CONTENTS 4 Experimental Studies

Some mechanisms of anhydrite deposition in Kuroko deposits. Shikazono et al. (1983) considered the depositional mechanism of anhydrite based on the mode of occurrence, texture, Sr content, nature of the contained fluid inclusions and isotopic composition of Sr, S and O in anhydrite together with the mineralogy of the sekko ore, combined with their experimental study on the patitioning of Sr between coexisting anhydrite and aqueous solution. The following is their discussion on the depositional mechanism of anhydrite. 

The carcinogenicity of polycyclic aromatic compound-rich tyre extender oils has lead to the proposal of a legislative ban on their use in Europe. The suitability of naphthenic oils as non-toxic plasticisers in tyre treads is discussed and results are presented of experimental studies of the use of these plasticisers in SBR, EPDM, sulphur-cured EPDM and peroxide-cured EPDM. Despite their low aromatic content, the naphthenic plasticisers are shown to give good results in SBR, probably as a result of the contribution to solvent characteristics of the naphthenic molecular structure. The use of naphthenic oils is expected to increase worldwide as they are said to be one of the best alternatives to aromatic extracts with regard to solvent properties, compatibility, performance and availability. 

So far, most of the experimental studies have been limited to fully polymerized samples or samples with a high plastic content. That is because the earlier Interest was mainly focused on the effect of properties of the constituents, such as crosslink density and miscibility, ease of TEM studies, etc. 

As Berner (36) pointed out in his classic work, the formation of pyrite is coupled to a process in which free sulfide is oxidized to form polysulfides, which again react with FeS to form pyrite. In this study elemental sulfur was the oxidant. However, elemental sulfur was always less than 1% of the total sulfur content in the study of White et al. (35). The findings of the experimental studies discussed on the interaction between H2S and ferric oxides (20-23), in combination with the field observations, suggest a mechanism in which ferric iron oxides are the oxidants to form polysulfides and subsequently pyrite. 

Because annual growth bands of sufficient size to permit chemical analysis form in corals, considerable effort has gone into the study of incorporation of trace components in these organisms. Experimental studies, such as those by Smith et al. (1979), have contributed substantially to the reliability of the use of the Sr content of corals as a paleothermometer, and the efforts of other researchers (e.g., Buddemeier et al., 1981 Swart and Hubbard, 1982 Shen and Boyle, 1988) have yielded insight into the processes controlling a variety of minor components in corals. 

Two species, chir (Pinus roxburghii Sargent.) size 7.5 x 2.75 x 1.25 cm3and mango (Mangifera indica Linn.) size 7.5 x 1.25 x 1.25 cm3 were studied to establish different reaction variables. Four replicates were taken for each treatment and experiments were carried out with oven-dried samples except in case of those where effect of moisture content was studied. Samples were placed in a reaction chamber and reaction was carried out under reflux conditions at 93+1 C, the boiling point of thioacetic acid. Experimental set-up for vapor phase acetylation is shown in Figure 1. 

Some experimental studies point out that the diffusion rate of pure hydrocarbons decreases with the coke content in the zeolite [6-7]. Theoretical approaches by the percolation theory simulate the accessibility of active sites, and the deactivation as a function of time on stream [8], or coke content [9], for different pore networks. The percolation concepts allow one to take into account the change in the zeolite porous structure by coke. Nevertheless, the kinetics of coke deposition and a good representation of the pore network are required for the development of these models. The knowledge of zeolite structure is not easily acquired for an equilibrium catalyst which contains impurity and structural defects. 

The experimental studies using industrial feedstock are carried out in a modified MA.T. (micro activity test) [10], The reaction conditions are presented in table 1, The catalyst is NOVA D equilibrium catalyst from Grace Davison Co, The equilibrium catalysts are previously coked under the same reaction conditions to get partially deactivated samples. The method using the conversion versus initial coke content from experiments to determine the deactivation function, is described in [10]. Three different feedstocks are used (table l). 

Contents An overview of synthetic fuel combustion issues and research activities / A.A. Boni. . . [et al.] — characteristics of typical synthetic fuel components / R. B. Edelman, R. C. Farmer, and T.-S. Wang — An experimental study of synthetic fuel atomization characteristics / R. G. Oeding and W. D. Bachalo —[etc.]... 

Synthetic liquid fuels derived from coal and shale will differ in some characteristics from conventional fuels derived from petroleum. For example, liquid synfuels are expected to contain significantly higher levels of aromatic hydrocarbons, especially for coal-derived fuels, and higher levels of bound nitrogen. These differences can affect the combustion system accepting such fuels in important ways. In continuous combustors, i.e. gas turbines, the increased aromatics content of coal-derived fuels is expected to promote the formation of soot which, in turn, will increase radiation to the combustor liner, raise liner temperature, and possibly result in shortened service life. Deposit formation and the emission of smoke are other potential effects which are cause for concern. Higher nitrogen levels in synfuels are expected to show up as increased emissions of N0X (NO+NO2) An earlier paper presented results of an experimental study on the effect of aromatics and combustor... 

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