FI73371B - METHODS FOER SEPARERING AV AVLAGRINGAR, SOM BILDATS PAO STRUKTURERS VAEGGYTOR UNDER PRODUKTIONSPROCESSEN ELLER VERKSAMHETEN. - Google Patents

Description

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SUOMI FINLAND

(FI) (21) Patent application-Patentan9ökning 331 * + / 72 (22) Application date-Ansökningsdag 23.11.72

Patent and Rector's Office (23) Start date - Giitighetsdag 23.11.72

Patent- och ragiateratyralaen (41) made public - Biivit offentiig 11.10.73 (44) Date of publication and of publication. -

Ansökan utlagd och utl.skriften publicerad 3 0.0 6.8 7 (86) Kv. application - Int. ansökan (32) (33) (31) Privilege claimed - Begärd priority 10.0 * 4.72

Ο7.Ο8.72 USSR (SU) 1764801, I813IOI

(71) (72) Igor Anatolievich Levin, Petrozavodskaya ulitsa, 15, building 1, kv. 113, Moscow, USSR (SU) (7 **) Oy Koi s te r Ab (5 * 0 Method for separating deposits formed on the wall surfaces of structures during the manufacturing process or operation -Metod för separering av avlagringar, som bildats pä strukturers vägg This invention relates to a method of separating deposits formed on the wall surfaces of structures during a manufacturing process or operation by providing an elastic deformation in the wall surfaces by applying to them energy impulses from an external source which cause a maximum of , 01 sec., Separated by time intervals that are at least ten times longer than the duration of the mechanical impulses and energy accumulates during the intervals between the impulses to obtain an impulse power that is many times the value of the energy source and is required for the mechanical impulse. to obtain one having sufficient amplitude to separate the deposits but not exceeding the value at which the mechanical stresses in the structure reach the fatigue limit, and wherein the rate of mechanical impulse formation ensures a deposition rate greater than the deposition rate but less than the p the impact velocity.

The method is most preferably used for cleaning equipment used in the chemical and food industries.

This method can also be used to clean machinery used in ore mines, to separate hard rock particles adhering to them, to separate foam or carbon particles from turbine blades, to clean railway freight wagons when they have been transported in bulk, etc.

Methods for removing solid deposits from structures are known in the art based on dissolving these deposits.

Methods for separating solid deposits by heating these structures are also known in the art.

In addition, the solid deposits are separated from the surface of the structures using flexible deformation of the surface to be cleaned. In this method, elastic deformations are achieved by direct mechanical shock applied to the surface to be cleaned or by continuous vibration of this surface.

None of these methods are effective enough and they are all very time consuming and labor intensive.

The equipment with which these methods are carried out, especially in connection with vibration cleaning, is clumsy, complex in design and cannot protect the surface to be cleaned against damage.

Devices for removing ice from thin-walled structures, in particular aircraft covers, are known from the prior art, in which case the flexible deformations obtained in said covers are used for this purpose. Flexible deformations are achieved in the coating by generating mechanical pulses when subjected to an electromagnetic field or fluid pressure.

Studies have shown that the flexible, deformation-induced deformation applied by a surface cleaner can also be used as a cleaning device in the chemical and food industries to remove deposits formed on surfaces during the manufacturing process and to clean machinery, railway wagons and other structures from accumulating on their surfaces.

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However, when equipment designed to remove ice from thin-walled coverings was used for this purpose, the results were not positive. Further investigation of the problem became necessary, especially with regard to the deformation of the deposits over their elastic limit and the conditions under which the fracture of these deposits is initiated. This study has identified some properties and operating parameters to provide the necessary impulses. Based on this study, parameters have also been determined that determine the probability of deposition separation and destruction by the impulse method.

As a result of the mentioned research work, the characteristic zone boundaries have been determined, which determine the optimal value of the impulses, which forms the basis of the proposed method.

The main object of the present invention is to develop a method by means of which the deposits formed on the surfaces of structures can be separated very efficiently, whereby the consumption of force supplied by an external source is as small as possible and the working time is as short as possible.

