Deviations and errors review on measuring and calculating heavy fuel oil consumption and fuel stock onboard vessels equipped with volumetric fuel consumption flowmeters

Abstract

A common way of measuring heavy fuel oil consumption on board a vessel is to use volumetric fuel flow meters installed at fuel systems inlets for each of the major fuel consumers. At each stage of the fuel processing cycle, certain mass fuel losses or deviations and calculation errors occur that are not counted accurately into fuel consumption figures. The goal of this paper is to identify those fuel mass losses and measuring/calculating errors and perform their quantitative numerical analysis based on actual data. Fuel mass losses defined as deviations identified during the fuel preparation process are evaporation of volatile organic compounds, water drainage, fuel separation, and leakages while errors identified are flow meter accuracy and volumetric/mass flow conversion accuracy. By utilizing statistical analysis of obtained data from engine logbook extracts from three different ships numerical models were generated for each fuel mass loss point. Measuring errors and volumetric/mass conversion errors are numerically analyzed based on actual equipment and models used onboard example vessels. By computational analysis of the obtained models, approximate percentage losses and errors are presented as a fraction of fuel quantity on board or as a fraction of fuel consumed. Those losses and errors present between 0,001% and 5% of fuel stock or fuel consumption figures for each identified loss/error point. This paper presents a contribution for more accurate heavy fuel oil consumption calculation and consequently accurate declaration of remaining fuel stock onboard. It also presents a base for possible further research on the possible influence of fuel grade, fuel water content on the accuracy of consumption calculation.

Quantitative Analysis of Fuel Consumption and Fuel Sediments Separation as a Function of Fuel Type and Ship Operation Mode on Product/Chemical Tanker Example

“…0.099 during anchorage, 0.063 during navigation). Separated sludge figures present significant difference from the findings in Dujmović et al [9], where during steaming was identified 0.15% and 0.26% of separated components from consumed quantity of fuel. However, the percentage of 0.8% to 1.2% are in line with guidelines from International Maritime Organization [24].…”

“…However, some topics and areas in this research are covered in previous papers. The accuracy of fuel consumption calculation and separated fuel sediments quantity as a function of consumed fuel is presented in Dujmović et al [9]. Simulation and application of marine fuel oil purifier and sludge generation based on fuel flow through purifier bowl on Alfa Laval S series purifier is described by Ying et al [10].…”