stockyard layout (re)design

1Stockyard layout (re)design

13-05-2013

Challenge the future

DelftUniversity ofTechnology

Stockyard layout (re)design

Delft University of Technology

G. Lodewijks, T.A. van Vianen and J.A. OttjesFaculty 3ME, Transport Engineering & Logistics


Export Terminal Saldanha Bay SA

2


Bulk terminal simulation


Content1. Stockyard functions2. Stockyard machines3. The machine selection for capacity & blending or

homogenizing 4. The machine selection for the storage of bulk materials5. CASE: stockyard layout design for an import terminal6. Summary

Delwaidedok, Antwerp (Courtesy HeliHolland/Kees Vlot)


1. Stockyard functions


Stockyard functionsStorage

(A)

Blending

(B)t

x(t)σx(t)

t

y(t)σy(t)

Homogenizing

(C)

y(t)σy(t)

x(t)σx(t)

t t


2. Stockyard machines


Stockyard machines - Overview (1)

Handling coal using wheel loaders and mobile feed bunker (Courtesy N.M. Heilig BV)

Stacking of coal using a stacker (Courtesy ThyssenKrupp) Circular storage (Courtesy HeliHolland/ Kees Vlot)



Bucket wheel reclaimer (Courtesy FAM)

Bucket wheel stacker/reclaimer, left: stacking, right: reclaiming (Courtesy ThyssenKrupp)



Double sided bridge scraper reclaimer (Courtesy ThyssenKrupp)

Reclaiming with a side scraper and stacking with an overhead belt conveyor (Courtesy Taim Weser)


3. The machine selection for capacity & blending or homogenizing


Stockyard machines - Effective capacity ratio (1)

• During terminal (re)design, the effective capacity ratio is essential to prevent selecting a machine with insufficient capacity

• Effective capacity ratio for a bucket wheel reclaimer relates to the used reclaiming method

Long-travel reclaiming method

Slewing bench reclaiming method


Δx

Δx

As(θ)

ωs

h

(A)

(B)

ωr

θ

As(θ)

MM’

pΔr

hs

θmax

Slewing reclaiming method A) top view and B) lateral view


cos( )cos( )

ssr s b bw mC h x l r

Nominal reclaiming capacity:

Para-meter

Description Value Unit Para-meter

Description Value Unit

hs Slice height 4.5 [m] rbw Radius of bucket wheel 4.5 [m]

Δx Max. chip thickness 1 [m] ωss Minimum slewing speed 0.145 [rad/min]

ρm Bulk density coal 0.8 [t/m3] ωsm Maximum slewing speed 0.58 [rad/min]

lb Boom length 60 [m] as Maximum slewing acceleration/ deceleration

0.5 [rad/min2]


• Reclaiming capacity for the slewing bench reclaiming method relates to (i) slice cross-sectional area, (ii) the slewing speed and (iii) bulk density of the reclaimed material.

• The reclaim capacity can be kept stable with an increase of the slewing speed

0

0.1

0.2

0.3

0.4

0.5

0.0

0.4

0.8

1.2

1.6

2.0

0 10 20 30 40 50 60 70 80 90

ωs

[rad

/min

]

C r[k

t/h]

θ [°]

Crωs

0

0.1

0.2

0.3

0.4

0.5

0.0

0.4

0.8

1.2

1.6

2.0

0 10 20 30 40 50 60 70 80 90

ωs

[rad

/min

]

C r[k

t/h]

θ [°]

Crωs

Without slewing speed adjustment With slewing speed adjustment


Stockyard machines - Effective capacity ratio (2)

• The effective capacity ratio was calculated for bucket wheel reclaimers for the long-travel and the slewing-bench reclaiming method.

