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Research interests
Multiphase systems impact a wide variety of
industries including advanced materials (e.g. production of silicone for
semiconductors), environmental (e.g. aerobic and anaerobic wastewater
treatment), chemical (e.g. synthesis reactions and cracking of
hydrocarbons), mineral (e.g. reduction of iron oxide), energy (e.g.
combustion and gasification of coal), agricultural (e.g. drying and
roasting of foods), and pharmaceutical (e.g. production of plant and animal
cells). Because of their
commercial importance and complex flow patterns, the analysis and design of
multiphase reactors is one of the most intensely studied areas of chemical
engineering. Below is a
schematic of an industrial three-phase fluidized bed hydroprocessor used to
upgrade bitumen, from the Canadian oil sands, into crude oil.
Here is a short description of current research
projects:
·
Transport phenomena
in high pressure multiphase reactors
Most slurry bubble columns and three-phase
fluidized bed reactors of commercial interest operate under pressure, e.g. hydrocracking
of petroleum resids (5-21 MPa) and hydrocarbon synthesis via
Fischer-Tropsch reactions (1-5 MPa).
Pressure strongly influences bubble dynamics, which in turn affects
transport phenomena (phase holdups and mixing, mass and heat transfer) and ultimately
the reactor performance (conversion, yield, selectivity). Elevated
pressures usually lead to greater gas holdups and higher dispersed to
coalesced bubble flow regime transition velocities due to reductions in
bubble mean size and size distribution
The overall goal of this program is to
elucidate various transport phenomena occurring in high pressure multiphase
reactors, particularly three-phase fluidized beds. The pilot
plant has two columns of 0.1 m in inner diameter and 1.8 m in height
with several sight windows to allow for visualization. The gas and liquid superficial
velocities can be respectively varied up to 0.4 m/s and 0.1 m/s for
pressures up to 10 MPa. This
research program is done in collaboration with Syncrude Canada Ltd.
·
Synthesis of gas
hydrates in slurry bubble columns
Gas hydrates are non-stoechiometric
crystalline compounds that belong to the group known as Clathrates. Hydrates occur when water molecules
attach themselves through hydrogen bonding and form cages that can be
occupied by a gas molecule.
Naturally occurring hydrates, containing mostly methane, exist in
vast quantities within and below the permafrost zone and in sub-sea
sediments and are being looked upon as a future energy source. Work is also being conducted on
capturing CO2 by transforming it into hydrates. Another important benefit of gas
hydrates deals with the transportation and storage of natural gas. This is being considered as a
cost-effective alternative over current methods such as liquefied or
compressed natural gas since each volume of hydrate can contain as much as
184 volumes of gas at standard temperature and pressure.
The overall goal of this research program
is to develop a slurry bubble column reactor for producing gas
hydrates. This program bridges
research in thermodynamics with fluid dynamics and is done in collaboration
with Professor
Phillip Servio from McGill University. One of the two columns in the pilot
plant can be cooled to 273 K to allow of the formation of gas hydrates.
·
Multiphase flow in microchannels
Process intensification is quickly becoming
an important aspect in the production of fine chemicals and active
pharmaceutical ingredients. Continuous flow microreactors are an integral
part of process intensification as they overcome many of the heat transfer
and safety drawbacks of traditional batch and semi-batch stirred reactors.
The goal of this research program is to
investigate the impact of channel geometry on the transport phenomena in
single and multiphase microreactors over a range of production associated
to clinical trial phases I to III.
This research program is done in collaboration with Lonza Ltd and the CCRI.
·
CO2
capture systems for combustion and gasification flue gases
The connection between increasing
atmospheric CO2 concentrations and climate change is now
recognized by a number of international organizations including the United
Nations Framework Convention on Climate Change. In 2015,
power from fossil fuels were responsible for 66% of the world GHG emissions
(IEA).
The overall goal of this research program
is to develop power, steam or hydrogen via the thermal conversion of fossil
(and renewable) fuels along with a high-volume CO2 capture system
using either limestone-derived sorbents (i.e., calcium looping) or direct
oxy-fuel combustion, including the use of metal oxides (i.e., chemical
looping). Technology costs are
strongly connected to the behaviour of the sorbent in multiple cycles and
the main hurdles are overcoming the deactivation and loss of sorbent
through sintering and attrition.
This research program is done in collaboration with CanmetENERGY-Ottawa.
Research
Group
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