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The first objective of this work was to compare the pyrolysis behavior of coals coming from different geographic locations (South Africa, South America, Europe, Australia, and North America). This preliminary study was limited to the kinetics of methane and tar evolution, with data on additional species to be reported in a separate publication. The second objective was to examine the possible relationship between tar and methane evolution during pyrolysis. This study was done by employing a thermogravimetric analyzer coupled with a Fourier-transform infrared spectrometer (TG-FTIR). The evolution curves for 35 coals of different elemental compositions were measured at three different heating rates (10, 30, and 100 K/min). Pyrolysis kinetics were described using a simple first-order reaction model. The technique, first proposed by Kissinger, is based on the variation of the temperature at which a volatile species evolution rate is a maximum (Tmax) as a function of the heating rate. The TG-FTIR data for tar evolution reveal a generally consistent behavior for coals from different parts of the world, showing increasing activation energies with increasing coal rank. The same correlation is also true for methane, although the slope of the activation energy versus carbon content curve is rather flat, at least up to about 90% carbon content. The values of activation energies for methane evolution were found to be lower in the case of the Argonne coals, as compared with the non-US coals. A study of the temperatures at which the evolution of methane and tar begins (Tini), and the temperatures at which the evolution rates reach a maximum (Tmax), reveals a correlation between the Tini for methane and Tmax for tar. This may be due to the fact that both tar and methane evolve as a result of similar reactions involved in the breakup and recombination of the coal macromolecular network.

The subject of this paper is mitigation of the undesirable side-effects of selective non-catalytic reduction (SNCR) and selective catalytic reduction (SCR): ammonia slip, residual NO x , and N 2 O emissions. The use of microwave-plasma discharge within the flue gas was explored as a potential pollution-control method. The key issues addressed were: (1) N 2 O, NH 3 , and NO removal efficiencies; and (2) sustaining a stable plasma at atmospheric, or close to atmospheric, pressure. In non-oxidizing atmospheres, removal efficiencies were always close to 100% for all species. In the presence of oxygen, however, appreciable amounts of nitric oxide and ammonia were formed. Methods leading to preventing these undesirable effects were examined. In a number of runs, stable plasma operation was attained at pressures close to atmospheric.

The desirable characteristics of activated carbons for gas-storage applica tions are: (1) high microporosity (pores smaller than 2 nm) ; and (2) high sorbent packing density, i.e., low voidage in the storage container (e.g., the use of mono lithic sorbent elements). A cyclic chemisorption-desorption char activation tech nique was used to maximize micropore formation and minimize mesoporosity. Several carbons were prepared at different degrees of burn-off, and the BET surface areas were found to be up to 2000 m2/g. The carbons were prepared in the form of powders and pellets to demonstrate that the future use of shaped mono lithic elements can lead to the reduction of voidage in the storage container by up to 40%. The adsorption isotherms of the produced carbons showed high microporosity and no appreciable mesoporosity, even at high burn-offs. The advantage of using the cyclic chemisorption-desorption char activation technique over the traditional steady-state gasification was experimentally demonstrated. The paper also discusses the evolution of sorbent microporosity as a function of carbon burn-off and the duration of the chemisorption step. Preliminary data on hydrogen-storage capacity are also reported.

The interest in utilizing biomass as a CO2 neutral fuel by combustion, gasification, or pyrolysis processes is increasing due to concern about the emission of greenhouse gases from fossil fuel combustion. In thermal fuel conversion, pyrolysis is an important step which determines the split of products into char, tar, and gas. In this work, a combination of thermogravimetry and evolved gas analysis by Fourier transform infrared analysis (TG-FTIR) has been applied to study the influence of potassium chloride (KCl) on wheat straw pyrolysis. Raw straw, washed straw, and washed straw impregnated with KCl have been investigated. To facilitate interpretation of the results, pyrolysis of biopolymers (cellulose, xylan, lignin) in the presence and absence of KCl was investigated as well. The raw straw decomposed in a single broad featureless peak. By washing, two peaks appeared in the derivative weight loss curve, corresponding to the decomposition of hemicellulose and cellulose components in the straw. Washing red...

Over the next decade there will be a renewed emphasis on the use of biomass as a fuel and the cofiring of coal and biomass materials. In view of the tremendous diversity of biomass feedstocks, a great need exists for a robust, comprehensive model that could be utilized to predict the composition and properties of pyrolysis products as a function of feedstock characteristics and process conditions. The objective of this work was to adapt an existing coal pyrolysis model, the Functional Group-Depolymerization, Vaporization Crosslinking (FG-DVC) model, and make it suitable for the pyrolysis of biomass. The soundness of this approach is based on numerous similarities between biomass and coal. However, there are important differences, which preclude direct application of the coal model. This work involved: (1) selection of a set of materials representing the main types of biomass, (2) development of a classification scheme, (3) development of a modeling approach based on an extension of a coal pyrolysis model, (4) calibration of the model for a set of standard materials against pyrolysis data taken over a range of heating rates, and (5) validation of the model against pyrolysis data taken under higher heating rate conditions. A streamlined version of the FG-DVC coal pyrolysis model was successfully developed for whole biomass samples and demonstrated to have predictive capability when extrapolated to high heating rate conditions (103 °C/sec). Improvements will be needed in the model to properly account for mineral effects and secondary reactions, and the model has not yet been tested under the very high heating rates that may exist in some combustion devices (104–105 °C/sec).

