Hx-15t Steelmaking Electric Arc Furnace

• Customization: Available
• After-sales Service: One Year
• Warranty: One Year
• Model NO.: HX-15t
• Secondary Voltage: Level 7:294V ~ 141V
• Voltage Regulating Mode: No Load Electric Voltage Regulation
• Secondary Rated Current: 13345A
• Transport Package: Case
• Specification: 304
• Trademark: jinrong
• Origin: China
• Package Size: 1.00cm * 1.00cm * 1.00cm
• Package Gross Weight: 20000.000kg

Product Description

1.Main technical parameters and component function description of the equipment

1.1 Main technical parameters
    Turn to the left (facing the transformer, turn the rotating frame to the left)
Nominal capacity 15t
The maximum capacity is 20t
Shell inner diameter φ3700mm
Rated capacity of transformer 7000kVA (20% long-term overload allowed)
The primary voltage is 11kV
Secondary voltage 294V ~ 141V level 7
Voltage regulation mode No load electric voltage regulation
Secondary rated current 13345A
Graphite electrode diameter φ350mm (high power electrode)
Electrode distribution circle diameter φ950mm±50
Electrode lifting stroke: 2300mm
Maximum electrode rise speed 3.5 (automatic) 4.0 (manual) m/min
The maximum electrode descent speed is 3.5 (automatic) 4.0 (manual) m/min
The maximum inclination Angle to the drawing side is 45°
Maximum inclination Angle to slag side: 15°
Maximum steel tilting speed 1 degree/second
Outlet type Outlet groove
The opening Angle of the furnace cover is 85°
Open the lid at 2 degrees/second
The lifting height of the furnace cover is 300mm
The whole lifting time of furnace cover is < 0.5min
The size of the slag outlet is 850×650mm
Cooling water consumption 180t/h(including transformer cooling water)




2.2.1 Mechanical structure description and working principle
HX-15t three-phase steelmaking electric arc furnace for the furnace cover screw open top charging, steel groove steel form, the mechanical part is composed of the following parts.
2.2.1.1furnace body
The furnace body includes the furnace shell, the steel groove, the furnace door, the lifting mechanism of the furnace door and the inspection platform of the steel groove, etc.
The top of the furnace shell is welded with sand sealing groove, and the groove is lined with magnesia, which improves the sealing between the furnace shell and the furnace cover, reduces the high temperature diffusion in the furnace and the flame channelling. Under the sand sealing groove is a water-cooled ring structure, which is cooled by water to prevent the furnace shell from overheating and deformation. The bottom is provided with a connecting flange plate, which is connected with the tilting frame through a wedge iron.      
The shell is made of steel plate with a thickness of 18mm and its inner diameter is 3700mm. The shell body and reinforcement plate are made of 20g material. The maximum steel output is 20t, the bottom of the furnace body is butterfly bottom, and the bottom is welded with 20mm thick steel plate. The inner wall and bottom of the lower furnace body are lined with refractory materials (that is, furnace lining), which can be constructed with formed brick.
A maintenance platform is installed in the steel outlet groove to facilitate the knot and maintenance of the steel outlet.
The outlet groove is composed of two sections of welded parts, which are bolted together. There is a prefabricated flow groove made of refractory material in the steel groove. When the flow groove is damaged, it can be lifted away by truck and replaced with a new flow groove, which is very convenient to operate.
The furnace door mechanism is composed of a furnace door frame, a guide rail, a furnace door and a furnace door lifting mechanism. The furnace door frame is welded by steel plate into a box-type water cooling structure, and the furnace door is knotted with internal refractory materials, which is not cooled by water. The door rail and the vertical direction form a 10 degree Angle to increase the sealing between the door and the door. The door lifting mechanism is manual mode, adopts the lever principle, and is equipped with an adjustable balance hammer.
The net height of the slagging door is > 600mm, which is convenient for on-site slagging operation. 
After the water cooling ring of the furnace shell and the furnace door frame of the furnace door mechanism are made, water pressure leak detection should be carried out. The test method is: the water pressure is 0.8Mpa and the pressure is maintained for 60 minutes.
2.2.1.2 furnace lid
The furnace cover includes: the furnace cover body, the central triangle area refractory prefabricated parts (user's own).
The furnace cover adopts tubular water cooling structure, sand sealing knife is set, and the furnace body sand sealing groove is matched. The water cooling pipe material is 20G.
After the furnace cover is made, water pressure leak detection should be carried out. The test method is: the water pressure is 0.8Mpa and the pressure is maintained for 60 minutes.   
2.2.1.3furnace tilting mechanism
Tilting mechanism includes: arc frame, tilting hydraulic cylinder, rail base, limit device and horizontal support device. The maximum tilt Angle of the steel side is 45°, and the slag side is 15°. The tilting action is driven by the plunger cylinder, the arc frame rolls along the horizontal rail, the hydraulic cylinder is driven out when the steel side tilts, and the hydraulic cylinder is compressed and relieved by the dead weight of the furnace body when the slag side tilts. The arc frame is provided with positioning nails to ensure that the emotional process does not deviate. The two ends of the hydraulic cylinder are connected to the tilting platform and the foundation respectively, and the earring is installed with a joint bearing to eliminate stress. The limit device comprises a mechanical limit and an electrical limit. The mechanical limit is only used in the maintenance, which is divided into front support and rear support. Before the electric furnace is stopped and repaired, the electric furnace is in a horizontal state, and then the two support rods are lifted respectively to ensure that the electric furnace is in a horizontal state and will not tilt. Compared with the traditional horizontal locking device, the advantages of the horizontal support device are that the force direction of the horizontal support is the downward pressure load of the vertical ground, and the bearing capacity is large. The electrical limit includes three states of forward tilt in place, horizontal in place and backward tilt in place, as well as front and rear support of the jacking in place and back in place, and is equipped with an indicator light on the operation table and a chain on the program. (See 5.2.6 for specific chains)

