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Jurnal Rekayasa Proses
Published by Universitas Gadjah Mada
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Search results for , issue "Vol 6, No 2 (2012)" : 5 Documents clear
Studi Simulasi pada Unit Reformer Primer di PT Pupuk Sriwidjaya Palembang Sigit Abdurrakhman; Sutijan; Muslikhin Hidayat
Jurnal Rekayasa Proses Vol 6, No 2 (2012)
Publisher : Departemen Teknik Kimia Fakultas Teknik Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (393.755 KB) | DOI: 10.22146/jrekpros.4693

Abstract

Pabrik amonia merupakan salah satu pabrik yang terdapat di industri pupuk. Unit Reformer Primer merupakan salah satu alat di pabrik amonia yang merupakan tempat terjadinya reaksi katalitik antara steam dengan metana dikenal dengan proses steam methane reforming. Bahan baku utama adalah steam (H2O) dan gas alam dengan kandungan utama metana (CH4). Penelitian ini membuat model proses unit Reformer Primer untuk menghitung profil temperatur, tekanan dan komposisi untuk kondisi operasi steady state dengan berdasarkan kondisi operasi di pabrik Amonia Pusri 3 PT Pupuk Sriwidjaya Palembang. Asumsi yang digunakan adalah plug flow baik pada sisi furnace maupun pada sisi reaktor katalitik dan kondisi steady state. Untuk menyelesaikan persamaan diferensial ordiner yang digunakan pada penelitian ini dipakai metode Runge Kutta dengan program SciLab sehingga didapat profil konversi dan temperatur di Reformer Primer. Variabel yang mempengaruhi dalam reaksi di Reformer Primer adalah temperatur, tekanan, dan komposisi. Hasil simulasi jika dibandingkan dengan data operasional pabrik menunjukkan ralat rerata 3,94 %. Jika model tersebut digunakan pada berbagai kondisi operasi menghasilkan ralat rerata 7,01 %. Kata kunci: reformer primer, metana, steam, amonia Ammonia plant is the main part of fertilizer industry. Primary reformer is an unit operation where catalytic reaction between steam and methane take place, or it is known as steam methane reforming. The main raw material is steam (H2O) and natural gas with major content of methane (CH4). The objective of this research was to develop primary reformer unit process model to calculate temperature, pressure and composition profiles for steady state operation according to operating condition on Ammonia III plant in PT Pupuk Sriwidjaya Palembang. The assumption used was plug flow model both on the furnace side and on the catalytic reactor side for steady state conditions. The ordinary differential equations were solved using Runge Kutta method with Scilab software to get the conversion, pressure and temperature profiles on primary reformer. Variabels evaluated were temperature, pressure, and composition. The simulation result showed that an average error of 3.94 % compared to the operational plant data. For various operating conditions this simulation showed an average error of 7.01 %. Keyword: primary reformer, methane, steam, ammonia
Kinetika Reaksi Polimerisasi Urea-Asetaldehid dalam Proses Enkapsulasi Urea Indah Purnamasari; Rochmadi; Hary Sulistyo
Jurnal Rekayasa Proses Vol 6, No 2 (2012)
Publisher : Departemen Teknik Kimia Fakultas Teknik Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (463.817 KB) | DOI: 10.22146/jrekpros.4694

