UTILIZATION OF COAL GASIFICATION UNIT IN A TEA DRYING PLANT

• Main Author: Susandy Sanjaya (NIM 230 04 013), Ari
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/7307
• Institution: Institut Teknologi Bandung

Abstract : <br /> <br /> <br /> Anticipating the increase in oil price, the management of a tea plantation and drying plant has considered in substituting its oil consumption with producer gas obtained from gasification of low calorific coal or biomass. A gasification unit having a designed capacity of about 120 kg/h had been installed and the producer gas (gaseous fuel obtained from gasification) was intended for substitute of oil burner with an original rate of 70 L/h. <br /> <br /> <br /> The gasification unit consisted of a downdraft fixed bed gasifier, gas cooling and cleaning systems. This gasifier has a throat diameter of 40 m and a reduction zone diameter of 80 cm. Low calorific value coals (4500 kcal/kg) and wood wastes (4000 kcal/kg) have been used as feedstock. The gasification unit could be operated as long as 8 hours without refueled, since the feedstock hopper on the top of gasifier has a capacity of about 1000 kg. <br /> <br /> <br /> Combustion of producer gas produced a pale-blue flame, probably due to a lower calorific value of the producer gas or too much excess air. Temperature of heating-air heated by combustion of this producer gas was only up to 96 C. To achieve the target temperature of 102 C, a small oil burner must be operating at a rate of about 15 L/h. Thus, the oil replacement was about 78%. <br /> <br /> <br /> Combustion characteristic of producer gas had been studied independently in our laboratory, using a model gas consisted of (mol fraction): 23.53%CO, 18.35% H2, 2.17% CH4, 10.77% CO2, dan 45.18% N2. This combustion test showed that stable flame could be maintained at a linear velocity of air-gas mixture in the range of 1,5-2,4 m/s This stable flame could also maintained at an air to fuel ratio in the range of 0,71-6,90 mole/mole (stoichiometric air to fuel ratio 0,93 mole/mole). <br /> <br /> <br /> Based on the above mentioned experimental flame stability and burner heat load of 1200000 kJ/h, diameter of gas producer burner should be 19 cm, while the existing gas burner had a diameter of 12 cm. This might be another reason why the tea drying air temperature could not be achieved on the combustion of solely producer gas. <br />