Section 04 - Fractionation

7/27/2019 Section 04 - Fractionation

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FractionationFractionation


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Task Checklist

X Introduction

TOWER SIMULATION

Z Basic Concepts

Z Specifications

DEVICE SELECTION

Z Contacting Devices

Z Tray Hardware Definitions

Z Tray Hydraulics

Z Packing Hydraulics

Z Other Process Considerations

Z Other Tower Internals

Z Tower Revamps


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Did You Know?

Oldest and most important petrochemical manufacturing process

Equipment accounts for 30% of all investments today

Consumes 70% of all energy at plant


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More on Fractionation

Separate feed into products

according to boiling point

Products sent to finished

product tank or further

processed by other units

Multiple products and feeds

common


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Objective Questions

How can you improve separation efficiency?

How do you decide on the optimum number of trays for a new

tower?

What sets a towers operating pressure?

What are my options to increase a towers vapor / liquid handlingcapacity?


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Designers Role

Perform HMB calculations to develop tower loadings

New Towers Select optimum tower size, contacting device, and internals to meet

process requirements

Existing Towers

Select optimum contacting device and internals to improve

performance or expand capacity

Screening - Apply Concepts to Troubleshoot Problems

Prepare Design Package (Consult with Specialist)


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Engineers Toolbox

XOM DP Section III

(Intranet)

Simulation Tool (PRO/II or

HYSIS)

Pegasys ExxonMobil TowerInternals Program - EMoTIP

Fractionation Specialists


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Task Checklist

X Introduction

TOWER SIMULATION

XBasic ConceptsZ Specifications

DEVICE SELECTION



Z Tray Hydraulics




Z Tower Revamps


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Conventional Tower

Reflux Ratio = R / D

R

D


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Rules of Thumb

More Reflux

More Trays More Separation

Lower Pressure


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BINARY DISTILLATION: MCCABE - THIELE DIAGRAM


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MINIMUM REFLUX


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TOTAL REFLUX - MINIMUM STAGES


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Stages Versus Reflux


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Optimum Reflux Ratio


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ESTIMATING ACTUAL REFLUX RATIO AND ACTUAL NUMBER OF STAGES

General Rule of Thumb--

RACTUAL = (1.1 TO 1.35) x R MIN


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Task Checklist

X Introduction

TOWER SIMULATION

X Basic ConceptsXSpecifications

DEVICE SELECTION



Z Tray Hydraulics




Z Tower Revamps


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Factors to consider:

Temperature of available condensing fluid (air, water, etc.)

Wheres the overhead product go?

Is the overhead totally condensed?

Possible Limitations:+ Bottoms temperature (cracking / color)

+ Reboiler

+ Critical Point (poor separation)

How much pressure drop is acceptable?

Operating Pressure


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Operating Temperature

Fixed once product specifications and

pressure are set

Dew Point Calculation

Overhead temp.

Bubble Point Calculations

Bottoms temp.

Flash Calculations

Reflux temp.


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Feed Condition

If not specified, start with bubble

point feed - Then optimize.

Adjust temp. to balance tower

loading

Other Considerations:

Reflux vs. Reboiler Duty / Costs

Quenching


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HIGH FEED TEMPERATURE

L

RECYCLE GAS

COMPRESSORPRODUCT

FUEL GAS CONTROL:

FEED RATE

PRODUCT VAPOR PRESSURE

PRODUCT SULFUR

OVERHEAD DRUM LEVEL

FEED

OVERRIDE

F

A VAPOR PRESSURE

SULFUR


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Simulation Inputs

Feed Rate and Composition

VLE Data Method

Specifications & Control

Variables

Operating Pressure

Initial Guess (If Required)

For Rating: Plant Test Data

Pressure, Temperature Profile

Lab Data (Complete Set of Samples)

Tray Efficiencies

See DP III-I Table 2; Estimates

from Past Designs


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Tower Specif ications

Specifications: usually on product quality or temperatures Can be mathematical

Avoid specifying rate. Better to specify % recovery or fraction.

