SAF-9000KVA Ferrosilicon Submerged Arc Furnace

SAF-9000KVA Ferrosilicon Submerged Arc Furnace

Introduction to Submerged Arc Furnace Principle and Application

Ferrosilicon subemerged arc furnace is an electric furnace used for smelting metals. Its working principle is to use the resistance heat generated by the current passing through the graphite electrode and the charge to melt the ore. It is mainly composed of furnace body, electrode, cooling system and other parts. The furnace body is like a solid container, carrying the entire smelting process; the electrode is like an energy carrier, introducing a strong current into the furnace; the cooling system can ensure the stable operation of the furnace body under high temperature environment to prevent overheating damage.

Ferrosilicon furnace belongs to subemerged arc furnace, which is mainly used for reducing ore, carbonaceous reducing agent and solvent and other raw materials. It mainly produces ferrosilicon, ferromanganese, ferrochrome, ferrotungsten, silicon-manganese alloy and other ferroalloys, which are important industrial raw materials and chemical raw materials such as calcium carbide in the metallurgical industry. Its working characteristics are that carbon or magnesium refractory materials are used as furnace linings and self-training electrodes are used. The electrode is inserted into the charge for submerged arc operation, and the energy of the arc and the current passing through the charge are used to generate energy due to the resistance of the charge to melt the metal, and the charge is added successively, and the iron slag is discharged intermittently. It is an industrial electric furnace with continuous operation.

Main Types and Uses of Submerged Arc Furnaces

(1) The power consumption value varies greatly depending on the raw material composition, finished product composition, furnace capacity, etc. The values shown here are approximate.

Structural Features

Ferrosilicon subemerged arc furnace is an industrial electric furnace with huge power consumption. It is mainly composed of furnace shell, smoke hood, furnace lining, furnace bus bar, water cooling system, smoke exhaust system, dust removal system, electrode shell, electrode pressing and lifting system, loading and unloading system, gripper, burn-through device, hydraulic system, submerged arc furnace transformer and various electrical equipment.

Ferrosilicon subemerged arc furnace equipment is divided into three layers: furnace body (including furnace bottom support, furnace shell, furnace lining), iron tapping system (including ladle or pot and ladle car, etc.), burn-through device, etc.

Second Layer

(1) Smoke hood.

Most Ferrosilicon subemerged arc furnacecurrently use a closed or semi-closed low smoke hood structure, which is environmentally friendly, easy to maintain, and improves the operating environment. The closed structure can also collect the waste gas (mainly carbon monoxide) generated during production for comprehensive utilization, reduce the heat loss of the circuit, reduce the temperature of the upper part of the electrode, and improve the operating conditions.

(2) Electrode holder.

Most Ferrosilicon subemerged arc furnace are powered by three phases, and the electrodes are arranged symmetrically in the middle of the furnace in a regular triangle or inverted triangle. Large submerged arc furnaces generally use anthracite, coke and coal tar mixed electrode materials, which are self-sintered during the electric furnace smelting process.

(3) Short net

(4) Copper tile

(5) Electrode shell

(6) Unloading system

(7) Furnace dumper

(8) Smoke exhaust system

(9) Water cooling system

(10) Ferrosilicon subemerged arc furnace transformer

(11) Operating system

Third floor

(1) Hydraulic system

(2) Electrode pressing and releasing device

(3) Electrode lifting system

(4) Steel platform

(5) Hopper and circular material distribution vehicle Other accessories: inclined bridge loading system, electronic batching system, etc.

Main configuration scheme of ore-fired furnace

Ferrosilicon Subemerged Arc Furnace Main Equipment

1. Main Equipment:

This ferrosilicon subemerged arc furnace design uses a semi-enclosed fixed submerged arc furnace with a low smoke hood. The main equipment selection is as follows:

1.1 Furnace body

The ferrosilicon subemerged arc furnace body is composed of a furnace shell, a furnace lining, a furnace bottom support, etc. The furnace shell is a cylindrical body welded with 14~18mm thick steel plates, and reinforced ribs are welded on the outside to ensure that the furnace body has sufficient strength. The furnace bottom is made of 18~20mm thick steel plates, and the furnace body is supported by 25~30# I-beams. The furnace bottom is cooled by natural ventilation. The furnace shell is equipped with 1~2 discharge ports.

 The furnace lining adopts a new seamless masonry process of high-aluminum refractory bricks and self-baked carbon bricks. The thickness of the furnace wall is 460~690mm, and a 20mm thick aluminum silicate fiberboard is applied on the outside. The thickness of the carbon bricks at the furnace bottom is 800~1200mm. The furnace mouth adopts silicon carbide corundum bricks, and the flow trough adopts a water-cooling structure. Water-cooled furnace doors can also be added as needed.

1.2 Low smoke hood

Adopt full water-cooling structure or composite structure of water-cooling frame and heat-resistant concrete. Its height is to meet the needs of equipment maintenance. The full water-cooling structure adopts water-cooling frame, water-cooling cover plate, water-cooling wall and water-cooling enclosure. The water-cooling frame is made of 16~20# channel steel, the inner cover plate around the three-phase electrode is made of non-magnetic stainless steel plate, the outer cover plate and enclosure are made of Q-235 steel plate, and are equipped with pole center circle adjustment device and three-phase electrode water-cooling protective sleeve and insulation sealing device. The water-cooling frame and heat-resistant concrete composite structure adopts the side wall of the smoke hood supported by metal component columns and cooled by water, and is built with refractory bricks around. There are three operating doors on the side wall. On the large surface of the furnace, the opening direction is horizontal rotation. There are two smoke exhaust ports on the upper part, which are connected to two vertical cooling bend flues, which are directly connected to the chimney or dust removal device.

