ITUB20151298A1 - Process of regeneration of used oils - Google Patents

Description

PROCEDURE FOR REGENERATION OF USED OILS

DESCRIPTION

The present invention relates to a regeneration process of used oils, in particular of mineral oils, aimed at obtaining a particularly clean product, which can be used as a lubricating base, increasing the valorisation of the used oil with respect to the processes of the known art.

In almost all sectors of mechanics, lubricating oils are used to make parts of engines and the like flow between them. A classic example? that of the oil used in internal combustion engines to help the sliding of the pistons in the cylinders, without the parts getting stuck together.

Lubricating oils are often used in machinery that involves very fast relative sliding movements of their parts. This, in addition to other facts, does s? that lubricating oils frequently undergo even very strong variations in temperature. For this reason, oils undergo chemical reactions of various kinds, which alter their nature. Do you have cos? reactions of cleavage, dehydration, dehydrogenation, condensation, etc. An example of such reactions? the dehydrogenation-dehydration of oils, which leads to the formation of carbon in the form of carbon black. In some cases, asphaltenes and bitumens also form. Furthermore, oils can come into contact with other substances, such as, for example, metal and / or ceramic particles, which remain so. inside the oil itself. Also, don't you? it is rare that spurious substances are mixed with oils, such as polymers of various kinds, since their use and / or their collection after use are not always carried out appropriately and with caution aimed at avoiding the introduction of foreign substances and obtain a quality deviation.

The transformations mentioned above and others do s? that the oil sees its physical and chemical characteristics deteriorate with use, ending up even being harmful to the machines inside which they are used due to the fact that the foreign substances that are found significantly increase friction. So? ? it is advisable to replace the oil after a certain use with fresh oil, so? to avoid reductions in the performance of the mechanisms or even their breaking.

Used oil contains a number of toxic substances, which is why it can't? simply be discharged into the environment, but must be treated to reduce its environmental impact. Yup ? thus came to the regeneration of used oils, which allows to reduce waste and the consequent environmental impact.

The first plants for the re-refining of used oils date back to the 60s of the twentieth century, when do you start? to create and spread an ecological awareness. Given the high costs of obtaining freshly refined oils and due to the increased consumption of these oils, the regeneration of waste oils? which has acquired important market shares over time.

Did the creation of mandatory consortia for the collection of waste oils then make it available easily? the material to be treated, now widely available at a good price, even if its quality level? rather poor. This type of market does it? gone a lot expanding over the years. About a third of the used oil is correctly collected by the consortia and sent for regeneration or other treatments to make it harmless, the rest being improperly dispersed in an uncontrolled way in the environment and being a source of pollution or, in any case, lost in its service cycle. , with economic damage too.

The typical yield of a regeneration process, starting from 100 kg of used oil to be sent to the process? today about 60 kg of regenerated oil (base for lubricants), 20-25 kg of fuel and 20-25 kg of bitumen.

Historically, the first processes were those with sulfuric acid or with propane. What do they deal with? the oils by adding sulfuric acid or propane, so? to eliminate a good part of the impurities contained in the used oils. However, the acid process? been practically abandoned, due to the considerable pollution problems it entails.

The process with sulfuric acid causes the formation of acid sludge, which retains internal quantities? not negligible of oil and which also contain polymeric compounds and heavy metals; these sludges are difficult to dispose of, there? which generally takes place in landfills, preferably after neutralization, which for? the volume of the sludge to be disposed of increases. Yup ? attempted for this the way of the combustion of sludge, but yes? proved impractical.

Yes, they are so? developed other processes, starting from the one already? mentioned that it uses propane.

The acid treatment phase is completely replaced by a clarification with liquid propane. Do you choose propane as a hydrocarbon, why? easily liquefiable and of low density? once liquefied. It therefore acts as a fluidifying agent on the oils to which it is added, so? to allow the separation of a high-density phase? - which contains high molecular weight polymers and heavy metals - from a second fraction, consisting of clarified and dehydrated oils. The propane is then removed and recycled when mixed with the incoming oils.

