iii

MANUFACTURE OF FORMALDEHYDE

FROM METHANOL

A PROJECT REPORT

Submitted by

S. GAYATHRI (41501203005)

G. MUTHAMILARASI (41501203014)

in partial fulfillment for the award of the degree

of

BACHELOR OF TECHNOLOGY

in

CHEMICAL ENGINEERING

S.R.M. ENGINEERING COLLEGE, KATTANKULATHUR-603 203, KANCHEEPURAM DISTRICT.

ANNA UNIVERSITY : CHENNAI - 600 025

MAY 2005

iv

BONAFIDE CERTIFICATE Certified that this project report "MANUFACTURE OF FORMALDEHYDE FROM

METHANOL" is the bonafide work of "S. GAYATHRI (41501203005) and G.

MUTHAMILARASI (41501203014)" who carried out the project work under my

supervision.

Prof. Dr. R. KARTHIKEYAN Prof. Dr. R. KARTHIKEYAN

HEAD OF THE DEPARTMENT SUPERVISOR

CHEMICAL ENGINEERING PROFESSOR & HEAD

S.R.M.Engineering College CHEMICAL ENGINEERING

Kattankulathur - 603 203 S.R.M.Engineering College

Kancheepuram District Kattankulathur - 603 203

Kancheepuram District

v

ACKNOWLEDGEMENT

Our heart felt thanks to the Director, Dr.T.P.Ganesan, and our Principal, Prof.

R.Venkatramani,M.Tech,F.I.E, for allowing us to carryout our project.

We express our profound gratitude to Dr.R.Karthikeyan, Head of the

Department, Chemical engineering, who guided us in the right direction through the

course of our project.

We also thank our project co-ordinater Mrs.K.Kasturi,B.Tech, for her valuable

advice and encouragement.

Our special thanks to the members of the DTP section and library for their co-

operation

vi

ABSTRACT

Formaldehyde, one of the important industrial chemicals, finds its applications

in polymeric resins like phenol formaldehyde, adhesives, alkali resins for paints and

coatings etc…Manufacture of formaldehyde (as formalin) is done by oxidation of

methanol, mainly by metal oxide process involving Fe/Mo catalyst with 95-99mol%

conversion of methanol. This project is aimed at designing plant producing 37 wt%

formalin and checking for feasibility of production.

vii

TABLE OF CONTENTS CHAPTERS TITLE PAGE NO

ABSTRACT iv

LIST OF TABLES

vii

LIST OF FIGURES

viii

LIST OF SYMBOLS

ix

1

INTRODUCTION

1

2

PROPERTIES

2.1 PHYSICAL PROPERTIES 2.2 THERMAL PROPERTIES

2.3 CHEMICAL PROPERTIES

3 3 3 4

3

ANALYSIS AND SPECIFICATIONS

7

4

COMMERCIAL USES OF FORMALIN

8

5

LITERATURE REVIEW

5.1 SELECTION OF PROCESS

10 11

6

PROCESS DESCRIPTION

6.1 FLOW SHEET

12 14

7

MATERIAL BALANCE

15

8

ENERGY BALANCE

19

9

DESIGN

23

10

PLANT LAYOUT 29

11 MATERIALS OF CONSTRUCTION 11.1 METALS 11.2 NON-METALS

39 39 40

12

INSTRUMENTATION AND CONTROL

41

viii

13 STORAGE AND TRANSPORTATION 46 14

HEALTH AND SAFETY CONSIDERATIONS

47

15

COST ESTIMATION

49

16

CONCLUSION

56

REFERENCES

57

LIST OF TABLES

Table Number

Description Page No

1

Heat transfer data

19

2 Storage temperatures 46

3 Dose-response relationship 47

4 Delivered cost of equipments 49

5 Direct cost factor 50

6 Indirect cost factor 50

7 Auxillary cost factor 52

ix

LIST OF FIGURES

Page No FIGURE 6.1

FLOW SHEET

14

FIGURE 7.1

REACTOR BALANCE

17

FIGURE 7.2

ABSORBER BALANCE

18

FIGURE 8.1

ENERGY BALANCE FOR METHANOL VAPORIZER

19

FIGURE 8.2

ENERGY BALANCE FOR REACTOR

20

FIGURE 8.3

ENERGY BALANCE FOR HEAT EXCHANGER 1

21

FIGURE 8.4

ENERGY BALANCE FOR HEAT EXCHANGER 2

21

FIGURE 8.5

ENERGY BALANCE FOR ABSORBER(BOTTOM)

21

FIGURE 8.6

ENERGY BALANCE FOR ABSORBER (TOP)

22

FIGURE 10.1

PLANT LAYOUT

38

x

LIST OF SYMBOLS

A Area (m2)

D,d Diameter (m)

L Length (m)

m Mass (Kg)

Nu Nusselt number

n Number of tubes

P Pressure (atm)

Pr Prandtl number

Re Reynolds number

V Volume(m3)

T Temperature(K)

U Overall heat transfer

coefficient(W/ m2.oC)

Z Height (m)

GREEK LETTERS ∆T Temperature difference (oC)

∆TL Logarithmic mean temperature difference (oC) µL

Viscosity of liquid

ρ

Density (Kg/m3)

11

1. INTRODUCTION

Formaldehyde occurs in nature and it is formed from organic material by

photochemical processes in the atmosphere. Formaldehyde is an important metabolic

product in plants and animals (including humans), where it occurs in low but

measurable concentrations. It has a pungent odour and is an irritant to the eye, nose

and throat even at low concentrations.

However, Formaldehyde does not cause any chronic damage to human health.

Formaldehyde is also formed when organic material is incompletely combusted.

Formaldehyde is an important industrial chemical and is employed in the manufacture

of many industrial products and consumer articles.

Formaldehyde was first synthesized in 1859, when BUTLEROV hydrolyzed

methylene acetate and noted the characteristic odour of the resulting solution. In

1867,HOFMANN conclusively identified formaldehyde, which he prepared by

passing methanol vapour and air over a heated platinum spiral. This method, but with

other catalyst, still constitutes the principal method of manufacture.

Industrial production of formaldehyde became possible in 1882,when

TOLLENS discovered a method of regulating the methanol vapour: air ratio and

affecting the yield of the reaction. In 1886 LOEW replaced the platinum spiral

catalyst by more efficient copper gauze. A German firm, Hugo Blank, patented the

first use of a silver catalyst in 1910.In 1905,Badische Anilin and Soda-Fabrik started

to manufacture formaldehyde by a continous process employing a crystalline catalyst.

