RU2062971C1 - Method of cleaning inner surface of tubers - Google Patents

Abstract

FIELD: tube cleaning equipment. SUBSTANCE: method comprises steps of pumping working liquid through tube to be cleaned, acting upon inner surface of the tube by electrohydraulic shock with use of electrohydraulic irradiator, being moved inside the tube as the last is being cleaned. Voltage is determined for providing electrohydraulic shock, preventing damage and breakage of surface of the tube. EFFECT: enhanced quality of tube surface cleaning. 1 cl, 1 dwg

Description

 The invention relates to techniques for cleaning the surfaces of products from contamination using electro-hydraulic shock and can be used to clean heat exchangers or pipelines in the energy, chemical and metallurgical industries.

 During operation, the inner surfaces of the pipes are contaminated with various deposits, which impair the performance of the apparatus in which they are used. Various methods and devices are used to remove deposits.

 A known method of cleaning the surfaces of pipes (1), which consists in the fact that in the cavity of the pipe simultaneously from opposite sides create shock waves using electro-hydraulic emitters. A device that implements the method contains two electro-hydraulic emitters, including two electrodes, partially coated with insulation, as well as pressure sensors associated with the recording equipment unit. The disadvantage of this method is the low quality of cleaning of long pipes due to the limited radius of action of the emitters, as well as low productivity and low-tech cleaning, since it is necessary to dismantle the contaminated pipes and immerse them in a special bath.

 There is also known a method of cleaning the inner surface of the pipe (2), which consists in the fact that the inner surface of the pipe is subjected to electro-hydraulic shock and at the same time the electro-hydraulic emitter is moved inside the pipe as it is cleaned. The disadvantage of this method is that the optimal voltage for creating an electrohydraulic shock is not determined, which depends on many factors, including the material and dimensions of the pipe being cleaned. If you choose the amplitude of the voltage pulse less than optimal, then to clean the pipe will need to produce several pulses. If the amplitude of the pulse is more than optimal, then not only scale and deposits can be destroyed, but also the pipe wall.

 The basis of the present invention is the task of creating such a method for cleaning the inner surface of the pipes, which eliminates the destruction and damage of the pipe walls during the cleaning process.

,
где Kд динамический коэффициент прочности материала трубы;
s_т статический предел текучести материала трубы;
δ_т толщина трубы;
r радиус трубы;
L индуктивность разрядной цепи батареи конденсаторов;
lр.п. длина разрядного промежутка;
С емкость батареи конденсаторов;
ρ плотность среды, в которой происходит разряд.The problem is solved in that in the method of cleaning the inner surface of the pipes, which consists in the fact that the working fluid is pumped through the pipe, an electro-hydraulic shock is applied to the inner surface and the electro-hydraulic radiator is simultaneously moved inside the pipe, the voltage to ensure electro-hydraulic shock is determined as:

,
where Kd is the dynamic coefficient of strength of the pipe material;
s _{t the} static yield strength of the pipe material;
δ _t pipe thickness;
r radius of the pipe;
L inductance of the discharge circuit of a capacitor bank;
l.p. discharge gap length;
With capacitor bank capacity;
ρ is the density of the medium in which the discharge occurs.

In the proposed method for cleaning the inner surface of the pipes, it is necessary to choose such an amplitude of the shock wave that occurs during an electric discharge in the liquid, which would destroy scale and other deposits and would not damage the pipe itself, i.e. the amplitude of the pulse pressure in the pipe should not be higher than the dynamic yield strength of the pipe walls. The proposed formula (1), based on the geometry of the pipe (r, d _t ), the yield strength of the pipe material (K _d , σ _t ) and the parameters of the discharge circuit (C, L, lp. P.) Determines the maximum allowable voltage of the capacitor bank, at which the pipe is not damaged (no permanent deformation).

 The drawing schematically shows a device that implements a method for cleaning the inner surface of the pipes.