Para-meter

Description Value Unit Para-meter

Description Value Unit

lt Total pile’s length 325 [m] h Slice height 4.5 [m]

w Pile’s width 50 [m] Δx Maximum chip thickness 1 [m]

h Height of the pile 18 [m] lb Boom length 60 [m]

ρm Bulk density coal 0.8 [t/m3] rbw Radius of bucket wheel 4.5 [m]

α Angle of repose 38 [°] ωss Start slewing speed 0.25 [rad/min]

vt Travelling speed 10 [m/min] ωsm Maximum slewing speed 0.58 [rad/min]

at Travel acceleration and deceleration

0.15 [m/min2] as Maximum slewing acceleration & deceleration

0.5 [rad/min2]

y Distance centerline machine to pile

10 [m]


• The effective capacity ratio was for the long-travel reclaiming method 75% and for the slewing bench reclaiming method 45%

0.0

0.5

1.0

1.5

2.0

2.5

500 505 510 515 520 525 530 535 540

C r[k

t/h]

Time [min]

long-travelslewing bench

Reclaiming capacity during a time interval of 40 hours for two reclaiming methods

Note: these ratios are not general but were derived using specific input parameters


0

0.4

0.8

1.2

1.6

2

50 100 150 200 250 300 350

C r [k

t/h]

lt [m]

Reclaiming efficiency versus the pile's length for the long-travel reclaiming method


Stockyard machines Main Characteristics

Machine type Maximum capacity [t/h]

Effective capacity ratio [-]

Stockpile width [m]

Reclaiming method to the pile

Stacker 10,000 0.5-0.65 30-60 -Radial stacker 8,000 0.5-0.65 Ø120 -Side scraper reclaimer

1,000 0.75 10-25 Alongside

Single boom portal scraper reclaimer

2,200 0.75 15-60 Alongside

Double boom portal scraper reclaimer

4,400 0.75 15-60 Alongside

Bridge scraper reclaimer

1,800 0.95 15-60 At the face

Bridge bucket wheel reclaimer

10,000 0.95 30-60 At the face

Drum reclaimer 4,500 0.95 20-50 At the faceBucket wheel reclaimer

12,000 0.4-0.8 30-60 Alongside


Blending or homogenizing machines• Stacking is the starting point of the blending process.

Generally there are four basic stacking methods

Reclaimer machineStacking method

Cone Shell

Chevron Strata Windrow

Single scraper reclaimer andPortal scraper reclaimer

2 2 3-4 4-6

Bridge scraper reclaimer - 10 5-6 8-9

Bridge bucket wheel reclaimer

- 4-8 4-6 4-8

Drum reclaimer - 9-10 4-6 7-8Bucket wheel reclaimer - 4-5 5-6 4-6

out

in


4. The machine selection for the storage of bulk materials

• Selection of archetype

• Cost calculation

• Operational performance


• Multi-purpose machine (stacker/reclaimer) or two single-purpose machines (stacker and reclaimer)

Stacker/reclaimer Stacker Reclaimer

(I)

(II)

Incoming stream Outgoing stream

Belt conveyor

Stockyard lane

ṁin ṁout

B1

B2

A

ṁin ṁout

(A)

(B)

Two layout archetypes

Selection of archetype


• Selection must be based on the archetype’s investment cost and performance

• It was assumed that the machine investment cost relates to its weight

0

200

400

600

800

1,000

1,200

0 2 4 6 8 10 12

w [t

]

Cs + Cr [t/h]

lb=25±3 [m]

lb=30±3 [m]

lb=37±3 [m]

lb=46±1 [m]

lb=63±3 [m]

Stacker/reclaimers weight versus capacities as function of boom length

0

1

2

3

4

5

6

7

8

9

10

0 1 2 3 4 5 6 7 8 9 10

κ bc

[k€/

m]

Cbc [kt/h]

Upper limitLower limitQuotations: 1 ≥ Lbc ≤ 1.5 [km]

Price per meter for belt conveyors versus its transport capacity

and the belt conveyor investment cost relates to its capacity

Cost calculation


• The performance at dry bulk terminals is generally expressed in the total time that ships and trains spend in the port

• The port time is the sum of the waiting time and service time

• The ships waiting time relates to:• Interarrival time distribution • Carrier tonnage distribution• The ship (un)loader utilization• Mean service rate• Mean arrival rate

Queuing theory formulas or simulation

Operational performance


5. Case: stockyard layout design for an import terminal


Main requirements:

• Import terminal with an annual throughput of 37 [Mt/y], 21% bypass (no storage and handling by stockyard machines)

• Required stockyard area: 92 [ha]• Seaside: bulk carriers, landside: trains• Interarrival time distribution seaside and landside: NED • Carrier tonnage distribution: based on historical data (avg. 101

[kt])• Train tonnage distribution : uniform distributed between 2 and

4 [kt]• Stockyard machine efficiency: 0.55 [-]• 4 unloaders at seaside and 4 loaders at landside• Average seaside’s port time (Wss): 3 days and average

landside’s port time (Wls): 0.5 day• Blending of coal: 1.7 [Mt/y]• 28 different grades of bulk materials must be stored

separately


Step 1:

Determine the number of stockyard lanes (nl) and dimension the stockyard lanes (length Ll and width w).