Formaldehyde output was 30 kg/day in the form of an aqueous 30 wt% solution. The

methanol required for the production of formaldehyde was initially obtained from the

timber industry by carbonizing wood. The development of high-pressure synthesis of

methanol by Badische Anilin and Soda-Fabrik in 1925 allowed the production of

formaldehyde on a true industrial scale

12

2. PROPERTIES

2.1 PHYSICAL PROPERTIES

Formaldehyde is a colorless gas at ambient temperature that has a pungent,

suffocating odor. At ordinary temperatures formaldehyde gas is readily soluble in

water, alcohols and other polar solvents. It has following physical properties:

Boiling point at 101.3 kPa = -19.2oC

Melting point = -118oC

Density at –80oC = 0.9151g/cm3

At –20oC = 0 .8153 g/cm3

Vapor density relative to air = 1.04

Critical temperature = 137.2 – 141.2 (oC)

Critical pressure = 6.784 – 6.637 Mpa

Cubic expansion coefficient = 2.83 x 10–3 K-1

2.2 THERMAL PROPERTIES

Heat of formation at 25oC = -115.9 + 6.3 kJ/mol

Heat of combustion at 25oC = 561.5 kJ/mol

Heat of vapourisation at –19.2oC = 23.32 kJ/mol

Specific heat capacity at 25oC = 35.425 J/mol K

Heat of solution at 23oC

In water = 62 kJ/mol

In methanol= 62.8 kJ/mol

In 1-propanal = 59.5 kJ/mol

In 1-butanol = 62.4 kJ/mol

Entropy at 25oC= 218.8 + 0.4 kJ/mol K

2.3 CHEMICAL PROPERTIES

Formaldehyde is one of the most reactive organic compounds known. The

various chemical properties are as follows:

Decomposition

At 150oC formaldehyde undergoes heterogeneous decomposition to form

methanol and CO2 mainly. Above 350oC it tends to decompose in to CO and H2.

13

Polymerization

Gaseous formaldehyde polymerizes slowly at temperatures below 100oC,

polymerization accelerated by traces of polar impurities such as acids, alkalis or

water. In water solution formaldehyde hydrates to methylene glycol

H

H2C=O + H2O HO C OH

H

Which in turn polymerizes to polymethylene glycols, HO (CH2O)nH, also

called polyoxy methylenes.

Reduction and Oxidation

Formaldehyde is readily reduced to methanol with hydrogen over many metal

and metal oxide catalysts. It is oxidized to formic acid or CO2 and H2O.

In the presence of strong alkalis or when heated in the presence of acids

formaldehyde undergoes cannizzaro reaction with formation of methanol and formic

acid. In presence of aluminum or magnesium methylate, paraformaldehyde reacts to

form methyl formate (Tishchenko reaction)

2HCHO HCOOCH3

Addition reactions

The formation of sparingly water-soluble formaldehyde bisulphite is an

important addition reaction. Hydrocyanic acid reacts with formaldehyde to give

glyconitrile.

HCHO + HCN HOCH2 - C ≡ N

Formaldehyde undergoes acid catalyzed Prins reaction in which it forms α-Hydroxy-

methylated adducts with olefins. Acetylene undergoes a Reppe addition reaction with

formaldehyde to form 2- butyne-1,4- diol.

14

2 HCHO + HC ≡CH HOCH2≡CCH2OH

Strong alkalis or calcium hydroxide convert formaldehyde to a mixture of sugars in

particular hexoses, by a multiple aldol condensation, which probably involves a

glycolaldehyde intermediate. Acetaldehyde, for example reacts with formaldehyde to

give pentaerythritol, C (CH2OH)4

Condensation reactions

Important condensation reactions are the reaction of formaldehyde with amino

groups to give schiff’s bases, as well as the Mannich reaction.

CH3COCH3 + (CH3) 2NH.HCl + HCHO

CH3COCH2CH2N(CH3) 2.HCl + H2O

Formaldehyde reacts with ammonia to give hexamethylene teteramine and

with ammonium chloride to give monomethylamine, dimethylamine, or

trimethylamine and formic acid, depending upon reaction conditions.

Aromatic compounds such as benzene, aniline, and toluidine combine with

formaldehyde to produce the corresponding diphenyl methanes. In the presence of

hydrochloric acid and formaldehyde, benzene is chloromethylated to form benzyl

chloride. Formaldehyde reacts with hydroxylamine, hydrazines, or semicardazide to

produce formaldehyde oxime, the corresponding hydrazones, and semicarbazone,

respectively.

Resin formation

Formaldehyde condenses with urea, melamine, urethanes, cyanamide,

aromatic sulfonamides and amines, and phenols to give wide range of resins.

15

3. ANALYSIS AND SPECIFICATIONS

Qualitative Methods:

Qualitative detection of formaldehyde is primarily by colorimetric methods.

Schiff’s fuchsin-bisulfite reagent is the general reagent used for detecting aldehydes.

In the presence of strong acids, it reacts with formaldehyde to form a specific bluish

violet dye.

Quantitative Methods:

Physical Methods: Quantitative determination of pure aqueous solutions of

formaldehyde can be carried out rapidly by measuring their specific gravity. Gas

chromatography and high-pressure liquid chromatography can also be used for direct

determination.

Chemical Methods:

The most important chemical method for determining formaldehyde is the

sodium sulfite method. It is based on the quantitative liberation of sodium hydroxide

when formaldehyde reacts with excess sodium sulfite.

CH2O + Na2SO3 + H2O HOCH2SO3Na + NaOH

The stoichiometrically formed sodium hydroxide is determined by titration

with an acid.

Formaldehyde in air can be determined with the aid of gas sampling apparatus.

In this procedure formaldehyde is absorbed from a definite volume of air by a wash

liquid and is determined quantitatively by a suitable method like pararosanline

method.

Formaldehyde is sold in aqueous solutions with concentrations ranging from

25 – 56 wt% HCHO. Formaldehyde is sold as low methanol (uninhibited) and high

methanol (inhibited) grades. Formaldehyde solutions contain 0.5-12 wt% methanol or

other added stabilizers. They have a pH of 2.5 –3.5,the acid reaction being due to the

presence of formic acid.

4. COMMERCIAL USES OF FORMALDEHYDE

Formaldehyde resins are one of the major applications of formaldehyde. Some

of the derivatives are given below.

Urea-formaldehyde resins are produced by the controlled reaction of urea and

formaldehyde. Their major uses are as adhesives for particleboard, fiberboard and

16

plywood. They are also used for compression molded plastic parts, as wet-strength

additives for paper treating, and as bonders for glass fiber roofing materials.

Phenol formaldehyde is produced by the condensation of phenol with

formaldehyde. The use of these resins is as an adhesive in waterproof plywood. These

resins are also used for binding glass fiber insulation.

Acetylenic chemical uses of formaldehyde involve the reaction with acetylene

to form butynediol, which in turn can be converted to butanediol, butyrolactone and

pyrrolidones. Their major applications are as specialty solvent and extractive

distillation agents.

Polyacetyl resins are produced from the anionic polymerization of

formaldehyde. These resins are used in plumbing materials and automobile

components.

Pentaerythritol is formed by the reaction of formaldehyde, acetaldehyde and

sodium hydroxide. Its largest use is in the manufacture of alkyd resins for paints and

other protective coatings.

