Silicon carbide heat exchangers – new sealing technology

Generally, during API synthesis or other chemical syntheses, solvents vapours generated from the reaction must be cooled and condensed using a dedicated heat exchanger, also called an overhead condenser, located at the top of the reactor.
When the synthesis occurs under corrosive conditions, the condenser’s material in contact with the vapours and the reactor itself must be corrosion-resistant.

Three different types of heat exchangers are available on the market:

  • Shell and tube heat exchanger
  • Block heat exchanger
  • Plate heat exchanger

They can be provided in the following materials:

  • Hastelloy®
  • Impregnated graphite
  • Silicon carbide
  • Tantalum

To ensure optimum performance for our customers, we developed our own shell and tube silicon carbide heat exchanger with double tube sheets: one that is glass lined carbon steel -glass lined and one in stainless steel (1 CS-GL and 1 SS).

The glass lined carbon steel (CS) tube sheet has been replaced with a PFA lined tube sheet that is machined to guarantee maximum sealing:

  • Base tube sheet is machined before and after PFA lining
  • All surfaces are perfectly even, CNC machined under the desired precise tolerance
  • Carbon steel tubesheet is pressure rated and verified according calculation code (not possible with a PTFE solid tubesheet)

Senza titolo

Main advantage of the new design

  • Risk free SiC tube breakage

Holes on the 2 different sides of the tube sheets are perfectly even and parallel: no risk of torsion and/or unsuitable load for the SiC tubes.

  • High reliability of the sealing system

All surfaces are CNC machined. All sealing surfaces are perfectly machined with the desired dimensions and required tolerances. To note one sealing element (the PTFE wedge) has been removed. The compression of the O-ring may be increased on the length of the SS spacer.

  • Advantage for maintenance

Sealing kit (two O-rings and one spacer) is now standardised for different heat exchanger sizes so that the customer can perform maintenance on different equipment with only one spare parts kit.

Operative temperature conditions

  • PFA

The PFA range is from – 190°C to + 220°C and is suitable for temperatures from – 25°C to + 200°C as per our standard design conditions.

  • Viton™ O-rings

The Viton™ range is from – 15°C to + 200°C and is suitable for temperatures from – 15°C to + 200°C and not outside this range. Alternatively, O-rings suitable for temperatures from – 55°C to 200°C.

  • Perfluoroelastomer O-rings

The perfluoroelastomer range reaches maximum + 200°C; the range for minimum temperatures is from – 2°C (Kalrez® standard) down to – 17°C (using a special 0040 series for low temperatures); even lower temperatures may be reached with other perfluoroelastomer brands (other than Kalrez®) such as – 20°C or even  – 40°C (with NEXA® PFX).


Want to know more about the silicon carbide heat exchangers?

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