Other considerations

Other difficulties can be caused by different feedstocks being used in different parts of the world to make similar products, such as natural versus synthetic feedstocks, which are different in their composition. 

The ideal situation would be to find a supplier that has manufacturing capabilities around the world using cormnon feedstocks so the same product would be available everywhere. 

Reality sometimes falls short of this ideal and compromises must be made. The compromises are determined by what is best for your comparty at the time. Will slightly different material work in one area and do what is required Do you need a uniform product around the world  

Global implementation adds a new dimension to the process. It is relatively easy to pick a preferred supplier and move business to them in North America. If you are doing business in Europe, Asia, or even Africa, there are matty other factors that can enter the picture. Some of these are  

If operations are being supplied by imports from North America, it will require longer delivery times and thus require the maintenance of higher raw material or product inventory levels. This will tie up working capital. With the focus of maity businesses on lean manufacturing and just-in-time inventories some creative results will be required to make this competitive on a global scale. 

Other considerations affecting the efficiency of the plating process were the voltage used, the agitation of the bath and the cathode surface area. 

The system ran at two volts. As the voltage was increased the plating process was less efficient or failed to work. 

Agitating the solution increased the efficiency of the plating operation. Therefore an electric stirrer was made and installed in the process. 

The surface area of the cathode was also important in increasing the efficiency of the plating operation. The aluminum wire was coiled in 

Some other considerations relative to polymer reactivity are as follow  

Polymer reactivity can also be affected by the conformation of polymer chains [Imanishi, 1979 Overberger et al., 1973 Overberger and Morimoto, 1971 Pshezetsky et al., 1968], Whether the polymer chain exists in a tight or expanded coil can influence the accessibility of polymer functional groups and the local concentration of a small-molecule reactant. 

The functional groups in a number of polymers are not of the same reactivity. For example, the hydroxyl groups in cellulose (VIII) are of different reactivities. The hydroxyl at C-2 is reported to be slightly more reactive than that at C-6, which is about 

4 times more reactive than the hydroxyl at C-3 [Lenz, I960]. Reaction of cellulose leads to a nonuniform distribution of reacted groups. Another report shows no reactivity difference between the secondary hydroxyls at C-2 and C-3 [Jain et al., 1985], The 

Almost all the other considerations are the same as those for teaching nuclear engineering students discussed earlier. 

Harvin, Leray and Roudier (Ref. PTI p.183) make several conclusions in their assessment of the advantages of each process. They conclude that the two processes may be economically competitive under particular conditions. Also selection of a process 

Their final comment was that In the USA, the relatively low raw materials and utilities costs, together with the methods of plant finance, make the trade-off between these factors opt in favour of the single-pressure process for plants built up to 1979 . 

In electric-field poling, a guest dipolar chromophore and a chemically and optically passive host polymer (the chromophore can also be covalently tethered to the polymer [74] or incorporated into the main chain of the polymer) is heated to above the glass transition temperature, Tg, of the mixture. A large electric 

It has also been found that chromophores based on 4-(diarylamino)phenyl donors exhibit enhanced thermal stability relative to 4-(dialkylamino)phenyl analogs, presumably because of their lack of a-hydrogens adjacent to the nitrogen (Fig. 11.9) [78, 80, 93, 94], 

High-performance Electooptic Poled-polymer Systems 

Electrooptic coefficient measured for poled host-guest systems with the chromophore weight percentage in parentheses. 

We mentioned in the previous section that the bulk NLO properties of a poled-polymer host-guest system might be expected to be proportional to the chromophore fi/3 multiplied by the number density of chromophores. However, for high loadings of molecules with large pi, the d33 and r33 coefficients do not continue to increase linearly with chromophore loading, but exhibit maxima these are attributed to competition between the interaction of the chromophores and the poling 

Since hydrogen sulfide is highly toxic and a leak from the pipeline could be catastrophic, it is recommended that the line be kept as short as possible. The disposal well should be near the plant, but off-site. The pipeline should therefore be from several hundred meters to two 

The pipeline is usually buried to a depth of 2 m (6 ft) to minimize freezing concerns. The line should be equipped with extensive redundant instrumentation to ensure complete safety and integrity of the system. 

