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All Journal Reaktor Sinergi ASEAN Journal of Chemical Engineering
Abdul Wahid
Dept. of Chemical Engineering, Faculty of Engineering, University of Indonesia
Biochemistry, Genetics & Molecular Biology Chemical Engineering, Chemistry & Bioengineering Chemistry Civil Engineering, Building, Construction & Architecture Control & Systems Engineering Electrical & Electronics Engineering Energy Engineering Industrial & Manufacturing Engineering Materials Science & Nanotechnology

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 1 
APPLICATION OF MODEL PREDICTIVE CONTROL (MPC) TUNING STRATEGY IN MULTIVARIABLE CONTROL OF DISTILLATION COLUMN A. Ahmad; A. Wahid
Reaktor Volume 11, Nomor 2, Desember 2007
Publisher : Dept. of Chemical Engineering, Diponegoro University

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (624.964 KB) | DOI: 10.14710/reaktor.11.2.66-70

Abstract

A model predictive control strategy is proposed for multivariable nonlinear control problem in a distillation column. The aim is to provide a solution to nonlinear control problem that is favorable in terms of industrial implementation. The scheme utilizes multiple linear models to cover wider range of operating conditions. Depending on the operating conditions, suitable model is used in control computations. Servo and regulatory controls of the system are examined. Comparisons are made to conventional controllers. The results confirmed the potentials of the proposed strategy.
PENGENDALIAN KOMPRESOR DAN STEAM REFORMER PADA PERANCANGAN PABRIK BIOHIDROGEN DARI BIOMASSA DENGAN PENGENDALI PI Abdul Wahid; Muhammad Iqbal
SINERGI Vol 20, No 2 (2016)
Publisher : Universitas Mercu Buana

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (685.118 KB) | DOI: 10.22441/sinergi.2016.2.001

Abstract

Proses pada pabrik biohidrogen dari biomassa terbagi menjadi beberapa unit proses, yaitu unit pengolahan awal bahan baku, unit gasifikasi, unit char combustor, unit kompresi, unit H2S Removal, unit steam reforming, unit water gas shift, dan unit pressure swing adsorber. Pada penelitian ini akan dijelaskan pengendalian pada kompresor dan steam reformer. Kedua unit tersebut penting dikendalikan agar mencapai tekanan yang diinginkan pada masukan H2S Removal dan untuk mendapatkan gas hidrogen pada unit Steam Reformer. Pengendali yang digunakan adalah pengendali PI karena hampir dapat menangani setiap situasi pengendalian proses. Untuk mendapatkan kinerja yang optimum, dilakukan penyetelan pengendali dengan metode Ziegler Nichols, Lopez, dan Default Unisim, kemudian membandingkan nilai IAE dan ISE dari ketiga jenis penyetelan tersebut. Hasilnya pengendalian tekanan dan suhu yang optimum adalah dengan metode penyetelan pengendali Ziegler Nichols. Sedangkan pengendalian surge-01, surge-02, surge-03 pada kompresor metode yang paling optimum adalah Default Unisim, dan untuk surge-04 adalah metode Lopez.
MODELING AND CONTROL OF MULTIVARIABLE DISTILLATION COLUMN USING MODEL PREDICTIVE CONTROL USING UNISIM Abdul Wahid; Richi Adi
SINERGI Vol 20, No 1 (2016)
Publisher : Universitas Mercu Buana

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (422.37 KB) | DOI: 10.22441/sinergi.2016.1.003

Abstract

Distillation columns are widely used in chemical industry as unit operation and required advance process control because it has multi input multi output (MIMO) or multi-variable system, which is hard to be controlled. Model predictive control (MPC) is one of alternative controller developed for MIMO system due to loops interaction to be controlled. This study aimed to obtain dynamic model of process control on a distillation column using MPC, and to get the optimum performance of MPC controller. Process control in distillation columns performed by simulating the dynamic models of distillation columns by UNISIM R390.1 software. The optimization process was carried out by tuning the MPC controller parameters such as sampling time (Ts = 1 – 240 s), prediction horizon (P = 1-400), and the control horizon (M=1-400). The comparison between the performance of MPC and PI controller is presented and Integral Absolut Error (IAE) was used as comparison parameter. The results indicate that the performance of MPC was better than PI controller for set point change 0.95 to 0.94 on distillate product composition using a modified model 1 with IAE 0.0584 for MPC controller and 0.0782 for PI controller.
PENGENDALIAN REAKTOR ALIR TANGKI BERPENGADUK MENGGUNAKAN REPRESENTATIVE MODEL PREDICTIVE CONTROL Abdul Wahid; Fazza Imanuddin Harsya Ramadhani
SINERGI Vol 19, No 3 (2015)
Publisher : Universitas Mercu Buana

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (797.424 KB) | DOI: 10.22441/sinergi.2015.3.010

