Equipment designEquipment design

Done By : : mohammed al-kashanDone By : : mohammed al-kashan

Supervised by:Supervised by:

DR. mohamed fahimDR. mohamed fahim

&&

Eng. Yusuf ismailEng. Yusuf ismail

AgendaAgenda

FurnaceFurnace

Packed bed reactorPacked bed reactor

CompressorCompressor

absorberabsorber

FurnaceFurnace

furnacefurnace

Increasing the temperature of first heat Increasing the temperature of first heat exchanger stream from 265 c ° to 405 c ° exchanger stream from 265 c ° to 405 c ° on radiation section and increase combined on radiation section and increase combined stream to 400 c ° on convection section stream to 400 c ° on convection section

Furnace contain two main area:Furnace contain two main area:

-Radiation section-Radiation section

- Convection section - Convection section

assumptionassumption

1.1. Fuel: pure methane with amount of 1000 Fuel: pure methane with amount of 1000 kmol/hrkmol/hr

2.2. Film heat transfer coefficient (hc) = 0.4Film heat transfer coefficient (hc) = 0.4

3.3. Excess air = 100%Excess air = 100%

4.4. The tube has staggered pitch The tube has staggered pitch arrangementarrangement

Radiant Section DesignRadiant Section Design

qr = saAcpF(Tg4 - Tw4)qr = saAcpF(Tg4 - Tw4)

Where,Where,

qr = Radiant heat transfer, Btu/hrqr = Radiant heat transfer, Btu/hr

s = Stefan-Boltzman constant, 0.173E-8 Btu/ft2-hr-s = Stefan-Boltzman constant, 0.173E-8 Btu/ft2-hr-R4R4

a = Relative effectiveness factor of the tube banka = Relative effectiveness factor of the tube bank

Acp = Cold plane area of the tube bank, ft2Acp = Cold plane area of the tube bank, ft2

F = Exchange factorF = Exchange factor

Tg = Effective gas temperature in firebox, °RTg = Effective gas temperature in firebox, °R

Tw = Average tube wall temperature, °RTw = Average tube wall temperature, °R

Alpha calculationAlpha calculation

Acp = (No. Tubes)*Space*(Eff. Length)Acp = (No. Tubes)*Space*(Eff. Length) aAcp , where the value of (a) is from aAcp , where the value of (a) is from

graph graph

Ar = (W*L*2 + W*H*2 + H*L*2-Exitarea*L )Ar = (W*L*2 + W*H*2 + H*L*2-Exitarea*L )

Aw = Ar - aAcp Aw = Ar - aAcp

Aw /aAcp Aw /aAcp

(W (W : : H H : : L) ratio of (width : height : L) ratio of (width : height : length)length)

Aw = Effective refractory area, ft2 Aw = Effective refractory area, ft2

Ar = Total refractory area, ft2 Ar = Total refractory area, ft2

aAcp = Equivalent cold plane area, aAcp = Equivalent cold plane area, ft2 ft2

Gas EmissivityGas Emissivity

Σmol% of CO2 and H2O in flue gas=Σmol% of CO2 and H2O in flue gas=

(mole% of O2 + mole% of N2) in product stream(mole% of O2 + mole% of N2) in product stream

beam length=2/3*(volume of beam length=2/3*(volume of furnace)^(1/3)furnace)^(1/3)

PL=product of the partial pressure of the PL=product of the partial pressure of the carbon dioxide (atm.ft)carbon dioxide (atm.ft)

PL=PL= beam length * beam length * Σmol% Σmol%

Exchange Factor (F)Exchange Factor (F)

FromFrom

previous graph we got previous graph we got the value of emissivty the value of emissivty

FromFrom

emissivty and emissivty and (Aw/aAcp)(Aw/aAcp)

The value of Exchange The value of Exchange factor can be factor can be calculated calculated

Convection Heat Transfer In Convection Heat Transfer In the Radiant Sectionthe Radiant Section

qcqc= = hc At hc At ((TgTg--TwTw))

At= 2πr * tube length * number of At= 2πr * tube length * number of tubestubes

Then,Then,

qRqR= = qrqr + + qc qc

Convection SectionConvection Sectionqcqc= = hc At hc At ((TgTg--TwTw))

