project report on industrial production of coke

A PROJECT PRELIMINARY REPORT ON

“INDUSTRIAL PRODUCTION OF COKE”

Submitted in partial fulfilment of the requirements for the

Degree of Bachelor of Technology

---------- Presented & Submitted-----------

By

ABHISHEK KUMAR

(Roll No. U10CH043)

AND

HARSHIT KUMAR

(Roll No. U10CH038)

B. TECH. IV (Chemical) 7th Semester

Guided by

Dr.V.N.LADAssistant Professor

CHEMICAL ENGINEERING DEPARTMENT

SardarVallabhbhai National Institute of Technology

Surat-395007, Gujarat, INDIA

DECEMBER-2013

1

SardarVallabhbhai National Institute of Technology

Surat-395007, Gujarat, INDIA

CHEMICAL ENGINEERING DEPARTMENT

CERTIFICATEThis is to certify that the B. Tech. IV (7th Semester)PROJECT PRELIMINARY

REPORT entitled “Industrial Production of Coke” presented & submitted by

Mr.AbhishekKumar(U10CH043) & Mr.Harshit Kumar (U10CH038)& in the partial

fulfilment of the requirements for the award of degree B. Tech. in CHEMICAL

Engineering at Sardar Vallabhbhai National Institute of Technology, Surat.

They has successfully and satisfactorily completed their project preliminary work.

Dr.V.N.Lad

(Guide)

Assistant Professor

Chemical Engineering Department.

DEPARTMENT OF CHEMICAL ENGINEERING

2

SardarVallabhbhai National Institute of Technology, Surat.

This is to certify that Mr.Abhishek Kumar (U10CH043) & Harshit kumar (U10CH038 ),

registered in Chemical Engineering Department of S.V.N.I.T. Surat have successfully

presented their Project preliminaries of B. Tech. (Chemical) 7 th Semester, on 11/12/2013 at

03:00 P.M. The Project preliminaries is presented before the following members of the

Committee.

Sign Date

1) Examiner-1 __________________ ___________ _________

2) Examiner-2 ___________________ ___________ _________

3) Examiner-2 ___________________ ___________ _________

The Project entitled “Industrial Production of Coke” is submitted to the Head (ChED) along

with this certificate.

Place: SuratDate: 11/12/2013

Prof. Z.V. P. Murthy

Head,

Chemical Engineering Department,

SVNIT – Surat.

ACKNOWLEDGEMENT

3

It gives me great pleasure to present my project preliminaries report on

“INDUSTRIAL PRODUCTION OF COKE”. No work, big or small, has

ever been done without the contributions of others. I would like to express deep

gratitude towards Dr.V.N.LAD, Assistant Professor at Chemical Engineering

Department, SVNIT,who gave me their valuable suggestions, motivation and

direction to proceed at every stage. He extended towards a kind and valuable

guidance, indispensible help and inspiration at time in appreciation I offer them

my sincere gratitude.

In addition, I would like to thanks Department of Chemical Engineering

Department, SVNIT.Finally, yet importantly, would like to express my heartfelt

thanks to my beloved parents and my brother for their blessings, my

friends/classmates for their help and wishes for the successful completion of

this project.

Abhishek Kumar Harshit Kumar

(U10CH043) (U10CH038)

4

CONTENTS PAGE NO.

ACKNOWLEDGEMENT 4

LIST OF FIGURES 6

1.Introduction 7

2.Demand And Supply Of Petrolleum Coke 8

3.Physical And Chemical Properties Of Coke, Coke Types, Their Applications 11

3.1Physical And Chemical Properties 11

3.2 Type Of Coke 11

3.2.1. Shot Coke 12

3.2.2. Sponge Coke 12

3.2.3. Needle Coke 13

3.3 Uses Of Petroleum Coke 13

3.3.1 Raw Petroleum Coke 13

3.3.2 Metallurgy Uses 14

3.3.3 Gasification 14

3.3.4 Calcined Petroleum Coke - Other Uses 14

4.Process Description—Delayed Coking 15

5 Material safety data sheet 18

6 Material balance 22

7. Energy balance 26

REFRENCES 32

5

List of tables

Table no. Name of table Page no.

