This paper presents the development of an artificial neural network (ANN) Gas Path Diagnostics (GPD) technique applied to pipeline compression system for fault detection and quantification. The work detailed the various degradation mechanisms and the effect of such degradations on the performance of natural gas compressors. The data used in demonstrating the ANN diagnostics is so derived using an advanced thermodynamic performance simulation model of integrated pipeline and compressor systems, which has embedded empirical compressor map data and pipeline resistance model. Implantation of faults within the model is in such a way to account for faults degradations caused by fouling, erosion and corrosion, of various degrees of severities, to obtain wide range of corresponding simulated “true” measurements. In order to account for uncertainties normally encountered in field measurements, Gaussian noise distribution was combined with simulated true measurements, which depends on the instrument’s tolerances. Furthermore, since judicious measurements selection are crucial in ensuring flawless GPD predictions, a sensitivity and correlation analysis of the available measurements revealed that discharge temperature, rotational speed and torque are the most effective measurements for the diagnostics with acceptable degrees of accuracies. The measurements observability technique is a novel approach in pipeline compressor diagnostics. Analytical case studies of the developed method show that, a selected ANN architecture can detect and quantify faults related to degradation in efficiency and flow capacities in the presence of instrument error, varied operational and environmental conditions.

Natural gas pipeline plays an important role in transporting natural gas over a long distance. Its performance and operating behavior are affected by many factors, such as ambient conditions, natural gas flow rate, operation and control of compressor pumping stations, etc. Better understanding of the performance and behavior of an integrated pipeline-compressor system used for gas transmission will be beneficial to both design and operation of natural gas pipelines. This paper introduces a novel steady-state thermodynamic performance simulation approach for natural gas pipelines based on fundamental thermodynamics with the inclusion of the coupling between a pipeline and compressor pumping stations. A pipeline resistance model, a compressor performance model characterized by an empirical compressor map and a pipeline control schedule for the operation of an integrated pipeline-compressor system are included in the simulation approach. The novel approach presented in this paper allows the analysis of the thermodynamic coupling between compressors and pipes and the off-design performance analysis of the integrated pipeline-compressor system. The introduced simulation approach has been applied to the performance simulation of a typical model pipeline driven by multiple centrifugal compressor pumping stations. It is assumed in the pipeline control schedule that the total pressure at the inlet of compressor stations is kept constant when pipeline operating condition changes. Such pipeline operating conditions include varying ambient temperature and varying natural gas volumetric flow rate. The performance behavior of the pipeline corresponding to the change of operating conditions has been successfully simulated. The introduced pipeline performance simulation approach is generic and can be applied to different pipeline-compressor systems.

The decision-making process behind the selection of a gas turbine engine (GT) is crucial and must be made in accordance with economic, environmental, and technical requirements. This paper presents the relevant economic, exergoeconomic and exergoenvironmental analyses for four GT engines with different compressor configurations. The GT engine configurations are identified according to the type of compressor: axial, axial-centrifugal, two-stage centrifugal, and centrifugal-centrifugal. The performances of the four GT engines were validated against manufacturer supplied data using specialized software. The economic analysis, a detailed life cycle costing considering the cost to be paid per unit net power obtained from the GT, and subsequent shortest payback period showed that the GT with centrifugal-centrifugal compressor was most economically feasible. This was followed, in order, by the GT-axial, GT-axial-centrifugal, and finally the GT-two-stage centrifugal configuration, where the cost of ownership for a 20 year plan ranges between 8000 USD/kW to about 12,000 USD/kW at different operational scenarios during the life cycle costing. Exergoeconomic assessment provided useful information to enhance the cost-effectiveness of all four systems by evaluating each component separately. The axial-centrifugal configuration registered the lowest CO2 emissions (about 0.7 kg/kWh); all environmental indicators confirmed it is the most environmentally friendly option.