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ASEAN Journal of Chemical Engineering

AJChE
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Published by Universitas Gadjah Mada

ISSN : 26555409 EISSN : 26555409 DOI : https://doi.org/10.22146/ajche.52004

Core Subject : Science, Engineering,

Biochemistry, Genetics & Molecular Biology Chemical Engineering, Chemistry & Bioengineering Chemistry

The ASEAN Journal of Chemical Engineering publishes papers on Chemical Engineering, specifically but not limited to the areas of thermodynamics, reaction kinetics, transport phenomena, process control, environment, energy, biotechnology, corrosion, separation science, powder technology, materials science, and chemical engineering education

Arjuna Subject : Teknik Kimia (semua kategori) - Kimia Proses dan Teknologi

Articles 372 Documents

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An Improved Method to Calculate the Conservation of Mass in the Simulation of Rapid Pressurization Depressurization in a Packed Bed Thomas S.Y Chong; William R. Paterson; David M. Scott
ASEAN Journal of Chemical Engineering Vol 2, No 1 (2002)
Publisher : Department of Chemical Engineering, Universitas Gadjah Mada

The work described here forms part of a project to model rapid pressure swing adsorption (RPSA), which is a single-bed process used for air separation. We have earlier identified a form of model and boundary conditions for an axially dispersed plug flow model that conserves mass. We solve the RPSA models numerically by spatially discretizing the partial differential equations to a system of ordinary differential equations (ODEs), which are then integrated over time. Although the formulation of our models conserves mass, our numerical simulations, however, do not perfectly conserve mass because of discretization error and rounding error. The discrepancy in the conservation of mass is computed as a guide to the numerical accuracy of the calculations. The computation of the conservation error requires the evaluation of time integrals of molar flowrates in and out of the bed. Since the velocity at the feed end of the bed changes rapidly with time, the application of quadrature to evaluate the time integrals does not provide the accuracy required. In this paper, the inadequacy is demonstrated using a simple problem, i.e. pressurization and depressurization into a non-adsorptive bed. An improved method is proposed. By transforming equations involving time integrals into ODEs, excellent accuracy is obtained. Further, this transformation minimizes the number of decision parameters that need to be specified by the users of the computer programs. Keywords: rapid pressure swing adsorption, modelling and simulation, packed bed.

CO Oxidation over Metal Oxide CatalystSupported by Indonesian Natural Zeolite Suryo Purwono
ASEAN Journal of Chemical Engineering Vol 2, No 1 (2002)
Publisher : Department of Chemical Engineering, Universitas Gadjah Mada

The objectives of this study are to attempt to develop catalysts and to find the operating conditions under which combustible waste gases concentrations in the exhaust gases can be eventually reduced to satisfy air pollution standards. The results shows that using impregnation method, nickel and vanadium metals, as active components of the catalyst, can be dispersed on the natural zeolite as catalyst support. The reaction rate measurements of catalytic oxidation of CO was done in the temperature range between 300 and 550°C using a differential micro-reactor. The catalysts used for this experiment were vanadium pentoxide and nickel oxide on activated natural zeolite. To avoid fluidization, the reactant gases were flowed downward. The results show that the reaction rate depends strongly on the bed temperature and feed concentration and is not controlled by bulk phase mass transfer and pore diffusion.

Oscillatory Flow Mixer for Pulp Bleaching Taslim Taslim; Mohd Sabri Takriff
ASEAN Journal of Chemical Engineering Vol 2, No 1 (2002)
Publisher : Department of Chemical Engineering, Universitas Gadjah Mada

This paper reports the results of an investigation on the use of oscillatory baffled column as a mixer for pulp bleaching. Unbleached hardwood kraft pulp was bleached using hydrogen peroxide. Variables studied were oscillation frequency, oscillation amplitude, and pulp consistency. The mixing process was achieved by oscillating pulp suspension in a periodically baffled column at a certain frequency and amplitude. The mixing quality of pulp bleaching was quantified using mixing index. The results showed that mixing quality improved with oscillation frequency and amplitude, but decreased with pulp consistency. This typical device is very promising as a mixer for pulp bleaching.

Deagglomeration of High Purity Fine Alumina Powder via pH Control Andanastuti Muchtar; Norazmira Wati; Nor Azri Jaafar
ASEAN Journal of Chemical Engineering Vol 2, No 1 (2002)
Publisher : Department of Chemical Engineering, Universitas Gadjah Mada

This paper presents results from a study on the effect of the pH of suspensions on the deagglomeration of a high-purity (99.99%), fine-grained alumina powder. The pH of the suspension was varied between pH 2 and 3. It is the aim of the study to determine the best pH for a successful dispersion of the alumina powders in the suspension. A series of rheological studies and analytical work under Scanning Electron Microscopy were conducted. It was found that the best pH was pH 2. Data obtained from rheological studies using a viscometer showed that the alumina suspension prepared at pH 2 was least viscous, which may be taken as a negative indicator of the presence of agglomerates. This hypothesis is validated by visual inspection using SEM. For the pH 2 samples, a successful removal of the agglomerates in the green compact has encouraged the sinterability of the samples and thus, resulted in an earlier sintering process at a low-firing temperature. In addition, the sintering characteristics and microstructures of the samples prepared with a pH 2 suspension are also presented.