• Assume a machine’s boom length (lb) of 60 meter and use 10 meter as distance from the machine’s centerline to the stockyard lane (p).

• Assume that the lane’s length (Ll) must be in the range between 1,000 and 1,500 meter

• Number of stockyard lanes must be an even number to realize complete archetypes. Calculate the number of archetypes using the following equation:

• An outcome is nl = 14, Ll = 1,315 [m] and w = 50 [m]

plLnA bll


Step 2:

Determine the required machine capacity based on Wss ≤ 3 days and Wls ≤ 0.5 day for both archetypes.

SR1

SR2

SR3

SR4

SR6

SR5

SR7

1,315 [m]

A B

C DE F

G HI J

K LM N

O P

Q R

S TU V

W XY Z

AA BB

Stacker/reclaimer

Yard conveyor

Stockyard lane

Bulk carrier

Train

(un)loader

Layout A with 7x archetype (I)

S1

R1S2

R2S3

R3S4

R4S5

R5S6

R6S7

R7

A B

C DE F

G HI J

K LM N

O PQ R

S TU V

W XY Z

AA BB

Stacker

Yard conveyorStockyard lane

Bulk carrier

Train

(un)loader

Reclaimer

1,315 [m]

Layout B with 7x archetype (II)


Step 2: results of the simulation study

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5W

ls[d

]Cr [kt/h]

Layout A: 7x archetype (I)

Layout B: 7x archetype (II)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5

Wss

[d]

Cs [kt/h]

Layout A: 7x archetype (I)

Layout B: 7x archetype (II)

(A) (B)Layout Machine Cs [kt/h] Cr [kt/h]

A Stacker/Reclaimer 3.8 4.5

B Stacker 3.6Reclaimer 2.7


Step 3:

Calculate the total investment cost per archetype.

• Calculate the stockyard machine’s weight (w) based on the determined stacking and reclaiming capacities

• Investment cost of the stockyard machine(s): where for this case it was assumed that κsm was 8 [€/kg],

machine fully installed at the stockyard• Investment cost for the belt conveyor(s):

where Lbc is conveyor length (1,400 [m]) and κbc was according Figure slide 22 “upper limit”.

Layout Machine Cs [kt/h] Cr [kt/h] w [kt] ICsm [M€] ICbc [M€] TIC(A) [M€]

A Stacker/Reclaimer 3.8 4.5 925 7.4 6.3 13.7

BStacker 3.6 409 3.3 5

16.1Reclaimer 2.7 506 4 3.8

smsm wIC

bcbcbc LIC


Step 4:

Design the blending bed with associated machine types.

• Future: high-quality coal will probably become scarce thus install stacker and reclaimer combination which is able to realize the highest bed blending ratio

• Blending bed dimensions: assume coal-fired power plant’s own storage of 5 days and use two blending beds for simultaneously stacking and reclaiming.


Step 5:

Final layout.

SR1

SR2

SR3

SR4

SR6

SR5

SR7

1,315 [m]

A B

C DE F

G HI J

K LM N

O P

Q R

S TU V

W XY Z

AA BB

Stacker/reclaimer

Yard conveyor

Stockyard lane

Bulk carrier

Train

(un)loader

Stacker Double sided bridge scraper reclaimer


6. Summary


Summary

• Three main stockyard functions: storage, blending and homogenizing

• Main characteristics of stockyard machines were presented• The effective capacity ratio for bucket wheel reclaimers

differs per reclaiming method; a method has been provided. • Different combinations of stacking methods and reclaimers

result in specific bed blending effect ratios.• A selection procedure was introduced to select single-

purpose or multi-purpose machines for the storage of bulk materials

• For a specific case, the stockyard layout was designed

• Future work: Design of the network of belt conveyors


Questions?

stockyard layout (re)design

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