WO2009067769A1

WO2009067769A1 - System for locating pigs in single phase and multiphase fluid transport pipelines

Info

Publication number: WO2009067769A1
Application number: PCT/BR2008/000280
Authority: WO
Inventors: Julio Roberto Alonso
Original assignee: Asel-Tech Technologia E Automação Ltda.
Priority date: 2007-11-30
Filing date: 2008-09-11
Publication date: 2009-06-04
Also published as: BRPI0705728A2

Abstract

This patent refer to a System For Locating Pigs In Single Phase And Multiphase Fluid Transport Pipelines capable of continuously determining the position of the pig all along the pipeline, characterized by use pressure sensors (1) strategically located along the pipeline (2), local processors (3) responsible for picking up and processing the pressure signals, a network communication system (4) between the local processors (3) and the microcomputer (5) for viewing the position of the pig via an HMI monitoring Interface and external communications via the network communication system (4), a microcomputer (5) and autonomous devices (6) capable of producing an oscillation in the pig displacement velocity relative to the flow velocity and generates a fluid dynamic transient whose main effect is the formation of acoustic pulses (7). AUTOMA

Description

"SYSTEM FOR LOCATING PIGS IN SINGLE PHASE AND MULTIPHASE FLUID TRANSPORT PIPELINES".

1.- PRELIMINARY CONSIDERATIONS Pipelines are widely used for the transport of fluids, both for industrial applications over long distances and for distribution systems when a given fluid must be delivered to a large number of users or processes via a pipeline network. In both cases, for a safe and efficient operation, it is necessary to carry out periodic inspections of the pipeline, whether this is to identify structural damage caused by corrosion, impacts and manufacturing defects; or to carry out cleaning operations, such as the removal of paraffin's, for example. To do this, devices known as PIG's or Pipeline Inspection Gear are usually used. These are introduced into the pipeline and are carried along by the flow.

2.- BACKGROUND OF THE INVENTION There are different types of pigs, depending on the application that they are to be used in. For example, the separation of different fluids transported in the same pipeline or multi-pipeline, can be guaranteed using a pig which is usually spherical and made from an inert material. To remove incrustation from the walls of the pipeline, scraper pigs that are fitted with brushes or other types of scraping devices, which remove the accumulated material, are used. For more complex applications, instrumented pigs fitted with different types of sensors or electronic components: magnetic, ultrasound or mechanical deformation sensors, can be used.

The use of instrumented pigs provides reliable results that can be used as a basis for efficient decisions on repairing any damage detected.

Leak detection is an important application where instrumented pigs can be successfully applied. Under normal conditions, leaks can be detected through direct inspection, the monitoring of chemical emissions. the installation of optical fibers along the pipeline or by the acoustic emissions caused by the rupture of the walls of the pipeline.

For this purpose, a pig can be fitted with a differential pressure sensor that is able to measure the pressure difference between its front and back sides and denominated propulsion pressure. This difference, i.e. the loss of localized pressure in the pig whose integral is equal to the friction forces, undergoes a significant perturbation at the moment that the pig passes the leak point.

3.- TECHNOLOGICAL DEVELOPMENT

In spite of its capacity for detecting a leak, one important limitation of this technique is its inability to locate the position of the leak with the necessary accuracy.

To this effect, this invention makes a significant contribution to improving this leak detection technique because, by monitoring the displacement of the pig in the pipeline, it is possible to accurately determine the place where the propulsion pressure was perturbed by the leak.

Another situation where it is crucial to determine the position of the pig in the pipeline occurs due to the presence of dents or internal imperfections which prevent the pig from moving. In this case, exact knowledge of the place where the pig is trapped allows for intervention actions which cause the minimum of damage to the pipeline.

4.- DESCRIPTION OF THE DRAWINGS

To obtain a full and complete picture of how this

System For Locating Pigs In Single Phase And Multiphase Fluid Transport Pipelines, matter and object of the present patent of invention, is constituted, follow-up the illustrative drawings in annex, which makes reference as below:

Figure 1 : It represents an schematical sight or view of the System For Locating Pigs In Single Phase And Multiphase Fluid Transport Pipelines.

