RU2577797C1 - Turbulent rheometer and method of determining efficiency of anti-turbulence additive (ata), implemented by turbulent rheometer - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to rheology of diluted solutions of polymers, as well as surfactants, and can be used to determine efficiency of anti-turbulence additive (ATA) used when pumping hydrocarbon fluids through pipelines. Turbulent rheometer contains mounted on a tripod a storage container with a ball valve and a Mariotte pipe, a tube with small internal diameter for passage of a low-viscosity hydrocarbon liquid in turbulent flow, a solenoid valve with a time switch for setting length of time of valve opening, a receptacle and technical scales for measuring mass of liquid in receptacle. Method of determining efficiency of ATP comprises filling supply tank through ball valve with low-viscous hydrocarbon fluid, valve is closed to maintain constant pressure in supply tank, setting time by time switch and opening solenoid valve. After automatic actuation of time switch, solenoid valve is closed, then weighed on industrial scales filled with receiving tank. It is then added to fluid in a certain concentration, actions described above are performed and reduction of hydrodynamic resistance after the introduction ATA is calculated. Actions described above are performed for a number of values of concentration of ATA in liquid and efficiency of ATA is then determined to obtain dependence of reducing hydrodynamic resistance of concentration of ATA.

EFFECT: simple design of turbulent rheometer and higher reliability of measurement results efficiency of ATA.

5 cl, 1 ex, 2 dwg

Description

The invention relates to the field of rheology of dilute polymer solutions, as well as surfactants, and can be used to determine the effectiveness of anti-turbulent additives (PTP) used in the pumping of hydrocarbon fluids through pipelines.

The effect of reducing the hydrodynamic resistance of liquids using additives of high molecular weight polymers or surfactants (Toms effect) [Hoyt, D. Effect of additives on the friction resistance in liquids // Theoretical Foundations of Engineering Calculations. - 1972. - No. 2. - S. 1-31] is observed only in the turbulent flow regime. A necessary condition for the manifestation of the effect in the case of polymers is a high molecular weight, about 106-107, and good solubility in this liquid; for surfactants, the necessary condition is the formation of filamentous micelles in the liquid. The Toms effect is widely used in engineering practice: when pumping oil and oil products through pipelines, in oil production when drilling wells, when moving surface and underwater objects, in fire fighting, to increase the throughput of storm sewers, in irrigation systems. Surfactant solutions are used to reduce friction losses in local heating and air conditioning systems.

The most widely used are polymer-type PTPs used to increase the throughput of oil and product pipelines.

A known method of testing an anti-turbulent additive on a natural pipeline [patent for invention RU 2488032 C1, publ. 07/20/2013, IPC: F17D 3/12, F15D 1/02], including the measurement of the pressure drop in the linear test section of the pipeline in the absence of an anti-turbulent additive in the pumped liquid, the introduction of an anti-turbulent additive in a linear section of the pipeline, at different concentrations, before filling, measurement the differential pressure in the linear section of the pipeline after each filling of the linear section and calculating the effectiveness of the additive (Ci) for each concentration according to the formula:

(C _i ) = (P ₀ -P _Ci ) / (P ₀ -P _gst ), where

P ₀ - pressure drop at the ends of the plot in the absence of additives;

P _Ci - pressure drop when introducing additives with a concentration of Ci;

Ρ _gst = g (z _n -z _k );

R _gst - hydrostatic pressure drop at the ends of the linear section;

ρ is the density of the pumped liquid;

g is the acceleration of gravity;

(z _n -z _k ) is the difference in elevations between the beginning and end of the linear section.

From the moment of starting the introduction of the additive with each concentration into the linear section of the pipeline to filling the test linear section of the pipeline with this additive and measuring the pressure drop at a given concentration of the additive, the flow rate of the pumped liquid is equal to the flow rate in the pumping mode without additives using actions that do not affect hydraulic losses in the test linear section.

The disadvantage of this method is the high cost of the experiment, which doubles or triple during comparative tests of two or three additives, respectively.

An important point that precedes the practical use of the polymer (or surfactant) is its test in the laboratory, where the dependence of the value of the decrease in resistance (DR) on the concentration of the agent in the liquid under given flow conditions is determined. For these purposes, laboratory turbulent rheometers of various designs are used, where the main element can be coaxial cylinders, a rotating disk, a segment of a smooth pipe (capillary).

