★ Electric arc furnace and electrode lifting automatic control system
Electric is used as heat energy during electric arc furnace steelmaking, it use high temperature of the electric arc emerges from the electrode and charge to heat and smelt charge.
Electric arc furnace can be used to produce straight carbon steel, fine carbon steel, various alloy steel , alloy iron and stainless steel ,etc, covering a wide application, which is necessary to equip in steel factories, casting factories, refractory factories.
Industry control computers together with fuzzy Control Technology is adopted to adjust the electrode lifting, provided with advantage of high control precision, fast reaction speed, low failure rate, high reliability, capable of realize the effect of fast arc striking, steady arc steam, high power factor, saving electric, reducing electrode fracture and extending furnace campaign.
Virtues:
◇ It can control the temperature flexibly.
The melting temperature can be managed flexibly by controlling the current and voltage in the course of smelting to meet the smelting requirements of different material.
◇ High thermal efficiency
◇ The atmosphere inside the furnace can be controlled.
Phosphorus, sulphur,oxygen and other mpurities can be eliminated mostly during the course of alkaline electric arc furnace smelting in order to guarantee the high quality of the steel , the high and steady recovery rate, easy-controlled chemical composition and various types of steel smelted.
◇ Easy-operated equipment, concise technical flow
◇ New technique
◇ Perfect design of electric arc furnace parameter choice
◇ Pipe-type water cool furnace wall and cover
◇ Eccentric bottom tapping
◇ Copper-steel complex conductivity cross arm
◇ Cluster wide section water cool cable
◇ optimize structure short net (energy saving type)
◇ Proportioner hydraulic system or steel wire hoisting System
◇ PLC basic level+ procedure level Industry Distribution System (IDS)
◇ Frequency Converter Control Technique, internet technique, nerve center control technique
electrode lifting automatic control system applies to several types of electric arc furnace below:
◎ Steelmaking electric arc furnace
◎ Steelmaking refining furnace
◎ Iron alloy electric arc furnace (ore smelting electric arc furnace)
◎ Automatic adjuster for AC electric arc furnace frequency conversion type electrode
◎ Automatic adjuster for AC electric arc furnace frequency conversion type electrode
Is controlled by PLC, applied to electrode lifting automatic control system of 0.5t-30t steelmaking electric arc furnace and iron alloy electric arc furnace.
Main technique standards for frequency conversion type electrode automatic adjuster.
Electric furnace capacity (T)0.5 1.5 3 Standard 5-10 to be extended 10—standard 15 to be extended 15--- standard 30
Frequency converter capacity arrangement (kw) 2.2 3.7 5.5 5.5 7.5 11
Top speed of electrode lifting(m/min) 2.5 3 4 4 – 4.5 4.5—5 5.5---6
inert zone(2△I%) each smelting stage±5%, to adjust and adapt to the sensibility automatically
Adjusting range of electric arc and electric current 15－150%IH (transformer rated current)
Electrode response time (s) lifting start<=0.15, lifting brake <=0.1
Properties and advantages of frequency conversion type electrode automatic adjuster
A. The imported frequency converter is selected to make the frequency conversion adjuster, with the frequency conversion and Speed Adjustment Technology of many advantages compared with the previous SCR AC variable voltage control technique , can get rid of the problems resulting from low voltage overloading and faulty circuit arose by separation element resulting in burning motors. Meanwhile, it can guarantee the user to get satisfactory economic efficiency , save smelting consumption of 5%-8%, reduce electrode consumption of 0.5-1.0KG/T, enhance furnace line of around 10%, shorten smelting time of 10-15MIN/furnace.
The unique self-cooled type MSMD act as the Motor executive motors, with capacity from 1.1kw to 7.5kw, applied to electromechanical electric arc furnace of 30 ton and below capacity.
The motors studied and designed by us needn’t air transferring and water transferring, and have action of self-cooled, big starting torque, small starting current, fast response speed, and are capable of executing the instructions from the frequency conversion adjuster exactly.
The self-cooled motors are assortative to the gears and worm reduction gears developed by us in compact arrangement, adapted to various kinds of needed disposal at the smelting site with convenient maintenance requirement.
The sensitivity selector switch is canceled to avoid all the problems induced by sensitivity manual selection. It is designed to effect sensitive and insensitive area self-adapted control and dispel the movement of the electrode by optimize control theory design of electric circuit, at the same time, reduce mechanical shock and abrasion greatly to extend the using life and prevent the screws of electrode tie-in from loosing.
There are various kinds of protection in electric circuit design, which can prevent electric furnace with rack driving from braking the electrode and damage the machinery because the charging don’t conduct electric.
steady current is adopted for power supply.
It reduce heat producing losses of the transformer and the circuit, keep electric arc steady, make the liquid steel heating-up rapidly.
The equipments are of widely universal usage. They are suitable for both rack driving and steel wire driving.
All the above four schemes are of four phases control, three phases among which are for main working , and one phase left as accessory. In such a design, it can meet with the requirement of the electric arc furnace reliability.
