Stockyard layout (re)design
Delft University of Technology
Faculty 3ME, Transport Engineering & Logistics
13-05-2013
G. Lodewijks, T.A. van Vianen and J.A. Ottjes
Delft
University of
Technology
Challenge the future
Stockyard layout (re)design
1
Export Terminal Saldanha Bay SA
2
Stockyard layout (re)design
2
Bulk terminal simulation
Stockyard layout (re)design
3
Content
1.
2.
3.
4.
5.
6.
Stockyard functions
Stockyard machines
The machine selection for capacity & blending or homogenizing
The machine selection for the storage of bulk materials
CASE: stockyard layout design for an import terminal
Summary
Delwaidedok, Antwerp (Courtesy HeliHolland/Kees Vlot)
Stockyard layout (re)design
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1. Stockyard functions
Stockyard layout (re)design
5
Stockyard functions
Storage
(A)
Blending
x(t)
σ x(t)
y(t)
σy(t)
t
t
(B)
t
(C)
Homogenizing
x(t)
σ x(t)
y(t)
σy(t)
t
Stockyard layout (re)design
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2. Stockyard machines
Stockyard layout (re)design
7
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)
Stockyard layout (re)design
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Stockyard machines - Overview (2)
Bucket wheel reclaimer (Courtesy FAM)
Bucket wheel stacker/reclaimer, left: stacking, right: reclaiming (Courtesy ThyssenKrupp)
Stockyard layout (re)design
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Stockyard machines - Overview (3)
Double sided bridge scraper reclaimer (Courtesy ThyssenKrupp)
Reclaiming with a side scraper and stacking with an
overhead belt conveyor (Courtesy Taim Weser)
Stockyard layout (re)design
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3. The machine selection for capacity
& blending or homogenizing
Stockyard layout (re)design
11
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
Stockyard layout (re)design
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θmax
As(θ)
ωs
θ
(A)
Δx
M’
M
Δx
As(θ)
p
Δr
(B)
hs
ωr
h
Slewing reclaiming method A) top view and B) lateral view
Stockyard layout (re)design
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Nominal reclaiming capacity:
C r   h s  x cos( ) 
Parameter
Description
 ss
cos( )
Value
Unit
Parameter
4.5
[m]
rbw
1
[m]
ωss
 lb  rbw   m
Description
Value
Unit
4.5
[m]
Minimum slewing speed
0.145
[rad/min]
hs
Slice height
Radius of bucket wheel
Δx
Max. chip thickness
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]
Stockyard layout (re)design
14
• 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
0.5
2.0
0.5
2.0
Cr
ωs
0.4
1.2
0.3
1.2
0.3
0.8
0.2
0.8
0.2
0.4
0.1
0.4
0.1
0
0.0
0.0
0
10
20
30
40
50
60
70
θ [°]
Without slewing speed adjustment
80
90
Cr [kt/h]
1.6
ωs [rad/min]
0.4
Cr [kt/h]
1.6
ωs [rad/min]
Cr
ωs
0
0
10
20
30
40
50
60
70
80
90
θ [°]
With slewing speed adjustment
Stockyard layout (re)design
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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.
Parameter
Description
Value
Unit
Parameter
Description
Value
Unit
4.5
[m]
lt
Total pile’s length
325
[m]
h
Slice height
w
Pile’s width
50
[m]
Δx
Maximum chip thickness
1
[m]
h
Height of the pile
18
[m]
lb
Boom length
60
[m]
rbw
Radius of bucket wheel
4.5
[m]
ρm
Bulk density coal
0.8
[t/m3]
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]
Stockyard layout (re)design
16
• The effective capacity ratio was for the long-travel reclaiming
method 75% and for the slewing bench reclaiming method 45%
2.5
Note: these ratios are
not general but were
derived using specific
input parameters
long-travel
slewing bench
2.0
Cr [kt/h]
1.5
1.0
0.5
0.0
500
505
510
515
520
525
530
535
540
Time [min]
Reclaiming capacity during a time interval of 40 hours for two reclaiming methods
Stockyard layout (re)design
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2
1.6
Cr [kt/h]
1.2
0.8
0.4
0
50
100
150
200
250
300
350
lt [m]
Reclaiming efficiency versus the pile's length for the long-travel reclaiming method
Stockyard layout (re)design
18
Stockyard machines
Main Characteristics
Machine type
Stacker
Radial stacker
Side scraper
reclaimer
Single boom portal
scraper reclaimer
Double boom portal
scraper reclaimer
Bridge scraper
reclaimer
Bridge bucket wheel
reclaimer
Drum reclaimer
Bucket wheel
reclaimer
Maximum Effective capacity Stockpile
Reclaiming
capacity [t/h]
ratio [-]
width [m] method to the pile
10,000
0.5-0.65
30-60
8,000
0.5-0.65
Ø120
1,000
0.75
10-25
Alongside
2,200
0.75
15-60
Alongside
4,400
0.75
15-60
Alongside
1,800
0.95
15-60
At the face
10,000
0.95
