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PRE FACTORY DESIGN

LIGNOSELLULOSE FRACSINATION OF OPEFB USING STEAM EXPLOSION METHOD

A. Description

Utilization of renewable natural resources, today, through the application of new and sophisticated chemical process technologies or through modification of existing processes provides enormous new results and opportunities. Lignocellulosic is one of the renewable resources, biomass, whose availability is very abundant.

Currently, biomass such as firewood, agricultural waste is generally used as fuel for cooking, fuel for boilers and other thermal processes in small and medium-sized industries. However, it can also be converted into gaseous and liquid fuels such as in the form of ethanol and biodiesel through a fermentation process or a reaction process.

As the world’s largest producer of palm oil, the potential availability of biomass in the form of empty oil palm fruit bunches (TKKS) is also abundant. As a prediction, one ton of fresh fruit bunches (FFB) of palm oil that is processed will produce 23% empty fruit bunches. OPEFB has great potential to be utilized because of its lignocellulosic content. Therefore, the task of this factory design is to utilize OPEFB biomass waste to produce intermediate products (lignin, cellulose, and hemicellulose) through the steam explosion method.

B. Process Description

The description of the process offered is divided into three process areas, namely: Pre-treatment which functions to clean raw materials and reduce their size; the second area, fractionation, is to separate hemicellulose from EFB that has gone through a pre-treatment process and to dissolve lignin from cellulose. Next, the third process area, the precipitation process, with the addition of strong acid to precipitate lignin from black liquor. The final area, the support area for the separation and drying process.

Before being processed, OPEFB undergoes a pre-treatment process through washing, size reduction and drying. OPEFB from the storage warehouse (F-110) is transferred using a belt conveyor (J-111) to a washing process (Rotary Washer, A-120) to remove impurities. The clean EFB is transported by bucket elevator (J-125) to be reduced in size to 8 – 12 mm in the shredder (C-130). The OPEFB fibers are then stored in the storage tank (F-134) and then enter the steam explosion reactor through the weigh belt feeder (J-135) and bucket elevator (J-136). At this stage, OPEFB is contacted with steam (200oC) for 10 minutes with a tank pressure of 16 bar. After the steam explosion is compressed, the treated EFB goes to the flash tank (F-141) and transported by screw conveyor (J-143) to the next process, fractionation.

In the fractionation stage, EFB which has been destroyed by the steam explosion process will go through two fractionation stages. In the first stage of extraction, OPEFB uses a screw conveyor (J-143) to a centrifuge (H-210) and is in contact with water (70oC), which is then separated by a centrifuge (H-210); This results in a supernatant containing mostly hemicellulose and water, and cake/pellet containing mostly cellulose and lignin. The supernatant containing hemicellulose and water then goes to the Hemicellulose Storage Tank (F-213). Meanwhile cake/pellet, cellulose and lignin, are further processed in the extraction reactor (R-220) using a screw conveyor (J-212).

The second stage of extraction took place in the extraction reactor (R-220) with the help of NaOH as a catalyst. The condition of the delignification reactor (R-220) had a consistency of NaOH 0.05 g/g fiber, 100°C, pH = 13 and 30 minutes. After the delignification process, the slurry is sent to the centrifuge (H-223) to be separated. Centrifuge (H-223) will produce a supernatant rich in lignin (black liquor) and a cake/pellet consisting of a large amount of cellulose and a small amount of residual lignin. This filtrate will proceed to the next process, the precipitation process. Meanwhile the cake/pellet is channeled to the tray dryer (B-225) to be dried, crushed in a fine crusher (C-226), then the cellulose powder produced is stored in a cellulose storage tank (F-229).

The black liquor solution from the centrifuge (H-223) will undergo a further process, the precipitation process. This precipitation process uses sulfuric acid to precipitate the lignin present in the black liquor. The precipitation process took place in a precipitation tank (F-230) with a temperature of 80°C, pH= 1.5-2.0 and a contact time of 10 minutes. The solution with the resulting lignin precipitate was then separated using a belt filter press (H-231), until 30% of the water content was successfully separated. Lignin in the form of cake is then dried using a tray dryer (B-232), crushed using a fine crusher (C-233), and then stored in a lignin storage tank (F-236).

In the process of producing lignin, a centrifuge is used to separate solid and liquid substances. Centrifuge is used in several processes, including the extraction process with water and the separation process of the extraction with NaOH.

During the extraction process with water, a centrifuge (H-210) functions as a separator from the extraction results between fiber solids containing lignin and liquids containing hemicellulose. The liquid containing hemicellulose will be pumped to the hemicellulose storage tank (F-213), then the flow containing most of the cellulose and lignin will be transferred using a screw conveyor (J-212) to the extraction reactor (R-220) for the extraction process using NaOH. The extracted NaOH will be pumped into a centrifuge (H-223) for the separation process between the cake containing cellulose and the solution containing lignin. The operating conditions used for the entire process of separating solids and liquids using this centrifuge are at a temperature of 30oC and a pressure of 1.013 bar. Normal operating conditions are used because in this separation process there is no reaction, and the working system for the centrifuge involves centrifugal force for sedimentation of a heterogeneous mixture, where the material will be inserted into a tube and will be rotated tightly. The denser mixture components migrate away from the centrifuge axis, causing the precipitate (pellet) to collect at the bottom of the tube, while the less dense mixture components migrate towards the liquid (liquid) axis.

Another separation process using a belt filter press (H-231) aims to perform solid-liquid separation by mechanical extrusion. The belt filter press produces a solids output cake which usually contains 20-30% solid mass. The process temperature during the separation takes place at room temperature of 30oC and the process pressure takes place following the pressure provided by the pressing roller.

The last process stage is the drying process, it is used to remove/reduce the water content in a material, namely cellulose and lignin products. Cellulose is separated from black liquor using a centrifuge and then dried using a tray dryer. The dried cellulose is then crushed using a fine crusher in order to form cellulose powder. The results of this powdered cellulose will be channeled into a cellulose storage tank (F-229).

Drying process is also needed to produce lignin in the form of powder. After the pressing process with a belt filter press (H-231), solid lignin which still contains water is put into a tray dryer (B-232) to be dried. Similar to cellulose, the dried solid lignin is then crushed using a fine crusher to form lignin powder. The resulting lignin powder will be channeled into the lignin storage tank (F-236).