Outside film heat transfer coefficient, hcOutside film heat transfer coefficient, hc::

hc = j*Gn*cp(kb/(cp*mb))0.67hc = j*Gn*cp(kb/(cp*mb))0.67Where,Where,J = Colburn heat transfer factorJ = Colburn heat transfer factorGn = Mass velocity based on net free area, Gn = Mass velocity based on net free area,

lb/hr-ft2lb/hr-ft2cp = Heat capacity, Btu/lb-Fcp = Heat capacity, Btu/lb-Fkb = Gas thermal conductivity, Btu/hr-ft-Fkb = Gas thermal conductivity, Btu/hr-ft-Fmb = Gas dynamic viscosity, lb/hr-ftmb = Gas dynamic viscosity, lb/hr-ft

Colburn heat transfer factor, jColburn heat transfer factor, j::

j=C1*C3*C5(df/do)0.5((Tb+460)/j=C1*C3*C5(df/do)0.5((Tb+460)/(Ts+460))0.25(Ts+460))0.25

Where,Where,C1 = Reynolds number correctionC1 = Reynolds number correctionC3 = Geometry correctionC3 = Geometry correctionC5 = Non-equilateral & row correctionC5 = Non-equilateral & row correctiondf = Outside diameter of fin, indf = Outside diameter of fin, indo = Outside diameter of tube, indo = Outside diameter of tube, inTb = Average gas temperature, FTb = Average gas temperature, FTs = Average fin temperature, FTs = Average fin temperature, F

Reynolds number correction, C1:Reynolds number correction, C1:

C1 = 0.25*Re-0.35C1 = 0.25*Re-0.35

Where, (Re = Reynolds number)Where, (Re = Reynolds number)

Geometry correction, C3:Geometry correction, C3:

For segmented fin tubes arranged in,a For segmented fin tubes arranged in,a staggered pattern,staggered pattern,

C3 = 0.55+0.45*e(-0.35*lf/Sf)C3 = 0.55+0.45*e(-0.35*lf/Sf)

If = fin height , Sf = fin spacing , (in If = fin height , Sf = fin spacing , (in inch)inch)

NonNon--equilateral & row correction, equilateral & row correction, C5: C5:

C5 = 0.7+(0.70-0.8*e(-0.15*Nr^2))*e(-C5 = 0.7+(0.70-0.8*e(-0.15*Nr^2))*e(-1.0*Pl/Pt)1.0*Pl/Pt)

Nr = Number of tube rowsNr = Number of tube rows

Pl = Longitudinal tube pitch, inPl = Longitudinal tube pitch, in

Pt = Transverse tube pitch, inPt = Transverse tube pitch, in

Mass velocity (Mass velocity (Gn)Gn)

Gn = Wg/AnGn = Wg/An

Where,Where,

Wg = Mass gas flow, lb/hrWg = Mass gas flow, lb/hr

An = Net free area, ft2An = Net free area, ft2

Net Free Area, An:Net Free Area, An:

An = Ad - Ac * Le * NtAn = Ad - Ac * Le * Nt

Where,Where,

Ad = Cross sectional area of box, ft2Ad = Cross sectional area of box, ft2Ac = Fin tube cross sectional area/ft, ft2/ftAc = Fin tube cross sectional area/ft, ft2/ftLe = Effective tube length, ftLe = Effective tube length, ftNt = Number tubes wideNt = Number tubes wideAd = Nt * Le * Pt / 12Ad = Nt * Le * Pt / 12Ac = (do + 2 * lf * tf * nf) / 12Ac = (do + 2 * lf * tf * nf) / 12tf = fin thickness, intf = fin thickness, innf = number of fins, fins/innf = number of fins, fins/in

Efficiency CalculationEfficiency Calculation

EE=(=(QQ//qrlsqrls)*)*100100

Q= qrQ= qr++qcqc

qrls:Heat released by qrls:Heat released by burner ,BTU/hrburner ,BTU/hr

qrlsqrls==Wfuel Wfuel **LhvfuelLhvfuel

ThicknessThickness

tt=(=(PriPri/(/(SEJ-0.6PSEJ-0.6P))+))+CcCc

t : thickness in (inch)t : thickness in (inch)

p: internal pressure in (psig)p: internal pressure in (psig)

ri: inside radius in (inch)ri: inside radius in (inch)

S: working stress (psi)S: working stress (psi)

EJ: efficiency 0f jointEJ: efficiency 0f joint

Cc: allowance for corrosion in (inch)Cc: allowance for corrosion in (inch)

