Duct-Lining Pig Outlet Channels for Uniform Thermoplastic Heating
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Solution Overview
Problem
Existing duct lining systems face limitations in achieving uniform heating of thermoplastic material 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 featuring a cylindrical heating chamber with annular coiled heating elements, a tree diffuser for gas distribution, and baffles to ensure uniform gas flow across heating coils, combined with an outlet diffuser that divides gas flow into discrete channels to enhance heating efficiency and prevent rotational flow, allowing for effective heating of thermoplastic material within ducts.
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 and be operated effectively, but the space available for heating air to sufficient temperature and ensuring uniform melting of thermoplastic material is limited
Solution Approach 1:
The heating chamber is divided into multiple zones with separate heating zones along the pig body, allowing temperature control in different sections. The air heating space is segmented into regions with different heating intensities to achieve uniform temperature distribution despite the limited overall pig length.
Solution Approach 2:
Different regions of the heating chamber are provided with different heating characteristics - some areas have higher heating intensity while others have lower intensity. This local differentiation ensures that the limited space within the 700mm pig can still achieve uniform hot air temperature through strategic placement of heating elements.
2Device complexity
If hot air is delivered without proper distribution design, then the heating process is simpler, but cold and hot spots occur in the fabric sleeve leading to points of weakness in the duct liner
Solution Approach 1:
The outlet structure is segmented into multiple air delivery outlets arranged around the pig circumference. Baffles divide the heating chamber into sections that direct hot air flow to different outlets, ensuring uniform distribution of hot air to the fabric sleeve and preventing localized overheating or underheating.
Solution Approach 2:
Baffles act as intermediary elements between the heating sources and the air delivery outlets. These intermediaries redirect and distribute the hot air flow uniformly across all outlets, transforming the simple heating process into a controlled uniform distribution system that prevents hot and cold spots.
3Device complexity
If the pig lacks proper gas distribution mechanisms, then the device structure is simpler, but uniform heating of the fabric sleeve cannot be achieved due to non-uniform hot air distribution
Solution Approach 1:
The gas distribution system is segmented into multiple channels and outlets positioned at different locations within the pig. This segmentation allows hot air to be delivered uniformly to different sections of the fabric sleeve, ensuring consistent heating throughout the liner formation process.
Solution Approach 2:
The gas distribution transitions from a single-dimensional flow to a three-dimensional distribution pattern through strategically positioned outlets and baffles. This dimensional transformation ensures uniform hot air delivery around the entire circumference of the fabric sleeve, achieving reliable heating uniformity.
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 uniform heating of thermoplastic material within ducts, preventing cold and hot spots and ensuring the formation of a strong, consistent liner, even around curves and longer duct lengths, thereby improving the quality and reliability of the lining process.
Implementation Method 1
heating air to a temperature sufficient to ensure adequate heating of the fabric sleeve and also to ensure uniform melting of the thermoplastic material
Implementation Method 2
melt the thermoplastic material and allow the formation of a hard sleeve in situ in a duct
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.