Main process parameters of energy-saving mainstream 2.5-ton energy-saving intermediate frequency furnace

1. Overview of 2.5-ton energy-saving intermediate frequency furnace :

2.5 tons IF furnace saving system for the production of cast steel, cast iron, is not less than that required by the set of auxiliary equipment 2000KW dual frequency power supply and two steel 2.5t coreless induction melting furnace and system uptime composition.

A series resonant dual output power supply with two electric furnaces can work at the same time (commonly known as energy saving ), that is, the output power can be randomly distributed between the two furnace bodies, and the two furnace bodies can be simultaneously powered, one insulation, one Smelting.

The power cabinet and the furnace body use separate closed circuit circulating water systems, including closed circuit cooling towers, heat exchangers and the like. The rectifier transformer adopts a high-voltage electric drop to the input voltage suitable for the intermediate frequency power supply. The primary voltage is 10KV, the second is DY11, and the d0 wiring is 12-pulse rectification.

The 2.5-ton energy-saving intermediate frequency furnace mainly includes 1 set of incoming high-voltage cabinets (optional), 1 set of rectifier transformers (optional), 1 set of medium-frequency power supply not less than 2000kW , 2 sets of inverters not less than 2000kW, and 2 sets of 2.5t furnaces. , 1 set of cooling water system (optional) , 1 set of automatic control system (optional), etc. skills requirement

Second, 2.5-ton energy-saving medium frequency furnace intermediate frequency furnace working mode :

1. One set of furnace body smelting production, another set of furnace body spare

2. One set of furnace body is smelted and the other set of furnace body is insulated at the same time.

3, two sets of furnace body production at the same time

Third, the main process parameters of 2.5 tons of energy-saving intermediate frequency furnace :

Main process parameters of 2.5-ton energy-saving intermediate frequency furnace intermediate frequency furnace

Main technical parameters and uses of auxiliary media:

Fourth, energy 2.5 tons IF furnace IF furnace apparatus main technical features described

1, 2.5 tons energy-saving medium frequency furnace power cabinet: (1 set)

The series resonant dual output IF power supply is housed in a closed cabinet. The incoming power supply is 660V-950V, 3-phase 6-way (12-pulse), 50HZ.

An isolating switch is provided between the rectification and the inverter. In the case of a side inverter failure, isolate the fault and continue to use the power supply on the other side to continue working.

Install the grounding switch at the appropriate position on the copper bus output. When the furnace part is to be repaired, the copper bars and coils of one side of the furnace body can be short-circuited to the ground to ensure the personal safety of the operator. At the same time, it does not affect the normal operation of the electric furnace on the other side.

The power cabinet is equipped with a melting manager (optional) . The PLC and man-machine interface consist of a convenient operation smelting manager, including: automatic oven, furnace start, fault diagnosis, fault information display and storage, operation information display, system status display, etc.

2, cabinet

Cabinet body is made of cold rolled steel sheet is not less than 1.5 mm thick high strength. Opening the door makes it easy to access parts such as rectification and inverter. All doors are equipped with a safety switch (optional) . If the door is not closed, the power supply will not start. There are hooks on the top of the power cabinet for easy transportation and installation.

The components of the power cabinet are reasonably arranged, easy to maintain, and the wiring and wiring are in compliance with the specifications. It is convenient for maintenance personnel to easily access all maintenance points.

The copper bars are all properly cooled as needed.

3. Isolation control room

A closed isolation control room is arranged at the upper part of the front door, and control components such as a main control board, a feedback board, and a control power supply are provided, so that the signal of the main control board can be conveniently observed.

The isolation control room does not require additional cooling.

4, the power receiving part

The secondary side of the circuit breaker receiving rectifier transformer is powered by a busway or a copper bus. The circuit breaker is a drawer type or a fixed type with a visible disconnect point. It is installed on the front side of the cabinet as a disconnector and visible disconnection of the power incoming line. point. They are equipped with a manual switch and an undervoltage coil for interlock protection. It consists of a circuit breaker, a voltage transformer, a current transformer, and the like.

5, the rectification part

Voltage feedback series type; the circuit adopts 12-pulse circuit rectification mode, the incoming line voltage adopts 660v-950V, and the rectifier part of the thyristor adopts the latest stacked heat sink assembly.

