RU2272682C2 - Underwater centrifugal spraying head - Google Patents

Abstract

FIELD: spraying equipment for building, particularly spraying heads adapted to apply protective cement-sand coating on inner pipe surface to protect thereof against corrosion and abrasion.

SUBSTANCE: spraying head comprises body made as container with cement-sand mix to be expelled through orifices made in container walls via pipes. The pipes are arranged in pairs and have free ends bent one towards another so that effluent jets impinge one against another at pipe wall to break sand particles and to increase sand particle surface areas, which results in irregular areas forming and in increase of cohesion ability of small and large particles. Coating surface may be smoothed out by spring-loaded smoothing means rotated by spraying head.

EFFECT: high coating strength and resistance to abrasion approximately equal to that of metal, as well as increased working ability.

3 cl, 2 dwg

Description

Use: for applying a protective coating in the field of construction. The essence of the invention: in the drive centrifugal spray head of the tube are fixed in pairs in the body, and their free ends are bent towards each other so that the intersection points of the axes of the outlet openings of the tubes are placed on the inner surface of the pipe.

The invention relates to construction, in particular to devices for applying a protective coating to the inner surface of the pipeline.

Known devices for applying a protective coating to the inner surface of the pipeline, including a container for the coating material and a pneumatic spray head [1].

The disadvantages of this device include the fact that the pneumatic spray head does not provide a uniform coating thickness, requires a significant consumption of material and does not allow the application of viscous and quick-hardening coating materials.

Known devices in which the spraying of the mixture is achieved due to the centrifugal forces arising from the rotation of the cylindrical body - the capacity of the spraying head, through the through slits of which are placed at an angle to the axis of the body, and along the radial outer vanes intersecting the slots, the sprayed mixture expires and falls on the inner surface of the pipe [2].

The disadvantage of this device is that all particles of the mixture material fly out from the ends of the blades at the same speed, and during the flight time of the particles they are separated depending on the weight. The heaviest and sharpest particles are ahead of the small particles, first hit the pipe wall, bounce off of it and fly towards the small ones, slow them down, as a result of which the coating is loose, of poor quality, which can lead to its destruction during operation.

Known devices [3], in which the centrifugal spray head contains a cylindrical body - a container with slots in the wall of the head, made at an angle to the axis of the head. All geometric and kinematic characteristics are selected experimentally. The head acts as a centrifugal nozzle spraying the mixture fed into it. Through the slots in the housing, the mixture flows out and enters the walls of the blades and, under the action of centrifugal forces, flows through them. The flow rate depends on the time the mixture was on the wall. With increasing blade height, the flow rate of the mixture from the ends of the blades increases. To obtain a coating of better quality than already known, the head blades are made with different heights along their length - conical or step, for example, their two degrees, high and low. The height of the low step is such that the entire mass of the mixture flying from the end of this blade reaches the pipe wall and is fixed on it due to the adhesion of the mixture particles to the pipe surface.

A low scapula follows a high one, and a mixture flies from it, being divided into large particles and small particles during the flight. The speed of movement of large and small particles is greater than that of particles flying from the low part of the scapula. Rapidly flying particles, hitting a layer deposited by a low blade, compact it not only with their entire mass, but also with large particles that penetrate to great depths and compress the mixture on the wall.

A significant disadvantage of the known drive centrifugal spray heads is that they do not fully realize all the advantages of centrifugal sawing devices due to the fact that the exposure time of the centrifugal force to accelerate the mixture on the surface of the blades is limited, and the efficiency . this exposure is low. Because of this, the maximum acceleration speed of the particles of the mixture is below the possible limit.

Large hydraulic losses along the internal path of the saw head lead to low efficiency of power consumption for achieving the speed of the mixture at the outlet of the head. Swirling the mixture in the head tank, passing the mixture through the slots, changing the direction of the mixture in the slots, flowing the mixture along the surface of the blades are the main areas of loss of speed of the mixture before it hits the pipe surface. During the flow of the mixture along the surface of the blade, the flow of the mixture is inhibited, rather than accelerated, because the stream is in contact with the rotating blade only on one side of its perimeter.

The problem solved by this invention is to obtain a coating capable of withstanding the most difficult hydraulic modes of fluid flow with different abrasive particles.

