Plasma Torch Boring with Closed-Loop Spall Control
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Solution Overview
Problem
Current underground boring methods using plasma technology face challenges in efficiently removing material while minimizing energy consumption and maintaining consistent spoil characteristics, particularly when dealing with geologies containing high proportions of crystals like SiO2, which tend to melt or decompose, leading to complex spoil removal and increased energy use.
Innovation Solution
A method and system that utilize a plasma torch with closed-loop controls, adjusting power, gas flow rate, and standoff distance based on real-time temperature profiles and spall fragment characteristics to fracture and disintegrate rock without melting, thereby reducing energy consumption and simplifying spoil removal by maintaining a target spall size and minimizing molten material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If plasma power is increased to improve material removal rate, then productivity increases, but energy consumption increases and crystalline materials melt or decompose
Solution Approach 1:
The system employs real-time feedback control by monitoring spall fragment characteristics (size, shape, velocity) and adjusting plasma power, gas flow rate, and standoff distance to maintain optimal boring conditions. This feedback mechanism prevents excessive energy input that would cause melting while maximizing material removal through controlled spallation.
Solution Approach 2:
The system dynamically changes multiple parameters (plasma power, gas flow rate, standoff distance) based on real-time conditions to optimize the balance between material removal rate and energy consumption. By adjusting these parameters in response to feedback, the system maintains efficient spallation without reaching temperatures that cause crystalline decomposition.
2Productivity
If plasma power is increased to fracture crystalline materials, then material removal efficiency improves, but the materials melt or decompose leading to complex spoil
Solution Approach 1:
Real-time monitoring of spall fragment characteristics provides feedback that enables dynamic adjustment of plasma parameters. This ensures materials are fractured into consistent spall fragments without reaching decomposition temperatures, maintaining stable spoil characteristics suitable for backfill applications.
Solution Approach 2:
The system replaces thermal processing (melting) with mechanical spallation processes. By controlling plasma parameters to induce mechanical fracture rather than thermal decomposition, the system achieves efficient material removal while maintaining consistent spoil characteristics without phase changes.
3Productivity
If plasma torch is positioned closer to bore face to increase energy density, then material removal rate improves, but temperature control becomes difficult and equipment life decreases
Solution Approach 1:
The system dynamically adjusts the standoff distance between the plasma torch and bore face based on real-time feedback from spall fragment monitoring. This dynamic positioning allows the system to optimize energy density for material removal while maintaining temperature control within safe limits, preventing equipment damage and extending operational life.
4Productivity
If conventional plasma boring is used on crystalline geologies, then material removal is achieved, but post-processing is required due to molten and decomposed materials
Solution Approach 1:
The system replaces thermal processing with mechanical spallation, producing clean fragments without melting or decomposition. This eliminates the need for post-processing of spoil materials, making them immediately suitable for backfill applications and significantly reducing preparation time and complexity.
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 system effectively fractures rock at the bore face, reducing energy consumption and extending equipment life by controlling the temperature near crystalline decomposition points, achieving efficient material removal with less complex spoil, and minimizing the need for post-processing.
Implementation Method 1
boring with plasma
Implementation Method 2
remove material from the bore face
Implementation Method 3
interpreting a temperature profile across the bore face based on intensities of intransient pixels
Data Source
AI summary
Systems to bore or tunnel through various geologies in an autonomous or substantially autonomous manner can include one or more non-contact boring elements that direct energy at the bore face to remove material from the bore face through fracture, spallation, and removal of the material. The systems can automatically execute methods to control a set of boring parameters that affect the flux of energy directed at the bore face. Systems can further automatically execute the methods to trigger an optical sensor to capture images at the bore face, generate temperature profiles, identify spall fragments and hot zones and/or adjust a set of boring controls. For example, the system can execute methods to adjust a standoff distance between the system and the bore face, and adjust power and/or gas supply to the non-contact boring element.