A recipe for success
There’s little argument that potash plays a central role in increasing food production for the world’s growing population. This is especially true for nutrient-poor areas of the world where crops need an additional boost and added protection from stressful conditions. There’s no substitute for this potassium-bearing group of minerals. Potash is readily available, although unevenly distributed, and mined in significant quantity in only 12 countries around the world.
The strength of potash is it contains water-soluble potassium. Potassium is a highly effective regulator that, when absorbed from the soil, allows plants to more effectively take in the right amounts of water and other nutrients. Plants in potassium-rich environments have stronger roots and stems, use water more efficiently, are better able to withstand extreme temperatures, and have greater resistance to disease. The strength of potash is then also its weakness; as a highly water soluble granular product it is prone to pulling water out of its ambient environment and, as a result, it tends to cake.
Although the potash caking issue is nothing new, the world’s largest potash fertilizer producers continue to seek effective methods to manage their product quality through the storage, loading, and shipping processes.
Natural properties that lead to unnatural business interruptions
As valuable as it is, potash is a difficult natural resource. Potash caking can cause serious business interruptions. If the potash cakes during the cooling and storage process then it can prove to be a challenge in the loading and distribution of the product. If the potash temperature is unstable during transport and it cakes en route, especially if it forms into large blocks, then it can be difficult to unload at port.
Figure 1. Solex's vertical-layout, indirect cooling system accepting and cooling potash in pre-loading storage area.
When manufacturers notice that they are prone to their potash fertilizer caking, they typically choose to halt or slow down operations and ensure they give the current batch time to cool and achieve a stable temperature. These types of delays can be costly and detrimental to return on investment (ROI) and potash fertilizer, as a traded commodity, is often manufactured on a nominal profit margin.
Bolstering the cooling process to ensure product integrity
The key to quality potash fertilizer is allowing the product to cool fully and completely, achieving a stable product temperature, before it is stored, loaded and transported, typically by rail, to its packaging and sales destination.
In 2013, JSC Belaruskali, one of the largest manufacturers and exporters of potash in the world, found itself in need of a solution to decrease its potash temperature before loading it into railways for distribution. As a natural insulator, potash can require significant time to cool, especially when the ambient air temperatures in storage areas and transport cars are not low enough to efficiently advance the cooling process. If potash fertilizer does not cool completely it is more likely to absorb water molecules out of the air, causing caking. Belaruskali decided that its risk of caking and amount of sub-quality product was significant enough to substantially reduce its production throughput and accommodate additional cooling days before moving its product from storage to loading and transport.
Rather than accept and account for this inefficiency in its process, this leading manufacturer focused on finding a consistent, highly efficient, cost-effective solution to its challenge. It quickly recognised that it needed a partner to help advance its practice of naturally cooling its processed potash fertilizer. It was hoping for an incremental, yet game-changing, addition to its process, which traditionally saw the high-temperature processed potash fertilizer stored in bulk and then moved, via a series of conveyors, to its railcar loading dock. JSC Belaruskali opted to partner with Solex Thermal Science Inc. (Solex), who sought out a small-scale pilot project to confirm that the company's indirect cooling technology would be effective in its operating environment.
In particular, JSC Belaruskali was seeking assurance that the technology could be adapted to its fertilizer production, ambient conditions and operating requirements. JSC Belaruskali needed to feel confident that Solex’s cooling system would stabilise the temperature of its potash fertilizer without introducing condensation, a sure recipe for caking, or other complications into its manufacturing process. It installed a small-scale version of Solex’s industrial fertilizer cooling technology as an incremental step in its predistribution cooling and storage in 2013, and fully embraced the merits of the cooling system within a couple of weeks. Belaruskali moved to Solex’s full-scale technology, which has a smaller operational footprint compared with traditional cooling approaches, in 2014.
By adopting Solex’s vertical-layout, indirect cooling system, JSC Belaruskali was able to not only resume its regular potash fertilizer throughput schedule, it was able to accelerate it. The deliberate emphasis on quickly and efficiently cooling its newly produced product allowed it to achieve a stable product temperature, assure product quality through both the storage and distribution process, and, ultimately, feel confident in its product quality year-round and regardless of ambient environmental conditions. In addition to decreasing its high product temperature problem and virtually eliminating en route caking, Belaruskali found that the vertical-layout, indirect cooling system was a low maintenance solution that also contributed to dust control and energy efficiency gains. As a sure sign of success, it is currently constructing a new Solex cooling system to expand its cooling capabilities. The new system is anticipated to be operational by mid-2017.
