Supercritical high-pressure nozzle extraction

Delivery of Extract Delivery Nozzle. Delivery of the extraction effluent is conducted via the six port static/dynamic valve while in the dynamic mode. Generally, extractions are conducted at a high density in the static mode. Once the extraction is complete, the valve is re-positioned into a dynamic evacuation, pressure or density is reduced rapidly to prevent significant losses of the supercritical fluid and the extraction effluent is transferred for collection. The extract leaves through the heated static/dynamic valve to the heated lines then to the delivery nozzle(s). Figure 8 shows a diagram of the delivery nozzle and its components. 

The relative importance of the nucleation and growth phases in the formation of crystals from supercritical fluids has received attention. Mohamed et al. [96] recently studied the size distribution of naphthlene crystals from a supercritical mixture. The supercritical solution was first completed by contact of carbon dioxide with solid naphthalene at a high pressure in an extraction cell, then expanded through a nozzle in a crystalliser. Apparently both the pre-... 

SEDS (solution-enhanced dispersion by supercritical fluids) The second modification of the gas antisolvent process known as solution-enhanced dispersion by SCFs was developed by the Bradford Universityt in order to achieve smaller droplet size and intense mixing of SCF and solution for increased transfer rates. Indeed the SCF is used both for its chemical properties and as spray enhancer by mechanical effect a nozzle with two coaxial passages allows the introduction of the SCF and a solution of active substance(s) into the particle-formation vessel where pressure and temperature are controlled (Figure 8.5). The high velocity of the SCF allows breaking up the solution into very small droplets. Moreover, the conditions are set up so that the SCF can extract the solvent from the solution at the same time as it meets and disperses the solution. Similarly, a variant was recently disclosed by the University of Kansas, where the nozzle design leads to development of sonic waves leading to very tiny particles, around 1 /rm. 

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