1. Blasch Precision Ceramics
Understanding the Impact of a Collapsed Flue Gas Tunnel in a Top Fired Steam Methane Reformer

2. The StaBloxTM Reformer Tunnel System

3. Tunnel Collapse in SMR Scope of Study
A Computational Fluid Dynamics study was performed on a theoretical reforming furnace to determine the comparative results of flow uniformity in flue gas tunnels with and without a standing tunnel in the outer position.
Initial Input Information:
Furnace dimensions: 52.5’ W x 42.5’ H
Tunnel internal width: 26” W
Tunnel length: 52.5’ L
Tunnel height: 72” T
Number of catalyst tubes: 336
Number of flue gas burners: 96

4. Tunnel Collapse in SMR Scope of Study
A Computational Fluid Dynamics study was performed on a theoretical reforming furnace to determine the comparative results of flow uniformity in flue gas tunnels with and without a standing tunnel in the outer position.
STUDY CASE 1
Reforming furnace with all tunnels
Study Case 2:
Reforming furnace without an outer tunnel

5. Tunnel Collapse in SMR STUDY CASE 1 Reforming furnace with all tunnels
Reforming Furnace without an outer tunnel

6. Tunnel Collapse in SMR
A variable fine mesh setting was selected to provide a level of flow detail required for desired outputs. To increase refinement level for this study, a symmetric plane condition was used.

7. Results – Reforming furnace with all tunnels
Flow trajectories from the CFD results show that a reforming furnace operating with all tunnels will have a flow field covering the entire furnace, as designed. This theoretical reforming furnace could benefit from burner and tunnel port balancing to optimize the overall furnace profile.

8. Results – Reforming furnace with all tunnels
Uniform residence time is an important aspect of furnace efficiency, as total heat transfer is dependent on time. This graph shows a histogram of the time it takes specific particles to travel from the burners overtop of the outside tunnel row to the furnace exit.

9. Results – Reforming furnace with all tunnels
A temperature profile inserted vertically in the middle of the outer tunnel shows the flow field of the burners.

10. Results – Reforming furnace with all tunnels
Temperature data points can be taken along the length of the middle of each tunnel, 18in above the furnace floor. This graph shows those data points, with right side of x axis representing the exit of the tunnels.

11. Results – Reforming furnace without an outer tunnel
Flow trajectories show that a reforming furnace without an outer tunnel will have non uniform flow conditions.
Reforming furnace without an outer tunnel
Reforming furnace with all tunnels

12. Results – Reforming furnace without an outer tunnel

13. Results – Reforming furnace without an outer tunnel
The non uniform conditions shown by flow trajectories result in a wider range on a residence time graph.

14. Results – Reforming furnace without an outer tunnel
A temperature profile inserted vertically in the middle of the outer tunnel shows the flow field of the burners.
Reforming furnace without an outer tunnel
Reforming furnace with all tunnels

15. Results
Temperature data points taken along the length of the middle of each tunnel are plotted here. Each line represents one tunnel, with the outlier red line coming from the area where an outer tunnel would be.
Average temperature inside of tunnels with all tunnels intact: 1753 °F
Average temperature inside of tunnels without outer tunnel: 1681 °F
Average temperature inside of area where outer tunnel would be: 1537 °F

16. Results
Gas composition of a SMR is directly related to the temperature. The expected composition can be calculated for a tunnel with all tunnels 1750 °F) and a tunnel without outer tunnel 1730 °F 1681 °F)

17. Production and Economic Impact
Production Impact
This CFD model suggests that the percentage of hydrogen in the gas composition of the furnace output decrease if all the tunnels are not in place, as a result in the decreased furnace temperature.
The percentage of hydrogen could decrease by 9.7% in the furnace area adjacent to the missing outer tunnel
In a reforming furnace with 8 tunnels, the overall hydrogen output of the furnace could be reduced by 0.95%
Economic Impact
A chemical plant producing 2,000 MT of ammonia per day could theoretically decrease production by 19 MT; if the primary reforming output is a limiting factor.
At a bulk sale price of $300 / MT, the theoretical annual impact of running without an outer tunnel is: $2,074,800

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