Comparison of liquid discharge from a tank through circular and irregular shape orifices
Systematic methods and tools for managing the complexity
Tools Integration - CAPE Methods & Tools (T4-10P)
Keywords: outflow, orifice, Newtonian, non-Newtonian
A dynamic development of industry in the 20th century contributed to a significant growth of the number and variety of chemical processes. The chemical processes have often been accompanied by the risk of accidents due to which substances might be released to the environment in an uncontrolled way. Hence, because of up-to-date industrial safety and risk problems, accidental discharge of liquids from damaged elements of process equipment has become very important.
The discharge of liquids from a closed tank has been discussed in literature insufficiently. Besides, the discussion refers to Newtonian liquids only. Accidental release of liquid from a pressure tank through orifices of irregular shapes has not studied so far.
Discharge of Newtonian and non-Newtonian liquids through circular and irregular shape orifices from a tank at various pressures is discussed in this study. The orifices of different geometries represented real orifices formed during an accidental discharge. Diameters of the circular orifices through which the liquid was discharged were 5, 8, 12.5 and 17 mm, while equivalent diameters of irregular openings were 5, 8 and 12.5 mm. The experimental Newtonian liquids were water and triethylene glycol and non-Newtonian ones were water solutions of carboxy¬methylcellulose at the concentrations 1.6, 2 and 2.5% wt.
As a result, a broad range of experimental data on a “bottleneck” discharge of liquid from a tank and liquid outflow at sub-atmospheric and overpressure was obtained. Depending on the initial conditions in the tank, the experimentally obtained ratio of the tank diameter to discharge orifice diameter Dv/d ranged from 11.8 to 40.5. For each investigated liquid and orifice geometry the values of flooding constant C were determined and presented graphically in the form of the relation C = f(Dv/d).
A comparative analysis of the experimental data was carried out. It was found that the values of flooding constant for the “bottleneck” discharge of all liquids were lower than constant C for the discharge at sub-atmospheric and overpressure in the whole range of geometries of the applied orifices. The authors found also that flooding constants assumed the highest values in the case of liquid discharge at overpressure.
Presented Thursday 20, 13:30 to 14:40, in session Tools Integration - CAPE Methods & Tools (T4-10P).
