The solid waste generated from military contingency bases (CBs) is a potential fuel for appropriately-scaled, waste to energy (WTE) systems. To inform WTE system design, fuel properties of seventeen components of synthetic contingency-base waste recipes from the literature were characterized for ultimate analysis, heating values, proximate analysis and reactivity in a steam atmosphere at three temperature typical of gasification conditions. A simple mathematical approach was applied to predict the properties and reactive behavior of composite mixtures using the weighted sum of the corresponding components, assuming negligible interaction between components. The method was validated using prepared composite mixture samples. In addition, chemical equilibrium calculations for steam gasification of the composite samples were conducted to explore the effects of waste composition variability on syngas production and composition.

X-ray fluorescence (XRF) spectroscopy was usedto assess the effectiveness of various mild pretreatMent methods for improving the fuel quality of banagrass, a tropical grass. Three types of pretreatment were used with increasing levels of severity: (i) S1 involves dewatering (pressing) only, (ii) S2 where the sample is pressed and leached, and (iii) S3 where pressing-leaching-pressing process is used. In addition, the influence of particle size (2 or 60-80 mm), leaching water temperature (25 or 75 degrees C), and leaching time (1 or 3 min) On the extraction of inorganic elements was examined`. The results show that the S3 pretreatment is the most effective and that reducing the particle size has,a more significant effect than increasing leaching temperature Or time. Using a 2 Aim particle size at 75 degrees C for 3 min produced the greatest effect, removing 50-60 wt % of the Na, similar to 65 wt % Mg,similar to 90 wt % P,similar to 90 wt % wt % K, similar to 55 wt % S, and similar to 95 wt % Cl. USing dewatering alone (S1) to pretreat the banagrass was the least effective approach. The S2 pretreatment produced results that are midway between the S1 and S3 results. However, using small particle's with the S2 method gives similar results tolprocessing large particles using the =S3 approach.

Mechanical dewatering and leaching were used to process freshly harvested banagrass (Pennisetum purpureum X Pennisetum glaucum) and improve fuel properties relevant to thermochemical conversion. A factorial, 23 experiment determined the effects of process operating parameters: particle size (1 mm and 80 mm), rinse water temperature (25 degrees C and 75 degrees C), and rinse duration (1 min and 3 min). Characterization of the samples from the process included moisture and ash contents of solid samples, potassium (K) and chlorine (Cl) contents of solid and liquid samples, and chemical oxygen demand, total solids, and total suspended solids of liquid samples. These were used to assess the effectiveness of treatment on reducing K and Cl in the processed material, estimate material/energy losses associated with the processing, and identify further treatment requirements and opportunities for material recovery. The effects of particle size, rinse water temperature, and their interaction indicate that processing with low-grade hot water (75 degrees C) can improve K and Cl removal by over 10% compared to treatment using ambient temperature water for larger particles (80 mm). The former could result in reduced capital and operating costs for size reduction, as well as reduced material losses during processing. (C) 2017 Elsevier Ltd. All rights reserved.

Efficient recovery of coal liquids "from direct coal liquefaction residue (DCLR) is beneficial for improving the economics of the direct coal liquefaction process. An attempt was made to evaluate the possibility of extracting coal liquids from DCLR using subcritical water (SBCW). The properties of water are compared with those of typical organic solvents. With regard to the ability of dissolving/emulsifying organic components, SBCW compares favorably with some typical organic solvents under certain conditions. This is evidenced by the fact that the SBCW3 (320 degrees C/11.7 MPa) extraction yield is similar to the n-hexane extraction yield, although the SBCW1 (250 degrees C/5.2 MPa) and SBCW2 (300 degrees C/8.9-11.6 MPa) extraction yields are lower than the n-hexane extraction yields under comparable conditions. The recovery rate of coal liquids from DCLR by SBCW3 extraction can be higher than the maximum recovery rate by n-hexane or methanol extraction when the (SBCW3/DCLR)(mass) is high enough. In comparison with n-hexane-extractable, SBCW-extractable contains more high-molecular-weight and heteroatom-containing components. The group composition balances of several SBCW extractions reveal that SBCW-extractable is mainly from the n-hexane-extractable fraction of the parent DCLR, with a small amount of components from the asphaltene-type materials. The solvent utilization index decreases with the increase of extraction yield, indicating that the overall solubility/emulsibility of coal liquids in SBCW3 decreases as the extraction proceeds. This implies that more and more high-molecular weight and low-solubility/emulsibility components are extracted from DCLR with the increase of extraction yield. Similar phenomena are found when n-hexane and methanol are used as the extraction solvents. It is also found that the SBCW3 extraction yield can be higher than the 320 degrees C-pyrolysis extraction yield when the (SBCW3/DCLR)(mas)s is high enough.

