Process reactor parallelization

A second strategy relies on parallel experimentation. In this case, the same experimental step is performed over n samples in n separated vessels at the same time. Robotic equipment such as automated liquid-handlers, multi-well reactors and auto-samplers for the analysis are used to perform the repetitive tasks in parallel. This automated equipment often works in a serial fashion as, for example, a liquid handler with a single dispensing syringe filling the wells of a microtiter plate, one after another. However, the chemical formation of the catalyst or the catalytic reaction are run at the same time, assuming that their rate is slow compared to the time needed to add all the components. The whole process appears parallel for the human user whose intervention is reduced. 

The kinetics of the toluene oxidation over Bi2Mo06 and a commercial Bi—Mo—P—O ammoxidation catalyst were investigated by Van der Wiele and Van den Berg [348]. A flow reactor was used at 450—550°C, 1—3 atm and varying feed rate, toluene and oxygen partial pressures. Benzaldehyde formation and combustion reactions are the main process the parallel-consecutive scheme which applies is... 

Description The Hostalen process is a slurry polymerization method with two reactors parallel or in series. Switching from a single reaction to a reaction in cascade enables producing top quality unimodal and bimodal polyethylene (PE) from narrow to broad molecular weight distribution (MWD) with the same catalyst. 

The performance of the PPR for NOx removal by the Shell low-temperature NOx reduction has been investigated extensively [20]. In the first commercial application of the Shell process with parallel-passage reactors, flue gases of six ethylene cracker furnaces at Rheinische Olefin Werke at Wesseling, Germany, are treated in a PPR system with 120-m catalyst in total to reduce the nitrogen oxide emissions to about 40 ppm v. Since its successful start-up in April 1990, the unit has performed according to expectations... 

Figure 10. Evolution with time of the effective rate profile of the main reaction in a plug flow reactor. Parallel coking. Diffusion-limited process on a ZSM-5 type catalyst.

Fig. 4 Photographs of p-DAAD production steps, (a) Front side of a 4" silicon wafer populated with etched microreactors 16 p-DAAD are processed in parallel, each consisting of four microreactors. (b) Front-side view of a single p-DAAD (16 x 1 mm ) after bonding a cover plate and dicing. DNA arrays are printed onto the bottom of the microreactor cavities, but carmot be seen in this image because of their small size. Holes of 1 mm in diameter are drilled in the cover glass for the filling of the p-DAAD reactors with reagent, (c) Back-side view of the device with platinum heater coil and thermoresistors placed at the corresponding area of the microreactor. Reproduced from [79] with permission...

In droplet-based microfluidics, these reaction vessels are formed by droplets of a dispersed phase, which are embedded into a continuous phase. Both liquid phases are immiscible. A huge amount of such droplet reactors can be generated, transported, controlled, and processed in parallel in a droplet-based lab-on-a-chip device. These devices can be characterized as application specific microfiuidic networks that implement and automate a conventional laboratory workflow in a microfluidic chip device or system. They are built up by appropriately intercoimecting microfluidic operation units, which provide the required laboratory operations at the microscale. Consequently, for each conventional laboratory operation, its microscale counterpart is required. 

As an example of the decontamination of subsystems, the treatment of a BWR recirculation loop and, in addition, parts of the residual heat removal system and the reactor water cleanup system, by using the Cord process in parallel to the... 

The design approach for Pearl GTL is that essentially limited scale-up risks have been taken at equipment level. As a result the Air Separation Units (ASU s), The Shell Gasification Process reactors (SGP s) and Heavy Paraffin Synthesis reactors (HPS s) are all built in a modular fashion, i.e. with multiple parallel imits. 

The electrochemical in situ hydrogen generation route is an alternative route that eliminates the need for an external hydrogen source for HDS. The process involves parallel reactors for batch operation. For continuous operation, parallel reactors can also be employed. In both cases, the residence time of the reactor is governed by the deployment of optimal surface area of the electrocatalysts in relation to reactor configuration. A simplified PFD of such a process for batch operation is shown in Fig. 2. 

The characteristic of this process is that several processes are parallel or cross-carried out i.e., the reduction process for the each catalyst particle proceeds from surface to core step-by-step and the reduction process of whole catalyst in reactor (bed) proceeds from the top (outside) down (internal) step by step, and also reaction process of H2 with N2 forms ammonia on reduced catalysts. Therefore, temperature (t) of catalyst bed, the reduction degree (i ) of catalyst and water vapor concentration (y>) are changing. Trends of different types of reactors at different reduction stages are shown in Fig. 5.26. 

Construct the preliminary models of the real process (two parallel reactor series) ... 

Most reactors have evolved from concentrated efforts focused on one type of reactor. Some processes have emerged from parallel developments using markedly different reactor types. In most cases, the reactor selected for laboratory study has become the reactor type used industrially because further development usually favors extending this technology. Descriptions of some industrially important petrochemical processes and their reactors are available (74—76). Following are illustrative examples of reactor usage, classified according to reactor type. 

Plasmas can be used in CVD reactors to activate and partially decompose the precursor species and perhaps form new chemical species. This allows deposition at a temperature lower than thermal CVD. The process is called plasma-enhanced CVD (PECVD) (12). The plasmas are generated by direct-current, radio-frequency (r-f), or electron-cyclotron-resonance (ECR) techniques. Eigure 15 shows a parallel-plate CVD reactor that uses r-f power to generate the plasma. This type of PECVD reactor is in common use in the semiconductor industry to deposit siUcon nitride, Si N and glass (PSG) encapsulating layers a few micrometers-thick at deposition rates of 5—100 nm /min. 

Dehydrogenation of /i-Butane. Dehydrogenation of / -butane [106-97-8] via the Houdry process is carried out under partial vacuum, 35—75 kPa (5—11 psi), at about 535—650°C with a fixed-bed catalyst. The catalyst consists of aluminum oxide and chromium oxide as the principal components. The reaction is endothermic and the cycle life of the catalyst is about 10 minutes because of coke buildup. Several parallel reactors are needed in the plant to allow for continuous operation with catalyst regeneration. Thermodynamics limits the conversion to about 30—40% and the ultimate yield is 60—65 wt % (233). 

For the same production capacity, the oxygen-based process requires fewer reactors, all of which operate in parallel and are exposed to reaction gas of the same composition. However, the use of purge reactors in series for an air-based process in conjunction with the associated energy recovery system increases the overall complexity of the unit. Given the same degree of automation, the operation of an oxygen-based unit is simpler and easier if the air-separation plant is outside the battery limits of the ethylene oxide process (97). 

A semi-batch reactor has the same disadvantages as the batch reactor. However, it has the advantages of good temperature control and the capability of minimizing unwanted side reactions by maintaining a low concentration of one of the reactants. Semi-batch reactors are also of value when parallel reactions of different orders occur, where it may be more profitable to use semi-batch rather than batch operations. In many applications semi-batch reactors involve a substantial increase in the volume of reaction mixture during a processing cycle (i.e., emulsion polymerization). 

The ratio of the ionic liquid to the organic phase present in the reactor also plays an important role. A too high level of ionic liquid results in much longer decantation time and causes lower dimer selectivity. To combine efficient decantation and a reasonable size for the settler in the process design, it has been proposed that the separation of the two phases be performed in two distinct settling zones arranged in parallel [38]. 

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