RU1776465C - Method of cleaning inner surfaces of cylindrical articles - Google Patents

Abstract

Scope: for cleaning the internal cavities of products from solid insoluble contaminants in the engineering, chemical and other industries. The inventive cavity of a cylindrical product (CI) is partially filled with a washing solution, the latter is placed dispersed particles of abrasive material and a gas volume (GO) with the formation of a gas-liquid oscillatory system (CS), including sealing the internal cavity of the CG and communicating vibration to it at the resonance frequency of the CS . To this end, a gas-liquid CS tuned to the resonance is formed by pulsed introduction of GO on the bottom of the QI cavity with simultaneous communication of the QI of vibrational vibrations followed by sealing of the cavity. The added GO is retained in the washing solution due to vibrational force, increasing force. increasing upon resonance vibrations of the resulting CS. Due to the direct dynamic contact of the washing solution and GO and the increase in the contact surface, the sensitivity of the gas-liquid CS increases and the turbulization of the washing solution in the resonant oscillation mode of the CS increases, thereby effectively removing contaminants from the surface being cleaned. 1 ill. THX

Description

The invention relates to methods for cleaning the internal cavities of products from solid insoluble contaminants and can be used in engineering, chemical and other industries.

There is a method of cleaning the inner surface of cylindrical products, which consists in pumping a washing solution with gas through the product and communicating vibration vibrations to the product with a frequency increasing from 5 Hz to the resonant value of the circular vibrations of the washing solution, the product being placed i horizontally, and the vibration is reportedly normal forming product and at an angle of 30-60 ° relative to the vertical plane of its symmetry with constant vibration acceleration, the value of which is 20-40 g (ed. St. Ns 942816, class B 08 V 3/10. 1980).

The disadvantage of this method is the difficulty of its implementation, due to the need to roll a gas-liquid stream through the product while simultaneously applying vibrations at an angle of 30-60 °, the frequency of which varies from 5 Hz to the resonant value of the circular oscillations of the washing solution. In addition, in this method, the intensity of the dynamic effects of detergent

XI XI O O

ate

the liquid on the surface of the product to be cleaned is determined mainly by the inertial properties of the liquid, which limits the possibility of improving the quality of cleaning. High values of vibration acceleration of the vibrations transmitted to the product result in high energy consumption for cleaning.

Closest to the proposed one is a method of cleaning the inner surface of cylindrical products, which consists in exposing the surface to be cleaned with a washing solution with gas and communicating the product with vibrations, in which the product is placed vertically and the internal cavity is sealed after filling it with 80-85% washing solution while dispersed particles of abrasive material are placed in the lower part of the cavity and above them is a localized elastic gas volume, forming a non-linear quantity with the washing solution the gas-liquid system, and the vibrations are communicated to the product in the vertical direction at the resonance frequency of the gas-liquid oscillation system (ed. St. Ms 1680386, class B 08 V 3/10. 1989). In this method, a localized elastic gas volume is formed by a gas-filled elastic shell made, for example, of a rubber film that provides good dynamic contact between gas and liquid. In this case, the gas plays the role of the elastic element of the oscillatory system, and the liquid - the inertial one. An elastic shell with gas is freely placed in the liquid above the dispersed particles and is prevented from floating by means of a grating fixedly installed in the lower part of the product cavity.

However, the presence of an elastic shell between the liquid and the gas volume worsens the dynamic contact between these elements of the oscillatory system. This reduces the intensity of turbulization of the washing liquid and the intensity of cavitation processes during resonance vibrations of the system, which limits the possibility of improving the quality of cleaning the inner surface of the products. According to this method, in the resonant mode of oscillations of a non-linear gas-liquid system, the amplitude of the waves of dynamic pressure in the washing liquid increases several times, which is sharply turbulized and. capturing gas from the upper part of the cavity of the product, turns into a homogeneous hydrosol. At the same time, powerful turbulent pulsating flows of washing liquid are formed in the cleaned cavity of the article, intensively washing the cleaned surface. Dispersed particles of abrasive material captured by the flows of washing liquid intensely affect the inner surface of the cavity, increasing the quality of its cleaning. The efficiency of removing contaminants is also increased due to cavitation processes that develop in the washing fluid with periodic decreases in hydrodynamic

0 pressure during negative half-cycles. It should be borne in mind that in the process of cleaning the product, the elastic shell is subjected to intense impact of abrasive particles and separated particles of impurities, and also during its pulsations collides with the grating and walls of the cavity being cleaned. This can lead to a disruption in the operating mode of cleaning due to a violation of the tightness of the elastic shell and the escape of gas from it. An increase in the strength properties of the shell is inevitably associated with an increase in its rigidity and a deterioration in the dynamic contact between gas and liquid, a decrease in the sensitivity of the oscillatory system, which leads to a decrease in the intensity of hydrodynamic processes during resonance vibrations of the system and a decrease in the quality of surface cleaning.

