RU2362053C1 - Method for protection of submerged centrifugal pump stage parts against scale - Google Patents

Abstract

FIELD: engines and pumps.

SUBSTANCE: invention is related to hydraulic machine building. Method consists in application of polymer coating on previously prepared metal surface of every stage part by means of its submersion into polymer solution with its further polymerisation. At that part in polymer solution is rotated around its axis in direction that mostly coincides with direction of liquid flow motion in flow channels of centrifugal pump during its operation in pumping mode. Previous preparation of every pump stage part is carried out by means of generation of micro- and macro-relief on surface. Formation of macro-relief on working surface of stage part is carried out either under action of centrifugal force created by alternate rotation of part clockwise and counterclockwise in liquid-abrasive medium, or by creation of honeycomb structure by means of pressing, where cell size is less than flow section of stage flow path. Formation of micro-relief on surface of powder part is done by control of pore size by variation of pressing force and application of powder with different particle size.

EFFECT: provision of submerged centrifugal pump stage parts against scale.

6 cl, 1 dwg

Description

The invention relates to hydraulic engineering and can be used to protect the working bodies of submersible centrifugal pump units, from the harmful effects of operational deposits, in particular from scaling, when the equipment is operated in complicated well conditions.

In the process of pumping formation fluid from wells on the inner surface of the parts of the centrifugal pump stages, namely in the flowing parts of the impellers and guide vanes, salt deposition occurs, leading to the emergence of additional hydraulic resistance, which, in turn, limits the flow of pumped pump fluid and reduce its performance up to a complete stop.

It is known to use an inhibitory coating to prevent the formation of operational deposits of a solid and viscous product on the working surface of industrial equipment made of metal, and a method for its production (see, for example, description of the invention to RF patent No. 2269557 C2, C09D 127/18 of 08/15/03 ) The said patent describes a method for producing a coating, which involves applying a polymer to a working metal surface of a technological equipment after its preliminary machining and heating. The method provides the formation of a dense, adhesive, inhibitory coating, preventing the adhesion of operational deposits on the metal work surface of technological equipment.

However, the methods used for coating metal working surfaces described in the patent, namely, spraying, pouring, simple immersion of a part in a polymer solution, cannot provide a uniform coating layer on the inner surfaces of the working parts of the pump stage, which are the flow channels of the impeller and the guide centrifugal pump apparatus, which does not allow to obtain a stable protective coating, which allows to reduce the salt deposition rate on the working surfaces of the stage, then It is in those areas in which, basically, this process occurs.

There is also a method of dealing with the harmful effects of operating deposits on the surface of the working bodies of centrifugal pumps by applying polymer coatings by cathodic electrodeposition (see, for example, patent RU No. 52128, F04D 1/00, from 23.09.05).

The disadvantage of the method used in this patent is that the cathodic electrodeposition method is an expensive process and requires the use of sophisticated equipment. In addition, the coating itself obtained by this method is also unstable due to insufficient adhesion of the applied polymer coating with the metal of the parts (impeller and guide vane) of the centrifugal pump stage.

The objective of the invention is the application of a uniform coating layer on the metal surfaces of the parts (impeller and guide vane) of a submersible centrifugal pump stage, including their internal flow part, while achieving a high degree of coating adhesion to the metal and reducing the cost of the process.

The achievement of the technical result is ensured by the method consisting in applying a polymer coating to the pre-prepared metal surface of each part of the step of a submersible centrifugal pump by immersing it in a polymer solution followed by polymerization, according to the invention, the step part in the polymer solution is rotated around its axis, while the preliminary preparation of each part steps are carried out by forming on its working surface a macro- and / or microrelief.

Moreover, the rotation of each part of the stage in the polymer solution is carried out mainly with the passage of the polymer solution through the flow part of the part in the same direction as the pumped liquid in the pump operating mode.

Preliminary preparation of the part is carried out depending on the type of polymer coating used, using one and / or several of the following processing options.

The formation of the macrorelief on the surface of the pump stage part is carried out in a liquid-abrasive medium under the influence of centrifugal force created by rotating the part around its axis alternately in the clockwise and counterclockwise direction.

The formation of the macrorelief on the surface of the step part, made on the basis of powder materials, is carried out by creating a honeycomb structure during the pressing process, the cell size of which is smaller than the passage section of the flow part of the step.

The formation of the microrelief on the surface of the powder part of the stage is carried out during its manufacture, adjusting the pore size in the structure of the material in the range from 20 to 100 μm by changing the pressing force and the use of powder with different particle sizes.

In addition, depending on the type of polymer used, the part is heated to a temperature of 40-120 ° C before coating.

The essence of the proposed method for protecting parts of a submersible centrifugal pump stage from scaling is illustrated by a drawing, which schematically shows one of the possible variants of a device that implements the method.

The device consists of a tank 1, which is filled with a solution or dispersion of polymer 2. Inside the tank 1, a shaft 3 connected to the drive (not shown) is vertically mounted. The shaft 3 can be driven in rotation both from an independent drive, and from any machine in the cartridge of which the shaft end is clamped. On the shaft 3 is fixed the workpiece 4 (impeller or guide vane) of the submersible centrifugal pump stage, made with channels 5 forming the flow part of the stage.

