ARTICLE IN PRESS Waste Management xxx (2008) xxx–xxx

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Gasification of refuse derived fuel in a fixed bed reactor for syngas production Ajay K. Dalai a,*, Nishant Batta b, I. Eswaramoorthi a, Greg J. Schoenau b a b

Catalysis and Chemical Reaction Engineering Laboratories, Department of Chemical Engineering, University of Saskatchewan, Saskatoon, SK, Canada S7N 5A9 Department of Mechanical Engineering, University of Saskatchewan, Saskatoon, SK, Canada S7N 5A9

a r t i c l e

i n f o

Article history: Accepted 3 February 2008 Available online xxxx

a b s t r a c t Steam gasification of two different refuse derived fuels (RDFs), differing slightly in composition as well as thermal stability, was carried out in a fixed-bed reactor at atmospheric pressure. The proximate and ultimate analyses reveal that carbon and hydrogen are the major components in RDFs. The thermal analysis indicates the presence of cellulose and plastic based materials in RDFs. H2 and CO are found to be the major products, along with CO2 and hydrocarbons resulting from gasification of RDFs. The effect of gasification temperature on H2 and CO selectivities was studied, and the optimum temperature for better H2 and CO selectivity was determined to be 725 °C. The calorific value of product gas produced at lower gasification temperature is significantly higher than that of gas produced at higher process temperature. Also, the composition of RDF plays an important role in distribution of products gas. The RDF with more C and H content is found to produce more amounts of CO and H2 under similar experimental conditions. The steam/waste ratio showed a notable effect on the selectivity of syngas as well as calorific value of the resulting product gas. The flow rate of carrier gas did not show any significant effect on products yield or their distribution. Ó 2008 Elsevier Ltd. All rights reserved.

1. Introduction There has been a gradually increasing demand for the treatment of municipal solid waste (MSW) and sewage sludge in many places around the world. MSW includes combustible and non-combustible wastes that come from household, municipal, commercial, and industrial sites. The primary waste management procedures in North America include dumping waste into landfills and massburn incineration. Land space for landfills is also a major concern. Canada is already paying the US to take the waste to their landfills. These procedures cause a high amount of greenhouse gas (such as methane, carbon dioxide, dioxins, furans, and nitrogen and sulfur oxides) to be emitted into the environment. Recently, a review (Malkow, 2004) on energy efficient and environmentally sound methods for the disposal of MSW was conducted. The most dominant method, mass-burn incineration, has many drawbacks including producing hazardous emissions and harmful residues. Waste management practices to date have been inadequate, thus affecting human health, the environment, air quality, and land and landscape. An ideal way to deal with the MSW would be to convert it all to energy through thermal treatment. Pyrolysis and gasification methods have emerged to address these issues and improve the energy output. As a medium to enhance the resource recovery from MSW, refuse derived fuel (RDF) is considered as priority solution in

* Corresponding author. Tel.: +1 306 966 4771; fax: +1 306 966 4777. E-mail address: [email protected] (A.K. Dalai).

industrialized countries. RDF is a value added material with a higher calorific value and a homogeneous particle size. Among biomass thermochemical conversion methods, pyrolysis and gasification processes appear to be promising for producing medium calorific value gas for electric power generation or H2-rich gas (H2 + CO) for synthesis purpose. Pyrolysis is the thermal breakdown of a biomass material in the absence of oxygen. Gasification is a process in which the biomass is heated at higher temperature with controlled oxygen to produce a fuel gas with minimum amounts of liquid and solid products. Steam may be used as the source of oxygen. It is well known that the products distribution and the yield of H2-rich gas depend mainly on the fuel type, reactor configuration, gas-solid residence time, reaction temperature, pressure, gasifying agent and catalyst of the gasification process. In the gasification process, decomposition reactions take place, and a mixture of H2 and CO is produced predominantly along with water, methane, and CO2. The resulting syngas can have many potential applications including as energy to power engines and generators, feedstock for producing pure hydrogen, fuel for fuel cells, and feedstock for producing methanol and ammonia (Friends of the Earth, 2002). The pyrolysis behavior of RDF in the temperature range of 500– 900 °C was investigated by measuring the composition and volume of released gas; the major components in the released gas were found to be CO, H2, CH4, C2H6, C2H4, C3H8 and C3H6 (Yang et al., 2001). An increase in pyrolysis temperature resulted in improved content of combustible gas components, particularly H2 and CH4. The total heating value of the released gas is dependent on the pro-

