CO2 Removal Using Adsorption Onboard A Floating Production Storage and Offloading (FPSO) Vessel
9 Pages Posted: 5 Apr 2021
Date Written: February 14, 2021
Offshore operations gas purification has always been limited to the marketable associated value of the gas where purification would either be onsite or sent to surface facilities for treatment. CO2 and H2S removal and gas sweetening in remote offshore locations is for the most part non-existent and CO2 is either being released into the atmosphere, within the acceptable operation limit of the platform, or being captured using conventional techniques with physical solvents such as in the selexol, rectisol, or sulfinol processes. Approximately 429.61 kg of CO2 exists in a 42-gallon barrel of distillate fuel oil and a CO2 coefficient of 0.0549 kg exists in 1 cubic foot of gas thereby emphasizing the need for an engineering solution on floating production storage and offloading (FPSO) units . With strict regulation on greenhouse gases, it is increasingly paramount to utilize engineering measures to provide a contingency plan in mitigating carbon footprint with emerging novel technologies.
The purpose of this study is to retrofit an existing FPSO with a CO2 capture plant; the efficiency of the capture plant, its capture capacity, and energy requirement based on experimental data will be thoroughly investigated during the scale up procedure.
The research proceedings will require the use of a plethora of simulation suites which include Autodesk Fusion 360 for plant design. Further simulation will be carried out with numerical suites using Mathcad Prime 3.0 to study the scale up procedure from experimental to industrial sized adsorption unit complete with dimensions, energy requirement, capture capacity, and thermal values.
The FPSO in figure 1 above presented by (Araujo et al., 2016) indicates the availability of a capture plant as part of the process train on an FPSO. Efficiency loss contribution to the system may be deduced but also it is relevant to note the custom nature of the FPSO design being independent in its operation mode compared to other profiles. The availability of the stage compressors, dehydration units, and steam generation plant as part of the FPSO operation aid in minimising the need for additional equipment for the adsorption plant, however investigation has to be made on the redirecting of processes to serve the additional components highlighted above.
Primary results have shown a low tendency for dual adsorption from the initial kinetic stoichiometric balance which could also be due to the force field parameters and charges affecting the active sites. For the current concept the fixed bed experimental model from the Research and Innovation Centre on CO2 and H2 is scaled up numerically to a fixed bed height of 6.56 feet, and filled with precipitated silica impregnated with PEI solution pressurized with CO2 inflow rated at 13 lb/hr at a fixed 1.2 Bar 60°C.
The operational nature of the FPSO will be modified to account for the changes requested in gas sweetening and capture programs or enhanced oil recovery. Results from the simulation will also assist in providing a tangible and relatable understanding to the complexity of solid sorption technology integration within existing processing plants. The findings of this study will help comprehend the viability of an integrated adsorption plant within an existing process train. The efficiency of the plant operation for an oil production offshore facility with associated gas or for a standalone gas field will be addressed using a feasibility study conducted for the purpose of sustainable offshore operations.
Keywords: FPSO, Adsorption, carbon capture, natural gas sweetening, process simulation, thermal analysis, sustainable operation
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