Abstract

Untuk meningkatkan efektivitas penggunaan urea dan mengurangi pencemaran lingkungan, perlu dilakukan enkapsulasi urea sehingga pelepasan urea dalam air dapat dikontrol. Dinding kapsul terbentuk langsung di permukaan partikel urea yang disebut in situ polimerisasi. Penelitian ini bertujuan untuk mempelajari kinetika reaksi polimerisasi urea dan asetaldehid dalam proses enkapsulasi urea. Urea dan asetaldehid dengan perbandingan 1:1,2 mol/mol dimasukkan ke dalam erlenmeyer yang dilengkapi dengan termometer dan pendingin. Reaksi dijalankan di dalam erlenmeyer selama 2 jam dan contoh diambil setiap 20 menit untuk dianalisis asetaldehid sisa dengan metode sodium sulfit dan ukuran butiran diukur dengan mikroskop optik dan menggunakan software image pro. Variabel yang dipelajari adalah suhu reaksi (5-15°C), ukuran butir urea (14, 18, dan 25 mesh), dan pH (2, 3, 4). Konstanta kecepatan reaksi dan koefisien difusivitas ditentukan dengan optimasi antara model dengan data penelitian. Hasil penelitian menunjukkan bahwa semakin tinggi suhu dan ukuran butir, semakin tinggi konversi yang dihasilkan. Semakin rendah pH (semakin asam) memberikan konversi yang semakin tinggi akan tetapi butiran hasil sedikit mengembang dan lengket. Model kinetika reaksi yang diajukan sesuai dengan data pengamatan. Reaksi adisi berlangsung lebih cepat dibandingkan dengan reaksi kondensasi. Kondisi reaksi yang cukup baik terjadi pada suhu reaksi 15°C, pH 4, ukuran butir 14 mesh dan waktu 120 menit dengan konversi sebesar 63,38%. Pada kondisi ini, produk polimer yang dihasilkan lebih keras dibandingkan dengan kondisi yang lainnya. Kata kunci: enkapsulasi, urea-asetaldehid, polimerisasi, pelepasan terkontrol The function of urea encapsulation is to control its release in water, thus increasing effectiveness of using urea and reducing environmental pollution. Microcapsule shell is formed directly on the surface of urea particles called in-situ polymerization. This research aimed to study the kinetics of the polymerization reaction of urea and acetaldehyde in the urea encapsulation process. Urea and acetaldehyde in the ratio of 1:1.2 mol/mol were placed in an erlenmeyer equipped with a thermometer and cooler. The reaction was run for 2 hours in erlenmeyer and sample was taken every 20 minutes. The amount of remaining acetaldehyde was determined by sodium sulfite method and grain size was measured by optical microscope and image pro software. Variables investigated were reaction temperatures (5 - 15°C), particle sizes (14, 18, and 25 mesh), and pH (2 - 4). Reaction rate and diffusivity constants were determined through fitting the experimental data and proposed model. The results showed that the higher temperature and grain size, the higher conversion was. Lower pH (more acid) provides higher conversion but urea particle was seen slightly swelling during the reaction, and also slightly sticky. Addition reaction was much faster than condensation reaction. The proposed reaction kinetics model fitted reasonably well to the experimental data. The process was best conducted at 15°C, 14 mesh, pH 4 and 120 minutes time of reaction which result in 63.38% conversion. Polymer product of urea-acetaldehyde obtained at this condition was slightly harder than that at other conditions. Keywords: encapsulation, urea-acetaldehyde, polymerization, controlled release
Studi Tekno-Ekonomi Pemurnian Biogas dari Limbah Domestik Akhwari Wahyu P; Moh Fahrurrozi; Muslikhin Hidayat
Jurnal Rekayasa Proses Vol 6, No 2 (2012)
Publisher : Departemen Teknik Kimia Fakultas Teknik Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (398.554 KB) | DOI: 10.22146/jrekpros.4695

