March 18-20 2013 öteborg, Sweden Steam Power Plant … · March 18-20 2013 Göteborg, Sweden Steam Power Plant Optimization & Retrofit in An Industrial Park at Chih-YaoLin ·Jui-YuanLee

March 18-20 2013Goteborg, Sweden

Steam Power Plant Optimization & Retrofit

in An Industrial Park at

Chih-Yao Lin · Jui-Yuan Lee

Cheng-Liang Chen

PSELABORATORY

Department of Chemical EngineeringNational TAIWAN University

Chen CL 1

Steam Power Plant Optimization & RetrofitAn Industrial Park at Taiwan

An Industrial Park at Taiwan – Original design

and recent trend to total site integration

Superstructure-based MINLP Formulationfor total site heat and power integration


A steel mill

A petroleum refinery

Concluding Remarks

Chen CL 2



A Steel Mill and A Petroleum Plant

Chen CL 3


Chen CL 4


Chen CL 5


Chen CL 6


Chen CL 7


Original design (∼1975): independent operation

Chen CL 8



Chen CL 8



95→11 Elec

Europe ×1.5USAsia ×1.0

Chen CL 8



95→11 Elec

Europe ×1.5USAsia ×1.0

95→11 Elec Fuel

Europe ×1.5 ×4USAsia ×1.0

Chen CL 9


Recent trend: enhanced total site M/E integration

?

?

Steam Power Plant Optimization & Retrofit?

Chen CL 10



Superstructure-based MINLP Formulation

Chen CL 11

Steam Power Plant Optimization & RetrofitSuperstructures for Steam Distribution System

Chen CL 12

Steam Power Plant Optimization & RetrofitSuperstructures for Steam Distribution System

Unit

Models

Chen CL 13

Steam Power Plant Optimization & RetrofitModeling the Superstructures

Ω1 =

x

∣∣∣∣∣∣∣∣∣∣∣∣∣∣

fbfwb =

∑i∈I

fbi +∑i∈I

fbdbi ∀b ∈ B

fbfwb Hdeaer + qb =

∑i∈I

fbihbi +∑i∈I

fbdbi H

sat,li ∀b ∈ B

fbdbi = ϕfbi ∀b ∈ B, i ∈ I

fbu =Zbuqb

ηbHLHVu

∀b ∈ B, u ∈ U

Ωbzbi ≤ fbi ≤ Ωbzbi ∀b ∈ B, i ∈ I

zb =∑i∈I

zbi ∀b ∈ B

Boiler

Chen CL 13


Ω1 =

x

∣∣∣∣∣∣∣∣∣∣∣∣∣∣

fbfwb =

∑i∈I

fbi +∑i∈I

fbdbi ∀b ∈ B

fbfwb Hdeaer + qb =

∑i∈I

fbihbi +∑i∈I

fbdbi H

sat,li ∀b ∈ B

fbdbi = ϕfbi ∀b ∈ B, i ∈ I

fbu =Zbuqb

ηbHLHVu

∀b ∈ B, u ∈ U

Ωbzbi ≤ fbi ≤ Ωbzbi ∀b ∈ B, i ∈ I

zb =∑i∈I

zbi ∀b ∈ B

Boiler

material andenergy balances

blowdown ratio

fuel type/rate

upper/lowercapacitis ↑

one boiler connected toone single steam header

Chen CL 14


header i

↓turbine t

↓header i′

Ω2 =

x

∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣

wii′t = 4hisii′t

Lii′+1

Bii′fii′t − Lii′W

dii′t − (Lii′ + 1)

