HR VDU Process

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Vacuum Distillation Unit - Process Sujit K Ghosh Igniting Minds... Energizing Lives… Haldia Refinery

Transcript of HR VDU Process

Page 1: HR VDU Process

Vacuum Distillation Unit

- Process

Sujit K Ghosh

Igniting Minds... Energizing Lives…Haldia Refinery

Page 2: HR VDU Process

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Introduction: Refinery Overview

• Refining Objective:

High volume Fuels / Lube production

Flexible operation for different crudes

Proactive on environmental issues

Maximize higher value distillate yield

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Introduction: Refinery Overview

• RefineryTypes: Simple:

Processing specific range of crude to middle distillatesCDU & VDU, FCCU / Hydrocracker, Catalytic Reformer,

Hydrogen Plant Complex:

Processing variety of crude making a range of high value added products

CDU & VDU, Visbreaker, Lube extraction, FCCU, Delayed Coker, Catalytic Reformer, Sulphur Plant, Bitumen Plant

Integrated:Refinery + Petrochemical

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Refinery Feed Stock

• Crude Oil:– mixture of large number of hydrocarbons

1. Paraffins : normal and iso paraffins Methane, Ethane, Butane, iso-butane

2. Napthenes : Cycloalkanes / Sat. ring structure Methyl cyclo pentane

3. Aromatics : Benzene Ring & its derivatives Benzene, Toluene

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Refinery Feed Stock

• Crude Assay:– Used to evaluate crude for processing

Crude assay Determines Refinery Configuration Product Yield Analysis

– Assay Content: Key Crude oil properties Boiling Point curve including properties of

fractions Chracterization factor (k) Density Curve Sulphur & Nitrogen content Other contaminants

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Vacuum Distillation

• Why Vacuum unit ?– Further fractionation of Reduced Crude Oil

(RCO) ex ADU/CDU residue to get heavier distillates :1. For Lube feed stock 2. For Cracking for high value fuel distillates.

• Recovery of distillates from RCO without Vacuum leads to coking/ cracking and quite energy intensive.

• Higher temperature operation requires :

- Special metallurgy & higher cost.

- Higher protection for equipment & personnel

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Vacuum Distillation

Product Routings:Distillates:

HSD Pool FCC Feed Hydrocracker Feed Lube Processing

Vacuum Residue Lube Processing ( PDA extraction) Visbreaker / Thermal cracker Feed Bitumen

Page 8: HR VDU Process

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Vacuum Distillation

• VDU Types:

Fuel Based Lube BasedPrepares feedstock for FCC, Hydrocracker

Prepares feedstock for Lube Processing

Products:1. Diesel

2. LVGO

3. HVGO

4. Slop

5. Vacuum Residue

Products:1. Gas Oil/Diesel

2. Spindle Oil

3. Light Oil

4. Intermediate Oil

5. Heavy Oil

6. Vacuum Residue

Page 9: HR VDU Process

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Vacuum Distillation

• Vacuum Column Types:

Dry Damp WetTop/Flash Press (mm Hga) 8 / 24 25 / 42 75 /95

Heater Outlet Temp (oC) 420 405 395

Steam Nil Medium Highest

Column Dia Highest Medium Least

Transfer Line Highest Least Medium

Page 10: HR VDU Process

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Vacuum Distillation: Column Types

• Dry Vacuum Features: Higher Heater Outlet temp (COT) More ejector steam

• Wet Vacuum Features: Used for Lube Stocks where Flash Point of Products

are to be met Reduces Heater Outlet temp (COT) requirement due

to partial pressure of steam Lesser Ejector steam Marginally better yield of distillates and

controllability due to steam Economics normally in favour of Damp Vacuum

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Vacuum Distillation: Distillate Specification

• Lube VDU Columns are typically wet vacuum as:

Products need to meet Flash Point spec Better product separation (Sharp Cut) required

KV ([email protected])

Flash Point (oC)

CCR (Wt %)

Gas Oil 1.3-1.6 120 -

Spindle Oil 3.5-3.6 160+ -

Light Oil 6.0 min 200+ -

Inter Oil 9.0-11.0 230-240 -

Heavy Oil 19.0-24.0 240-260 2.4 max

Short Residue 1200+ 300-320 18-20

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VDU: Process Description

Block Diagram:

Pre-heat Train

Furnace

Vacuum Column

SO

IOLO

HO

OSBL

Feed PumpFeed BoosterGO

LN

IN

HN

SR

SO

Ejector

Page 13: HR VDU Process

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What is Vacuum Distillation?

Distillation under vacuum Condition

Page 14: HR VDU Process

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What is Vacuum?

• Any pressure below atmospheric.

How is it expressed?

