Speed Regulated Pipeline Pig With Modulating Valve
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Solution Overview
Problem
Pipeline pigs face challenges in controlling speed and preventing stalling and surging in high-velocity pipelines, as existing speed control devices rely on sophisticated control means and fail to optimize speed reduction, leading to ineffective dispersal and cleaning processes.
Innovation Solution
A pipeline pig equipped with a modulating valve that allows a predetermined maximum bypass flow, instantly reducing to a minimum when stalling occurs, and then reopening to prevent surging, utilizing a poppet-style or frusto-conical valve mechanism to regulate speed and maintain efficient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the pig travels at the same speed as the pipeline fluid without speed control, then the device complexity is minimized, but the pig cannot maintain effective operating speed in high-velocity pipelines and may stall or surge
Solution Approach 1:
The pig incorporates an automatic speed control system that regulates its own speed without external control. The bypass valve and spring mechanism automatically adjust bypass flow based on pig speed, allowing the pig to self-regulate its speed within the effective range without requiring complex external control systems.
Solution Approach 2:
The invention uses fluid pressure differential across the pig to drive the bypass valve mechanism. The pneumatic/hydraulic pressure difference automatically controls the valve position, which in turn controls the bypass flow and pig speed, creating a self-regulating system that avoids complex electronic or mechanical control devices.
2Reliability
If passive speed control devices allow more bypass flow when the pig stalls, then debris may be flushed out to allow the pig to start again, but the valve does not prevent the pig from stalling or controlling speed surges
Solution Approach 1:
The spring-loaded bypass valve creates a feedback mechanism where spring pressure opposes fluid pressure differential. When pig speed decreases, the pressure differential increases, overcoming spring pressure to open the valve and increase bypass flow, which reduces the pressure differential and prevents excessive speed increases. This automatic feedback control prevents both stalling and surging.
Solution Approach 2:
The bypass valve dynamically adjusts the bypass flow area based on operating conditions. The valve opening varies continuously with the balance between spring force and fluid pressure differential, allowing the system to adapt to changing pipeline conditions and maintain stable pig speed without fixed orifice limitations.
3Measurement precision
If valve-actuated control devices use active control means to regulate bypass flow, then speed control precision is improved, but the device complexity and cost increase significantly
Solution Approach 1:
The pig incorporates an automatic speed control system that regulates its own speed without external control. The bypass valve and spring mechanism automatically adjust bypass flow based on pig speed, allowing the pig to self-regulate its speed within the effective range without requiring complex external control systems.
4Ease of operation
If the pig speed is not regulated, then the ease of operation is maximized, but the dispersal and cleaning processes become ineffective due to speed being outside the desired range
Solution Approach 1:
The pig incorporates an automatic speed control system that regulates its own speed without external control. The bypass valve and spring mechanism automatically adjust bypass flow based on pig speed, allowing the pig to self-regulate its speed within the effective range without requiring complex external control systems.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The modulating valve effectively reduces the pipeline pig's speed to a small percentage of the average fluid flow velocity, preventing stalling and surging, ensuring consistent and effective dispersal and cleaning operations.
Implementation Method 1
the pressure increase at the rearward end of the pig causes the valve member to move farther into the sleeve, thereby blocking the front ports and reducing flow through the valve and, therefore, increasing bypass flow though the pig. The reduced flow through the valve further increases the pressure differential across the pig, and, therefore, the speed of the pig increases.
Implementation Method 2
Both categories of speed control devices work by altering the amount of bypass flow through the body of the pig.
Implementation Method 3
The central passageway includes a venturi preferably concentric to the pig body. The venturi may be provided by a nozzle affixed to the forward end of the pig.
Data Source
AI summary
A pipeline pig includes a venturi and a modulating valve located rearward of the inlet side of the venturi. When the valve is in the open position, a predetermined maximum bypass flow is allowed through the venturi. The closed position allows a predetermined minimum bypass flow. The valve may be a poppet-style valve or a frusto-conical shaped stopper. The stopper has sufficient mass and/or aerodynamic drag to overcome the spring force holding the valve in the open position. When the pig stalls, the valve closes and the stopper chokes bypass flow through the venturi. When the pig starts running again, the valve opens as inertia forces the stopper away from the inlet side of the venturi. Also, as friction of the pig increases due to changes in the internal diameter of the pipeline or accumulation of debris ahead of the pig, increased airflow across the valve creates drag sufficient to partially overcome the spring force, thus keeping the pig moving at a desirable rate of travel.