Integrated Production-Distribution Planning with Considering Preventive Maintenance

The preventive maintenance activity is important thing in production system especially for a continuous production process, for example in fertilizer industry. Therefore, it has to be considered in production-distribution planning. This paper considers the interval of production facility’s preventive maintenance in production-distribution planning of multi echelon supply chain system which consists of a manufacturer with a continuous production process, a distribution center, a number of distributors and a number of retailers. The problem address in this paper is how to determine coordinated productiondistribution policies that considers the interval of production facility’s preventive maintenance, and customer demand only occurred at retailers and it fluctuates by time. Based on model of Santoso, et al. (2007), using the periodic review inventory model and a coordinated production and replenishment policies that are decided by central planning office and it must be obeyed by all entities of multi-echelon supply chain, the integrated production-distribution planning model is developed to determine the production and replenishment policies of all echelon in the supply chain system in order to minimize total system cost during planning horizon. Total system cost consists of set-up/ordering cost, maintenance cost, holding cost, outsourcing cost and transportation cost at all of entities. With considering preventive maintenance and there is one production run over the planning horizon, the replenishment cycle at distribution center, distributors and retailers that are found out are greater than the basic model. Also, the multiplication of replenishment cycle at distribution center in production cycle that is found out is greater than the basic model but the multiplication of replenishment cycle at retailers in its distributor are smaller than the basic model

Modified Two-Step Dimethyl Ether (DME) Synthesis Simulation from Indonesian Brown Coal

A theoretical study was conducted to investigate the performance of dimethyl ether (DME) synthesis from coal. This paper presents a model for two-step DME synthesis from brown coal represented by the following processes: drying, gasification, water-gas reaction, acid gas removal, and DME synthesis reactions. The results of the simulation suggest that a feedstock ratio of coal : oxygen : steam of 1 : 0.13 : 0.821 produces the highest DME concentration. The water-gas reactor simulation at a temperature of 400°C and a pressure of 20 bar gave the ratio of H2/CO closest to 2, the optimal value for two-step DME synthesis. As for the DME synthesis reactor simulation, high pressure and low temperature promote a high DME concentration. It is predicted that a temperature of 300°C and a pressure of 140 bar are the optimum conditions for the DME synthesis reaction. This study also showed that the DME concentration produced by the two-step route is higher than that produced by one-step DME synthesis, implying that further improvement and research are needed to apply two-step DME synthesis to production of this liquid fuel

Modified Two-Step Dimethyl Ether (DME) Synthesis Simulation From Indonesian Brown Coal

A theoretical study was conducted to investigate the performance of dimethyl ether (DME) synthesis from coal. This paper presents a model for two-step DME synthesis from brown coal represented by the following processes: drying, gasification, water-gas reaction, acid gas removal, and DME synthesis reactions. The results of the simulation suggest that a feedstock ratio of coal : oxygen : steam of 1 : 0.13 : 0.821 produces the highest DME concentration. The water-gas reactor simulation at a temperature of 400°C and a pressure of 20 bar gave the ratio of H2/CO closest to 2, the optimal value for two-step DME synthesis. As for the DME synthesis reactor simulation, high pressure and low temperature promote a high DME concentration. It is predicted that a temperature of 300°C and a pressure of 140 bar are the optimum conditions for the DME synthesis reaction. This study also showed that the DME concentration produced by the two-step route is higher than that produced by one-step DME synthesis, implying that further improvement and research are needed to apply two-step DME synthesis to production of this liquid fuel

Photocatalytic Simulation of Phenol Waste Degradation Using Titanium Dioxide (TiO2) P25-Based Photocatalysts