0956-053X/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.wasman.2008.02.009

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cess temperature and the type of RDF used. A higher process temperature improved the recycle energy efficiency converted into inflammable gas from RDF, but reduced the volumetric heating value of the gas. Several pilot plants in North America are working towards finding a financially viable method of thermal treatment for different types of waste. Hydrogen production from biomass by pyrolysis and steam gasification was attempted and found that the yield from steam gasification increases with increasing water-to-biomass ratio (Demirbas, 2006). Further, the hydrogen yield from the pyrolysis and the steam gasification increased with increasing the process temperature. The H2 yield from gasification was higher than that from pyrolysis for a similar type of biomass. The addition of steam as gasifying agent and catalyst in gasification process makes it possible to obtain high-grade and nearly N2free product gas. Steam gasification of biomass has been studied in various reactors (Rapagna et al., 1998; Corella et al., 2005) including a bubbling fluidized bed reactor (Pfeifer et al., 2004) and a circulating fluidized bed reactor (Wei et al., 2007) in recent years. Oxygen-blown gasification of combustible waste mixed with plastic and cellulosic materials was performed in the temperature range 1100–1450 °C in a fixed bed gasifier to investigate the gasification behavior with the operating conditions (Na et al., 2003). They found that the composition of H2 was in the range 30– 40 mol% and that of CO was 15–30 mol% depending upon the oxygen/waste ratio. It was desirable to maintain the top temperature of the reactor at 400 °C to ensure the mass transfer and uniform reaction throughout the packed bed. Further, when increasing the bed height, the formation of H2 and CO was increased, while the CO2 formation was decreased by the char-CO2 reaction and plastic cracking. Kinoshita et al. (2004) used a circulating fluidized bed reactor for gasification of three kinds of RDFs and found that an increase in process temperature improved the yield of the combustible gas components and energy recycle efficiency. However, the highest heating value of product gas was obtained at 600–700 °C. Atmospheric fluidized bed combustors were also used for the combustion of RDFs at various operating conditions by Hernandez-Atonal et al. (2007). They observed that CO concentration increased exponentially when air ratios approached the stoichiometric value. Also, 2.6% to 4.3% of N2 present in the fuel was converted into harmful NOx. Injection of secondary air slightly reduced the NOx concentration. De Filippis et al. (2004) simulated the syngas composition for different gasification conditions using a simple thermodynamic model for two-stage gasification of selected waste feedstocks, including RDFs. The simulation shows that methane and landfill gas are comparable in terms of H2 + CO in the resulting syngas, both reaching values higher than 80%. For the waste-based feedstocks considered, landfill gas and the MSW of high-income countries are expected to give the best syngas in terms of H2 + CO and H2/CO, while MSW of low-income countries are expected to yield syngas with low H2/CO ratios. Further they stated that the energy content of syngas produced from waste feedstocks, except in the case of MSW from low-income countries, shows potential for generating electric power. Co-gasification of the MSW from these countries, with landfill gas and the mixture of waste oil with RDF from low-income countries, are considered as options to improve the gas quality. Also, an attempt has been made to study the combustion behavior of two kinds of RDFs in a fluidized bed incinerator (Piao et al., 2000). They found that the concentrations of CO in flue gas are high and are strongly affected by the air ratio, but the CO concentrations were decreased when secondary air was injected. Horne and Williams (1996) studied the influence of temperature on the products distribution in flash pyrolysis of biomass and found that the formation of pyrolytic liquid products derived from biomass can be maximized using a fluidized bed reactor coupled with moderate temperatures (400–550 °C) and short residence

time. Further, the pyrolytic liquids were found to have relatively low calorific value, but contained 63% of the potential energy in the initial biomass feed and had a much greater density than the original biomass. The steam gasification of RDF was carried out by Galvagno et al. (2006) in a series of trials, by varying the process temperature (850–1050 °C), to investigate the effect of process temperature on the properties of the products formed and found that higher temperature resulted in higher conversion of the total organic content, which accounts for the greater syngas production. Further, at higher temperatures, the H2 content in the product gas is always in excess due to the contribution from water. There is yet to be a process designed for steam gasification of RDF that is energy efficient. In most gasification/pyrolysis plants, the energy required to keep the plant running is only slightly less than the amount of energy being produced. Hence, it is necessary to study the optimal parameters, such as steam flow rate and temperature, for the thermal treatment of MSW and its composites, such as wood, plastics, and RDFs, as a feedstock to derive the maximum possible energy. Hence, in this study, it is aimed to gasify two different RDFs, differing slightly in composition and thermal stability, using steam as oxygen source in a fixed-bed reactor. Also, the effects of gasification temperature, steam/waste ratio and carrier gas flow rate on the production of syngas as well as gaseous mixture and its calorific value were studied in a fixed bed reactor operated at atmospheric pressure.