Tropical biomass feedstock candidates, banagrass (Pennisetum purpureum x Pennisetum glaucum), guinea grass (Panicum maximum), energy cane (Saccharum spontaneum), and sugar cane (Saccharum officinarum L.) (as reference) were harvested and processed using pressing and leaching techniques to improve fuel properties for thermochemical conversion. Test results are reported that summarize the impacts of treatment methods on fuel properties and provide detailed data on mass and element partitioning between process streams to inform system design. The processed fuels had lower ash contents, improved heating values, higher ash deformation temperatures, and higher volatile matter to fixed carbon ratios than the parent materials. The liquid streams generated by the process were characterized for chemical oxygen demand, sugar content, total solids, total suspended solids, and major and trace elements. At least 20% of the initial fuel dry matter was partitioned to the byproduct liquid streams as total solids under the combined influences of leaching and mechanical processing. Analytical results support the land application of liquids as a nutrient recycling option. Element partitioning between solid and liquid process streams was determined and material and element mass balances were performed. Chemical equilibrium calculations based on the elemental composition of the parent materials and processed fuels and steam gasification conditions predicted substantial reductions in concentrations of K, Cl, S, Na, and Mg in the product gas. (C) 2015 Elsevier B.V. All rights reserved.

Two types of biomass fuel were gasified in a steam atmosphere using a bench-scale fluidized bed reactor. Filter char, bed material and the product gas stream were sampled and analyzed for a total of 21 elements including Al, Ca, Fe, K, Mg, Na and Si defined as major elements (ME), and Ba, Cd, Co, Cr, Cu, Mn, Mo, Ni, P, Sr, Pb, Ti, V, and Zn defined as trace elements (TE). The effects of the sampling system and gasification system on the measurement were determined. Mass balances for ME and TE are reported for individual elements and overall. It was found that most ash particles or metal elements can be captured by a silicon carbide candle filter that removes small particles from the gas phase, but some of volatile elements pass through the filter and are present in the gas stream.

Previously a lab scale catalytic autothermal reformer (ATR) capable of operating at pressures from 6 to 50bar was constructed and tested. The objective of the experimental program was to maximize H2 production per mole of O2 supplied (H2(out)/O2(in)). In this companion paper a 1-D, heterogeneous, numerical model is developed and tested for simulating the high pressure ATR. The effects of molar steam to carbon (S/C) and oxygen to carbon (O2/C) ratios are studied and optimal operating conditions are identified for three system operating pressures; 6, 28 and 50bar. Experimental optimal conditions and model results are compared and found to be in close agreement. The optimal conditions, however, predicted by the model at pressures of 28 and 50bar have higher S/C ratios and produce higher H2(out)/O2(in) yields than the experimentally determined optimums. A sensitivity analysis consisting of 9 model parameters is also performed. The model is most sensitive to the activation energy of the two steam reforming reactions used in the model and the operating parameter O2/C.

