1. The present situation investigation and problem analysis
Calcium-magnesia phosphate fertilizer production, the order is: the original fuel for blast furnace raw material storage bin, vibrating feeder feeding weighing hopper, belt conveyor, storage hopper, skip, blast furnace smelting. By analyzing think there are three reasons for the coke loss was likely to be: the creates batching controller and weighing sensor caused by inaccurate measurement; For more, there is no measurement; Measured vibration feeding the residual vibration of no more. Through careful investigation and analysis on the ingredients of the controller and the weighing sensor calibration, ruled out the batching controller and weighing sensor. Because the batching controller has records and the cumulative function, at the same time weighing hopper doumen's not reach the designated position, vibrating feeder is not feed, can rule out the factors of human no more measurement. So the question is after dosing and controller signal weighing the foot and the cumulative, disconnect after feeding mechanical and electrical and mechanical vibration source of aftershocks in feed, and batching controller not cumulative measurement, cause the original fuel consumption increase, inaccurate metering and blast furnace burden. From the above analysis, to ensure the accurate ingredients and measurement, the key lies in the control of vibrating feeder, vibration is to solve more than vibrating feeder feeding problems, namely, vibrating feeder brake problems.
2. Vibration feeding mechanism motion analysis
Ingredients used in blast furnace feeding machine of my company for the GZG503 series since the synchronization of inertial vibrating feeder, using VB W0.3 634 kW vibration motor. The conventional control circuit, there is no any braking measures. If you want to control the residual vibration of vibrating feeder, accurate, stable and reliable to ensure that the motor to stop feeding, only take the brake control. The brake of the asynchronous motor can be divided into: the mechanical braking and electric control. Due to vibrating feeder installation position, the limitation of installation, installation of mechanical brake is not possible, therefore, can only take the electric braking, energy consumption braking or reverse connect braking. By the analysis of braking energy and superior to reverse connect braking. Braking energy has the following characteristics.
(1) small braking current.
Reverse connect braking brake about 10 times greater than the rated current of the motor current and larger for electrical components damage. Energy consumption braking current is only the motor no-load current of 3 ~ 5 times, reduces the electrical components and electrical motor damage.
(2) the impact is small.
Reverse connect braking brake torque is very big, huge impact and vibration. And braking energy can be according to the need of the equipment and production, designed to all kinds of control circuit, implement different ways of soft brake, reduce impact and vibration of mechanical parts.
(3) parking stable and reliable.
Reverse connect braking is to change the power phase sequence, the reverse rotation of the motor stator magnetic field, to achieve the torque of the motor reverse, resulting in a brake. Because the load moment of inertia of the motor and the speed is not a constant, so it is difficult to control, easy to cause the parking is not stable, or forward or reverse. Energy consumption braking parking accurate, stable, easy to control and operation, when the speed of the motor n = 0, braking torque also goes to zero, there will not be reversed or stop the phenomenon.
Strong adaptability.
Reverse connect braking is only applicable to small asynchronous motor and start do not frequent occasions with brake, even if the current limiting resistor in series with the main loop of the brake in, also can only be used under 10 kW. While braking energy is suitable for small power to a relatively high power device, as well as the frequent braking device.
Half wave energy consumption braking and full wave energy consumption braking comparative analysis and improvement.
3. Improve the advantages of half wave energy consumption braking
(1) has the advantages of full wave energy consumption braking ripple component is small, convenient adjustment, stable dc current, accurate and reliable.
(2) use half wave braking energy transformation equipment cost is low. Full-wave braking energy need to configure the four special step-down transformer rectifier diode and; The half wave energy consumption braking with only two rectifier diode, cost is 30% ~ 40% of full wave energy consumption braking.
(3) easy installation, the full wave braking energy use components, take up the space is large; The half wave energy consumption braking due to fewer components, small footprint, easy to install, work cycle is only a few hours.
4. Improve the half wave energy consumption braking in the application of vibrating feeder
(1) after vibrating feeder used half wave energy consumption braking, to ensure the accurate and blast furnace feeding. The use of more than 1 year show that stable and reliable, low failure rate, maintenance is convenient.
(2) benefit comparison After the improvement, 2003 average actual blast furnace coke consumption is lower than statements average coke consumption 1 kg/t, than before improvement reduces the 6 kg/t, such as 2 sets total annual capacity of 200000 t calcium-magnesia phosphate fertilizer semi-finished products according to the calculation of blast furnace can save coke 1 200 t every year. Coke prices calculated at 600 yuan per ton, can reduce the cost of 720000 yuan, have achieved good economic benefits.
