Auxiliary


Depending on the mix of waste being burnt, the incinerator may or may not require auxiliary firing from fuel oil or natural gas.  [c.299]

Fluidized-bed incinerators. Liquid, solid, and gaseous wastes can be treated in fluidized-bed incinerators. Solid particles, however, must be small (typically around 1 mm). If low-temperature incineration (less than 900 C) is required, then sand can be used as the bed material. Higher temperatures result in fusion of the bed and require a particulate refractory material instead. If the waste can be incinerated at temperatures less than around 770°C, limestone can be used for the bed material, which absorbs the acid gases. Fluidized beds have two main advantages over other designs good mixing allows lower excess air, which in turn leads to less auxiliary firing, and the heat capacity of the bed compensates for variations in feed material, giving more stable operation.  [c.300]

While incineration is the preferred method of disposal for wastes containing high concentrations of organics, it becomes expensive for aqueous wastes with low concentrations of organics because auxiliary fuel is required, making the treatment expensive. Weak aqueous solutions of organics are better treated by wet oxidation (see Sec. 11.5).  [c.301]

Incineration. Incinerators were discussed in Sec. 11.1. When incinerators are used to treat gaseous pollutants in relatively low concentration, auxiliary firing from fuel or other waste material normally will be necessary. The capital and operating costs may be high. In addition, long duct lines are often necessary.  [c.305]

The factors fp and fj have not been applied to installation costs because installation costs are not a simple function of purchase cost. Although process piping and fittings made for the same unusual conditions are proportionally more expensive, labor, foundations, insulation, etc. are not. Furthermore, only about 70 percent of piping is directly exposed to process fluid. The balance is auxiliary or utility piping made of conventional materials.  [c.417]

Prior to moving the rig and all auxiliary equipment the site will have to be cleared of vegetation and levelled. To protect against possible spills of hydrocarbons or chemicals the surface area of a location should be coated with plastic lining and a closed draining system installed. Site management should ensure that any pollutant is trapped and properly disposed of.  [c.43]

The two diabatic nuclear wave functions xf and x can be expressed as linear combinations of auxiliary nuclear wave functions and, respec-  [c.210]

Auxiliary subroutines for handling coordinate transformation between local and global systems, quadrature, convergence checking and updating of physical parameters in non-linear calculations.  [c.196]

Witt in 1876 coined the term chromophore for unsaturated groups such as C=C, C=0 and N=N, which he thought to be essential for colour in organic compounds, and the term auxochrome for groups, such as —NR, thought to play an auxiliary role in producing and modifying colour. In modern usage the terms chromophore and auxochrome are employed to designate Tt-electron and p-electron groups respectively.  [c.1145]

Oppolzer Camphor based auxiliaries Tetrahedron, 1987, 43, 1969. diastereoselectivities on the order of 50 1  [c.77]

Clearly, there is a need for techniques which provide access to enantiomerically pure compounds. There are a number of methods by which this goal can be achieved . One can start from naturally occurring enantiomerically pure compounds (the chiral pool). Alternatively, racemic mixtures can be separated via kinetic resolutions or via conversion into diastereomers which can be separated by crystallisation. Finally, enantiomerically pure compounds can be obtained through asymmetric synthesis. One possibility is the use of chiral auxiliaries derived from the chiral pool. The most elegant metliod, however, is enantioselective catalysis. In this method only a catalytic quantity of enantiomerically pure material suffices to convert achiral starting materials into, ideally, enantiomerically pure products. This approach has found application in a large number of organic  [c.77]

The merits of (enantioselective) Lewis-acid catalysis of Diels-Alder reactions in aqueous solution have been highlighted in Chapters 2 and 3. Both chapters focused on the Diels-Alder reaction of substituted 3-phenyl-1-(2-pyr idyl)-2-prop ene-1-one dienophiles. In this chapter the scope of Lewis-acid catalysis of Diels-Alder reactions in water is investigated. Some literature claims in this area are critically examined and requirements for ejfective Lewis-acid catalysis are formulated. Finally an attempt is made to extend the scope of Lewis-acid catalysis in water by making use of a strongly coordinating auxiliary.  [c.107]

Scheme 4.6. Schematic representation of the use of a coordinating auxiliary for Lewis-acid catalysis of a Diels-Alder reaction. Scheme 4.6. Schematic representation of the use of a coordinating auxiliary for Lewis-acid catalysis of a Diels-Alder reaction.
This goal might well be achieved by introducing an auxiliary that aids the coordination to the catalyst. After completion of the Diels-Alder reaction and removal of the auxiliary the desired adduct is obtained. This approach is summarised in Scheme 4.6. Some examples in which a temporary additional coordination site has been introduced to aid a catalytic reaction have been reported in the literature and are described in Section 4.2.1. Section 4.2.2 relates an attempt to use (2-pyridyl)hydrazone as coordinating auxiliary for the Lewis-acid catalysed Diels-Alder reaction.  [c.111]

Literature examples of auxiliary-aided catalysis  [c.112]

Pyridyl)hydrazine as coordinating auxiliary  [c.113]

A coordinating auxiliary via a Mannich reaction  [c.114]

In a second attempt to extend the scope of Lewis-acid catalysis of Diels-Alder reactions in water, we have used the Mannich reaction to convert a ketone-activated monodentate dienophile into a potentially chelating p-amino ketone. The Mannich reaction seemed ideally suited for the purpose of introducing a second coordination site on a temporary basis. This reaction adds a strongly Lewis-basic amino functionality on a position p to the ketone. Moreover, the Mannich reaction is usually a reversible process, which should allow removal of the auxiliary after the reaction. Furthermore, the reaction is compatible with the use of an aqueous medium. Some Mannich reactions have even been reported to benefit from the use of water ". Finally, Lewis-acid catalysis of Mannich-type reactions in mixtures of organic solvents and water has been reported ". Hence, if both addition of the auxiliary and the subsequent Diels-Alder reaction benefit from Lewis-acid catalysis, the possibility arises of merging these steps into a one-pot procedure.  [c.114]

