TEAM 3

Index

1. Our Take on the Problem Statement

2. Abstract

3. Global Survey

4. Average Throughput Calculations

5. Scoring and Process Selection

6. Our Solution

7. Process Flow Diagram

8. Design of Lab-Scale Facility

9. Feasibility

10. Annexures

11. References

Our Take on the Problem Statement

From the Problem Statement provided, we understand that the primary issue of a steel

plant in Eastern India is the increase of Quinoline Insoluble (Q.I.) content in the Clarified

Coal Tar, obtained after processing the coke oven gas in the by-product section of the plant.

However, it has been noted that the cause of the increase in Q.I. content could not be

attributed to a single entity of the by-product section of said steel plant. We believe that the

cause of increase in the Q.I. content might be due to a possible change in coal charge fed into

the coke battery. However, one cannot be certain if that is the reason and hence, we proceed

to work on the solution without making any assumptions as to what is causing the increase in

Q.I. content.

We also understand from the Problem Statement, that a limited amount of Q.I. content

is desirable as it is believed that a small amount of Q.I. content enhances binding ability of

the tar pitch which aids in the manufacture of electrodes. It is also stated that excessive Q.I.

content (>9% w/w) is undesirable.

The Problem Statement also suggests some conventional procedures that are often

used to remove Q.I. particles viz. Electro-Coagulation, Demulsification and Centrifugation.

The problem statement encourages us to either use these techniques or look beyond these

processes while developing a solution of the problem.

The problem statement states the classification of Q.I. into primary Q.I. and tertiary

Q.I. The definition of primary Q.I. has been provided while the definition of Tertiary Q.I. was

not mentioned. It was mentioned that tertiary Q.I. caused high ash content and needed to be

removed. The problem statement also mentions that the amount of primary Q.I. needs to be 7-

9% for the production of carbon electrodes and hence, a need for enhancement of primary

Q.I. content. However, it is of prime importance to mention here that the enhancement

of primary Q.I.s will most probably be done in the electrode processing industry during

the production of coal tar pitch and not in the steel plant by-products section.

Thus, following the problem statement, we aimed at making changes in the current

set-up to ensure that the Q.I. content in the saleable tar was around 5%.

Finally, the key takeaways from the problem statement are that it demands us to fulfil

the following:

i. Suggest changes to the current by-products section to reduce the Q.I. to around 5%.

ii. Focus more on the removal of tertiary Q.I.s rather than primary Q.I.s.

iii. Survey the procedures used worldwide to reduce Q.I.s in coal tar.

iv. Choose the best procedures to use for the removal of Q.I.s in this case.

v. Design the new equipment required for the solution, if any.

vi. Design a lab-scale set-up to determine the efficiency of Q.I. removal from the method

suggested by us in this solution.

Abstract

As the industrial world works its way towards excellence, the focus on competitive

advantage has increased now more than ever. Every industry aims to provide its customers

with something that gives it a comparative edge over its competitors. Similar is the case in

the problem statement, wherein the Steel Plant hopes to regain its competitive advantage of

providing high quality coal tar with low ash forming solid materials, known as Quinoline

Insolubles or Q.I.s.

In our attempt to solve the challenge faced by the industry, we have worked hard,

scanning through tons of patents, amounting to an uncountable number of pages. Research

papers on separation techniques of Q.I.s in coal tar, methods of increasing efficiency of

Electrostatic Precipitators, methods for increasing the efficiency of Decanter Centrifuges

were all studied upon. Countless methods on solvent extraction, cyclone separation,

dehydration and demulsification were thoroughly gone through and the most common, most

innovative and most feasible solutions selected to be represented in this literature for the

Global Survey of Q.I. reduction techniques.

Modified Cross-Flow Circulating Filtration was used in Japan. Hydrocyclones and

Swirl Tubes were used to affect separation in China. Patents under corporations of the United

States of America, Canada, Russia and Europe all contained varying techniques of solvent

extraction of Q.I.s in the form of α-resins.

