Utility power


The AFC fuel-ceU module for the U.S. Apollo space program (57-cm diameter, 112-cm high, - 110 kg, 1.42 kW at 27—31 V, 0.6-kW average power) utilized pure H2 and O2 and concentrated electrolyte (85 wt % KOH) to permit cell operation at lower (ca 400 kPa (58 psi) reactant gas pressure) pressure without electrolyte boiling. Using this concentrated electrolyte, cell performance is not as high as ia the less concentrated electrolyte thus the operating temperature was iacreased to 260°C. The typical performance of this AFC was 0.85 V at 150 m A /cm, which compared favorably to the performance of the original cell operating at about 10 times higher pressure.  [c.579]

Objectives and Types. A specification estabhshes assurance of the fitness of a material, product, process, or service for use. Such fitness usually encompasses safety and efficiency in use as well as technical performance. Material specifications may be classified as to whether they ate appHed to the material, the process by which it is made, or the performance or use that is expected of it. Product or design specifications ate not relevant to materials. Within a company, the specification is the means by which engineering conveys to purchasing what requirements it has for the material to be suppHed to manufacturing. It has its greatest utility prior to and at the time of purchase. Yet a properly written and dated specification with accompanying certificates of test, heat, or lot numbers, vendor identification, and other details pertinent to the actual material procurement constitutes an important archival document. Material specification records provide information regarding a proven successful material that can be used in a new product. Such records also are useful in the rebuilding of components and as defense evidence in a HabiUty suit.  [c.21]

Energy Conservation. Cogeneration of steam and power is usually an integral part of a Bayer plant, unless there is abundant low cost (usually hydroelectric) power available from an existing grid. The cogeneration feature enables fuel efficiencies of >85% compared to ca 35% in pubHc utilities power plants where turbine exhaust steam is merely condensed and recycled rather than being used for process heating.  [c.135]

Some wastewater-treatment plants have utilized pure oxygen in place of air. This permits higher oxygen concentration gradients within the Hquid phase and thus allows higher biomass concentrations (24). The use of pure oxygen requires less energy, but the cost of pure oxygen must be taken into account. The aeration tank is under slight pressure and three stages are usually provided. Mixed Hquor-suspended soHds are 3—10 g/L (11—38 g/gal). Significant increases in volumetric loading rates, reduction in sludge production, and lowered treatment costs are reported.  [c.286]

A fuel cell has no moving parts. It runs quietly does not vibrate, and does not generate gaseous pollutants. The idea of the fuel cell is generally credited to Sir William Grove, who lived in the nineteenth century. It took over 100 years for the first prac tical devices to be built, in the U.S. space program, as the power supply for space capsules and the space shuttle. Commercialization of terrestrial fuel cell systems is beginning only now. Having lower emissions and being more efficient than heat engines, fuel cells may in time become the power source for a broad range of apphcations, beginning with utility power plants, including civihan and military transportation, and reaching into portable electronic devices.  [c.2409]

A variety of applications exist for liquid, 100% solid adhesives, (An adhesive is considered 100% solid if there is no solvent in the adhesive.) Some of the largest uses include structural wood adhesives and adhesives used for the transportation industry, such as windshield adhesives and those used for bonding composite sidewalls of a recreational vehicle (RV). Structural wood adhesives are often made of a polymeric MDI with functionality of approximately 2.7 or higher. Rigid assemblies often utilize polymeric MDI, whereas flexible adhesive assemblies will more often utilize pure MDI, a solid waxy material that melts at around 37°C, or a modified MDI , i.e., MDI that has been modified to make it a liquid at room temperature. Prepolymers are made with ratios of anywhere from NCO/OH = 1.6 to 3.0 or higher.  [c.782]

Utility Data Institute. (1994). Electric Utility Power Plant Construction Costs. Washington DC Utility Data Institute.  [c.415]

The following sections describe the various compliance options for controlling emissions from utility power plants.  [c.446]

For example, sulfur emissions from utility power plants in the United States are subject to an emissions cap and an allowance-trading system established under the Clean Air Act. An effective cap on annual sulfur dioxide emissions took effect in 2000, so no more than 8.95 million tons of SO can be emitted annually. Utilities that want to build another coal plant must purchase sulfur emission allowances from others who do not need them. This system provides a market incentive for utilities to reduce their sulfur emissions as long as the cost of such reductions is less than the price of purchasing the allowances.  [c.1167]

