Journal of Pipeline Science and Engineering最新文献

After analyzing existing pipeline-network design solutions in literature, the authors have developed a novel framework model that considers important technical, financial, and environmental factors such as terrain profile, thermal impact, dynamic pump efficiency, cost escalation, tariffs, project phasing, depreciation, and carbon emissions. This comprehensive model not only prioritizes cost optimization for performance measurement but also takes into account tariffs and carbon emissions. To validate the model, the authors conduct a case study on a China multiproduct pipeline and perform sensitivity analysis. The technical model is accurate to 1.1%, except for upstream pressure at the end receiving station. Sensitivity analysis reveals that incorrect judgment of elevation profile, volume escalation, and product temperature variables can render the outcome of pipeline design infeasible. Moreover, neglecting financial components, such as lines fill cost and tankage cost, can cause a variation of 23% in the performance parameters, leading to erroneous decision-making in Pipeline Network Configuration (PNC) design and operations. Lastly, the authors discuss the significance of considering tariff and carbon-emissions performance parameters during design optimization.

The inhibitory effect of La³⁺ on the hydrogen permeation of X70 pipeline steel was investigated via steady-state hydrogen permeation current (i_∞) through electrochemical hydrogen permeation tests. The experimental permeation data were fitted with a constant concentration model and Electrochemical Impedance Spectroscopy (EIS) tests were conducted to characterize the activity of Hydrogen Evolution Reaction (HER) after the optimization of electrochemically active surface area. Additionally, the kinetics of HER and the adsorption/desorption process is calculated by Iyer-Pickering-Zamanzadeh (IPZ) and surface effect models, of which the results demonstrate that the La³⁺ in the corrosion products could effectively reduce the rate of Volmer reaction and hydrogen adsorption process, and accelerate the process of hydrogen atom desorption, thus leading to the remarkable decrease in C₀.

In this article, the observations from two different experimental studies on CO₂ two-phase flow regimes in a near horizontal pipe are analysed. These experiments show significant bubble entrainment in a stratified flow, and the bubble entrainment in liquid is found to be a dominant mechanism for the flow regime transition between the stratified and bubbly flow. The hydrodynamic slug flow is not observed in these experimental studies. The X-ray measurement of the experimental study in a near horizontal pipe of 44 mm internal diameter is processed to obtain the bubble volume fraction in the liquid layer, which is found to be a function of two-phase Froude number. This Froude number definition takes into account gas density and pipe inclination effects. A parametric study shows that the bubble entrainment into the liquid layer decreases significantly with an increase of pipe internal diameter.

In this study, a pulse Cathodic Protection (CP) rectifier was designed and made. The performance of the pulse rectifier was monitored and compared with a conventional system. In this regard, different values of duty cycle (73% and 50%) and frequency (50 kHz and 60 kHz) were analyzed. Results showed that the AC voltage and current consumption dramatically dropped compared to the conventional rectifier. Also, the pulse CP protection potential was distributed more uniformly as a function of pulse parameters in the optimum combination of 50 kHz and 73% for frequency and duty cycle, respectively. This was explained by the changes in the electrochemical polarization resistance of the environment when utilizing the pulse CP.

This paper presents research on the thermophysical properties of an LNG-conveying corrugated cryogenic hose during the precooling process. A numerical model consisting of the $k-ϵ$ turbulent model with enhanced wall treatment and the Volume of Fluid method is established to simulate the cryogenic multiphase flow, along with the energy equation to capture the thermal conduction and convection process. In addition to the analysis of physical phenomena under a specific precooling working condition, parametric studies on the effects of inlet LNG velocity and initial hose temperature on the cooling rate, boiling regime, and structural temperature gradients are carried out. The simulations successfully capture boiling regime transition and discover its significance on the cooling rate. Correlations of structural temperature gradient with the assessed parameters are identified. The findings of this work serve to enhance understanding of the corrugated hose precooling thermophysics in order to guide safer and more efficient industrial operations.