Hexamethylene tetramine is formed by the reaction between formaldehyde

and ammonia. It is used as a partial replacement for phosphates as a detergent builder

and as a chelating agent.

Urea-formaldehyde concentrates are used as controlled release nitrogen

fertilizers.

Melamine resins are thermosetting resins produced from melamine and

formaldehyde and are primarily used for surface coatings.

The direct use of formaldehyde is to impart wrinkle resistance in fabrics.

17

5. LITERATURE SURVEY

Most of the world’s commercial formaldehyde is manufactured from methanol

and air either by a process using a silver catalyst or one using a metal oxide catalyst.

SILVER CATALYST PROCESS

The silver catalyst processes for converting methanol to formaldehyde are

generally carried out at an atmospheric pressure and at 600 – 720°C .The reaction

temperature depends on the excess of methanol in the methanol-air mixture. The

composition of mixture must lie outside the explosive limits. The amount of air used

is also determined by the catalytic quality of the silver surface. The following

reactions take place

CH3OH + ½ O2 HCHO + H2O

CH3OH HCHO + H2

Methanol conversion is 65 – 75% per pass.

METAL OXIDE PROCESS

In this process formaldehyde is formed by oxidation process only. The

reactions are

CH3OH + ½ O2 HCHO + H2O

HCHO + ½ O2 CO + H2O

The reactions occur over a mixed oxide catalyst containing molybdenum oxide

and iron oxide in a ratio 1.5 to 3.The reaction is carried out at 250 –350 oC and

essentially at atmospheric pressure. Methanol conversion is 95 – 98% per pass.

5.1 SELECTION OF PROCESS

It is estimated that nearly 70% of commercial formaldehyde is produced by

metal oxide process. This process has a very low reaction temperature, which permits

high catalyst selectivity, and the very simple method of steam generation. The

conversion is around 95-98% per pass, which is greater than silver oxide process.

18

6. PROCESS DESCRIPTION

Metal oxide process: Vaporized methanol is mixed with air and optionally recycled

tail gas is passed through catalyst filled tubes in a heat exchanger reactor. The

following reactions take place in the reactor.

CH3OH+ ½ O2 HCHO +H2O +37 Kcal/g-mol

HCHO + ½ O2 CO+H2O+51 Kcal/g-mol

The temperature inside the reactor is maintained at 250-350°C.

The heat released by the exothermic reaction is removed by vaporization of a

high boiling heat transfer fluid on outside of the tubes. Steam is normally produced by

condensing the heat transfer fluid. The catalyst is granular or spherical supported

Fe/Mo and has an effective life of 12 –18 months. A typical reactor has short tubes of

1-1.5m and a large shell diameter of 2.5 m or more. The exit gases from the reactor

pass through a heat exchanger where the temperature is reduced to 110oC and then to

the absorption column where water is used as the scrubbing medium.

The absorber can be either of packed or tray type. It is necessary to remove the

heat of solution plus the residual sensible heat of the feed gases, and this is done by

circulating down flow liquid through external heat exchangers and in some cases by

the use of cooling coils. The bottom stream from the absorber represents the final

product. Formaldehyde concentration in the product is adjusted by controlling the

amount of water added to the top of the absorber. Formic acid is removed by ion

exchange. A large portion of the absorber overhead gas is recycled back to the feed

system. The methanol conversion ranges from 95-99mol% and depends on the

selectivity, activity and spot temperature of the catalyst, the later being influenced by

the heat transfer rate. The overall plant yield of formaldehyde is 88-95 mol%.

19

The final product contains up to 55wt% formaldehyde and 0.5-1.5 wt%

methanol.

ABSORBER

R E A C T O R

WATER

CW

CW

DEIONISER

METHANOL

RECYCLE GAS

PURGE GAS

AIR

St

St

BLOWER

BFW

St

BFW

2

1 `

3 F ORMA L I N

1. METHANOL VAPORIZER 2. HEAT EXCHANGER 1 3. HEAT EXCHANGER 2

20

FIG 6.1 FLOW SHEET 7. MATERIAL BALANCE

Basis: 100 kmoles of methanol in fresh feed per hour

Molecular weight of methanol = 32 kg/kmole

Weight of methanol in feed = 3200 kg

CH3OH + ½ O2 HCHO + H2O

Assume methanol conversion is 97 %.

Hence methanol reacted = 97 kmoles

= 3104 kg

Assume that 1% of methanol reacts to form formic acid.

HCHO + ½ O2 CO + H2O

Actual O2 required = 51.925 kmoles = 1661.60 kg

Actual O2 supplied (250% excess) = 181.738 kmoles = 5815.62 kg

Excess O2 = 181.738 – 51.925

= 129.813 kmoles =4154.02 kg

Assume that 57% of oxygen requirement comes from recycle stream and 43% comes

from fresh feed.

O2 from fresh feed = 181.738 x 0.43

= 78.147 kmoles = 2500.70 kg

Corresponding N2= 78.147 x (79/21)

= 298.982 kmoles = 8371.50 kg

Assume that the percentage composition of recycle stream is

O2 - 7.78%

21

N2 - 88.3%

H2O - 3.89% O2 from recycle stream = 103.590 kmoles =3314.88 kg

N2 in recycle stream = 1175.910 kmoles =32925.48 kg

H20 in recycle stream = 51.795 kmoles =932.31 kg

Reactor outlet:

Unreacted methanol = 2 kmoles=64 kg

HCHO formed = 92.15 kmoles=2764.50 kg

H2O formed = 154.64 kmoles=2783.52 kg

CO formed = 4.85 kmoles= 135.8 kg

Nitrogen =1484.185 kmoles=41157.20 kg

Unreacted oxygen =129.813 kmoles =4154.02 kg

HCOOH formed = 1 kmole = 46 kg

FIG 7.1

REACTOR

Methanol =3200kg

O2= 3314.82 kg N2 = 32925.48 kg H20 = 932.31 kg

Air O2=2500.71kg N2 =8231.50 kg

CH3OH = 64 kg O2=4153.92 kg N2=41157.20kg H20 = 2783.4 kg

HCHO=2764.5 kg CO=135.8 kg HCOOH=46 kg

TOTAL INPUT =51104.82 kg TOTAL OUTPUT =51104.82 kg

22

ABSORBER

Gms (Ya-Yb) = Lms (Xa- Xb)

Gms =molar flow rate of gas on solute free basis

Lms =molar flow rate of liquid on solute free basis

Xa =% of solute in liquid at inlet

Xb =% of solute in liquid at outlet

Ya =fraction of solute in gas at inlet

Yb =fraction of solute in gas at outlet

Gas flow rate = Gms= 1653.645 kmoles/hr M= 0.0678 (VLE data) M= (Lms) min Gms (Lms) min = 112.117 kmoles Yb = 5/95 = 0.0526 Ya = 3.14 X10–4 Xa = 0 Xb =0.7758 Assume Lms = 1.4 (Lms) min Lms = 157.71 kmoles