2. Experimental 2.1. Characterization of the RDFs The feedstocks are two different RDFs, named as RDF 1 and RDF 2, which were obtained from Home Farms Technology in Brandon, Manitoba, Canada. RDF 1 is in pellet form, and was ground before using for gasification and RDF 2 is in a fluff form, and was used as it is. The compositions of the above two RDFs were analyzed in a CHNS analyzer (Vario EL III, a combustion analyzer). The thermal stability of the RDFs was analyzed by thermo gravimetric analysis in a PerkinElmer TGA instrument (Pyris Diamond). Using air at a flow rate of 30 ml/min as sweeping gas, the experiments were carried out up to 700 °C with a heating rate of 5 °C/min. 2.2. Experimental set-up The schematic diagram of the experimental setup used for the gasification process is shown in Fig. 1. The fixed bed reactor was first loaded with 1 g of feedstock for each experiment, and placed in a high temperature insulated furnace. The condenser was attached to the exit of the reactor and to a gas collector. Nitrogen was used as carrier gas for all the experiments. The temperature controller and steam/waste ratio were set accordingly to the desired values for each experiment. The steam was passed at the desired flow rate to the reactor once the temperature of the reactor reached 200 °C. Experiments were carried out at different temperatures, as well as different steam/waste ratios with varying flow rates of carrier gas for both the RDFs. The gasification was carried out for a period of 1 h. The gasification temperature was varied from 675 to 775 °C in increments of 25 °C, the steam/waste ratio was varied as 0.68, 1.35, 2.03, 2.70 and 3.33 (kg/kg) and the carrier gas flow rate was varied as 18, 24, 28, 32 and 36 ml/min. The amounts of gaseous and liquid products collected were recorded along with the char remaining after the gasification process to check the mass balance. The composition of the chars obtained from all the experiments was also analyzed in Vario EL III CHNS analyzer. The composition of the product gas was analyzed using HP 5890 and HP 5880 gas chromatographs. HP 5890 equipped with a TCD

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1 T

14

3

12 M

4 2

5

8

10 6 9

11

7

Fig. 1. Schematic diagram of the experimental set-up used for gasification of RDFs. (1) Syringe pump, (2) temperature controller, (3) temperature indicator, (4) electric furnace, (5) fixed bed reactor, (6) condenser, (7) ice container, (8) ice, (9) gas collector, (10) brine solution, (11) nitrogen cylinder, (12) mass flow controller, (13) valve, and (14) vent.

detector and a Molecular Sieve column was used to analyze H2, CO and CO2. HP 5880 equipped with a FID and a Poropak Q column was used to analyze hydrocarbons in the product gas. Experiments were duplicated to check the reproducibility. 3. Results and discussion 3.1. Characterization of RDFs The proximate and ultimate analyses of the RDFs used in this study are presented in Table 1. It is clear that carbon is the major component in both the RDFs (46.7 wt% for RDF 1 and 44 wt% for RDF 2). The hydrogen content of RDF 1 is 6.2 wt% and that of RDF 2 is 5.7 wt%. No significant amount of sulfur is detected in either of the RDFs. The major components of biomass have been shown to be of cellulose, hemicellulose and lignin (Theander, 1985; Williams and Besler, 1996). TGA was used to determine the thermal degradation of the RDFs in O2 atmosphere. The TGA profiles of RDF 1 and RDF 2 in air atmosphere are given in Fig. 2a and b, respectively. In the case of RDF 1, up to 200 °C, only slight weight loss (2%) is noted indicating the moisture content of the material. The thermal decomposition of RDF starts at approximately 250 °C and a major weight loss, around 52.1%, is observed in the temperature region of 200–350 °C indicating that the major composition of the RDF is hemicellulose and cellulose based com-

Table 1 Proximate and ultimate analysis of RDFs used for steam gasification RDF 1

RDF 2

Proximate analysis (wt% dry basis) Moisture content (wt% wet basis) Volatile matter Fixed carbon Ash