Additional safety considerations for the entire injection scheme are discussed in other chapters. But again, safety is paramount. 

The acid gas is transported from the compressor to the injection well in a pipeline. The design of such a pipeline follows that standard practice for all lines. 

In addition, the line is filled with a highly toxic mixture. Therefore, safety must be paramount in the mind of the design engineer and in that of the operators. 

The strengthening of H-bonds that occurs when one of the two partners is charged can be sufficient to form H-bonds between C atoms. For example, a recent crystal structure revealed that a proton can bind together the C atoms of a pair of imidazole species. The H-bond is apparently noncentrosymmetric with r(C—H) distances of 2.03 and 1.16 A the bond is within 8° of being linear. 

There are certain manifestations of H-bonds which are either centrosymmetric or in which the transfer potential contains a broad minimum, or a pair of minima separated by a low barrier. In such cases, the proton position can be easily shifted by external influences and its vibration extends over a wide amplitude. Consequently, the infrared spectrum con- 

COMPOSITION OF WOOD-PLASTIC COMPOSITES COUPLING AGENTS 

Some contributors to the field believe that maleated polymers do not form covalent bonds with hydroxyl groups of the filler but rather form ionic bonds via interactions with ionic groups on its surface. It is known, for example, that cellulose fiber contains many cationic and anionic groups on its surface. 

However, adding of inorganic materials into a WPC formulation with a coupling agent can complicate an outcome. For example, addition of nanoclay to WPC (50% wood flour and 50% polypropylene) in the presence of Polybond 3200 has systematically decreased both tensile and flexural strength of the final material, for amounts of the nanoclay of 0, 2,4, and 10%. Effect of tensile and flexural modulus was more complex. The authors concluded that the nanoparticles disrupt adhesion between wood flour and the polymer matrix [24]. 

Polypropylene-based maleated coupling agents can be used in HDPE-based WPCs, particularly if a small amount of polypropylene is added to the system. Table 5.11 compares two HDPE-based composites, containing rice hulls and Bio-dac as cellulosic/mineral fillers, with Polybond 3009 (HDPE-based) and Polybond 3200 (polypropylene-based). As one can see, in all the cases both flexural strength and modulus are significantly increased. 

TABLE 5.11 Effect of Polybonds 3009 (HDPE-based) and Polybond 3200 (polypropylene based) on flexural strength and flexural modulus of HDPE-based composites 

In the previous example it was assumed that the CO boiler would receive its feed water from existing equipment. The cost of deaerators and related feed water equipment would increase the investment somewhat. Also, running feed water piping a considerable distance to the CO boiler was assumed not to be required in the example. 

The value of fuel and the richness of the regenerator flue gas vary widely in different refineries. Industry practice o varies as to the value of adiabatic temperature maintained in a boiler to sustain the conversion of CO to CO2. A tempera-uire range of 1,600° to 1,800° F is normally considered acceptable. 

At the higher level, 1,800°F, more auxiliary fuel is burned than if a lower adiabatic furnace temperature is used. This fuel is not wasted since it generates steam, but it has some influence on economic justification because it requires the recovery unit to be slightly larger than if less auxiliary fuel were burned. 

If the CO boiler represents 10 to 30% of the r.eam supply, a sudden shutdown is obviously undesirable. This point must be given very careful consideration for a plant located in an area with no connections for electric power or steam outside the sjiant. 

Most CO boilers are conservatively rated for economic justification and actually save more fuel and supply more steam than their rated capacity indicates. 

Semiempirical molecular orbital methods have long been a mainstay for the prediction of NLO properties, particularly with sum-over-states methods, and much of our understanding of how molecular properties affect NLO prop- 

Basis Set Basis Functions C, N, O/H Acetylene C2H3 p-Nitroaniline NOjCgH NHj 

As an alternative to Hartree-Fock semiempirical and ab initio calculations, density functional theory has been used to obtain nonlinear optical properties in both the finite field and TDHF (or time-dependent Kohn-Sham) approaches. 

