RU2754173C1 - Method for producing drag-reducing additives for application under low temperatures of the transported medium - Google Patents

Abstract

FIELD: petroleum industry.

SUBSTANCE: invention relates to the field of petroleum and petroleum product pumping through main pipelines. The method includes obtaining a copolymer with a high molecular weight by copolymerisation of alpha-olefins in a medium of fluorinated alkanes on a titanium-magnesium Ziegler-Natta catalyst in an inert atmosphere. The polymerisation mass is then discharged into alkanediol or a mixture of propylene glycol and n-butyl dipropylene glycol ether while stirring. The subsequent stripping of the unreacted monomer of fluorinated organic compounds is executed while stirring and bubbling with nitrogen. Filtration and subsequent stabilisation of the commercial form of DRA are then conducted by dispersion in alcohol with an adhesion-reducing agent. Hexene-1 with decene-1 or dodecene-1 are used as comonomers in a molar ratio of 0.95:0.05 to 0.80:0.20.

EFFECT: reduction of the throughput capacity of the main pipelines in the cold period of the year is prevented.

1 cl, 2 dwg, 2 ex

Description

The invention relates to the field of pumping oil and oil products through main pipelines, namely, reducing the hydraulic resistance of the flow at low temperatures of oil and oil products.

In order to increase the throughput of pipelines and increase the energy efficiency of pipeline transportation of oil and oil products, anti-turbulent additives (hereinafter referred to as PTP) are widely used - agents that reduce the hydrodynamic resistance of pumped hydrocarbon fluids.

The efficiency of DRA significantly depends on the type of the transported liquid, as well as on the pumping conditions, the properties of the transported medium, as well as on the chemical nature of the polymer component of the additive. Under conditions of pumping media with low temperatures (oil and diesel fuel at low temperatures, from 0 to + 10 ° C, which is especially important for countries with a cold climate), many traditionally used DTPs demonstrate reduced efficiency.

The active component of widely used DRAs is mainly a polymer based on alpha-olefins (mainly hexene-1). The product of homogeneous polymerization of olefins is usually a viscous product (RU2590535 dated 10.7.2016, C08F 110/14).

The use of this product in the transportation of hydrocarbons is impossible due to the extremely low rate of dissolution of ultra-high molecular weight olefins in hydrocarbons.

The finished forms of polyolefin DRAs are solutions or dispersions that have their own advantages and disadvantages.

The first generation of commercial polyolefin anti-turbulence additives (from the 1980s to the mid-1990s) were polyolefin-based solutions or gels. Even relatively dilute (5-10%) polymer solutions weighing several million amu. had a high viscosity, showed a tendency to aggregation and delamination (RU2075485 from 20.03.1997, C08F 10/14).

These factors significantly hampered the storage and transportation of solution forms of DTP. Due to the high viscosity, the low rate of dissolution of polymer concentrates necessitated preliminary dilution, or the use of high-pressure units and special nozzles when introducing DRA into petroleum products. As a result, the solution forms of PTP were replaced by PTP in the form of suspensions.

Second-generation turbulence additives (since the late 1990s) are highly dispersed mixtures based on solid microparticles of polyolefin, they usually contain up to 25% polymer. Microparticles of the polymer were originally prepared by freezing the bulk polymer to cryogenic temperatures (of the order of minus 100 ° C) and grinding (cryogenically-ground slurry) (US4826728 from 05/02/1989, C02F 1/68; US4720397 from 01/19/1988, C02F 1/68; US4340076 from 07.20.1982, В29В 13/10).

In the early 2000s, it was these products that were mainly introduced on the polyolefin DRA market.

The disadvantages of dispersed forms obtained using cryo-grinding are the tendency to aggregation and gelation, requiring compliance with the temperature regime during storage and transportation, as well as difficulties in introducing oil and oil products into the flow (the need to use heated injectors, etc.). In addition, cryo-grinding leads to a noticeable decrease in the effect of reducing the hydraulic resistance due to the mechanical destruction of macromolecules. An alternative to cryo-grinding is long-term dispersion or laborious reprecipitation in the presence of a surfactant. At the present stage, cryo-grinding is complemented by the use of mixtures of reagents - dispersants and stabilizers, to obtain stable and soluble dispersions. As a medium for polymer particles, so-called "non-solvents" are used - various polar organic compounds (ethers, alcohols, amino alcohols, etc.).

To date, technologies for the production of suspension-type polyolefin DRAs have generally been developed and implemented. These technologies are used to produce a wide range of additives used in the transportation of oil and oil products. These additives show consistently high performance in diesel fuels and low viscosity grades under normal climatic conditions. However, problems arise when using polyolefin DRAs at low temperatures.

