Thesis about a apetroleum industry

3

Design project on the processing of 10,000 barrel/day crude oil for

production of n-paraffin

Session: 2010-2014

Project Supervisor

Engr. Khaqan Javed

Project Co-Supervisor

Engr. Aamir Ali

Submitted by

Beenish Younis Cheema 2010-UET-ShCET-LHR-CE-10

Muhammad Usama 2010-UET-ShCET-LHR-CE-12

Bilal Ahmad 2010-UET-ShCET-LHR-CE-26

Muzammil Muzaffar 2010-UET-ShCET-LHR-CE-27

Department of Chemical Engineering

Sharif College of Engineering and Technology (affiliated with UET),

Lahore

4

Design project on the processing of 10,000 barrel/day crude oil for

the production of n-paraffin

This project is submitted to the Department of Chemical Engineering, Sharif

College of Engineering and Technology for the partial fulfillment of the

requirements for the

Bachelor of Science

In

Chemical Engineering

Session 2010-2014

Approved on: ____________

Supervisor: External Examiner:

Engr. Khaqan Javed Prof. Dr. Javed Iqbal

________________ ________________

Co-Supervisor: Chairman:

Engr. Aamir Ali Prof. Dr. Anwar Ul Haq

________________ ________________

Department of Chemical Engineering

Sharif College of Engineering and Technology (affiliated with UET),

Lahore

5

DEDICATION

This project work is dedicated to our beloved parents, respected teachers and

to all those people, who are working to make our motherland Pakistan a

Prosperous country.

6

Acknowledgment

We take on the initiation with the prestiges name Almighty ALLAH, lord, designer, builder of the most complex processing plants; the human body. Its

accurate and sophisticated fluid transportation, gas absorption, filtration,

chemical reactions and electronic control systems with partial mechanical

structural capillaries is a product of HIS engineering that we strive to understand

and duplicate WHO gave us caliber, incentives and courage to complete this project within prescribed limits and to the HOLY PROPHET MOHAMMAD (S.A.W)

who showed light of knowledge to the humanity as a whole.

The ideas of report writing are usually attributable to all of the group members

and the sources, which helped us a lot to compile it. This is all due to the

illuminated guidance of our teachers as they are builders of our academic

carrier, all this could not have been done without their enlightened supervision

and coaching. For this we are very much grateful to them, especially Engr.

Khaqan Javed and Engr. Aamir Ali who spared a lot of their precious time in

advising and helping us throughout our project.

It is with great pleasure and extreme feelings of obligation that we thank

professor, Dr. Khalid Qamar (Director of Sharif College of Engineering and

Technology (affiliated with UET), Lahore) and Dr. Anwar-ul-Haque (Head of

Chemical Engineering Department SCET) for their constructive criticism and

valuable suggestions during our academic carrier.

Last but not Least, we owe immense sense of gratitude to our parents who not

only supported us financially throughout our education but gave us the strength

of character and would always remain as beacon of light for us.

7

Preface

The design report on the production of Linear Alkyl Benzene (LAB) from Crude Oil

is a very useful process used worldwide for the production of LAB, we chose this

project as there is no plant in Pakistan which produces LAB.

The design report of our project is made very carefully and honestly, so hopefully

the content is adequate for the basic understanding of the process as each

and every aspect is discussed in detail with clear visual graphics. All the

designing and calculations are done by using up to date correlations of heat

transfer, mass transfer and equipment design. This report should also be useful to

the engineers in the chemical engineering department.

All the calculations are done in English units and the cost estimation is done in

dollars. The references are given in detail at the end of the report so each can

be accessed easily.

Separate chapters are devoted to each of the step for the designing of a

project including introduction, process description, material and energy

balances and equipment design. For the good operation and safety purpose,

the instrumentation of equipment is done and explained in a separate chapter.

Also, the project cost evaluation is done in the other chapter. Environmental

impacts are also discussed in the last chapter.

Authors

8

Table of Contents

1. INTRODUCTION ... 11 1.1 Synopsis ....... 11 1.2 Refineries . 12 1.3 List of refineries in Pakistan . 13 1.4 Properties and uses of product . 13 2. PROCESS DESCRIPTION ...................... 15 2.1 Brief overview of process .... 15 2.2 Raw Material ... 15 2.3 Properties ........ 16 2.4 Overall Process .. 16 3. PROCESS DIAGRAMS 18 3.1 Input/ Output Diagram .... 18 3.2 Functional Diagram .. 19 3.3 Operational Diagram ... 19 3.4 Process Flow Diagram ..... 20 4. MATERIAL AND ENERGY BALANCE ... 20 4.1 Material and Energy Balance over equipments ..... 21 5. EQUIPMENT DESIGN ... 37 5.1 Plug Flow Reactor Design ... 41 5.2 Distillation Column Design ..... 53 5.3 Heat Exchanger Design .. 67 5.4 Fractionating Column Design ....... 75 6. INSTRMENTATION AND PROCESS CONTROL .... 83 6.1 Introduction .................................... 83 6.2 The Importance of Process Control ......... 83 6.3 Learning objectives .................... 84 6.4 Process control ........................... 84 6.5 Process variables ...... 85

9

6.6 Objectives ...... 85 6.7 Process Control over Fractionating Column-1 ..... 86 6.8 Cascade Control .......... 87 6.9 Feedback Control ........ 88 7. COST ESTIMATION .. 89 7.1 Equipment Costs ........... 89 7.2 Estimation of Project Cost ....... 95 7.3 Estimation of Fixed Capital Investment ............. 96 7.4 Estimation of Total Capital Investment ........... 97 8. HAZOP STUDY 98 8.1 What Is a HAZOP Study? ............ 98 8.2 Objective of HAZOP ............ 99 8.3 How and Why HAZOP is used ................................. 99 8.4 Purpose of HAZOP ............................................. 100 8.5 HAZOP Study Flowchart ............................. 101 8.6 HAZOP Study for a Distillation Column ............ 102 9. ENVIRONMENTAL IMPACTS .... 104 9.1 Introduction ......... 104 9.2 Potential Environmental Impacts .......... 104 REFERENCES .. 109

10

List of Figures

Fig. 1.1a Regional Lab Capacity 11 Fig. 3.1a Input/ Output Diagram .... 18 Fig. 3.2a Functional Diagram .. 19 Fig. 3.3a Operational Diagram ... 20 Fig. 3.4a Process Flow Diagram ..... 20 Fig. 4.1a Mass and Energy Balance Diagram 21 Fig. 5.1a Plug Flow Reactor Schematic Diagram .. 43 Fig. 5.2a Direct Sequencing Diagram .. 55 Fig. 5.2b Indirect Sequencing Diagram ... 56 Fig. 5.2c Indirect Sequence for Process Diagram .... 57 Fig. 5.4a Fractionating Column Schematic Diagram .. 78 Fig. 6.7a Process Control on FC-1 Diagram .... 87 Fig. 8.5a HAZOP Study Flowchart .... 102

11

Chapter 1

Introduction

1.1 Synopsis

Current statistics shows an ever increasing demand for Linear Alkyl Benzene

(LAB). There is no plant in Pakistan that produces LAB. Statistics show that 150-200

metric tons/day of LAB is being imported in Pakistan. These statistics inspired us

to prefer this project over other projects. Regional LAB capacity statistics are

shown in the figure mentioned below:

According to the capacity statistics shown above it is easy to conclude that

Asia is the largest consumer or user of LAB, but out of the countries in Asia only

Figure 1.1a

12

Pakistan is the one which has no plant to produce LAB as it is a very large scale

industry and this plant is expensive to install as well. According to the emerging

needs of LAB it is necessary to install a plant in Pakistan as well. We have tried to

work on the project so that we can contribute towards the progress of our

country. This project is an integration of petroleum and chemicals therefore it

comes under the category of petrochemical industries.