In our solution to this problem, we suggested a minor improvement in the decanter

centrifuge to avoid abrasion of the centrifuge wall, causing unnecessary pressure drop, thus

decreasing the separation efficiency of the said equipment. Addition of a modified solvent

extraction technique to treat the clarified tar further to remove tertiary Q.I.s while retaining

the useful primary Q.I.s. The economics of the solution was also worked upon and we figured

out that the pay-back time of the newly installed process is less than 3 months. The

laboratory scale model was developed and an Aspen simulation for the same was designed

and run to show the effectiveness of removal of Q.I.s from tar samples taken from the by-

product plant.

Global Survey

Before we proceed to conduct the global survey of Q.I. reduction, we need to

understand the constituents of Q.I. material. E. O. Ohsol et al.[1] states that Q.I.s are materials

that are the insoluble residue left after extraction of the coal tar or pitch with a large excess of

Quinoline at 80OC. and comprises primarily coal dust, breeze, inorganic matter, graphitic

carbon, amorphous carbon and organic high polymers and macromolecules.

Therefore, we have worked to include processes which not only remove Q.I. from the

coal tar, but also focussed on de-ashing methods for Coal Tar so that ash-forming tertiary

Q.I.s are handled. Of the many processes surveyed, some worth mentioning are:

1. Removal of Quinolone Insolubles and Ash using Electrostatic Fields

In this method described by Q. Cao et al, [2] Q.I. and ash can be effectively

removed on applying an electrostatic field of 2.25x 10^5 V/m on an oil dissolved

mixture of coal tar. This method of treatment has a low energy consumption

(1/12th of that of centrifugal methods) and completely strips coal tar of Q.I.

(primary and tertiary). While this may be suitable for the production of needle

coke and carbon fibres, primary Q.I. is desired for binder coke production which

is the primary drawback. High labour intensive tasks such as fine screening and

filtering at 140-200oC and low recovery rates (70%) are additional setbacks to this

method.

2. Solvent Extraction of Q.I. using Benzene

As mentioned in the U.S. Patent document, US3147205 by E. O. Ohsol et al,

Benzene as a solvent dissolves most of the components of coal tar such as toluene,

xylenes, naphthalenes, pyridines, etc. By the application of super-atmospheric

conditions (120-200oC and 35-300 psig), benzene becomes an even better solvent

and dissolves organic macromolecules and some of the Q.I. as well, leaving

behind a residue containing only coke breeze, amorphous carbon and inorganics.

Benzene is then separated from the residue and distilled to leave behind pitch

which valuable for binder pitch production.

3. Removal of Ash Forming Salts using High Pressure CO2[3]

Washing of coal tar with water and compressed CO2 gas promotes the formation

of an aqueous phase containing dissolved salts. These salts are highly undesirable

in the manufacture of electrodes, since they not only form additional slags but also

increase the consumption of anode. Water containing these salts can be decanted

off to obtain coal tar. The advantage of this method is that once washing is carried

out, all chlorides (NaCl and NH4Cl) and more that 50% of zinc salts (ash forming

constituents) are removed, while valuable primary Q.I.s remain in coal tar. Once

water is depressurized, zinc sulphides precipitate out and water can be recycled.

4. Cross Flow Filtration using Membranes

Referring to a German patent, DE69511045D1[4], a continuous Q.I. containing

liquid tar feed is introduced at higher pressure than the permeate in a series of

cross-flow filter membranes that gives a product having increased Q.I.

concentration and concurrently, a Q.I. free liquid tar product.

Particles larger than the membrane pores do not pass through the membrane and

hence, are rejected. In cross-flow filtration, feed flows parallel to the surface of

membrane creating shear forces that keep this layer thin, while the filter cake does

not continuously accumulate with time and the permeation flux reaches a

substantially constant value. Chemical stability of the membrane helps ceramic

membranes to be resistant to a wide range of organics and thermal stability helps

in undiluted tar operation (high temperature operation i.e., >80° C.) which is

required to reduce the viscosity of a tar to attain practical filtration.

