I. System overview The new generation of intelligent, energy-saving local fans for mines was developed based on the current status of domestic mine ventilation and based on a large number of deep underground coal mine investigations to reduce gas accidents. With the goal of "safety and reliability, energy saving and environmental protection", and the characteristics of "module unit, personality combination, real-time monitoring, and intelligent control", the effect of "real-time warning, dual control of man-machine, wind supply on demand, disaster prevention and mitigation" is achieved It fills the blank in the field of intelligent control of local ventilation in mines in China and reaches the domestic leading level.
System composition: The system consists of FBD series flameproof press-type axial flow local fan fans
, flameproof and intrinsically safe variable frequency speed control devices, V-type automatic switching dampers, air dividers, air ducts, brackets and other units. composition. The speed control device is composed of a frequency conversion speed control system, a gas monitoring system, an LCD display and a parameter setting system. It applies advanced IGBT frequency conversion speed control and heat pipe self-cooling and heat dissipation technology and fuzzy control theory to the speed control device. , High degree of automation, leading technology III. Function overview The mine intelligent local ventilation system is a closed-loop control system. Its main function is to determine the amount of air supply through the parameters collected by downhole sensors and underground substations, avoiding existing local ventilation. The phenomenon of "one wind blowing" by the machine to supply wind, thereby solving the problem of on-demand air supply for local ventilation in the mine. Starting from the requirements of safety and energy saving, the system adopts a control system composed of PLC and inverter to control the fan speed in real time to achieve the effect of "real-time warning, dual control of man-machine, on-demand air supply, disaster prevention and mitigation", so that the mine Local ventilation and automatic gas emission are efficient and safe, reduce gas accidents, and save energy and electricity.
1. The on-demand ventilation function automatically adjusts the speed of the local fan, adjusts the output air volume and air pressure, and prevents the gas from exceeding the limit to enable the local fan to operate economically and economically. When the system detects that the concentration of T1 and T2 is lower than the upper limit of the set value, it automatically enters the speed regulation state. The head gas concentration detected by T1 and T2 and the gas concentration in the return air flow of the tunnel (below the lower limit of T1 and T2 concentration, the local fan will decelerate; if the concentration of T1 and T2 is higher than the upper limit, the local fan will rise. ) Control the inverter to automatically adjust the air volume.
2. After the gas emission function enters the gas exhaustion state manually or automatically, the speed of the local fan is automatically controlled according to the gas concentration detected by the T1, T2, and T3 sensors on the working surface, working surface return air flow, and total combined air flow. When the concentration of T3 does not exceed the set value (1.5%), the speed increases and the air volume is increased. When the concentration of T3 exceeds the set value (1.5%), the speed is reduced to reduce the air volume. According to this principle, the output air volume is adjusted to control the exhaust air flow. The gas concentration is within the range of the safety setting value, that is, the gas is safely discharged with the maximum efficiency, which can avoid gas overrun and reduce gas safety accidents.
3. The function of adjusting the air volume manually can set the output frequency of the inverter through the man-machine interface of the inverter display panel and the display panel of the intelligent control switch to control the speed of the local fan to adjust the air volume.
4. When the main control switch of the gas electric blocking function system is working and the data of each gas sensor is lower than the blocking value, the driving face has power and can produce normally. At this time, the vacuum contactor of the standby control switch is turned off, and the standby control switch is in a power-off standby state. When the data of the gas sensor is higher than the blocking value, the main control switch output control signal of the system controls the feed switch, and the feed switch controls the power supply of the tunneling face to cut off the power to realize the gas blocking function. When the system's standby control switch is in working state, it only realizes the roadway ventilation, and cannot control the power supply of the tunneling working face to achieve gas lockout.
5. Wind power lockout function When the main control switch of the system is turned off and the main control switch is off, the main control switch of the system outputs a control signal, and the feed switch controls the power supply of the tunneling face to cut off power to achieve the wind power lockout function.
6. Sound and light alarm function In order to promptly remind the staff working in the field under abnormal conditions, this system can be equipped with a sound and light alarm device, which uses 36V AC input. When the PLC detects that the gas sensor exceeds the limit through the probe, or finds the inverter fault through the 485 bus communication, the PLC will issue an audible and visual alarm to prompt the staff to take corresponding measures to solve the abnormal situation.
Fourth, the system working process
1. Power on the main system startup system → Close the intelligent control switch joystick → Press the start button of the intelligent control switch → The vacuum contactor closes → The inverter is powered on and initialization is started. After a delay, the inverter powers the fan. The output frequency is gradually increased from the start setting value (1.5Hz) to achieve soft start.
In the system, T1 to T4 are four gas concentration sensors, F1 is a wind speed sensor, and W1 is a temperature sensor, as shown in Figure 2:
Figure 2 Upper computer of intelligent local ventilation system in mine
T1 is the gas concentration sensor on the working surface, T2 is the gas concentration sensor of the return air flow, and T1 and T2 are used as the basis for controlling the air volume in the normal ventilation state; T3 is the gas concentration sensor in the return airway. Only data is collected during the automatic ventilation state, not used The control basis is used as the basis for controlling the air volume when exhausting gas; T4 is the gas concentration sensor at the air inlet of the fan.