Condenser temperature

Variables: usually condenser / reboiler duty


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ProII Condensers

Stage 1, if present

Different Types


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ProII Reboilers

Last Stage(s)

Kettle or Thermosiphon

Kettle

Thermosiphon specify if have baffle or not


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KETTLE REBOILER

Advantages:

+ Additional fractionation stage

Disadvantages:

- Low NPSH to downstream pump- Very low hold-up

- Tubes can dry out

- High temperature increase

- Large plot space


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VERTICAL THERMOSIPHON REBOILER

-Advantages:

+ Partial fractionation stage

+ Low plot space

+ Low temperature increase

Disadvantages:

- Partial fractionation stage- High circulation rate

- Pressure drop critical

- Limited duty

- Difficult to clean


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HORIZONTAL THERMOSIPHON REBOILER

-Advantages:+ Partial fractionation stage

+ Large duty

+ Low temperature increase

+ LowerP than vertical

Disadvantages:- Partial fractionation stage

- High circulation rate

- Pressure drop critical

- Large plot space

- Large piping


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Column Stage Summary

Number of Stages Condenser (1)

Theoretical Trays (#)

Can also use Actual Trays * Tray

Efficiency Efficiency will be different above and

below feed

Reboiler (1 or 2)


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Simulation Strategy

Optimize Reflux Ratio, Stages, Feed Condition, and Feed

Location


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Simulation Pitfalls

Save / Backup cases often.

Viscosity (high temperature), otherproperties may need to be verified.

Others?


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SIMULATION RESULTS


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Task Checklist

X Introduction

TOWER SIMULATION

X Basic Concepts

X Specifications

DEVICE SELECTION

XContacting DevicesZ Tray Hardware Definitions

Z Tray Hydraulics


Z Other Process ConsiderationsZ Other Tower Internals

Z Tower Revamps


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Device Categories

Conventional Trays

High Capacity Trays(Proprietary)

Random Packing

Structured Packing

Baffles, Sheds, and Grid


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Valve Up to 5:1 Turndown

5-10% higher capacity over sieve

Marginally higher cost

Not recommended for fouling

services

Jet hExxon Design for High Liquid

Loads

Efficiency ~20% less than sieve

Mainly used in pumparounds

Conventional Trays

Sieve Most Widely Used

2:1 Turndown

Low Cost (Nonproprietary)

Bubble Cap Standard until 1950s

High Cost

Maintenance / Inspection Difficult

Excellent Turndown


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Pumparound Definition

Method to provide towerreflux by cooling tower liquid

Draw-off intermediate liquid

Cool liquid by pumping itthrough heat exchanger

Return liquid to tower

Use trays/packing to return

Can provide high value heat

Reduces OH condenser

duty Reduces furnace duty

Reduces liquid traffic intower

Can reduce tower diameter

Increases tower heightsince pumparound traysare for heat transfer, notfractionation


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High Performance Fixed Valves (Increase vapor handling capacity)

Koch-Glitsch PROVALVE

Directional effect reduces fouling and vapor jetting/entrainment

10-15% jet flood capacity advantage to 1/2 (13mm) sieve trays

Sulzer MVG

High Capacity Trays


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High Capacity Trays (Cont.)

Enhanced Downcomer(Increase vapor handling capacity) Koch-Glitsch

Nye

MaxFrac

SuperFrac

Triton

Sulzer MVG-T

(not shown)


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High Capacity Trays (Cont.)

Multiple Downcomers UOP

MD and ECMD

~20% higher capacity, but lower efficiency

than conventional sieve tray

Limited access; not recommended for

fouling (Very difficult to clean / inspect)

Sulzer Shell HiFi


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MD and ECMD Tray Unit Cells

W t M Hi h C it T I f ti ?


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Want More High Capacity Tray Information?

