By:Aditya Dembla (071101)

IDD (4th Yr) Dept. Of Chemical Engineering

Presentation On Summer Internship at

IOCL MATHURA

OverviewLOCATION:

IOCL MATHURA is located on NH-2 , between the historic cities of Delhi and Agra,in Mathura, Uttar pradesh.

• Commissioned in January, 1982

• CAPACITY: 8 MMTPA

• A Fortune 500 company. Placed at 125

• Current turnover of Rs. 271,074 crore and profits of Rs. 10,221 crore for the year 2009-10.

• Receives crude oil through the 1870 km long Salaya Mathura Pipeline (SMPL).

• Processes low sulphur crude from Bombay High, imported low sulphur crude from Nigeria, and high sulphur crude from the Middle East.

• Mainly produces middle distillates for Northern India supplied though a 760km long product pipeline to Jalandhar in Punjab via Delhi (MJPL) and 100km long Mathura Tundla Pipeline (MTPL).

• Mathura refinery received “Gold Award” in petroleum Refinery sector from Greentech Foundation, New Delhi, for outstanding achievement in Safety Management in 2009 .

Overview

BUSINESS STRUCTURE OF IOCLDownstream Operations

Recent entry into Petrochemicals, E&P and GAS Business

Plant Layout

PROCESSING UNITS OF MATHURA REFINERY

• Atmospheric & Vacuum Distillation Unit(AVU )

• Visbreaker Unit (VBU)• Fluidized Catalytic Cracking Unit (FCCU)• Continuous Catalytic Reforming Unit (CCRU)• Propylene Recovery Unit (PRU)• Hydrogen Generation Unit ( HGU )• Once Through Hydrocracker Unit (OHCU)• Sulphur Recovery Unit (SRU)• Bitumen Blowing Unit (BBU)• Diesel Hydro Desulphurization Unit (DHDS)• Merox (Mercaptan Oxidation)• Diesel Hydrotreater (DHDT)

1. Liquid Petroleum Gas (LPG) 2. Fuel Oil Products: • Motor Spirit (MS) • Superior Kerosene (SK) • Aviation Turbine Fuel (ATF) • High Speed Diesel (HSD) • Furnace Oil (FO) • Naptha • Gasoline

3. Lube Oil Products4. Other Products: • Slack Wax • Carbon Black Feed Stock • Bitumen • Sulphur• Propylene

PRODUCTS

• New Unit block of Mathura refinery comprises of 4 units namely

HGU (Hydrogen Generation Unit )OHCU (Once Through Hydrocracker

Unit)DHDS (Diesel Hydro Desulfurization Unit

)DHDT (Diesel Hydrotreater Unit)

NEW UNITS

Purpose of the Unit : To generate High purity Hydrogen for

supply to DHDS unit and Hydrocraker Unit.

Project Details:• Capacity of the Unit (MTPA) : 34000• Licensor : Haldor Topsoe,Denmark.• Project Cost : 160 Crores

• PMC Consultant : EIL, Delhi.

HGU (Hydrogen Generation Unit)

FEED: • Naptha(from Arab mixed crude oil)• Or Natural Gas

PRODUCT QUALITY (DESIRED)• H2- 99.99 volume % (minimum)• CO,CH4,CO2 – 15ppm (maximum)

CATALYSTS 1) TK –550 - Hydrogenation catalyst 2) HTZ-3 - S-adsorption catalyst 3 RKNGR - Adiabatic pre reforming

Catalyst 4) R-67-7H - Reforming catalyst 5) LK-811 - MT shift catalyst

HGU (Hydrogen Generation Unit)

Block Flow Diagram

PRE-TREATMENT

PRE-REFORMING

REFORMING SHIFT SECTION PSA

RECYCLE H2

OFF GAS FUEL

FUELSTEAM

H2

DESULFURIZATION• HYDROGENATION ( Hydrogenation of Sulfur contained in

the feed ) • ABSORPTION OF SULFUR (Removal of Sulfur from the feed

)