This problem is solved by performing a spray device in the form of a container, in the walls of which holes are made with tubes installed in them perpendicular to the axis of the container. The tubes are installed in pairs and their free ends are bent towards each other so that the intersection point of the axes of the outlet openings is on the surface of the tube. This ensures the collision of the jets, so that the relative velocity of the sand particles increases almost twice without the additional cost of energy to accelerate the mixture flow. This increase in the speed of impact provides a crushing of sand particles to such sizes that were unattainable with the existing method of applying a cement-sand mixture in the prototype. Such crushing provides a very strong coating of the pipes, and therefore, the protective qualities of the coating are increased, because the coating becomes monolithic and approaches the metal in strength.

This design of the head ensures the achievement of a technical result, which is manifested in the fact that the coating over its entire thickness is extremely dense, high-quality, which ensures high performance and long life of the pipeline with such a coating.

Figure 1 shows a front view of the head, figure 2 is a side view of the head.

The drive centrifugal spray head 1 comprises a cylindrical body-container 2 with holes 3 in the head wall drilled along the radius to the axis of the head. The diameter of the holes is made equal to the outer diameter of the nozzle tube 4. The diameters of the tubes, the holes in them and all other geometric dimensions, as well as the length of the tubes and their number are selected experimentally depending on the physical characteristics of the mixture. Tubes 4, their length, the number in one section along the length of the head, the number of sections, as well as the number of revolutions of the shaft 5 of the drive 6, physicochemical properties and flow rate of the mixture supplied through the pipeline 7 are selected experimentally. The criterion for evaluating the efficiency of the head is the performance and service life of the coating.

The head 1 operates as a centrifugal nozzle spraying the mixture supplied to it. The container body 2 is rotated by the drive 6 through the shaft 5. Through the openings 3, the mixture flows out through the channels of the tubes 4, which are fixed in the housing 2 so that their outlet openings are opposite each other at each pair of tubes, and when the mixture expires from each pair of tubes collision of jets on the surface of the pipe wall. The collision velocity is 2 times the velocity of the mixture in each tube. By changing the length of the tubes regulate the rate of flow of the mixture from the tubes.

The execution of all tubes of the spray head of the same length will give the best results in coating strength, as the coating will be multilayer, and all layers will have maximum strength due to the laying of the mixture with the maximum achievable speed of the mixture flows colliding on the pipe wall. This speed could not be achieved with any of the known spraying devices.

All the advantages achieved with the proposed method of coating and design of the saw head are provided while simplifying the design of the saw head, reducing power costs by increasing the hydrodynamic quality of the hydraulic system and simplifying the requirements for sand classifiers, because practically any quality sand (by size) will provide the highest quality of the coating due to the achievable particle collision velocities at the nozzle exit. At these speeds, all grains of sand are crushed to form sharp edges, rough planes and minimal sizes, which were unattainable with all known methods of supplying the mixture to the pipe surface. The axis 8 of the nozzles 4 intersect at points O in each section along the length of the head. Points O are on the inner surface of the pipe. Placing pairs of nozzles in each of the sections I-I - V-V opposite to each other ensures the achievement of all the above advantages in terms of coating quality.

The entire mixture from the head is laid evenly on the pipe wall and compacted with each subsequent layer, resulting in a dense, high-quality coating that can work reliably in any severe hydraulic, thermal and abrasive conditions existing in practice.

To increase the operability of the coating, its surface can be further leveled by smoothing machines driven by rotation from the spray head.

Information sources

1. A.S. USSR No. 263443, class B 05 C 7/08, 1970.

2. A.S. USSR No. 531552, class B 05 C 7/08, 1976.

3. RF patent No. 2095159, cl. B 05 C 7/08, 1996.

Claims (3)

1. Drive centrifugal spray head for applying a protective coating on the inner surface of the pipe, including a cylindrical body-container with through holes made perpendicular to the axis of the body along its entire length, characterized in that the holes are fixed in pairs located tubes, the free ends of which are bent towards each other to a friend so that their axes intersect on the inner surface of the pipe. 2. The head according to claim 1, characterized in that the tubes are made conical and the bases of the cones are mounted on the housing. 3. The head according to claim 2, characterized in that the tubes are made of wear-resistant material.

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