THE EFFECT OF HYDROTHERMAL DEWATERING AND ADDITION OF METHYL ESTER SULFONATE SYNTHESIS FROM RUBBER SEED ON REOLOGICAL PROPERTIES OF COAL-WATER SLURRY

• Main Author: Akbar, Billyan
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/72216
• Institution: Institut Teknologi Bandung

To increase the added value of Indonesian coal, the government has encouraged coal mine owners to conduct downstream development and utilization of coal. Coal gasification is chosen from many downstream coal options because the syngas produced by gasification is flexible to be used as raw material for the chemical industry. The gasification technology used is an entrained-bed reactor such as the MHI Gasifier to produce the final product. It uses a slurry feed called coal water slurry (CWS) to obtain hydrogen gas and methane syngas. Coal feed suitable for CWS generally has low inherent moisture and particle properties that are not too hydrophobic, so CWS has good rheological properties. However, considering that Indonesia's current coal reserves are dominated by Low-Rank Coal (LRC), it is necessary to make efforts to change the nature of the LRC. In addition, using an additive as a dispersant is commonly used to improve the rheological properties of CWS. In this study, a combination of the Hydrothermal Dewatering (HTD) process and the addition of Methyl Ester Sulfonate (MES) resulting from synthesizing rubber seeds was proposed to improve the rheological properties of CWS. The study began with preparing and grinding LRC coal samples from East Kalimantan until they passed a 140-mesh sieve and then mixed with water at a 1:1 (w/w) ratio to form 50% solid CWS. The HTD process is carried out by placing the CWS in an autoclave for 40 minutes at a temperature of 200°C (15 bar pressure) or 250°C (40 bar pressure). Raw and dry HTD coal is then characterized to see their chemical composition and functional groups. Raw coal and HTD are then made CWS (55% solid) with variations without additives and the addition of additives with variations of ±1% by weight. The additive added is MES synthesized from rubber seed oil or Sodium Lignosulfonate (SL), a commercial dispersant, for comparison. All CWS samples were then analyzed by viscosity test, zeta potential and static stability. The experimental results show that the coal HTD process at a temperature of 250°C can reduce the atomic ratio O/C which was initially 0.49 to 0.29, and the atomic ratio H/C which was initially 1.27 to 0.98, where this decrease is proportional to the reduction of alkane, hydroxyl, and carboxyl groups from the results of FTIR analysis. With the standard CWS viscosity for gasification feed in the range of 900 mPa.s to 1,000 mPa.s, the CWS viscosity resulting from HTD can reduce the viscosity from 1,280 mPa.s to 890 mPa.s with the addition of 2.5 g/L MES. In comparison, adding SL needs up to 15 g/L to achieve the same viscosity. Adding MES to the Critical Micelle Concentration (CMC) point shows a penetration ratio value of 80.14% with a storage time of about 120 minutes, which is better than the addition of SL at the CMC point and the same storage time.