RU2806459C1 - Device for thermal abrasive treatment of surfaces of products and materials - Google Patents

Abstract

FIELD: heat treatment.

SUBSTANCE: device for thermal abrasive treatment of surfaces of products and materials. The device contains a burner having a pipe-shaped body, inside of which a combustion chamber is formed on the rear side of the body with liquid fuel and air supplied into it through separate channels, inside which an igniter of the fuel mixture is located and at the outlet of which there is a nozzle with a narrowing of the passage channel at the inlet and expansion of this channel at the output. The channel of this nozzle communicates with the cavity of the receiving chamber, made in the form of an ejector for suction of powder or liquid material supplied through a separate channel and thrown towards the processing surface. At the exit from the ejector, a particle accelerator of the specified material, which is made in the form of a Laval nozzle, is installed coaxially with it. The combustion chamber is separated from the housing wall by a metal shell stretched along the combustion chamber wall to form a first annular cavity along the combustion chamber wall and a second annular cavity communicated with the first and formed between the shell and the housing wall. The igniter is made in the form of a nozzle connected to the liquid fuel supply channel and a glow plug.

EFFECT: speed of movement of material particles in the heated gas flow increases at the exit from the burner.

4 cl, 7 dwg

Description

The invention relates to jet thermal abrasive processing of surfaces of products and materials and concerns the design of a device for cleaning the surfaces of products and applying heat-resistant coatings to the surface of the material, etc.

To clean surfaces and prepare them for coating, the thermal abrasive method is used, which consists of simultaneous thermal and shock-abrasive effects on the surface with a two-component supersonic high-temperature jet consisting of a gas flow and particles of abrasive material. Thermal abrasive cleaning is an analogue of abrasive blasting (sandblasting), the difference is in temperature and gas flow rate. This technology exposes the surface to be cleaned to a high-temperature supersonic jet carrying particles of abrasive material.

The gas jet is formed by combustion products of fuel burned in compressed air in the combustion chamber of the burner. The burner ensures the introduction of abrasive particles into the gas flow and is equipped with an accelerating channel that allows them to be accelerated to the highest possible speeds. The characteristic values of the velocity and temperature of the gas phase of the flow in the outlet section of the accelerating channel are 1250 m/s and 1400 K, respectively. In this case, the speed of abrasive particles is 100-300 m/s, depending on their fraction and origin. The speed of particles is 2.5-3.5 times higher than the speed during traditional jet-abrasive processing, and the energy of impact with the surface is 6-10 times higher, respectively. It is the high kinetic energy of abrasive particles that determines the effectiveness of thermal abrasive cleaning technology. The technology makes it possible to clean metal surfaces from all types of contaminants and deposits, such as metallurgical scale, corrosion products, paint, galvanic and gas-thermal coatings, lime and other deposits. With the thermal abrasive cleaning method, degreasing, dust removal and activation of the surface are simultaneously ensured, which eliminates the need for any additional operations before applying coatings of any type. After cleaning using thermal abrasive technology, the surface becomes uniformly rough, degreased, and heated to a temperature of 50-60°C. and chemically active. Such surface properties provide a high degree of adhesion to the protective coating applied to it.

A device is known for thermal abrasive cleaning of product surfaces, containing a separate container with an oxidizer, a container with liquid fuel, a container with abrasive powder and a burner containing paths for supplying oxidizer, fuel and abrasive particles supplied through hoses from the corresponding containers, a pre-chamber, a combustion chamber, a nozzle and an igniter and a receiving chamber for abrasive particles installed at the exit from the nozzle and coaxially with it, made in the form of an ejector, at the exit of which a gas-dynamic accelerator of abrasive particles is installed coaxially with it, made in the form of a cylindrical pipe, the geometric dimensions of which are selected from the conditions eliminating the formation of shock waves inside the accelerator, which slow down the gas flow to a speed lower than the speed of sound, and heating of abrasive particles until they transform into an amorphous state (RU 2201329, B24C5/04, published on March 27, 2003).

This solution was adopted as a prototype.