The closest analogue of the claimed invention is a method of measuring the magnitude of the reduction in hydrodynamic resistance and a turbulent rheometer [Manzhay V.N. Turbulent flow of dilute polymer solutions in a cylindrical channel: Abstract of dissertation for the degree of Doctor of Chem. Sciences: 02.00.06 / Tomsk state. un-t - Tomsk, 2009. - 44 p.]. The working section of the rheometer is a glass capillary with a length of about 1 m and a diameter of 2 to 5 mm. Liquid flows out through the capillary at a constant pressure created in the receiver using a can of compressed gas. The upper open end of the tube communicates with the working chamber of the rheometer, where the test liquid is poured. Through the other end, equipped with a tap, the liquid has an outlet to the external environment and then enters the receiver. The receiver has a fixed capacity tank. The meniscus of fluid, moving as the receiver fills, turns the electronic stopwatch on and off using sensors with photodiodes.

On a turbulent rheometer, the expiration time of a fixed volume of pure solvent and polymer solutions with different concentrations at the same given pressure drops ΔP _s = ΔΡ _p = const is measured. The hydrodynamic drag reduction value is calculated by the formula:

where t _s is the expiration time of a fixed volume of solvent (without PTP),

t _p is the expiration time of the same volume of polymer solution at the same pressure.

A disadvantage of the known design of the rheometer is that at high flow rates, the liquid at the inlet of the receiver can capture air bubbles, which can lead to foaming, and this, in turn, can lead to premature operation of the stopwatch.

The problem to which the claimed invention is directed, is the development of a turbulent rheometer that allows to measure the mass flow rate of a liquid flowing for a given period of time, quickly evaluate the effectiveness of a particular PTP without the need for tests on an existing pipeline or the use of complex expensive laboratory equipment.

The technical result of the claimed invention is to simplify the design of a turbulent rheometer and increase the reliability of the results of measurements of the effectiveness of anti-turbulent additives.

The specified technical result is achieved by the fact that the turbulent rheometer contains a supply container mounted on a tripod, in the upper part of which there is a ball valve for receiving a low-viscosity hydrocarbon liquid or a low-viscosity hydrocarbon liquid with an anti-turbulent additive (PTP) introduced into it in a certain concentration, while the consumable tank is equipped with Mariotte tube to maintain a constant pressure in the supply tank when fluid flows from it; a tube of small internal diameter for the passage of a low-viscosity hydrocarbon fluid in a turbulent flow regime, the upper end of which is connected to the supply tank; an electromagnetic valve located at the lower end of the tube of small internal diameter, configured to set the length of time during which it will be open, by means of a time relay connected to it; a receiving tank, the input of which is under the lower end of the tube of small internal diameter, emerging from the electromagnetic valve; technical scales for measuring the mass of liquid passing through a tube of small internal diameter into the receiving tank for the length of time specified by the time relay.

In addition, in a turbulent rheometer, a tube of small inner diameter is a tube of metal, plastic or glass, the length of which is from 80 to 150 cm, and the inner diameter is from 1.5 to 6.5 mm.

In this case, a low-viscosity hydrocarbon liquid has a viscosity of less than 1.3 cSt.

In addition, the length of time during which the solenoid valve is open is preferably in the range of 15-25 seconds.

The technical result is also achieved by the fact that in the method for determining the effectiveness of an anti-turbulent additive (PTP), implemented by means of a turbulent rheometer, a low-viscosity hydrocarbon liquid is poured into a flow tank equipped with a Marriott tube through a ball valve; close the ball valve to ensure that a constant pressure is maintained in the supply container when liquid flows out of it; set by means of a time relay the length of time during which the electromagnetic valve will be open, and start the opening of the electromagnetic valve; fill the pre-weighed receiving container with liquid for a given period of time; close the solenoid valve by automatically activating the time relay; weigh the receiving container with liquid on a technical balance and determine the mass of pure liquid; perform the above actions after introducing PTP in a low-viscosity hydrocarbon liquid at a certain concentration and determine the mass of the liquid with the PTP introduced into it; calculate the decrease in hydrodynamic resistance after the introduction of PTP in a certain concentration according to the following formula:

где

Where

m ₀ is the mass of low-viscosity hydrocarbon fluid that has passed into the receiving tank for the length of time specified by the time relay;

m _PTP is the mass of liquid with the PTP introduced into it, which has passed into the receiving tank for the same length of time specified by the time relay;

perform the above actions for a number of concentrations of PTP in a low-viscosity hydrocarbon liquid; evaluate the effectiveness of PTP, obtaining the dependence of the magnitude of the reduction in hydrodynamic resistance on the concentration of PTP.

