การผลิตเอทิลเอสเทอร์แบบต่อเนื่องจากส่วนกลั่นกรดไขปาล์มด้วยเครื่องปฏิกรณ์คลื่นเสียงอัลตราโซนิกชนิดแคลมป์ท่อ

Abstract

This research studied the ethyl ester production from palm fatty acid distillate (PFAD) using ultrasound clamps on a tubular reactor. The by-product from the refined palm oil (RPO) production process, PFAD was used as a raw material in the oleochemical industry to produce soap and grease. In Thailand the crude palm oils (CPO) are mainly used to produce biodiesel. According to seeking alternative feedstock, PFAD are cheaper than CPO, however, its property contain a high free fatty acid (FFA) content. Therefore, the FFA content in PFAD should be converted to ester using the acid-catalyzed esterification process. In the experiment equipment for first-step continuous process consisted of 5 meters of helical static mixer, and ultrasound clamp. The helical static mixer of 5 m in length was installed for premixing the PFAD, ethanol, and sulfuric acid. The ultrasound clamps has 16 units of ultrasonic clamps on a tubular reactor. Each unit was operated at a frequency of 20 kHz with 400W power. For optimizing the ester purity in each step, the central composite design (CCD) in design the experiments and the response surface methodology (RSM) were used to analyze the results. For first step esterification, three independent parameters were ethanol (19.8-70.2 vol.%), sulfuric acid (0.6-7.4 vol.%), and length of ultrasonic tubular reactor (100-700 mm). It was found that the first step recommended condition was 46.5 vol.% ethanol, 0.7 vol.% sulfuric acid, and 400 mm length of ultrasonic tubular reactor. As a result, 66.68 wt.% ester purity and 135.25 vol.% yield were achieved under suitable condition. The first-step esterified oil was then used as feedstock of second-step esterification process. Three independent parameters of second-step processes were ethanol (26.4-93.6 vol.%), sulfuric acid (0.6-7.4 vol.%), and length of ultrasonic tubular reactor (100-700 mm). It was found that the high purity of 95.32 wt.% and 135.41 vol.% yield were achieved under the second step recommended condition was 57.0 vol.% ethanol, 2.1 vol.% sulfuric acid, and 400 mm length of ultrasonic tubular reactor. Subsequent, the second-step esterified oil was used to produce ethyl ester with third- step transesterification. For the design experiment, two independent parameters were ethanol (2.9-17.1 vol.%), and potassium hydroxide (1.2-6.8 g.L1). It was found that the maximum ethyl ester purity was 98.15 wt.%, and yields was 64.87 vol.% PFAD under the optimum condition was 14.6 vol.% ethanol, and 3.9 g.L1 potassium hydroxide. After biodiesel purification by washing method, 98.15 wt.% of ethyl ester purity and 59.13 vol.% yields of ethyl ester were obtained. In conclusions, the total chemical consumptions were 118.1 vol.% ethanol, 2.8 vol.% sulfuric acid, 3.9 g.L1 potassium hydroxide and total residence time was 40.1 s using three step process. When consideration of production costs, 45.93 THB.L1 of chemical cost and 0.81 THB.L-1 electricity cost were consumed in continuous three step process.