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Alex Mtonga, Senior Mechanical Engineer & Bulk Material Handling Specialist, BMT WBM delivered this presentation at the 10th Annual Bulk Materials Handling conference 2013. This conference is an expert led forum on the engineering behind the latest expansions and upgrades of bulk materials facilities. It also evaluates the latest engineering feats that are creating record levels of throughput whilst minimising downtime. For more information on this conference, please vist http://www.informa.com.au/bmh2014
Citation preview
Minimising conveyor project
costs by design
Materials Handling Week, Brisbane
3 - 6 June 2013
Outline
• Introduction
• Conveyor system project costs
• Minimising costs by design
• Equipment selection
• Plant lay out (Maintenance)
INTRODUCTION
BMT is an international multidisciplinary science, engineering and technology consultancy.
BMT WBM is an Australian subsidiary of the BMT Group, with offices in Sydney,
Melbourne, Brisbane, Perth, Newcastle, Mackay, Denver and Vancouver.
BMT WBM has provided materials handling design and investigation services for over 40
years. Our experience in the field has included conveyor designs, modifications and
upgrades of existing systems.
In this presentation we explore ways in which we as designers can work towards
minimising overall project costs associated with a conveyor.
Conveyor system project costs:
Capital (initial) costs
Operating costs
Maintenance costs
• The total cost needed to bring a project to a commercially operable status.
• Costs associated with the day to day operation of the conveyor system. These
include both fixed and variable costs
• The costs incurred on activities which reasonably ensure that the design levels of
availability and performance of the conveyor system is achieved in order to meet
business objectives.
Conveyor system project costs
Costs due to lack of availability
Costs due to lack of reliability
• Costs incurred due to the conveyor system not being available to perform its
intended function as and when required
• Costs incurred due to the conveyor system not performing its intended function
as and when required
Minimising costs by design
Project business requirements and objectives
Minimising costs by design
Outages
In both planned and unplanned outage availability of a conveyor system
to perform its intended function becomes more important than the
supply and outage work costs due to production losses.
The designer has to understand the particular project requirements
and make design decisions appropriate for the particular project.
Provide an explanation of intended construction and installation
sequence plan to minimise duration of construction and installation
outage, hence minimise production losses
Minimising costs by design
Outages
Minimising costs by design
Removal sequence
• Magnet
• Magnet Frame
• Stair and Walkway
• Top of upper chute
• Scrapper
• Impact plate
• Upper chute
• Crossbeam
• Chute fingers
Minimising costs by design
Replacement sequence
• Chute fingers
• Packers adjusted
• New lower chute
• New Intermediate chute
• Grid mesh
• Modify upper chute
• Scrapper
• New impact plate
• Stairs re-installed
• Magnet
• Top of chute
Minimising costs by design
FIG. 3 –
Chute
installed and
in operation
Outages
Minimising costs by design
• Can determine the design to suit the construction requirements.
• Arrangement of construction work that has no direct impact on
the operations of the plant or equipment to be upgraded or
modified is possible before the actual outage.
Planned outages
Recently BMT WBM designed an intermediate drive unit with a
2 x 1000 kW drives. The unit was scheduled to be installed in a three
week outage but was installed and commissioned in less than the
planned three week outage.
Intermediate drive unit
Fig.4 -
2 x 1000 kW Drives
inserted into an
existing conveyor.
Business
requirement was to
minimise the
outage.
Intermediate drive unit
Fig. 5 - Intermediate drive unit. The unit was lifted in place in two fully
assembled sections connected by a pin joint and commissioned in less
than the outage planned timeframe of three weeks.
Intermediate drive unit
• Foundations were built in an early outage and buried and the
conveyor reinstated over them until the main outage.
Factors contributing in minimising the overall project costs and risk of
lost production included:
Intermediate drive unit
• The switch room and the VSD equipment including power supply were
erected besides the conveyor before the outage.
Intermediate drive unit
• The drive unit was fully assembled before the outage and lifted in
place in two sections connected by a pin joint. To complete the belt
line, two 30 m beam sections were used.