3.2 84.7 21.3 0.8

9.5 77.0 16.7 1.1

Ultimate analysis (wt% dry basis) C H O N S

46.7 6.2 44.1 1.2 0.5

44.0 5.7 47.2 1.4 0.7

pounds. At a higher temperature range, 350–600 °C, around 32.8% weight loss is observed. Two exothermic and one endothermic peaks were observed in the temperature range of 350–700 °C. Even at higher temperature, around 13% of the materials are stable, indicating the presence of some inorganic materials in the RDF. The TGA results for RDF 1 showed two main regimes of weight loss. The lower-temperature regime could be correlated with the decomposition of hemicellulose and the initial stages of cellulose decomposition. The higher-temperature regime can be mainly correlated with the later stages of cellulose decomposition. Similarly, in the case of RDF 2, a significant weight loss, around 8% is observed up to 200 °C indicating a higher moisture content compared to RDF 1. A major weight loss around 56.3% is noted in the temperature range of 200–350 °C. Higher temperature weight loss (18.9%) is also noted, indicating the presence of some plastic materials. Around 17% of the materials are stable, even at 700 °C, indicating the presence of inorganic materials, similar to RDF 1. These results are similar to the previous work (Narukawa et al., 1996; Namba et al., 1998; Piao et al., 2000) which showed that RDFs were composed of low and high temperature combustible components. Comparatively the hemicellulose content is significantly less in RDF 1 than in RDF 2, but an opposite trend is noted in the case of cellulose and inorganic materials content. 3.2. Gasification of RDFs The gasification process yielded three different phases of products: solid (char), liquid, and gas. The mass balance analyses showed that above 95% of the feed materials were recovered as products in the above forms. Gasification was carried out at different temperatures maintaining a constant steam/waste ratio and carrier gas flow rate for both of the RDFs. The effects of gasification temperature on gaseous products distribution and their corresponding calorific value for RDF 1 and RDF 2 are shown in Fig. 3a and b, respectively. In the case of RDF 1, it is interesting to note that CO and H2 are the major components comprising more than 70 mol% at all the temperatures studied. However, the CO and H2 percentages vary individually depending on the gasification temperature. For better CO selectivity, 675 °C was found to be the optimum temperature and 750 °C was found to generate a greater amount of H2. Based

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550.0 6.500 500.0

200.0 6.000

450.0 5.500

150.0 400.0

5.000

4.500

4.000 50.0

TG mg

300.0

100.0 DTA uV

DTG μg/min

350.0

250.0 3.500 200.0 0.0

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2.000 50.0 1.500

-100.0 0.0 100.0

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700.0

Temperature (°C) 600.0 11.00

18.00

10.00

500.0

16.00 9.00 400.0

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300.0

TG mg

6.00

DTA uV

DTG mg/min

7.00

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5.00 200.0 4.00

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6.00

2.00

1.00

0.0

4.00 0.00

100.0

200.0

300.0

400.0

500.0

600.0

700.0

Temperature (°C) Fig. 2. TGA profiles of (a) RDF-1, and (b) RDF-2.

on hydrogen selectivity, 750 °C was found to be the optimum temperature for further studies with different steam/waste ratios and carrier gas flow rates. A slightly increasing trend in CO and CO2 selectivities is noted with increasing process temperature, which

may be due to the enhanced gasification of RDFs at a significantly higher process temperature. However, CO2 and hydrocarbon production are found to be almost constant indicating that the generation of these products is not dependent on the gasification

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8.00

14.00

13.00

12.00

CO2

40.00

CO H2 +CO

11.00

CV

CH4 C2 H4

12.00

C3 H6

4.00

C2 H 6 C3 H8 C4 H8

11.00

CV

2.00

20.00

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10.00

0.00 650

700

750 Temperature (°C)

0.00 650

9.00 800

700

750 Temperature (°C)

14.00

8.00 14.00

80.00

6.00

H2 CO

12.00

H2 +CO

40.00

CO2 HC

11.00

CV

20.00

10.00

13.00

CH4 C2 H4 C3 H6

Mol%

60.00

Calorific value (MJ/m3)

13.00

Mol%

9.00 800

4.00

12.00

C2 H 6 C3 H8

11.00

C4 H8 CV

2.00

0.00 650

10.00

700

750

Calorific value (MJ/m3)

Mol%

HC

6.00

Mol%

H2

Calorific value (MJ/m3)