This paper continues previous work on pyrolysis processing of solid wastes for spacecraft and planetary surface applications. A prototype microwave pyrolyzer apparatus was designed, constructed and tested. Experiments were done with cellulose, wheat straw and two formulations of a feces simulant. A central microwave absorber was used consisting of a quartz tube filled with activated carbon. The pyrolyzer included a primary pyrolysis zone and a secondary cracking zone consisting of a SiC bed. The cracking zone temperature ranged from ~ 850 to 1000 °C. The sample was inserted into the (primary) microwave heating zone after the cracking bed temperature was stabilized to ~ 950 °C. Analysis of the gas products was performed by both FTIR spectroscopy and mass spectrometry. The sample sizes were 15-20 g for wheat straw, 40 g for cellulose and 100 g for the feces simulants. The cellulose sample was not run to completion, but was interrupted to provide photographic evidence that microwave heating using a central microwave absorber results in pyrolysis beginning near the center of the sample and proceeding in an outward fashion. For the wheat straw and feces simulant samples, it was found that, on a per-gram basis, the yields of ethylene, methane, and hydrogen were significantly higher than a previous pyrolyzer that was based on a modified domestic microwave oven. This result was mainly attributed to the presence of a separate cracking zone in the current pyrolyzer.

Radiation pyrometry and thermometry combined with fiber optics provide sensors for determining surface and gas temperatures in otherwise inaccessible locations. However several applications require that temperature measurements be made in the long-wavelength infrared (LWIR) where widely used silica fibers are nontrasmissive. This study involved the development and testing of hollow sapphire fiber-optic radiometric temperature sensors that operate in the LWIR. Hollow sapphire waveguides are suitable for use at high temperatures and transmit in the LWIR: no currently available solid-core fiber offers this combination of features. A prototype fiber-optic radiometric temperature sensor was assembled for the LWIR spectral region, and several experiments were performed to demonstrate the feasibility of developing a system that could be used in gas turbine applications. Open-tip and closed-tip hollow sapphire waveguides were used as the sensor probes and were coupled to an FT-IR spectrometer using hollow glass waveguides. Both types of sensors were tested in laboratory facilities and the closed-tip configuration was also used in a jet engine test rig. The principal findings can be summarized as follows: (1) Open-tip hollow sapphire waveguides were demonstrated to be useful sensors for remote pyrometric temperature measurements in the LWIR. Analysis of calibration data predicted an error level of less that 1% of the reading at 800°C. (2) Closed-tip hollow sapphire waveguides were demonstrated to be useful sensors for radiometric gas temperature measurements in the LWIR. (3) It was determined that interference ence caused by hot H2O and CO2 emission in the open-tip configuration could be eliminated through careful selection of the analyzed spectral region. (4) It was found that interference caused by heating of the waveguide walls in either configuration could be eliminated by limiting the throughput of the optical system.

Significant improvements in efficiency for electricity generation from coal can be achieved by cycles that employ a high-temperature, highly recuperative gas turbine topping cycle. The principal difficulty of employing a gas turbine in a coal-fired power generation system is the possible erosion and corrosion of the high-temperature rotating gas turbine components caused by the coal’s inorganic and organically bound constituents (ash, sulfur, and alkali metals). One route to overcome this problem is the development of an externally fired gas turbine system employing a coal fired heat exchanger. The solution discussed in this paper is the design of a Radiatively Enhanced, Aerodynamically Cleaned Heat-Exchanger (REACH-Exchanger). The REACH-Exchanger is fired by radiative and convective heat transfer from a moderately clean fuel stream and radiative heat transfer from the flame of a much larger uncleaned fuel stream, which supplies most of the heat. The approach is to utilize the best ceramic technology available for high-temperature parts of the REACH-Exchanger and to shield the high-temperature surfaces from interaction with coal minerals by employing clean combustion gases that sweep the tube surface exposed to the coal flame. This paper presents a combined experimental/computational study to assess the viability of the REACH-Exchanger concept. Experimental results indicated that the REACH-Exchanger can be effectively fired using radiation from the coal flame. Both computation and experiments indicate that the ceramic heat exchanger can be aerodynamically protected by a tertiary stream with an acceptably low flow rate.

There have been several studies on the devolatilization of large coal particles under laboratory conditions simulating large-scale fluidized or fixed-bed combustion conditions, all of which demonstrate that the process of devolatization of large coal particles occurs over a much longer timescale than that of pulverized coals under the same conditions. This paper reports the development of a model for large coal particle devolatilization under fluidized and fixed-bed combustion conditions. The model combines a heat transfer model with a general and comprehensive coal devolatilization model, FG-DVC. It inherits the generality of FG-DVC and can be applied to coals of various types without extensive prior knowledge of the coals. This model includes a detailed treatment of coal pyrolysis reactions including the yields of individual gas species, tar yields, and tar molecular weight distributions. The changes in coal physical properties are modeled with the application of Merrick's coal physical property submodels for specific heat and thermal conductivity. Both the convective and radiative heat transfer between the gas phase and coal particles are considered and Gunn's correlation for the surface heat transfer coefficient is used. Model predictions are compared with the data of large coal particle devolatilization measured in fluidized beds and tubular reactors, for particle thermal response, total weight loss, and individual gas evolution rates. In general, the agreement with the data is very good for the particle center temperature and weight loss curves and is fair for the individual gas evolution curves.

A methodology to determine the chemistry and kinetics of the multiple reactions during geological maturation was developed, with a special emphasis on the representation of diagenesis and oil formation processes. The methodology combines a unique macromolecular and kinetic model for hydrocarbon pyrolysis, the FG-DVC (functional group-devolatilization, vaporization, cross-linking) model, with a method of analysis based on thermogravimetric analysis with Fourier transform infrared spectroscopy (TG-FTIR). TG-FTIR pyrolysis data from several natural maturation series of coals and kerogens were measured, systematic trends with the degree of maturation were identified, and empirical processes and reaction kinetics during maturation necessary to induce these trends were estimated. This approach eliminates potential inaccuracies when extrapolating kinetic parameters obtained from laboratory experiments to geological conditions. The FG-DVC pyrolysis model was modified to include these maturation processes, with aqueous chemistry providing a guide for such modifications. The resulting FG-DVC maturation model was then used to predict the maturation of several immature samples through the well-known time/temperature history of the basin. The FG-DVC pyrolysis model was subsequently used to predict the open-system pyrolysis decomposition of the predicted maturation residues, and the predictions were compared to TG-FTIR data of the corresponding naturally matured samples. For most of the series investigated, the model gave good predictions of the variations in oxygenated gas precursors, tar T max , and extractable yield with maturation. Kinetics derived from open-system pyrolysis for bridge breaking were found to be applicable during maturation. However, faster kinetics were necessary to describe the removal of oxygenated gas precursors. In addition, the removal of methane and tar was found to be too slow during maturation when using open-system pyrolysis kinetics. Artificial maturation experiments using confined pyrolysis were also performed for comparison. While the evolution rates, during subsequent pyrolysis of the maturation residues, of oxygenated gas species are different from those obtained from samples naturally matured, the yields compare favorably with model predictions. The trends for pyrolysis tar and methane from artificially matured samples are similar to those of natural samples but suggest different kinetics.