The RC absorption branch at both ends of the thyristor can act as a buffer current sudden change when the thyristor switch is used.

Each thyristor heat sink has a pressure indicating device.

6, filter network

Reactor, leveling DC current, removing current ripple and preventing high frequency signals from entering the factory power supply line.

Filter capacitor. Filter capacitor is water cooled

The filter capacitor has an external discharge resistor that can be discharged within 5 minutes after the power is turned off.

The reactor is air-core, water-cooled, vacuum-cast with epoxy resin, solid-sealed, and protected by a temperature switch. When the temperature is too high, the power is turned off.

6, the inverter part

The inverter circuit has two sets of series resonant inverter bridges, and the output power can be randomly and arbitrarily distributed between two series resonant inverter bridges.

The RC absorption circuit is connected in parallel across the thyristor to buffer the thyristor switch.

One power supply with two furnaces work at the same time, the power is distributed arbitrarily, one smelting one heat preservation, when it is needed for uninterrupted smelting, heat preservation, temperature rise, quenching and tempering at an accurate temperature, and maximally increase the amount of steel output.

Constant power output, power output is controlled by constant. During the melting process, when the load and temperature change, the load is always full power output, thus shortening the melting time.

Increase the power factor to ensure that the power factor is not less than 95% at any power.

The two furnaces share a transformer, and in any case the transformer reaches full capacity, reducing the capacity of the transformer.

The starting characteristics are good, and it can be started freely under full load and heavy load conditions, and the starting success rate is 100%.

7, inverter capacitor group

Two sets of series resonant capacitor compensation devices to meet the dual output, can simultaneously send power to the two furnaces. Capacitance capacitor mounted on the closed cabinet, the cabinetbody is made of cold-rolled steel sheet is not less than 1.5 mm thick high strength.

8, power conversion function

Power conversion between the two furnace bodies is achieved by rotating the power conversion potentiometer on the panel. A furnace body is melted to melt the other furnace body. It can also be smelted in a furnace. The other furnace was shut down.

9, the control system

It is equipped with output voltage meter, output power meter, working frequency meter, input current meter, input voltmeter, DC voltmeter, DC current meter, phase display on the control panel, and inverter working display. The two furnaces can display the intermediate frequency voltage, power and operating frequency respectively to monitor and control the operating conditions of the two electric furnaces.

The circuit board contains all the necessary control and electronic logic components to respond instantaneously to the voltage, current and power of each induction coil and to generate thyristor trigger pulses.

The circuit board sets limits on the inverter to avoid damaging the thyristors and capacitors in the event of current or overvoltage.

The circuit board ensures system reliability; and the system is fully monitored for each half cycle of the furnace current.

Press the button to control the “Run” and “Disconnect” of the inverter.

Main power indicator, this indicator lights when the circuit breaker is closed to power the variable frequency power supply.

10. Complete monitoring and operation monitoring system.

A current limiting reactor is required to delay the rising speed of abnormal current

A fuse is required to provide short circuit protection.

A disconnect switch is required to isolate each inverter from the rectification side for easy maintenance and safety protection (optional).

For the inverter, the operating temperature of the filter capacitor is monitored by a temperature switch meter. Once the temperature of the cooling water exceeds the set value or a waterway fault occurs, an alarm is issued and the power is turned off.

Ground/leak detector alarm (optional)

11, 2.5 tons of energy-saving medium frequency furnace body (2 sets):

The furnace body is composed of a furnace shell, a fixed frame, a tilting furnace mechanism, an induction coil, a yoke, and the like, and is additionally provided with a furnace lining material and a leaking furnace alarm device.

12, furnace shell:

The medium frequency melting furnace shell is a squirrel-cage frame structure welded by steel plate, and the lower part of the furnace shell has a fixing bracket of the furnace lining mechanism. A contour yoke is provided in the furnace shell. The yoke shielding can reduce the leakage magnetic flux to prevent the furnace body from heating, improve the electric energy efficiency, support the induction coil at the same time, improve the strength, and can conveniently disassemble the coil and repair, observe and dissipate the coil when the yoke is not taken away.

13, the fixed frame:

The fixed hob adopts high-strength integral steel structural parts to ensure long-term work without deformation. The furnace platform is made of 10mm pattern steel plate, which can be kept flat and not deformed during long-term use, and the noise on the working platform of the furnace is <85dB.