1 Physical and chemical properties of coke 11

2 Overall conversion 22

3 Coke composition in product stream 23

4 data for furnace 26

5 data for coke drum 27

6 Data of hot and cold streams in HEN retrofit of

the coking unit

28

List of table

figure no. Name of figure Page no.

1 PROCESS DIAGRAM 17

2 balance across coke drum 22

3 balance across fractionator 23

4 Delayed Coker Charge Heater 4 Pass - Single Fired

27

5 Modified flowsheet for preheating of feedstocks

31

6

CHAPTER 1

INTRODUCTION

The petroleum coke belongs to a group of materials with a high carbon content. It is produced

by coking of feed stocks obtained from residue of primary and secondary oil refining

processes (atmospheric residue, vacuum residue, thermal cracking residue, gasoline pyrolysis

residue, etc.).Coke is industrially mainly produced using delayed coking process. The

delayed coking is one of the main processes for heavy oil processing in petroleum industry. It

is essentially a high-temperature process involving extensive use of direct heat to up-grade

products. The coking process, as a combined process of the severe thermal cracking and

condensation reactions, needs to consume a large amount of high-grade energy [1].Heavy

oils, such as vacuum residue, cracking residue and catalyzed slurry oil, etc., undergo

severe thermal cracking and condensation reactions at a high temperature of 500 0C, and such

products as dry gases, liquefied petroleum gases, gasoline, diesel, heavy gas oils and cokes

are produced. All heat required by the strong endothermic coking reactions is provided by the

coking heater. The high-temperature reaction vapors at a superheated state are introduced into

the main fractionating column from the coke drums. Different coking products are separated

from the fractionating system in liquid or gas state at relatively low temperatures which carry

a large quantity of low-grade heat. As with other refining plants such as crude topping,

catalyticre forming, etc. [2,3], significant energy-conservation opportunities exist in a delayed

coker.To efficiently lower the energy consumption of the coking unit, it is crucial to increase

the efficiency of the coking heater and to utilize the low-temperature heat. In this our project

the mass and energy analyses of a delayed coker in a refinery are presented.

7

CHAPTER 2

DEMAND AND SUPPLY OF PETROLLEUM COKE

Most industries operate with fixed prices for their input materials, for periods of at least 3–6

months ahead, with prices set either by contracts or by the hedging of future prices. However,

the situation is different in terms of petcoke purchasing by the European cement industry.

The European cement industry (including its non European subsidiaries) consumes around

13Mt of petroleum coke per annum, around 10Mt of which are priced according to indices set

monthly, in US dollars on an FOBi basis US Gulf/Venezuela, by Jacobs Consultancy (a unit

of Jacobs Engineering Group Inc) in the US, and called the Pace indices.

The indices should, theoretically, be assessed as an average of the previous month’s spot

price deals and other new price agreements for petcoke cargoes on an FOB basis from the US

Gulf/Venezuela. The way the indices are evaluated is not published and very often the price

changes between months are inexplicable and direct. This is surprising given the known FOB

prices of petcoke cargoes to European customers and the price developments of other

combustibles, such as steam coal and natural gas.

The price assessments for January 2011 (published in mid February and used for the pricing

of cargoes - depending on contracts - for loading in January or for loading at a later date),

which are up around 15% from the indices in December of 2010, are very difficult to explain,

given declines in steam coal prices of 10–15% based on FOB prices from South Africa, and

falls in natural gas and crude oil prices, WTI. Furthermore, a number of spot cargoes to

European buyers in January were priced at below the January Pace indices.

8

http://www.cembureau.eu/glossary/term/201

Historically, 100% of the petcoke from the US Gulf/Venezuela was shipped to buyers in the

Atlantic basin (mainly to cement companies), meaning that the price assessments for new

cargoes were based on FOB prices for Atlantic destinations.

However, petcoke has become a global commodity since 2008, with buyers in Asia (power

and industrial users) becoming more and more focused on US Gulf/Venezuelan petcoke,

whenever the C&F price Asia for petcoke is competitive with C&F prices Asia for Pacific

steam coal. With record low freights (and Asian steam coal prices), due to a tighter

supply/demand balance, set to level at US$10–20 above Atlantic coal prices, Asian buyers

have come to set the floor price for FOB prices for petcoke in the Atlantic.