Permanent gas species, tar compounds, sulfur compounds, and ammonia produced from a bench-scale (similar to 1 kg/h) fluidized-bed biomass gasifier were analyzed. Two commercial Ni-based catalysts and one commercial ZnO sorbent were evaluated under varied conditions by quantifying contaminants from the reactor inlet and outlet With Specific sampling and analysis methods. The Ni catalysts targeted tar destruction and ammonia reduction, and the ZnO sorbent was selected for sulfur compound removal. Tar components were identified by gas chromatography-mass spectrometry (GC-MS) and quantified by GC-flame ionization detector(FID). A total of 13 compounds (>= C-6) were identified in raw product gas, principally "lighter tar" Species with an average concentration of 15.5 g m(-3) (dry gas basis). For tar species that were not detected by GC, a gravimetric method was used to quantify the portion of "heavier tar" (5.3 g m(-3) dry gas basis). These data are raw gas tar concentrations for the gasifier-operating conditions used for the remainder of the tests. The performance of two commercial Ni catalysts were evaluated by comparing the concentrations of both "lighter tar" and "heavier tar" after the raw gas passed through the tar reforming reactor. Concentrations of hydrogen sulfide (H2S), carbonyl sulfide (COS), and thiophene (C4H4S) in the raw, dry, product gas averaged 93, 1.7, and 2.2 ppmv, respectively, C4H4S and two additional sulfur compounds, benzothiophene and One unidentified compound (UN I), were found in the tar-trapping Solution. Removal of sulfur compounds using the ZnO sorbent at varied temperatures and gas hourly space velocities (GHSVs) was investigated, The primary sulfur component, H2S, was reduced to less than 1 ppmv; COS was not reduced Significantly; and C4H4S concentrations were not affected at all. The average NO and ammonia concentrations were determined to be 8.2 and 2662 ppmv in the dry gas. respectively. Both were successfully converted to permanent gas species by Ni catalysts.

The adsorption capacity of activated carbon for the natural gas contaminant dimethylsulfide (DMS) was improved by impregnating it with FeCl3 introduced in solution to affect surface modification. A DMS adsorption mechanism and roles of impregnated FeCl3 on the capacity enhancement were proposed based on experimental tests results. Samples of activated carbon and activated carbon impregnated with FeCl3 were tested as DMS sorbents.Samples loaded with DMS were subsequently extracted with n-octane and the resulting solvents were analyzed for sulfur species using a gas chromatograph equipped with a sulfur chemiluminescence detector. No other sulfur Compounds were detected in the liquid samples other than DMS. DMS, dimethyl disulfide, and carbonyl sulfide were recovered from identical DMS-adsorbed samples of activated carbon impregnated with FeCl3 subjected to temperature programmed desorption (TPD) in a nitrogen gas stream. Only DMS was recovered from the activated carbon samples. The TPD patterns indicate different kinetics of DMS desorption related to the carbon phase and the new active sites created by the FeCl3 impregnation. The new active sites improved DMS adsorption capacity and likely had stronger affinity with DMS molecule. As a reference, similar tests were investigated using methyl mercaptan (MM) as an adsorbate on the carbon sorbents. A different adsorption mechanism was found and discussed from these experimental results. Regeneration of the used carbon sorbents by thermal desorption was also explored. (C) 2008 Elsevier B.V. All rights reserved.

Recent interest in fuel cells has led to the conceptual design of an ocean floor, fuel cell-based, power generating station fueled by methane from natural gas seeps or from the controlled decomposition of methane hydrates. Because the dissolved oxygen concentration in deep ocean water is too low to provide adequate supplies to a fuel processor and fuel cell, oxygen must be stored onboard the generating station. A lab scale catalytic autothermal reformer capable of operating at pressures of 6–50bar was constructed and tested. The objective of the experimental program was to maximize H2 production per mole of O2 supplied (H2(out)/O2(in)). Optimization, using oxygen-to-carbon (O2/C) and water-to-carbon (S/C) ratios as independent variables, was conducted at three pressures using bottled O2. Surface response methodology was employed using a 22 factorial design. Optimal points were validated using H2O2 as both a stored oxidizer and steam source. The optimal experimental conditions for maximizing the moles of H2(out)/O2(in) occurred at a S/C ratio of 3.00–3.35 and an O2/C ratio of 0.44–0.48. When using H2O2 as the oxidizer, the moles of H2(out)/O2(in) increased ≤14%. An equilibrium model was also used to compare experimental and theoretical results.