ResultsResults

qrqr7.37E+06 (BTU7.37E+06 (BTU//hrhr((

qcqc9.19E+04 (BTU9.19E+04 (BTU//hr)hr)

QRQR7.46E+06 (BTU7.46E+06 (BTU//hr)hr)

Qconv.Qconv.2.71E+06 (BTU2.71E+06 (BTU//hr)hr)

Qtotal Qtotal 1.02E+07 (BTU1.02E+07 (BTU//hr)hr)

insulationinsulationGlass wall and Glass wall and quartzquartz

thicknessthickness0.85290295 (in) 0.85290295 (in)

costcost1908300 $ 1908300 $

ReactorReactor

Packed bed reactorPacked bed reactor A catalytic fixed bed reactor is a A catalytic fixed bed reactor is a

cylindrical tube, randomly filled with cylindrical tube, randomly filled with catalyst particlescatalyst particles

Objective: main reactor of plant and used Objective: main reactor of plant and used to produce ethylbenzene to produce ethylbenzene

Reaction involves:Reaction involves:

C6H6 + C2H4 C6H6 + C2H4 C6H5C2H5 C6H5C2H5

AssumptionsAssumptions

1. Assume that each bed is reactor to 1. Assume that each bed is reactor to calculate the main reactor dimensionscalculate the main reactor dimensions

2. Assume (L/D)=0.135 (for first bed) and2. Assume (L/D)=0.135 (for first bed) andOther beds (L/D) = 0.0829Other beds (L/D) = 0.0829

3. Assume the space between each 3. Assume the space between each bed=2.75 ftbed=2.75 ft

DESIGN OF BACKED BED DESIGN OF BACKED BED REACTORREACTOR

Design equation :Design equation :

Rate low and Rate low and stoichometry :stoichometry :

0

00

0

0

1 P

P

T

T

x

xPP

y

y

y

PkPr

iAi

A

Ai

A

BAA

Arrhenius Arrhenius equationequation : :

A=0.69E6A=0.69E6

Ea= -6.344E4Ea= -6.344E4

R=83.14R=83.14

Energy equation:Energy equation:

Volume of the reactorVolume of the reactor

All the previous equations will solved All the previous equations will solved by polymath simulator.by polymath simulator.

The result of the simulation will be The result of the simulation will be the volume of the reactor (1 bed).the volume of the reactor (1 bed).

From the volume equation we can get From the volume equation we can get the diameter of the reactor and the the diameter of the reactor and the height of each bed height of each bed

Polymath for volumePolymath for volume

volume of the reactorvolume of the reactor

Equation :Equation :

From (L/D) assumption From (L/D) assumption

The height of bedThe height of bed

and diameter Of and diameter Of

The reactor can be calculatedThe reactor can be calculated

Height of reactorHeight of reactor

From our calculation and assumption From our calculation and assumption the height of the reactor can be the height of the reactor can be calculated.calculated.

- H= (space high* no. of spaces) + first - H= (space high* no. of spaces) + first bed high + (high of each of fife bed* no. bed high + (high of each of fife bed* no. of beds)* (dome high*no. of dome) of beds)* (dome high*no. of dome)

- Dome high= dimeter/2 - Dome high= dimeter/2

Area: 2πrhArea: 2πrh

Weight of the catalystWeight of the catalyst

W= V (1-ε) ρ , ρ = catalyst W= V (1-ε) ρ , ρ = catalyst density density

ResultsResults

Diameter Diameter 2.743 2.743 m m

heightheight10.1310.13 mm

volumevolume6060 m^3m^3

areaarea87.29587787.295877 m^2m^2

Weight of catalystWeight of catalyst2399.762399.76 kgcatkgcat

thicknessthickness0.1530.153 mm

costcost14996881499688$ $

compressorcompressorObjective: To increase the pressure of Objective: To increase the pressure of

the feed from 14.5 to 72.52 (psia) the feed from 14.5 to 72.52 (psia)

Choosing the compressor typeChoosing the compressor type..