A hot filtration is then carried out, allowing the recovery of a gaseous fraction. It then ends with discoloration and deodorization of the content.

This process, which allows you to achieve higher returns? high, however, still has some disadvantages. First of all, handling propane can? be dangerous for plant workers. In addition, some of the propane is trapped in the asphalt; this presence excludes the use of the bitumen obtained for the construction of roads, with considerable economic damage. Therefore, the bituminous fraction in this process is simply a waste, to be disposed of and cannot? be valued. Finally, the process? by itself? much more? expensive than the sulfuric acid process.

In more years? recent, ? A new type of process has been introduced, which provides that the used oils are sent to the axial rotor of a distillation column and from said rotor are sprayed on the internal walls of the column, kept at high temperature thanks to a diathermic fluid that flows through some ducts . In contact with the heated walls, the vaporizable fraction evaporates, while the pi? heavy remains in the liquid phase. The fractions are then collected and further fractionated in a subsequent fractionation column, where it is divided into further cuts within a subsequent fractionated distillation column. The yields of this process are important, but preventive treatment is required to purify the used oils.

EP 0 618 959, by the same Applicant, describes a process for re-refining used oils, in which said oils are put in contact with a basic reagent, heated to eliminate the water contained, the polymers and heavy metals are separated, proceeding to the fractional distillation in a filled column to obtain one or more? fractions of bases for lubricants and discolouration. The basic reagent? a strong base, the water is eliminated together with a fraction pi? volatile in a preliminary phase of partial vaporization distillation (flash), while polymers and heavy metals are mostly removed? by decantation. However, the filled distillation column tends to become clogged due to the solid residues still contained in the oil to be fed into it.

Recently, the same Applicant filed an Italian patent application for a process which, starting from that of EP 0 618 959, provides for a centrifugation step of the oil to be regenerated between the distillation step by partial vaporization and the distillation step in filled column. The pressure inside the filled distillation column is regulated thanks to a liquid ring pump, obtaining a higher product. clean and a number of interventions to regenerate the distillation column pi? low.

WO2004 / 033 608 describes a process and a device for the treatment of waste oils, which provides for a preliminary separation by decantation of at least a fraction of water and a fraction of solid particles (sediments), a preliminary heating of the oily phase in output from the decanting phase and the centrifugal separation of the oil preheated to a temperature below the boiling point of water and the separation in this way of water and other pollutants. The product obtained, however, is not reused to produce new lubricating bases, but is fed to a combustion phase, together with other hydrocarbons and therefore its valorisation is not obtained.

WO96 / 00 273 describes a process of reclamation of used oils, with a view to their reuse. According to this document, the used oil is subjected as it is to a centrifugation to remove the solids; the oil at the outlet is then put in contact with diammonium phosphate and / or oxalic acid at a temperature between 60 and 85-90 ° C and is then subjected to a new centrifugation to separate oil and water. There are no distillation phases.

In all the processes just examined, next to the lubricant base - what? the product pi? valuable - you get quantities? important of bitumen and asphalt. This fraction is, in the aforementioned processes, of quality? not particularly high and pu? be sold only at relatively low prices and for simple uses, such as for the construction of paved roads.

Problem behind the invention? to propose a process for the regeneration of waste oils, which overcomes the aforementioned drawbacks and which allows a further enhancement of the process effluents. This purpose is achieved through a process for the regeneration of used oils, comprising a distillation phase by partial vaporization of the regenerated oil, a decantation phase of the heavy fraction, a distillation phase in a filling distillation column, which allows to produce a fraction of oil, to be sent to refining with hydrogen and a fraction of bitumen, characterized by ci? that the bitumen fraction is ground, the liquid fraction obtained after this grinding being collected as bitumen and the remaining solid fraction being recycled to the decanting stage. The subordinate claims describe preferential features of the invention.