The oxidizer and fuel enter through the supply paths into the pre-chamber and combustion chamber, in which, after the igniter is triggered and the burner enters operating mode, the combustion process of the fuel components occurs. The resulting combustion products flow through a supersonic nozzle into the ejector vacuum cavity. Closing onto the cylindrical surface of the ejector, the supersonic jet PS creates a vacuum in the ejector cavity, necessary for the stable supply of abrasive particles along the supply path, provided that the pressure in the abrasive supply tank is equal to the ambient pressure. Thus, the supply of abrasive particles is carried out due to the pressure difference in the abrasive supply tank and in the ejector, and the operation of the burner is not related to the supply of abrasive. At the outlet of the ejector, a gas-dynamic accelerator of abrasive particles is installed coaxially with it in the form of a cylindrical pipe, the geometric dimensions of which are made in such a way that there is a supersonic gas flow throughout its entire length.

The disadvantage of the known device is the use of a pipe in the form of a tubular cylinder as a gas-dynamic accelerator of abrasive particles.

Acceleration of abrasive particles in such a gas-dynamic accelerator will take place if the gas velocities in it are maximum, and therefore supersonic (U-800...1700 m/s). These parameters are obtained on a nozzle that has a narrowing in the lumen. As for the cylindrical pipe, it is indicated that its geometric dimensions must be selected to exclude the formation of shock waves inside the accelerator, which decelerate the gas flow to a speed lower than the speed of sound, and heating of the abrasive particles until they transform into an amorphous state.

In the tapering subcritical section of the nozzle, gas movement occurs at subsonic speeds; in the narrowest, critical section of the nozzle, the local gas speed reaches sonic speed, and in the expanding supercritical section, the gas flow moves at supersonic speeds. Moving through the nozzle, the gas expands, its temperature and pressure drop, and its speed increases. The internal energy of the gas is converted into the kinetic energy of its directed motion. When leaving the nozzle into the ejector chamber, the gas captures abrasive particles and moves them along the channel of the cylindrical pipe. In this case, the pressure in this pipe drops (due to braking during friction of the abrasive against the pipe wall, the wall zone of turbulent movement of the mixed flow) and the speed at the exit from the cylindrical pipe decreases. This can lead to shock waves, followed by an increase in gas temperature and pressure and a decrease in gas velocity to a value less than the speed of sound (400-650 m/s). The presence of shock waves inside a gas-dynamic accelerator of abrasive particles leads to a decrease in the speed of particles at the exit from it and, as a consequence, to a decrease in the efficiency of cleaning product surfaces.

In addition, the surface area treated by this known apparatus depends on the length of the hoses. After cleaning a surface area, when moving to another area, it is necessary to move containers with agents. At the same time, the device requires a sufficiently large area to deploy it at the workplace. Such a device works well and effectively when the workpiece is brought to it or placed next to it, but it becomes inconvenient when it is necessary to clean, for example, metal bridge structures or fences, when working with which the surfaces on the site are cleaned quickly, and moving the device with one section of a cleaned surface to a section of an uncleaned surface takes a lot of time. This requires disconnecting the hoses and then reconnecting them, which is an unsafe operation when it comes to oxidizer and liquid fuel.

The present invention is aimed at achieving a technical result consisting in increasing the operating efficiency of the device by increasing the speed of movement of material particles in a heated gas flow at the burner outlet when carrying out operations for cleaning surfaces and applying metallized coatings to them and eliminating numerous operations on disconnecting/connecting supply hoses to the working agent burner.

The specified technical result is achieved by the fact that in a device for thermal abrasive processing of surfaces of products and materials, containing a container with air, a container with liquid fuel, a container with powder or liquid material, communicated with a burner, including a tube-shaped housing, inside which on the back side of the housing a combustion chamber is formed with the supply of liquid fuel and air into it through separate channels, inside which the igniter of the fuel mixture is located and at the exit of which there is a nozzle with a narrowing of the passage channel at the inlet and an expansion of this channel at the outlet, while the nozzle channel communicates with the cavity of the receiving chamber for liquid or particles of powder material, made in the form of an ejector for suction of the material ejected towards the processing surface, supplied through a separate channel, at the outlet of which an accelerator of particles of this material is installed coaxially with it, the accelerator of particles of powder material or liquid material is made in the form of a Laval nozzle, the igniter is made in the form of a nozzle connected to the liquid fuel supply channel and a glow plug, the combustion chamber is separated from the body wall by a metal shell stretched along the wall of the combustion chamber to form a first annular cavity along the wall of the combustion chamber and a second annular cavity communicated with the first and formed between the shell and the wall of the housing for supplying air under a pressure of 7-9 bar into the cavity near the combustion chamber and cooling the adjacent nozzle, while these containers are placed on a movable frame on which a compressor is mounted, communicating with the air container in the form of a receiver, communicating with a fitting fixed to the frame, a container with liquid fuel is fixed to the wall of a container for powder or liquid material, which is connected to another fitting fixed to the frame, and the burner channels are connected to the said fittings and the container with liquid fuel by hoses, which are twisted and placed on a fitting fixed to the frame bracket together with the burner. And the material thrown towards the treatment surface can be particles of abrasive material in the form of a powder or particles in the form of a powder of metals with a lower electrical potential in relation to the electrical potential of the surface being treated.