The most common type of Leak Detection System (LDS) is designed to detect leaks that generate a sufficient pressure variation which can be detected at either the inlet or the outlet sensors. However, the pressure variation from low-pressure leaks at locations far away from the inlet and outlet is dissipated before they arrive at these sensors. Thus, these leaks can continue for weeks before they are detected. This work developed a leak detection architecture which comprised of a pressure sensor installed in the middle of the pipeline segment. This sensor was found to be more sensitive to leak-induced pressure variations from leaks far away from the inlet and outlet and this was because leak-induced pressure variation was higher at the midpoint even when it had diminished to zero at the inlet or outlet. The work also developed a Leak Detection as a Service (LDaaS) platform, which utilizes the leak detection algorithm developed from this research and pressure values from the inlet and midpoint sensor to detect real-time pipeline leaks. The midpoint sensor utilizes an exception-based transmission protocol capable of extending the sensor's battery life. Operators can subscribe to the Leak Detection service by installing the midpoint sensor and transmitting the inlet and the midpoint pressure values to the platform. This platform will monitor the pipeline in real-time and detect both the high-pressure and low-pressure leaks which would have ordinarily been missed by the traditional LDSs.

Machine learning (ML) based algorithms, due to their ability to model nonlinear and complex relationship, have been used in predicting corrosion pit depth in oil and gas pipelines. Class imbalance and data scarcity are the challenging problems while training ML models. This paper utilized a conditional generative adversarial network (cGAN) to handle class imbalance problem in a corrosion dataset by generating new samples. Utility of the cGAN data augmentation is evaluated by training an artificial neural network (ANN) model. In addition, random oversampling and Borderline-SMOTE data generating techniques are used for comparison with cGAN. The testing accuracy of the ANN model increased greatly when trained by the cGAN based augmented dataset and this model performance improvement can be useful for a pipeline integrity management.

As the pressure and temperature of natural gas pipelines decreases during operation, water and condensate accumulates form in the low areas of the pipelines, affecting the operational efficiency of the pipelines and even corroding them. The critical gas velocity is a key factor in predicting liquid loading onset in the pipeline, so that appropriate measures can be taken in advance and hazards can be reduced. This paper proposes a model for predicting pipeline liquid loading onset based on the liquid film and wall shear stress of zero, and applicable to different pipe diameters and different inclination angles. This model provides a more simplified and comprehensive prediction of pipeline fluid loading than other models with complex calculations. The critical gas velocity in this model is a function of the liquid holding rate rather than the liquid film thickness, and the critical gas velocity prediction in a phase-inclined pipe is carried out by an improved Belfroid angle correction term. The experimental data, field data and seven models in the published literature were compared and validated, and the errors were judged. The results showed that the new model outperformed the other models in terms of absolute mean error at full inclination angle, and was able to predict the pipeline liquid loading accurately.

A comprehensive numerical investigation is carried out using a newly developed constitutive model to describe failure at low temperatures in multiaxially loaded cracked pipes made of 316L stainless steel. The kinetic phase transformation and the temperature-dependent fracture criterion are implemented to accurately capture the mechanical response at different temperature levels. Although experimental observations of these simulations were not available, their results were quite consistent with some already published results obtained on similar materials and loading conditions at room temperature. The results indicate that the existing multiaxial plastic collapse failure criterion, including shearing, still provides a fail-safe design margin for low temperature loading conditions, including internal pressure. Moreover, martensite kinetic phase transformation plays an important role, especially during straining at low temperatures.

The transportation environment of multiphase pipelines in deepwater gas fields is likely to cause the problem of hydrate flow safety. Aiming at the gas-liquid-solid three-phase flow problem containing hydrate, a hydrate slurry flow model for a multiphase pipeline in a deep-water gas field was developed based on the two-fluid model coupled with the population balance equation, and a mesh was carried out for the axial distance of pipeline and size difference of hydrate particles to obtain a transient solution. The multiphase flow characteristics of the pipeline are simulated upon engineering scale, the transient flow characteristics of gas and liquid phases, the aggregation and fragmentation characteristics of hydrate particles, and the coupling interaction between them were studied, which lays the foundation for further research on the characteristics of hydrate particle deposition and blockage based on particle size distribution. This study provides support for the safety of hydrate flow in multiphase pipelines in deepwater gas fields.