The SUPRAYIELD Process

In the SUPRAYIELD process, the delayed decompression is a degenerated flash process slowed down to such an extent that the period of time for going from a high primary pressure to a lower secondary pressure corresponds to the reaction time needed for the desired conversion of pentosan to furfural. To make this a practical proposition, the primary temperature must be high, say 240 °C, and the secondary temperature should not be below 180 °C as in this range the reaction rate would be too slow. 

As after heating the reactor to the primary temperature the pressure in the vessel is high, the delayed decompression can be readily effected and controlled by a simple leak valve. In special cases, when the primary temperature is limited by the available steam pres- 

Losses can occur only during the short heating period when the reaction medium is not yet boiling. For this reason, the heating to the primary temperature should be an inverse flash , as fast as possible. 

Depending on the primary temperature, the process can be run with or without a foreign acid. The higher the primary temperature, the smaller is the need for a foreign acid. 

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