hydrogen fluoride l.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
HYDROGEN FLUORIDE PowerPoint Presentation
Download Presentation
HYDROGEN FLUORIDE

Loading in 2 Seconds...

play fullscreen
1 / 47

HYDROGEN FLUORIDE - PowerPoint PPT Presentation


  • 471 Views
  • Uploaded on

HYDROGEN FLUORIDE . CHEMICAL ENGINEERING DESIGN PRESENTATION 02/05/02. Hydrogen Fluoride Manufacture for the Semiconductor Industry. Important bulk chemical used as an intermediate for the production of refrigerants and solvents

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'HYDROGEN FLUORIDE' - stevie


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
hydrogen fluoride

HYDROGEN FLUORIDE

CHEMICAL ENGINEERING DESIGN PRESENTATION 02/05/02

hydrogen fluoride manufacture for the semiconductor industry
Hydrogen Fluoride Manufacture for the Semiconductor Industry
  • Important bulk chemical used as an intermediate for the production of refrigerants and solvents
  • Development of the electronics industry means that it is becoming an increasingly important chemical, where it is used for etching silicon chips
  • Concerns over its transport and storage has led to an interest in small ‘point of use’ plants
basics
BASICS…
  • All processes follow the same basic chemistry

H2SO4(l) + CaF2(s)2HF(g)+ CaSO4 (s)

  • Similar feed preparation, solids handling and separation
  • Producing 100te/yr of HF
slide4

3 PROCESSES WERE DEVELOPED

  • SOLID-LIQUID
  • Buss kneader and rotary kiln reactor
  • Simple separation scheme
  • SLURRY
  • Three-phase, co-current upflow reactor
  • Complex separation scheme with diluent recovery
  • SOLID-GAS
  • Fluidised bed reactor
  • Simple separation scheme
slide5

BLOCK FLOW DIAGRAM FOR ALL PROCESSES

HF PRODUCT

All Processes

Slurry

AREA 600

HIGH

PURITY

UNIT

AREA 400

SEPARATION

SECTION

AREA 300a

SLURRY SEPARATION

AREA 200

REACTOR SECTION

AREA 300b

SLURRY SOLIDS HANDLING

AREA 100

FEED PREPARATION

AREA 500

SOLIDS

HANDLING

CaF2

BY-PRODUCT

presentation outline
PRESENTATION OUTLINE
  • AREA 100 – FEED PREPARATION
  • AREA 200 – SOLID-GAS REACTOR – SOLID-LIQUID REACTOR
  • AREA 400 – GENERAL SEPARATION
  • AREA 500 – SOLIDS HANDLING
  • AREA 300 + SLURRY PROCESS DIFFERENCES
  • AREA 200 – SLURRY PROCESS REATOR
  • AREA 600 – HIGH PURITY UNIT
  • HAZARDS AND SAFETY ANALYSIS
  • COST, CONCLUSIONS AND RECOMMENDATIONS
area 100 feed preparation
AREA 100 - Feed Preparation
  • Fluorspar
  • Steam (2 and 10.6 bar)
  • Sulfur trioxide
  • Sulfuric acid
  • Diluent hexafluorobenzene (slurry only)
slide8

Storage

tank

Fluorspar

Steam (10.62 bar)

Steam (2 bar)

Sulfur trioxide

Diluent

Sulfuric acid

Screw conveyor

Lock

hopper

Lock

hopper

Steam

boiler

Main Reactor

Main Reactor

Steam

boiler

High purity unit

Storage

tank

Vapouriser

Main Reactor

Storage

tank

Main Reactor

Reactor gas absorber

Storage

tank

Mixing vessel

Sulfuric acid

absorber

area 200 solid gas reactor
Area 200: Solid-Gas Reactor
  • 3 Stage Fluidised Bed Reactor
  • Reaction 1 (Main)
    • CaF2(s) + H2SO4(l) 2HF(g) + CaSO4(s)
  • Reaction 2 (Heat)
    • SO3(g) + H2O(g) H2SO4(g) + Heat
operating conditions performance
Operating Conditions/Performance

0.4m

  • Conversion of CaF2 = 99%
  • Temperature = 400oC
  • Pressure = 10 bar(a)
  • Acid : Spar Ratio = 1.15
  • Residence Time (CaF2) =15 minutes

0.85m

2.75m

1.5m

0.1m

slide11

H2SO4(l)

ATOMISER

FLUIDISED BED SECTION OF REACTOR

SOLIDS FROM

CYCLONE

SOLID

REACTANT

(CaF2)

