RU2293612C2 - Inter-tube inspection tool at controllable speed of motion - Google Patents

Abstract

FIELD: inter-tube tools for inspection of pipe lines at high stabilization of speed of motion.

SUBSTANCE: proposed tool has cylindrical body with front and rear supports in form of circular collars mounted between body and pipe line, tool speed sensor, control unit and drive for adjustment of gas bypass. Tool is provided with bypass system including six double-loop gas bypass sections with central passage provided with nozzle and passage of second loop having nozzle in form of deflector and throttle valve secured in one module in tool body.

EFFECT: enhanced stabilization within preset limits flaw detector speed due to outflow of gas in nozzles.

3 dwg

Description

The device relates to in-pipe shells for inspection of pipelines with increased stabilization of the speed of movement.

Known flaw detectors for in-line inspection of pipelines (patent RU No. 2102738, IPC G 01 N 27/87). The projectile is equipped with a bypass pipe for bypassing the product transported through the pipeline being examined and an automatic speed control system containing a speed sensor, a control unit with a speed sensor and a regulating body in the form of a brake device interacting with the pipe wall.

The disadvantage of this projectile is the adjustment of speed only due to friction forces, which lead to increased wear of the walls of the pipeline and the contact surface of the brake device. In addition, the introduction of an electromagnet for a braking device requires a lot of energy, and the battery power is limited.

A well-known container of a pipeline pneumatic transport installation (A.S. SU No. 117353, IPC B 65 G 65/06, BI No. 31, 1985), comprising a housing with a mechanical seal and channels for communicating high and low pressure areas in the pipeline, symmetrically located relative to the longitudinal axis of the housing, stabilizing elements and a rotary valve relative to this axis with a counterweight to block the inlet openings of the channels. The stabilizing elements are radial plates fixed along the container body, made with a seal on its free longitudinal edge, with the plates mounted at an acute angle to one another in the direction of the rear of the container.

The use of a stabilizer improves the process of passing curved sections of the track without reducing speed and reduces wear on the tires of the running wheels. However, this device does not allow speed control in rectilinear motion and in curved sections in a vertical plane.

The scraper for cleaning the inner surface of the pipeline with variable speed (US patent No. 5208936 from 05/11/1993, MKI B 08 B 9/04) consists of a cylindrical body with a first and second open end face of the ring seal between the pipe and the body, a shut-off element located inside the body to block the flow of fluid passing through the housing, but passing through numerous second holes, the first holes include devices that come into contact with the second holes, which are bypass channels, o limiting values of the flow of passing fluid, scraper speed sensors, controls, drive and closing means. The first and second holes are located around the circumference around the first and second plates, and the bypass channels include numerous tubes, form a Central cavity between the corresponding tubes of the first and second holes.

With a maximum gas bypass, this device does not allow to stabilize the velocity of the in-tube projectile due to the plates blocking the gas flow, and the large ellipse in the cross section of the pipeline sections, on the turning sections in the vertical plane. Speed stabilization in magnetic flaw detectors becomes an urgent problem, and it is especially necessary where it is detuned from it in the digital processing unit (Abakumov A.A., Abakumov A.A. (Jr.) Magnetic diagnostics of gas and oil pipelines. - M .: Energoatomizdat. - 2001. - p. 395).

The devices used for gas bypass in closed volume pipelines are identical to throttling valves. The gas flow rate at regimes close to the critical gas flow is sensitive to changes in the cross section of the channel (G. Abramovich. Applied gas dynamics. M.: Nauka, 1969 - p. 138). Relations are known, for example, a change in the channel cross section by 1% changes the gas flow rate by ≈10%, i.e. in Mach numbers, respectively, from M = 0.9 to M = 1.0, which leads to pulsation of the speed of movement when moving the magnetic flaw detector. The aerodynamic loads that act on the flaw detector to balance with mechanical devices or energy converters in closed volume pipelines is a laborious task to implement and is a difficult technical problem.

The objective of the invention is the stabilization within specified limits of the speed of movement of the magnetic flaw detector due to the processes of gas flow in nozzles, proposed for use for mass bypass gas in the bypass system of the flaw detector.

This goal is achieved due to the fact that in the in-tube inspection projectile with a controlled speed of movement, containing a cylindrical body, with front and rear support in the form of annular cuffs between the body and the pipeline, a projectile velocity sensor, a control unit and a drive for adjusting gas bypass are introduced a bypass system of six double-circuit gas bypass sections with a central channel with a nozzle and with a second channel of the circuit with a nozzle in the form of a deflector and a throttle using ejector workflows at small x pressure drops attached to the fairing body section and the base wall, which are integrally formed with the projectile design flaw detector in one module. The regulatory body of the coordinated regimes of the outflow of gas flows in the channels allows you to effectively manage aerodynamic loads during the movement of the flaw detector in the pipeline.