REFORMING SECTION• FEED MIXING (Mixing of steam and feed after

desulfurization) • ADIABATIC PRE-REFORMING ( hydrocarbons are decomposed

into H2, CO2, CH4 )• TUBULAR REFORMING (Reforming at higher temperatures

possible )

CO-CONVERSION SECTION• GAS PURIFICATION SECTION ( SHIFT REACTION )

CO + H2O CO2 + H2 + heat

PSA UNITS: Purification of gas from reformer to get High purity H2 and offgas containing impurities.

H2 from PSA-I and PSA-II are combined and sent to OHCU/DHDS.

Chemical Reactions :

Desulphurisation section:• RSH+H2 -> RH + H2S• R1S-SR2+3H2 -> R1H+R2H+ 2H2S• R1SR2+2H2 -> R1H+R2H+H2S• COS+H2 -> CO + H2SCatalyst : Co Mo . (TK 550)Normal life : 5years.

H2 mixed with feed and passed over catalystat 380-390 deg C.

H2 rate : 0.13 m3/kg of feed. Feed ‘S’ <200 ppm. Product ‘S’ < 50 ppb.

HGU FEED

HYDROGEN

R-01

DESIGN PRESS. : 42 Kg/cm2 DESIGN TEMP : 430C

HDS section :• Too low a (<350 degree Celcius) temp will

lead to gum formation on catalyst• Temp > 400 deg C will lead to

polymerisation of products leading to coke laydown.

• So ideally we keep the temprature at about 380-390 degree celcius.

Absorption of H2S:• H2S+ZnO ZnS+ H2O • Two absorbers in series with 2 beds each• Chloride guard placed on top of ZnO

catalyst (HTZ-3) to retain any entry of chloride along with feed to protect MT shift catalyst (LK-811).

• Normal life of ZnO catalyst and chloride guard is 6 months.

HGU

16

Design Pressure : 34 Kg/cm2

Design Temp. : 430 C.

GUARD REACTOR

HTZ-3

HTG-1

HTZ-3 : ZnO Catalyst

HTG-1 : Chloride Guard

H2S+ZnO ZnS+H2O

Sulphur Absorbtion

R-02A R-02B

PRE-REFORMING :

• CnHm+nH2O nCO + ( n+m/2) H2 - heat• CH4+H2O CO+ 3H2 -

heat• CO+H2O CO2+H2 + heat

• Desulphurised feed along with surplus H2 is mixed with HP saturated steam and passed over pre-reformer and reformer in series.

• Design Steam/Carbon ratio : 2.5• Normal operating Steam/Carbon ratio : 2.8• If S/C < 1.5, Carbon laydown will be there on

pre-reformer catalyst• If feed Temp > 520 deg C, Carbon laydown will

happen• Normal inlet temp : 490 deg C. Normal range :

470-505 deg C.• If feed temp < 445 deg C, gum formation will

take place.

HGU(Steam)

• Optimum Inlet Temperature. : 490 C• Temp Range at Inlet : 470-505 C.• Temp. > 505 C : Carbon Formation . • Temp. < 470 C : Gum Formation• Steam /Carbon Ratio : 2.5• Ratio < 1.5 : Risk of Carbon Laydown.• Very High : Risk of Oxidation• H2 in Process Gas : 0.13 m3/kg of Steam

• Fixed Bed , Adiabatic Reactor.• Energy Savings.• Low Steam / Carbon Ratio.• Conversion of Heavy H.C’s to CH4.• Reduced Possibility Of Carbon

Formation.• Preheating Reformer Feed to 650 degree

C.

490 ℃

RKNGR (Ni Cat)

R-03

Why pre-reforming and not reforming directly?

Basically there are three reasons for performing pre –reforming:

1) By incorporation of the pre-reformer, considerable energy savings are obtained because heat from the waste heat section of the tubular reformer can be utilized for additional preheating of feed to the tubular reformer.

