Multi-stage Combustion Impact Wave Coal Cracking Method
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Solution Overview
Problem
Current coal mass pressure relief technologies, such as deep hole blasting, are hazardous and inefficient due to limited influence scope, low pressure relief, small drill hole flow, high attenuation coefficients, and complex underground conditions, making them risky and difficult to operate.
Innovation Solution
A multi-stage combustion impact wave coal mass cracking and heat injection alternating method involves constructing an impacting and heat injecting drill hole with a porous cylinder and piston, using a combustion chamber to generate high-temperature and high-pressure impact waves that crack coal masses, followed by high-temperature vapor injection to enhance gas extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If deep hole blasting technology is used for coal mass pressure relief, then gas extraction efficiency can be improved, but safety risk increases and operation becomes complicated
Solution Approach 1:
The patent replaces the traditional mechanical blasting system with a combustion impact wave system. Instead of using explosive charges and detonation, the invention uses controlled combustion of gas mixtures to generate impact waves that propagate through the coal mass, achieving pressure relief without the safety hazards of blasting operations
Solution Approach 2:
The patent changes the physical parameters of the pressure relief process by using controlled combustion to generate impact waves with specific pressure ranges (5-50 MPa). The combustion process allows precise control of wave intensity through gas composition and injection parameters, providing a safer alternative to blasting while maintaining effectiveness
2Productivity
If deep hole blasting technology is used for coal mass pressure relief, then gas extraction efficiency can be improved, but device complexity and operation difficulty increase
Solution Approach 1:
The patent replaces complex mechanical blasting equipment with a combustion-based system using gas injection pipes and ignition devices. This substitution simplifies the overall system structure and reduces operational complexity while achieving the same pressure relief effect
Solution Approach 2:
The combustion impact wave system utilizes the coal seam gas itself as part of the fuel mixture, reducing the need for external materials. The system automatically generates the required impact waves through controlled combustion, eliminating the need for complex blasting charge placement and detonation control procedures
3Area of stationary object
If conventional drill hole extraction is used, then gas can be extracted, but influence scope is limited and pressure relief is insufficient
Solution Approach 1:
The patent employs periodic injection of gas mixtures into the combustion chamber, generating repeated combustion cycles that produce multiple impact waves. This periodic action extends the influence scope by repeatedly fracturing and loosening the coal mass over time, increasing both the affected area and pressure relief effectiveness
Solution Approach 2:
The combustion process involves phase transitions of the gas mixture from unburnt to burnt state, generating rapid expansion and pressure waves. This phase transition mechanism enables the system to achieve wide influence scope and effective pressure relief through controlled energy release in the coal mass
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
This method significantly enlarges the crack aperture in coal masses, increases gas extraction efficiency, and is safer, more cost-effective, and easier to operate, effectively addressing the limitations of existing technologies by extending the pressure relief scope and improving gas flow.
Implementation Method 1
combustible gas and auxiliary gas are injected into the combustion chamber; the combustible gas in the combustion chamber is ignited by a control system, wherein impact wave generated by combustion of the combustible gas
Implementation Method 2
the heat injection pipe is opened to inject high-temperature vapour into the impacting and heat injecting drill hole by the heat injection and gas injection extracting pipe
Data Source
AI summary
A multi-stage combustion impact wave coal mass cracking and heat injection alternating intensified gas extracting method is provided. A large amount of N2 or CO2 is injected into a drill hole by a heat injection and gas injection extracting pipe and by a high-pressure gas cylinder and a reducing valve, then a certain amount of methane and dry air are injected into a high-temperature and high-pressure combustion chamber by the high-pressure gas cylinder and the reducing valve, to be mixed and combusted to form high-temperature and high-pressure impact wave. High-temperature vapour is injected into the drill holes by the heat injection and gas injection extracting pipe to promote desorption of the coal masses.