The advantages of vertical, indirect fertilizer cooling systems
The caking issue of potash fertilizers is directly tied to lower grade product and significant increases in natural cooling, loadout, and throughput times. The impact of low-grade product and lost time is lost revenue.
In the past, there were no easy-to-install, small-footprint, high-impact solutions to augment natural potash fertilizer cooling. Instead, large-scale industrial manufacturers, including Belaruskali, had to find the space, capital and time to install large-scale rotary cooling drums, fluid-based cooling beds or extensive conveyor systems that use multiple, industry-scale fans. Developed in the mid-1970s, these technologies were once ahead of their time. Today, when floor space is at a premium, environmental and energy conversations are common, and ageing facilities are facing retrofits, new options are needed.
The advent of vertical, indirect fertilizer cooling systems directly targeting the potash-caking problem gives manufacturers the cost-effective advantage of a small installation footprint, low operating and maintenance costs, near zero emissions, and, in many cases, up to a 90% reduction in energy use. Fertilizer manufacturers who choose this route realise the revenue gains associated with quality product and the ongoing cost savings that come with efficiency gains over time.
To understand the advantages of vertical, indirect potash fertilizer cooling systems, it is important to understand how they differ from their predecessors and other available Figure 1. Solex’s vertical-layout, indirect cooling system accepting and cooling potash in pre-loading storage area. As the innovator and first supplier of vertical, indirect fertilizer cooling systems, Solex combined the science of mass flow with the thermal efficiency of plate heat exchange design. It also developed proprietary thermal modelling software that regulates the conditions inside Solex’s cooling system and ensures the potash emerges at a precise and desirable temperature.
By design, the technology eliminated the conventional use of high-energy consumption air chillers and large fans to cool fertilizer in fluidbeds and rotary drums. Solex focused on a vertical tower that allows the fertilizer to slowly pass through proprietary offset heat exchanger plates that are cooled by water or other liquid mediums. One of its key strengths is that the design allows true counter-current flow of the cooling water inside the heat exchanger plates, which achieves greater thermal efficiency and, as a result, more effective cooling. The stainless-steel plates absorb the heat from the fertilizer and the product cools as, encouraged by gravity, it slowly moves through the tower. The potash fertilizer is cooled by conduction as opposed to convection (air cooling) and, as a result, the product cools evenly and without the risk of condensation, excessive temperature changes, and ultimately, caking.
This fertilizer cooling system is a complete equipment package, including a vertical cooler, a cooling water module, a bucket elevator and a purge air system. As a system, a tower can typically be installed within one week. With respect to operating requirements, the cooling system constitutes only a small additional load on any existing cooling water system and runs with exceptionally low horsepower. With high thermal efficiency and a large capacity of up to 150 thrust horse power (thp) in a single cooler, the cooler’s total power load is 85 kW (0.6 kWh/t of fertilizer). It typically saves 4 – 5 kWh/t compared to a fluidbed system, resulting in an accelerated ROI.
The industry impact
Whether a manufacturer is facing an immediate product quality challenge as a result of the hygroscopic nature of fertilizers, as was Belaruskali, or is simply looking for leadingedge yet proven practices to deliver consistent product in an efficient manner, it is clear that vertical, indirect fertilizer cooling systems have established a following in the market. The four largest potash fertilizer manufacturers in the world, including Belaruskali, Uralkali, Dead Sea Works, and PCS, are all making use of, or have projects underway to make use of, this cooling technology in their operations.
For an industry that depends on difficult resources, such as potash, and is continuously being pressed to examine its environmental impacts, it is promising to see technological innovations that have a game-changing impact on the market. There is a proven need for solutions that look beyond conventional design frameworks and integrate well into existing operations – especially when they directly tackle costly industry-wide challenges.
Figure 2. Vertical-layout, indirect cooling system, which also includes a vertical cooler, a cooling water module, a bucket elevator, and a purge air system.
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