Development, Atmospheric Testing and Field Operation of a Fuel Flexible Gas Turbine Combustion System for Crude Oil Volatile Organic Compounds

Abstract

Volatile Organic Compounds (VOCs) evaporate from crude oil due to their volatile characteristics. These VOCs are conventionally vented, thereby contributing significantly to the harmful emission in the crude oil loading, storage and transport on offshore platforms, ships, storage tanks, terminals and shuttle tankers. The VOCs can be captured by a VOC recovery system, thereby reducing the harmful emissions significantly. The heavier fractions (mainly C3+) out of VOCs can be stored as liquid VOC (LVOC). The non-condensable fraction is a surplus gas (SVOC) mainly consisting out of lighter hydrocarbons and inert gases. The composition of LVOC and SVOC significantly varies depending on the type of crude oil. The application of both LVOC is challenging due to the high volatility, high dew point and varying compositions, while the SVOC is challenging because of the high variation in inert gas concentration, which depends on the crude oil level in the cargo tank. This paper will present the development and testing of a new tubular combustion system that can operate on the LVOC and SVOC from a VOC recovery unit as well as on LNG in case the VOC recovery plant is not operational. The challenges of the high variety in fuels are mainly translated in a dedicated fuel nozzle for the low calorific fuel combustor. This novel nozzle allows for stable operation on a wide variety of fuels with limited supply pressure requirements. The combustor has been tested in OPRA’s state-of-the-art atmospheric combustor test rig. Hereby various fuels have been supplied. The results presented in this paper focus on the validation of flame stability, operational window, turn down and emissions operating on different mixtures of low calorific gas (SVOC) and high calorific gas (LVOC, propane and natural gas). After successful completion of the atmospheric testing, a full-scale engine test has been performed with the OP16 gas turbine in OPRA’s engine test cell. Multiple gensets are installed on shuttle tankers and have been successfully commissioned with the various fuels. Operational experience from these sea trials are discussed. It has been proven that the OPRA OP16 gas turbine can utilize 100% of the VOC emissions recovered from the shuttle tanker, whereby power is supplied to the vessel. This results in a significant reduction of the ship’s emissions.