Abstract

Permasalahan terbesar dalam pengendalian reaktor alir tangki berpengaduk adalah sistem yang sangat tidak linear dan multivariabel. Sistem pengendalian konvensional tidak dapat mengkontrol sistem semacam ini dengan optimal, sehingga kemurnian produk yang dihasilkan rendah. Multiple Model Predictive Control (MMPC) digunakan untuk mengatasi masalah pengendalian proses yang nonlinear dan melibatkan banyak variabel. Beberapa MPC lokal digunakan pada MMPC diperoleh dengan metode yang baru dikembangkan, Representative Model Predictive Control (RMPC). Penelitian ini menggunakan model reaktor alir tangki berpengaduk yang disimulasikan dengan perangkat lunak MATLAB. Variabel yang dimanipulasi adalah suhu inlet pendingin dan konsentrasi umpan. Sedangkan variabel yang dikontrol adalah komposisi produk. Untuk perubahan set point konsentrasi produk dari 8.5 sampai 8.6; disarankan menggunakan MMPC 4,1,2.
PENGENDALIAN pH LIMBAH CAIR LABORATORIUM DEPARTEMEN TEKNIK KIMIA UI MENGGUNAKAN PENGENDALI PID LINEAR PADA MINI PLANT WA921 Abdul Wahid; Faizal Abdillah
SINERGI Vol 18, No 2 (2014)
Publisher : Universitas Mercu Buana

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (351.51 KB)

Abstract

Setiap semester Laboratorium Dasar Proses Kimia Departemen Teknik Kimia UI menghasilkan sekitar 180 liter limbah cair (asam campuran). Limbah ini tentunya harus diolah supaya dapat dibuang ke lingkungan dengan memenuhi standar baku mutu air buangan. Departemen Teknik Kimia memiliki alat simulasi pengendali pH air yaitu unit mini plant WA921. Penelitian ini bertujuan untuk menemukan parameter PID linear optimum yang dapat diterapkan di unit mini plant WA921 untuk menetralkan pH limbah tersebut yang memiliki sifat nonlinear. Dari pengujian unjuk kerja terhadap alat ini dalam menetralkan pH limbah, didapatkan parameter PID sebagai berikut: PB = 6,6%, TI = 166 detik, TD = 41 detik pada skema S dan PB = 3,4%, TI = 59 detik, TI = 14 detik pada skema L. Kedua hasil tersebut memiliki kinerja yang lebih baik dari pada setelan parameter pengendali PID linear hasil pengujian sebelumnya (asam murni).
PEMODELAN DINAMIK DAN PENGENDALIAN PROSES STIRRED TANK HEATER MENGGUNAKAN SISTEM DINAMIK Abdul Wahid; I Gede Eka Perdana Putra; Ferdi Fajrian Adicandra; Agasta Prio Prasetyo; Yoga Wiranoto
SINERGI Vol 21, No 2 (2017)
Publisher : Universitas Mercu Buana

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (512.247 KB) | DOI: 10.22441/sinergi.2017.2.002

Abstract

Stirred tank heater digunakan dalam proses kimia untuk memanaskan fluida hingga mencapai suhu yang diinginkan. Prinsip pemanasan pada stirred tank heater adalah dengan mengalirkan fluida pemanas dalam koil atau jaket pemanas. Suhu fluida proses dijaga dengan mengendalikan laju alir fluida pemanas. Pengendalian suhu stirred tank heater dengan algoritma PID (proportional-integral-derivatif) dilakukan menggunakan model dinamik proses yang diturunkan dari persamaan neraca massa dan energi. Pemodelan dinamik dan pengendaliannya menggunakan metode sistem dinamik dengan bantuan perangkat lunak ithinkTM.  Hasil simulasinya menunjukkan bahwa pengendali yang dipasang dapat menangani perubahan setpoint dan gangguan hingga ±15% secara baik.
PENGENDALIAN PROSES PURIFIKASI DME DAN METANOL PADA PABRIK DME DARI GAS SINTESIS Abdul Wahid; Tubagus Aryandi Gunawan
SINERGI Vol 19, No 1 (2015)
Publisher : Universitas Mercu Buana

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (842.698 KB) | DOI: 10.22441/sinergi.2015.1.010

