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United Arab Emirates University College Of Engineering Chemical Engineering Department Graduation Project I. The Design of Formaldehyde Production Plant. Group Members: Abrar Abdalla Ahmed 200002089 Ayisha AL-Marzouqi 200002243 Huda Tag Hamza 200004386

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United Arab Emirates University College Of Engineering Chemical Engineering Department Graduation Project I

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United Arab Emirates UniversityCollege Of EngineeringChemical Engineering DepartmentGraduation Project I

The Design of

Formaldehyde Production Plant

  • Group Members:

    • Abrar Abdalla Ahmed 200002089

    • Ayisha AL-Marzouqi 200002243

    • Huda Tag Hamza 200004386

    • Noora Al-Mulla200002122

  • Supervisors:

  • Advisor: Dr. Mohammed Nounou


Objectives

  • First formaldehyde plant in UAE.

  • Economical, Environmental & safety.


Presentation layout

1- Formaldehyde background.

2- Process selection.

3- The description of the silver catalyst

process.

5- Material and energy balances calculations.

6- Safety and environmental impact.

7- Preliminary cost estimation.


Formaldehyde background

1- Definition.

2- History .

3- Physical and chemical characteristics.

4- Availability and market.

5- Uses and applications.


Definition

Simplest form of aldehyde

Chemical formula

HCHO


History

USA

Butlreov

1859

1901


Availability and market

Japan

Canada

America


Availability and market

Gulf region

Saudi Arabia


Uses and applications


Formaldehyde Production Process

1- Oxidation of dimethyl ether

2- Partial oxidation of methane

3- Dehydrogenation and/or Oxidation of methanol


Dehydrogenation and/or oxidation

of methanol

Methanol processes

Silver catalyst

75 %

Metal Oxide

catalyst

25 %


Process selection


N

.

.

7

6

5

4

3

2

1

88oC

35oC

Tail gas

water

Water

145 oC

Converter

Distillation Column

Cooling Water

Absorber

Air washer

88oC

145 oC

Air

110 oC

160oC

Methanol superheater

64.7oC

35oC

Methanol vaporizer

37% CH2O1% CH3OH

Fresh methanol

Recycled methanol


Water steam

145 oC

145 oC

Air fed

Methanol superheater

160 oC

64.7oC

Methanol vaporizer

Fresh methanol

Recycled methanol


Tail gas

Water

Recycled methanol

Reactor effluent

Product


(Material balance)Objective

  • Amount of raw materials

  • Compositions & flow rates


Degree of freedom

Ndf = Nunknowns – Nindependent equations

Nunknowns= 12

Msteam

MH2O

MTail gas

Mmethanol

Mair

Compositions in tail gas:

HCHO, CO2, CO,

H2, H2O, C2H4O2,

N2

Msteam

MH2O

MTail gas

Mair

Nindependent equations= 4

Mmethanol

Mproduct

atomic balance equations (H, N, C, O).


Degree of freedom

Ndf = 12 – 12 = 0

Ndf = 12 – 4 = 8

20% Tail gas = H2

0.1%Tail gas = C2H4O2

EPA:

- HCHO

- CO2

- CO

Yield = 0.92

Ratio of air to methanol

30% of the feed entering the reactor is steam


Recycled methanol : Fresh methanol

1:3

(Air : Methanol) fed to the reactor

0.9:1

Assumptions and specifications

30% of the reactor feed is steam

Plant yield = 92%


N

.

.

7

6

5

4

3

2

1

Distillation Column

Top product

Basis

Product = 5,707,762 kg/hr

From absorber

Bottom product


N

.

.

7

6

5

4

3

2

1

Fresh methanol

= 2,448,547 Kg/hr

88oC

35oC

Tail gas

Yield =92%

water

Water

145 oC

Converter

Distillation Column

Cooling Water

Absorber

Air washer

88oC

145 oC

Air

110 oC

160oC

Methanol superheater

64.7oC

35oC

Methanol vaporizer

37% CH2O1% CH3OH

Fresh methanol

Recycled methanol


N

.

.

7

6

5

4

3

2

1

Recycled stream /Fresh methanol

= 1 / 3

Recycled stream

=812,611 Kg/hr

88oC

35oC

Tail gas

water

Water

145 oC

Converter

Distillation Column

Cooling Water

Absorber

Air washer

88oC

145 oC

Air

110 oC

160oC

Methanol superheater

64.7oC

35oC

Fresh methanol

Methanol vaporizer

37% CH2O1% CH3OH

Recycled methanol


Air fed

=2,656,138 Kg/hr

Air / Methanol

= 0.9/1

Water

145 oC

Cooling Water

Air washer

145 oC

Air

160oC

Methanol superheater

64.7oC

Fresh methanol

Methanol vaporizer

Recycled methanol


30% of reactor feed

is steam

Water steam

=2,529,704 kg/hr

Reactor feed

=8,432,346 kg/hr

Mixing point

Mass in = Mass out

Water steam

145 oC

Cooling Water

Air washer

145 oC

Air

160oC

Methanol superheater

64.7oC

Fresh methanol

Methanol vaporizer

Reactor effluent

=8,432,346 kg/hr

Recycled methanol


N

.

.