5. Viscosity Modification to Enhance Solid Separation in Decanting Centrifuge

As the schematic provided by the Steel Company indicates the presence of a

decanting centrifuge, we worked to figure out ways to enhance the separation of

dense ash particles from the tar phase. Otto Houwen’s patent on the Method for

calculating the turbulence factor for decanter centrifuge [5] suggests that a low

viscous fluid helps in the easy separation of solids from liquids in a centrifuge.

Viscosity modification techniques of tars comprise of heating a stream of gas and

a stream of tar and then mixing them before passing the mixture through an

orifice. The mixture is introduced in a reaction chamber where fine droplets of oil

interact with a turbulent gas stream, producing a low viscosity fluid. This fluid

when passed through the decanting centrifuge causes easy separation of ash and

mineral particles, thus reducing to an extent, Q.I. content in the coal tar.

6. Solvent Extraction using Organic Solvents such as NMP

In this process for the separation of quinoline insoluble components, coal tar pitch

is treated with an organic solvent[6] and the insoluble components are thereafter

separated; the improvement involved comprises the selection of a coal tar pitch

with a softening point, greater than 60° C. Here, we use multiple solvents among

which at least one is a solvent with paraffinic characteristics and one is a tar

solvent, at temperatures between 200° – 270° C. Mixing of the pitch with solvents

can be done in two ways. In the first case, pitch is mixed directly with the mixture

of solvents. An alternative is to first treat the pitch with the tar solvent at an

elevated temperature and the paraffinic solvent is added later to the affect the

separation of Q.I.-components. This process can selectively remove α- resins

(which are mostly Q.I. – components) without altering the state of β- resins

(content of compounds of soluble in quinoline, insoluble in toluene). By this

method it is possible to obtain a pitch with an essentially uniform share of β –

resin and very small share of α- resins (Q.I.) as desired.

7. Solvent Extraction followed by Centrifugation

A few Brazilian literatures such as the one by A.T. Gontijo et al [7] state that the

dilution of coal tar by coal-tar derived organic oils as solvents followed by

physical separation has been found to be most efficient in the process of removing

Q.I. The process suggests that the coal tar be digested with the said solvent at an

elevated temperature of 90 – 95oC under constant stirring followed by semi-

continuous centrifugation at a high rpm and final distillation at 300oC to remove

any remaining solvent which gave rise to good quality coal tar with reduced Q.I.

content. This process is particularly efficient considering the fact that Q.I. matter

removable using both chemical and physical techniques can be removed.

8. Process of de-ashing coal using multiple centrifuges

Extraordinarily high solid and high ash coal tar are subjected to centrifugation at

very high G forces to reduce ash, Q.I. and other solids levels to produce a coal tar

suited for use in the production of coal tar pitch[8].

The process includes subjecting ash-containing initial coal tar to multiple

centrifugation. A first centrifuge of low G force provides an intermediate tar. It is

then subjected to a solids-ejecting, disk-stack centrifuge at a centrifugal force of

about 5000 G's. The first fraction is recovered from the centrifuge which provide a

finished coal tar with the desired characteristics.

Additional centrifuges can also be used depending upon the quality of coal tar

used.

9. Treatment of Coal Tar using Surfactants

Samuel Cukier’s patent, US4395326[9] suggests that water and Q.I. in coal tar are

believed to be associated with each other to form the dispersed phase of a stable

emulsion. Therefore, the use of a surfactant derived from a long chain alkyl group,

mixed with coal tar is employed to promote the separation of the aqueous phase

from tar, carrying along with it Q.I. particles. This separation can be achieved by

allowing the mixture to settle down by means of a decanter, after which a portion

of the water is bled off. Thus, fresh surfactant must be added to replenish its

concentration before being returned for treatment.

Average Throughput Calculations

Since it was mentioned in the Problem Statement that the steel plant was situated in

the eastern part of India, we adopted the SAIL Steel plant of Rourkela and all the calculations

and designs following this section in the report are based on the Rourkela Steel Plant.

