10 research outputs found
Potential for Significant Energy-Saving via Hybrid Extraction–Distillation System: Design and Control of Separation Process for <i>n</i>‑Propanol Dehydration
The
hybrid extraction–distillation separation system is
a process combining liquid–liquid extraction and also distillation.
This hybrid system can be viewed as a derivative of the heterogeneous
azeotropic distillation method. In this work, the potential for significant
energy-saving via this hybrid process is demonstrated with both conceptual
illustration and a case study of <i>n</i>-propanol dehydration.
Diisopropyl ether (DIPE) is selected as the extraction solvent considering
its favorable properties of density, heat of vaporization, and lower
toxicity. Since the solvent flow rate is the most important design
degree-of-freedom in this process that influences overall energy consumption,
an iterative optimization procedure is conducted to minimize total
annual cost. Furthermore, a novel control strategy is proposed on
the basis of closed-loop and open-loop sensitivity tests. Here, an
adjustable solvent flow rate during dynamic control allows steady-state
operation at the optimal condition. Dynamic simulation results show
that both <i>n</i>-propanol and water products can still
be maintained at high purities despite large variations in feed flow
rate and feed composition disturbances
Design and Economic Evaluation of a Coal-Based Polygeneration Process To Coproduce Synthetic Natural Gas and Ammonia
The
steady-state design and economic evaluation of a polygeneration
(POLYGEN) process to coproduce synthetic natural gas (SNG) and ammonia
are studied in this work. POLYGEN has been a widely studied topic
recently, in which several products could be produced parallel at
the same time. One of the two products in this study, SNG, has a composition
and heat value very similar to those of typical natural gas, and can
be used as a replacement in industrial and home usages. Another product,
ammonia, is one of the most important inorganic chemicals in the world,
and could be used as the precursor of various kinds of chemicals,
as fertilizers, or as a cleaning agent. In the POLYGEN process, the
relative production rates for different chemicals could be adjusted
on the basis of different market demands, daily usages, and also changing
political strategies. In our previous study (Yu, B. Y.; Chien, I.
L. Design and Economical Evaluation of a Coal-to-Synthetic Natural
Gas Process. <i>Ind. Eng. Chem. Res.</i> <b>2015</b>, <i>54</i>, 2339–2352), we illustrated that the
SNG production price is lower than the liquefied natural gas importation
price in Taiwan. The SNG production price is 10.837 USD/GJ (USD =
U.S. dollars) in an SNG-only plant. With the POLYGEN process to coproduce
SNG and ammonia, the SNG production cost could become even lower.
If 20% of the syngas is used to produce ammonia, the SNG production
price will drop to 9.365 USD/GJ, and if 40% is used for ammonia production,
the SNG production price will drop further to 7.063 USD/GJ. Thus,
although the POLYGEN process leads to an increasing total capital
investment, it has positive influences from economic aspects. Besides,
the flexibility of shifting the production rate of SNG or ammonia
makes it possible to adapt to changes in the market demand
Design and Economic Evaluation of a Coal-to-Synthetic Natural Gas Process
The steady state design and economic
evaluation for coal to synthetic
natural gas (SNG) process is rigorously studied, and this study could
give a baseline for design and analysis for SNG production in Taiwan
or other countries relying on importation of an energy source. SNG
is a product that holds very similar composition and heat value to
typical natural gas, and can be used as a replacement in industrial
and home usages. Natural gas is an important energy source in Taiwan,
with increasing demand year by year. Because over 99% of our energy
sources is imported in Taiwan, and because of the advantages of coal
over natural gas (lower importation price, great abundance, easier
transportation and storage, etc.), the process that converts coal
into SNG is expected to benefit Taiwan if the related technology is
successfully established. The whole process is divided into several
parts, including air separation unit (ASU), gasification, the syngas
treating section (water gas-shift reaction, syngas cooling, and acid
gas removal), methanation reaction section, and electricity production
block from upstream to downstream. The overall energy conversion efficiency
for the plant is 60.38%, with the SNG production cost to be 10.837
(USD/GJ), thus this process will be economically and practically attractive
Potential for Significant Energy-Saving via Hybrid Extraction–Distillation System: Design and Control of Separation Process for <i>n</i>‑Propanol Dehydration
The
hybrid extraction–distillation separation system is
a process combining liquid–liquid extraction and also distillation.