23

FIG 7.2

8. ENERGY BALANCE DATA TABLE 1:

Latent heat of vaporization,λ (KJ/Kg)

Specific heat capacity Cp(KJ/Kg oC)

Methanol 1099.90 (at 64.7 oC) 2.513 O2 - 0.928 N2 - 1.04 H2O 2255(at 100 oC)

3278.20 (at 400 oC) 2228.69(at 110 oC)

1.88

CO - 1.13 HCOOH - 0.6 HCHO - 0.5 Oil - 1.75 1) Methanol vaporizer RECYCLE AIR (25oC) H20 (400 oC) O2 :3314.8 Kg N2: 32925 Kg H20:932.31 Kg CH3OH = 3200 Kg AIR(285 oC) METHANOL

CH3OH=64 kg HCOOH=46 kg

H20=1165.39 kg O2=4153.92 kg N2=41156.64 kg

PRODUCT STREAM HCHO=2764.5 kg H20=4593.02 kg

HCHO=2764.5 kg CO =135.8 kg HCOOH=46 kg

FROM REACTOR CH3OH = 64 kg O2=4153.92 kg N2=41157.20kg H20 = 2783.4 kg ABSORBER

SOLVENT H20=2838.78 kg

RECYCLE STREAM

TOTAL INPUT = 53943.46 kg TOTAL OUTPUT = 53943.46 kg

Methanol Vaporizer

24

FRESH AIR O2: 2500 Kg N2: 8231.5Kg (400 oC) SUPERHEATED STEAM

FIG 8.1

mCp ∆T(inlet stream) = mλ (steam)

(m Cp (recycle) + m Cp (air) +m Cp (methanol liq)+mλ(methanol) +m Cp (methanol gas) )(285-25) =

18.08x105 = m x 3278.20

Steam required m = 551.52 Kg

2)Reactor CH3OH = 3200 Kg CH3OH = 64 Kg O2 = 5815.6 Kg O2 = 4153.92 Kg N2 = 41157.2 Kg N2 = 41157.20 Kg H20 = 932.31 Kg H20 = 2783.61 Kg (285 oC) CO = 135.80 Kg HCOOH = 46 Kg HCHO = 2764.50 Kg

FIG 8.2 Reactions: CH3OH + 1/2 O2 HCHO + H20 ∆ Ho = -4839 KJ/Kg HCHO + 1/2 O2 CO + H20 ∆Ho = -7115.35 KJ/Kg For an isothermal reaction: Σ ∆H(products) + Σ ∆Ho - Σ ∆H(reactants) =∆H (∆H = m CP∆ T) (∆T=285-25=260) Substituting values from table 1, ∆H = 13.8687x106 KJ

∆H (reactor) = m Cp∆T(cooling oil)

13.8687x106 = m x 1.75x 110

Oil required m = 72045.058 Kg

Isothermal

Reactor

25

3) Heat exchanger 1: Oil (120 oC) H20 (25 oC) Steam (100 oC) Oil (230 oC)

FIG 8.3

mCp ∆T(cooling oil) = mCP ∆T(H20) + mλ (steam)

13.8687x106 = m x 1.88 x 75 + m x 2255

Water required m = 5144.19 Kg

4) Heat exchanger 2:

Steam (100 oC) Reactor outlet (285 oC) (110 oC) H20 (25 oC)

FIG 8.4

mCp ∆T(products) = m Cp∆T(H20) + mλ (steam)

9.1815x106 = m x 1.88 x 75 + m x 2255

Water required m = 3405.60 Kg

5)Absorber:

Bottom: Water (50 oC)

Products (gases) H20 (liquid)

(110 oC) (110 oC)

Water (25 oC)

FIG 8.5

mCp ∆T(cooling H20) = mλ (condensing water)

m x 1.88 x 25 = 2783.61 x 2228.7

Cooling water required m = 13996.121 Kg

Top:

Water (50 oC)

26

Products (gases) Products (gases)

(110 oC) (30 oC)

Water(25 oC)

FIG. 8.6

mCp∆T(cooling H20) = mCp∆T (product gases)

m x 1.88 x 25 = mCp (110-30)

Cooling water required m = 81457.60 Kg

27

9. DESIGN

HEAT EXCHANGER 1

U0A0∆TL = (m CP∆T) OIL

Where U0 = Overall heat transfer co-efficient (KW/m2 oC)

A0= Outside tube area (m2)

∆TL = Logarithmic mean temperature (oC)

∆TL = (230 – 100) – (30 -25)

ln (130/5)

= 38.3659 oC

U0x 2Π x R x L x n x∆ TL = 3852.409

U0 = 1

1/h0 + (A0/Ai) ( 1/hi)

Nu =0 .023 (Re)0.8 (Pr)0.3

Assume that d0 = ¾ “ BWG NO = 16

d0= 0.0191 m

di = 0.0157 m

m = AV ρ

V = m / A ρ = (72045.05 /3600)

Π x (0.0157/2)2 x 864.9939

= 119.56 m/s

Nu = 0.023 x (120262.0154) (1.9989)

= 5504.1158

hi = 44.87 kW/ m2 oC

Assume ho = 1.7201 kW/ m2 oC

28

1

Uo =

(1/1.7021) + (1.216/44.87)

Uo = 1.6270 kW/ m2 oC

Assume L = 2.7432 m

1.6270 x 3.14 x 0.0191x111 x 2.7432 x n = 3852.409

HEAT EXCHANGER 2

U0A0 ∆TL = (m CP∆T) PRODUCTS

∆TL = (285 – 100) – ( 110 -25)

ln (185/85)

= 128.584 oC

U0x 2 Πx R x L x n x ∆TL = 2550.4324

U0 = 1

1/h0 + (A0/Ai) (1/hi)

Nu =0 .023 (Re)0.8 (Pr)0.3

Assume that d0 = ¾ “ BWG NO = 16

d0= 0.0191 m

di = 0.0157 m

m = AV ρ

V = m / A ρ = (51105.03/3600)

Π x (0.0157/2)2 x 900

= 81.517m/s

n = 147 tubes

29

Nu = 0.023 x (138695.051) (0.6795)

= 21676.058

hi = 181.714 kW/ m2 oC

Assume ho = 1.7201 kW/ m2 oC

1

Uo = (1/1.7021) + (1.216/181.714)

Uo = 1.682kW/ m2 oC

Assume L = 3.048 m

1.682 x 3.14 x 0.0191x128.5842 x 3.048x n = 2550.4324

REACTOR DESIGN

Specification: Packed multiple tubular reactor

Assumption:

Shell diameter of each reactor =39”

= 0.99 m

Tube specifications: 1 1/2" BWG (No 16)

Corresponding number of tubes = 307

Volume of one tube:

ID = 0.03479 m L = 1.5 m

Volume =Π R2L = Πx0.01742 x 1.5=1.426 x10-3 m3

Volume of 307 tubes =0.4379 m3

Void fraction = 0.4 (assumption)

