EP3323518A1

EP3323518A1 - Method for cleaning cylindrical long-dimensional products and device for implementing same

Info

Publication number: EP3323518A1
Application number: EP16899575.1A
Authority: EP
Inventors: Sergej Nikolaevich SIROTKIN; Tatyana Aleksandrovna Voronina; Igor Anatolevich PROCHUKHAN; Nikita Maksimovich KUZNETSOV
Original assignee: Obschestvo S Ogranichennoi Otvetstvennostyu "nauchno-Technichesky Tsentr "trubmetprom" Ooo "ntc "trubmetprom"
Current assignee: Obschestvo S Ogranichennoi Otvetstvennostyu "nauchno-Technichesky Tsentr "trubmetprom" Ooo "ntc "trubmetprom"
Priority date: 2016-04-21
Filing date: 2016-04-21
Publication date: 2018-05-23
Also published as: CN109070149A; WO2017184010A1; EP3323518A4; EA201890284A1; RU2668033C1

Abstract

The inventions relate to the processing of rolled metal products, and specifically to cleaning-away process lubricants, and may be used in the cleaning of long-dimensional products (pipes, wire, rods) following cold rolling and drawing, and before applying various types of coatings, and also for finishing the surfaces of products. In a method for cleaning cylindrical longdimensional products, said products are passed through a toroidal chamber having an outlet nozzle. A rotating flow of aqueous washing solution and compressed air are fed into the chamber via inlet nozzles, creating turbulence in a gas-liquid flow in the outlet nozzle, wherein the pressure of the flow of aqueous solution is changed from 20 atmospheres to 1 atmosphere in order to form a pulsating gas-liquid flow which is fed as a counter-current toward a product. Following cleaning, products are rinsed with water and dried using compressed air in similar toroidal chambers, with each medium being fed as a counter-current toward the product. A cleaning device contains a toroidal chamber with two tangential inlet nozzles and a coaxially-disposed outlet nozzle. Between two and ten channels are provided in the outlet nozzle, the longitudinal axes of which are disposed tangentially to the surface of a product. The use of the inventions generates hydrodynamic and surface cavitation, and increases the effectiveness and quality of cleaning.

