Pressure vessels types

An overview of design criteria and the resulting pressure vessel types will be given for the high pressure range from 250 to 10,000 bars. 

The following two pressure vessel types have been built for erection in France, hence the French pressure vessel code CODAP [3] has been followed. 

It is a boiling water pressure tube (channel) reactor, cooled by light water and moderated by graphite. (In pressure tube (channel) reactors the nuclear fuel, made from low enriched uranium oxide, is contained in a set of parallel and closely spaced tubes or channels.) On passing, it has to be said that water reactors are numerous in the world, although the majority of these reactors are of the pressure vessel type, where all the nuclear fuel is contained in a strong vessel and not in a set of parallel pressure channels. 

HWRs of the pressure vessel type have been designed and constructed in Sweden, Germany, and Argentina. The main references of this line are the Agesta reactor in Sweden (shutdown), the MZFR reactor in Germany, and the Atucha-1 and Atucha-2 reactors in Argentina. 

The PHWR 300 of KWU is a pressurized heavy water reactor of the pressure vessel type with the following main characteristics ... 

Some applications are closed shapes or have a local reduction, like some pressure vessel types or rocket motor cases. If the products have no liner the core must be dissolvable. For dissolvable materials the following are usable sand (soluble, water soluble),plaster (soluble,breakout), salt (meltable, eutectic) and alloy (with a low melting temperature). All dissolvable cores are precast in an extra process step before the winding process starts. After the winding process the core is nearly complete covered with filaments. Depending on the dissolvable material used, different techniques to dissolve the core are required such as rinsing with water or heating up to a certain temperature. All dissolvable cores are non-heated. 

The PBWFR concept [XXVII-1] is an evolution of the concept of a direct contact Pb-Bi fast breeder reactor (PBWR) proposed in [XXVII-2]. It is a pressure vessel type reactor, in which sub-cooled water is fed into the hot Pb-Bi coolant above the core, resulting in a direct contact boiling, as shown in Fig. XXVII-1. Boiling bubbles rise due to buoyancy effect, which also works as a lift pump for Pb-Bi circulation. The generated steam passes through the separator and the dryer to remove Pb-Bi droplets, and then flows to the turbine-generator plant. The outlet steam is superheated by 10°C to avoid the accumulation of condensate on a free Pb-Bi surface in the reactor vessel. 

Under an association contract our company is co-operating with the Jililloh Nuclear Research Centre In the development of DgO cooled and moderated thorium converters. The aim of this study is a project for a 600 MW unit of the pressure vessel type and comprises a detailed R D orogramme. 

A preconceptual plant design with 1700 M W net electric power based on a pressure vessel-type reactor has been studied by Yamada et al. (2011) and has been assessed with respect to efficiency, safety, and cost. The study confirms the target net efficiency of 44% and estimates a cost reduction potential of 30% compared with current pressurized water reactors. Safety features are expected to be similar to advanced boiling water reactors. 

The pressure-vessel type of SCWR may use UO2 in a once-through fuel cycle, with an enrichment of 5—7%, or mixed oxide (MOX) fuel if plutonium should be recycled in a closed fuel cycle. In the case of a thermal neutron spectrum, the use of MOX fuel is optional as in a conventional PWR or BWR. However, because the higher... 

Safety system in a pressure vessel-type supercritical water-cooled reactor concept... 

Y. Ishiwatari, Y. Oka and K. Yamada, Japanese R D lYojects on Pressure-Vessel Type SCWR, Proc. 4th Int. Symp. on SCWR, Heidelberg, Germany, March 8-11,2009, Paper No. 73 (2009)... 

In Europe, R D on the SCWR has been performed as the high performance light water reactor (HPLWR) projects. The HPLWR is the designation of the pressure vessel type, thermal spectrum SCWR. 

Certain types of equipment are specifically excluded from the scope of the directive. It is self-evident that equipment which is already regulated at Union level with respect to the pressure risk by other directives had to be excluded. That is the case with simple pressure vessels, transportable pressure equipment, aerosols and motor vehicles. Other equipment, such as carbonated drink containers or radiators and piping for hot water systems are excluded from the scope because of the limited risk involved. Also excluded are products which are subject to a minor pressure risk which are covered by the directives on machinery, lifts, low voltage, medical devices, gas appliances and on explosive atmospheres. A further and last group of exclusions refers to equipment which presents a significant pressure risk, but for which neither the free circulation aspect nor the safety aspect necessitated their inclusion. 

