MXPA01001166A - Process for reducing total acid number of crude oil - Google Patents

Abstract

The instant invention is directed to a process for reducing organic acids in petroleum feeds containing organic acids comprising:(a) thermally treating a petroleum feed containing organic acids in a thermal reaction zone comprising a plurality of stages in series, at a temperature and pressure sufficient to decompose at least a portion of said organic acids while sweeping said plurality of stages with an inert gas, to produce a volatile organic acid containing hydrocarbon fraction and a non-volatile hydrocarbon fraction;(b) treating said volatile hydrocarbon fraction to neutralize at least a portion of said organic acids therein and to produce a treated volatile hydrocarbon fraction;(c) collecting said non-volatile hydrocarbon fraction from said thermal reaction zone;and (d) blending said treated volatile hydrocarbon fraction of step (b) with said collected non-volatile hydrocarbon fraction.

Description

PROCESS TO REDUCE THE TOTAL ACIDITY INDEX OF CRUDE OIL FIELD OF THE INVENTION The present invention is directed to a process to reduce the Total Acidity index of crude oil.

BACKGROUND OF THE INVENTION The present invention is directed to a method for reducing the Total Acid (TAN) ratio of crude oils, an index which is based on the amount of organic acids, for example, carboxylic acids, especially naphthenic acids, which are present in oil.

BACKGROUND OF THE INVENTION The presence of relatively high levels of acids in petroleum, for example naphthenic acids, in crude oils or fractions thereof, is a problem for petroleum refiners and more recently for producers as well. Essentially, those acids that are to a greater or lesser degree in virtually all crude oils are corrosive, tend to cause equipment failure and lead to high maintenance costs, general inspections of facilities more frequently, than would otherwise be the case. necessary in another way, they reduce the quality of the product and cause problems of environmental elimination. fcg »&« jia ^ 'j ^ j¿i # ¿^ ^ ^^^ A very important amount of literature, both in patents and in publications, already exists which deals with the removal of naphthenic acid by conversion or absorption . For example, the addition of aqueous material, absorption on zeolites, use of alloy materials resistant to expensive corrosion in refinery or production equipment, and combination of crude oils with high TANs with lower TAN crude oils. Lazar, et al. (U.S. Patent No. 19,53,353) teaches the decomposition of naphthenic acid from raw or distillate products of primary distillation, carried out at atmospheric pressure between 315.6 to 398.9 ° C. However, it only recognizes CO2 as the only decomposition product of naphthenic acid that is not gaseous hydrocarbon and makes no provision to avoid the accumulation of reaction inhibitors. Additionally, U.S. Patent No. 2,921,023 describes the removal of naphthenic acids from the heavy petroleum fractions by hydrogenation with molybdenum oxide catalyst on silica / alumina. WO 96/06899 describes a process for essentially removing naphthenic acids from a hydrocarbon oil. The process includes the hydrogenation at 100 to 5000 kPa and at 100 to 300 ° C of a crude oil that has not been previously distilled or from which a naphtha fraction has been distilled É = aa-fefr - using a catalyst consisting of Ni-Mo or Co-Mo on an alumina carrier. U.S. Patent No. 3,617,501 describes an integrated process to retinalize all crude oil although it does not disclose the reduction of TAN. British Patent 1,236,230 describes a process for the removal of naphthenic acids from petroleum distilled fractions by processing on sustained hydrotreating catalysts without the addition of hydrogen gas. No mention is made of the partial pressure control of water and carbon dioxide. Water-based treatments have also been described (see, for example, United States Patent 4,199,440; United States Patent 4,300,995; United States Patent 3,806,437; United States Patent 3,847,774; U.S. Patent 4,033,860; U.S. Patent 5,011,579; and Kalichevsky and Kobe, Petroleum Refinition with Chemicals (1956, Chapter 4. U.S. Patent 2,795,532 and 2,770,580 describe the processes in which U.S. Pat. fractions of oil with high content of minerals and petroleum vapors respectively are treated, therefore the need to eliminate or i-iiiBa = A ^^ less reduce substantially the concentration of acids in petroleum in crude products or fractions thereof that is of a low cost and suitable for refineries. Said technology would be particularly suitable for raw products or fractions where the TAN value is approximately 2 or more. TAN, determined by the method ASTM D-664, is measured as milligrams of KOH required to neutralize the organic acids contained in 1.0 grams of oil.