This development has meant that the price assessments by Pace have become more a gauge

of Asian demand and prices than of the petcoke market in the Atlantic.

In fact, by applying these indices, European buyers accept the bidding up of the petcoke

market in line with what Asian buyers are accepting.

The assessment of the future Pace indices are more and more difficult to predict. This means

an extremely uncertain price pattern for European and Atlantic buyers of petcoke.

Most cement companies commit their petcoke volumes on an annual basis, but the actual

FOB price for a given loading month is determined by the Pace indices (normally with a

premium of US$8–18 above these indices, as the premiums reflect the tightness of the

market).

This means that it is impossible for a buyer who uses Pace indices for pricing to evaluate the

cost of the petcoke to be delivered during the calendar year, in his/her budgets, forecasting

etc...

An additional problem is that it is not possible to hedge the petcoke prices with most other

commodities and, specifically, all other combustibles. A buyer can hedge the prices of steam

coal, oil product and natural gas purchases, but not the petcoke price.

Buyers, such as power companies in Europe, are being banned from using petcoke by their

risk management departments, as open positions of petcoke cannot be hedged. Other buyers,

such as lime producers and brick companies, will only accept petcoke purchases based on a

system with fixed prices. Contrary to these policies, the Atlantic cement industry

9

continuously has huge positions of petcoke with unhedged prices. Every month a change in

the Pace indices affects the liability of these positions.

The increasing Asian impact makes the indices more volatile and less predictable.

The Pace indices increased by nearly 15% both at the beginning of 2008 and in January 2011,

and similar price jumps will be seen even more frequently in the future.

The only way to reduce the uncertainty in the cost of future petcoke shipments is for cement

companies, acting individually, to reconsider their purchasing policy. This may be done by an

increased share of the annual petcoke volume being agreed on fixed prices instead of being

set on Pace indices. The petcoke price situation at the beginning of 2011 has, furthermore,

been aggravated by overall low inventories, both with refineries and with end users. A more

flexible system, with higher inventories during periods of rising prices, would alleviate

buyers from the price shocks seen in January.

Buyers may also choose to switch to increasing their use of steam coal, with prices which are

directly hedgeable.

The best alternative to petcoke is to burn the most competitive US steam coal. Already Asian

cement plants are burning such coal and some European cement companies are also

considering this option, such coal being priced at 30-40% discount for calorific content

against petcoke.

However, given the very high growth in demand for steam coal in Asia over the next 5 years,

steam coal prices, and thus petcoke prices, will stay at very high levels. For medium/long

term, the only option for the world cement industry is to sharply increase its consumption of

alternative fuels.

10

CHAPTER 3

PHYSICAL AND CHEMICAL PROPERTIES OF COKE, COKE TYPES,

THEIR APPLICATIONS

3.1 PHYSICAL AND CHEMICAL PROPERTIES

Table 1: Physical and chemical properties of coke[7]

3.2TYPE OF COKE: Coke can be classified into 3 types depending on the asphalt

content :- 1) Shot coke2) Sponge coke 3) Needle coke

3.2.1. Shot Coke:

The production of shot coke in a delayed coker requires high concentrations of asphaltenes in

the feedstock, dynamics (velocity and/or turbulence) in the coke drum, and high coke drum

11

temperatures. A coker feedstock high in oxygen content can also produce shot coke. When

asphaltene content compared to the Conradson carbon residue content of the coker feed is

high, the production of shot coke is very likely. The present trend in refineries is to run

heavier crudes with higher asphaltene contents and to improve operation of the vacuum

distillation unit to produce a heavier VRC with a higherasphaltene content. This trend toward

increased production of shot coke has been observed in refineries which originally ran

atmospheric reduced crude in the delayed coker, never making shot coke, that started

producing shot coke after a vacuum distillation unit was installed. Shot coke is produced as

the oil flows into the coke drum. With the light ends flashing off, small globules of heavy tar

are suspended in the flow. These tar balls rapidly coke due to the exothermic heat produced

by asphaltene polymerization. (Cokers going from sponge coke production to shot coke

production have seen the drum overhead temperature increase by as much as 276 k.) The

balls then fall back into the drum as discrete little spheres two to five millimeters in size. In

the main channel up through the drum, some of the spheres will roll around and stick together

forming large balls as large as 25 centimeters.

