METHOD FOR TREATING HEAVY HYDROCARBON RESIDUES CONTAINING CALCIUM AND OTHER HEAVY METALS AND PRODUCT OBTAINED

Abstract

 The method envisages the involvement of any industrial mixer (8) to which an aqueous solution (1) of an oxoacid of the chalcogens with an oxoacid of the pnictogens and an aromatic sulfonic acid or mixtures (2) thereof are added and they are mixed with the heavy fraction (3) or hydrocarbon residue to be treated, such that this mixture is heated by way of any conventional heating system (9) to a temperature comprised between 20 and 100°C and once the reaction is carried out, the resulting product is forced to pass to a decanter or centrifuge machine where the separation step (4) of the organic phase (5) from the aqueous phase (6) takes place.
An organic phase used directly as a fuel (7) which contains at least 0.5% by weight of polymeric solids and the viscosity thereof is below 100 mm²/s at 50°C is thereby obtained.

Description

OBJECT OF THE INVENTION

[0001] The present invention relates to a method for treating heavy hydrocarbon residues containing calcium and other heavy metals such as for example the rejected materials associated with the consumption of fuel oil in engines, in order to purify said residues and obtain a fuel as a result of applying said method.

BACKGROUND OF THE INVENTION

[0002] Heavy fuel oil is a complex combination of hydrocarbons, sulfur compounds and organometallic compounds obtained as the residue of cracking processes in refineries. This finished fuel consists of saturated hydrocarbons with carbon numbers predominately in the range C15-C50.

[0003] In the prior preparation of this fuel for use thereof in fuel oil engines and given that it usually has the presence of water and sediment, it is essential to carry out a preparation step before injecting it into the engine.

[0004] This preparation is carried out by means of vertical plate separators. The fuel is supplied to the separators which continuously generate an already purified fuel and also a residue consisting of the water and the sediments which are intended to be removed from the fuel oil and which are mixed with abundant fuel residues.

[0005] Aside from this main flow of residue, the flow coming from the purging and cleaning of the preparation circuit must be added, including the filters prior to injection as well as the detergents and other cleaning products in the machine hall. Sometimes, the oil used and generated in the periodic oil changes of the engine is added to this residue.

[0006] A possible use of this fuel is as a fuel. However, the high content of metals and other impurities makes it difficult to use due to the high level of emissions (in an increasingly more restrictive environment), high wear in injection systems, as well as the increased solid residue following combustion. The fuel obtained by means of this process poses serious stability problems as is reflected in the accelerated ageing tests.

[0007] The technique of treating hydrocarbon residues is described, for example, in the patents numbered WO201421368, WO2007149292, WO2011014686, WO2011143770, US20050234284, WO2014121368, WO2011143770, GB299925 and US2434528. Some of these describe a process for reducing the content of water and sediments by means of decantation treatment and subsequent centrifugation. The separation method is similar to separation by gravity. The driving force is greater as it is a result of the rotation of the liquid: in the case of sedimentation where the driving force is the result between the differences in density of the solid and liquid particles, separation is achieved with a force in the order of 1000 to 20000 times greater than gravity. The residue separates in an aqueous phase a solid phase containing the very heavy impurities and a phase with little water and sediments. This is also subjected to a centrifugation treatment and a subsequent filtering before it can be used as a fuel.

[0008] The process previously mentioned has the disadvantage of not removing the contaminant compounds whose densities are not sufficiently different since they do not achieve terminal sedimentation velocity of the particle in the centrifugal field.

[0009] There is also an extensive bibliography of patents mentioned for decontamination of used lubricating oils and the recycling thereof to recover the base lubricants obtained as subproducts or residues (depending on the treatment) from the fuel fraction process. In some of these processes, the use of sulfuric or phosphoric acid is mentioned as part of the pretreatment of the oil to reduce the content of metals. These treatments are effective as a step prior to heat treatment and do not resolve, by themselves, neither the stability problems nor the acidity problems of the resulting flow, both parameters being critical for fulfilling any quality regulation for the fuel. These heat treatments, on the other hand, despite being very effective for decontaminating the lubricating oils used and residues with similar characteristics, are not effective for the residues of the purification of the fuel oil. A product obtained from the sources of the distillation columns of the refineries and which could only be "treated" with heat at greater depth by means of coke units to produce middle distillates and coke.

