|Title of Invention||
ECO-FRIENDLY PROCESS FOR RE-REFINING OF USED CRAMKCASE ENGINE OILS
|Abstract||A environmentally friendly process is developed for re-refining used engine crankcase oils, which contain various additives i.e. Detergents, antioxidants, EP antiwear additives, polymers and other contaminants like carbon sludge, oxidation products, wear metals, fuels and moisture. In this process used oil is first dehydrated to remove water and mixed fuel. This dehydrated oil was mixed with a small amount of tri ethanol amine and a solvent i.e. ethylene glycol mono butyl ether to remove carbon sludge and other contaminants substantially from the oil. The purified solvent -oil mixture is subjected vacuum distillation to separate extraction solvent, light hydrocarbons and lubricating oil fraction respectively. A small amount of high temperature antioxidant is added in the solvent-oil mixture to avoid oxidation of oil during distillation. This lube base stock is bleached with activated clay to get metal free and odourless lubricating oil. The used oil subjected to the re-refining process of the present invention is relatively free of PCB's for environmental concerns. The residue can be used for making soft asphalt and other applications. Hence this process is zero waste environmentally friendly technology of re-refining of used crankcase oils.|
THE PATENT ACT,1970
(39 of 1970)
THE PATENTS RULES,2003 COMPLETE SPECIFICATION
See Section 10; Rule 13
Title of the Invention:
Eco friendly process for pre-defining of usedcramkcase engine, oils
Hindustan Petroleum Corporation Limited Research & Development Center, Plot D-500, TTC Area of MIDC, Navi Mumbai, Maharastra India.
The following specification particularly describes the nature of the invention and the manner in which it is to be performed.
ECO-FRIENDLY PROCESS FOR RE-REFINING OF USED ENGINE
3. PREAMBLE TO THE DESCRIPTION Field of Invention
The present invention relates to the process specifically related to an ecofriendly process for the re-refining of used engine crankcase oils by the removal of carbon sludge, oxidation products and liquid impurities contained therein.
Background of the Invention & the Related Art
The fast depletion of the petroleum resources world over and the environmental legislations on disposal of the used lubricating oil have focused attention on development of an eco-friendly process development of re-refining of used lubricating oils particularly, used crankcase engine oils. The re-refining extends the life of the petroleum resource indefinitely. The re-refining is preferred because the re-refined used oils takes only about one-third of the energy than making of the lubricating oil from refining crude oil. Additionally, the used oil is becoming one of the biggest challenge for performing the waste disposal maintenance activities for industries. Recycling is the most efficient and economical way of managing the used oil. The re-refining saves money by preventing the costly clean ups and the liabilities that are associated with mismanagement of the used oil and to protect the environment. The current all India requirement of the base oil is about 25,000 KL and presently about one-third of it is indiscriminately dumped or burned every year in the country, thus, the contamination of the water and polluting the environment by releasing the metallic oxides into the atmosphere. These metallic contaminants are generated from the lubricants and the fuel additives incorporated for keeping the required engine performance. Additionally, due to the inadequate and the unsafe technology of reprocessing tones of used oil is wasted. These oils have generally been
used as the engine crankcase lubricants, transmission and gear oils etc. These oils commonly contain various detergents and extreme pressure additives such as polyvalent metal soaps as well as impurities which result from oxidation of the oil itself, water and fuels (diesel, gasoline).
Presently various processes are being adopted for the purification and reprocessing of used lubricating oils.
Typically, the used oil is heated to drive off volatile hydrocarbons and water and to permit some of the solids to settle before adding a strong mineral acid which precipitates out a large portion of the oil as sludge. The supernatant oil is separated from the sludge, neutralized with a caustic and distilled or further treated with clay and filtered. This process is severe, altering the petroleum base composition of the lubricating oil and resulting in the loss of a substantial quantity of the recoverable organic materials and ultimately producing a product deficient in properties required in high-quality lubricants.
Some reprocesses utilize the sodium hydroxide rather than an acid, but in either of the process a large percentage of the used oil is lost (up to about 50%) and large quantities of acidic or caustic sludge remain which are increasingly difficult to dispose of due to environmental considerations.