30-60
At the face
4,500
12,000
0.95
0.4-0.8
20-50
30-60
At the face
Alongside
Stockyard layout (re)design
19
Blending or homogenizing machines
• Stacking is the starting point of the blending process. Generally
there are four basic stacking methods
 

in
 out
Reclaimer machine
Single scraper reclaimer
and
Portal scraper reclaimer
Bridge scraper reclaimer
Bridge bucket wheel
reclaimer
Drum reclaimer
Bucket wheel reclaimer
Cone
Shell
2
Stacking method
Chevron Strata
Windrow
2
3-4
4-6
-
10
5-6
8-9
-
4-8
4-6
4-8
-
9-10
4-5
4-6
5-6
7-8
4-6
Stockyard layout (re)design
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4. The machine selection for the
storage of bulk materials
• Selection of archetype
• Cost calculation
• Operational performance
Stockyard layout (re)design
21
Selection of archetype
• Multi-purpose machine (stacker/reclaimer) or two single-purpose
machines (stacker and reclaimer)
A
ṁin
ṁout
(I)
(A)
B1
ṁin
ṁout
B2
(B)
(II)
Stacker/reclaimer
Incoming stream
Stacker
Reclaimer
Outgoing stream
Belt conveyor
Stockyard lane
Two layout archetypes
Stockyard layout (re)design
22
Cost calculation
• Selection must be based on the archetype’s investment cost and
performance
• It was assumed that the machine investment cost relates to its weight
and the belt conveyor investment cost relates to its capacity
10
1,200
lb=25±3 [m]
lb=30±3 [m]
1,000
lb=37±3 [m]
8
lb=46±1 [m]
7
lb=63±3 [m]
κbc [k€/m]
w [t]
800
Upper limit
Lower limit
Quotations: 1 ≥ Lbc ≤ 1.5 [km]
9
600
400
6
5
4
3
2
200
1
Cs + Cr [t/h]
Stacker/reclaimers weight versus
capacities as function of boom length
Cbc [kt/h]
Price per meter for belt conveyors versus
its transport capacity
Stockyard layout (re)design
23
10
9
8
7
12
6
10
5
8
4
6
3
4
2
2
1
0
0
0
0
Operational performance
• 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
Stockyard layout (re)design
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5. Case: stockyard layout design for
an import terminal
Stockyard layout (re)design
25
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
Stockyard layout (re)design
26
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:
A  n l L l l b  p 
• An outcome is nl = 14, Ll = 1,315 [m] and w = 50 [m]
Stockyard layout (re)design
27
Step 2:
Determine the required machine capacity based on Wss ≤ 3 days and Wls
≤ 0.5 day for both archetypes.
1,315 [m]
Layout A with 7x archetype (I)
1,315 [m]
A
C
E
K
M
D
F
SR2
C
E
R1
S2
D
F
G
R2
H
J
SR3
B
S3
I
K
M
R3
S4
L
N
O
R4
P
R
R5
T
V
S5
H
Q
J
S
L
N
SR4
O
S6
U
W
Y
R6
S7
X
Z
AA
R7
BB
P
Q
SR5
R
S
U
SR6
T
V
W
Y
A
B
SR1
G
I
S1
X
Z
SR7
AA
BB
Stacker
Bulk carrier
Reclaimer
Train
Stockyard lane
Stacker/reclaimer
Bulk carrier
Stockyard lane
Train
(un)loader
Yard conveyor
Yard conveyor
(un)loader
Layout B with 7x archetype (II)
Stockyard layout (re)design
28
5.0
1.0
4.5
0.9
4.0
0.8
3.5
0.7
3.0
0.6
Wls [d]
Wss [d]
Step 2: results of the simulation study
2.5
0.5
2.0
0.4
1.5
0.3
1.0
0.2
Layout A: 7x archetype (I)
0.5
Layout B: 7x archetype (II)
0.0
Layout B: 7x archetype (II)
0.0
1.0
(A)
Layout A: 7x archetype (I)
0.1
1.5
2.0
2.5
3.0
Cs [kt/h]
Layout
A
B
3.5
4.0
4.5
1.0
1.5
2.0
3.0
3.5
4.0
Cr [kt/h]
(B)
Machine
Stacker/Reclaimer
Stacker
Reclaimer
2.5
Cs [kt/h]
3.8
3.6
Cr [kt/h]
4.5
2.7
Stockyard layout (re)design
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4.5
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): IC
 w
sm
sm
where for this case it was assumed that κsm was 8 [€/kg], machine fully
installed at the stockyard
IC bc  L bc  bc
• 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
A
B
Machine
Cs [kt/h] Cr [kt/h] w [kt]
Stacker/Reclaimer
3.8
Stacker
3.6
Reclaimer
4.5
2.7
ICsm [M€] ICbc [M€] TIC(A) [M€]
925
7.4
6.3
409
3.3
5
506
4
3.8
Stockyard layout (re)design
13.7
16.1
30
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.
Stockyard layout (re)design
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Step 5:
Final layout.
1,315 [m]
A
C
E
B
SR1
D
F
SR2
H
G
I
SR3
J
K
M
SR4
L
N
P
O
Q
SR5
R
S
U
SR6
T
V
W
Y
X
Z
SR7
BB
AA
Stacker/reclaimer
Bulk carrier
Stockyard lane
Train
(un)loader
Stacker
Yard conveyor
Double sided bridge
scraper reclaimer
Stockyard layout (re)design
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6. Summary
Stockyard layout (re)design
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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
Stockyard layout (re)design
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Questions?
Stockyard layout (re)design
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