ACHRNEWS

Detecting And Correcting Oil Flow Problems

November 23, 2005
What are some of the most common heating oil problems and their possible solutions? Here are some thoughts about quick and easy methods to determine oil flow problems and how to choose the right additive or corrective procedure.

Problem: Icing

Many times technicians must use their intuition and experience to evaluate problems. If icing is suspected, technicians should first check the tank for water by using a water-finding paste.

When water is present, it is usually in the lines and probably pooling at low points in the system. Ice in the tank will not give a positive reading. Water-finding paste must contact water in order to react. It is easy to determine if the problem is ice, provided a sample of the blockage can be obtained.

Technicians should take the sample and drop it into a clear glass jar or bottle filled with warm fuel oil. When the sample melts, the ice crystals will form water droplets that will appear in the bottom of the container.

If there is ice in the line, how do technicians get the de-icing additive to the blockage and quickly unblock the plug?

This cannot be accomplished by pouring the additive into the tank unless there is a small amount of flow through the line to the oil burner.

The quickest and best way to unblock a plugged line is to use de-icer under pressure. This product injects a large amount of de-icer directly to the ice plug utilizing 100 psi of pressure. The ice plug should melt within 5 to 10 minutes after injection. Water absorbents in the de-icer should then allow the plug to be burned with the fuel.

It is possible to de-ice by using a de-icing agent added directly to the tank when there is ice in the tank. Several bottles may be required for a severely iced tank. The de-icing agents will drop to the bottom of the tank and begin melting the ice. It can take approximately two to three hours or longer to effectively de-ice a tank. The length of time is dependent on outside temperature and the amount of water in the tank.

Problem: No Cold Flow

There are situations in which it can be difficult for technicians to differentiate between no oil flow due to icing in the line or cold-gelled oil. Fuel oil that has poor cold flow properties looks almost like "granular" Vaseline®.

The material, when placed in a hand or on a warm surface, will quickly return to a liquid. When placed into warm fuel oil, the gelled material will redissolve leaving no residue.

Fuel oil has a cold flow problem because it contains wax. Depending on the refinery and the oil feedstock, different heating oils have different wax contents and crystal formations. Kerosene contains almost no wax, giving it natural, extremely low pour points. Burning almost pure kerosene will likely ensure no problems in cold weather.

Cold-flow improving additives and pour point depressants are identical. These additives work by modifying or distorting the wax crystal being formed during a cold snap. The modified crystals tend not to interlock, which stops or impedes oil flow. These additives can reduce the pour point of oil by 5 degrees to 20 degrees F.

This does not imply that oil with a 15 degree pour point will now have a -5 degree pour point. Rather, at best it may flow at -5 degrees. Furthermore, not all oils react in the same manner and some may not react at all.

Cold flow improvers must be added prior to the oil gelling or waxing. Adding a cold flow improver once the tank has gelled is not effective. The only effective methods at that point are warming the gelled oil, adding warm kerosene, or agitating the tank. The motion of the oil tends to break up the wax crystals.

A quick way to get the oil moving again and break up the gelled oil in the tank is to inject a de-icer and sludge solvent with a pressure device through the feed line.

The de-icer must be added downstream of any check valves. Solvents, de-icing additives, and the motion should break up the gelled oil.

If tank temperatures do not increase within an hour, however, the oil will regel. To prevent regelling, a pour point depressant should be added.

Adding kerosene measuring at least 15 percent of the tank volume and containing a cold flow improver should keep the oil moving through declining temperatures. Many additives claim pour point depression.

If the additive is a multi-use product, however, it probably does not contain enough pour point depressant to be effective. The one-product "cure-alls" usually don't work under these conditions.

Problem: Copper Gelling

It is a known fact in oil refineries that copper and distillate fuel are not compatible. These incompatible materials form a copper "mercaptide" gel.

Mercaptides are sulfur-based organic compounds found in distillate fuels in trace quantities. The reaction of brass or copper with mercaptans in the fuel forms an oil insoluble gel.

