High pressure vessel examples

The above example is obvious, but when the reaction takes place in a much smaller, steel, high-pressure vessel with less familiar reagents, the true rate processes are much more readily hidden from the investigator s imagination. 

Since the beginning of the manufacture of high-pressure vessels in the early 1910 s their weight have increased continuously up to the beginning of the 1970 s. As an example, the development of ammonia-reactors is shown in Table 4.3-4 [29]. 

As decribed in Chapter 4.3.2, it is increasingly common to design and manufacture such apparatus as monobloc reactors. Furthermore with modem testing facilities with, for example, ultrasonic methods it is possible to check the finished apparatus up to wall-thicknesses of 350 mm. These developments are an excellent contribution for the safe operation of high-pressure vessels. 

Another type is the shell- and tube-arrangement. In Fig. 4.3-23 an example with a combined inlet- and outlet chamber is shown, which is designed as a high-pressure vessel. One end of this vessel is the tube plate into which the hair-pin tubes are welded. The lower-pressure side could be connected to a low-pressure heating or cooling system. A further apparatus is the multi-tube hair-pin heat exchanger presented in Fig. 4.3-24. 

The known unknowns are the focus of most hazards analyses. For example, a process may involve the transfer of chemical from a high-pressure vessel to another vessel that operates at lower pressure. The designers of the system may not have considered the possibility that the pressure gradient could reverse, i.e., that the pressure in the first vessel could drop to a value less than that in the second vessel, thus creating the possibility of reverse flow. Such a scenario is a vaUd topic for the hazards analysis team to discuss. This scenario is a known unknown — it may not have been considered, but it is part and parcel of a normal hazards analysis. 

Section 1.5 Data for Examples High Pressure Vessels... 

Type D Extraction is from material which is sufficiently fluid to be pumped and the product is also a fluid. In this case extraction takes place in a high pressure column in which the material to be extracted flows counter-current to the solvent stream. Depending on the product, the separation takes place by release of pressure or by adsorption in standard pressure vessels or by absorption in a high pressure vessel operated as a column (Table 8.1 D). Examples of type D processes include the refining and fractionation of seed oils and the fractionation of milk fat at pilot plant scale. 

Explosions can be caused by nuclear reactions, loss of containment in high pressure vessels, high explosives, runaway reactions, or a combination of dust, mist or gas in air or other oxidisers. This chapter concentrates on the latter examples. 

There are also opportunities for making active and procedural risk management systems inherently safer. For example, consider two alternative designs for a high pressure interlock for a vessel ... 

Although many engineers provide only the minimum adequate vessel design to minimize costs, it is inherently safer to minimize the use of safety interlocks and administrative controls by designing robust equipment. Passive hardware devices can be substituted for active control systems. For example, if the design pressure of the vessel system is higher than the maximum expected pressure, an interlock to trip the system on high pressure or temperatures may be unnecessary. 

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