Delumping

C. Extension of Kinetics to Predict Process and Product Characteristics Delumping... 

While the 13 hydrocarbon lumps accurately represent the hydrocarbon conversion kinetics, they must be delumped for the deactivation kinetics. In addition, delumping is necessary to estimate many of the product properties and process conditions important to an effective reformer process model. These include H2 consumption, recycle gas H2 purity, and key reformate properties such as octane number and vapor pressure. The following three lump types had to be delumped the C5- kinetic lump into Cl to C5 light gas components, the paraffin kinetic lumps into isoparaffin and n-paraffin components, and the Cg+ kinetic lumps into Cg, C9, C10, and Cn components by molecular type. 

As an example of delumping, the kinetically predicted C5- lump is delumped by means of distribution correlations C5- is distributed into Ct, C2, C3, iso-C4, n-C4, iso-C5, and n-C5, as indicated in Table VIII. The... 

The paraffin isomer and Cg+ kinetic lumps are delumped in a more rigorous fashion than the C5-. Semikinetic delumping equations have been developed for both the Cg+ lumps and paraffin distribution (Table VIII). The paraffin distribution is constrained by known equilibrium. 

Low-shear delumping (Quadro Comil) Continuous process... 

Equipment size and capacity The mill should be large enough to delump the entire batch within a reasonable time period to minimize manufacturing time and prevent the material from drying during this operation. 

Screen size The screen needs to be small enough to delump the material, but not too small to cause excessive heating of the mill, resulting in drying of the granulation. 

Mill speed The speed should be sufficient to efficiently delump the material without straining the equipment. 

In the case of low-dose formulations, it is important that the feed system convey material without allowing the material to segregate. All of the feed system arrangements shown in Fig. 6.1 rely on gravity feed for the powder to reach the force feeding screws. Feed systems i, ii, and iii can be outfitted with an agitator in the intermediate hopper which will aid in powder flow and delumping. 

Delumpers and hammer mills are frequently used to reduce the particle size of products, thereby creating a manageable physical form for ongoing processing, usually improving rates of dissolution or an even distribution of a product when blended in a mixture. 

The submitters used reagent grade tetrahydrofuran (EM Science) dried over 4 A or 5 A molecular sieves (Aldrich Chemical Company, Inc.), and determined the water content in the solvents by Karl Fisher titration (KF). The submitters report that the tetrahydrofuran should be dry (KF < 50 pg/mL) and MUST NOT contain any DMF (< 1 ppm). Also, the KF of the tetrahydrofuran/proline suspension should be < 50 pg/mL. The submitters used (S)-proline obtained from Ajinomoto while the checkers used (S)-proline from Aldrich Chemical Company, Inc. The proline should be milled and/or delumped prior to use, if necessary, to insure complete reaction. The enantiomeric purity of the (S)-proline should be > 99.5%, and can be assayed via the procedure of Marfey.2 The checkers used HPLC grade THF (Fisher Scientific Company) that was dried over 4 A molecular sieves. 

In the pilot plant, intermittent delumping of the partially dried cake was needed to reach the desired dryness. A change in crystal morphology was noted during the filtration and drying stages. 

The crystals are filtered, washed, dried, and delumped, and the bulk product is dry-filled into single-dose vials. 

The uniform shape and size achieved by this process are required for these downstream steps to be successfully completed. Key issues are filtration rate, low retention of solvent by the wet filter cake (< 10%), drying at <25 C, and flowability of the delumped crystals. 

Even though, as presented above, certain characteristic relationships have been developed for many agglomeration methods, scale-up is a serious problem. Furthermore, aging has very often a marked effect on the results, because binding mechanisms rely on chemical and physical interactions at the surfaces of particles to be agglomerated and, if applicable, with the binder component(s). Therefore, a representative material which is several days or weeks old and may have to be reheated, re wetted, dried, or delumped to bring it back to a comparable condition as found in the real plant environment may yield completely different results than those found later in-line. This means that not only tests must be carried out with representative samples of raw materials and, if applicable, binders but pilot plant evaluations on site and/or in-line should also be considered if the risk of a new application is to be minimized. 

In order to enhance the drying rates in the rotary dryer without raising the gas temperature or gas flowrate excessively, it is possible to introduce steam heated mbes or coils within the shell. Aside from providing additional energy for drying, such internals can also help with redistribution or delumping of the material. Of course, it is possible to use internal heaters only if the material does not stick to the walls of the internals. 

In conclusion, even if a representative sample is provided, a material which is several days, weeks, or months old and may have had to be reheated, dried, rewetted, delumped, mixed, fluffed, etc. to bring it back to conditions that are corresponding to or comparable with those found or expected in the real plant environment may yield completely different results than obtained later in-line . Although, as described in the previous chapters of this book, as reviewed in other publications (see Section... 

Taskmaster Shredder, Plastics and solid waste shredder, Franklin Miller Inc., Delumper Mixer Div. 

---