Peningkatan Kualitas Pelet Tandan Kosong Kelapa Sawit melalui Torefaksi Menggunakan Reaktor Counter-Flow Multi Baffle (COMB)

Abstract

Oil palm (Elaeis guineensis) empty fruit bunches (EFB) have not been utilized optimally. Currently, it is considered as a resource with low economic value. This biomass can be converted into bioenergy through a torrefaction process. Torrefaction is a mild pyrolysis at temperatures ranging between 200 and 300 °C, and it is generally performed under an inert atmosphere. The objective of this study was to evaluate the effects of torrefaction using Counter-Flow Multi Baffle (COMB) on the properties of oil palm EFB pellets. Torrefaction was conducted at 280 °C temperature with a residence time of 4 minutes. The results showed a decrease in the equilibrium moisture content and an increase in hydrophobicity after torrefaction using the COMB reactor. The change in the hygroscopic property could make the oil palm EFB pellet more stable against chemical oxidation and microbial degradation, hence self-heating and auto-ignition during storage could be prevented. The heating value of biomass increased after torrefaction. Torrefaction with the COMB reactor resulted in a heating value of 17.90 MJ/kg, which is comparable with the results of oxidative torrefaction (with longer residence time) of 18.28 MJ/kg. The results suggested that torrefaction using the COMB reactor could provide a great improvement in the quality of the bioenergetic properties of oil palm EFB pellets. However, the high ash content of the EFB pellets implied that the EFB pellets suitable for a small-scale application, but not yet for cofiring in power plants or as a feedstock for gasification.Keywords: Counter-Flow Multi Baffle; oil palm empty fruit bunches; renewable; torrefactionA B S T R A KTandan kosong kelapa sawit (Elaeis guineensis) belum dimanfaatkan secara optimal. Saat ini bahan tersebut masih dianggap sebagai sumber daya bernilai ekonomi rendah. Tandan kosong kelapa sawit (TKKS) dapat dikonversi menjadi bioenergi melalui proses torefaksi. Torefaksi merupakan proses pirolisis ringan pada suhu berkisar antara 200 dan 300 °C dan umumnya dilakukan di bawah kondisi inert. Penelitian ini bertujuan untuk mengetahui pengaruh torefaksi dengan reaktor Counter-Flow Multi Baffle (COMB) terhadap sifat-sifat pelet TKKS. Torefaksi dilakukan pada suhu 280 °C dengan waktu tinggal 4 menit. Hasil penelitian menunjukkan bahwa torefaksi menyebabkan penurunan kadar air kesetimbangan dan menjadi hidrofobik setelah torefaksi dengan reaktor COMB. Perbaikan sifat higroskopis dapat membuat pelet TKKS lebih stabil terhadap oksidasi kimia dan degradasi mikroba, sehingga pemanasan sendiri dan pembakaran spontan selama penyimpanan dapat dicegah. Nilai kalor biomassa meningkat setelah torefaksi. Torefaksi dengan reaktor COMB menghasilkan nilai kalor 17,90 MJ/kg, yang sebanding dengan hasil torefaksi oksidatif dengan waktu tinggal lebih lama, sebesar 18,28 MJ/kg. Hasil penelitian menunjukkan bahwa torefaksi dengan reaktor COMB dapat meningkatkan kualitas energi pelet TKKS. Tetapi pelet TKKS masih memiliki kadar abu yang tinggi sehingga biomassa hasil torefaksi belum sesuai untuk cofiring di pembangkit listrik atau sebagai bahan baku untuk gasifikasi.Kata kunci: Counter-Flow Multi Baffle; tandan kosong kelapa sawit; terbarukan; torefaksi

Effects of Torrefaction Temperature on the Characteristics of Betung (Dendrocalamus asper) Bamboo Pellets

“…Bamboo betung pellets that have been torrefied at temperatures of 200 °C, 240 °C and 280 ℃ did not change shape and did not expand at all until observation within 24 hours. This is in line with the research conducted by Hidayat et al (2020) by conducting torrefaction on OPEFB pellets that did not experience significant changes after soaking for 12 hours. Another study by Iryani et al (2019) also stated that the pellets of palm oil empty fruit bunches that were not torrefied completely disintegrated in the 30minute test, while the pellets that had been torreffied did not change even after 12 hours of testing, indicating that they are good for long-term storage.…”

“…Purnomo et al (2022) conducted torrefaction of oil palm empty fruit bunches (OPEFB) pellets with a rotary reactor at a temperature of 260 °C for 35 minutes and reported that the torrefaction process produced pellets with low water content and hydrophobic properties so that their moisture absorption power was low. Hidayat et al (2020) also reported that OPEFB pellets torrefied with a Counter-Flow Multi Baffle (COMB) reactor with temperatures between 230 -280 °C had hydrophobic properties, so that when the water resistance test was carried out, there were no changes in the pellet form even after 12 hours of observation. Siyal et al (2020) conducted a torrefaction study on rice husk and sawdust pellets at temperatures of 230 °C, 280 °C, and 300 °C with residence times of 15, 30, 45, 60, and 120 minutes and reported that the torrefied pellets were ideal for long-term storage due to its hydrophobic nature.…”

Valorization of corncob through torrefaction process

“…Hemicellulose will be decomposed first and followed by cellulose and lignin decomposition, respectively [10]. We have reported that torrefaction is able to improve fuel quality of biomass pellet made of oil palm empty fruit bunch [11][12][13][14][15]. The structure of the biomass changes in such a way that the material becomes brittle, and more hydrophobic.…”

Effects of Torrefaction Using COMB Dryer/Pyrolizer on the Properties of Rubberwood (Hevea brasiliensis) and Jabon (Anthocephalus cadamba) Pellets

“…Biomass feedstocks are considered a renewable resource. However, biomass has several weaknesses compared to fossil fuels because it has high moisture content, lower in energy value and bulk density, high in mineral and oxygen contents, highly hygroscopic, and non-uniform in physical that make it difficult to handle [8,9].…”