Global warming is currently one of the greatest threats to humanity; Latin America being one of the most vulnerable regions in the world.
Figure 1. Installation of a Neptuno Pumps VTP1000X, highly efficient pump custom designed for this application.
Pumps are essential to human life and are considered the heart of industries, accounting for 30% of total energy consumption on an average industrial site. However, 90% of pumps are operating at low efficiencies worldwide, wasting millions of dollars in energy and emitting millions of tons of carbon dioxide every year. Several studies have shown that an old worn pump operating 20% below its best efficiency point will consume up to 40% more energy and will produce twenty percent more carbon dioxide in order to deliver the same volume of water.
The mining industry is heavily dependent on water and energy, two resources which are particularly scarce and valuable in Latin America; nonetheless, pumping systems are still the “elephant in the room” for this sector, and no serious or definitive measures have been taken in order to improve neither their energy efficiency nor their carbon footprint.
To put in perspective, the global average carbon emission per person is 7 tons, which is approximately the weight of a large male elephant. At the same time, a single 15,000 hp reclaim water pumping system produces 106,900 tons of carbon annually; fortunately some mining companies have started noticing the 15,270 elephants in their pumping stations.
Figure 2. Visual of the carbon footprint volume those 3798 Figure 3. Rebowling service allows reusing valuable
tons of CO2 would occupy at standard pressure and 15°C. pump components keeping cost and lead times low.
The Choapa pumping system
Antofagasta Minerals’ Minera Los Pelambres in Chile, has led the transition towards a new more cooperative business model with its providers; creating synergies that have allowed them improve their pumping systems with outstanding economic and environmental results, saving millions of dollars in energy and reducing thousands of tons of carbon emissions each year (for more information read the award-winning article “Mining industry gets pump improvements”, World Pumps, Number 573, October 2014). In order to continue on this path, the company wanted to improve its Choapa pumping system, as shown in Figure 1, increasing its capacity and availability while saving energy. This pumping system consists of two pumping stations, namely Choapa 1 and Choapa 2, the first is located at 975 meters above sea level and was equipped with three seven-stage vertical turbine pumps with capacities of 686 (m3/h) and a total dynamic head (TDH) of 287 (m), powered by 1250 (hp) motors and operating at 68% efficiency, delivering a total pumping capacity of 1825 (m3/h). Choapa 2, located at 1219 meters above sea level, consisted also of three seven-stage vertical turbine pumps rated for a capacity of 650 (m3/h) and a TDH of 292 (m), also equipped with 1250 (hp) motors and operating at substandard efficiency of 68%, pumping a total of 1821 (m3/h).
Los Pelambres wanted to increase its pumping capacity in 5%, balancing the flow on both pump stations to 1919 (m3/h), while increasing its availability and reliability by replacing the old pumps with new equipment with more capacity in order to be able to pump with just two pumps, leaving one free space for a spare equipment. However the company was most interested in improving its system efficiency in order to reduce its electricity bills as well as its carbon emissions.
Due to the international success of its previous award-winning reclaim water repowering project, Minera Los Pelambres contacted the Chilean designers and manufacturers Neptuno Pumps in order to assess this challenge and deliver an innovative, efficient and sustainable solution.
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Figure 4. Choapa pump station powered by its original 1250 hp motors, located at Antofagasta Minerals’ Minera Los Pelambres in Chile.
The alternatives
The first alternative was to analyse if the old pump was capable of delivering the required capacity. The study showed that the addition of two stages would allow this equipment to deliver the required 1919 (m3/h). However, the new efficiency would have been increased in merely 6%, reaching substandard 74% pump efficiency, saving US$54,274 and US$ 47,418 annually per station. Nonetheless, the repair and maintenance costs would have increase in 29% due to the new added stages and components. Furthermore, in order to achieve this performance, a full overhaul and potential replace of all wet parts would still be needed, increasing the initial cost of the project in an extra US$200,000.
This alternative did not satisfy the customer, who was looking for high-impact economic and environmental results. Therefore the best solution would be to custom design a highly efficient pump, which could save energy reducing its carbon footprint, with larger capacity that could satisfy the new duty point with 33% less equipment, leaving a free space for a spare pump thus increasing the system’s availability.