Read recently released:EE48E2008, Application Guidelines For Debottlenecking Light EndsTowers With Enhanced Capacity Fractionation Trays

R d P ki


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Random Packing

1ST Generation Berl Saddle

Intalox Saddle

Rashig Ring

2ND Generation Pall Ring

Flexirings

Ballast Rings

Slotted Rings

3RD

Generation CMR IMTP

Nutter Ring

Rashig Super-Ring

R d P ki (C t )


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Random Packing (Cont.)

Packing can usually provide higher capacity and better efficiency than

trays.

As size increases, the capacity increases while the pressure drop, cost,and efficiency decrease.

Usually not first choice for new designs

Consider for:

Small tower diameter (


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Packing Warning

Fire Hazard: Some sites prevent hot work above a packed bed

DP III-G (Packing and Grid)

Structured Packing


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Structured Packing

Conventional Koch-Glitsch: Flexipac, Intalox Sulzer: Mellapak

Montz: Montz-Pak Type B1

High Capacity Koch-Glitsch: Flexipac HC, Intalox Sulzer: Mellapak Plus

Montz: Montz-Pak Type M

Structured Packing (Cont )


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Structured Packing (Cont.)

Why Structured Packing?

Lowest pressure drop per stage

Best capacity / efficiency combination device Less sensitive to liquid maldistribution than random packing

Recently, cost is much more competitive with random packing

Why Not Structured Packing?

Not recommended for high pressure towers - above 100 psia (7

kg/cm2) due to poor test results, or where liquid rate exceeds 20

gpm/ft2

(13.6 dm3

/s*m2

) unless application is high pressureaqueous system.

Grid


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Grid

Used for entrainment removal where fouling is too severe for acrinkle wire mesh screen (CWMS)

High Open Area

Prevents plugging

Low Surface Area

Low efficiency

Baffles


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Baffles

Large Open Area

Prevents plugging

Low Liquid Residence Time

Prevents coking

Practice Tower Internal Type


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Practice Tower Internal Type

What type of tower internal would you use for the following? Desuperheating reactor effluent in bottom of a fractionator?

Vacuum fractionator

High pressure light ends tower

24 (610mm) diameter absorber

Recycle gas absorber (remove H2S from H2)

Tail gas absorber (remove H2S from Sulfur Plant effluent)

Pumparound section of large fractionator

Device Selection Criteria


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Device Selection Criteria

Fouling Tendency

Good Liquid & Vapor Handling Capacity

Good Contacting efficiency

Acceptable Pressure Drop

Predictable Turndown Characteristics

Economical

See DP III-A Tables 3-5

Device Selection Procedure


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Device Selection Procedure

New Design

Start with trays, unless pressuredrop is critical. If need low dP,consider 2 (50mm) random packing.

Calculate optimum tray spacing,diameter, and layout (i.e. bubble areaand downcomer dimensions) by trial anderror to avoid downcomer and jet

flood limitations.(Use Pegasys / EMoTIP)

Then select best device type basedon Device Selection Criteria.

(See DP III-A Tables 3&5 Decision Trees)

Dont consider High Capacity Traysfor new towers - Instead IncreaseDiameter, etc.

Revamp

Rate existing contacting device to identify

potential limitations (i.e. downcomer, jet

flood, etc.)

(See Table 1 Design Principles in appropriate

DP III Section)

Identify new layout and device where all

design parameters are satisfied

(Use Pegasys / EMoTIP)

Consider:

Multi-pass Conventional Trays

High Performance Fixed Valves

Enhanced Downcomer Trays

Multiple Downcomer Trays

Packing

Trays vs. Packing


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Trays vs. Packing

XOM DP III-A Table 3D -- Fouling Tendencies

Task Checklist


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as C ec st

X Introduction

TOWER SIMULATION

X Basic Concepts

X Specifications

DEVICE SELECTION

X Contacting Devices

XTray Hardware Definitions

Z Tray Hydraulics


ZOther Process Considerations


Z Tower Revamps

Common Pass Arrangements


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g

Downcomer Types


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yp

Stepped / Sloped: Provide sufficient DC inlet area for adequate vapor / froth

disengagement while maximizing bubble area

Downcomer Expansion


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Can expand downcomer without welding Commonly called Z-bar or downcomer adapter

Exiting Downcomer

Bolting Bar

Exiting Tray Support

Ring

Koch-Glitsch supplied

Downcomer Adapter

Weir Types


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Picketing: Can reduce spray

regime operation by increasing

effective liquid height; Also

used to balance multipass

designs by making their

effective weir lengths the

same.