Bolton, H. R. and Ray, N. J., Non-Utility Power Generation Steam Plant. Inst. Mech. Eng. (1989)  [c.859]

Clearly, the time chart shown in Fig. 4.14 indicates that individual items of equipment have a poor utilization i.e., they are in use for only a small fraction of the batch cycle time. To improve the equipment utilization, overlap batches as shown in the time-event chart in Fig. 4.15. Here, more than one batch, at difierent processing stages, resides in the process at any given time. Clearly, it is not possible to recycle directly from the separators to the reactor, since the reactor is fed at a time different from that at which the separation is carried out. A storage tank is needed to hold the recycle material. This material is then used to provide part of the feed for the next batch. The final flowsheet for batch operation is shown in Fig. 4.16. Equipment utilization might be improved further by various methods which are considered in Chap. 8 when economic tradeoffs are discussed.  [c.121]

A more complex utility is combined heat and power (or cogeneration). Here, the heat rejected hy a heat engine such as a steam turbine, gas turbine, or diesel engine is used as the hot utility.  [c.193]

Now let us take a closer look at the two most commonly used heat engines (steam and gas turbines) to see whether they achieve this efficiency in practice. To make a quantitative assessment of any combined heat and power scheme, the grand composite curve should be used and the heat engine exhaust treated like any other utility.  [c.194]

Local and global emissions. When considering utility waste, it is tempting to consider only the local emissions from the process and its utility system (Fig. 10.8a). However, this only gives part of the picture. The emissions generated from central power generation are just as much part of the process as those emissions generated on-site (Fig. 10.86). These emissions should be included in the assessment of utility waste. Thus global emissions are defined to be °  [c.291]

This is particularly important when considering the effect that combined heat and power generation (cogeneration) has on utility waste.  [c.291]

Combined heat and power cogeneration). Combined heat and power generation can have a very significant effect on the generation of utility waste. However, great care must be taken to assess the effects on the correct basis.  [c.291]

Assessing only the local efiects of combined heat and power is misleading. Combined heat and power generation increases the local utility emissions because, besides the fuel burnt to supply the heating demand, additional fuel must be burnt to generate the power. It is only when the emissions are viewed on a global basis, and the emissions from central power generation included, that the true picture is obtained. Once these are included, on-site combined heat and power generation can make major reductions in global utility waste. The reason for this is that even the most modem central power stations have a poor efficiency of power generation compared with a combined heat and power generation system. Once the other inefficiencies associated with centralized power generation are taken into account, such as distribution losses, the gap between the efficiency of combined heat and power systems and centralized power generation widens.  [c.292]

Heat exchanger network and utilities targets. Having established a design for the two inner layers of the onion (reaction and separation and recycle), the material and energy balance is known. This allows the hot and cold streams for the heat recovery problem to be defined. Energy targets can then be calculated directly from the material and energy balance. It is not necessary to design a heat exchanger network in order to establish the energy =costs. Alternative utility scenarios and combined heat and power schemes can be screened quickly and conveniently using the grand composite curve.  [c.401]

With respect to fuels utilized as heating fuels for industrial furnaces, or as motor fuels for large diesel engines such as those in ships or power generation sets, the characteristics of primary importance are viscosity, sulfur content and the content of extremely heavy materials (asphaltenes) whose combustion can cause high emissions of particulates which are incompatible with antipollution legislation.  [c.178]

The nomenclature used in Volume 1 is based on the recommendations of the lUPAC (International Union of Pure and Applied Chemistry) for the system of units utilized as well as for their symbols. The reference is entitled,  [c.493]