Further characteristics and advantages of the invention are however better evident from the following detailed description of a preferred embodiment, given purely by way of non-limiting example and illustrated in the attached drawings, in which:

fig. 1? a block diagram illustrating the process according to the present invention;

fig. 2 ? a block diagram representing a part of the process according to the present invention, based on an alternative embodiment; And

fig. 3? a block diagram illustrating the process according to a second alternative embodiment.

How to ? said previously, a first embodiment of the process according to the present invention? represented as a block diagram in fig. 1. The oil to be regenerated comes from the pipeline 1. In this pipeline, the oil can? be mixed with an alkaline substance. A strong base is generally used, preferably KOH which has given the best results. Line 1 feeds the oil to be regenerated to a distillation column 2 by partial vaporization. The pressure inside column 2 is kept at about 250 torr and the temperature? slightly above the boiling temperature of water, preferably around 130-140? C. In column 2 we have cos? the vaporization of a substantial part of the water contained in the oil, partly coming directly from the used oil, partly fed into 1 as a solvent of the basic substance. The vaporized water comes out of a drain 3. The oil, which still contains a minor part of water, together with other impurities mostly? solid, comes out of the pipeline 4 and is fed cos? to a decanter 5. In fig. 1? was represented only one decanter 5, but the skilled in the art can? find practical reasons for providing two or more, without thereby departing from the scope of protection of the present invention. In the decanter there is the further separation of the oil from the water and from a part of the solid particles contained in it. The fraction to be subjected to the subsequent phases leaves the decanter 5 through the duct 6. The latter feeds the oil to be treated to a heat exchanger 7, preferably an oven, which brings the oil temperature to values higher than 300? C, preferably at values between 350? and 400? C, feeding it cos? to a filling distillation column 8. In it, some useful fractions are separated, transported respectively by pipelines 9, 10, 11 and 12 to a reactor 13 where the oil is refining with hydrogen, thus obtaining? the lubricating bases that come out of the system at 14.

Column 8 also leaves a bituminous tail fraction which, in the processes according to the known technique, is usually sold directly as bitumen. According to the present invention, however, the bituminous fraction exits from the bottom of the column 8 and, through the duct 15, is fed to a mixer 16 to homogenize it. From mixer 16, an outlet 17 feeds the mixed fraction to a unit? 18 grinding. The unit 18 can be any kind of grinding device. In particular, a ball mill is preferred, but wedge mills, disc shredders and others can also be used.

The unit 18 shreds the solid particles contained in the bitumen, opening them and making it so? other oil to be regenerated is available. Do you get a bigger part? liquid and a part that remains more? solid. From the unit? 18 there are two exits. An outlet 19, from which the liquid part of the product comes out, substantially a bitumen pi? liquid and containing fewer solid impurities than that present in the pipe 15 and therefore of more value? tall; and an exit 20, from which the fraction pi? solid, containing, among other things, the particles opened in the grinding phase with the oil to be regenerated. The outlet 20 carries the solid fraction back to the decanter 5, where it mixes with the flow of oil leaving the column 2 and starts the process again, releasing more oil for regeneration. In this way, the yield of the process rises, allowing to obtain a quantity? greater of lubricant base (valuable fraction), up to 67-70% by weight, and quantity? less fuel and bitumen (poorer fractions).

In fig. 2 ? shown the block diagram of an alternative embodiment of the present invention. Elements identical to those of fig. 1 are indicated with the same reference numbers.

The streams 9, 10, 11 and 12, leaving the filling distillation column 8 are fed to a tank 21 which acts as a buffer, to allow subsequent operations to be carried out discontinuously, by batches or by campaigns. From tank 21, a pipeline 22 leads to a unit? 23 of microfiltration, type of per s? known. A flow 24 carries the liquid fraction to the reactor 13 to carry out the refining with hydrogen and to withdraw the lubricating base produced through the outlet 14.

