Pandji Prawisudha

Hydrothermal Upgrading of Korean MSW for Solid Fuel Production: Effect of MSW Composition

In Korea, municipal solid waste (MSW) treatment is conducted by converting wastes into energy resources using the mechanical-biological treatment (MBT). The small size MSW to be separated from raw MSW by mechanical treatment (MT) is generally treated by biological treatment that consists of high composition of food residue and paper and so forth. In this research, the hydrothermal treatment was applied to treat the surrogate MT residue composed of paper and/or kimchi. It was shown that the hydrothermal treatment increased the calorific value of the surrogate MT residue due to increasing fixed carbon content and decreasing oxygen content and enhanced the dehydration and drying performances of kimchi. Comparing the results of paper and kimchi samples, the calorific value of the treated product from paper was increased more effectively due to its high content of cellulose. Furthermore, the change of the calorific value before and after the hydrothermal treatment of the mixture of paper and kimchi can be well predicted by this change of paper and kimchi only. The hydrothermal treatment can be expected to effectively convert high moisture MT residue into a uniform solid fuel.

Municipal solid waste processing and separation employing wet torrefaction for alternative fuel production and aluminum reclamation

This study employs wet torrefaction process (also known as hydrothermal) at low temperature. This process simultaneously acts as waste processing and separation of mixed waste, for subsequent utilization as an alternative fuel. The process is also applied for the delamination and separation of non-recyclable laminated aluminum waste into separable aluminum and plastic. A 2.5-L reactor was used to examine the wet torrefaction process at temperatures below 200°C. It was observed that the processed mixed waste was converted into two different products: a mushy organic part and a bulky plastic part. Using mechanical separation, the two products can be separated into a granular organic product and a plastic bulk for further treatment. TGA analysis showed that no changes in the plastic composition and no intrusion from plastic fraction to the organic fraction. It can be proclaimed that both fractions have been completely separated by wet torrefaction. The separated plastic fraction product obtained from the wet torrefaction treatment also contained relatively high calorific value (approximately 44MJ/kg), therefore, justifying its use as an alternative fuel. The non-recyclable plastic fraction of laminated aluminum was observed to be delaminated and separated from its aluminum counterpart at a temperature of 170°C using an additional acetic acid concentration of 3%, leaving less than 25% of the plastic content in the aluminum part. Plastic products from both samples had high calorific values of more than 30MJ/kg, which is sufficient to be converted and used as a fuel.

Hydrothermal Treatment of Municipal Solid Waste for Producing Solid Fuel

The usage of municipal solid waste (MSW) is usually hindered by its nonuniformity, high moisture, low energy density, and the occurrence of chlorine in the plastic-impregnated waste. A hydrothermal treatment is developed to convert the MSW into solid fuel by employing a commercial scale system of about 1 ton capacity, applying saturated steam at about 2 MPa for about 60 min holding time. It was shown that the product has better uniformity, higher density, and better drying performance compared to MSW without reducing its heating value. The combustion characteristic of the final product was similar to that of sub-bituminous coal, and capable of reducing the SO2 and NO emissions during co-combustion with coal. Additionally, the product showed that about 80 % of the organic chlorine was converted into inorganic, water-soluble chlorine, and the total chlorine content in the water-washed product was down to 16 %. It was calculated that the required energy for the hydrothermal treatment was 0.8 MJ/kg MSW, lower than conventional RDF production process which needs 1.35 MJ/kg MSW. It can be concluded that the hydrothermal treatment can be employed to convert MSW into a chlorine-free solid fuel suitable for co-combustion with coal.

Sewage Sludge Treatment by Hydrothermal Process for Producing Solid Fuel

Sludge treatment and disposal is one of the focus points in the waste treatment technology research due to the fact that sewage sludge is a form of pollution. One of the promising methods of sewage sludge treatment, considering its maximum sludge reduction and short processing time, is incineration. However, the usage of sewage sludge as fuel in incinerator is hindered by its high water content and high nitrogen content. A hydrothermal process for producing solid fuel from sewage sludge is developed by using saturated steam at 160–200 °C and about 60 min holding time. It was shown that the product has improved dehydrability, but at the same time exhibiting higher solubility in the water, resulting in slightly lower calorific value due to the loss of dissolved solids, which have significant calorific value; therefore, an optimum operating condition is required to improve the dehydrability of sludge without reducing its solid content and calorific value. In the term of sewage odor, it was shown that after the hydrothermal treatment the sulfur-containing compound concentration was decreased, the same with the total odor intensity in the solid product. On the other hand, the odor intensity in the liquid and gaseous products were increased, suggesting the transfer of these compounds to the liquid and gaseous parts. During the combustion experiment, it was shown that the hydrothermally treated sludge emits lower NO emission compared to the raw sludge, promoting its possibility to be used in incinerator as direct or co-fuel without resulting in secondary pollution.

