Session: 02-10 DESIGN - Hydraulic Modelling

Paper Number: 131162

131162 - Increasing the Operational Reliability of an Onshore Pipeline Using Positive Displacement Pumps 

Abstract: 

This abstract presents a proposal to adapt the pumping system of the OSVAT 24” oil pipeline at the REVAP refinery in the State of São Paulo, Brazil. The pipeline, approximately 120 km long with a nominal 24-inch diameter, connects the refinery to the São Caetano do Sul Terminal, transporting hydrocarbons produced by the refinery. The OSVAT 24" pumping system at REVAP is composed of three main pumps in sequence and two booster pumps operating in parallel. The booster pump pumps the product to the heat exchanger, where its temperature rises up to 85 °C. The heated product travels to the oil pipeline via the main pumps, while low-viscosity products bypass the heat exchanger, proceeding directly from the booster pump to the main pumps.

The OSVAT 24” pumps installed in the refinery were originally designed for products with viscosities lower than those of the fuel oils that are produced today. Over time, the refinery developed new fuel oils, many with viscosities exceeding 600 cP (@50 °C). If the pumps operate below their minimum steady continuous flow rate, the heat transferred to the system by the product entering the pipeline will not be sufficient to maintain the overall thermal state of the system, therefore, a cooling process is established, increasing the pressure required at the pump system to the point where flow may become unfeasible. In addition to severe vibrations and bearing failures, pumps operating below their minimum steady continuous flow rate might also fail because of excessive pump heating.

The need for pumping system adaptation arose due to a different product profile with higher viscosity, placing the pumps outside their best-efficiency region. Consequently, a more suitable pumping system was designed to pump fuel oils, enhancing the operational reliability of the OSVAT 24” and preventing fuel oil stoppage in the pipeline, which could lead to temperatures below its pour point.

The viscosity of the fluid significantly affects the pump’s efficiency. According to the “Centrifugal Pump Handbook” by Sulzer Pumps, economically viable viscosity for centrifugal pumps ranges between 150 and 500 cSt. As a solution to increase the operational reliability of the OSVAT 24” pipeline, we decided to install a new pumping system composed of positive displacement pumps with heat exchangers located downstream of the pumps. The selection of the positive displacement pump of the screw type was based on the guidelines of the API STD 676 standard, taking into account the flow and the maximum operating pressure allowed for the OSVAT 24”. Computational simulations using the Stoner Pipeline Simulator program, version 9.8, were carried out to verify the selection of this new pumping system. The simulation results demonstrate that the suggested pumping system is feasible and has the potential to enhance the dependability and efficiency of fuel oil transportation.

Presenting Author: André Auras Petrobras Transporte S.A.

Presenting Author Biography: Technical consultant with experience in engineering projects for the transfer and storage of hydrocarbons and biofuels. Working at Petrobras Transporte (Transpetro) mainly in brownfield pipeline and terminals projects in Brazil.

Authors:

Marcus Valle Petrobras Transporte S.A.
André Auras Petrobras Transporte S.A.