The penetration of microwaves in various materials gives active microwave imaging a large potential for subsurface radar, civil engineering etc. Several inverse-scattering theories have been proposed in the scientific literature. Among them, the simplest Bom-type approach, which does not take into account multiple reflections, is valid for weakly scattering objects [1-2]. To improve the quality of reconstruction, the method based on the successive application of the perturbative algorithm was developed [3]. However, the inherent approximations of this approach are not overcome in the iterative scheme. Another class of algorithms aims to obtain the spatial distribution of permittivity by using numerical solutions of exact equations [4-6]. Unfortunately, a rate of convergence of the solution to the global minimum of cost function depends on actual contrast values, measurement error etc. That is why an importance of a priori knowledge about the object imder investigation is usually emphasized. In general, existing inversion algorithms suffer from serious problems when discontinuous profiles of high contrast, which are often encountered in practical applications, are to be reconstructed. Moreover, the frequency-swept imaging methods utilize usually reflection coefficient data measured in a very broad frequency band starting from zero frequency [1-2, 4-5]. Such methods are inappropriate from an application point of view.  [c.127]

TraditioaaHy, wiad turbiaes have operated at coastant rpm to produce 60 Hz a-c power. Because the extra torque geaerated by wiad gusts must be absorbed by the drive traias of coastant speed wiad turbiaes, they requite heavier desigas than comparable variable speed models. By contrast, variable speed turbiaes employ a power electronic converter between the generator and the utility power line. The converter allows the rotor and generator to speed up with gusts or stronger wiads, without increasing drive-train torque. The iacreased rotational energy is converted iato additioaal electricity. Eaergy capture iacreases by 10% or more, and stresses on the turbiae are reduced. The variable speed desiga produces wiad power at a cost of 5 /kW-h, a level that is also achieved ia moderate wiad resources by other, fixed speed turbiaes, eg, the AWT-26, Z, and Z-46.  [c.107]

Design of nonregenerative sorption systems and many regenerative ones often relies on the concept of the mass-transfer zone or MTZ, which closely resembles the constant pattern [Collins, Chem. E/ig. Prog. Syrrm. Ser. No. 74, 63, 31 (1974) Keller et al., sen. refs.]. The length of this zone (depicted in Fig. 16-3) together with stoichiometry can be used to predict accurately how long a bed can be utilized prior to breakthrough. Upstream of the mass-transfer zone, the adsorbent is in equilibrium with the feed. Downstream, the adsorbent is in its initial state. Within the mass-transfer zone, the fluid-phase concentration drops from the feed value to the initial, presaturation state. Equilibrium with the feed is not attained in this region. As a result, because an adsorption bed must typically be removed from service shortly after breakthrough begins, the full capacity of the bed is not utilized. Obviously, the oroader that the mass-transfer zone is, the greater will be the extent of unused capacity. Also shown in the figure is the length of the equivalent equilibrium section (LES) and the length of equivalent unused bed (LUB). The length of the MTZ is divided between these two.  [c.1498]

York, Ontario, New England, New Jersey, and Pennsylvania. The blackout was widespread, and the damages that resulted from looting and panic were extraordinai"y. In response to the outage, the National Electric Reliability Council (now the North American Electric Reliability Council—NERC) was created, with the responsibility to ensure system security and reliable operation. NERC is owned by ten regional coordinating councils consisting of various utilities, power producers, power marketers, and customers. While many other blackouts have occurred since the one in 1965, some affecting millions of customers, none has affected as many customers, and none has had an impact on the indnstiy that was so widespread. This is largely due to the efforts of NERC to study and promote reliability and establish policies, guidelines, and standards conducive to reliable operation.  [c.435]

Vapor-liquid and liquid-liquid equilibria depend on the nature of the components present, on their concentrations in both phases, and on the temperature and pressure of the system. Because of the large number of variables which determine multi-component equilibria, it is essential to utilize an efficient organizational tool which reduces available experimental data to a small number of theoretically significant functions and parameters these functions and parcimeters may then be called upon to form the building blocks upon which to construct the desired equilibria. Such an organizational tool is provided by thermodynamic analysis and synthesis. First, limited pure-component and binary data are analyzed to yield fundamental thermodynamic quantities. Second, these quantities are reduced to obtain parameters in a molecular model. That model, by synthesis, may be used to calculate the phase behavior of multicomponent liquids and vapors. In this way, it is possible to "scale up" data on binary and pure-component systems to obtain good estimates of the properties of multicomponent mixtures of a large variety of components including water, polar organic solvents such as ketones, alcohols, nitriles, etc., and paraffinic, naphthenic, and aromatic hydrocarbons.  [c.2]