3.2.2. Sponge Coke :

Sponge coke is named for its sponge-like appearance and is produced from VRC with a low

to moderate asphaltene concentration. If sponge coke meets strict property specifications, it is

considered anode grade sponge coke suitable for calcination for use in making carbon anodes

for the aluminum industry. Otherwise, if sponge coke meets the more lenient fuel grade

specifications, it can be used in its raw form for fuel. The biggest problem for refineries

producing anode grade sponge coke is obtaining the low volatile matter (VM) required.

3.2.3.Needle Coke :

Needle coke, named for its needle-like structure, is produced from feedstocks without

asphaltenes present, normally FCCU decant oils. Needle coke is the premier coke, used in

graphite electrode manufacturing (used in steel arc furnaces) and commands a high price

(calcined ultra-premium non-puffing, $500 per ton); but needle coke requires special

feedstocks, special coking, and special calcination to obtain the optimum properties that it

12

requires. The Shea patent on needle coke [12] gives an accurate description of the formation

of needle coke, still relevant today. Most needle coke is produced from hydrodesulfurized

decant oil (due to the low sulfur requirement for non-puffing coke, that can be nearly flash

graphitized in the new direct current (DC) length-wise graphitization method, without

splitting the electrode). The principle requirement for needle coke is that the CTE must be 2.0

or below (low CTE is required to prevent spalling due to the thermal stresses on the tip of the

electrode which can be as high as 20000C/cm). Needle coke must have low sulfur (<0.6 wt%)

and nitrogen contents in order to be non-puffing during graphitization to 29000C(measured by

a special dynamic puffing test that is proprietary). Needle coke must also have a maximum

amount of coarse sizing (>6 mm), a minimum amount of fines (<1 mm), good density (>78

grams/100 cc; 4/6 mesh test), low ash content (<0.3%; any ash leaves a void when

graphitized), and a high real density (2.13 grams/cc)

3.3 USES OF PETROLEUM COKE

3.3.1 Fuel Coke.Fuel grade coke (shot or sponge) is used in the production of cement and

with fluidized bed boilers (using limestone for sulfur removal) for generation of steam and

electricity. The important properties for pulverized fuel coke is the cost per BTU, high HGI,

and sulfur content. Vanadium in petroleum coke does not cause corrosion on boiler tubes as

does vanadium in heavy fuel oil.

3.3.2 Metallurgy Uses. Some raw petroleum coke, if the sulfur is low enough, can be

blended into feed for slot ovens which produce blast furnace coke. Petroleum coke increases

the physical strength and density of the coke when blended with coal.

3.3.3 Gasification. Partial oxidation of petroleum coke in a gasification process enables raw

petroleum coke to be used to produce steam, electricity, or gas feedstocks for the

petrochemicals industry.

13

3.3.4 Calcined Petroleum Coke - Other Uses

Some calcined petroleum coke is used in production of titanium dioxide (in the chloride

process), production of carbon monoxide for production of plastics, as a feedstock for

continuous particle thermal desulfurization for special low sulfur carbon raiser (steel ladle

additive), or as carbon raiser in cast iron and steel making

14

CHAPTER 4

PROCESS DESCRIPTION—DELAYED COKING

Coke is industrially prepared mainly by delayed coking process. The delayed coking process

was developed to minimize refinery yields of residual fuel oil by severe thermal cracking of

stocks such as vacuum residuals, aromatic gas oils, and thermal tars. In early refineries,

severe thermal cracking of such stocks resulted in unwanted deposition of coke in the heaters.

By gradual evolution of the art it was found that heaters could be designed to raise residual

stock temperatures above the coking point without significant coke formation in the heaters.