The capacity of Rourkela Steel Plant’s Coking unit is 3500 T/day [10]. Following the

coke flow diagram given in the problem statement, we end up with a coal tar throughput of

58.5 T/day.

Fig 1. Coke Flow Chart and Distribution

Hence, all our calculations are based on a capacity of 58.5 tonnes per day. Although

this step is not necessary, we find it compelling to include it in the report as it provides the

robustness required for the selection of the best process for the separation of Q.I. from coal

tar. The process selection can very easily be done without the need to quantify the capacity

and throughput of the equipment being used. However, we felt it would provide better

understanding of the feasibility and economic aspects of the selection criteria if a tangible

quantity is put forward rather than generalizing the solution.

Having this in mind, we can now proceed towards the criteria for the selection of the

best process for Q.I. reduction from coal tar. Assuming that the cost per kg of the tar is

around Rs. 30, the revenue generated per day by the sale of coal tar is close to Rs. 18,00,000.

Keeping a margin of around 50%, the average operating cost must not exceed Rs. 9,00,000

per day which gives us a good amount of freedom to select the best process among the

processes shortlisted in the report.

As we proceed to figure out the best procedure for the removal of Q.I. we can have a

good idea as to how much is an acceptable operating cost that can be afforded, given a

process is finalized.

Scoring and Process Selection

The following criteria were considered while scoring the various processes so as to

select the best process. However, some criteria were more important than others. For

example, a process with a huge capital cost but small operating costs is always better than a

process with a small capital cost and a large operating cost. Hence, weightages were allotted

to the different criteria and a final scoring was done. The criteria along with its weightages

are as follows:

i. Capital Cost, weightage of 1

ii. Operating Cost, weightage of 2

iii. Efficiency, weightage of 1

iv. Scalability and Capacity, weightage of 1

v. Power Requirement, weightage of 1

vi. Waste Generated, weightage of 0.5

vii. Operating Time, weightage of 2

viii. Product Specification, weightage of 2

ix. Space Requirement, weightage of 0.5

Each process was evaluated with respect to these criteria and relatively graded

accordingly. The final score was calculated by multiplying the score in each criterion with its

weightage and summing them together.

Table 1. Scoring of processes.

As can be seen above, the scoring for High Pressure CO2 separation as well as Benzene

solvent extraction have high scores compared to others. Therefore, our solution will focus

majorly on these two processes to remove Q.I. content from tar.

Our Solution

The solution to this problem statement requires addressing the following issues:

1. Reduction of Tertiary Q.I. solids which include mineral matter and coal solids,

without significantly affecting the desired Primary Q.I. solids.

2. Abrasion of equipment caused by the presence of Tertiary Q.I. solids, reducing capital

expenditures down the line.

For this, we propose a combination of 2 methods discovered in the global survey of Q.I.

reduction processes:

1. Ash removal using Water and Supercritical CO2

Given that tertiary Q.I. solids are a major concern due to their abrasive nature

(damaging equipment downstream), the first step involves the washing of coal tar

with water and compressed CO2. This is achieved by inserting coal tar and water into

a high pressure vessel along with the pumping of compressed CO2 (at 100 bar).

A residence time of 3 hours not only results in the removal of ash constituents like

zinc sulphides and oxides but the presence of water also dissolves salts like

ammonium chloride and sodium chloride which are known to corrode distillation

columns. The mixture water and CO2 is then depressurized and condensed to recover

water, which is sent to a treatment facility, and CO2 both of which can be recycled.

The coal tar obtained from the bottom now has reduced quantity of ash.

2. Solvent Extraction of Coal Tar using Benzene

Now that we have a coal tar devoid of most of the tertiary Q.I. solids, it is safe to

perform an extraction of desirable coal tar constituents. Under normal atmospheric

conditions, benzene dissolves most of the constituents of coal tar, however, upon

raising this pressure to about 300 psig, benzene dissolves most organic

macromolecules and some quinolone insoluble as well.

This operation, performed in an extraction column under pressure leaves behind a

residue that consists of coke breeze, graphitic and amorphous carbon and inorganics.

