Sulphuric Acid: A challenge for materials and sealing systems for centrifugal pumps - Aliaxis -...

18. – 21. October 2015

DIVISION RHEINHÜTTE PUMPEN

COBRAS, IX Brazilian Congress of Sulfuric Acid Fortaleza, Brazil

SULPHURIC ACID:A CHALLENGE FOR MATERIALS AND SEALING SYSTEMS FOR CENTRIFUGAL PUMPS

2

CONTENT

IntroductionOverviewMaterialsPump Design & Sealing Systems

Rheinhütte Pumpen are experts for sophisticated pumping applications for corrosive, abrasive and toxic fluids.

■ Our unique material expertise ■ Our broad variety of materials■ And more than 150 years of experience (1857)

always offer you the right solution:

Pumps which reliably convey the most difficult fluids throughout demanding industries - worldwide.

COMPANY PROFILE

ABOUT US

3

COMPANY PROFILE

GLOBAL EXPERTISE Headquarter in

Wiesbaden / Germany

Production plants in• Wiesbaden and

Rennerod / Germany• Cataguases / Brazil• Shanghai / China• Odessa / Florida

Worldwide more than 70 Sales Offices and Service Depots

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Rheinhütte Pumpen sitesGroup-affiliated-companiesSales companies

HQ in Germany:2 Factories300 employees

Brazil:Cataguases90 employees

COMPANY PROFILE

FACTORY CATAGUASES

7

CONTENT


OVERVIEW

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Materials

Metal

Plastic

Sealing Systems

Gland Packing

Pump Design

Vertical

Horizontal Mechanical Seal

Mag Drives

Hydrodynamic Seal

Sulphuric Acid

Ceramic

9

CONTENT


MATERIALS

OVERVIEW

10

SigussPTFEnur bis 180°C

Concentration H SO in %2 4

Tem

pera

ture

20

50

100

200

300

0 50 100

[°C]

Boiling line

PlasticPP, Pe1000, PVDF, ETFE

Ferre

tic &

spec

ial m

etal

allo

ys

Special metal alloys like:

•SX•Saramet 35•Lewmet•1.4136S

1.4408

1.4408

MATERIALS

CORROSION BEHAVIOR OF SULPHURIC ACID

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0 10 20 30 40 50 60 70 80 90 100

Concentration [%]

Rel

ativ

e co

rros

iven

ess

low

high

Iron base materials

Plastics

Ceramics

MATERIALSCORROSION OF PLASTIC MATERIALS IN H2SO4

ISO Corrosion Curve H2SO4

0

25

50

75

100

125

150

175

200

225

250

275

300

325

350

0 10 20 30 40 50 60 70 80 90 100

Concentration [%]

Tem

pera

ture

[°C

]

Boiling curve sulphuric acid

Corrosion curve PP

Corrosion curve PE UHMW

Corrosion curve PVDF

Corrosion curve PTFE / PFA

Corrosion curve ETFE

no responsibility is taken for the correctness of this information !

MATERIALS

SILICON CAST IRON (15% SILICON) - CORROSION RATE PER YEAR

20406080

100120140160180

200220240260280

300320340

0 10 20 30 40 50 60 70 80 90 100

T (°

C)

< 0,4 mm/a

< 0,02 mm/a

< 0,1 mm/a

% H2SO4

Source: Rheinhuette technical information 1

Siguss is resistant against corrosion of sulphuric acid at all concentrations and temperatures

MATERIALS

CORROSION AND ROTATING SPEED

Corrosion rate of SS 316 for different concentrations of H2SO4 at different rotation speed.

0,01

0,1

1

10

100

0 10 20 30 40 50 60 70 80 90 100

0 m/s

2 m/s

4 m/s

25� C

Cor

rosi

on ra

te in

mm

per

yea

r

Concentration in % H2SO4

MATERIALS

UNIFORM CORROSION

■ Typical for metallic materials

■ Uniform (homogeneous) material loss on the surface

■ Corrosion rate is calculable by corrosion tests

■ Max. 0,5 mm per year – resistant material

■ Iso-corrosion-curves often available

■ This corrosion form is acceptable

Please note ■ Especially for mixtures – corrosion rates of the single

components are not summable!

■ Already traces can boost, but also inhibit the corrosion rate!

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MATERIALSH2SO4 ISO CORROSION CURVES

original

resistantnot resistant

0,1mm/a curve – static testsnote: no flow and no impurities

Source: Outokumpu stainless corrosion handbook

DIN EN 1.4571= 316 Ti

MATERIALSH2SO4 AND ADDITIVES

The corrosiveness of sulphuric acid could be significantly different, by the presence of various additives.

Some matters inhibit and other matters enforce the corrosiveness of sulphuric acid.

