impact of particle size distribution of material ...• bulk density, tapped bulk density - srps en...

1

IMPACT OF PARTICLE SIZE DISTRIBUTION OF

MATERIAL ON PNEUMATIC CONVEYING

OPERATION ON EXAMPLE OF GROUND

PHOSPHATE

Nikola KARLIČIĆ, Marko OBRADOVIĆ, Dušan TODOROVIĆ,

Dejan RADIĆ, Aleksandar JOVOVIĆ, Miroslav STANOJEVIĆ

University of Belgrade, Faculty of Mechanical Engineering, Department of Process Engineering

[email protected]

33. Međunarodni kongres o procesnoj industriji, Beograd, 10. septembar 2020

33rd International Congress on Process Industry, Belgrade, September 10, 2020


33rd International Congress on Process Industry, Belgrade, September 10, 2020 2

Phosphates – fertilizers - essential in the agricultural sector

~ 95% of the world phosphate rock production - fertilizer industry



Grinding

Mechanical conveyor

Pneumatic conveying system



Different types of phosphate rocks widely differ in their characteristics



Physical properties of bulk material must be taken into the consideration in

pneumatic conveying system design and operation



30 t/h 240 m ground phosphate pneumatic conveying

Pneumatic conveying was working with no problems

Clogging

Line chocking

Build-ups in pipes

Sudden pipe blockage

All kinds of pneumatic system inspections were conducted, and possible causes

that were leading to stoppage of the flow could not be found.



Laboratory for Process and Environmental Engineering (Faculty of Mechanical

Engineering, University of Belgrade)

Simple characterization of problematic material

One sample, about 20 kg of ground phosphate was delivered from the plant

Input data on material characteristics used for pneumatic conveying system

design

Ground phosphate

Sieve analysis Bulk density (kg/m3)

Sieve (mm) 1 0.63 0.5 0.4 0.25 0.125 0.063 < 0.063 Non-tapped Tapped

coarsely ground (%) 0.60 1.90 2.20 3.20 33.80 26.70 14.60 17.00 1343 1702

finely ground (%) 0.40 1.30 1.90 2.70 10.60 20.00 41.50 21.60 1207 1582



Laboratory tests:

• Sieve analysis - SRPS ISO 2591-1:1992 and SRPS ISO 3310-1:2018

• Bulk density, Tapped bulk density - SRPS EN ISO 787-11:2010 and ASTM D7481-18

• Physical density - SRPS B.C8.023

• Permeability (factor) - ASTM D7743-12

1. plexiglas fluidizing column, 2. porous membrane, 3. air

flow equalization chamber, 4. air mover,

5. pipeline for air supply, 6. orifice plate,

7. regulating valve



Ground phosphate


Sieve (mm) 1 0.63 0.5 0.4 0.25 0.125 0.063 < 0.063 Non-tapped Tappedcoarsely ground (%) 0.60 1.90 2.20 3.20 33.80 26.70 14.60 17.00 1343 1702finely ground (%) 0.40 1.30 1.90 2.70 10.60 20.00 41.50 21.60 1207 1582

Sieve (mm) 0.8 0.63 0.4 0.315 0.2 0.125 0.08 0.063 0.056 <0.056

Sample 1.1 0.59 1.85 9.19 10.29 21.33 34.06 18.38 1.60 0.51 2.19

Sampe 1.2 0.74 1.57 9.48 10.80 52.68 17.64 4.70 1.73 0.16 0.49

Sieve (mm) Average particle diameter (mm)Sample 1.1 0.233Sampe 1.2 0.275

Sieve (mm) Average particle diameter (mm)coarsely ground 0.227finely ground 0.155

Sieve (mm) 0.2 0.16 0.125 0.09 0.08 0.071 0.063 0.063 0.056 <0.056

Sample < 0.25 mm 4.20 19.80 34.95 26.28 3.92 5.02 4.93 0.27 0.09 0.55

Sieve (mm) Average particle diameter (mm)Sample < 0.25 mm 0.135

Bulk density (kg/m3) Bulk tapped density (kg/m3) Physical density (kg/m3)1141.4 1331.2 2500

Bulk density (kg/m3) Bulk tapped density (kg/m3) Physical density (kg/m3)

1320.4 1692.8 2663.3

Minimum fluidization velocity 16-17 cm/s

Permeability factor in range (7.41-24.09)∙10-6 m2/(Pa∙s)

