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Abstrak :
Pembakaran spontan pada batubara merupakan salah satu masalah besar bagi industri penambangan dan pemanfaat batubara. Pembakaran spontan pada batubara di pengaruhi oleh banyak faktor , baik faktor internal maupun eksternal. Salah satu faktor eksternal adalah kelembaban relatif. Di indonesia yang beriklim tropis dan mempunyai kelembaban udara cukup tinggi faktor ini sangat penting. Metode pengujian yang digunakan untuk penelitian ini adalah metode oksidasi adiabatik. Metode ini beroperasi pada temperatur awal sekitar 40oC, sehingga mensimulasikan kondisi mendekati nyata seperti yang terjadi dilapangan. Secara khusus penelitian ini membahas pengaruh kelembaban relatif pada laju peningkatan temperatur batubara dan kondisi tercapainya pembakaran spontan.

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Spontaneous combustion of coals cause one of big problem for coal mining industry and coal user. Spontaneous combustion influences a lot of factors, internal also external factors. One of external factor is relative humidity. In Indonesian which have the tropical climate and have high air humidity enough this factor of vital importance. An adiabatic oxidation testing method used for this experiment. This method operate on initial temperature 40 oC, that condition of simulation near reality such as those which happened on the field. Special this research study influence of relative humidity on temperature rises and ignited state.

Abstrak :
Cadangan batubara Indonesia sebagian besar lebih dari 60 merupakan batubara dengan kalori rendah dan sedang yang dikenal dengan batubara peringkat rendah. Pada skenario KEN, pertumbuhan kebutuhan batubara rata-rata sebesar 5,1 dimana pada tahun 2025 kebutuhan batubara mencapai 37 juta Toe dan meningkat hingga mencapai 116 juta Toe di tahun 2050.Pemanasan mandiri self-heating dan pembakaran spontan spontaneous combustion batubara telah menjadi masalah serius di industri batubara. Kebakaran Batubara dan gambut dari Indonesia sering terjadi akibat kebakaran hutan di dekat singkapan.Kegiatan utama dari studi saat ini adalah melakukan eksperimen terhadap batubara peringkat rendah Indonesia dengan menggunakan metode uji yang berbeda TG-DTA, metode crossing point / CPT dan metode adiabatik . Selain itu, dilakukan pemodelan dengan piranti lunak COMSOL Multiphysics dan validasi dengan data eksperimen serta studi parametrik.Hasil pemodelan menunjukkan hasil yang berkesesuaian dengan data hasil ekperimen dengan penyimpangan temperatur sekitar 0,9 untuk CPT dan 1,5 untuk reaktor adiabatik.Dari studi parametrik di dapatkan bahwa porositas tumpukan dan konsentrasi oksigen memiliki efek yang cukup besar terhadap perilaku pembakaran spontan dan perlu mendapatkan perhatian dalam upaya untuk mencegah pembakaran spontan.Pemodelan dan Simulasi dapat digunakan sebagai alatbantu yang efektif untuk mencegah dan mencari solusi permasalah pembakaran spontan pada aplikasi di lapangan.

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Indonesia's coal reserves mostly over 60 are low to moderate calorie coal known as low rank coal. In the KEN scenario, the average coal demand growth of 5.1 is where in 2025 the demand for coal reaches 37 million toe and increases to 116 million toe in 2050.Self heating and spontaneous combustion of coal have become a serious problem in the coal industry. Coal and peat fires from Indonesia often occur due to forest fires near the outcrop.The main activity of the current study is to conduct experiments on Indonesia's low rank coal using different test methods TG DTA, crossing point CPT method and adiabatic method. In addition, modeling with COMSOL Multiphysics software and validation with experimental data and parametric studies were performed.The modeling results show results that are compatible with experimental data with a temperature drift of about 0.9 for CPT and 1.5 for adiabatic reactors. From the parametric study it was found that the porosity of the pile and the oxygen concentration had a considerable effect on spontaneous combustion behavior and needed to get attention in an effort to prevent spontaneous combustion.Modeling and Simulation can be used as an effective tool to prevent and solve spontaneous combustion problems in field applications.

Abstrak :
In this study, modeling of the crossing point temperature (CPT) phenomenon in the low-temperature oxidation of coal was carried out using COMSOL Multiphysics®. Low-temperature oxidation can lead to spontaneous combustion of coal stockpiles. The CPT phenomenon was modeled with the kinetics data obtained from a prior laboratory experimental study. The coupling of the heat-transfer phenomenon through conduction and convection determined the thermal evolution model. In this case, coal received the initial heat of the oven temperature increases. As the coal temperature rose, the heat generated from oxidation was released into the environment via conduction and convection. Meanwhile, oxidation products and oxygen were transferred by convection and diffusion. The effects of moisture and the humidity were not considered. The outcomes of modeling were validated through comparison with the results of experimental tests, and the modeling result agreed well with the experiment tests, with temperature deviations of about 0.9%. The effects of airflow rate, oxygen concentration, porosity, and the initial temperature on low-temperature coal oxidation were also examined.

Abstrak :
In this study, modeling of the crossing point temperature (CPT) phenomenon in the low-temperature oxidation of coal was carried out using COMSOL Multiphysics®. Low-temperature oxidation can lead to spontaneous combustion of coal stockpiles. The CPT phenomenon was modeled with the kinetics data obtained from a prior laboratory experimental study. The coupling of the heat-transfer phenomenon through conduction and convection determined the thermal evolution model. In this case, coal received the initial heat of the oven temperature increases. As the coal temperature rose, the heat generated from oxidation was released into the environment via conduction and convection. Meanwhile, oxidation products and oxygen were transferred by convection and diffusion. The effects of moisture and the humidity were not considered. The outcomes of modeling were validated through comparison with the results of experimental tests, and the modeling result agreed well with the experiment tests, with temperature deviations of about 0.9%. The effects of airflow rate, oxygen concentration, porosity, and the initial temperature on low-temperature coal oxidation were also examined.