760 mmHg (a) 1 Atm 0 Kg/cm2 (g)

76 mmHg vac ? (760-76) mmHg absolute

76 mmHg abs ? (760-76) mmHg vac

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Process Description

Five main sections

• The Pre-heat Train

• The Furnace

• The Vacuum Column

• The Side Strippers

• Auxilliary Systems

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Process DescriptionBlock Flow Diagram

Pre-heat Train

Furnace

Vacuum Column

SO

IOLO

HO

Feed PumpFeed BoosterGO

LN

IN

HN

SR

SO

Ejector

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Process Description

The Pre-heat Train configuration is based on

• Heat recovery plan & Product R/D temp before cooler

• Heat Exchanger network configuration as per heat/ temperature potential of streams

• Fouling characteristics, Corossivity of the liquid, flow, viscosity, metallurgy, etc

To Furnace

RCO Feed

SRIOGas Oil

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Process Description

The Furnace

• The required temperature for distillation is achieved in the furnace, the outlet of which directly goes to to the Flash zone of the vacuum distillation column.

• The furnace is a balanced draft type and has the facility of dual firing (both Fuel gas & Fuel oil). Its has got two passes with flow control in each.

• The feed stream from the pre-heat train enters the convection zone followed by the radiation zone.

• Major part of the oil feed to the furnace gets vaporized before entering the vacuum column.

Page 19: HR VDU Process

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Process DescriptionVacuum Column features :

• The distillation and stripping takes place in the vacuum column.• Internals are normally packing/ tray type or both.• Bottom section (stripping) are typically with trays (sieve).• Downcomers are either side/central or both based on liquid load.• Transfer line enters tangentially with impingement plate to reduce impact.• Multi Product Draw.• Side draws are provided with strippers to control flash point• Typical turn down 60-65%• Top and bottom section are SS cladded based on crude property.• Top temperature maintained 15-20 C above the Dew Point• Column Diameter higher as compared to ADU columns (?)• Diameter fixed by capacity and height depends on degree of rectification.

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Process DescriptionThe Vacuum Column

• Two reflux :• Top reflux• Bottom Reflux (Known as Pump Around).

• Pump Around: To remove heat from the column• Key parameters:

– Flash zone temperature/ pressure, – Top temperature/pressure, – Side draw temperatures– PA return flow and tempearure– Bottom tempearture

Page 21: HR VDU Process

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Process Description

The Vacuum Column

Vacuum Distillation

Column

RCO From Furnace

Stripping Steam

To Ejectors

Gas oil

Reflux

S O

LO

IO

HO

Vacuum Slop

SR/VR

Page 22: HR VDU Process

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Process Description

The Side Draw Strippers• Different cuts drawn from the vacuum column are

routed to their respective Stripper columns.• Lighter components in the draws are stripped off

the main product by using superheated steam. ```` Draw Temperatures

• Spindle Oil stripper----- 210-240 C• Light Oil stripper-------- 250-280 C• Inter Oil stripper--------- 300-320 C• Heavy Oil Stripper------ 340-360 C

Page 23: HR VDU Process

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Process Description

The Side Draw Strippers• The bottom products from the Strippers are routed to their

respective storage tanks after exchanging heat with the RCO Feed in the Pre- Heat exchanger Train and then Cooling Water Exchangers.

Page 24: HR VDU Process

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Process Flow Diagrams

Page 25: HR VDU Process

Haldia Refinery Vacuum Distillation Unit PFD(furnace and fractionator circuit)

F-1

P-113/113R

SR to E-11R

CO

ex F-1/F-2

CW

To Ejectors

VS STEAM

GO as refluxex E-2A/B/C

#1

#4

#5

#8

#12

#16

#19

#22

#26

C-1

F-2

Burners

Fuel gas

IFO supply

IFO returnAtomising steam

Fuel gas

IFO supplyIFO returnAtomising steam

RCO Ex E-11

P-10/10R

#4

#1

#1

#1

#1

#4

#4

#4

P-8/7R

P-12/12R

P-5/5R

P-7/7R

HO draw

IO draw

LO draw

PA draw

SO draw

GO draw

SR draw

P-9/9R

Vac slop to E-9

Over Flash

HO Ex P-8/7Ras Demister Wash

Bot Quench Ex H-1A/B

Burners

Furnace recycle Ex p-9/9r

VB steam VS steam

Comb. air To burners

Turbulising steam

Turbulising steam

Turbulising steam

Turbulising steam

Combustion airEx APH

Com

bustion airE

x APH

P-6/6R

E-6A/B/C

P-3/3R

E-128A/B

GO to E-1A/B/C/D

SO toE-123

VS steam

VS steam

VS steam

VS steam

LO to E-121

IO to E-7

HO to E-9

LC-101

LC-03

FC-11

LC-04

LC-05FC-10B

FC-13

FC-12

FC-10AFC-10B

FC-4

FC-5

FC-8

FC-9

FC-102

PC-06 HV-01

DPC-03

FC-209

FC-216FC-217

FC-201

FC-202

C-105

C-2

C-3

C-4

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Haldia RefineryVacuum Distillation Unit PFD