These problems are most likely due to the limited solubility of some types of polyolefin DRAs at low temperatures, the tendency of DRA molecules to aggregate and form associates with components of hydrocarbon mixtures. Thus, it has been experimentally established that the effectiveness of traditional polyolefin DRAs when transporting oil with a high asphaltene content decreases with decreasing temperature, this is especially pronounced when using polyhexene DRAs (Valiev M.I., Khasbiullin I.I., Kazakov V.V., Features the use of anti-turbulent additives based on polyalphaolefins at various oil temperatures, Science and technology of pipeline transport of oil and oil products, 2016, 32).

One of the analogues of the present invention is the composition "Polymer Composition Useful as Flow Improvers in Cold Fluids", which provides a method for producing an additive for reducing the hydraulic resistance of cold fluids. The composition is a polymer obtained by copolymerization of C ₄ -C ₉ alpha olefin with a comonomer with a carbon chain length of more than 12 carbon atoms (US 20030069330 A1 from 10.04.2003, C08F 2/02).

The disadvantage of the proposed method is the cumbersome and unsafe technology of cryogenic grinding of the polymer in liquid nitrogen, as a result of which its mechanical destruction (decrease in molecular weight) occurs, which leads to a decrease in the final efficiency of the resulting additive. The disadvantages of the specified composition of the composition include the use of a comonomer with low reactivity, in which the chain length is greater than 12 carbon atoms. Too much increase in comonomer chain length over 1-hexene results in a polymerization substrate with a lower double bond “concentration”. This leads to the fact that, all other things being equal, the polymerization of higher alpha-olefins on Ziegler-Natta catalysts proceeds at a slower rate, which leads to an increased risk of chain termination by the beta-hydride elimination mechanism, a lower molecular weight of the polymer, and its poorer efficiency. Also, if the molecular weights are equal, the actual length of the polymer chain with the "longer" comonomer will be shorter, which is directly related to a decrease in the efficiency of reducing the hydraulic resistance.

A method for producing suspension DRAs without the use of polymer grinding is known from the prior art. In this method, the polymerization of higher alpha-olefins is carried out in the medium of fluorinated organic compounds on a titanium-magnesium catalyst modified with an electron-donor compound, followed by the replacement of the medium of fluorinated organic compounds with a dispersion medium consisting of triglycerides of fatty acids (RU 2579583 dated 05.24.2015, C08F 110 /fourteen).

The disadvantage of this method is to obtain PTP with low performance when used at low temperatures of the pumped oil and oil product, as well as at low ambient temperatures, in which pipelines with a low temperature of the pumped medium are operated. Thus, in this method, alpha-olefins such as butene-1, hexene-1, octene-1 are selected as the monomer. At the same time, as our experience shows, polymers based on these monomers showed a significant decrease in efficiency when used at oil temperatures below 10 ° C. To maintain the effectiveness of such additives with a decrease in the temperature of oil and oil products in the cold season, it is necessary to increase the concentration of the additive input, and in some cases it is not possible to provide the required efficiency even with a multiple increase in the dosage of DRA.

The disadvantage of this solution is also the use of vegetable oils (triglycerides of fatty acids) as a dispersion medium, which can lead to solidification of the additive and the impossibility of its introduction into the pipeline without heating at low ambient temperatures, which usually accompany the pumping of cold oils and oil products. Also, this solution does not take into account other features of obtaining specialized additives for cold ambient temperatures (the ratio of comonomers, an increase in the viscosity of the polymer, and deterioration of the removal of the heat of polymerization when using comonomers above C ₆ ).

The objective of the invention is to obtain DRA for use at low temperatures of pumped oil and oil products by obtaining a polymer with side alkyl branches of irregular length, which has an increased solubility in hydrocarbons with decreasing temperature.

The task is achieved by copolymerizing hexene-1 with decene-1 or dodecene-1, which results in a polymer with increased solubility in hydrocarbons and a lower tendency to aggregation with decreasing temperature due to the disordered microstructure and the presence of extended alkyl side chains of various lengths.

The technical result consists in increasing the throughput of main pipelines at a temperature of the transported medium below + 10 ° C.

The technical result is provided by the fact that the method for producing anti-turbulent additives for use in the transportation of oil and oil products through main pipelines includes obtaining a copolymer with a high molecular weight by copolymerization of alpha-olefins in fluorinated alkanes on a titanium-magnesium Ziegler-Natta catalyst in an inert atmosphere, while unloading the polymerization mass into alkanediol or a mixture of propylene glycol and n-butyl ether of dipropylene glycol with stirring, distilling off the unreacted monomer of fluorinated organic compounds with stirring and bubbling with nitrogen, filtration and subsequent stabilization of the commercial form of PTP by dispersing in alcohol with an anti-agglomerator as an anti-agglomerator -1 with decene-1 or dodecene-1 in a molar ratio of 0.95: 0.05-0.80: 0.20.

