The following papers have been written by academia and make use
of AspenTech software.
- Integration Of
Biomass Gasification With Pem Fuel Cell -
First International Symposium On Process Intensification and
Miniaturisation
H. Olgun, A. Ersoz, S. Ozdogan, M. Tiris, F. Akgun
In this paper, we discuss the results of a simulation study for
a biomass gasifier integrated with a PEM fuel cell. The system
study comprises reforming and cleanup units as well. The HYSYS 3.1
- ASPEN code has been used for simulation. The biomass source is
hazelnut shells. It is desired to investigate both the overall
system efficiency and the net electrical efficiency.
Fuel properties, gasification and reforming operation parameters
affect the overall system efficiency. The net electrical efficiency
is determined by the fuel conversion system efficiencies and fuel
cell efficiency as well as on the heat integration within the whole
system.
Currently, hazelnut shells are combusted in smallscale ovens for
residential purposes being far away from sustainability. Results
indicate that integration of gasification with PEM fuel cell
presents a sustainable way of power generation.
ISBN 0-9545956-0-2
- Simulation Study Of A Pem Fuel Cell System
-
The First International Exergy, Energy And Environment
Symposium
H. OLGUN, A. ERSO, D. KAYA, M. TIRIS, F. AKGUN, S.
OZDOGAN
This paper summarizes the results of a study for a 100 kWe DC
electrical power PEM fuel cell system. The system consists of a
pre-steam reformer, a steam reformer, high and low temperature
shift reactors, a preferential oxidation reactor, a PEM fuel cell,
a combustor and an expander. Acceptable net electrical efficiency
levels can be achieved via intensive heat integration within the
PEM fuel cell system. The calculations take into account the
auxiliary equipment such as pumps, compressors, heaters, coolers,
heat exchangers and pipes. The process simulation package
''Aspen-HYSYS 3.1'' has been used. The operation parameters of the
reactors have been determined considering all the technical
limitations involved. A gasoline type hydrocarbon fuel has been
studied as hydrogen rich gas source. Thermal efficiencies have been
calculated for all of the major system components for selected
operation conditions. The fuel cell stack efficiency has been
calculated as a function of cell numbers (500, 750, 1000 and 1250
cells). Efficiencies of all of the major system components along
with auxiliary unit efficiencies determine the net electrical
efficiency of the PEM fuel cell system. The obtained net electrical
efficiency levels are between 34 (500 cells) to 41% (1250
cells).
- SIMULATION STUDY
OF A PEM FUEL CELL SYSTEM WITH AUTOTHERMAL REFORMING -
16th International Conference On Efficiency, Costs, Optimization,
Simulation And Environmental Impact Of Energy
Systems
Ozdogan, Sibel; Ersoz, Atilla; Olgun, Hayati; Gungor,
Cengiz; Akgun, Fehmi; Tyrys, MustafaThis paper presents the results of a study for a 100 kW net
electrical power PEM fuel cell system. The major system components
are an autothermal reformer, high and low temperature shift
reactors, a preferential oxidation reactor, a PEM fuel cell, a
combustor and an expander. Intensive heat integration within the
PEM fuel cell system has been necessary to achieve acceptable net
electrical efficiency levels. The calculations comprise the
auxiliary equipment such as pumps, compressors, heaters, coolers,
heat exchangers and pipes. The process simulation package
''Aspen-HYSYS'' has been used along with conventional calculations.
The operation conditions of the autothermal reformer have been
studied in detail to determine the values, which lead to the
production of a hydrogen rich gas mixture with CO concentration at
ppm level. The operation parameters of the other reactors have been
determined considering the limitations implied by the catalysts
involved. A gasoline type hydrocarbon fuel has been studied as the
source for hydrogen production. The chemical composition of the
hydrocarbon fuel affects the optimum operation conditions of
autothermal reforming and the following fuel purification steps.
Thermal efficiencies have been calculated for all of the major
system components for selected operation conditions. The fuel cell
stack efficiency has been calculated as a function of number of
cells (500 to 1250 cells). Efficiencies of all of the major system
components along with auxiliary unit efficiencies determine the net
electrical efficiency of the PEM fuel cell system. The obtained net
electrical efficiency levels are between 30 (500 cells) to 37%
(1250 cells). Hence, they are comparable with or higher than those
of the conventional gasoline based engine systems. Keywords:
Autothermal reforming, hydrocarbon fuel, PEM fuel cell.
- Experiences in Process
Control Web-based Learning -
ASEE Annual Conference 2003
Chernik, P., Lambden, J., Svrcek, W.Y. and Young,
B.R.
