Equipment Costing - Chemical Engineering Department_ University by dandanhuanghuang

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									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) 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
                   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

								
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