2) Incorporation of the pre reformer allows operation at a low steam/carbon ratio whereby the mass flow through the plant is reduced.

3) Furthermore the pre-reformer is reducing the possibility of carbon formation in the tubular reformer.

REFORMING :

CH4+H2O CO+ 3H2 - Heat• Gases from prereformer are further heated to 650 deg C and

passed over Reformer tubes containing Reforming catalyst (TOPSOE R67-7H)

• Since there are no heavier Hydrocarbons at the outlet of Pre-reformer, the coking in Reformer is avoided. However when catalyst is poisoned by ‘S’, activity is lost and coke laydown occurs.

• 126 No. of Tubes in furnace design. Tubes of high alloy metallurgy (CrNiNbTi)

• 216 No of Burners in 6 rows of 9 burners each on 4 furnace walls.

• Furnace designed for high heat flux rate. Tube skin temp 990 ℃.

MT SHIFT CONVERTER:• CO+H2O → CO2+H2 + heat

• Catalyst Cu2O reduced to Cu (LK 811 i.e. Oxides of Cu, Zn & Cr.)

• Inlet Temp : 205 deg C, Outlet Temp. 337 0C

• Operating range 200-340 ℃

POISONS :• Sulfur : mostly retained by pre-

reformer/reformer catalysts

• Chloride : HDS outlet monitored to have chloride < 50 ppb using chloride guards

REFORMER205 0C

R-04

• Selective Adsorption of Impurities at High Pressure on Adsorbent.

• Regeneration of Adsorbent at Low Pressure.

• Cyclic Pressure Variation Process

PSA(PRESSURE SWING ADSORPTION)

OHCU(Once Through Hydrocracker Unit)

OBJECTIVE : To process 1.2 MMT/yr of VGO to convert 65% into products

boiling below 370 0C i.e. Diesel, lighter fractions and 35% as unconverted oil i.e. FCC feed.

FEED :Feed to the unit consists of Vacuum gas oil (VGO) 70 % High

sulfur & 30 % low sulfur.

PRODUCTS: The primary products from OHCU are◦ L.P.G◦ Stabilized Light Naphtha◦ Heavy Naphtha◦ Aviation Turbine Fuel (ATF)/ Superior Kerosene (SK)◦ High Speed Diesel (HSD)◦ FCC feed

OHCU

ADVANTAGES OVER OTHER HYDRO-CRACKING PROCESSES:

• Yield of middle distillates is very high.

• Does not yield coke or pitches as by product.

• No post-treatment is required for Hydrocracker products.

Once-through Hydrocracker Unit

THE HYDROCRACKER IS MADE-UP OF FOUR PRINCIPLE SECTIONS:

Make-up Hydrogen compression section◦ The compressed make up hydrogen is combined with hydrogen

recycle gas in the reaction to from reactor feed gas.

Reactor section

◦ In the reactor section, the feedstock is combined with Hydrogen at high temperatures & pressures and is catalytically converted to lighter transportation fuels. The hydrotreating and hydrocracking takes place in the reaction stage.

◦ A high Hydrogen partial pressure is needed to promote hydrocracking reactions and to prevent coking of the catalyst. So excess of Hydrogen is circulated to maintain a high partial pressure.

The Fractionation section◦ To separate reaction section products into off gas,

light naphtha, heavy naphtha, kerosene, diesel and FCC feed.

Light end recovery section◦ Remove Light ends and waters from light

naphtha ,C-2, H2S◦ Separate LPG from light naphtha and treat LPG to

meet the desired specification.

OHCU

Power recovery turbine

(Flasher)

H2 recycle

(FCC feed)

DIESEL HYDRO DESULFURIZATION UNIT (DHDS)

• OBJECTIVE:

Pollution control Producing low sulfur diesel (0.25 w/w%) (as per govt.

directive w.e.f. Oct. 1999.) • FEED: Proportion of straight run LGO, HGO, LVGO.