Reduction of NOx Emission from Gas TURBINE COMBUSTOR Applying Fuel-Staged Combustion Mohammad Nazri; Mohd. Jaafar
ASEAN Journal of Chemical Engineering Vol 2, No 1 (2002)
Publisher : Department of Chemical Engineering, Universitas Gadjah Mada

A two-stage lean/lean gas turbine combustor was developed with low NOx characteristics in each stage using a small radial swirler of 40-mm outlet diameter in the pilot stage. Both flame tubes were arranged in series with the smaller combustor (76 mm inside diameter) as the pilot stage and the larger combustor (140 mm inside diameter) as the main stage. The pilot stage was fuelled via vane passage fuel injector, while the main stage was fuelled around the wall of the exit plane of the pilot stage, using wall fuel injectors. Low NOx emissions were obtained when using fuel staging for methane fuel, as low as 6 ppm. A NO. reduction of more than 40 % was obtained at equivalence ratio of near 0.7, when using fuel staging compared to the non-fuel-staging test. Tests were conducted using methane as fuel. This was achieved at very small increase in carbon monoxide emissions especially near the rich region and with almost no increase at all in the unburned hydrocarbon emissions at the same equivalence ratio.Keywords: NOx emissions, fuel staging, carbon monoxide, swirler.

Effects of Shear Rate on Morphology and Gas Separation Performance as Asymetric Polysulfone Membranes Ahmad Fauzi Ismail; Lai Ping Yean
ASEAN Journal of Chemical Engineering Vol 2, No 1 (2002)
Publisher : Department of Chemical Engineering, Universitas Gadjah Mada

Asymmetric polysulfone flat sheet membranes have been produced by a dry/wet casting technique. The membranes were produced at different shear rate. Gas permeation properties were examined using pure hydrogen and nitrogen as test gases. Infrared dichroism was detected in all samples, the extent being greater in the high shear membranes. This suggests that the polymer molecules become aligned under high shear. Gas separation tests showed that the higher shear membranes exhibited greater selectivity (H!Nz)' Some of the membrane selectivities even surpass the intrinsic selectivity of the membrane polymer. Increasing shear rate during casting had decreased skin layer thickness and thus increased pressure-normalized flux. High-shear casting also enhances the molecular orientation in skin layer and, in turn, heighten selectivity of membrane. Therefore, correlation of rheological aspects with primary phase inversion parameters provides a potential platform to develop high performance asymmetric polysulfone membranes for gas separation.Key words: asymmetric membranes, gas separation, rheology, molecular orientation, super-selective, polysulfone

A Review on Fuel Cell as Advanced Power Source S. K. Kamarudin; W.R. W. Daud; M. S. Ayub; A. W. Mohammad; S. E. lyuke
ASEAN Journal of Chemical Engineering Vol 2, No 1 (2002)
Publisher : Department of Chemical Engineering, Universitas Gadjah Mada

Fuel cells are making headlines across the globe in almost all arenas of power production. While the technology for these electrochemical power plants was invented around 1839 and has been in use for nearly 150 years, it is only recently that fuel cells have gained popular recognition and reckoned for serious consideration as a power zone for the future. Despite their relatively new arrival on the popular scene, fuel cells have already found their way into pre-commercial testing in domestic, commercial, industrial and mobile applications. Fuel cells convert chemical energy of a fuel gas directly into electrical work, and are efficient and environmentally clean, since no combustion is involved. Fuel cells are presently under development for a variety of generation application in response to the critical need for a cleaner energy technology. The use of fuel cell systems has been strongly promoted in Japan and the United States for medium-scale co-generation plants. Nowadays, this interest has been extended to the smaller scale, in particular at the residential area level. All fuel cells currently being developed for near term use in electric vehicles require hydrogen as a fuel. At the same time, increased interest has arisen for the application of fuel cell systems to automotive propulsion, although there is no clear option on the direct use of hydrogen stored on board or the installation of hydrogen plant on board as of this time. This paper outlines the acute global population growth and the growing need and use of energy and its component as well as its environmental impact. In particular, this paper reviews the existing or emerging fuel cells technologies, limitations, and their benefits in connection with energy, environment and sustainable development relationship. In addition, this paper also explores fuel sources and the various types of fuel cells as well as their applications.

