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Equipment Costing

Equipment Costing. Chapter 22 (p558-597) CH EN 4253 Terry A. Ring. 6/10 th scale up/down Factor. Used for scaling the total capital cost for a chemical plant of a different size Cost 2 /Cost 1 = (Capacity 2 /Capacity 1 ) 0.6 Accounts for economy-of-scale. Accounting for Inflation.

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Equipment Costing

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  1. Equipment Costing Chapter 22 (p558-597) CH EN 4253 Terry A. Ring

  2. 6/10th scale up/down Factor • Used for scaling the total capital cost for a chemical plant of a different size • Cost2/Cost1 = (Capacity2/Capacity1)0.6 • Accounts for economy-of-scale

  3. Accounting for Inflation • Cost to purchase = Base Cost*(I/Ibase) • Base Cost, CB, = Historical price at Ibase • I is a Cost Index at present time • Chemical Engineering, CE, Plant Cost Index • Marshall and Swift (MS) Equipment Cost Index • Nelson-Farrar (NF) Refinery Construction Cost Index • Engineering News-Record (ENR) Construction Cost Index • Cp(I) = Cp(Ibase)*(I/Ibase) • Cp(Ibase)=FT*Fm*Cbase(Ibase)

  4. Cost Estimate Methods • Order of Magnitude Estimate • Method of Hill • Marshall Swift for I/Ibase • Six Tenths Rule for Production Capacity • CTCI-2 (I)=CTCI-1 (Ibase)*(I/Ibase)* (Capacity2/Capacity1)0.6 • Study Estimate (±35%) • Method of Lang • CTCI=1.05*fL-TCI ∑ (Ii/Ibase-i) Cp-i • Lang factors for different types of Plants • Solids -3.10, Solids&Fluids 3.62, Fluids 4.73 • Sum over all major equipment • Preliminary Estimate (±20%) • Method of Guthrie • Bare module cost, CBM= Cp-base(I/Ibase)[FBM+(FdFpFm-1)] • d= design factor, p = pressure factor, m =materials factor • CTCI= ∑ CBM_i • Quote Estimate

  5. Purchase Costs for Equipment • Size Factor, S, depends on type of equipment • Cp(Ibase)=A*(S)b • Cp(Ibase)=exp(Ao+A1[lnS]+A2[lnS]2+…) • Your book gives 2006 base costs • Ibase = 500 (2006) average

  6. Pumps & Electric Motors • Pump Types (Centrifugal, Gear, Plunger) • Centrifugal Pump • Size factor, S=Q(Head)0.5 • Base Cost, CB=exp(9.2951- 0.6019[ln(S)] +0.0519[ln(S)]2) • Cp=FTFMatCB • Fm materials factor see Table 22.21 • FT pump type factor see Table 22.20 • Other types of pumps have different CB formulas • Electric Motor to drive pump • Size Factor=Power consumption, PC=PT/ηp/ηM=PB/ηM=QHρ/(33,000ηpηM) • Q= flow rate, H = head, ρ = density • Efficiencies (pump and motor) are a function of flow rate and break horsepower (power without any losses), respectively • CB=exp{5.4866+0.013141[ln(PC)]+0.053255 [ln(PC)]2 +0.028628 [ln(PC)]3-0.0035549[ln(PC)]4} • Cp=FTCB • FT= motor types factor see Table 22.22 • ηM=~90% • Installation, etc, FBM=3.3 • CBM=FBM*∑CP

  7. Fans • Fan • Sizing factor is the volumetric flow rate, Q • Different CB formula for different types of fans • CP=FHFM CB • FH Head factor see Table 22.24 • FM material of construction factor • Fiberglass 1.8 • Stainless steel 2.5 • Nickel Alloy 5.0 • Motor size by PC=QHt(in. water)/(6,350 ηFηM) • ηM =~90%, FBM = 2.15 • CBM=FBM*∑CP

  8. Blowers • Sizing factor is the power consumption, PC • Centrifugal (turbo) Blower CB=exp{6.6547+0.7900[ln(Pc)]} • CP=Fm-fansCB • Motor • Motor size by PC=QHt(in. water)/(6,350 ηFηM) • ηM =90% , FBM = 2.15 • CBM=FBM*∑CP