BRIEF DESCRIPTION OF THE INVENTION The present invention is directed to a process for reducing organic acids in petroleum streams containing organic acids comprising: (a) heat treating a stream of petroleum containing organic acids in a thermal reaction zone comprising a plurality of stages in series, at a temperature and pressure sufficient to decompose at least a portion of the organic acids while sweeping the plurality of stages as an inert gas, to produce an acid-containing hydrocarbon fraction volatile organic and a non-volatile hydrocarbon fraction; (b) treating the volatile hydrocarbon fraction to neutralize at least a portion of the organic acids therein and to produce a volatile hydrocarbon fraction treated; (c) collecting the non-volatile hydrocarbon fraction from the thermal reaction zone; and (d) combine the hydrocarbon fraction * ^^^^^^^ 9k * ^ fa ¡£ j & ^ and volatile treated from step (b) with the fraction of non-volatile hydrocarbon collected. As used herein, the plurality of reaction stages or zones includes a plurality of reactors or a plurality of reaction zones within the same reactor. In the present invention, it is understood that, the current can be introduced continuously to the process and form the volatile hydrocarbon fractions. TAN is defined as the weight in milligrams of base required to neutralize all the acid components in the oil. Typically, the organic acids that are neutralized will be carboxylic acids, more specifically, naphthenic acids.

BRIEF DESCRIPTION OF THE FIGURE The Figure is an example of a possible configuration for conducting the present invention in the recycling mode. (1) is crude oil, (2) is combustible gas, (3) is a step-by-step thermal reactor, (4) it is an area for recovery of volatile liquid product containing acid, (5) it is a reactor where less a portion of the volatile liquid is treated with a basic salt of a metal from the HA Group, (6) it is a recycle line that transports the treated volatile liquid to the reactor vessel, (7) it is a line that returns the volatile liquid to the mixing tank (9) where it is mixed with nonvolatile reactor oil (line 8) to convert the treated raw product. Line 10 illustrates one modality of this ÜÜü g ^ * • * & amp; & amp; & amp; - rfh? ^ F * invention, wherein at least a portion of the stream treated with a basic metal salt of the HA group is directly combined with the non-volatile reactor oil.