13.00 60.00

14.00

Calorific value (MJ/m3)

80.00

9.00 800

Temperature (°C) 0.00 650

700

750

9.00 800

Temperature (°C) Fig. 3. Effect of gasification temperature on product distribution and their corresponding calorific values of (a) RDF-1, and (b) RDF-2.

temperature, but may be dependent on the other factors such as steam/waste ratio or carrier gas flow rate and composition and nature of the RDFs. When considering the calorific value of the gas product, gasification at low temperature (675 °C) is found to produce gas products with higher calorific value than at higher process temperature (775 °C). In the case of RDF 2, the total CO and H2 contents are found to be slightly lower compared to those for RDF 1 under similar experimental conditions studied. This indicates that the composition of RDFs (Table 1) plays an important role in CO and H2 contents in the product gas. Gasification of RDF with high carbon and hydrogen contents resulted in product gas with higher CO and H2 contents. Also, the hydrogen yield is found to decrease with temperature similar to that of CO2 and hydrocarbons. However, CO production is gradually increased with increasing temperature. The calorific value of the product gas produced at the gasification temperature of 725 °C is found to be significantly higher than that of the product gases produced at other process temperatures. At 775 °C, no significant increase in syngas production or calorific value is noted. Based on the amount of syngas produced and calorific value of product gas, 725 °C was chosen as the optimum process temperature under the experimental conditions studied for further studies on both the RDFs. The effects of temperature on the distribution of hydrocarbon and their corresponding calorific values for RDF 1 and RDF 2 are given in Fig. 4a and b, respectively. The steam/waste ratio and carrier gas flow rate were kept constant at 2.0 ml/h and 25 ml/min, respectively for all the experiments. Among the hydrocarbons, methane is found to be the major product in both of the RDFs. A

Fig. 4. Effect of gasification temperature on distribution of hydrocarbons and their corresponding calorific values of (a) RDF-1, and (b) RDF-2; steam/waste ratio – 2.0, N2 flow rate – 25 ml/min.

maximum of around 7 mol% methane is observed in both cases. In the case of RDF 1, the methane selectivity is found to decrease significantly with increasing temperature, but a similar trend is not observed for RDF 2. A similar trend is observed in calorific value of the product gas, since it is mainly dependent on the amount of methane. Next to methane, a notable amount of ethylene is observed in both of the RDFs and all other hydrocarbons such as, ethane, propane, propene and butane are less than 1 mol%. In order to study the effects of steam/waste ratio on the product gas distribution and calorific value, gasification was carried out with different steam/waste ratios (0.68, 1.35, 2.0, 2.7 and 3.22) and carrier gas flow rates (25 ml/min) at 725 °C and the corresponding plots are shown in Fig. 5a and b, respectively, for RDF 1 and RDF 2. In Fig. 5a and b, the hydrogen selectivity is found to increase significantly with increasing steam/waste ratio up to 2; beyond that a slight fall is noted. In contrast, the CO production is found to decrease with increasing steam flow rate. Demirbas (2006) observed an increase in total gas yield and H2 selectivity with increasing steam/waste ratio in pyrolysis and steam gasification of biomass. A slight increase in CO2 selectivity is also observed when increasing the steam/waste ratio from 0.68 to 3.22. When considering the amount of liquid product and char collected (given in Table 2), an increase in steam/waste ratio resulted in more liquid products and char. A fall in calorific value is noted when increasing the steam/waste ratio. The CHNS analysis of the char obtained at higher gasification temperature (775 °C) indicate the presence of greater amounts of hydrogen and carbon, indicating that higher temperature is not favoring the H2 and CO production. Fig. 6a and b, shows the distribution of hydrocarbon components at various steam/waste ratios at 725 °C for RDF 1 and RDF 2, respectively. In the case of RDF 1, which was in pellet form, it can be seen

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14.00

80.00

13.00

13.00

6.00

CH4

3

CO2

12.00

H2 HC CV

11.00

C2 H4

Mol%

CO

Mol%

Calorific value (MJ/m)

60.00

40.00

14.00

8.00

12.00

C3 H6

4.00

C2 H6 C3 H 8

11.00

C4 H8 CV

2.00

Calorific value (MJ/m3)

6

10.00

20.00 10.00 0.00 0

0.00 0

0.7

1.4 2.1 Steam/waste ratio (kg/kg)

0.7

1.4 2.1 Steam/waste ratio (kg/kg)

