Contact our plant for additional information, advice and pricing.
| eNZoil New Zealand Ltd., 127 Port Rd., Seaview, Lower Hutt. | |
| Phone: | 04-5760567 |
| Fax: | 04-5760915 |
| Email: | enzoilquestion@gmail.com |
Contact our plant for additional information, advice and pricing.
| eNZoil New Zealand Ltd., 127 Port Rd., Seaview, Lower Hutt. | |
| Phone: | 04-5760567 |
| Fax: | 04-5760915 |
| Email: | enzoilquestion@gmail.com |
Many utilities worldwide and now locally, specify Regenerated Oil in place of both New Imported and locally Reclaimed Oil for initial filling of new transformers and for refilling refurbishments. ENZOIL Regeneration maximizes the potential of a diminishing resource by full and safe conversion of used transformer oil to meet or exceed all international new oil standards. ENZOIL Regeneration is a zero waste process and has a negligible carbon and environmental footprint compared to alternative refining and reclaiming methods. Thus, the trend towards regeneration continues as the most environmentally compliant and cost effective option.
ENZOIL uses high-tech regeneration or selective depolarisation to restore spent transformer oil to an as-new condition that exceeds all the international standards set for new transformer oil.
Regenerated oil uses a more consistent feedstock, local used transformer oil, which is renewable many times over by regeneration, as opposed to imported oil which is non sustainable, becoming more scarce, is variable in composition and price, and can contain unspecified additives
Regeneration is less harsh, more consistent and selective, compared to imported oil produced by the severe hydrotreatment refining process introduced twenty years ago. This results in a regenerated oil with superior inherent oxidative and non corrosive performance. The bottom line is longer life, lower transformer maintenance and less oil related outages.
The ever fluctuating price and inflationary effect of imported oil and its impact on project planning is mitigated by use of a locally available feedstock (used transformer oil) which enables consistent pricing.
The carbon footprint of imported oil is huge compared to regenerated oil. Overseas oil refineries emit millions of tonnes of carbon per annum. Add to this, carbon emissions from shipping to NZ ex US, Europe and Asia.
Around 1990 there was a significant change in oil refining practices. The previous methods produced lower yields of refined product from a barrel of crude oil and higher levels of toxic sludge which was a major environmental issue.
Severe hydrotreating using hydrogen and a catalyst became the preferred refining process worldwide producing higher yields and less toxic waste.
Severe hydrotreating is non selective, reducing all sulphur types including natural sulphur compounds which otherwise act as oil stabilisers (anti oxidants). Depending on the feedstock used, severe refining can lower oil stability to unacceptable levels as determined by standard test methods for oxidation stability.
In these cases, to restore oil stability, some refiners have added back sulphur in the form of a synthetic additive, DBDS (Dibenzyl Disulphide). Under certain conditions in the transformer DBDS degrades to form corrosive sulphur which reacts with copper parts to form highly conductive copper sulphide which deposits on windings and insulation paper. Terminal failure follows by shorting, arcing and then fire or explosion.
To minimise the formation of copper sulphide, another additive, metal passivator was added but these have failed to provide robust protection and have caused side effects. As a result large transformers worldwide continue to fail, many after only five to seven years in service.
Most international transformer oil standards specify that there should be no additives in transformer oil other than chemically specified antioxidant but for inhibited oils only.
Until recently, test methods to detect corrosive sulphur were inadequate. As a consequence the same brand of oil used in a failed transformer was often returned to the same repaired transformer only to cause a repeat failure having been given a clean bill of health by test methods applicable at the time.
CIGRE estimates that there is one billion gallons of Transformer Oil worldwide containing DBDS installed in electrical equipment.
This oil mainly represents brands from three major oil companies.
Johan Manaf of the University of Southampton, in his paper “Corrosive Sulfur in Insulating Oils with respect to Large Transformers and the Oil Test Methods”, claims that a large proportion of power transformers installed since 1990 have failed due to corrosive sulphur.
In a 2008 presentation to Brazilian customers Doble stated “that the large majority of recently failed transformers due to corrosive sulphur had DBDS”.
At the 2008 CIGRE International Conference in Paris it was reported that a 2005 survey of 630 Power Transformers on interconnection duty, over 50% of the segment built over the previous five years showed a corrosive condition.
Sea Marconi report that a large power generation transformer which was built in 1998, failed in 2003 due to corrosive sulphur causing a major black out throughout Italy amounting to tens of millions of Euro of direct and indirect damages.
