By: Mark L.Walde, Parramatta Group
New methods and technologies generally propel progress. And when discoveries contribute to cost savings, as well as more efficient, safer operations, the pace of progress accelerates. That’s because it can be measured in specific terms of productivity and profit.
So it is with conveyor systems, especially those handling bulk materials. A patented new approach, called the Controlled Flow Material Transfer System (CFMTS), addresses common, often costly problems and inefficiencies stemming from the transfer of materials from one belt conveyor to the next. Savings can be appreciable.
The system concentrates completely on controlling the movement of material within conveyor transfer points. Improvements in this area, along with a better understanding of the bulk handling of coal, led to the new approach, which models the flow of coal as a fluid using ceramic-tiled chute lining surfaces for the material to slide against. By applying this theory — which involves more than just adding hood and spoon hardware — it becomes possible to predict and direct material flow through complex transfer situations, and deliver it on to the receiving belt softly at a similar velocity and in the same direction.
The design concept can be applied to simple and complex conveyor systems alike. The hood and the spoon are the key physical components. In the hood section, material from the discharge belt is collected and concentrated. As the material moves through the chute, it is directed onto the spoon where it is softly and uniformly placed on the receiving belt.
Potential savings can be appreciable regardless of the size of the system or the number of transfer points. For a typical power plant, savings from replacing transfer chutes with CFMTS can exceed $400,000 annually, or $1,800,000 over a 10-year period. Consider a hypothetical coal handling plant consisting of:
- Five direct transfers, i.e., one feed belt loading material onto one receiving belt
- Two (2) two-way transfers, i.e., one feed belt loading material onto two receiving belts
- Two (2) three-way transfers, i.e., one feed belt loading material onto three receiving belts
- 15 load zones with traditional impact/slider beds
- 15 lower chutes, with skirts
- 3,000 HP original power equipment for all drives
- Standard AR liners in chutes
- Fully enclosed skirting system (installation estimated at $3,000)
- 60-inch wide belts with a total length of 20,000 ft.
The facility has an annual throughput of 4 million tons per year. Belt repairs are assumed at five-year intervals, and labor rates are set at $50/hr.
A number of separate though related factors contribute to the savings that can be achieved with an optimized material handling system:
Savings feature: Conventional skirting arrangements can often be eliminated by centrally and softly loading material in the direction of the receiving conveyor.
Savings Potential: An average 12 hours per year would be spent adjusting and maintaining a typical load point skirting arrangement. Additionally, about $200 of materials would normally be needed per year, e.g., replacement rubber, clamp strips and bolts. Thus:
.12 x hourly labor cost, plus $200 x number of on site transfer loading points x 10 years = Direct skirt savings over a ten-year period.
For the simulated coal handling plant, projected 10-year skirt savings would be ((12 x $50.00) + 200) x 15 x 10 = $120,000.
Impact Bed Savings
Savings Feature: Impact idlers or slider beds are not required if the receiving conveyor is soft loaded. Standard troughing idlers can be used instead and the required spacing between rollers can be increased.
Savings Potential: On average, 8 man-hours per year would be spent changing impact frames or slider bed components at typical transfer load points. An additional $400 of materials, such as rollers, would also not be required. Thus:
.8 x hourly labor cost, plus $400 x number of impact beds on site x 10 years = Direct 10-year cost savings.
For the simulated coal handling plant, projected 10-year impact frame savings would be ((8 x $50.00) + $400) x 15 x 10 = $120,000.
Reduced Maintenance Savings
Savings Feature: Correctly installed, ceramic-lined transfer chutes can process up to 200 million tons without maintenance.
Savings Potential: A conventional transfer chute with AR or stainless steel wear plates requires routine remedial maintenance. An average of 20 hours of maintenance per transfer point per year is a realistic estimate. There would also be a projected complete liner change over the 10-year period. Thus:
.(20 x hourly labor cost) x 10 years + the cost to supply and install a complete set of liners x the number of transfer sites = Direct 10-year maintenance savings.
A set of AR liners is estimated at $30/ft2 installed, and assuming 100 ft2 of liners per chute on average, then the cost to replace the liners = $30 x 100 = $3,000.
For the simulated coal handling plant, projected 10-year maintenance savings are .((20 x $50.00 x 10) + $3,000) x 15 = $195,000.
System Clean-up Savings
Savings Feature: Because CFMTS centrally and softly deposits material at a similar speed to the receiving conveyor, blockages are rare. The chutes are generally self-cleaning after a fully loaded stop event.
Savings Potential: Material hang-up, bridging, and blockages are not uncommon occurrences for conventional transfer systems. Another all-too-often occurrence is the cleaning of blocked chutes after an emergency stop. General clean-up costs, therefore, are ongoing. A conservative estimate would involve average clean-up time of one man-hour per week, per transfer system over a 10-year period. Thus:
.1 x 52 x (hourly labor cost) x 10 years x the number of transfer chutes = Direct cleaning savings.
For the simulated coal handling plant, 10-year clean-up projected savings would be (1 x 52 x $50.00 x 10 x 10) = $260,000.
Savings Feature: Power savings stem from the removal of friction at the loading point and the elimination of the need to re-accelerate the load as it moves from one transfer point to another. Conventional transfer systems deposit material onto the receiving conveyor in an uncontrolled fashion, generally as a vertical drop. After coming into contact with the receiving conveyor the material has to be moved from a standing start.