And on the side wall of a container with abrasive material or liquid fuel, a container with metal powder with a lower electrical potential in relation to the electrical potential of the surface being treated can be fixed.

These features are essential and are interrelated to form a stable set of essential features sufficient to obtain the required technical result.

The present invention is illustrated by a specific example of implementation, which, however, is not the only possible one, but clearly demonstrates the possibility of achieving the required technical result.

In fig. 1 - general view of the device for thermal abrasive surface treatment, first version;

fig. 2 - the same as in Fig. 1, front view;

fig. 3 - the same as in Fig. 1, side view;

fig. 4 - general view of the device for thermal abrasive surface treatment, second version

fig. 5 - general view of the device for thermal abrasive surface treatment, third version, view from one side;

fig. 6 - the same as in Fig. 5, view from the other side.

fig. 7 - longitudinal section of the burner showing structural elements.

According to the present invention, the design of a device for thermal abrasive processing of surfaces of products and materials is considered: cleaning and spraying metallized coatings in heat treatment mode. Particles of abrasive material in the form of a powder (for example, quartz sand) or particles in the form of a metal powder (Zn, Al) with a lower electrical potential relative to the electrical potential of the metal surface being processed or a liquid agent can be considered as material particles thrown towards the processing surface. containing additives, which at high temperature and speed enters into physical interaction with the metal, penetrating into its crystal lattice and leaving a firmly adherent protective layer.

Structurally, the claimed device contains a frame 1 of a rod structure (Fig. 1-3 and 5, 6) (can be covered with a casing, Fig. 4), installed on the supporting surface of the workplace on wheels 2 (Fig. 2, 3, 4-6) . In any embodiment, the frame 1 becomes movable either by means of a lift or fork conveyor or independently on wheels. This frame contains a container with air, a container 3 with liquid fuel, a container 4 with powder or liquid material, which are pneumatically connected to the burner 5. Two fittings 6 are fixed in the bottom part of the frame (Fig. 4), equipped with valve-type shut-off valves. A hose 7 is connected to one fitting, connected to a container 4 for powder or liquid material, and a hose 8 (Fig. 4) is connected to the other fitting, connected to a receiver connected to a compressor (the receiver with a compressor is not shown), which is located on the frame.

On the wall of the container 4 with powder or liquid material there is fixed a container 3 with liquid fuel (Fig. 3), connected by a pipeline to the fuel supply channel to the burner. And the burner channels are connected by hoses 7 and 8 with the indicated fittings 6 at their other end and in the initial position, when the frame is not in use or moving, they are placed in a twist together with the burner on a bracket fixed to the frame. During operation, the burner is removed from the bracket, the hoses are straightened and the device is ready for use.

A control unit 9 for on/off control and material distribution is mounted on the frame or on the wall of the container.

On the side wall of the container with abrasive material or liquid fuel, an additional container 10 with metal powder with a lower electrical potential relative to the electrical potential of the treated surface can be fixed (Fig. 4-6).

The burner (Fig. 7) for the device for thermal abrasive treatment of the surfaces of products and materials contains a tubular-shaped housing 11 made of metal, inside of which, on the back side of the housing, a combustion chamber 12 is formed with the supply of liquid fuel and air into it through separate channels 13 and 14, respectively. The combustion chamber is tubular in shape with perforations in the side wall. A nozzle 15 for introducing liquid fuel and a glow plug 16, related to the igniter of the fuel mixture, are fixed in the end wall of the combustion chamber and at the same time in the body of the housing (inside the chamber). The nozzle communicates with channel 13 for supplying liquid fuel and provides an aerosol supply of fuel to the combustion chamber.