This hybrid system can be viewed as a derivative of the heterogeneous
azeotropic distillation method. In this work, the potential for significant
energy-saving via this hybrid process is demonstrated with both conceptual
illustration and a case study of <i>n</i>-propanol dehydration.
Diisopropyl ether (DIPE) is selected as the extraction solvent considering
its favorable properties of density, heat of vaporization, and lower
toxicity. Since the solvent flow rate is the most important design
degree-of-freedom in this process that influences overall energy consumption,
an iterative optimization procedure is conducted to minimize total
annual cost. Furthermore, a novel control strategy is proposed on
the basis of closed-loop and open-loop sensitivity tests. Here, an
adjustable solvent flow rate during dynamic control allows steady-state
operation at the optimal condition. Dynamic simulation results show
that both <i>n</i>-propanol and water products can still
be maintained at high purities despite large variations in feed flow
rate and feed composition disturbances
Assessment on CO<sub>2</sub> Utilization through Rigorous Simulation: Converting CO<sub>2</sub> to Dimethyl Carbonate
This
paper intends to discuss the economical performances and CO<sub>2</sub> reduction potential of two CO<sub>2</sub>-based dimethyl
carbonate (DMC) production processes through rigorous process simulation.
One of them is the direct production process with addition of butylene
oxide (BO) as dehydrating agent (DIR-BO porocess), while the other
is the indirect production process through ethylene carbonate (EC)
as an intermediate (IND-EC process). Both processes are systematically
optimized and heat-integrated. From economical evaluation, the IND-EC
process exhibits economical attractiveness, while the DIR-BO process
does not. We suggest that once the reaction rate of the DIR-BO process
can be improved, the overall economic performance of the direct process
can be much better. From the aspect of CO<sub>2</sub> reduction, the
net CO<sub>2</sub> emissions throughout both processes are calculated.
We found that DIR-EO process is largely carbon positive, with CO<sub>2</sub> emission of 2.242 (kg CO<sub>2</sub>/kg DMC), yet for the
IND-EC process, it is near carbon neutral, with CO<sub>2</sub> emission
of 0.049 (kg CO<sub>2</sub>/kg DMC). Thus, from the aspect of achieving
CO<sub>2</sub> reduction, converting it into DMC provides limited
benefits
Fuzzy-Logic-Based Supervisor of Insulin Bolus Delivery for Patients with Type 1 Diabetes Mellitus
In this article, a fuzzy-logic-based supervisor of insulin
bolus
delivery for type 1 diabetes mellitus (T1DM) is proposed. The proposed
supervisor incorporates expert knowledge into three phases, including
recall, inference, and learning phases. A recently developed and well-acknowledged
meal simulation model of the glucose–insulin system for T1DM
was employed to create virtual subjects for testing. Data from virtual
subjects were used to identify an intermediate physiological model,
and then our proposed supervisor was synthesized based on this intermediate
model. The key features of this fuzzy-logic-based supervisor are that
the implementation does not need an online model and it can gradually
be updated meal-by-meal. In addition, only two blood glucose measurements
between each meal are needed for updating the insulin bolus delivery.