In order to ensure the maintenance of electric arc furnace support cylinder, the width of the foundation pit is designed to be 130cm.
2.2.1.4Lid lifting and rotating mechanism:
The lifting and rotating mechanism of the furnace cover is composed of a rotating frame, a lifting mechanism of the furnace cover, a rotating mechanism of the furnace cover, a limiting device and a rotating locking device.
As the supporting structure of the furnace cover and electrode lifting device, the rotating frame is welded by steel plate and has a uni-shaped
structure frame. Equipped with mounting guardrail and seat belt anchor points.
The lifting mechanism of the furnace cover is composed of two hydraulic cylinders, chain, sprocket and synchronous shaft. The rise of the furnace cover is realized by the chain driven by the hydraulic cylinder, and the fall is realized by the self-weight of the furnace cover.
The unscrewing mechanism of the furnace cover is composed of cross roller rotary bearing and rotary hydraulic cylinder with large bearing capacity. Driven by the rotating cylinder, the furnace cover and lifting rotary mechanism can be rotated or rotated on the tilting platform at a rotation Angle of 85°. The hydraulic cylinder is provided with a buffer structure, and a mechanical buffer mechanism is provided at the furnace cover rotation to reduce the impact of the furnace cover rotation. In order to lubricate the cross roller rotary bearings well, the bearings are lubricated by hand/automatic centralized lubrication system.
The limiting device comprises: the furnace cover is rotated to position and back to position; The latch of the rotary locking device is in place, the pull pin is in place, the furnace cover is lifted into place, and the furnace cover is lowered into place. And the operator is equipped with an indicator light, and the program is provided with a chain. (See 5.2.6 for specific chains)
The rotary locking device is a hydraulically driven latch device.
2.2.1.5 Electrode lifting device
The electrode lifting device is composed of a conductive cross arm, a column, a guide wheel, an electrode lifting hydraulic cylinder, an electrode clamping mechanism, a trailer, etc. The conductive cross arm is a rectangular beam structure made of copper-steel composite plate, which is cooled by water inside. The connecting part between the transverse arm and the column is insulated by using 3240 phenolic glass cloth insulating material. The electrode distribution circle can be adjusted ±50mm. The electrode distribution circle is φ950 and adjustable to ±50mm. The column is made of steel pipe and steel plate welded into a member with double guide rails. The guide surface is machined to ensure straightness and form and position tolerances. It is vertically installed in the mechanism of the double-layer guide wheel on the rotating frame of the furnace cover, and the guide wheel is compressed with the column. The guide wheel plays a guiding role on the column during the lifting of the electrode. The electrode lifting hydraulic cylinder is installed in the column, driving the column up and down, simple structure, saving space. The bracket holds up the lower end of the lifting hydraulic cylinder, which is equivalent to the base of the lifting column, and the bracket is suspended under the rotating frame. The electrode clamping mechanism consists of an electrode clamping spring, a connecting rod, a brake, a hydraulic cylinder, etc. The hydraulic cylinder and dished spring clamp and relax the electrode by connecting rod and holding brake. The electrode holder is made of copper forging, which has the advantages of good electrical conductivity, high mechanical strength and abrasion resistance. In the structure, the traditional buried pipe cooling method is abandoned, and the deep hole is used to direct water cooling, which greatly enhances the cooling effect and improves the service life of the chuck. The electrode lock is made of non-magnetic stainless steel. The electrode lifting device has the following advantages: the copper steel composite conductive transverse arm is flexible in lifting, the system has little inertia and good rigidity; Simple structure, good insulation performance, high reliability; Convenient and reliable clamping and relaxing electrode; The clamping force of the electrode is large, and the ignition phenomenon is not easy to occur at the chuck. The electrode lock is a water-cooled component, which will not cause the electrode to slide due to thermal expansion in the high temperature area.
2.2.1.6 High current line
The high-current line is composed of connecting copper bar, soft compensation, through-wall copper bar, large-section water-cooled cable, conductive cross arm, electrode holder, graphite electrode and support, etc. The two ends of the water-cooled cable are respectively connected with the copper bar through the wall and the conductive cross arm with stainless steel bolts. Water cooling cable and conductive cross arm, water cooling. Using the space triangle arrangement, the value of the three-phase impedance unbalance is less than 5%, so that the energy of each phase in the input furnace is balanced and reasonable as far as possible, which can shorten the melting time and effectively improve the life of the furnace lining. Connecting copper bars and through-wall copper bars are made of T2 material copper, and the lap surface is drilled, deburred and de-oxidized. Soft connection is a copper conductor composed of multiple layers of purple copper foil superimposed. Copper foil selected T2 material copper strip, a single piece of copper foil thickness of about 0.2mm. At both ends of the lap surface, the polymer diffusion welding process is used to dissolve the multi-layer copper foil on the contact surface together, change its molecular structure, solidified into copper blocks, passivation treatment, lap surface drilling, and the surface and the surrounding area of the burr treatment, and the lap surface tin plating. The role of soft connection:
