(110d) Thermodynamics of Liquid-Vapour Two-Phase Draft Tubes for Liquefied Gas Expanders

In modern refrigeration process plants the liquefaction of gases is achieved at high pressure to improve the overall efficiency of the cryogenic process. After the condensation of the refrigerated gas the pressurized liquefied gas is expanded across a liquid-vapour two-phase expander to a lower pressure suitable for storage and transportation of the liquefied gas. The expansion process generates a certain amount of vapour and the remaining liquid is cooled down.

The objective is to increase the amount of liquid and to decrease the amount of vapour at the outlet of the two-phase expander. By employing a two-phase draft tube at the exit of the two-phase expander an increase in the amount of liquid is accomplished. The fluid dynamic operation and the thermodynamic performance of two-phase draft tubes is presented and analyzed.