A pipe 15 which carries the bituminous fraction also exits from the filling distillation column 8. This flow is also joined by that carried by pipeline 25, leaving the unit? 23 of microfiltration, from which it removes the sediments separated in the microfiltration phase.

Again, pipeline 15, which one? together with the pipe 25, they transport the bituminous fraction, containing solid sediments, to the mixer 16 and from here, through the pipe 17, to the unit? 18 grinding. How already? in the case illustrated in fig. 1, also here the pipeline 19 transports and discharges bitumen, plus? higher than that obtainable according to the known art, while the duct 20 recycles the solid and ground part at the first stages of the process according to the present invention, pushing to higher levels? high yield to lubricating bases.

On the basis of this embodiment, in addition to the increase in the valuable products and the greater value of the poor products, a greater cleanliness of the fraction fed to the reactor 13 is also obtained. that the catalyst used in this phase has a net lengthening of its useful life; since, although? used in small quantities, catalysts for refining with hydrogen are normally based on precious metals, there is a certain cost saving, increased by the fewer interruptions in operation due to the replacement of the catalyst.

In fig. 3? shown the block diagram of a further alternative embodiment. Again, the stages already? described in relation to fig. 1 will carry the same reference numerals and will not be described further. This embodiment depends on a patent application recently filed by the same Applicant.

The oil to be treated, coming out through the duct 4 from the distillation column 2 by partial vaporization, is divided into two streams 4A and 4B, which feed respective decanters 5A and 5B, completely similar to the decanter 5 described in relation to fig. 1. The fraction to be regenerated leaves the decanters 5A, 5B through the pipes 26A, 26B and is fed to centrifugal separators 27A, 27B. The part still to be treated (oil to be regenerated) is carried by the pipes 28A, 28B, which then meet in the pipe 28, to a decanter 29. The useful fraction leaving the decanter 29 is then fed to the heat exchanger 7, usually a oven, from which it is brought to a temperature above 300? C, typically between 350? and 400? C. The fraction is then fed to the filling distillation column 8. Column 8 is managed in such a way as to have a tail pressure between 8 and 15 torr and a head pressure between 2 and 7 torr. to take the best product. According to a preferred embodiment, the pressure is regulated, instead of? by the ejectors commonly used for this purpose, by a liquid ring pump. In this way, in addition to saving on costs related to steam and not having the management of a dedicated steam cycle, you have greater regularity? in the flows and in the pressure, compared to what? that could previously be achieved with ejectors.

From column 8 the flows of useful product leave, through the pipes 9, 10, 11 and 12, which go to the subsequent refining phase with hydrogen, in the reactor 13; the lubricating bases produced are taken from the reactor 13, through the pipeline 14. If the liquid ring pump is used to regulate the pressure inside the column 8, the fraction fed to the reactor 13? particularly clean and there is a net lengthening of the life of the catalyst contained in the reactor 13.

The tail flow also exits from column 8 through pipeline 15. To this flow, containing the bituminous fraction, are also joined flows 30 and 31, leaving the centrifugal separators 27A, 27B and containing the solid sediments separated from the oil being regenerated .

The pipe 15 carries the bituminous fluid to the mixer 16 and from here, through the pipe 17, to the unit? 18 grinding.

The liquid fraction obtained after grinding is taken from pipeline 19 and sold.

The fraction pi? solid is taken from the conduit 20, which is divided into two streams 20A, 20B, which respectively feed the decanters 5A, 5B.

The two alternative embodiments described last can also be advantageously combined with each other.

The present invention also refers to a plant for implementing the process described above. The plant? of the type comprising a distillation column 2 by partial vaporization, a number of decanters 5 or 5A, 5B, a distillation-filled column 8 and a refining reactor 14 with hydrogen, characterized by this? which also includes a unit? 18 for grinding the bituminous fractions and any process sediments. Normally, the unit? 18 of grinding? consisting of a ball mill.