Clearly, the use of diamine 4.43 as a coordinating auxiliary is not successful. However, we anticipated that, if the basicity of the tertiary amine group of the diamine could be reduced, the elimination reaction will be less efficient. We envisaged that replacement of the tertiary amine group in 4.43 by a pyridine ring might well solve the problem.  [c.116]

Finally, in the last step, the chelating auxiliary had to be removed Ideally, one would like to convert 4.54 into ketone 4.55 via a retro Mannich reaction. Unfortunately, repeated attempts to accomplish this failed. These attempts included refluxing in aqueous ethanol under acidic and basic conditions and refluxing in a 1 1 acetone - water mixture in the presence of excess paraformaldehyde under acidic conditions, in order to trap any liberated diamine. Tliese procedures were repeated under neutral conditions in the presence of copper(II)nitrate, but without success.  [c.117]

Equation (1) is of little practical use unless the fuga-cities can be related to the experimentally accessible quantities X, y, T, and P, where x stands for the composition (expressed in mole fraction) of the liquid phase, y for the composition (also expressed in mole fraction) of the vapor phase, T for the absolute temperature, and P for the total pressure, assumed to be the same for both phases. The desired relationship between fugacities and experimentally accessible quantities is facilitated by two auxiliary functions which are given the symbols (f  [c.14]

Catalytic incinerators. Cataljdic incinerators allow oxidation of wastes at lower temperatures than conventional thermal incinerators. Operating temperatures are less than 550" C. Their advantages are lower fuel consumption if auxiliary fuel is required and less severe operating conditions for materials of construction. However, catalytic incinerators cannot handle solid waste, and catalyst fouling and aging are a problem. Catalysts are usually noble metals (such as platinum or rhodium) finely divided on a support such as alumina. Both fixed and fluidized beds are used. The most common applications for catalytic incinerators are dedicated devices to treat gaseous process vents, particularly purges.  [c.300]

Auxiliary buildings such as offices, medical, personnel, locker rooms, guardhouses, warehouses, and maintenance shops  [c.418]

Bauman, H. C., Estimating Cost of Process Auxiliaries, Chem. Engg. Progr., 51 45, 1955.  [c.426]

Precision combustion measurements are primarily made to detennine enthalpies of fonnation. Since the combustion occurs at constant volume, the value detennined is the energy change AJJ. The enthalpy of combustion A //can be calculated from A U, provided that the change in the pressure within the calorimeter is known. This change can be calculated from the change in the number of moles in the gas phase and assuming ideal gas behaviour. Enthalpies of fonnation of compounds that do not readily bum hr oxygen can often be detennined by combusting in fluorine and the enthalpy of fonnation of volatile substances can be detennined using flame calorimetry. For compounds that only combust at an appreciable rate at high temperature, such as zhconium in chlorine, the teclmique of hot-zone calorimetry is used. In this method one heats the sample only very rapidly with a known amount of energy until it reaches a temperature where combustion will occur. Alternatively, a well characterized material such as benzoic acid can be used as an auxiliary material which, when it bums, raises the temperahire sufficiently for the material to combust. These methods have been discussed in detail [2, 3 and 4].  [c.1910]

The derivation of the mollified impulse method in [7] suggests that the same integrator be used for the auxiliary problem as that used for integrating the reduced primary problem M d fdt )X = F X) between impulses. Of eourse, Ax(x) is also needed. For the partitionings + j/aiow typically used in MD, this would lead unfortunately to a matrix Ax(x) with a great many nonzeros. However, it is probably important to take into account only the fastest components of [7]. Hence, it would seem sufficient to use only the fastest forces jjj averaging calculation.  [c.326]

This section descrihes IlyperChem s four force fields, MM-h AMBER, OPES, and BlO-h providing auxiliary information for all force field calculations.  [c.173]

Asymmetric DieJs-Alder Reactions - Chiral Auxiliaries  [c.158]

The element has applications as a beta source for thickness gages, and it can be absorbed by a phosphor to produce light. Light produced in this manner can be used for signs or signals that require dependable operation it can be used as a nuclear-powered battery by capturing light in photocells which convert it into electric current. Such a battery, using 147Pm, would have a useful life of about 5 years. Promethium shows promise as a portable X-ray source, and it may become useful as a heat source to provide auxiliary power for space probes and satellites. More than 30 promethium compounds have been prepared. Most are colored.  [c.184]

Czamik et al." studied the auxiliary-assisted copper(II)-ion catalysed hydrolysis of acrylate esters  [c.112]

In summary, we have demonstrated that it is possible to extend the scope of Lewis-acid catalysis of Diels-Alder reactions in water, by employing a chelating auxiliary. We envisage that analogues of 4.39 capable of undergoing a Mamrich reaction with 4.50 can be treated with reactive dienes in the presence of a Lewis-acid catalyst in water.  [c.119]


See pages that mention the term Auxiliary : [c.562]    [c.1463]    [c.1908]    [c.2470]    [c.326]    [c.464]    [c.352]    [c.153]    [c.154]    [c.126]    [c.72]    [c.159]    [c.159]    [c.27]    [c.112]    [c.113]    [c.113]    [c.113]    [c.114]   
Practical aspects of finite element modelling of polymer processing (2002) -- [ c.0 ]

Turboexpanders and Process Applications (0) -- [ c.0 ]