14, tilting mechanism (hydraulic plunger cylinder)

The tilting furnace adopts two inverted plunger hydraulic cylinders, and the hydraulic cylinder inlet port is directly connected to the speed limit shut-off valve (flow control valve) to prevent the furnace body from falling sharply due to the rupture of the pipeline and the like, causing an accident. Manual speed control reversing valve control.

The two oil cylinders are connected in parallel, and there is no jamming at the same time. The furnace body rises and falls smoothly when the furnace is tilted. A high temperature resistant protective sleeve is required on the outside of the cylinder.

15, induction coil (ie sensor)

The induction coil is made of TU1 type (purity of 99.97% electrolytic copper), wall thickness / 6mm extruded rectangular copper tube on a special mold, the pitch error is not more than 2mm, and the coil group needs to be relieved after welding. deal with.

The induction coil is made of high temperature resistant, high pressure insulation paint, which is dip coated and vacuum dried. The insulation grade is H grade. The induction coil passed the 12kg/cm3 water pressure withstand test before leaving the factory.

A stainless steel water-cooling ring is arranged on the upper and lower parts of the induction coil to ensure uniform heating of the furnace lining. A Faraday short-circuit ring is required at the upper and lower ends of the coil to fully absorb the leakage flux at the upper and lower ends to prevent the furnace body from heating up. The furnace body is connected to a large-section water-cooled cable, and the lead-out line is in the form of a side lead-out line. The coil pressing device is pulled down on the stainless steel rod.

16, yoke

The yoke is laminated with Z11 high-quality crystal oriented cold-rolled silicon steel sheet, and its thickness is ≤0.3mm, which is clamped on both sides with stainless steel. The yoke has a contoured arc-shaped structure that is consistent with the outer diameter of the coil. After assembly, the bending degree is ≤ 4mm, and the deviation between the theoretical center line and the actual center line is ≤ 3mm. The yoke covers the area of the induction coil ≥60%. The yoke fixing method: the yoke is closely attached to the induction coil, and a high-voltage insulating layer is used in the middle, and the outer surface is screwed on the stainless steel plate on the back of the yoke.

The inside of the yoke stainless steel clamping plate needs a water-cooled radiator. When the electric furnace is in operation, the yoke temperature is kept at normal temperature to prevent the yoke temperature from rising and deformation, thereby strengthening the support of the induction coil and improving the strength of the furnace.

17. Furnace lining and bottom

A 12 to 25 mm permanent lining (refractory clay coating) is applied to the inside of the inductor, and the lining material is then kneaded inside the cement.

The bottom structure satisfies the requirement of removing the lining by using the lining pushing mechanism.

18, leaking furnace alarm device

It is necessary to set the lining thickness detecting device: when the lining thickness detecting device is working normally, the work indicator lights up and the warning light goes out. When the furnace lining has a low resistance phenomenon or the induction coil has a short circuit to the ground, the alarm lamp lights up and the buzzer sounds an alarm.

The detection device has a self-test button and a reset button. When the device is normal, the self-test button is pressed, the alarm lamp is lit, and the buzzer alarms. Press the reset button to cancel the alarm and resume the detection device to work again. The button below the reset button and the self-test button is used to break the bottom electrode. When the detecting device is in normal operation, the button can be used to initially determine the cause of the alarm. The detecting device can judge the change of the lining.

19, output copper row and water-cooled cable

The output copper row is made of high quality T2 copper row with a purity of 99.9%. The copper busbar is connected to the variable frequency power supply and the furnace water-cooled cable.

The water-cooled cable is made of high-quality T2 material multi-strand copper stranded wire. The jacket is made of American Gates carbon-free hose or high-strength flame-retardant rubber tube. The joint needs to be cold-formed to ensure good contact and strong tensile strength.

The water-cooled cable and the induction coil must be connected to ensure better electrical conductivity, no deformation under high temperature working environment, good contact, long service life, impermeability > 10kg/cm 2 , convenient and quick to replace, easy to repair.

20, model

The boring die is made of ≥8mm steel plate and can be pulled out at any time as the furnace melts or the slab is finished.

