Main benefits
  • Easy and safe scale-up since your crystallizer consists of the same tubular elements used in our pilot plants 
  • Ease of operation, since there is no crystal slurry handling and no filtration 
  • Our customers report high reliability and low operating costs 
  • Environmentally safe process due to inert gas blanketing and the absence of solvents 
  • Minimization of thermal degradation (cracking, polymerization) thanks to operation at melting point instead of boiling point
Main applications
  • Organic and inorganic chemicals at high purities
  • Monomers
  • Carboxylic acids
  • Aromatic isomers
Falling film crystallizer
Falling film crystallizer


The crystallizer consists of a system of vertical tubes. The collecting vessel below the tube sheet contains the liquid product.

The product and the heat transfer medium (HTM) both flow as a falling film. The product flows down on the inside surface of the tubes, whereas the liquid used for cooling and heating is distributed to wet the external surface of the tubes. During crystallization, cold HTM is used to chill the tubes. Partial melting, also called sweating, is induced by slightly raising the temperature of the HTM, and the final melting to provide the purified liquid is achieved by applying higher temperatures. The product and HTM distribution systems are designed to equalize flow through the tubes. Optimum performance is achieved through accurate control of the heating and cooling profiles.

Falling film crystallization is often combined with our static crystallization. This set-up improves the yield and recovery of your product.

For some applications, a high purity and separation yield are difficult to achieve using a single separation technology. In this case, we suggest you apply a hybrid process, which is a combination of our various separation technologies, for example crystallization and distillation. In this way, the separation is carried out in the most efficient concentration range of each Sulzer unit operation. This improves the efficiency and flexibility of your plant and saves energy costs.

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