It is a particular object of the present invention to provide a method for separating deposits formed on the surfaces of structures by such elastic deformations provided by a cleaning agent, and to effect flexible deformation without impacting the surface to be cleaned with the result that the pre-brittle layers are destroyed and separated.

These objects are achieved by the method according to the invention, characterized in that before energy impulses are generated which are applied to the wall surface to be cleaned to separate the deposits, these deposits are converted to a solid state in which the adhesion between the deposits and the wall surface material critical impact speed.

It is suitable that the external action applied to the deposits is carried out in the form of a heat treatment, e.g. by calcination or cooling.

Calcination is suitable when the deposit contains at least two components, one of which is fusible and the other is solid and brittle.

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Cooling of several materials is preferred to reduce plasticity, i. to reduce the deposition rate of the deposit.

If the deposits have a loose or plastic structure, it is possible that the external action applied to the deposits is performed by mechanical cold working to compact the deposits.

It is also possible that an external effect on the deposits is exerted by an external pressure which causes the layers to recrystallize.

This embodiment has several advantages when used in closed containers in which plastic deposits have formed which move to a brittle phase during or after exposure to high pressure.

If the layers are not thick enough, they are covered with an additional layer of material that adheres to the layers to increase their thickness before the flexible deformation is used.

This embodiment is very advantageous when dealing with a thin layer which is flexible and which requires a very strong impulse to dispose of by making it brittle. By using an extra layer of brittle material that firmly adheres to the material of the layer, the force required to push is reduced.

It is also suitable that the external action on the deposits be carried out using a substance which reacts chemically or forms a solid solution with them. When these substances are used, it is possible to administer to different layers, e.g. for non-solids, those properties that are important for removing deposits by simple mechanical impulses.

Research has shown that an external effect can be applied to the strata by means of a liquid which solidifies when applied to the strata.

This embodiment has certain advantages when dealing with deposits consisting of a plurality of bodies which, when exposed to a cured liquid, form a unitary layer, which facilitates the removal of deposits by impulses.

If the surface to be cleaned is non-metallic, it is suitable to use a metal grate placed on said surface so that deposits form on the grate, which is removed together with the deposits after they have been treated with impulses.

5,7371 This embodiment is advantageous when an impulse treatment by means of an electromagnetic field is used to remove deposits from a non-metallic surface, if a metal grate is placed on said surface and a secondary current is induced in the grate.

It should be noted that in many cases the properties required to remove deposits from the surface are naturally achieved.

When using the method according to the invention, the surfaces of the structures can be effectively cleaned of practically any deposits which, before their removal, can be brought naturally or by force into a solid, brittle state.

In addition, this method allows the surface to be cleaned quickly without damaging it, using as little force as possible from an external source.

The invention will now be described in more detail with reference to its embodiments by means of the accompanying drawings, in which: Figure 1 shows a wall of a freight wagon and a device mounted close to the wall for generating electromagnetic field impulses; Fig. 2 shows a cross-sectional view along the line II-II in Fig. 1; and Figure 3 shows a chamber and a device mounted therein which provides pressure impulses in the liquid contained in the chamber.

The method of separating the layers formed on the surface of structures during operation is characterized in that the layers are brought into a solid, brittle state by an external effect, either by a natural effect or by forcing.

It is known that the nature of destruction is determined by the behavior of the substance (deposit) when it is loaded above the elastic limit. The behavior of a substance under these conditions can be expressed using Maxwell's relaxation equation:

& t “λ = ^ * e Y

where = stress on the substance at time t; ^ = elastic limit stress; & = initial load; e = base of natural logarithms; T = brewing time.

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From the above, another equation can be derived to determine the change in stress in matter: P- - A ft -, ^ - λ! i

dt dt t T

where A is the modulus of elasticity (for tension and compression it is equal to Young's modulus E).

^ = rate of deformation of the hull.

