Equipment Costing

Chapter 22 (p558-597)

CH EN 4253

Terry A. Ring

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

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)

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

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

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

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

Blowers

• Sizing factor is the power consumption, PC

• Centrifugal (turbo) BlowerCB=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

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

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)

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

Pressure Vessels

• Storage Tanks

• Distillation Towers– Tray– Packed

• Absorber Towers

• Stripping Towers

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

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

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

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

Absorbers/Strippers

• Pressure Vessel plus platforms and packing

• Separate costs for blowers

• Separate costs for motors

Other process equipment

• Different sizing factors

• Different basis cost equations

• Same methods used for cost calculation

Other Process Equipment

• Various Size Factors

• Table 22.32