This gel is unaffected by ambient temperature and is actually an insoluble grease. In addition, the gel tends to stick to nonferrous metal parts and will plug brass-fitted filters quickly.

A quick mercaptan gel test is to take some of this gel and drop it into clean warm oil. If it doesn't dissolve it is probably a mercaptan gel. Once a gel has formed, it can only be removed by hand cleaning system components using a good degreaser. The use of a pressurized solvent cleaner will help force the copper gels through the system so they can be burned.

Using a fuel additive that contains metal deactivators or stabilizers and water coupling agents can prevent future formations of mercaptan gels.

This class of additive specifically targets the copper and brass by reacting with the metal before the fuel can deteriorate. It further prevents fuel deterioration by keeping these metals "tied up" and not allowing them to interact with the fuel.

Water definitely contributes to the gel-forming process by freeing up copper ions. As a result, an additive should be used year round to prevent mercaptan gels from forming. This problem is particularly bad in the summer when fuel is lying stagnant in the oil lines and pumps.

Problem: Microorganisms

Microorganisms or "bugs" growing in oil is a myth. This is not true. The bugs actually grow in the water phase of the oil tank and feed off the oil.

Microorganism growth does not begin if there isn't water in the tank. The oil is only a food source. Microbe waste products include large amounts of acidic materials, which are capable of corroding tanks, pipes, pumps, and fuel lines. Microbial bodies can plug filters and screens. The key to preventing bugs in oil is to keep water out of the oil tanks.

There is no quick and easy test to determine if microorganism growth exists in the fuel oil tank. Slimy and stringy masses on filters and screens may be an indication of "bug" growth. If it is determined that there is microbial growth in an oil tank, the water should be pumped out. This should reduce the bug body count by 90 percent to 95 percent.

Killing the bugs with a microbiocide and not removing the water can lead to serious filter plugging problems. There are no chemical means to remove the dead bodies. They must be removed mechanically, or over time they will breakdown into finer filter plugging particles.

Once the water has been removed from the system, an Environmental Protection Agency (EPA) registered microbiocide may be introduced according to the directions. A good microbiocide should prevent future contamination.

Boron-based biocides tend to concentrate themselves in the water phase of the oil tank. Continuous use of a microbiocide is often suggested because it should disperse greater concentrations of biocide into the system.

Once a system has been contaminated, it will be prone to future bug attacks. No biocide can truly sterilize a system. A few surviving organisms will be present to recontaminate the oil as soon as conditions are prime.

It is important to control the infiltration of water to help prevent recontamination. A diligent program including water testing and year-round usage of an additive will help prevent future problems. For serious water infiltration problems, it is suggested to use some water dispersant to redistribute the water.

Problem: Sludge And Varnish

Sludge is a general name for a complex of organic and inorganic material. This matrix of sticky, oxidized byproducts accumulates in tanks, lines, filters, and burners, often leading to oil burner plugging, oil system plugging, and outages. Sludge and varnish are constantly forming in a system and the rate of growth usually accelerates over time.

To determine if sludge is present in the system, take a small sample and mix it with one ounce of a commercial sludge-dispersing product. If the sludge breaks up or redissolves within several minutes, the chosen testing additive should fix the problem.

In order to maintain a satisfactory degree of cleanliness in an oil system, it is important to continually use a fuel oil additive designed for year-round usage.

When a newly formed sludge problem is encountered, use a product specifically designed to remove and disperse gross sludge problems. Initial treatment usually requires a double dose to get the fastest response. If the oil line is plugged, use a de-icer or sludge solvent under pressure to clear and dissolve the sludge and varnish in the oil feed line. Doing so should immediately restore oil flow.

It is suggested that an aggressive fuel oil treatment program be implemented to prevent future outages. A comprehensive additive program should save time, money, labor, and aggravation. In addition, it should enhance customer retention programs and convert ordinary heating oil into premium fuel. If service and performance are the company's primary vision, then the proper use of additives should be part of every applicable service plan.

Harvey Grodjesk is the plant manager for the Rectorseal Corp. For more information, visit www.rectorseal.com.

Publication date: 11/28/2005