1.2 Refineries

Different types of refineries are as follows:

Lube oil Refineries

Fuel oil Refineries

Petroleum to Petrochemical Refineries

A refinery breaks down crude oil into its various components (petroleum products). These components are then selectively changed into new products.

Refinery has always been very alluring for Chemical Engineers. There is a lot to

become skilled at in refineries for Chemical Engineers. It has an assortment of

Unit Operations and Processes. So, as Chemical Engineers we are inclined

towards a refinery project. In an interview with James Murphy (Process Design

Engineer for the Richmond Refinery) he advised students and I quote:

13

I would advise any student studying Chemical Engineering that Refinery is definitely worth it. It's a fun, exciting field. It challenges you in your problem

solving, it allows you to be creative and come up with creative solutions to

problems. Chemical engineers are used very heavily in the refining industry [1]

1.3 List of Refineries in Pakistan

Pak-Arab Refinery Ltd. (100,000 bbl/d)

National Refinery Ltd. (64,000 bbl/d)

Attock Refinery Ltd. (46,000 bbl/d)

Byco Petroleum Pakistan Ltd. (150,000 bbl/d)

Pakistan Refinery Ltd. (50,000 bbl/d)

Enar Petroleum Refining Facility (3,000 bbl/d)

Indus Oil Refinery Ltd. (100,000 bbl/d) (not yet operational)

1.4 Properties and uses of Product

LAB is a family of organic compounds with the formula C6H5CnH2n+1.

Typically, n lies between 10 and 16, although generally supplied as a tighter cut,

such as C12-C15, C12-C13 and C10-C13, for detergent use. The CnH2n+1 chain are un-

branched. They are mainly produced as intermediate in the production

of surfactants, for use in detergent. Since the 1960s, LABs have emerged as the

14

dominant precursor of biodegradable detergents. It exhibits flammable and

non-toxic properties.

Following are some different areas and products where LAB is utilized:

In Detergent Industry

In Households and Cleaning Products

To remove stains and oil

Can resist static electricity

In Hair Care products

Raw material in Foaming

15

Chapter 2

Process Description

2.1 Brief Overview of Process

Starting with Crude Oil, it is transformed into its fractions from there on higher

carbon chains in Kerosene are estranged as they are requisite for LAB

production. Carbon chains then go through two reactors to remove most of the

impurities. In the end with the help of Gas Separator impurities are estranged.

Preferred Carbon chains are then sent to Molex Unit. After Molex Unit it goes into

Alkylation Unit from where we attain LAB. We are restricting our project till the

production of n-Paraffins. To design all the process in such a short period is not

an achievable goal.

2.2 Raw Material

Primary raw material used is Crude Oil and secondary raw materials used are

Kerosene and Hydrogen. Crude Oil is a fossil fuel and mixture of naturally

occurring hydrocarbons. It is refined through distillation and many other

processes on the basis of difference in their boiling points into

Diesel

Gasoline

16

KEROSENE (Secondary Raw Material)

Heating oil

Jet fuel

Compounds found in crude oil are composed of hydrogen and carbon. In

addition to hydrocarbons, small amounts of sulfur, oxygen, nitrogen and

some metallic compounds are also present.

NOTE: Composition of crude oil varies according to region from where it is

being extracted.

2.3 Properties [2]

Specific Heat = 0.480 Btu/lbF

Viscosity = 310 lb/ft.s

Temperature = 640F [3]

Degree API = 38.6

2.4 Overall Process

Our overall process includes the following units:

Atmospheric Distillation Unit

N-paraffin Production Unit

17

Molex Unit

Alkylation Unit

We will be working on the following units as to cover the whole production unit

was beyond our ranger and also there is not enough time.

Atmospheric Distillation Unit

N-paraffin Production Unit

In atmospheric distillation unit we get fractions at different boiling points as

crude oil is separated into its fractions and from there on undesired fractions are

cooled down and sent to further treating units whereas desired carbon chain

from kerosene goes further to N-paraffin production unit where it is treated to

give us required chain of N-paraffin to be utilized in the production of Linear

Alkyl Benzene.

18

Chapter 3

Process Diagrams

3.1 Input/ Output Diagram

Figure 3.1a

19

3.2 Functional Diagram

3.3 Operational Diagram

Figure 3.2a

Figure 3.3a

20

3.4 Process Flow Diagram

Figure 3.4a

21

Chapter 4

Material and Energy Balance

4.1 Material and Energy balance over equipments

Material and energy balances are fundamental to many engineering

disciplines and have a major role in decisions related to sustainable

development. Material and energy balances are very important in an industry.

Material balances are fundamental to the control of processing, particularly in

the control of yields of the products. The first material balances are determined

in the exploratory stages of a new process, improved during pilot plant

experiments when the process is being planned and tested, checked out when

the plant is commissioned and then refined and maintained as a control

instrument as production continues. When any changes occur in the process,

the material balance needs to be determined again.

The increasing cost of energy has caused the industries to examine means of

reducing energy consumption in processing. Energy balances are used in the

examination of the various stages of a process, over the whole process and

even extending over the total production system from the raw material to the

finished product.

22

The law of conservation of mass leads to what is called a mass or a material

balance.

Mass In = Mass Out + Mass Stored

The energy coming into a unit operation can be balanced with the energy

coming out and the energy stored.

Energy In = Energy Out + Energy Stored

In order to determine the energy involved in terms of heat following formula is

considered and applied:

Q = m*Cp*T

Material and Energy balance over different equipments used throughout the

designing in project are explained as follows:

Figure 4.1a

23

Heat Exchanger-1 (HE-1)

24


25


26


27

Furnace-1 (F-1)

28

Atmospheric Distillation Column-1 (ADC-1)

29

Stripper-1 (ST-1)

30

Stripper-2 (ST-2)

31

Fractionating Column-1 (FC-1)

32

Fractionating Column-2 (FC-2)

33

Mixer-1 (MX-1)

34


35


36

Plug Flow Reactor-1 (PFR-1)

37


38

Plug Flow Reactor-2 (PFR-2)

39


40

Gas Seperator-1 (GS-1)

41

Chapter 5

Equipment Design

5.1 Plug Flow Reactor (PFR-1) Design

The plug flow reactor (PFR, sometimes called continuous tubular reactor CTR,

or piston flow reactors) is a model used to describe chemical reactions in

continuous, flowing systems of cylindrical geometry. The PFR model is used to

predict the behavior of chemical reactors of such design, so that key reactor

variables, such as the dimensions of the reactor, can be estimated.

A tubular reactor is a vessel through which flow is continuous, usually at steady

state, and configured so that conversion of the chemicals and other dependent

variables are functions of position within the reactor rather than of time. In the

ideal tubular reactor, the fluids flow as if they were solid plugs or pistons, and

reaction time is the same for all flowing material at any given tube cross section.

Tubular reactors resemble batch reactors in providing initially high driving forces,

which diminish as the reactions progress down the tubes. On the coming page

a general schematic diagram represents a tubular reactor in which along the

length concentration changes:

42

(Schematic diagram of an ideal plug flow reactor)

Characteristic of an ideal plug flow:

Perfect mixing in the radial direction (Uniform cross-section concentration)

No mixing in the axial direction or segregated flow.