This required high velocities (minimum retention time) in the heaters. Providing an insulated

surge drum on the heater effluent allowed sufficient time for the coking to take place before

subsequent processing, hence the term ‘‘delayed coking.’’ Typically furnace outlet

temperatures range from 900–930°F (482–500°C). The higher the outlet temperature, the

greater the tendency to produce shot coke

and the shorter the time before the furnace tubes have to be decoked. Usually furnace tubes

have to be decoked every three to five months. Hot fresh liquid feed is charged to the

fractionator two to four trays above the bottom vapor zone. This accomplishes the following:

1. The hot vapors from the coke drum are quenched by the cooler feed liquid thus preventing

any significant amount of coke formation in the fractionator and simultaneously condensing a

portion of the heavy ends which are recycled.

2. Any remaining material lighter than the desired coke drum feed is stripped (vaporized)

from the fresh liquid feed.

3. The fresh feed liquid is further preheated making the process more energy efficient. Vapors

from the top of the coke drum return to the base of the fractionator. These vapors consist of

steam and the products of the thermal cracking reaction: gas, naphtha, and gas oils. The

vapors flow up through the quench trays previously described. Above the fresh feed entry in

the fractionator there are usually two or three additional trays below the gas oil drawoff tray.

These trays are refluxed with partially cooled gas oil in order to provide fine trim control of

the gas oil end point and to minimize entrainment of any fresh feed liquid or recycle liquid

into the gas oil product. The gas oil side draw is a conventional configuration employing a

15

six- to eight-tray stripper with steam introduced under the bottom tray for vaporization of

light ends to control the initial boiling point (IBP) of the gas oil. Steam and vaporized light

ends are returned from the top of the gas oil stripper to the fractionator one or two trays above

the draw tray. A pump-around reflux system is provided at the draw tray to recover heat at a

high temperature level and minimize the low-temperature-level heat removed by the

overhead condenser. This low-temperature-level heat cannot normally be recovered by heat

exchange and is rejected to the atmosphere through a water cooling tower or aerial coolers.

Eight to ten trays are generally used between the gas-oil draw and the naphtha draw or

column top. If a naphtha side draw is employed, additional trays are required above the

naphtha draw tray.

4.1 Coke Removal—Delayed Coking

When the coke drum in service is filled to a safe margin from the top, the heater effluent is

switched to the empty coke drum and the full drum is isolated, steamed to remove

hydrocarbon vapors, cooled by filling with water, opened, drained, and the coke removed.

The decoking operation is accomplished in some plants by a mechanical drill or reamer [7],

however most plants use a hydraulic system. The hydraulic system is simply a number of

high pressure [2,000 to 4,500 psig (13,800 to 31,000 kPa)] water jets which are lowered into

the coke bed on a rotating drill stem. A small diameter hole [18 to 24 in. (45 to 60 cm) in

diameter] called a ‘‘rat hole’’ is first cut all the way through the bed from top to bottom using

a special jet. This is done to allow the main drill stem to enter and permit movement of coke

and water through the bed. The main bulk of coke is then cut from the drum, usually

beginning at the bottom. Some operators prefer to begin at the top of drum to avoid the

chance of dropping large pieces of coke which can trap the drill stem or cause problems in

subsequent coke handling facilities. Today some operators use a technique referred to as

‘‘chipping’’ the coke out of the drum. In this technique, the cutting bit is repeatedly

transferred back and forth from top to bottom as the hydraulic bit rotates, and the coke is cut

from the center to the wall. This reduces cutting time, produces fewer fines, and eliminates

the problem of the bit being trapped. The coke which falls from the drum is often collected

directly in railroad cars. Alternatively, it is sluiced or pumped as a water slurry to a stockpile

or conveyed by belt.

16

PROCESS DIAGRAM

Figure 1 process flow diagram

Technological devices and equipment:

1, 6, 12-15 - pumps;2, 3 - tube furnaces;4 - receiver;5, 5 '- delayed coking drums;

7 - four-way valves;8, 19, 21 - air-cooled heat exchangers;9 - distillation column;

10, 11 - stripping columns;16 - water cooler;17 - gas-water-separator;18, 20 - heat

exchangers

17

CHAPTER 5

MATERIAL SAFETY DATA SHEET

CHEMICAL PRODUCT: Petroleum Coke

COMPOSITION AND INFORMATION ON INGREDIENTS: A solid, carbonaceous

material resulting from the thermal decomposition of petroleum residue; remaining

hydrocarbons have a very high carbon to hydrogen ratio

HAZARDS IDENTIFICATION:

EYES: Contact may cause slight to moderate irritation.