Aii′Bii′

∀i, i′ ∈ I, t ∈ C

fii′thii′t = fii′t(hi − 0.8384 hisii′t) + 809.721 ∀i, i′ ∈ I, t ∈ C

Lii′ = aL + bL 4 T satii′ ∀i, i′ ∈ I

Aii′ = a0 + a1 4 T satii′ ∀i, i′ ∈ I

Bii′ = a2 + a3 4 T satii′ ∀i, i′ ∈ I

qcwii′t = fii′t(hii′t − hi′t) ∀i, i′ ∈ I, t ∈ CT

zii′t ≤ zt ≤∑

i, i′ ∈ Ii < i′

zii′t ∀i, i′ ∈ I, i < i

′, t ∈ T

Ωtzii′t ≤ fii′t ≤ Ωtzii′t ∀i, i′ ∈ I, i < i′, t ∈ T

Γtzii′t ≤ wii′t ≤ Γtzii′t ∀i, i′ ∈ I, i < i′, t ∈ T

SteamTurbine

Chen CL 14


header i

↓turbine t

↓header i′

Ω2 =

x

∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣

wii′t = 4hisii′t

Lii′+1

Bii′fii′t − Lii′W

dii′t − (Lii′ + 1)

Aii′Bii′

∀i, i′ ∈ I, t ∈ C

fii′thii′t = fii′t(hi − 0.8384 hisii′t) + 809.721 ∀i, i′ ∈ I, t ∈ C

Lii′ = aL + bL 4 T satii′ ∀i, i′ ∈ I

Aii′ = a0 + a1 4 T satii′ ∀i, i′ ∈ I

Bii′ = a2 + a3 4 T satii′ ∀i, i′ ∈ I

qcwii′t = fii′t(hii′t − hi′t) ∀i, i′ ∈ I, t ∈ CT

zii′t ≤ zt ≤∑

i, i′ ∈ Ii < i′

zii′t ∀i, i′ ∈ I, i < i

′, t ∈ T

Ωtzii′t ≤ fii′t ≤ Ωtzii′t ∀i, i′ ∈ I, i < i′, t ∈ T

Γtzii′t ≤ wii′t ≤ Γtzii′t ∀i, i′ ∈ I, i < i′, t ∈ T

SteamTurbine

linear unit model

regressioncoefficients −→CW for CT −→

turbine t exists if steam from i

passes it to i′

steam turbine tdoes not existif no steam

passes itfrom any i

to any i′

Chen CL 15


Ω3 =

x

∣∣∣∣∣∣∣∣∣∣

∑i∈I

fi + fc+ f

w=

∑b∈B

fbfwb +

∑i∈I

fldi

∑i∈I

fihi + fcH

c+ f

wH

w=

( ∑b∈B

fbfwb +

∑i∈I

fldi

)H

deaer

ΩD ≤∑i∈I

fi + fc+ f

w ≤ ΩD

Deaerator

Chen CL 16


Ω4 =

x

∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣

∑b∈B

fbi +∑

i′ ∈ Ii′ < i

∑t∈T

fi′it +∑

i′ ∈ Ii′ < i

fi′i + fldi + F

psi + f

imp,si

=∑

i′ ∈ Ii′ > i

∑t∈T

fii′t +∑

i′ ∈ Ii′ > i

fii′ + Fpdi + fi + f

venti + f

exp,si ∀i ∈ I

∑b∈B

fbihbi +∑

i′ ∈ Ii′ < i

∑t∈T

fi′ithi′it +∑

i′ ∈ Ii′ < i

fi′ihi′ + fldi H

deaer+ F

psi H

psi + f

imp,si H

imp,si

=( ∑

i′ ∈ Ii′ > i

∑t∈T

fii′t +∑

i′ ∈ Ii′ > i

fii′ + Fpdi + fi + f

venti + f

exp,si

)hi ∀i ∈ I

SteamHeader

Chen CL 17


Ω5 =

x

∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣

∑i, i′ ∈ Ii < i′

wii′t =∑j∈J

wtj ∀t ∈ T S

zt =∑j∈J

ztj ∀t ∈ T S

Γtztj ≤ wtj ≤ Γtztj ∀j ∈ J , t ∈ T S

∑t∈T S

wtj +∑

m∈Mwmj = W

dem,sj ∀j ∈ J

∑i, i′ ∈ Ii < i′

∑t∈T E

wii′t + wimp,e

= Wdem,e

+∑

m∈M

∑j∈J

wmj

ηm+ w

exp,e

zimp,e + zexp,e ≤ 1

wimp,e ≤ Ω zimp,e

wexp,e ≤ Ω zexp,e

PowerBalance

Chen CL 17


Ω5 =

x

∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣

∑i, i′ ∈ Ii < i′

wii′t =∑j∈J

wtj ∀t ∈ T S

zt =∑j∈J

ztj ∀t ∈ T S

Γtztj ≤ wtj ≤ Γtztj ∀j ∈ J , t ∈ T S

∑t∈T S

wtj +∑

m∈Mwmj = W

dem,sj ∀j ∈ J

∑i, i′ ∈ Ii < i′

∑t∈T E

wii′t + wimp,e

= Wdem,e

+∑

m∈M

∑j∈J

wmj

ηm+ w

exp,e

zimp,e + zexp,e ≤ 1

wimp,e ≤ Ω zimp,e

wexp,e ≤ Ω zexp,e

PowerBalance

shaft demand W dem,sj

andelectricity de. W dem,e

are givenshaft balance −→

shaft demandprovided byturbine or motor

electricity balance

to prevent coexistenceof powerimport/export

Chen CL 18

Steam Power Plant Optimization & RetrofitMINLP Formulation

minx∈Ω

J =[

Cwfw + C imp,ewimp,e − Cexp,ewexp,e (water; electricity imp/exp)

+∑b∈B

∑u∈U

Cufbu +∑

i,i′∈I

∑t∈T C

Ccwqcwii′t (fuels; cooling)

+∑i∈I

(C imp,s

i f imp,si − Cexp,s

i f exp,si

) ]thrs (steam import/export)

− JAOCbase + JAIC

retrofit (base AOC; retrofit cost)

Ω = Ω1 ∩ · · · ∩ Ω5 (searching space)

x ≡

zb, zt, zm; zbi, zii′t, ztj; zimp,e, zexp,e;

fbfwb , fbu, fbi, f

bdbi ; fi, f

ldi , f imp,s

i , f exp,si , f vent

i ;

fii′, fii′t; f c, fw; hi, hbi, hii′t;

qb, qcwii′t; wii′t, wtj, wmj; wimp,e, wexp,e

∀b ∈ B, u ∈ U , t ∈ T ,m ∈M, i ∈ I, j ∈ J

(variables)

Minimizing AOC

or

Max Retrofit Benefit

Chen CL 19



The Steel Mill

Chen CL 20


?

?

Chen CL 21

Steam Power Plant Optimization & RetrofitA Steel Mill: Current Status

B3: coal, B1, B2, B4: SG; ΩB′is= 375, 750, 600, 800

Chen CL 22


B3: coal, B1, B2, B4: SG; ΩB′is= 375, 750, 600, 800

Total working hours 8,600 hr/yr

Coal LHV 28,000 kJ/kg

Synthesis gas LHV 52,000 kJ/kg

Electricity price (export) 0.0833 USD/kWh

Steam price (for export) 33.333 USD/ton

Coal price 120 USD/ton

Synthesis gas price 192 USD/ton

Synthesis gas flow rate 75.5 ton/hr

Steam demand (17.6 kg/cm2) 300 ton/hr

Steam demand ( 2.0 kg/cm2) 278 ton/hr

Power demands 300 MW

Shaft power demand 1 25 MW

Shaft power demand 2 30 MW

Chen CL 23


B3: coal, B1, B2, B4: SG; ΩB′is= 375, 750, 600, 800

Power self-sufficient Power import allow

Optimization Scenario 1 Scenario 3

Retrofit Scenario 2 Scenario 4

Chen CL 24


AOC 164.53∆AOC -

T I C -PB (y) -

mUSD/y

Chen CL 25

Steam Power Plant Optimization & RetrofitA Steel Mill: Scenario 1 – Power Self-sufficient?

AOC 164.53∆AOC -

T I C -PB (y) -

Chen CL 25

Steam Power Plant Optimization & RetrofitA Steel Mill: Scenario 1 – Power Self-sufficient?

