PRESENTATION ON REFINERY UNITS DESCRIPTION

Presented By:-

ARNAB CHAKRABORTY

Refinery Configuration

Refinery Units

• CDU / VDU/ NSU(Naph. Stablizn Unit)

• NHT, CCR, Isomerization [MS Block]

• DHDT

• VGO-HDT

• FCC-PC, PRU & FCC

• LPG/FG/Naphtha Treaters

• Delayed Coker Unit

• Polypropylene Unit

• Sulphur Block

• HRU

• HGU

• ATF Merox

CDU / VDU Plant Details

Unit Objective:

To separate crude oil into different products

by boiling point differences & Prepare feed

for secondary processing units.

Naphtha Hydrotreating Unit Details

Product:

Light Naphtha to Isomerization Unit Feed

Heavy Naphtha to CCR Unit Feed

NHT CONTD…..

• Heavy Naptha cut from the atmospheric crude oil distillation column in a refinery issent to a ‘Naphtha Hydrotreater Unit’. After the hydrotreater unit, naphtha is sent toan isomerisation unit or a catalytic reformer unit, which often use reformingcatalysts. Most reforming catalysts contain platinum as the active material. Sulphurand nitrogen compounds present in naphtha cut from atmospheric distillationcolumn can deactivate the catalyst and must be removed prior to catalyticreforming.

• Purpose of the naphtha hydrotrater unit is to remove sulphur and nitrogencompounds. The naphtha hydro treating unit uses a cobalt-molybdenum catalyst toremove sulphur by converting it to hydrogen sulphide that is removed along withunreacted hydrogen. Some of the hydrogen sulphide-hydrogen mixture is recycledback to the reactor to utilize the unreacted hydrogen, using a compressor.

• Reactor conditions for naphtha hydrotreater unit are around 400-500˚F (205-260˚C)and pressure of 350-650 psi (25-45 bar). As coke deposits on the catalyst,reactor temperature must be raised. Once the reactor temperature reaches ~750˚F(400˚C), the unit is scheduled for shutdown and catalyst replacement.

Isomerization Unit Details

• There are two distinct isomerization processes, butane (C4) and pentane/hexane

(C5/C6) Isomerization is a process in petroleum refining that converts n-butane, n-

pentane and n-hexane into their respective isoparaffins of substantially higher

octane number. The straight-chain paraffins are converted to their branched-chain

counterparts whose component atoms are the same but are arranged in a different

geometric structure. Isomerization is important for the conversion of n-butane into

isobutane, to provide additional feedstock for alkylation units, and the conversion

of normal pentanes and hexanes into higher branched isomers for gasoline

blending. Isomerization is similar to catalytic reforming in that the hydrocarbon

molecules are rearranged, but unlike catalytic reforming, isomerization just

converts normal paraffins to isoparaffins.

• Butane isomerization produces feedstock for alkylation. Aluminum chloride

catalyst plus hydrogen chloride are universally used for the low-temperature

processes. Platinum or another metal catalyst is used for the higher-temperature

processes. In a typical low-temperature process, the feed to the isomerization plant

is n-butane or mixed butanes mixed with hydrogen (to inhibit olefin formation) and

passed to the reactor at 230°-340° F and 200-300 psi. Hydrogen is flashed off in a

high-pressure separator and the hydrogen chloride removed in a stripper column.

CONTD....

The resultant butane mixture is sent to a fractionator (deisobutanizer) to separate n-

butane from the isobutane product.

• Pentane/hexane isomerization increases the octane number of the light gasoline

components n-pentane and n-hexane, which are found in abundance in straight-run

gasoline. In a typical C5/C6 isomerization process, dried and desulfurized feedstock

is mixed with a small amount of organic chloride and recycled hydrogen, and then

heated to reactor temperature. It is then passed over supported-metal catalyst in the

first reactor where benzene and olefins are hydrogenated. The feed next goes to the

isomerization reactor where the paraffins are catalytically isomerized to

isoparaffins. The reactor effluent is then cooled and subsequently separated in the

product separator into two streams: a liquid product (isomerate) and a recycle

hydrogen-gas stream. The isomerate is washed (caustic and water), acid stripped,

and stabilized before going to storage.

•

Simplified block diagram

CCR Unit Details

Unit Objective: The purpose of Continuous Catalytic Reformer Unit is to produce high

octane aromatics from paraffin and naphthenes for use as a high octane blending

component.

Reforming : Reforming involves conversion of low octane paraffinic & naphthenic

compounds to aromatics.

Feed Input:

• Hydrotreated Heavy Naphtha cut from Naphtha Hydrotreating unit

• Off gas from Isomerization Unit

Product Details:

• Reformate

• LPG

• Hydrogen

Simplified block diagram

DHDT Plant Details

Process Description:-

• In Diesel hydrodesulphurization/hydrotreating process, diesel feed is mixed with

recycle Hydrogen over a catalyst bed in a trickle bed reactor at temperature of 290-

400°C and pressure of 35-125 bar.

• The main chemical reactions in DHDS/DHDT are hydrodesulphurization(HDS),

hydrodenitrification (HDN), and aromatic and olefin saturation. These reactions are

carried on bi-functional catalysts.

• Reactor effluent is separated into gas and liquid in a separator. Gas is recycled back

to the reactor after amine wash along with make-up Hydrogen and liquid is sent to

the stripper for removal of light gases and H2S.

