i. background
converter blowing process, the mouth will emit large amounts of brown-red smoke, high temperature flue gas containing combustible gas and metal particles, flue gas must be cooled and cleaned by the induced draft fan to exhaust chimney to diffuse or delivered to gas recovery system in the back. each converter is equipped with a set of dust removal system, dust removal system uses two venturi dust purification, flue diameter φ1.8m, flue gas transfer line 620mm, fan model d900, motor power 630kw / 6kv. since oxygen blowing converter periodically interrupted, to meet the energy and environmental demands to shift the fan runs throughout the work cycle of steel, high-speed operation blowing, low-speed operation is not blowing. the original use of hydraulic coupling speed, high-speed 2700r / min (design 2900r / min), low speed 800r / min. due to the limitations of hydraulic coupling technology, such that:
1. speed range between 30% to 90%, speed instability; moreover, low speed 800r / min is still high, resulting in waste of energy, high-speed operation, the hydraulic coupling are sometimes left turn, the converter mouth smoke;
2. after years of use, the hydraulic coupling has been seriously aging, the need to frequently replace the bearings, causing the converter shutdown, continuous production can not meet the need.
3. the motor is inefficient, loss, especially in low speed, low efficiency;
4. adjust the low accuracy, linearity is poor, slow response;
5. start current is relatively large, the impact of grid stability;
6. hydraulic coupling failure, can not switch to power frequency bypass operation, must downtime;
7. the severe oil spills of environmental pollution;
given the presence of the many problems fluid coupling, its transformation has become a priority.
in order to improve the efficiency of the fan, to solve the many problems caused by the use of hydraulic coupling, steel mills decided to frequency transformation.
second, the drive rehabilitation programs
1. calls drive to have high reliability, long-term trouble-free operation.
2. demands that the drive bypass function in case of failure, the motor can switch to the frequency operation.
3. to a large speed range, the efficiency is higher.
4. with logic control, automatic cycle in accordance with lance lifting speed.
5. resonance point jump settings can cause the motor to run away from the resonance point, so fans do not breathe shock.
after much research, we compare, developed a frequency converter dust removal transformation plan no. 1 fan, rehabilitation programs are as follows:
1, device configuration
km: the inverter power supply voltage vacuum circuit breaker
kg1, kg2, kg3: vacuum contactors
bpq: cshf-800/06 converter
dj: 630kw / 6kv asynchronous motor.
km is the original high-voltage switch, kg1, kg2, kg3.
fan running at high speed, the drive if a serious failure, the motor should be automatically switched to the frequency of power grid operation, after blowing end of the current cycle, automatically disconnect kg3, maintenance inverter, the inverter overhaul is complete, reset button, automatic return to the original state inverter. if the low-speed operation, immediately disconnect kg3, began overhaul. thus, a serious failure in the drive, the system can be automatically transferred to the grid frequency, the load do not stop, can not stop the scene to meet the requirements.
2, the motor and fan parameters
motor parameters: fan parameters:
model: model: d900-13-2
rated power: 630kw intake volume flow: 900m3 / min (mixed gas)
rated voltage: 6kv pressure increases value: 2600mmh2o
rated frequency: 50hz inlet air temperature: 35 ℃
current rating: 64a spindle speed: 2975rpm
rated power factor: 0.89 shaft power: 540kw
rated efficiency: 92.5%
rated speed: 2970rpm
3, dust blower process requirements
1) blowing process cycle
a to b as against scrap iron plus time.
b to c for the fan speed rise time can be adjusted.
c to d is oxygen blowing time.
d point for the fan begins to decelerate.
d to e to pour furnace temperature sampling time.
e to f is tapping time.
f to g to slag splashing time.
blowing the whole process cycle about 23 minutes, in which the high-speed time (c to d) 13 minutes. high speed as 45hz, it can be adjusted; low as 5hz, can be adjusted.
2) the drive and field interface
at point b, providing a pair of closed nodes (nitrogen oxide conversion point) from the field, from the drive to start the high-speed low. at point c, the drive-through speed, close to the site provides a pair of nodes (node high speed) to the next field operatives lance work. at point d, the drive to the scene to provide another pair of closed nodes (fan deceleration point), the inverter begins to slow down, slow down time does not make specific requirements, but during deceleration, if desired speed, the drive should be able to meet the speed requirements.
fan speed, switch node nitrogen oxides, oxygen lance position three nodes satisfy the following relationship:
site provided to drive two pairs of nodes (nox conversion point, fan deceleration point) and drive to the scene of high speed nodes are passive node with 5a / 30vdc or 0.8a / 230vac capacity.
3) drive specifications
rms input voltage three-phase ac 6.3kv ± 10%
input frequency 50 ± 5hz
output voltage three-phase sinusoidal voltage 0-6kv
output frequency 0-50hz
frequency resolution 0.01hz
the acceleration time is set according to process requirements
q according to process requirements set deceleration
two low frequency setting mode speed can be adjusted within the range of 0-50hz
fault diagnosis and testing automatic detection, automatic positioning
net side power factor 0.95 (at high speed)
overload protection 120% l minutes (every 10 minutes), 150% immediate protection
protection class ip20
ambient temperature 0-40 ℃
humidity 90%, non-condensing
altitude 1000 meters
third, the equipment operation
the end of 2006 i ordered a high-voltage converter, model cshf-800/06, january 16, 2007 officially put into use the drive.
1, with the original use fluid strength coupler comparison, hunan branch electric co., ltd. of high-voltage inverter has the following advantages:
stable, safe and reliable. the original use of hydraulic coupling must often replace bearings, each about a half-day shutdown required, enormous economic losses. hunan branch electric co., inverter maintenance-free characteristics, just regular replacement of the filter ventilation on the doors, do not stop to ensure the continuity of production.
2, energy-saving effect is remarkable, greatly reducing the power consumption per ton of steel.
3, the motor to achieve a true soft start, soft outage, the inverter to the motor of sine wave current without harmonic interference, reducing the number of failures of the motor. simultaneously, the drive to set the resonance frequency jumps to avoid the resonance point in the long run the fan, the fan working smoothly, reducing fan bearing wear and prolong the motor and fan life and maintenance cycle and improve the utilization of the fan.
4, frequency changer own protection function, compared with the original protection, more protection, more sensitive, greatly enhanced motor protection. during commissioning the inverter, inverter automatic protection, reported the motor overcurrent. the inspection found that the motor has a broken nose phase, motor phase run, causing overcurrent. we timely overhaul, to avoid accidents expansion.
5, the drive signal with a seamless interface to the scene, to meet production needs. built inverter plc, field signal access and flexible. converter inverter providing a high-speed, low-speed node, according to the drive state of the node automatic high-speed, low-speed running back and forth; the previous instrument cabinet converter gas flow, flue gas temperature signal access the drive, the removal of the meter cabinet , significantly saving space. drive comes with speed measured with the motor connected to the original gun was canceled, provided directly by the drive motor speed for on-site instruction
6, to adapt the grid voltage fluctuation ability.
7, compared with the fluid coupling, during acceleration greatly reduces noise, weakens the noise pollution. because it is not regularly removable bearings, reducing oil pollution of the environment, so that the wind room scene environment has greatly improved.
iv conclusion
from the point of view of the operation a few months, good hunan branch electric co., ltd. of cshf-800/06 high-voltage power converter performance, high reliability, significant energy savings to meet the continuous production of the speed control system requirements.