AOC 164.53∆AOC -

T I C -PB (y) -

zb=1 =1 zexp,e=0zbi=11=1 zimp,e=0

i = 1zt=4 zb=3 zb=4

zbi=32 zbi=42

i = 2zb=2zbi=23 zt=5 zt=6 zt=7

i = 3 ztj=72

zt=1 zt=2 zt=3i = 4 ztj=31 i = 4

zii′t=342 zii′t=144 zii′t=246

i = 5zii′t=255

zii′t=361 zii′t=362 zii′t=363 zii′t=164 zii′t=265 zii′t=266 zii′t=267i = 6 i = 6

Chen CL 26

Steam Power Plant Optimization & RetrofitA Steel Mill: Scenario 1 – Power Self-sufficient

AOC 164.53 133.31∆AOC - -33.22

T I C - -PB (y) - -

Chen CL 26


AOC 164.53 133.31∆AOC - -33.22

T I C - -PB (y) - -

reduceMHP steam

turn off ST1(condensing)

Chen CL 26


AOC 164.53 133.31∆AOC - -33.22

T I C - -PB (y) - -

reduceMHP steam


increaseHP steam

increase←−VHP steam

Chen CL 26


AOC 164.53 133.31∆AOC - -33.22

T I C - -PB (y) - -

reduceMHP steam


increaseHP steam


increase MP steam extraction

inc. exportMP steam

Chen CL 26


AOC 164.53 133.31∆AOC - -33.22

T I C - -PB (y) - -

reduceMHP steam


increaseHP steam



inc. exportMP steam

increaseelectricitygeneration

stop exportelectricity

↓ 20%

Chen CL 27


AOC 164.53 133.31∆AOC - -33.22

T I C - -PB (y) - -

reduceMHP steam


increaseHP steam



inc. exportMP steam

increaseelectricitygeneration


zt=8=1zii′t=248zii′t=258zii′t=268

reach maxcapacity

−→ ←−space forexpansion

Chen CL 28


AOC 164.53 133.31 123.92∆AOC - -33.22 -9.39

T I C - - 5.00PB (y) - - 0.53

reduceMHP steam

turn off ST1, ST2(condensing)

increaseHP steam



inc. exportMP steam


inc.electricity

newST8

zt=8=1zii′t=248=1zii′t=258=0zii′t=268=0

↓ 7%

Chen CL 29

Steam Power Plant Optimization & RetrofitA Steel Mill: Scenario 3 – Power Import Allow

AOC 164.53 133.31 123.92 72.24∆AOC - -33.22 -9.39 -92.26

T I C - - 5.00 -PB (y) - - 0.53 -

reduceMHP steam


increaseHP steam



inc. exportMP steam

decreaseelectricitygeneration

importelectricity

Chen CL 30

Steam Power Plant Optimization & RetrofitA Steel Mill: Scenario 4 – Power Import Allow

AOC 164.53 133.31 123.92 72.24 53.46∆AOC - -33.22 -9.39 -92.26 -18.78

T I C - - 5.00 - 5.00PB (y) - - 0.53 - 0.27

reduceMHP steam

turn off ST1, ST2(condensing)

increaseHP steam



max exportMP steam

importelectricity

dec.electricity

newST8

Chen CL 31

Steam Power Plant Optimization & RetrofitA Steel Mill: Summaries

Power Self-sufficient Power Import Allow

Current Optimization Retrofit Optimization RetrofitAOC 164.53 133.31 123.92 72.24 53.46

∆AOC - -33.22 -9.39 -92.26 -18.78

T I C - - 5.00 - 5.00

PB (y) - - 0.53 - 0.27

Decrease condensing rate Reduce power generation

Increase MP steam(17.6 kg

cm2

) More MP steam export

Operational Optimization ⇒ Annual operating cost reduced by 20%

Chen CL 32



The Petroleum Plant

Chen CL 33

Steam Power Plant Optimization & RetrofitAn Industrial Park in Taiwan

?

?