DETAILED DESCRIPTION OF THE INVENTION The present invention neutralizes and destroys organic acids (e.g., carboxylic acids, more specifically, naphthenic acids), in petroleum streams, including crude oils and crude petroleum fractions. For example, petroleum streams, such as totally crude oils (including heavy crude oils), and fractions thereof such as petroleum fractions and vacuum gas, raw primary distillation products, atmospheric residues, vacuum residues and petroleum from vacuum gas. The process of the present invention includes a heat treatment step conducted at temperatures sufficient to destroy the organic acids. Preferred temperatures of at least about 204.44 ° C, more preferably at least 315.56 ° C. The heat treatment of step (a) comprises at least two serial heat treatment reaction steps which may be within the same reactor or separate reactors. The neutralized or partially neutralized fraction of volatile hydrocarbon (referred to herein as the treated volatile hydrocarbon fraction) is reintroduced into a different reaction step from the first reaction step of step (a) when the recycling process is employed. Preferably, the recycle stream enters The temperature of the reactor in one stage when the decomposition of the acids contained in the non-volatile hydrocarbon fraction is essentially complete. As used herein, essentially terminated means that most of the acid remaining in the non-volatile hydrocarbon fraction that can be decomposed by heat treatment has been decomposed. Preferably, the recycle stream is introduced in a step wherein the concentration of acid in the non-volatile fraction, expressed as the Total Acid Index (TAN) is less than about 1.0 and preferably less than about 0 5. In the present invention, the new stream can be introduced continuously into the process and produced therefrom a volatile hydrocarbon fraction containing organic acids. The inert gas scavenging used during the thermal treatments of step (a) serves to sweep the decomposition inhibitors formed during the decomposition of the acid. Mainly, the water must be removed along with the carbon dioxide. A pre-evaporation to remove the decanted water present in the stream (described in co-pending application of the United States of America Serial No. 920,549), is likewise preferred. The more water that can be removed, it will be preferable to remove it. Commonly, heat treatment or breeding processes to reduce TAN are operated at temperatures from 204.44 to about 426.67 ° C, more preferably from about 232.22 to about 398.89 ° C and more preferably from about 260.00 to about 385 ° C. The pressures range from about atmospheric 5 to about 6,996.33 kPa, preferably from about 204.75 to about 3548.83 kPa, and more preferably from about 308.18 to about 3169.83 kPa. The conditions are selected so that the TAN level of the non-volatile hydrocarbon fraction is below about 1.0, preferably below about 0.5. Although the above conditions are typical in the art, other conditions for the treatment produced by a volatile stream containing organic acids would be adequate in the present invention. The purging of inert or purged gas comprises the majority of any dry gas that does not react with the oil. Therefore as used herein, "inert" means those gases that will not react with, or alter the flow of oil to any detectable level. Suitable examples include methane, fuel gas and nitrogen. The scavenging speed in the reactor is adjusted to maintain a partial pressure of acid decomposition inhibitors (e.g., water and carbon dioxide), at a value below about 1.5 kg / cm2, preferably by below 0.703 kg / cm2, and more preferably below approximately 0.140kg / cm2. In general, the speed of the sweeping gas will be on the scale of approximately 1165.5 ha.ta 23,310 liters per barrel. The heat treatment reactor operates at 204.44-426.67 ° C, preferably at 232.22 ° C-398.89 ° C) and more preferably at 260-385 ° C. The pressure is maintained below about 2169.83, preferably below 1135.58 kPa, and more preferably below 446 kPa. The reaction time required to destroy the acids varies inversely with temperature, requiring longer times at lower temperatures. Within the preferred temperature range of 371.11-398.89 ° C, the reaction time will vary from about 30 to 120 minutes. The conditions are selected such that the TAN level of the non-volatile hydrocarbon fraction is below about 1.0, preferably below about 0.5. In the course of the heat treatment reaction, a volatile hydrocarbon fraction is removed from the thermal reaction zone as a gaseous effluent. The exact amount depends on the type of current and the reaction conditions. For certain heavy crudes, the amount of volatile hydrocarbon fraction recovered amounts from about 5 to 25% of the crude that is fed to the reactor. Such streams typically contain low molecular weight volatile acids and the TAN of such streams can vary from 1 to 4 or more. jfatS? SSi * m ^^ SZ After the thermal treatment of the petroleum stream, the hydrocarbon fraction is treated to reduce at least a portion of the organic acids contained therein. Said treatment includes contacting the volatile fraction with a basic salt. The basic salts that may be used herein are any of the basic salts known to those skilled in the art capable of neutralizing organic acids, particularly naphthenic acids. Preferably, the basic salts of Group IA and Group HA of the periodic table (See Basic Inorganic Chemistry, Cotton &Wiikinson, 1976) to be used. Preferably, the basic salt with an oxide, hydroxide, hydroxide hydride or carbonate. Preferably, the salts of the HA Group will be used and more preferably the calcium or magnesium salts, even more preferably a calcium salt. For example, suitable salts include CaO, CA (OH) 2, CaCO 3, MgO, Mg (OH) 2, MgCO 3 and mixtures thereof. The applicants consider that the treatment with basic salts converts at least a portion of the volatile organic acids to the corresponding organic acid salts (in the volatile hydrocarbon fraction). Such materials can be recovered through conventional means and used as a source of, for example, naphthenic acids for commercial salts. Neutralization with basic salts can be conducted by means known to those skilled in the art. By ^^ | ^^ gg ^ ¡| example, the methods set forth in WO97 / 08270, WO97 / 08275 and WO97 / 08271 incorporated herein by reference may be used. In addition, the volatilized hydrocarbon fraction of the petroleum stream can only be passed over a basic salt bed to effect the desired degree