If one can measure the acceptor decay kinetics due only to RET, they will display the unique properties of an exdted-state reaction. In the time doinain, the characteristics (ff an excited-state reaction are a rise time in the decay and a negative preexponential frBtor in (he mnitiex ponentlal analy In the frequency domain, (he phase angles of the acceptor can exceed 90°. These characteristic features are the result of the acceptor being excited by the donor, rather than directly. These features can be hidden by spectral overlap of the donor and acceptor emission spectra and by decay of directly excited accqitor. Exdted-state reactions are described in more detail in Chapter 18. 

Doing Volunteer Work if your study schedule allows, volunteer for a few hours a week to help those in need in your community. The rewards are unbelievable Not only will you feel good about yourself but you will gain a sense of sadsfacdon and feel connected to your community. Volunteering could also help develop communicadon, management, or supervisory sldlls that you may not develop by just attending school. 

Vote in Local and National Elections Most of you are 18 or older. Take your dvic dudes seriously. Exercise your right to vote, and try to pl an active role in your local, state, or federal government. Remember that freedom is not free. Be a good, responsible dozen. 

Get to Know Your Classmates There ate many good reasons fer getting to know one or two other students in your classes. You may want to study with someone from class, or if you are absent from dass, you have someone to contact to find out what the assignment is or find out what vras covered in class. Record the following infiirmadon on the course syllabi for all your classes the name of a student sitring next to you, his or her telephone number, and his or her e-mail address. 

PSEUDO-OCTAHEDRAL d NICKEL COMPLEXES WITH POLY(4-VINYLPYRIDINE) 

It cannot be claimed that this chapter is an exhaustive coverage of all those chemicals which are used to improve solid-liquid separations. For example, the potato starch which is commercially available has found wide use. This naturally occurring polymer with a molecular weight of about 1000000 is 

Substrate to be treated Class of electrolyte Typical dosage, per tonne of dry solids 

Water (potable) High molecular weight polyacrylamides of low toxicity with usage of Must not exceed 

Textiles Low molecular weight, highly cationic— followed by anionic  

Sewage sludge High molecular weight polyacrylamides 1-4 kg 

A number of cormnon issues arise from the various legislative requirements for examination and inspection of plant and equipment. 

In general where the law requires particular items of plant to be thor-ou ly examined and tested it requires that the work be carried out by a competent person.  

There is no precise guidance in the statute or in subsequent case law as to what constitutes competence. However, the competency of a person to carry out particular examinations or tests is a matter of fact on which the occupier or owner of the statutory equipment must be satisfied. In the event of legal proceedings if will require to be demonstrated in court that the person chosen was indeed competent to carry out the statutory surveys. 

An often quoted definition is that the competent person should have such practical and theoretical knowledge and actui experience of the type of machinery or plant which he has to examine, as will enable him to detect defects or wealmesses which it is the purpose of the examination to discover, and to assess their importance in relation to the strength of the machinery or plant in relation to its fxmction. It is not sufficient for the person making the examination to be able to detect faults, he must also, from his knowledge and experience, be able to assess their seriousness. 

The competent person need not necessarily be from an independent authority, but can be an internal appointment of a suifably qualified person by tile company concerned, but in exercising his responsibilities for carrying out examinations he must be separated from any ofher fxmctions that might cause a clash of interests. The competent person, whether employee or from a specialist organisation, must be allowed to act objectively and in a professional manner. 

Occasionally, a situation arises in which a flat-turn pipe rack may be employed. This often happens near a dead-end area where Ae potential for problems is minimal. As shown in Exhibit 11-28, the line sequence 

Alternative pipe rack expansion of the individual vels can be accomplished by adding a cantilever earn as required on the outside of the column. The nly problem with this approach is that, if not planned r, the vertical risers commonly found outside the ipe rack use a considerable amount of the space of le extension, as shown in Exhibit 11-13. 