Downcomer Seal Techniques


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Design should ensure vapor cannot bypass a tray by flowing upward

through the DC resulting in poor efficiency.

Process SealMechanical Seals

Area Definitions


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Also see DP III-A, Figures 12-13

Task Checklist


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X Introduction

TOWER SIMULATION

X Basic Concepts

X Specifications

DEVICE SELECTION


X Tray Hardware Definitions

XTray Hydraulics




Z Tower Revamps

Hydraulic Limitations


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VAPOR

Jet Flooding

Ultimate Capacity

Flow Regimes

Entrainment

LIQUID

Downcomer Backup

Secondary Limitations:

Liquid Rate per Inch of Weir

Downcomer Choking

Velocity Under the Downcomer Downcomer Seal


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FRI VIDEO

Jet Flooding


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At high vapor rates, liquid is

jetted to tray above

Vapor handling limitation; sets

design in most cases

Expressed as Percent;

Rigorously Calculated(See DP III-B / Use Pegasys)

Related to vapor velocity

through the free area

Strong function of:

Tower Diameter

Tray Spacing

Jet Flooding and Efficiency


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XOM Jet Flood Limit

85

Late Breaking News: XOM Jet Flood

Limit now 80% for new designs

Problem Jet Flood


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What steps can we take to reduce jet flood, and what are the

drawback for each?

Ultimate Capacity


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Highest vapor rate tower can handle -- Stokes Law

Cannot be increased by hardware changes; only way to increase

it is by increasing the tower diameter

Flow Regimes


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To Eliminate Spray Regime:

Use Picket Fence Weirs

Increase Open Area

Use Smaller Sized Orifices

Use Valve Trays

Entrainment


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Liquid [drops] carried by the

vapor to the tray above

Design should limit entrainment

to 10% of the tray liquid rate

Function of:

Vapor Rate

Liquid Rate

Tray Spacing

Other Hardware Parameters

Downcomer Backup


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DC froth height expressed as

percent of tray spacing plus the

weir height

DC Filling Components:

hi = inlet head; f(inlet & outlet weir)

ht = total tray dP

hud = head loss under DC;

f(DC Clearance)

hdc = head loss due to two-phase

flow in DC

Percent Downcomer Flood

P f it i t h l t i t fl di lt f


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Performance criteria to see how close a tower is to flooding as a result of

excessive froth height in the downcomer

Represents actual vapor / liquid rates as a percent of the rates which cause 100%

DC Backup

Rigorously Calculated

(See DP III / Use Pegasys)

Flooding Symptoms


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Jet Flooding

Tower unstable

Liquid entrainment intooverhead system; sharp

increase in reflux rate with no

separation improvement

Pressure drop increases sharplywith a small incremental

increase in vapor rate

Separation efficiency gradually

decreases

Downcomer Flooding

Tower unstable, surging

High pressure drop with a smallincrease in either vapor or liquid

rate

Separation efficiency suddenly

decreases

Loss of tower bottoms liquid

level

Problem Downcomer Backup

Wh t t h 2 ff t d filli ?


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What parameter has a 2x affect on downcomer filling?

Name steps we can take to lower downcomer filling, and what

drawbacks for each.

Secondary Liquid Hydraulic Limitations


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Liquid Rate per Inch of Weir The accuracy of the Jet flood and DC Flood correlations can only be

ensured within the range of liquid rates used to develop them.

Downcomer Choking results when the DC inlet area is too small.

Velocity Under the Downcomer

If too high, can produce channeling effect leading to vapor / liquid

maldistribution on the tray.

Downcomer Seal

If not sealed, vapor can bypass the tray and flow upward through the

downcomer resulting in reduced efficiency.