of neutralization. The contact with the basic salt is typically carried out at room temperature or at an elevated temperature sufficient to reflux the solution. Typically, this range is up to 200 ° C, with suitable narrower ranges of about 10 20 ° C to 200 ° C, preferably 50 ° C to 200 ° C, more preferably 75 ° C to 150 ° C. When it is recycled, the neutralization should preferably be conducted at the highest possible temperature compatible with the design of the process to avoid the need to heat the volatile hydrocarbon fraction neutralized during the process. recycling to the reactor. The basic salt, the hydroxides, oxides carbonates and hydroxide hydrates can be purchased commercially or synthesized using known processes. In the solid form, they may be in the form of a powder or a compound, particles sized or supported on a refractory matrix (ceramic). The reaction times depend on the temperature and the nature of the oil stream to be treated, its acid content and the amount and type of basic salt added. Typically, the neutralization can be carried out from less than about 1 hour to about 20 hours to produce gjgi ^^^^^^^^^^ j ^^^ ij * M &: s3 ^ é? ^^ - a = ^^^^ É ^^^^^^^^ a product that has a decrease in Corrosion and acid content. The treated volatile hydrocarbon fraction contains naphthenate salts of the metal oxide, hydroxide, carbonate or hydroxide hydride corresponding to Group IA or HA used in the treatment. The conditions can easily be determined by someone skilled in the art. The reactor system for the heat treatment (stage (a) of the process) is designed to provide a residence time of the liquid at a selected temperature suitable to achieve the desired conversion and achieve a rapid mass transfer to remove the inhibition products from the reaction of acid decomposition, that is, water and carbon dioxide. Suitable reactors comprise two or more stages and may be, for example, one of the following designs; Bubble lifting column, mechanically agitated bubble lifting column and percolating bed, etc. The recycling of the treated volatile hydrocarbon fraction has the added benefit of reducing the requirement to separate the gas in the thermal reactor. Additionally, the basic salts that remain in the crude can act as inhibitors against corrosion. Similarly, the recycling serves to reduce the acid content of the volatile hydrocarbon fraction of step (a) since the acids neutralized in the volatile hydrocarbon fraction treated and recycled are at least partially destroyed when introduced, by means of recycling to the reaction zone thermal Therefore, the total volatile hydrocarbon fraction produced from the recycling process will comprise the volatile hydrocarbon fraction from the new stream plus the volatile hydrocarbon fraction treated and recycled. In carrying out the present invention using recycle, it is understood that the petroleum stream which is introduced to the thermal reaction stage (a) produces a volatile hydrocarbon reaction. Therefore, the total volatile hydrocarbon fraction produced at the completion of the recycling process, will that from the new stream plus that amount of the volatile hydrocarbon fraction treated and recycled. After the last recycling, the volatile hydrocarbon fraction combined with the non-volatile hydrocarbon fraction will comprise the treated and recycled volatile hydrocarbon fractions and the fractions of volatile hydrocarbons newly generated from the new oil stream introduced during recycling. One skilled in the art will recognize that the number of recycles will depend on the capacity of the thermal reactor that is being used and the desired TAN for the combined product. In the practice of this invention, the volatile hydrocarbon fraction is treated with the basic salt to neutralize at least a portion of the acids contained therein. The volatile hydrocarbon fraction is contacted with the basic salt in a mixing zone that operates on a scale of 65.5 to 148.8 ° C under autogenous pressure for a sufficient time to complete the sBMSaafeatfg »» «i a¿. The reaction between the basic salt and the organic acid. Suitably, a small amount of water, from 0.25 to 1.0% by weight based on the weight of the volatile liquid, is included in the mixing zone to facilitate the reaction. In a preferred embodiment, a sufficient amount of basic salt is added to the volatile hydrocarbon fraction to completely neutralize the acid and the entire treated stream is recycled to the reactor. Referring to the figure, the volume ratio of 0 the neutralized hydrocarbon stream (line 6) to the volatile liquid stream that is removed from the combination (line 7) is at least 1: 1 and can vary up to 3: 1 or more The higher the ratio, the lower the TAN of the volatile hydrocarbon fraction withdrawn from the process by means of line 7. In another embodiment of the process, the treated volatile hydrocarbon fraction that arises from vessel 5 (after contact with the basic salt ) is not recycled, but is fed directly to the combination vessel 9. The basic salt thus added acts as a regulator to mitigate the corrosive effects of any residual acids. In another embodiment of the process, the treated hydrocarbon fraction arising from the container 5 (after contact with the basic salt) is not recycled to the reactor 3, but is fed to a separate thermal treatment zone 5 from the stage (a ), for example, an area of instant distillation ^^ H ^^ ¡l a¡ & (not shown), wherein the neutralized acid component of the stream is at least partially destroyed. The resulting treated volatile hydrocarbon fraction (with lower TAN) is then fed to a mixing vessel 9 or recycled to step (a). One skilled in the art can easily determine the reaction conditions for said step. In fact, a sufficient time and temperature to destroy at least a portion of the neutralized acids would be selected. In the recycling mode of the present invention, the volatile hydrocarbon fraction arising from the heat treatment step (a) can be combined with the non-volatile hydrocarbon fraction without executing a final contact step with the basic salt. In such a case, the volatile hydrocarbon fraction (comprising fractions of volatile hydrocarbon treated and freshly formed volatile hydrocarbon fraction originating from the new stream) would be combined with the non-volatile hydrocarbon fraction by line 7. Alternatively, a final treatment of the volatile fraction can be conducted before mixing. The following examples illustrate the invention although they do not limit it in any way.

