Usama Ahmed

Risk-based underground pipeline safety management considering corrosion effect

Due to the long term usage and irregular maintenance for corrosion checks, catastrophic accidents have been increasing in underground pipelines. In this study, a new safety management methodology of underground pipeline, risk-based pipeline management, is introduced reflecting corrosion effect. First, principle of the risk-based pipeline management is presented compared with an original method, qualitative measure. It is distinguished from the qualitative measure by reflecting societal risk and corrosion in safety management of underground pipeline. And then, it is applied to an existing underground propylene pipeline in Ulsan Industrial Complex, South Korea. The consequence analysis is based on real information, and the frequency analysis reflects degree of corrosion. For calculation of corrosion rate, direct current voltage gradient (DCVG) and close interval potential survey (CIPS) are conducted. As a result of applying the risk-based pipeline management, risk integral is reduced by 56.8% compared to the qualitative measure. Finally, sensitivity analysis is conducted on variables, which affect the risk of the pipeline. This study would contribute to introduce quantitative measure to pipeline management and increase safety of pipeline.

Multi-mode operation of principal component analysis with k-nearest neighbor algorithm to monitor compressors for liquefied natural gas mixed refrigerant processes

Abstract LNG mixed refrigeration (MR) process is usually used for liquefying natural gas. The compressors for refrigerant compression are associated with the high-speed rotating parts to create a high-pressure. However, any malfunction in the compressors can lead to significant process downtime, catastrophic damage to equipment and potential safety consequences. The existing methodology assumes that the process has a single mode of operation, which makes it difficult to distinguish between a malfunction of the process and a change in mode of operation. Therefore, k -nearest neighbor algorithm ( k -NN) is employed to classify the operation modes, which is integrated into multi-mode principal component analysis (MPCA) for process monitoring and fault detection. When the fault detection performance is evaluated with real LNG MR process data, the proposed methodology shows more accurate and early detection capability than conventional PCA. Consequently, proposed k-NN integrated multi-mode PCA methodology will play an important role in monitoring the LNG process.

Performance Analysis of Industrial CO2 Capture from Natural Gas using Diglycolamine

Abstract Conventional natural gas sweetening processes are mainly focused on the H 2 S removal with the bulk removal of CO 2 . However, the placement of natural gas processes within the carbon capture and storage (CCS) framework provides an opportunity to achieve the synergies between the two technologies. The purpose of this study is to investigate the CO 2 capture process from the natural gas processing plants. In this study, a steady-state model has been developed that can reasonably predict the CO 2 capture mechanism from the natural gas using diglycolamine (DGA) solvent. The developed model is first validated against a commercial operating plant using the required data and operating conditions. The model is then tested for all the possible key parameters that can affect the performance of the process.

Topside process design for the liquid CO 2 Injection

Abstract Carbon capture and storage (CCS) is one of the dominant technologies to tackle the global warming issue. The transport of CO2 for geological storage is economically feasible by ship when the storage site location is off-shore and instalment of an off-shore pipeline requires a huge capital cost. Ship transportation requires the captured CO2 to be in liquid phase under pressurized thermodynamic conditions. The injection of liquid CO2 into the geological reservoir involves pressurization and heating in order to maintain the safe well head operating conditions. This study presents two alternative top side injection process designs that can reduce the power requirement compared to the base case design. The base case design and alternative designs are simulated using Aspen HYSYS® in order to decide the process design variables. The study employed two-stage rankine cycle in order to extract the cold energy available from the liquid CO2 before its injection into the reservoir. The alternative designs also proposed to utilize a vapor return line in order to maintain the vessel pressure within safe limits by performing a dynamic simulation. Finally, a sensitivity analysis has been done in order to investigate the effect of some important variables in the study.