3

FLOW OF

HOT GASES

DISTRIBUTOR

PLATE

FLOW OF

SOLIDS

2

FLUIDISED

SOLIDS

1

WASTE

SOLIDS

(CaSO4)

SO3(g)

H2O(g)

slide12

TOP SECTION OF REACTOR

HF (+H2SO4) TO SEPARATION

AREA 400

CYCLONE

SOLIDS

FLOW OF

HOT GASES

FLOW OF

SOLIDS

SOLIDS TO STAGE 3

area 200 solid liquid process reactor
AREA 200: SOLID-LIQUID PROCESS REACTOR
  • BFD
  • PROBLEM
      • LARGE SCALE SMALL SCALE
  • INDUSTRY - KNEADER & KILN
  • THINK DIFFERENT!

H2SO4

HF

REACTOR

CaF2

CaSO4

kneader
KNEADER
  • DIRECT SCALE DOWN
  • DIMENSIONS
  • T = 200°C, P = 10 bara
  • HEATING
      • DIRECT RESISTANCE
      • ALTERNATIVE – HEATING TAPE

5.21cm

25.25cm

rotary kiln reactor
ROTARY KILN REACTOR
  • WHY KILN?
  • DIMENSIONS
  • T = 400°C, P = 10 bara
  • PROBLEMS
      • CONTAINMENT
      • ROTATION
      • HEATING

0.175m

0.699m

solutions for kiln
SOLUTIONS FOR KILN…
  • PRESSURE VESSEL
      • ENCOMPASS KILN
      • CONTAIN ALL PRODUCT
  • ROTATION
      • MAGNETIC DRIVE
      • BALL BEARINGS
      • ALCOMAX
  • MICROWAVES
      • HEAT POLAR LIQUID (AND HENCE PROCESS)
      • COAXIAL CABLE AND ANTENNA
      • HIGHLY EFFICIENT BUT COSTLY!
summary
SUMMARY
  • BASIC BFD
  • REALISABLE PROCESS SECTION
    • KNEADER
          • SCALE DOWN
          • DIRECT RESISTANCE HEATING
    • ROTARY KILN
          • CONTAINED IN PRESSURE VESSEL
          • ROTATED BY MAGNETS
          • HEATED WITH MICROWAVE UNIT
area 400 separation section
Area 400 - Separation Section

To atmosphere

Reactor Gas

Absorber T400

Sulfuric Acid

Absorber T420

Condenser E410

Water Absorber

T430

From Reactor

Area 200

To High Purity Section

Area 600

To disposal

HF Recycle

slide21

Area 400 - Separation Section

To atmosphere

Reactor Gas

Absorber T400

Sulfuric Acid

Absorber T420

Condenser E410

Water Absorber

T430

From Reactor

Area 200

To High Purity Section

Area 600

To disposal

HF Recycle

t420 sulfuric acid absorber
T420: Sulfuric Acid Absorber
  • Function: To remove the HF from the vapour feed to the column.
  • Operating conditions highly favour absorption.
  • Packed bed construction.
  • High integrity design.

667 mm

33 mm

t430 hf recycle water absorber
T430: HF Recycle & Water Absorber
  • Recycle: The HF absorbed is recycled along with a quantity from the high purity section to the reactor gas absorber.
  • Cooling, pressure reduction, pumping and heating are the operations carried out in the recycle of the HF.
  • Water Absorber: Absorption of remaining HF and conversion of SiF4 to H2SiF6.
summary24
Summary
  • Main stages in the separation section:
  • (1) Cooling of the reactor gases.
  • (2) Condensation of the HF passing to the high purity section.
  • (3) Absorption of remaining HF.
  • (4) Recycle of the HF.
area 500 pfd solids handling
Area 500 - PFD Solids Handling

From

Reactor

To Separations

Compressor P530

Lock-hoppers LH500A/B

Cyclone Dust Collector

Screw Conveyor S510

TK520A/B

Storage

Hopper

Solids To Disposal

lock hoppers lh500a b
Lock-hoppers LH500A/B

Solids In

80 mm

LH500A

140 mm

43 mm

Hopper Gates

90 mm

LH500B

150 mm

70 mm

Solids to S510

storage hopper tk520a b
Storage Hopper TK520A/B

Air Out

Hot Solids In

Cold Air In

Cold Air Out

Cold Air Injection

Jacket of Cold Air

Air Injection Distributor

Solids Outlet

the slurry process
THE SLURRY PROCESS
  • H2SO4 + CaF2 2HF + CaSO4

+ INERT DILUENT

    • aids mixing of reactants
    • improves heat transfer during reaction
    • Lower operating temperature
    • comparable or lower residence times
    • NOT PRACTICAL ON A LARGE SCALE
diluent selection
DILUENT SELECTION
  • HEXAFLUOROBENZENE (C6F6)
  • Originally 1,2,4-trichlorobenzene
    • suspected carcinogen
  • Criteria for new diluent
    • Inert under reaction conditions
    • boiling point higher than reactor temperature
    • less hazardous than TCB
    • cost comparable to TCB
  • Operating pressure raised so product separation easier
simplified bfd of the slurry process
SIMPLIFIED BFD OF THE SLURRY PROCESS