Two types: Mechanical [Static]

Process [Dynamic]

Tray Hydraulics

DP III-B P.20-22

SIEVE TRAY DESIGN PARAMETERS


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DP III-B P.20-22

SIEVE TRAY DESIGN PARAMETERS


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Task Checklist


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X Introduction

TOWER SIMULATION

X Basic Concepts

X Specifications

DEVICE SELECTION



X Tray Hydraulics

XPacking Hydraulics



Z Tower Revamps

Packing Hydraulics

Packing Hydraulics

Flooding -- (Use Pegasys)


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Flooding (Use Pegasys)

Harder to define than tray hydraulics (i.e. no tray spacing or downcomerto fill with liquid)

As vapor rate increases, liquid accumulates and the pressure drop

begins to rise more sharply.

With further increases in vapor rate, the pressure drop rises almostvertically and liquid stacks up on top of the packing.

Ultimate Capacity -- (Use Pegasys)

Similar to tray hydraulics

Packing Hydraulics

Task Checklist


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X Introduction

TOWER SIMULATION

X Basic Concepts

X Specifications

DEVICE SELECTION



X Tray Hydraulics

X Packing Hydraulics

XOther Process Considerations


Z Tower Revamps

Packing Hydraulics

Tray Efficiency


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Overall Efficiency, EO, is a measure of the effectiveness of an entire

tower or tower section.

Allows designer to determine the number of actual trays to provide and

sets the tower height.

Actual Trays = Theoretical Stages / EO

Calculated Rigorously - Use Pegasys

(See DP III-I)

Factors affecting EO:

Weir Height

Flow Path Length and Number of Passes (i.e. Residence Time) Weeping or Vapor Recycle

VLE Properties and Tower Loading

Other Process Considerations

Calculation of Tray And Packing Efficiency


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# of theoretical trays = # of actual trays x tray efficiency

Screening Estimates - See DPM III-I

Table 2 for historical efficiencies

Figure 8 for heavy hydrocarbons

Rigorous Methods - DPM III-G (Packing) & DPM III-I (Trays)

Plot y* vs x for light key and heavy key

y* = vapor mole fraction in equilibrium with liquid

x = liquid mole fraction

Input slope into PEGASYS tray program

Estimating Tray Efficiency


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Estimating Tray Efficiency, Heavy Hydrocarbons


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Packing Height


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To specify correct packing height, designer must calculate height

equivalent to a theoretical plate (HETP)

Packing Height = Theoretical Stages x HETP

HETP must be calculated rigorously - Use Pegasys

(See DP III-G)

Other methods for packing efficiency exist, but HETP applies to most

systems

Factors affecting HETP:

Distributor Design

Packing Size / Geometry

VLE Properties and Tower Loading


Turndown


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Defines range of loadings for acceptable device performance

Excessive Weeping Decreases Efficiency


Dry Tray Pressure Drop, hed


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Dry tray dP is important because:

If its too high --- Entrainment

If its too low --- weeping at turndown

Calculated based on vapor flow through device with no liquid

present

Function of:

Vapor Rate Open Area / Device


( )2

VelocityVapor

edh

Foaming


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Foaming Mechanisms: Presence of surface active materials or solids

HC entrainment or condensation in aqueous systems

Compensate design by using: Lower percent of Jet and Downcomer Flood

Low dry tray dP

Low DC entrance velocity and filling

Radial tips (shaped lips) and large DC clearance

Provide antifoam injection facilities

(Since degree of foaminess varies and is generally unpredictable, experience in similar

towers may be used instead - Contact a Fractionation Specialist)

Known Foamers

Amine and Glycol Absorbers Caustic Towers

Ethylene Demethanizers

Sour Water Strippers


EXISTING T-2851 RE-DISTRIBUTOR

509


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20" Manway

650

1830

20" Manway

100

480

25

Top of PackingBed Limiter

Top Bed, 5334 deep (17.5')

2" Pall rings

800

74

254

180 Redistributor

110

Bed Support

396

286

357

Bottom Bed, 5334 deep (17.5')

2" Pall rings

This FLEXSORB

absorber tower

foams. Whatchanges would

you make to

improve it? Units

are in mm

(25mm=1) unless

stated.