Input data

Ground phosphate

Ground phosphate < 0.2 mm



Ground phosphate



Sieve (mm) 0.8 0.63 0.4 0.315 0.2 0.125 0.08 0.063 0.056 <0.056

Sample 1.1 0.59 1.85 9.19 10.29 21.33 34.06 18.38 1.60 0.51 2.19

Sampe 1.2 0.74 1.57 9.48 10.80 52.68 17.64 4.70 1.73 0.16 0.49



Sieve (mm) 0.2 0.16 0.125 0.09 0.08 0.071 0.063 0.063 0.056 <0.056

Sample < 0.25 mm 4.20 19.80 34.95 26.28 3.92 5.02 4.93 0.27 0.09 0.55




1320.4 1692.8 2663.3



Input data

Ground phosphate




Ground phosphate



Sieve (mm) 0.8 0.63 0.4 0.315 0.2 0.125 0.08 0.063 0.056 <0.056

Sample 1.1 0.59 1.85 9.19 10.29 21.33 34.06 18.38 1.60 0.51 2.19

Sampe 1.2 0.74 1.57 9.48 10.80 52.68 17.64 4.70 1.73 0.16 0.49



Sieve (mm) 0.2 0.16 0.125 0.09 0.08 0.071 0.063 0.063 0.056 <0.056

Sample < 0.25 mm 4.20 19.80 34.95 26.28 3.92 5.02 4.93 0.27 0.09 0.55




1320.4 1692.8 2663.3

Minimum fluidization velocity 16-17 cm/s and 10 cm/s

Permeability factor in range (7.41-24.09)∙10-6 m2/(Pa∙s) and (3,01 – 7,03)∙10-6 m2/(Pa∙s)

Input data

Ground phosphate




100

1000

10000

10 100 1000 10000

Densi

ty d

iffe

rence [

kg/m

3]

Mean particle diameter [μm]

Ground phosphate Ground phosphate < 200 μm

C

AB D

Geldart’s classification

100

1000

10000

10 100 1000 10000

Den

sity

dif

fere

nce

[kg/m

3]


Ground phosphate Ground phosphate < 200 µm

CA

B D

Dixon’s slugging diagram



Pan’s diagram Jones’ diagram

100

1000

10000

10 100 1000 10000

Bulk

den

sity

[kg/m

3]



PC1

PC3

PC2

100

1000

10000

0.1 1 10 100 1000

Bulk

den

sity

[kg/m

3]

Permeability [∙10-6 m2/(Pa∙s)]


Plug flowDilute only

Fluidised dense

phase

100

1000

10000

10 100 1000 10000

Densi

ty d

iffe

rence [

kg/m

3]



C

AB D



Mills’ diagram

1 72

5

6

9

3

8

4

10

0

4

8

12

16

20

24

0.1 1 10 100 1000

Min

imum

co

nvey

ing a

ir v

elo

city

[m/s

]

Permeability factor [∙10-6 m2/(Pa∙s)]

Suspension flow

Non-suspension flow

1. Barytes

2. Cement

3. Coal

4. Coal degraded

5. Flour

6. Pearlite

7. Pulverized fuel ash

8. Polyethylene pellets

9. Sugar

10. Sugar degraded

Ground phosphate < 200 µm

Ground phosphate

Jones’ diagram

100

1000

10000

0.1 1 10 100 1000

Bulk

den

sity

[kg/m

3]




Fluidised dense

phase



Mills’ diagram

1 72

5

6

9

3

8

4

10

0

4

8

12

16

20

24

0.1 1 10 100 1000

Min

imum

co

nvey

ing a

ir v

elo

city

[m/s

]


Suspension flow

Non-suspension flow

1. Barytes

2. Cement

3. Coal

4. Coal degraded

5. Flour

6. Pearlite



9. Sugar

10. Sugar degraded


Ground phosphate

Jones’ diagram

100

1000

10000

0.1 1 10 100 1000

Bulk

den

sity

[kg/m

3]




Fluidised dense

phase



Mills’ diagram 1 72

5

6

9

3

8

4

10

0

4

8

12

16

20

24

0.1 1 10 100 1000

Min

imum

co

nvey

ing a

ir v

elo

city

[m/s

]


Suspension flow

Non-suspension flow

1. Barytes

2. Cement

3. Coal

4. Coal degraded

5. Flour

6. Pearlite



9. Sugar

10. Sugar degraded


Ground phosphate

100

1000

10000

0.1 1 10 100 1000

Bulk

den

sity

[kg/m

3]




Fluidised dense

phase



• A few simple laboratory tests of material to be conveyed might be sufficient to

indicate possible roots of problems with pneumatic conveying system

operation

• Even minimal deviation of initial particle size distribution of material is very

important issue

• If the plant operates with previous crushing or milling facility, constant and

uniform grinding quality must be ensured

impact of particle size distribution of material ...• bulk density, tapped bulk density - srps en...

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