After the separation of this high density residue in a decanter, benzene is distilled off

from the extract to recover a high value coal tar.

This series of steps ensures that the coal tar obtained is completely ash free and is suitable for

the manufacture of carbon electrodes.

Although the above procedure ensures that equipment downstream is not eroded by solids,

precautionary measures can be employed to protect high value equipment, namely, the

decanter centrifuge. The decanter centrifuge scroll is most vulnerable and requires the use of

abrasion protection materials which can be melted and fused directly such as a nickel or

cobalt alloy using an oxy-acetylene gas torch in a manner similar to welding.

[Refer Annexure – 2 for 3D Rendering]

Process Flow Diagram

Laboratory Scale Investigation Facility

The laboratory scale investigation facility designed in this report can be used to

investigate not only the reduction in Q.I. content of the tar, but also the reduction of ash

content after the preliminary process of hi-pressure CO2 extraction.

In the laboratory scale facility, we used an autoclave as a suitable alternative for a

pressure vessel since they are designed to handle very high pressures of up to 3000 psi (g).

However, the more expensive pressure vessel can be used as well. The decanter centrifuge

has been modelled using a laboratory centrifuge and decanters have been replaced by

manually decanting the upper phase by tilting and pouring out the top phase. The final

filtration method has been modelled by use of filter papers in funnel arrangement. The

extraction column in the benzene extraction method was again replaced by an autoclave since

it satisfied all requirements of a laboratory scale extraction unit.

The ash content was evaluated using European Standard DIN51719 wherein 1 gram

of the sample is placed in a crucible and heated at a rate of 5K/min till the temperature

reached 106oC under nitrogen atmosphere. The sample is then heated at a rate of 5 K/min till

the temperature reaches 550oC under oxygen atmosphere. The sample is heated for 30-60

minutes at the same temperature. The remaining content is weighed and reported as the ash

content.

The Q.I. content was evaluated using ASTM D4746[12] wherein the tar is dissolved in

quinoline at 75oC and filtered through a porcelain filtration crucible with a medium porosity

bottom at a pressure in the range of 10-30 psi(g) using nitrogen. The sample is washed in hot

quinoline until clear, followed by acetone and dried. The portion of the tar remaining in the

crucible is defined as Q.I. fraction.

The procedure used to simulate the process is as follows. The following apparatus will

be required for setting up the investigation facility.

i. Stirrable Autoclave

ii. Compressor

iii. Centrifuge

iv. Beaker

v. Liebig’s Condenser

vi. Round bottomed Flask

vii. Electrical Heater

viii. Centrifuge tubes

ix. Water Pump

x. CO2 Cylinders

xi. Digital Weighing Scale

Procedure:

A 0.5 kg sample of clarified tar from the decanter centrifuge is taken for investigation.

The sample is divided into two parts. 400g of the sample is taken aside and the

remaining sample is used to evaluate its Q.I. content and ash content.

o Let them be Q1 and A1 respectively.

This sample is used to evaluate the initial Q.I. content and ash content.

400 g of the sample is then mixed with 500g of water in a beaker and placed in an

autoclave.

The autoclave is heated to 150oC and pressurized to 100 bar using CO2 and stirred for 3

hours.

The autoclave is depressurized by venting off the CO2 and the phases are separated

using a laboratory centrifuge at 4000 rpm for 10 minutes and the top phase is drawn off.

The bottom layer is removed from the tube and 50g of this sample is separated and the

ash content is measured.

o Let the ash content be A2.

The 350g fraction is taken in a fresh beaker and mixed with 1.2 parts (420g) of benzene.

The beaker is again placed in the autoclave and heated to 158oC while asserting a

pressure of 80 psi(g) for 2 hours.

The beaker is then taken out and either centrifuged or filtered using a filter paper. The

cake of the filtration process or the palette from the centrifuge tube is then analysed for

Q.I. content.

o Let the Q.I. content be Q2.

The Q1 and A1 values are compared with Q2 and A2 respectively to judge the

effectiveness of the process.