Measuring and Modeling the Performance of Rigid Ceramic Filters T. G. Chuah M; J. P.K Seville
ASEAN Journal of Chemical Engineering Vol 2, No 1 (2002)
Publisher : Department of Chemical Engineering, Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/ajche.50807

Rigid ceramic filters have been proven to be highly efficient gas filtration devices. However, they must be cleaned periodically for maximum efficiency. This is done by applying a pulsed reverse flow. The cleaning mechanism by which the deposited dirt is removed from the filter surface is still not fully understood. Experiments were carried out to measure pressure drop along the axis of two different candle geometry, cylindrical and tapered. For the cylindrical filter, the reverse pulse pressure was not uniformly distributed along the element. Generally, the pressure difference across the wall of the element is highest at the close end, and lowest, sometimes close to zero, at the open end. Pressure drop across the tapered filter was more uniform compared to that of the cylindrical filter. Hence, it should demonstrate better filter dirt removal. The authors have written a computer program that models the flow of the reverse pulse from the cleaning bar nozzle to the dirty side of the filter. It uses the iterative calculation mode and allows variables such as reverse pulse pressure and filter geometry to be changed. The calculations demonstrate fair agreement with the experimental results.

Use of the Taguchi Design of Experiments to Optimize the Parameters of Cleaning Machines for Sensitive Plastic Products Sherwin Celestino; Joseph Auresenla
ASEAN Journal of Chemical Engineering Vol 2, No 1 (2002)
Publisher : Department of Chemical Engineering, Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/ajche.50808

The Taguchi Design of Experiments (DOE), an optimization technique, was used to establish stabilized operating parameter settings for an ultrasonic cleaning machine for a new and very dirt sensitive plastic product referred to as type A plastic produced in a company in the Philippines. The optimization process is done in actual industrial setting. Taguchi DOE defined quality as minimum variation around the target specification of a product. The matrix used for the project is the La 27 orthogonal array wherein the experiment is comprised of eight runs with seven maximum possible factors at two levels. After each experimental run, the percentage ejection rate was monitored as the measurable characteristic of the finished product. Since rejection rate was the parameter used, the ultimate value closer to zero is better (the smaller the better). Confirmation runs showed that the percentage of rejection rate has improved from 62% to 17% when the established optimized machine parameters were used. Moreover, production yield has increased from 75% to more than 90% for product type A.

Gas-LiquidMassTransferin Continuous Oscillatory Flow BaaledColumnina Taslim Taslim; Mahd. Sabri Takriff
ASEAN Journal of Chemical Engineering Vol 4, No 2 (2004)
Publisher : Department of Chemical Engineering, Universitas Gadjah Mada

Gas-liquid mass transfer in continuous oscillatory flow was conducted in a vertical baffled column. Pure carbon dioxide (C02) was used as the dispersed phase and tap water was used as the continuous phase. The mass transfer rate of C02 measured under continuous operation was expressed in terms of the liquid-side volumetric mass transfer coefficient (kLa) and was calculated using a stationary method. The effects of oscillation frequency, oscillation amplitude, and flow rates on mass transfer were also determined. The results showed that a significant increase in mass transfer could be achieved in oscillatory flow in a baffled column comp.:lfed to that in a bubble column. The mass transfer in continuous oscillatory flow in a baffled column was not affected by the liquid flow rate in the range tested. Then, kLQwas correlated as a function of power density and superficial gas velocity.

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Contact Name
Ari Pramudyantoro

Contact Email
ajche.ft@ugm.ac.id

Phone
+62274555320

Journal Mail Official
ajche.ft@ugm.ac.id

Editorial Address
Jln. Grafika No. 2 Kampus UGM Yogyakarta Indonesia 55281

Location
Kab. sleman,

Daerah istimewa yogyakarta

INDONESIA

Abstract

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Home Page

OAI Link

Editorial Team

Contact

Reviewer

Google Scholar

Contact Name Ari Pramudyantoro

Contact Email ajche.ft@ugm.ac.id

Phone +62274555320

Journal Mail Official ajche.ft@ugm.ac.id

Editorial Address Jln. Grafika No. 2 Kampus UGM Yogyakarta Indonesia 55281

Location Kab. sleman, Daerah istimewa yogyakarta INDONESIA

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Contact Name
Ari Pramudyantoro

Contact Email
ajche.ft@ugm.ac.id

Phone
+62274555320

Journal Mail Official
ajche.ft@ugm.ac.id

Editorial Address
Jln. Grafika No. 2 Kampus UGM Yogyakarta Indonesia 55281

Location
Kab. sleman,

Daerah istimewa yogyakarta

INDONESIA