9.00 3.5

2.8

9.00 3.5

2.8

14.00

80.00

14.00

80.00

13.00

40.00

12.00

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Mol%

H2 CO CO2 CO+H2 HC CV

Calorific value (MJ/m3)

Mol%

60.00

1.35 2 2.7 Steam/waste ratio (kg/kg)

11.00

10.00

0.68

1.35 2 2.7 Steam/waste ratio (kg/kg)

9.00 0.68

12.00

20.00

0.00

0.00

H2 CO CO2 CO+H2 HC CV

40.00

Calorific value (MJ/m3)

13.00 60.00

9.00

3.3

3.3 Fig. 6. Effect of steam/waste ratio on the distribution of hydrocarbons from gasification of (a) RDF-1, and (b) RDF-2; temperature – 725 °C, N2 flow rate – 25 ml/min.

Fig. 5. Effect of steam/waste ratio on the product distribution of gasification of (a) RDF-1, and (b) RDF-2; temperature – 725 °C, N2 flow rate – 25 ml/min.

obtained from all the experiments are listed in Table 2. Generally, the amounts of char and liquid products are found to be greater for experiments at higher process temperatures as well as at higher steam/waste ratio. Most of the hydrogen present in RDFs was converted into gaseous products during the gasification with steam.

that the selectivity of methane decreased with increasing steam/ waste ratio. The selectivities for other components are almost constant irrespective of steam/waste ratio. In this way, the calorific value of the product gas shows a similar trend as that of methane. A similar trend is noted in the case of RDF 2 (Fig. 6b). The controlling factor for the calorific value of the product gas seems to be methane. Hence, a lower steam/waste ratio is more suitable for the production of high calorific value gas under the experimental conditions studied. However, a higher steam/waste ratio is preferred to produce H2-rich product gas (Fig. 5a and b) indicating the H2 contribution from steam when the steam/waste ratio is higher. Experiments were carried out at different carrier (N2) flow rates (10, 15, 20, 25 and 30 ml/min) for both of the RDFs. There is no significant effect observed in amount or composition of gaseous products collected. The amounts of char, liquid and gaseous products

4. Conclusions Refuse derived fuels, differing slightly in composition and thermal stability, were subjected to steam gasification at different temperatures using steam as the oxygen source. The proximate and ultimate analyses confirm that the major composition of RDF is carbon and hydrogen. The thermal degradation study of RDFs confirms the presence of hemicellulose and cellulose based materials in RDFs along with plastics and some inorganic materials. A series of gasification experiments carried out indicates that the H2 and CO

Table 2 Amounts of byproducts obtained from RDF 1 and RDF 2 at different gasification temperatures, and CHN composition of the obtained chars Temperature (°C)

Steam/waste ratio (kg/kg)

RDF 1 Char (g)

675 725 725 725 725 725 750 775 775

2.0 0.68 1.35 2.0 2.7 3.33 2.0 1.35 2.0

0.33 0.58 0.38 0.31 0.27 0.30 0.32 0.38 0.38

RDF 2 Liquid (g)

2.2 0.63 1.63 2.60 3.22 3.50 1.93 1.68 2.33

Gas (l/g)

0.23 0.26 0.33 0.29 0.31 0.37 0.33 0.43 0.30

CHN analysis of char (%) C

H

N

47.3 37.8 43.2 48.2 55.7 59.5 60.7 61.0 61.8

1.9 0.8 0.9 1.0 0.9 1.1 0.9 0.9 1.1

0.1 0.3 0.5 0.5 0.5 0.1 0.1 0.1 0.2

Char (g)

1.21 0.29 0.38 0.57 0.38 0.66 0.69 0.74 0.78

Liquid (g)

1.06 1.96 2.15 0.55 1.68 0.83 0.92 1.56 1.72

Gas (l/g)

0.32 0.30 0.33 0.31 0.35 0.31 0.30 0.28 0.29

CHN analysis of char (%) C

H

N

55.8 54.8 56.4 58.6 56.9 47.4 59.5 61.7 62.4

1.5 1.0 0.7 1.8 1.3 1.0 0.9 1.2 1.6

0.1 0.1 0.1 0.2 0.2 0.1 0.2 0.1 0.1

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Please cite this article in press as: Dalai, A.K. et al., Gasification of refuse derived fuel in a fixed bed reactor for syngas production, Waste Management (2008), doi:10.1016/j.wasman.2008.02.009