How to make vibrating feeder accurate feeding
1. Survey of the current situation and problem analysis
Calcium magnesium phosphate fertilizer production, blast furnace raw fuel feeding sequence is: raw material storage bin - vibrating feeder feeding weighing hopper - belt conveyor - storage hopper - material car - blast furnace smelting. Through the analysis of the coke loss may be caused by 3 reasons: ¹ batching controller and weighing sensor caused by inaccurate measurement; artificially added more, no measurement; vibration feeder after vibration more than added no measurement. Through careful investigation and analysis and calibration of dosage controller and weighing sensor, the problem of dosage controller and weighing sensor is excluded. As the dosage controller has the record and accumulation function, at the same time, the weighing hopper door is not closed in place, the vibration feeder does not feed, can exclude the human plus no measurement factors. Then the problem is that the dosage controller issued a weighing signal and accumulated measurement, after disconnecting the vibration feeder motor power after the residual vibration led to more material, and the dosage controller did not accumulate measurement, resulting in increased consumption of raw fuel, blast furnace measurement and batching inaccurate. From the above analysis, to ensure accurate batching and metering, the key lies in the control of the vibrating feeder, is to solve the problem of after-vibration feeding vibrating feeder, that is, the braking problem of vibrating feeder.
2. Vibrating feeder brake analysis
My company blast furnace batching feeder model GZG503 series self-synchronous inertia vibrating feeder, the motor using VB 634 W0.3 kW vibrating motor. The most conventional control circuit, without any braking measures. To control the residual vibration of the vibrating feeder and to ensure that the motor stops feeding accurately, stably and reliably, only braking control can be adopted. Asynchronous motor braking is divided into: mechanical braking and electrical control. Due to the vibrating feeder installation location, installation restrictions, the installation of mechanical braking is not feasible, therefore, can only take the electric brake, that is, the energy brake or reverse connection brake. After analysis, energy braking and better than the reverse braking. Energy braking has the following characteristics.
(1) Braking current is small.
The braking current of reverse connection is more than 10 times of the rated current of the motor, and the damage to electrical components is greater. The energy consumption braking current is only 3-5 times of the no-load current of the motor, which reduces the electrical damage to the electrical components and motor.
(2) The impact force is small.
Reverse braking torque is very large, the impact force is large, vibration is large. And energy braking can be designed according to the needs of equipment and production, into a variety of control lines, to achieve different ways of soft braking, reducing the impact on mechanical components and vibration.
(3) Stopping smoothly and reliably.
Inverted braking is to change the phase sequence of the power supply to reverse the rotating magnetic field of the motor stator, so as to reverse the torque of the motor and produce braking. Because the load inertia and speed of the motor is not a fixed number, so it is difficult to control, easy to cause unstable parking, or positive or reverse phenomenon. When the speed of the motor n=0, the braking torque also becomes zero, so there is no reversing or stopping.
(4) Strong adaptability.
The reverse braking is only suitable for small asynchronous motor and the occasion of infrequent starting and braking, even if the main circuit of braking in series with current limiting resistor, it can only be used in the following 10 kW. The energy brake is suitable for small to large power equipment, as well as frequent braking equipment.
Half-wave energy braking and full-wave energy braking comparison analysis and improvement
3. Improve the advantages of the half-wave energy brake
(1) has the advantages of full-wave energy braking, pulsation component is small, DC current adjustment is convenient, smooth, accurate and reliable braking.
(2) The use of half-wave energy brake transformation equipment costs are low. Full-wave energy braking requires the configuration of four rectifier diodes and special step-down transformer; and half-wave energy braking with only two rectifier diodes, the cost of full-wave energy braking 30% to 40%.
(3) easy to install, full-wave energy brake using more components, occupy a lot of space; while the half-wave energy brake due to less components, occupy less space, easy to install, the transformation work cycle is only a few hours.
4. improve the half-wave energy brake in the application of vibrating feeder effect
(1) After the application of half-wave energy brake in vibratory feeder, ensure the accurate feeding of blast furnace. 1 year of use shows that the brake is smooth and reliable, low failure rate, easy maintenance.
(2) Benefit comparison After improvement, the actual average coke consumption of blast furnace in 2003 is 1 kg/t lower than the reported average coke consumption, which is 6 kg/t lower than before improvement, if the total annual output of calcium-magnesium-phosphorus fertilizer semi-finished products of 2 blast furnaces is calculated at 200,000 t, it can save 1,200 t of coke per year.
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