluid in order to confirm the basic heat transfer characteristices of vacuum steam and the influence of non-condensable gasses. In the field tests, the heat transfer performance, controlability and a transient response were confirmed in a scaled-down model device using external steam as the heat source.
As a result, it was confirmed that: (1) a high heat transfer coefficient is obtained on the outer surfaces of the heat transfer tubes where the vacuum steam is condensing. (2) quick load change is possible and the outlet temperature drop rate is gradual when the heat source is cut off. (3) non-condensable gasses on the outer tube surfaces which obstructs heat transfer could be easily removed. These results indicate that this vaporizer responds flexibly to operating conditions and is suitable for a wide range of applications.
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