When separating a three-component mixture using simple columns, there are only two possible sequences (see Fig. 5.1). Consider the first characteristic of simple columns. A single feed is split into two products. As a first alternative to two simple columns, the possibilities shown in Fig. 5.10 can be considered. Here, three products are taken from one column. The designs are in fact both feasible and cost-effective when compared with simple arrangements on a standalone basis (i.e., reboilers and condensers operating on utilities) for certain ranges of conditions. If the feed is dominated by the middle product (typically more than 50 percent of the feed) and the heaviest product is present in small quantities (typically less than 5 percent), then the arrangement shown in Fig. 5.10a can be an attractive option. The heavy product must find its way down the column past the sidestream. Unless the heavy product has a small flow and the middle product a high flow, a reasonably pure middle product cannot be achieved. In these circumstances, the sidestream is usually taken as a vapor product to obtain a reasonably pure sidestream.  [c.147]

Again, there are two fundamental ways in which a heat pump can be integrated with the process across and not across the pinch. Integration not across (above) the pinch is illustrated in Fig. 6.38a. This arrangement imports W shaftwork and saves IV hot utility. In other words, the system converts power into heat, which is normally never economically worthwhile. Another integration not across (below) the pinch is shown in Fig. 6.386. The result is worse economically. Power is turned into waste heat. Integration across the pinch is illustrated in Fig. 6.38c. This arrangement brings about a genuine saving. It also makes overall sense because heat is pumped from the part of the process which is overall a heat source to the part which is overall a heat sink.  [c.204]

Example 7.4 For the process in Pig. 6.2, the stream and utility data are given in Taible 7.1. Pure countercurrent (1-1) shell and tube heat exchangers are to be used.  [c.230]

When utility waste was considered, it was found that to obtain a true picture of the flue gas emissions associated with a process, both the local on-site emissions and those generated by centralized power generation corresponding to the amount of power imported (or exported) need to be included. In the limit, this basic idea can be extended to consider the total emissions (process and utility) associated with the manufacture of a given product in a life-cycle analysisf In life-cycle analysis, a cradle-to-grave view of a particular product is taken. We start with the extraction of the initial raw materials from natural resources. The various transformations of the raw materials are followed through to the manufacture of the final consumer product, the distribution and use of the consumer product, recycling of the product, if this is possible, and finally, its eventual disposal. Each step in the life cycle creates waste. Waste generated by transportation and the manufacture and maintenance of processing equipment also should be included.  [c.295]

This technology has since been introduced to the fossil power generating industry. To-date, several major utilities including the Termessee Valley Authority, Baltimore Gas and Electric and American Electric Power, as well as many others, have employed this technology to assess the condition of power-generating boiler tubes.  [c.1064]

The practical value of the Boltzmaim equation resides in tlie utility of the predictions that one can obtain from it. The fomi of the Boltzmaim is such that it can be used to treat systems with long range forces, such as Leimard-Jones particles, as well as systems with finite-range forces. Given a potential energy frmction, one can calculate the necessary collision cross sections as well as the various restituting velocities well enough to derive practical expressions for transport coefficients from the Boltzmaim equation. The method for obtaining solutions of the equation used for fluid dynamics is due to Enskog and Chapman, and proceeds by finding solutions that can be expanded in a series whose first temi is a Maxwell-Boltzmaim distribution of local equilibrium fomi. That is, the first takes the fomi given by (A3.1.55). witli the quantities A, p and u being fimctions of r and t. One then assumes that the local temperature, (/rgP) mean velocity, u, and local density, n, are slowly varying in space and time, where the distance over which they change, L, say is large compared with a mean free path, L. The higher temis in the Chapman-Enskog solution are then expressed in a power series in gradients of the five variables, n, p and u, which can be shown to be an expansion in powers of l/L < 1. Explicit results are then obtained for the first, and higher, order solution in / /L, which in turn lead to Navier-Stokes as well as higher order hydrodynamic equations. Explicit expressions are obtained for the various transport coefficients, which can then be compared with experimental data. The agreement is sufficiently close that the theoretical results provide a usefiil way for checking the accuracy of various trial potential energy fimctions. A complete account of the Chapman-Enskog solution method can be found in the book by Chapman and Cowling [3], and comparisons with experiments, the extension to polyatomic molecules, and to quantum gases, are discussed at some length in the books of Hirslifelder et al [4], of Hanley [5] and of Kestin [VT as well as in an enomious literature.  [c.686]