Effectiveness of the process can then be defined as:

η = 𝑄1−𝑄2

𝑄1∗ 100 %

The Q.I. content can be measured as:

Qi = 𝑊𝑠𝑐−𝑊𝑐−𝑊𝑓

𝑊𝑠𝑐−𝑊𝑐∗ 100 %

Where: Wsc = Weight of Sample + Crucible

Wc = Weight of Empty Crucible

Wf = Final Weight of Crucible

The ash content can be measured as:

Ai = 𝑊𝑓

𝑊𝑖∗ 100 %

Where: Wf = Final Weight of sample

Wi = Initial Weight of sample

Feasibility

Any practical solution to a problem has to be feasible. We believe that the most

important criteria to evaluate a solution to a problem is its feasibility.

The feasibility study for this solution will focus on 5 main areas: Technical,

Economic, Legal, Operational and Scheduling.

Technical Feasibility:

To establish the technical feasibility of our solution, we need to examine the new

equipment which would be commissioned. We would also examine the human

resource, expertise and other possible factors that could affect the successful

implementation of the solution.

In our case, the new equipment being commissioned are: i) Pressure Vessel, ii)

Extraction Column, iii) Decanter, iv) Distillation Column.

Calculations mentioned in Annexure -3 state that all the raw materials required have

a ready market and are easily available in the market. For instance, our pressure

vessel, extraction column and distillation column need to be fabricated using Carbon

Steel Sheets of 61mm, 28mm and 10mm thickness, all of which are available with

local and international suppliers and can be procured within a timeframe of 4 weeks.

The vessels themselves can be manufactured by fabricators all over India.

The newly commissioned equipment requires the recruitment of specialist personnel

to ensure smooth operation. Alternatively, the controls systems can be automated

and operated remotely.

Economic Feasibility:

As mentioned in the problem statement, there is a risk of huge losses if the Q.I.

content in the tar is above 9%. The capital cost of our proposed solution is around

Rs. 20,00,000. As estimated earlier in the report, the revenue by tar sales is close to

Rs. 18,00,000 per day. Provided that the changes suggested by us improve the

marketability of our product and results in a modest 5% increase in selling price,

that would amount to an increase of Rs. 90,000/day in revenue due to sale of tar.

With the daily operating cost coming to Rs. 56,500/day and assuming an interest

rate of 8%, the breakeven time is around 2 months from the date of

commissioning. Refer Annexure -1 for detailed break-up.

Moreover, the proposed solution aims at removing the tertiary Q.I, hence reducing

the maintenance cost by reducing damage to all other equipment due the abrasive

property of tertiary Q.I.s.

Legal Feasibility:

An area of around 1000 sq.ft would be required for which no additional land would

be acquired. Therefore, there are no possible conflicts with respect to land

ownership.

Water treatment plant is present in the steel plant and CPCB guidelines must be

met.

Operational Feasibility:

Although there are better solvent extraction methods for the removal of Q.I.s from

coal tar, they are mostly not feasible for the reason that they remove all the primary

and secondary Q.I.s which are desirable. David R Ball’s experiment[11] suggests

that blending of tar pitches is undesirable and usually results in inferior quality of

pitches.

In our proposed solution, we intend to use Carbon-dioxide gas which can be

procured from the coke over gas which contains around 2% of CO2 which amounts

to 1,638 Nm3/day which suffices our requirements. Moreover, our procedure

ensures that the primary Q.I.s are not affected, which makes the coal tar desirable.

The solvent used in our solution, Benzene is relatively cheaper and easily

recoverable compared to the solvent mentioned in the Problem Statement N-methyl

2-Pyrrolidone.

Schedule Feasibility:

The time required for the completion of this project would be two and a half

months. The breakeven time is around 60 days. Hence, there will be no major set-

backs and thus, the project would be feasible.

Having discussed all the facets of the feasibility study, we can now conclude that the

suggested solution to the problem statement is feasible in all aspects and one of the most

innovative and efficient method of removing Q.I.s from coal tar.