[0010] There is also bibliography on the use of carboxylic acids for the removal of Na, being very effective at reducing Na, but not at reducing the rest of the contaminants that remain in the treated product at levels greater than those permitted in spite of repeated iterations of the treatment.

[0011] In this way, there is still a need for a method effective at eliminating calcium and other heavy fraction contaminants containing calcium and other contaminants and producing fuel which meets the international standard ISO 8217 Table 2 and which avoids the mentioned drawbacks.

DESCRIPTION OF THE INVENTION

[0012] The object of the present invention is a method for eliminating calcium and other heavy fraction contaminants which they contain, resulting from the purification of heavy fuel oil used as a fuel in ship and cogeneration engines, the method comprising:
Mixing an aqueous solution of an oxoacid of the chalcogens with an oxoacid of the pnictogens and an aromatic sulfonic acid or mixtures thereof; with the heavy fraction at a temperature comprised between 20 and 100°C and the separation of the organic phase from the aqueous phase.

[0013] Obtaining an organic phase directly used as a fuel which contains at least 0.5% by weight of polymeric solids and the viscosity thereof is below 100 mm²/s at 50°C.

[0014] The main source of the residue to be treated is the centrifuges at the head of the heavy fuel systems of the ship engines. With the aim of protecting the engine and extending the useful life thereof, in addition to avoiding faults in the same, and due to the particularities of the fuel used, it is necessary to use this purification step prior to the injection of the fuel into the engine. The fuels primarily used are summarized in Table 2 of ISO 8217, although the fuels in cogeneration engines, where there the casuistry is used, are regulated by national legislation.

[0015] The use of chalcogens is very effective at eliminating metals, the use of pnictogens and aromatics prevents secondary effects such as the polymerisation of unsaturated compounds which solidify and make their post treatment difficult. The method of the present invention provides, as a result, a heavy fraction with low viscosity. The solid material eliminated by means of separation is less than 0.5% by weight of the total heavy oil fraction.

[0016] The acid mixture is also advantageous since it allows high flexibility and reliability, necessary due to the high variability of the original residue owing to its nature.

[0017] The heavy fraction low in metals is characterised by a low viscosity and by the absence of a relevant quantity of polymeric solids (below 0.5% by weight). The absence of metals is a very significant achievement since it allows the direct use of the fuel without subjecting the heavy fraction to other treatments, for example, passing through a fuel reduction unit or coke unit.

[0018] The low viscosity of the product obtained means there is less need for heating to bring the fuel to the viscosity range for optimal injection with the energy saving which this entails and the consequently positive impact for the environment.

[0019] The chalcogenic acids used according to the present invention are 3 and 4 period acids. Those of period 3 have between 1 and 2 sulfur atoms or mixtures thereof. In one embodiment, the acid is selected from the list: sulfur dioxide hydride hydroxy acid, sulfur dioxide dihydroxy acid, heptaoxo disulfuric acid or pyrosulfuric acid, trioxoselenic acid, heptaoxo diselenic acid and sulfur oxide hydride hydroxy acid or mixtures thereof.

[0020] The pnictogen acids used are of period 2 and 3. They contain between 1 and 2 nitrogen or phosphorus atoms or mixtures thereof.

[0021] The acid is preferably selected from the list: nitrogen dioxide hydroxy acid, nitrogen oxide hydroxy acid, phosphorus oxide trihydroxy acid, phosphorous oxide hydride dihydroxy acid, phosphorous trihydroxy acid, phosphorous hydride dihydroxy acid and phosphorus oxide dihydride hydroxy acid or mixtures thereof.

[0022] The importance of the use of aromatics in the acid mixture is to prevent the aggregation of the asphaltenes, mainly formed by aromatic rings linked to alkyl and cycloalkane chains, in addition to heterocyclic compounds which have N, S and O and the subsequent deposition thereof. The aromatic acids used according to the present invention are sulfonic acids. Aromatics, preferably the acid selected from the list: phenylsulfonic acid or benzenesulfonic acid, 1-phenanthrene sulfonic acid, p-methyl benzenesulfonic acid, p-phenolsulfonic acid, 2-hydroxy benzenesulfonic acid and o-phenolsulfonic acid or mixtures thereof.

