Alternative 2 Reactor

A further parameter search increasing the pitch between the fuel pins and placing extra yttrium hydride in the matrix was done. The effect of pitch on k-effective is shown in 

Some downsides to this design are inherent in the decision to go with a thermal system. Several of the launch accident scenarios provide an unacceptable risk of the core going supercritical. Any scenario where water or additional moderator enters the core is likely to result in a supercritical configuration. This largely was the result of the need to decrease the thickness of the rhenium layer in the fuel to allow for a critical thermal system, and thus is probably unavoidable. 

---

This section covers the Reactor that uses 49% enriched 49 kg fuel. The Alternative 1 reactor uses smaller radius fuel pins enriched to 49% and was the simpler of the two cores to achieve a supercritical configuration with. The active length of the older source core was retained, the cross sectional flow are increased, and the overall core radius decreased. Cross sectional screenshots of the design are shown in Figure 5-7 through Figure 5-9. 

Figure 2.7 Two alternative reactor designs for methanol production give quite different thermal profiles.

More recent process research aimed at anionic PS is that of BASF AG. Unlike the Dow Process, the BASF process utilizes continuous linear-flow reactors (LFR) with no back-mixing to make narrow polydispersity resins. This process consists of a series alternating reactors and heat exchangers (Fig. 22). Inside the reactors, the polymerization exotherm carries the temperature from 30°C at the inlet to 90°C at the outlet. The heat exchangers then take the temperature back down to 30°C. This process, which requires no solvent, results in the formation of narrow polydispersity PS. 

SASOL has pursued the development of alternative reactors to overcome specific operational difficulties encountered with the fixed-bed and entrained-bed reactors. After several years of attempts to overcome the high catalyst circulation rates and consequent abrasion in the Synthol reactors, a bubbling fluidized-bed reactor 1 m (3.3 ft) in diameter was constructed in 1983. Following successflil testing, SASOL designed and construc ted a full-scale commercial reac tor 5 m (16.4 ft) in diameter. The reactor was successfully commissioned in 1989 and remains in operation. 

The first reaction is exothermic, and the second is endothermic. Overall, the reaction evolves considerable heat. Figure 7.1 shows two alternative reactor designs2. Figure 7.1a shows a shell-and-tube type of device that generates steam on the shell side. The temperature profile shows a peak shortly after the reactor inlet because of a... 

ILLUSTRATION 8.10 USE OF THE DESIGN CHARTS FOR COMPARISON OF ALTERNATIVE REACTOR NETWORKS... 

Alternative reactor types are possible for the VHTR. China s HTR-10 [35] and South Africa s pebble bed modular reactor (PBMR) [41] adopted major elements of pebble bed reactor design including fuel element from the past German experience. The fuel cycles might be thorium- or plutonium-based or potentially use mixed oxide (MOX) fuel. 

These relationships are displayed in Fig. 6.9 for two alternative reactor arrangements, both giving the same final conversion X2. Note, as the intermediate... 

Remark 5 Note also that reactors of various distribution functions can be treated with this approach, on the grounds that different distribution functions are usually approximated via cascades of CSTRs. In this case, we can treat the number of CSTRs as a variable or provide a variety of alternative reactors each featuring different numbers of CSTRs. Kokossis and Floudas (1990), present examples for batch, semibatch reactors and different distribution functions. 

To show the uniqueness of the optimum design, a comparison was made with an alternate reactor of identical volume but shorter length and larger diameter. Results are shown in Table V. The alternate reactor does not meet both the residence time and tubeskin temperature specifications. 

Using dimensions of the alternate reactor as initial estimates, the system again converges to the unique optimum design in five iterations. 

Recycling of water is imperative. Because water treatment implies substantial expense, it must be considered as a negative term in the economic potential. If the cost is excessive then alternative reactors should be considered. 

The fast fluidized bed reactor can offer several considerable advantages over alternative reactors for many catalytic and non-catalytic reactions, especially for very fast exothermic/endothermic reactions. With the mushrooming of high activity catalysts and the ever increasing pressure for energy conservation, environmental controls, etc., FFB can play more and more important roles in these areas. More potential commercial applications of FFB in the near future include hydrocarbon oxidations, ammoxidation, gasoline and olefines production by concurrent downflow FFB and basic operation for organic chemical productions. 

Orsenigo et al. [47] have proposed an alternative reactor design suitable in principle to exploit NH3 inhibition for minimizing SO3 formation in the SCR process. This is based on the idea of splitting the NOx-containing feed stream in substreams fed separately to the SCR reactor in this way, a portion of the catalyst volume can operate with an excess of ammonia, while the overall NH3/NO feed ratio is still substoichiometric. 

It should also be observed that the catalytic cell reactor (described in Section II.D), which is intended to be an alternative reactor to trickle beds for liquid-phase hydrogenations, is a further-developed electrochemical filter-press cell based on the firm Electro Cell AB s concept with respect to the preparation of thin, porous electrodes. 

---