- Calculate the Calculate the compression factor (n) compression factor (n) using the following using the following equationequation::

Where, Where,

P1,2 : is the pressure of P1,2 : is the pressure of inlet and outlet inlet and outlet respectively (psia)respectively (psia)

T1,2 : is the T1,2 : is the temperature of the temperature of the inlet and outlet inlet and outlet respectivelyrespectively (R) (R)

11 1

2 2

n

nP T

P T

Calculate the work done in Btu/lbmol by:

Where, R is the ratio of the

specific heat capacities (Cp/Cv)

3. Calculate the horse power, Hp using the following equation:

Hp=W*M

Where, M is the molar flow rate in lbmol/s

4. Calculate the efficiency of the compressor using the following equation:

1 2( )

1

nR T TW

n

1

1

nnEp

KK

- - Where , Where ,

Mw :is the Mw :is the molecular weight molecular weight of the gas in the of the gas in the streamstream

CP :is the specific CP :is the specific heat capacity heat capacity (Btu/lb◦ F )(Btu/lb◦ F )

1.986p

p

MwCK

MwC

ResultResult

Inlet TemperatureInlet Temperature1221 (oC)1221 (oC)

Inlet PressureInlet Pressure14.5 (psia)14.5 (psia)

EfficiencyEfficiency75.96 (%)75.96 (%)

out Temperatureout Temperature1318.4 (oC)1318.4 (oC)

out Pressureout Pressure72.52 (psia)72.52 (psia)

Power (Hp)Power (Hp) 197.913197.913 (hp)(hp)

costcost119100119100 $ $

AbsorberAbsorber

AbsorberAbsorber

Objective : to separate the vent gas and Objective : to separate the vent gas and

waste from the feed waste from the feed

Material : carbon steel Material : carbon steel

AssumptionAssumption

Plate spacing = 0.8 mPlate spacing = 0.8 m

Absorber designAbsorber design

the column diameter:the column diameter:

Flv Flv = (= (Lw Lw / / VwVw) * () * (ρρv v / / ρρll) ) ^0.5^0.5

Where,Where,

Lw : liquid mass flow rate (kg/s)Lw : liquid mass flow rate (kg/s)

Vw : Vapor mass flow rate (kg/s)Vw : Vapor mass flow rate (kg/s)

Flv : liquid vapor flow factorFlv : liquid vapor flow factor

we assumed try spacingwe assumed try spacing

From the figure we get K1From the figure we get K1

- - Correction for surface tension:Correction for surface tension:

K1 = (surface K1 = (surface tention*1E3/20)^.2 * K1tention*1E3/20)^.2 * K1

Where,Where,

K1: correction for surface K1: correction for surface tensiontension

Flooding vapor velocity :Flooding vapor velocity :

uf uf = = K1K1((((ρρll--ρρvv)/)/ρρvv) ) ^̂..55

Where,Where,

uf : flooding vapor velocity (m/s)uf : flooding vapor velocity (m/s)

Design for 85%flooding at maximum Design for 85%flooding at maximum flow rateflow rate

ŭf = uf*0.85ŭf = uf*0.85

maximum volumetric flow rate =maximum volumetric flow rate =

flow rate/densityflow rate/density

net area required =net area required =

( volumetric flow rate / uf )max( volumetric flow rate / uf )max

Take down comer area as 12 % of Take down comer area as 12 % of total areatotal area

A = A net *0.88 (m2)A = A net *0.88 (m2)

column diameter column diameter =(=(areaarea**44//ππ))^̂..55

Maximum volumetric liquid rateMaximum volumetric liquid rate

Maximum volumetric liquid rate Maximum volumetric liquid rate

l

bottomMwL

*3600

Column height:Column height:

h =(actual number of stages* tray spacing )h =(actual number of stages* tray spacing )+Dmax+Dmax

Where,Where,

h: column height (m)h: column height (m)

Actual number of stage = Efficiency * Actual number of stage = Efficiency * #of stage #of stage

Provisional plate design:Provisional plate design:

Where,Where,

Dc: column diameter (m)Dc: column diameter (m)

Ac: column area for cylinder = (m2)Ac: column area for cylinder = (m2)

An: down comer area = 0.12*Ac An: down comer area = 0.12*Ac (m2)(m2)

Aa: active area= Ac-2Ad (m2)Aa: active area= Ac-2Ad (m2)

Ah :hole area by taking 10% of AaAh :hole area by taking 10% of Aa

- Check weeping- Check weeping

Maximum liquid rate= lw*MW (Kg/s)Maximum liquid rate= lw*MW (Kg/s)

Minimum liquid rate @ 70% turn-down Minimum liquid rate @ 70% turn-down =0.7*max liquid rate (Kg/s)=0.7*max liquid rate (Kg/s)