21, furnace lining fast ejection mechanism (optional)

The lining ejector mechanism is used for quickly removing the waste lining, and needs to be composed of a pushing block, a pushing cylinder and an operating mechanism. The pushing block is installed under the lining and can be connected to the pushing cylinder through the pushing hole at the bottom of the furnace body. When the old lining is required to be pushed out, the furnace body can be tilted by 90°, and the pushing mechanism is connected with the fixing part of the bottom of the furnace, and the furnace table is operated. The old lining can be pushed out by the handle.

22, the intermediate frequency furnace table operating cabinet:

Stainless steel cabinets, instruments and operating controls are mounted on stainless steel panels. Install the operation switch, button, signal indicator and instrument indication on the operation console. The main function is the semi-automatic or manual manual operation of the intermediate frequency furnace system. This panel has a hinge that can be opened for easy maintenance inspection. There are mainly the following components.

The power meter, voltmeter shows the electric furnace voltage and frequency meter, as well as the required transmitter, voltage transformer, current transformer, used to monitor and control the operating conditions of the two electric furnaces.

Press button to control the "run" and "disconnect" of the inverter

Main power indicator, this indicator lights when the circuit breaker is closed to power the variable frequency power supply.

The main console outlet mode is in front of the platform, and the terminal blocks are arranged in the console panel.

23, hydraulic device

The hydraulic device is mainly composed of two parts: a hydraulic pump station and a hydraulic console.

Hydraulic power station

The hydraulic pumping station is used to provide power to the cylinder of the tilting cylinder lining out of the mechanism cylinder. It needs to adopt a dual-machine dual-pump unit (one set of work, one set of spare), and has a pressure regulating device, oil returning and oil suction filtering device. The hydraulic cylinder requires a protective cover to ensure that the cylinder rod is not contaminated by dust and splash metal.

Hydraulic console

The hydraulic console is mounted on the table to control the tilting of the furnace (in the range of 0 to 95 degrees) and the lining. The operation console is operated by manual hydraulic valve. The work should be reliable, stable, without impact and creeping. The speed can be adjusted and can stay at any position.

24, power supply, furnace body circulating water cooling system

Power supply, induction coils and other components carrying large currents require water cooling. The cooling water system is the key system in the intermediate frequency smelting device. The power supply and the furnace water cooling system are relatively independent. The power supply and furnace circulating water cooling system is composed of a pump station, an exchanger, a closed cooling tower, a gas-water separation, a pipeline filter, and a monitoring device.

Power Cooling System RBL-50T

The power supply cooling system adopts closed cooling mode. The cooling system of the furnace body removes the heat of the cooling water through the heat exchanger. It is required to set the display water pressure and temperature, and is equipped with a pressure switch and a temperature switch, a water pressure regulating switch, a water quantity control valve, etc. The component monitors the cooling system and emits an audible and visual alarm when the water pressure or temperature is abnormal, and cuts off the main power. The main components of the pump are Shanghai Kaiquan pump or tin pump. The circulating water pipe and valve are made of domestic high-quality stainless steel. The hose connection part is under pressure ≥1.0Mpa, and the clamp is made of stainless steel.

Furnace cooling system RBL-80T

The furnace cooling system adopts a closed cooling tower, and the tube heat dissipation heat exchanger is placed in the tower to ensure the cooling effect by the heat exchange between the circulating air, the spray water and the circulating water. At the same time, the furnace cooling water is cooled by the heat exchanger to the cooling water of the power supply. The closed cooling tower must meet the cooling requirements of the power supply and the cooling water of the furnace body. It is required to set the display water pressure and temperature, and is equipped with pressure switch and temperature switch, water pressure adjustment switch, water quantity control valve, self-cleaning pipeline filter and other components on the water outlet pipe to monitor the cooling system when the water pressure or temperature is abnormal. Can sound and light alarm, while cutting off the main power. The main components of the pump are Shanghai Kaiquan pump or tin pump. The circulating water pipes and valves are made of stainless steel. The hose connection part is under pressure ≥1.0Mpa, and the clamp is made of stainless steel.

Hydraulic station control cabinet: (1 set)

A control device is installed in the cabinet to provide power and control for the motor of the hydraulic pump station .

The main electrical components selected ABB, Siemens, Chint brand.

1            Major purchased parts supplier