Process design factors

Before considering the specifics of adsorption design factors, it may be useful to generalize the process with some simplified analogies. 

imagine a beaker of water containing an organic pollutant to which a large amount of activated carbon is added. The pollutant will sorb onto, and desorb from, the carbon particles until the rate of sorption equals the rate of desorption and the system is in equilibrium. At equilibrium, the concentration of the pollutant in the water will be at a minimum value. The carbon in equilibrium with this solution will have reached its adsorptive capacity, and cannot adsorb any more pollutant under the current conditions. This batch system is one method to measure the equilibrium loading of the sorbent. 

The mass transfer zone will move down the column with time. When it reaches the bottom of the column, the effluent pollutant concentration will start to rise above the minimum value, and this is known as breakthrough. When the very bottom layers of carbon 

Adsorbent columns can be used until they are exhausted by placing them in series. As one column is exhausted, it is taken off line and the adsorbent is replaced or regenerated. The column can then be placed below the second column, and the process is continued. If only one column were to be used, it would have to be regenerated sometime before exhaustion, depending on the allowable effluent pollutant concentration. Placing columns in parallel is also a possibility, so that breakthrough in one column will not significantly affect the effluent quality. 

We can use two methods to visualize the effect of the mass transfer zone (MTZ) on the adsorption column operation. In one method, we measure the solute concentration in the fluid phase at the column exit (position is fixed, time is a variable). 

---

SAQ 2.5 Select an appropriate combination of process design factors for each of the processes. ... 

Process design factors for iron ore pelletizing machines [8]. Factors are based on effective areas. 

The rate of flow of the nitrogen purge in the hydrogen header is an important process design factor. Considerations include ... 

Cooper D (2009) Behavioral safety interventions. Professional Safety 37. http //www.behav-ioural-safety.com/articles/behavioral safety interventions a review of process design factors.pdf... 

Vehicle Fa.ctors. Because knock is a chemical reaction, it is sensitive to temperature and reaction time. Temperature can in turn be affected either by external factors such as the wall temperature or by the amount of heat released in the combustion process itself, which is directiy related to the density of the fuel—air mixture. A vehicle factor which increases charge density, combustion chamber temperatures, or available reaction time promotes the tendency to knock. Engine operating and design factors which affect the tendency to produce knocking are... 

Hydrothermal Synthesis Systems. Of the unit operations depicted in Figure 1, the pressurized sections from reactor inlet to pressure letdown ate key to hydrothermal process design. In consideration of scale-up of a hydrothermal process for high performance materials, several criteria must be considered. First, the mode of operation, which can be either continuous, semicontinuous, or batch, must be determined. Factors to consider ate the operating conditions, the manufacturing demand, the composition of the product mix (single or multiple products), the amount of waste that can be tolerated, and the materials of constmction requirements. Criteria for the selection of hydrothermal reactor design maybe summarized as... 

Process plant design has come a long way from the early 1930s when process designers used the rule-of-thumb that a process faciUty could not be scaled-up more than 10-fold (2). American Oil s Ultracracking unit (Texas City, Texas) for example, was designed from data from a small pilot plant with a scale-up factor of 80,000 (3). 

The application of the science of human factors to eliminating error in all aspects of process design, management, operation, and maintenance is the focus of this work. Human error has been a major cause of almost all of the catastrophic accidents that have occurred in the chemical process industries (CPI). If one adopts the broad view of human error as being the result of a mismatch between human capabilities and process demands, then clearly management s role is critical in the following areas ... 

While this process implies an ordered, structured process, it should be noted that the various stages overlap and it is frequently necessary to return to an earlier step in the process to modify or clarify information or decisions made in an earlier phase. The influence of the human factors aspects on design needs to be similarly integrated into the process design procedure. The particular human factors elements to be addressed at each phase are discussed below. These phases can be directly related to the human factors engineering and ergonomics (HFE/E) design approach described in Section 2.2. 

In order to illustrate the critical process parameters of SMB process validation, we will consider the separation of the racemic drug as described in Process design. The study represents the effect of the influence of feed concentration, number of plates and retention factor on the second eluting enantiomer. The simulation of the process for different values of feed concentration is performed and the variations of the extract and raffinate purities are shown in Fig. 10.10. 

Edmister, W. C., Hydrocarbon Absorption and Fractionar tion Process Design Methods, Pet. Engr. May 1947-March 1949 and, Absorption and Stripping—Factor Functions for Distillation Calculations by Manual and Digital—Computer Methods. A.I.ChJE. foumal, V. 3, No. 2 p. 165 (1957). 

---