Secondary Mixing Device: Qidong Coal Mine’s "Magic Mixer," the Ultimate Cost-Saving and Efficiency-Boosting RTO Equipment!
Imagine a "magic mixer" that can turn dangerous gas into safe energy while saving costs for enterprises—doesn't it sound like futuristic sci-fi technology?
At Qidong Coal Mine, this "magic mixer" is the secondary mixing device. Today, we'll unveil this incredible device and see how it "mixes" both environmental and economic benefits into a win-win solution!
01 Secondary Mixing Device
The ultra-low-concentration gas regenerative oxidation Phase I project at Qidong Coal Mine not only installed a set of primary and secondary gas mixing and delivery systems but also equipped two 60,000 Nm³/h regenerative oxidation furnaces and two 7 t/h medium-temperature, medium-pressure waste heat boilers.
After completion, the project not only met the mine's heating demands but also achieved "zero emissions" of extracted gas, significantly reducing operational costs. It created substantial economic benefits for the coal mine while delivering dual environmental and social advantages.
Operational Benefits:
- Annual gas destruction volume: 55 million m³
- Annual carbon reduction: 250,000 tons CO2e
Behind this success lies the project's highlight technology—the secondary mixing device. Its design purpose was to solve the issue of excessively high initial gas concentration at the front end.
To ensure system safety and mixing uniformity, the project team adopted a two-step strategy:
- The primary mixing system first reduced the gas concentration to 8%.
- The secondary mixing device was then diluted further to 2%, achieving an astonishing ≥97% mixing uniformity.
02 Optimizing Mixing Performance
To maximize the "magic mixer's" efficiency, the project team used Fluent software for simulation during the design phase. By setting gas parameters, boundary conditions, and establishing mathematical models, they performed local mesh refinement in complex jet pipe areas using Fluent Meshing, ultimately generating 4.4 million grids.
| Mesh Quality | Locally Refined Area | Surface Mesh |
| Minimum Mesh Length (m) | 0.022 | 0.08 |
These grids achieved a minimum orthogonal quality of 0.268, far exceeding the 0.15 requirement, with no negative grids, ensuring high-quality simulation.
Local Mesh Refinement
Additionally, the project selected M125Y-type packing, combining linear and arc designs to optimize mixing further.
Simulation Parameters Table:
| Viscous Resistance Coefficient | Inertial Resistance Coefficient | Porosity | Height (mm) |
| 563,000 | 26.8 | 0.98 | 200 |
Model Diagram:
Final Installation & Operation:
Through the coordinated operation of the primary and secondary mixing devices, the system not only became safer but also achieved more thorough mixing, maintaining uniformity above 97%.
03 Conclusion
The secondary mixing device is Qidong Coal Mine's "magic mixer." It not only makes gas safe and controllable but also delivers tangible economic and environmental benefits. In the future, as this technology spreads, more coal mines may join this "waste-to-resource" green revolution.
Are you ready to witness the magic?