Stockyard layout (re)design

1
Stockyard layout (re)design

• Delft University of Technology

Faculty 3ME, Transport Engineering Logistics
G. Lodewijks, T.A. van Vianen and J.A. Ottjes
2
Export Terminal Saldanha Bay SA
2
3
Bulk terminal simulation
4
Content

1. Stockyard functions
2. Stockyard machines
3. The machine selection for capacity blending or
   homogenizing
4. The machine selection for the storage of bulk
   materials
5. CASE stockyard layout design for an import
   terminal
6. Summary

Delwaidedok, Antwerp (Courtesy HeliHolland/Kees
Vlot)
5
1. Stockyard functions
6
Stockyard functions
7
2. Stockyard machines
8
Stockyard machines - Overview (1)
9
Stockyard machines - Overview (2)
Bucket wheel reclaimer (Courtesy FAM)
Bucket wheel stacker/reclaimer, left stacking,
right reclaiming (Courtesy ThyssenKrupp)
10
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)
11
3. The machine selection for capacity blending
or homogenizing
12
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

13
Slewing reclaiming method A) top view and B)
lateral view
14
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
?x Max. chip thickness 1 m ?ss Minimum slewing speed 0.145 rad/min
?m Bulk density coal 0.8 t/m3 ?sm Maximum slewing speed 0.58 rad/min
lb Boom length 60 m as Maximum slewing acceleration/ deceleration 0.5 rad/min2
15

• 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

16
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 piles length 325 m h Slice height 4.5 m
w Piles width 50 m ?x Maximum chip thickness 1 m
h Height of the pile 18 m lb Boom length 60 m
?m Bulk density coal 0.8 t/m3 rbw Radius of bucket wheel 4.5 m
a Angle of repose 38 ?ss Start slewing speed 0.25 rad/min
vt Travelling speed 10 m/min ?sm 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        
17

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

18
Reclaiming efficiency versus the pile's length
for the long-travel reclaiming method
19
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 face
Bucket wheel reclaimer 12,000 0.4-0.8 30-60 Alongside
20
Blending or homogenizing machines

• Stacking is the starting point of the blending
  process. Generally there are four basic stacking
  methods

Reclaimer machine Stacking method Stacking method Stacking method Stacking method
Reclaimer machine Cone Shell Chevron Strata Windrow
Single scraper reclaimer and Portal 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 7-8
Bucket wheel reclaimer - 4-5 5-6 4-6
21
4. The machine selection for the storage of bulk
materials

• Selection of archetype
• Cost calculation
• Operational performance

22
Selection of archetype

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

Two layout archetypes
23
Cost calculation

• Selection must be based on the archetypes
  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
Price per meter for belt conveyors versus its
transport capacity
24
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

25
5. Case stockyard layout design for an import
terminal
26

• 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 seasides port time (Wss) 3 days and
  average landsides port time (Wls) 0.5 day
• Blending of coal 1.7 Mt/y
• 28 different grades of bulk materials must be
  stored separately

27

• Step 1
• Determine the number of stockyard lanes (nl) and
  dimension the stockyard lanes (length Ll and
  width w).
• Assume a machines boom length (lb) of 60 meter
  and use 10 meter as distance from the machines
  centerline to the stockyard lane (p).
• Assume that the lanes 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

28
Step 2 Determine the required machine capacity
based on Wss 3 days and Wls 0.5 day for both
archetypes.
29
Step 2 results of the simulation study
Layout Machine Cs kt/h Cr kt/h
A Stacker/Reclaimer 3.8 4.5
B Stacker 3.6
B Reclaimer 2.7
30

• Step 3
• Calculate the total investment cost per
  archetype.
• Calculate the stockyard machines 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 ?sm 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
  ?bc 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
B Stacker 3.6 409 3.3 5 16.1
B Reclaimer 2.7 506 4 3.8 16.1
31

• 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
  plants own storage of 5 days and use two
  blending beds for simultaneously stacking and
  reclaiming.

32
Step 5 Final layout.
33
6. Summary
34
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

35
Questions?