Solid loading retention Time

For estimating purposes for direct-heat drying applications, it can be assumed that the average exit-gas temperature leaving the sohds bed wih approach the final solids discharge temperature on an ordi-naiy unit carrying a 5- to 15-cm-deep bed. Calculation of the heat load and selec tion of an inlet-air temperature and superficial velocity (Table 12-32) will then permit approximate sizing, provided an approximation of the minimum required retention time can be made. 

Settling ponds, a less sophisticated alternative to mechanical clarifiers, also remove suspended solids by sedimentation. Settling ponds may be clay-lined, synthetic-lined, or unlined and earthen, and have longer retention times than clarifiers. Settling ponds produce less constant solids loadings than mechanical clarifiers, but still provide sufficient solids removal prior to... 

DEC and the internal standard (Istd), 1-diethylcar-bamyl-4-ethyl piperazine HC1 (E-DEC), were extracted from human plasma - that has been alkalised with carbonate buffer - after loading onto a conditioned Cl8 solid phase extraction cartridge, rinsed with water and eluted with methanol. After evaporation under a stream of nitrogen and reconstitution in methanol, 3 il. were injected into the GC system and detected using a flame ionization detector (FID). The retention time for DEC was 5.5 min and for the internal standard (E-DEC) it was 7.28 min. 

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