Synthetic natural gas (SNG), which is produced from petroleum and distributed via pipeline in Honolulu by The Gas Company, was analyzed using a gas chromatograph equipped with a sulfur chemiluminescence detector (GC/SCD). Hydrogen sulfide (H2S), methyl mercaptan (MM), ethyl mercaptan (EM), dimethylsulfide (DMS), dimethyl disulfide(DMDS), tetrahydrothiophene (THT), ethyl disulfide (EDS), and one unidentified compound (UN1) were detected. Among these sulfur compounds, THT is added as an odorant and was present in the highest concentration.A commercial activated carbon (Calgon OLC plus 12X30) was modified by oxidation and impregnation methods and the resulting materials were evaluated for their ability to adsorb sulfur compounds present in SING. The evaluation results indicate that all of the modification methods can improve the retention of individual sulfur compounds or the total sulfur capacity compared with the untreated virgin carbon. It is also found that activated carbons impregnated with metal impurities have different selectivity for sulfur compounds. Cu and Zn loaded carbons had the highest capacity for H2S removal, Fe loaded carbon was more efficient for DMS removal (the most difficult S compound to remove), and carbon oxidized by HNO3 was the best for THT removal.Based on these findings, a composite sorbent consisting of Cu loaded and Fe loaded carbons was designed and tested. The test results indicate that the composite sorbent had improved performance in the removal of individual sulfur compound. A linear programming model was used to design a composite sorbent optimized to minimize the required sorbent mass based on a 1-kW scale fuel cell system service target. Validation tests showed that the optimized sorbent required less of the individual modified carbon components than when they were individually used for the same sulfur removal target. (C) 2008 Elsevier B.V. All rights reserved.

A commercial activated carbon (Calgon OLC plus 12X30) was modified by oxidation and impregnation methods. The capacities of the resulting sorbents to adsorb tetrahydrothiophene (THT) were evaluated by conducting breakthrough tests. Carbon modified by oxidation with 50% HNO 3 solution followed by impregnation with 1.05 mmol FeCl 3 per gram sorbent displayed the greatest improvement in THT capacity, increasing from 0.9 mg S per gram of the parent activated carbon to 6.4 mg S per gram of the modified carbon sorbent. Effects of modification on surface physical and chemical properties were investigated using nitrogen sorption, scanning electron microscopy (SEM), and the pH detector. The results indicate that improving THT adsorption capacity is related to the surface acidity/basicity of carbon sorbents, i.e. increasing the acidic groups on the carbon surface improves THT capacity. The surface chemical properties play a more important role than physical properties (such as pore structure) in enhancing the sulfur adsorption capacity of the modified carbons. Impregnated metals also play important roles in THT adsorption and this effectiveness is related to increasing the number of acidic groups on the carbon surface.

Chicken waste and chicken waste blended samples with selected high sulfur coal were used as raw materials for activated carbon preparation. Raw materials were subjected to the preparation procedures of carbonization in a nitrogen atmosphere and activation in a steam atmosphere. The basic properties of the raw materials, chars and activated carbons were investigated by components analysis, surface porosity and thermogravimetric analysis. Two activated carbon samples were selected for elemental mercury capture tests in a lab-scale drop tube reactor with air flow.The current results show that chicken waste is not a suitable raw material for activated carbon production due to its higher contents of volatile matter and ash. Coal can be used as a carbon carrier for improving the carbon content of products. A low-cost activated carbon was prepared by a co-process of chicken waste and coal, and examining the high capture efficiency for elemental mercury. It suggests that the coal provides a carbon carrier or trap for some active species, such as chlorine released from the chicken waste. These active species would likely provide or create the adsorptive sites on the surface of activated carbon for elemental mercury. (c) 2007 Elsevier B.V. All rights reserved.