Impacts of programs
In projects with short programs, it is common for designers to make
decisions based on their past experiences and in most cases re-use
existing designs. Most often the decisions are based on incomplete
information and centred on meeting the program. Alternative solutions
are not fully investigated. The result is typically a conveyor system
design that meets the program but not optimised for the particular project
Figures 6,7 and 8 show such a case where the program was critical. The
design met the program but in operation the conveyor system had a lot of
tracking issues brought about by the screw take-up type considered in
the design.
Impacts of short programs
The screw take-up shown is considered not suitable. Difficult to
measure tension applied to the conveyor
FIG.6
Left & right take-up screws at tail pulley – Incorrect take-up tension settings
FIG.7 – Tail pulley tracked to one
side as a result of incorrect
take-up tension setting
FIG.8 – The servo roller on the
return belt tracker at the tail
end has worn through the
stringer as a result
Impacts of short programs
Impacts of programs
To get a more cost minimised design, the design team needs to get
involved early in the planning stage. Interaction between design costs
and other initial and ongoing costs need to be understood by both
designers and project managers if the lowest cost outcome is to be
achieved
FIG 9 – shows a 3-D model of new conveyors between and through
existing conveyors. Due to early involvement, the design team was
able to asses fitment of the new conveyors through a 3-D model
Early involvement of conveyor design team in
the project planning.
FIG 9 - 3 D modelling of new conveyors between and
through existing conveyors
Equipment Selection
Equipment selection can play a major role in minimising a conveyor
system life cycle costs.
• Must be selected considering the site conditions (more robust is often
better.)
FIG. 10 -
Columns
supporting
conveyors
damaged by
mobile plant
clean-up
Equipment Selection
• Selection must consider maintenance, including
- Skills required,
- Time taken for maintenance,
- Spares requirements,
- Ease of identifying faults, assessing condition.
• Should be a site standard, if practical.
• If it works why change it ? OR, Can it be done better?
Plant Layout (Maintenance)
The plant layout must be such that:
• It allows for maintenance to be carried out easily and efficiently.
• Minimises the number of steps.
• Minimises the time taken for the work.
• Has good access.
• Maintenance provisions are obvious.
• Includes lifting points, labels etc.
Figures 11, 12, and 14 show some examples of plant layout designs with
maintenance taken into consideration while Fig. 13 shows a typical example of
a design with no maintenance consideration
Plant Layout (Maintenance)
Fig 11
• Jack support,
Lifting lug,
• Bottom rail to
support pulley
in slack
position
• Removable
hangers to let
belt through
when hopper
is empty
Plant Layout (Maintenance) Fig 12
• Orange steelwork
is removable.
• Structure provided
for belt lifting
during pulley
removal.
• Lifting point
labelled.
• Concrete shaped
to facilitate
cleaning under
loading boot.
Plant Layout (Maintenance)
Fig 13 - Typical design
without maintenance
considerations
Fig 14 - Typical Design with
maintenance considerations
Plant Layout (Maintenance)
The designer needs to understand maintenance practices of the site where
the plant is to be used to ensure the design is appropriate to the site.
Some of the site specific issues that should be understood by the designer
include:
• The skill and capacity of site maintenance resources, and the availability
of local maintenance contractors. The design needs to suit the local
workforce.
• The maintenance equipment available at the site.
• The extent and type of existing plant on the site.
• The site power supply capacity.
Plant Layout (Maintenance)
• Environmental and land use issues. The choice of conveyor routes, and
overall design of the conveyors is often determined by the particular site
limitation, such as wetlands, culturally significant areas and residential
areas.
• How often the plant will be operated and how critical reliability issues are.
Conclusion
In conclusion, we can only encourage conveyor designers, project managers
and site personnel to communicate, to ask questions, and to listen to other
opinions, in order to make design decisions that truly minimise the cost for
the particular project.
Thank you / Questions
Alex Mtonga / Gary Ryan
t: (03) 8620 6100
w: http://www.bmtwbm.com.au