Volume occupied by catalyst/reactor = 0.4379 x 0.6

= 0.2627 m3

Space velocity = 5 m3 of gas charged to the reactor (assumption)

(at NTP) hr- m3 of catalyst per tube

Space velocity for 307 tubes = 1535 m3 of gas charged to the reactor

n = 65 tubes

30

hr- m3 of catalyst

Volumetric flow rate: (at NTP)

No of moles entering the reactor/hr = 1803.43 Kmol/hr

Pressure = 1.1 atm; Temperature = 298 K

R = 0.08206 atm m3 / Kmol K

PV= nRT

V = 1803.43 x 0.08206 x 298 = 40,091.70 m3 of gas/hr

1.1

Volumetric flow rate

Volume of catalyst = = 26.1183 m3

Space velocity

Number of reactors required = volume of catalyst Volume occupied by

Catalyst per reactor

= 26.1183/0.2627

= 99.42 ~ 100 reactors

ABSORBER DESIGN

Absorber height Z =Noy x Hoy

Noy = yb - ya ; ∆YL = (yb-yb *)- ( ya-ya * )

∆ YL ln ((yb-yb *)/ ( ya-ya * ))

Hoy = Gms / Kya ; where Gms = mass flow rate of gases (Kg/s)

K ya = overall mass transfer coefficient based on

gas phase (Kmol/m3 s )

Calculation of Noy:

ya = 3.13 x 10 –4 xa = 0

yb = 0.0499 xb = 0.4368

31

Kya = 0.4 Kmol/m3s (assumption)

Gms (ya-yb) =1.32 Lms (xb-xa ) (x,y are mole fractions of HCHO in

liquid and gas phase resp)

xb = 0.5877

yb * = 0.067 xb * (equilibrium data)

yb * = 0.039

substituting the above values,

∆YL = 0.00298

Noy = 16.69 ~ 17 transfer units

Calculation of Hoy:

Gms = 2764.50 Kg/hr = 0.7679 Kg/ s

Gas density at 110oC = 0.90 Kg/m3

Liquid density = 1000 Kg/m3

Viscosity = 0.0009 Kg/ms

K4 = 0.9; FP = 1 0.5

Mass flow rate per unit area V = K4 ρv (ρl - ρv )

(Kg/m2s ) 13.1 FP (µ l /ρl )0.1

Substituting the values,

V = 1.4616 Kg/m2s

Column area = Gms/V =0.5252 m2

Column diameter =(0.5252 x 4/∏)0.5 = 0.8179 m

Hoy = Gma/Kya=Gms/(column area x Kya )

= 0.19 m

Calculation of height: (for the top of the absorber)

Z = 17 x 0.19

Z= 3.33m

32

10. PLANT LAYOUT

INTRODUCTION

The economic construction and efficient operation of a process unit will

depend upon how well the plant and equipment specified on the process flowsheet is

laid out and on the profitability of the project with its scope for future expansion.

Plant location and site selection should be made before the plant layout.

Plant location and site selection:

The location of the plant has a crucial effect on the profitability of the project.

The important factors that are to be considered while selecting a site are:

1. Location, with respect to market area

2. Raw material supply

3. Transport facilities

4. Availability of Labour

5. Availability of utilities

6. Availability of suitable land

7. Environmental impact and effluent disposal

8. Local community considerations

9. Climate

10. Political and strategic considerations

1. Marketing area

For materials that are produced in bulk quantities, such as cement, mineral

acids, and fertilizers where the cost of product per tone is relatively low and the cost

of transport a significant fraction of the sales price, the plant should be located close

to the primary product. This consideration will be less important for low volume

production, high-priced products, such as pharmaceutical.

2. Raw materials

The availability and price of suitable raw materials will often determine the

site location. Plants producing bulk chemicals are best located close to the source of

33

major raw material, where this is also close to the marketing area. For the production

of formaldehyde the site should be preferably near a methanol plant.

3. Transport

Transport of raw materials and products is an important factor to be

considered. Transport of products can be in any of the four modes of transport.

4. Availability of labour

Labour will be needed for construction of the plant and its operation. Skilled

construction workers will usually be brought in from outside the site area, but there

should be an adequate pool of unskilled labours available locally; and labour suitable

for training to operate the plant. Skilled tradesman will be needed for plant

maintenance. Local trade union customs and restrictive practices will have to be

considered when assessing the availability and suitability of the local labour for

recruitment and training.

5. Environmental impact and effluent disposal

All industrial processes produce waste products, and full consideration must

be given to the difficulties and cost of their disposal. The disposal of toxic and

harmful effluents will be covered by the local regulations and the appropriate

authorities must be consulted during the initial survey to determine the standards that

must be met.

6. Local community consideration

The proposed plant must fit n with and be acceptable to the local community.

Full consideration must be given to the safe location of the plant so that it does not

impose a significant additional risk to the community on a new site, the local

community must be able to provide adequate facilities for the plant personnel.

7. Land

Sufficient suitable land must be available for the proposed plant and for future

expansion. The land should ideally be flat, well drained and have suitable load-

bearing characteristics full site evaluation should be made to determine the need for

piling or other special foundations.

8. Climate

34

Adverse climatic conditions, at a site will increase costs. Abnormally low

temperatures will require the provision of additional insulation and special heating for

equipment and pipe runs.

9. Political and strategic considerations

Capital grants, tax concessions and other inducements are often given by

governments to direct new investment to preferred locations; such as areas of high

unemployment. The availability of such grants can be overriding consideration in the

site selection.

After considering the location of the site the plant layout is completed. It

involves placing of equipment so that the following are minimized:

1. Damage to persons and property in case of fire explosion or toxic release

2. Maintenance costs

3. Number of people required to operate the plant.

4. Construction costs

5. Cost of planned expansion.

In plant layout first thing that should be done is to determine the direction of the

prevailing wind. Wind direction will decide the location of the plant.

List of items that should be placed upwind and downwind of the plant is given down.

Items that should be located upwind of the plant.

Laboratories

Fire station

Offices building

Canteen and Change house

Storehouse

Medical facilities

Electrical substation

Water treatment plant

Water pumps

Workshops

35

Items that should be located downwind of the plant

Blowdown tanks

Settling tanks

Burning flares

The various units that should be laid out include

1. Main processing unit

2. Storage for raw materials and products

3. Maintenance workshops

4. Laboratories for process control

5. Fire stations and other emergency services

6. Utilities: steam boilers, compressed air, power generation, refrigeration

7. Effluent disposal plant

8. Offices for general administration

9. Canteens and other amenity buildings,such as medical centers

10. Car parks

1. Processing area

Processing area also known as plant area is the main part of the plant where

the actual production takes place. There are two ways of laying out the processing

area

1.) Grouped layout

2.) Flowline layout

Grouped layout

Grouped layout places all similar pieces of equipment adjacent. This provides

for ease of operation and switching from one unit to another. This is suitable for all

plants.

