Method for cleaning the external surface of elongate articles

Abstract

The invention relates to treating rolled metal products and can be used in the cleaning of cylindrical elongate articles. A method for cleaning the external surface of elongate articles includes the following steps: passing an article through a toroidal chamber equipped with a discharge nozzle, feeding a stream of an aqueous detergent solution and compressed air into the toroidal chamber, imparting turbulence to the gas-liquid stream in the discharge nozzle, and directing a pulsating gas-liquid stream at the external surface of the article to be cleaned, with hydrodynamic cavitation being generated. In order to generate a pulsating gas-liquid stream and hydrodynamic cavitation on the external surface to be cleaned, the flow rate of the gas-liquid jet is varied by feeding in the aqueous solution in a steady flow and at a constant pressure and simultaneously feeding in the compressed air in a pulsed manner and with a constant frequency in a range of from 1 to 20 Hz. This results in better quality cleaning of the surface of articles and a more efficient process.

Description

[0001] METHOD FOR CLEANING THE OUTER SURFACE OF LONG PRODUCTS

[0002] Field of technology to which the invention relates

[0003] The invention relates to the processing of rolled metal products, namely to cleaning them from process lubricants, and can be used in cleaning long cylindrical products, in particular pipes, wire and rods after cold rolling, drawing, before applying various types of coatings, as well as for finishing the surface of products.

[0004] State of the art

[0005] A method for cleaning from contaminants is known, which consists in the fact that the cleaning liquid is pre-saturated with gas below the solubility limit under normal conditions and cleaning is carried out in a gas-liquid flow with the release of gas from the liquid by heating the product being cleaned (USSR patent No. 1030058, B08BZ / 04, published on 23.07.1983). With this method, gas bubbles released from the liquid turbulize the boundary layer on the surface being cleaned, which improves the quality of cleaning.

[0006] The disadvantage of this method is the need for preliminary heating of the product, which is not always possible for technical and technological reasons, and is also economically inexpedient. This reduces the quality of the cleaned surface with the possible formation of an oxide film.

[0007] A method of cleaning long cylindrical products from contamination is known, in which the product is passed through a toroidal annular chamber device with nozzles, into which a rotating flow of cleaning liquid is fed and turbulence of the flow is created in the nozzle, made with annular protrusions and depressions on the inner surface (USSR patent No. 1276686, C23G 3 / 04, C25D 19 / 00, published 12 / 15 / 1986).

[0008] The design of the device does not ensure the creation of sufficient flow turbulence inside the toroidal chamber, as a result of which complete destruction and removal of any contaminants, such as hard-to-remove process lubricants, does not occur.

[0009] A method for cleaning a long cylindrical product is also known, which is implemented using a device in which the product is passed through a toroidal chamber with an outlet nozzle, into which a rotating flow of cleaning liquid is fed, compressed air is added and flow turbulence is created in the outlet nozzle by using annular grooves on its inner surface (RU Patent No. 2355484, B08B3 / 02, B05B1 / 02, published on 27.07.2008).

[0010] The disadvantages of the method and device are the low efficiency of the cleaning process from hard-to-remove contaminants - process lubricants, due to the significant volume of supplied gas, which leads to the need to separate its excess and complicates the cleaning process.

[0011] The closest solution adopted as a prototype is a method for cleaning the outer surface of a cylindrical article, in which the article is passed through a toroidal chamber with an outlet nozzle, into which a rotating flow of a washing aqueous solution and compressed air are fed, and turbulence of the gas-liquid flow is created in the outlet nozzle by changing the pressure of the gas-liquid flow from 20 to 1 atmosphere to form a pulsating gas-liquid flow, wherein the gas-liquid flow is fed counter-currently towards the article. In addition, a washing substance is added to the aqueous solution in an amount of no more than 1.0%, and compressed air is fed in an amount of no more than 10% of the volume of the washing aqueous solution. After cleaning the articles with the washing aqueous solution, they are washed with water and dried with compressed air in toroidal chambers with outlet nozzles, wherein each medium used is fed from the nozzle counter-currently towards the article. (Patent No. 2668033 B08B 3 / 02, B08B 9 / 023, B08B 3 / 08, published 09.25.2018)

[0012] The disadvantages of the method are the high technical complexity of the process of changing the pressure of the gas-liquid flow from 20 to 1 atmosphere, low productivity, low efficiency of the cleaning process from hard-to-remove contaminants and low quality of cleaning, as well as the need to use cleaning chemicals.

