PRARANCANGAN PABRIK BIOETANOL DARI LIMBAH PADAT TEPUNG TAPIOKA DENGAN KAPASITAS BAHAN BAKU 360.000 TON/TAHUN

Pabrik bioetanol dari limbah padat tepung tapioka yang mengandung 68% karbohidrat didirikan untuk memproduksi bahan bakar alternatif serta menanggulangi krisis energi dan terbatasnya cadangan bahan bakar fosil di dunia. Pabrik ini menggunakan proses hidrolisa enzim dan fermentasi. Proses produksi pabrik ini meliputi empat tahapan. Tahap pertama adalah proses pengolahan bahan baku (pre-treatment). Tahap kedua adalah proses hidrolisa enzimatik terdiri dari likuifikasi dengan menambahkan enzim amilase dan sakarifikasi dengan menambahkan enzim glukoamilase. Tahap ketiga adalah fermentasi menggunakan Saccaromycess cereviceae hingga mendapatkan bioetanol 11%. Tahap keempat yaitu distilasi dan dehidrasi dilakukan untuk menaikkan kadar bioetanol dari 11% menjadi 99,5%. Bentuk perusahaan yang direncanakan adalah Perseroan Terbatas (PT) dengan menggunakan metode struktur garis dan staf. Kebutuhan tenaga kerja untuk menjalankan perusahaan ini berjumlah 160 orang. Pabrik ini direncanakan berlokasi di Kecamatan Pekalongan, Kabupaten Lampung Timur, Propinsi Lampung dan beroperasi secara kontinyu dengan operasi 330 hari/tahun atau 24 jam/hari. Kapasitas produksi yang dihasilkan 93.202 kl/tahun bioetanol 99,5%. Bahan baku yang digunakan adalah limbah padat tepung tapioka sebesar 45.454,55 kg/hari. Kebutuhan air pada pabrik bioetanol ini meliputi: air sanitasi, air proses, air boiler, air pendingin, air recycle, air make up dan air untuk backwash yang masing-masing dibutuhkan sebesar 7.040 kg/jam, 58.441,56 kg/jam, 16.858,38 kg/jam, 209.026,48 kg/jam, 203.296,38 kg/jam, 33.227,79 kg/jam, dan 3.136,61 kg/jam. Sumber air pabrik Bioetanol ini berasal dari Sungai Way Seputih, Lampung Timur, Provinsi Lampung dan untuk memenuhi kebutuhan listrik diperoleh dari Perusahaan Listrik Negara (PLN) dan Generator dengan daya 3.791 kW. Dari hasil perhitungan analisa ekonomi diperoleh Break Event Point sebesar 65% dan Pay Out Time selama 6 tahun, maka disimpulkan Prarancangan Pabrik Bioetanol ini layak dilanjutkan ke tahap rancangan..Kata Kunci : bioetanol; limbah padat tepung tapioka; hidrolisa enzim; fermentasi

A lifecycle cost-driven system dynamics approach for considering additive re-manufacturing or repair in aero-engine component design

Aero-engine component design decisions should consider re-manufacturing and/or repair strategies and their impact on lifecycle cost. Existing design approaches do not account for alternative production technologies such as the use of additive manufacturing in life extension processes. This paper presents a modeling and optimization methodology for examining the impact of design decisions in the early development stage on component lifecycle cost during the in-service phase while considering the potential use of additive manufacturing in life extension strategies. Specifically, a system dynamics model is developed to assess different end-of-life scenarios. Finally, an optimization problem is formulated and solved to minimize lifecycle cost with respect to design variables related to remanufacturing

Ferroelastic Control of the Multicolor Emission from a Triply Doped Organic Crystal.

Emission from crystalline organic solids is often quenched by nonemissive energy-transfer deexcitation processes. While dispersion of fluorophores in polymers or other hosts has been used to enhance the emission intensity, this strategy results in randomization of guest orientation and optical losses at grain boundaries. Here, we report the doping of inherently nonemissive single crystals of anilinium bromide with three fluorescent organic molecules. The doping process equips the crystal with emission characteristics that tune from blue to deep orange. The emission intensity can be reversibly modulated by ferroelastic twinning, which causes the material to function as a multiemissive force sensor. This approach opens up new pathways in the manipulation of emissive properties in organic crystals and may have substantial implications for optoelectronic devices and sensors

Efficient occlusion of oil droplets within calcite crystals

It is well known that oil and water do not mix. Similarly, the incorporation of oil droplets within inorganic crystals is highly counter-intuitive because there is a large difference in surface energy for these two components. Nevertheless, herein we demonstrate the efficient occlusion of ∼250–500 nm oil droplets within 20–40 μm calcite crystals. These droplets are stabilized using various amphiphilic poly(methacrylic acid)–poly(n-alkyl methacrylate) diblock copolymer emulsifiers. Both copolymer concentration and diblock compositions affect the extent of occlusion, with optimized conditions producing calcite crystals containing up to 11% oil by mass. Moreover, compressive forces exerted by the growing crystals cause significant deformation of the oil droplets during occlusion. In principle, this protocol enables the incorporation of water-insoluble dyes or hydrophobic nanoparticles within calcite, which is a cheap, naturally-occurring and environmentally-benign mineral. The single crystal nature of this host lattice ensures efficient retention of such guests, while lowering the solution pH leads to triggered release via acid dissolution

Performance evaluation of wiper coated ceramic tool when hard turning tool steel

Hard turning is a technique that can be used as a substitute to grinding in the finishing operation for hardened steel (45 HRC and above). However, the use of this technique is limited due to the high cost of the cutting inserts. The developments of new cutting tools such as ceramic and CBN has made hard turning feasible. This project was undertaken to evaluate the performance of wiper coated ceramic tool (KY 4400) when turning hardened ASSAB DF-3 grade hardened steel with hardness 55 HRC. Various cutting speeds: 100, 155 and 210 m/min and various feed rates: 0.05, 0.125 and 0.2 mm/rev were used. The process was performed under dry cutting condition with a constant depth of cut of 0.2 mm. The machinablity responses that have been studied were tool life and surface roughness. This study shows that the effects of cutting speed and feed rate on the tool life are statistically significant. Specifically, at low cutting speed and low feed rate, wiper inserts are able to produce higher tool life compared to higher cutting speed and higher feed rate. Also this study shows that the effects of cutting speed and feed rate on the surface roughness are also statistically significant, specifically, at high cutting speed and low feed rate, wiper inserts are able to produce better surface finish. Tool life and surface roughness models were developed using the 3- level full factorial design. Analysis done showed that both mathematical models for tool life and surface roughness can be used to predict the machining response within the limits of cutting speed and feed rate that have been investigated

Keutamaan dan amalan bulan Rajab, Syakban dan Ramadhan/ Al-Handawi

168 hal.; 18 cm