A transient technique has been used to study the rate of evaporation of Freon-11 contained in a 0.3 m diameter × 0.7 m high cylindrical glass vessel. Saturation pressures ranging from 7.5 to 10.5 kPa gauge were first established by adjusting the temperature of a water bath in which the tank was submerged. The pressure was then reduced linearly with time, and the resulting evaporation measured by condensation of the vapour issuing from the tank. Rates of depressurization from 1.9 to 6.3 Pa s−1 were employed.It was observed that nucleation was initiated and evaporation rates were increased when the liquid superheat exceeded 1.5 K. In the non-nucleate, or quiescent regime, which is believed to be that which exists in large scale liquefied gas storage tanks, the rate of evaporation (w) was correlated by w = 2.37 × 10−8 (ΔP)1.33 kg s−1 m−2. The exponent of the supersaturation pressure is almost identical to that found in previous studies of water evaporation. In non-dimensional form, the data are represented by This equation is shown to give a good prediction of published data on the rate of evaporation from tanks of LNG, which exhibits a similar Rayleigh property to Freon-11. The nature of the liquid phase convective process in the surface layer which appears to control the rate of evaporation is also discussed. 相似文献
For a liquefied natural gas (LNG) storage tank, the greatest concern is for the release of a large amount of LNG or its vapor
due to the mechanical failures of main tank and its ancillary equipments or the malfunctions of various hardware components.
Nowadays two types of LNG storage tank design, that is, 9%-Ni full containment and membrane concepts, are mostly applied to
LNG industry. In Korea the membrane type has been nationally adopted from the beginning step of LNG project because of its
higher flexibility in storage capacity comparing to the 9%-Ni type. All the while several huge membrane-type tanks have been
built up and operating, the quantified results of risk associated with them has not been systematically delineated. Hence
the method of fault tree analysis as a quantitative risk assessment has been here employed to identify and evaluate the risks
related to the membrane-type LNG storage tank. Six top events leading greatly to the large release of natural gas are defined
as internally induced major accidents and the failure frequencies of these events are calculated by using other sources of
process equipment reliability data for the lack of membrane type-specific data. 相似文献
Although the operation of an LNG receiving terminal, especially for LNG unloading process, is important in terms of economics
and safety, the systematic approach for this process is deficient with regard to operating variables and inherent terminal
characteristics. Because the characteristics of each LNG terminal vary according to its individual condition, it is worth
to investigate the operational method manipulating operating variables to reduce operating costs regarding terminal characteristics.
In this study, we perform a rigorous and extensive dynamic simulation of LNG unloading process to demonstrate the effects
of terminal characteristics, including the total length of the pipeline, the number of storage tanks, the ambient temperature,
and the operation cycle. Based on simulation results and cost analyses, we can suggest an operational strategy to minimize
the operating cost in LNG receiving terminals. 相似文献