The simulation results show that effective and robust glycemic control
performance can be achieved. This methodology can be widely applied
to patients with continuous subcutaneous insulin infusion (CSII) or
multiple daily injections (MDI)
Critical Assessment of Using an Ionic Liquid as Entrainer via Extractive Distillation
Ionic
liquids (ILs) have received much attention in the last two
decades. One of the important applications is to use this relatively
new class of compounds for the separation of azeotropic mixtures via
extractive distillation. In this paper, overall extractive distillation
processes of two azeotropic separation systems using a favorable ionic
liquid as entrainer are rigorously developed. The optimized design
flowsheets are compared with the conventional processes using an industrial
entrainer. The two ionic liquid extractive distillation systems include
separating acetone and methanol using 1,3-dimethylimidazolium dimethylphosphate
([MMIM]Â[DMP]) as entrainer and another system of separating isopropyl
alcohol and water using 1-ethyl-3-methylimidazolium acetate ([EMIM]Â[OAC])
as entrainer. The potential drawbacks of using an ionic liquid in
the extractive distillation systems are given in the paper. It is
found that the degradation temperature and high normal boiling point
temperature of the ionic liquids in these two systems require the
IL processes to use high vacuum operating conditions, thus making
them only economically comparable to the conventional processes
Energy-Saving Optimal Design and Effective Control of Heat Integration-Extractive Dividing Wall Column for Separating Heterogeneous Mixture Methanol/Toluene/Water with Multiazeotropes
To the best of our knowledge, very
few efforts have been investigated
for separating heterogeneous mixtures methanol/toluene/water with
multiazeotropes using extractive dividing-wall column (EDWC). In this
work, we propose a systematic approach for the energy-efficient EDWC
to achieve less capital cost and operating cost in separating heterogeneous
multiazeotropes mixtures, which involves thermodynamic feasible insights
via residue curve maps to find separation constraints, global optimization
based on a proposed CPOM model, and a dynamic control through Aspen
Dynamics simulator to better maintain product purities. An energy-saving
EDWC with heat integration (HI-EDWC) flowsheet is then proposed to
achieve the minimum total annualized cost (TAC). The computational
results show that the TAC of the proposed HI-EDWC is significantly
reduced by 15.14% compared with the optimal double-column extractive
distillation with an additional decanter. Furthermore, an effective
control strategy CS3 with a fixed reboiler duty-to-feed ratio and
temperature/(S/F) cascade is proposed to better handle the methanol,
toluene, and water product purities than basic control structures
CS1 and CS2 while feed flow rate and composition disturbances are
introduced in the proposed HI-EDWC process
Energy-Efficient Extraction–Distillation Process for Separating Diluted Acetonitrile–Water Mixture: Rigorous Design with Experimental Verification from Ternary Liquid–Liquid Equilibrium Data
In
this paper, an energy-efficient extraction–distillation
process to separate diluted azeotropic acetonitrile–water mixtures
is newly developed. Compared with the conventional azeotropic separation
methods (i.e., extractive distillation), the potential dominant benefit
of this proposed method is that the main separation task can be achieved
by an extraction column without needing reboiler duty. In this work,
an efficient solvent of <i>n</i>-propyl chloride is proposed
to extract the organic compound into the extract phase and to let
water remain in the raffinate phase. Ternary liquid–liquid
equilibrium experiments are also conducted to verify the separation
performance in the extraction column and decanter of the proposed
process. It is found that significant savings of 40.3% in steam cost
and 34.7% in total annual cost can be obtained by the proposed separation
method as compared to that of a three-column extractive distillation
system published in open literature
Design and Control of the Glycerol Tertiary Butyl Ethers Process for the Utilization of a Renewable Resource
In this paper, the design and control of an improved process for the manufacture of a fuel additive (glycerol tertiary butyl ethers, GTBE) from glycerol and isobutylene is developed. The improved process redirects one recycle stream, uses a stripping column instead of a flash tank to recover isobutylene, and uses a rectifying column instead of a distillation column to purify the product. Economic analysis shows that the improved process has a 22% lower total annual cost (TAC) than the best known process published in the literature. Significant increases in the selectivity of the overall process from 84.7% to 99.3% can also be realized by comparing the optimized improved design versus the original design. Dynamic simulations were also conducted and indicated that stringent product specification can be met with a simple decentralized feedback control structure despite impurities in the feed streams and also changes in the throughput