SKIN: May cause slight to moderate irritation with prolonged or repeated contact.

INGESTION: Low order of oral toxicity. Not an expected route of exposure under most

conditions. However, good personal hygiene should be practiced to minimize ingestion (such

as from hands).

INHALATION: Inhalation of excessive dust concentrations may be irritating to the nose,

mouth, throat, and lungs.

CHRONIC and CARCINOGENICITY: Repeated chronic inhalation exposure may cause

impaired lung function. There is no evidence that such exposures cause pneumoconiosis,

carcinogenicity, or other chronic health effects

18

FIRST AID MEASURES:

EYES: In case of contact with eyes, immediately flush with clean, low-pressure water for at

least 15 min. hold eyelids open to ensure adequate flushing. Seek medical attention.

SKIN: Remove contaminated clothing. Wash contaminated areas thoroughly with soap and

water or waterless hand cleanser. Obtain medical attention if irritation or redness develops.

INGESTION: Obtain medical attention if large amounts are ingested.

INHALATION: Remove person to fresh air. If person is not breathing provide artificial

respiration. If necessary, provide additional oxygen once breathing is restored if trained to do

so. Seek medical attention immediately

FIRE FIGHTING MEASURES

FIRE AND EXPLOSION HAZARDS: Product will burn. In very large quantities,

spontaneous heating and combustion (smoldering) may occur.

EXTINGUISHING MEDIA: Water, foam, carbon dioxide, or dry chemical.

FIRE FIGHTING INSTRUCTIONS: Small fires in the incipient (beginning) stage may

typically be extinguished using handheld portable fire extinguishers and other fire fighting

equipment. Large fires are best extinguished with water. Surfactant (foam or soap) in water

may be effective in reaching deep, smoldering fires (such as in coke pile). Fire fighting

activities that may result in potential exposure to high heat, smoke or toxic by-products of

combustion should require NIOSH/MSHA- approved pressure-demand self-contained

breathing apparatus with full face piece and full protective clothing.

19

TOXICOLOGICAL PROPERTIES

ACUTE TOXICITY:

Acute Dermal (rabbits) LD50: > 2 g/kg

Acute Oral (rats) LD50: > 2 g/kg

Primary Dermal Irritation: slightly irritating (rabbits)

Draize Eye Irritation: practically non-irritating (rabbits)

CHRONIC EFFECTS AND CARCINOGENICITY

Carcinogenicity: OSHA: NO IARC: NO NTP: NO ACGIH: NO

Repeated inhalation of the petroleum coke dust (10.2 and 30.7 mg/m3) over a two-year

period resulted in lung damage typical of high dust exposure including inflammation and

scarring in rats. Similar exposures in monkeys did not produce similar lung effects. There

was no observation of a carcinogenic effect at any dose following a lifetime exposure. There

is no evidence of pneumoconiosis or carcinogenicity in human.

EXPOSURE CONTROLS and PERSONAL PROTECTION EXPOSURE LIMITS

ENGINEERING CONTROLS: Use adequate ventilation to keep dust concentrations of this

product below occupational exposure limits.

EYE/FACE PROTECTION: Chemical splash or dust goggles are recommended where dust

may be generated.

SKIN PROTECTION: Avoid repeated or prolonged skin contact. Gloves and skin protection

are recommended for repeated/prolonged contact. Disposable clothing such as Tyvek®

(DuPont) may be warranted to minimize skin and clothing contamination, depending on the

work to be performed.

RESPIRATORY PROTECTION:A NIOSH/ MSHA-approved air-purifying respirator with

particulate classification N-95 or greater filter cartridges or canister may be permissible under

certain circumstances where airborne concentrations are or may be expected to exceed

20

exposure limits or for odour or irritation. Protection provided by air-purifying respirators is

limited. Refer to OSHA 29 CFR 1910.134, ANSI Z88.2-1992, NIOSH Respirator Decision

Logic, and the manufacturer for additional guidance on respiratory protection selection.