Figure 1 shows the proposed in-line inspection projectile with a controlled speed of movement, figure 2 is a view of a dual-circuit gas bypass system, figure 3 is a view of a bypass system module.

The projectile contains a cylindrical housing 1, defect information sensors 2, a magnetic core 3, a front support in the form of an annular cuff 4, a rear support in the form of an annular cuff 5, a bypass system 6, an input channel 7, a thermal container 8 with electrical equipment, a bypass system control unit 9 of six dual-circuit gas bypass sections, the output channel 10, odometric sensors for the velocity of the projectile 11. The dual-circuit gas bypass system consists of a central channel housing 12, a deflector (a device for passing the second gas outflow) 13, throttle 14, inlet fairing 15, the central channel of the first circuit 16, the outer channel of the controlled second circuit 17.

The central channel is characterized by the following parameters: inlet diameter, inlet area of the central channel of all sections, inlet radius of the central channel, narrowing angle of the nozzle inlet, critical diameter of the central channel, critical area of all sections, expansion angle of the nozzle outlet, outlet diameter, outlet area of the central channel.

The throttle device has the following parameters: constructive outer diameter of the throttle, hole diameter, their number, throttle area of all sections, throttle coefficient of the device.

The second channel is characterized by the following parameters: diameter of the forming shell, rounding radius of the forming shell, initial diameter of the inner cone, final diameter of the inner cone, rounding radius, transition to the cone, the angle of the forming cone, the area of the second channel in the middle section, the output diameter of the diffuser section, the diffuser angle, the area of the output section of the diffuser of the second channel, the total area of the output section of the first and second channels.

Works in-tube inspection shell as follows. When the projectile-flaw detector moves through the pipeline on supports 4 and 5, the information sensors 2 register the magnetic fields of scattering of defects in the metal of the pipe walls due to a change in the magnetic flux in the casing 1 and the magnetic circuit 3. The module of the projectile-flaw detector is based on the magnetic defectoscopy method, which analyzes magnetic scattering fields defects in the metal walls of pipelines. In the pressurized container 8, the electronic storage device stores all the information on the technical condition of the studied pipeline. In the electrical equipment module of the pressurized container 8, the limits for changing the velocity of the projectile recorded by odometer sensors 11 are also set. In the bypass system 6, due to the outflow of gas flows, the velocity of the projectile is stabilized due to the outflow of gas with consistent mass flow rates of gas through the Central channel 16 and the second circuit 17 in the housing 12.

Thus, an in-line inspection projectile with a controlled speed of movement, equipped with a bypass system 6 with a varying bypass ratio, projectile velocity sensors 11, a control unit and a drive unit 9, a front cuff 4 and a rear cuff 5, provides the required speed of the flaw detector due to gas bypass , while maintaining operational modes of pumping gas in pipelines.

The double-circuit modification of gas bypass, integrated with the design of a flaw detector in one module, is performed using stationary profile channels on the principle of double-circuit gas outflow:

- the Central stream through the channel of the primary circuit with nozzle 16;

- external flow through the channel of the second circuit with the nozzle 17.

The ejector system of the second circuit is made in the form of a deflector 13, a throttle 14, mounted on the fairing 15 of the shell of the shell.

In the bypass system, the aerodynamic principles of the gas flows of the "geometric" nozzle are implemented in conjunction with the "flow" nozzle. The introduction of a dual-circuit design of tubular channels satisfies the condition of mass gas bypass through stationary channels: the internal circuit has critical and supercritical flow regimes; the external circuit is set to a subcritical expiration mode. Each circuit is in a coordinated mode of gas flow outflow by mass flow. To stabilize the speed of movement of the projectile flaw detector, the secondary gas flow of the external circuit is throttled. The limited gas flow during throttling of the "flow" nozzle is used to perform technical work on moving the projectile. The aerodynamic efficiency of the gas flow occurs with a positive component of the gas pulse, the dynamics of the flaw detector is determined by the bypass system bypass degree.

The mechanism of the outflow of gas flows in the working section is identical to the processes in the ejector stage with critical operating conditions. The peculiarity of the operation of the stage is determined by the nature of the flow in the initial section of the mixing chamber, that is, by the presence of a cross section in which the ejector can be locked. In this case, the gas stream of the central nozzle fills the entire cross section of the second channel; in the locking mode, the reduced flow rate of the second stream is zero.

The apparatus is affected by the total impulse of the second gas stream, therefore, the apparatus is set in motion, movement can occur with a high gradient of the increment of speed, therefore, the locking mode in the working section should not be encountered during diagnostic monitoring of pipelines.