Height of the liquid crest over weirHeight of the liquid crest over weir

how = 750*(Lw/ρl * lw)^(2/3)how = 750*(Lw/ρl * lw)^(2/3) in (mm)in (mm)

Assuming,Assuming,

take hole diameter(mm)take hole diameter(mm)

plate thickness (mm)plate thickness (mm)

weir height(hw) (mm)weir height(hw) (mm)

at minimum rate hw + howat minimum rate hw + how

from figure @ hw + how we get K2 from figure @ hw + how we get K2

Vapor velocity = (K2-0.9*(25.4-Vapor velocity = (K2-0.9*(25.4-dh))/(ρv ^.5)dh))/(ρv ^.5)

Where,Where,

uh : vapor velocityuh : vapor velocity

K2 : constantK2 : constant

dh : hole diameter (mm)dh : hole diameter (mm)

Actual minimum vapor velocity = Actual minimum vapor velocity = minimum vapor rate / Ahminimum vapor rate / Ah

Plate pressure dropPlate pressure drop

Maximum vapor velocity through holes = Max Maximum vapor velocity through holes = Max volumetric flow rate/Ahvolumetric flow rate/Ah

From figureFrom figure

For plate thickness/ hole diameter =1, and For plate thickness/ hole diameter =1, and Ah/Ap = Ah/Aa =0.1Ah/Ap = Ah/Aa =0.1

We find Co.We find Co.

hd hd = = 51 51 *( *( uhuh//CoCo))^2 ^2 * (* (ρρv v //ρρll))

hr hr = (= (12.512.5**10001000) /) /ρρll

ht = hd +(weir length +how )+hrht = hd +(weir length +how )+hr

Where,Where,

hd: dry plat drop (mm liquid)hd: dry plat drop (mm liquid)

hr :residual head (mm liquid)hr :residual head (mm liquid)

ht: total pressure drop (mm liquid)ht: total pressure drop (mm liquid)

ThicknessThickness

( t) = (Pri/ SE-0.6P)+C,( t) = (Pri/ SE-0.6P)+C, (t in (in)) (t in (in))

Where,Where,t: thickness (in)t: thickness (in)p: Internal pressure (psig)p: Internal pressure (psig)ri: Inside radius (in)ri: Inside radius (in)S: Working stress (psi)S: Working stress (psi)Ej: Efficiency 0f jointEj: Efficiency 0f jointCc: Allowance for corrosion (in)Cc: Allowance for corrosion (in)

Down comer back upDown comer back up

Take hap (mm) = hw - 10Take hap (mm) = hw - 10

Area under apron (m2) =0.6*hapArea under apron (m2) =0.6*hap

As this less than Ad use Aao(m2)As this less than Ad use Aao(m2)

Head loss in the down comer (mm)=Head loss in the down comer (mm)=

hdc hdc = = 166166*(*(LwdLwd//ρρl l * * AmAm))^2^2

Lwd: liquid flow rate in down comer Lwd: liquid flow rate in down comer (kg/s)(kg/s)

Am: either Ad , or Aad (the smaller ) Am: either Ad , or Aad (the smaller ) (m2)(m2)

hb (mm) = hw +how +ht +hdchb (mm) = hw +how +ht +hdc

Number of holes:Number of holes:

Area of on hole (m2) =Number of Area of on hole (m2) =Number of holes=holes=

hole area/area of one holehole area/area of one hole

weight of the metalweight of the metal

di= Internal column diameter (m)di= Internal column diameter (m)

do=di+2t (m)do=di+2t (m)

Volume of cylinder (di) m3=(3.141*H)*(di/2)^2Volume of cylinder (di) m3=(3.141*H)*(di/2)^2

Volume of cylinder (do) m3=(3.141*H)*(do/2)^2Volume of cylinder (do) m3=(3.141*H)*(do/2)^2

Volume of metal m3= Volume of metal m3=

volume of cylinder (do)- volume of cylinder (di)volume of cylinder (do)- volume of cylinder (di)

Weight (Kg)= volume of metal *7900Weight (Kg)= volume of metal *7900

ResultResult

diameterdiameter1.751.75 mm

thicknessthickness0.1250.125 mm

costcost103500 $103500 $

Volume of metalVolume of metal1.4441.444 mm

Weight of metalWeight of metal 11118.811118.8 kgkg

HeightHeight 77 mm

Thank youThank you