Split vessel design

Split jacket designs are available for virtually all vessels, and the additional cost may be offset by the savings realized in preventing decomposition at the upper wall. In addition, by limiting exposure at the critical liquid-vapor interface, the temperature of the heating fluid... 

For large vapor flow, it may be cheaper to use split flow design to reduce the required vapor flow area. Feed will enter the vessel at its midpoint and vapor exits from both ends of the vessel, or feed is split to half and enters the vessel from each end, and vapor exits fix>m vessel s midpoint. 

In these systems, the total collection efficiencies of the dry product are 85 per cent for the drying vessel, 90 per cent for the cyclone collector and 98 per cent for the scrubber-condenser. The net efficiency of the system may be as high as 99.97 per cent if the scrubber effluent is considered as product. All the runs are based on 1.25 kg/s product and 0.75 kg/s evaporation at an elevation of 300 m above sea level. The total air flow is measured at the outlet before the stream is split into the recycle and bleed portions and, for such flows, the design of suitable fans is outlined by Jorgensen164 . The calculations outlined here may be confirmed by the use of psychometric charts, and this procedure has been considered in some detail by Cook and Demount165. ... 

The split-and-pool synthesis not only simplifies the complexity of the combinatorial synthetic process, but also offers additional important benefits. To undertake a full range of solid-phase chemical reactions, elaborate reaction conditions are needed for some chemical transformations. These include, but are not limited to, low temperature and inert atmosphere conditions. Parallel synthesis of a thousand compounds requires handling of a thousand reaction vessels. The timely addition of sensitive reagents (e.g., butyl lithium) at low temperature (—78°) under inert atmosphere during parallel synthesis is not a trivial task. It can be done if sophisticated automated synthesizer equipment is designed to handle and tolerate such reaction conditions. Such a synthesis can alternatively be performed easily in a manual fashion using a split-and-pool method that requires only a limited number of reaction vessels. Examples from Nicolaou s17 and Schrei-ber s18,19 laboratories have shown that the split-and-pool method is the methodology of choice for the synthesis of complex and diversity-oriented combinatorial libraries. 

To illustrate some of the design and control issues, a vessel size (DR = 2 m, VR = 12.57 m3, jacket heat transfer area Aj = 25.13 m2) and a maximum reactor temperature (7j) ax = 340 K) are selected. The vessel is initially heated with a hot fluid until the reaction begins to generate heat. Then a cold fluid is used. A split-range-heating/ cooling system is used that adds hot or cold water to a circulating-water system, which is assumed to be perfectly mixed at temperature Tj. The setpoint of a reactor temperature controller is ramped up from 300 K to the maximum temperature over some time period. 

The impellers used in this study are shown in Figure 1. They are both of the radially discharging type which is characterized by a strong radial jet of fluid that moves out to the vessel walls while entraining fluid from above and below. Near the wall it splits into two circulation zones. The flat blade turbine (FBT) is commonly used in industry and consists of a disc with several paddles fixed normal to the disc which serve to generate the radial flow. The novel impeller design... 

Closures between heads and cylinders, often taking the form of clamps, split rings, or bolts, are also an important consideration in the proper design of the pressure vessel, for it is these components that must hold the vessel head to the cylinder. It is important to recognize the force that is exerted on the closure. For example, in a 1000 psi vessel, a circular head with a diameter of 12 in. will have over 110,0001b of force pushing on it. This force must be evenly divided between bolts or spread out over the clamp or split ring closure. 

Flat gasket seals must be preloaded with a force equivalent to the force that will be exerted by the pressure within the vessel. A flanged bolt closure or split ring bolt closure design can be used to achieve this preload. Closure bolts should be evenly tightened to a specified torque that will provide the proper closing force. 

Perhaps the most important and most readily achievable equipment design to minimize wall decomposition is the use of jacket services on the bottom section of the vessel only. Such services can be provided either by a lower jacket only or, more commonly, by a split jacket to provide for full services in multipurpose vessels. Decomposition can be especially severe on the wall above the boiling surface, where any liquid may evaporate and leave the residual compound to dry and be exposed to the maximum temperature in the jacket (baking). 

A number of different solid supports and uniquely designed reaction vessels are adopted for the parallel synthesis of organic compound libraries. The yields of the individual compounds synthesized vary widely from nanomoles to millimoles. Unlike split-pool synthesis, which requires a solid support, parallel synthesis can be done either on solid phase or in solution. 

The feedwater lines enter the containment via two lines, each with inner and outer isolation valves, splitting up into four lines adjacent to the RPV for connection to four nozzles, at "mid-height" of the vessel. The nozzles and the internal removable feedwater distributers are of a special ABB Atom design that ensures a "thermal sleeve" protection against the "cold" feedwater for the RPV wall, and efficient distribution into the downcomer. The feedwater flow rate is adjusted to match the steam flow rate from the vessel, to keep the water level within close limits, by speed control of the feedwater pumps at high power operation, but valve arrangements enable flow rate control also at low reactor power levels in these situations the feedwater flow is routed via smaller nozzles that can easier withstand thermal transients. 

A tap cooler mounted into a hot distribution loop requires a special design. The loop and the storage vessel must be kept at high temperature while no long branches filled with stationary (colder) water can be accepted. Therefore the loop splits near the cold tap into two parallel pipes both continuously being flushed with the hot pharmaceutical water. In one of the two branches a heat exchanger is mounted. 

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