As more and more students gain access to computers, the idea of
implementing Internet-based chemical engineering courses becomes
more of a reality. With web-based learning comes new opportunities
and challenges for both faculty and students. In courses where
hands-on learning directly facilitated by an instructor is not
required, web-based classes offer students the flexibility to
complete coursework while still maintaining full-time employment,
or when schedule conflicts between classes occur. The independent
learning style challenges students to gain a greater understanding
of the course material, as interactions between classmates can be
limited. A student gains the ability to complete the course at
their own pace, which allows the student to blend the needs of the
web-based course with other courses or activities.
The key to web-based learning is communication. The ease of
communication between the professors and the students, the ability
of students to communicate with each other and the ability of the
students to easily find and access the information they require are
all vital to a successful web-based learning experience. Successful
communication in a web-based course is dependent on the web site
interface chosen and on the willingness of both the professors and
students to utilize the tools of the web site.
This paper explores these issues from the perspectives of two
students who have completed the University of Calgary .Process
Dynamics and Control. course via the Internet, and the instructors
involved with the course. By investigating the benefits and
challenges to web-based learning and offering possible solutions to
these challenges, it is shown that web-based learning can become an
integral part of any Chemical Engineering program.
Navigate to the 2003 conference proceedings to obtain the
publication.
- Advanced
Control of a Refinery Naphtha Train -
IEEE Industry Applications Society Advanced Process Control
Applications for Industry Workshop
Williamson, C.J. and Young, B.R.
The paper describes dynamic simulation studies on a section of
the New Zealand Oil Refining Company's oil refinery in Whangarei,
New Zealand. A sequence of two distillation columns with heat
integration is used for the stabilisation of a refinery naphtha
stream. Naphtha, distilled from crude oil, is fed to a distillation
column designed to remove light components (C1-C4) from the feed.
The topped stream feeds a second column that separates C5 and C6
compounds from the heavier components. The vapour product stream
from the top of the second column preheats the feed to the first.
The naphtha feed stream varies in composition, especially in the
quantity of the lighter components. The feed composition variation
has caused instability in the operation of the distillation columns
with their present control scheme. Using a series of dynamic
simulation studies (carried out using the HYSYS simulation package)
the reason for the unstable operation was detected. Alternative
control schemes, including Model Predictive Control, were simulated
to choose a scheme that provided best control for operation of the
process.
-
Dynamic Modelling of an Acid Gas Flood Facility for Assuring Safety
during Non-routine Operations -
AIChE Spring National Meeting, New Orleans LA
Young, B.R., Burton, D.J. and Svrcek, W.Y.
Acid gas injection is a method of disposal of sour natural gas
into a producing or depleted hydrocarbon reservoir that may offer
benefits from both an environmental and economic standpoint. It is
both one way to dispose of acid gas so that it is not released to
the atmosphere and can also provide enhanced recovery from a
producing hydrocarbon reservoir.
In 2002 Dominion Energy Canada Ltd commissioned an acid gas
flood for its West Stoddart field near Ft. St. John, B.C., Canada.
In this flood, 2.5 MMSCFD of acid gas that is a 75% H2S and 25% CO2
mixture is injected into a producing reservoir. The acid gas
mixture is delivered from a multistage compressor to a 1.4-mile
long pipeline for transportation to the wellhead. Facilities at the
wellhead site include a line heater and flare system.
This paper describes the use of dynamic simulation to model the
start-up, turn down and blow-down of these acid gas flood
facilities. The model was developed to help assure the safety of
the design and operating procedures to handle the acid gas during
these non-routine operations. In the presentation, experiences from
the start-up and operation of the facility will also be
detailed.
-
Model Predictive Control of a Heat-Integrated Plant, A Case Study
on the Reaction Section of the HDA Process -
AIChE Spring National Meeting, New Orleans LA
Tellez, R., Young, B.R. and Castillo, F.J.L.
Heat integrated plants involving exothermic chemical reactions
always show a degree of positive feedback and instability when
trying to control the outlet temperatures of process-to-process,
feed-effluent heat exchangers. This is the case for the well-known
hydrodealkylation (HDA) of toluene process (Douglas, 1988) in which
this kind of situation adds complexity to all intended control
systems. In recent years, process control engineers have widely and
successfully applied Model Predictive Control (MPC) for the
management of difficult multiple-input-multiple-output process with
significant interactions between the manipulated variables (MV's),
the disturbance variables (DV's) and the controlled variables
(CV's).
A 2 by 2 MPC controller was implemented on a dynamic simulation
of the HDA Plant in this study. The control system was formulated
according to the Dynamic Matrix Control (DMC) (Cultler and Ramaker,
1979) configuration. The controller was designed to control the
temperatures for both the reactor feed and the outlet stream
reactor effluent condenser (CV's). The plant feed flow rates were
selected as the DV's and the heat duties were selected as the MV's.