Landfilling used tires which are generated each year in the US is increasingly becoming an unacceptable solution. A better approach, from an environmental and economic standpoint, is to thermally reprocess the tires into valuable products such as activated carbon, other solid carbon forms (carbon black, graphite, and carbon fibers), and liquid fuels. In this study, high surface area activated carbons (> 800 m{sup 2}/g solid product) were produced in relatively high yields by pyrolysis of tires at up to 900 C, followed by activation in CO{sub 2} at the same temperature. The surface areas of these materials are comparable with those of commercial activated carbons. The efficiency of the activation process (gain in specific surface area/loss in mass) was greatest (up to 138 m{sup 2}/g original tire) when large pieces of tire material were used ({approximately} 170 mg). Oxygen pretreatment of tires was found to enhance both the yield and the surface area of the carbon product. High-pressure treatment of tires at low temperatures (< 400 C) is an alternative approach if the recovery of carbon black or fuel oils is the primary objective.

There has recently been an increased interest in using pyrolysis of mixed solid wastes in space or on planetary surfaces to produce methane for applications in propulsion and for power generation using fuel cells. This paper involves a review of previous pyrolysis results collected at Advanced Fuel Research, Inc. (AFR) and elsewhere to determine how the pyrolysis conditions and feedstock composition affect methane yields. In general, the production of methane from primary pyrolysis of most biomass materials is pretty modest, 0.1 to 2.5 wt. % for a wide range of materials, with an average slightly above 1.2 wt. % (dry, ash-free basis). The primary pyrolysis yield variations for methane (and other species) with biomass sample type are well described using a simple Neural Network model. In pyrolysis experiments that include significant secondary reactions (e.g., tar cracking), the methane yield can be increased by a factor of 2-3. The methane yield can also be increased significantly by increasing the plastic component of the mixed waste stream (e.g., by the addition of polyethylene), but would be unlikely to exceed 15 wt. % by conventional, low-pressure pyrolysis of a typical mixed waste stream. The use of high pressure (>500 psig) pyrolysis in pure hydrogen is one approach that could be used to increase the methane yield even further. However, this approach would require a much heavier reactor unit, high pressures, and the associated safety concerns. An alternative pathway to higher methane yields would be to oxidize the waste completely to carbon dioxide and water and use the Sabatier reaction to convert the carbon dioxide to methane.

Results are presented on the development of regenerable trace-contaminant (TC) sorbents for use in Extravehicular Activities (EVAs), and more specifically in the Primary Life Support System (PLSS). Since ammonia is the most important TC to be captured, data presented in this paper are limited to ammonia sorption, with results relevant to other TCs to be reported at a later time. The currently available TC-control technology involves the use of a packed bed of acid-impregnated granular charcoal. The sorbent is non-regenerable, and its use is associated with appreciable pressure drop, i.e. power consumption. The objective of this work is to demonstrate the feasibility of using vacuum-regenerable carbon sorbents for PLSS application. In this study, several carbon monoliths were fabricated and tested. Multiple adsorption/vacuum-regeneration cycles were demonstrated at room temperature, as well as carbon surface conditioning that enhances ammonia sorption without impairing sorbent regeneration. Depending on sorbent monolith geometry, the reduction in pressure drop with respect to granular sorbent was found to be between 50% and two orders of magnitude.

The desire to employ a range of pure fuels as surrogates for jet fuels has led to an increased need for detailed oxidation reaction mechanisms. These mechanisms require a good pyrolytic base mechanism. Furthermore, aircraft cooling requirements beyond those of conventional fuels has led to research into so called “endothermic” fuels. Unlike conventional fuels, whose heat sink capabilities are derived solely from sensible and latent enthalpies, endothermic fuels offer additional heat sink potential through endothermic chemical reaction. Endothermic fuels play an important role in cooling for hypersonic craft. To date, heavy iso-alkanes, an important hydrocarbon class present in logistical fuels, have not received much analysis with respect to their pyrolytic decomposition or endothermic potential. Yet such compounds are likely to be present in large fractions in future alternate fuels. This paper presents the development of computational suband supercritical pyrolysis mechanisms for iso-dodecane (i.e., 2,2,4,6,6-pentamethyl heptane). Both proposed mechanisms utilize Wang et al.’s small species (C4 and below) reactions and Curran et al.’s isooctane model for large species reactions. Utilizing fuel structure similarities, reactions involving iso-dodecane are patterned after those for iso-octane. Standard group additivity techniques are used to estimate associated kinetic rate parameters as necessary, and several parent fuel activation energies are compared with ab-initio (Gaussian) calculations. Reactions necessary to model supercritical environments are also presented. The sub-critical mechanism is benchmarked against several literature reactor data-sets, and the new supercritical mechanism is compared to newly acquired UTRC non-isothermal rig data.