Abstract

Pengembangan produksi DME (dimetil eter) sebagai energi alternatif yang ramah lingkungan sudah banyak dilakukan di negara-negara lain seperti Jerman, Belanda, Australia, Jepang, China dan Taiwan. Indonesia masih mengimpor DME untuk memenuhi seluruh kebutuhan industri dalam negeri, karena itu perlu didirikan pabrik pembuatan DME. Proses pembuatan DME secara indirect melibatkan sintesis metanol, dehidrasi metanol, purifikasi DME hingga purifikasi metanol untuk di recylce. Optimasi proses purifikasi DME dilakukan dengan mendapatkan kinerja pengendalian yang optimum pada proses purifikasi DME hingga purifikasi metanol. Unit-unit yang ada pada proses purifikasi DME ialah unit distilasi DME, unit cooler dan unit storage tank, sedangkan pada proses purifikasi metanol terdapat unit distilasi metanol, unit cooler dan unit pompa. Proses purifikasi DME dan Metanol ini mengandalkan unit distilasi yang memiliki suhu operasi hingga 190oC dan tekanan hingga 1950 kPa. Sistem pengendalian yang dipilih untuk proses ini ialah jenis pengendali Proportional Integral (PI) karena dapat menangani hampir setiap situasi pengendalian proses di dalam skala industri. Penelitian ini menggunakan pemodelan penyetelan pengendali Ziegler Nichols dan Lopez, lalu dibandingkan nilai parameter kinerja pengendalinya yaitu Offset, Rise Time, Time of First Peak, Settling Time, Periode osilasi, Decay Ratio, Overshoot, Deviasi maksimum, Integral Absolute Error (IAE) dan Integral Square Error (ISE) dari kedua jenis penyetelan tersebut. Hasil penelitian ini dapat digunakan untuk penentuan variabel input dan output yang optimum pada proses purifikasi DME dan Metanol yang dapat diterapkan pada pabrik DME.
MULTI-LOOP CONTROL DESIGN IN MULTIVARIABLE (2X2) CONTINUOUS STIRRED TANK REACTOR Abdul Wahid; William Andreas Hambali
SINERGI Vol 19, No 2 (2015)
Publisher : Universitas Mercu Buana

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (852.401 KB) | DOI: 10.22441/sinergi.2015.2.001

Abstract

With this study, the design and tuning of multi-loop for multivariable (2x2) CSTR will be made in order to achieve optimum CSTR control performance. This study used Bequette model reactor and MATLAB software and is expected to be able to cope with disturbances in the reactor so that the reactor system is able to stabilize quickly despite the distractions. In this study, the design will be made using multi-loop approach, along with PI controller as the next step. Then, BLT and auto-tune tuning method will be used in PI controller and given disturbances to both of tuning method. The controller performances are then compared. Results of the study are then analyzed for discussions and conclusions. Results from this study have shown that in terms of disturbance rejection, BLT is better than auto-tune based on comparison between both of controller performances. For IAE for the case of temperature, BLT is 30% better than auto-tune, but it is almost the same for the case of concentration. For settling time for the case of concentration, BLT is 30% better than auto-tune, and for the case of temperature, BLT is 18% better than auto-tune. For rise time for the case of concentration and temperature, BLT is 30% better than auto-tune.
Effect of Ultrasonic During Preparation on Cu-Based Catalyst Performance for Hydrogenation of C02 to Methanol M Nasikin; A Wahid
ASEAN Journal of Chemical Engineering Vol 5, No 2 (2005)
Publisher : Department of Chemical Engineering, Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/ajche.50178

Abstract

Indonesia is rich in natural gas resources. These resources contain hydrocarbons and impurities such as C02. C02 creates a difficulty in further gas treatment and also becomes an environmental problem. Therefore, it is needed to develop a concept to recover this kind of gas and to convert it into more useful chemicals. Catalytic hydrogenation to methanol is one of the technologies that can be considered. Conversion of C02 to methanol can be catalyzed by Cu-based catalyst. Reported tobe the best catalyst, this catalyst is selected as a catalyst for a pilot plant that is operated at a high pressure and a high temperature. However, further development is needed to rearrange the synthesis to be operated both at lower pressure and temperature. For this system, it is needed to increase its catalytic activity. One of the alternatives is to apply a catalyst preparation method using ultrasonic effect. In this research work, CuO/ZnO/AJp3 catalyst with Cr as a promoter was prepared by co-precipitation method. The effect of ultrasonic on catalyst performance, which was irradiated to the catalyst during preparation, was investigated. Co-precipitation was conducted by using carbonate salt for respective metal cations added to the catalyst. Ultrasonic wave was irradiated to the catalyst preparation chamber with 40kHZ and time variable. The characteristics of the catalyst were analyzed by BET method for surface area, while SEM and H2 chemical adsorption were conducted to determine active site dispersion. A high-pressure continuous flow reactor was used for catalyst activity and stability test. The test was conducted at an operation condition of 30 bars and 200-30QoC. The effect of ultrasonic on the CuO/ZnO/AJp3 catalyst shows that ultrasonic irradiation enhances the catalyst surface from 23 to 50 m2/g. SEM analysis shows the change of catalyst morphology to be more uniform and the catalyst particle becomes smaller. The activity test shows that the catalyst with 60 min irradiation time has the highest activity in the hydrogenation of C02 to methanol at 30 bars and at 275°C. Keywords: Hydrogenation, dispersion, methanol, and ultrasonic.
Co-Authors A. Ahmad Agasta Prio Prasetyo Faizal Abdillah Fazza Imanuddin Harsya Ramadhani Ferdi Fajrian Adicandra I Gede Eka Perdana Putra M Nasikin Muhammad Iqbal Richi Adi Tubagus Aryandi Gunawan William Andreas Hambali Yoga Wiranoto