Loop reactor, improved design

Batch time lowered by a factor of 2 catalyst loading reduced by factor of 2 Solventless system increases productivity as compared to conventional stirred tank reactor. Reaction time reduced by 80% yield increased from 83 to 94% Appropriate design of venturi loop reactor reduces chlorination batch time by a factor of 5-7 from 20 to 40 h required in a conventional stirred tank reactor. Highly efficient heat transfer in the external loop affords nearly isothermal operation at 45-50 °C, resulting in a high yield (more than 90%) of 2,4-dichloro phenol while suppressing formation of 2,6 dichloro phenol. Efficient removal of reaction by-product (hydrogen chloride) in the external gas circuit (Fig. 8.3) improves the yield Almost complete conversion of methanol in less than 1 h... 

The temperature of the catalyst is not controlled in the investigated FCC unit yet, so a control loop should be designed to improve the operation of the actual control structure. In the first step, the analysis of degrees of freedom is carried out and a possible manipulated variable is found the coke formation in the reactor can be controll by the feed flow of the bottom product of the main distillation column (BMC) which contains heavy hydrocarbons. (This main distillation column separates the products of the FCC unit.) This flow is free for this control and it is selected as manipulated variable. 

An improved loop reactor design with cone-shaped zones that transition the loop to a wider diameter section was recently patented by Basell Polyolefine GmbH [29]. This design is illustrated in Figure 5.15. 

Most fast-spectrum reactors operated around the world use liquid sodium metal as a coolant. Future fast-spectrum reactors may use lead or a lead-bismuth alloy, or even helium, as a coolant. One of the attractive properties of metals as coolants is that they offer exceptional heat-transfer properties in addition, some (but not all) metal coolants are much less corrosive than water. However, because sodium is reactive with air and water, fast-spectrum reactors built to date have a secondary sodium system to isolate the sodium coolant in the reactor from the water in the electricity-producing steam system. The need for a secondary system has raised capital costs for fast reactors and has limited thermal efficiencies to the range of 32 to 38 percent. Novel steam-generator designs, direct gas cycles, and different coolants are options that may eliminate the need for this secondary sodium loop and improve the economics of fast reactors (Lake et al 2002). 

ALWRs are expected to be deployed ia the United States and ia Asian counties. However, France will use improved versions of standard reactors, considering them to be amply safe and economical. The reactors were modified after the Three-Mile Island-2 (TMI-2) accident. The company Framatome that has built most of the reactors of France is associated with Babcock Wilcox ia the United States. The new Framatome 1500 MWe N4 PWR is an extension of the successful four-loop units of 1300 MWe originally designed by Westiaghouse. Full emphasis is givea to safety, ecoaomy, and rehabiUty. More severe design criteria than those ia the former model have beea adopted. 

Internal-loop airlift reactors (ALRs) are widely used for their self-induced circulation, improved mixing, and excellent heat transfer [1], This work reports on the design of an ALR with a novel gas-liquid separator and novel gas distributor. In this ALR, the gas was sparged into the annulus. The special designed gas-liquid separator, at the head of the reactor, can almost completely separate the gas and liquid even at high gas velocities. 

With the unique reactor and smart particle designs, the oxygen carrying capacity and recyclability of the iron-based chemical looping particles have been radically improved, and OSU s SGR process has shown a great potential for commercialization. Its pilot-scale demonstration is currently under way. In addition, the sulfur present in coal is expected to react with Fe and form FeS. Flence, the SGR process has the capability of removing... 

The loss of expensive catalyst from the reactor system can be fatal for any process. Physical loss involves the removal of active catalyst from the closed loop of the process. This can include the plating out of metal or oxides on the internal surfaces of the manufacturing plant, failure to recover potentially active catalyst from purge streams and the decomposition of active catalyst by the process of product recovery. The first two can be alleviated to some extent by improvements in catalyst or process design, the last is an intrinsic problem for all manufacturing operations and is the subject of this book. 

Small bubbles and flow uniformity are important for gas-liquid and gas-liquid-solid multiphase reactors. A reactor internal was designed and installed in an external-loop airlift reactor (EL-ALR) to enhance bubble breakup and flow redistribution and improve reactor performance. Hydrodynamic parameters, including local gas holdup, bubble rise velocity, bubble Sauter diameter and liquid velocity were measured. A radial maldistribution index was introduced to describe radial non-uniformity in the hydrodynamic parameters. The influence of the internal on this index was studied. Experimental results show that The effect of the internal is to make the radial profiles of the gas holdup, bubble rise velocity and liquid velocity radially uniform. The bubble Sauter diameter decreases and the bubble size distribution is narrower. With increasing distance away from the internal, the radial profiles change back to be similar to those before contact with it. The internal improves the flow behavior up to a distance of 1.4 m. 

The reactor design must account for heat removal as well as chemical reaction. For monoliths, the unique situation exists that because of the low-pressure drop, external heat removal in a liquid loop is feasible 38,39). Alternatively, structured packings can be applied that improve radial transport 124,126). 

A single, isothermal reactor design more reliably yields gypsum crystals than multiple-reactor designs with poorer temperature control [39]. This benefit has also been claimed for a two-vessel loop system. The effect of surfactants on crystallization of phosphogypsum has been examined [40]. Higher reactor circulation rates and increased agitation coupled with other refinements also improve acid recovery [41]. 

The most suitable driving force in BI is the reduction of the diffusion path that already operates in transport processes across biological bilayers. Consequently, biocatalyst membranes and specially designed bioreactors, such as jet loop and membrane reactors, are available to intensify biochemical reactions. " " Supported biocatalysts are often employed to enhance catalytic activity and stability and to protect enzymes/ microorganisms from mechanical degradation and deactivation.f Immobilization of the cells is one of the techniques employed to improve the productivity of bioreactors. 

LOCA (secondary) frequency for severe vessel leaks and ruptures - primary loop largely integrated in reactor pool limits LOCA effects on core and fuel - wet motor RCPs eliminates small LOCAs due to shaft seal failure - not important - simplifieations and improved materials reduce initiator frequency - increased design margins reduee initiator frequency ... 

The Rolls-Royce prefabricated nuclear plant is a 300 MW power station mounted on two barges. The nuclear Island is contained on one barge and the conventional plant on the other. Essentially the nuclear Island consists of a compact 4-loop PWR using standard components and designed to meet UK safety criteria with appropriate equipment redundancy and diversity (Fig. 1). The reactor has been designed to take full advantage of PWR safety Improvements since the Three Mile Island incident in 1979. Basic data are given in Table 1. 

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