36

Flowline layout

Flowline layout uses the line system, which locates all the equipment in the

order in which it occurs on the flowsheet. This minimizes the length of transfer lines

and therefore reduces the energy needed to transport materials. This is used mainly for

small volume products.

2. Storage house

The main stage areas should be placed between the loading and unloading

facilities and the process they serve. The amount of space required for storage is

determined from how much is to be stored in what containers. In raw material storage,

liquids are stored in small containers or in a pile on the ground. Automatic storage and

retrieving equipment can be substantially cut down storage

3. Laboratories

Quality control laboratories are a necessary part of any plant and must be

included in all cost estimates. Adequate space must be provided in them for

performing all tests, and for clearing and storing laboratory sampling and testing

containers.

4. Transport

The transport of materials and products to and from the plant will be an

overriding consideration in site selection. If practicable, a site should be selected that

is close to at least two major forms of transport: road, rail, waterway or a seaport.

Rail transport will be cheaper for long distance transport of bulk chemicals.

Road transport is being increasingly used and is suitable for local distribution. Road

area also used for fire fighting equipment and other emergency vehicles and for

maintenance equipment. This means that there should be a road around the perimeter

of the site. No roads should be a dead end. All major traffic should be kept away form

the processing areas. It is wise to locate all loading and unloading facilities ,as well as

plant offices, personnel facilities near the main road to minimize traffic congestion

within the plant and to reduce danger.

5. Utilities

37

The word “Utilities” is now generally used for ancillary services needed in the

operation of any production process. These services will normally be supplied from a

central site facility and will include:

• Electricity

• Steam for process heating

• Cooling water

• Water for general use

• Inert gas supplies

Electricity

Electrical power will be needed at all the sites. Electrochemical processes that

require large quantities of power need to be located close to a cheap source of power.

Transformers will be used to step down the supply voltage to the voltages used on the

purpose.

Steam for process heating

The steam for process heating is usually generated in water tube boilers using the

most economical fuel available. The process temperature can be obtained with low-

pressure steam. A competitively priced fuel must be available on site for steam

generation.

Cooling water

Chemical processes invariably require large quantities of water for cooling. The

cooling water required can be taken from a river or lake or from the sea.

Water for general use

Water is needed in large quantities for general purpose and the plant must be

located near the sources of water of suitable quality, process water may be drawn

from river from wells or purchased from a local authority.

Offices

The location of this building should be arranged so as to minimize the time

spent by personnel in travelling between buildings. Administration offices in which a

38

relatively large number of people working should be located well from potentially

hazardous process.

Canteen

Canteen should be spacious and large enough for the workers with good and hygienic

food.

Fire station

Fire station should be located adjacent to the plant area, so that in case of fire or

emergency, the service can be put into action

Medical facilities

Medical facilities should be provided with at least basic facilities giving first aid

to the injured workers. Provision must be made for the environmentally acceptable

disposal of effluent.

The layout of the plant can be made effective by

1. Adopting the shortest run of connecting pipe between equipments and the least

amount of structural steel work and thereby reducing the cost.

2. Equipment that need frequent operator attention should be located convenient to

control rooms.

3. Locating the vessels that require frequent replacement of packing or catalyst

outside the building

4. Providing at least two escape routes for operators from each level in process

buildings.

5. Convenient location of the equipment so that it can be tied with any future

expansion of the process.

39

CANTEE

WORKSHO

FINISHED PRODUCT STORAGE

ADMINISTRATIVE OFFICE

SECURITY OFFICE

CANTEEN

WORKSHOP

RAW MATERIAL STORAGE

PROCESSING AREA

EXTENSION AREA

ENTRY EXIT

SAFETY HEALTH DEPT CENTER

MAIN ROAD

FIG 10.1 PLANT LAYOUT

40

11. MATERIALS OF CONSTRUCTION

Materials of construction may be divided into two general classifications of

metals and non-metals.

11.1 Metals

Pure metals and metallic alloys are included under this classification. Some

commonly used metals are discussed in the following section.

Iron and steel

Although many materials have greater corrosion resistance than iron and steel,

cost aspects favor the use of iron and steel. As a result, they are often used as

materials of construction when it is known that some corrosion will occur.

In general, cast iron and carbon steel exhibit about the same corrosion

resistance. They are not suitable with dilute acids, but can be used with strong acids,

since a protective coating composed of corrosion products forms on the metal surface.

Carbon steel plates for reactor vessels are a good example. This application

generally requires a minimum level of mechanical properties, weldability, formability,

and toughness as well as some assurance that these properties will be uniform

throughout.

Stainless steel

There are more than 100 different types of stainless steels. These materials are

high chromium or high nickel-chromium alloys of iron containing small amounts of

other essential constituents. They have excellent corrosion-resistance and heat

resistance properties.

The addition of molybdenum to the alloy increases the corrosion resistance

and high – temperature strength. If nickel is not included, the low –temperature

brittleness of the material is increased and the ductility and pit type corrosion

resistance are reduced. The presence of chromium in the alloy gives resistance to

oxidizing agents.

Aluminum

41

The lightness and relative ease of fabrication of aluminum and its alloys are

factors favoring the use of these materials. Aluminum resists attack by acids because a

surface film of inert hydrated by aluminum oxide is formed. This film adheres to the

surface and offers good protection unless materials, which can remove the oxide, such

as halogen acids or alkalis, are present.

11.2 Non-metals

Plastics

In comparison with metallic materials, the use of plastics is limited to

relatively moderate temperature and pressures.generally,plastics have excellent

resistance to weak mineral acids and are unaffected by inorganic salt solutions-areas

where metals are not entirely suitable. One of the most chemical resistant plastics

commercially available today is tetrefluoroethylene.This thermoplastic is practically

unaffected by all alkalis and acids except fluorine and chlorine gas at elevated

temperatures and molten metals.

Epoxies reinforced with fiberglass have very high strengths and resistance to

heat. Chemical resistance of the epoxy resin is excellent in non-oxidizing and weak

acids not good against strong acids.

12. INSTRUMENTATION AND CONTROL

Instruments are provided to monitor key process variable during plant

operation. It is desirable that the process variable to be monitored be measured

directly; often however this is impractical and some dependent variable, that is easier

to measure, is monitored in its place. The temperature instrument may form part of a

control loop controlling, say, reflux flow; with the composition of the overheads

checked frequently by sampling and laboratory analysis.

Objectives

The primary objectives of the designer when specifying instrumentation and

control schemes are:

1) Safe plant operation:

42

To keep the process variables within known safe operating limits.

To detect dangerous situations as they develop and to provide alarms and automatic

shut down systems.

To provide interlocks and alarms to prevent dangerous operating procedures.

2) Production rate:

To achieve the design product output

3) Product quality:

To maintain the product composition within the specified quality standards.

4) Cost:

To operate at the lowest production cost, commensurate with the other objectives.

