Chemical cost estimation procedures

Process economics is an essential element of a good design procedure. The objective of this appendix is to provide an overview of basic concepts in cost estimation and economics of chemical processes. For more details, the reacker is referred to Humphreys and Wellman (1996), Peters and Timmerhaus (1991), Garrett (1989) and Ulrich (1984). 

Operating costs can be estimated based on statistical analysis of operating costs in existing plants. Costs of waste disposal can be evaluated in the same way as costs for any chemical process since procedures for disposal include, in fact, unit chemical processes and operations. Costs of utilities and maintenance are best assessed based on the company data banks. Typical utility figures per m capacity of reactors in MPPs are 800-1100 kg steam/h, 60-80 kW power, and 7,000-8,000 kJ/h refrigeration capacity. 

Chapter 2, Production and Capital Cost Estimation, only contains the essentials of chemical-engineering economics. Many students learn other aspects of engineering economics in a separate course. Rather than placing this chapter later in the book, it is placed here to show the student how equipment influences the production cost. Chapter 2 describes cash flow and working capital in a corporation. This chapter also describes the components of the production cost and how to calculate this cost. Finally, this chapter describes the components of capital cost and outlines a procedure for calculating the cost. Most of the other chapters discuss equipment selection and sizing needed for capital cost estimation. 

The procedure for determining the cetane number in the CFR engine is not extremely widespread because of its complexity and the cost of carrying it out. There also exist several methods to estimate the cetane number of diesel fuels starting from their physical characteristics or their chemical structure. 

In the laboratory or process research section a laboratory procedure for a fine chemical is worked out. The resulting process description provides the necessary data for the determination of preliminary product specifications, the manufacture of semicommercial quantities in the pilot plant, the assessment of the ecological impact, an estimation of the manufacturing cost in an industrial-scale plant, and the vaHdation of the process and determination of raw material specifications. 

When the attractiveness of new products is evaluated, either for submitting an offer or for inclusion in the R D program, manufacturing costs have to be estimated on the basis of a laboratory synthesis procedure. This is best done by breaking down the process into unit operations, the standard costs of which have been determined previously. Care has to be taken to estimate the time required for each step of a process. Thus a liquid-liquid extraction can take more time than the chemical reaction. The capability of a fine-chemical company to make dependable manufacturing cost forecasts is a distinct competitive advantage. 

This procedure is used to estimate the weight, fabricated cost, and erection hours of the various types of steel structures required in a chemical plant. It is a very good tool for checking contractors take-offt and estimates as well as discussing and evaluating field extras. 

The EPA s "Risk Management Programs for Chemical Accidental Release Prevention Proposed Rule 40 CFR Part 68" estimates the cost for developing standard operating procedures at 2,500 for simple processes to... 

The main challenge in the present type of quantum mechanical modeling is to estimate the protonation cost The proton needed for the substrate reaction is ultimately provided by the solvent, a part that cannot be included in the model. To be able to work with a limited model, it is assumed that the resting state of the proton is the position of lowest energy in the quantum chemical model. For most models this position turns out to be the carboxyl-ate. This does not mean that the proton actually comes from the carboxylate or that the mechanism requires that the carboxylate is protonated in the reactant. The procedure simply gives a lower limit for the energy required to protonate the base. 

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