Adding Unit Operations

There are several ways to add imit operations. For a complete description, see Chapter 3 (Adding Unit Operations). 

Now you can reconsider the material balance equations by adding those additional factors identified in the previous step. If necessary, estimates of unaccountable losses will have to be calculated. Note that, in the case of a relatively simple manufacturing plant, preparation of a preliminary material-balance system and its refinement (Steps 14 and 15) can usefully be combined. For more-complex P2 assessments, however, two separate steps are likely to be more appropriate. An important rule to remember is that the inputs should ideally equal the outputs - but in practice this will rarely be the case. Some judgment will be required to determine what level of accuracy is acceptable, and we should have an idea as to what the unlikely sources of errors are (e.g., evaporative losses from outside holding ponds may be a materials loss we cannot accurately account for). In the case of high concentrations of hazardous wastes, accurate measurements are needed to develop cost-effective waste-reduction options. It is possible that the material balance for a number of unit operations will need to be repeated. Again, continue to review, refine, and, where necessary, expand your database. The compilation of accurate and comprehensive data is essential for a successful P2 audit and subsequent waste-reduction action plan. Remember - you can t reduce what you don t know is therel... 

Increased Plant Capacity - When an existing plant capacity is increased, the entire pressure relieving system should be reevaluated, even though new equipment has been added. For example, a unit operating at 120 % of design capacity may require additional pressure relieving capacity. 

Membrane Ultrafiltration Membrane ultrafiltration is often one of the favored unit operations used for the isolation and concentration of biomolecules because they can be easily scaled up to process large feed volumes at low costs. Toward the end of an ultrafiltration operation, additional water or buffer is added to facilitate the passage of... 

Most of the chapters have been updated to reflect the increased body of knowledge in the respective areas of unit operations. The sections on scale-up of granulation and tableting have been completely revised. New sections have been added, namely, on the scale-up of roller compaction, extrusion, and hard gelatin encapsulation. 

New chapters on several unit operations (such as encapsulation, extrusion and spheronizing, and roller compaction) have been added. 

Volatile Treatment. This method of treatment may be used for units operating above 2000 psi (136 atm) drum pressure. In this method, no Solid chemicals are added lo either the boiler 01 pie-boiler cycle. By eliminating solid treatment, the volatile carry-over of solids is eliminated and consequently turbine deposits are avoided. Cycle pH is controlled at 9.0 to 9.5 with a volatile amine such as ammonia. Hydrazine is added as an oxygen scavenger in quantity sufficient to provide a concentration of 20 to 30 ppb at the economizer inlet. 

The second set-up concept from Microinnova, the Lab Experiment Toolbox , has some minor differences from the first concept. It was designed to speed up process development and reduce the time to market of chemicals or compounding products (Figure 4.25) [77]. A modular toolbox has been developed for laboratory-scale experiments. Small tube connections are used to connect various unit operation devices to each other. Process control and user interface are based on Fieldpoint and LabView or Microinnova Process Control. The integration of the sensors into the system is different to the previous concept. The Fieldpoint unit has a front panel, where sensors can be added on a plug-and-play basis. All experimental data are stored in spreadsheets, which can be transferred to common spreadsheet... 

The conceptual development of a typical chemical process remains somewhat of an art. Usually, experience with similar process plants leads to an initial process flowsheet. Parameter optimization on that flowsheet can be used to determine the best economic design. Other flowsheets can be generated by adding/removing unit operations and process streams and changing the structure of the process flowsheet. A simplified depiction of this synthesis process is shown in Fig. 5. 

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