Evaporator - Multiple stage

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    Simulation of a multiple-effect evaporator

    Instructions

    2. For a forward feed 2-effect evaporator

    In the spreadsheet "2-Effect"

    a. Insert parameter values in the yellow cells

    b. Turn the "SWITC" ! #set the value in the cell $% #red cell& e'ual to (&

    c. Iterate #by pressin) *%& until "*IIS" or "+,+" si)nal is shown in the control panel

    in cells $2/ or $2% respectively and start a)ain from 2b

    in cells $2/ or $2% respectively and start a)ain from 2b f. When "*IIS" is shown in the control panel0 read the results in the )reen cells #$1-$1

    and repeat steps 2a to 2f

    h. To recalculate for different parameter values turn the "SWITC" !** #set the value in th

    3. For a forward-feed 4-effect evaporator

    In the spreadsheet "-Effect *orward"

    a. Insert parameter values in the yellow cells

    b. Turn the "SWITC" ! #set the value in the cell $% #red cell& e'ual to (& c. Iterate #by pressin) *%& until "*IIS" or "+,+" si)nal is shown in the control panel

    in the cells $2/ or $2% respectively and start a)ain from 2b

    in the cells $2/ or $2% respectively and start a)ain from 2b

    f. When "*IIS" is shown in the control panel0 read the results in the )reen cells #$11-$1

    and5or 6(% and repeat steps 2a to 2f

    h. To recalculate for different parameter values turn the "SWITC" !** #set the value in th

    4. For a backward-feed 4-effect evaporator

    In the spreadsheet "-Effect $ac7ward"

    a. Insert parameter values in the yellow cells

    b. Turn the "SWITC" ! #set the value in the cell $% #red cell& e'ual to (&

    c. Iterate #by pressin) *%& until "*IIS" or "+,+" si)nal is shown in the control panel

    1. a. !n the Toolsmenu0 clic7 Options0 then clic7 the Calculationtab and tic7 on theterati

    d. If a si)nal to "E89CE Tsor m

    win" is shown in the control panel0 turn the SWITC !**0

    e. If a si)nal to "ICE+SE Tsor m

    win" is shown in the control panel0 turn the SWITC !*

    ). If a solution can not be reached under any combination of Ts

    and mwin

    values0 chan)e th

    d. If a si)nal to "E89CE Tsor m

    win" is shown in the control panel0 turn the SWITC !**0

    e. If a si)nal to "ICE+SE Tsor m

    win" is shown in the control panel0 turn the SWITC !*

    ). If a solution can not be reached under any combination of Tsand m

    winvalues0 chan)e th

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    in the cells $2/ or $2% respectively and start a)ain from 2b

    in the cells $2/ or $2% respectively and start a)ain from 2b

    f. When "*IIS" is shown in the control panel0 read the results in the )reen cells #$11-$1

    and5or 6(% and repeat steps 2a to 2f

    h. To recalculate for different parameter values turn the "SWITC" !** #set the value in th

    d. If a si)nal to "E89CE Tsor m

    win" is shown in the control panel0 turn the SWITC !**0

    e. If a si)nal to "ICE+SE Tsor m

    win" is shown in the control panel0 turn the SWITC !*

    ). If a solution can not be reached under any combination of Tsand m

    winvalues0 chan)e th

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    /&

    e cell $% e'ual to 3& and repeat steps 2a to 2f

    4&

    e cell $% e'ual to 3& and repeat steps 2a to 2f

    onbo;. !n !a"imum iterationsbo; write (333

    reduce the value of either Tsor m

    win

    0 increase the value of either Tsor m

    win

    e heat transfer area in the cells (% and5or :(% and5or (%

    reduce the value of either Tsor m

    win

    0 increase the value of either Tsor m

    win

    e heat transfer area in the cells (% and5or :(% and5or ,(% and5or (%

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    4&

    e cell $% e'ual to 3& and repeat steps 2a to 2f

    reduce the value of either Tsor m

    win

    0 increase the value of either Tsor m

    win

    e heat transfer area in the cells (% and5or :(% and5or ,(% and5or (%

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    T#e followin$ assumptions are used

    (& The pressure drop in the vapour lines is ne)lected

    2& The effect of superheatin) on the vapour enthalpy due to the $ation of water0 7:57)

    f& ?apour pressure of li'uid water0 atm #ef. (=&

    1& The heat losses to the environment are ta7en into account. If cells $21 or $2 for 9los and

    a& eat capacity of li'uid foods #e'uation of 8ic7erson&0 :57)oC

    where ;wis the mass fraction of water content

    b& $oilin)

