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Abstrak :
Salah satu struktur biaya dalam industri pembangkit tenaga listrik adalah bahan bakar. Harga bahan bakar minyak yang relatif tinggi telah menyebabkan biaya pembangkitan atau Cost of Electricity (COE) dari pembangkit yang menggunakan bahan bakar minyak seperti MFO menjadi tinggi, sehingga konsumsi bahan bakar MFO pada PLTU minyak diturunkan, hal tersebut mengakibatkan kapasitas listrik yang dibangkitkan oleh PLTU minyak cenderung turun setiap tahunnya. Alternatif bahan bakar yang lebih murah untuk PLTU minyak diperlukan, salah satu alternatif bahan bakar yang dapat digunakan adalah Coal Water Mixture (CWM), yaitu Coal Slurry berupa campuran antara batubara dan air serta zat aditif yang berbentuk suspensi kental yang dapat menggantikan minyak bakar berat MFO (Marine Fuel Oil) yang biasa digunakan di industriindustri yang menggunakan boiler sebagai penghasil uap untuk proses maupun untuk pembangkit listrik. Untuk dapat memanfaatkan CWM, modifikasi pada boiler pembangkit perlu dilakukan. Penelitian ini bertujuan menganalisa kelayakan pemanfaatan CWM pada PLTU serta batasan setiap parameternya agar prinsip "to produce electricity at the lowest possible cost" tetap terpenuhi. Analisis yang digunakan pada penelitian ini adalah metode probabilistik dengan simulasi Monte Carlo. Penelitian ini berhasil membuktikan bahwa pemanfatan CWM pada PLTU layak dilakukan dan dapat menurunkan biaya pembangkitan listrik pada PLTU.

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One of structure of cost on power generation industry is fuel. The price of oil fuel which relatively high has make the Cost of Electricity (COE) of the Power Generation that using MFO as the fuel has become higher too, therefore the consumption of MFO on the steam turbine power plant has been decreased every year, these situation has cause the electricity that being generate by Steam turbine power plants is getting lower every year. Fuel alternative which is more cheaper for steam turbine power plant is needed, one of the fuel alternative that can be used is Coal Water Mixture (CWM), a coal slurry that a mix of coal and water and additives in a form of suspension which can be used as a replacement of MFO (Marine Fuel Oil) in Indutries that have boiler to produce steam for process or for power generation. In order to utilize CWM, a modification on the boiler of the existing steam turbine power plant is required. This study has purpose to analyze the feasibility of CWM utilization on steam turbine power plant and the boundary of each parameters so the principle "to produce electricity at the lowest possible cost" can be achieved. In order to analyze each parameters this reasearch is using probabilistic methode by monte carlo simulation. This reasearch has proving that the utilization of CWM on steam turbine power plant is feasible to apply and it can reduce the power generation cost on steam turbine power pkant.

Abstrak :
The experiment of CWF preparation in laboratory scales have been studied using the kind and amount of additives and coal content as the process variables. Other variables such as particle size, time, and speed rate of stirring were kept constant. CWF with 45 wt % of dry solids, heating value of 5,475 BTU/lb, and stable without the evidence of sedimentation for 9 weeks have been obtained by using Carboxy Methyl Cellulose as the additive. Low coal content and heating value can be increased by hydrothermal process on the elevated temperature and pressure. By this process, CWF with dry solid of 55 wt % and heating value of 7,125 BTU/lb could be obtained.

Abstrak :
The rheological properties of CWF were studied in laboratory scale. A subbituminous coal was ground to a medium size of about 75 micrometer and mixed with water and small quantities of additives. Thr coal contents and types of chemical additives were varied to investigate effects on rheology behavior. Direct plots of viscosity and shear stress versus shear rate were obtained using a rotational viscometer. The results indicate that CWF exhibits non-Newtonian pseudoplastic rheological behavior. The viscosity increases rapidly with increasing coal concentration. The CWE of 55% coal content, obtained by adding a mixture of CMC and kaocoal, represents a practical slurry that shows good handling properties and good automization behavior. One of the most obvious factors that may have an effect on rhetorogical behavior of viscosity decreases when the temperature increases up to 50 degree Celcius but increase at 80 degree Celcius. However, the yeilded CWF stress point increases with increasing temperature up to 80 degree Celcius.