7

6

5

4

3

2

1

Distillation Column

Recycled stream

Top Product = 812,611 kg/hr

Feed = 6,520,374 kg/hr

88oC

Product = 5,707,762 kg/hr

35oC

37% CH2O1% CH3OH


N

.

.

7

6

5

4

3

2

1

Tail gas

=100,409 kmol/hr

Tail gas

water

Overall carbon atomic balance

Water steam

145 oC

Converter

Distillation Column

Cooling Water

Absorber

88oC

145 oC

Air

110 oC

160oC

Methanol superheater

64.7oC

Product

Methanol vaporizer

Fresh methanol

Recycled methanol


N

.

.

7

6

5

4

3

2

1

Neglect (H2O) in tail gas

MWav.= 22.8 Kg/Kmol

N2 = 0.72

Tail gas

water

Tail gas

=2,249,102 kg/hr

Water steam

145 oC

Converter

Distillation Column

Cooling Water

Absorber

88oC

145 oC

Overall Nitrogen balance

Air

110 oC

160oC

Methanol superheater

64.7oC

Product

Methanol vaporizer

Fresh methanol

Recycled methanol


N

.

.

7

6

5

4

3

2

1

XN2=0.75

XH2O=0.009

Water

=337,129 kg/hr

Tail gas

water

Water steam

145 oC

Converter

Distillation Column

Cooling Water

Absorber

88oC

Overall hydrogen atomic balance

Overall mass balance

145 oC

Air

110 oC

160oC

Methanol superheater

64.7oC

Product

Methanol vaporizer

Fresh methanol

Recycled methanol


(Energy balance)Objectives

  • Amount of energy power requirements


Hv

,TD , m

Qc

HL

HD

,TD

QB

Hw

Energy balanceDistillation Column

TD= 64.85oC

HD

HD = 0 kJ/hr

Hf

Tw= 91.5 oC

Hw = Hf - HD

Hw = Hf = 5.7*108 kJ/hr

Hw = mw Cpw (Tw-Tref)

Hw


Reboiler & condenser duties

Condenser duty:

Qc = Hv = 2.7*109 kJ/hr

mH2O = 3.2*107 kg/hr

HD

Reboiler duty:

Qrb = Qc + Hw +HD - Hf

Qrb = 2.7*109 kJ/hr

mH2O = 1.2*106 kg/hr

Hf

Hw


Cooler

1- Amount of cooling water

mw Cpw (Tw – 35) = mH2O CpH2O (Tout – Tin)

HD

mH2O = 6.77*106 kg/hr

Hf

Hw

35oC

91.5oC


Energy balanceAbsorber

88 oC

35 oC

Qrb =H15- HH2O - Hf

Water

, TH2O = 20 oC

Qrb =6.56*108 kJ/hr

Hf

Qc = HH2O + Qrb +Hf – H15 – Hw

TR = 110 oC

Qc = 1.61*108 kJ/hr

Hw


Methanol vaporizer & superheaterduties

Q1+QR = mm Cpm (Tm-Tref)

Tm = 56 oC

QA

QA = msteamH2O = mair CpairT

QA=5*107 kJ/hr

msteam=2.21*104

Qv =mm + mm cpm T

= 3.64*109 kJ/hr

msteam= 1.61E+06 kg/hr

Qs

Qv

Q1

Qs= msteamH2O = mm CpmT

= 5*107 kJ/hr

msteam= 1.67E+06 kg/hr

T 1 = 30oC

T m

, QR

T R = 64.85oC


Energy balanceReactor

145 oC

HR = -2.1*108 kJ/hr

mH2O = 9.26*107 kg/hr

Cooling water

Qc = 1.6*109 kJ/hr

Qc

110 oC

160 oC

mH2O = 1.9*107 kJ/hr


Where does formaldehyde exist?


Sources of exposure

Tobacco smoke

Oil refineries

Engine exhaust


Limits of exposure

  • Acute duration (0.04 ppm)

  • Intermediate duration (0.03 ppm)

  • Chronic duration (0.008 ppm)


Environmental Impact

Formaldehyde in nature

Air

Soil

Water


Plant Capital Cost

Capital cost definition

Step counting method

C' = 13000 N Q0.615

Timm’s Correlation

N: 3

Q: 50,000,000 tonne/ year

C' = 2.12E+09 $

Cost in year 2004 =2.5E+09 $


Conclusion

  • Tasks achieved

  • Plan for next semester


References

1- Robert H. Perry, Don W. Green, Perry Chemical Engineer’s Handbook, seventh edition, McGRAW international, 2003.

2- K.Weissermel, H.-J.Arpe, Industrial Organic Chemistry, Third compeletely revised edition, VCH A wiley company, 1997.

3- R. Norrris shereve, Chemical process industries, fourth edition, McGRAW Hill book company,1977.

4- Kirk-othmer, Encyclopedia of chemical technology, fourth edition, volume 11, A wiley interscience publication, New York, 1992.

5- Sybil P. Parker, Encyclopedia of chemistry, second edition, McGRAW Hill book company, 1993, pages 408-410, 637-638.

6- Douglas M. Considine, Chemical and process technology encyclopedia, McGRAW Hill book company, 1974.


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