Flow in tubular reactors can be laminar, as with viscous fluids in small-diameter

tubes, and greatly deviate from ideal plug-flow behavior, or turbulent, as with

gases. Turbulent flow generally is preferred to laminar flow, because mixing and

heat transfer are improved. For slow reactions and especially in small laboratory

and pilot-plant reactors, establishing turbulent flow can result in inconveniently

long reactors or may require unacceptably high feed rates.

Catalytic hydrogenation is done in a tubular plug-flow reactor (PFR) packed

with supported catalyst. The pressures and temperatures are typically high,

although this depends on the catalyst.

This is the reason we chose tubular plug-flow reactor and the catalyst used is

Nickel (Ni)

Figure 5.1a

43

Reaction

C4H4S + 3H2 C4H8 + H2S

Rate Equation [4] = = Where;

r = Rate of Reaction

k = Rate Constant

CT = Concentration of Thiophene

CH = Concentration of Hydrogen

Rate Constant

Using Arrhenius Equation to calculate rate constant = Assume Frequency Factor A= 1 Assume Internal Energy E= 17000 J/mol [5] Ideal Gas Constant R= 8.31 J/K.mol Temperature = 513 K = . = . . Concentrations

Concentration of Hydrogen= CH = 0.0009

44

Concentration of Thiophene= CT = 0.77 Type of Catalyst

Catalyst used is Palladium Sulfide (PdS), as it is a very commonly used catalyst to

carry out hydrogenation reactions. Some physical properties are:

Bulk density of Catalyst= c = 56.18 Bed Void Fraction= = 0.55 Particle Diameter= DP = 0.0196 ft

Weight of Catalyst [6] = [+ ] Where,

Reactant Flow rate= F = 1.238

Rate Constant= K1 = 0.0186 .

Reactant Concentration= = 0 .77 Fractional Volume Change= = 1

Conversion= XA = 0.66

= . . . [ + . + . ] = . Catalyst Volume [20]

45

= = . . = . Volume of Reactor [21]

Reactor Volume is calculated using the following formula: = = . . = . Space Time [22]

Space Time is calculated using the following formula: = Where;

Space Time= Volume of Reactor= = 9.62 ft3 Volumetric Flow Rate of Reacting Mixture= = 29088.7 = . . = .

Reactor Geometry

In reactor geometry, we discuss necessary parameters regarding shell and tube

side design;

Tube Side Calculations

Let us assume some parameters to design tubes for plug flow;

46

Length of Tube= Lt = 9 ft

Tube outside Diameter= do = 0.17 ft

Tube inside Diameter= di = 0.13 ft

Now, calculating Total Number of Tubes Nt [7] = . . = . . = As we know that most efficient way of arranging tubes is triangular pitch

arrangement so we use this arrangement to carry on with our calculations: = . = . Pressure Drop

To calculate pressure drop [7] for tube side we use Eurgen equation; = [ ] [ ] [ + . ] Where;

Bed Void Fraction= = 0.55

Particle Diameter= DP = 0.054 ft

Feed Density = f = 0.032 Viscosity of Feed = = 0.000021 . Length = Lt = 9 ft

47

gc = 32.17 = . . = . = .

= . Now Calculating, Superficial Mass Velocity as follows;

, = = . . , = . . Putting all the above values in Eurgen equation to calculate pressure drop; = [ ] [ ] [ + . ] = [ . . ] [ . . . . ] [ . . . + . . ] = . Material of Construction

The reactor tubes are suggested to be of stainless steel so that any kind of

corrosion is avoided.

Shell Side Calculations

Calculating Shell Side inside diameter:

48

= [ + ] Where,

ND= Number of tubes at bundle diameter

= [ ] = [ ] = .

Now, Calculating Shell Side inside diameter = [ + ] = . [. + ] = . Shell Height

As assumed above;


To calculate Shell height we leave 20% space above and below. So; = . + = . Pressure Drop

Water is flowing through the shell side as it is used as Cooling Media.

Heat duty= Q = 546281.24

Specific Heat Capacity of Water= Cp = 0.071 .K

49

Temperature difference= T = 20K Water Required; = . = .

= . . =

Mass Flow Rate= mw = 4231.75

Shell Side Flow Area; = [ ] Where;

Shell Inside Diameter= Di = 2.41 ft

Total Number of tubes= Nt = 80

Tube outside Diameter= do = 0.17 ft = [ ] = [. . ] = . Calculating Equivalent Diameter [7];

50

= [ [ ] ] = [ [ . . ] . . ] = 3.14 ft

Calculating Shell Side Mass Velocity;

= = . . = . . Viscosity of Water= 0.00059

. Calculating Reynolds Number;

= = . . . =

= + . Where;

Pressure drop= PS

51

Shell Side Mass Velocity= Gs = 1544.4 .


Baffle Spacing= B = 1.3 ft

Friction Factor for Tube Side= fs = 0.0015

Number of Crosses= (N+1) = = . = 83 Equivalent Diameter= De = 3.14 ft

Shell Inside Diameter= Di = 2.41 ft

Specific Gravity= s = 0.998 = 1 = . . . . . .

= . (Negligible) Shell Thickness

Shell thickness is calculated using the following relationship:

= + Where,

tp = Design thickness of shell

f = Design stress = 2880000 for carbon steel

52

Di = Shell diameter = 2.41 ft

P = Maximum allowable pressure = 5079

C = Corrosion allowance = 0.0105 ft under sever conditions

Substituting the values into equation gives;

= + = . + . = . Material of Construction

For the reactor shell, proposed material of construction is carbon steel as it is

cheap and compatible.

Heads for Reactor Shell [8]

Most commonly used heads are Standard torispherical for pressure up to 15bar.

Thus torispherical heads has been designed for the reactor. Material of

construction is plain carbon steel.

Specification Sheet

Fixed Bed Multi-Tubular Reactor (PFR-1)

Volume of Reactor = 9.62 ft3

Space Time = 1.19 sec

53

Shell Side

Heat Duty = 546281.24

Material Flow Rate = 4231.75

Shell Inside Diameter = 2.25 ft

Height of Shell = 12.6 ft

Flow Area = 2.40 ft2

Shell Thickness = 0.0124 ft

Pressure Drop = 0.00036 psi

Temperature = 493 K

Tube Side

Material Flow Rate = 0.381

Length = 9 ft

Inside Diameter = 0.13 ft

Outside Diameter = 0.17 ft

No. of Tubes = 80

Pitch = Triangular

Temperature = 513 K

Catalyst

Weight = 243.5 lb.cat

Volume = 4.33 ft3

Bed Void Fraction= 0.33

Particle Diameter= 0.0196 ft

5.2 Atmospheric Distillation Unit (ADU) Design

Distillation is a process of separating the component substances from a liquid

mixture by selective evaporation and condensation. Distillation may result in

essentially complete separation (nearly pure components), or it may be a

partial separation that increases the concentration of selected components of

the mixture. In either case the process exploits differences in the volatility of

mixture's components. In industrial chemistry, distillation is a unit operation of

54

practically universal importance, but it is a physical separation process and not

a chemical reaction.

Distillation Train

It is a sequence of two or more columns to desirably split streams into specified

composition.

Types

Direct sequence

Indirect sequence

Figure 5.2a

55

Sequence for desired distillation is selected on the basis of some classifying rules.

Rule of thumb for Distillation Sequence

Remove thermally unstable, chemically corrosive, or chemically reactive

components early in the sequence.

Remove final products one-by-one as distillates (the direct sequence).

Separate early in the sequence, those components of greater molar

percentage parentage in the feed.