[0013] Disclosure of invention

[0014] The technical problem solved by the invention consists in creating an effective method for cleaning the outer surface of long metal products from process lubricants after rolling and drawing, before heat treatment, application of coatings and finishing operations.

[0015] The technical result consists in improving the quality of cleaning the surface of products and increasing the productivity of the process by ensuring hydrodynamic cavitation and eliminating the washing operation.

[0016] The technical result is achieved due to the fact that the method for cleaning the outer surface of long articles comprises the following stages: passing the article through a toroidal chamber equipped with an outlet nozzle; feeding a flow of a cleaning aqueous solution and compressed air into the toroidal chamber; creating turbulence in the gas-liquid flow in the outlet nozzle and feeding a pulsating gas-liquid flow onto the outer surface of the article being cleaned, forming hydrodynamic cavitation on the outer surface of the article being cleaned; wherein, in order to form a pulsating gas-liquid flow and hydrodynamic cavitation on the outer surface of the article being cleaned, changing the speed of the gas-liquid jet by feeding an aqueous solution in a continuous flow at a constant pressure and simultaneously pulsed feeding of compressed air at a constant frequency within the range from 1 to 20 Hz.

[0017] In addition, the aqueous solution is supplied in a continuous flow at a constant pressure of more than 10 atmospheres.

[0018] In addition, the compressed gas is supplied at a constant pressure exceeding the pressure of the aqueous solution by at least 1 atmosphere.

[0019] In addition, water is used as a solution, and air is used as a compressed gas. In addition, the aqueous solution is supplied in a continuous flow at a temperature of 30-40 °C.

[0020] Implementation of the invention

[0021] The claimed method for cleaning the outer surface of long articles, such as pipes, wires, rods and other long articles, comprises the following stages: the article, such as a pipe, is passed through a toroidal chamber with an outlet nozzle, a flow of a cleaning aqueous solution and compressed air are fed into the toroidal chamber, turbulence of the gas-liquid flow is created in the outlet nozzle and a pulsating gas-liquid flow is fed to the outer surface of the article being cleaned, forming hydrodynamic cavitation on the outer surface of the article being cleaned, wherein, in order to form a pulsating gas-liquid flow and hydrodynamic cavitation on the outer surface of the article being cleaned, the speed of the gas-liquid jet is changed by feeding an aqueous solution in a continuous flow at a constant pressure and simultaneously pulsed supply of compressed air at a constant frequency in the range from 1 to 20 Hz.

[0022] In this case, the aqueous solution can be supplied in a continuous flow at a constant pressure of more than 10 atmospheres, and the compressed gas can be supplied at a constant pressure exceeding the pressure of the aqueous solution by at least 1 atmosphere.

[0023] Water is used as a solution, and air is used as a compressed gas.

[0024] The movement of the gas-liquid flow on the outer surface of a cylindrical long product has a turbulent nature. The pulsed supply of compressed gas causes a sharp change in the speed and pressure of the liquid flow on the outer surface of the long product at the outlet of the outlet nozzle of the toroidal chamber, leading to the occurrence of hydrodynamic cavitation, due to which the surface of the product is cleaned of residual contaminants and process lubricant.

[0025] In the zone of a sharp pressure drop caused by an increase in the liquid flow rate due to the pulsed supply of compressed gas, gas bubbles change their volume, burst and destroy a strong layer of contamination on the outer surface of a cylindrical long product. In this case, compressed gas is supplied mainly at a pressure exceeding the pressure of the aqueous solution by at least 1 atmosphere, which eliminates the flow of the aqueous solution into the compressed gas supply system.

[0026] Using water as a solution eliminates the need to wash the product, which increases the productivity of the process.

[0027] The method of cleaning the outer surface, for example, of long metal products such as pipes, wires, rods before heat treatment, coating, finishing operations, etc., can be implemented, for example, on a unit having a toroidal chamber with an outlet nozzle, to which two pipes are connected from a distributor, providing a continuous supply of an aqueous solution to the cleaned surface of the product with a simultaneous pulse supply of compressed gas. An aqueous solution with a temperature of ZSN-40 degrees Celsius is supplied at a constant pressure, preferably more than 10 atm. The pulse supply of compressed gas is carried out with a constant frequency within the range from 1 to 20 Hz (at a frequency below 1 Hz and above 20 Hz, cavitation is practically absent) at a pressure exceeding the pressure of the aqueous solution by at least 1 atmosphere.

