The Role of CFD in Process Development and Optimization

Solidia, a startup company founded in 2012, has developed a new concrete formulation to help tackle the CO2 reduction goals of the cement industry—the third largest producer of global greenhouse gas. We have worked with Solidia on the development and optimization of their curing chambers since 2013. This is our story.

Background

The cement industry has an ambitious goal. In order to meet targets set in the Paris Climate Accord, the industry must reduce its CO2 emissions by 16% before 2030, with some calling for pledges of carbon neutrality by 2050.  The cement industry is the third largest global greenhouse gas producer behind energy and transportation, and reductions of that magnitude cannot be met without major disruptions to the status quo. 

Every system Solidia builds is the first of its kind. Working with Kimbal Hall from Alden gives us confidence to skip costly physical prototyping, and accelerate our projects by months

George Perry, Director, Engineering, Solidia Technologies

When Solidia's new concrete formulation came into the picture, it was enough to turn heads. Unlike the portland cement curing process used throughout the industry, Solidia's technology relies on carbonation, a process that absorbs and sequesters CO2, literally mineralizing the carbon dioxide into rock.  For concrete companies, the most important aspect of this process is the end result: a product that needs shorter curing times, is higher in strength, has better dye uptake, and best of all, lowers the carbon footprint beyond that of anything else in the industry.

Experts are indeed hopeful. Solidia has several large investors, most notably LaFarge, who is the largest concrete manufacturer in the world. 

Solidia-Cement-NYT-Article-Cover-Photo

Photo courtesy of Solidia Technologies.

 

But first...

Solidia isn't the only player in this developing market—there are several startups that have their own process, but Solidia has a plan and it appears to be working.  Solidia’s business strategy is to first target the precast curing facilities to the greatest extent possible. These kind of products include pavers, cinder blocks, roofing tiles, etc.  By minimizing the required changes to existing facilities, Solidia and their industry partners will make use of existing infrastructure and experience, only changing what is necessary for these existing facilities to implement Solidia's technology.

So what needs to be changed?  Mostly the curing chamber.  A key difference in the Solidia process versus typical portland cement curing is that the product must be cured in a nearly 100% CO2 atmosphere, and water must be evaporated from the concrete before the carbonation reaction can begin.  Back in 2013, Solidia was getting great results with tiny samples, but was having trouble getting consistent results when they started to move to larger scales.  They needed some help to dial in their unique manufacturing process for optimum results.  That's when they called Alden.

Teaming with Alden 

Starting with their small scale curing chambers, Solidia relied on our computational fluid dynamic (CFD) and experimental testing expertise to better understand their process.  For each new chamber design, team members from Alden and Solidia met to discuss how best to achieve the latest objectives—something that's easily done when you can build on the numerous lessons learned from our partnership over the years. 

Once a concept is agreed upon, the Alden team takes the lead to optimize flow features in the chamber that ensure uniform evaporation from the surface of all products in the chamber. This allows for batch processing time to be minimized, since the slowest curing product in the chamber sets the duration of the entire process. Additional modeling and design work includes efficiently purging air from the chamber without wasting CO2, and optimizing the gas conditioning system so that the energy used for heating and drying the gas is minimized. 

Solidia-water-evaporation-CFD

Fig 1: CFD model indicating water evaporation rate inside curing chambers

Solidia-air-flow-circulation-CFD

Fig 2: Gas flow inside Solidia chambers is modeled for optimal conditions

Conclusion

Since 2013, Alden has acted as a general technical adviser to Solidia. Together, we have designed and built chambers up to 10’ wide x 18’ tall x 75’ long with tens of thousands of pavers each, and we are still going bigger.  Solidia is well on its way to full commercialization, and Alden has been there every step of the way.

Discover more: https://solidiatech.com/
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