The value (-7)) η * / A, determined by the fading time and expressed in units of rate of deformation, is called the fading rate and describes the plasticity of the substance. In order to enhance the separation of the substance caused by the impulses, the latter would undergo brittle destruction and therefore the right-hand part of the formula should be considerably larger than the other. Thus, the highest possible value J £, i.e. the highest possible rate of deformation, must be obtained.

Experiments with several substances have confirmed the notion that plastic substances can also be made brittle and destroyed at a high rate of deformation.

However, the possibilities for adding a value are limited by the properties of the surface from which the material is separated: the rate of deformation should not exceed the critical impact velocity of the surface, i. the rate at which surface damage begins with impact.

Another property of the substance is related to the adhesion relative to the surface substance. Adhesion should not exceed the strength of the surface material so that the material is not spoiled when impacted.

Once the layers 1 (Figures 1, 2) on the walls 2 of the freight wagon have acquired said properties, a flexible deformation in the surface of the walls 2 of the wagon inside the cleaning agent is achieved by initiating simple mechanical impulses in said surface with a duration of less than 0.01 sec. by impulses that induce a secondary current in the metal parts of the carriage walls 2 (on the surface to be cleaned).

To generate the impulses of the electromagnetic field, a solenoid 3 is used, which is formed by bends of a metal wire without a metal core inside them. This solenoid is installed as close to the surface 2 to be cleaned as the operating conditions allow on the side of the deposits 1

II

7 73371 and is connected via an electrical impulse generator (not shown) to a non-power source such as a power grid. Solenoid 3 is attached to the carriage beams with fasteners 5 and 6.

It is also possible to mount the solenoid close to the surface to be cleaned on the side not covered by the deposits.

In the example given, the air acts as a medium for carrying the impulses.

When the electrical pulses separated by the time slots are passed through the solenoids, electromagnetic field pulses are generated which induce secondary electric currents in the metal parts of the surface. The interaction of the pulsating electric currents, first in the solenoid 3 and second in the surface 2, causes a momentary displacement of this surface opposite the solenoid 3, which displacement is characterized by high accelerations and velocities.

This mechanical deformation impulse on the surface 2 propagates like a wave from its origin to the entire cleaning agent.

Research has shown that high efficiency is obtained when the duration of the impulse does not exceed 1/4 of the natural oscillation period of the wall and structure. Given the stiffness of existing structures with a natural oscillation frequency of at least 30 Hz, the impulse duration is apparently not more than 0.01 sec.

The time interval between successive impulses is at least ten times longer than the duration of the mechanical impulse. Accumulation of energy occurs during this time interval to produce an impulse force that is many times greater than the power of the supply source. The force collecting means may be a capacitor included in the electric shock generator.

The acceleration of the surface points provided during the mechanical impulse should be sufficient so that the inertial force (equal to the product of mass and acceleration) of the solid-particle particles exceeds the adhesive force of these particles relative to the surface. It should be noted that the shear stress between the surface and the solid caused by the bending of the wall as the wave travels along the surface reduces the adhesion and reduces the required acceleration value.

The amplitude of the mechanical impulse should be large enough to obtain the required acceleration value, but should not exceed the value at which the wall or structure is initially stressed and which is equal to the fatigue limit or cyclic strength of their materials. In addition, the rate of formation of mechanical impulses should ensure a rate of deformation of the solid deposit that is higher than the rate of loosening of the deposit of the material to be cleaned. When the limits defined by said conditions limit the properties of the impulses, the solid layers 1 of the surface 2 become separated, while the surface of the structure itself remains undamaged throughout its service life.

The energy pulses are the pressure pulses generated in the liquid contained in the chamber 7 (Fig. 3). During the manufacturing process in this chamber, the deposits 8 differ from this liquid and settle on the wall of said chamber.