An interpolation method was proposed to correlate the input parameters of a coal devolatization model[functional group-depolymerization, vaporization, cross-linking (FG-DVC)] to coals of a wide range of ranks, and it conceptually applicable to other devolatilization models. This method uses a set of well-defined coals (library coals) to form a triangular mesh in the van Krevelen diagram. If an unknown coal is within a triangle formed by three library coals, the model input parameters for this unknown coal can be interpolated from those of the three library coals based solely on the elemental composition. This method extends the FG—DVC model to be able to model any coal that can be interpolated, without the requirement for any additional characterization of the coal. It is also easy to accommodate more library coals so that a wider range of coal types can be covered. The validity of this method was demonstrated by comparing the tar yield measurements and the predictions for 27 coals over a wide range of pressures and heating rates. For most of the coals, the predictions compare very well with the data. For selected coals, data were available on the variation of the yield of total volatiles with pressure and heating rate, and again, good agreement was obtained. The model could be improved by using additional parameters to describe the exchangeable cation content, sulfur content, and/or the maceral composition.

Pyrolysis of lignin is one approach that has been investigated to upgrade this material into higher value products. However, there have been relatively few efforts to quantitatively model these reactions. This paper describes a methodology for modeling lignin pyrolysis which has been extensively developed for related materials like coal. The samples are characterized using pyrolysis experiments under a standard set of conditions, where the products are analyzed by Fourier Transform Infrared (FT-IR) Spectroscopy and Field Ionization Mass Spectrometry (FIMS). Solvent extraction experiments are done to determine the extractables yields and elemental analysis is done to further constrain the model. One lignin, produced from ethanol/water extraction of mixed hardwoods, was selected for the application of this modeling approach. The model was able to qualitatively predict the tar molecular weight distributions and quantitatively predict the variations of the gas and tar evolution rates and yields with heating rate for the calibration set of experiments. The model can be improved by more precise information on lignin structure, crosslinking chemistry, and tar transport mechanisms. It also needs to be validated by simulation of pyrolysis conditions at high heating rates and/or high pressures for which data is currently not available.

A test instrument was developed and used to characterize the changes in the thermal and optical properties of charring polymeric materials when exposed to radiative heat fluxes. The system is based on a bench-top emissometer apparatus, which was developed originally to simultaneously measure the surface temperature and spectral properties of materials at elevated temperatures and was modified in this work to study charring polymers. An advantage of using a modified emissometer is that the front surface temperature is measured optically instead of with a thermocouple. Time-resolved measurements of the front surface temperature, along with thermocouple measurements of the interior and back surface temperatures can provide information on the changes in thermal conductivity and thermal diffusivity with the extent of charring, assuming that the heat of gasification is known. In addition, this apparatus measures the changes in the material's spectral emissivity and functional group composition as it chars. Data are presented for experiments on two different samples of 3.2-mm-thick polyurethane, heated using radiant fluxes from 22 to 32 kW/m2. Analysis of the surface temperature and emissivity data indicates that the samples undergo a transition from a volume to a surface absorber during initial irradiation. Quantification of this behavior will be a critical element in predicting the flammability limits of these materials.

The recent nuclear crisis at Fukushima, Japan is a stark reminder that radiation emergencies can and do happen. In addition to accidents, the potential use of radioactive materials by terrorists has raised serious concerns. While the primary concern has been with preventing these materials from entering the United States, thousands of dangerous radiological sources are already here within our borders, located in vulnerable locations in hospitals, food processing plants, and industrial sites. These sources pose a risk for use in two terrorist threats described by the Department of Health and Human Services (DHHS): the Dirty Bomb and the Silent Source. In a Dirty Bomb attack, radioactive material is dispersed using a conventional explosive. In a Silent Source attack, radioactive material is hidden in locations where people congregate (restaurants, airports, subway stations, shopping malls, etc.). Both scenarios can injure or kill people and cause significant political, social and economic disruption. This paper will describe the GammaPixTM technology, which has the potential to provide low cost, pervasive detection of, and warning against, radiation threats. The GammaPix technology is based on software analysis of the images produced by a surveillance or smartphone camera to measure the local gamma-ray radiation exposure at the device. The technology employs the inherent gamma-ray sensitivity of CCD and CMOS chips used in the digital image sensors of these devices. This paper describes the use of the technology in calibration and testing scenarios using installed video cameras and smartphone cameras.

In this paper, results of further work on pyrolysis processing of mixed solid wastes for spacecraft applications are reported. A domestic microwave oven was modified for scoping studies in which the effects of sample size and the use of distributed versus central microwave absorbers were studied. Experiments were done with wheat straw and included those in which the sample was rotated during pyrolysis in order to improve heating uniformity. The experiments using central microwave absorbers of various compositions included a ferrite rod, a quartz tube filled with activated carbon, and silicon carbide. The ability to monitor the sample temperature and sample heating uniformity during microwave heating was demonstrated. A comparison was made with conventional pyrolysis experiments in an electrically heated furnace to a similar final temperature. In general, it was found that microwave heating reduced the energy demand by about 50% and increased the yield of gas products by about 100%, while reducing the char yield about 20%.

Sulfur and nitrogen evolution from the Argonne Premium coals has been studied using thermogravimetric analysis with measurement of evolved products by Fourier transform infrared spectroscopy (TG-FTIR). The method combines temperature-programmed pyrolysis and combustion. H 2 S and tar sulfur were monitored by measuring SO 2 after oxidation of volatile products. The SO 2 evolution curves produced with volatile oxidation erhibit two main evolution peaks and one smaller high-temperature evolution peak. For each peak, the temperature of the maximum evolution rate (T max ) increases with increasing rank. The individual evolution curves of the organic and pyritic sulfur were identified, and their evolution kinetics were derived

An experimental technique is described that combines tomography, Hadamard signal encodement, and a patented Fourier transform infrared (FT‐IR) emission/transmission (E/T) technique to perform simultaneous spatially resolved gas species and soot measurements during combustion. Tomographic analysis of line‐of‐sight FT‐IR data allows spatially resolved measurements to be made. Hadamard encodement of the tomographic sections increases the overall signal throughput, improving the signal to noise (S/N) ratio for each measurement. The Hadamard technique leads to a major simplification in the tomographic apparatus in that the scanning apparatus that would normally be required is eliminated, and focusing of the infrared light is much easier. An experiment demonstrating Hadamard data processing as applied to FT‐IR tomography is described. Deconvolution of the encoded data is shown to be accurate and gives the predicted improvement in S/N ratio. The FT‐IR Hadamard tomography is performed to measure soot in a fuel‐ri...

