Book - School of Science and Technology

Liquid fuel 307For heavy oils, grades F and G, it is necessary to provide heating and pumpingequipment to take fuel from storage and deliver it to the burners. At the tank, an outflowheater may be provided, as in Figure 11.5, designed to preheat oil flow at the point of exitrather than in store. The principal item of equipment may be a prefabricated pumping andheating unit as shown in Figure 11.6 which incorporates not only the necessary positivedisplacement pumps but also hot water or steam heaters with electrical back-up for usewhen starting the plant from cold.From the pumping and heating set, the hot oil circulation is extended right up to theburner in order to avoid any problems of smoke on start up but variations in the actualarrangement may be found to be necessary with burners which do not incorporateintegral pumping equipment. Pipework carrying oil at the temperatures noted in Table11.4 should be insulated and be provided with trace heating, either electrically or by hotwater/steam as may be available.Tank faceOutflowShroudedheating elementTo burnerFigure 11.5 Oil tank outflow heaterBoilersRotary cup burnerwith oil pumpRing mainBy-pass forquick heat upNon return valveTracer linesTracer lineSteam or hotwater oil heatersElectric oil heaterIndicates stop valveDuplicateoil pumpsDuplex strainerFire valveFrom oilstorageFigure 11.6 Pumping and heating set with oil ring main