Dear forum,
I am aiming to simulate a big reactor for gasification using PIC. For the moment, I am just testing a small domain. However, I am having some questions with how to apply the relevant BCs. The snapshots show the geometry reactor, with MI at the bottom, PO at top, a PO at the bottom small diameter inclined tube and a MI at the top small tube. In fact, the bottom PO and the top MI are connected through a riser and cyclone, which I aim to replicate as a change in temperature and composition of the particles between the PO and the MI (I found a post in the forum indicating how to “connect” two boundaries).
When setting the boundary conditions of these two small tubes, I find the issue that CG-MI is not compatible with PIC, neither does PS. The two small tubes are not in the same plane, so I cannot reduce the size of the domain without interferring with the main .stl walls.
Any clue on how to use a MI condition in that region? In fact, for future developments of this model, biomass will be introduced through the inclined part of the reactor. I was thinking about making smaller STL regions and selecting them for the biomass input, but the fact CG-MI and PS are not allowed comlicates things a lot.
Any support in this regard would be much appreciated.
Thank you,
Eduardo
Hello,
I have managed to get rid of the need of CG_MI by rotating the problem and doing some bricolage on the BCs. However, I am still wondering how to apply a mass inflow in the inclined part of the reactor.
Also, do you have any recommendation for code analysis and dependency trees? I normally do it manually, but I am going to do some modifications in the code. For example, following the following thread to replicate the riser, and I want to make sure I understand everything I am doing. How to count the number of parcels in the solid outlet, and then inject the same number of parcels to the solid inlet in MFIX-PIC? - MFiX - NETL Flow Science Software Support (doe.gov)
Thank you!
Hello,
Any help on how to set the biomass injection through the inclined wall of the system?
I have though about creating a large tube for the particles to enter the system and use a normal MI boundary condition. However, air will enter that tube, which will promote the particles to start reacting before entering the reactor.
Then, if the tube is too small, that forces me to use a very fine mesh for the .stl.
Sorry for the insistence, but any help in here would be really appreciated!
Thank you!
You should be able to extend the inlet tube so it goes past the MFiX box. Then apply the MI BC over a rectangular region that encompasses the intersection of the inlet tube and the box.
Thank you for your answer.
This was our first idea. However, in a previous experience, we saw that particles started to react inside the tube before entering the bed, as air can enter it, and this is unrealistic.
Is there any other possibility? For example, using this stategy combined with some internal surface that does allow the particles to go through but not the gas?
I wouldn’t say it is unrealistic for air to enter the tube, but I guess you want fresh particles to enter as close as possible to the cylindrical reactor. I think you could
a) Set the reaction rate to zero where particles are inside the inlet tube. Use a conditional statement based on the particles coordinates.
b) Add a rectangular box of No-slip-walls to cover most of the tube. Then you apply the MI BC along the area where this box is in contact with fluid cells. This would work if your inlet is aligned with the x or z direction.
Dear Jeff,
Thank you for your answer. Both solutions seem pretty good. In fact, I did not know that setting a MI boundary condition next to a wall even if this MI is “inside” the regions of the system would work (if I understood well). I will give it a try and get to you as soon as I have something.