This paper considers the development of a predictive macromolecular network decomposition model for coal conversion which is based on a variety of modern analytical techniques for coal characterization. Six concepts which are the foundation of the functional group-depolymerization-vaporization-cross-linking (FG-DVC) model are considered: 1. (1) The decomposition of functional group sources in the coal yields the light gas species in thermal decomposition. The amount and evolution kinetics can be measured by t.g.-FT-i.r., the functional group changes by FT-i.r. and n.m.r. 2. (2) The decomposition of a macromolecular network yields tar and metaplast. The amount and kinetics of the tar evolution can be measured by t.g.-FT-i.r. and the molecular weight by f.i.m.s. The kinetics of metaplast formation and destruction can be determined by solvent extraction, by Gieseler plastometer measurements and by proton magnetic resonance thermal analysis (p.m.r.t.a.). 3. (3) The molecular weight distribution of the metaplast depends on the network coordination number (average number of attachments on aromatic ring clusters). The coordination number can be determined by solvent swelling and n.m.r. 4. (4) The network decomposition is controlled by bridge breaking. The number of bridges broken is limited by the available donatable hydrogen. 5. (5) The network solidification is controlled by cross-linking. The changing cross-link density can be measured by solvent swelling and n.m.r. Cross-linking appears to occur with evolution of both CO2 (before bridge breaking) and CH4 (after bridge breaking). Thus low-rank coals (which evolve much CO2) cross-link before bridge breaking and are thus thermosetting. High-volatile bituminous coals (which form little CO2) undergo significant bridge breaking before cross-linking and become highly fluid. Weathering, which increases the CO2 yield, causes increased cross-linking and lowers fluidity. 6. (6) The evolution of tar is controlled by mass transport in which the tar molecules evaporate into the light gas or tar species and are carried out of the coal at rates proportional to their vapour pressure and the volume of light species. High pressures reduce the volume of light species and hence reduce the yield of heavy molecules with low vapour pressures. These changes can be studied with f.i.m.s. The paper describes how the coal kinetic and composition parameters are obtained by t.g.-FT-i.r., solvent swelling, solvent extraction and Gieseler plastometer data. The model is compared with a variety of experimental data in which heating rate, temperature and pressure are all varied. There is good agreement with theory for most of the data available from the authors' laboratory and in the literature.

The drilling industry routinely encounters formations with pore pressures that are lower than anticipated. In some cases, these pore pressures require specialized treatments to control the loss of whole drilling fluid. A massive loss of whole drilling fluids, whether water-based or oil-based, can be costly, result in nonproductive time (NPT), and if encountered near potential productive zones, also result in damage to the producing capability once completion has been performed. Key wellbore data, such as actual hole size versus drilled hole size, accurate bottomhole circulating temperature (BHCT), and placement technique with optimum bottomhole assembly (BHA) for accurate placement of treatment design is critical for job success. Placing a successful treatment for the control of whole mud losses and to minimize possible formation damage can be a complex and often expensive undertaking. Numerous solutions have been identified in the industry ranging from effective bridging or lost circulation material (LCM) incorporated in the mud to complete process solutions such as crosslinked fluid structures to ultimate cement slurries. The damage that is left as a result of the fluids pumped is a major disadvantage of most systems. This paper presents a novel approach using a rigid setting fluid (RSF) that can be engineered to maintain a low viscosity during placement and activate by temperature to transition from a fluid to a set state almost immediately to effectively control further losses to the formation. In addition, using the right angle set (RAS) created by the exothermic reaction, the system can tolerate contamination of extraneous fluids up to 50% and still provide adequate compressive strength. Lastly, the material is soluble in acid with a predicted 99% regained permeability. A case history will be presented where the RSF treatment was used and effectively controlled, eliminating further whole mud losses to the weak formation.

The main objective of the current work was to develop a char reactivity submodel that could be used in a comprehensive code for entrained coal combustors and gasifiers. The requirement of a char reactivity model is to predict the reactivity of chars from a wide range of coals, over a wide range of temperatures, and for various degrees of burnoff. In order to predict intrinsic reactivity, correlations of reactivity with char hydrogen content, coal oxygen content and coal mineral content were used. A random pore model (high rank coals) and a volumetric model (low rank coals) were included to predict variations of intrinsic reactivity with burnoff. The correlations combined with those models gave good predictions of reactivity (within a factor of 2 to 4) and reactivity variations with burnoff (within 20%) for the range of chars studied. In the pore diffusion regime, the model uses the Thiele modulus to calculate the reaction rate as a function of the intrinsic rate (obtained using the correlations) and char properties such as porosity, tortuosity and mean pore radius. Predictions of reactivity required an estimate of the tortuosity and the mean pore radius. The tortuosity was kept constant at a value of 2. Using a value of 6(corresponding to the size of micropores) for the mean pore radius led to good predictions of the onset of diffusion limitations for low heating rate, fluid chars. For high heating rate chars, pore size distribution measurements showed that values of approximately 100were more appropriate. The corresponding predictions using this value gave a fairly good fit of the literature data investigated. This analysis shows that it may be possible to extend a low temperature reactivity model to high temperatures.

