Process Intensification and Integration for Sustainable Design. Группа авторов

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Process Intensification and Integration for Sustainable Design - Группа авторов


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Refrigerant price 13.11 $/GJ [28] Electricity price 0.049 $/kWh [29] Fuel price 2.98 $/MSCF [30] Plant operator rate 32.74 $/h [31] Plant supervisor rate 68.13 $/h [32] Maintenance 5 % of FCI [25] Operating charges 25 % of operating labor cost [25] Plant overhead 50 % of operating labor + maintenance cost [25] General administrative 8 % of all other operating costs [25] Stream factor 0.96 — —

      The only additional equations used were those to estimate the number of workers based on the number of processing steps [28]:

      (2.2)equation

      where Nnp, the number of non‐particulate processing steps, which is related with the number of operators per shift (NOL), given as in Eq. (2.3):

      where P, the number of processing steps where particulate solids are handled.

      2.4.2.1 Changes in Fixed and Variable Costs

      2.4.2.2 Revenue

Commodity Units Base case
Heat valuea $/MMBtu 2.98
Ethane $/gal 0.262
Propane $/gal 0.632
n‐Butane $/gal 0.691

      a Methane and wellhead gas are priced in terms of their heat value ($/MMBtu).

      2.4.2.3 Economic Calculations

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

      (2.4)equation

      where TCI, total capital investment.

      (2.5)equation

      where FCI, total fixed capital investment:

      (2.6)equation

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

      (2.7)equation

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

      (2.8)equation

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

      (2.9)equation

      where TAC, total annualized cost:

      (2.10)equation

      (2.11)equation

      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)equation

      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:

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

      2.4.3 Safety Index Calculations

      (2.14)equation

      where


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