Heat Exchanger Suitable for Fouling fluids, slurries
1. Scraped Surface Heat Exchanger (SSHE)
This is the ultimate solution for severe fouling or products containing large particles.
- How it works: A rotating blade assembly (scraper) continuously removes material from the inner heat transfer wall, preventing buildup.
- Why it’s perfect for fouling/slurries:
- Active Fouling Prevention: The scraping mechanism mechanically prevents fouling from ever forming.
- Handles Viscosity Changes: Can process fluids that change viscosity during cooling/heating (e.g., crystallization, solidification).
- Handles Large Particles: Suitable for mixtures with particulates and fibrous materials.
- Disadvantages:
- High Capital and Maintenance Cost: Complex design with rotating parts, seals, and drives.
- Higher Energy Consumption: Requires power for the motor.
- Limited Size/Scale.
- Ideal Applications: Food products (e.g., peanut butter, chocolate, margarine), polymers, waxes, heavy oils, and crystallizing fluids.
. Wide Gap Plate Heat Exchanger
A specialized variant of the standard plate heat exchanger designed for challenging fluids.
- How it works: Features specially designed plates with wide, free-flowing channels that prevent clogging and allow the passage of fibers or small particles.
- Why it’s suitable:
- Resists Clogging: The wide gaps prevent particles from getting trapped.
- Easy to Clean: Like all gasketed PHEs, it can be opened for inspection and mechanical cleaning.
- More Efficient than Shell and Tube: Still offers higher efficiency than a shell and tube unit.
- Disadvantages:
- Not suitable for very large particles or highly abrasive slurries (which can wear gaskets and plates).
- Pressure and temperature limits are lower than shell and tube.
- Ideal Applications: Pulp and paper stock, fruit juices with pulp, wastewater, fluids with fibers or soft particles.
3. Spiral Heat Exchanger
An excellent choice for fouling fluids due to its single, long, curved flow channel.
- How it works: Two long metal plates are wound around a central core to create two concentric, spiral flow channels.
- Why it’s suitable:
- Self-Cleaning Action: The curved path creates high turbulence and centrifugal force, which keeps solids in suspension and scrubs the walls.
- No Stagnation Zones: The single channel has no dead spots where material can settle.
- Handles Slurries: Very effective for fluids with suspended solids.
- Disadvantages:
- Limited Pressure Capability: The large, flat cover plates make it difficult to design for very high pressures.
- Not easily modified or expanded.
- Ideal Applications: Slurries, sludge, wastewater treatment, fluids with crystals, and viscous fluids.
Comparison Table
| Feature | Scraped Surface (SSHE) | Wide Gap Plate (PHE) | Spiral Heat Exchanger |
| Fouling Handling | Excellent (Active prevention) | Very Good (Resists clogging) | Very Good (Self-cleaning flow) |
| Slurry/Solids Handling | Excellent (Handles large particles) | Good (Small/soft particles) | Very Good (Suspended solids) |
| Cleanability | CIP possible, mechanical access can be complex | Excellent (Can be fully opened) | CIP, mechanical cleaning is difficult |
| Maintenance | High (rotating parts, seals) | Low (replace gaskets/plates) | Medium |
| Capital Cost | Very High | Medium | Medium-High |
Other Notable Option: Shell and Tube with Special Features
While standard shell and tube exchangers foul easily, they can be adapted for these services:
- Square Pitch Layout: Tubes arranged in a square pattern are much easier to clean mechanically (e.g., with a drill) than triangular pitch.
- Kettle Reboiler: A type of shell and tube with a large shell-side space that allows solids to settle out instead of clogging the bundle.
- Finned Tubes: Avoided for slurries, but studded tubes can be used to break up fouling layers.
- Advantage: Can be designed for very high pressures and temperatures where other types fail.
Ideal For: Adapted shell and tube exchangers are used in the oil and gas industry (e.g., pre-heating crude oil, which is very fouling) and other high-P/T fouling applications.