1, play an auxiliary cooling role.
2, can avoid the surrounding environment due to earthquake, displacement and other operating accidents.
3. Absorb the noise and vibration generated during transformer operation.
4, make the conductive connection inside the short network more convenient, reliable, protect the equipment from external influence.  
The water-cooled cable consists of an end joint, a soft conductor, an outer sleeve, a core tube, a clamp and a protective ring. Each phase of two, a single section of 2400mm2 (6 strands of 400mm2 twisted). The end joint is made of T2 copper rod turning, internal water holes are drilled, and two stainless steel cable tie grooves are arranged on the copper joint, and the internal krulling is treated to increase the sealing and prevent the leakage of cooling water or the withdrawal of the outer casing. The soft wire uses T2 copper material of national standard oxygen-free bare copper wire, which has good softness, small bending radius, tight structure, no stress residual and no scattering phenomenon. The outer casing is made of synthetic rubber tube with reinforced reinforcement layer, which can withstand the pressure of cooling water and mechanical stress during movement. It has high temperature resistance, electric radiation heat resistance, good insulation performance, good curvature, small bending radius and long service life. The core tube is used to support and position the flexible wire and withstand the tension and flexible extrusion of the water-cooled cable connection. The clamp is installed at both ends of the outer casing, which is used to fix the outer casing and the end joint and has a locking device. The clamp made of non-magnetic 304 stainless steel and the clamp anti-collision ring are separated in the outermost layer of the water-cooled cable, which is a synthetic rubber ring to reduce the external wear of the water-cooled cable and buffer the shock effect.
2.2.1.7 hydraulic system
The hydraulic system is composed of pump station, oil tank, accumulator, valve platform, cooler, filter and pipeline and other accessories. Provide power source and control for EAF body tilting cylinder, horizontal support cylinder, cap rotating cylinder, cap jacking cylinder, rotary locking cylinder, electrode lifting cylinder and electrode relaxation cylinder. The hydraulic source has two constant pressure variable pumps (one used and one standby), the motor is selected from Wannan motor, and the liquid storage box is equipped with domestic Chuan instrument pressure, temperature sensor and level sensor, and temperature control actuator. The pressure of the hydraulic system is 12MPa, and there is a pointer pressure display device on the hydraulic station. The working medium is water-glycol, the hydraulic medium is filtered in the hydraulic box through the oil suction filter, and a high pressure pump provides all the system pressure oil. The oil tank of the hydraulic station is made of 304 stainless steel, with a capacity of 2000L, equipped with 4X100L accumulator, and two inspection manholes are set on the side of the oil tank. The hydraulic station pump body is placed outside the box for easy maintenance. An oil collecting tank and an oil discharge port are provided around the box. Hydraulic station with water cooler. The soft connection and pipe connection of hydraulic station are connected by ball valve with flange. Hydraulic hose with fire resistant and externally wrapped wire mesh tubing.
2.2.1.7.1 Control valve station
2.2.1.7.1.1 The three phase electrode lifting adjustment adopts 4 groups of imported Parker brand built-in amplifier plate electro-hydraulic proportional valve (3 used and 1 standby), the standby proportional valve is manually switched through the three-way ball valve, and the proportional valve is composed of the cartridge integrated block circuit to form the automatic electrode control circuit.
2.2.1.7.1.2 The lifting, electrode loosening, rotating support, rotating locking, etc. are controlled by the Beijing Huade slide valve.
2.2.1.7.1.3 Furnace body tilting and furnace cover opening are controlled by domestic proportional valve.
2.2.1.7.2 Other Parameters
2.2.1.7.2.1 All pressure gauges used in the system are seismic pressure gauges.
2.2.1.7.2.2 System cleanliness of hydraulic system media NAS7 level.
2.2.1.7.2.3 All ball valves and hydraulic hoses in the hydraulic station are made of well-known domestic brands.
2.2.1.7.2.4 The hydraulic system is equipped with pressure, temperature, liquid level alarm and interlocking control.
2.2.1.7.2.5 The control power supply voltage is DC24V.
2.2.1.7.2.6 The rated pressure of high-pressure elements on all valve racks is 31.5Mpa, and the flow rate meets the flow requirements of the actuator.
2.2.1.7.2.7 The system is equipped with two stages of filtration -- the inlet and return oil lines are equipped with filters, the inlet oil filtration accuracy is less than 10μm, and the return oil filtration accuracy is less than 20μm.
2.2.1.7.2.8 The hydraulic valve block is forgings and adopts electroplating (chromium or nickel plating) to prevent rust.
2.2.1.7.2.9 The oil piping and flanges in the station are made of stainless steel (304), cold-rolled precision seamless steel, and the oil pipes in the hydraulic station have visual identification and description of the functional direction.
2.2.1.7.2.10 Heavy aluminum alloy pipe clamps are used for hydraulic system pipelines.
2.2.1.7.2.11 energy accumulator
Accumulator type: skin type accumulator Rated pressure: 20MPa accumulator capacity: 100L (to meet the accident state can shake the furnace body from the steel to the horizontal position, the electrode in the smelting position raised by 400mm) Number of accumulators: 4 accumulator device with pressure protection cut off unloading function. Nitrogen charging pressure: 10-12 mpa