Abstrak :
ABSTRAK Batu bara merupakan bahan tambang yang paling sering digunakan dalam kehidupan manusia dan Indonesia menjadi salah satu negara pengekspor batu bara terbesar di dunia. Akan tetapi batu bara jika disimpan dengan jangka waktu tertentu dapat terbakar sendiri dan akan mengurangi nilai jual batu bara. Beberapa penelitian telah dilakukan untuk mengurangi swabakar atau pembakaran spontan pada batu bara, mulai dari pemadatan pada stockpile, menyemprotkan batu bara dengan cairan kimia seperti Outodust/Vinasol, Focustcoat, Hydrosol atau Suppressol, pemeriksaan temperatur secara, volcano trap dan pembuatan parit. Penelitian ini mempelajari mencegah pembakaran spontan pada batu bara yang berada dalam tongkang saat pengiriman. Batu bara yang digunakan dalam penelitian diambil dari Kalimantan, Indonesia. Selama pengujian di laboratorium air dialirkan melalui pipa baja dengan memvariasikan kecepatan air untuk mendapatkan temperatur terendah batu bara yang bisa diturunkan. Air dialirkan dengan kecepatan 0.5 mL/s, 0.7 mL/s dan 0.9 mL/s. Pada percobaan ini dilakukan dua pendekatan, yaitu mengalirkan air secara terus menerus dan diberhentikan setiap 20 menit dan dialirkan lagi jika temperatur batu bara sudah mencapai temperatur tertentu. Hasil penelitian menunjukan semakin cepat air mengalir bukan berarti semakin turun temperatur batu bara. Lama waktu dalam pengaliran air mempengaruhi sebebrapa turun temperatur batu bara.

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ABSTRACT
Coal is the most commonly used as a fuels for power generaion sector and Indonesia is one of the largest coal exporting countries in the world. However, if a coal stored for a certain period of time, they can burn itself and it will reduce the selling price of coal. Several studies have been done to reduce self ignition or spontaneous combustion of coal, from solidification to stockpiles, spraying coal with chemical liquids such as Outodust Vinasol, Focustcoat, Hydrosol or Suppressol, temperature checks, volcano trap and trenching. This study studied preventing spontaneous combustion on coal in a barge during delivery. The coal used in the study was taken from Kalimantan, Indonesia. During testing in the laboratory water is flowed through steel pipes by varying the speed of water to obtain the lowest possible coal low temperature. Water flowed at a rate of 0.5 mL s, 0.7 mL s and 0.9 mL s. In this experiment, two approaches are carried out, continuous flow of water and discharged every 20 minutes and flowed again if the coal temperature has reached a certain temperature. The results show the faster water flow does not mean the falling temperature of coal. The length of time in the how fast the water flow affact how low the temperature of the coal.

Abstrak :
ABSTRAK Proses transportasi batu bara di sektor industri banyak menggunakan kapal tongkang yang dapat memakan waktu transportasi yang cukup lama. Panjangnya durasi transportasi batu bara dapat menyebabkan pembakaran spontan akibat panas yang dihasilkan oleh timbunan batu bara. Batu bara kualitas rendah seperti sub-bituminus dan lignit cenderung lebih mudah untuk terbakar sendiri. Fenomena pembakaran spontan batu bara merupakan peristiwa yang kompleks yang melibatkan banyak elemen, baik secara intrinsik seperti kadar air dan ukuran partikel, maupun faktor ekstrinsik yaitu temperatur ambient, kecepatan angin, tekanan udara, dan lainnya. Suatu model inovatif dari kapal tongkang dirancang untuk dapat mengontrol terjadinya pembakaran spontan batu bara menggunakan air yang dialirkan melalui pipa tembaga yang ditempatkan di dalam timbunan batu bara. Menurut percobaan yang telah dilakukan pada skala laboratorium, ditemukan bahwa temperatur batu bara dapat diturunkan, dengan penurunan temperatur mencapai 150 C menggunakan metode ini. Penerapan metode ini pada kapal tongkang, akan menghasilkan suatu model kapal tongkang baru di masa depan. Ruang kargo pada kapal tongkang akan dibagi menjadi empat kompartemen dimana pada setiap kompartemen terdapat dua rangkaian pipa tembaga. Air akan dialirkan melalui pipa tembaga tersebut, sehingga dapat menyerap panas yang dilepaskan oleh batu bara menyebabkan temperatur batu bara turun hingga di bawah temperatur kritisnya untuk mencapai pembakaran spontan.

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ABSTRACT
Coal for industrial sectors mainly uses barge for its shipment that may take long time to transport. The long duration of coal shipment can lead to self heating that could progressed to spontaneous combustion of coal. This still remains a great challenge in coal industry. The low rank coal such as sub bituminous and lignite are more prone to combust spontaneously. The self heating phenomenon is a complex event which involve many factors such as moisture content, particle size, wind speed, ambient temperature, barometric pressure and others. An innovative model of barge was designed to control the spontaneous combustion of coal using a flowed water through a coiled pipe which is placed inside a coal pile. From a laboratory scale experiment, it is found that the temperature of coal can be lowered up to 150 C using this method. Applying this experiment to a full scale barge, would introduce a new model of barge in the future. The cargo space of barge is divided to four compartments, which each compartment has two sets of coiled pipe. Water is flowed inside the pipe to transfer heat generated by the coal pile, which can reduce the temperature of coal below its critical temperature for spontaneous combustion.