Processing methods equipment cost considerations

In the dyestuff industry, anthraquinone still ranks high as an intermediate for the production of dyes and pigments having properties unattainable by any other class of dyes or pigments. Its cost is relatively high and will remain so because of the equipment and operations involved in its manufacture. As of May 1991, anthraquinone sold for 4.4/kg in ton quantities. In the United States and abroad, anthraquinone is manufactured by a few large chemical companies (62). At present, only two processes for its production come into consideration manufacture by the Friedel-Crafts reaction utilizing benzene, phthahc anhydride, and anhydrous aluminum chloride, and by the vapor-phase catalytic oxidation of anthracene the latter method is preferred. 

Thermal and catalytic incinerators, condensers, and adsorbers are the most common methods of abatement used, due to their ability to deal with a wide variety of emissions of organic compounds. The selection between destruction and recovery equipment is normally based on the feasibility of recovery, which relates directly to the cost and the concentration of organic compounds in the gas stream. The selection of a suitable technology depends on environmental and economical aspects, energy demand, and ease of installation as well as considerations of operating and maintenance. 7 he selection criteria may vary with companies or with individual process units however, the fundamental approach is the same. 

Automatization of all stages of the analytical process is a trend that can be discerned in the development of modern analytical methods for chemical manufacture, to various extents depending on reliability and cost-benefit considerations. Among the elements of reliability one counts conformity of the accuracy and precision of the method to the specifications of the manufacturing process, stability of the analytical system and closeness to real-time analysis. The latter is a requirement for feedback into automatic process-control systems. Since the investment in equipment for automatic online analysis may be high, this is frequently replaced by monitoring a property that is easy and inexpensive to measure and correlating that property with the analyte of interest. Such compromise is usually accompanied by a collection of samples that are sent to the analytical laboratory for determination, possibly at a lower cost. 

At this stage, a tentative selection of at least two alternative size enlargement methods can be made. These initial selections can then be refined with the help of laboratory and/or pilot plant tests. Most vendors (see Appendix, p. 177) have pilot equipment available on a rental basis and are prepared to assist with test runs and technical advice. A final process selection can then be made taking into account the normal considerations of reliability, flexibility, ease of maintenance and minimum overall cost at the required throughput. 

If a process is to be profitable, the total annual cost must be offset by the revenue (R) the process generates. Moreover, if the revenue exceeds the TAC, income taxes will be owed. Finally, if income taxes are a consideration, so will be the depreciation of the process equipment. (Depreciation, an income tax book entry, should not be confused with the capital recovery cost see later discussion on the EUAR method.) Space does not permit a thorough discussion of either income taxes or depreciation, as the rules governing the calculation of both are quite complex. For our purposes, the following equation, which encompasses all of these variables, will suffice ... 

In spite of the use of high-quality steel grades for the segments and other machine parts, wear is considerable and, while, when compared with other methods, the total costs associated with this item are not excessive, the process interruptions, which can be only avoided if redundant stand-by equipment is installed, are not tolerable. In... 

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