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    where with T in Kelvin=273 .16

    T

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    o,are set e'ual to 30 the heat losses are ne)lected

    )+0. 42873x 103 (104.76955 (1 )1 )2.2195983

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    Forward-Feed 2-%ffect %vaporator

    Control panel

    [email protected] (

    F&S'%(

    3.333

    nput data

    (3333 7)5h

    (3A

    13A

    43

    23

    3

    =3

    2=

    Control variables

    (22

    1/133 7)5h

    )esults

    1112 7)5h

    13.3A

    1%14 7)5h

    Steam economy (.4 7)57)

    1/133 7)5h

    *eed flow rate0 [email protected]

    *eed solids content0 ;[email protected]

    8esired product solids content0 Bspec

    @

    *eed temperature0 [email protected] oC

    Temperature of the environment0 [email protected] oC

    !verall eat transfer coeffic. for heat losses0 9los

    @ W5m2oC

    !utside +rea of each effect of the evaporator0 +o,@ m2

    Coolin) water temper. at the inlet of the cond.0 [email protected] oC

    Steam temperature0 [email protected] oC

    ass flow rate of coolin) water in the conden.0mWin

    @

    Concentrated product flow rate0 [email protected] content at the outlet0 ;

    [email protected]

    Steam consumption0 [email protected]

    Coolin) water flow rate0 mWin

    @

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    *arameters 1st %FF%CT 2nd %FF%CT C

    /3 /3 eat transf. area

    (/33 (333 !veral heat transf. coef.

    2.44/ (./4/ Coolin) water flow rate in

    3.( 3.(/ Coolin) water temper. in

    43 (3=.1 Water vapour temper. in

    (3=.1 4%./ Coolin) water temp. out

    (3=.3 4%.2 Condensation temperat.

    Saturation pressure #atm&0 < (.(% 3.=1 Water vapour pressure

    (.4 2=.2

    3.1 3.

    1%2% 1/3%

    1/3% 124

    3 3

    3./%% 3.%=1

    (./4/ 3.%2=

    3.(/ 3.133

    (.3% 3./%%

    (22 (3=.3

    eat transfer area #m2&0 +

    !verall heat transfer coef. #W5m2oC&0 9

    ,i'uid flow rate at the inlet #7)5s&0 mi

    Solids content at the inlet0 ;i

    ,i'uid temperature at the inlet #oC&0 Ti

    $oilin) temperature #oC&0 Tb

    Saturation temperature #oC&0 Tv

    Temperature drop #oC&0 D

    $oilin)

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    &(%&S%)

    =3

    2=33

    (3.1% 7)5s

    2=

    4%.2

    4.=

    4%.(

    3.=2 atm

    m2

    W5m2oC

    oC

    oC

    oC

    oC

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    Forward-Feed 4-%ffect %vaporator

    Control panel

    [email protected] (

    F&S'%(

    3.3333

    nput data

    23333 7)5h

    %A

    /A

    3

    23

    3

    =3

    2=

    Control variables

    4=

    =13333 7)5h

    )esults

    14= 7)5h

    4.%A

    2 7)5h

    Steam economy 1./ 7)57)

    =13333 7)5h

    *eed flow rate0 [email protected]

    *eed solids content0 ;[email protected]

    8esired product solids content0 Bspec

    @

    *eed temperature0 [email protected] oC

    Temperature of the environment0 [email protected] oC

    !verall eat transfer coeffic. for heat losses0 9los

    @ W5m2oC

    !utside +rea of each effect of the evaporator0 +o,@ m2

    Coolin) water temper. at the inlet of the cond.0 [email protected] oC

    Steam temperature0 [email protected] oC

    ass flow rate of coolin) water in the conden.0mWin

    @

    Concentrated product flow rate0 [email protected]

    Solids content at the outlet0 ;[email protected]

    Steam consumption0 [email protected]

    Coolin) water flow rate0 mWin

    @

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    1st %FF%CT 2nd %FF%CT 3rd %FF%CT 4t# %FF%CT

    243 243 243 243

    2233 (/33 (133 =3

    =.== ./( 1.142 2.213

    3.3% 3.((2 3.(/ 3.22

    3 43. =.3 =4.1

    43. =.3 =4.1 14.(

    43.2 .4 =.% 1=.4

    Saturation pressure #atm&0 < 3.1(3 3.2 3.(43 3.3=/

    . =.2 4. (%./

    3.2 3.1 3. (.