[0028] Quality control of cleaning is carried out according to the degree of contamination of a white cotton napkin when wiping the inner surface of a 1 m long pipe, which is weighed before and after wiping.

[0029] The proposed cleaning method allows obtaining the outer surface of products without residual contamination and increasing the productivity of the process.

[0030] An example of a specific implementation.

[0031] Using the proposed method, cleaning (removal of Castrol TDN86 process lubricant) of the outer surface of cold-rolled stainless steel pipes made of 12X18N10T alloy with a diameter of 16 mm, a thickness of 1 mm, a length of 4 to 24 m with an average initial contamination of 6080 mg / m was carried out. 2 The pipes were cleaned in water using a pilot pulse jet cavitation cleaning unit.

[0032] A continuous supply of an aqueous solution with a simultaneous pulse supply of compressed gas was carried out on the cleaned surface of the pipes. An aqueous solution with a temperature of 30-5-40 degrees was supplied at a constant pressure of 12 atm. Compressed air with a frequency of 15 Hz under a pressure of 17 atmospheres was used as a compressed gas.

[0033] Then the quality control of cleaning of the outer surface of the pipes was carried out. The test results are presented in the table below.

[0034] Table - Performance of the installation for cleaning the outer surface of pipes of different lengths.

[0035] Conducted pilot industrial tests have shown that the duration of high-quality cleaning (without residual contamination) of pipes of different lengths is the same and ranges from 1 to 3 minutes, and the productivity of the cleaning process is higher the longer the pipe.

[0036] And if the cleaning duration is less than 1 minute, the required quality for the outer surface of the pipes is not ensured.

[0037] Similar cleaning results were obtained when cleaning the outer surface of pipes made of titanium, zirconium, molybdenum and other types of alloys.

[0038] Compared with the known method of cleaning the outer surface, in particular removing grease, the duration of the proposed cleaning method is 3-3.5 times shorter. As follows from the data given in the table, the productivity of the industrial installation for cleaning long pipes (10-40 m) will also be 3-3.5 times higher.

[0039] Thus, the use of the proposed method for cleaning the outer surface of long products, in comparison with the known one, is environmentally friendly, highly effective, allows to reduce energy and resource costs, significantly reduce the time of cleaning the surface of the product, increase the productivity of the process and the quality of cleaning, obtaining a surface without residual contamination regardless of the nature of the metal being processed and lubricant, due to the fact that the pulsed supply of compressed air causes a sharp change in the speed and pressure of the gas-liquid flow on the outer surface of the cylindrical long product, leading to the occurrence of hydrodynamic cavitation, which allows to completely clean the surface from the process lubricant.

Claims

CLAUSE OF THE INVENTION 1. A method for cleaning the outer surface of long articles, characterized in that it contains the following stages: passing the article through a toroidal chamber equipped with an outlet nozzle, feeding a flow of a cleaning aqueous solution and compressed air into the toroidal chamber, creating turbulence in the gas-liquid flow in the outlet nozzle and feeding a pulsating gas-liquid flow onto the outer surface of the article being cleaned, forming hydrodynamic cavitation on the outer surface of the article being cleaned, wherein, in order to form a pulsating gas-liquid flow and hydrodynamic cavitation on the outer surface of the article being cleaned, changing the speed of the gas-liquid jet by feeding an aqueous solution in a continuous flow at a constant pressure and simultaneously pulsed feeding of compressed air at a constant frequency in the range from 1 to 20 Hz.

2. A method for cleaning the outer surface of long products according to paragraph 1, characterized in that the aqueous solution is supplied in a continuous flow at a constant pressure of more than 10 atmospheres.

3. A method for cleaning the outer surface of long products according to paragraph 1, characterized in that the compressed gas is supplied at a constant pressure exceeding the pressure of the aqueous solution by at least 1 atmosphere.

4. A method for cleaning the outer surface of long products according to paragraph 1, characterized in that water is used as a solution and air is used as a compressed gas.

5. A method for cleaning the outer surface of long products according to paragraph 1, characterized in that the aqueous solution is supplied in a continuous flow at a temperature of 30-40 °C.

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