2.2.1.8 Cooling water system (closed) The cooling water system is composed of pointer pressure display device, pressure transmitter, thermal resistance, flow meter, stop valve, water dispenser, pipeline, etc. The cooling water source is connected to the main water inlet pipe of the workshop, the pressure is not less than 0.3MPa, the total inlet water temperature is not more than 32 ° C, and the water temperature of each return water is not more than 55 ° C. The main inlet pipe is provided with water pressure, water temperature and flow monitoring, and the main return pipe is provided with water temperature and flow detection. When the inlet pressure is at the bottom of the set value, the return water temperature exceeds the set value, and the difference between the inlet and return water flow is greater than the set value, an alarm signal is issued. Each branch pipeline (including hydraulic station, transformer water cooling pipe) is equipped with inlet flow detection, return water temperature, flow monitoring, when the return water temperature exceeds the set value, the difference between the inlet and return water flow is greater than the set value, alarm signal will be issued. When the return water temperature exceeds the set value and the difference of inlet and return water flow is greater than the set value, the power is automatically cut off and the electrode is raised to stop smelting. The water cooling system has a special monitoring screen, and transmits data and alarms to the PLC control. The cooling water device is located in front of the furnace on the wall side of the transformer room, connected to the cooling part of the furnace body through pipelines (including hoses), and is used for cooling the furnace body, furnace cover, conductive cross arm, water-cooling cable, hydraulic station, etc. Water pipeline valve adopts middle core valve. All monitoring instruments have instrument valves for easy instrument replacement. Water discharge ports are reserved on the inlet and return pipes of the water-cooled cables and conductive cross arm to facilitate the early discharge of water during short-network maintenance. Avoid disassembling pipes with water. The drainage pipes are led to the low point under the valve bracket to facilitate the use of containers when discharging water. 2.2.1.9 Top Side suction clamp type smoke hood The top side suction clamp type smoke hood is composed of a side suction trap and a double rotary telescopic device. The flue gas produced by the electric furnace steelmaking mainly emerges from the three electrode holes at a faster rate, and the oxygen blowing and oxidation period overflow from the furnace door. The third factor is that some flue gas will be generated when the contact surface of the furnace cover and the furnace shell is not sealed well.    
2.2.1.9.1 Side suction cover The side suction cover is a curved cover on the side of the three electrodes, which is arranged at 0.8-1m above the electrode hole of the furnace cover. The side suction cover is fixed on the portal frame and can be rotated with the furnace cover when loading. The furnace door cover is arranged above the furnace door, and a certain amount of air is allocated. When the oxygen is blown to help melt and during the oxidation period, the flue gas is pumped away from the furnace door just overflow. A diversion coiling plate is installed along the upper edge of the furnace shell. Under the guidance of the coiling plate, the flue gas from the gap of the furnace cover rises along the arc surface of the furnace cover, enters the negative pressure area of the side suction hood mouth, and is caught by the side suction hood.
2.2.1.9.2 Double-rotating mechanism Expansion pipe The double-rotating mechanism expansion pipe has two sets of rotating mechanisms, the upper rotating point is connected with the fixed smoke pipe, the lower rotating point is installed on the column fixed with the cradle, and the middle part is a double-layer expansion pipe. In one smelting cycle, the maximum forward tilt of the furnace body is 15° and the backward tilt is 45°. The lower turning point does the cycloidal track movement, the telescopic tube can rotate around the turning point on the vertical surface, and can be extended or shortened in length, and the side suction hood is always connected with the fixed pipeline, so as to realize the whole dust extraction process of the smelting process.
2.2.2 Auxiliary support
2.2.2.1 The pumping station of the external circulating water system is equipped with three water supply pumps, one for dual use. One of them fails, the standby pump is put into operation in time, and the whole pipeline from the pump to the cooling tower is a closed structure. The water supply pump sends the water of the auxiliary water tank of the cooling tower to the cooling water distributor in front of the furnace, and the water temperature rises after the heat exchange equipment, and the water is sent to the cooling tower on the roof for cooling through the tube pressure, and the cooled water is recycled back to the auxiliary water tank of the cooling tower. The cooling tower adopts Wuxi Fangzhou FBF-3364-5P closed cooling tower. Circulating water pump adopts Kaiquan low pressure centrifugal pump, motor 22kw, with soft start.
This section describes the basic conditions for device installation and operation
3.1 Power Supply Condition: a. Ac 11kV power supply system voltage: 11kV±10% Number of phases: 3 Frequency: 50±0.5Hz 7000KVAX1.2=8400KVA b. Low-voltage power distribution system Voltage 380V/220V +10% frequency 50Hz three-phase five-wire computer individually grounded Low-voltage system: about 100KW Dust removal: about 160KW (based on the final dust removal manufacturer's configuration)
3.2 Energy medium conditions: (oxygen blowing, ~20Nm³/t)