Design Contingency


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To insure 90% chance of successful operation, safety margins

should be adhered to and are built into EMoTIP.

Examples

Jet Flooding (Trays) 80-90% of predicted

Downcomer Filling 35-50%

Packing Flooding 80-85% of predicted

Tray efficiency Point efficiency debited 10%

Packing HETP Predicted divided by 0.85


Trayed Tower Thoughts

Review all designs with Fractionation Specialist

U EM TIP t ti i t


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Use EMoTIP as starting point

Will not optimize open area or downcomer slope

Design for vacuum if can occur

Check vapor pressure of contents if reduced to ambient temperature

Try high capacity designs instead of packing for revamps

Prevent water from entering tower

#1 cause of refinery tray damage

Specify additional static pressure drop for design pressure

Use water filled basis if not high cost

Consider if can condense water on top tray

BEWARE of foaming

A well designed tower for non-foaming service will still flood if itfoams


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CONTACTING DEVICE

PROBLEM


Task Checklist

X Introduction


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X Introduction

TOWER SIMULATION

X Basic Concepts

X Specifications

DEVICE SELECTION



X Tray Hydraulics


X Other Process Considerations

XOther Tower Internals

Z Tower Revamps

Other Tower Internals

Tray Internals


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Perforated Pipe Distributors

Usually directed against a downcomer


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Usually directed against a downcomer

Use baffle to prevent downcomer boiling

Hole/Slot Area should give 0.25-0.5 psi (0.018-0.035 kg/cm2) pressure

drop

(See Fluid Flow Equations, DP III-H)

Four common types:


Tower Internals Details (DP III-H)

Pay special attention to tower inlets and outlets

Follow directions in DP III-H


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Follow directions in DP III H

Leave extra tray spacing for distributors and manways

Figure out where the manways will be

Distributors will create high velocity areas where flooding

can start Insulate baffle to prevent vaporization in downcomer

0.25-0.5 psi (0.02-0.04 kg/cm2) for distributor hole/slots

Chimneys

Long rectangular lowest cost, then round, last square

Size CWMS for 100% Vc, unless foaming service

Useful fluid flow equations hidden in DP III-H

Some drawoffs require self venting flow (eq 13)

Chance that vapor can enter drawoff line

Low residence time

Lack of seal in drawoff pan (coking or fouling services)

See also Distillation Operations, p. 89-94 (Kister)

Packing Internals


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Packing Liquid Distributors

Gravity Type


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Most important packing internal

Trough type preferred, but high cost

Design details by vendor but must

meet DP III-G, Appendix A criteria

Must be installed level


Packing Distributor


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Packing Spray Nozzles

Provide poor liquid distribution

Plug easily; strainers required


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Plug easily; strainers required

upstream

Low cost, but often require

demister above

Sprays in action: Water Test of

BTRF PS 8 VPS Wash Oil

Distributor at Turndown Rate - 2003


Distribution Quality


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All packing distributors should be

tested at vendor shop

Distributor should be fully

assembled during test

Area samples and individual

random sample are compiled to

verify performance


Packing Supports

Located at bottom of packed bed


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Open Area sized for at least 100% of tower cross section to prevent flooding

Design details by vendor

Bed Limiters

Restrain packing during upsets - keep out of draw nozzles, etc.