    1%= 1%33 1/3/ 1(/

    1%33 1/3/ 1(/ 2%4%

    3 3 3 3

    (.34= (.(3% (.(2 (.(//

    ./( 1.142 2.213 (.32

    3.((2 3.(/ 3.22 3.4%

    (.(4% (.34= (.(3% (.(2

    4= 43.2 .4 =.%

    eat transfer area #m2&0 +

    !verall heat transfer coef. #W5m2oC&0 9

    ,i'uid flow rate at the inlet #7)5s&0 mi

    Solids content at the inlet0 ;i

    ,i'uid temperature at the inlet #oC&0 Ti

    $oilin) temperature #oC&0 Tb

    Saturation temperature #oC&0 Tv

    Temperature drop #oC&0 D

    $oilin)

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    CO&(%&S%)

    eat transf. area (=3

    !veral heat transf. coef. 2=33

    Coolin) water flow rate in (4.2 7)5s

    Coolin) water temper. in 2=

    Water vapour temper. in 1=.4

    Coolin) water temp. out 2%.4

    Condensation temperat. 1=.4

    Water vapour pressure 3.3=/ atm

    m2

    W5m2oC

    oC

    oC

    oC

    oC

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    +ackward-Feed 4-%ffect %vaporator

    Control panel

    [email protected] (

    F&S'%(

    3.333

    nput data

    23333 7)5h

    %A

    /A

    3

    23

    3

    =3

    2=

    Control variables

    4=

    223333 7)5h

    )esults

    14= 7)5h

    /.(A

    124 7)5h

    Steam economy 1./ 7)57)

    223333 7)5h

    *eed flow rate0 [email protected]

    *eed solids content0 ;[email protected]

    8esired product solids content0 Bspec

    @

    *eed temperature0 [email protected] oC

    Temperature of the environment0 [email protected] oC

    !verall eat transfer coeffic. for heat losses0 9los

    @ W5m2oC

    !utside +rea of each effect of the evaporator0 +o,@ m2

    Coolin) water temper. at the inlet of the cond.0 [email protected] oC

    Steam temperature0 [email protected] oC

    ass flow rate of coolin) water in the conden.0mWin

    @

    Concentrated product flow rate0 [email protected]

    Solids content at the outlet0 ;[email protected]

    Steam consumption0 [email protected]

    Coolin) water flow rate0 mWin

    @

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    1st %FF%CT 2nd %FF%CT 3rd %FF%CT 4t# %FF%CT

    243 243 243 243

    (2( (33 (243 (3

    2.232 1.1(2 .1=3 =.==

    3.224 3.(=( 3.((= 3.3%3

    =4.4 %. 3.= 3.3

    .= =4.4 %. 3.=

    .% =4.2 %.1 3.1

    Saturation pressure #atm&0 < 3.2 3.(41 3.((/ 3.34

    /.= 4.2 4.4 /./

    (. 3. 3.1 3.2

    1(( 1/3( 1/%2 1%=

    2%4 1(( 1/3( 1/%2

    3 3 3 3

    (.(2 (.((3 (.314 (.23

    (.33 2.232 1.1(2 .1=3

    3./( 3.224 3.(=( 3.((=

    (.232 (.(2 (.((3 (.314

    4= .% =4.2 %.1

    eat transfer area #m2&0 +

    !verall heat transfer coef. #W5m2oC&0 9

    ,i'uid flow rate at the inlet #7)5s&0 mi

    Solids content at the inlet0 ;i

    ,i'uid temperature at the inlet #oC&0 Ti

    $oilin) temperature #oC&0 Tb

    Saturation temperature #oC&0 Tv

    Temperature drop #oC&0 D

    $oilin)

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    CO&(%&S%)

    eat transf. area (=3

    !veral heat transf. coef. 2=33

    Coolin) water flow rate in (.( 7)5s

    Coolin) water temper. in 2=

    Water vapour temper. in 3.1

    Coolin) water temp. out 1.

    Condensation temperat. 3.2

    Water vapour pressure 3.34 atm

    m2

    W5m2oC

    oC

    oC

    oC

    oC

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