Silicon Carbide Heat Exchangers
Where other materials are reaching the end of their life, silicon carbide (SiC) is only just get-ting into its stride. This superior material defies high temperatures and pressures, as well as corrosive chemicals. ESK Ceramics GmbH & Co. KG of Kempten offers a complete range of plate heat ex-changers of EKasic® silicon carbide for applications in a variety of industries. Recently, gasket-free models have become available for special customer requirements.
Anyone looking for an “extremist” in the world of materials would be certain to come across silicon carbide (SiC). This glossy green to bluish-black material is a tough cookie. With a Mohs hardness of 9.6, it is almost as hard as diamond and scratches both steel and corun-dum. This feature is the direct result of the strong bond between the silicon and carbon at-oms. But this is by no means the only special feature of this high-performance ceramic. For example, SiC resists aggressive chemicals such as chlorine, strong acids and alkalis, and also has extremely high wear resistance. The material is therefore tailor-made for industrial applications at high temperatures. The high-temperature form (α-SiC) is most commonly em-ployed, and has a proven track record, for example, in the refractories industry, coatings, but also as a grinding and polishing agent and for high-temperature transistors.
Reliable materials are also rated highly by users in chemical process engineering. That ap-plies to the production or processing of corrosive materials, as well as to all kinds of thermal processes, such as cooling, heating, pasteurization, evaporation and condensation. EKasic® silicon carbide’s high chemical resistance has made it a promising candidate for use in, for example, general purpose heat exchangers. As of recently, therefore, ESK Ceramics GmbH & Co. KG of Kempten now offers a complete range of heat exchanger products of EKasic® sili-con carbide. The B260 and B500 series countercurrent plate heat exchangers were designed especially for heat transfer between liquids with a pressure difference of up to 16 bar. Compu-tational fluid dynamics (CFD) simulations were carried out to conceive a common plate design for liquid media to provide outstanding heat transfer rates with minimum pressure loss.
More Robust and Efficient than Stainless Steel
Besides its high wear resistance and robustness towards almost all conceivable corrosive media, EKasic® silicon carbide also has a high thermal conductivity of over 110 W/mK. This value lies well above that of chrome-nickel steel or chrome steel (16 to 25 W/mK). This prop-erty, together with an optimized plate design, obtains extremely high thermal efficiency. Con-sequently, the dimensions and weight of the heat exchangers can be kept very small. As a result, the spectrum of potential applications now covers the high-temperature range up to 850 °C and geothermal functions, liquid/liquid heat exchange of aggressive chemicals and seawater applications, through to cryogenic applications.
These useful properties have benefits in a wide range of different industries, specifically
Because of its high abrasion resistance, EKasic® silicon carbide does not liberate either parti-cles or metal ions even in long-term service. The material is approved for drinking water ap-plications ac-cording to KTW, WRAS and Fresenius, and has also been classified as harm-less for food-contact applications. That also applies to pharmaceutical applications, where, in a pilot application, a facility’s conventional graphite heat exchangers were replaced with EKasic® SiC.
The reason for the substitution was that the end product was being contaminated with tiny graphite particles. Another pilot application focuses on the material’s chemical resistance. In this specific case, plate heat exchangers of EKasic® silicon carbide are used for concentration of caustic soda. The stainless steel heat exchangers formerly used could not resist the alka-line medium in the long term and were virtually completely corroded away after an average of two years.
Minimum-Gasket Designs Offer a Safety Margin
Plate heat exchangers, as critical components of thermal process engineering, are subject to strict demands for safety and a long service life. The Achilles’ heel is the elastomeric gaskets, which are used to seal the individual plate channels and are subject to both wear and aging. To increase the safety and lifetime of the plate heat exchangers, ESK has recently offered a gasket-free model besides its fluoro-elastomer Viton and semi-gasket systems.
The key to this breakthrough was “diffusion welding,” which permits the manufacture of low-stress, and in many cases more homogeneous bonds between different materials. With this welding method, the parts to be joined are heated to welding temperature in a furnace under a controlled atmosphere, and, over several hours, subjected to a pressure that causes diffu-sion of the material at the weld joints. The final product is a plate heat exchanger that is a hermetically tight monolithic block. It therefore offers an unrivalled degree of safety in contact with hazardous substances.
Reliable materials are also rated highly by users in chemical process engineering. That ap-plies to the production or processing of corrosive materials, as well as to all kinds of thermal processes, such as cooling, heating, pasteurization, evaporation and condensation. EKasic® silicon carbide’s high chemical resistance has made it a promising candidate for use in, for example, general purpose heat exchangers. As of recently, therefore, ESK Ceramics GmbH & Co. KG of Kempten now offers a complete range of heat exchanger products of EKasic® sili-con carbide. The B260 and B500 series countercurrent plate heat exchangers were designed especially for heat transfer between liquids with a pressure difference of up to 16 bar. Compu-tational fluid dynamics (CFD) simulations were carried out to conceive a common plate design for liquid media to provide outstanding heat transfer rates with minimum pressure loss.
More Robust and Efficient than Stainless Steel
Besides its high wear resistance and robustness towards almost all conceivable corrosive media, EKasic® silicon carbide also has a high thermal conductivity of over 110 W/mK. This value lies well above that of chrome-nickel steel or chrome steel (16 to 25 W/mK). This prop-erty, together with an optimized plate design, obtains extremely high thermal efficiency. Con-sequently, the dimensions and weight of the heat exchangers can be kept very small. As a result, the spectrum of potential applications now covers the high-temperature range up to 850 °C and geothermal functions, liquid/liquid heat exchange of aggressive chemicals and seawater applications, through to cryogenic applications.
These useful properties have benefits in a wide range of different industries, specifically
- chemicals
- steel
- ore extraction
- paper
- pharmaceuticals
- fertilizer manufacture
- flue-gas purification
- semiconductors, and
- power engineering
Because of its high abrasion resistance, EKasic® silicon carbide does not liberate either parti-cles or metal ions even in long-term service. The material is approved for drinking water ap-plications ac-cording to KTW, WRAS and Fresenius, and has also been classified as harm-less for food-contact applications. That also applies to pharmaceutical applications, where, in a pilot application, a facility’s conventional graphite heat exchangers were replaced with EKasic® SiC.
The reason for the substitution was that the end product was being contaminated with tiny graphite particles. Another pilot application focuses on the material’s chemical resistance. In this specific case, plate heat exchangers of EKasic® silicon carbide are used for concentration of caustic soda. The stainless steel heat exchangers formerly used could not resist the alka-line medium in the long term and were virtually completely corroded away after an average of two years.
Minimum-Gasket Designs Offer a Safety Margin
Plate heat exchangers, as critical components of thermal process engineering, are subject to strict demands for safety and a long service life. The Achilles’ heel is the elastomeric gaskets, which are used to seal the individual plate channels and are subject to both wear and aging. To increase the safety and lifetime of the plate heat exchangers, ESK has recently offered a gasket-free model besides its fluoro-elastomer Viton and semi-gasket systems.
The key to this breakthrough was “diffusion welding,” which permits the manufacture of low-stress, and in many cases more homogeneous bonds between different materials. With this welding method, the parts to be joined are heated to welding temperature in a furnace under a controlled atmosphere, and, over several hours, subjected to a pressure that causes diffu-sion of the material at the weld joints. The final product is a plate heat exchanger that is a hermetically tight monolithic block. It therefore offers an unrivalled degree of safety in contact with hazardous substances.
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