Description

The invention refers to the processing of rolled metal products, namely, to the cleaning from the process lubrications and can be used for cleaning of long-length products, in particular, pipes, wires and bars after cold rolling, drawing, before coating of different types of coatings and also after finishing of the surface of products.
The known method of cleaning from contaminations consists of the preliminary saturation of washing fluid with gas below the limit of solubility at normal conditions and cleaning is performed in the gas-liquid flow with gas emission from liquid by heating of the productto be cleaned (inventor's certificate USSR No. 1030058 , V08V3/04, published on 23.07.1983). Using such method the gas bubbles evolved from the liquid create turbulence in the boundary layer on the cleaning surface and this increases the quality of cleaning.
The shortcoming of this method is the necessity to preheat the product and that is not always possible due to some technical and technological reasons and also economically impractical. At the same time the quality of the cleaned surface is decreasing with possible formation of oxide film.
Another known method of cleaning of the long-length products from contamination consists of passing of a product through the toroidal annular chamber with nozzles into which the rotating flow of washing fluid is supplied and the flow turbulence is created in the nozzle performed with collars and cavities on the internal surface (inventor's certificate USSR No. 1276686 , C23G 3/04, C25D 19/00, published on 15.12.1986).
The design of the device does not provide the creation of the sufficient flow turbulence inside the toroidal chamber and due to this there is no complete destruction and removal of any contaminations, for example, the process lubricants that are hard to remove.
The closest solution that was accepted as a prototype for the method and the device is the cleaning method for the long-length product realized by means of the device when the product is passed through the toroidal chamber with the exit nozzle into which the rotating flow of washing fluid is supplied and compressed air is added and the flow turbulence is created in the exit nozzle using the collars on its internal surface (RF patent No. 2355484 , V08V3/02, V05V1/02, published on27.07.2008).
The shortcoming of the method and the device is the low efficiency of the cleaning process from contaminations that are hard to remove - process lubricants due to the significant volume of supplied gas and this leads to the necessity to release its excess and makes the cleaning process difficult.
The technical problem that is solved by the inventions is the creation of the hydrodynamic and surface cavitation, increase of efficiency and quality of cleaning.
The set problem is solved due to fact that in the cleaning method for cylindrical long-length products when the products are passed through the toroidal chamber with the exit nozzle and where the rotating flow of washing aqueous solution and compressed air are supplied and the turbulence of the gas-liquid flow is created in the exit nozzle, according to the invention, pressure of the aqueous solution flow is changed from 20 to 1 atmosphere to form the pulsing gas-liquid flow and at the same time the gas-liquid flow is supplied towards the product. Besides, the cleaning agent is added into the aqueous solution in the amount of max. 1.0% and the compressed air is supplied, max. 10% of the volume of the washing aqueous solution. After cleaning the products with the washing aqueous solution they are flushed with water and dried with compressed air in the toroidal chambers with the exit nozzles and every used medium is supplied from the nozzle in counter-flow towards the product.
The set problem is solved also due to the fact that in the device for cleaning of the cylindrical long-length products containing the toroidal chamber with two input tangential nozzles and an exit nozzle is located coaxially, according to the invention, the exit nozzle is made by channels, the longitudinal axes of which are located tangentially to the surface of the product. Besides, from two to ten channels, cross section diameter of each 0.5÷2.0 mm, are made in the exit nozzle, the ratio S ₁ between the cross section areas of the internal section of the nozzles and cylindrical products to the total area S ₂ of the cross section channels meet the following conditions: $\frac{s_{1}}{s_{2}} \geq 10,$
the device is equipped additionally with at least two analogous toroidal chambers for flushing and drying of the products.
When changing the pressure of the aqueous solution flow in the interval from 20 to 1 atmosphere and formation of the pulsing gas-fluid flow on the surface of the product in the toroidal chamber the creation of the hydrodynamic cavitation effect is provided, the cleaning process is intensified due to the change of rate of the gas-fluid flow and therefore the bubbles change their size, the cavitation effect arises in the exit of the nozzle in the zone of the sharp pressure drop, the bubbles explode and destroy the solid layer of contaminations on the surface of the product. At the same time the supply of the gas-fluid flow in the counter-flow towards the processed product intensifies the cavitation due to the hydraulic resistance in the flow jet.
The use of the cleaning agent in the working solution in the amount of max 1.0% allows decreasing the agressivity and ecological harm of the process and creating the low waste environmentally safe technology at the high cleaning quality. The use of the compressed air in the amount of max 10% of the total volume of the washing aqueous solution is optimal and sufficient to create the hydrodynamic cavitation capable to provide the destruction and removal of any contaminations. The increase of the compressed air concentration above 10% makes the formation of the hydrodynamic cavitation difficult due to the excess of the gas, decreases the efficiency and effectiveness of the cleaning process.
After cleaning the products with the washing aqueous solution they are flushed in the toroidal chamber with the water from the exit nozzle in the counter-flow towards the processed product to remove its residues and this helps the intensification of the process, increase of its efficiency and improvement of the cleaning quality due to the creation of the effects of hydrodynamic and surface cavitation. After flushing with water the products are dried with compressed air.
The execution of the exit nozzle with channels, longitudinal axes of which are located tangentially to the surface of the product provides the creation of the additional cavitation in the surface layer of the gas-liquid flow on the processed product and allows intensifying the cleaning process and increasing its quality. The most optimal is the execution with two to ten channels, cross section diameter of each 0.5÷2.0 mm, when the ratio S ₁ between the cross section areas of the internal section of the nozzles and cylindrical products to the total area S ₂ of the cross section channels meet the following conditions: $\frac{s_{1}}{s_{2}} \geq 10,$
and due to the intensive suction of air through the channels and increase of turbulence of the gas-liquid flow the additional centers of the surface cavitation arise. Execution of less than two channels in the exit nozzle create insufficient cavitation and the execution of more than ten channels leads to the leakage of the washing solution and this decreases the efficiency and the quality of cleaning. It was experimentally proved that the execution of channels, diameter less than 0.5 and more than 2 mm and also at the ratio $\frac{s_{1}}{s_{2}} < 10$
there is the air suction decrease into the gas-liquid flow through the channels, the sufficient cavitation is not provided and this also decreases the efficiency the cleaning quality.
The invention is illustrated by the figures, wherein:

Fig.1 shows the section of the device schematically for the implementation of the method;
Fig. 2 shows the section of the chamber and the processed product;
Fig.3 shows the section A-A in the Fig.2 - internal surface of the nozzle and;
Fig.4 shows the passing of the processed product through the washing, flushing and drying chambers.