ANNEXURE

Annexure – 1 Estimation of Capital Cost & Operating Cost

Capital Cost:

Item Specification Price (INR)

Gas Compressor Power Requirement = 22 KW 1000000

Capacity = 25 Nm3/hr

CO2 Extraction Column O.D. = 2.026 m 500000

I.D = 1.9 m

Thickness = 63 mm

Height = 4.1 m

Benzene Extraction Column O.D = 1.756 m 170000

I.D = 1.7 m

Thickness = 28 mm

Height = 3.5 m

Distillation Column O.D. = 1.52 m 60000

I.D. = 1.5 m

Thickness = 10 mm

Height = 8 m

No. of Trays

Tray Spacing

Decanter (1 Quantity) Capacity = 2-35 Nm3/hr 150000

Power Requirement = 20 KW

Dimensions

(L*W*H)=1850*1250*1750

Piping and Instrumentation 100000

Total 19,80,000

Operating Cost per day:

Utility Quantity Price

1. Electricity 70 kW 10000

2. Water 10 TPD 500

3. Benzene make up 0.5 TPD 26000

4. CO2 Conditioning 10000

5. Labour 10000

Total 56,500

Annexure – 2 3D Rendering of Proposed Scheme

Fig: Schematic depicting Pressure vessel, Extraction column, Distillation Column,

Condenser and Decanter

Annexure – 3 Process Equipment Design

Calculation of shell thickness

From WEBSITE FOR STATIC EQUIPMENT CALCULATION link and the book

Introduction to Chemical Equipment Design, B. C. Bhattacharyya we have calculated:

Shell & Hemispherical Head for CO2 Extraction Column:

Carbon Steel

63mm thickness

1.9m I.D

Shell & Hemispherical Head for Distillation Column:

Carbon Steel

10mm thickness

1.5m I.D

1. No. of lugs = 4

2. Load on lug = 9651 kg

3. Lug width = 150 mm

4. End radius = 150 mm

5. Hole size = 30 mm

6. Lug thickness = 66 mm

7. Material = GR 300 ; Mild Steel AS3678

8. Continuous weld size = 10 mm

For given temperature, pressure and flow rate conditions.

References

[1] E. O. Ohsol et al,"Upgrading Coal Tar." U.S. Patent 3,147,205, issued Sept. 1, 1964.

[2] C. Qao et al, "A novel method for removing quinoline insolubles and ash in coal tar pitch

using electrostatic fields, 2011.

[3] H. Beneke et al, “Novel Method for Extraction of Salts from Coal Tar and Pitches”. U.S.

Patent 4,871,443A, issued Oct. 3, 1989.

[4] German Patent number DE 69511045 D1, Durchgehendes Verfahren, zur Quinoline

unlösbaren Konzentrationserhöhung eines flüssigen Teers, während der gleichzeitigen

Herstellung eines Quinoline unlösbaren freien Teers.

[5] O. Houwen, “Method for calculating the turbulence factor for a decanting centrifuge.”

U.S. Patent 20060003881 A1, issued Jan. 5, 2006.

[6] J. Stadelhofer et al, “Process for the separation of quinoline insoluble components from

coal tar pitch”. U.S. Patent 4259171A, issued Mar. 31, 1981.

[7] A.T. Gontijo et al. “The study of Q.I. extraction from coal tar pitch using coal tar derived

oils as solvent in centrifugal process”

[8] E. S. Griggs, “Process for De-ashing coal tar”, U.S. Patent 5534137A, issued July 9, 1996

[9] S. Cukier, “Treatment of Coal Tar Emulsions”, U.S. Patent 4395326A, issued Jul 26,

1983.

[10] Webpage at www.sail.co.in/rourkela-steel-plant/about-rourkela-steel-plant

[11] D. R. Ball, “The influence of the type of Quinoline Insolubles on the quality of Coal Tar

binder pitch”, Carbon, 16(3), pp-205-209.

[12] ASTM D4746, Standard Test Method for Determination of Quinoline Insolubles (QI) in

Tar and Pitch by Pressure Filtration.