Pressure vessels Separators

Pressure Vessels. High pressure tanks are vessels operating above 15 psig. These are reaHy pressure vessels and the term high pressure tank is basicaHy never used. Pressure vessels are a speciali2ed form of container treated separately from tanks by aH codes, standards, and regulations. 

The PEBC at the Tidd Station operates at 1200 kPa (170 psi) and a bed temperature of 860°C (51). A pressure vessel, 13.4 m in diameter by 20.7 m high, houses the combustor and its ancikafies. Coals, which contain ash contents less than about 25%, are blended with dolomite and pumped to the combustor as a paste having a total water content of 20—25%. Coals, which contain ash contents higher than 25%, and dolomite are individually fed pneumatically via separate lock hoppers. Both coal and dolomite are cmshed to 3-mm top size before being fed to the unit. 

As the coiled plate spirals outward, the plate thickness increases from a minimum of 2 mm to a maximum (as required by pressure) up to 10 mm. This means relatively thick material separates the two fluids compared to tubing of conventional exchangers. Pressure vessel code conformance is a common request. 

Pressure storage tanks should be coirelated using /lb vs. w eight, much the same as other pressure vessels. Materials of construction, of course, would be another variable. Special internals, insulation, and internal heat exchangers should again be separated from the base cost of the tank. The w eight of supports, ladders, and platforms should be estimated and added to the weight of the... 

In many cases, if it is not feasible to contain a runaway reaction within the reactor, it may be possible to pipe the emergency device effluent to a separate pressure vessel for containment and subsequent treatment. 

The pressure vessel is 79 ft high with an upper diameter of 23 ft and lower diameter of 20 ft. This height is key to establishing natural circulation core flow by providing a chimney in the space between the top of the core and the steam separator assembly. This large top diameter increases the water inventory above the core (no accumulators needed), and the smaller lower diameter reduces the volume of water needed to be replaced to provide core cooling. 

Most reactions in solution have rather small AV" values (usually Av" is less than 20 cm /mol), so only small perturbations are possible. The pressure change is created by rupturing a diaphragm separating the reaction solution from a pressure vessel. A typical pressure change is about 60 atm. 

Pressure vessels and tanks may be used for reactions, storage of raw materials, conlaimnenl of chemical inlennediales or products, and pliase separations. Tlie... 

Bridgestone Corporation has announced in its news release in Febmary 2006 the development of a multi-air chamber tire, which has three separate chambers acting as pressure vessels. ... 

Whereas the liquid-solid filtration processes described so far can separate particles down to a size of around 10 xm, for smaller particles that need to be separated, a porous polymer membrane can be used. This process, known as microfiltration, retains particles down to a size of around 0.05. im. A pressure difference across the membrane of 0.5 to 4 bar is used. The two most common practical arrangements are spiral wound and hollow fiber. In the spiral wound arrangement, flat membrane sheets separated by spacers for the flow of feed and filtrate are wound into a spiral and inserted in a pressure vessel. Hollow... 

Example 13.3 Water is to be pumped between two vessels separated by an estimated distance of 30 m under the action of flow control. An increase in elevation of 5 m is also estimated. The flowrate of water is 100 m3 per hour, its viscosity is 0.8 mN-s-nr2 (equal to centipoise) and its density is 993 kg-nr3. Estimate the pressure drop required to be produced by the pump. 

The issue of parallel versus sequential synthesis using multimode or monomode cavities, respectively, deserves special comment. While the parallel set-up allows for a considerably higher throughput achievable in the relatively short timeframe of a microwave-enhanced chemical reaction, the individual control over each reaction vessel in terms of reaction temperature/pressure is limited. In the parallel mode, all reaction vessels are exposed to the same irradiation conditions. In order to ensure similar temperatures in each vessel, the same volume of the identical solvent should be used in each reaction vessel because of the dielectric properties involved [86]. As an alternative to parallel processing, the automated sequential synthesis of libraries can be a viable strategy if small focused libraries (20-200 compounds) need to be prepared. Irradiating each individual reaction vessel separately gives better control over the reaction parameters and allows for the rapid optimization of reaction conditions. For the preparation of relatively small libraries, where delicate chemistries are to be performed, the sequential format may be preferable. This is discussed in more detail in Chapter 5. 

---