MXPA00009643A - Process for moving highly viscous residues deriving from oil processing - Google Patents

Abstract

Process for recovering and moving refinery tar by the formation of oil in water dispersions of the above tar, the above dispersions having a water content of at least 20%by weight, and the dispersing agent being selected from salts of alkaline metals and ammonium, and relative mixtures, of the condensates of naphthalenesulfonic acid with formaldehyde, which comprises:a) fluidification of the tar by heating to a temperature at least equal to its softening point;b) mixing the tar thus fluidified with the desired quantity of water and dispersing agent until an oil in water dispersion is formed;c) recovery and moving of the tar in the form of the oil in water dispersion formed in step (b).

Description

PROCESS FOR MOVING HIGHLY VISCOSES WASTE DERIVED FROM THE PROCESSING OF OIL DESCRIPTION OF THE INVENTION The present invention relates to a process for moving petroleum residues (tar) having a softening point greater than 80 ° C. More specifically, the present invention relates to a process for moving petroleum tar through of the formation of aqueous dispersions, in the presence of particular dispersing agents, of the above tar. The term "petroleum tar" refers to petroleum residues that have a softening point greater than 80 ° C, usually greater than 100 ° C. Typical examples of this petroleum tar are residues from the vacuum distillation of petroleum. crude, or other petroleum fractions (for example, from the distillation residue at atmospheric pressure), and residues from the viscosity separation by pyrolysis. At present, the above tar is moved and recovered by dilution with lighter hydrocarbon fractions, until diesel is obtained.

This process has the obvious disadvantage of having to use huge quantities of fractions of hydrocarbons with a higher value, to obtain a lower quality product. The patent literature describes various processes for moving viscous crude oils or viscous petroleum fractions, which, however, as far as the properties are concerned, are not compatible with refinery tar. One of the most widely studied methods for moving viscous crude oils is the formation of oil-in-water (O / W) emulsions, in which the external phase (water) is less viscous than the internal phase (petroleum). These emulsions, prepared by mixing, with stirring, water, emulsifying agent and oil, can be easily moved. As they have a low viscosity, these emulsions must also have a certain stability, that is, they must not be separated into two phases when transported, and during their possible storage. In addition, the emulsification additives should allow the formation of emulsions with a high content of the petroleum phase. Regardless of these characteristics, a fundamental requirement for the use of this technique is the low cost of emulsifying agents. The emulsification agents proposed in the patent literature do not meet these requirements. For example, US-A-4, 246, 920, US-A-4, 285, 356, US-A-4, 265, 264 and US-A-4, 249, 554 describe emulsions having an oil content of only 50%; this means that under these conditions, half of the available volume (for example of a pipeline) is not available to transport oil. Canadian patents 1,108,205; 1,113,529; 1,117,568 and US-A-4, 246, 919, on the other hand indicate rather limited decreases in viscosity, despite the presence of a low oil content. US-A-4, 770, 199 discloses the use of emulsifying agents consisting of complex mixtures of non-ionic alkoxylated surface active agents and ethoxylated-propoxylated carboxylates. The nonionic active surface agent of this mixture is obviously sensitive to temperature, and can consequently become insoluble in water under certain temperature conditions, reversing the phases, ie from O / W to W / O. The phase inversion can also be caused by high shear values during the movement operation. The surface active agents above, on the other hand, are extremely expensive and contribute to considerably increase the costs of the process. Finally, again in the field of O / W emulsions, EP-A-237,724 describes the use of mixtures of ethoxylated carboxylates and ethoxylated sulfates, products that are not readily available in the market. Contrary to these documents, WO-94/01684 solves the problem of moving viscous crude oils by the formation of O / W dispersions obtained with the aid of dispersion agents injected into the oil wells. With respect to the usual surface active agents, the dispersing agents are sulfonates which are extremely soluble in water, and do not greatly reduce the surface tension of the water. All these documents however do not describe the movement of refinery tar (a material that is very different from viscous crude oils) by means of the formation of O / W dispersions. Now a process has been found that allows a more qualified use of refinery tar. Accordingly, the present invention relates to a process for recovering and moving refinery tar through the formation of petroleum dispersions in tar water from above, the above dispersions have a water content of at least 20% by weight, preferably greater than 25% by weight, even more preferably from 28% to 32% by weight, and the dispersing agent is selected from alkali metal and ammonium salts, and their relative mixtures, from naphthalenesulfonic acid condensed materials with formaldehyde, comprising: a) fluidization of the tar by heating to a temperature at least equal to its softening point; b) mixing the tar fluidized in this manner with the desired amount of water and dispersing agent until a petroleum dispersion is formed in water: c) recovery and movement of the tar in the form of the oil dispersion in water formed in the stage (b) With respect to the dispersing agents, these are particular additives with the following characteristics, in which they differ from the usual surface active agents: high solubility in water (usually at 20 ° C over 15% by weight); limited decrease in surface tension in water (usually at a concentration d 1% in water, the surface tension decreases by a maximum of 10%). From a chemical chemistry point, the dispersing agents which may be used in the process of the present invention are alkali or ammonium salts of polymeric sulfonates which are derived from the condensation of naphthalenesulfonic acid with formaldehyde. With regard to dispersion agents, these are products or product mixtures that promote the formation of a dispersion, or stabilize a dispersion, without significantly altering the interfacial tension between water and oil. In the process of the present invention, the term "dispersion" refers to a multi-phase system, in which one phase is continuous and at least one is finely dispersed. In the dispersions formed according to the process of the present invention, the continuous phase is water, while the dispersed phase, more or less finely distributed, consists of particles, either solid or liquid, of refinery tar. The dispersing agents promote and stabilize the dispersions formed in this manner. As can be seen in the experimental part, the alkaline-earth metal sulphonates are not effective, but only the sulfonates of alkali metals and ammonium, preferably of sodium. Step (a) of the process of the present invention consists of fluidizing the tar, usually by heating at least to its softening point. Once fluidized, the tar is contacted with water and the dispersing agent, preferably with an aqueous solution of the dispersing agent. The weight ratio between the tar and the water can vary within a wide range, for example between 90/10 and 10/90. It is preferable, however, for obvious economic reasons, to use other tar contents, which may however cause the drawback of excessive viscosity. The amount of dispersing agent also depends on the type of tar to be moved; in any case, the amount of dispersing agent needed to have a stable and fluid dispersion is in the range from 0.05 to 2.5% by weight, preferably from 0.3 to 1.5% by weight, the percentages refer to the amount of dispersing agent with respect to the total amount of water and petroleum tar. The contact between the tar and the aqueous solution of the dispersing agent can be carried out, either batchwise or continuously, directly in the plant in which the tar is formed, or in any storage location of the above tar. The contact between the aqueous solution of the dispersing agent and the tar can be facilitated by stirring devices, such as agitators, centrifugal pumps and turbines. Once the dispersion has been formed (this can easily be confirmed by observing the decrease in the viscosity of the system), it can be easily transported by pumped to the storage sites or for the final use (for example directly in combustion). The following examples provide a better understanding of the present invention.