Pipe rack additions are shown in Exhibit 11-30. rea A shows a standard two-level pipe rack, as lanned. Because it is always possible for the pipe rack ) be expanded in the future, the area over the slumns must be kept free of piping and conduit. The iture expansion may include another new level (B), 1 air cooler (C), or a series of shell and tube exchang-rs (D). The preferred location of a relief header )Ove a pipe rack is illustrated in Exhibit 11-12. 

Lighting panels and welding receptacles also must 

Structures are used in most industrial fecilities to accommodate equipment and associated components to suit specific process, real estate, climatic, and client requirements. A structure can be designed to support one or two pieces of equipment or an entire process plant and can be open or enclosed, The principal ob-jeaives in the layout of struaures are to optimize all available space and to suppon safety, maintenance, operation, cost, and constructability. 

The design of the incineration facility should include a provision, to the extent deemed necessary by the regulatory body, to limit the effects of the significant risks identified in the system safety analysis. These risks may include both natural events (e.g. earthquakes, tornadoes, floods) and man-made events (e.g. nearby explosions, impact of aircraft). 

As stated above, these ratios are based on natural gas feedstocks. If heavier feedstocks are used, the ratios will be lower because the hydrogen to carbon ratio of the feed will be lower. 

The above ratios are based on t5q)ical reformer outlet temperatures and pressures for each technology. The reformer outlet temperature is t5q)ically set by the residual methane requirement. The reformer outlet pressure is t5q)ically 

Thus far, considerable discussion has centered on the H2/CO ratio, since as noted above, the technology that can most easily achieve the required product H2/CO ratio has an inherent initial advantage. But there are other considerations that could over-ride this advantage. These are outlined below. 

Section 12-6 provides a discussion of drop suspension, dispersion formation, and the interrelationships between dispersion, coalescence, and suspension. Additional 

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The described method can generate a first-order backward or a first-order forward difference scheme depending whether 0 = 0 or 0 = 1 is used. For 9 = 0.5, the method yields a second order accurate central difference scheme, however, other considerations such as the stability of numerical calculations should be taken into account. Stability analysis for this class of time stepping methods can only be carried out for simple cases where the coefficient matrix in Equation (2.106) is symmetric and positive-definite (i.e. self-adjoint problems Zienkiewicz and Taylor, 1994). Obviously, this will not be the case in most types of engineering flow problems. In practice, therefore, selection of appropriate values of 6 and time increment At is usually based on trial and error. Factors such as the nature of non-linearity of physical parameters and the type of elements used in the spatial discretization usually influence the selection of the values of 0 and At in a problem. 

Other considerations (such as mixed quantum and classical forces) arise when considering the complete merger of two or more methodologies in the same molecular system, but since they are not yet available in this release of HyperChem they need not be considered here. 

Other considerations for fault tree constmction are (/) assume that faults propagate through normally operating equipment. Never assume that a fault is stopped by the miraculous failure of another piece of equipment. (2) Gates are coimected through labeled fault events. The output from one gate is never coimected directly into another. 

Many reaction schemes have been proposed (161,162). All reaction schemes ate designed such that reaction steps having positive A. " values are operated at high (625—725°C) temperatures, whereas reaction steps having negative AA values are operated at low (about 225°C) temperatures. The purpose is to lower the free energy change, ie, the work requirement, and increase the thermal requirement, for improved efficiency. Other considerations, such as reaction kinetics, corrosion, cost of materials, and side reactions must also be taken into account. 

Table 6 shows the production of abrasive sihcon carbide in the United States and Canada (131). In 1988, four firms were producing cmde sihcon carbide under various trade names at six plants in the United States and Canada, The Exolon-ESK Co. General Abrasive/Dresser Co. Norton Co. and Superior Graphite Co. Most plants are located in areas where electrical power is, or at one time, was available at relatively low rates. Other considerations are availabihty of labor, reasonable air and water pollution standards, future expansion potential, and proximity of raw materials and markets. 