The claimed invention is illustrated by drawings:

FIG. 1 is a diagram of a turbulent rheometer;

FIG. 2 - dependence of reducing the hydrodynamic resistance of a low-viscosity hydrocarbon fluid (nefras) on the concentration of anti-turbulent additives (PTP).

The designations indicated in the drawings are shown by the following positions:

1 - consumable capacity;

2 - ball valve;

3 - Mariotte tube;

4 - a tube of small internal diameter;

5 - the electromagnetic valve;

6 - time relay;

7 - receiving capacity;

8 - tripod.

In FIG. 1 shows a diagram of the inventive capillary-type turbulent rheometer for measuring the hydrodynamic drag reduction of low-viscosity hydrocarbon liquids caused by the addition of PTP in the form of polymers or surfactants. The rheometer consists of a flow tank 1, equipped with a Mariotte tube 3, and a ball valve 2 in the upper part of the tank 1. A tube 4 of small internal diameter (capillary) serves to pass a low-viscosity hydrocarbon fluid in a turbulent flow mode, while its upper end is connected to the flow tank 1, and the bottom through the solenoid valve 5 to the receiving tank 7. A time relay 6 is connected to the solenoid valve 5, which allows you to set the length of time during which the solenoid valve 5 will be open. The rheometer also includes a technical scale (not shown) for measuring the mass of liquid passing through the tube 4 of small internal diameter into the receiving tank 7 for the length of time during which the electromagnetic valve 5 was opened. Elements of the turbulent rheometer are mounted on a tripod 8.

The main difference of the proposed turbulent rheometer is that instead of measuring the expiration time of a fixed volume of liquid, the mass of the outflowing liquid is measured over a given period of time, which is set using a time relay 6 connected to the electromagnetic valve 5. Thus, the measurement of the volumetric flow rate of the liquid is replaced by the mass measurement expense. In this case, the formation of a two-phase system during fluid leakage and mixing with air bubbles does not affect the reliability of the measurements.

In addition, the proposed turbulent rheometer implements free flow of fluid under the action of gravitational forces. This eliminates the need to use a can of compressed gas and a receiver contained in the structure of the closest analogue, which greatly simplifies the design. In order for the pressure to be constant during free flow of liquid, the Mariotte 3 tube is used in the proposed design. Moreover, the tube 4 has a small internal diameter, the length of which is from 80 to 150 cm, and the diameter is from 1.5 to 6.5 mm, the turbulent mode flows (with Reynolds numbers Re> 4000) are realized only for liquids whose viscosity does not exceed 1.3 cSt. This viscosity range includes most organic solvents, water, and aqueous-organic mixtures.

A method for determining the effectiveness of PTP is as follows.

A low-viscosity hydrocarbon liquid is poured into the supply tank 1 through a ball valve 2 and the ball valve 2 is closed to maintain a constant pressure in the supply tank 1 when the fluid flows from it. Then set by the timer 6 the length of time during which the electromagnetic valve 5 will be open. This time period is preferably in the range of 15-25 seconds. The liquid under the action of gravity begins to flow through the tube 4 of small internal diameter in a stationary mode of turbulent flow.

After that, the opening of the electromagnetic valve 5 is started and the pre-weighed receiving container 7 is filled with liquid for a predetermined period of time. In this case, the discharge pressure is kept constant using the Marriott tube 3. After the automatic operation of the timer 6, the electromagnetic valve 5 closes. The filled receiving tank 7 is weighed on a technical balance and the mass of liquid is determined without PTP.

Then, a low-viscosity hydrocarbon liquid is introduced into the anti-TB agent in a certain concentration and all the above steps are performed to determine the mass of the liquid with the anti-TB agent introduced in the same period of time. The decrease in the hydrodynamic resistance DR after the introduction of PTP in a certain concentration is calculated by the formula (1).

