Traditional reactors

A modification of the direct process has recentiy been reported usiag a ckculating reactor of the Buss Loop design (11). In addition to employing lower temperatures, this process is claimed to have lower steam and electricity utihty requirements than a more traditional reactor (12) for the direct carbonylation, although cooling water requirements are higher. The reaction can also be performed ia the presence of an amidine catalyst (13). Related processes have been reported that utilize a mixture of methylamines as the feed, but require transition-metal catalysts (14). 

GL 12] [R 5] [P 9] [P 10] [P 11] Significantly lower temperature can be used to achieve a yield of the perfluorinated product as high as when employing the conventionally used cobalt trifluoride process with traditional reactors [15]. 

The reaction system involved in the case studied is a kind of relatively complex van de vusse reaction, nevertheless the reaction system in real manufacturing process may involve more reaction types and, therefore, is more complex than that one. One can, however, simulate the change of environmental indexes within a reactor by combining traditional reactor mathematical model with the PEI balance, and may also discover the effects of reaction conditions and engineering factors on environmental performance by PEI rate-law expression and/or combinations it with other reaction rate equations as well as other related equations in reactor mathematical models. 

Membrane reactors (MRs) are an interesting alternative to traditional reactors (TRs) owing to their characteristic of product separation during the reaction progress. The simultaneous separation shows some advantages related to the process of both permeate and retentate downstreams and on the reaction (rate) itself. In fact, the load of the downstream separation is significantly lower because both (permeate and retentate) streams leaving the MR are concentrated in more and fewer permeable species, respectively. In addition, separation/purification is not required in the special case of pure permeate. 

The discontinuous stirred tank reactor represents one of the most traditional reactor configurations for enzymatic reactions. It consists of a stirred tank where the enzyme, substrates, and cofactors are added at the beginning of the operation with no inlet and/or outlet stream during the reaction time. This type of reactor is usually considered to present an ideal hydrodynamic behavior therefore, the reactor is supposed to be completely mixed and the concentration of all... 

Description DCC is a fluidized process to selectively crack a wide variety of feedstocks into light olefins. Propylene yields over 24 wt% are achievable with paraffinic feeds. A traditional reactor/regenerator unit design uses a catalyst with physical properties similar to traditional FCC catalyst. The DCC unit may be operated in two operational modes maximum propylene (Type I) or maximum iso-olefins (Type II). Each operational mode utilizes unique catalyst as well as reaction conditions. DCC maximum propylene uses both riser and bed cracking at severe reactor conditions, while Type II utilizes only riser cracking like a modern FCC unit at milder conditions. 

Description DCC is a fluidized process to selectively crack a wide variety of feedstocks into light olefins. Propylene yields over 24 wt% are achievable with paraffinic feeds. A traditional reactor/regenerator unit design uses a catalyst with physical properties similar to tra-... 

When combining the membrane and the reactor into an integrated system, cost savings may be significant. This difference can be attributed to the convection and other transport modes in the separation steps by membranes in contrast to the traditional diffusion mode by other separation techniques. For example, the use of membrane reactors instead of the traditional reactors for bioengineered products can reduce the operating costs by as much as 25% [Chan and Brownstein, 1991]. 

The heterogenization of catalysts in membrane is particularly suitable for catalyst design at the atomic and molecular level. One of the main advantages of the membrane reactors, compared to traditional reactors, is the possibility to recycle easily the catalyst. Moreover, the selective transport properties of the membranes can be used to shift the equilibrium conversion (e.g., esterihcation reaction), to remove selectively products and by-products from the reaction mixture, to supply selectively the reagents (e.g., oxygen for partial oxidation reactions). 

Traditionally reactor engineers analyze the mixing of fluids in terms of the degree of segregation (Levenspiel, 1972), a measure of mixing on the molecular scale. 