  9. Compressors • Compressor types • Centrifugal, CB=exp{7.2223+0.80[ln(PC)]} • Reciprocating, CB=exp{7.6084+0.80[ln(PC)]} • Screw, CB=exp{7.7661+0.7243[ln(PC)]} • Size factor is the power consumed, PC=PB/ηC • CP=FDriveFMatCB • FDrive =1 (electric motor), 1.15 (steam), 1.25 (gas turbine) • FMat = 1.0 Carbon steel, 2.5 SS, 5.0 Nickel Alloy • CBM=FBM*∑CP • FBM = 2.15

  10. Heat Exchangers • Types of Heat exchangers • Floating, CB=exp{11.667-0.8709[ln(A)]+0.09005[ln(A)]2} • Fixed Head, CB=exp{11.0545-0.9228[ln(A)]+0.09861[ln(A)]2} • U-tube, CB=exp{11.147-0.9186[ln(A)]+0.09790[ln(A)]2} • Kettle, CB=exp{11.967-0.8709[ln(A)]+0.09005[ln(A)]2} • Thermosiphon, CB= • Double pipe, CB=exp{7.1248-0.16[ln(A)]} • Size Factor is HX area, A • CP=FpFMatFLCB • Pressure Factor, Fp= 0.9803+0.018(P(psig)/100)+0.0017(P(psig)/100)2 • Not for double pipe • Materials Factor, Fmat=a+(A/100)b, a & b from Table 22.25 • a≥1.0 note error in first row of Table 22.5 • Tube Length Factor FL= 1.25 for 8 ft, 1.0 for 20 ft. on a sliding scale • CBM = FBM*CP, FBM=3.17 (S&T), 1.80 (DP), 2.17 (Fin/Fan)

  11. Fired Heaters • Size Factor is the heat duty, Q • CB=exp{0.08505+0.766[ln(Q)]} • CP=FPFMatCB • FP=0.986-0.0035(P(psig)\500)+0.0175(P/500)2 • Fmat=1.4 Cr-Mo alloy steel, 1.7 for stainless steel • CBM = FBM*CP, FBM=2.19

  12. Pressure Vessels • Storage Tanks • Distillation Towers • Tray • Packed • Absorber Towers • Stripping Towers

  13. Pressure Vessels • Sizing Factor is the weight of steel, W • Horizontal Vessels, 1,000<W<920,00 lb CB=exp{8.717-0.2330[ln(W)]+0.4333[ln(W)]2} • Vertical Vessels, 4,200<W<1,000,00 lb CB=exp{6.775-0.18255[ln(W)]+0.02297[ln(W)]2} • Add Platform Costs, • Horizontal, 3<Di<12 ft • CPL=1580(Di)0.20294 • Vertical, 3<Di<21 ft • CPL=258.1(Di)0.7396(L)0.70684 • Weight, W=π(Di+ts)(L+0.8Di)tsρs • C=FMCB+CPL • FM= materials factor see Table 22.26 • Installation, etc, FBM=4.16 (V), 3.05 (H) • CBM=FBM*∑CP

  14. Hoop Stress Calc for thickness, ts • Design Pressure is function of operating pressure, Po • For Po> 1,000psig use Pd=1.1Po • For Po< 1,000psig but not for vacuum Pd=exp{0.60608+0.91615[ln(Po)]+0.0015655[ln(Po)]2} • Thickness (Hoop Stress Calculation) • ts= PdDi/(2SE-1.2 Pd) • S = max allowable stress for steel is f(T) • E = weld efficiency (fraction) • Minimum wall thickness for given diameters • May add extra thickness for wind stresses, corrosion • Different calculation for vacuum vessels • Also account for leakage when vacuum vessel is used

  15. Distillation Towers • Pressure vessel with plates or packing and additional nozzles and manholes • Tray Cost CT=NTFNTFTTFTMCBT • NT= no. trays • FNT= 1 for NT>20 otherwise FNT=2.25/(1.0414NT) • FTT = tray type, 1.0 sieve, 1.87 bubble cap • FTM= Materials, f(D) • Carbon Steel FTM=1.0 • 316 SS FTM=1.401+0.0788 Di • Installation, etc, FBM=4.16 • CBM=FBM*∑CP

  16. Packed Distillation Column • Pressure vessel with platforms plus packing • Packing Cost basis is volume of packing, VP • C=VpCPK+CDR • CPK= is installed cost per unit volume • Distributors cost, CDR

  17. Absorbers/Strippers • Pressure Vessel plus platforms and packing • Separate costs for blowers • Separate costs for motors

  18. Other process equipment • Different sizing factors • Different basis cost equations • Same methods used for cost calculation

  19. Other Process Equipment • Various Size Factors • Table 22.32

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