Solidification and storage of carbon captured on ships (CCS)

Student thesis: Doctoral Thesis

Abstract

In order to meet the IMO's (International Maritime Organisation) target of 14% reduction of CO₂ emissions from marine activities by 2020, the application of Carbon Capture and Storage (CCS) on ships is considered as an effective way to mitigate the CO₂ emission while other low carbon shipping emission technologies are being developed. A comprehensive literature review of onshore CCS applications has indicated that current CCS technologies could not be implemented on-board directly due to the various limitations of ships, such as constraint space and system retrofit. In this thesis, a novel method of chemical CO₂ absorption and solidification for marine applications is analysed and presented. Technical feasibility and cost assessment of this method are carried out by comparison with the conventional method (liquefaction) for a case study ship. The thesis will also present results obtained from laboratory-scale experiments. Theoretical study and lab-scale experiments have shown that the proposed CO₂ absorption and solidification method is a promising, cost-effective and practicable method for CO₂ emissions reduction on ships. Carbon capture and storage is an excellent solution for reducing the greenhouse gas emissions from applications on shore. A novel method to absorb and solidify CO₂ from the exhaust gases on the ship is proposed and verified. CO₂ gas flow rate, the geometry of the absorption tanks and the concentration of the absorption solution are key factors that affect the reaction efficiency. The experimental results illustrate the impacts of these factors on CO₂ absorption efficiency. Meanwhile, the effects of these key factors on CO₂ absorption rates will also be presented in the CFD simulations of this thesis. Pressure distributions, the concentration of the solution and the velocity of both the gas and the solution during the different processes will be derived from the numerical simulations. The results of the simulations provide fundamental details for the design of a prototype demonstration system on-board a ship. In addition to the key factors discussed above, the effect of atmospheric temperature will be observed and analysed. With a comparison of experimental data and CFD simulation results, it will be demonstrated that the CFD simulations of the effects of CO₂ gas flow rate, the geometry of the absorption container and the concentration of the absorption solution on absorption rate have a good agreement with the experimental results. Optimised values of these factors are obtained from the comparisons and analyses. The numerical simulations will [sic] carried out to test the impact of phase temperature on absorption rate also indicate the optimal temperature for carrying out the absorption process.;As the simulation results match with the experimental results, the simulation model developed is considered to be applicable for a case study ship practical system simulation. Geometry, fluid flow rate, temperature and some other parameters are adjusted to fit a practical system. At this stage, the practical system is designed and the most appropriate absorption process is selected. The designated system is modelled and simulated based on the simulation processes from the lab-scale experiments. The orthogonal design method is applied to optimise the system. Key parameters are varied within a reasonable range so that a large number of trials are initially needed to find the optimal one. With the orthogonal design method, the number of trials is reduced so that computing intensity is reduced and finally the optimised absorption system is derived. The volume required for the precipitation tanks, CaO and CaCO₃ storage tanks and the centrifuge separation are derived and the installation and positioning of these tanks, as well as the positioning of the whole system, will be presented. It is concluded that CCS for marine activities could enable ships to comply with various regional and international CO₂ emissions regulation whilst also maintaining the efficiency of waterborne transportation. The whole design process for the case study ship is presented here and could be applied as a guideline process for new design, analysis and installation.
Date of Award23 Jan 2017
Original languageEnglish
Awarding Institution
  • University Of Strathclyde
SponsorsUniversity of Strathclyde

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