To initiate the pressure impulse, a line 9 is placed in the chamber 7 with a discharge gap 10, which line is connected to the electric power network via an electric impulse generator (not shown). As the deposits 8 grow larger than allowed, one or more electrical impulses pass through said line 9 having a discharge gap 10, separated by time slots. When the impulse voltage is high enough to exceed the discharge interval 10, a pressure impulse is generated in the liquid. This pressure impulse causes a short-term, flexible deformation in the walls of the chamber 7 which contains the liquid. This deformation takes place at high acceleration and speed and if its properties meet the said requirements, the deposit becomes separated from the walls of the chamber 7, while the walls themselves remain unchanged throughout their specified life. The liquid flowing through the chamber 7 takes the finely divided deposit to the purpose trough (not shown). It should be noted that when the chamber 7 and the pipelines 11 and 12 connected to it have different diameters, the liquid does not have time to flow out through the pipelines 11, 12 due to the short duration of the pressure impulse and the high inertia of the liquid, so that for the duration of.

Below are examples of external influences applied to deposits that have formed on the surfaces of the device during manufacturing processes or during operation of the machine.

(a) Sodium chloride which precipitates out of solution during the manufacturing process. In order to separate the sodium chloride from the walls of the vessel, it is appropriate to subject the sodium chloride to a heat treatment (calcination to evaporate the moisture it contains or cooling to reduce plasticity) before using the impellers.

li 9 73371 (b) A thick, loose layer of earth with a high clay content and adhering to a flat surface of the machinery during work. To facilitate the separation of this layer, it is convenient to apply a mechanical effect to it (seal with a roller) to achieve a higher density.

c) In order to accelerate the precipitation of sulfur from the solution during the manufacturing process and to facilitate its separation from the walls of the vessel, it is best to maintain an overpressure inside the vessel.

d) The separation of a thin layer of foam or carbon from the walls of the vessel by the impact effect is facilitated if the layer is covered in advance with a layer of epoxy resin.

e) To ensure the internal separation of the sugar precipitated from the solution during the manufacturing process, the deposit can be treated with alcohol.

f) To ensure the separation of the epoxy binder, it can be treated with a hardener (polyethylene-polyamine) during its solidification to make it more brittle.

g) In order to be able to remove carbon or sawdust adhering to the walls by frost by the impulse method, it is suitable to spray the deposit with water to form a thick and dense layer which can be effectively separated by the impulse method.

(h) The separation of carbon or cement waste from the walls of wooden freight wagons shall be enhanced by placing metal gratings inside the wagons before the impulse treatment.

(i) Sufficiently thick layers of foam, carbon or cement can be separated from the metal surfaces of the structures without prior external treatment.

Claims (8)

1. A method of separating deposits formed on wall surfaces of structures during a manufacturing process or function by effecting an elastic deformation in the wall surfaces by subjecting them to energy pulses from an outside source which impulses cause in the structural walls simple mechanical impulses, the duration of which is highest 0.01 s and which are separated by time intervals that are at least ten times longer than the duration of the mechanical pulses, and energy is accumulated during the intervals between the impulses for the presence of such a pulse effect that exceeds the value of the energy source multiplied and needed to achieve a mechanical impulse having a sufficient amplitude for separating the deposits but not exceeding a value at which the mechanical stresses in the design reach the fatigue limit, and wherein the mechanical impulse generating speed ensures that the deposition deformation has a velocity greater than the deposition ring n but not less than the critical impact speed of the material of the surface to be cleaned, characterized in that prior to generating the energy pulses directed at the wall surface to be cleaned to separate the deposits, these deposits change to a fixed state in which the adhesion between the deposits and wall surface material are less than the breaking surface strength of the wall surface material, while the slacking rate of the deposit is less than the allowable critical impact velocity of the wall surface material. 2. A method according to claim 1, characterized in that the external impact directed at the deposits is achieved by heat treatment, e.g. by calcination or by cooling. 3. A method according to claim 1, characterized in that the external impact directed on the deposits is accomplished by mechanical cold working for compressing the deposits. 4. A method according to claim 1, characterized in that the external impact directed at the deposits is achieved by an external pressure which causes recrystallization of the deposits.