Production of Steel Shot Josh Ball – [email protected] Matt Calcutt – [email protected] Sean Loney...

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Production of Steel Shot Josh Ball – [email protected] Matt Calcutt – [email protected] Sean Loney – [email protected]

Transcript of Production of Steel Shot Josh Ball – [email protected] Matt Calcutt – [email protected] Sean Loney...

Page 1: Production of Steel Shot Josh Ball – jbball@mtu.edu Matt Calcutt – mtcalcut@mtu.edu Sean Loney – smloney@mtu.edu.

Production of Steel Shot

Josh Ball – [email protected] Calcutt – [email protected] Loney – [email protected]

Page 2: Production of Steel Shot Josh Ball – jbball@mtu.edu Matt Calcutt – mtcalcut@mtu.edu Sean Loney – smloney@mtu.edu.

Introduction

• Background• Process Overview• Calculations• Conclusions

Page 3: Production of Steel Shot Josh Ball – jbball@mtu.edu Matt Calcutt – mtcalcut@mtu.edu Sean Loney – smloney@mtu.edu.

Background

• What is Steel Shot?– Tiny steel balls

• What is it used for?– Cleaning work pieces (Shot Blasting)

• Sand and Scale removal from castings, Surface prep for painting

– Shot Peening– Granite Cutting– Non-Toxic Shotgun ammunition

Page 4: Production of Steel Shot Josh Ball – jbball@mtu.edu Matt Calcutt – mtcalcut@mtu.edu Sean Loney – smloney@mtu.edu.

Process Overview

• Molten Steel flows from a tundish and is made into a spray.

• The droplets (1mm diameter spheres) freefall in a cylindrical chamber containing a gas atmosphere.

• Upon reaching 1000C, they will land in a fluidized bed for further cooling.

Page 5: Production of Steel Shot Josh Ball – jbball@mtu.edu Matt Calcutt – mtcalcut@mtu.edu Sean Loney – smloney@mtu.edu.
Page 6: Production of Steel Shot Josh Ball – jbball@mtu.edu Matt Calcutt – mtcalcut@mtu.edu Sean Loney – smloney@mtu.edu.

Objective

• Determine what gas (He ,Ne, Ar, Kr) in the vessel will result in the fastest solidification time, and therefore the shortest vessel.

• Determine the relationship between air velocity and cooling time in the fluidized bed.

Page 7: Production of Steel Shot Josh Ball – jbball@mtu.edu Matt Calcutt – mtcalcut@mtu.edu Sean Loney – smloney@mtu.edu.

Assumptions

• The steel shot will not deform on impact• The conveyor movement will not impact the

rate of cooling• Density and size of particles does not change

with temperature• 1 Million pounds of shot would be produced

in a 24 hour period

Page 8: Production of Steel Shot Josh Ball – jbball@mtu.edu Matt Calcutt – mtcalcut@mtu.edu Sean Loney – smloney@mtu.edu.

Calculating terminal velocity of the droplets for each atmosphere

vtHe 31.164m

s vtNe 16.058

m

s vtAr 11.827

m

s vtKr 8.111

m

s

ReAr vtAr 2 r vtAr Ar

Ar

vtAr1

4 2 r( ) st Ar 9.8m

s2

3 Ar18.5

2 r Ar

Ar

3

5

5

7

ReAr vtAr1 1.224 103 Re > 500 So using friction factor 2 is incorrect

vtAr

4 2r( ) st Ar 9.81m

s2

3 .44 Ar

1

2

ReAr vtAr 940.997 Friction factor 3 gives an acceptable value for Re (500 < Re < 20000)

Page 9: Production of Steel Shot Josh Ball – jbball@mtu.edu Matt Calcutt – mtcalcut@mtu.edu Sean Loney – smloney@mtu.edu.

Finding the heat transfer coefficient for each process

Finding the heat transfer coefficient, h, for each process

Nu 2 0.6Re

1

2Pr

1

3 Pr Cp

kNu

h 2 rk

hk

2r2 0.6Re

1

2Pr

1

3

PrHe

He CpHe

kHe

hHe

kHe

2 r2 0.6ReHe vtHe

1

2PrHe

1

3

hHe 1.533 103

kg

K s3

hNe 595.92kg

K s3

hAr 293.09kg

K s3

hKr 169.871kg

K s3

Page 10: Production of Steel Shot Josh Ball – jbball@mtu.edu Matt Calcutt – mtcalcut@mtu.edu Sean Loney – smloney@mtu.edu.

Calculating Biot Numbers

Bih r3k

BiHe 6.573 103 BiNe 2.555 10

3 BiAr 1.257 103 BiKr 7.283 10

4

All Biot numbers are below 0.1 = No significant temperature gradients across the solid

Page 11: Production of Steel Shot Josh Ball – jbball@mtu.edu Matt Calcutt – mtcalcut@mtu.edu Sean Loney – smloney@mtu.edu.

