Synergistic effect of droplet self-adjustment and rod bank internal on fluid distribution in a WFGD spray column

- The “droplet self-adjustment” effect is revealed.
- Characteristics of flow distribution in a WFGD spray column are proposed.
- An expression of the critical droplet diameter against gas velocity is defined.
- A synergistic effect of the “droplet self-adjustment” and rod bank internal is indicated.

With increases in the throughput requirement in a spray column, a column with a larger diameter and higher gas velocity will result in flow maldistribution, reducing the desulfurization rate and increasing the energy consumption of the column. In this paper, theoretical analysis and numerical simulation are utilized to characterize the flow maldistribution in a spray column with and without rod bank internal. Distribution mechanisms of “droplet self-adjustment” generated by droplets and resistance distributed effects generated by rod bank internal are presented in addition to their synergistic effects. Numerical research shows that trends of gas velocity uniformities and liquid loads perform synchronously in spray columns without rod bank internal; these will be improved with decreases in gas velocity and increases in droplet diameter. To acquire better column efficiency, an expression for critical droplet diameter is obtained in Eq. (28). In a spray column with rod bank internal, the optimized geometry for rod bank internal is acquired for better flow distribution and a lower resistance coefficient (ζp): s/dr = 2, H/D = 1/8 and h/dr=23. Under different operating conditions, variation trends of uniformities in columns with and without a rod bank internal are similar. The synergistic effect of distribution mechanisms generated by droplets and rod bank internal is shown; the distribution effect generated by droplets mitigates the peak of gas velocity to make the “droplet self-adjustment” effect work well across the whole column.