การศึกษาเตาฟลูอิไดซ์เบดแก๊สซิไฟเออร์แบบหมุนควงสำหรับเชื้อเพลิงชีวมวลแบบผง

Abstract

The purpose of this thesis was to design a small fluidized bed gasifier using palm cake as fuel. In beginning, the diameter of fluidized bed gasifier (D) was designed at D=20 cm. Then, the reactor of fluidized bed gasifier was studied numerically. A 3-D numerical model of the reactor was created using a commercial software of ANSYS Ver.15.0 (Fluent). The reactor was cylindrical, and the reactor length was 7.5D. The comparison of the effect of (1) single air inlet, (2) double air inlets and (3) air inlet positions on swirling flow in a fluidized bed gasifier were studied based on the same mass flow rate. The air inlet pipe was assembled tangentially to the bottom of the reactor. The geometry of the reactor bottom was conical. The results showed that swirling flow at the bottom of the reactor for the case of double inlets at position of Y/D=0.75 (Y/D=0 was the end of reactor bottom) was the most suitable. In the next step, a small pilot scale of bubbling fluidized bed gasifier was designed and fabricated. The feedstock was palm cake with the size was less than 10 mm. The mass feeding rate of feedstock was fixed at 0.05 kg/min, and flow rate of air was varied according to Equivalent Ratio (ER) at 0.03, 0.06, 0.19, 0.31, 0.49, 1.17, 1.43 and 2.64, respectively. Based on the result obtained in this study, it was found that the ER which can be provided for continuous operation was 0.19<ER≤1.17. For the syngas production study at the ER of 0.06 and 1.43 could not run continuously. Moreover, the result found that the syngas production was incombustible at ER=0.03 and 2.64. Finally, the thermal efficiency of the fluidized bed gasifier was evaluated, which Equivalent Ratio at ER = 1.17, 0.49 and 0.31. It can be concluded that the thermal efficiency of the reactor is increased.