Modelling of the Behavior of the Heated Crude oil in the East African Crude oil Pipeline.

Abstract

The East African Crude Oil Pipeline (EACOP) is designed to transport waxy crude oil from Uganda to the port of Tanga, Tanzania. Uganda's crude oil has a uniquely high pour point of 40°C, making active heating necessary for flow assurance. This research developed an integrated numerical model (Finite Element Method (FEM) and Computational Fluid Dynamics (CFD) in ANSYS) to simulate the behavior of heated crude oil in the East African Crude Oil Pipeline (EACOP) under normal and failure scenarios. The specific objectives were to quantify radial heat loss across the pipe cross‑section for different crude oil fill levels (full, ¾, ½, ¼ bore) and ambient soil temperatures (18 °C to 35 °C), to simulate temperature, velocity, and viscosity profiles along an 18 m pipeline section for five scenarios (normal operation: 50 °C inlet temperature with 70 °C heat trace , heating failure at 50 °C and 40 °C inlet temperature) and to assess the impact of a 20 mm wax layer on those profiles under heating failure at the same two inlet temperatures. The key findings were firstly, the polyurethane foam (PUF) layer contributed 97.8 % of the total thermal resistance, heat loss varied by 32.8 % across the soil temperature range and fill level had a negligible effect when crude oil was present in the pipe. Secondly, under normal heating, the temperature drop was only 2‑3 °C over 18 m and viscosity remained constant; without heating and with a 40 °C inlet, the crude oil cool ed below its pour point (36.5 °C) and viscosity increased by 300 %. Thirdly, a 20 mm wax layer caused a 31‑47 % velocity increase: however, while offering a minor thermal insulation (10 % reduction in cooling rate). The FEM cross‑sectional results were validated against the analytical multi‑layer conduction solution with a deviation <0.2 %. The study concluded that EACOP’s heated and insulated design is sound, but operational success requires maintaining the inlet temperature above 50 °C, proactive pigging before wax reaches 20 mm, and dynamically adjusting heating power according to soil temperature variations.