Figure 2: It corresponds at sight schematical of the operational form for detection pigs. 5.- DESCRIPTION OF THE INVENTION As deduced from the drawings that follows and is part of this report, the System For Locating Pigs In Single Phase And Multiphase Fluid Transport Pipelines involves a system that is capable of continuously determining the position of the pig all along the pipeline. This system is characterized by use pressure sensors (1) strategically located along the pipeline (2), local processors (3) responsible for picking up and processing the pressure signals, a network communication system (4) between the local processors (3) and the microcomputer (5) for viewing the position of the pig via an HMI monitoring Interface and external communications via the network communication system (4).

As well as these external components, the System For

Locating Pigs, which is the object of this invention, includes an acoustic pulse generating device (6) to be installed in the pig. This is described in further detail below, and the operating principals of this invention are shown in the diagram in Figure 2.

Acoustic pulses are generated by a specific autonomous device (6) capable of producing an oscillation in the pig displacement velocity relative to the flow velocity. This oscillation generates a fluid dynamic transient whose main effect is the formation of acoustic pulses (7) which propagate at the speed of sound upstream and downstream the pipeline and are picked up by the pressure sensors (1).

Different autonomous devices (6) can be installed in the pig with the aim of generating periodic acoustic pulses. For example, a solenoid valve can be installed in order to alleviate the propulsion pressure as the pig passes through the fluid and, consequently, to reduce its velocity whilst it remains open. Alternatively, a braking device consisting of retractable levers, which when activated drag along the walls of the pipeline slowing the pig down, can be used. The acoustic pulses generated by the device (6) picked up by the pressure sensors (1) are sampled by the local processors (3) which compare them to the standard forms that have already been stored in their memories. This comparison can be carried out by different signal processing algorithms such as, for example, correlative filters or with the help of neural networks. Once the arrival times for each pulse have been determined, the pig can be located using the following formula:

L-V_A (Td-Te) 2 where x represents the position of the pig with respect to the nearest pressure sensor, L denotes the distance between the pressure sensors, VA indicates the acoustic propagation velocity and, Td and Te indicate, respectively, the times at which the pulse arrives at the pressure sensors (Td > Te), as shown in Figure 2. Once the variable x has been determined, it is transmitted through the network (5) to the microcomputer (6) so that the position of the pig can be updated in the HMI. 6.- CONCLUSION

It is verified that for all hat was described and illustrated concerning the System For Locating Pigs In Single Phase And Multiphase Fluid Transport Pipelines, which perfectly fits into the standards that rules the Patent of Invention just to fill important missing piece in the market, deserving from what was exposed and consequently the respective privilege.

Claims

1) "SYSTEM FOR LOCATING PIGS IN SINGLE

PHASE AND MULTIPHASE FLUID TRANSPORT PIPELINES", capable of continuously determining the position of the pig all along the pipeline, characterized by use pressure sensors (1), local processors (3), network communication system (4), microcomputer (5) and autonomous devices (6).

2) "SYSTEM FOR LOCATING PIGS IN SINGLE

PHASE AND MULTIPHASE FLUID TRANSPORT PIPELINES", characterized according to claim number one because the pressure sensors (1) are strategically located along the pipeline (2).

3) "SYSTEM FOR LOCATING PIGS IN SINGLE

PHASE AND MULTIPHASE FLUID TRANSPORT PIPELINES", characterized according to claim number one because the local processors (3) are responsible for picking up and processing the pressure signals. 4) "SYSTEM FOR LOCATING PIGS IN SINGLE

PHASE AND MULTIPHASE FLUID TRANSPORT PIPELINES", characterized according to claim number one because its have a network communication system (4) between the local processors (3) and the microcomputer (5) for viewing the position of the pig via an HMI monitoring Interface and external communications via the network communication system (4).

5) "SYSTEM FOR LOCATING PIGS IN SINGLE

PHASE AND MULTIPHASE FLUID TRANSPORT PIPELINES", characterized according to claim number one because its have an autonomous device (6) capable of producing an oscillation in the pig displacement velocity relative to the flow velocity and generates a fluid dynamic transient whose main effect is the formation of acoustic pulses (7).