The above steps of the method are performed for a number of PTP concentrations in a low-viscosity hydrocarbon liquid, determining for each PTP concentration the magnitude of the decrease in the hydrodynamic resistance DR. After that, the dependence of the magnitude of the decrease in the hydrodynamic resistance DR on the value of the concentration of the anti-TB agent is obtained and the effectiveness of the anti-TB agent is evaluated by the obtained dependence.

Below is an example to assess the effectiveness of anti-TB drugs in hydrocarbon fluids.

Example

Pure nefras C2 with a volume of 700 ml (469 g) was poured through an open ball valve into the flow tank of a turbulent rheometer with a solenoid valve locked. A tube of small internal diameter (capillary) was taken with a length of 110 cm and a diameter of 4 mm. Then the ball valve was closed, the time relay was set for 20 s, the receiving tank was weighed and installed under the tube outlet. The solenoid valve was opened for 20 s, the filled receiving tank was weighed and the mass of the leaked liquid m _{0 was} determined. She was 251.6 g.

The same was done with a solution of a sample of anti-turbulent additives (PTP) in nephras C2 at a concentration of 2 ppm (0.0002%). The mass of the _PTP solution m that leaked over 20 s was 294.9 g.

Substituting the values of m ₀ and m _PTP in the formula (1), we obtained the value of the decrease in resistance DR equal to 27.2%.

Then, according to the same scheme, the DR values were determined for solutions of the same PTP sample with concentrations of 1, 4, and 8 ppm, after which the dependence of DR on concentration C was plotted for this additive (Fig. 2).

This curve characterizes the quality of the additive in the given flow conditions, and it can be used for comparison with the data obtained for PTP samples of other manufacturers in the same flow conditions.

Claims (5)

1. A turbulent rheometer, characterized in that it contains a flow tank mounted on a tripod, equipped with a Mariotte tube to maintain a constant pressure in the flow tank when the fluid flows from it, and a ball valve is located in the upper part of the flow tank to receive a low-viscosity hydrocarbon liquid or low-viscosity hydrocarbon liquids with an anti-turbulent additive (PTP) introduced into it in a certain concentration; a tube of small internal diameter for the passage of a low-viscosity hydrocarbon fluid in a turbulent flow regime, the upper end of which is connected to the supply tank; an electromagnetic valve located at the lower end of the tube of small internal diameter, configured to set the length of time during which it will be open, by means of a time relay connected to it; a receiving tank, the input of which is located under the lower end of the small internal diameter tube exiting the solenoid valve, and a technical balance for measuring the mass of liquid passing through the small internal diameter tube into the receiving capacity for the length of time specified by the time relay. 2. The turbulent rheometer according to claim 1, characterized in that the tube of small inner diameter is a tube of metal, plastic or glass, the length of which is 80-150 cm, and the inner diameter is 1.5-6.5 mm. 3. The turbulent rheometer according to claim 1, characterized in that the low-viscosity hydrocarbon liquid has a viscosity of less than 1.3 cSt. 4. The turbulent rheometer according to claim 1, characterized in that the length of time during which the electromagnetic valve is open is preferably in the range of 15-25 seconds. 5. A method for determining the effectiveness of an anti-turbulent additive (PTP), implemented by means of a turbulent rheometer according to paragraphs. 1-4, characterized in that a low-viscosity hydrocarbon liquid is poured into a consumable container equipped with a Mariotte tube through a ball valve, the ball valve is closed to maintain a constant pressure in the consumable container when the fluid expires, set the time interval by means of a timer whose solenoid valve will be open, and start the opening of the solenoid valve, fill the pre-weighed receiving tank with liquid for a given period of time, close the electric the solenoid valve by automatically activating the time relay, weigh the receiving container with the liquid on a technical balance and determine the mass of clean liquid, perform the above actions after introducing the PTP in a low-viscosity hydrocarbon liquid at a certain concentration and determine the mass of the liquid with the PTP introduced into it, calculate the decrease in hydrodynamic resistance after the introduction of PTP in a certain concentration according to the following formula:

,
where m ₀ is the mass of a low-viscosity hydrocarbon fluid that has passed into the receiving tank for the length of time specified by the time relay, m _PTP is the mass of the liquid with the introduced PTP that has passed into the receiving tank for the same length of time specified by the timer; perform the above actions for a number of concentrations of PTP in a low-viscosity hydrocarbon liquid; evaluate the effectiveness of PTP, obtaining the dependence of the magnitude of the reduction in hydrodynamic resistance on the concentration of PTP.

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