Two-Phase Flow Design of the Spill Pipe System for the Liquefied Gaseous Fuels Spill Test Facility

摘要

Cooldown and pressure drop design of the liquid delivery pipe system are analyzed for a Spill Test Facility proposed for studying the effects and dispersion of spills of liquefied natural gas (LNG) and other liquefied gaseous fuels (LGFs). The design analyzed includes a 488-m (1600-foot) long, 0.61 m diameter (24 inch nominal size) delivery pipe to carry the LNG from the storage tanks to the spill area where experiments are conducted. Various methods of cooling the pipe to LNG temperature are examined. Cooldown with LNG flow at between 2.0 and 2.4 m sup 3 /min is recommended because it is the fastest method and requires the least amount of on-site equipment of the methods examined. Pressure drop is also examined because 200 m sup 3 /min flowrate must be achieved within the 1.03 MPa (150 psig) allowable pressure rating of the storage tanks. The LNG will be pushed out of the tanks and down the delivery (or spill) pipe by injecting pressurized nitrogen (N sub 2 ) gas into the tank vapor space. Existing tanks will be used, so their pressure rating of 1.03 MPa (150 psig) governs the design. The effects of phase change and two-phase flow in the spill pipe are included by use of the Martinelli and Nelson (1948) correlation for two-phase flow. A modification is made to the Martinelli and Nelson correlation at low qualities (below 1.8% for LNG) to account for uncertainty in the correlation at low quality. The results of the pressure drop analysis show that a flowrate of 200 m sup 3 /min can be achieved with 1.03 MPa (150 psig) drive gas pressure. This assumes that the spill pipe is completely precooled (with no residual heat remaining) and that LNG is stored with a saturation temperature of not over 110.7 sup 0 K (199.3 sup 0 R) in the storage tanks (corresponding to a saturation pressure of not over 3.45 x 10 sup 3 Pa (0.500 psig)). 32 refs., 10 figs., 9 tabs. (ERA citation 13:000247)