EXAMPLE # 1 (Comparative) This experiment was carried out in a 300 cc autoclave reactor with stirring. The reactor was operated in batch mode with respect to the crude oil that was loaded. It was flowed ^ g ^^ ü ^ ^ g ^^^^^^^^^^ j argon through the reactor to maintain the combined partial pressures of water and carbon dioxide (acid decomposition gases that can inhibit the decomposition of acid) at less than 0.0703 kg / cm2. 5 The reactor was loaded with 100 grams of an extra heavy Venezuelan oil that had a TAN of 3.0, cleaned with an argon discharge and then heated with agitation at a temperature of 375 ° C. The argon was flowed through the reactor to 0.14 liters per minute at a pressure of 2,109 kg / cm2 gauge, which was maintained by a counter pressure regulator. After a reaction period with stirring at 385 ° C, the reactant was cooled and discharged. Then, 83.8 g of the reactor oil and 14.21 g of volatile hydrocarbon liquid were recovered, which was removed from a cold trap downstream of the reactor. The TAN tests of the reactor oil and the volatile liquid were respectively 0.05 and 1.42. The experiment was repeated several times to obtain the volatile liquid product for subsequent recycling experiments. EXAMPLE # 2 (Comparative) The experiment of Example # 1 was repeated, except that 12 g of volatile liquid of Example # 1 was charged to the autoclave together with 100 g of fresh stream. 25 85.7 g of the reactor oil and 24.21 g were recovered *? a? k ~ ** t * t ** «** i? * ^ g && amp; j¡ «gÜ» g¡¡H ^ ^ j ¡^ ggg | ^ of the volatile liquid. The TAN tests of the reactor oil and the volatile liquid were respectively 0.06 and 1.49. This example illustrates that the recycling of the volatile liquid without treatment with a basic salt does not result in any reduction of the TAN content of the volatile liquid product.

