Simulasi pengeringan batu bara muda dengan metode rangkaian pori pada kondisi isotermal

Anton Irawan, Indar Kustiningsih

Abstract


Simulation of low rank coal drying with pore network method in isothermal condition.

Indonesia has large coal reserve with most of them are low rank coal. Low rank coal has low energy content (< 4,800 kcal/kg) and high moisture content (> 25%). High moisture content of coal will make a problem for coal conversion processing to be a main energy source such as power plant  so that the moisture of coal must be removed from inside of coal. The moisture content in the coal can be removed by drying based on drying kinetic (drying rate). Drying kinetic is influenced by several variables such as hot fluid velocity and temperature, size and pore structure of material. In this model, sample of low rank coal are analyzed to obtain the data of pore size distribution. The size of pore were used 40 and 100 nm, the pore length was 100 nm. Four different pore structures were simulated by pore network modelling. From pore network simulation, the structure with large pore had long time for drying constant period, but the structure with small pore had short time for drying constant period.

Keywords: coal, drying, pore network, moisture, vapour diffusion.

 

Abstrak

Indonesia merupakan negara yang memiliki cadangan  batubara yang besar yang dapat digunakan sebagai sumber energi utama untuk industri, tetapi batubara yang dimiliki oleh Indonesia sebagian besar merupakan batubara muda yang memiliki kandungan energi yang rendah (< 4.800 kcal/kg) serta kandungan air yang tinggi (> 25%). Kandungan air batubara yang tinggi menyulitkan dalam proses konversi batubara untuk dijadikan sebagai sumber energi utama seperti pada sistem tenaga. Kandungan air dalam batubara dapat dikurangi dengan pengeringan dengan mengamati data kinetika pengeringan berupa laju pengeringan. Laju pengeringan batubara dipengaruhi oleh beberapa variabel antara lain kecepatan fluida panas, temperatur fluida panas, ukuran partikel yang dikeringkan serta struktur pori-pori dari partikel yang dikeringkan. Beberapa sampel batubara muda dianalisis strukturnya untuk mendapatkan data distribusi pori. Ukuran pori yang digunakan terdiri atas 2 macam yaitu 40 dan 100 nm serta panjang pori 500 nm.  Empat macam struktur pori disimulasikan dengan metode rangkaian pori. Dari simulasi rangkaian pori memperlihatkan bahwa ukuran pori yang besar akan memberikan waktu yang lebih lama untuk laju pengeringan tetap sedangkan struktur pori dengan  ukuran pori  kecil akan memberikan laju pengeringan tetap yang lebih pendek waktunya.

Kata Kunci: batubara, pengeringan, rangkaian pori, kandungan air, difusi uap.


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DOI: http://dx.doi.org/10.5614/jtki.2009.8.3.2

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