System identification using open-loop tests with the DV's was
employed in order to build process models. A pairing analysis was
also carried out.
Good performance from the MPC controller was obtained,
maintaining the process variables within a reasonable range.
Moreover, the MPC controller showed good responses to several set
point changes. Comparison of the MPC controller performance against
IMC-PID and simple classical tuning rules, such as Ziegler-Nichols,
was carried out.
- Strategies
for the Operation and Control of Heat Exchanger Networks
-
FOCAPO 2003, Foundations of Computer-Aided Process
Operations
Westphalen, D.L., Young, B.R., Svrcek, W.Y. and M.
Broussard
Click on the link above to learn how to obtain this
publication.
- Controllability
of Heat Exchanger Networks -
52nd Canadian Chemical Engineering Conference
Westphalen, D.L., Young, B.R., Svrcek, W.Y. and Shetha,
H.
A new degrees of freedom methodology for the controllability
analysis of heat exchanger networks was developed. In the procedure
described in this paper, the number of degrees of freedom is
calculated as the number of manipulated variables, minus the number
of controlled variables, minus teh number of constraints. In a heat
exchanger network, the number of manipulated variables is equal to
the number of heat exchangers, the number of controlled variables
is equal to the numver of targeted streams and the number of
constraints is equal to the number of independent loops. A loop
represents a redundant number of units transferring heat between
streams and therefore represents a constraint for process control
in that it removes a degree of freedom. Furthermore, sub-networks
also play an important role in the controllability of a network,
and the degrees of freedom analysis must be carried out for all
independent sub-networks. Examples will be presented that show
overall networks with a positive number of degrees of freedom
containing a sub-network with a negative number of degrees of
freedom, resulting in the sub-network and therefore the overall
network being uncontrollable. New algorithms for the identification
of loops and sub-networks were also developed and implemented in a
computer program, thus providing for the rapid analysis of large
complex networks of heat exchangers. A degrees of freedom analysis
for controllability analysis is now a feasible additional step that
should be performed during the synthesis and optimization of
networks. The process engineer now has the capability to discard
all non-controllable structures prior to the design of the
network.
- A
Process Design and Control Strategy for DiMethyl Ether Production
from a Methanol Feedstock -
2002 American Control Conference
van der Lee, J.H., Young, B.R. & Svrcek, W.Y.
With ever tightening vehicular emission regulations, alternative
fuels to diesel are being developed. One such alternative is
Dimethyl Ether (DME) which has a performance similar to diesel
while at the same time meeting or exceeding the current emission
regulations. A plant wide control strategy for a DME plant is
presented. The dynamic response of the plant to expected
disturbances using a conventional multiloop PID control scheme
provided adequate control. However, set point tracking of the water
methanol column bottoms product composition controller was
inadequate, resulting in considerable interaction between the
column temperature and composition control loops. The
implementation of a Model Predictive controller (MPC) on the column
improved set point tracking but resulted in poorer disturbance
rejection.
- The Use of
Dynamic Simulation in the Design and Testing of a Model Predictive
Control Scheme -
IEEE Industry Applications Society 2002 Advanced Process Control
Applications for Industry Workshop
Young, B.R.
Process control engineers have used dynamic simulation for many
years to analyse and design process control strategies. Even as
recently as the last decade, only an engineer who is an expert in
process modelling, simulation and control typically even attempted
this work on large, industrially relevant applications as the
development of a dynamic simulation model required considerable
effort. The computing power that was also required for a useful and
fast simulation was also such that such projects required many
months to build the dynamic models and test them - even for a
single unit operation (e.g. a single distillation column). State of
the art simulation technology as well as current computer hardware
and software have changed the level of expertise required to build
dynamic models and to build dynamic simulations. With the new
technology dynamic models of entire "virtual" plants (e.g. a small
refinery) can be built and tested in a matter of days. This order
of magnitude improvement in the computing and simulation technology
has enabled the process control engineer to develop better process
understanding and to contemplate the application of advanced
control applications such as Model Predictive Control at the plant
design stage. In this tutorial I will describe the use of dynamic
simulation in the design and testing of a Model Predictive Control
scheme for a simple chemical process.
- A Study
in Advanced Control Application to an Azeotropic Distillation
Column within a Vinyl Acetate Monomer Process Desig -
Developments in Chemical Engineering and Mineral Processing
Olsen, D.G., Young, B.R. and Svrcek, W.Y.
Click on the link above to learn how to obtain this
publication.
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