Application of the hottest high voltage inverter i

Application of high-voltage inverter in 4 # dust removal fan

1. Introduction

there are three original 15t oxygen top blowing converters in Sansteel steelmaking plant, which adopt the "three blowing and three" method. During the converter blowing process, a large amount of brownish red flue gas will be discharged from the furnace mouth, and the flue gas temperature is high, containing flammable gas and metal particles, According to the emission standard of air pollutants synthesis 3) distortion effect: the center of gravity of the support point of the bending specimen is not on the same 1z plane (GB16297-1996) issued by China in 1996, the flue gas must be cooled and purified, and then discharged to the chimney by the induced draft fan or transported to the gas recovery system for standby. Therefore, each converter needs to be equipped with a set of dust removal system, which adopts the two-stage venturi flue dust purification method, and the flue diameter Φ 1.7m, flue gas transmission pipeline 820mm, fan model ai850, motor power 630kw/6kv. Due to the periodic intermittent oxygen blowing of the converter, in order to meet the requirements of energy conservation and environmental protection, the fan is required to operate at a variable speed during the whole steelmaking working cycle, with high speed when blowing oxygen and low speed when not blowing oxygen. At the beginning of 2000, the steel plant expanded the capacity of three converters, moved the fans to the ground, and adjusted the speed with hydraulic coupling, with high speed of 2700r/min (designed to be 2900r/min) and low speed of 1200R/min. After a period of operation, it is found that the hydraulic coupling technology has limitations, which are mainly manifested in:

1, the speed range is between 30% and 90%, and the speed is unstable; Moreover, the low speed of 1200r/min is still high, resulting in a waste of energy. When running at high speed, the hydraulic coupling sometimes stalls and the converter mouth smokes

2. The bearing of the hydraulic coupling needs to be replaced frequently, resulting in the shutdown of the converter, which cannot meet the needs of continuous production

3. The efficiency of the motor is low and the loss is large, especially at low speed

4, low adjustment accuracy, poor linearity and slow response

5. The starting current is still relatively large, affecting the electrical stability

6. When the hydraulic coupling fails, it cannot be switched to the power frequency bypass operation, and it must be shut down for maintenance

7. Serious oil leakage, great environmental pollution, and serious oil erosion on the ground

in view of the above-mentioned problems of the hydraulic coupling, in 2001, when the steel-making company built a new 30t converter, it decided not to use the hydraulic coupling for speed regulation, but to use the high-voltage frequency converter for the new converter fan for speed regulation

2. Technical requirements and transformation scheme of high voltage inverter

dust removal basically eliminates the old brand experimental machine manufacturers. The fan is the power center of the dust removal and purification system. Once the dust removal fan fails to operate normally, it will not only affect production, cause huge economic losses, but also threaten the personal safety of on-site production personnel; In addition, the working environment of the speed regulation system is relatively bad; At the same time, the converter blows oxygen periodically and intermittently; Therefore, high-voltage speed regulation system supporting dust removal fan is required to be highly reliable. Based on the above working characteristics, the main requirements for the variable frequency speed regulation system are as follows:

1. The frequency converter is required to have high reliability and long-term operation without fault

2. The frequency converter is required to have a bypass function. In case of failure, the motor can be switched to power frequency operation

3. The speed regulation range should be large and the efficiency should be high

4. It has logic control ability and can automatically increase and decrease the speed according to the oxygen blowing cycle

5. There is a resonance point jump setting, which can make the motor run away from the resonance point and prevent the fan from panting

after investigation and comparison in many ways, it was finally decided to adopt the high-voltage inverter produced by Beijing Lide Huafu Electric Technology Co., Ltd. through the cooperation of technicians from both sides, the frequency conversion transformation scheme of 4 # converter dust removal fan was jointly formulated. The transformation scheme is as follows:

2.1 equipment configuration

km: high-voltage vacuum circuit breakers powered by the inverter

kg1, kg2, kG3: vacuum contactors inside the high-voltage inverter, The manufacturer provides

bpq:harsvert-a06/076 frequency converter

dj:630kw/6kv asynchronous motor

km is the original high-voltage vacuum switch

dj retains the original asynchronous motor

it is required that it can be controlled remotely and locally. When the fan is running at high speed, if the frequency converter has serious failure, the frequency converter will stop automatically. During remote control, switch the motor to power frequency operation through the power frequency/frequency conversion knob on the console. When the blowing cycle is over, overhaul the frequency converter. After the maintenance of the frequency converter, turn the power frequency/frequency conversion knob on the operation console to the frequency conversion position to return to the frequency conversion speed regulation state. When the machine is controlled, switch the motor to power frequency operation through the power frequency/frequency conversion knob of the frequency converter control cabinet. When the blowing cycle is over, overhaul the frequency converter. After the maintenance of the frequency converter, turn the frequency/frequency conversion knob of the frequency converter to the frequency conversion position to return to the frequency conversion speed regulation state

2.2 motor and fan parameters

1) motor parameters: 2) fan parameters:

model: Y model: ai850

rated power: 630kw intake volume flow: 850m3/min (mixed gas)

rated voltage: 6kV pressure added value: 2600mmh2o

rated frequency: 50Hz intake air temperature: 35 ℃

rated current: 73a spindle speed: 2975rpm

rated efficiency: 92.5% rated power factor: 0.89

rated speed: 2970rpm shaft power: 500kW

2.3 dust removal fan process requirements

1) converting process cycle

a to B are The time of adding scrap steel to iron mixing is about 1 minute

b to C are the fan speed-up time, tentatively 1 minute, which can be adjusted

c to D is the oxygen blowing time, about 14 minutes

d point fan starts to decelerate, tentatively for 3 minutes, which can be adjusted

d to e are the sampling time for temperature measurement of furnace inversion, about 2 minutes

e to f is the tapping time, about 2 minutes

f to G is the slag splashing time, about 3 minutes

the whole blowing process cycle is about 26 minutes, of which the high-speed time (C to d) is 12 minutes. The high speed is set at 45Hz, which can be adjusted; The low speed is set as 20Hz, which can