In a typical chemical processing plant these objectives are achieved by a

combination of automatic control, manual monitoring and laboratory analysis.

Guide rules:

The following procedure can be used when drawing up preliminary piping and

instrumentation diagrams.

1. Identify and draw in those control loops that are obviously needed for steady

plant operation, such as:

Level controls

Flow controls

Pressure controls

Temperature controls

2. Identify the key process variables that need to be controlled to achieve the

specified product quality. Include control loops using direct measurement of

the controlled variable, where possible, if not practicable, select a suitable

dependent variable.

3. Identify and include those additional control loops required for safe operation,

not already covered in steps 1 & 2

43

4. Decide & show those ancillary instruments needed for monitoring of the plant

operation by the operators; and for trouble-shooting and plant development. it

is well worthwhile including additional connections for instruments, which

may be needed for future troubleshooting and development ,even if the

instruments are not installed permanently. This would include extra thermo

wells, pressure tapings, orifice flanges, and extra sample points.

5. Decide on the location of sample points.

6. Decide on the need for recorders and the location of the readout points, local

or control room. This step would be done in conjunction with step 1 to 4

7. Decide on the alarms and interlocks need, this would be done in conjunction

with step 3.

Typical control Systems

Level control

In any equipment where an interface exists between two phases some means

of maintaining the interface at the required level must be provided. This may be

incorporated in the design of the equipment. The control valve should be placed on

the discharge line from the pump.

Pressure control

Pressure control will be necessary for most systems handling vapor or gas.

The method of control will depend on the nature of process.

Flow control

Flow control is usually associated with inventory control in a storage tank or

other equipment. There must be a reservoir to take up the changes in flow rate. To

provide flow control on a compression or pump running at a fixed speed and

supplying a near constant volume output, a by-pass would be used.

Heat Exchangers

Here, the temperature can be controlled by varying the flow of the cooling or

heating medium. If the exchange is between two process streams whose flows are

fixed, by-pass control will have to be used.

44

Cascade control

With this arrangement, the output of one controller is used to adjust the set

point of another. Cascade control a give smoother control in situations where direct

control of variable would lead to unstable operation. The “slave” controller can be

used to compensate for any short-term variations in, say, a service stream flow, which

would upset the controlled variable, the primary controller and long term variations.

Reactor control

The schemes used for reactor control depend on the process and type of

reactor. If a reliable on-line analyzer is available and the reactor dynamics are

suitable, the product composition can be monitored continuously and the reactor

conditions and feed flows controlled automatically to maintain the desired product

composition and yield. More often, the operation is the final link in the control loop,

adjusting the controller set points to maintain the product within specification, based

on periodic laboratory analyzer.

Reactor temperature will normally be controlled by regulating the flow of the

heating or cooling medium. Pressure is usually held constant. Material balance control

will be necessary to maintain the correct flow of reactants to the reactor and flow of

product and unreacted materials from the reactor.

Alarms and safety trips, and interlocks

Alarms are used to alert operators of serious and potentially hazardous,

deviations in process conditions. Key instruments are fitted with switches and relays

to operate audible and visual alarms on the control panels. Where delay or lack of

response from the operator may lead to a hazardous situation, the instrument would be

fitted with trip system to take action automatically to avert the hazard. Interlocks are

included to prevent operations departing from the required sequence. They may be

incorporated in the control system design, as pneumatic or mechanical locks.

45

13. STORAGE AND TRANSPORTATION

Formaldehyde solutions can be stored and transported in containers made of

stainless steel, aluminum, enamel or polyester resins. Iron containers lined with

epoxide resin or plastic may also be used, although stainless steel containers are

preferred, especially for higher formaldehyde concentrations. Unprotected vessels of

iron, copper, nickel and zinc alloys must not be used.

With a decrease in temperature and/or increase in concentration, aqueous

formaldehyde solutions tend to precipitate paraformaldehyde. On other hand, as the

temperature increases, so does the tendency to form formic acid. Trace metallic

impurities such as iron can boost the rate of formation of formic acid. Therefore, an

appropriate storage temperature must be maintained. Stabilizers can also be added to

prevent polymerization. Methanol is generally used as a stabilizer. Other compounds

used as a stabilizer for formaldehyde are ethanol, propanol, urea, melamine, hydrazine

hydrate and bismelamines.

Table 2 Storage temperatures for commercial formaldehyde solutions Formaldehyde content,wt% Methanol content,wt% Storage

temperature,oC 30 ≤1 7-10 37 <1 35 37 7 21 37 10-12 6-7 50 1-2 60-65 50 1-2 45

14. HEALTH AND SAFETY CONSIDERATIONS Sources of human exposure to formaldehyde are engine exhaust, tobacco

smoke, natural gas, fossil fuels, waste incineration, and oil refineries. It is an essential

intermediate in cell metabolism in mammals and humans. All tissues contain

measurable amounts of formaldehyde, e.g., human blood 2-3 ppm.

Formaldehyde causes eye, upper respiratory tract, and skin irritation and is

skin sensitizer. Although sensory irritation, e.g., eye irritation, has been reported at

concentrations as low as 0.1 ppm in uncontrolled studies, significant eye/nose/throat

46

irritation does not generally occur until concentrations of 1 ppm, based on controlled

human chamber studies.

Table 3 Dose – response relationship following human exposure to gaseous formaldehyde Effect Exposure level,ppm

Odor threshold 0.05 – 1.0

Irritation threshold in eyes ,nose, or throat 0.2 – 1.6

Stronger irritation of upper respiratory

tract,coughing,lacrimination,extreme

discomfort

3 - 6

Immediate dyspnea,burning in nose and throat,

heavy coughing and lacrimation

10- 50

Necrosis of mucous membranes,

laryngospasm,pulmonary edema

>50

Formaldehyde is classified as a probable human carcinogen by the

International Agency for Research on Cancer(IARC).Lifetime inhalation studies with

rodents have shown nasal cancer at formaldehyde concentrations that are

overwhelmed cellular defense mechanisms,ie,6 to 15 ppm.No nasal cancer was seen

at 2 ppm or lower levels.

Available data do not indicate that formaldehyde produces mutagenic,

tetrogenic, embryo toxic effects in man at concentrations which humans are exposed

to or can tolerate.

47

15. COST ESTIMATION ESTIMATION OF THE TOTAL CAPITAL INVESTMENT

The total capital investment “I” involves the following:

A: FIXED CAPITAL INVESTMENT IN THE PROCESS AREA, IF

B: THE CAPITAL INVESTMENT IN THE AUXILLARY

SERVICES,IA

C: THE CAPITAL INVESTMENT AS WORKING CAPITAL, IW

i.e., I=IF+IA+W A. FIXED CAPITAL INVESTMENT IN THE PROCESS AREA, IF

This is the investment in all processing equipment within the processing area.

