Alex Mtonga, BMT WBM - Minimising Conveyor Project Costs by Design


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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

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Alex Mtonga, BMT WBM - Minimising Conveyor Project Costs by Design

  1. 1. Minimising conveyor project costs by design Materials Handling Week, Brisbane 3 - 6 June 2013
  2. 2. Outline • Introduction • Conveyor system project costs • Minimising costs by design • Equipment selection • Plant lay out (Maintenance)
  3. 3. 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.
  4. 4. Conveyor system project costs: Capital (initial) costs • The total cost needed to bring a project to a commercially operable status. Operating costs • Costs associated with the day to day operation of the conveyor system. These include both fixed and variable costs Maintenance 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.
  5. 5. Conveyor system project costs Costs due to lack of availability • Costs incurred due to the conveyor system not being available to perform its intended function as and when required Costs due to lack of reliability • Costs incurred due to the conveyor system not performing its intended function as and when required
  6. 6. Minimising costs by design Project business requirements and objectives
  7. 7. 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
  8. 8. Minimising costs by design Outages
  9. 9. Minimising costs by design Removal sequence • • • • • • Magnet Magnet Frame Stair and Walkway Top of upper chute Scrapper Impact plate • Upper chute • Crossbeam • Chute fingers
  10. 10. 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
  11. 11. Minimising costs by design Outages FIG. 3 – Chute installed and in operation
  12. 12. Minimising costs by design Planned outages • 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. 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.
  13. 13. Intermediate drive unit Fig.4 2 x 1000 kW Drives inserted into an existing conveyor. Business requirement was to minimise the outage.
  14. 14. 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.
  15. 15. Intermediate drive unit Factors contributing in minimising the overall project costs and risk of lost production included: • Foundations were built in an early outage and buried and the conveyor reinstated over them until the main outage.
  16. 16. Intermediate drive unit • The switch room and the VSD equipment including power supply were erected besides the conveyor before the outage.
  17. 17. 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.
  18. 18. 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.
  19. 19. 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
  20. 20. Impacts of short programs 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
  21. 21. 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
  22. 22. Early involvement of conveyor design team in the project planning. FIG 9 - 3 D modelling of new conveyors between and through existing conveyors
  23. 23. 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
  24. 24. 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?
  25. 25. 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
  26. 26. 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
  27. 27. 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.
  28. 28. Plant Layout (Maintenance) Fig 13 - Typical design without maintenance considerations Fig 14 - Typical Design with maintenance considerations
  29. 29. 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.
  30. 30. 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.
  31. 31. 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.
  32. 32. Thank you / Questions Alex Mtonga / Gary Ryan t: (03) 8620 6100 e: e: w: