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Impeller Restoration Extends Biomass Production Lifetime

aug 17 13Impeller Restoration Extends Biomass Production Lifetime

Among the renewable energy sources available today, generating biofuels from algae is a relative newcomer to the industry but one that has grown exponentially.

In fact, the algae products market is anticipated to only increase further, with projections indicating a potential $44.7 billion valuation by 2023. (Read More) Algae-based biofuels make up approximately a quarter of this estimate and point to the vast possibilities of this aquatic organism for the energy industry.

Because of its simpler compound structure and suspension in nutrient-rich solutions, algae can multiply rapidly in comparison to other traditional biomass crops, such as corn. This means that it can be continually harvested, with typical growth cycles for aquatic algae ranging between one and ten days. Meanwhile, it also benefits from a higher yield potential versus these other forms of biomass (in some cases as high as 20 times more) and requires a smaller surface area for cultivation. As a result, this makes algae production both highly sustainable and increasingly attractive in terms of future development and investment.

The process and its potential problems

In order to cultivate this form of biomass effectively, there are several different stages of the algae’s development. These include algal ponds, as well as photobioreactors, between which the nutrient-and carbon-enriched fluid is transferred and exposed to necessary sunlight. As the fluid is transferred between each area, it is prevented from settling by maintaining a highly turbulent flow within the reactor, using either a mechanical pump or an airlift pump. This turbulent flow can exacerbate issues such as erosion and corrosion damage, which traditionally trouble pumps and can result in faster rates of metal deterioration.

In addition, the algal biomass requires a contaminant-free environment, rid of any microbiological matter which could affect the algae’s growth or quality. Many producers will use high-strength chemicals to eliminate any unwanted growth, as well as chemical cleaning agents to disinfect the process equipment. When combined, this can take a significant toll on the lifespan of process equipment.

Disruption to algae production

This problem had significantly impacted Portuguese bioengineering company A4F (Algae for Future), who focus on the production of algae for a variety of different purposes, including biomass and biofuel generation. In 2014, their production process was continually being affected by the need to replace damaged pump components. With the pumps being cleaned on a weekly basis, the frequency of harsh chemical contact and erosion-corrosion caused by the fluid handling had resulted in severe metal loss on the impellers. The damage reached such an extent, that the company required a complete overhaul of three damaged impellers after just one year in service.

Polymeric solutions maintain green energy progress

To minimise downtime and avoid future replacement costs, the bioengineering company were in search of an alternative solution to their pump troubles. As a result, they contacted Belzona’s Portuguese Distributor, Belzona Portugal, with regards to using their cold-applied, polymeric materials for the repair and protection of pumps. Belzona Portugal had considerable experience in the restoration of process equipment and therefore suggested suitable solutions to repair and protect the impellers. These systems would be able to not only rebuild the metal loss, but also enhance the pump’s longevity against chemical attack and erosion-corrosion.

Following confirmation, all three pump impellers were cleaned and gritblasted to achieve the correct surface profile. This revealed the extent of the metal loss, which had resulted in complete deformation of the impeller blades. Fortunately, this could be rebuilt to its former design using a combination of wire steel mesh and Belzona 1311 (Ceramic R-Metal), a paste-grade metal repair material. Once the shape was restored, the impellers were coated using Belzona 1321 (Ceramic S-Metal) to provide additional protection. Together these materials provide enhanced erosion-corrosion resistance versus the original metal, whilst also providing outstanding chemical resistance to combat the aggressive cleaning agents.

Three years in service

In 2017, the pump impellers were revisited and found to still be in exceptional condition after three years of service. Compared to the short lifespan and excessive damage when unprotected, the Belzona coating had improved the longevity of the component significantly, much to the satisfaction of the client. As an additional precaution, the customer requested a further application of the coating, simply to ensure the successful protection was continued. Due to the overwhelming success of these applications, Belzona has been chosen to coat four new impellers in 2017.

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