When one process fluid is highly corrosive and tends to foul, how should it be routed in a shell-and-tube exchanger for easier maintenance and reliability?

Introduction / Context:
Fluid allocation to tube or shell side affects maintenance, pressure limits, and heat-transfer performance. For problematic fluids, correct routing can greatly reduce downtime and cost.

Given Data / Assumptions:

• One fluid is corrosive and fouling.
• Conventional removable-bundle design available.
• Objective is easier cleaning and component replacement.

Concept / Approach:
Routing corrosive or fouling fluids inside tubes is preferred because tubes can be mechanically or chemically cleaned, plugged individually if necessary, and made of a different (corrosion-resistant) alloy without making the entire shell of that alloy. Tube-side also confines hazardous inventory in smaller passages, reducing risk.

Step-by-Step Solution:
Identify the problem fluid: corrosive/fouling.Select routing that eases maintenance: tube-side for rodding/cleaning or replacement.Confirm design flexibility: tubes can use higher-alloy materials at lower cost than an alloy shell.

Verification / Alternative check:
Heat-exchanger selection guides list “corrosive/fouling fluid to tube side” among standard allocation rules, alongside high-pressure fluid to tube side.

Why Other Options Are Wrong:
Shell side: harder to clean mechanically; may demand costly alloy shell.Very low velocity: can worsen fouling by reducing wall shear; not a routing solution.Direction-dependent rule (outside if countercurrent…): not a recognized criterion.

Common Pitfalls:
Ignoring allowable pressure drop and velocity criteria; underestimating fouling factors in rating calculations.

Final Answer:
Preferably inside the tubes for easier internal cleaning