One of the cost-effective mercury control technologies in coal-fired power plants is the enhanced oxidation of elemental mercury in selective catalytic reduction (SCR) followed by the capture of the oxidized mercury in the wet scrubber. To better understand Hg oxidation chemistry within a SCR, the Institute for Combustion Science and Environmental Technology at Western Kentucky University set up a pilot-scale SCR slipstream facility at a selected utility boiler burning bituminous coal. The greatest benefit of this scaled-down SCR slipstream test is the ability to investigate the effects of Hg oxidation in a SCR using actual flue gas with fly ash included and to isolate and control specific flue-gas compositions with spike gas additions. The average sulfur, chlorine, and mercury contents in the burned coal were 1.67% and 731 and 0.13 ppm, respectively. CaO and Fe2O3 and loss on ignition of the fly ash, which are reported to possibly affect Hg speciation, are approximately 1.65, 14.6, and 2.6% on average, respectively. The maximum concentrations of spike gases were 500, 25, 2000, 50, and 15 ppm for HCl, Cl-2, SO2, SO3, and HBr, respectively. Semicontinuous mercury emission monitors were used to monitor the variation of mercury speciation at the inlet and outlet of the SCR slipstream reactor, and the American Society for Testing and Materials certified Ontario hydro method was used for data comparison and validation. This paper is the first in a series of two in which the validation of the SCR slipstream test and Hg speciation variation in runs with or without SCR catalysts inside the SCR slipstream reactor under special gas additions (HCl, Cl-2, SO2, and SO3) are presented. Effects of HBr additions on mercury speciation within the SCR will be presented in the second part of the series. Tests indicate that the use of a catalyst in a SCR slipstream reactor can achieve greater than 90% NO reduction efficiency with a NH3/NO ratio of about 1. There is no evidence to show that the reactor material affects mercury speciation. Both SCR catalysts used in this study exhibited a catalytic effect on the elemental mercury oxidation but had no apparent adsorption effect. SCR catalyst 2 seemed more sensitive to the operational temperature. The spike gas tests indicated that HCl can promote Hg-0 oxidation but not Cl-2. The effect of Cl-2 on mercury oxidation may be inhibited by higher concentrations of SO2, NO, or H2O in real flue-gas atmospheres within the typical SCR temperature range (300-350 degrees C). SO2 seemed to inhibit mercury oxidation; however, SO3 may have some effect on the promotion of mercury oxidation in runs with or without SCR catalysts.

In this paper, combustion behaviors of two kinds of raw sewage sludge were investigated under air and pure-oxygen atmospheres, and in the case of nitrogen atmosphere, reaction behavior was also investigated as a reference. The overall combustion process can be described as follows: dehydration and devolatilization simultaneously take place from the surface to the interior, then the produced steam and volatiles flow out from the interior, passing though hot layers and react with the char produced from devolatilization. Consequently, volatiles and syn-gas burn around the pellet surface and increase the surface temperature. When the temperature is high enough to melt the ash layers, some small molten droplets were formed and covered the pellet surface. Finally, the remained char combustion facilitates ash droplet agglomeration. Shrinkage and ash agglomeration are the main contributions for volume reduction of raw sludge. The rate-limiting steps in overall reactions were suggested as mass diffusion of water and volatiles.

The response factor of CO2 for mass spectral ( MS) signal in a thermal gravimetry/mass spectrometric (TG/MS) system was determined by decomposition of KHCO3. The influence of TG operation parameters included flow rate of carrier gas, heating rate and sample weight on the shape and intensity of MS. signal has been investigated. The accuracy of this method was tested for pure compounds of NaHCO3, CaC2O4 . H2O and CaCO3. Comparing with the theoretical values, the relative error of this method is about 3% similar to 5%.

The properties of residues from thermal or catalytic coal hydroliquefaction experiments were characterised by the ultimate, proximate analyses. The relations between the properties of the residues and the liquefaction reaction conditions, such as temperature, time, catalyst, H-donor solvent and atmosphere were investigated. Variations in H/C ratio and organic volatile matter (OVM) content of the residues with liquefaction conditions and coal conversion were studied. Results show that liquefaction temperature and time are main factors that control the organic properties of the residues. The roles of the Fe–S catalyst and H-donor solvent are to reduce the proportion of condensation products in the residue rather than increase the extent of polymerisation. Consequently, coal liquefaction conversion is improved by 100% by the catalyst, but H/C ratio and OVM content of the residues are not significantly decreased.

Devolatilization behaviour of residual chars from coal liquefaction was investigated using thermogravimetric analysis. Effect of remained and enriched minerals on devolatilization of residual chars was mainly concerned. By analysing TG/DTG profiles, it was found that the measured volatile matter (VM) includes not only the decomposed volatile products of unreacted organic substances of coal but also that of the inorganic materials, such as enriched mineral matters, remained liquefaction catalyst, as well as by-products formed in catalyst preparation. Therefore, the VM measured by the standard proximate analysis (up to 950°C) should preferably be called ‘total volatile matter’ (TVM), which does not reflect the organic properties of the residue as one would expect for VM. Therefore, the VM released from 110 to 700°C was named organic VM, which shows a better linear relationship with H/C ratios of the residual char and characterises the reactivity of the residue more rationally than TVM does.