The solution
As finalists of the 2015 Pump Industry Awards in the Technical Innovation of the Year – Products category with its engineered high-pressure vertical turbine pump design, known as the VTPX, Neptuno Pumps has characterised for custom engineering pumps for mining and heavy-duty applications. For this project Neptuno Pumps engineered its VTP1000X model, as shown in Figure 1, which offers a TDH of 294 meters and a capacity 960 (m3/h), thus delivering 37% more capacity than the previously used pump model. This tailored pump model offers a pump efficiency of 84%, being 15.4% more efficient than the old equipment, thus saving energy and lowering its carbon emissions. It was also designed in order to require just five stages to reach the TDH, meaning 30% less components in the bowl assembly, thus reducing its manufacturing time and final costs in approximately 29% compared to the first analysed alternative.
Figure 5. Recycling materials helps move towards a new circular economy.
Towards a circular economy
At stated above, the end user needed this solution with the lowest lead times and costs as possible in order to be able to operate fast and get the shortest payback period for this project. In order to accomplish this, Neptuno Pumps considered that some components from the previous pump could still be used, being the rebowling option the best and cost-effective solution for this application. A rebowling, as shown in Figure 3, is a great way to reuse valuable components and materials which, with minor repairs, can still be used thus lowering costs for the customer. A rebowling service offers the following benefits: • Hydraulic upgrade • Improved efficiency • Upgrade materials • New pump warranty • Reuse existing discharge head, column pipe and motor • Reduce energy consumption and maintenance costs
There was also an opportunity regarding the reuse of the old pump material. It is widely known that the production of cast iron and other metals is an energy intensive process but recycling these materials can reduce energy usage in about 70%. However, in the mining industry, worn metal components from old pumps are generally dismissed and transported overseas, further increasing its carbon footprint. Taking advantage of its own in-house foundry, as shown in Figure 5, Neptuno Pumps remelted and reused the gray iron ASTM A48 from the old pumps’ impellers and bowls it in order to use it for the production of the ductile iron ASTM A536 that was specified for the new bowl assembly.
For the new pumps power requirements, six existing 1500 hp motors from a previous award-winning project were reused (“Re-powering water reclaim systems”, World Pumps, Number 547, May 2012), thus taking advantage of valuable existing assets while keeping the projects costs low.
This new way of doing things represents a great option for the end user, not just by reducing its costs and carbon footprint, but by moving towards a new circular economy which does not just “throw things away” but reuses, reduces and recycles.
Results
The incorporation of these custom engineered pumps in the Choapa 1 pumping station, as shown in Figure 4, allowed an increase in capacity of 5%, stabilising it at 1919 (m3/h), and an efficiency improvement of 15.4%, thus reducing energy consumption in US$292,609 per year, while reducing carbon emissions in 1930 tons annually. The system’s capacity was stabilised at 1825 (m3/h) with 33% less pumps, being able to install a new stand-by pump, increasing the system’s availability and permitting an increase in capacity of 25.4% when operating with all three pumps, reaching 2288 (m3/h).
For Choapa 2, results were as impressive as in the previous station, also stabilising the capacity at 1919 (m3/h) increasing pump efficiency in 15.5%, which was translated in an annual energy saving of US$286,424 and a reduction of 1868 tons of CO2 emissions, also with 33% less equipment. The new stand-by pump would increase the system’s capacity in 23.5%, pumping up to 2253 (m3/h).
This custom engineered highly efficient pumps allowed the reuse of six existing 1500 HP motors and reused components and parts from the old pumps, considerably reducing the lead times and total cost of the project, allowing the company to start operating in just four months.
Sustainable mining
This project shows how a single pump station can represent a huge opportunity for saving money and fighting the effects of climate change. Upgrading pump systems with new custom engineered energy efficient equipment brought great economic and environmental benefits, reducing energy consumption in 15%, thus saving US$ 579,033 per year, and reducing 3798 tons of CO2, as shown in Figure 2, equivalent to avoiding the emissions of approximately 3800 cars annually. Furthermore, this innovation allowed the reuse of valuable assets such as the six 1500 HP vertical motors and other old pump components, like the discharge heads, shafts and column pipes, as well as recycling material from old worn pumps to produce the new equipment, offering a low-cost and fast turnaround, delivering the project in four months, with a payback period of just one year and with invaluable benefits for the surrounding communities and the environment. This project shows how companies are moving towards a more sustainable mining industry that will set the basis of this industry for the XXI century.