[0023] The aqueous solution of the acid mixture as well as the proportion of each one varies, as a function of the composition of the residue to guarantee the final result, in a wide concentration range. However, it is preferable to use a solution in which the concentration of the acid is between 1% and 20% by weight.

[0024] The oxoacid formulation is carried out in a quantity that is normally at least stoichiometric with respect to the content of metals. In addition, the aromatic content contains heteroatoms.

[0025] The temperature of the treatment is generally comprised between 60°C and 85°C.

[0026] The heavy fraction and the aqueous solution of the acid formulation are mixed intensively for a period of time preferably comprised between a few minutes and a few hours, depending on the mixing device. Normally, a contact time comprising between 30 mins and 6 hours is sufficient for obtaining effective elimination of the metals. The mixture can be carried out when using any industrial mixer, for example a static mixture or agitation tank. After contact with the acidic mixture, the water and the organic phase are separated, according to the methods known in the art, for example using a decanter or a centrifuge machine.

[0027] The organic phase obtained after treatment with the acid mixture is characterised not only by a very low level of solids, but also by a small quantity of ashes and by a low viscosity.

[0028] The quantity of ash is preferably less than 0.1% w/w.

[0029] The viscosity at 50°C of the organic phase after the treatment is preferably less than 100 mm²/s, more preferably less than 80 mm²/s.

[0030] In one aspect of the invention, it is advantageous for the viscosity at 50°C of the organic phase to be below 100 mm²/s.

DESCRIPTION OF THE DRAWINGS

[0031] In order to complement the description being made and with the object of helping to better understand the characteristics of the invention, in accordance with a preferred practical exemplary embodiment thereof, said description is accompanied, as an integral part thereof, by a set of plans where, in an illustrative and non-limiting manner, the following has been represented:

Figure 1 shows a schematic diagram of an installation for implementing the method for treating heavy hydrocarbon residues containing calcium and other heavy metals object of the invention.

PREFERRED EMBODIMENT OF THE INVENTION

[0032] In view of the described figure, it can be observed how in the process of the invention, the involvement of any industrial mixer (8), for example a static mixer or an agitation tank, has been envisaged.

[0033] In said tank or industrial mixer (8) an aqueous solution (1) of an oxoacid of the chalcogens with an oxoacid of the pnictogens and an aromatic sulfonic acid or mixtures (2) thereof are added and they are mixed with the heavy fraction (3).

[0034] This mixture is heated by way of a conventional heating system (9) to a temperature comprised between 20 and 100°C.

[0035] Once the reaction has been carried out, the resulting product is forced to pass to a decanter or centrifuge machine, where the separation step (4) of the organic phase (5) from the aqueous phase (6) takes place.

[0036] In this way, an organic phase directly used as a fuel (7) is obtained which contains at least 0.5% by weight of polymeric solids and its viscosity is below 100 mm²/s at 50°C.

[0037] In turn, the aqueous phase (6) will be subjected to a physiochemical treatment process in order to separate the water (11) from the sludge (12) present in said mixture.

[0038] As has been mentioned previously, the oxoacid of the chalcogens is selected from the group formed by: sulfur dioxide hydride hydroxy acid, sulfur dioxide dihydroxy acid, heptaoxo disulfuric acid or pyrosulfuric acid, trioxoselenic acid, heptaoxo diselenic acid and sulfur oxide hydride hydroxy acid or mixtures thereof.

[0039] In turn, the pnictogen acids are selected from the group formed by: nitrogen dioxide hydroxy acid, nitrogen oxide hydroxy acid, phosphorus oxide trihydroxy acid, phosphorous oxide hydride dihydroxy acid, phosphorous trihydroxy acid, phosphorous hydride dihydroxy acid and phosphorus oxide dihydride hydroxy acid or mixtures thereof.

[0040] In terms of the aromatic acids, they are selected from the group formed by: phenylsulfonic acid or benzenesulfonic acid, 1-phenanthrene sulfonic acid, p-methyl benzenesulfonic acid, p-phenolsulfonic acid, 2-hydroxy benzenesulfonic acid and o-phenolsulfonic acid or mixtures thereof.