Figure 5.2b

56

Sequence separation points in the order of decreasing relative volatility so

that the most difficult splits are made in the absence of other

components.

Sequence separation points to leave last those separations that give the

highest purity products.

Sequence separation points that favor near equimolar amounts of

distillates and bottoms in each column.

Selected Sequence

On the basis of thumb rules, following sequence is selected for the separation of

kerosene among crude oil.

Indirect Sequence in Process

Figure 5.2c

57

Available Data [9]

Xi,f Xi,d K

C1 0.002302 0.002326 549

C2 0.018419 0.018606 527

C2= 0.020722 0.020931 523

C3 0.07598 0.076748 260

C4 0.08519 0.086051 175

C5 0.004605 0.004651 102

C5= 0.001151 0.001163 101.3

C6 0.010361 0.010466 68

iC6 0.008059 0.00814 67.3

n-C7 0.02145 0.0214 51

i-C7 0.013673 0.0136 50.7

n-C8 0.014401 0.0143 34

n-C9 0.019917 0.0199 26.06667

n-C10 0.029694 0.0296 19.83333

i-C10 0.010948 0.0109 19.66333

n-C11 0.013837 0.0137 13.03333

C-11= 0.01325 0.0132 12.86333

i-C11 0.004182 0.004 12.46667

n-C12 0.017313 0.012 10.2

n-C13 (H.K) 0.01202 0.0119

7.026667

58

n-C14 0.043232 0.0431 6.233333

n-C15 0.034545 0.0345 4.533333

i-C15

(L.K) 0.021414 0.0214 4.363333

C16 0.046869 0.0468 3.343333

C17 0.033636 0.033976 2.096667

C18 0.027374 0.02765 1.87

C19 0.028889 0.029181 1.53

C20 0.013131 0.013264 1.133333

C21 0.017071 0.017243 1.02

C22= 0.012323 0.012448 0.793333

C23 0.030505 0.030813 0.566667

C23= 0.018788 0.018978 0.555333

C24 0.048485

0.51

C25 0.067879

0.436333

C26 0.04202

0.357

C27 0.019394

0.226667

C28 0.022626

0.187

C29 0.025859

0.147333

C30 0.032323

0.130333

C31 0.006465

0.113333

Column-1

Calculation of Number of Plates [10]

59

Calculating minimum number of plates using Fenskees equation:

Nmin = 2.59

Ideal Number of Plates from graph = 3

Calculating minimum reflux ratio using Colburns equation [10]:

Rmin = 0.99

Net Area [11]

An = mv/un

Where

mv= Vap flow rate(ft3/s) = 1.87 ft3/s

un= Actual vapor velocity(ft./s) = 0.2182 ft3/s

An = 2.179 ft2

Column Area

Down comer area = 15% * Cross Sectional Area

nH

dHAB

nL

dL

AB XX

XXR )1(

1min

LK

bLK

HK

dHK

LK

m

XX

XX

N lnln

60

Ac = 2.394 ft2

Diameter of column

Ac = (pi/4)*(Dc)2

Dc = 1.74 ft

Downcomer Area

Ad = 0.15*Ac

Ad = 0.2155 ft2

Active Area [10]

Aa = Ac-2*Ad

Aa = 1.963 ft2

Hole Area [11]

Ah = (Ah / Aa) * Aa

Ah/Aa =0.1

Ah = 0.1374 ft2

Specification Sheet

Column-1

Sequence Indirect

61

Column temperature 673.5 F

Column pressure 4 psi

Column diameter 1.74 ft

Number of plates (minimum) 2.59

Ideal number of plates 3.01

Type of column Tray

Tray type Sieve

Tray spacing 0.5

Active Area 1.96 ft2

Hole Area 0.137 ft2

Material of construction Carbon steel

Column-2

Calculation of Number of Plates

62


Nmin = 13.8

Ideal Number of Plates from graph = 15.3

Calculating minimum reflux ratio using Colburns equation:

Rmin = 0.5

Net Area

An = mv/un

Where



An = 3.302 ft2

Column Area


Ac = 3.71 ft2

nH

dHAB

nL

dL

AB XX

XXR )1(

1min

LK

bLK

HK

dHK

LK

m

XX

XX

N lnln

63

Diameter of column

Ac = (pi/4)*(Dc)2

Dc = 2.086 ft

Downcomer Area

Ad = 0.15*Ac

Ad = 0.3339 ft2

Active Area

Aa = Ac-2*Ad

Aa = 3.04 ft2

Hole Area

Ah = (Ah / Aa) * Aa

Ah/Aa =0.1

Ah = 0.2129 ft2

Specification Sheet

Column-2

Sequence Indirect

Column temperature 630 F

64

Column pressure 5 psi

Column dia 2.08 ft

Number of plates (minimum) 13.8


Type of column Tray

Tray type Sieve

Tray spacing 0.5


Hole Area 0.21 ft2


Column-3

Calculation of Number of Plates


65

Nmin = 3

Ideal Number of Plates from graph = 4.1

Calculating minimum reflux ratio using Colburns equation:

Rmin = 0.45

Net Area

An = mv/un

Where



An = 2.233 ft2

Column Area


Ac = 2.627 ft2

Diameter of column

nH

dHAB

nL

dL

AB XX

XXR )1(

1min

LK

bLK

HK

dHK

LK

m

XX

XX

N lnln

66

Ac = (pi/4)*(Dc)2

Dc = 1.755 ft

Downcomer Area

Ad = 0.15*Ac

Ad = 0.236 ft2

Active Area

Aa = Ac-2*Ad

Aa = 2.15 ft2

Hole Area

Ah = (Ah / Aa) * Aa

Ah/Aa =0.1

Ah = 0.1508 ft2

Specification Sheet

Column-3

Sequence Indirect

Column temperature 540 F

Column pressure 5.7 psi

67

Column dia 1.75 ft

Number of plates (minimum) 3


Type of column tray

Tray type sieve

Tray spacing 0.5


Hole Area 0.15 ft2


5.3 Heat Exchanger (HE-2) Design

A heat exchanger is a piece of equipment built for efficient heat transfer from

one medium to another. The media may be separated by a solid wall to

prevent mixing or they may be in direct contact.[1] They are widely used

in space heating, refrigeration, air conditioning, power plants, chemical

68

plants, petrochemical plants, petroleum refineries, natural gas processing,

and sewage treatment.

Heat transfer is perhaps the most important as well as most applied process in

chemical and petrochemical plants. The economics of plant operation often

are controlled by the effectiveness of the utilization and recovery of heat .The

word exchanger applied to all type of equipment in which heat is exchange but

is often specifically to denote equipment in which heat is exchange between

two process streams. A heat exchanger is a piece of equipment that continually

transfers heat from one medium to another, without mixing the process fluids.

Classification of Heat Exchanger

In general, industrial heat exchangers are classified according to their:

Transfer processes

Degrees of surface compactness

Flow arrangements

Pass arrangements

Phase of the process fluid

Heat transfer mechanism

Types of Heat Exchanger:

The major types of heat exchangers that are used industrially are:

Double pipe

69

Shell and tube

Spiral type

Plate and frame

Compact heat exchanger

Types of Shell & Tube Heat Exchanger

Fixed tube

U tube

Floating head

Advantages of Shell and Tube Exchanger:

It is used for high heat transfer duties.

It can be used in systems with higher operating temperatures and

pressures.

Shell and tube heat exchangers are ideal for applications with extremely

high flow rates.

Its configuration gives large surface area in small volume.

Its cleaning and repairing (maintenance) is straight forward.