Phenol waste treatment is vital in industries such as polymer production, coal gasification, refinery, and coke production. Photocatalytic technology using semiconductor materials offers an effective and ecofriendly approach to degrade phenol. TiO2 P25 is a widely used photocatalyst, known for its cost-effectiveness, favorable optical and electronic properties, high photoactivity, and photostability. The PHOTOREAC application, a recently developed MATLAB-based software, simulates the degradation of phenol using visible light. A study that combines existing literature and research revealed that pH significantly influences photocatalytic activity, with an optimum pH of 7 for TiO2 P25-mediated phenol degradation. The recommended photocatalyst concentration ranged from 0 to 10 g/L for reactor volumes between 25 and 60 mL, and from 0 to 5 g/L for 100-mL reactors. Phenol wastewater volume and light intensity also impact degradation efficiency. Adequate oxygen supply, achieved through bubbling and mixing, is essential for the formation of radical compounds. The Ballari kinetic model proved to be the most suitable for phenol degradation with TiO2 P25. Thus, by combining PHOTOREAC simulations with experimental data, the treatment process could be optimized to achieve higher degradation efficiency and estimate the treatment time for specific waste degradation levels. This study contributes to the advancement of phenol waste treatment and the development of improved photocatalytic wastewater treatment technologies

Photocatalytic Simulation of Phenol Waste Degradation Using Titanium Dioxide (TiO2) P25-Based Photocatalysts

Phenol waste treatment is vital in industries such as polymer production, coal gasification, refinery, and coke production. Photocatalytic technology using semiconductor materials offers an effective and ecofriendly approach to degrade phenol. TiO2 P25 is a widely used photocatalyst, known for its cost-effectiveness, favorable optical and electronic properties, high photoactivity, and photostability. The PHOTOREAC application, a recently developed MATLAB-based software, simulates the degradation of phenol using visible light. A study that combines existing literature and research revealed that pH significantly influences photocatalytic activity, with an optimum pH of 7 for TiO2 P25-mediated phenol degradation. The recommended photocatalyst concentration ranged from 0 to 10 g/L for reactor volumes between 25 and 60 mL, and from 0 to 5 g/L for 100-mL reactors. Phenol wastewater volume and light intensity also impact degradation efficiency. Adequate oxygen supply, achieved through bubbling and mixing, is essential for the formation of radical compounds. The Ballari kinetic model proved to be the most suitable for phenol degradation with TiO2 P25. Thus, by combining PHOTOREAC simulations with experimental data, the treatment process could be optimized to achieve higher degradation efficiency and estimate the treatment time for specific waste degradation levels. This study contributes to the advancement of phenol waste treatment and the development of improved photocatalytic wastewater treatment technologies

Studi Pengaruh Konsentrasi Katalis ZnO untuk Degradasi Limbah Palm Oil Mill Effluent (POME) Menggunakan Teknologi Fotokatalitik

Indonesia is among the world’s largest palm oil market countries leading to significant growth in the domestic palm oil industry. However, the increase in palm oil trading has also led to a rise in the production of waste known as Palm Oil Mill Effluent (POME). Currently, the majority of factories use open ponds for POME processing, but this method is considered ineffective for treating POME. To address this issue, researchers are exploring photocatalytic technology, which utilizes light energy (UV, visible, sunlight) to produce radical compounds that act as oxidizing agents for POME degradation. In this study, ZnO was employed as a catalyst. The XRD and UV-vis DRS characterizations confirmed that ZnO had a hexagonal wurtzite crystal structure with a band gap energy of 3,22 eV. The photocatalytic activity test results revealed that using 0.5 g/L ZnO catalyst proved to be efficient in degrading organic content in POME. The percentage of chemical oxygen demand (COD) degradation reached 22.85%, color degradation reached 48.53% and the reaction rate kinetics constant of COD degradation was at 2.6´10-3 min-1.Indonesia merupakan salah satu negara center market kelapa sawit terbesar di dunia sehingga perkembangan industri kelapa sawit dalam negeri tumbuh dengan sangat pesat. Namun, meningkatnya aktivitas perdagangan kelapa sawit berdampak terhadap meningkatnya limbah yang dihasilkan yaitu Palm Oil Mill Eflluent (POME). Mayoritas pabrik saat ini masih menggunakan open pond sebagai teknologi pengolahan POME, namun penggunaan teknologi ini dinilai belum efektif untuk pengolahan POME. Fotokatalitik merupakan teknologi berbasis energi sinar (UV, tampak, sinar matahari) untuk menghasilkan senyawa radikal yang dimanfaatkan sebagai agen pengoksidasi limbah POME. Katalis yang digunakan pada penelitian ini adalah ZnO. Berdasarkan hasil karakterisasi XRD dan UV-vis DRS, struktur kristal dari ZnO adalah hexagonal wurtzite dengan energi celah pita sebesar 3,22 eV. Berdasarkan hasil uji aktivitas degradasi fotokatalitik limbah POME, diperoleh bahwa penggunaan katalis ZnO dengan konsentrasi 0,5 g/L dinilai cukup efisien untuk mendegradasi kandungan organik pada limbah POME dengan persentase reduksi chemical oxygen demand (COD) mencapai 22,85%, warna 48,53% dengan konstatnta laju reaksi COD (k) adalah 2,6´10-3 menit-1

