Study on the Coal Underground Gasification Reaction Characteristics Based on the Controlled Retraction Injection...

Area of Science:

• Energy Engineering
• Chemical Engineering
• Geological Engineering

Background:

• Modern coal underground gasification using the controlled retraction injection point (CRIP) process faces challenges including unstable gas quality and limited process control.
• A deeper understanding of the gasification reaction zone's distribution and expansion is crucial for technological advancement.

Purpose of the Study:

• To establish a 3D model of coal seam horizontal well injection underground gasification based on the CRIP process.
• To analyze the distribution of temperature fields and the heat-affected zone during a single gasification reaction cycle.
• To investigate the influence of gas flow rate, oxygen concentration, and gasification pressure on underground coal gasification.

Main Methods:

• Utilized COMSOL Multiphysics software to create a three-dimensional model.
• Simulated a single backward gasification reaction cycle.
• Analyzed temperature fields, heat-affected zone, and coal seam heat-affected boundary variations.

Main Results:

• Identified optimal gas flow rate (0.45 m/s) and oxygen concentration (60%) yielding a 0.08 m heat-affected boundary.
• Demonstrated that heat-affected boundary thickness increases significantly with gasification pressure, expanding from 0.04 m at 0.1 MPa to 0.23 m at 12.0 MPa.
• Characterized underground gasification reaction behavior for typical coal types.

Conclusions:

• The study provides scientific evidence for controlling and regulating CRIP process operating parameters.
• Understanding CRIP coal underground gasification reaction characteristics is key to improving process efficiency and stability.
• Optimizing gas flow rate, oxygen concentration, and pressure is essential for managing the heat-affected zone and enhancing gasification outcomes.