Abstract

Pemurnian biogas untuk meningkatkan nilai kalor pembakaran dan mencegah korosi. Biogas yang berkomposisi 95% CH4 dapat dimanfaatkan sebagai pengganti gas alam kualitas pipeline. Penelitian ini bertujuan mempelajari kelayakan secara teknis dan ekonomi metode pemurnian biogas, nilai production cost, kapasitas scale-up. Penelitian ini menggunakan data sekunder dari pilot plant Biogas Pasar Induk Buah dan Sayuran Gemah Ripah, Gamping, Sleman. Penelitian menghitung nilai production cost dan kapasitas scale-up untuk tiap metode pemurnian biogas. Sensitivity analysis yang dilakukan pada perubahan komposisi gas CH4 terhadap nilai perbandingan laju solven terhadap laju biogas pada menara absorber dan perubahan harga limbah serta perubahan finances. Secara ekonomi pemurnian biogas paling murah menggunakan water scrubber dengan kapasitas minimum 100 ton limbah domestik/hari. Nilai production cost yang lebih rendah dari harga gas alam kualitas pipeline berkisar antara 6-10 US$/MMBtu. Sensitivity analysis menghasilkan perubahan nilai L/G berkisar 0,005-0,025; variasi harga limbah dari penurunan sampai dengan kenaikan 100% dan perubahan finances 0-15 %, masing-masing memberikan perubahan production cost antara 3-8 US$/MMBtu dan 2-14 US$/MMBtu. Kata kunci : pemurnian biogas, limbah domestik, tekno-ekonomi, biometan Biogas purification can increase the caloric value of combustion and prevent corrosion. Biogas with 95% of methane is similar to pipeline quality natural gas. The objective of this research was to study technical and economical feasibility of biogas purification and also to estimate gas production cost and scale up capacities. This research used the secondary data from pilot plant of Biogas of Pasar Induk Buah dan Sayuran Gemah Ripah, Gamping, Sleman, Yogyakarta. This research was to obtain the production cost and scale up capacities for each biogas purification method. The sensitivity analysis was conducted to study the influence of gas composition ranged at 30-70% CH4 toward the flow of absorbent to gas ratio, the price of waste changed from decreasing 100% up to increasing 100% and the finance changed ranged at 0-15% to the change of production cost. The result showed that water scrubber was the cheapest method for scrubbing impurities. The production cost of scale up capacities compared to the price of pipeline quality natural gas which ranged at 6-10 US$/MMBtu. The minimum capacity of economical biogas purification methods was 100 tons waste/day. The influence of gas composition ranged at 30-70% of CH4 produced the L/G value change in the absorber column ranged at 0,005-0,025; the influence of waste price from decreasing and up to increasing 100% and finances from 0-15% produced the production cost change ranged at 3-8 US$/MMBtu and 2-14 US$/MMBtu respectively. Keywords: biogas purification, domestic waste, techno-economic, bio-methane.
Life Cycle Assessment Pabrik Semen PT Holcim Indonesia Tbk. Pabrik Cilacap: Komparasi antara Bahan Bakar Batubara dengan Biomassa Taufan Ratri Harjanto; Moh Fahrurrozi; I Made Bendiyasa
Jurnal Rekayasa Proses Vol 6, No 2 (2012)
Publisher : Departemen Teknik Kimia Fakultas Teknik Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (308.884 KB) | DOI: 10.22146/jrekpros.4696

Abstract

PT. Holcim Indonesia Tbk. Pabrik Cilacap dengan kapasitas produksi 2,6 juta ton/tahun telah menggunakan sekam padi sebagai energi alternatif biomassa. Penggantian batubara dengan biomassa akan menimbulkan emisi dan dampak ke lingkungan. Penelitian ini bertujuan untuk mengevaluasi dampak lingkungan penggunaan batubara dan biomassa dengan menggunakan metode Life Cycle Assessment (LCA). Pendekatan cradle to gate digunakan untuk mengevaluasi 4 skenario penggunaan bahan bakar: (1) 100% batubara, (2) campuran 90% batubara dan 10% biomassa, (3) campuran 50% batubara dan 50% biomassa, (4) 100% biomassa, dengan basis 1000 kg produk semen. Langkah-langkah evaluasi mengacu pada ISO 14040 tahun 2006 yang terdiri dari: (1) pendefinisian tujuan dan ruang lingkup, (2) analisis inventori, (3) analisis/penakaran dampak, (4) interpretasi. Hasil analisis kontribusi dampak terhadap lingkungan dengan skenario 1, 2, 3, dan 4 diperoleh nilai kontribusi total berturut-turut 2,78 x10-1 Pt, 2,24 x10-1Pt, 1,57 x10-1Pt, dan 8,50 x10-2 Pt. Kategori dampak global warming, respiratory inorganic dan resources merupakan kontributor terbesar dari total dampak terhadap lingkungan. Analisis perbaikan dan rekomendasi mengurangi dampak yang terjadi yaitu mengganti angkutan truck pasir silika dengan kereta api, bahan bakar biomassa menggunakan miscanthus giganteus dan melakukan penghijauan. Kata kunci : PT Holcim Indonesia Tbk. Pabrik Cilacap, Life Cycle Assessment, Komparasi batubara dengan biomassa PT. Holcim Indonesia Tbk. Cilacap having capacity of 2.6 million ton/year uses rice husk as alternative fuels. The utilization of the rice husk will effect the environment. The aim of the study is to evaluate the effects of biomass utilization to environment using life cycle assessment (LCA) method. The “cradle to gate” approach was used to evaluate four scenarios of different fuel combinations: (1) 100% coal, (2) mixed fuel of 90% coal and 10% biomass, (3) mixed fuel of 50% coal and 50% biomass, (4) 100% biomass as primary fuels in the kiln for 1000 kg cement. Evaluation of environment impact related to each scenario was using ISO 14040 (2006) that consists of: (1) goal definition and scoping, (2) inventory analysis, (3) impact assessment, and (4) interpretation. Results showed by contribution analysis, the scenario 1, 2, 3, and 4, give 2.78 x10-1 Pt, 2.24 x10-1Pt, 1.57 x10-1Pt, and 8.50 x10-2 Pt respectively. It was also found that the global warming, respiratory inorganic and resources give significant impacts to the environment. It is suggested to replace silica tranportation using train, to utilize miscanthus giganteus and to grow plants or reforestry. Keywords: PT Holcim Indonesia Tbk Cilacap Plant, Life Cycle Assessment, Comparative Coal with Biomass.
Karakterisasi dan Laju Pembakaran Biobriket Campuran Sampah Organik dan Bungkil Jarak (Jatropha curcas L.) Eddy Kurniawan; Wahyudi Budi Sediawan; Muslikhin Hidayat
Jurnal Rekayasa Proses Vol 6, No 2 (2012)
Publisher : Departemen Teknik Kimia Fakultas Teknik Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (440.876 KB) | DOI: 10.22146/jrekpros.4697

