High vessel design, recommendations

In designing faciUties for handling and processing nitromethane, it is recommended that nitromethane not be processed in high pressure equipment. AH vessels for nitromethane service should be protected to prevent adiabatic compression. Detonation traps should be installed at each end of transfer lines and in every 61 m (200 feet) of continuous line. Nitromethane lines should be located underground or in channels wherever possible. Pressure rehef devices (rated - 690 kPa = 100 psig) should be installed between closed valves (81). 

Note that the recommended value for p is not always conservative. In some cases, heat input may be so high that the safety valve cannot vent all the generated vapor. In such cases, the internal pressure will rise until the bursting overpressure is reached, which may be much higher than the vessel s design pressure. For example, Droste and Schoen (1988) describe an experiment in which an LPG tank failed at 39 bar, or 2.5 times the opening pressure of its safety valve. Note also that this method assumes that the fluid is in thermodynamic equilibrium yet, in practice, stratification of liquid and vapor will occur (Moodie et al. 1988). 

The tank dimensions are determined according to standard tank geometries as used by the Denver Company (United States). Tank shell thickness is sized according to the limitations imposed by the Australian design standard for pressure vessels (AS1 210 Ref. T1). The tank contents are non-flammable but highly toxic and corrosive, appropriate safety features are recommended. Details of the calculations are given in Appendix J. 

This design provides high velocity and turbulence within the jacket. This in turn will result in an unusually high film coefficient. The half pipe coil is recommended for high temperature and all liquid applications. It is better than conventional jackets because the pressure drop can be carefully controlled and calculated. It is not however practical for small vessels, less than 500 gallons. Because there are no limitations to the number of inlet and outlet connections, this type of jacketing can be divided into multiple zones for maximum flexibility and efficiency. 

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