EXAMPLES The quantities of distilled water (FW) and additive calculated in relation to the type of dispersion to be produced are exactly weighed in a glass container. The additive, soluble in water, is homogenized by simple mechanical agitation. The heavy amount of tar, previously heated in a water bath or in an oven at 80-130 ° C, is added to the aqueous solution. The glass container, which contains the aqueous additive solution as the lower phase and the oil as the upper phase, is heated in a water bath at the pre-selected preparation temperature of the dispersion (40-95 ° C). When the desired temperature has been reached, the mixture is subjected to mechanical agitation (Ultraturrax type UT45, equipped with a single turbine at a constant speed of 10,000 rpm) for the desired time (2 to 5 minutes): the Ultraturrax turbine is placed, for its activation, in the aqueous phase. The dispersion produced is allowed to stand for about 24 hours and analyzed in terms of viscosity at 25 ° C. The above viscosity measurements are made using an RFSII rheometer, with a rheometer geometry, from Rheometrics. The following tables, under the viscosity point, indicate two values, both in MPa, at 24 hours after the start of the preparation of the dispersion, the first corresponds to 10 sec "1, the second to 100 sec" 1. The stability of the aqueous solutions is determined by calculating the separated water during a period of time with respect to the dispersed? total.

The tables indicate the stability as a measure of the percentage of water separated after 27 days with respect to the total weight of the dispersion. With respect to the dispersing agents used, the symbol R5 is related to Rheobuild ™ 5,000 of M.A.C., namely sodium salt of condensed naphthalene sulfonic acid with formaldehyde, which has a molecular weight of 4.304; the symbol Rl is related to Rheobuild ™ 1,000 of M.A.C., that is to say calcium salt of condensed naphthalene sulfonic acid with formaldehyde, having a molecular weight of 3,390; the symbol D4 is related to NNMSHMR 40 of Great, that is to say to an ethoxylated nonylphenol having a molar ratio between ethylene oxide and nonyl phenol of 5.18. Table 1 indicates the tests performed using a pyrolysis viscosity separation tar with initials 6B2 VSB load RA 673 having the following characteristics: Fe 53 mg / kg, Na 16 mg / kg, Ni 70 mg / kg, V 238 mg / kg; RCC: 16.2 weight / weight%, S: 2.71 weight / weight%. Table 2 on the other hand indicates the tests performed using a vacuum residue with initials SZRN / 02 having the following characteristics: Fe 73 mg / kg, Na 25 mg / kg, Ni 129 mg / kg, V 390 mg / kg; RCC: 29.0 weight / weight%, S: 3.62 weight / weight%.

Finally, Table 3 indicates the tests performed using a tar with initials ATZ RV, which had the following characteristics: Fe 49 mg / kg, Na 23 mg / kg, Ni 81 mg / kg, V 236 mg / kg; RCC: 28.3 weight / weight%, S: 4.38 weight / weight%. In the tables above, the viscosity is expressed in MPa. The first data refer to the viscosity at 10 cm "1, the second data at the viscosity at 100 c" 1. The stability is expressed in the% of water separated after 27 days of rest.

Table 3

Claims (5)

1. RE IVINDICATIONS 1. A process for recovering and moving refinery tar by the formation of oil dispersions in tar water from above, the above dispersions have a water content of at least 20% by weight, and the dispersing agent is selected from alkali metal and ammonium salts, and relative mixtures of the condensed mater of naphthalenesulfonic acid with formaldehyde, comprising: a) fluidization of the tar by heating to a temperature at least equal to its softening point; b) mixing the tar fluidized in this manner with the desired amount of water and dispersing agent until a petroleum dispersion is formed in water; c) recovery and movement of the tar in the form of the oil dispersion in water formed in step (b).
2. 2. The process according to claim 1, wherein the water content of the dispersion is greater than 25% by weight.
3. 3. The process according to claim 2, wherein the water content of the dispersion is in the range from 28% to 32% by weight.
4. 4. The process according to claim 1, wherein the dispersing agent is selected from alkali metal salts of the condensed mater of naphthalenesulfonic acid with formaldehyde.
5. 5. The process according to claim 4, wherein the dispersing agent is selected from sodium salts of the condensed mater of naphthalenesulonic acid with formaldehyde.