74% LGO, 21% HGO, 5% LVGO The feed is a mixture of products containing Unsaturated components (diolefins, olefins), Aromatics, Sulfur compounds and Nitrogen compounds.

The Hydrodesulfurisation reaction releases H2S in gaseous hydrocarbon effluents. This H2S removal is achieved by means of a continuous absorption process using a 25% wt. DEA solution.

In addition to the desulfurisation, the diolefins and olefins will be saturated

Denitrification will occur. Denitrification improves the product stability.

The hydrogen is supplied from the hydrogen unit.

The HR-348 and HR-448 are desulfurisation catalysts, it consists of cobalt and molybdenum oxides dispersed on an active alumina. Its fine granulometry and large surface area allow a deep desulfurisation rate.

Lean Amine for absorption operation is available from Amine Regeneration Unit (ARU).

What we basically do in DHDS?

o Feed received from different feed sources namely Diesel Storage tanks and FCC unit.

o Hydrogen recycle join the feed before heat exchangers.

o Feed then enters heater in four passes and then to reactor.

o Vapour phase is sent to high-pressure amine absorber.

o The liquid hydrocarbon under level control is sent as feed to stripper.

o Sweet diesel from bottom of stripper is pumped to storage tank.

PROCESS DESCRIPTION

REACTIONS INVOLVED IN THE REACTOR

1.Desulfurization Reaction:

2. Denitrification Reaction:

3. Deoxygenation (Hydrogenation of C=O bond)

4. Hydrogenation of Olefins & Aromatics

322 NHHRHNHR

SH H-R 2 H H-S-R 22

OHHRHOCHR 22

3222 CHCHRHCHCHR

CATALYSTS USED :

Catalysts consists of NiMo oxides with alumina support;

For R-01:HR-945 For Hydrogenation of Olefins and Aromatics.HR-348 For Desulfurization, Denitrification, and Saturation of Olefins and Aromatics.

For R-02:HR-448 For Desulfurization, Denitrification, and Saturation of Olefins and Aromatics. Alumina Balls ¾” and ¼” dia. . arranged around the 3 catalyst beds to safegaurd catalysts.

BLOCK FLOW DIAGRAM:

280 ⁰C

374 ⁰C

383 ⁰C

126 ⁰C50 kg/cm2

60 ⁰C34 kg/cm2

STRIPPER

DHDT(DIESEL HYDROTREATER)

OBJECTIVE :o To produce a low sulfur diesel product, with substantial

cetane number improvement.

FEED:o Several straight run distillate streams.o Cracked feed from FCC.o A heavy naphtha stream from the Visbreaker unit(VBU).

PRODUCT:o Desulfurized Diesel with reducad sulphur content and

improved ceatne number.o Stabilized Naphtha.

Two main types of chemical reactions, namely :- Refining- Hydrogenation reaction

- 1.Refining Reaction : involve the removal of heteroatoms, namely, sulfur, nitrogen and oxygen. It also includes the saturation reactions of olefins and diolefins.

A)Desulfurization Reaction -Mercaptans, sulfides and disulfides react easily leading to the corresponding saturated or aromatic compounds.Mercaptans : R – SH + H2 R – H + H2S

Sulphides : R-S-R + 2H2 2R – H + H2S

Process :

B) Denitrogenation Reaction

oNH3 is released following a series of reactions : satura-tion of the

ring to which nitrogen is attached and carbon-nitrogen bond scission.

The rate is lower than for the desulfurization reactionThese reaction lead to ammonia formationThese reactions are also exothermic.

2.Hydrogenation Reaction :

oSaturation of aromatic compounds and denitrification of heterocyclic compounds having an aromatic structure.

oThe polynuclear aromatics are first converted to mononuclear

aromatics, which are then converted to naphthene. Aromatics Saturation

+ 3 H2 C6H12