21 research outputs found
Optimal design of distillation column using three dimensional exergy analysis curves
This paper presents two main contributions. Firstly, a new exergy graphical method is proposed for optimaldesign of distillationcolumn with minimum exergy lost. The method is applicable to both grass-root and retrofit cases, respectively. The effect of design and operating parameters of a distillationcolumn on the exergy lost is graphically visualized by threedimensionalexergyanalysiscurves. The curve shows the correlations between exergy lost, design and operating parameters of a distillationcolumn. This technique can be used as an effective method to reduce the simulation effort to search for the optimum design and operating parameters of a distillationcolumn at minimum exergy lost. Besides, visualization also enhances the engineers’ understanding of the column performance. The other contribution is a four-level idealization concept, which is based on threedimensional graphical exergyanalysiscurves. The concept defines the effect of transport rate and configuration on exergy lost of distillationcolumn. The effectiveness of the method has been demonstrated on a xylene column, which suggested that an implementation of feed pre-heater yields a significant reduction in exergy lost by up to 15.5%
Application of an environmentally optimum cooling water system design to water and energy conservation
Recirculating cooling water systems are consist of a cooling tower and
heat-exchanger network which conventionally have a parallel
configuration. However, reuse of water between different cooling duties
enables cooling water networks to be designed with series arrangements.
This will result in performance improvement and increased cooling tower
capacity. Research on recirculating cooling water systems has mostly
focused on the individual components. However, a particular design
method represented by Kim and Smith accounts for the whole system
interactions. In this study, the Kim and Smith design method is
expanded and a comprehensive simulation model of recirculating cooling
system was developed to account for the interaction between the cooling
tower performance and the heat-exchanger network configuration.
Regarding this model and considering cycle water quality through
introducing ozone treatment technology, a modern methodology of
recirculating cooling water system design was established and
developed. This technique, called the integrated ozone treatment
cooling system design, is a superior designed tool based on pinch
analysis and mathematical programing. It also ensures maximum water and
energy conservation, minimum cost and environmental impacts. Related
coding in MATLAB version 7.3 was used for the illustrative example to
get optimal values in cooling water design method computations. The
result of the recently introduced design methodology was compared with
the Kim and Smith design method
Comparison of Stochastic Methods with Respect to Performance and Reliability of Low Temp Gas Separation Processes
New Method for Designing an Optimum Distributed Cooling System for Effluent Thermal Treatment
Temperature restrictions on aqueous effluents dictate that streams with
a temperature higher than the permitted level needed to pass through
cooling systems to reduce the effluent temperature before discharge. In
this study, by considering the grouping design rules based on pinch
technology, an optimum design for a distributed effluent cooling
system, has been developed. A counter-flow wet cooling tower, with a
mechanical air draft, is also assumed as an effluent thermal treatment
facility in predicting the exit water and air conditions of the tower
in the system. In this new design method, an optimum inlet flow rate to
cooling tower has been achieved by exploring the feasible region. Also,
the evaporation loss effect, flexible design variables, and physical
properties have been incorporated in targeting the optimal conditions
for the cooling tower. A case study is presented to illustrate the
design methodology and the optimization model of cooling systems
Techno-economic optimization of IGCC integrated with utility system for CO2emissions reduction—Maximum power production in IGCC
Solar thermochemical production of ammonia from water, air and sunlight: thermodynamic and economic analyses
Ammonia is an important input into agriculture and is used widely as base chemical for the chemical industry. It has recently been proposed as a sustainable transportation fuel and convenient one-way hydrogen carrier. Employing typical meteorological data for Palmdale, CA, solar energy is considered here as an inexpensive and renewable energy alternative in the synthesis of NH[subscript 3] at ambient pressure and without natural gas. Thermodynamic process analysis shows that a molybdenum-based solar thermochemical NH[subscript 3] production cycle, conducted at or below 1500 K, combined with solar thermochemical H[subscript 2] production from water may operate at a net-efficiency ranging from 23 to 30% (lower heating value of NH[subscript 3] relative to the total energy input). Net present value optimization indicates ecologically and economically sustainable NH[subscript 3] synthesis at above about 160 tons NH[subscript 3] per day, dependent primarily on heliostat costs (varied between 90 and 164 dollars/m²), NH[subscript 3] yields (ranging from 13.9 mol% to stoichiometric conversion of fixed and reduced nitrogen to NH[subscript 3]), and the NH[subscript 3] sales price. Economically feasible production at an optimum plant capacity near 900 tons NH[subscript 3] per day is shown at relative conservative technical assumptions and at a reasonable NH[subscript 3] sales price of about 534 ± 28 dollars per ton NH[subscript 3]