0 The aim of the invention is to improve the quality of cleaning the inner surface of cylindrical products by intensifying the process of resonant oscillations of the gas-liquid system and increasing the stability of the operating mode.

This goal is achieved due to the fact that in the method of cleaning the inner surface of cylindrical products with partial filling of the product with detergent

0 solution and placement in the solution of dispersed particles and gas volume with the formation of a nonlinear oscillatory gas-liquid system, including sealing the internal cavity of the product and communication

5 to the vibration product at the resonance frequency, the gas volume is placed in the washing solution when the vibration product is communicated by the pulsed introduction of gas into the layer of dispersed particles in the lower cavity

0 product, followed by sealing the product cavity and maintaining constant pressure in the cavity at the time of introduction of the gas. The drawing shows a diagram of a device for implementing the proposed method.

5 The cleaned hollow cylindrical article 1 is mounted vertically on the platform 2 of the vibrating stand. In the lower part of the cleaning cavity of the product 1, a layer of dispersed particles 3 of abrasive material is placed and the product is filled

detergent solution to 80-85% of its internal volume. Then the product 1 is hermetically closed using a removable cover 4 with an annular seal 5, docked to the upper end of the product. An opening with a seal 6 is made in the central part of the lid 4, in which a tube 7 is hermetically fixed, mounted along the axis of the article 1 with the possibility of vertical movement and fixation of the position. The vertical tube 7 is installed in such a position that its lower end is in the layer of dispersed particles 3 near the bottom of the cavity (at a distance of 3-6 mm). The upper end of the tube 7, located above the cover 4, is connected via a flexible pipe 8 to a gas metering device 9, made, for example, in the form of an elastic rubber bulb 10 with shut-off valves 11 and 12, of which valve 11 is connected to the atmosphere and valve 12 - with a tube cavity 7. A vertical pipe 13 is also installed in the cap 4 with a movable rod 14 located therein, at the lower end of which is located in the cavity of the product 1, the float 15c is fixed with the valve 16, and at the upper end, which is outside cavity, limiter 17. At the lower end of the pipe 13, the seat 18 of the valve 16 is fixed at the bottom side of the cover 4. The float 15 is, for example, made of foam and is at the level of the surface of the washing solution, while the valve 16 is below the seat 18, so that the gas part of the cavity of the article 1 is connected through the pipe 13 to the atmosphere .

When the vibrostand is switched on, the product 1 is informed of periodic vertical vibrations that excite a dynamic pressure of a given frequency fi in a liquid (washing solution). Then, using the dispenser 9, a predetermined volume of air is pulsedly introduced through the tube 7 into the lower part of the product cavity being cleaned. The pulsations of the liquid pressure are immediately transmitted to the introduced gas, which is in dynamic contact with the liquid, and a nonlinear gas-liquid system is formed in the cavity of the article. This system is tuned to resonance, because gas is introduced in an amount corresponding to the resonant mode of oscillations of this system, equal to

l p R S r 3,

Q ICM 1 where n is the adiabatic index of gas dt:

P is the pressure in the cavity above the surface of the washing solution, dyne / cm;

S is the cross-sectional area of the gas volume, cm2;

fi is the frequency of vibration on the product, Hz;

p is the density of the washing solution, g / cm3;

h - column height of the cleaning solution, see

That is, upon the pulsed introduction of gas (due to the formation of a gas-liquid oscillatory system tuned in resonance with the source of vibration), the hydrodynamic pressure immediately increases in the cavity of the product and the turbulization of the washing solution increases sharply.

Under conditions of variable pressure in the liquid, the gas present in it is affected by a vibrational force directed downward against the force of Archimedes. At a small hydrodynamic pressure, the buoyancy force of Archimedes exceeds the vibrational force and therefore the gas floats to the surface of the liquid. With resonant vibrations of the gas-liquid system, the vibrational force increases sharply and exceeds the force of Archimedes. Therefore, the gas introduced pulsed on the bottom of the cavity does not float, but is held by a vibrational force on the bottom, interacting with the liquid column above it. The introduced gas is located on the bottom of the cavity in the form of a dense local accumulation of dynamically active finely dispersed bubbles distributed in the form of a fluidized bed over the surface of the bottom. Dispersed particles of abrasive material; are powerful turbulent fluid flows and, being in a suspended state, make intensive chaotic movements in the volume of the cavity, intensively affecting the surface being cleaned.

When pulsed introduction of air (gas volume) through the tube 7 into the liquid part of the cavity to be cleaned, the same amount of air is simultaneously discharged from the gas part of the cavity through the open pipe 13 and the pressure in the cavity does not change. This is necessary because introducing gas into the cavity without simultaneously venting gas therefrom will increase pressure. An increase in the pressure in the cavity will make it difficult to impulse the introduction of gas into it (the rate of injection decreases), and will also lead to a change in the natural frequency of the gas-liquid oscillation system formed in the cavity. As a result of this, when a gas is introduced into the cavity, the resonance mode of oscillations may not occur in it.

system, the introduced gas pops up in the upper part of the cavity and the operating mode of cleaning will not be obtained.

