Pipeline Batch Planning to Optimize Storage Requirements

Abstract

Pipeline batch delivery is a common practice in the industry to transport multiple products in the same pipeline. Proper batch planning can minimize the product storage requirement in operating a pipeline system. Transporting fluids in batches without using separation pigs can result in interface contamination between two different fluids in the pipeline. The volume of interfaces is closely related to the diffusion and dispersions occurred on the interface, which are dependent on product properties such as density and viscosity, fluid flow velocity, flow regime, pipeline mechanical configuration, pipe diameter and roughness, and travelling distance. In general, a turbulent flow is preferred to minimize the boundary viscous layer, thus, reducing the interface volume. The batching sequence is typically arranged so as to achieve the minimum batch interface contamination with the distance travelled. Normally, this is done by arranging the adjacent batches in descending or ascending order of the product quality or density. In this paper, a batch delivery analysis is performed on a proposed multiproduct pipeline to transport eight refined products from a refinery to a delivery terminal through a 240 km NPS 18 pipeline. The minimum volume of each product making up a batch will be sized to allow for reinjection of the interfaces back into the corresponding product tanks at the delivery terminal according to a set of contamination criteria. The proposed batch sequence is to minimize the required tank storage volume. A dynamic hydraulic flow simulator is utilized in this study to confirm the batch planning of the delivery system. The model is developed with the optimized batch plan and the dynamic net tank storage requirement for each product is determined. This paper will detail the methodology for batching design and tank storage calculations.