EXAMPLE # 3 A volatile liquid treated with calcium hydroxide was prepared in the following manner. To a 50 cc round bottom flask equipped with stirrer and condenser was charged 21 g of volatile liquid (TAN 1 42) prepared according to Example # 1 together with 0.036 calcium hydroxide powder and 0.13 g deionized water. The flask was heated with stirring at 93.3 ° C for a period of 5 hours. The flask was cooled and the treated volatile liquid was decanted and stored for later use. The experiment of Example # 1 was repeated except that 9.45 g of the volatile oil treated with calcium hydroxide was charged together with 100 g of fresh stream. 85.65 g of reactor oil and 22.2 g of volatile liquid product were recovered. The TAN tests of the reactor oil and the volatile liquid were respectively 0.04 and 1.62. This example illustrates that the recycling of the volatile product treated with calcium does not have a beneficial effect when the recycle stream is added to the new stream or to the first stage of the thermal reactor, for example by adding to a stage 1 of the multi-stage reactor.

EXAMPLE # 4 Example # 3 was repeated except that the volatile liquid 5 treated with calcium was not added to the new stream. Instead, the reactor was initially charged with 100 g of fresh stream. After a stirring contact of 34 minutes at 385 ° C the reactor was cooled to 65.5 ° C and 8.85 g of the volatile liquid treated with calcium were added. The reactor was then heated to 385"C during an additional contact of 30 minutes. 87.6 g of the reactor oil and 19.1 g of the volatile liquid product were recovered. The TAN tests of the reactor oil and the volatile liquid products were, respectively, 0.02 and 1.18. This example illustrates that the recycling of a volatile liquid treated with calcium can effectively reduce the TAN of the volatile liquid provided that the treated liquid is recycled to the reactor after the new stream has undergone some degree of reaction, is say, the volatile liquid treated is recycled to a second or third stage, etc.

EXAMPLE # 5 A sample of 70 g of volatile liquid (TAN = 1) obtained from the heat treatment of a Venezuelan heavy oil was charged to a round bottom flask together with 0.42 g of water deionized and 0.07 g of 'calcium hydroxide powder. The mixture was heated and stirred at 93.3 ° C for a period of 5 hours under a nitrogen atmosphere. The resulting calcium-treated oil was then placed in an autoclave and heated to 385 ° C while the argon was swept at a rate of 0.05 liters per minute. At the end of a 30 minute period at 385 ° C, 61.14 g of the volatile liquid had been distilled from the autoclave and 6.07 g of the liquid remained in it. The TAN tests showed that the oil remaining in the autoclave had a TAN of 0.1, considering that the volatile oil had a TAN of 0.39. This example illustrates that the TAN content of a volatile oil can be reduced by treating said oil with a basic calcium salt and then distilling it.

Claims (10)

1. CLAIMS 1. A process for reducing organic acids in petroleum streams containing organic acids comprising: (a) heat treating a stream of petroleum containing organic acids in a thermal reaction zone comprising a plurality of stages in series, a temperature and pressure sufficient to decompose at least a portion of said organic acids, while sweeping the plurality of stages with an inert gas, to produce a hydrocarbon fraction containing volatile organic acid and a non-volatile hydrocarbon fraction; (b) treating the volatile hydrocarbon fraction to neutralize at least a portion of the organic acids therein and to produce a volatile hydrocarbon fraction treated; (c) collecting the non-volatile hydrocarbon fraction from the thermal reaction zone; and (d) combining the volatile hydrocarbon fraction treated from step (b) with the non-volatile hydrocarbon fraction collected.
2. 2. The process according to claim 1, characterized in that the treatment step (b) comprises contacting the volatile hydrocarbon fraction with a basic salt of a metal selected from the group consisting of metals from Group IA, Group HA and mixtures thereof at a temperature and for a time sufficient to neutralize at least a portion of said organic acids.
3. 3. The process according to claim 2, further comprising heat treating the hydrocarbon stream at a temperature and for a time sufficient to destroy at least a portion of the neutralized organic acids.
4. The process according to claim 1, further comprising recycling at least a portion of the volatile hydrocarbon fraction treated to a different stage of the first stage from the plurality of steps of step (a).
5. 5. The process according to claim 1, characterized in that the heat treatment temperature of step (a) is at least about 204.4 ° C.
6. 6. The process according to claim 1, characterized in that the petroleum stream undergoes a previous evaporation step to remove the decanted water.
7. The process according to claim 1, characterized in that the inert gas scavenging maintains a partial pressure of the acid decomposition products in the reactor below approximately 1.75 kg / cm2.
8. 8. The process according to claim 1, characterized in that the inert gas sweep has a sweep speed in the range of about 1165.5 to 23,310 liters per barrel.
9. 9. The process according to claim 1, characterized in that the temperature and pressure are selected such that the non-volatile hydrocarbon fraction has a TAN of less than about 1.0 after the heat treatment of step (a).
10. 10. The process according to claim 2, characterized in that the treatment is conducted in the presence of about 0.25 to about 10% by weight of water.