A CFD (Computational Fluid Dynamics) study is carried out with numerical simulation for fluid flows (gaseous or liquid), heat transfer and other phenomena related to combustion, aerodynamics, reactions, etc. its practical complexity requires real expert engineers to be able to make modeling a faithful representation of reality.
At DYNAMIS, with its engineers specialized in combustion, we attend all customers with due professionalism, and when it comes to our CFD studies we always start with process measurements carried out at the customer’s plant in addition to doing rigorous mass balances, general and specific for the subsystems, so that all the experience of our technical staff is effectively put into the base case and the case studies for improvements and so that technical solutions are valid and they provide the guarantees that our customers need.
Following, DYNAMIS presents several case studies, some with high complexity and even with unique solutions so that our customers can understand the true power of Dynamis Engineering.
D-Flame Burner Case
When designing a burner for combustion of alternative solid waste fuel (ASF or RDF), it is important for DYNAMIS to consider how it will burn inside the kiln. A 1D analysis gives an estimate of how the fuel is burned throughout the kiln. 3D analysis is primordial to provide us more information about the trajectory of particles. In addition to the injection velocity of a particle, the velocity of the primary air is important for understanding fuel dynamics.
Depending on the physical properties of the fuel (density, average diameter and sphericity), the impact of the flow will be different, having a direct impact on the burnout of the burner, being possible to predict how the burner will impact the process and the quality of the clinker, fundamental analysis for the industry of cement, in addition to predicting the trajectory of particles and their behavior, important for cement manufacturers, but essential for some mining kilns in complex calcinations such as nickel iron, vanadium, magnesite, lime and others, all of which have already been studied by DYNAMIS, so that the presence of solid particles does not damage the reactions and products in the kiln bed.
The 02 videos below show the impact of the flow for 2 situations in the cement industry: the first comparing the trajectories of coal and RDF injected through the burner tip. The second compares the trajectory of particles from the same RDF fuel, but of different diameters injected through a satellite.
D-Gasifier Case: Gasification Simulation
To verify the feasibility and later design our D-Gasifier, it is important to understand how heat and mass transfer occurs inside it. This analysis should consider the trajectory of the particle and its drying, in addition to devolatilization. Due to so many complex phenomena, the use of CFD is necessary to estimate how much of the fuel can be gasified in it.
The video below shows the consumption of coal inside the D-Gasifier. In cases of normal burners, the coal burns mainly inside the kiln, but this is not the case with the D-Gasifier. However, the fuel considered here is mainly composed of volatiles (66%), which burn almost completely inside the gasifier and indicate the suitability of the equipment for this case. The orange tone already indicates the complete consumption of coal particles (burnout) in the very beginning of the transition D-Gasifier/Kiln.
The different stages and phenomena that occur in the video can be better observed in the figure below:
DYNAMIS designs its D-Gasifier, with this powerful tool, in order to guarantee complete gasification in your equipment, in order to inject gaseous fuel (Syngas) and thermal energy into the kiln, in these types of application, in which low temperatures of process make it difficult to directly inject the same types of fuel (coke, or even biomass) into traditional burners.
A classic case for the use of D-Gasifier is in calcined clay kilns, which require process temperatures in the order of 700 – 900 oC (1.300 – 1.650 oF), but also another very popular case is the injection of fuel with 100% biomass, either for the lime or cement industry, both solutions supplied by DYNAMIS.
Grate Cooler Case
Fine particle drag can be an important bottleneck in a clinker grate cooling operation. Some cases already studied by DYNAMIS have already indicated a solution in which the tertiary air outlet position required a cyclone separator, so that the fine product does not return to the kiln, through this duct, and is recovered.
This CFD analysis, which requires modeling with highly experienced professionals, is useful for optimizing this process, as it helps in visualizing the flow and find an original solution, so a change in the tertiary air outlet can solve the reduction of fine particle drag.
In the grate cooler modeled below, hot gases are accelerated in the discharge kiln hood so that large amounts of fine particles are drawn into a cyclone inlet and not into the system again.
Calciner Case
One of the critical aspects of alternative solid fuel consumption (combustion) in a precalciner is the trajectory of the fuel particles. The contact between the fuel and tertiary air, as well as the entrainment of the particles, are necessary to guarantee the burning efficiency (see base case with petcoke in the video below that in the future it will be the basis of the alternative fuel model), and despite being a classic application of CFD study in cement industry, it requires that experienced professionals carry out this study so that the model faithfully reflects the real case of the application.
CFD analysis is useful not only for predicting fuel particle trajectories, but also for estimating feed point AF injection and the effects of operating conditions on CO and NOx emissions, in addition to raw decarbonation. In the next video, we can see the calcination process, through the LOI – loss on ignition (loss on fire) relationship.
In the precalciner below, the volatile content of the crushed tire injection is released, but due to the large particle size, in this case, the unburned large particles of tire chip fall to the kiln outlet.
Cyclone Case
One of the critical aspects in the geometry of a cyclone of a cyclone tower of a clinker is the excessive wear caused by the operation of the flour combined with the injection of solid fuels in the calciner.
Although granulometry strongly influences erosion on cyclone walls, the equipment’s intelligent design helps overcome problems like this. Using CFD tools, DYNAMIS has been continuously improving solutions to minimize wear and tear as transport air swirls with solid particles, as shown in the video below, developed on a DYNAMIS project.
This setup has proven to be successful in reducing the erosion rate and eliminating the problem of excessive wear on its lining, which also caused the refractory fall, which helped in scheduling maintenance downtime and increasing the life of the refractory.
It is important to point out that the studies for cyclones, whether in the development of new projects, or even in the evaluation of existing ones, DYNAMIS also applies other software, in particular computational analysis of FEA (Finite Element Analysis) to guarantee the integrity of the equipment and also the refractory fixation and its anchoring.
The cases presented above are examples of studies already delivered to customers or even in the internal developments of DYNAMIS equipment, but they do not necessarily represent isolated cases, since many studies of complex processes of an entire line of an kiln, with rotary kiln and pre -calcination, studied with our D-RK Kiln simulation and mass balance software , include specific studies of bottleneck solutions with CFDs to obtain the best specific solution for a single point in the process.
Get in touch with the DYNAMIS team, the best combustion professionals on the market and learn more about how we can improve your process with our tools and studies.
Dynamis.