Pyrolysis is a very versatile waste processing technology which can be tailored to produce a variety of solid, liquid and/or gaseous products. The pyrolysis processing of pure and mixed solid waste streams has been under investigation for several decades for terrestrial use and a few commercial units have been built for niche applications. The use of pyrolysis as a key step in solid waste processing in space has been under consideration by NASA for several years. A large component of the solid waste is from biomass sources (e.g., paper, food waste, human waste). A methodology has been developed to characterize a large number of biomass materials using a standard pyrolysis experiment in combination with a neural network model in order to classify the data. Such a methodology can be helpful in the design and operation of pyrolysis reactors for spacecraft applications.

We have developed a TG-FT-IR instrument which combines thermogravimetric analysis (TGA) with evolved product analysis by Fourier Transform Infrared (FT-IR) spectroscopy. FT-IR analysis of evolved products has an advantage over mass spectroscopy in allowing analysis of very heavy products, and over gas chromatography in speed. This paper describes the most recent improvements in the apparatus and presents its application in characterizing coal. The emphasis in this work is on employing the TG-FT-IR system to obtain kinetic rates for species evolution under easily obtained laboratory conditions. These rates can then be extrapolated to predict the conversion behavior of the hydrocarbon at higher heating rates and temperatures in practical conversion processes or at lower heating rates and temperatures in geological conversion processes. For several coal samples, a kinetic analysis was applied to species evolution data collected at several different heating rates. For coal, there is a systematic variation in rate with rank for almost all volatile species. Extrapolation to high temperatures shows excellent agreement with high temperature coal pyroloysis data. Extrapolation to low temperatures is consistent with the expected changes induced by bed temperatures over geological times.

During a sidetrack operation out of 9 7/8-in. casing on a deepwater well in Green Canyon Block 243, Gulf of Mexico, unexpected hole conditions were encountered that required the use of an additional casing string. The decision was made to run a 7 5/8 x 9 5/8-in. expandable liner in the 8 1/2 x 9 1/2-in. wellbore. The liner would expand to provide an inside diameter of 7.71 in., allowing space for a 7-in. production liner in the targeted interval. The 6,867-ft liner (pre-expansion length) is currently the world record for the longest expandable liner set to date and presented several challenges for cement job design. The liner would be cemented conventionally before the expansion operation. Expansion time was calculated to be approximately 17 hours, allowing the fluid time for the primary lead cement, with a safety factor, to exceed 19 hours. The tail cement had to exhibit good compressive strength around the shoe track, and the operator specified top of cement (TOC) at 17,000 ft to protect a secondary pay zone. Slurry properties were simulated to meet fluid times required for the liner expansion. Standard API lab tests used for cement testing were modified to accommodate this lengthy operation. The expandable liner was set at 20,605 ft measured depth (MD) and 19,930 ft true vertical depth (TVD) with a maximum hole angle of 36°. The liner was cemented successfully using an extended thickening-time lead slurry mixed at 15.7 lb/gal, followed by a 16.2-lb/gal tail slurry with a shorter pumping time to achieve good strength at the liner shoe. After drilling out the liner, the operator obtained a 16.8-lb/gal equivalent (PPGE) formation integrity test (FIT) and resumed drilling to the target depth. The cement-evaluation log showed excellent bonding behind the expandable liner with TOC at 17,000 ft as planned. Operational details and cement design considerations are provided in the paper. Emphasis is placed on wellbore configuration, expandable installation procedures, and hole preparation, a full understanding of which is the beginning of a successful cement job.

Several groups have considered statistical network fragmentation models to describe coal thermal decomposition. In these models, the coal macromolecule is viewed as a collection of fused aromatic rings (monomers) linked by bridges. During thermal decomposition, existing bridges break and new bridges are formed. The parameters of the models are the geometry of the network, which is expressed as the number of attachments per monomer (the coordination number, σ + 1), and the chemistry of bridge breaking and formation. Given σ + 1 and the instantaneous number of unbroken and formed bridges, the molecular weight distribution can be predicted. The different groups have employed both Monte Carlo methods and percolation theory to describe the network statistics. The former approach has advantages in terms of describing both the depolymerization and crosslinking processes in coal decomposition, since it does not require a constant coordination number. The latter method provides closed form solutions and is computationally less demanding. The models differ in the geometry of the network, the chemistry of bridge breaking and bridge formation (crosslinking) and the mass transport assumptions. This paper considers for three such models: the mathematical schemes; the assumed network geometries; the assumed bond breaking and bond formation chemistries; and the mass transport assumptions. The predictions of three models were compared by comparing the oligomer populations as a function of the number of unbroken bridges per ring cluster. This paper also presents results from a new model which combines the geometry, chemistry and mass transport assumptions of the FG-DVC model with the mathematics of a modified percolation theory.

This paper describes the most recent improvements in the apparatus and presents its application in characterizing the Argonne premium coal samples. The TG-FTIR apparatus for pyrolysis, oxidation of pyrolysis products, and oxidation of the sample is described. To analyze coal, a sequence of drying, pyrolysis, and combustion is employed to obtain proximate analysis, volatile composition, volatile kinetics, and relative char reactivity. Pyrolysis results are presented for the eight Argonne coals, several demineralized coals, and two oxidized samples of Pittsburgh Seam coal. A kinetic analysis was applied to species evolution data collected at several different heating rates. There is a systematic variation in rate with rank

During coal conversion, the breakup of the coal macromolecular network and resulting product formation are controlled by the relative rates of bond breaking, cross-linking, and mass transport. THe objective of this work was to systematically study the variations in cross-linking with several parameters (rank, temperature, heating rate, pretreatment, etc.), to identify the factors that control cross-linking rates. This paper describes a study of cross-linking behavior in which chars of a number of coals (including the Argonne premium coal samples) have been pyrolyzed under a variety of temperature histories and analyzed at intermediate extents of pyrolysis for solvent swelling behavior and functionnal group compositions