Multi-production of solid fuel and liquid fertilizer from organic waste by employing wet torrefaction process

Preliminary survey showed that organic waste from the market is about 18.77%, or second largest in the total waste generation. Its management becomes a challenge, because it is not comprised only of organics but also mixed with small amount of plastics; therefore, conventional biological process will not achieve their maximum efficiency. Wet torrefaction is a thermal process in hot water medium, which will dissolve organic materials into water, effectively converting most solids into liquid product. Banana fruit stem and cabbage were chosen as the mixed organic waste representative, and treated in a 2.5 L reactor using saturated steam in the temperature range of 175 to 225 °C before being analyzed for their heating value in solid products as fuel precursors, and their nitrogen, phosphorus and potassium (NPK) contents in liquid products as liquid fertilizer precursors. It was found that for cabbage, the wet torrefaction process at 200 °C and 90 min resulted in 15.59 MJ/kg product heating value with NPK content of 3.43%. For banana fruit bunch stem, the wet torrefaction process at 225 °C and 30 min resulted in 17.64 MJ/kg product heating value with NPK content of 5.13%. It can be concluded that wet torrefaction process can simultaneously produce solid and liquid product as solid fuel and liquid fertilizer, respectively.Preliminary survey showed that organic waste from the market is about 18.77%, or second largest in the total waste generation. Its management becomes a challenge, because it is not comprised only of organics but also mixed with small amount of plastics; therefore, conventional biological process will not achieve their maximum efficiency. Wet torrefaction is a thermal process in hot water medium, which will dissolve organic materials into water, effectively converting most solids into liquid product. Banana fruit stem and cabbage were chosen as the mixed organic waste representative, and treated in a 2.5 L reactor using saturated steam in the temperature range of 175 to 225 °C before being analyzed for their heating value in solid products as fuel precursors, and their nitrogen, phosphorus and potassium (NPK) contents in liquid products as liquid fertilizer precursors. It was found that for cabbage, the wet torrefaction process at 200 °C and 90 min resulted in 15.59 MJ/kg product heating value with NPK con...

Numerical and experimental study on rocket stove combustion process for heating stirling engine

As an archipelago country, electrification in Indonesia is still limited in the main islands and has not reached the remote and outer islands due to the limited infrastructure of the country. To provide the electricity in the region, the small generator set is needed. However, the usage of the diesel fueled engine in the generator set is predicted to be more difficult in the future due to the fossil fuel price and rareness. The Stirling Engine offers the solution for such problem since it is able to utilize various type of fuel as energy sources. In this research, the further study was conducted on the performance of the 200-Watt Stirling engine’s furnace to provide the heat source. The type of furnace used in the stirling engine system is called Rocket Stove. The fuel used in this research was bamboo as one of the biomasses with enormous potential in the country. The numerical simulation was conducted to estimate the mass flow rate of the fuel. The experiment was conducted to obtain the rocket stove temperature distribution. Evaluation was then conducted to analyze the performance of the heat exchanger absorbing the heat of the flue gas. The results obtained from this research were the fuel rate required to produce sufficient heat to meet the heat requirement of Stirling Engine was 3.28 kg/h in bamboo and 1.43 kg/h in LPG. The average temperature distribution before the Heat Exchanger reached 788 ℃ with the standard deviation of 61 °C on the bamboo and the average temperature distribution before the Heat Exchanger reached 725 °C with the standard deviation of 3 °C on LPG. The effectiveness of heat exchanger used is 68%.As an archipelago country, electrification in Indonesia is still limited in the main islands and has not reached the remote and outer islands due to the limited infrastructure of the country. To provide the electricity in the region, the small generator set is needed. However, the usage of the diesel fueled engine in the generator set is predicted to be more difficult in the future due to the fossil fuel price and rareness. The Stirling Engine offers the solution for such problem since it is able to utilize various type of fuel as energy sources. In this research, the further study was conducted on the performance of the 200-Watt Stirling engine’s furnace to provide the heat source. The type of furnace used in the stirling engine system is called Rocket Stove. The fuel used in this research was bamboo as one of the biomasses with enormous potential in the country. The numerical simulation was conducted to estimate the mass flow rate of the fuel. The experiment was conducted to obtain the rocket stove temp...