Wlien sweeping the magnetic field through resonance, a crystal detector renders a slowly varying DC signal which is not readily processed and which is superimposed by low-frequency noise contributions. To overcome this, a phase-sensitive detection teclmique utilizing small-amplitude magnetic field modulation is employed in most EPR spectrometers. Modulation of the magnetic field is achieved by placing a pair of Helmlioltz coils on each side of the cavity along the axis of the external magnetic field. An alternating current is fed tlirough them and a small oscillating magnetic field is induced which is superimposed on the external magnetic field. The effect of the modulation is depicted in figure BL15.5. Provided the amplitude of the modulation field is small compared to the linewidth of the absorption signal, A B 2> 1 2 change in MW power at the detector will contain an oscillatory component at the modulation frequency whose amplitude will be proportional to the slope of the EPR line. A lock-in detector compares tlie modulated EPR signal from the crystal with a reference and only passes the components of the signal that have the proper frequency and phase.  [c.1561]

Flence tire orbital energies of occupied orbitals pertain to interactions appropriate to a total of N electrons, while the orbital energies of virtual orbitals pertam to a system with A-r 1 electrons. This usually makes SCF virtual orbitals not very good for use in subsequent correlation calculations or for use in interpreting electronic excitation processes. To correlate a pair of electrons that occupy a valence orbital requires double excitations into a virtual orbital of sunilar size the SCF virtual orbitals are too diflfiise. For this reason, significant effort has been devoted to developing methods that produce so-called improved virtual orbitals (IVOs) [46] that are of more utility in perfomiing correlated calculations.  [c.2173]

Stresses during drying can be minimized by controlled humidity drying, by supercritical drying, or by freeze drying. Controlled humidity drying utilizes a high-humidity atmosphere during tire critical, initial stage of drying to maintain a liquid film on tire (solid) surface of the ware (i.e. a solid-liquid interface). Supercritical drying is accomplished by heating ware under pressure in an autoclave until tire liquid becomes a supercritical fluid (i.e. botli a liquid and a vapour simultaneously), after which drying can be accomplished by isotliennal depressurization to remove tire vapour. Supercritical drying is often used to avoid generating catastrophic capillary stresses during tire drying of fme-pore materials such as gels. Freeze drying makes use of freezing and sublimation to minimize drying stresses due to capillarity. In freeze drying, tire temperature of tire ware is initially decreased to below tire freezing point of tire liquid.  [c.2767]

The manufacture of ceramics starts witli tlie constituent raw materials and carries tlirough to tliennal consolidation. Intennediate processing steps include raw material beneficiation, shape fonning, and pre-sinter tliennal processing. Surfaces are created, modified, and eliminated during ceramic powder processing. Optimizing ceramic manufacturing requires understanding and controlling tlie physical chemistry of surfaces and interfaces during the various unit process steps. The control and utilization of surface energy and surface curvature are critical. Surface tension creates pressure gradients that contribute to tlie agglomeration and rearrangement of particles in powders, to tlie migration of liquids during mixing, shape fonning, and drying, and to pore slirinkage during sintering. Chemical potential gradients associated witli surface curvature detennine tlie solubility of any particles in liquids, control tlie rate of evaporation from solid surfaces, and drive material transport during sintering. In combination witli a strong engineering component, robust ceramic processing requires understanding and controlling tlie physical chemistry of surfaces.  [c.2772]

The utility of a protein model depends upon the use to which it is put. In some cases, on< only interested in the general fold that the protein adopts and so a relatively low-resoluti structure is acceptable. For other applications, such as drug design, the model must be me more accurate, including the loops and side chains. In such cases, a poor model may often fa r worse than no model at all, as it can be seriously misleading.  [c.563]


See pages that mention the term Utility power : [c.494]    [c.494]    [c.67]    [c.242]    [c.293]    [c.264]    [c.284]    [c.1235]    [c.1246]    [c.1559]    [c.2864]    [c.167]    [c.863]   
See chapters in:

Surface production operations Ч.2  -> Utility power


Surface production operations Ч.2 (1999) -- [ c.494 ]