At the exit of the combustion chamber there is a nozzle with a narrowing of the passage channel at the inlet and an expansion of this channel at the outlet, which represents the first Laval nozzle 17.

The combustion chamber is separated from the housing wall by a metal shell 18, stretched along the wall of this chamber to form a first annular cavity along the wall of the combustion chamber and a second annular cavity communicated with the first and formed between the shell and the housing wall. Air is supplied to the outer cavity at a pressure of 7-9 bar from the compressor receiver. In the area where these cavities communicate, the first Laval nozzle is located so that when air is supplied under pressure into the cavity near the housing wall, the air passes through this cavity, cools the shell, passes further, bends around the body of the Laval nozzle, cooling it, and then enters the cavity near the combustion chamber , from which it enters the combustion chamber through perforations.

The choice of pressure of the supplied air into the combustion chamber is determined by giving the ignition process of the fuel mixture characteristics similar to the process of ignition of the mixture in a diesel engine. The mixture is ignited by a glow plug. The method of igniting fuel in a burner is similar to the method of igniting fuel in a diesel engine cylinder. In a car engine, the piston rises upward, thereby sharply compressing and simultaneously increasing the temperature of the fuel-air mixture, which, in the presence of an additional heat source in the form of a glow plug, ignites the mixture. At a pressure of 7-9 bar, a pressure is created in the chamber, similar to the pressure of the piston in its upper position in the cylinder. Air is supplied from the compressor receiver by opening a quick-acting valve on the installation and moves at high speed through the channel to the burner. Along the way there is a hole in the first Laval nozzle, but due to its small size, this hole in the nozzle is considered as a throttle, that is, resistance that ensures an increase in pressure in the chamber.

This is also facilitated by the fact that a stoichiometric combustible mixture is formed in the chamber at the moment of ignition (when there is exactly as much oxidizer as is necessary for complete oxidation of the fuel).

Next to the first Laval nozzle 17 and along the direction of the combustion gas products, there is a receiving chamber 19 for abrasive particles or metal powder. This chamber is made in the form of an ejector for sucking particles of powder material supplied through a separate channel 20 and thrown towards the treatment surface. Upon exiting the first Laval nozzle 17, the high-velocity gas flow forms an area of low pressure relative to the pressure in the abrasive powder or powder metal supply channel. Due to this, a suction effect is formed, ensuring the flow of powder from the storage tank into the ejector cavity, where the powder is picked up by the gas flow and moves towards the outlet of the burner.

And at the exit from the ejector, a material particle accelerator is installed coaxially with it, made in the form of a second Laval nozzle 21, to which a cylindrical guide nozzle 22 is connected to organize the direction of the vector of powder mixed with gas.

The burner is used to create a supersonic jet stream. To do this, liquid fuel under pressure is supplied to the nozzle through the fuel supply channel: kerosene, white spirit, diesel fuel. Air is supplied through the air supply channel at a pressure of 7-9 bar. The air passes through the cavities formed by the shell, which allows you to simultaneously cool the first Laval nozzle and supply air to the combustion chamber. The mixture is ignited by a glow plug. Gas combustion products are formed in the combustion chamber, passing through the critical section of the first Laval nozzle, receiving additional acceleration, after which they enter the injector. The abrasive material or metal powders are fed into the injection chamber by injection using the suction of a large amount of air. This air performs two functions at once: as a transport medium for powders and abrasives and as an additional oxidizer of unburned fuel. That is, if, after passing through the first Laval nozzle, unburned fuel remains in the gas stream, obtained by excessively enriching the mixture in the combustion chamber, then it has the opportunity to burn out in the injection chamber and provide additional acceleration with the help of the second Laval nozzle.