Additionally, severe treatments of the acid or caustic type result in a substantial loss of diaromatic and polyaromatic polar materials from the oil. The higher molecular weight aromatics are generally associated with natural lubricity characteristics of the base oil and removal of these compounds would affect the performance of the lubricant. Likewise, the polar materials are responsible for natural resistance to oxidation, and selective removal of these compounds will contribute to poor oxidation stability of reprocessed lubricating oils.
The various other processes have also been developed to meet the environmental
legislations by utilizing various hydrocarbon liquid diluents which may be also combined with the solvents such as alcohol or water-alcohol mixtures to form solvent precipitation mixtures. Even though these processes do not result in a loss of the desirable aromatic compounds, most of these solvent processes still are not able to remove the sufficient contaminants from the used oil and need some additional steps which utilize an acid or other more severe treatment.
Considering the environmental regulations for disposal of spent acid/alkali, pretreatment of the used oil by extraction with a solvent at ambient temperature is preferred to remove most of the additives, carbon sludge, oxidation products and other contaminants substantially from the oil and to prevent coking and column fouling during distillation.
Summary of the Invention
We have invented a acid free pretreatment process for re-refining of the used engine crankcase oils which produces a high recovery yields of highly purified oil and which does not result in an environmentally objectionable byproducts. In this process the used oil is first dehydrated to remove any water and volatile hydrocarbon. Then, 5 to 6 parts of this dehydrated used crankcase engine oil is mixed with 0.5 to 1.0% tri ethanol amine and 1 part of ethylene glycol mono butyl ether and is kept for 2-3 hours at 40-50°C. Then, this mixture was kept for settling for 18 to 24 hours. Due to the high polarity of solvent most of the additives, carbon sludge and other contaminants settle due to coagulation from the oil in the bottom along with some solvent. The upper layer clear is mixture of the oil and the solvent.
The purified oil-solvent mixture is separated from the sludge and is subjected to the vacuum distillation at 10 to 20 mm Hg pressure to separate extraction solvent, light hydrocarbon fraction and lubricating oil fraction upto 80-90% recovery. The residue is
processed for making of the soft asphalt, fuel oil and other applications. Thus this process is virtually zero waste, environmentally friendly technology of re-refining of used crankcase engine oils. The object of the invention is to develop an eco-friendly process for purifying the used engine oils which gives increased yields of oil, while utilizing the less solvents and produces a sludge which is environmentally compatible and is useful as a byproduct.
4. DESCRIPTION OF THE INVENTION
The used engine crankcase oil is dehydrated in order to remove water and other volatile hydrocarbons which may be present in the used oil to prevent the formation of azeotropes with the solvent which may later hinder separation of the sludge and the solvent recovery.
The dosage of the tri ethanol amine should be from 0.5 to 1.0%. The higher amount of this amine may results in the haziness of the product and alter the process of the coagulation. The used oil to solvent ratio may vary from about 3 to 5 parts used oil to one part of the solvent, while the normal ratio is preferably from 5 to 6 parts of oil and one part solvent depending upon the type of impurities in the used oil contains without affecting the coagulation of sludge. It is preferable that, the contact between the solvent and used engine oil done at 40-50°C. The slightly higher temperature will increase the effectiveness of the solvent by precipitation of sludge and carbon residue, while higher temperature above 60°C, reduces the effectiveness due to the evaporation of solvent. Then, this mixture of oil and solvent is kept for settling, for 18 to 24 hours. Due to high polarity of the solvent most of the additives, carbon sludge and contaminants settle from the oil by coagulation at the bottom along with solvent. The upper layer is a mixture of oil and solvent.
Alternatively, a centrifuge be used to separate the sludge from the solvent-oil mixture immediately after mixing. The sludge obtained from the separation process contains
no other added solid matter and hence is not objectionable from environmental legislation point of view. The sludge contains more amount of solvent and can also be recovered by either atmospheric distillation or under reduced pressure. The sludge is high in the metal contents. The purified oil-solvent mixture is subjected for the vacuum distillation at 10 to 20 mm Hg pressure to separate the extraction solvent, the light hydrocarbons fraction and the lubricating oil fractions upto the maximum recovery. To avoid the thermal oxidation, 0.20 to 0.30% aminic antioxidant is added in the oil-solvent mixture. This lubricating oil fraction is bleached with activated clay to get metal free and odourless lubricating oil.