 The device contains a switching power supply 1, including a step-up transformer 2, a rectifier 3, a capacitor bank 4, a spark gap 5. The positive pole of the power supply 1 is connected to an insulated core 6 of cable 7. The negative pole of the power source 1 is connected to another core 8 of cable 7. The cable is placed in the cavity of the cleaned pipe 9, the inner surface of which is covered with scale and various deposits 10.

,
где Kд динамический коэффициент прочности материала трубы;
s_т статический предел текучести материала трубы;
δ_т толщина трубы;
r радиус трубы;
L индуктивность разрядного контура;
lp.п. длина разрядного промежутка;
C емкость конденсаторной батареи;
ρ плотность среды, в которой происходит разряд.The method is as follows. Through the pipe 9, into which the cable 7 is placed, the working fluid (process water) is pumped. An electric discharge is created between the cores 6 and 8 of the cable, and shock waves are generated in the liquid, which destroy and grind scale and other deposits 10. The water flow brought to the pipe flushes the crushed scale out of it, and the cable moves inside the pipe as the scale breaks down . In this case, the voltage to ensure electro-hydraulic shock is defined as:

,
where Kd is the dynamic coefficient of strength of the pipe material;
s _{t the} static yield strength of the pipe material;
δ _t pipe thickness;
r radius of the pipe;
L inductance of the discharge circuit;
lp.p. discharge gap length;
C capacitance of a capacitor bank;
ρ is the density of the medium in which the discharge occurs.

Example 1. We determine the parameters of the discharge circuit for descaling a brass tube with an external diameter of 16 mm and a wall thickness of 1 mm. Capacitor bank capacity C 20 μF, L 3000 nG, r 7 mm, lp.p. 2 mm, σ _t = 0.35 • 10 ⁹ Pa, Cd 30.67, ρ = 1000 kg / m ³ . Then, according to formula (1), we obtain the maximum allowable voltage at which it is necessary to clean Uo 3.05 kV. Experimental studies on the cleaning of such tubes showed that at a voltage of U 3.0 kV, the tubes are descaled without residual deformation. With a scale thickness of 1-1.5 mm, the cleaning speed is 2-3 m / min.

Example 2. We determine the parameters of the discharge circuit for descaling stainless steel pipes with an external diameter of 38 mm, wall thickness δ _t = 1.5 mm, C 10 μF, L 3000 nG, l.p. 6 mm, σ _t = 0.4 • 10 ⁹ Pa, Kd 30.67, ρ = 1000 kg / m ³ . The maximum allowable voltage determined by the formula (1) is 7.12 kV. The experiments showed that the cleaning of the above tubes at U 7 kV occurs without permanent deformation.

 Thus, the proposed method for cleaning the inner surface of the pipe helps to prevent destruction and damage to the surface of the pipe walls during the cleaning process.

 The present invention can be used to clean the inner surface of the pipes used in various technological processes in heat exchangers.

Information sources:
1. A. p. USSR N 1316037, MKI B08 B 9/00, F 28 G 7/00, priority 15. O5.84.

 2. International application N WO 91/01183, MKI B 08 B 9/02, 3/10, published 7.02.91.

Claims (1)

The method of cleaning the inner surface of the pipes, which consists in the fact that the working fluid is pumped through the pipe, the electro-hydraulic impact is applied to the inner surface using an electro-hydraulic emitter, which is moved inside as the pipe is cleaned, characterized in that the operating voltage to ensure electro-hydraulic shock is determined from the ratio

where K ₈ dynamic coefficient of strength of the pipe material;
s _t static yield strength of the pipe material, Pa;
δ _t pipe thickness, mm;
r pipe radius, mm;
L inductance of the discharge circuit of a capacitor bank, NG;
l _{p . n.} the length of the discharge gap, mm;
With capacitor bank capacity, microfarad;
ρ is the density of the medium in which the discharge occurs.