| OCR Text |
Show was assumed, For a saturated lime-urea hydrate, in which the urea/CaO mass ratio is approximately 0,60, the sorbent cost becomes $114/ton, In order to evaluate the economics associated with the retrofit of a lime-urea sorbent injection system, a spreadsheet model developed by Stearns-Roger was employed, The model Is based on the EPRI Technical Assessment Guidelines (EPRI, 1986), The program incorporates actual equipment costs over different size ranges, as well as a retrofit factor ranging between 10-25 percent of installed equipment cost, a 25 percent process contingency, and a 20 percent project contingency, The economic basis for the current analysis is summarized in Table 1, All other process systems - sorbent feed system, boiler modifications, particulate control modifications, and waste handling modifications are assumed to be similar to furnace sorbent injection with an atmospheric lime hydrate (Ireland et aI., 1986), albeit at reduced particulate loadings due to the lower Ca/S injection ratios, A summary of all of the major cost components for the retrofit of the lime-urea sorbent technology onto a 100 MW base unit is presented in Table 2, The major cost components are presented in both first year and levelized values based on a 20 year remaining plant life, It should be noted that the total capital requirement is generally distributed over the remaining plant life so that the first year costs already reflect the levelized fixed charge rate, In addition to total dollars, the retrofit costs are also presented in the following units: o $/kW-year o mills/kWh o $/ton of NOx removed , and o $/ton of total pollutants removed (S02 included), The $/kW-years and mills/kWh represent normalized technology costs in terms of power produced, The dollar per ton pollutant removed categories provide a normalized basis of comparison between lime-urea hydrate sorbent injection and alternative technologies in terms of cost effectiveness, As shown in Table 2, the sorbent cost represents approximately 500;0 of the total levelized technology costs, In combination with other variable O&M costs, the limeurea hydrate technology is comprised of almost 60010 in variable operating costs, Thus, the technology reduces the capital expenditures incurred at the outset, with the majority of costs incurred in direct proportion with use, The value of this approach is to retain the greatest flexibility in system planning, If system demands warrant a reduction in capacity factor, then the variable portion of the pollution control costs are similarly reduced, In the case of capital Intensive technologies, the pollution control costs are Incurred irrespective of use, In terms of cost per ton of pollutant removed, the levelized cost for the lime-urea hydrate is 1,081 $/ton NOx based on a 60% reduction from a baseline of 0,73 Ib NOx/106 Btu and a 65% capacity factor. If the nominal 8% reductions in S02 are also taken into account, the cost effectiveness is improved to 758 $/ton of NOx and S02' -12- |
