Читать книгу Process Intensification and Integration for Sustainable Design - Группа авторов - Страница 35

The next step was to calculate the return on investment (ROI) [26]:

(2.4)

where TCI, total capital investment.

First, the quantities in Eqs. must be calculated.

(2.5)

where FCI, total fixed capital investment:

(2.6)

where WCI, working capital investment (assumed to be 15% of FCI):

(2.7)

where AFC, annualized fixed cost (depreciation); FCI_S, the salvage value of the FCI (assumed to be 10% of FCI); and N, plant lifetime (assumed to be 10 years):

(2.8)

where AOC, annual operating cost; VC_i, total variable cost for each process unit:

(2.9)

where TAC, total annualized cost:

(2.10)

(2.11)

where the tax rate is assumed to be 30%.

For the other cases, the calculations are similar, except instead of fixed and variable costs only the additional costs were determined. This is done because we are considering only the additional costs for processing a new composition. Similarly instead of ROI, incremental return on investment (IROI) is calculated instead:

(2.12)

where ΔTCI, the change in total capital investment for a given additional case.

Finally, the total ROI can be determined for treating multiple feeds from the following:

(2.13)

where p, probability or likelihood of obtaining a particular feed, and the subscript f denotes feed.