According to an alternative embodiment, the plant according to the present invention also comprises centrifugal separators 27A, 27B and the filling distillation column 8 comprises a liquid ring pump.

Advantageously, the plant according to the present invention also comprises a unit? 23 of microfiltration.

The bituminous fraction that leaves the process through the pipe 19 has improved characteristics with respect to that obtained from the regeneration processes of used oils according to the prior art. In particular, this bitumen - thanks also to its carbon black content -, as well as for the common uses for which bituminous fractions are used, such as the preparation of roads and the like,? also suitable for more uses? nobles. If this bitumen is mixed with polythene (for example, low density polythene) or with polypropylene, for example making 10% bitumen and 90% polymer mixtures, it can? be used for creating masterbatches. For example, you can? easily obtain a film with a thickness of about 60? m.

In addition, such bitumen can? be used for the production of inks, such as, for example, heatset or coldset inks.

The process and the plant according to the present invention allow to obtain a higher yield. high in lubricating bases (as we have seen, it goes from 60% by weight to about 67-70% by weight), increasing the valorisation of the starting waste and reducing process waste. This enhancement is further increased by the fact that, how can it be? seen, even the least valuable product - bitumen - is ennobled.

It is understood, however, that the invention must not be considered limited to the particular arrangement illustrated above, which constitutes only an exemplary embodiment thereof, but that various variants are possible, all within the reach of a person skilled in the art, without however exit from the protection scope of the invention itself, as defined by the following claims.

LIST OF REFERENCE CHARACTERS

1 Pipeline

2 Distillation column for partial vaporization 3 Discharge (of 2)

4 Pipeline (of 2)

5 Decanter

5A Decanter

5B Decanter

6 Pipeline

7 Heat exchanger

8 Filled distillation column

9 Pipeline

10 Pipeline

11 Pipeline

12 Pipeline

13 Reactor

14 Exit (of 13)

15 Pipeline

16 Mixer

17 Exit (of 16)

18 Units of grinding

19 Outlet (of 18) liquid product

20 Output (of 18) solid fraction

21 Tank

22 Pipeline

23 Units microfiltration

24 Flow

25 Pipeline

26A Pipeline

26B Pipeline

27A Centrifugal separator

27B Centrifugal separator

28 Line 28A Line 28B Line 29 Decanter

Claims (9)

CLAIMS 1) Process for the regeneration of used oils, comprising a distillation phase by partial vaporization of the regenerated oil, a decantation phase of the heavy fraction, a distillation phase in a filling distillation column, which allows to produce an oil fraction , to be sent to refining with hydrogen and a fraction of bitumen, characterized by ci? that the bitumen fraction is ground, the liquid fraction obtained after grinding being collected as bitumen and the remaining solid fraction being recycled to said decanting phase of the heavy fraction. 2) Process as in 1), characterized by ci? that said step of grinding of the bituminous fraction? preceded by a mixing phase. 3) Process as in 1) and in 2), characterized by ci? that ? a microfiltration step is provided for the product leaving the distillation step in the filled column, the sediment of which is sent to said grinding step. 4) Process as in any of the preceding claims, characterized by that? that before said filling column distillation step? provided for a phase of centrifugal separation and from there? that the pressure inside said filling distillation column? regulated by a liquid ring pump. 5) Plant for setting up a process according to any one of the preceding claims, comprising a distillation column (2) by partial vaporization, a certain number of decanters (5; 5A, 5B), a distillation column (8) filling and a hydrogen refining reactor (14), characterized by ci? which also includes a unit? (18) grinding of bituminous fractions and any process sediments. 6) Plant as in 5), characterized by ci? that the unit? (18) of grinding? consisting of a ball mill. 7) Plant as in 5) or in 6), characterized by there? which also includes centrifugal separators (27A, 27B). 8) Plant as in 7), characterized by ci? that the fill distillation column (8) comprises a liquid ring pump. 9) Plant as in any one of claims 5) to 8), characterized by that? which also includes a unit? (23) of microfiltration.