It is used for high heat transfer duties.

Its compactness is more.

70

It can be fabricated with wide variety of material depends upon fluid

properties.

Applications of Heat Exchangers:

Heat exchangers are commonly used in a wide variety of industrial, chemical,

and electronics processes to transfer energy and provide required heating or

cooling. Automotive radiators are a common example. Heat from the hot

engine water is pumped through the radiator, while air is blown through the

radiator tins. The hot engine water's heat energy is transferred to the air, thus

keeping the water at the right temperature, to keep the engine from

overheating. Essentially automotive radiators are liquid-to-air heat exchangers.

Heat exchangers occur naturally in the circulation system of whales. Arteries to

the skin carrying warm blood are intertwined with veins from the skin carrying

cold blood causing the warm arterial blood to exchange heat with the cold

venous blood.

Heat Duty

Q= m*Cp*T

= (11800 lb/hr) x (0.65 Btu/lb. oF) x (380 oF 350oF )

= 230159Btu/hr

= 2.30159*10^5 Btu/hr

LMTD [12]

71

45.13335017.137380ln

45.13335017.137380LMTD

= 222.29oF

064.812

12

tt

TTR

015.011

12

tTttS

Ft [23]

1-2 exchanger: Ft (possible)

The four 1-2 exchangers in series are more adequate for heat transfer.

Tm = (.97) x (222) =229 oF

tc = 137.4 - 133.4 = 3.72 oF

th = 380 - 350 = 30 oF

tc/th = 0.124 Kc = 0.344

Fc = 0.21

Tc = T2 + Fc (T1-T2) = 360.5 oF

Tc = t1+Fc (t2-t1) = 134.29 oF

Tube Specifications [24]

72

Length = 6 ft

OD, BWG, pitch = 3/4in, 16 BWG, 1in Square pitch

Passes = 2

Outside surface area per linear ft. = a = 0.1963 ft2

Flow area of tube, at = 0.302 in2

Ud = 32 (for dirt factor of .003 and allowable pressure drop 5 to 10 psi)

Estimation of Heat Transfer Area [25]

A = Q/ Ud *Tm = 32.13 No. of tubes = Nt = A/ a*L = 28 (for 1 exchanger)

Nearest Count =Nt = 32

Shell ID = 8 1/2 in

Baffle spacing = 5 in

New Area = (outside surface area/linear foot x no. of tubes x tube length)

= (.1963 x 32 x 6)

= 37.68 ft2 (For One Heat Exchanger)

Hot Fluid (Tube Side) [26]

= 1+2/2=365 302.0ba in2

n

aNta tt

144

73

= 0.334 ft2

at

WGt

=3616411 lb/hr.ft2

Tc = 360.5 oF

= 8.712 lb/ft.hr

Re = DGt/

= 0.0156*3616411/8.712 =21249

Jh = 80

For = 0.23 cp and 70 o API

K*(C/k)1/3 = 0.398

s = 1

hi = 616.49 Btu/hr.ft2 oF

h io = ho x ID/OD

= 616.49 x 0.012

=509.44 Btu/hr.ft2 oF

Cold Fluid (Shell Side)

t

s RBCID

a

144

3/1)( kCpe

h

s

o

DkJh

74

1144

6.11875..8sa = 0.333 ft2

Gs = W/as

= 11800/0.333 = 354000 lb/hr.ft2

At tc = 421oF

= 0.23 lb/ft.hr

DGt/ De

23.03540000458..0Re = 29150.2

jH = 98

Cp = 0.69 Btu/lb oF

3/1

k

CDekjHho

= 363.49 Btu/hr.ft2 oF

Clean overall coefficient for preheating Uc [26]

Uc = (hio * h o)/( hio + ho)

= (509.44 x 363.49) / (509.4+363)

= 212.2 ft2 oF Btu/hr

Rd = Uc Ud / Uc * Ud

Rd = 0.00312 hr.ft2.oF/Btu

Pressure Drop [12]

75

Tube side

Re = 21429.39

f = 0.00024 ft2/m2

Specific gravity = 0.7

t

ntt DeS

LfGP 10

2

1022.5

= 9.34 psi

Shell Side

Re = 29150.4

De =0.62 in= 0.0516

f = 0.0010

No. of crosses = N + 1 =12 Lp/B

= 6*12/5

D=8/12= 0.666 ft

= 0.44 Psi

Specification Sheet

Heat Exchanger (HE-2)

Area 32.17ft2

76

Diameter of shell 8 in

Number of Tubes 32

Type of tube Plain

Tube length 6 ft


Clean Overall Heat Transfer Co-efficient 212.4 Btu/(hr)(ft2)( F)

Design Overall Heat Transfer Co-efficient 27.43 Btu/(hr)(ft2)( F)

Dirt factor 0.031(hr)(ft2)( F)/Btu

Pressure drop shell side 0.446psi

Pressure drop tube side 9.43 psi

5.4 Fractionating Column (FC-1) Design

A fractionating column is an essential item used in distillation of liquid mixtures so

as to separate the mixture into its component parts, or fractions, based on the

differences in volatilities. Fractionating columns are used in small scale

laboratory distillations as well as for large-scale industrial distillations.

77

Simple distillation can be used to separate components of a mixtures that have

large difference in their boiling point. If two components have a boiling point

difference of less than 40-50C, simple distillation will not be successful at

separating them. In this case fractional distillation is used.

(Chemical engineering schematic of a continuous fractionating column)

Fractional distillation is one of the unit operations of chemical engineering.

Fractionating columns are widely used in the chemical process industries where

large quantities of liquids have to be distilled. Such industries are the petroleum

processing, petrochemical production, natural gas processing, coal tar

Figure 5.4a

78

processing, brewing, liquefied air separation, and hydrocarbon solvents

production and similar industries but it finds its widest application in petroleum

refineries. In such refineries, the crude oil feedstock is a complex, multi-

component mixture that must be separated, and yields of pure chemical

compounds are not expected, only groups of compounds within a relatively

small range of boiling points, also called fractions. That is the origin of the name

fractional distillation or fractionation. It is often not worthwhile separating the

components in these fractions any further based on product requirements and

economics.

In our project, kerosene ranging from C7 to C18 is sent into the fractionating

column-1 for further separation and the Bottom Product we obtained from here

is our desired range of kerosene C12 to C16.This range is then further sent for the

treatment. As importance of this equipment is high in the process, so, that is the

reason why we selected this equipment as well for designing.

Available Data

Temperature and flow rate ranges of feed, bottom and top product are given

below:

Feed composition is given below [9]:

FEED TOP BOTTOM

TEMPERATURE (oF) 176.66 335 350

FLOW RATES

(lbmol/hr) 11800 7540 4259

FEED

Mass Flow

(lb/hr) Composition

n-C7 354 0.03

i-C7 118 0.01

79

Calculation for top product

TP Cmpstn Press (psi)

Vap Press [19]

(335F)

k

(335F)

x (dew

pt)(335F)

n-C7 0.03 14.7 88.1 5.99 0.01

i-C7 0.01 14.7 84.3 5.73 0.00

n-C8 0.04 14.7 43.7 2.97 0.01

n-C9 0.097 14.7 25.4 1.73 0.06

n-C10 0.18 14.7 15.5 1.05 0.17

i-C10 0.04 14.7 14.9 1.01 0.04

n-C11 0.12 14.7 6.5 0.44 0.27

i-C11 0.03 14.7 5.7 0.39 0.08

n-C12 0.09 14.7 3.5 0.24 0.38

C4H4S 0.002 14.7 2.9 0.20 0.01

1.02

Calculation for bottom product

BP Cmpstn Press (psi)