As a titanium-magnesium Ziegler-Natta catalyst, a titanium-magnesium Ziegler-Natta catalyst modified with an electron-donor compound can be used.

Brief description of graphic images:

FIG. 1 - Comparison of the efficiency of samples according to Examples 1 and 2 with the efficiency of polyhexene DRA at an oil temperature of 5 ° C.

FIG. 2 - Comparison of the efficiency of the sample according to Example 1 at an oil temperature of 5 ° C with the efficiency of polyhexene DRA at an oil temperature of 15 ° C.

The method is carried out as follows.

Fluorinated compounds and hexene-1 are loaded into the polymerization reactor in a nitrogen atmosphere based on a volume ratio of 1.5-2.5 (fluorinated compounds): 1 (Hexene-1). The cocatalyst is loaded - a solution of TIBA in dodecene-1 or decene-1, the catalyst is injected. Polymerization is carried out at a temperature of -10 - + 10 ° C. The reaction time is 240-300 minutes, during the reaction, continuous stirring is carried out at 55 rpm for 120 minutes. After 120 minutes, the number of revolutions of the stirrer is increased to 80 rpm and the polymerization is continued. After 180 minutes, the speed of the mixing device is raised to 95 rpm. To prevent sticking of polymer particles formed during the copolymerization, mixing in the reactor can be carried out using a belt mixer with an increased spiral width and a reduced angle of attack of the spiral.

After the polymerization process, the polymerization mass is unloaded into alkanediol or a mixture of propylene glycol and n-butyl ether of dipropylene glycol with stirring. The unreacted monomer and fluorinated compounds are distilled off at a temperature of 70-75 ° C with stirring and bubbling with nitrogen.

The choice of alkanediol / a mixture of propylene glycol and n-butyl ether of dipropylene glycol as a medium for the isolation of the polymer is due to the following. From the data accumulated as a result of studies of the process of obtaining DRA in laboratory and industrial conditions, it was concluded that it is the vegetable oil used in the prototype as a medium for isolating polymer chips and obtaining a suspension that has the greatest effect on the pour point of DRA.

One of the aspects of the proposed technical solution is the replacement of oil in the process of polymer isolation with alkanediol, (for example, hexanediol-1,2), which has a number of properties, such as: high extracting ability with respect to hexene-1, non-volatility, is a nonsolvent for polyolefin even in the presence of significant amounts of monomer, low viscosity on heating and at room temperature.

Experiments have shown that hexanediol is an acceptable alternative to the used release medium, does not degrade the properties of the polyolefin being recovered, and is also suitable for reuse in the production cycle.

After distillation of unreacted monomer and fluorinated compounds, the polymer is filtered on a vacuum filter to separate the polymer from hexanediol.

Filtered polymer chips are dispersed in butanol with an anti-agglomerator.

The need for the stage of replacing the alkanediol with alcohol (butanol) with an anti-agglomerator to obtain a commercial polymer suspension is due to the need to ensure a low pour point of the commercial form of DRA, the possibility of reusing hexanediol, and a decrease in the cost of components of the commercial form of the additive.

Thus, in the claimed method, the production of DRA for low temperatures of the pumped medium is carried out in the following stages:

- catalytic copolymerization of hexene-1 with decene-1 or dodecene-1 in a molar ratio of 0.95: 0.05-0.80: 0.20 in fluorinated alkanes on a titanium-magnesium catalyst modified with an electron-donor compound in an inert atmosphere;

- upon reaching a conversion of 60-90%, dispersing the reaction mixture in alkanediol, followed by distilling off the organofluorine solvent and unreacted hexene-1;

- filtration of the suspension for removal;

- dilution of the dried polymer with alcohol (butanol-1) in the ratio polymer: butanol 0.2-0.3: 0.8-0.7 and adding an anti-agglomerator to obtain a commercial form of PTP.

One of the advantages of the proposed method in comparison with the prototype is the possibility of using PTP at a low temperature of the surrounding oil pipeline environment with a temperature of oil and oil product below 10 ° C.

The following are examples of the implementation of the method and characteristics of the resulting additive.

Example 1.

