Book - School of Science and Technology

Liquid fuel 301Table 11.4 Properties of fuel oilsGrade of oilDescriptionC2KeroseneDGas oilELightFMediumGHeavySpecific mass (re water) 0.789 0.834 0.929 0.949 0.969Flash point (closed) ( C) 38 55 66 66 66Viscosity at 38 CRedwood No 1 28 34 250 1000 3500kinematic (cSt) 1 to 2 4 62 247 864Pour point ( C) ± 18 7 21 21Calorific value (MJ/kg)gross 46.4 45.5 43.4 42.9 42.5net 43.6 42.7 41.0 40.5 40.0Impurities (% mass)sulphur 0.2 0.75 3.2 3.5 3.5ash ± 0.01 0.05 0.12 0.2Temperature ( C)storage (minimum) Atmospheric 10 25 35handling (minimum) Atmospheric 10 30 45upon the amount of low boiling-point material which may be incorporated in the oil, itis not very significant from the point of view of combustion.Viscosity. This quantity, which is comprehensible when given as a Redwood number (secondstaken for a given quantity to flow through an orifice of given size), is important in so far asit affects the ability of oil to flow in delivery and from storage. It is usually determined via a`U'-tube viscometer. Values for kinematic viscosity are given in centistokes.Pour point. This generally follows viscosity and is the temperature at which the oil ceasesto run freely. For practical purposes, this must be below that of the normal temperatureof a storage vessel.Sulphur content. Very significant as far as the potential for corrosion is concerned and isalso a determinant of statutory requirements for chimney height.Ash. Although present in small quantities, this has little significance.DeliveryExcept in the case of very large installations, oil delivery is made by road tanker. Thus,site facilities must be provided for tanker parking and the position of the fill terminal bewithin an agreed distance from the park. The fill terminal should be a standard 50, 65 or80 mm male gas thread, the size being determined by the length of the fill pipe and thegrade of oil. The thread should be suitable for hose coupling and fitted with a non-ferrouscap as protection. As may be seen from Table 11.4, the heavier grades of oil are deliveredalready heated and for such usage the fill pipe should be insulated and provided withelectrical trace heating.Where more than one tank exists, filling should preferably be through separate pipes,one per tank, although a single fill pipe and an arrangement of three-way cocks or valvesat the tanks may be used. Fill pipes should, where practicable, be laid to drain into the