Optimal Design of a Multi-Phase Pipeline

A slurry pipeline is one of the transportation modes used for transporting bulk materials for long distance using water or any other type of liquid as a carrier fluid [1-3]. Extensive research has been carried out on the improvement of this type of transportation in addition to the development of alternative ways for transpotation of solid materials. Although the use of fluid flow for transportation purposes has been practiced for more than a millennium, detailed information on the flow behaviour of such complex mixtures in pipelines is still the subject of active research today.

The optimal design of a slurry pipeline includes the selection of the correct pipe sizes, shapes and materials for optimum energy consumption, equipment sizing and reliable operation of the pipeline networks. The prediction of some parameters such as pressure loss, concentration distribution, velocity distribution and wear rate will help the designer to optimise the selection of the design parameters [3-5].

The experimental investigation was carried out to obtain an improved database for modelling the solid-liquid flow in horizontal pipelines. Tests are conducted using uni-sized plastic beads, 4.5 mm diameter and 1329.2 kg/m3 density, as solid particles, and water as a carrier fluid. Frictional head loss is measured as a function of solid concentration and mean velocity. Transparent pipe section is used to study solids’ deposition velocities and solids’ bed. In addition to the experimental results, some other published experimental results are used to develop advanced modelling tools based on an SRC (Saskatchewan Research Council) two-layer model in order to predict and quantify the solid-liquid flow properties horizontally.

In order to improve the accuracy of the predicted data, this study includes improvement over the last previous version of Multi-Layer model for predicting flow properties across the cross-section of horizontal pipes transporting a solid-liquid mixture. The proposed model contains empirical correlations, which incorporate a wide range of experimental conditions. The model is applied for the prediction of concentration distribution of solid particles, velocity profile, and pressure drop. The predicted data are compared with the experimental results of different experimental works.

Furthermore, an optimisation model is developed in the current study based on the least cost principle. This model is designed based on the proposed multi-layer model to find the cost of energy for running any slurry system. In addition, the model has been used to find the optimal diameter of horizontal pipelines transporting slurries.