This chapter develops a system resembling a CO2 scrubber that can provide a route to safe, long-term sequestration of CO2 from, for example, fossil-fuel-burning power plants. It has been estimated that an amount of carbon equivalent to 150,000 × 1012 tonnes of CO2 is naturally sequestered in the form of carbonate minerals, such as calcite, aragonite, dolomite, and dolomitic limestone, which thus constitute the earth's largest CO2 reservoir. Mineralization is attractive as a possible route to carbon sequestration because it offers the potential for safe storage of very large quantities of CO2 over very long time periods, as demonstrated by the geological record. This would, of course, minimize risks and monitoring requirements, and facilitate licensing. Produced waters offer a particularly attractive because of the potential to improve cost effectiveness for sequestration while also benefiting the oil and gas industry. In active production areas such as the Permian Basin, substantial amounts of brine are already being produced, transported, and re-injected. Some of these produced waters are used in water flooding for secondary production, but most constitute a waste product requiring disposal.

The objective of our research is the development of a system resembling a CO2 scrubber, in which carbonic anhydrase catalyzes the rate of CO2 hydration for subsequent fixation into stable mineral carbonates. The present focus is on the use of produced waters as one of various possible sources of the counterions for precipitation. Carbonate precipitation has been studied from synthetic brines corresponding to a range of compositions of produced waters from the Permian and San Juan Basins, and promising results have been obtained with carbonic anhydrase. CO2 sequestration capacities are estimated to be 0.49–1.85×103 tonnes CO2/year and 1.28–2.80×105 tonnes CO2/year for the San Juan and Permian Basins, respectively, per cycle, up to ∽3mt CO2 per year total, based on the volumes of produced waters in 2002.

Chitosan and alginate are two polyelectrolytes that can be used as thickening agents in the food industry, in drug-release systems in pharmaceutical applications as biomaterials in wound healing, and cell culture applications, or as ion exchange material for the removal of heavy metal ions from industrial wastewaters. These two polysaccharides can also be used together to form a polyelectrolyte complex, especially to encapsulate proteins, cells, and enzymes. Although there are many applications of these polyions, few publications explain the interaction between their functional groups. This is mostly because of the difficulty of following ionic interaction in an interface of macromolecules, especially since they alter much with the reaction conditions such as pH. The present study reveals the interaction between chitosan and alginate at different pH values by means-of a particular method for Fourier transform infrared (FTIR) studies. A previously reported disagreement between the yield of the complexes in weight and density of the interacting functional groups is explained through this method. The obtained results are supported with the morphological studies of the polyelectrolyte beads prepared at different pH values. Freeze-dried beads of both alginate and chitosan-coated alginate beads could be viewed after hexamethyl disilazane (HNIDS) treatment. (C) 2003 Wiley Periodicals, Inc.

AbstractIn recent years, considerable experience and insight regarding the behavior of materials and components in the bubbling pressurized fluidized-bed combustion (PFBC) of coal has been developed, largely as a result of the operation of a fleet of 80-MW(e) PFBC-based power plants installed by ABB Carbon. The first plant went into operation over 10 years ago and it appeared timely to review this practical experience and to document areas where improvements have been made, or can be suggested.In keeping with general bubbling-bed experience, the in-bed heat exchanger and water-wall tubes experienced metal loss. Other plant areas that experienced difficulties were the hot-gas cyclone system, the gas-turbine expander, and some balance-of-plant items including solids-handling equipment, valving, and expansion joints. The captured dust removal lines from the cyclones sometimes plugged sending high dust loadings over to the turbine expander. Consequently the turbine blades experienced material deposition and significant erosion damage. Concerns about turbine longevity in this application have led to attempts to develop high-temperature filter systems that protect the turbine by removing all the dust from the flue gas prior to expansion. These filters have themselves suffered from a range of materials problems, which is not unexpected for a relatively new technology. The current experience of these and other materials issues is reviewed.Keywords: bubbling pressurized fluidized-bed combustion of coal

AbstractMany industrial and commercial sectors are made up of separate, relatively small components: aerospace and ground transport, for example. In such applications, truly smart materials systems (SMS) are defined as those that respond autonomously to changes in their operating conditions. That is, they detect the onset of “illness” and take steps to effect a cure. In contrast, the electric power industry is a vast, interconnected enterprise, not a collection of individual entities. It is a far‐flung grid, fed and drained continuously at variable rates. SMS must be consistent with this character: owing to the extent of the grid and the way it operates, just detecting illnessand determining its locationconstitutes smartness. Moreover, users of electricity expect reliability everywhere the grid reaches, so avoiding failures (outages) is paramount. Thus,distributedSMS are often required to achieve reliability. Some other sectors (e.g., highways) also will rely on distributed SMS, but in electricity systems the SMS must function under more hostile conditions of temperature, pressure, aggressive chemicals, and especially, intense electric and/or magnetic fields. Early detection of deviations or trouble is vital. In a sense, successful performances of SMS in the power industry equates to buying time for a rational response. Whatever else they might do by way of autonomous responses (derating a unit, eliminating an ailing component from a redundant set, etc.), the crucial action for SMS in electricity systems is to notify a central authority about an (impending) illness and where that illness is.Although investment in SMS research by the power industry has been substantial, utilization of SMS within the industry is still in the early stages. There is little doubt, however, that the influence of SMS will be profound in the future. This article discussed where smart materials can be used in the power production process and challenges awaiting smart materials solutions.

