Pipe Lining Pig With Radial Hot-Air Diffuser for Uniform Heating
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Solution Overview
Problem
Existing duct lining systems face limitations in achieving uniform heating of thermoplastic materials within fabric liner sleeves due to restricted pig length and non-uniform hot air distribution, leading to potential cold and hot spots and weaknesses in the formed liner.
Innovation Solution
A pig design with an outlet diffuser and baffles within a heating chamber, featuring a central core and coiled heating elements, ensures efficient gas flow and uniform heating by directing gas across the heating elements, and a shroud for centering and sealing, enhancing heating efficiency and uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the pig length is limited to around 700 mm for practical navigation, then the pig can navigate curves in the pipe, but the space available for heating air to sufficient temperature is limited
Solution Approach 1:
The heating chamber is divided into multiple zones with separate heating elements (first heating element in the first zone, second heating element in the second zone). This segmentation allows each zone to be heated independently, ensuring sufficient temperature rise within the constrained pig length while maintaining navigation capability.
2Device complexity
If hot air is delivered from the pig without uniform temperature distribution, then the heating process is simpler, but cold and hot spots occur in the fabric sleeve leading to points of weakness
Solution Approach 1:
The outlet diffuser incorporates multiple radially spaced outlets that distribute hot air at different locations around the pig circumference. Each outlet delivers hot air to a specific zone of the fabric sleeve, ensuring uniform local heating throughout and preventing cold or hot spots that would create weak points in the formed liner.
Solution Approach 2:
The outlet diffuser acts as an intermediary device between the heating chamber and the fabric sleeve. It receives hot air from the heating chamber and redistributes it uniformly through multiple radial outlets, transforming the concentrated heat source into a distributed heating pattern that ensures even temperature distribution across the fabric sleeve surface.
3Device complexity
If the hot air delivery means is not carefully designed, then the device complexity is reduced, but uniform heating of the fabric sleeve around the circumference cannot be achieved
Solution Approach 1:
The outlet diffuser incorporates multiple radially spaced outlets that distribute hot air at different locations around the pig circumference. Each outlet delivers hot air to a specific zone of the fabric sleeve, ensuring uniform local heating throughout and preventing cold or hot spots that would create weak points in the formed liner.
Solution Approach 2:
The outlet diffuser design creates equipotential heating conditions by distributing hot air uniformly around the entire circumference of the fabric sleeve. All zones of the fabric sleeve receive equivalent thermal energy, ensuring consistent melting and formation of the liner without temperature variations that would compromise reliability.
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 solution enables effective and uniform heating of thermoplastic materials within ducts, preventing cold and hot spots, thus ensuring a robust and correctly formed liner with improved structural integrity.
Implementation Method 1
a pig (10) having a pig body (11) defining a longitudinal axis (7) that extends in a longitudinal direction from a rear portion (11a) to a front portion (11b)
Implementation Method 2
heating means in the form of an outlet diffuser (20) at the rear end (11a) of the pig body (11) for directing the heated gas in the heating chamber radially outwardly through a series of apertures (9) in the outlet diffuser (20)
Implementation Method 3
The thermoplastic material is melted by heating in situ in the pipe and then allowed to harden to form the tubular liner within the pipe
Data Source
AI summary
The present invention relates to a pig for use in a system for lining ducts such as water or sewage pipes or electrical ducts or gas pipes. The pig is insertable at least partly within a fabric liner sleeve located in a duct such as a water or sewage pipe and is capable of heating the liner sleeve in situ in the duct to melt or soften thermoplastic material of the liner sleeve to subsequently form, on cooling of the melted thermoplastic material, a rigid liner in the duct. A pig for fitting a liner to the inside of a pipe, comprising a pig body defining a longitudinal axis in a longitudinal direction from a front portion to a rear portion; a gas supply port in the front portion; a gas outlet diffuser forming part of the rear portion; a heating chamber in the pig body forming a flow path from the fluid inlet to the outlet diffuser; and a heater within the heating chamber, wherein the outlet diffuser comprises a plurality of channels, each channel comprising an inlet facing the front portion in the longitudinal direction and an outlet extending radially outwardly from the longitudinal axis.