Coanda R&D Corp.

The application of CFD to liquid flows with suspended solids can be especially useful in numerous water-based processes. One particular application was for sand separation in a manure handling system. Our client wanted to know whether impeller mixers would be able to keep fine sand particles in suspension.

Our simulations were able to predict the settling rate of these larger particles and thus the client was able to determine how often the pit would need to be manually cleaned out to remove the settled sand.

Head over to our blog to discover more details on our modelling approach for this project:
https://coanda.ca/blog/cfd-sand-separation/

The residence time distribution (RTD) of piece of fluid-handling equipment like a tank, pipe, or reactor describes how much time fluid spends inside.

For example, in a batch mixer or ideal plug-flow reactor, all of the fluid spends the same amount of time in the vessel.

If we plot a distribution of fraction of fluid vs. the amount of time spent in the vessel, we get a spike corresponding to the residence time, as shown below (left).
On the other hand, for fluid flowing through an ideal continuous stirred tank reactor (CSTR), some of the fluid that enters the tank goes through immediately (because the tank is perfectly mixed), but some spends a longer time. This means there is a distribution of time spent in the reactor over all of the fluid elements passing through, also as shown below (middle)...

Head over to our website to discover more about residence time distribution in our blog:
https://coanda.ca/blog/rtd-modeling/

According to a 2024 study by a group of researchers in China, the domestic cost of biochar burial levelized to approximately $90/t (net CO2). The cost of removing 1.0 Gt/yr, which researchers believe to be a realistic objective, would therefore be in the region of $90 billion annually. While that is an enormous expense to offset 2-3% of global CO2 emissions, it is eclipsed by the cost of direct air capture (DAC), currently estimated at about $500/t. For reference, the cost of offsetting global emissions at $90/t is $3.5 trillion, whereas at $500/t, the cost is about $20 trillion. Both of these figures are comparable to the gross domestic product of major global economies (UK: $3.4 trillion, 6th; China: $18 trillion, 2nd).

Head over to our blog to discover more about biochar burial:
https://coanda.ca/blog/biochar-burial/