The enzyme, carbonic anhydrase, is the biological catalyst responsible for the interconversion of CO(2) and bicarbonate in living organisms. The present research is aimed at the development of a CO(2) scrubber that can be used to reduce CO(2) emissions from, for example, fossil-fuel-burning power plants. In this system, the enzyme works as a catalyst to accelerate the rate of CO(2) hydration for subsequent fixation into stable mineral carbonates, the counterions for which may be supplied from such sources as brines from saline aquifers, waste brines from desalination operations, or seawater. Proof of principle has already been demonstrated. One of the requirements for the enzyme will be that it must be able to function in the presence of other chemical species likely to be present in the industrial application. The present results show excellent enzyme activity in the presence of low levels of SO(x) and NO(x) (that might be expected from flue gases) and also in solution representative of seawater. The effects of SO(x) and NO(x) are of interest because, although emissions of these species are strictly controlled, some very low level will still be present. The reason for examining enzyme performance in seawater-like solutions is to give a better approximation of the compositions likely in actual process streams based on either seawater or other brines.

This paper reports initial results from a laboratory fluidized bed test rig where HCl gas was incorporated into the bed. The rig simulates the particle hammering interactions between in-bed particles and tubes within bubbling fluidized bed combustors (BFBCs). A significant increase in material wastage rates in the presence of HCl was found at 450°C as well as at 200°C. The detrimental effect decreased with decreasing HCl concentration.

Heat-exchanger tubes in fluidized bed combustors (FBCs) often suffer material loss due to combined corrosion and erosion. The effect of chlorine on in-bed tube wastage and its possible mechanism are being studied using the EPRI/LBNL FBC wastage simulator. This test rig was designed to simulate dense particle impacts on tube bottoms with well-controlled parameters, and has been proven to closely reflect situations found in operating bubbling FBCs. In this study, HCl gas was chosen to be the Cl source and was introduced into the fluidizing air with a 50-ppm concentration. Tests were performed at temperatures ranging from ambient to 400°C using 1018 low carbon steel rods in a bed of commercial SiO2 sand that had an average size of 800 μm. The wear profile after each test was measured using a profilometer. Results showed an increase in material wastage rates in the presence of HCl, and that the rate was significantly higher with higher test temperatures. Microstructural and chemical analysis of the wear surface and corrosion products are reported. It is concluded that the dominating effect of HCl on the wastage rates is due to an enhanced oxidation and a reduced scale adherence.

Reduction of the emissions of greenhouse gases, such as CO2, is currently the subject of extensive research. A novel strategy is put forward here, based on a biomimetic approach providing accelerated deposition into carbonate form for long-term sequestration. It offers the advantages of a process that: does not require concentration of CO2 from flue gases; could potentially be used in an on-site scrubber to provide a plant-by-plant solution to reducing CO2 emissions; is an environmentally benign procss with an environmentally benign product; and is based on readily available, low-cost reagents (except perhaps the catalyst).

The papers presented in this volume focus on today's materials technology for land-based and aircraft gas-turbine engines. While they emphasize the materials for these applications, they also include practical ideas of inspection, life assessment, repair, refurbishment, and reliability. The contents include: The DOD and NASA materials programs for propulsion systems; Manufacturing needs for advanced turbines; Vane and blade materials; Rotor and disc materials; Inspection and lifetime-assessment techniques; Methods for gas-turbine inspection and health monitoring; Materials repairs; Refurbishment; and Reliability.

High temperature corrosion problems in coal-based power plant have been matters of concern since the very early days of using the combustion of coal to raise steam to generate electricity. The early problems could be separated into water-wall corrosion, typically at temperatures in the range 350 - 450 degrees C; and superheater and reheater corrosion, typically at metal temperatures in the range 500 - 650 degrees C. These issues have changed in the last few years for a number of reasons, including demands for higher efficiency, procedures adopted to reduce NOx emissions, and cost pressures to use lower-grade fuels.Solutions to high-temperature corrosion problems include the selection of more corrosion-resistant materials of construction; the use of protective coatings and claddings; and modification of the process or the design to reduce the aggressiveness of the conditions experienced by the components at riskIn addition, it is increasingly necessary to develop instrumentation capable of measuring the extent of corrosion, preferably in a non-intrusive way that can be applied to plant in service; and 'lifing models' that will allow the planning of maintenance outages, help with run-repair-replace decisions, and allow the penalties associated with performance different from the original design conditions to be quantitatively assessed.

The paper summarizes our present understanding, as established at a recent workshop, of two classes of intermetallic alloys: nickel and iron aluminides, which are currently used by industries; and advanced intermetallic alloys including silicides and Laves-phase alloys, which have a great potential to be developed as new high-temperature structural materials for future industrial use. The workshop emphasized close interaction and co-operation between basic research, applied research, and industrial development, and stressed discussion of critical scientific and technological issues. The current status of these intermetallic alloys was assessed, and the directions for future research and development, as well as emerging opportunities, were identified. The information presented in the text is summarized from the presentations at the workshop, and so no references are given to the published literature. However, an extensive bibliography is appended, in which further details may be found.