Calculating Cooling Time and Chamber Height

Time required to remove superheatt ln

Tmelt Tgas

Ttundish Tgas

1( )r

3

st Cpst

h

tSHHe lnTmelt Tgas

Ttundish Tgas

1( )r

3

st Cpst

hHe

tSHHe 0.071s

tfusionHe

1

3r3

r2 hHe

Hs st Tmelt Tgas

Time required to remove heat of fusion

tfusionHe 0.142s

Time required to cool from melting temp to 1000C

tcoolHe ln1273K Tgas

Tmelt Tgas

1( )r

3

st Cpst

hHe

tcoolHe 0.225sttotalHe tcoolHe tfusionHe tSHHe

ttotalHe 0.437s ttotalNe 1.125s ttotalAr 2.288s ttotalKr 3.948s

ChamberHeightNe vtNe ttotalNe

ChamberHeightHe 13.632m ChamberHeightNe 18.072m ChamberHeightAr 27.064m ChamberHeightKr 32.023m

Page 12: Production of Steel Shot Josh Ball – jbball@mtu.edu Matt Calcutt – mtcalcut@mtu.edu Sean Loney – smloney@mtu.edu.

Void Area fractionVoid Area Fraction of a Close Packed Bed

a2

a2 4 r( )

2

a 8r2

Area a2

8r2 2 8r

2

Area_Spheres 2 r2 2r2

Volume_Voids a2

2r2 r28 2

Void_Area_FracArea_Voids

Area

r28 2

8r2

8 28

8 28

0.215

Page 13: Production of Steel Shot Josh Ball – jbball@mtu.edu Matt Calcutt – mtcalcut@mtu.edu Sean Loney – smloney@mtu.edu.

Bed ThicknessDetermining Thickness of Cooling Bed

DailyProduction 1 106lb

day ConveyorSpeed .05

m

s

BedWidth 0.5m

VolumeFlowRateDailyProduction

st

VolumeFlowRate 6.679 104m3

s

BedThicknessVolumeFlowRate

BedWidth ConveyorSpeed 1

BedThickness 34.017mm

Page 14: Production of Steel Shot Josh Ball – jbball@mtu.edu Matt Calcutt – mtcalcut@mtu.edu Sean Loney – smloney@mtu.edu.

Velocity of AirDetermining Minimum Fluidization Velocity for Steel Shot

Remf 33.673 1134 0.0408Ga( )

1

2 Minimum Fluidization equation

Remf

gas vmf dst

gasGa

dst3 st gas gas 9.81

m

s2

gas2

air 1.202kg

m3

air 1.695105kg

m s

Gaair

2r( )3 st air air 9.81

m

s2

air2

Reair 33.673 1134 0.0408Gaair 1

2

vmfair

Reair air

air 2 r

vmfair 1.211m

s

Terminal velocity was calculated the sameas before

vtair

4 2r( ) st air 9.81m

s2

3 .44 air

1

2

vtair 13.941m

s

vair 1.211m

s1.3

m

s 13.941

m

s

Page 15: Production of Steel Shot Josh Ball – jbball@mtu.edu Matt Calcutt – mtcalcut@mtu.edu Sean Loney – smloney@mtu.edu.

Cooling in Fluidized BedsTcoolair 298K Cpair 1001

J

kg K kair 0.02394

W

m K

Prair

air Cpair

kair

Recoolair vair air vair 2 r

air

hair vair kair

2 r2 0.6Recoolair vair

1

2Prair

1

3

Biair vair hair vair r3 kst

0 5 10 155 10 4

0.001

0.0015

0.002

Biair vair

vair0 5 10 15

100

200

300

400

500

hair vair

vair

Bi is always less than 0.1 so there are notemperature gradients across the solid

Page 16: Production of Steel Shot Josh Ball – jbball@mtu.edu Matt Calcutt – mtcalcut@mtu.edu Sean Loney – smloney@mtu.edu.

Cooling in Fluidized Beds continued

tcoolair vair ln300K Tcoolair

1273K Tcoolair

1( )r

3

st Cpst

hair vair

Gives the amount of time to cool steel shotfrom 1000 degress C to room temperature

0 5 10 1510

15

20

25

30

35

tcoolair vair

vair

Determining length of the bed required

ConveyorLengthvair ConveyorSpeedtcoolair vair

0 5 10 150.5

1

1.5

2

ConveyorLength vair

vair

ConveyorLength 1.211m

s

1.509m

ConveyorLength 13.941m

s

0.558m

The conveyor (when moving at 5 cm/s) must bebetween 0.558 m and 1.509 m depending on the airvelocity. Since we are trying to conserve space,blowing the air at 13.941 m/s would make theconveyor shortest.

Page 17: Production of Steel Shot Josh Ball – jbball@mtu.edu Matt Calcutt – mtcalcut@mtu.edu Sean Loney – smloney@mtu.edu.

Conclusion

• Helium gives the smallest chamber height (13.63m)

• At 0.5m wide the cooling bed is 34mm thick

• The length of the cooling bed depends upon the velocity (0.56m to 1.5m)

Page 18: Production of Steel Shot Josh Ball – jbball@mtu.edu Matt Calcutt – mtcalcut@mtu.edu Sean Loney – smloney@mtu.edu.

Sources

• Dr. Hackney’s wonderful class notes• http://encyclopedia.airliquide.com/

encyclopedia.asp• http://chem.lapeer.org/PhysicsDocs/

Goals2000/Laser1.html