At the same time, upon excitation of the resonance regime in the cavity being cleaned, the liquid (washing solution) sharply turbulizes and, capturing free gas from the upper part of the cavity, turns into a homogeneous hydrosol filling the entire volume of the cavity. In this case, the float 15 rises up along with the level of the washing solution, the valve 16 sits on the seat 18, blocking the entrance to the nozzle 13, and the internal cavity of the article 1 is sealed. During the cleaning process, the valve 16 is firmly pressed against the seat 18 due to the excess pressure arising in the cavity during resonance vibrations of the gas-liquid system.

Thus, upon pulsed gas injection through the tube 7 into the product cavity, resonant oscillations of the gas-liquid system are immediately excited, providing a high degree of hydrodynamic disturbance of the washing medium. In this case, the surface to be cleaned is subjected to the combined action of turbulent flows of the washing solution, cavitation and dispersed particles of abrasive material, due to which the contaminants are effectively removed from the surface to be cleaned.

Since the gas volume placed in the liquid is held therein without the aid of an elastic shell present in the prototype, the dynamic contact of gas and liquid in the gas-liquid oscillation system is improved and the sensitivity of the system is increased. In this case, since the introduced gas volume passes into the disperse structure in the form of a local accumulation of dynamically active bubbles, the total surface of interaction of the gas with the liquid increases, which also increases the sensitivity of the system. An increase in the sensitivity of the oscillatory system increases the intensity of its resonant vibrations - the turbulization of the washing solution increases, cavitation processes intensify, and the movement of abrasive particles accelerates. This improves the cleaning quality of the inner surface of the cylindrical products.

In addition, the presence of highly active bubbles on the bottom of the cavity of the gas volume in the form of a fluidized bed significantly intensifies the movements of dispersed particles, enhancing their abrasive effect on the surface being cleaned, and the intense effect of the fluidized bed on the bottom of the cavity further increases the efficiency

cleaning it up. The stability of the operating mode of cleaning is also increased in comparison with the known method in which it may have a spontaneous gas outlet

from the elastic shell and the breakdown of the resonance regime of the oscillatory system.

The duration of the cleaning process of the proposed method is on average 0.5-1.5 minutes. At the end of the process

0 cleanings turn off the source of vibrations, the dynamic pressure in the liquid disappears and its turbulent pulsations cease. In this case, the hydrosol in the cavity of the product disintegrates into the initial components - the gas leaves the washing solution in the upper part of the cavity, dispersed particles sink to the bottom of the cavity. If necessary, the cleaning process can be repeated by pouring fresh washing solution into the cavity to be cleaned.

During experimental testing of the proposed method, the inner surface of hollow cylindrical products with a diameter of 50-130 mm was cleaned and

5 with a length of 180-350 mm, for which covers of several sizes were manufactured. The VEDS-100 electrodynamic vibrating stand was used to communicate the vibration product. Product is full

0. Washing solution at 80-85% of the height, at

the bottom of the cavity of the product was placed layer

particles of abrasive material - electrofused corundum with a dispersion of 0.8-1

mm, the layer height was 0.05-0.1 height

5 cavities. Pulse air was introduced into the layer of dispersed corundum particles through a central tube located at a distance of 3-10 mm from the bottom of the cavity. The dynamic pressure in the washing solution was determined using an LX-610 acoustic sensor having a sensitivity of 5.4 μV / N / m2 connected to a microvoltmeter. The use of transparent (from plexiglass) models showed5 that the resonant regime of pulsations of the washing medium in the product cavity appeared immediately after gas was introduced with an input pulse duration of not more than 0.25 s. The float moved up and the valve

0 blocked the hole in the lid, providing sealing of the internal cavity of the product. In the operating mode of cleaning in the frequency range 35-65 Hz with vibration accelerations of 5-7 g, the dynamic pressure in the washing solution was 130-150 kPa or 1.3-1.5 these (depending on the size of the cavity being cleaned), which 20-25% exceeds the dynamic pressure in the known prototype method. The obtained high-intensity cleaning regime was stable; there were no cases of a breakdown of the resonance regime of oscillations of the gas-liquid system during the cleaning process.

Claims (1)

SUMMARY OF THE INVENTION A method for cleaning the inner surface of a cylindrical product, the method comprising partially filling the cavity of a product with a washing solution; dispersed particles and a gas volume are placed in the solution to form a non-linear of the gas-liquid oscillatory system, after which the product cavity is sealed and the product is vibrated at a resonance frequency, in order to improve the quality of cleaning, the gas volume is placed in the washing solution by means of pulsed introduction of gas into the layer of dispersed particles at maintaining constant pressure in the cavity at the time of gas injection.