Teknologi Distilasi Vakum-Adsorpsi pada Pengembangan Minyak Kelapa Sawit sebagai Isolator Listrik Cair

MUHAMAD MUSTANGIN, Prof. Dr, Ir. Bambang Purwantana, M.Agr; Prof. Dr. Ir. Chusnul Hidayat; Dr. Radi, S.T.P, M.Eng

2025 | Disertasi | S3 Mekanisasi/Teknik Pertanian

Penelitian ini bertujuan memperoleh isolator listrik cair dari CPO yang memiliki kadar air 2000 ppm, kadar asam 10 mg KOH/g, dan kadar kotoran 0,2%. Penelitian tahap 1 bertujuan mengetahui karakteristik CPO. Penelitian tahap 2 implementasi teknologi distilasi vakum adsorpsi terhadap CPO. Tahap ini melakukan degumming menggunakan distilasi vakum pada tekanan 15% – 65%vakum pada suhu 160oC-200oC dan penambahan asam fosfat, bleaching earth dan zeolit masing-masing sebesar 0,05%; 5%,dan 10% dilanjutkan dengan penambahan KOH sebesar 0,2?n vacuum spray drying. Penelitian tahap 3 melakukan uji isolator terhadap sifat panas sebagai pendingin dengan pengukuran konduktivitas panas dan panas spesifik. Penelitian pada tahap 4 melakukan desain dan pembuatan sebuah reaktor untuk memproduksi  CPO menjadi isolator listrik dengan mengevaluasi analisis kinerja teknis dan keekonomiannya. 

Hasil penelitian menunjukkan tekanan vakum dan suhu distilasi paling optimal diperoleh pada 51,9%vakum dan suhu 168,7oC selama 60 menit. Isolator memenuhi persyaratan IEC 62770 yaitu kadar air, tegangan tembus, viskositas kinematik dan keasaman masing - masing sebesar 176 ppm, 60 kV, 12,7 cSt, dan 0,01 mgKOH/g. Tekanan vakum memiliki efek yang signifikan pada kadar air, viskositas kinematik, dan keasaman, sedangkan suhu signifikan terhadap tegangan tembus dan keasaman. Tegangan tembus isolator diformulasikan sebagai  BDV=?0.0107 (suhu)2+3.9843 (suhu)?310.  Isolator dari CPO memiliki nilai panas spesifik  dan konduktivitas panas sebesar 2.6247 kJ/kg°C dan 0.2751 W/m2.C pada suhu 62.1oC, lebih tinggi dibandingkan minyak mineral. Hasil analisis dimensionless menunjukkan bahwa koefisien perpindahan panas prediksi memiliki nilai R2=0,99 sehingga sangat identik. Bilangan Nusselt berkorelasi langsung dengan bilangan Prandtl dengan pendekatan prediksi R² = 0,95, berdasarkan persamaan Nu = 10.801(Pr)0.0514 yang merupakan temuan penelitian ini sehingga dapat digunakan sebagai acuan desain CPO sebagai pendingin.

Reaktor untuk mengolah CPO menjadi isolator membutuhkan energi 2,1 kWh/liter CPO dengan rendemen 63%. Evaluasi ekonomi menunjukkan kelayakan implementasi industri dengan IRR 24,71%, NPV Rp 3,56 miliar, dan payback period 5,5 tahun.

Isolator cair untuk peralatan listrik umumnya menggunakan bahan berbasis minyak bumi yang tidak biodegradable sehingga diperlukan alternatif berbahan nabati. Standar isolator  nabati mengikuti IEC 62770 antara lain: tegangan tembus > 30 kV, kadar asam < 0>

Liquid insulators for electrical equipment are generally derived from petroleum-based materials that are not biodegradable. Therefore, alternative materials based on renewable sources such as vegetable oils are needed. The standard for vegetable-based insulators refers to IEC 62770, which includes the following specifications: breakdown voltage > 30 kV, acid number < 0>

This research aims to produce a liquid electrical insulator from CPO with a target moisture content of 2000 ppm, acid number of 10 mg KOH/g, and impurity level of 0.2%, starting with the characterization of CPO in Phase 1. In Phase 2, the implementation of vacuum distillation and adsorption technology was applied to CPO to transform it into an insulator. This phase involved degumming using vacuum distillation at 0–60% vacuum pressure and temperatures of 160–200°C, along with the addition of phosphoric acid (0.05%), bleaching earth (5%), and zeolite (10%), followed by KOH (0.2%) and vacuum spray drying.Phase 3 focused on testing the insulator's thermal properties as a coolant, including measurements of thermal conductivity and specific heat. In Phase 4, a reactor was designed and built to convert CPO into a liquid electrical insulator, followed by technical performance and economic feasibility analysis.

The results showed that the most optimal vacuum pressure and distillation temperature were 51.9% vacuum and 168.7°C for 60 minutes. The resulting insulator met IEC 62770 standards with a moisture content of 176 ppm, breakdown voltage of 60 kV, kinematic viscosity of 12.7 cSt, and acid number of 0.01 mg KOH/g. Vacuum pressure significantly affected moisture content, kinematic viscosity, and acidity, while temperature had a significant effect on breakdown voltage and acidity. The breakdown voltage (BDV) of the insulator was formulated as: BDV = ?0.0107(temperature)² + 3.9843(temperature) ? 310

The CPO-based insulator had a specific heat of 2.6247 kJ/kg°C and thermal conductivity of 0.2751 W/m²·°C at 62.1°C, which are higher than those of mineral oil. Dimensionless analysis showed that the predicted heat transfer coefficient had a very high correlation with the observed data (R² = 0.99). The Nusselt number was directly correlated with the Prandtl number, as expressed in the derived equation: Nu = 10.801(Pr)^0.0514. This equation is a key finding of the study and can serve as a design reference for using CPO as a cooling fluid. The reactor for processing CPO into an insulator requires 2.1 kWh/liter of CPO with a yield of 63%. Economic evaluation indicates industrial feasibility, with an IRR of 24.71%, NPV of IDR 3.56 billion, and a payback period of 5.5 years. 

Kata Kunci : CPO, isolator, tegangan tembus, koefisien transfer panas, Nusselt