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PRE DESIGN OF CELLULOSE FACTORY FROM RICE STRAW WITH STEAM EXPLOSION METHOD

Presented by :

1. Ni Nyoman Kaniya Kumala Dewi (02211840000111)
2. Aisyah Fadzlina (02211840000121)

Indonesia is an agricultural country with rice productivity reaching more than 54 million tons in 2020. The part of the rice plant that is most often used is rice as the staple food of the Indonesian population and the rest of the plant is usually used for animal feed. This is very unfortunate, because rice straw contains lignocellulose which has a lot of potential. Lignocellulosic is biomass derived from plants with the main content of lignin, cellulose, and hemicellulose. Lignocellulose is commonly found in the cell walls of plants. Due to the abundant availability of raw materials and not being used as food ingredients, this material has the potential to become a new and environmentally friendly energy resource. The cellulose content in rice straw is greater than other lignocellulosic content, where cellulose is 32.1% in rice straw, while lignin and hemicellulose are only 18% and 24%, therefore, the design of this plant focuses more on cellulose fractionation.

Cellulose can be used in the paper, food, drug, and chemical industries. The cellulose derivatives that are often used for commercial products are carboxymethyl celullose (CMC), methyl cellulose (MC), hydroxypropyl methyl cellulose (HPMC). MC has a function to control the release of drug content into the solvent, so it is very useful in the drug/pharmaceutical industry to prevent the risk of dose dumping. CMC has the function of binder, thickener and emulsion stabilizer so it is often used in the pharmaceutical and textile industries. Meanwhile, HPMC can be used to make gels. Cellulose is also often used as raw material for bioethanol and pulp/paper.

Process Description

To separate the cellulose it is necessary to do pre-treatment. This pretreatment is useful for breaking down the crystalline structure of cellulose. The initial treatment was divided into 4, namely, physical, chemical, physico-chemical, and biological pre-treatment, and one of these treatments was steam explosion which was included in the physico-chemical pre-treatment.

1. Size Reduction

Rice straw that has been transported from the warehouse to the crusher uses a belt conveyor to reduce the size of rice from 10 – 14 cm to 2.5 cm. This size reduction is done to facilitate the entry of raw materials into the next process.

2. Main Process

This stage is carried out in a steam explosion reactor where the straw that has entered the reactor is given high pressure steam until it reaches a pressure of 15 bar in the reactor. The reactor was then allowed to stand for 5-10 minutes and then suddenly the pressure was lowered, resulting in explosive decompression.

Rice straw heated by steam condensation causes the wet rice structure with hot water which causes the release of acid from the hemicellulose fraction and lowers the pH to 3-4. Acid conditions make hydrolysis of hemicellulose to xylose occur.

After that, the rice straw then goes into the washing place to be washed for 15 minutes at 80 C. This washing function is to hydrolyze the hemicellulose again into xylose which is soluble in water. The ratio of liquid to solid is 1 to 2. The slurry from the washing output is then filtered to separate the xylose and cellulose in the form of a cake.

This cake is then extracted using NaOH and ethanol solvent for 60 minutes at a temperature of 160 C. This extraction aims to delignify the lignin contained in the cake. Where, this lignin will react with NaOH to form soluble Na-Ligninate. The slurry is then filtered, the cake containing cellulose is then taken and stored in a storage area with conditions that have been adapted to the product so that it does not get damaged quickly.

3. Recovery

The filtrate containing Na-Ligninate and other components such as ethanol then goes to distillation to recover the ethanol which is used back into the extraction alcohol. While the other component, black liquor, will be returned to the boiler as feed for steam