[0041] In terms of the organic phase, after the mixing step in the industrial mixer (8), said phase constitutes the upper phase, the acid concentration in water being comprised between 1 and 20% by weight, while its temperature comprised is between 60°C and 90°C.

PRACTICAL EXAMPLES

[0042] The fuel, after and before the treatment was characterised by using the following methods: the content of metals was measured using an atomic absorption spectrometer after diluting the fuel in a mixture of light distillates, all the metal content was expressed in a percentage in weight/weight. The kinematic viscosity was measured using the suitable viscometer submerged in an oil bath at 50°C and is expressed in mm²/s. The ash content was determined by means of complete calcination of the sample at 800°C for a minimum of 15 hours and is expressed in percentage by weight/weight (w/w). The possible polymer solid formation by means of filtration of the mixture at 100°C was inspected using a filter with a pore size of 1.6 micrometres.

Comparative example 1

[0043] A heavy fraction rich in metals obtained from a representative residue mixture was characterised obtaining an ash content (solid residue after calcination at 800°C) of 1.35% w/w and a viscosity of 90 mm²/s at 50°C. The method of the treatment was the following: the heavy fraction (100 g) was heated to a temperature of 90°C and a solution of sulfur oxide hydride hydroxy acid was added in water (25 g, 8% w/w) and was mixed at 90°C for fifteen minutes. The mixture was then centrifuged at 4,500 rpm for 5 minutes and the two phases (organic and aqueous) were separated. The organic phase was separated in the upper fraction and was characterised by obtaining an ash value of 0.05% w/w and a viscosity value of 78 mm²/s at 50°C. In this case, the presence of a solid polymeric phase was observed at the bottom of the centrifuge tube, considerably above 1%.

Comparative example 2

[0044] Example 1 was repeated using a phosphorus hydride dihydroxy acid solution (25 g, 10.5% w/w). The organic phase was separated in the upper fraction. The ash content of the final organic phase was 0.16% w/w and the viscosity at 50°C of the final organic phase was 80 mm²/s. In this case, the presence of a solid polymeric phase was observed at the bottom of the centrifuge tube, considerably above 1%.

Comparative example 3

[0045] Example 1 was repeated using a p-methyl benzenesulfonic acid (25 g, 7.5% w/w). The organic phase was separated in the upper fraction. The ash content of the final organic phase was 1.1% w/w and the viscosity at 50°C of the final organic phase was 80 mm²/s. The mixture was filtered without problem and the quantity of solid retained in the filter was less than 0.5% w/w.

Comparative example 4

[0046] Example 1 was repeated using a sulfur oxide hydride hydroxy acid, phosphorus hydride dihydroxy acid and p-methyl benzenesulfonic acid (25 g, 12% w/w). The organic phase was separated in the upper fraction. The ash content of the final organic phase was 0.5% w/w and the viscosity at 50°C of the final organic phase was 75 mm²/s. The mixture was filtered without problem and the quantity of solid retained in the filter was less than 0.5% w/w.

Comparative example 4A

[0047] Example 4 was repeated using 12.5 g of a mixture of sulfur oxide hydride hydroxy acid, phosphorus hydride dihydroxy acid and p-methyl benzenesulfonic acid (21% w/w). The organic phase was separated in the upper fraction. The ash content of the final organic phase was 0.02% and the viscosity at 50°C of the final organic phase was 78 mm²/s. The mixture was filtered without problem and the quantity of solid retained in the filter was less than 0.5% w/w.

Comparative example 4B

[0048] Example 4 was repeated using 50 g of a mixture of sulfur oxide hydride hydroxy acid, phosphorus hydride dihydroxy acid and more diluted p-methyl benzenesulfonic acid (2.6% w/w), heating the mixture to 60°C. The organic phase was separated in the upper fraction. The ash content of the final organic phase was 0.035% and the viscosity at 50°C of the final organic phase was 80 mm²/s. The mixture was filtered without problem and the quantity of solid retained in the filter was less than 0.5% w/w.

Comparative example 4C

[0049] Example 4 was repeated using a temperature of the mixture of 25°C. The organic phase was separated in the upper fraction. The ash content of the final organic phase was 0.6% and the viscosity at 50°C of the final organic phase was 85 mm²/s. In this case, the presence of a solid polymeric phase was observed at the bottom of the centrifuge tube, considerably above 1%.