The following example illustrates the process involved in the invention. For this process a used crankcase engine oil used. The physico-chemical properties of used oil selected for re-refining are as under:
The used engine oil is first dehydrated at 120 to 140°C to remove the water and light hydrocarbons (due to fuel dilution) from the same. Then, four to five parts of this dehydrated used oil is mixed with 0.5 to 1.0% tri ethanol amine and 1 part of ethylene glycol mono butyl ether at 40 to50°C for 2-3 hours. This mixure is kept for settling for 18 to 24 hours. The above mentioned settling time depends on the size and the amount of contaminants present in the used oil. After 18 to 24 hours there is a clear separation and two layers take place. The upper layer is quite clear and the bottom layer is containing the black carbon sludge and other impurities. Then, with some amount of ethylene glycol mono butyl ether is mixed. The upper layer is then separated from the sludge. Alternatively, the mixture of the oil and solvent can be centrifuged for faster separation of the sludge. After the complete separation the upper layer is 80% and sludge is 20%. This top solvent oil mixture is then subjected to the vacuum distillation at 10 to 20 mm Hg pressure to separate the solvent, the light hydrocarbon fraction and the lubricating oil fraction. In the solvent-oil layer, 0.20 to 0.30% aminic antioxidant is added to avoid cracking during distillation. The two fractions of the lubricating oils are collected at AET of 311 to 475°C and at AET of 398 to 540°C. Lastly, these fractions were given 3% fuller's earth clay treatment at 80-90°C for 1 hours to remove smell, improve colour and residual metals.
These lubricating oil fractions were meticulouly tested for the physico-chemical properties (Table 1). In addition, the base oil fractions were tested for four ball wear scar diameter (Table 2) in a fully formulated Hydraulic oil vis-a-vis hydraulic oil manufactured with virgin oil. The physico-chemical properties of two blended oils when tested as per DIN 51524 Part II specifications were found to be in agreement.
Four ball EP test (Table 2)
The above process reveals an improved pretreatment process for reprocessing of the used engine oils with increased oil recovery. The rerefined oils thus obtained can be reused for manufacture of the finished lubricants of similar qualities as obtained from the oil made from virgin oils. Hence, an eco-friendly process for re-refining of the used engine crankcase oils been developed and technique demonstrated.
5. WE CLAIM:
1. The eco-friendly process for re-refining of used engine crankcase oils, the used engine oil being pre-treated i.e. dehydrated at 120*to 140°C to remove the water and light hydrocarbons (due to fuel dilution) from the same, taking four to five parts of the dehydrated used oil mixed with 0.5 to 1.0% tri ethanol amine and 1 part of ethylene glycol mono butyl ether at 40 to50°C for 2-3 hours,
2. The eco-friendly process for re-refining of used engine crankcase oils as
claimed in claim 1 wherein, the mixure obtained, being kept for separation of
of sludge for 18 to 24 hours, then, the layer the sludge being removed,
3. The eco-friendly process for re-refining of used engine crankcase oils as
claimed in claim 1 and 2 wherein, the upper layer being left on removal of the
sludge from the mixure and 0.2 to 0.3% antioxidant being added to avoid the
oxidation of oil during distillation^further the purified solvent-oil mixture being
subjected to the vacuum distillation to separate the extraction solvent, the light
hydrocarbon and the lubricating oil fraction respectively.
|Indian Patent Application Number||1498/MUM/2005|
|PG Journal Number||N/A|
|Date of Filing||02-Dec-2005|
|Name of Patentee||HINDUSTAN PETROLEUM CORPORATION LIMITED|
|Applicant Address||RESEARCH & DEVELOPMENT CENTRE, PLOT D -500, TTC AREA OF MIDC, NAVI MUMBAI 400 705, MAHARASHTRA, INDIA|
|PCT International Classification Number||C10M 101/00|
|PCT International Application Number||N/A|
|PCT International Filing date|