Unit Objective:

The process objective is to maximize production of diesel to meet the Euro IV

specifications.

Feed Input:

Mixture of LGO, HGO, Vacuum Diesel, LKO & HKO, Heavy Naphtha from

CDU/VDU, Coker Naphtha, LCGO from DCU, LCO from FCC Unit and DSO rich

stream from the LPG treating Unit

Simplified flow diagram of DHDT

VGO HDT Plant Details

Unit Objective:

The main objective of the unit is to produce hydro treated vacuum gas oil having

desired level of hydrogen, low sulphur and low nitrogen for the various design feed

cases. The hydro treated VGO is feedstock for the FCC (Petrochemical) unit.

Feed Input:

The feed stock of this unit is a mixture of Straight Run VGO from CDU/VDU and

HCGO from DCU unit.

VGO-HDT process flow diagram

FCCU Plant Details

Unit Objective:

The Fluidized Catalytic Cracking unit Petrochemical Complex is a Deep catalytic

cracking unit. The main objective of the unit is to produce feeds to various units

like PPU, M S Block & Offsite.

Feed Input:

Mix of straight run VGO and HCGO from CDU/VDU and DCU .

FCCU Product Details:• Propylene to PPU• Fuel Gas to FG Treating Unit• LPG to LPG Treating Unit• LCN / MCN Naphtha to MS Block• LCN/MCN to MS Blending in Offsite

Simplified block diagram

HGU Plant Details

Unit Objective: To Generate Hydrogen of High Purity Required for Hydro-

processing Units of Refinery (NHT, DHDT, VGOHDT), ISOMER, PP & SRU

TGT.

Feed Input: SR Naphtha from NSU & DHDT Naphtha from DHDT

Product: Hydrogen for DHDT, VGO HDT, PPU, SRU, NHT, HRU

PPU Plant Details

Unit Objective: objective of Polypropylene (PPU) unit is to produce Polypropylenefrom Propylene,

Polypropylene: Polypropylene is a long chain polymer made from propylenemonomers. After exposing the propylene to both heat and pressure with an activecatalyst, the propylene monomers combine to form a long chain polymer.Polypropylene is a thermoplastic polymer.

Feed Input: Propylene from Propylene Recovery Unit of FCCU & PropyleneMounded bullets

Product: Polypropylene Polymer

Uses of Polypropylene: Fibers, Automobiles plastic, Wires and cables etc

SWS Unit Details

Unit Objective: The process objective of SWS Unit is to process Sour water streams

generated in refinery process units CDU/VDU, DCU, Flare KOD, ARU, SRU-

TGTU, HGU and DCCU for Single Stage Stripper. Sour Water streams from

VGOHDT and NHTU for Two stage stripper for removal of H2S and NH3.

Feed Input:

Sour Water Stripper – I (SWS-I) : Sour water from CDU/VDU, DCU, Flare KOD,

ARU, TGTU, FFCU

Sour Water Stripper –II (SWS-II) : Sour water from VGO HDT, DHDT, NHTU

Product:

Stripped water to effluent treatment plant or water to CDU/VDU, FCCU, DCU.

Stripped water to effluent treatment plant or water to VGO DHT, DHDT, NHTU

Amine Regeneration Unit Details

Gases containing H2S or both H2S and CO2 are commonly referred to as sour gases

or acid gases in the hydrocarbon processing industries.

A typical amine gas treating process (as shown in the flow diagram (below)

includes an absorber unit and a regenerator unit as well as accessory equipment.

In the absorber, the downflowing amine solution absorbs H2S and CO2 from the

upflowing sour gas to produce a sweetened gas stream (i.e., a gas free of hydrogen

sulfide and carbon dioxide) as a product and an amine solution rich in the absorbed

acid gases. The resultant "rich" amine is then routed into the regenerator (a stripper

with a reboiler) to produce regenerated or "lean" amine that is recycled for reuse in

the absorber. The stripped overhead gas from the regenerator is concentrated H2S

and CO2. In oil refineries, that stripped gas is mostly H2S, much of which often

comes from a sulfur-removing process called hydrodesulfurization. This H2S-rich

stripped gas stream is then usually routed into a Claus process to convert it into

elemental sulfur.

CONTD....

Other plants or units at a glance

Sulphur regeneration unit:-

This unit produces sulphur from the H2S stream and later on the product of this unit

is sold off.

RWTP plant:- : Raw Water Treatment Plant (RWTP) produce filtered and treated

water to meet the requirements of: Cooling water make-up, DM plant feed,

Drinking water, Service water.

Effluent Treatment Plant :-ETP treats effluent water received from various units in

refinery and produce treated water for reuse in Refinery.

RO DM plant :-RO DM is a centralized facility for producing DM water for the

Refinery complex. DM water is required for following purposes: Boiler feed water

makeup for generation of steam, Process water for dilution of chemicals, washing

etc.

Flare System Details

Flare system Objective:

The flare system is provided for safe disposal of combustible, toxic gases which, are

relieved from process plants and off sites during start - up, shutdown, normal

operation or in case of an emergency such as:• Cooling water failure • General Power failure• External fire case• Any other operational failure• Blocked outlet• Reflux failure• Local power failure• Tube rupture

The refinery complex has two flare systems, one for Hydrocarbon flare for process units & off-sites handling hydrocarbon and the other for the sulphur block handling sour flare.

THANK YOU