A carrier is selected by the dyer according to various criteria. The type of equipment and conditions under which it is to be used have already been mentioned. Other considerations include color yield, dye migration, and product and emulsion stabiUty. 

Other Considerations. Some carrier-active products, especially o-phenylphenol and methylnaphthalenes, have an adverse effect on the lightfastness of the finished dyeing. The reason for this is not clear, but the effect is readily estabhshed. This problem is overcome by submitting the dyed material to temperatures higher than those normally required in drying. Under the conditions (150—175°C) that are usually required to heat-set dyed fabrics or to cure resins apphed in finishing operations, the residual carrier is volatilized. 

Other Considerations in Feedforward Control The tuning of feedforward and feedback control systems can be performed independently. In analyzing the block diagram in Fig. 8-32, note that Gy is chosen to cancel out the effects of the disturbance Us) as long as there are no model errors. For the feedback loop, therefore, the effects of L. s) can also be ignored, which for the sei vo case is ... 

Selecting the Sampling Point The selection of the sampling point is based primarily on supplying the analyzer with a sample whose composition or physical properties are pertinent to the control function to be performed. Other considerations include selecting locations that provide representative homogeneous samples with minimum transport delay, locations that cohect a minimum of contaminating material, and locations that are accessible for test and maintenance procedures. 

It is important when appraising by (NPV) and (DCFRR) not to consider the past in profitabihty estimations. Good money should never follow bad. It is unwise to continue to put money into a project if a more profitable project exists, even though this course may involve scrapping an expensive plant. Other considerations may, however, outweigh purely financiaf criteria in a particular case. 

In selec ting the machines of choice, the use of specific speed and diameter best describe the flow. Figure 10-67 shows the characteristics of the three types of compressors. Other considerations in chemical plant service such as problems with gases which may be corrosive or have abrasive solids in suspension must be dealt with. Gases at elevated temperatures may create a potential explosion hazard, while air at the same temperatures may be handled qmte normally minute amounts of lubricating oil or water may contaminate the process gas and so may not be permissible, and for continuous-process use, a high degree of equipment rehability is required, since frequent shutdowns for inspec tion or maintenance cannot be tolerated. 

Expansion Joints All the foregoing applies to stiff piping systems, i.e., systems without expansion joints (see detail 1 of Fig. 10-169). When space hmitations, process requirements, or other considerations result in configurations of insufficient flexibihty, capacity... 

Other Considerations Autoignition can occur if combustible fluids are absorbed by wicking-type insulations. Chloride stress corrosion of austenitic stainless steel can occur when chlorides are concentrated on metal surfaces at or above approximately 60°C (140°F). The chlorides can come from sources other than the insulation. Some calcium sihcates are formulated to exceed the requirements of the MIL-I-24244A specification. Fire resistance of insulations varies widely. Calcium sihcate, cellular glass, glass fiber, and mineral wool are fire-resistant but do not perform equally under actual fire conditions. A steel jacket provides protection, but aluminum does not. 

Other considerations are (I) proper ventilation and discharge enclosures, (2) provision for relief of internal explosion, (3) vibration isolation (shock mounts), (4) remote operation of charge and discharge, (5) noise during operation. 

Specific. surface of solid spheres of 0.1 mm (0.0039 in) dia is 0.06 mVml (18,300 ftVfF) and a porous activated alumina pellet has about 600 mVml (1.83 X 10 ftVfF). Other considerations aside, a large surface is desirable because the rate of reaction is proportional to the accessible surface. On the other hand, large specific surface means pores of small diameter. 

The annualized capital cost (ACC) is the product of the CRF and TCC and represents the total instaUed equipment cost distributed over the lifetime of the project. The ACC reflects the cost associated with the initial capital outlay over the depreciable life of the system. Although investment and operating costs can be accounted for in other ways such as present-worth analysis, the capital recovery method is preferred because of its simplicity and versatUity. This is especiaUy true when comparing somewhat similar systems having different depreciable lives. In such decisions, there are usuaUy other considerations besides economic, but if all other factors are equal, the alternative with the lowest total annualized cost should be the most viable. 

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