DEM simulation applied to boilers
- Alvaro Filho
- 7 days ago
- 4 min read
The use of biomass as an energy source has gained relevance in the industrial scenario. Coming from waste from other processes, this type of fuel represents a viable and sustainable alternative. When used in efficient combustion systems, it contributes significantly to reducing operating costs, reduces greenhouse gas emissions and strengthens the company's image, especially in a market that is increasingly attentive to sustainability criteria and seals.
Figure 1 – Biomass
In the case of boilers that use biomass, the combustion involves organic materials such as wood chips, sugarcane bagasse, rice husks and agricultural waste that provide thermal energy to generate steam for generating electricity or for industrial processes.
Figure 2 – Boiler
The efficiency of the combustion process in boilers is directly linked to the adequate flow of fuel over the grate. In fixed grate systems, the uneven distribution of material, including the presence of layers already consumed over portions not yet burned, can cause localized accumulations and the formation of regions with incomplete combustion, reducing thermal efficiency.
This effect increases the amount of unconsumed residue, increasing specific fuel consumption, since a significant portion of unburned biomass will be present among the ashes. This unburned biomass, in addition to reducing boiler efficiency, can cause accidents due to spontaneous combustion that can occur when it is removed from the boiler while hot and comes into contact with oxygen in the air again. Some companies report accidents, for example, when blowing air to unclog the ash collection hopper and the air comes into contact with the unburned biomass.
Figure 3 – Wood chips
Given these limitations, different grate configurations have been studied and applied to improve the movement and distribution of biomass during combustion. Modeling the flow of this material in the boiler is essential to optimize its behavior, considering physical properties such as particle size and density, in addition to the characteristics of the grate. These solutions aim to promote a more homogeneous flow, favoring contact between the biomass and the air, reducing regions with excess or deficiency of fuel and allowing the identification of critical zones.
Modeling biomass flow with Simcenter Star-CCM
Simcenter STAR-CCM+ offers advanced features to simulate the behavior of granular materials and particles through the DEM (Discrete Element Method) methodology. The model is based on the representation of particulate materials as a set of discrete particles that can interact with each other and with solid surfaces.
Figure 4 – DEM element
This approach allows to accurately represent the interaction between biomass particles and internal boiler components, such as the vibrating grate, in addition to incorporating operational parameters and physical characteristics of the material.
Figure 5 – DEM elements in contact
During the simulation, it is possible to configure the grate inclination and analyze how this variable, together with gravity, influences the speed and flow pattern of the biomass. It is also possible to adjust the intensity and direction of the vibrations (horizontal, vertical or combined), observing how these forces affect the movement of the material.
In the simulation, the behavior of the particles on the same grate was analyzed, one in a static configuration (top) and the other in a vibrating configuration (bottom), both maintained at the same inclination. Video 1 illustrates the simulation of the aforementioned cases.
Video 1 – Biomass flow velocity using DEM (side view)
Although the grate was inclined, the particles did not present the same flow observed in the vibrating configuration. This behavior is related to the nature of the particle material, which, due to its physical characteristics, does not allow flow in the static configuration. This comparison highlights the importance of simulation, where it is possible to predict behavior under different scenarios.
This flexibility allows identifying ideal configurations that avoid clogging, promote uniform flow and maximize combustion efficiency. In addition, specific characteristics of the biomass, such as particle size and distribution, density, roughness and friction coefficients, can be incorporated into the model. This makes the simulation more realistic and faithful to real operating conditions, allowing for more accurate prediction of the behavior of the material inside the boiler.
In biomass combustion simulation, the use of numerical models allows for the prediction and correction of problems before they occur, optimizing system performance. In Simcenter STAR-CCM+, simulations make it possible to evaluate different operational scenarios before building or modifying boilers. By changing parameters such as grate inclination and vibration intensity, it is possible to analyze the impact of these variables on the flow and distribution of biomass, identifying problems such as material accumulation, irregular flows or low-burning zones even in the design phase. This prevents late corrections, resulting in more assertive decisions, reducing the need for field adjustments and preventing unscheduled shutdowns. With these adjustments, there are gains in thermal efficiency, lower fuel consumption and reduced emissions.
These approaches illustrate how the use of simulations and numerical models, such as DEM, becomes a strategic tool, providing more efficient and sustainable operations, whether in mineral handling or in the design of burning systems.
Do you want to maximize the efficiency of your boiler and reduce operating costs safely and sustainably? Schedule a meeting with CAEXPERTS and find out how DEM simulation in Simcenter STAR-CCM+ can transform the performance of your biomass burning system. Let's find the best solution for your process together!
WhatsApp: +55 (48) 98814-4798
E-mail: contato@caexperts.com.br
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