incineration exercise

7/25/2019 Incineration Exercise

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Incineration Exercise


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Objectives

Compute the composition of uegas

Compute the temperature of uegas (a function of waste heat valueand composition)

Compute the amount of airrequired


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tep !" #aste

Composition$etermine the chemical

composition (lb)% water content

(lb)% and energ& content


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Step 1: Calculate chemical composition, water content, and energy content.

Component Composition Moisture Energy Dry --------------- Chemical Composition (dry basis -------------- Energy

(lb Content Content !eight Carbon "ydrogen #$ygen %itrogen Sul&ur 'sh (tu

(lb) lb (tu) lb (lb

*ood !aste + . 1.+/ .10 1.1 . .11 .10 12,

3aper 04 / 0. 10.+0 1.+12 14./ .+/ ./4 1.+12 44,2

Cardboard / . .2 .00/ .4 .1 .11 .2 4,3lastics 14 /.+ 4.11/ .4+4 1./4 . . ./2/ +2,

5e$tiles 1 1.2 .++ .11+ ./ .20 .0 .4 1,

6ubber . 1 . .02 .4+ . .1 . .4+ ,

7eather . 1 . . .0/ . .4 . .4 0,

8ard !astes 12. / 2 .4 0.0 .444 .21 . . .000 1,2

!ood 2 1./ .+ .+/ ./20 .0 . .4 1/,

9lass 2 / .2 .0+ .2 .01 .2 . .4 42

5in Cans / 0 0 .2 ./ .0 . ./ . ./ 1,2

'lumiinum . . . .0 .1 . . .440

#ther Metal 0 0 0 .+ .101 .1 .1 .0 . ./04 +

Dirt, ash, etc 0 2 0 .2 ./ .20 . .14 ./ 1.2 +,

sum: 1 2.2 2.+ 0.21 0.2 ./1 .1 1.4+ /,0

!ater content: 1. lb

Energy content /.0 tu)lb


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tep ' and " $etermine

the moles of Ox&genrequiredtep '" convert chemical

composition and water content

from lb to lbmole using molecularweights

tep " $etermine the moles of

ox&gen required to combust thesample completel&


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C---;C#

4"---;"

---;%---;%

S---;S#Note: oxygen in the waste mass is released during thecombustion process and decreases the oxygen required

for stoichiometric combustion


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Step and 0:

Component !eight Molecular Moles Moles

(lb !eight (lbd

Carbon 2.+ 1 C---;C#"ydrogen 0.21 1 4"---;"

#$ygen 0.2 1/ # --;#

%itrogen ./1 14 %---;%

Sul&ur .1 0.1 S---;S#

!ater 1. 12?nerts ('sh 1.4+ n)a

1.

#$ygen &or combustion o& 1 lb o& MS! lb


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Step and 0:

Component !eight Molecular Moles Moles

(lb !eight (lbd

Carbon 2.+ 1 .414 .414 C---;C#"ydrogen 0.21 1 0.21 .+ 4"---;"

#$ygen 0.2 1/ 1.42/ -.40 # --;#

%itrogen ./1 14 .40 %---;%

Sul&ur .1 0.1 .4 .4 S---;S#

!ater 1. 12 1.1+

?nerts ('sh 1.4+ n)a 1.

#$ygen &or combustion o& 1 lb o& MS! ./0 lb


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tep *" Composition of

+lue ,asCalculate the composition of gas

produced b& combustion of waste

-e sure to add the water content inthe waste sample to the waterproduced b& combustion


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Step 4

Component Moles Combustion Combustion

(lb


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tep ." Calculate the /ir

0equirementsCalculate the air suppl& required to

provide the ox&gen needed for

stoichiometric combustion1oles of air required 2

0equired O'suppl&3O'mole

fraction


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4&pical /ir Composition

(mole fractions)

Component mole fractionCO2 0.0003

N2 0.!02

O2 0.20"#$2O 0.0%2"

&ir Composition


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Moles o& 'ir re=uired per 1-- lb o& waste lb


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'oles of air ( 2."3)0.20"#

( %2. lb*moles

tep .


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tep 5" Composition of /ir

uppliedCalculate the moles of each gas

component supplied in air using

the air composition provided intep .


