Capital investments estimating heat exchangers

Had the new heat exchanger been an addition to an existing plant that did not require investment in electrical services, utilities, offsites, buildings, site preparation or working capital, then the cost would be estimated from ... 

An example of an estimate of the total capital investment for a processing plant is given in Tables 16.14 and 16.15 for an ammonia plant producing 1 billion Ib/yr. The costs are for the year 2000 at a U.S. Midwest location. The plant is part of an integrated complex. The process involves a variety of equipment, including gas compressors, pumps, heat exchangers, a catalytic reactor, a distillation column, an absorber, a flash drum, a gas adsorber, and gas permeation membrane separators. The material of construction is almost exclusively carbon steel. 

In order to calculate the CO2 avoidance costs, the capital investment costs are first calculated using a conceptual cost estimation method with an accuracy of 40%. In this method, the main equipment costs are estimated. The costs for blowers, the heat exchanger and the columns have been calculated using correlations reported by Seider et al. [24] and Loh and Lyons [25] and are updated to costs in 2010 using the Chemical Engineering Plant Cost Index (CEPCI). 

Investment costs If the equipment delivered costs (main items like reactors, heat exchangers, compressors, distillation columns, etc.) are known, the total capital costs, which include additional direct and indirect costs for the erection, piping, engineering, and so on, can be estimated. For a quick estimation of the total capital investment the overall factor method is helpful. The costs of each piece of equipment is estimated and summed and, finally, multiplied by an overall factor of about four. 

To this point, it has been assumed that the log-mean tenperature correction factor, F, for all exchangers is the same and equal to 0.8. The reason that F is not assumed to be equal to unity is that, for heat exchangers in most practical applications, the flows of the hot and cold streams are never purely countercurrent. The most common type of heat exchanger in use in the chemical process industries is the shell-and-tube (S T) type. These units are typically made as multiples of the basic 1-shell pass, 2-tube pass (1-2) design. When estimating the fixed capital investment associated with the purchase and installation of the heat-exchanger network, the number of 1-2 S T exchangers is needed in addition to the total surface area of the network. 

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