Volatile organic compound emission from marine oil loading operations

Abstract

Marine oil loading operations release enormous volumes of oil vapours into the atmosphere. Releasing oil vapours causes direct economic loss and localised environmental pollution. Prolonged exposure to Volatile Organic Compounds (VOCs) can cause acute and chronic effects on human health. The adverse health effects of toxic VOCs from oil vapour emission (OVE) have been widely discussed in the literature. The current marine oil tanker design does not require equipment to be part of the standard design to stop this evaporative emission. Current procedures to load oil tankers affect the health of seafarers onboard and pollute the local environment, as tanker loading ports handle many ships simultaneously every day. This thesis aims to address the monetary loss, environmental pollution, and health risks to seafarers due to OVE during marine oil tanker loading operations and to make the loading operations sustainable and carbon neutral. There are no regulations in International Maritime Organization (IMO) conventions and coastal states to address this economic loss and environmental pollution. The research analysis is conducted for a crude oil and gasoline loading operation using Aspen HYSYS Chemical Process Simulator. Crude oil loading operation is analysed for an Aframax tanker and an Ultra Large Crude Carrier (ULCC), whereas gasoline loading is simulated in a product tanker. Results reveal an annual monetary loss of $1.2 to 5.5 million for an Aframax tanker loading crude oil between the temperature range of 25℃ to 45℃, whereas for a ULCC, the annual monetary loss was found in the range of $1.6 to 11.2 million for the same temperature range. OVE increases with an increase in oil temperature and decreases when higher cargo tank pressure is maintained during tanker loading operations. Hence, OVE can be reduced by adopting a working practice of maintaining elevated tank pressure of 120 kPa instead of the current practice of 108 kPa. Furthermore, the hydrocarbon (HC) emission was found to reduce by 4% to 10% for both crude oil and gasoline loading operations of 25℃ to 45℃ and cargo tank pressure of 120 kPa. The results also indicate that VOC emission is lower for a tanker with a higher loading rate (ULCC) during crude oil loading operations. Toxic VOCs, the current research identifies, include hexane, benzene, toluene, ethyl benzene, and xylene. Solutions are proposed to safeguard the health of seafarers due to toxic VOC exposure and reduce or stop the monetary loss and environmental pollution. This includes the amendments to the current regulations in SOLAS and MARPOL conventions such as the mandatory provision of vapour return line during oil tanker loading operations and conducting VOC Toxicity Hazard Assessment (VOCTHA) during ship design for oil tanker loading and ship bunkering operations.