Chen CL 34

Steam Power Plant Optimization & RetrofitA Petroleum Plant: Current Status

Existing layout and current operating conditions

Chen CL 34


Existing layout and current operating conditions

Total working hours 8,000 hr/yr

Fuel oil LHV 28,000 kJ/kg

Synthesis gas LHV 42,800 kJ/kg

Electricity price (import) 0.1267 USD/kWh

Steam price (import) 33.333 USD/ton

Fuel price (oil) 824.33 USD/ton

Steam demand (101.0 bar) 13.0 ton/hr



Power demand 81.3 MW

Shaft power demand 1 15.2 MW



65% of self-production←− cost

Chen CL 35


Existent layout and current operating conditionsAOC 299.28

∆AOC -T I C -

PB (y) -

mUSD/y

Chen CL 36

Steam Power Plant Optimization & RetrofitA Petroleum Plant: Scenario 1

Best operating conditions without modifying layout and units?AOC 299.28

∆AOC -T I C -

PB (y) -

Chen CL 36


Best operating conditions without modifying layout and units?AOC 299.28

∆AOC -T I C -

PB (y) -

zb=1 zexp,e, zimp,e zb=2zbi=11 zbi=22

i = 1 i = 2

zb=3 zb=4 zt=1 zt=2zbi=33 zbi=43 ztj=21

i = 3

zt=3 zt=4ztj=32 ztj=43

i = 4zii′t=344


i = 5

zii′t=131

Chen CL 37


Best operating conditions without modifying layout and unitsAOC 299.28 297.19

∆AOC - -2.09T I C - -

PB (y) - -

increaseVHP steam

decrease MP steam

increaseMP steamextraction &electricity

Chen CL 38


Retrofit of steam system without installing new equipment?AOC 299.28 297.19

∆AOC - -2.09T I C - -

PB (y) - -

Chen CL 38



∆AOC - -2.09T I C - -

PB (y) - -

excess MPlarge let-down

less LP

Chen CL 39



∆AOC - -2.09T I C - -

PB (y) - -

zb=1 zexp,e, zimp,e zb=2zbi=11 zbi=22

i = 1 i = 2

zb=3 zb=4 zt=1 zt=2zbi=33 zbi=43 ztj=21

i = 3

zt=3 zt=4ztj=32 ztj=43

i = 4zii′t=344


i = 5

zii′t=131

zii′t=141

Chen CL 40


Retrofit of steam system without installing new equipmentAOC 299.28 297.19 261.85

∆AOC - -2.09 -35.35T I C - - 10.00

PB (y) - - 0.28

increaseVHP steam

turn off B3, B4


condensingturbine

⇒ extractionturbine

reducelet-down

MP→LP

↓ 12%

Chen CL 41


Retrofit of steam system with installing new equipmentAOC 299.28 297.19 261.85 257.84

∆AOC - -2.09 -35.35 -4.00T I C - - 10.00 5.00

PB (y) - - 0.28 1.25

increaseVHP steam

turn off B3, B4


condensingturbine


reducelet-downHP→MP→LP

new ST5

zt=5=1zii′t=235=1zii′t=245=0zii′t=255=0

Chen CL 42


Integration of steam import in a steam systemAOC 299.28 297.19 261.85 257.84 253.95

∆AOC - -2.09 -35.35 -4.00 -3.89T I C - - 10.00 5.00 2.50

PB (y) - - 0.28 1.25 0.64

turn off B3, B4


condensingturbine


reducelet-downHP→MP→LP

new ST5

steamejector

↑import steamfrom steel mill

Chen CL 43


Integration of steam import in a steam system

Chen CL 43


Integration of steam import in a steam system

Chen CL 44

Steam Power Plant Optimization & RetrofitA Petroleum Plant: Summaries

Optimization Retrofit

Current Current Without With Steam(106 USD/yr) Condition Layout New Unit New Unit Ejector

AOC 299.28 297.19 261.85 257.84 253.95

∆AOC - -2.09 -35.35 -4.00 -3.89

T I C - - 10.00 5.00 2.50

PB (y) - - 0.28 1.25 0.64

Condensing → Extraction turbine Decrease power generation

Increase HP steam (101 bar) Import more MP & enhanced by HP

Installed cost ≈ 10 mUSD ⇒ AOC reduced by 12.5%

Chen CL 45


Chen CL 46


Chen CL 47

Steam Power Plants Retrofitin An Industrial Park at Thank You

Questions ?

March 18-20 2013 öteborg, Sweden Steam Power Plant … · March 18-20 2013 Göteborg, Sweden Steam Power Plant Optimization & Retrofit in An Industrial Park at Chih-YaoLin ·Jui-YuanLee

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