Air quality is very important to the population health and the environment, being one of the themes more debated currently.  Nowadays, atmospheric pollution is increasing due to the large-scale use of fossil energies and production and use of chemicals.

Amongst the technologies for gas cleaning the filter bags are of great interes due to their low cost and efficiency. They are assempled in block of multiple filters in order to clean large volumes of air and reduce the pressure drop. On of the probles concern with possible flow maldistributions inside the assembly which leads to excessive wear and maintenance costs. .

The main goal of this project was to study the flow in a modular bag filter of a dedusting system at a Biomass Power Plant, in order to improve the filtration of the solid particles coming from the biomass combustion. The baghouse is composed by ten modules with two hundred and fifty-five filters each and it was sized for a flow of two thousand and twelve and four hundred cubic meters per hour (dry flow). Uneven flow distribution inside the bag house leads to increased wear in some of the filters due to frequent clogging. For this purpose, a numerical model using the ANSYS Fluent software was developed.

Initially, it was necessary to model the dedusting system in the software SolidWorks. Once this system had ten modules and to facilitate the simulation in Fluent, only one module was modelled with proper simplifications. Once the geometry was modelled, it was exported to Fluent where the mesh was made, with special care in the inlet zone of the module, as the most critical zone for simulation. Firstly, a simple case studied wherein the place of the filter is modelled as a single block with the size of the total number of the filters. In this study, it was concluded that the expected flow will not be the desired one, due to an oversimplification.

In the second stage, it was simulated four cases, where the filters were already modelled. Each one of the filters was modeled as porous jump boundary. A case with the normal operating conditions given by the company was simulated. Thereafter, two cases with different mass flow rates were simulated in order to assess the operation of the bag filter outside the normal conditions. Lastly, it was studied the influence of the vertical baffle’ size that is in the entrance of the module.

Comparing the last four studies, it was concluded that in the first three cases, the flow is very similar, with only a slight increase of the velocity in the study with higher flow, as expected. From the simulations, it was concluded that using a smaller vertical baffle, the flow distribution would be improved, as the filter near to the entrance would subjected to higher wear.


Numerical Study of the Flow Inside a Modular Bag Filter From a Biomass Power Plant

Division / Sponsors: 
Aerospace, Bioengineering, Applied Mechanics, Design Engineering Division, Advanced Energy Systems, Manufacturing Engineering Division, Noise Control and Acoustics, Nondestructive Evaluation, Diagnosis, and Prognosis (NDPD), Nuclear Engineering Division, Process Industries Division, Fluids Engineering, Heat Transfer, Materials, Microelectromechanical Systems, Safety Engineering and Risk Analysis, Computers & Information in Engineering


Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2020/volume/84478

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