Feed reactor-design

Solution The reversible nature of the reaction means that neither of the feed materials can be forced to complete conversion. The reactor design in Fig. 

Fig. 24. Elements of a bubbleless turbulent fluid-bed reactor design where the internals create four stages. A represents the shrouded grid B, the first feed ...

The kinetic study was made in two parts. First, a feed-forward design was executed based on variations in feed conditions. A larger study was made by feed-back design, where conditions were specified at the discharge of the reactor. Details of the two designs can be seen on the tables in Figures 6.3.2 and 6.3.3. 

The flowsheets shown in Figure 1.4 feature the same reactor design. It could be useful to explore the changes in reactor design. For example, the size of the reactor could be increased to increase the amount of FEED that reacts5. 

Solution The reversible nature of the reaction means that neither of the feed materials can be forced to complete conversion. The reactor design in Figure 14.21a shows that the reactor product contains a mixture of both feed and product materials together with the n-butane impurity. These must be separated, but how ... 

In principle one can treat the thermodynamics of chemical reactions on a kinetic basis by recognizing that the equilibrium condition corresponds to the case where the rates of the forward and reverse reactions are identical. In this sense kinetics is the more fundamental science. Nonetheless, thermodynamics provides much vital information to the kineticist and to the reactor designer. In particular, the first step in determining the economic feasibility of producing a given material from a given reactant feed stock should be the determination of the product yield at equilibrium at the conditions of the reactor outlet. Since this composition represents the goal toward which the kinetic... 

Your assignment is to use the data and assumptions listed below to prepare a preliminary reactor design in which particular emphasis is placed on the variation of the maximum yield of phthalic anhydride with feed temperature. 

Understanding catalysis has been emphasized here, but the possible practical effects of deliberate cycling of a reactor feed to improve yield must also be kept in mind. Also, undesired feed oscillations must be taken into account in the design of a reactor. Design for such a situation is not possible based on steady state laboratory data alone. 

The choice of appropriate reaction conditions is crucial for optimized performance in alkylation. The most important parameters are the reaction temperature, the feed alkane/alkene ratio, the alkene space velocity, the alkene feed composition, and the reactor design. Changing these parameters will induce similar effects for any alkylation catalyst, but the sensitivity to changes varies from catalyst to catalyst. Table II is a summary of the most important parameters employed in industrial operations for different acids. The values given for zeolites represent best estimates of data available from laboratory and pilot-scale experiments. 

An economic benefit can occur through the retrofitting of a catalytic reactor, designed to perform partial destruction of the hypochlorite, into a plant already equipped with a chemical treatment system. The savings in chemicals consumption can more than offset the capital investment associated with the catalytic reactor and purchase of the initial catalyst charge. At high feed concentrations, say above a few weight per cent, the payback time can in fact be less than six months. 

There are several aspects of thermal sensitivity and instability which are important to consider in relation to reactor design. When an exothermic catalytic reaction occurs in a non-isothermal reactor, for example, a small change in coolant temperature may, under certain circumstances, produce undesirable hotspots or regions of high temperature within the reactor. Similarly, it is of central importance to determine whether or not there is likely to be any set of operating conditions which may cause thermal instability in the sense that the reaction may either become extinguished or continue at a higher temperature level as a result of fluctuations in the feed condition. We will briefly examine these problems. 

Reactor design is a key element in each process listed in Table XX. The method of feed introduction, the arrangement of the catalyst bed, and the mode of operation have an impact on the ability to process residua. For this reason, classification by reactor type provides a convenient and appropriate distinction for discussing hydroprocessing technology. The most common reactor designs include fixed beds, ebullated or expanded beds and slurry beds, and moving-bed reactors. These classifications are discussed in more detail next. 

The swing-reactor design reserves two of the hydrodemetallization reactor design reserves for use as guard reactors one of them can be removed from service for catalyst reconditioning and put on standby while the rest of the unit continues to operate. More that 50% of the metals are removed from the feed in the guard reactors. 

The typical reactor design situation is to be given the feed conditions (flowrate, temperature, and composition), the kinetic information, and the desired conversion. The problem is to determine the temperature and the size of the reactor. 

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