ABSTRACT

A 1.8 km pipeline equipped with EHT (Electrically Heat Traced) system has been installed and commissioned in 2020 to transport bitumen at a design temperature of 228°C and allow temperature maintenance and reheat up to the minimum flowing temperature (160°C).

During engineering, a risk has been identified where empty sections appear during bitumen cooling, potentially leading to overheat at those locations in the pipeline as the reheat of empty portions will proceed faster than liquid/solid portions.

This paper presents the thermal modelling performed during engineering phase and data obtained during the site acceptance tests, leading to the operating philosophy of the EHT system.

INTRODUCTION

Purpose of this paper is to highlight the challenges of this project regarding thermal engineering and demonstrate how FEA models were validated with field testing.

Following the description of project and its thermal challenges, FEA models will be presented as well as their calibration against field data.

To conclude, the heating strategy is explained and illustrated through two cases.

PROJECT CHALLENGES
Project description

The pipeline presented in this paper is a 1.8km pipeline transporting flowing bitumen between two refineries located across a sea channel in the harbor of Singapore (Salque, Orberg, Geertsen, 2022). This portion is therefore subsea, and Figure 1 below shows an aerial view of the project site and pipeline location.

Thermal requirements

Due to the bitumen properties, it must be transported at an elevated temperature of at least 160°C and the pipeline must be designed to a maximum temperature of 228°C to manage temporary process upsets at the refinery.

Under steady state flowing conditions, the thermal performance of the pipeline insulation allows delivery of the fluid across the channel with a temperature drop below 1°C. During transient conditions (upsets and unplanned shutdowns) there is a potential that the line could cool to the extent that the bitumen cannot flow through the pipeline.

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