1.3 Furnace Bus bars

The Furnace Bus bars includes the water-cooled compensator, water-cooled copper tube, water-cooled cable, conductive copper tube, copper tile and its hanging, fixed connection and other devices at the transformer end. Its layout type can be divided into a right triangle or an inverted triangle. 

Regardless of the layout, it is required to shorten the distance of the short-circuit as much as possible and reduce the impedance of the short-circuit to ensure the acquisition of active power under the premise of meeting the operating space. 

The water-cooled copper tube and the conductive copper tube are both thick-walled copper tubes, and each phase is connected in the same direction in reverse parallel, so that the short-circuit round-trip current is arranged in a two-wire system, and the mutual inductance compensation and magnetic induction are offset. The middle copper tube is connected with a water-cooled cable, and the cooling water flows directly from the water-cooled copper tube through the water-cooled cable and the conductive copper tube into the copper tile. 

After cooling the copper tile, it flows out of the furnace through the returning conductive copper tube, water-cooled cable, and water-cooled copper tube. The low operating temperature reduces the heat loss generated when the short-circuit is conductive, which can effectively increase the active power of the short-circuit. At the same time, the copper tube is light in weight and easy to process and install, which greatly reduces the investment in the short-circuit.

1.4 Electrode system:

The electrode system consists of a holder cylinder, copper tile hanging, pressure ring, water-cooled sleeve, electrode lifting device, electrode pressing and releasing device, etc. In the electrode system, we have adopted international technologies such as Demark and South Africa PYROMET. For example, the electrode lifting device with hanging oil cylinder can flexibly, reliably and accurately adjust the upper and lower positions of the electrode. The upper and lower brakes and the pressing and releasing oil cylinders form an electrode live automatic pressing and releasing device. There are three sets of electrode systems, each of which includes 1 electrode cylinder, 1 holding cylinder, 1 protective sleeve, 1 pressure ring, and 6 to 8 copper tiles. The function of the holder is to hold the self-baking electrode, and the protective sleeve, pressure ring, and copper tile are hung and fixed on it in sequence. Each electrode is equipped with 6 to 8 copper tiles. Through the oil cylinder and the tightening device on the pressure ring, a one-to-one tightening copper tile is formed, and the pressure is uniform, which can ensure that the clamping force of the copper tile on the electrode is balanced, and the contact and conductivity between the copper tile and the electrode are good.

The upper part of the gripper is connected by a stand and two lifting cylinders. The support of the cylinder is fixed on the steel platform of the three-layer platform. The pole center circle can be adjusted within a certain range on the steel platform as needed.

Each electrode is equipped with a separate electrode automatic pressing and releasing device. The airbag brake (or hydraulic brake) holds the electrode tightly. The inflated airbag holds the electrode tightly, and the deflated airbag releases the electrode.

The upper and lower airbag brakes are connected by guide columns and the pressing and releasing cylinder. The lower airbag brake is connected to the holding tube. During smelting, the lower airbag always holds the electrode tightly. Only when it is pressed and released, it cooperates with the upper airbag to alternately release the clamped electrode to complete the pressing and releasing action.

1.5 Cooling water system

The cooling water cooling system is a device for cooling components (including short nets, pressure rings, protective sleeves, furnace shells, smoke hoods, chimneys) working under high temperature conditions. It consists of a water distributor, a water collecting tank, a pressure gauge, valves, pipes and hoses, joints, etc.

The waterway of the pressure ring of the short network (including water-cooled copper pipes, water-cooled cables, and copper tiles) is specially equipped with a drain device for rapid drainage during maintenance and emergency repairs. The cooling water requirements for the water-cooled short network, pressure ring, and protective cover are: soft water, water inlet temperature ≤30℃, and water outlet temperature ≤50℃.

2. Main electrical equipment

2.1 Submerged arc furnace transformer

Use low-loss energy-saving shell-type submerged arc transformer, on-load electric voltage regulation, strong circulation, oil-water cooler, impedance voltage 4~6%, primary side voltage can be 35~110KV, secondary side voltage is divided into 5~27 levels (different capacity transformers and different smelting varieties use different secondary voltage levels), the first few gears are constant power, the last few gears are constant current, and the overload capacity is required to be >25%, and the side outlet pipe connection method is adopted.

2.2 High-voltage power supply system

The high-voltage power supply system is fed by 35KV (or 110KV) through the transformer isolating switch and vacuum breaker to the electric furnace transformer. At the same time, the harmonic absorption device and primary compensation can be designed according to user requirements.

2.3 Low-voltage power supply system

A power transformer is installed, and the power supply is sent to the power cabinet in the main room, to the water pump, transformer, voltage regulating device, power control power supply, PLC power supply, hydraulic station and air compressor room. Low voltage can increase secondary compensation.

3. Main auxiliary equipment

According to user needs, the equipment or drawings designed and manufactured by our company can be prepared by the user or used.

3.1 Feeding and feeding system equipment

The feeding equipment can be belt feeding, single bucket elevator feeding, bucket elevator, hopper, material tank and single beam electric hoist feeding. The feeding equipment can be a material distribution trolley, steel silo → feeding pipe → electromagnetic vibrating feeder → automatic gate valve → feeding pipe.

3.2 Furnace unloading equipment: molten iron ladle, molten iron ladle gantry hook, ladle transport vehicle, ground winch.

3.3 Casting equipment: ingot mold

3.4 Stamping machine, charging machine, burn-through device.

3.5 Dust removal equipment

3.6 High pressure compensation, secondary low pressure compensation.