Before applying the coating, in order to improve the adhesion of the polymer material to the metal of the part and to obtain a uniform coating polymer layer, special preparation of each part of the 4 stage is carried out by changing the macro- and microrelief of its treated surface. Moreover, depending on the used polymer coating material, the preparation of the surface of the step part is carried out using one of the following processing options or a combination thereof.

1. The formation of macrorelief on the surface is produced by the mechanical action of an abrasive. For this, part 4 is mounted on a vertical spindle and immersed in a liquid abrasive medium, consisting, for example, of iron-free sand with aluminum oxide. Further, the part is rotated around its axis alternately clockwise and counterclockwise (not shown in the drawing). Under the influence of the centrifugal force created by alternating rotation of the part, multidirectional risks are formed on its surface, which, when coating is applied, increases the adhesion of the coating material to the metal of the step part.

2. To prevent peeling of coatings formed in the form of a continuous solid film and clogging of the flow channels of the pump stage with its fragments on the surface of the part made of powder, a macro relief is formed in the process of pressing it, which is a honeycomb structure. In this case, the cell size in the formed honeycomb structure must be less than the passage section of the channels 5 of the flowing part of the stage (impeller and guide vane). This allows fragments of the coating, which may peel off during the operation of the pump, to freely pass through the flow part of the stage without clogging the pump channels. The shape of the cells can be arbitrary.

3. For powder parts obtained by impregnation, the necessary level of adhesion is achieved by the formation of a microrelief in the manufacture of the part by adjusting the pore sizes in the material in the range from 20 to 100 microns by changing the pressing force and the initial particle size of the powder.

Before applying the polymer coating, the step part is heated, thereby accelerating the diffusion of the polymer coating into the pores of the product material. The heating temperature of the part depends on the type of polymer coating used and can vary between 40-120 ° C.

To remove excess polymer and obtain a uniform coating layer on the stage guide vane, special axial or helical grooves up to 0.1 mm deep are applied uniformly across the entire surface of the step guide device, along which excess polymer flows (not shown).

After preparation for applying the polymer coating, the step 4 part is fixed on the shaft 3, lowered into the polymer solution 2 and the shaft 3 is rotated depending on the viscosity of the solution for 30-60 seconds at a rotation speed of 50-1000 rpm. In this case, the rotation of the shaft 3 together with the part 4 of the pump stage is carried out mainly in the direction corresponding to the passage of fluid through the flow channels 5 in the operating mode of the pump during pumping. Then part 4 is removed together with the shaft 3 from the polymer solution 2 and rotated for another 10-40 seconds to remove excess coating. The coating is dried on the same shaft 3 at a rotation speed of 560-1800 rpm, depending on the required thickness of the polymer layer. You can get a layer with a thickness of 40-60 microns to 120-140 microns. Due to the action of centrifugal forces, the polymer film fills the flow channels in the impeller and guide vane of the submersible centrifugal pump stage, ensuring its uniform distribution over the thickness on the entire inner surface of the part. The drying time of the polymer coating varies depending on the rotation speed from 15 seconds to 5 minutes.

Further heat treatment of parts is carried out in accordance with the instructions for the use of polymer coatings.

If it is necessary to intensify the coating process, it is possible to simultaneously fix on the shaft 3 parts 4 (impellers or guide vanes) of several stages of a submersible centrifugal pump.

To maintain a uniform consistency of the solution when using a dispersion of polymer powders in water, the tank 1 can be equipped with a spatula mixing device mounted on the bottom of the tank (not shown in the drawing).

The proposed method of protecting the details of the stages of a submersible centrifugal pump from scaling allows an additional 30% reduction in the rate of scaling in the flowing parts of the details of the stages of a submersible centrifugal pump, which increases its productivity and service life.

In addition, the implementation of the method does not require expensive equipment and significant material costs.

Claims (6)

1. A method of protecting the details of the stage of a submersible centrifugal pump from scaling, which consists in applying a polymer coating to the previously prepared metal surface of each part of the pump stage by immersing it in a polymer solution and subsequent polymerization, characterized in that the part of the pump stage is rotated around its axis, with the preliminary preparation of each part is carried out by forming on its working surface macro- and microrelief. 2. The method according to claim 1, characterized in that the rotation of each part of the stage in the polymer solution is carried out mainly with the passage of the polymer solution through the flow part of the part in the same direction as the pumped liquid in the pump operating mode. 3. The method according to claim 1, characterized in that the formation of the macrorelief on the working surface of the step part is carried out in a liquid-abrasive medium by the action of centrifugal force created by alternating rotation of the part in a clockwise and counterclockwise direction. 4. The method according to claim 1, characterized in that the formation of a macrorelief on the surface of the step part made on the basis of powder materials is carried out by creating a honeycomb structure by pressing, while the cell size in the honeycomb structure is smaller than the passage section of the flow passage of the step. 5. The method according to claim 1, characterized in that the formation of the microrelief on the surface of the powder part of the stage is carried out during its manufacture, by adjusting the pore size in the material structure in the range from 20 to 100 microns by changing the pressing force and the use of powder with different particle sizes. 6. The method according to claim 1, characterized in that, depending on the type of polymer used, before applying the coating, the step detail is heated to a temperature of 40 ° -120 ° C.