Inhibiting effect- CuSO4

- FeSO4

- Nitrates / HNO3

Enforcing effect- SO2

- Chlorides- Traces of other acids (HCl)

Example: 1.4539 (904L) Corrosion ratein 20% H2SO4 at 50 °C 0,01 mm/a in 500 ppm Cl- at 50 °C 0,0025 mm/ain 20% H2SO4 with 500 ppm Cl- at 50 °C 0,1 mm/a

1.4571 (316Ti) Corrosion ratein 20% H2SO4 at 50 °C 1,3 mm/ain 20% H2SO4 with 500 ppm CuSO4 at 50 °C 0,01 mm/a

MATERIALS

EROSION (CORROSION)

Erosion is a known problem for flowing media■ High flow rates may cause eddies at obstacles,

defects or at turnarounds■ Increased material losses aground of eddies■ Typical are “erosion scars” like tears

Specific liquids enforce the effect of erosion!

Serious consequence could be an erosion corrosion

MATERIALS

EROSION - CORROSION IN DETAIL■ Effect is known for metallic and plastic materials■ Localized (inhomogeneous) material loss on the surface■ Only in regions with high flow rates■ Flow washes the passive layer away – velocity of the

removal is higher as the velocity of the reformation■ Corrosion rate by flowing media is higher than in static

media■ The harder the material, the higher the resistance against

erosion corrosion ■ This corrosion form is not acceptable

MATERIALS

EROSION – CORROSION ON A PUMP IMPELLER

MAG-DRIVE PUMP HIGHLY ALLOYED AUSTENITIC96% H2SO4 AT 30 °C IN APPLICATION FOR 3 YEARS

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CONTENT


SEALING SYSTEMS

OVERVIEW

Concentration H SO in %2 4

Tem

pera

ture

20

50

100

200

300

0 50 100

[°C]

Boiling line

Vertical orHydrodynamic

Mag-Drive

Mechanical Seal

PUMP DESIGN

VERTICAL PUMP TYPE VS4 OR VS1, STRONG ACID CIRCULATING PUMPS

Photo: Lewis Pumps Photo: Ensival-Moret

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Corrosion resistant sleeve bearing lubricated by the fluid with different groove systems available

Double volute casing to balance radial loads on the sleeve bearing system

PUMP DESIGN

MTBF - VERTICAL PUMP STRONG ACID CIRCULATING PUMPS

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PUMP DESIGN


Ceramic catalyst always anissue for sleeve bearing system

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PUMP DESIGN


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PUMP DESIGN


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PUMP DESIGN


Groove system with high pressure injection from discharge.

Gap clearance can be adjusted

PUMP DESIGN

HORIZONTAL WEAK ACID PLASTIC PUMP

Cast iron armourSolid plastic

PUMP DESIGN

PLASTIC IMPELLER

PUMP DESIGN

MASSIV PLASTIC CASING

PUMP DESIGN

HORIZONTAL WEAK ACID PUMP

10% H2SO4

with Ni, Cu &Co powder

Material: PET: 70°CQ: 2500 m³/hH: 29 mMotor: 280 kW

PUMP DESIGN

SILICON CAST IRON PUMP WITH HYDRODYNAMIC SHAFT SEAL

Hydrodynamic shaft sealwith up to 3 expellers

Standstill seal:grease, pneumatic, packing

Concretfilling

Silicon cast iron

Cast iron armour

PUMP DESIGN

HORIZONTAL MAGNETIC DRIVEN METAL PUMP

CriticalComponents:-Spacer Can-Inner Rotor

Inner rotor

Spacer can

Materials:-SX-Hastelloy C4-1.4539 (904L)-1.4136S

PUMP DESIGN

ACID CIRCULATING PUMP WITH AN „INDUCER“ IMPELLER

Hydrodynamic shaft sealwith up to 3 expellers

Pneumatic standstillseal

Concret filling

Silicon cast iron

Cast iron armour

PUMP DESIGN

ACID CIRCULATING PUMP WITH AN „INDUCER“ IMPELLER

30 - 80% H2SO4

with metal sulfatechrystals

T: 50 - 190°CQ: 1500 m³/hH: 3 mDN 500

A Special Pumpfor a SpecialApplication

GermanHistory

39

REFERENCES

EUROPEAN END-USERS AN ENGINEERING COMPANIES

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REFERENCES

■ Vertical Acid Pumps: 237 units

■ Horizontal Acid Pumps: 952 units

NUMBER OF DELIVERED PUMPS IN H2SO4 SERVICE SINCE 2004

THANK YOU!

Sulphuric Acid: A challenge for materials and sealing systems for centrifugal pumps - Aliaxis -...

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Transcript of Sulphuric Acid: A challenge for materials and sealing systems for centrifugal pumps - Aliaxis -...