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Step /: Composition o& supplied air

Component 'ir supply(lb


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Step /: Composition o& supplied air

Component 'ir supply(lb


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tep 6" $etermine the

Composition of +lue ,astoichiometric (78 excess air) gas

composition

/dd tep * results to tep 5 results

Calculate in both moles andpercent

um moles to calculate total molesgas production


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Step : *lue gas composition

Combusti --------- Moles o& *lue 9as ---------

3roduct Combustion 'ir Supply 5otal 3ercent3roduct 9as

C#

"

#

%

S#

. 1. 1./ 1.


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Step : *lue gas composition

Combustion --------- Moles o& *lue 9as ---------

3roduct Combustion 'ir Supply 5otal 3ercent

3roduct 9as

C# .41 . .4 1.

" 0.2 .1/ 0.4 .2

# . . . .

% . +.+1 +.+0 /0./S# . . . .

. 1. 1./ 1.


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tep 9" Calculate the +lue

,as Enthalp&-4:3lbmole is a function of temperature

and compound% this function is complex%

nonlinear#e will calculate the enthalp& of the ue

gas at various temperatures (!777% !.77%'777% '.77o+) using enthalp& data for

individual gases and ue gas composition4otal -4:3lbmole is a weighted average

of all gases present


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0equired Enthalp& $ata

5emp C# " # %

1 142 /+ /+4 /

1 1/14 0140 112 1/

1+ 0/+0 11+1 14

+0+ 44 1+1 12/+


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Step 2: Calculate &lue gas enthalpy

5emp, * tu)lb


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Step 2: Calculate &lue gas enthalpy

5emp, * tu)lb


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tep ;" Convert Enthalp&

in ,as to

moles of ue gas (from tep 6)3(!77 lb of waste)


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Step +: Con@ert enthalpy &rom tu)lb


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Step +: Con@ert enthalpy &rom tu)lb


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tep !7" +lue ,as

4emperature$etermination based on

conservation of energ& (Energ& In

2 Energ& Out ?osses)@nowing energ& is transferred from

waste to gas we can interpolate

from tep ; the temperaturecorresponding to the heat value ofthe waste


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tep !7" Continued

Calculate the temperature of the uegas assuming no losses b& using the

energ& content of the waste tointerpolate between temperaturesusing information calculated in tep ;

Calculate temperature of the ue gasassuming an eAcienc& of combustion


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Step 1:

Case ': %o losses

Energy in &lue gas /.0 tu)lb

5emperature *

Case : A losses

E&&iciency 2 A

Energy in &lue gas 4. tu)lb5emperature *


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Step 1-:

Case ': %o losses

Energy in &lue gas -/ tu)lb

5emperature 0 *

Case : -A losses

E&&iciency 2- A

Energy in &lue gas 4- tu)lb

5emperature / *


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Excess /ir Calculation

Combustion is generall& not donewithout excess airB Excess air is

supplied to control temperatureand increase mixing to ensurecomplete combustion


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Excess /ir Calculations

tep !!/$etermine how man& moles of air

will be added"

(8E/3!77)>(moles reqd for 78 E/(tep .))


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tep !!/ '.8 Excess /ir

%2. lb moles + 2,)%00 ( 3.%! lb moles


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Excess /ir Calculations

tep !!-$etermine composition (lb mole) of

extra air supplied using air

composition tep ./dd gas components from tep -

to gas components (lb moles) fromtep 6 for 78 excess air

um moles and convert topercentage composition


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tep !!- '.8 Excess /ir

Combustio ase &lue gas E$cess 5otal

3roduct &rom -A E' 'ir 3ercent

lb


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Combustion ase &lue gas E$cess 5otal

3roduct &rom A E' 'ir 3ercent

lb


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Excess /ir Calculation

tep !!C0epeat teps 9 through !7

In tep ;% use the moles of gas

calculated in tep !!-


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5emp, * tu)lb


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5emp, * tu)lb


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5emp, * tu)lb waste

1---

1--

---

--


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5emp, * tu)lb waste

1

1 21

0//0

44


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Case ': %o losses

Energy in &lue gas /.0 tu)lb

5emperature *Case : A loss

E&&iciency 2 A

Energy in &lue gas 4. tu)lb

5emperature *


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Case ': %o losses

Energy in &lue gas / tu)lb

5emperature + *

Case : A loss

E&&iciency 2 A

Energy in &lue gas 4 tu)lb

5emperature 0 *


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0epeat for .78% 6.8% and

!778 Excess /ir

50 % Excess Air


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E$tra air supplied: /.0 lb


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E$tra air supplied: +.0 lb


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100 % Excess Air

E$tra air supplied: 1.- lb

incineration exercise

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