Vap Press

(600F)

k

(600F) y (bbl pt)

C12= 0.018 14.7 95 6.46 0.12

n-C13 0.08 14.7 61 4.15 0.33

n-C14 0.09 14.7 52 3.54 0.32

n-C15 0.03 14.7 33.5 2.28 0.07

i-C15 0.004 14.7 32 2.18 0.01

n-C8 472 0.04

n-C9 1144.6 0.097

n-C10 2124 0.18

i-C10 472 0.04

n-C11 1416 0.12

i-C11 354 0.03

n-C12 1062 0.09

C12= 212.4 0.018

n-C13 944 0.08

n-C14 1062 0.09

n-C15 354 0.03

i-C15 47.2 0.004

n-C16 1180 0.1

n-C17 247.8 0.021

n-C18 129.8 0.011

C4H4S 106.2 0.009

80

n-C16 0.1 14.7 24 1.63 0.16

n-C17 0.021 14.7 19 1.29 0.03

n-C18 0.011 14.7 14 0.95 0.01

C4H4S 0.007 14.7 3.3 0.22 0.00

1.05

Calculation for feed boiling point temperature

FEED Cmpstn Press (psi)

Vap Press

(350F)

k

(350F) y (bbl pt)

n-C7 0.03 14.7 100 6.80 0.20

i-C7 0.01 14.7 99.3 6.76 0.07

n-C8 0.04 14.7 48 3.27 0.13

n-C9 0.097 14.7 29 1.97 0.19

n-C10 0.18 14.7 17 1.16 0.21

i-C10 0.04 14.7 16.4 1.12 0.04

n-C11 0.12 14.7 8.7 0.59 0.07

i-C11 0.03 14.7 8.4 0.57 0.02

n-C12 0.09 14.7 5.3 0.36 0.03

C12= 0.018 14.7 4.9 0.33 0.01

n-C13 0.08 14.7 3.1 0.21 0.02

n-C14 0.09 14.7 2 0.14 0.01

n-C15 0.03 14.7 1.4 0.10 0.00

i-C15 0.004 14.7 1.1 0.07 0.00

n-C16 0.1 14.7 0.7 0.05 0.00

n-C17 0.021 14.7 0.5 0.03 0.00

n-C18 0.011 14.7 0.31 0.02 0.00

C4H4S 0.009 14.7 0.04 0.00 0.00

1.01

Pressure and relative volatilities [10]

At Top P=14.7 Psia

Therefore, LK= K1/K2=1.64

At Bottom P=14.7 Psia

Therefore, HK= K1/K2=1.005

81

Calculation of Number of Plates [10]

Calculating minimum number of plates using Fenskees Equation

Minimum Number of Plates= Nm = 5

Ideal number of plates from graph = 12

Minimum reflux ratio [11]

ixi,f/i- = 0 = 0.97

ixi,d/i- = Rm+1 Rm= 2.56

Net Area

An = mv/un

Where



An = 1.17 ft2

LK

bLK

HK

dHK

LK

m

XX

XX

N lnln

82

Column Area


Ac = 3.627 ft2

Diameter of column

Ac = (pi/4)*(Dc)2

Dc = 1.317 ft

Downcomer Area

Ad = 0.15*Ac

Ad = 0.10 ft2

Active Area

Aa = Ac-2*Ad

Aa = 0.98 ft2

Hole Area

Ah = (Ah / Aa) * Aa

Ah/Aa =0.1

Ah = 0.18 ft2

Height of Column

83

Total Height = ((no. of trays -1) Tray spacing) + (no. of trays width of tray +

(0.25diameter) + 1

Total Height = 11.31 ft

Specification Sheet

Fractionating Column (FC-1)

Column Diameter (ft) 1.317

Number of Trays (Nm) 5

Number of Trays (N) (incl. Reboiler) 12

Reflux Ratio 2.56

Operating Pressure (psi) 14.7

Column Height (ft) 11.31

Tray Type Sieve

Tray Spacing (ft) 0.7

Total Net Area (ft2) 1.17

Active Area (ft2) 0.98

Hole Area (ft2) 0.18

Downcomer Area (ft2) 0.10

Material of Construction Carbon Steel

84

Chapter 6

Instrumentation and Process Control

6.1 Introduction

Control in process industries refers to the regulation of all aspects of the process.

Precise control of level, temperature, pressure and flow is important in many

process applications. This module introduces you to control in process industries,

explains why control is important, and identifies different ways in which precise

control is ensured. The following five sections are included in this module:

The importance of process control

Control theory basics

Components of control loops and ISA symbology

Controller algorithms and tuning

Process control systems

6.2 The Importance of Process Control

Refining, combining, handling, and otherwise manipulating fluids to profitably

produce end products can be a precise, demanding, and potentially

hazardous process. Small changes in a process can have a large impact on the

end result. Variations in proportions, temperature, flow, turbulence, and many

85

other factors must be carefully and consistently controlled to produce the

desired end product with a minimum of raw materials and energy. Process

control technology is the tool that enables manufacturers to keep their

operations running within specified limits and to set more precise limits to

maximize profitability, ensure quality and safety.

6.3 Learning objectives

Learning objective involves to,

Define process

Define process control

Describe the importance of process control in terms of variability,

efficiency and safety

6.4 Process control

Process control refers to the methods that are used to control process variables

when manufacturing a product. For example, factors such as the proportion of

one ingredient to another, the temperature of the materials, how well the

ingredients are mixed, and the pressure under which the materials are held can

significantly impact the quality of an end product. Manufacturers control the

production process for three reasons:

Reduce variability

Increase efficiency

86

Ensure safety

6.5 Process variables

A process variable is a condition of the process fluid (a liquid or gas) that can

change the manufacturing process in some way. Common process variables

include:

Pressure

Flow

Level

Temperature

Density

pH (acidity or alkalinity)

Liquid interface (the relative amounts of different liquids that are

combined in a vessel)

Mass

Conductivity

6.6 Objectives

Define control loop

Describe the three tasks necessary for process control to occur:

Measure Compare

87

Adjust Define the following terms:

Process variable Set point Manipulated variable Measured variable Error o Offset Load disturbance Control algorithm

6.7 Process Control over Fractionating Column-1 (FC-1) [13]

Figure 6.7a

88

In the above diagram two different type of control schemes are illustrated

which are:

Cascade Control

Feedback Control

6.8 Cascade Control

In cascade control, we have one manipulated variable and more than one

measurement. Cascade Control Systems contain integrated sets of control

loops:

Primary Loop: Monitors the control variable and uses deviation from its set

point to provide an output to the secondary loop

Secondary Loop: Receives its set point from the primary loop and controls

the reference variable accordingly. In this configuration:

In the picture mentioned above we have two Feedback controllers but only a

single control valve. Cascade control is employed to regulate the temperature

at the top of distillation column and the secondary loop is used to compensate

for changes in flow rate. Two different types of controllers are used in the above

mentioned Cascade control:

PI controller is used to control the flow

PID controller is used to control the temperature

6.9 Feedback Control

89

In Feedback control information from measurements are used to manipulate a

variable to achieve the desired result. Feedback control takes control action

after the influence of disturbances on the process. In the picture mentioned

above we have a Feedback controller in which composition is analyzed and

then accordingly flow rate of the steam is manipulated.

PI controller is used

90

Chapter 7

Cost Estimation

7.1 Equipment Costs

Plug Flow Reactor

Material of Construction: Carbon Steel

Purchased cost (2004) [14]: ost @ = Where, ost @ = Cost of equipment at 2004 (for carbon steel grade A515 material of construction).

