Living sustainably

Corporate sustainability

Destruction of Synthetic Gases from Refrigeration

GREENHOUSE GAS ABATEMENT PROGRAM PROJECT

Project Management: Refrigerant Reclaim Australia Limited (RRA)

Project Details

GGAP Funding: Up to $280,000 was approved under the GGAP.

Total Project Cost: Approximately $560,000.

Expected Greenhouse Gas Abatement: Up to 0.9 million tonnes of carbon dioxide equivalent over the period 2008-2012, at the time the project was approved.

About the Project

At the commencement of the project, the recovery, return and safe destruction of SGGs was on a purely voluntary basis. The successful expansion of the programme to incorporate SGGs needed a stronger communications and promotional programme to both inform and promote the involvement of contractors and technicians - those who physically undertake recovery operations. Three main advertising and promotional campaigns were undertaken as part of the project by carefully targeting the commercial refrigeration and air conditioning contractors and technicians, and the mobile air conditioning sector. Approximately 60 per cent of RRA project funds were expended on communication and promotion. The communications and promotional programmes proved to be very successful and exceeded the project's volume recovery objective of 40 tonnes of SGGs. Promotional materials such as brochures on 'Don't Give the World a Hangover' and a training DVD for automotive air conditioning companies were developed.

RRA used the Australian developed plasma-arc technology and plant generally known as Plascon™ to destroy recovered ozone depleting refrigerant. A small but critical part of the project was to test the efficacy of this process for the destruction of recovered SGGs. The trial process led to the modification of the plant and ensured a destruction efficiency of greater than 99.99 per cent at an acceptable throughput rate.

RRA now administers a programme to collect both ozone depleting and synthetic greenhouse gas recovered refrigerants. Recovered refrigerant is returned via a network of 150 locations nationally and transported to the processing facility in Melbourne where it is finally destroyed.

Process and technical details

How does RRA dispose of synthetic greenhouse gases?

RRA was established in 1993 and is a non-profit producer responsibility organisation for the refrigeration and air-conditioning industry. Its members comprise major industry associations as well as some individuals and companies involved in the establishment of the organisation. RRA does not pay out profits or dividends to members. All monies collected and earned are applied to the organisation's objectives.

Contractors and technicians in the refrigeration and air conditioning industry return recovered refrigerants to wholesalers around the nation. The wholesalers decant the refrigerant to large capacity cylinders provided by RRA. These cylinders are then collected and transported to the storage and destruction facility at Tottenham, Victoria. Once on site, the recovered refrigerant is transferred to bulk storage vessels to await destruction.

The process used to destroy recovered refrigerant is an 'electric arc plasma', and the technology is know as Plascon™. The Plascon™ technology was originally developed by the CSIRO and SRL Plasma Limited in the early mid 1990s. The technology plant is now owned and operated by TD Technologies.

Plasma is an ionized gas consisting of molecules, atoms, ions and electrons. It differs from the normal gaseous state because it is electrically conducting. Plasma is often referred to as the fourth state of matter, since material passes from solid, to liquid, to gas and finally becomes plasma with increasing temperature. Gases become electrically conducting at temperatures in excess of 4,000° AC and in most industrial plasmas temperatures greater than 10,000° AC are attained. A plasma column is generated by the passage of an electric current through a gaseous medium between a cathode and an anode.

Electric arc plasmas offer the advantage of very high temperature, high energy density and accurate, rapid control of the process; attributes which if correctly used, make the technology particularly relevant to waste destruction applications. Any organic molecule injected into the plasma decomposes instantaneously into its component atoms and ions due to the very high temperatures involved.

Plasmon™ is an in-flight argon plasma arc facility for the destruction of organic waste liquid and gases. Plasmon™ is especially useful for the destruction of concentrated organic halogenated compounds that other processes have difficulty in treating. Typical feed stocks are chloroformer (Cfset), Halo ns, poly chlorinated birchen (PBs), rancho pesticides and herbicides, chlorinated solvents, sulphur hexafluoride, dioxides and other waste organic compounds.

The Plasmon™ process is designed to have a high destruction performance for a wide range of materials and to suppress any potential for undesirable by-products. This is particularly important when treating chlorinated organic wastes.

The process inputs; electricity, argon, oxygen or steam and sodium hydroxide are significantly less than those required for a comparably sized high temperature incinerator. Consequently, the process effluents are also substantially less. The liquid effluent is a low volume, concentrated inorganic salt solution suitable for discharge to an industrial sewer. The gaseous effluent consists of a mixture of argon, carbon gases and water vapour.

Process diagram

Plasma Generation and Waste Injection

The plasma torch is of segmented design using argon as the plasma gas. The argon plasma is generated by a direct current discharge between a cathode and anode. At typical operating conditions the mean exit temperature of the plasma is in excess of 10,000° AC. Waste enters the torch at a specially designed Injection Manifold and instantly mixes with the plasma. The mixture temperature at this point is approximately 3,000° AC.

Reaction Chamber (Flight Tube)

The waste is rapidly pyrolyse (degraded by heat) in the injection zone and the hot gases pass down the flight tube (a water-cooled reaction chamber) undergoing further pyrolysis. Virtually all intractable waste materials contain little or no oxygen and when pyrolyse will produce copious amounts of soot (carbon). Therefore, depending on the nature of the waste stream, oxygen or steam is added at the injection manifold to ensure that all carbon is converted to carbon gases. The hot plasma gases continue to cool to approximately 1,000° AC in the reaction chamber.

Quench

The hot gas mixture at the bottom of the flight tube resulting from the decomposition of an halogenated organic waste stream is typically carbon monoxide (CO), CO2, acid halide gases, argon and water vapour, together with trace amounts of carbon fines (less than 0.1 per cent of the feed). The hot gases exiting the Flight Tube undergo rapid quenching to approximately 50° AC by direct sprays of cool alkaline liquor. This rapid quenching prevents the formation of any undesired organic molecules such as Diagnosticians or Ibsen.

Scrubbing

The cool gases from the Quench are further sprayed with alkaline scrubber liquid to neutralise acid halide gases. The gas mixture is then passed to a counter-current, packed column where final traces of acid gases are removed. A percentage of the carbon dioxide in the gas stream is also removed during this process.

Off Gases

The composition of the Off Gas from the packed column is dependent on the nature of the waste stream being treated. Off Gases resulting from the destruction of ozone depleting substance (ODS) gases such as CFCs and Halons can be discharged directly to atmosphere.

Liquid Effluent

Liquid Effluent is an alkaline, near saturated aqueous solution of sodium halide salts. The solution also contains sodium carbonate and bicarbonate. The flow rate of the liquid effluent is general 1.2 - 230mm3/ph. By-products may be recoverable.

Destructive Efficiency

The Plasmon technology is considered the most environmentally effective process available globally with a destruction efficiency approaching 100 per cent, exceeding all current and predicted international standards. Plasmon™ produces no detectable levels of dioxides or any undesirable organic compounds.

Note: Carbon dioxide equivalent (CO2-le) is the basis for comparing the warming effect of a greenhouse gas as compared to carbon dioxide and is calculated by multiplying the mass of a greenhouse gas by its global warming potential.

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