Use a positive pressure, air-supplied respirator if there is a potential for uncontrolled release,

exposure levels are not known, in oxygen-deficient atmospheres, or any other circumstance

where an air-purifying respirator may not provide adequate protection.

WORK/HYGIENIC PRACTICES:Use good personal hygiene practices. Avoid repeated

and/or prolonged skin exposure. Wash hands with soap and water before eating, drinking,

smoking, or using toilet facilities. Do not allow eating, drinking, or smoking in the work area.

As with any dust, remove contaminated clothing and launder before reuse.

21

CHAPTER 6MATERIAL BALANCE

FEED inlet in iocl refinary is – 1.4MMTPA

Table 2 Overall conversion [6]

Sr. No. OVERALL PRODUCTS Case1A Wt%(VR+RCO)1 COKE PRODUCT GAS (FUEL GAS) 2.562 C3/C4 MIX LPG 2.993 COKER NAPHTHA 7.694 MIDDLE DISTILLATE(LCGO) 23.085 HCGO 36.756 COKE 14.537 OTHER BY PRODUCTS 12.4

6.1 Balance across coke drum

Figure 2 balance across coke drum

Feed = 1.4*10^9 kg/h = 1.4*10^9/ (365*24) =159817 kg/h

Coke produced = 14.53 % of feed = 159817*14.53/100 = 23221 kg/h

22

Line to the fractionator = 85.47% of feed = 85.47*159817/100=136596kg/h

Total mass in = 159817kg/h

Total mass out = 23221+136596=159817kg/h

Hence Mass in = mass out

6.2 Balance across fractionator

Figure 3 balance across fractionator


Fuel gas produced is 3 % of feed=3*136596/100=4098kg/h

LPG gas produced is 3.5 % of feed=3.5*136596/100=4780kg/h

Coker naphtha is 9 % of feed=9*136596/100=12293kg/h

LCGO is 27 % of feed=27*136596/100=36801kg/h

HCGO is 43 % of feed=43*136596/100=58753 kg/h

Bottom product is 14.5 % of feed=14.5*1365967/100=19806kg/h

Mass in =136596kg/h

Mass out = 4098+4780+12293+36801+58753+19806=136596kg/h

Hence Mass in = mass out

23

Table 3 COKE COMPOSITION IN PRODUCT STREAM (6)

6.3 Overall material balance

Feed = 1.4*10^9 kg/h = 1.4*10^9/(365*24) =159817 kg/h

Coke produced = 14.53 % of feed = 159817*14.53/100 = 23221 kg/h

This is 88.9% pure so % of carbon in it = 23221*88.09/100 = 20623 kg/h

% of hydrogen in coke = 3.9% = 23221*3.9/100 = 905 kg/h

% of nitrogen in coke = 2.2% = 2.2*23221/100 = 510kg/h

% of sulfer in coke = 2.1%= 2.1*23221/100=487kg/h

%of oxygen =1.3%=1.3*23221/100=302kg/h

% of ash =1.6%=1.6*23221/100=371kg/h


Fuel gas produced is 2.56 % of feed=2.56*159817/100=4098kg/h

LPG gas produced is 2.99 % of feed=2.99*159817/100=4780kg/h

Coker naphtha is 7.69 % of feed=7.69*159817/100=12293kg/h

LCGO is 23.08 % of feed=23.08*159817/100=36801kg/h

HCGO is 36.75 % of feed=36.05*159817/100=58753 kg/h

Bottom product is12.4 % of feed=7.69*159817/100=19806kg/h

Total mass in =159817kg/h

24

Total mass out=4098+4780+12293+36801+58753+19806+371+302+487+105+905+20623

= 159817kg/h

Hence Mass in =mass out

25

Chapter 7

ENERGY BALANCE

7.1 Energy balance across furnace

Table 4 data for furnace [6]

Radiant/ convection

Service Process fluid

Flow rate, kg/hr

Liq. (in/out)