C = cost constant ($) = 15000$

S = size of equipment (m3) = 0.231 m3 ,

n = index value = 0.4

ost @ = $8347 Present Cost (2015):

ost @ = (index @ index @ ) ost @ index @ = 463 [15]

91

index @ = 1024 [15] ost @ for reactor = $ ost @ for reactors = $

Heat Exchanger

Shell: Carbon steel

Tubes: Carbon Steel

Purchased cost (2004):

According to graph [16] for

Area = 3.5 m2

Pressure = 1.01 bar

Purchase Cost @ 2004 = Bare Cost * Type factor * Pressure factor

= $63000 (0.8) (1.0) = $50400

Present Cost (2015):

Index @ 2004 = 463

Index @ 2015 = 1024

ost = index index ost @

92

ost = ost @ for . E = $ ost @ for . E = $

Atmospheric Distillation Column

Shell: Carbon Steel

Plates: Stainless Steel 410


Vessel purchase cost according to graph [17] for

Vessel Height = 8.37 m

Vessel Diameter = 1.69 m

Purchase Cost @ 2004 = Bare Cost * Material factor * Pressure factor

= $10100 (1.0) (1.1) = $11110

Cost per plate [18]

$900* 1.7 = $1530

22 plates = 1530 *22 = $ 33660

Total cost of column @ 2004 = 11110 + 33660 = $ 44770

93


Index @ 2004 = 463

Index @ 2015 = 1024

ost = index index ost @ ost = ost @ for . D. = $

Fractionating Column

Shell: Carbon Steel

Plates: Stainless Steel 410


Vessel purchase cost according to graph [17] for

Vessel Height = 3.44 m

Vessel Diameter = 0.3991 m

Purchase Cost @ 2004 = Bare Cost * Material factor * Pressure factor

= $5100 (1.0) (1.0) = $5100

Cost per plate [18]

94

$1000* 1.7 = $1700

12 plates = 1700 *12 = $ 20400

Total cost of column @ 2004 = 5100 + 20400= $ 25500


Index @ 2004 = 463

Index @ 2015 = 1024

ost = index index ost @ ost = ost @ for . = $

ost @ for . = $ Centrifugal Pump

Material of Construction: Stainless Steel 316

Purchase Cost @ 2004 = $5000

Index @ 2004 = 463

Index @ 2015 = 1024

95

ost = index index ost @ ost = ost @ for ump = $

ost @ for ump = $ Mixer

Material of Construction: Carbon Steel


Purchase Cost of Tank @ 2004 = $996

Purchase Cost of Propeller @ 2004 = $319

Total cost of Mixer @ 2004 = 996 + 319= $ 1315


Index @ 2004 = 463

Index @ 2015 = 1024

ost = index index ost @ ost =

96

ost @ for ixer = $ Gas Separator

Purchase Cost @ 2004 = $10,800

Index @ 2004 = 463

Index @ 2015 = 1024

ost = index index ost @ ost = ost @ for . = $

7.2 Estimation of Project Cost

Equipment

No. of equipments

Cost ($)

Plug Flow Reactor 2 36921

Heat Exchanger 8 891742

Atmospheric Distillation

Column

1 99016

Fractionating Column 2 112794

97

Centrifugal Pump 14 154812

Mixer 1 2908

Gas Seperator 1 23885

Total cost of the equipments @ 2015 = $ 1,322,078

Total cost of the equipments incl. 20% extra for other accessories = $ 1,586,494

7.3 Estimation of Fixed Capital Investment

Purchased equipment delivered, 25% of total = $ 396623

Purchased equipment installation, 6.3% of total = $ 99949

Instrumentation (installed), 6.4% of total = $ 101535

Electrical installed, 4.6 % of total = $ 72978

Piping (installed), 7.3 % of total = $ 115814

Buildings including services, 4.6 % of total = $ 72978

Yard improvement, 1.8% of total = $ 28556

Service facilities installed, 13.8% of total = $ 218936

Land, 0.9% of total = $ 14278

Total Direct Plan Cost, D = $ 932855

Engineering and Supervision, 9.2% of total = $ 155276

98

Construction expenses, 11 % of total = $ 174514

Contractors fee, 1.8 % of total = $ 28556

Contingency, 7.3 % of total = $ 115814

Total Indirect Cost, I = $ 474,160

Fixed Capital Investment = D+I = $ 1,407,015

7.4 Estimation of Total Capital Investment

Total Capital Investment = Fixed Capital + Working Capital

Working capital cost = 20% of Fixed Capital Investment = $ 281,403

Total Capital Investment = $ 1,407,015 + $ 281,403

Total Capital Investment = $ 1,688,418

99

Chapter 8

HAZOP Study

8.1 What Is a HAZOP Study?

A Hazard and Operability Study (HAZOP) is a systematic approach to

investigating each element of a process to identify all of the ways in which

parameters can deviate from the intended design conditions and create

hazards or operability problems.

A HAZOP Study typically involves using the piping and instrument diagrams

(P&ID), or a plant model, as a guide for examining every section and

component of a process. A HAZOP team consisting of experienced and

knowledgeable people, brainstorms potentially hazardous situations that could

arise in each section of pipe, each valve, and each vessel in the system.

The HAZOP team should be led by someone with an in-depth knowledge of the

process, but they do not need to be an expert in the technology used in the

process. The HAZOP team should include people with a variety of expertise

such as operations, maintenance, instrumentation, engineering/process design,

and other specialists as needed.

100

8.2 Objective of HAZOP

Identifying cause and the consequences of equipment and associated

operator interfaces in the context of the complete system.

It accommodates the status of recognized design standards and codes of

practice but rightly questions the relevance of these in specific

circumstances where hazards may remain undetected.

8.3 How and Why HAZOP is used

HAZOP identifies potential hazards, failures and operability problems. Its

use is recommended as a principal method by professional institutions

and legislators on the basis of proven capabilities for over 40 years. It is

most effective as a team effort consists of plant and prices designers,

operating personnel, control and instrumentation engineer etc. It

encourages creativity in design concept evaluation. Its use results in fewer

commissioning and operational problems and better informed personnel,

thus confirming overall cost effectiveness improvement.

Necessary changes to a system for eliminating or reducing the probability

of operating deviations are suggested by the analytical procedure.

HAZOP provides a necessary management tool and bonus in so far that it

demonstrates to insurers and inspectors evidence of comprehensive

thoroughness.

101

HAZOP reports are an integral part of plant and safety records and are

also applicable to design changes and plant modifications, thereby

containing accountability for equipment and its associated human

interface throughout the operating lifetime.

HAZOP technique is now used by most major companies handling and

processing hazardous material, especially those where engineering

practice involves elevated operating parameters:

Oil and gas production

Flammable and toxic chemicals

Pharmaceuticals etc. Progressive legislation in encouraging smaller and specialty

manufacturing sites to adopt the method also as standard practice.

8.4 Purpose of HAZOP

It emphasizes upon the operating integrity of a system, thereby leading

methodically to most potential and detectable deviations which could

conceivably arise in the course of normal operating routine including "start-up and "shut-down" procedures as well as steady-state operations. It is important to

remember at all times that HAZOP is an identifying technique and not intended

as a means of solving problems nor is the method intended to be used solely as

an undisciplined means of searching for hazardous scenarios.