Liquid PFMCG and hexene-1 were loaded into the polymerization reactor in a nitrogen atmosphere based on a volume ratio of 1 (fluorinated compounds): 2.25 (Hexene-1). A 3% solution of TIBA in decene-1 was added based on the ratio of hexene-1 to decene-1 85.5%: 14.5%. The TMK catalyst is being introduced. The polymerization is carried out at a temperature of 5 ° C. The reaction time was 300 minutes, during the reaction was carried out with continuous stirring. Then carried out the dispersion of the polymerization mass in a mixture of propylene glycol and n-butyl ether of dipropylene glycol for 120 minutes and distillation of unreacted hexene-1 and PFMCG liquid at a temperature of 70-75 ° C with stirring and bubbling with nitrogen. The polymer was filtered on a vacuum filter to separate the polymer from the hexanediol. Filtered polymer chips were added to butanol and dispersed with an anti-agglomerator. The resulting polymer suspension was tested on a hydraulic bench.

Example 2.

The experiment is carried out in the same way as the experiment described in example 1, with the difference that instead of decene, dodecene-1 was used in an amount based on the ratio of hexene-1 to dodecene-1 91.5%: 8.5%.

The polymer suspensions obtained according to the formulation of Examples 1-2, as well as a comparison sample of polyhexene DRA were carried out on oil on an experimental stand for conducting multivariate studies of the characteristics of agents for reducing the hydraulic resistance of oil and oil products (patent RU 2659747 dated 03.07.2018, G01N 11/08).

The stand allows you to determine the effectiveness of DRA directly on oil at different temperatures.

The tests included:

- measurement of the value of the drop in hydrodynamic resistance (DR) of the solution of the test sample of DRA in oil at a temperature of 5 ° C;

- plotting a graph of the change in efficiency from time to time since the introduction of a given amount of anti-drug products into the model fluid;

- determination of the maximum value of the effectiveness of the commercial form of DTP.

The decrease in the hydrodynamic resistance DR was calculated by the formula:

where: ΔP _f , is the pressure drop on the measuring line during the flow of liquid from the DRA, Pa;

ΔР ₀ - pressure drop across the measuring line during fluid flow without DRA, Pa;

Q _f , is the flow rate of the liquid from the PTP, m ³ / h;

Q ₀ - liquid flow rate without DRA, m ³ / h.

The test results of DRA samples obtained according to Examples 1 and 2, as well as polyhexene DRA (prototype) are shown in FIG. 1. The graphs show that the highest maximum efficiency is demonstrated by the sample according to example No. 1 based on a copolymer of hexene and decene, as well as the highest residual efficiency. A little less is shown by the sample according to Example 2, based on a copolymer of hexene-1 and dodecene-1.

The efficiency of the sample according to Example 1 at an oil temperature of 5 ° C is significantly higher than the efficiency of the classical hexene DRA. Moreover, the efficiency of Example 1 at a reduced oil temperature is not inferior to the efficiency of PT-FLYDE PTP, which the latter demonstrates at an oil temperature of 15 ° C (Fig. 2).

Thus, the above examples 1-2 and the results of testing the efficiency of DRA samples, shown in Figures 1 and 2, confirm the solution of the technical problem posed, namely the development and implementation of a method for producing an anti-turbulent additive that provides a decrease in hydrodynamic resistance at temperatures of a hydrocarbon liquid below 10 ° C, by carrying out suspension copolymerization of hexene with decene or dodecene with a content of the latter of 5-15% in a medium of fluorinated organic compounds using a titanium-magnesium catalyst and adding an electron-donor modifier, followed by dispersion in a dispersion medium (alkanediol or a mixture of propylene glycol and n -butyl ether of dipropylene glycol) and distillation of fluorinated organic compounds and monomers, and replacement of the dispersion medium with butanol-1. This technical solution ensures the preservation of the efficiency of the DRA when the temperature of the pumped oil and oil product drops below 10 ° C at a level comparable to the efficiency of traditional polyhexene additives demonstrated at higher temperatures.

Claims (1)

A method of producing anti-turbulent additives for use in the transportation of oil and oil products through main pipelines, including obtaining a copolymer with a high molecular weight by copolymerizing alpha-olefins in fluorinated alkanes on a titanium-magnesium Ziegler-Natta catalyst in an inert atmosphere, characterized in that the polymerization is unloaded mass into alkanediol or a mixture of propylene glycol and n-butyl ether of dipropylene glycol with stirring, distillation of unreacted monomer of fluorinated organic compounds with stirring and bubbling with nitrogen, filtration and subsequent stabilization of the commercial form of the anti-turbulent additive by dispersing in alcohol with an anti-agglomerator-1 with decene-1 or dodecene-1 in a molar ratio of 0.95: 0.05-0.80: 0.20.

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