The working scheme of the gas bypass system has 6 (six) sections, each uses a calculated supersonic nozzle and a flow nozzle with subcritical gas flow. At small angles of profiling of the supersonic nozzle (γ = 10 ° ... 12 °), we can take constant the parameters of the central gas flow over the entire area of the outlet cross section without any special errors for calculation. The use of a supersonic nozzle allows for given initial parameters and gas flow rates to obtain a section design with a smaller mixing chamber area, to have lower energy losses of the gas stream and to exclude overexpansion of the central stream in the blocking section.

The reactive force of the gas stream moving the projectile is determined by the formula:

Where

ΔР is the pressure drop across the projectile, the gas velocity in the pipeline, the velocity of the projectile, and K _y is the gas leakage coefficient.

The reduced gas flow velocity and gas-dynamic functions are

R _G = 51.2 - kgf · m / kg · K - gas constant for gas; k _g is the adiabatic exponent for gas; q (λ _Tr ) is the reduced density of the gas mass flow; z (λ _tr ) is the reduced total momentum of the gas flow, S _tr is the pipe area, W _tr is the gas velocity.

The total component of the reactive force from the two gas flows of the double-circuit modification of the gas bypass with active throttling of the second circuit is equal to:

The gas flow rate of the second circuit during the throttling of the "flow" nozzle decreases in proportion to the decrease in the passage area of the deflector, at the same time the losses increase and, accordingly, the coefficient of recovery of the total gas pressure when the gas flows through the deflector decreases.

The gas flow rate limited by the throttle of the “flow” nozzle is capable of performing technical work and is the source of the force that the projectile can move. When the gas is completely bypassed through a double-circuit modification, the central gas stream expires at a transonic speed from six "geometric" nozzles, the secondary gas stream freely flows from the six annular channels of the "flow" nozzles. During throttling of the secondary gas stream, gas accumulates in front of the projectile, a uniform load from the working pressure of the gas is distributed on the end surface of the projectile, and an equivalent force of the gas stream arises. This force is determined by the value of the working pressure in the pipeline and some equivalent projectile area.

The pneumatic drive of the second channel is made by a cylindrical chamber with an axial size of L ₁ , and the inner diameter is limited by the casing of the magnetic circuit. The left wall - the diaphragm has a group of holes for filling the chamber with gas, the right wall is an additional support of the nozzle sections, an unloading valve is installed on the wall. Power springs are installed in the chamber, which close the throttle device of the second channel.

When pressure is applied to the storage chamber of the main pipeline, the “nozzle” chamber is filled with gas through the diaphragm separator of the throttle device. The gas pressure in front of the diaphragm and in the chamber of the "nozzle" are balanced, the throttle is held in its original position by the chamber spring. The working pressure in the chamber through the nozzle hole acts on the piston, together with its spring, holds the discharge valve in the closed position.

The pressure rises gradually, reaches a value of ≈20 kgf / cm ² and opens the ball valve. After the ball valve is opened, the gas pressure above the piston will drop due to the throttle action of the nozzle compared to the pressure, and the main valve will rise, and the pressure P ' ₁ will drop to a value at which the gas flow through the ball valve will be equal to the amount of gas that enters through the nozzle hole. By changing the pre-compression force of the ball valve spring, the adjustment of the discharge valve can be changed. With an increase in the compression force of the ball valve spring, the pressure at which the discharge valve opens will increase, and the working pressure in front of the piston of the discharge valve will increase accordingly. Until the operating pressure rises to P'1, the main valve will be closed and the gas flow through the discharge valve will be determined by the flow through the ball valve. When a pressure of P'1 is reached, the working pressure remains constant regardless of the gas flow rate through the safety valve and the nozzle orifice.

The gas pressure acting on the main valve overcomes the spring pretension force, the valve moves from its seat and opens the gas passage from the “nozzle” chamber. The pressure in the chamber will decrease, on the left wall - the diaphragm, a force will appear in the direction of the action of the unbalanced force, i.e.

where p ₁ is the gas pressure in front of the sections of the "nozzle"; p ' ₁ - gas pressure in the pneumatic drive chamber; F _diaph - the aperture area; P _CR - the tightening force of the spring; S _p - the friction force of rest of the main valve.

A full-scale bypass system module with a double-circuit modification for a flaw detector projectile with a pipeline dimension of Du = 1400 mm was developed and manufactured.

Claims (1)

An in-line inspection projectile with a controlled speed of movement, comprising a cylindrical body, with front and rear bearings in the form of annular cuffs between the body and the pipeline, a projectile velocity sensor, a control unit and a drive for adjusting gas bypass, characterized in that a bypass system of six double-circuit gas bypass sections with a central channel with a nozzle and a secondary circuit channel with a nozzle in the form of a deflector and a throttle mounted in one module on the shell of the projectile.

Images