242,084/169,184

Vap. (in/out)

0,0/72,800

Pressure , kg/cm2g

inlet 34.5outlet 6.3

Temperature ,k inlet 499outlet 777

Mass flow rate = 242087 kg/h temperature in =499K temperature out=777K

Mass absorbed=242084-169184-72800=100kgHeat capacity of liquid = 8090kg/hHeat absorption = mCp∆T=100*8090*(777-499)=224.9*106J/hr = 53.81Mcal/hrHeat in = 242084*8090*(777-499)/4.18=1.302*1011cal/hrHeat out = (169184+72800)*8090*(777-499)/4.18=1.3091*1011cal/hrHence Heat in –Heat out =Heat absorbed

26

Figure 5 Delayed Coker Charge Heater 4 Pass - Single Fired

7.2 ENERGY BALANCE FOR COKE DRUM

Table 5 data for coke drum [6]

INLET

TEMPRATURE

OUTLET

TEMPERATURE

FLOW RATE

IN(Kg/Hr)

FEED

TEMPERATURE(0C)

500 426 159817

Heat load = mCp∆T = 159817*2500*(500-426)/3600 = 8212 KW

27

7.3 Energy balance across fractionator [5]

Table 6 Data of hot and cold streams in HEN retrofit of the coking unit

1. Heavy gas oil, heavy gas oil pump around and quenching oil

Mass flow rate = 58050kg/h heat capacity = 2986 J/Kg-K

Inlet temperature = 2300C outlet temperature = 3400C

So, Heat load = mCp∆T =58050*2986*(340-230)/3600=5297KW

2. Heavy gas oil and heavy gas oil pump around



So, Heat load = mCp∆T =50050*2647*(230-220)/3600=368 KW

3. Heavy gas oil

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4. Diesel and lean absorption oil



So, Heat load = mCp∆T = 30550*4536*(228-60)/3600=6467 KW

5. Lean absorption oil




6. Top pump around

Mass flow rate = 29000 kg/h heat capacity = 2217 J/Kg-K



7. Intermediate pumparound




8. Overhead vapors




9. Fresh feed stocks




10. Feeds to convective section




11. Feeds to radiation house

Mass flow rate = 75000 kg/h heat capacity = 3733 J/Kg-K


29


12. Steam of 1.0MPa




13. Preheating of softened water




14. Water injected into tubes

Mass flow rate = 3200 kg/h heat capacity = 4188.5 J/Kg-K


So, Heat load = mCpdt =3200*24188.5*(170-40)/3600=484KW

15. Deaerated water




16. Recycling mediumwater



So, Heat load =mCp∆T =250000*4186*(65-40)/3600=7205KW

Total energy in =5540+5297+368+3180+3467 +5065+185 +1250 =24352

Total energy out=2121 ++4320 +9720 + +698 +455 +7205=24352

Hence Energy in = energy out

30

Figure 4 Modified flowsheet for preheating of feedstocks (1—fractionating column; 2

—coke drums; 3—convectionsection; 4—radiation house)

31

REFERENCES

[1] Jones DSJ. Elements of petroleum processing. New York: J. Wiley & Sons; 1995.

[2] Ballut AA. Heat recovery analysis of an existing crude distillation unit. Heat Recovery

Systems & CHP1986;6:361–7.

[3] Ballut AA. Energy conservation in a catalytic reforming plant. Heat Recovery Systems &

CHP 1989;9:493–7.

[4] Hua B, Shen JF. The energy synthesis of fractionating tower networks.Proceedings of the

4th International SymposiumonProcess System Engineering, Canada.Design.Montebello, vol.

I. 1991, p. I.12.1–I.12.14.

[5] Q.L. Chen, Q.H. Yin, S.P. Wang, B. Hua,Energy-use analysis and improvement

for delayed coking units ,Energy 29 (2004) 2225–2237

[6] Indian Oil Cooperation limited Delayed Coking Unit Process Manual

[7] A. Raðenoviæ, K. Terziæ, Microstructure and physical-chemical properties of petroleum coke as carburizer, NAFTA 61 (3) 136-139 (2010)

32

project report on industrial production of coke

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