      gaseous medium

name	purity	pressure
oxygen	99.9	0.8~1.20

    Cooling water system and its supplementary fresh water quality

serial number	Items	unit	Industrial water purification
1	PH value		7.0-8.5
2	suspended solids	Mg/L	≤50
3	hardness	°dh	5-6
4	basicity	Mg/L	20-40
5	chloridion	Mg/L	50
6	temperature	ºC	≤35
7	pressure	MPa	0.4

External cooling circulating water configuration requirements: Cooling tower: 200t/h
3.3 Civil foundation
The foundation construction of all the equipment of the buyer is completed, the embedded parts required for the basic drawing are completed, and the driving is ready for use;
Electric control system function description
4.1Brand of main components

serial number	name	specifications and models	Accessory manufacturer
1	high-tension switch cabinet	KYN28-12	Western Electric
2	electric furnace transformer	HKSSP-7000/11	Changchun Sanding/Jiangsu Province
4	Electrical control cabinet housing		Verto pattern
5	programmable controller	S7-1500series	Siemens
6	Red light	XB2BVM4C	Schneider Electric
7	Yellow light	XB2BVM5C	Schneider Electric
8	Green light	XB2BVM3C	Schneider Electric
9	Short handle two-digit knob	XB2BD25C	Schneider Electric
10	rocker type switch	XD2PA22CR(both of them)	Schneider Electric
11	Three position self-resetting knob	XB2BJ53C	Schneider Electric
12	key switch	XB2BG21C	Schneider Electric
13	Red button	XB2BA41C	Schneider Electric
14	Green button	XB2BA31C	Schneider Electric
15	current transmitter	G2-A 0-5A4-20mA	Jin Rong (Custom)
16	Voltage transmitter	G2-V AC0-300V4-20mA	Jin Rong (Custom)
17	Small relay	RXM2AB2BD	Schneider Electric
18	ac voltmeter	6L2-V 0-300V	Jin Rong (Custom)
19	ac voltmeter	6L2-V 35KA/100V	Jin Rong (Custom)
20	AC ammeter	6L2-A	Jin Rong (Custom)
21	moulded case circuit breaker	WZDseries	Schneider Electric
22	AC contactor	LC1 series	Schneider Electric
23	thermorelay	LRD series	Schneider Electric
24	DC power	NDR-480-24	Taiwan Mingwei
25	Industrial Personal Computer	610 series	Advantech/Siemens
26	displayer	27"	Samsung

