Search Results (3)

This paper aims to identify the best solution for three SOx scrubber systems by evaluating their economic, environmental and technical performances: open-loop, closed-loop and hybrid scrubber systems. It adopted a novel muti-criteria decision-making model which can be introduced as the combination of lifecycle cost and lifecycle assessments, and fuzzy-TOPSIS and fuzzy-AHP. The analysis results of the case study of 72,100 gross-ton cargo ships suggested that the closed-loop scrubber systems would be the most effective in the consideration of all of the aspects, overall. It also shows the excellence of the proposed decision-making model to remedy the shortcomings of the conventional multi-criteria decision-making process by directing the analytic process in a wiser way, by means of fuzzy elements. For the environmental impact assessment, the lifecycle assessment approach enables one to obtain a holistic view of the Lifecycle emissions from the cradle to the grave. This paper finally shows the effectiveness of the proposed method, which can improve confidence in decision-making by extending a short-term view widely. Therefore, it was strongly believed that the proposed model is not necessarily/limitedly applied to marine systems but can be broad and noteworthy for a variety of studies requiring appropriate decision-making. Full article

Since 1 January 2020, the sulfur content allowed in exhaust gas plume generated by marine vessels decreased to 0.5% m/m. To be compliant, a hybrid scrubber was installed on-board, working in closed loop and generating a high volume of alkaline wastewater. The alkaline water suspension was treated by a silicon carbide multitubular membrane to remove pollutants, and to allow the water discharge into the natural environment. In this paper, membrane filtration behavior was analyzed for the maritime scrubber wastewater. A range of operating parameters were obtained for several feedwater quality-respecting industrial constraints. The objective was an improvement of (I) the water recovery rate, (II) the filtration duration, and (III) the permeate quality. Thus, in high-fouling water, a low permeate flow (60 L h⁻¹ m⁻²) with frequent backflushing (every 20 min) was used to maintain membrane performance over time. In terms of water quality, the suspended solids and heavy metals were retained at more than 99% and 90%, respectively. Other seawater discharge criteria in terms of suspended solids concentration, pH, and polyaromatic hydrocarbons were validated. The recommended operating conditions from laboratory study at semi-industrial scale were then implemented on a vessel in real navigation conditions with results in agreement with expectations. Full article

In the present work, the contemporary exhaust gas treatment systems (EGTS) used for SO_x, PM, and NO_x emission mitigation from shipping are reviewed. Specifically, after-treatment technologies such as wet scrubbers with seawater and freshwater solution with NaOH, hybrid wet scrubbers, wet scrubbers integrated in exhaust gas recirculation (EGR) installations, dry scrubbers, inert gas wet scrubbers and selective catalytic reduction (SCR) systems are analyzed. The operational principles and the construction specifications, the performance characteristics and the investment and operation of the reviewed shipping EGTS are thoroughly elaborated. The SCR technology is comparatively evaluated with alternative techniques such as LNG, internal engine modifications (IEM), direct water injection (DWI) and humid air motor (HAM) to assess the individual NO_x emission reduction potential of each technology. Detailed real data for the time several cargo vessels spent in shipyards for seawater scrubber installation, and actual data for the purchase cost and the installation cost of seawater scrubbers in shipyards are demonstrated. From the examination of the constructional, operational, environmental and economic parameters of the examined EGTS, it can be concluded that the most effective SO_x emission abatement system is the closed-loop wet scrubbers with NaOH solution which can practically eliminate ship SO_x emissions, whereas the most effective NO_x emission mitigation system is the SCR which cannot only offer compliance of a vessel with the IMO Tier III limits but can also practically eliminate ship NO_x emissions. Full article