2009 Doble International Conference reported that “ according to some experts more than 100 transformers have failed worldwide owing to corrosive sulphur”
Corrosive sulphur first impacted early in the life of large generator and shunt transformers, because of high operating loads and temperatures which trigger the corrosive reaction. Free breathing Power Transformers on HVDC Converter and Interconnection duty were slower to show the problem. More recently and taking longer to fail are those distribution transformers that have exposed copper components.
The main source of corrosive sulphur, DBDS wasn't discovered until 2005 (Source: Sea Marconi), many years after the first failures were reported. DBDS is added at very low concentrations 50 to 350ppm and the very nature of it and it’s derivatives, makes detection very difficult. Special testing equipment is required. While most country have experienced failures, only cases in UK, Italy, Brazil, Spain, S Africa, Canada, Mexico, Norway, Belgium, France and Saudi have reached the public arena.
While the number of failures is estimated to be between 100 and 150 some of which have been fatal, this does not include the very large number of power transformers which on having their oils tested for corrosive sulphur, were found to be in a "corrosive condition". Fortunately in most of these cases there was time to mitigate the problem including implementation of the regeneration option thereby avoiding failures and unscheduled outages.
ENZOIL Regeneration can also be used to upgrade new oil and it is now recommended as the most effective and safest means of detoxifying oil containing corrosive sulphur compounds.
As stated above corrosive sulphur problems have arisen as some manufacturers have added supplements to new oil to compensate for the effects of severe hydrotreatment.
The ENZOIL Regeneration Process effectively removes the corrosive sulphur compound returning the oil to full specification including oxidation stability (indicative of the oil’s longevity).
The ENZOIL Laboratory is installing equipment for detecting corrosive sulphur and it is recommended that customers avail themselves of this service to check all large transformers.
A transformer failure due to corrosive sulphur problems normally results in a full transformer refurbishment at a cost of 60 to 70% of the value of a new power transformer.
“On passivators "CAUTION, the Doble Engineering Company does not recommend or approve any of these additives. These additives are used at your own risk" ( Source: Doble 2008 Bulletin which also lists all commercially available passivators).
"How ironic to have to depend on an additive in order to counteract what appears to be another one that is not supposed to exist." Source "Understanding and Management of Sulfur Corrosion from Insulating Oil" presented at CIGRE 2008 International Conference in Paris
ENZOIL is also an importer of new oil for those customers requiring it, but has chosen a refinery source that has not had to use non standard additives, such as DBDS and passivators, because of selective feedstock streaming and hytrotreating.
As Vander Tumiatti of Sea Marconi, said in his Lecture to “My Transformer International Advisory Committee”, 17/18 Dec 2008: “ Reclaiming-with fullers earth is not appropriate for the effective elimination of critical contaminants (such as corrosive sulphur compounds, aldehydes, ketones etc) in compliance with IEC oil maintenance standards. These operational practices, many times, create the conditions for propagation of critical factors within the transformer fleet, caused by cross contamination. The consequences of these actions are high financial costs both in terms of disposal of dangerous waste and carbon dioxide equivalent emissions.”
Contrary to claims, the Fullers Earth process cannot restore used transformer oil to recognised international standards, thus not attaining its potential as a new oil substitute or classification as a renewable resource.
Reclaiming results in a 15 to 20% loss of the used oil volume and produces a concentrated sludge of oil, transformer degradation products and fullers earth, the mixture of which is an acknowledged carcinogen.
This waste, a toxic soup of organic compounds, acids and sludge has to be dumped and is normally disposed of in local landfills incurring a high risk of potential contamination of the environment and groundwater. Landfill operators are becoming more discerning and it is becoming more difficult and costly in some areas to dispose of this waste.
Alternatively, disposal of waste by burning as a fuel or as a fuel extender is just as damaging as toxic pollutants are released into the atmosphere e.g. 1 tonne of waste oil produces 5 tonnes of carbon dioxide. This practice still persists in NZ.
Fullers earth and filtration plants are not appropriate for eliminating polar contaminants such as corrosive sulphur and oxidation sub products. In fact these plants spread the contaminants by cross contaminating subsequent operations.
Although diminishing, reclaiming oil with Fullers Earth is still evident in NZ.
NOTE: ENZOIL Regeneration is a zero waste process, each step of which undergoes rigorous Quality Control testing by an experienced graduate chemist.
ENZOIL has never used undeclared additives such as DBDS or Passivator.
Stockists for Q8Oils automotive and industrial lubricants.