4.2 Electrical equipment composition and working principle
This set of electrical equipment mainly includes: high voltage power supply system, electric furnace transformer, low voltage power supply system, low voltage electrical control system, automatic adjustment system of electrode lifting, industrial computer system.
4.2.1 equipment composition
1 set of high pressure cabinet
1 electric furnace transformer
1 set of low-voltage electrical equipment
The low-voltage electrical equipment includes:
a. One main console
b. Low pressure control cabinet 1 side
c. PLC control cabinet 1 side
d. One operating table in front of the furnace
e. One operating table behind the furnace
4.2.2 System working principle
4.2.2.1 High voltage power supply system (refer to KYN28-412 sample)
· Model KYN28-12
· Rated current 1250A
· Rated voltage 11KV
"Five prevention" functions:
· Prevent misopening and closing of circuit breakers
· Prevent with load separation, closing isolation switch
· Prevent straying into live intervals
· Prevent live grounding wire
· Prevent the ground wire from closing
· The high-voltage power supply system is fed by 11KV and sent to the electric furnace transformer through the high-voltage vacuum circuit breaker. The high-voltage power supply system is also equipped with zinc oxide arrester to absorb the operating overvoltage and surge overvoltage to protect the normal operation of the transformer. The vacuum circuit breaker is used to switch on and off the main circuit of the high-voltage side.
· The high voltage side secondary metering circuit is equipped with the measurement of the high voltage side voltage, high voltage side current, power factor, active power, active power and reactive power of the electric furnace transformer.
· The secondary protection circuit is equipped with complete protection circuits such as short circuit protection and undervoltage protection.
· The DC 220V power supply of the high voltage closing and opening control loop of this system is provided by the built-in closing DC power supply. Dc 220V power supply is a single-phase bridge rectifier, flat wave, energy storage, and finally output stable DC 220V power supply to ensure that the high-voltage vacuum circuit breaker can be separated smoothly when the power supply circuit is disconnected.
· The closing and opening control of the vacuum circuit breaker of the high voltage system is mainly controlled by the main operating station in the main control room, and can also be operated locally by the high voltage cabinet during equipment debugging.
4.2.2.2 electric furnace transformer
The electric furnace transformer is a special transformer for electric arc furnace. It adopts no-load electric voltage regulation. The low voltage secondary side adopts copper bar top outlet line and external seal. Transformer oil water cooler adopts double pipe strong oil water cooler, such as cooling water leakage, cooling water flows from between the double pipe, will not pollute the transformer oil.
Transformer technical parameters:
Type: HSSPK-7000/35 electric arc furnace transformer
Rated capacity: 7000 KVA
Primary voltage: 11kV
Secondary voltage: 294V (17-21% with reactance), 294V (7-8% with reactance), 269, 245, 222V, 198V, 170V, 141V
Secondary rated current: 137460A
Connection group: D-Y/d0-d11
Impedance voltage: 7 ~ 8%
Cooling method: strong oil circulation water cooling
Voltage regulation mode: no excitation electric voltage regulation
Secondary exit mode: open triangle top exit line, each phase of 4 copper bars.
Cooling method: Strong oil circulating water cooler (OFWF)
4.2.2.3 Low voltage power supply system
2.2.1.9.1 Side suction cover The side suction cover is a curved cover on the side of the three electrodes, which is arranged at 0.8-1m above the electrode hole of the furnace cover. The side suction cover is fixed on the portal frame and can be rotated with the furnace cover when loading. The furnace door cover is arranged above the furnace door, and a certain amount of air is allocated. When the oxygen is blown to help melt and during the oxidation period, the flue gas is pumped away from the furnace door just overflow. A diversion coiling plate is installed along the upper edge of the furnace shell. Under the guidance of the coiling plate, the flue gas from the gap of the furnace cover rises along the arc surface of the furnace cover, enters the negative pressure area of the side suction hood mouth, and is caught by the side suction hood.
2.2.1.9.2 Double-rotating mechanism Expansion pipe The double-rotating mechanism expansion pipe has two sets of rotating mechanisms, the upper rotating point is connected with the fixed smoke pipe, the lower rotating point is installed on the column fixed with the cradle, and the middle part is a double-layer expansion pipe. In one smelting cycle, the maximum forward tilt of the furnace body is 15° and the backward tilt is 45°. The lower turning point does the cycloidal track movement, the telescopic tube can rotate around the turning point on the vertical surface, and can be extended or shortened in length, and the side suction hood is always connected with the fixed pipeline, so as to realize the whole dust extraction process of the smelting process.
2.2.2 Auxiliary support
2.2.2.1 The pumping station of the external circulating water system is equipped with three water supply pumps, one for dual use. One of them fails, the standby pump is put into operation in time, and the whole pipeline from the pump to the cooling tower is a closed structure. The water supply pump sends the water of the auxiliary water tank of the cooling tower to the cooling water distributor in front of the furnace, and the water temperature rises after the heat exchange equipment, and the water is sent to the cooling tower on the roof for cooling through the tube pressure, and the cooled water is recycled back to the auxiliary water tank of the cooling tower. The cooling tower adopts Wuxi Fangzhou FBF-3364-5P closed cooling tower. Circulating water pump adopts Kaiquan low pressure centrifugal pump, motor 22kw, with soft start.
This section describes the basic conditions for device installation and operation
3.1 Power Supply Condition: a. Ac 11kV power supply system voltage: 11kV±10% Number of phases: 3 Frequency: 50±0.5Hz 7000KVAX1.2=8400KVA b. Low-voltage power distribution system Voltage 380V/220V +10% frequency 50Hz three-phase five-wire computer individually grounded Low-voltage system: about 100KW Dust removal: about 160KW (based on the final dust removal manufacturer's configuration)
3.2 Energy medium conditions: (oxygen blowing, ~20Nm³/t)


      gaseous medium

name	purity	pressure
oxygen	99.9	0.8~1.20

    Cooling water system and its supplementary fresh water quality

serial number	Items	unit	Industrial water purification
1	PH value		7.0-8.5
2	suspended solids	Mg/L	≤50
3	hardness	°dh	5-6
4	basicity	Mg/L	20-40
5	chloridion	Mg/L	50
6	temperature	ºC	≤35
7	pressure	MPa	0.4

External cooling circulating water configuration requirements: Cooling tower: 200t/h
3.3 Civil foundation
The foundation construction of all the equipment of the buyer is completed, the embedded parts required for the basic drawing are completed, and the driving is ready for use;
Electric control system function description
4.1Brand of main components

serial number	name	specifications and models	Accessory manufacturer
1	high-tension switch cabinet	KYN28-12	Western Electric
2	electric furnace transformer	HKSSP-7000/11	Changchun Sanding/Jiangsu Province
4	Electrical control cabinet housing		Verto pattern
5	programmable controller	S7-1500series	Siemens
6	Red light	XB2BVM4C	Schneider Electric
7	Yellow light	XB2BVM5C	Schneider Electric
8	Green light	XB2BVM3C	Schneider Electric
9	Short handle two-digit knob	XB2BD25C	Schneider Electric
10	rocker type switch	XD2PA22CR(both of them)	Schneider Electric
11	Three position self-resetting knob	XB2BJ53C	Schneider Electric
12	key switch	XB2BG21C	Schneider Electric
13	Red button	XB2BA41C	Schneider Electric
14	Green button	XB2BA31C	Schneider Electric
15	current transmitter	G2-A 0-5A4-20mA	Jin Rong (Custom)
16	Voltage transmitter	G2-V AC0-300V4-20mA	Jin Rong (Custom)
17	Small relay	RXM2AB2BD	Schneider Electric
18	ac voltmeter	6L2-V 0-300V	Jin Rong (Custom)
19	ac voltmeter	6L2-V 35KA/100V	Jin Rong (Custom)
20	AC ammeter	6L2-A	Jin Rong (Custom)
21	moulded case circuit breaker	WZDseries	Schneider Electric
22	AC contactor	LC1 series	Schneider Electric
23	thermorelay	LRD series	Schneider Electric
24	DC power	NDR-480-24	Taiwan Mingwei
25	Industrial Personal Computer	610 series	Advantech/Siemens
26	displayer	27"	Samsung

