WATER

Water can become emulsified in oil during processing and can also be introduced into oil during handling by condensation, contamination, or leakage. The presence of water can lead to many problems:

water that separates from oil is generally acidic and can readily corrode storage tanks, particularly at the oil/water interface
separated water occupies useful storage space

water at the burner can cause oil flow discontinuity

if it enters the firing system in sufficient quantity, water may cause thermal shock, leading to refractory damage

Most water can be eliminated by means of careful shipping and handling procedures. Proper design and maintenance of equipment can also minimize water leaks, such as those resulting from steam heater or tank leaks. To minimize condensation, proper lagging and heating of the tank are necessary.

Properly selected additives can be used to emulsify small amounts of water (up to approx-imately 1%) economically. Large quantities of water should be removed physically from the tank by draining or pumping. When large amounts of water are detected, the source should be identified and corrected.

Water in storage tanks can be detected by means of a Bacon Bomb. This device is lowered into a tank and opened to allow sampling at any point beneath the surface. The sample can then be evaluated by testing for bottom sediment and water (BS&W). Testing for water can be as simple as waiting for the sample to settle in a graduate.

SLUDGE

Sludge is composed of settled heavy agglomerates combined with suspended matter from an oil or liquid fuel. Sludge formation increases when fuel oils of different crudes or liquid fuels of different sources are mixed. When fuel oils are heated in a tank to ensure good flow, the likelihood of sludge formation is increased. If the heat is high enough to break the water in oil emulsion, the heavier agglomerates may settle. Sludge formation in the tanks reduces storage space for usable fuel and removes part of the high energy containing components of the fuel. Frequent strainer cleaning is required to prevent high pressure drops and ensure good flow. Sludge formation can also cause heater burner tip fouling. Sludge can be detected in a storage tank by Bacon Bomb sampling of the tank.

In order to mix settled sludge with new fuel, it helps to fill the storage tank from the bottom. A tank with effective lagging (outer insulation) is less susceptible to sludge buildup. Long-term storage (over 7 days) should be avoided and some method of recirculation employed to keep the heavy agglomerates mixed. Where mechanical methods are not completely effective and/or some degree of help is desired, additives are effective in dispersing sludge, even at low use rates. The additives help clean fouled storage tanks and heater and burner assemblies, on-line or off-line.

Many advantages result when fuel sludge is minimized:

Increased energy content in the fuel increases efficiency.
Clean tanks afford maximum utilization of storage space.
Clean feed lines, heaters, and burners are essential to good flow and good combustion.
Proper fuel conditioning produces good flame patterns, reducing the chances of flame impingement.

Proper fuel flow allows the boiler to operate at maximum capacity and helps control the formation of burner deposits. It also allows operation at minimum excess air, which helps control slagging and high-temperature corrosion.