Design of automatic control system for underground hydraulic fracturing in coal mine

The analysis points out that the current hydraulic pressure technology in coal mines faces challenges such as the inability to quickly and accurately adjust the output pressure and flow rate of fracturing pumps, the need to improve the remote safety monitoring effect, and the level of automation. An underground hydraulic fracturing automatic control system in coal mine has been designed. Based on the hydraulic fracturing technology and system composition in coal mines, it is clear that the key technologies of the control system include rapid and precise adjustment of the output flow and pressure of high-pressure and high flow fracturing pumps, remote high reliability and safety, high-speed real-time monitoring, one click start stop, and graphical analysis. Based on the KXH12 intrinsic safety controller as the core, combined with frequency converters, combination switches, monitoring hosts, electric valves and other equipment, as well as a dual line redundant communication scheme with fiber optic and CAN bus, the control system hardware has been developed. The fracturing pump controller, water tank controller, and central controller software have been developed. It achieves functions such as fast variable flow water injection, stable pressure maintenance, remote high-speed real-time monitoring and alarm of the fracturing system. Industrial tests are conducted on the hydraulic fracturing automatic control system at the coal mine site, and the results show that the pressure control precision of the system is 0.1 MPa, and the flow control precision is 0.1 m³/h. During 14 consecutive fracturing processes, good pressure retention effects are achieved after each coal layer crack. The operation is simple with high safety, meeting the requirements of hydraulic fracturing technology in coal mines underground.