102

8.5 HAZOP Study Flowchart

Figure 8.5a

103

8.6 HAZOP Study for a Distillation Column

SYSTEM:

DISTILLATION

COLUMN

PARAMETER GUIDEWORD CAUSE CONSEQUENCES SAFEGUARD

LEVEL

HIGH level

Level

Controller

fault

Level rises and re-

boiler operation

stops.

High level

alarm

TEMPERATURE

HIGH

Increased

re-boiler

duty.

Composition can

be affected

Temperature

controller,

Control Reflux

ratio

LOW

More reflux

than

optimum.

Composition can

be affected

Control reflux

ratio

PRESSURE

HIGH

Blockage

at outlets.

Column can burst.

Pressure

controller and

alarm.

Pressure relief

valve

COMPOSITION

Misdirected

Disturbed

column

feed

Inferior product

quality

Composition

analyzer at

inlet.

Recycle

bottom

product.

104

SYSTEM:

REBOILER

TEMPERATURE

High

More steam

injection

More cost

Control valve

at steam inlet

Temperature

controller

Low

Less steam

injection

Desired separation

will be affected.

Control Valve

SYSTEM:

CONDENSER

PRESSURE

High

High water

temperatur

e.

No water.

Excessive Pressure

Backup

cooling water

system

TEMPERATURE

High

Fault in

cooling

water

generator

Vapors will not

condense.

Increase

reflux.

Low

Failure of

temperatur

e sensor.

Operating cost will

increase.

Install tripping

system.

105

Chapter 9

Environmental Impact

This chapter aims to present the main environmental impacts of oil and gas

industry throughout the stages of hydrocarbon production, separation, new

deposits and oil refining. It also addresses the issue of environmental risks in

industry and possible accidents that may arise from occurring activities.

9.1 Introduction

Oil plays a vast and vital role in our society as it is organized today.oil represents

much more than just one of the main source of energy used by mankind.

Besides, being an important energy source, petroleum products serve as

feedstock for several consumer goods, thus playing a relevant and growing role

in humans life.

On the other hand oil industry holds major potential hazards for the environment,

and may impact it at different levels air, water, soils and consequently all living

beings on our planet.

9.2 Potential environmental impacts

Following table presents in a simplified manner the main potential environmental

impacts and some feasible alleviating measures

106

Potential environmental

impacts

Mitigation measures

Limitations

Water contamination

due to effluent, wash

water and cooling

water discharges, and

seepage from disposal

and waste tanks.

Water contamination

due to discharges of

water effluents rich in

inorganic salts without

appropriate treatment.

(saline pollution)

No waste water shall be discharged

without appropriate treatment into

rivers or other locations where

infiltration may occur.

Water effluents may be treated by:

neutralization, evaporation,

flocculation, aeration, oil and grease

separation, carbon adsorption,

reverse osmosis, ion exchange, and

bio treating etc, depending on the

contaminant to be removed.

Total solids (70g)

TDS (50)

SS (10g)

BOD (6g)

Nitrogen (40)

Phosphorus(10)

Chloride(50)

Grease(2g)

COD (50g)

Thermal pollution due to

discharge with

temperatures higher

than the recipients

water bodies

Water contamination

due to oil spills

Liquid effluent discharges into

recipient water bodies must comply

with standard governed by laws and

regulations adopted in each

country.

Materials that may seep due to rains

must be placed in covered storage

areas, equipped with drainage

systems, in order to avoid

contamination of rain waters.

Particulate emissions

into the atmosphere

Particulate emissions can be

controlled by equipments such as

PM( ranging from less

than 0.1 to 3 kg )

107

generated during

operations at

production and refining

plants.

cyclones, bag filters, electrostatic

precipitators and scrubbers among

others.

Acidic emissions such as sulfur and

nitrogen oxides can be controlled

with the use of wet scrubber.

Dust emissions from outdoors and

patios areas free from chemical

contaminants can be controlled with

water sprays.

Sox( 1.3 kg, ranging

0.2 to 0.1 kg )

NOx( 0.3 kg, ranging

0.06 to 0.5 kg)

Sulfur and nitrogen

oxides, ammonia, acid

mist and fluorine

compounds gas

emissions from

production and refining

plant operations.

Gas emissions can be controlled by

wet scrubbers or carbon adsorption

among other techniques.

Occasional release of

potential hazardous

materials, such as

solvents and acid or

alkaline materials.

Preventive maintenance of

equipment and storage areas, to

prevent occasional releases.

Dikes and catch basins placed

around or downstream from

dangerous or environmentally

hazardous materials storage tanks.

BTX (ranging 0.75 to 6

g)

Solid wastes that cannot be

108

Soil, surface water

and/or ground water

contamination by

inappropriate disposal

of solid wastes resulting

from chemical industry

processes, including

effluent treatment,

sludge and particulate

matter from dust

collectors.

recycled must be treated

appropriately before final disposal.

The choice of appropriate treatment

must comply with the waste

classification according to the

pertinent regulation(s).

Depending on the nature of the

waste, possible treatment methods

include: incineration, controlled

landfill disposal, chemical

immobilization and solidification,

encapsulation, burning in cement

kilns.

Should these treatments be

unavailable at the site, the waste

may be treated in other plants with

suitable facilities, in which case

special care must be taken during

waste transportation.

If the waste is not treated

immediately after being generated,

there must be suitable area for

storage at plant site.

Sludge( 0.3 kg per

ton of crude

processed )

Changes in local traffic

due to truck

circulation(including

dangerous cargos)

Accessibility and road system

conditions must be assessed during

feasibility studies, selecting the best

routes to reduce impact of

109

accidents.

Noise pollution caused

by equipment and

operations that cause

loud noise.

Acoustic treatments by enclosure of

equipment or soundproofing

buildings that hold loud equipment

and/or units that operate at

significant noise levels.

Daily exposure to

workers noise (3 dBA)

Accidents that impact

the environment such as

large spills, leaks, fires

and explosion on plants.

Eventual deaths.

Emergency response plan.

110

REFERENCES

[1] (Hellyer, n.d.). Article at profiles of chemical engineers. published on 27th

march 2010.

[2] Nelson. Petroleum Refineries. ch24. p889.

[3] Nelson. Petroleum Refineries. ch24. Fig. 24-1. p890.

[4] http://link.springer.com/article/10.1023/A%3A1011692118809#page-1

[5] http://www.chemguide.co.uk/physical/basicrates/arrhenius.html

[6] Octave levenspiel. Chemical Reaction Engineering. ch. 18. p411.

[7] Donald. Q. Kern. Process Heat Transfer. ch. 7. p151.

[8] http://www.slawinski.de/en/products/torispherical-heads/

[9] Byco Petroleum Pakistan Limited.

[10] JF, Richardson & Coulson JM. Coulson and Richardson's Chemical

Engineering. 4th ed. Vol. 6. ch. 11. p524.

[11] McCabe & Smith. Unit Operations of Chemical Engineering. 7th ed. ch. 21.

p704.


[13] George Stephanopoulos. Chemical Process Control.

111

[14] From Table 6.2 of Coulson & Richardsons volume 6. ch. 6. p259.

[15] http://cadiary.org/cost-inflation-index-capital-gain/


Engineering. 4th ed. Vol. 6. Fig 6.7. p254.


Engineering. 4th ed. Vol. 6. Fig 6.5b. p257.


Engineering. 4th ed. Vol. 6. Fig 6.7. p258.

[19] Cox Chart.




[23] Donald. Q. Kern. Process Heat Transfer. fig. 18. p828.

[24] Donald. Q. Kern. Process Heat Transfer. tab. 9&10. p842-843.



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8.1 What Is a HAZOP Study?

Thesis about a apetroleum industry

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