Development of torre-briquetting process to convert mixed MSW into high energy density solid fuel

A combination of wet torrefaction and binderless briquetting processes, namely torre-briquetting process, has been developed in Indonesia to treat the mixed municipal solid waste into a solid fuel. A mixture of organic and plastic waste was treated in a 2.5 L reactor using saturated steam in the temperature range of 175 to 225°C. Afterwards, the products were briquetted in varied pressure of 500 to 1000 bar. It was observed that the wet torrefaction process at the temperature of 225°C, residence time of 30 min and sample-to-water ratio of 1:2.5 was able to produce the solid product with heating value of up to 5923 kcal/kg, equivalent to that of bituminous coal. In the briquetting aspect, the briquetted product showed adequate drop test durability of 90% at 1000 bar briquetting pressure. The density of the briquette however, has not reached the standard of 1000 kg/m3, presumably due to the presence of large sized plastic in the briquette. The results suggest that by employing wet torrefaction, the organic fibers in the mixed waste are trapped into the plastic matrix, producing granules which are suitable for briquetting. Therefore, the torre-briquetting process can be a revolutionary solution to treat the MSW without any separation required to produce high caloric solid fuel.A combination of wet torrefaction and binderless briquetting processes, namely torre-briquetting process, has been developed in Indonesia to treat the mixed municipal solid waste into a solid fuel. A mixture of organic and plastic waste was treated in a 2.5 L reactor using saturated steam in the temperature range of 175 to 225°C. Afterwards, the products were briquetted in varied pressure of 500 to 1000 bar. It was observed that the wet torrefaction process at the temperature of 225°C, residence time of 30 min and sample-to-water ratio of 1:2.5 was able to produce the solid product with heating value of up to 5923 kcal/kg, equivalent to that of bituminous coal. In the briquetting aspect, the briquetted product showed adequate drop test durability of 90% at 1000 bar briquetting pressure. The density of the briquette however, has not reached the standard of 1000 kg/m3, presumably due to the presence of large sized plastic in the briquette. The results suggest that by employing wet torrefaction, the organic ...

Study on utilization of Indonesian non-recycled municipal solid waste as renewable solid fuel

In 2008, Indonesia produced 38.5 million tons of municipal solid waste (MSW) and was estimated to increase 2-4% per year. Approximately 25% of the waste was consisted of paper, glass, recycled plastic and metal, taken by scavengers due to their economic value. The rest was non-recycled MSW consisted of organic waste, non-recycled plastic, textile and rubber. In this research, field survey based on Indonesian Standard SNI 19-3964-1994 was conducted to find out the latest MSW composition in final landfill, and its potential as solid fuel was analyzed by investigation of its physical composition and calorific value. The survey data showed that the composition of remained MSW at final landfill was dominated by organic waste and non-recycled plastic waste with a mass ratio of about 5:1. The composition of non-recycled plastic waste was dominated by colored plastic packaging, while the organic waste was dominated by leaves, food wastes, fruit wastes and vegetable wastes. The water content of non-recycled waste was high at about 51.38%, indicating that a pre-treatment process is required before the waste can be used as solid fuel. This characteristic, added with the fact that the waste is mixed and irregular in size and shape, hinders the non-recycled MSW utilization as solid fuel. Based on these characteristics, the wet torrefaction technology can be an appropriate pre-treatment process for Indonesian MSW, because it requires no initial drying and sorting process, producing 75% densified solid material with higher energy density and calorific value of almost equal to sub bituminous coal.In 2008, Indonesia produced 38.5 million tons of municipal solid waste (MSW) and was estimated to increase 2-4% per year. Approximately 25% of the waste was consisted of paper, glass, recycled plastic and metal, taken by scavengers due to their economic value. The rest was non-recycled MSW consisted of organic waste, non-recycled plastic, textile and rubber. In this research, field survey based on Indonesian Standard SNI 19-3964-1994 was conducted to find out the latest MSW composition in final landfill, and its potential as solid fuel was analyzed by investigation of its physical composition and calorific value. The survey data showed that the composition of remained MSW at final landfill was dominated by organic waste and non-recycled plastic waste with a mass ratio of about 5:1. The composition of non-recycled plastic waste was dominated by colored plastic packaging, while the organic waste was dominated by leaves, food wastes, fruit wastes and vegetable wastes. The water content of non-recycled waste ...

A pilot-scale study of wet torrefaction treatment for upgrading palm oil empty fruit bunches as clean solid fuel

Less utilized empty fruit bunch (EFB) is seldom used as solid biofuel due to its high alkali content that potentially cause ash deposit called slagging and fouling. This phenomenon could harm biomass-fired power plant equipment. Some pre-treatment of EFB is needed to reduce EFB ash deposit potential. The effect of wet torrefaction pre-treatment in laboratory scale was successfully proven in decreasing slagging and fouling potential while increasing EFB calorific value that could fulfill clean solid fuel criteria. This research focuses on wet torrefaction process that conducted on a pilot scale with the capacity of 250 liters. It was found that wet torrefaction process can improve the products calorific value up to 9.41% while reduce its ash content down to 1.01% comparing to the raw EFB. The reduction of ash content also leads to the reduction of slagging and fouling tendency that presents in terms of alkali index. Alkali index is a quantitative method that can be calculated after obtaining metal oxides fraction on solid fuel. Metal oxides could be obtained by using energy dispersive x-ray spectroscopy.