4.2 Electrical equipment composition and working principle
This set of electrical equipment mainly includes: high voltage power supply system, electric furnace transformer, low voltage power supply system, low voltage electrical control system, automatic adjustment system of electrode lifting, industrial computer system.
4.2.1 equipment composition
1 set of high pressure cabinet
1 electric furnace transformer
1 set of low-voltage electrical equipment
The low-voltage electrical equipment includes:
a. One main console
b. Low pressure control cabinet 1 side
c. PLC control cabinet 1 side
d. One operating table in front of the furnace
e. One operating table behind the furnace
4.2.2 System working principle
4.2.2.1 High voltage power supply system (refer to KYN28-412 sample)
· Model KYN28-12
· Rated current 1250A
· Rated voltage 11KV
"Five prevention" functions:
· Prevent misopening and closing of circuit breakers
· Prevent with load separation, closing isolation switch
· Prevent straying into live intervals
· Prevent live grounding wire
· Prevent the ground wire from closing
· The high-voltage power supply system is fed by 11KV and sent to the electric furnace transformer through the high-voltage vacuum circuit breaker. The high-voltage power supply system is also equipped with zinc oxide arrester to absorb the operating overvoltage and surge overvoltage to protect the normal operation of the transformer. The vacuum circuit breaker is used to switch on and off the main circuit of the high-voltage side.
· The high voltage side secondary metering circuit is equipped with the measurement of the high voltage side voltage, high voltage side current, power factor, active power, active power and reactive power of the electric furnace transformer.
· The secondary protection circuit is equipped with complete protection circuits such as short circuit protection and undervoltage protection.
· The DC 220V power supply of the high voltage closing and opening control loop of this system is provided by the built-in closing DC power supply. Dc 220V power supply is a single-phase bridge rectifier, flat wave, energy storage, and finally output stable DC 220V power supply to ensure that the high-voltage vacuum circuit breaker can be separated smoothly when the power supply circuit is disconnected.
· The closing and opening control of the vacuum circuit breaker of the high voltage system is mainly controlled by the main operating station in the main control room, and can also be operated locally by the high voltage cabinet during equipment debugging.
4.2.2.2 electric furnace transformer
The electric furnace transformer is a special transformer for electric arc furnace. It adopts no-load electric voltage regulation. The low voltage secondary side adopts copper bar top outlet line and external seal. Transformer oil water cooler adopts double pipe strong oil water cooler, such as cooling water leakage, cooling water flows from between the double pipe, will not pollute the transformer oil.
Transformer technical parameters:
Type: HSSPK-7000/35 electric arc furnace transformer
Rated capacity: 7000 KVA
Primary voltage: 11kV
Secondary voltage: 294V (17-21% with reactance), 294V (7-8% with reactance), 269, 245, 222V, 198V, 170V, 141V
Secondary rated current: 137460A
Connection group: D-Y/d0-d11
Impedance voltage: 7 ~ 8%
Cooling method: strong oil circulation water cooling
Voltage regulation mode: no excitation electric voltage regulation
Secondary exit mode: open triangle top exit line, each phase of 4 copper bars.
Cooling method: Strong oil circulating water cooler (OFWF)
4.2.2.3 Low voltage power supply system
Workshop power supply provides three-phase five-wire braking power supply with voltage of 380V / 220V (also need to provide a separate computer grounding), to the main control room of the low-voltage cabinet in the main circuit breaker upper end (N line is connected to the cabinet with zero copper bar), and then through the main circuit breaker to each power point through the circuit breaker power supply. The circuit breakers at all levels are respectively provided to transformer regulator power supply, oil-water cooler power supply, control power supply, PLC power supply, switching power supply, variable frequency motor, hydraulic pump and backup power supply for users to use. Voltmeter and ammeter are installed on the instrument panel of the low-voltage cabinet to indicate the voltage and current of the low-voltage control system.
4.2.2.4 Low voltage electrical control system
The control of the electric arc furnace body system is completed by Siemens S7-1500 series PLC. All kinds of limit switch action signals, control switch instruction signals, contactor and relay action signals are collected through the input module, and equipment action control and interlock protection are carried out through the PLC internal program. The corresponding output module controls the closing and opening of the high voltage circuit breaker, the hydraulic pump, the hydraulic valve, the lifting and rotating of the furnace cover, and the tilting furnace interlock. At the same time, the fault signal of the equipment is detected and sent out by the indicator light and the alarm bell.
The low-voltage electric control is composed of the furnace backstage, the furnace front, the low-voltage power control cabinet, the PLC control cabinet and the electrode lifting operation table.
· Both the main console and the industrial computer have the functions of data display, status display, parameter setting and action operation.
· The main operating station and the monitor are equipped with the functions of displaying three-phase arc current and three-phase arc voltage respectively, and the voltage regulating gear display and corresponding instructions for relevant operations.
· The operation panel of the main console is equipped with the key switch for the operation of the high pressure system, the switch for the high pressure closing and opening, and the red mushroom-shaped button for the high pressure emergency opening. The transformer voltage regulating switch, the three phase electrode respectively lifting switch and lifting switch, each phase arc current given value of the switch and some other auxiliary operation switch.
· Through a series of transfer switches set on the operating platform in front of the furnace, the clamping and loosening of the three-phase electrodes and the control and operation of the operating part of the furnace (including the operation of electrode lifting, tilting, lid lifting, lid rotation, etc.) can be completed. There is also a corresponding indicator to show the execution status of the action.
4.2.2.5 Electrode lifting regulator system
The electrode lifting system and smelting process automation system adopt Siemens S7-1500 series PLC, and the communication adopts Ethernet communication.
All buttons, indicators, relays, circuit breakers and other low-voltage components use Schneider products.
PLC electrode regulator is mainly composed of Siemens S7-1500 series PLC. Arc current signal and arc voltage signal are converted into 4~20mA standard signal through standard transmitter and enter the analog module of PLC. Transformer gear signal, manual lifting electrode signal, high voltage closing signal into the PLC DI module. After the analog signal enters the PLC, it is filtered and then transmitted to each controller. The main functions are as follows:
(1) Detection of arc current, arc pressure and gear position.
(2) Control mode of operation: manual mode and automatic mode, manual mode is preferred in any case. Manual mode: In manual mode, the electrode is controlled only by manual lift/drop signals. If there is no manual lift/drop signal, the electrode stays in place. Automatic mode: In automatic mode, the electrode can be controlled by the current controller, which is set by the overcurrent controller. Its speed is proportional to the current bias and is limited within the limits given by the parameters.
(3) Communication function with industrial computer.
(4) Control mode: current control.
(5) Can achieve manual/automatic switching.
(6) To achieve various parameters online adjustment and modification, sensitivity adaptive.
(7) Arc current setting range 25% ~ 125%Ie.
(8) The output signal of the PLC regulator is sent to the inverter to complete the electrode lifting action.
(9) Install multi-function instrument to collect the primary voltage and primary current signal of the high voltage cabinet to calculate the power consumption of a single furnace, and collect the accumulated power consumption statistics to form an EXCEL report, which can be checked and printed at any time.
(10) Overcurrent control, the actual current signal is compared with the limit value obtained in a parameter setting, and the difference is multiplied by a PI controller by a time constant respectively to obtain positive and negative control values (upward integration and downward integration). The output of the controller is limited to between zero and maximum. The mode of overcurrent output can be selected so that each phase is affected by its own controller. Alternatively, a common three-phase maximum overcurrent set point can be set for each phase. When the actual current exceeds the maximum rated current of the transformer, the electrode rises at the maximum given speed (the control voltage of the electrode rise and fall in normal operation is DC-7V-+7V, and the control output is superimposed on the normal control signal according to the proportion of overcurrent, and the value is automatically calculated by the program).
(11) Short-circuit controller: If the actual current is greater than the set maximum current of the transformer, and its time exceeds the set delay time, it is considered to be a short circuit, and the responding electrode is immediately lifted by another set point. It can protect transformers and equipment. Electrode regulation control process of electric arc furnace when all the smelting chain conditions, after the high voltage closing, the mode is selected as automatic, the three-phase electrode quickly drops the electrode, after the electrode starts, the electrode rise and fall speed depends on the size of the current and always automatically track the pre-set current.
4.2.2.6 Industrial computer system
    Man-machine interface, system software using win10 system (legitimate), configuration software using WINCC7.5 (legitimate), industrial computer using Taiwan Advantech.
An HMI is placed on the indoor console for easy troubleshooting.

