Date of this Version
Spring 2016 Research Fair poster, University of Nebraska-Lincoln.
Non-metallic tanks are used in industry to store and transfer gasses such as methane. As the tanks are emptied, the properties of the gas change, causing heat transfer with the tank wall. When emptied while at low temperatures, liquid condensation can form and the tank lining can reach a critically low temperature, causing fracture to the tank wall. In this study, the emptying of methane in cold weather conditions from a non-metallic tank was modelled using Aspen Tech Software. A full tank of methane, at 250 bar and 288 K, was cooled to the following starting temperatures: 263, 253, 243, 233, and 223 K. Additionally, three different mass flows were used, 0.300, 0.119, and 0.064 kg/s. The study included heat transfer with the tank and the environment. Results of the simulations indicated that at a mass flow rate of 0.300 kg/s, and a starting temperature of 223 K, the methane approached and followed the saturation line, signifying risk of liquification. At all other starting temperatures, the methane did not reach the saturation line. Additionally, at lower mass flow rates and all starting temperatures, the methane did not reach the saturation line. Further simulations could be conducted at lower temperature ranges to determine the point at which methane crosses the saturation line.