Other factors further contribute to lower power consumption. The CFMTS loads materials onto the receiving conveyor at low impact angles in the direction of the conveyor, and at a similar speed to the receiving conveyor. In effect, the controlled material stream helps the belt. In addition, skirting and impact beds are generally not required, resulting in reduced friction.
Savings Potential: For this calculation, to reflect total energy savings, the power is converted to kVA, operating hours for all conveyors are assumed, and an electric power cost of five cents per kWh is used. Thus:
For a total installed power of 3000 HP, we assume that the average consumption is 60-70% of the installed power, say
where 0.8 is the power factor and 1.34 is the conversion from HP to kW (kVA). Operating at 5000 hours per year yields 9.1 million kWh.
Reducing consumption by 2% (a very conservative estimate) saves 182,000 kWh or $9,100 per year at five cents per kWh.
For the simulated coal handling plant, 10-year power projected savings are $9,100 x 10 = $91,000.
Reduced Dust & Material Degradation
Savings Feature: CFMTS’s scientific design contributes to significant reductions in dust generation and material degradation. Material is accelerated, slowed and directed through the transfer with active contact surfaces enclosed by the material stream.
Savings Potential: This technology concentrates on the primary cause of dust, and eliminates the need for an expensive enclosed skirting system, baffle boxes or dust collectors. Thus:
Installation cost for a fully enclosed skirting system, baffle boxes and dust collection + associated ongoing maintenance over a 10 year period = savings relating to not needing these add-ons.
For the simulated coal handling plant, projected 10-year savings would be $3,000 for the skirting system and $200,000 for a standard dust collection system plus an estimated 40 man-hours per year on maintenance.
Therefore ((15 x $3,000) + $200,000) + (40 x $50 x 10) = $265,000.
Savings Feature: Due to its low angles of incidence, the operation of a CFMTS is quieter than conventional transfer systems.
Savings Potential: The reduced noise level proactively contributes to a safer working environment, which, in turn, helps companies comply with occupational health and safety requirements.
Reduced risk of employee health problems should translate into monetary savings, but due to its unpredictable nature, no attempt is made to quantify savings from reduced noise.
Reduced Belt Damage
Savings Feature: Controlled flow systems load material onto the receiving conveyor at low impact angles in the direction of the conveyor. Unlike conventional systems where severe impact is common, this approach makes it nearly impossible for a foreign object to damage the belt.
Savings Potential: Although damage from foreign objects is not a daily occurrence — once every five years is a realistic forecast — the resulting damage to the receiving conveyor represents a major maintenance job. Thus:
Belt repairs x 2 (estimated at five-year intervals) = Reduced belt damage savings.
For the simulated coal handling plant, projected 10-year belt damage savings would be [(2 men x $50.00 x 8 hours) + $500 belt cost] x 15 x 2-times per year = $39,000.
Reduced Belt Consumption and Splicing Costs
Savings Feature: Both system design and the flow of material protect the belt cover and prolong the belt life.
Savings Potential: Significantly, an independent NATA (National Australian Testing Authority) approved test on a ship loader boom conveyor at a 35 MTPA export coal terminal resulted in belt life operation three times longer than conventional systems. Thus:
Assuming the conveyors in the hypothetical handling system carry 4 million tons annually, with the 15 receiving belts totaling 20,000 ft in length and assuming an average belt cost of $60 per ft., then the total belt value is $1,200,000. The average service life of the belts is 20 million tons.
Belt cost per ton = Total belt value/Average service life =
= $0.06 per ton.
Belt life increase (conservatively figured at 50%) over a 10 year period = (1,200,000/(20,000,000 x 1.5)) = $0.04 per ton
At current values, this demonstrates a savings of $0.02 per ton in extended belt life, without taking into account associated Belt Splicing Savings.
Over a 10-year period the savings due to reduced belt cost are therefore: Total production x $0.02 x 10 = $800,000 or 67% of the total costs of belts on site.
Table 1 summarizes the cumulative savings possible using a controlled flow system. Whether evaluated on an annual basis or over a 10-year period, the savings are considerable.
Although the potential savings presented in this article are hypothetical, the potential for savings is real and available now. And while the CFMTS technology represents a new method for much of the world, it is a proven, production and profit driven approach (see sidebar).
Capacities Going Up Down Under
The vast majority of black coal exported from Australia — the largest coal exporting country in the world — passes through a Controlled Flow Material Transfer System. Approximately 20 of these systems have surpassed 200 million tons of service, with no system requiring a complete ceramic liner change. Based on this and other performance achievements, Parramatta offers an unconditional performance warranty on its CFMTS.
At the Dalrymple Bay Coal Terminal at the Port of Hay Point in Queensland, the installation of a CFMTS has boosted annual throughput capacity from 37.5 million tonnes to 44.4 million tonnes, an increase of more than 18%.
At the RG Tanna Coal Terminal of the Gladstone Port Authority in Queensland, another CFMTS has increased capacity by nearly 50%, from 30 million tonnes per year to nearly 45 million tonnes per year.
To help prospective customers to calculate anticipated savings, Parramatta Group application engineers perform cost analyses that pinpoint and quantify savings in key operational areas, as well as compute anticipated total annual savings.
Mark L. Walde has served as General Manager of Parramatta Group since the company’s formation in 2002. He joined Flexible Steel Lacing Company, Parramatta’s parent company, in 1988 and most recently served as a Field Engineer. In his present role he is responsible for new product development, sales and marketing for the entire Parramatta Group product line. Walde holds a Masters Degree in Business Administration from Northwestern University, and a Bachelor of Science degree from California State University – Chico.