It would be extremely difficult to predict by calculation what sequence of joystick movements would be needed to produce a desired X-T trajectory, and in feet impossible unless all the details of the reaction were known ahead of time. However, a human operator could quickly develop considerable intuitive expertise through repeated trial-and-error experience with a simulator or with a real reactor. This would raise the role of the technician in charge from the traditional reactor operator to a reaction phase plane pilot whose skill in covering the desired area of the reaction phase plane would be a great asset to expediting experimental work. 

When a reaction is carried out in traditional reactors (for example, fixed bed reactors), the main factors influencing the economics are the feed and process pressures (compressors), feed composition, flow rates, operating temperatures, product pressure, product purity and yield, flexibility, and capabiUty for future expansion (see Table 9.1). 

Factors involved in the economics of membrane reactors include those related to traditional reactors as well as parameters typical of the membrane device. First, the membrane type plays an important role. In particular, its permeability and selectivity affect, respectively, the capacity of the process and the product purity and, therefore, the membrane area needed for reaching a specific target. 

Tab. 9.1 Main factors influencing the economics of traditional reactors.

The effect of feed composition on CO conversion has been studied by CriscuoU et al. in a defect-free tubular Pd-based membrane reactor with a low-temperature shift catalyst packed inside the lumen [23]. The three mixtures tested are summarized in Table 9.3. These authors found that for all feeds it was possible to overcome equilibrium conditions, and that the highest conversion was obtained when the composition of the mixtures was closer to that thermodynamically more favorable (complete conversion was achieved for Mix 1). In the same work, the authors performed system modelling and found that, with respect to traditional reactors. 

The results of a 2 year field weathering test in Europe have confirmed that a UF resin to which has been added 15% melamine acetate salt at the glue mix stage, to obtain a melamine urea mass ratio of 10 90 solids on solids, imparts a better durability and better exterior performance to plywood glue lines than traditionally reactor-coreacted MUF resins of melamine urea mass ratio of 33 66 and even of commercial, prereacted PMUF resin where the relative mass proportions of the materials in the resin are 10 30 60 [23]. 

At the next centuiy in the course of NP development based on the evolutionary improvement of traditional reactors the situation would be deteriorated because in order to keep up the value of severe accident risk at the today s existing socially acceptable level, die probability of that accident should be reduced inversely proportional to the number of reactor-years generated by the NPP units. It would inevitably yield to increasing the capital costs for increasing the NPP safety. 

Criscuoli et al. compared Pd membrane reactor with mesoporous membrane reactor and fixed-bed reactor [5]. Figure 6.5 shows the effect of space velocity on the CO conversion for the three reaction systems. As expected both membrane reactors exhibit better CO conversion than traditional reactor. Between the two membrane reactors Pd membrane reactor exhibits much better CO conversion compared to mesoporous membrane reactor. At the highest time factor, Pd membrane reactor exhibits 100% CO conversion. By increasing the Pd membrane thickness, the hydrogen permeation rate decreases and lower conversions of carbon monoxide are achieved. When they compared experimental results with simulation results the model fits well with the experimental points. 

The presence of H2 did not have any influence on CO conversion. The measured CO conversion of 90% was three to four times higher than that of a traditional reactor. The improvement of CO conversion and hydrogen recover is more effective at higher feed pressure and GHSV. They recovered 80% of the H2 stream in the permeate side. 

Brunetti et al. also foimd that with Fe-Cr catalysts and at temperatures more than 400 °C and feed pressures 15 bar the membrane reactor only require 9% of the catalyst volume of the traditional reactor [11b]. 

WGS measurements a disc membrane was prepared instead of tubular membrane [46]. The WGS reaction experiments were performed with feed side pressures varying from 2 to 6 atm. The permeate side was swept by a N2 flow at atmospheric pressure, and the WHSV was fixed at 7500 h and steam to CO ratio fixed at 3.5. The results are presented in Figure 6.22. The CO conversion of the membrane reactor is much higher than that of the traditional reactor... 

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