Tanker Fleet Upgrade: Gas Turbine and Propulsion Control Systems Retrofit

Abstract

Many gas turbines commissioned in the late 1960’s and early 1970’s employ “first generation” electronic control systems. Usually a combination of analog-digital fuel and temperature control circuits and electromechanical relay sequencers, these systems (and the gas turbines they were designed to control) inevitably experience diminished performance as they age. This paper describes the project to design, construct, install, and commission replacements for the control systems on the main and auxiliary gas turbines and the propulsion controls for Chevron Shipping Company’s domestic tanker fleet. Since replacing the main gas turbine control system and propulsion controls on the oil tanker Chevron Colorado in the spring of 1993, both the main and auxiliary turbine and propulsion controls have been replaced on each of the other four (4) tankers. Triple modular redundant (TMR) digital systems were selected 10 replace the original analog-digital control systems on the main and auxiliary gas turbines (MGT & AGT). Required American Bureau of Shipping and US Coast Guard certification tests, as well as dock and sea trials for the new control systems are discussed. Economic results including maintenance repair action rates, start percentages, availabilities, and fuel savings are detailed.