The combustion products of the combustion chamber directly enter the first Laval nozzle and are accelerated (to supersonic speed). Powder from the powder supply channel is sucked into the gas flow of combustion products, heats up, and acquires a gas flow rate. In this case, the flow of powder causes a slight decrease in the gas flow rate. The mixture of powder and combustion product gases is directed to the second Laval nozzle, where the flow rate increases significantly. Passing the second Laval nozzle, the mixture flow passes through the cavity of the cylindrical guide nozzle and is transferred to the surface of the product to form a coating or cleaning (in the latter case, abrasive particles can be used as a powder, or the powder may not be introduced into the flow at all). In this case, the introduction of powder into a supersonic flow (into the supercritical part of the nozzle) into its zone with a pressure below atmospheric makes it possible to decouple the combustion chamber and the powder container (not shown) in pressure and burn fuel at high pressures without increasing the pressure in the powder container , which makes it possible to increase the efficiency of the burner by achieving higher temperatures and rates of combustion products. It should also be noted that transferring the flow through the speed of sound in supersonic Laval nozzles eliminates the formation of direct shock waves in the flow and thereby leads to a reduction in energy costs for processing products.

The present invention is industrially applicable and makes it possible to increase the operating efficiency of the device due to its mobility, compact placement of all units in a common frame area and due to the fact that the burner at the outlet has a speed of up to Mach 7 to move abrasive particles in a heated gas flow for carrying out operations. cleaning surfaces and applying metallized coatings to them.

The device is capable of operating at high powers of a thermal abrasive jet to clean surfaces from deep rust, bitumen build-up, cement and other surface contaminants until the main surface is completely cleaned and for further covering the cleaned surface with a protective layer of metal with a lower electrical potential (Zn, Al), which is supplied to powder form from a separate container. The possibility of working with liquids is provided (for processing the prepared surface). The liquid is supplied with a special additive, which at high temperature and speed enters into physical interaction with the metal, penetrating into its crystal lattice and leaving a firmly adherent protective layer. The device can be used as a stationary one, but it is possible to transport and move without any obstacles (except weight). Fully filled, the weight will be about 600 kg, and without contents 120 kg. A container with fuel and a fully filled container with cooper slag allows you to work for up to 4 hours without stopping.

Claims (4)

1. A device for thermal abrasive treatment of the surfaces of products and materials, containing a container with air, a container with liquid fuel, a container with powder or liquid material, communicated with a burner, including a tube-shaped housing, inside of which a combustion chamber is formed on the back side of the housing with a supply to it through separate channels of liquid fuel and air, inside which the igniter of the fuel mixture is located and at the exit of which there is a nozzle with a narrowing of the passage channel at the inlet and an expansion of this channel at the outlet, while the nozzle channel communicates with the cavity of the receiving chamber for liquid or particles of powder material , made in the form of an ejector for sucking powder or liquid material supplied through a separate channel, ejected towards the treatment surface, and at the exit from the ejector, a particle accelerator of the said powder or liquid material is installed coaxially with it, characterized in that said particle accelerator of the powder material or liquid material is made in the form of a Laval nozzle, the igniter is made in the form of a nozzle communicated with the liquid fuel supply channel and a glow plug, the combustion chamber is separated from the body wall by a metal shell stretched along the wall of the combustion chamber to form a first annular cavity along the wall of the combustion chamber and a second annular cavity communicated with the first and formed between the shell and the wall of the housing for supplying air under a pressure of 7-9 bar into the cavity at the combustion chamber and cooling of the adjacent nozzle, while the specified containers with air, with liquid fuel and with powder or liquid material are placed on a movable frame on which a compressor is mounted, communicating with an air container in the form of a receiver, communicating with a fitting fixed to the frame, a container with liquid fuel is fixed on the wall of a container for powder or liquid material, which is in communication with another fitting fixed to the frame, and the mentioned channels The burners are connected to the indicated fittings and the container with liquid fuel by hoses, which are twisted and placed on a bracket fixed to the frame together with the burner. 2. The device according to claim 1, characterized in that the material thrown towards the processing surface is particles of abrasive material in the form of a powder. 3. The device according to claim 1, characterized in that the material ejected towards the treatment surface is particles in the form of metal powder with a lower electrical potential in relation to the electrical potential of the surface being treated. 4. The device according to claim 1, characterized in that on the side wall of a container with powdered material in the form of an abrasive or a container with liquid fuel, a container with metal powder with a lower electrical potential is fixed in relation to the electrical potential of the surface being treated.

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