Desolventizer toaster with convective current recycle
A desolventizer for processing solvent-wet solid material may include a thermal recirculation loop to increase thermal performance. In some examples, the desolventizer includes a housing, an ejector, and a vent. The housing contains a first tray and a second tray vertically elevated above the first tray to define a processing space. The ejector has an inlet located between the first tray and the second tray and an outlet also located between the first tray and the second tray. The vent has an inlet located between the first tray and the second tray. In operation, the ejector can draw gas from the processing space via the inlet and discharge the gas through the outlet back into the processing space, creating a recirculation loop.
1. A method comprising:
introducing a solvent-containing material into a housing containing a plurality of trays vertically spaced from one another to define a plurality of processing zones;
heating the solvent-containing material in at least some of the plurality of processing zones through application of at least one indirect or direct heating and thereby vaporizing solvent from the solvent-containing material;
drawing gas from an annular space formed between a baffle and an inner wall of the housing within a select one of the plurality of processing zones, and reinjecting the gas via application of a motive gas to an ejector into a second space positioned on an opposite side of the baffle in the select one of the plurality of processing zones.
2. The method of claim 1 , wherein introducing the solvent-containing material into the housing comprises forming a bed of the solvent-containing material on a tray within the select one of the plurality of processing zones deeper than a distance separating a bottom edge of the baffle from the tray, thereby requiring gas traveling from the second space to the annular space within the processing zone to pass through the bed of material.
3. The method of claim 1 , wherein drawing gas from the annular space and reinjecting the gas into the second space comprises drawing gas from an inlet and reinjecting the gas through an outlet, the outlet being vertically elevated above the inlet.
4. The method of claim 1 , further comprising venting gas from the select one of the plurality of processing zones via a vent line.
5. The method of claim 4 , wherein venting gas comprises venting gas though a first vent opening in the annular space and a second vent opening in the second space.
6. The method of claim 5 , wherein the first vent opening and the second vent opening are each radially offset from an outlet through which gas is reinjected into the second space.
7. The method of claim 1 , wherein the motive gas is steam, and a tray within the select one of the plurality of processing zones is indirectly heated but not directly heated such that sparge steam is not injected through the tray.
8. The method of claim 1 , wherein the solvent-containing material comprises a material selected from the group consisting of a soy material, a palm material, a corn material, a rapeseed material, and combinations thereof, and a solvent wetting the material is an organic solvent.
9. The method of claim 1 , further comprising:
drawing gas from an second annular space formed between a second baffle and a second inner wall of the housing within a second select one of the plurality of processing zones, and reinjecting the gas via application of a motive gas to a second ejector into another second space positioned on an opposite side of the second baffle in the second select one of the plurality of processing zones.