The device for implementation of the cleaning method contains the toroidal chamber 1, the nozzle 2 for the supply of the washing aqueous solution, the nozzle 3 for the compressed air supply, the exit nozzle 4 with the channels 5. The long-length product 6 is drawn through the washing chamber 1 in the direction shown by the arrow V_Tp. After cleaning the products 6 are taken into the washing chamber 7 and the drying chamber 8.
The method was implemented in the following way. The washing aqueous solution 9 is supplied into the toroidal chamber 1 through the nozzle 2, and the compressed air is supplied through the nozzle 3 and it is formed into the vortical flow with a gas-liquid flow containing the air bubbles, diameter of several microns. The movement of the gas-liquid flow inside the toroidal chamber 1 has a turbulent character due to the change of the aqueous solution pressure 9 and formation of the pulsing gas-liquid flow changing its rate when moving inside the chamber 1 and along the exit nozzle 4 and creating the hydrodynamic cavitation and also the surface cavitation due to the suction of the air into the gas-liquid flow through the channels 5. Owing to the pressure change the bubbles change their size and in the exit from the nozzle 4 through the channels 5 in the zone of the sharp pressure drop the bubble explode and destruct the solid layer of contaminations on the surface of the long-length product 6 and then the product is flushed by water 10 and dried by compressed air 11 in the toroidal chambers 7 and 8 correspondingly.
The method and the device for cleaning were tested during removal of the process lubricants, for example, Castrol, paraffin wax, Blasomill, Blasocut used in the cold rolling mill when manufacturing the cold-rolled stainless steel pipes, diameter 6÷30 mm being the most difficult lubricants to remove, in particular, for cleaning of the external surface of the stainless steel pipes, diameter 10 mm. The device was used in the exit nozzle of which the four channels were made, diameter 1 mm, the longitudinal axes of which were located tangentially towards the surface of the pipe. The section area S ₁ was 35 mm², and the total cross section area of channels S ₂ was 3.14 mm², and $\frac{s_{1}}{s_{2}} = 11.15.$
For tests the washing aqueous solution containing, for example 0.5% of "Flotter" agent was used with the pressure of the washing aqueous solution 5-10 atm., compressed air pressure - 2 atmosphere, the gap between the cleaned pipe and the internal surface of the nozzle was 1 mm. After cleaning of the external surface of pipes from the process lubricants on the surface of the products there are no residual contaminations, traces and spots of water after flushing, the surface of the products correspond to the set requirements to the condition of the surface of high-duty products.
Using the previously applied technology such lubricants were removed, in particular, by means of the batch degreasing of pipes in the baths with the high concentrated hot-alkaline solutions or organic solvents with the following batch flushing of pipes in the hot water and drying in the air or wiping with the soft material but this did not provide the high quality cleaning and, besides, this technology is power and resource consuming and environmentally harmful.
The application of the offered method of cleaning for the cylindrical long-length products and device allows:

providing the creation of hydrodynamic and surface cavitation,
decreasing the concentration of the cleaning agent in the solutions up to 1% and less and increasing of the environmental safety,
increasing the quality of the products cleaning due to the exclusion of residual contaminations,
decreasing the power costs 35÷40 times due to the used of the washing solutions without heating,
removing the process lubricants regardless their nature and composition,
decreasing the prime cost of the output products.

Claims

Cleaning method for cylindrical long-length products, wherein the products are passed through a toroidal chamber having an exit nozzle, a rotating flow of a washing aqueous solution and compressed air are supplied into the toroidal chamber and a turbulence of a gas-fluid flow is formed in the nozzle, characterized in that the pressure of the aqueous solution flow is changed from 20 to 1 atmosphere to form a pulsating gas-liquid flow, said gas-liquid flow being supplied in counter-flow towards a product.
The method according to claim 1, wherein the cleaning agent is added into the aqueous solution in the amount of max 1.0% and the compressed air is supplied in the amount max 10% of the total volume of the washing aqueous solution.
The method according to the claims 1 and 2, wherein cleaning the products with the washing aqueous solution they are flushed with water and dried with compressed air in the toroidal chambers with the exit nozzles and every used medium is supplied from the nozzle in the counter-flow towards the product.
A device for cleaning cylindrical long-length products, comprising a toroidal chamber with two tangential nozzles and a coaxially located exit nozzle, characterized in that the exit nozzle is made with channels, the longitudinal axes of which are located tangentially to the surface of the product.
The device according to the claim 4, wherein there are from two to ten channels, cross section diameters of each 0.5÷2.0 mm in the exit nozzle, and the ratio S ₁ between the cross section areas of the internal surface of the nozzle and the cylindrical product to the total area S ₂ of cross sections of channels meets the following condition: $\frac{s_{1}}{s_{2}} \geq 10.$
The device according to claim 4, further comprising at least two analogous toroidal chambers for flushing and drying of products.