DIMAX DTDC
The hexane loaded meal coming from the extractor, needs to be desolventized, toasted, dried and cooled before it goes to the finished meal storage.
Desmet has developed the proprietary Dimax DTDC design for this purpose. The modular design of the different tray types, allows to optimize and adapt the design to the specific needs of the client, in function of the feedstocks that will be processed in the plant.
In general, the apparatus will contain one or more pre-desolventizing trays with indirect heating, a number of desolventizing trays with direct steam injection, a number of drying trays and a number of cooling trays. The modular design of the different tray types, allows to optimize and adapt the design of the DTDC to the specific needs of the client, in function of the feedstocks that will be processed in the plant, the plant capacity and the final desired meal quality.
The apparatus can be designed with the DT and DC integrated in one apparatus, but in some cases, especially for large capacity plants, the DT and DC can be two separate vessels.
The Dimax technology, first introduced in 2001, has been further optimized based on the many references all over the world, especially for soybean and rapeseed meal, and delivers excellent meal quality with low anti-nutritional factors and low residual hexane content.
How does it work
The extracted meal coming from the solvent extractor is transported with a solvent tight conveyor from the outlet hopper. The meal then, first enters the pre-desolventizing trays to evaporate part of the free hexane by indirect heating with steam.
The meal then enters the desolventizing trays. These trays have the typical Dimax open design with round slotted screens that allow the passage of the steam and solvent from one tray to another. In these trays the meal is further desolventized but also toasted by a combination of direct steam injection and indirect steam heating. The residence time is this desolventizing section is crucial for the final meal quality and is adapted in function of the feedstock to treat. Rapeseed meal needs in general a quite longer residence time compared to soya meal. The layer height and residence time in the desolventizing trays is controlled by rotary valves with level control.
The hexane-steam vapours leaving the DT dome at the top, are first washed and cleaned in an external water scrubber, before they will pass to the economizer in the distillation section
From the desolventizing trays, the meal falls into the drying trays. In these trays the meal is dried with steam heated air to the desired humidity level. Finally, the meal is cooled in the cooling trays to a temperature acceptable for storage and further transport.
Key advantages
Dimax trays
High steam density for efficient stripping and toasting
Rotary valves on DT trays
Consistent retention time in DT section
Energy efficient
Low power consumption
High meal quality
Low residual hexane and minimal anti-nutritional factors
Hygienic drying–cooling design
Prevents bacterial contamination