Biosolubilisasi Lignit Mentah Hasil Iradiasi Gamma dan oleh Trichoderma asperellum

Biosolubilisasi batubara adalah proses mengubah padatan batubara menjadi bahan bakar cairdengan bantuan mikroorganisme. Tujuan dari penelitian ini adalah untuk membandingkanbiosolubililisasi batubara lignit hasil iradiasi gamma (10 kGy) dengan lignit mentah olehkapang terseleksi Trichoderma asperellum. Perlakuan terdiri dari A (MSS + lignit iradiasigamma 5% + T. asperellum) dan B (MSS + lignit mentah 5% + T. asperellum) dengan kultursub-merged. Parameter yang diukur adalah pH medium, kolonisasi, analisis logam denganAnalisis Aktivasi Netron (AAN) dan produk biosolubilisasi dengan menggunakanspektrofotometer UV-Vis 250nm and 450nm. Sampel yang memiliki tingkat biosolubilisasitertinggi akan dianalisis lanjut dengan FTIR dan GCMS. Hasil penelitian menunjukkan bahwatingkat biosolubilisasi kapang T. asperellum pada lignit mentah (B) lebih tinggi dibandingkandengan lignit iradiasi gamma (A) berdasarkan karakteristika produk biosolubilisasi batubaralignit yang meliputi analisis senyawa fenolik dan aromatik terkonjugasi. Analisis logammenunjukkan terjadinya pengurangan kandungan logam batubara saat proses biosolubilisasi.Analisis produk biosolubilisasi dengan FTIR memperlihatkan kemiripan spektra pada keduaperlakuan. Analisis GCMS menunjukkan kisaran jumlah rantai karbon yang terdeteksi padaproduk biosolubilisasi untuk perlakuan A dan B adalah C6 — C35 dan C10 — C35 yang didominasioleh senyawa asam aromatik, alifatik dan fenil ester. Produk biosolubilisasi pada keduaperlakuan dapat digunakan sebagai pengganti minyak bumi dan direkomendasikan untukdilakukan deoksigenasi sehingga kualitas bahan bakar dapat ditingkatkan. Biosolubilization is a promising technology for converting solid coal to liquid oilby addition of microorganism. Aim of this research is to compare between gamma irradiatedlignite (10 kGy) with raw lignite in biosolubilization by selected fungi Trichoderma asperellum.Treatments were A (MSS + gamma irradiated lignite 5% + T. asperellum) and B (MSS + rawlignite 5% + T. asperellum) with sub-merged culture. There were two parameters observed i.e.biosolubilization product based on absorbance value at 250nm and 450nm and metal analysis byneutron activation analysis (NAA). The highest biosolubilization will be analyzed by FTIR andGCMS. The results showed that biosolubilization of raw lignite (B) was higher than sterilizedlignite (A) based on absorbance value at 250nm and 450nm. The metal of lignite was decreasedafter incubation. FTIR analysis showed that both of treatment had similar spectra onbiosolubilization products. GCMS analysis showed that both of treatment had differentnumber of hydrocarbon, i.e. C6 — C35 (A) and C10 — C35 (B) and dominated by aromatic acids aliphatic and phenylethers. Both of treatment product had the potency as oil substituted butits recommended to deoxygenate for higher quality

Genetic Algorithm for Solving the Integrated Production-Distribution-Direct Transportation Planning

