Abstract
MSF (Multi-stage flash) desalination process faces two main challenges that madeindustrialists choose to RO (Reverse Osmosis) process over MSF: Corrosion and fouling; and
carbon emission. As it was seen from the literature, the scale formation occurring in the
condenser tubes could reduce the heat transfer rates by 80%, drastically affecting the total
performance and production ratios of the column. On the other hand, ever since the Paris
agreement, the restriction upon the total industrial carbon emission have been becoming
complicated annually. Even though, hydrate formation had the capacity in addressing both the
issues, challenges like stochasticity associated with hydrate nucleation and lower hydrate
formation kinetics discouraged the process from industrial application as an independent plant.
Hence, the current project proposed the usage of hydrate formation phenomenon to improve
the performance of Multi-stage flash (MSF). The study focussed on analysing the practicability
of HBD (Hydrate Based Desalination) -MSF hybrid and HBCC (Hydrate Based Carbon
Capture)-MSF hybrid as an industrial application.
Addressing the stochasticity of hydrate nucleation, the evaluation of stochasticity was studied
under various operational conditions by using the theoretical mathematical model proposed by
Kashchiev and Firoozabadi. In addition to this analysis, a theoretical induction time equation
was derived and validated based on the experimental analysis. The optimum pressure and
temperature conditions to conduct hydrate formation experiments for desalination applications
were derived based on this induction time analysis. Hydrate formation experiments in the
presence of saline water and impure guest gas were conducted under various influencing factors
such as kinetic additives and physical interventions. The study concluded that the energy
invested upon stirring was unnecessary as the initial hydrate formation was higher in case of
quiescent conditions.
Addressing the carbon capture through HBCC, tertiary amines were added to the mixture of
Tetrahydrofuran (THF) + Sodium dodecyl sulphate (SDS) + Distilled water, which was aimed
at separating CO2 from post-combustion gas capture mixture. A set of experiments were
conducted under various amines and their concentrations of amine along with various pressure
conditions. It was observed that the carbon selectivity was higher at operational pressures and
in the presence of TIPA. When evaluated the practicability of HBCC-MSF hybrid, from the
perspectives of both water usage and the carbon emission during hydrate formation, an
optimistic version of HBCC was observed to be effective to be used for carbon capture. Finally,
for the analysis of HBD-MSF practicability of industrial application, mathematical models
were created addressing MSF-OT (Once Through) and MSF-BR (Brine Recycle) in
SIMULINK. Even though, the introduction of HBD precursor to MSF was seemed to be
improving the performance of MSF, the overall practicability of MSF-HBD was observed to
be less due to the slower hydrate formation kinetics. Hence, it was concluded that the
combination of HBD-MSF for hybrid could be viable only when the higher input water
requirements of HBD are addressed.
| Date of Award | 28 Jul 2021 |
|---|---|
| Original language | English |
| Awarding Institution |
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| Supervisor | Sina Rezaei Gomari (Supervisor), Faizan Ahmad (Supervisor) & Meezanul Islam (Supervisor) |