AORA Standards for burner oils

 

High Grade Fuel Oil

Mid Grade Fuel Oil

Low Grade Fuel Oil

Introduction to the AORA Burner Oil Standards

In April 2007, AORA entered into an agreement with the (then) Department of the Environment and Water Resources to develop industry standards for used oil as a burner fuel. AORA then engaged the University of Melbourne - School of Enterprise to develop these new standards.

At that time, there were no standards in Australia for industrial burning oils (or 'burner oils'), including the 'low grade' and 'high grade' burner oils that are defined in the Product Stewardship (Oil) Act 2000 ('the Act'). However, the existing and future markets in burner oils are substantial. This project arose from a need to ensure that potential customers are given accurate information about the products, including the standards that apply.

AORA believed it was appropriate to produce specifications for each product as understood by the industry based on accurate definitions, experience and knowledge of used oil products. Thus, the standards are aligned with three types of treatment processes.

The following information can be used to understand the rationale behind the three burner oil standards

Density

Density is measured because burner fuel is often ordered by weight but supplied by volume. If the density value is less than that stated, there will be a relative shortfall in the quantity of product supplied.

Since it is easier to measure the volume of a liquid than its weight, the density affords a convenient conversion factor for specifying the quantity.

Viscosity

Fuel Oil Viscosity tells burner oil users of the ease with which it may flow or be pumped to burners and the rate at which it will be expressed from burner nozzles.

It is well known that as the temperature of the fuel is increased, the viscosity is reduced. Burner equipment is designed to operate with specified burner oil viscosities.

Distillation

The distillation criterion is important because it denotes the temperature at which a product will be totally evaporated in a boiler or furnace application. It equates to some degree to the heating value of a product, and also gives proxy information about other criteria. A distillation criterion is always set for new fuel and bunker fuel, and so should be set for recycled oil so that customers can make appropriate comparisons.

The 90% distillation figure is an important indicator of quality, especially for the High Grade Fuel Oil, since it signifies that distillation has been performed successfully. It is not as important for the Low Grade Fuel and Mid Grade Fuel Oil, which will include ash and non-combustibles.

Pour point

The pour point is an important indicator of fluidity so that customers can be assured that the products they purchase will meet their needs. Too low a pour point would make operation of the oil supply system difficult to operate at low temperatures.

Pour point is included in the Standards to compare recycled oil with new fuel oil that low temperature will cause to solidify if not heated continually.

Flash point

Flash Point is the temperature at which vapour is given off which will ignite when an external flame is applied under standardised conditions. A flash point is defined to minimise fire risk during normal storage and handling.

The flash points of the various grades of oil would normally be similar except for possible presence of petrol fractions taken up by used engine lubricating oil and solvent contamination not removed during re-refining. Flash points of >60oC are considered to offer adequate safety assurance while preserving the flammability desired in burner use.

Gross heating value

The gross heating value is the amount of heat produced by the complete combustion of a unit quantity of fuel.

The minimum values recommended in the Standards increase slightly as used oil is subjected to more extensive treatment and non-calorific impurities are removed. Some customers will be prepared to pay more for 'premium' product that has higher heating value while merely meeting the other criteria that define the particular grade (primary, secondary or tertiary).

Water

There is a connection between excessive water content and heating value - more water equals less oil equals lower heating value - and separation of water can affect the operation of burners, especially if gross water emerging from nozzles results in intermittent combustion of fuel.

The term 'de-watered' is commonly used but normally applies only to oil that has been treated by gravity settling and draining before sale or further treatment. As a rule-of-thumb, such oil contains 6-10% of emulsified water and would be better designated as 'gravity settled and drained' rather than 'dewatered'.

As noted, treatment with emulsion breakers and/or heat can improve separation so that water content can be reduced to = 1%. The treatments address the understandable concern that the purchaser should not have to pay for water.

Ash

This is another important parameter, and the acceptability of oils with higher ash content would be dependent on the nature of the burners and the equipment being fired since clogging of the burner nozzles and steam & water boiler tubes may result when ash content is too high. Some kilns can tolerate fuel with higher ash content.

Sulfur

Sulfur levels in new fuel oils are typically between 2 - 4 %. Very low sulfur distillate fuels are used in environmentally-sensitive areas because of concern over ambient air pollution. Recycled lube oil generally has less sulfur than the heavy fuel oils and coal it can replace.

Vanadium, potassium, calcium and sodium

High temperature corrosion and fouling can be attributed to vanadium and sodium in the fuel.

No standard values are proposed for low and mid-grade burner oils, but metals are removed in high grade treatment processes and the low values recommended can serve as indicators of the efficiency with which the high grade treatment has been conducted. It should be noted that vanadium compounds are found in crude petroleum but that vanadium may also be present in recycled oil as a result of engine wear. The metals sodium, potassium and calcium may be introduced with oil additives.

Sodium, especially, as well as potassium and calcium would be found in oil that has been in contact with seawater, while calcium compounds are among the additives used to enhance the properties of virgin oil and is thus present in used oil.

Cadmium, chromium, copper and lead

Cadmium, chromium, copper and lead are of environmental concern and standards can be used to ensure that their presence in burner oils, and consequent release to the environment, is kept to a minimum.

As with the previous group, low concentrations of these metals in the high grade product indicate that it has been properly distilled.

Inadvertent contamination of lubricating oils by leaded gasoline was the major source of lead, but leaded fuels have been phased out for some years, so significant lead contamination of recycled oil should be rare. Criteria for the other metals, cadmium, chromium and copper, have been adopted from those commonly specified by recyclers for their products.

Polychlorobiphenyls (PCBs)

The toxicity of PCB's has led to a regulatory level set by the National Management Plan (1996), and consequent State and Territory regulations which require fuels to be 'PCB free' - that is, to contain no more than 2 ppm (2 mg/kg) PCB.

The source of PCBs in recycled oil is likely to be mixing of transformer oil, which is commonly contaminated with PCBs, with the used lubricating oil stream. Since PCBs would not be removed by any of the recycling technologies now in use for production of burner oils, the industry is careful to segregate the two streams, with PCB oils going for destruction rather than reuse. It should be noted that the use of PCBs in transformer oils is being phased out and this source of chlorinated oils should disappear in the near future.

Chlorinated compounds

Most jurisdictions apply a regulatory standard of 1000 ppm for total chlorinated compounds in fuels. The regulation takes into account the propensity of the fuel, when combusted, to produce polychlorodibenzo-dioxins and -furans which can be emitted to atmosphere and are potentially harmful to human health.

Funded by the Australian Government under the Product Stewardship for Oil Program.
www.oilrecycling.gov.au