Characteristics of liquefied petroleum gas in storage during exhaustion process

Abstract

Liquefied Petroleum Gas (LPG) has been regarded as a cleaner fuel because it has less impact on air quality. The study conducted opened up a more realistic solution to predict the actual usage of LPG. This is to minimize the problem related to the residue amount since there was no single method capable to empty the cylinder. Residue problem was still unsolved since at the early stage of LPG usage in Malaysia, therefore, it was considered as one of the national interest projects. The objective of this study is to obtain detailed understanding of LPG characteristics in cylinder during the continuous exhaustion process via modification of the existing operation design. The parameters affecting the evaporation process such as the surrounding temperature, composition, initial flow rate and filling weight of LPG were observed through experimental works on the rig set up. The experimental data was compared with the model that was developed based on fundamentals of material and energy balance under dynamic condition using MathCAD 2000. A rather good agreement between the model and experimental data was obtained. The propane content of minimum of 60%, the quantity filling of minimum and maximum of 62.5% and 84.0% and the surrounding temperature of minimum of 25oC must be considered in the planning of the composition and filling percentage design as well as selection of the installation method. Additionally, based on scaled-up factor the maximum discharging flow rate is approximately 18.0 m3/hr. The distributions of heat in cylinder showed that the sensible heat used for evaporation process is taken mainly at the internal wall. With that, the dominant heat derived for the evaporation process is through the axial direction than the radial direction. Finally, the study indicates that with proper selection of operating parameters the LPG residue in a cylinder could be reduced to less than 10%.