I. System Overview
The new generation of intelligent and energy-saving local ventilation fans for mines is developed based on the current situation of mine ventilation in China and extensive research conducted in deep-seated coal mines. Aimed at reducing gas accidents, these fans are designed with the objectives of "safety and reliability, energy conservation and environmental protection," featuring "modular units, personalized combinations, real-time monitoring, and intelligent control." They achieve the effects of "real-time early warning, dual control by both man and machine, demand-driven air supply, and disaster prevention and mitigation," thus filling the gap in the intelligent control field of local ventilation in Chinese mines.
II. System Composition
The system consists of FBD series coal mine explosion-proof axial flow fan units, explosion-proof and intrinsically safe variable frequency speed control devices, V-type automatic switching dampers, wind distributors, wind pipes, brackets, and other components. The speed control device is composed of variable frequency speed control systems, gas monitoring systems, LCD displays, and parameter setting systems. It applies advanced IGBT variable frequency speed control technology, heat pipe self-cooling heat dissipation technology, and fuzzy control theory to the speed control device, achieving a high level of automation and advanced technology.
Section 3: Function Overview
The Intelligent Local Ventilation System for Mining is a closed-loop control system. Its primary function is to determine the amount of airflow based on parameters collected from underground sensors and substations, thereby avoiding the "one-blow" phenomenon of existing local ventilation fans and solving the problem of demand-based local ventilation in mines. The system, designed with safety and energy-saving in mind, utilizes a control system composed of PLC and variable-frequency drives to real-time regulate the fan speed, achieving effects of "real-time early warning, dual human-machine control, demand-based ventilation, and disaster prevention and mitigation." This ensures efficient and safe local ventilation in mines, automatic gas discharge, reduces gas accidents, and saves energy and electricity.
1. Demand-based ventilation feature:
Automatically adjusts the fan speed, controlling the output air volume and pressure to prevent gas over-limit, ensuring the fan operates energy-efficiently and economically. When the system detects that the T1, T2 concentration values are below the set upper limit, it automatically enters the speed control mode. Based on the head gas concentration detected by T1, T2 and the return air flow concentration in the tunnel (if below the lower limit of T1, T2 concentration, the fan slows down; if above the upper limit, the fan speeds up), the variable frequency inverter is controlled to automatically adjust the air volume.
2.瓦斯排放 feature
Upon manual or automatic entry into the gas drainage state, the fan speed is automatically controlled based on the gas concentrations detected by the T1, T2, and T3 sensors at the working face, return air flow, and total convergence air flow. When the T3 concentration does not exceed the set value (1.5%), increase speed to enhance air volume. When the T3 concentration exceeds the set value (1.5%), decrease speed to reduce air volume. Adjust the output air volume accordingly to maintain the gas concentration in the return air flow within the safe set value, ensuring high-efficiency safe gas drainage and preventing over-limit gas levels, thereby reducing gas safety accidents.
3. Manual air volume adjustment feature:
The human-machine interface of the frequency converter display panel and the intelligent control switch display panel can set the frequency output of the converter to control the fan speed and adjust the air volume.
4. Gas-Electric Interlock Function
When the main control switch is operational and the data from each gas sensor is below the locking value, the power for the driving face is on and production can proceed normally. At this time, the vacuum contactor of the standby control switch is disconnected, and the standby control switch is in a power-off standby state. When the gas sensor data exceeds the locking value, the main control switch outputs a control signal to control the feeder switch, which then controls the power supply to the driving face's power, thereby implementing the gas lockout function.
The system's auxiliary control switch is in operation, it only facilitates tunnel ventilation and cannot control the power supply to the driving face to achieve gas-electric interlock.
5. Wind Power Interlock Function
When the main control switch fails (the main control switch stops), the main control switch outputs control signals, the power supply switch controls the power cutoff of the driving power for the driving face, and achieves the wind power interlock function.
6. Audio-Visual Alarm Function: To promptly alert on-site personnel in case of abnormal conditions, this system is equipped with an audio-visual alarm device that operates on a 36V AC input. When the PLC detects a gas sensor limit exceeded via a probe, or a variable frequency inverter fault via 485 bus communication, the PLC will trigger an audio-visual alarm, prompting staff to take appropriate actions to address the abnormal situation.
4. Security Assurance:
1. In the event of a main system failure or shutdown, the intelligent local ventilation system's smart control switch enables online switching to start the hot standby fan for air supply, ensuring more reliable air supply.
2. Improve the working environment on the job site. Under normal ventilation conditions, the intelligent local ventilation system automatically adjusts air speed and volume based on the amount of gas emitted from the excavation face, to prevent excessive air volume from causing dust.
3. Rapid gas exhaust with automatic control. In case of power outages, planned ventilation shutdown, or excessive gas outbursts leading to over-limit gas concentrations at the excavation face, the intelligent local ventilation system can automatically exhaust the gas rapidly and safely.
4. The intelligent local exhaust ventilation system can also switch between the main and backup units while operating in the gas exhaust mode, ensuring safety.
5. Prevents "one gust" effect. The fan speed is adjustable, and the air volume can be regulated; the fan's full-pressure start is a soft start, which can avoid the wind tube failure caused by the fan's full-pressure start. As well as power source failure due to current surge.
6. Compatible with intelligent local ventilation and monitoring systems, ensuring system safety and reliability.
V. System Features:
1. The channel-type variable frequency inverter features an explosion-proof housing, with the outer diameter of the explosion-proof housing matching that of the local fan motor. This design meets the heat dissipation requirements of the inverter without compromising the fan's operational performance. The channel-type inverter is integrated with the local fan main unit, with the outer casing designed according to the standardized dimensions of the fan series and is capable of independent assembly and disassembly. 2. The inverter itself is equipped with a local operation box, ensuring convenient operation.
3. The control circuit is separated from the main circuit for better layout, minimizing interference and ensuring greater stability and reliability of the system.
4. Achievable demand-based ventilation;
5. Controlled emissions of gas
6. Dual power supply with automatic dual-fan switching.
7. Power failure memory, lock display, and lock interface;
8. Network with underground sub-stations.
9. Operation Status Control
10. Reliable protection features.