Fluid trapped in the annulus of subsea wells can cause casing strings to fail. This condition occurs when casing annuli attain a closed-volume circumstance (when a well is cased, cemented, and head seals are set). During production, the heat transfer of the produced fluids to the casing strings causes the trapped fluid to increase in pressure. This condition is magnified in deepwater because annular fluids are cooler due to the cold deepwater environment. Laboratory testing indicates that thermal expansion of these fluids can cause trapped water- or oil-based fluids to increase in pressure above casing-collapse pressure, resulting in annular pressure buildup (APB). This paper outlines a simple laboratory procedure and resulting data to determine the resulting trapped-volume pressure. Data from eight fluid combinations are presented. The temperature change during testing is an increase from 80°F to 230°F. The testing relates to the conditions commonly found in deepwater Gulf of Mexico. The laboratory data obtained from this testing was used to design a spacer system for Walker Ridge 285 #1, a deepwater, subsea well located in the Gulf of Mexico. This paper also presents the job design and related procedure for the executed spacer system.

Pyrolysis processing is one of several options for solid waste resource recovery in space. It has the advantage of being relatively simple and adaptable to a wide variety of feedstocks and it can produce several usable products from typical waste streams. The overall objective of this study was to produce a prototype mixed solid waste pyrolyzer for spacecraft applications. A twostage reactor system was developed which can process a maximum of about 0.5 kg of waste per cycle. The reactor includes a pyrolysis chamber where the waste is heated to temperatures above 600 °C for primary pyrolysis. The volatile products (liquids, gases) are transported by a N2 purge gas to a second chamber which contains a catalyst bed for cracking the tars at temperatures of about 1000-1100 °C. The tars are cracked into carbon and additional gases. Most of the deposited carbon is subsequently gasified by oxygenated volatiles (CO2, H2O) from the first stage. In a final step, the temperature of the first stage can be raised and the purge gas switched from N2 to CO2 and/or O2 in order to gasify the remaining char in the first stage and the remaining carbon deposits in the second stage. Alternatively, the char can be removed from the first stage and saved as a future source of CO2 or partially gasified to make activated carbon. This paper describes several improvements that were made in the original (First Generation) prototype pyrolyzer including: 1) replacement of stainless steel flanges with machineable ceramic in order to reduce weight; 2) construction of a new sample holder in order to make sample insertion and removal easier and sample heat-up more uniform; 3) replacement of a stainless steel outer shell with a double-wall quartz cylinder in order to significantly reduce weight and heat losses. In addition, experimental results are included for wheat straw and chicken manure feedstocks, primarily from the First Generation prototype.

Pyrolysis processing is one of several options for solid waste resource recovery in space. It has the advantage of being relatively simple and adaptable to a wide variety of feedstocks and it can produce several usable products from typical waste streams. The objective of this study is to produce a prototype mixed solid waste pyrolyzer for spacecraft applications. A two-stage reactor system was developed which can process about 1 kg of waste per cycle. The reactor includes a pyrolysis chamber where the waste is heated to temperatures above 600°C for primary pyrolysis. The volatile products (liquids, gases) are transported by a N2 purge gas to a second chamber which contains a catalyst bed for cracking the tars at temperatures of about 1000 °C – 1100 °C. The tars are cracked into carbon and additional gases. Most of the carbon is subsequently gasified by oxygenated volatiles (CO2, H2O) from the first stage. In a final step, the temperature of the first stage can be raised and the purge gas switched from N2 to CO2 in order to gasify the remaining char in the first stage and the remaining carbon deposits in the second stage. Alternatively, the char can be removed from the first stage and saved as a future source of CO2 or used to make activated carbon. The product gases from the pyrolyzer will be rich in CO and cannot be vented directly into the cabin. However, they can be processed in a shift reactor or sent to a high temperature fuel cell. A control system based on artificial neural networks (ANNs) is being developed for the reactor system. ANN models are well suited to describing the complicated relationships between the composition of the starting materials, the process conditions and the desired product yields.

The NASA objective of expanding the human experience into the far reaches of space will require the development of regenerable life support systems. A key element of these systems is a means for solid waste resource recovery. The objective of this work was to demonstrate the feasibility of pyrolysis processing as a method for the conversion of solid waste materials in a Controlled Ecological Life Support System (CELSS). A pyrolysis process will be useful to NASA in at least four respects: 1) it can be used as a pretreatment for a combustion process; 2) it can be used as a more efficient means of utilizing oxygen and recycling carbon and nitrogen; 3) it can be used to supply fuel gases to fuel cells for power generation; 4) it can be used as the basis for the production of chemicals and materials in space. A composite mixture was made consisting of 10% polyethylene, 15% urea, 25% cellulose, 25% wheat straw, 20% Gerepon TC-42 (space soap) and 5% methionine. Pyrolysis of the composite mixture produced light gases as the main products (CH4, H2, CO2, CO, H2O, NH3) and a reactive carbon-rich char as the main byproduct. Significant amounts of liquid products were formed under less severe pyrolysis conditions, but these were cracked almost completely to gases as the temperature was raised. A primary pyrolysis model was developed for the composite mixture based on an existing model for whole biomass materials. An artificial neural network model was also used successfully to model the changes in gas composition with the severity of pyrolysis conditions.

The objective of this work was to determine if C60 or its derivatives could enhance the oxidative thermal stability of JP-5 and similar aviation fuels. Two derivatives of C60 were prepared, n-hexyl amine and di-isopropylamine. Several conventional thermal stressing experiments were also performed: oxygen overpressure (OOP), isothermal corrosion oxidation test (ICOT), quartz crystal microbalance (QCM), and hot liquid process simulator (HLPS). In addition, a fuel stability test system (FSTS) developed at Advanced Fuel Research, Inc. (AFR) was also used. The FSTS includes fiber optic infrared transmission cells to assess fuel thermal stability during thermal stressing up to 500 deg C. The low temperature data from OOP, ICOT, QCM and HPLS show that pure C60 generally reduces the deposit formation, although the amount of this reduction is only modest (between 5 and 30%). The beneficial effects are larger under more severe conditions (higher temperatures, longer oxidation times, higher oxygen concentrations). The FSTS results were consistent with this trend, although at the highest temperatures (425-500 deg C), some potentially deleterious effects of C60 also appear to be enhanced. The effects of reactor tube activation were important for the FSTS. Additional work is warranted on exploring the beneficial effects of C60 addition which could serve to extent the operating range of common jet fuels.

