I am looking for some advice on the design of a fuel storage system (Tank, Pump, Heater).
This tank is a one day storage tank for a fuel oil being used in an industrial furnace. Due to the viscosity of the oil it needs to be heated to flow well enough to be atomized in the furnace burner. The client has requested that the fuel oil heater be external. My current design is an insulated vessel with a pump that circulates oil through a steam heated shell and tube exchanger recalculating a majority of the flow back to the storage tank with the rest being sent to the furnace under flow control. The vessel will use a nitrogen blanket to ensure an inert vapour space and a PCV will control the pressure inside the vessel to slightly above atmospheric (~5 mbar).
My questions are as follow:
· Do the overflows on storage tanks typically have a rupture disk to reduce the wasting of nitrogen?
· As this system has an external heater it is dependent on the pump running in order to keep the contents of the vessel warm is this common in the industry? Do these systems have some sort of emergency steam tracing on the lower portion of the vessel?
· Are radar level instruments the norm for level measurement?
· I currently plan to specify the pump to be able to turn over the contents of the vessel every six hours, is this a reasonable value?
· At 4 bar(g) the steam temperature is ~ 150 for a fairly heavy oil am I at risk of auto ignition?
· Was planning on having the oil the tube side, any issues with this?
Is there anything else I should think about or are there an huge mistakes in my design?
Additional Information Below:
Fuel Oil
Pour Point = 24C
Flash Point = 66C
Viscosity = 180 cSt
B/L Supply Temp = 120C
Fuel Oil Tank
Atmospheric Vertical Cylindrical Tank
Volume = 100m3
Storage Temp = 100C
Heater
Shell and Tube
Steam Pressure 4 bar(g)