Fixed capital investment in the process area, IF= Direct plant cost + Indirect plant cost

The approximate delivered cost of major equipments used in the proposed

Formaldehyde manufacturing plant are furnished below:

(Table 4)

S.NO EQUIPMENT UNITS Cost in Lakhs /Unit

Cost in Lakhs

1 Heat Exchanger 3 20 60

2 Reactors 100 3.85 385

3 Absorption column 1 50 50

4 Deionizer 1 1 1

5 Pumps 3 0.3 0.9

6 Blower 1 0.1 0.1

7 Storage tank sealed 1 1.5 1.5

8 Miscellaneous 1

Total 500

48

DIRECT COST FACTOR (Table 5)

S.No Items Direct Cost Factor

1 Delivered cost of major equipments 100

2 Equipment installations 15

3 Insulation 15

4 Instrumentation 15

5 Piping 75

6 Land and building 30

7 Foundation 10

8 Electrical 15

9 Clean up 5

Total direct cost factor 280

Direct plant cost = (Delivered cost of major equipments)

X (Total direct cost factor)/100

Direct plant cost = (500 x 280)/100

= 1400 lakhs

INDIRECT COST FACTOR (Table 6)

S.NO ITEMS INDIRECT COST FACTOR

1 Over head contractor etc 30

2 Engineering fee 13

3 Contingency 13

Total indirect cost factor 56

Indirect plant cost = (Direct plant cost) x (Total indirect cost factor)/100

= (1400 x 56)/100

= 784 lakhs

Fixed capital investment in process area, IF = Direct plant cost

+ Indirect plant cost

= 1400 + 784

= 2184 lakhs

49

B.THE CAPITAL INVESTMENT IN THE AUXILLARY SERVICES,IA

Such items like steam generators, fuel stations and fire protection facilities are

commonly stationed outside the process area and serve the system under

consideration.

Table 7:

S.No

Items Auxillary Service Cost Factor

1 Auxiliary buildings 5

2 Water supply 2

3 Electric main substation 1.5

4 Process waste system 1

5 Raw material storage 1

6 Fire protection system 0.7

7 Roads 0.5

8 Sanitary and waste disposal 0.2

9 Communication 0.2

10 Yard and fence lighting 0.2

Total 12.3

Capital investment in the auxillary services = (Fixed capital investment in process

area) x (Auxiliary services cost )/100

= (2184 x 12.3)/100

= 268.632 lakhs

Installed cost = Fixed capital investment in the process area

+ Capital investment in the auxiliary services

= 2184 + 268.632

= 2452.632 lakhs

50

C.THE CAPITAL INVESTMENT AS WORKING CAPITAL, IW

This is the capital invested in the form of cash to meet day-to-day operational

expenses, inventories of raw materials and products. The working capital may be

assumed as 15% of the total capital investment made in the plant (I)

Capital investment as working capital, IW = ((2184 + 268.632) X 15) /85

= 432.817 lakhs

Total capital investment, I = IF+ IA + IW

= 2184 + 268.632 + 432.817

= 2885.449 lakhs

ESTIMATION OF MANUFACTURING COST

The manufacturing cost may be divided into three items, as follows

A. Cost proportional to total investment

B. Cost proportional to production rate

C. Cost proportional to labour requirement

A. COST PROPORTIONAL TO TOTAL INVESTMENT

This includes the factors, which are independent of production rate and

proportional to the fixed investment such as

- Maintenance- labour and material

- Property taxes

- Insurance

- Safety expenses

- Protection, security and first aid

- General services, laboratory, roads, etc.

- Administrative services

For all this purpose we shall charge 15% of the installed cost of the plant

=( Installed cost x 0.15)

= 2452.632 x 0.15

= 367.894 lakhs

B. COST PROPORTIONAL TO PRODUCTION RATE

The factors proportional to production rate are

- Raw material costs

- Utilities cost-power, fuel, water, steam, etc.

- Maintenance cost

- Chemical,warehouse,shipping expenses

51

Assuming that the cost proportional to production rate is nearly 60% of total capital

investment,

Cost proportional to production rate = (Total capital investment x 0.6)

= 2885.449 x 0.6

= 1732.269 lakhs

C. COST PROPORTIONAL TO LABOUR REQUIREMENT

The cost proportional to labour requirement might amount 10% of total

manufacturing cost.

Cost proportional to labour requirement = (367.894 + 1731.269) x

(0.1)/(0.9)

= 233.240 lakhs

Therefore, manufacturing cost = (364.894 + 1731.269 + 233.240)

= 2332.403 lakhs

SALES PRICE OF PRODUCT

Market price of Formaldehyde = Rs.15 /kg

Production rate = 21196.8 TPA

Total sales income = 3179.52 lakhs

PROFITABILITY ANALYSIS

A.DEPRICIATION

According to sinking fund method: R= (V- VS) I/ (1+I)n

R = Uniform annual payments made at the end of each year

V = Installed cost of the plant

VS = Salvage value

N = Life period (assumed to be 15 years)

I = Annual interest rate (taken as 15%)

R = (2452.632 x 0.15) / ((1+ 0.15)15 -1)

= 51.547 lakhs

B.GROSS PROFIT

Gross profit = Total sales income – Manufacturing cost

= 3179.52 – 2332.40

= 847.117 lakhs

52

C.NET PROFIT

It is defined as the annual return on the investment made after deducting

depreciation and taxes. Tax rate is assumed to be 40%

Net profit = Gross profit – Depreciation – (Gross profit x Tax rate)

= 847.117- 51.547-(847.117x 0.4)

= 456.723 lakhs

D.ANNUAL RATE OF RETURN

RATE OF RETURN = (100 x Net profit) /Installed cost

= (100 x 456.723)/2452.632

= 18.619%

E.PAYOUT PERIOD

Payout period = Depreciable fixed investment /(Profit + Depreciation)

= 2452.632 / (456.723 + 51.547)

= 4.825 years

16. CONCLUSION

The metal oxide process was selected for the manufacture of formaldehyde.

From mass balance and energy balance, the various equipments were designed

and cost estimation was made. The payout period was found to be 5 years. Hence the

project is feasible .

53

REFERENCES

1. Austin , G.T. Shreve’s Chemical Process Industries,Fifth edition McGraw-Hill,1984

2. Charles E.Dryden , Outlines of Chemical Technology for 21st Century, Third

edition , NEW YORK PRESS,1997

3. John Mc.Ketta - Encyclopedia of Chemical Technology,vol 8,1997

4. Kirk and Othmer - Encyclopedia of Chemical Technology,vol 11,1997

5. Mccabe, Smith and Harriot - Unit Operations in Chemical Engineering ,sixth edition,McGraw Hill,2001

6. Perry, R.H., and D.W. GREEN , Perry’s chemical engineers’ Handbook,

Seventh edition, McGraw-Hill,1997.

7. Robert E.Treybal - Mass Transfer Operations, Third edition, 1984. 8. Ullmann - Encyclopedia Of Chemical Technology, Vol. A11, 1997.