This paper proposes a model of integrated production, distribution and transportation planning for 4-echelon supply chain system that consists of a manufacturer using a continuous production process, a distribution center, distributors and retailers. By means of time-dependent demand at all retailers and direct transportation from one echelon to its successive echelons, the purpose of this paper is to determine production/replenishment and transportation policies at manufacturer, distribution center, distributors and retailers in order to minimize annually total system cost. Due to the proposed model is classified as a mixed integer non-linear programming so it is almost impossible to solve the model using the exact optimization methods and a lot of time is needed when the enumeration methods is applied to solve only a small scale problem. In this paper, we apply the genetic algorithm for solving the model. Using integer encoding for constructing the chromosome, the best solution is going to be searched. Compared with enumeration method, the difference of the result is only 0.0594% with the consumption time is only 0.5609% time that enumeration methods need

Simulasi Dinamik Pengoperasian Kompresor Sentrifugal Multitahap untuk Mengatasi Penurunan Tekanan Sumur Gas

Currently, the utilization of natural gas as an energy source needs to be optimized due to its increasing demand. The utilization of natural gas to produce LNG requires a high-pressure operating system of 1000 psig. The installation of a multistage centrifugal compressor unit is essential to maintain the operating pressure when there is a decrease in the feed gas pressure from natural gas wells. This study aims to predict the performance of the compressor that would be used and optimize the compressor operating conditions to satisfy the specifications of the gas selling pressure. In this study, simulations were conducted on how to maintain the stability of the feed operating pressure in the case of a drop in the gas source pressure from 1000 psig to 200 psig over a period of 15 years. Herein, the gas flow rate under normal conditions is 80 MMSCFD with a gas flow rate variation under surge (minimum) and maximum conditions of 110% × normal flow rate. By using the compressor map prediction curve and Hysys simulation under dynamic conditions, the compressor performance can be analyzed and then used for process requirements in the field.Dewasa ini pemanfaatan gas alam sebagai sumber energi perlu dioptimalkan karena kebutuhannya yang meningkat. Pemanfaatan gas alam untuk memproduksi LNG memerlukan sistem operasi bertekanan tinggi yaitu 1000 psig. Pemasangan unit kompresor sentrifugal multitahap mutlak diperlukan untuk dapat menjaga tekanan operasi saat terjadi penurunan tekanan gas umpan pada sumur-sumur gas alam. Penelitian ini bertujuan untuk memprediksi kinerja kompresor yang akan digunakan serta mengoptimasi kondisi operasi kompresor agar memenuhi spesifikasi tekanan gas jual. Dalam kajian ini, dilakukan simulasi bagaimana mempertahankan kestabilan tekanan operasi umpan untuk kasus penurunan tekanan sumber gas dari 1000 psig hingga 200 psig dalam kurun waktu 15 tahun. Laju alir gas pada kondisi normal adalah 80 MMSCFD dengan variasi laju gas pada kondisi surge (minimum) dan kondisi maksimum sebesar 110% × laju alir normal. Dengan menggunakan kurva prediksi peta kompresi dan simulasi Hysys pada kondisi dinamik, kinerja kompresor dapat dianalisis dan kemudian dapat digunakan untuk kebutuhan proses di lapangan

Karakterisasi Produk Biosolubilisasi Lignit Oleh Kapang Indigenus Dari Tanah Pertambangan Batubara Di Sumatera Selatan

Characterization of Lignite Biosolubilization Products by Indigenous Moulds from Soil ofCoal Mining in South Sumatera. Biosolubilization of coal is a potential technology of convertingsolid coal to liquid fuel and chemicals at ambient condition. Our previous research hassuccessfully isolated four moulds from soil at coal mining - South Sumatera and has potency aslignite biosolubilization agent, i.e. T1, T2, T4, T5. The objective of this research was to characterizeof lignite biosolubilization products by four isolates. The method used was sub-mergedculture. Cultivation medium was MSS+ (minimal salt + sucrose 0,1% + yeast extract 0,01% +lignite 5 %). Incubation was conducted at room temperature for 28 days. The result showed thatall indigenos moulds have different ability in lignite biosolubilization. The highestbiosolubilization occurred after 7 days of incubation belonging to T1 isolate. However, GC-MSanalysis showed the largest percentage of hydrocarbon compound which equivalent to gasolineand diesel was T5 after 7 days of incubation