(Feed preheat and product cooling section )

P-1/1R

B-1

E-121

E-1A

E-1B

E-1C

E-1D

E-2AE-2B

E-2C

E-123

E-127

E-14A/B

E-6A

E-6BE-6C

E-4B

E-4A E-122A/B

E-7

E-9

E-11

RCO Ex tanks

LO Ex P-5/5R

GO Ex P-3/3R

SO Ex P-7/7R

PA Ex P-6/6R

IO Ex P-12/12R

HO Ex P-8/7R

SR Ex P-10/10R

H-1A H-1B

DM water

To VB steamheader

CW To TK-761

GO to R/D

GO to top reflux

CWCW

CW

CW

RCO to P-113/113R suction

SO to R/D

E-10

TW

E-125A/B IO to R/D

HO to R/D TW

TW

TW

SR to R/D

E-126A/B

E-124A/B

Pump Around To # 18 of C-1

IO to VBU

FC-20

FC-21LO R/D

To Tar

To VBU

FC-15

FC-19 FC-23A

FC-22FC

-23

To HSD

To Tar

To TK-761

To VBU

FC-25

FC-24

FC-27

FC-26

To R/D

To VBU

FC-12FC-28

LC-02

TC-06

Vac slop to PDA

Vac slop Ex P-9/9R

HO Ex P-8/7R

To PDA

To VBU

Bot quench

Page 27: HR VDU Process

Haldia RefineryVacuum Distillation Unit PFD

(Vacuum System)

E-128A

CW

#19

#22#26

E-128B

E-129E-130

31C-1

Cooling Water Inlet Header

Cooling Water Return Header

VM Steam to Ejectors

PEJSEJ

B-2

B-7seal pot

Vent

oil waterBarometric legs

P-101/101R P-102/102R

B-3coaleser

Hot well gas oil to HSD pool

Hot well water to OWS/ DesalterHot well

PC-05

PC-121

VB steam

DM water

P-114A/B/C

E-116A/B/C

E-124A/B/C

E-126A/B

E-125A/B

E-10

Tempered water circuit

B-105SR

HO

IO

Vac Slop

CW

Tempered water

CW CW

CWCW

Page 28: HR VDU Process

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Auxilliary Systems

The VDU has following auxilliary systems

1. The tempered water system

2. Steam generation and SR Cooling

3. Balanced Draft Furnace

4. Battery Limit product lines

5. Pumping systems

6. Vacuum System

Page 29: HR VDU Process

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Auxiliary SystemsThe Tempered Water System :Why?

• Run down temperature @80 C

• Product congealing in nature.

• C/W higher scaling nature above 55 C.

• Less corrosive due to DM water/ Condensate

.

TW vessel

TW pump

SR SR IO HN

TW cooler

C/WMake Up DM Water

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Auxiliary SystemsSteam Generation and SR cooling

• Steam generation reboilers from SR stream.

• SR after Exchanging heat with RCO in 31 E 11 and 31 E 122 A/B enters 31-H- 1A/B where DM water recovers the heat from SR and generates steam at ~5 Kg/ Cm2 g and 151 C.

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Auxiliary SystemsBalance Draft Furnace

Main Features:Process circuit: PHE Convection zone Radiation

ZoneColumnFlue gas Circuit: Radiation Zone, Convection Zone,

APH , ID fan, StackCombustion Air Circuit: FD fan, SCAPH, APH,

BurnersFuel Oil Circuit & Fuel gas circuit

Turbo Steam

Page 32: HR VDU Process

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Auxiliary SystemsBattery Limit and Product lines

Feed, Products and utilities are routed through the Battery Limit.

The product lines are provided with Flow control valves, Level control valves and necessary instrumentations like Temperature Transmitters, Pressure Transmitters, Pressure/ Temperature Gauges etc.

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Auxiliary SystemsVacuum System

Precondensers

Primary ejectors

Secondary ejectors

Seal pot

Barometric legs

Hot Well (HW)

Gas oil recovery system from HW

Page 34: HR VDU Process

Haldia RefineryVacuum Distillation Unit PFD

(Vacuum System)

E-128A

CW

#19

#22

#26

E-128B

E-129

E-130

31C-1

Cooling Water Inlet Header

Cooling Water Return Header

VM Steam to Ejectors

PEJSEJ

B-2

B-7seal pot

Vent

oil waterBarometric legs

P-101/101R P-102/102R

B-3coaleser

Hot well gas oil to HSD pool

Hot well water to OWS/ DesalterHot well

PC-05

PC-121

CW CW

CW

CW