Non-condensables

AREA 100

E300

E310

E320

T420

T430

AREA 200

H2SO4

H2SiF6

CaF2

D330

M360

AREA 600

D350

AREA 500

slurry reactor

HF gas + diluent vapour

Solid spar

Liquid acid

Liquid diluent (recycle)

Solid calcium sulfate + liquid diluent

SLURRY REACTOR

- 3-phase continuous reactor able to achieve 99% conversion of calcium fluoride in the presence of a diluent.

  • acid 15% in excess
  • amount of diluent used based on 30%w/w CaSO4 in exit slurry
operating conditions
Operating Conditions

Op. temp = 200oC Op. Pressure = 20bara

- Reactants’ residence time = 80 mins

Key issue: how to ensure good mixing between the reacting materials (i.e. acid and solid spar) and keeping the solids in suspension?

configuration
Configuration

- 3-phase co-current upflow reactor column

- height-to-diameter ratio to be determined

- critical gas velocity for solid suspension (small variation with reactor height-to-diameter ratios).

gas liquid and solid holdups
Gas, Liquid and Solid holdups

- gas residence time estimated as 5 seconds.

- vary with column height-to-diameter ratios.

- with H/d ratio = 10,

Column diameter = 24cm; height = 300cm

- vapour recirculation (1 part to separation , 3 parts recirculated)

- slurry recirculation

- heated by heating tapes (over 90% heating done in Reactor vessel)

- Gas disengagement vessel

slide35

Vapour Recirculation

Reactor

L/S sep

Feed stream + diluent recycle

HF recycle

Slurry

recirculation

V/L sep

Gas disengagement drum

why a high purity unit
Why a High Purity Unit?
  • Build-up of Contaminants
  • Ionic & Particulate Materials Damage Wafers
  • This Reduces Yield & Increases Cost
  • Advances in Technology
  • Impurities to be in region of Parts per Billion
what impurities are we dealing with

SiF4

CO2

SO2

HF

H2SO4

As2O3

Metals

What Impurities are we Dealing With?
  • 99.8% pure HF from Separations Section

Order of Decreasing Relative Volatility

slide38

Process Flowsheet for Area 600

To Recycle

Partial Condenser

Partial Condenser

Partial Condenser

Ion Exchange Mechanism

HF from

Separations

1st Packed Column

2nd Packed Column

HF Storage Tank

other process options
Other Process Options
  • An Ultrafiltration Device
  • An Evaporator
  • A Refrigerated Packed column
  • Reusing the spent HF
hazards and environmental impact
Hazards and Environmental Impact
  • Hazards
    • Materials Present
    • Operating Conditions
    • Location
  • Scale of plant
hazards and environmental impact41
Hazards and Environmental Impact
  • Materials
    • HF and H2SO4
      • very hazardous to humans and the environment, particularly aquatic life.
  • Operating Conditions
    • High temperatures and pressures
  • Location
    • within another manufacturing facility
  • Plant design and safety features
hazards and environmental impact42
Hazards and Environmental Impact
  • Construction Materials
    • Hastelloy C2000
    • Stainless steel
    • Carbon Steel
  • Equipment Design
    • large design margins
  • Process safety features
    • Alarms and trips
slide43

CAPITAL COST ESTIMATION

£2M

KEY:

£0M

Sol-Liq

Slurry

Sol-Gas

£-1.5M

results
RESULTS
  • As can be seen, the Solid Liquid Process is the most economically attractive of the three
which process
WHICH PROCESS…?
  • REACTOR COMPLEXITY
      • Solid-Liquid ü
      • Solid-Gas û
      • Slurry û
  • SEPARATION COMPLEXITY
      • Solid-Liquid ü
      • Solid-Gas ü
      • Slurry û
  • EVALUATION OF CAPITAL COSTS
      • Solid-Liquid ü
      • Solid-Gas û
      • Slurry û
conclusions and recommendations
CONCLUSIONS AND RECOMMENDATIONS
  • INITIAL INVESTIGATION…
  • BUT! FURTHER ANALYSIS REQUIRED

SOLID-LIQUID PROCESS