Case study No. 8:
Production of solar cells

Initial situation

One production step in the production of solar cells is the etching of the silicon wafers in wet banks with highly concentrated mixed acid, consisting of nitric and hydrofluoric acid.

The reaction between mixed acid and silicon is highly exothermic, so that the acid heats up.

With the temperature, the reaction speed also increases and gets out of control. The mixed acid must be cooled. However, metals, glass or other common materials for heat exchangers are not resistant to this mixed acid.

Task

We were looking for an effective, metal-free and reliable heat exchanger for cooling. It had to be chemically resistant to a highly concentrated mixture of fluridic and nitric acid and used for installation in wet banks.

Solution

This is where our shell and tube heat exchanger comes into play.

The mixed acid is driven in circulation by a PVDF solid plastic heat exchanger and kept at temperature with cooling water.

Result

Wet benches with PVDF shell and tube heat exchangers have been used since 2006.

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