OVERVIEW 1. Chemistry of Advanced Materials 2. New Horizons in the Structure and Properties of Layered Materials CHEMICAL VAPOR DEPOSITION SYNTHESIS AND SURFACE CHARACTERIZATION 3. Chemical Considerations Regarding the Vapor-Phase Epitaxy of Binary and Ternary III-Nitride Thin Films 4. Autocompensated Surface Structure of GaN Film on Sapphire 5. In Situ Monitoring by Mass Spectrometry of Laser Ablation Plumes Used in Thin Film Deposition 6. Fullerenes and Polymers Produced by the Chemical Vapor Deposition Method 7. Chemical Vapor Deposition of Organic Compounds over Active Carbon Fiber To Control Its Porosity and Surface Function 8. Recombination of Oxygen and Nitrogen Atoms on Silica and High-Temperature Coating Materials SOLUTION SYNTHESIS AND CHARACTERIZATION 9. Application of Chemical Principles in the Solution Synthesis and Processing of Ceramic and Metal Particles 10. Precursors for Aqueous and Liquid-Based Processing of Ferroelectric Thin Films 11. Nucleation and Formation Mechanisms of Hydrothermally Derived Barium Titanate 12. Glycothermal Synthesis of Alpha Aluminum Oxide 13. Synthesis and Characterization of a Trimetallic Double-Alkoxide Precursor to Potassium Aluminosilicate 14. Synthesis of *b"-Alumina Polymer Precursor and Ultrafine *b"-Alumina Composition Powders PYROLYSIS AND COMBUSTION SYNTHESIS AND CHARACTERIZATION 15. High-Rate Production of High-Purity, Non-Agglomerated Oxide Nanopowders in Flames 16. In-Situ Particle Size and Shape Analysis During Flame Synthesis of Nanosize Powders 17. Reactants Transport in Combustion Synthesis of Ceramics 18. A Comparison of the Syntheses of V, Nb, Mo Carbides and Nitrides by Temperature Programmed Reaction POLYMERIZATION SYNTHESIS AND CHARACTERIZATION 19. Frontal Polymerization: Self-Propagating High-Temperature Synthesis of Polymeric Materials 20. Synthesis and Characterization of Linear Tetraphenyl Tetramethyldisiloxane Diacetylene Copolymers 21. Blending Studies of Poly(siloxane acetylene) and Poly(carborane siloxane acetylene)

An on-line carbon-in-ash monitor based on in-situ infrared emission spectrometry is described. Laboratory measurements of the infrared spectral emissivity of flyash are presented in order to demonstrate that emissivity can be correlated to the residual carbon content in the range of interest for pulverized coal-fired power plants. Data collected during a field test at a pilot-scale combustor are presented in order to demonstrate that the emissivity measurements could be made in situ on a realistic facility, and that the spectral emissivity could be correlated to the residual carbon content. Since this measurement can be made in-situ in a few seconds using an FT-IR spectrometer, an infrared emissivity based carbon-in-ash monitor will be capable of providing data on a time scale appropriate for implementation in combustion control strategies while avoiding the disadvantages associated with extractive ash sampling.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Recently, infrared transmitting optical fibers have been employed for remote spectral analysis of processes such as composite curing and polymerization of polyurethane. By imbedding the fiber in the sample, spectra can be obtained by measuring the attenuation of the evanescent wave that penetrates into the sample. This method, fiber optic attenuated total reflectance (FO/ATR), provides a minimally invasive technique for probing the chemistry occurring inside the sample during processing. The purpose of this work is to extend FO/ATR to the analysis of harsh liquid process streams that are difficult to monitor using other techniques.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

been hindered by the lack of reliable instrumentation and test methods to evaluate these fuels.This paper describes the use of an insitu FT-JR fiber optic probe to monitor the growth andcomposition of deposits from thermal stressing of jet fuel A high temperature (500°C), highpressure (700 psig) heated flow cell was constructed and equipped with a sapphire fiber as anAttenuated Total Reflectance (ATR) element. At the outlet of the system, a Spectra Tech ATR

The development of diagnostic instrumentation for monitoring coal liquefaction process streams is discussed. A sapphire optical fiber was used as an attenuated total reflectance (ATR) element in conjunction with Fourier transform infrared (FT-IR) spectrometry to probe harsh liquefaction process streams. ATR provides a short, reproducible pathlength which allows for the analysis of highly absorbing materials, such as liquid hydrocarbons, and the properties of sapphire are well suited for the analysis of high temperature and high pressure process streams. A test cell was constructed which allowed in-situ monitoring of coal liquefaction reactions at 400 degree(s)C and 3000 psig. The cell incorporated a sapphire optical fiber as an ATR sensing element which was coupled to an FT-IR spectrometer using zirconium fluoride fiber optic cables. The spectra provide qualitative information about the liquefaction process.

The overall objective of this project was to elucidate and model the dual role of oxygen functions in thermal pretreatment and liquefaction of low rank coals through the application of analytical techniques and theoretical models. The project was an integrated study of model polymers representative of coal structures, raw coals of primarily low rank, and selectively modified coals in order to provide specific information relevant to the reactions of real coals. The investigations included liquefaction experiments in microautoclave reactors, along with extensive analysis of intermediate solid, liquid and gaseous products. Attempts were made to incorporate the results of experiments on the different systems into a liquefaction model.