Example 5

[0050] Example 1 was repeated using a solution of 1-phenanthrene sulfonic acid, sulfur oxide dihydroxy acid and phosphorus hydride dihydroxy acid and benzenesulfonic acid (25 g, 12.5% w/w). The organic phase was separated in the upper fraction. The ash content of the final organic phase was 0.05% w/w and the viscosity at 50°C of the final organic phase 5 was 80 mm²/s. The mixture was filtered without problem and the quantity of solid retained in the filter was less than 0.5% w/w.

Example 6

[0051] Example 1 was repeated using a solution of sulfur dioxide dihydroxy acid, phosphorus oxide trihydroxy acid and benzenesulfonic acid (25 g, 10% w/w). The organic phase was separated in the upper fraction. The ash content of the final organic phase was 0.20% w/w and the viscosity at 50°C of the final organic phase was 85 mm²/s. The mixture was filtered without problem and the quantity of solid retained in the filter was less than 0.5% w/w.

Example 7

[0052] Example 1 was repeated using a solution of phosphorus trihydroxy acid, sulfur oxide hydride hydroxy acid and 1-phenanthrene sulfonic acid (25 g, 11.5% w/w). The organic phase was separated in the upper fraction. The ash content of the final organic phase was 0.06% w/w and the viscosity at 50°C of the final organic phase was 80 mm²/s. The mixture was filtered without problem and the quantity of solid retained in the filter was 20 less than 0.5% w/w.

Claims

1. A method for treating heavy hydrocarbon residues containing calcium and other heavy metals which is intended for eliminating calcium and other heavy fraction contaminants from a residue resulting from the purification of heavy fuel oil used as a fuel in ship engines and cogeneration engines, characterised in that in the same method the following operative phases are defined:

• Mixing an aqueous solution (1) of an oxoacid of the chalcogens with an oxoacid of the pnictogens and an aromatic sulfonic acid or mixtures (2) thereof; with the heavy fraction (3) at a temperature comprised between 20 and 100°C,

• Separating (4) the organic phase (5) from the aqueous phase (6).

• Obtaining from said separation step (4) an organic phase directly used as a fuel (7)

2. The method for treating heavy hydrocarbon residues containing calcium and other heavy metals according to claim 1, characterised in that the oxoacids of the chalcogens are selected from the group formed by: sulfur dioxide hydride hydroxy acid, sulfur dioxide dihydroxy acid, heptaoxo disulfuric acid or pyrosulfuric acid, trioxoselenic acid, heptaoxo diselenic acid and sulfur oxide hydride hydroxy acid or mixtures thereof.

3. The method for treating heavy hydrocarbon residues containing calcium and other heavy metals according to claim 1, characterised in that the pnictogen acids are selected from the group formed by: nitrogen dioxide hydroxy acid, nitrogen oxide hydroxy acid, phosphorus oxide trihydroxy acid, phosphorous oxide hydride dihydroxy acid, phosphorous trihydroxy acid, phosphorous hydride dihydroxy acid and phosphorus oxide dihydride hydroxy acid or mixtures thereof.

4. The method for treating heavy hydrocarbon residues containing calcium and other heavy metals according to claim 1, characterised in that the aromatic acids are selected from the group formed by phenylsulfonic acid or benzenesulfonic acid, 1-phenanthrene sulfonic acid, p-methyl benzenesulfonic acid, p-phenolsulfonic acid, 2-hydroxy benzenesulfonic acid and o-phenolsulfonic acid or mixtures thereof.

5. The method for treating heavy hydrocarbon residues containing calcium and other heavy metals according to claims 1 to 4, characterised in that after the mixing step, the organic phase is the upper phase and the acid concentration in water is comprised between 1 and 20% by weight.

6. The method for treating heavy hydrocarbon residues containing calcium and other heavy metals according to claims 1 to 4, characterised in that after the mixing step, the organic phase is the upper phase, it being maintained at a temperature comprised between 60°C and 90°C.

7. A product obtained by means of the method of claims 1 to 6, characterised in that it consists of an organic phase usable as a fuel containing at least 0.5% by weight of polymeric solids and a viscosity below 100 mm²/s at 50°C.

Drawing