2. Initial running state The system is powered on initially and the output frequency is set to 20Hz (it can also be set to 30Hz);
3. Normal ventilation state When the gas concentration sensors T1 and T2 of the working face exceed the upper limit of the set value (0.7%), the inverter will increase the frequency step by step, and the fan will automatically increase the air volume. When the gas concentration sensors T1 and T2 of the working face are lower than When the lower limit of the set value (0.5%) is set, the inverter will reduce the frequency and the air volume of the fan will decrease automatically. When the gas concentration sensor T1 or T2 in the heading working face exceeds the alarm set value (1.0%), it will alarm, and the system will enter the diluted gas state. When the gas concentration sensor T1 or T2 of the working face exceeds the power-off setting value (1.5%), the non-intrinsically safe power supply on the working face is automatically cut off, and the system enters the gas discharge state. The values in parentheses are factory set values and can be changed according to the user's specific conditions.
4. Exhaust gas state When the system enters exhaust gas state, the fan operation is automatically controlled by the gas concentration sensor T3. When the gas concentration sensor T3 exceeds the set upper limit (1.5%), the inverter will reduce the frequency and reduce the fan's air volume to make T3 Within the set upper limit range (1.5%); when the gas concentration sensor T3 is lower than the set lower limit (1.0%), the frequency converter increases the frequency, increases the fan air volume, and efficiently emits gas. When the gas concentration sensor T3 exceeds the alarm set value (1.5%), it will alarm. When the gas concentration in the working face drops to a set safe concentration (<1.0%) and remains below the safe concentration, the working face can be re-energized. The values in parentheses are factory set values, which can be changed according to the user's specific conditions
T4 is the gas concentration sensor at the inlet of the fan. When the concentration of T4 is ≥0.5%, the fan will automatically stop working according to the "Safety Regulations for Coal Mine", and the tunneling face will be treated as power cut off and power off.
5. Automatic switching between main fan and standby fan When the main fan intelligent control switch stop button is pressed (or the main fan fails) → the main fan intelligent control switch vacuum contactor is powered off → the inverter of the main fan loses power (the main fan stops working) → The PLC of the main fan intelligent control switch issues a fault signal → The PLC of the standby fan intelligent control switch receives a fault signal → The standby intelligent control switch closes the vacuum contactor → The standby fan inverter is powered → the standby fan starts to run. The connection line between the main and standby intelligent control switches is not powered under normal operating conditions, and is only powered for a short time during the mutual switching process of the fans (our company's dual-fan dual-power patented technology), making it safer to use.
Figure 3 Block diagram of intelligent local ventilation system in the mine 6. Parameter settings of the system In order to adapt to the actual conditions of various mines, the alarm, lockout, and regenerative values of T1, T2, and T3 can be set by the user. To set these parameters under actual conditions, the setting of these values is limited to the range specified in the "Coal Mine Safety Regulations".
V. Security Guarantee
1. When the main system fails or stops, the intelligent control switch of the intelligent local ventilation system realizes online switching to start the hot standby fan for air supply, and the air supply is more reliable. 2. Improve the working environment at the job site. Under normal ventilation conditions, the intelligent local ventilation system automatically controls the wind speed and adjusts the air volume according to the amount of gas emitted from the driving face to avoid excessive dust and dust. 3. Maximum efficiency of self-controlled emission of gas. When accidental power outages or planned wind outages or large gas outflows cause gas to exceed the heading face, the intelligent local ventilation system can automatically and safely emit gas at the fastest speed. 4. When the intelligent local ventilation system works in the state of exhausting gas, it can also realize the main and backup switching to ensure safety. 5, can prevent "one wind". The fan speed can be controlled and the air volume can be adjusted; the full pressure start of the fan is soft start, which can avoid the failure of the fan caused by the full pressure start of the fan. And power failures caused by current surges. 6. The intelligent local ventilation system is compatible with the monitoring system, and the system is safe and reliable.
1. The runner-type inverter adopts a flame-proof casing. The outer diameter of the flame-proof casing is the same as the outer diameter of the local fan motor. It meets the heat dissipation requirements of the inverter without affecting the performance of the fan. It is integrated with the main body of the local fan, and the outer tube is designed according to the series size of the local fan, and can be independently installed and removed; 2. The main body of the flow channel inverter is provided with a local operation box, which is convenient to operate; Avoid interference, the system is more stable and reliable; 4. On-demand ventilation can be achieved; 5. Controllable emission of gas; 6. Dual power and dual fans automatically switch; 7. Power failure memory, lock display, lock interface; 8. Distribute with the underground Station networking; 9. Operation status control; 10. Reliable protection function.
1. Altitude ≤1000m. When it is greater than 1000m, derating and selection; 2. Temperature: -5 ℃ ～ + 40 ℃; 3. Annual average relative humidity of surrounding air: 95% ～ 98% (at 25 ℃) 4. Applicable to mines with explosive mixtures of methane and other gases with air; 5. Inclination of installation to the horizontal plane ≤ 15 degrees; 6. In places without significant shaking and severe shock vibration; 7. In the prevention Place of dripping water; 8. Installation category: Class III; 9. Pollution degree: Class III