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Fastened to clips welded to shell or suspended from distributor

Packed Tower Details

First, dont use packed tower unless necessary

Low pressure drop (vacuum or atmospheric pressure tower)


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Very small diameter tower (3 ft or 915mm or less)

Possibly foaming, but still try trays first

Revamp where high capacity trays still cant provide necessary

capacity/efficiency Specify liquid distributor to meet criteria in DP-III-G Appendix A

3/8 (10mm) minimum orifice desired, but can reduce to (6mm)

Smaller holes may plug, resulting in poor fractionation

Be careful of high turndown requires small orifices Specify liquid distributor to meet flow test criteria in Appendix B

Copy both appendices and give to vendor

Provide dual strainers on liquid feed to prevent plugging

No bypass recommended SS piping downstream of strainers (especially if at grade)

Liquid Draws - Trays and Packing

Two types:

Downcomer (Sump)

Chi T


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Chimney Tray

Either type may be a partial or total draw

Reboiler Draws are unique (see DP III-H)


Reboiler Draw and Return Design11"


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3'-10"

1' - 3"

11"

2"

4"

4"

4"

8"

2'-0"

1'-6"

9"

2"

6"

1' - 9" 3' - 3"

4"

2'-10"

1'-4"

71

8"

1' - 0"

4'-10

"

5' - 0"

1

1/2"

4"

15

1' - 12"

2"

Task Checklist

X Introduction


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TOWER SIMULATION

X Basic Concepts

X Specifications

DEVICE SELECTION



X Tray Hydraulics


X Other Process Considerations

X Other Tower Internals

XTower Revamps

Tower Revamps

Tower Revamps

Always consider process alternatives first!!!(e g increase tower pressure etc )


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(e.g. increase tower pressure, etc.)

Revamp Strategy: Rate existing tower to identify limitations

Vapor Handling Limitation? Liquid Handling Limitation?

Poor Separation Efficiency?

Different Service?

Explore high capacity tray options discussed previously before

considering packing

Fundamental design concepts remain the same. However, sometimes

design criteria are too conservative - consult with a FractionationSpecialist.

Tower Revamps

Options Guide

Revamp Objective: Increased capacity at constant separation efficiency

(XOM DP III-A Table 4A)


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Debottleneck Examples

Cheap

Operational changes

Expensive

Install sloped or mod arc


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Operational changes

Reduce weir height, increase DC

clearance or add a shaped lip tolower DC filling

Change tray decks

Packed Towers:

Increase Packing Size

Install Structured Packing

Replace liquid distributor(s)

Install sloped or mod. arc

downcomers

Increase number of liquidpasses

Install high capacity trays

Changing tray spacing

Install packing

Change amine type or

concentration

Tower Revamps

Packing Selection

C il


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Can easily compare

different packing types

using this chart

(see DP III-G, Figure 3)

Tower Revamps

Expansion Example

What consider for expansion?


110/112

110

Top Trays

160%95%45%Expansion

150%90%42%Base


111/112

111

Verify bolts are tight

Make sure internals are put together correctly

Levelness of weirs

Tools Helmet mounted and hand held flashlights (explosion proof recommended)

Rechargeable spotlight for large vessels/furnaces

Knee pads, and maybe seating pad

Wrench (to check bolts)

Ruler, tape measure, and wooden blocks cut to measurement tolerances Water bottle

Level (consider laser type)

Hardhat, gloves, clear safety glasses, pool FRCs

Marker or paint pen

Shoulder bag Do not enter vessel without signing in through hole watch

Do not even put head inside vessel without permission

Gas test required to make sure safe

Sign out through hole watch when leaving

NEW T-2851 RE-DISTRIBUTOR

20" Manway

509

Replace packing with


112/112

112

649

1830

20" Manway

Old Top of Packing

Old Bed Limiter

Top Bed, 5334 deep (17.5')

Cascade Minirings #3

825

396

Bottom Bed, 5182 deep (17.0')

Cascade Minirings #3

Bed Support

112

New Top of PackingNew Bed Limiter (supported by clips)

152

Old Redistributor (removed)

New Redistributor

633

one with higher

capacity . Newer

packings can give

similar performance

with higher capacity

(at lower % jet flood).

Velocity through

chimneys was 21.5

ft/sec (6.6 m/s), with

only 3 (76 mm) gap

between top ofchimney and bed

support. Chimneys

were missing hats.

Lower distributor

and install hats on

chimneys.

Documents

Section 04 - Fractionation