1. The HMI can display fault information and operating status, manage corresponding databases, record relevant data, and generate reports. It mainly includes the following contents:

(2)Mainscreen:
The main display:
Actual primary current, voltage, power, power factor, active power, transformer gear voltage, gear current, etc
Actual secondary current, secondary voltage
Set current
Control mode selection: Manual/automatic
Current curve, voltage curve, control output curve
Fault alarm information
Display heating simulation work screen.
(2)hydraulic system
It mainly displays the operating state of the hydraulic station oil pump, the hydraulic pressure, oil temperature and liquid level, and the operation state of each solenoid valve.
(3)cooling water system
It mainly displays the total inlet pressure, flow rate and temperature of the cooling water system, the total return water flow rate and temperature of each return water flow and temperature display, and can also set the pressure, flow rate and temperature alarm value.
(4) Electric furnace chain process screen
 Main display electric furnace action chain.
(5)curve
Real-time curve and historical curve of each data
(6)Alarm screen
Summary of the alarm, showing the alarm time, name. In any monitoring screen state, alarm information is preferentially popped up and prompted to the operator.
4.2.2.7Arc furnace grounding
4.2.2.8Total electric installed capacity of electric arc furnace
Electric arc furnace: 7000KVAX1.2=8400KVA
Low voltage system: approx. 100KW
Dust removal: about 160KW (subject to the final dust removal manufacturer configuration)
The total capacity is considered as 8000 KW
5,Equipment supply scope and quotation
6 Other supplementary notes
6.1 Performance Commitment
6.1.1 Provide users with equipment layout drawings, basic condition drawings, and wearing parts drawings.
6.1.2 Provide the user with the operation instructions, operation drawings and relevant technical materials.