Flow sheet continuous

Flow Sheet. Most purge-swing appHcations use two fixed-bed adsorbers to provide a continuous flow of feed and product (Fig. 16). Single beds are used when the flow to be treated is intermittent or cycHc. Because the purge flow is invariably greater than that of adsorption, purge is carried out in the down-flow direction to prevent bed lifting, and adsorption is up-flow. 

Hydroxjiamine is used as a substitute for the ferrous sulfamate (26). These systems are called salt-free flow sheets. The main purpose is to ease the problems associated with the processing and storage of the Hquid waste streams (27). Another approach is to use an electropulse column to electrolyticaHy produce to reduce Pu to Pu on a continuous basis (28,29). The half reactions for the flow sheets are... 

It is likely that there will always be a distinction between the way CAD/CAM is used in mechanical design and the way it is used in the chemical process industry. Most of the computations requited in mechanical design involve systems of linear or lineatizable equations, usually describing forces and positions. The calculations requited to model molecular motion or to describe the sequence of unit operations in a process flow sheet are often highly nonlinear and involve systems of mixed forms of equations. Since the natures of the computational problems are quite different, it is most likely that graphic techniques will continue to be used more to display results than to create them. 

Level 1 Batch versus continuous Level 2 Input—output stmcture of the flow sheet Level 3 Recycle stmcture of the flow sheet Level 4 Separation system specification... 

Chloroprene mbber is usually manufactured by either batch or continuous emulsion polymerization and isolated either by freeze coagulation or dmm drying of a polymer film. Figure 1 is a schematic flow sheet of this process. 

From the process flow sheet developed in the above exercise, identify a) those unit operations involving simple mass flows only b) those unit operations in which phase changes are occurring c) those operations in which there are chemical reactions taking place d) those operations that are batch e) those operations that are continuous. 

Figure 28. Continuous flotation system flow sheet. (Courtesy of Beekart Environmental, Ine., Kenosha, WI, email info beekart.eom)...

Figure 1. Flow-sheet of experimental procedure for continuous pectin degradation,...

At the end of 24 hours of continuous process the system was shut down. The knowledge of flowed buffer volumes and of the optical densities inside and downstream each ultrafiltration stage allowed to estimate product distribution (see appendix for mass-balance equations and the calculation procedure). The content of each cell was recovered and ffeeze-dried in order to be stored and used for subsequent kinetic experiments. A schematic flow-sheet of the whole procedure is illustrated in figure 1. 

There is an additional point to be made about this type of processing. Many gas-phase processes are carried out in a continuous-flow manner on the macro scale, as industrial or laboratory-scale processes. Hence already the conventional processes resemble the flow sheets of micro-reactor processing, i.e. there is similarity between macro and micro processing. This is a fimdamental difference from most liquid-phase reactions that are performed typically batch-wise, e.g. using stirred glass vessels in the laboratory or stirred steel tanks in industrial pilot or production plants. 

Flow-sheets drawn up for batch processes normally show the quantities required to produce one batch. If a batch process forms part of an otherwise continuous process, it can be shown on the same flow-sheet, providing a clear break is made when tabulating the data between the continuous and batch sections the change from kg/h to kg/batch. A continuous process may include batch make-up of minor reagents, such as the catalyst for a polymerisation process. 

When sub-dividing the process and approximating equipment performance to produce a flow-sheet, the designer must appreciate that the resulting design for the complete process, as defined by the flow-sheet, will be an approximation to the optimum design. He must continually be aware of, and check, the effect of his approximations on the performance of the complete process. 

Figure 5.8 A schematic flow sheet of the continuous process...

Lob P, Hessel V, Krtschil U, Lowe H (2006a) Continuous micro-reactor rigs with capillary sections in organic synthesis—generic process flow sheets, practical experience, and novel chemistry . Chimica Oggi Chem Today 24 46-50... 

HAZOP studies may be made on batch as well as continuous processes. For a continuous process, the working document is usually a set of flow sheets or piping and instrument diagrams (P IDs). Batch processes have another dimension time. Time is usually not significant with a continuous process that is operating smoothly, although start-up and shutdown must also be considered, when the continuous process will resemble a batch process. For batch processes, the working documents consist not only of the flow sheets or P IDs but also... 

The engineering analysis and design of these operations addresses questions which are different than those addressed in connection with the shaping operations. This is illustrated in Fig. 1 which is a flow sheet, cited by Nichols and Kheradi (1982), for the continuous conversion of latex in the manufacture of acrylonitrile-butadiene-styrene (ABS). In this process three of the nonshaping operations are shown (1) a chemical reaction (coagulation) (2) a liquid-liquid extraction operation which involves a molten polymer and water and (3) a vapor-liquid stripping operation which involves the removal of a volatile component from the molten polymer. The analysis and design around the devolatilization section, for example, would deal with such questions as how the exit concentration of... 

Fig. 1. Process flow sheet for the continuous conversion of latex in a counterrotating, tangential twin-screw extruder as it might be arranged for the production of acrylonitrile-butadiene-styrene polymer (Nichols and Kheradi, 1982). Polystyrene (or styrene-acrylonitrile) melt is fed upstream of the reactor zone where the coagulation reaction takes place. Washing (countercurrent liquid-liquid extraction) and solids separation are conducted in zones immediately downstream of the reactor zone. The remainii zones are reserved for devolatilization and pumping.

As in any process development work, the data have to be examined critically to make certain that there is sufficient reason to carry the project on to the next phase. Thus, if a particular system has poor stripping characteristics, it is very doubtful whether any improvement can be made by going to a larger scale, in which case the investigation may have to be terminated. However, if the bench data have produced sufficient information to draw a conceptual flow sheet, then a decision can be made on whether to run a small-scale continuous operation or a pilot plant. Many other factors have to be considered in making this decision, such as the economics of the process, cost of... 

The data obtained from small-scale continuous operations will be required to determine whether the process should be investigated on a larger scale, such as a pilot plant. These data should be sufficient to draw a conceptual flow sheet, which will include a number of stages for extraction, scrubbing [10], and stripping the flow rates, size and type of equipment, and the various parameters considered earlier in this chapter. Another important aspect should also be considered in the continuous test work, and that is chemical analysis of both the aqueous and organic phases for their various components. 

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