Effect of Chemical Impurities on Centrifugal Machine Performance: Implications for Compressor Sizing in A CO 2 Transport Pipeline [QUERY]

© 2017 The Author(s). Several research studies have been published on CO 2 pipeline transportation. Most of them focus on developing hydraulic models of entire CO 2 pipeline networks. From these studies, a lot of original knowledge has been produced to understand the behaviour of CO 2 pipeline networks under dense phase or supercritical conditions. The globalized modelling approach used in these studies are generally sufficient for carrying out an overall design and operation of an entire CO 2 pipeline network. However, such models are too insufficiently detailed for use in optimizing the performance of a compressor in a CO 2 transport pipeline. This is because in hydraulic models, compression is simulated with adiabatic or polytropic equations which do not account for the geometry and internal fluid flow processes within the compressor. Moreover, in energy requirement calculations involving these equations, compressor efficiency is assumed to be fixed, where as in reality, it varies with change in the purity of the CO 2 stream being compressed. Given that compressors consume most of the energy needed to operate an entire CO 2 pipeline network, it is vital that a detailed analysis of the effect of impurities on machine performance is done as a prerequisite for developing an optimal procedure for compressor sizing and selection. To this end, a quasi-dimensional model based on the laws of conservation was developed and validated for a detailed investigation of the effect of various impurities on the performance of a centrifugal machine handling supercritical carbon dioxide. Results of the study confirm that the power requirement of a compressor is affected by the impurities and provides an insight into the relationship between compressor size, work input and the pressure required to maintain the CO 2 stream flowing in a transport pipeline network in supercritical state

Simulation-based techno-economic evaluation for optimal design of CO₂ transport pipeline network

For large volumes of carbon dioxide (CO₂) onshore and offshore transportation, pipeline is considered the preferred method. This paper presents a study of the pipeline network planned in the Humber region of the UK. Steady state process simulation models of the CO₂ transport pipeline network were developed using Aspen HYSYS®. The simulation models were integrated with Aspen Process Economic Analyser® (APEA). In this study, techno-economic evaluations for different options were conducted for the CO₂ compression train and the trunk pipelines respectively. The evaluation results were compared with other published cost models. Optimal options of compression train and trunk pipelines were applied to form an optimal case. The overall cost of CO₂ transport pipeline network was analyzed and compared between the base case and the optimal case. The results show the optimal case has an annual saving of 22.7 M€. For the optimal case, levelized energy and utilities cost is 7.62 €/t-CO₂, levelized capital cost of trunk pipeline is about 8.11 €/t-CO₂ and levelized capital cost of collecting system is 2.62 €/t- CO₂. The overall levelized cost of the optimal case was also compared to the result of another project to gain more insights for CO₂ pipeline network design

A comprehensive study of the effect of chemical impurities on selection and sizing of centrifugal machines for supercritical carbon dioxide transport pipelines

Compressors and booster pumps constitute the “heart” of the supercritical carbon dioxide transport pipeline network because they consume most of the required energy input. In other words, most of the operating expenditure for the transport pipeline goes to the running of compressors and pumps. The long-term economic feasibility of running such pipeline networks is achievable only if operating costs linked to the energy consumption of both machines can be kept as low as possible. Energy consumption can be kept as low as possible by sizing compressors and booster pumps optimally to ensure that power losses in both machines are minimized. In this study, a quasi-dimensional model based on the laws of conservation was developed, validated with available experimental data and then used for a detailed investigation of the effect of various impurities on the performance of a centrifugal machine handling supercritical carbon dioxide of varying purity. Results of the study show that discharge pressure, power requirement and efficiency of a centrifugal machine are strongly dependent on certain key parameters; namely, the size and speed of its impeller rotor as well as the composition of the impure CO2stream. More importantly, this study also demonstrates that the quasi-dimensional model can be used as a tool for appropriate selection and sizing of centrifugal compressors and booster pumps installed on a supercritical carbon dioxide transport pipeline