Chlorine is stored and transported as a Hquefied gas in cylinders of 45.4-kg or 68-kg capacity that are under pressure and equipped with fusible-plug rehef devices. Quantities in the range of 15 to 90 t are transported in tank cars having special angle valves on the manhole cover on top of the vessel. Tank barges of the open-hopper type having several cylindrical uninsulated pressure vessels are used for amounts ranging from 600 to 1200 t. Road tankers are used for capacities of 15 to 20 t. 

A plate-type filter, the PDF filter (18), uses a paddle wheel with radial, longitudinal plates coveted with filter cloth and manifolded to the filter valve at one end of the vessel, instead of a dmm. This filter uses a horizontal pressure vessel, was built to have only 0.75 or 1.5 m area, and operates at 25 kPa. A central screw conveyor collects the cake blown off the plates and conveys it to the discharge end of the vessel. 

The axial filter (Oak Ridge National Laboratory) (30) is remarkably similar to the dynamic filter in that both the rotating filter element and the outer shell are also cylindrical. An ultrafiltration module based on the same principle has also been described (31). Unlike the disk-type European dynamic filters described above, the cylindrical element models are not so suitable for scale-up because they utilize the space inside the pressure vessel poorly. 

One aspect of pressure vessel design which has received considerable attention in recent years is the design of threaded closures where, due to the high stress concentration at the root of the first active thread, a fatigue crack may quickly initiate and propagate in the radial—circumferential plane. Stress intensity factors for this type of crack are difficult to compute (112,113), and more geometries need to be examined before the factors can be used with confidence. 

HoUow-fiber membranes, therefore, may be divided into two categories (/) open hoUow fibers (Eigs. 2a and 2b) where a gas or Hquid permeates across the fiber waU, while flow of the lumen medium gas or Hquid is not restricted, and (2) loaded fibers (Eig. 2c) where the lumen is flUed with an immobilized soHd, Hquid, or gas. The open hoUow fiber has two basic geometries the first is a loop of fiber or a closed bundle contained ia a pressurized vessel. Gas or Hquid passes through the smaU diameter fiber waU and exits via the open fiber ends. In the second type, fibers are open at both ends. The feed fluid can be circulated on the inside or outside of the relatively large diameter fibers. These so-caUed large capiUary (spaghetti) fibers are used in microfUtration, ultrafUtration (qv), pervaporation, and some low pressure (<1035 kPa = 10 atm) gas appHcations. 

There are many different equipment options avaQable to suit specific product needs including continuous winders for pipe, multiaxis winders for pressure vessels, and simple lathe-type winders for tanks and large pipe. Specialty machines combine a chopped reinforcement with continuous fibers for tank walls and large-diameter pipe where both stiffness and tensQe strength are required. Textile braiders have also been adapted for use as continuous... 

There are problems to be considered and avoided when using Hquid-in-glass thermometers. One type of these is pressure errors. The change in height of the mercury column is a function of the volume of the bulb compared to the volume of the capillary. An external pressure (positive or negative) which tends to alter the bulb volume causes an error of indication, which may be small for normal barometric pressure variations but large when, for example, using the thermometer in an autoclave or pressure vessel. 

Lever and Shaft Mechanisms In pressurized vessels, float-actuated lever and shaft mechanisms are frequently used for level measurement. This type of mechanism consists of a hollow metal float and lever attached to a rotaiy shaft, which transmits the float motion to the outside of the vessel through a rotary seal. 

Code Administration The American Society of Mechanical Engineers has written the ASME Boiler and Pressure Vessel Code, which contains rirles for the design, fabrication, and inspection of boilers and pressure vessels. The ASME Code is an American National Standard. Most states in the United States and all Canadian provinces have passed legislation which makes the ASME Code or certain parts of it their legal requirement. Orrly a few jurisdictions have adopted the code for all vessels. The others apply it to certain types of vessels or to boilers. States employ inspectors (usually under a chief boiler inspector) to enforce code provisions. The authorities also depend a great deal on insurance company inspectors to see that boilers and pressure vessels are maintained in a safe condition. 

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