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Shell-and-Tube Heat Exchangers Made Simple: A Beginner’s Design Guide for Chemical Plants

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Shell-and-tube heat exchangers are a classic piece of equipment in chemical plants—and a favorite among mechanical engineers. Whether you’re designing your first exchanger or reviewing one from a vendor, understanding the basics is essential.

Even with software or handbooks, things can get confusing fast. This article walks you through the core concepts needed to design a condenser-type shell-and-tube heat exchanger, especially for batch-type chemical plants.


1. Focus on Fixed-Tube Designs

In batch chemical plants, fixed-tube sheet heat exchangers dominate—often over 99% of installations. They’re space-saving, reliable, and offer excellent sealing performance.

Why fixed-tube?

  • Minimal thermal expansion concerns
  • Limited cleaning required on the shell side
  • Compact layout
  • No sliding parts = better sealing

Even though floating-head designs allow for better maintenance access, fixed-tube setups are more than sufficient for most batch processes.


2. Tube Side vs. Shell Side: Where’s the Process?

In condenser-type exchangers, choosing tube-side vs. shell-side cooling depends on:

  • Materials compatibility
  • Cleanability
  • Required heat transfer rate

Generally, corrosive or special materials (like glass-lined or carbon steel) go on the tube side due to better cleanability and cost considerations.


3. Key Tube-Side Design Factors

  • Material
    Choose based on process fluid. Exotic materials mean tube-side duty is fixed early.
  • Flow velocity
    Critical for heat transfer coefficient (U). Calculated from Q and pipe dimensions.
  • Number of passes
    More passes = higher velocity, but exotic materials like glass-lined steel limit you to one pass.

For condensers, single-pass tubes are standard. Multi-pass setups often underperform due to gas-liquid separation issues and pressure drops.


4. Shell-Side Design Basics

  • Material
    If the shell handles utilities, mild steel is usually fine. If process fluid runs through the shell, use stainless or equivalent.
  • Flow velocity
    Important for liquid-side performance. Gas-side condensation doesn’t rely on flow speed as much.
  • Baffle spacing
    Shorter = higher velocity = better heat transfer—but also higher pressure loss.
  • Baffle cut
    Typically 25%. Orientation (horizontal vs. vertical) has minimal real-world impact, though vertical cuts are often preferred to avoid pooling of dirty utility liquids.

5. What About Cleanability?

Cleanability is often overstated in textbooks. In real-world batch plants:

  • Processes are usually mild
  • Equipment is reused across multiple chemicals
  • Corrosion-resistant materials are standard
  • Cleaning challenges are mitigated through design standardization or routine replacement

Most of the time, tube-side condensation with utility fluid in the shell is the default. Designing around exceptions is rare and usually not cost-effective.


✅ Conclusion

Shell-and-tube heat exchangers, especially fixed-tube condenser types, are foundational to batch chemical plants. By understanding a few critical parameters—material, flow velocity, and layout—you can design effective, practical systems.

While design handbooks and software help, grasping the logic behind choices ensures better judgment and troubleshooting.

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