Abstract

Potensi limbah biomassa dan bungkil jarak pagar cukup besar dan saat ini belum termanfaatkan. Kedua bahan tersebut dapat diolah menjadi bio-arang melalui proses pirolisis. Bio-arang dapat digunakan sebagai bahan bakar. Tar dan tepung tapioka digunakan sebagai perekat dalam pembuatan briket arang. Pada penelitian ini digunakan briket arang dengan fraksi massa bungkil jarak pagar 0, 25, 50, 75 dan 100%. Percobaan diawali dengan pembuatan arang, penghalusan arang dan pengayakan ukuran 35 mesh, pencampuran bahan baku dengan pelbagai komposisi dengan penambahan perekat (tapioka atau tar) kemudian ditekan dengan tekanan 1 kg/cm2. Selanjutnya, briket dianalisis kuat tekan, kadar air, kadar bahan mudah menguap, kadar abu, karbon terikat dan nilai kalor. Pembakaran briket dilakukan untuk mempelajari laju pembakaran dengan model matematis. Hasil analisis model matematis menunjukkan bahwa laju pembakaran briket pada komposisi bungkil jarak 75% dengan perekat tar, lebih cepat. Briket yang menggunakan perekat tar memberikan asap pada saat dibakar, sedang penggunaan perekat tapioka tidak manghasilkan asap. Model matematis yang diajukan dapat menggambarkan laju pembakaran briket. Parameter kinetik dan laju pembakaran dapat diperoleh dari model yang diajukan. Kata kunci: briket, bahan perekat, laju pembakaran, parameter kinetik The potential of biomass municipal waste and jatropha cakes is abundant, but has not been utilized. These materials can be converted into biobriquette via pyrolisis, which can be used as alternative fuel. Tar and tapioca adhesive were applied for the binder. In this study, briquettes with the mass fraction of jatropha cakes of 0, 25, 50, 75 and 100% were used. Research was done by performing carbonization, screening (35 mesh), mixing raw materials (municipal waste, jatropha cakes, tapioca adhesive and tar adhesive) and pressing at 1 kg/cm². Briquettes were then analyzed for compressive strengh, heating value, the moisture content, volatile matter, ash and fixed carbon. The combustion of the briquette was undertaken to study the rate of combustion. Mathematical model showed that the rate of combustion of the briquette with composition of municipal waste and jatropha oil cakes (25% : 75%) with adhesive tar was faster. Briquettes with adhesive tar produce smoke when burned, while briquettes with tapioca adhesive is smoke-free. Therefore it is more preferable. The proposed mathematical model describes the rate of combustion of the briquette well. The kinetic parameter of the rate of combustion were also obtained. Keywords: Briquette, adhesive materials, rate of combustion, kinetics parameter.

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