In an ion exchange system, increasing the hydraulic loading rate (HLR) can be achieved by which measure?

In an ion exchange system, increasing the hydraulic loading rate (HLR) can be achieved by which measure?

• A. add exchanger vessels in parallel
• B. add exchanger vessels in series
• C. recirculate flow
• D. none of the above

Answer: (C)

Hydraulic loading rate is the flow rate through the exchanger per unit bed area (Q divided by A). To raise this rate without adding more bed area, you can increase the amount of water passing through the resin by looping some of the treated water back into the system. Recirculating flow increases the effective throughflow through the bed, raising the hydraulic loading rate. Adding vessels in parallel would spread the flow across more beds, so the per-bed loading rate stays the same or changes only with how you split the flow. Adding vessels in series increases contact time but doesn’t raise the flow through the bed itself, which lowers the per-bed loading rate. Therefore, recirculating flow is the measure that increases the hydraulic loading rate.

Hydraulic loading rate is the flow rate through the exchanger per unit bed area (Q divided by A). To raise this rate without adding more bed area, you can increase the amount of water passing through the resin by looping some of the treated water back into the system. Recirculating flow increases the effective throughflow through the bed, raising the hydraulic loading rate.

Adding vessels in parallel would spread the flow across more beds, so the per-bed loading rate stays the same or changes only with how you split the flow. Adding vessels in series increases contact time but doesn’t raise the flow through the bed itself, which lowers the per-bed loading rate. Therefore, recirculating flow is the measure that increases the hydraulic loading rate.