Graphite Rotor Applications:
Graphite rotor includes impeller and shaft. Used in the aluminum and zinc casting industries, nitrogen, argon or carbon tetrachloride are injected and sprayed into molten metal through graphite rotors for dehydrogenation. It can eliminate the bubbles inside the castings and improve their inner quality. Injects inert gases into the Metallic solution
Graphite rotor is an appropriate product which could be used in depuration to dispose hydrogen of Aluminium melt.
The main reason of the graphite rotor damage:
Oxidation in the high temperature: the main element of graphite is carbon, Graphite in more than 600 ℃ air condition happened visible oxidation phenomenon, The product of carbon oxidation reaction is CO and CO2 gases, it will not protect the rotor.
Used for aluminium, alloy, zinc and other casting industry's purification, deslagging, degassing, blow materials, etc. Special treatment greatly improves the service life . Shorten the smelting time, reduce the production cost. Outgassing rate is more than 50%,being suitable for purification treatment of the liquid aluminum in the crucible furnace , ladle, outgassing box, static box.
Graphite rotor work continuously within the speed of 200 r/min to 400 r/min in about 750 ℃ aluminum melt . Our graphite rotors are made from high purity graphite graphite quality has a significant effect to the service life of the rotor
Working principle:
Dashing into nitrogen and argon, exhausting hydrogen and impurity.
Graphite rotor consists of rotor rod and nozzle. Drive system drives graphite rotor to make the rotary motion, argon or nitrogen are blowed into aluminum melt through graphite rotor's rod and nozzle. High speed rotating graphite rotor breaks up the argon gas and nitrogen in the aluminum melt and makes them form many scattered small bubbles, dispersing in the liquid metal. And the rotating rotor also promotes hydrogen and impurity to spread, make them contact bubbles, the bubbles in the melt absorb hydrogen and oxidation slag with gas pressure difference and surface adsorption principle. hydrogen and oxidation slag are brought out of the melt surface with the bubble rising, making the melt purify.
1. Graphite rotor rotating nozzle is made from high purity graphite, the structure of the nozzle should be considered to scatter bubbles.Also it should be considered to use agitation aluminium alloy melt to produce centrifugal force, making the melt go into the nozzle and mix evently with the horizontal extrusive gas, forming gas/liquid flow to jet, increasing the contact area and the contact time of bubbles and aluminium alloy liquid , improving the gas purification effect.
2, graphite rotor speed can realize stepless adjustment through the frequency converter , it can reach to 700 r/min. Graphite rotor specifications : Φ 70 mm to 250 mm, impeller specifications : Φ 85 mm to 350 mm. high purity antioxidant graphite rotor is high strength, high temperature resistant, resistant to aluminum flow corrosion etc. In the purification degassing process, the aluminum alloy liquid surface is filled with nitrogen to protect, making graphite rotor out of liquid aluminum alloy in the inert gas, preventing rotor high temperature oxidation, prolonging the service life of the rotor.
3, impeller shape is streamline, can reduce the resistance of the rotating ,the friction scour force of lmpeller and aluminium alloy liquid is relatively small.,which makes the outgassing rate be more than 50%, shorten the smelting time, reduce the production cost.
4, surface with a special oxidation treatment maks the service life be five times more than ordinary products. the rotors are widely used in aluminum alloy casting industry.
5, the life cycle is up to 2 month in aluminum foil casting, aluminum alloy wheel hub, etc.
Graphite rotor operation skills :
1, preheating before using: graphite rotor preheats 5 min ~ 10 min in the liquid level above 100 mm before immersing in liquid aluminum . avoid stock cooling has influence on material; Rotor must pass into the gas before immersion; it can stop providing the gas after raising the level to prevent rotor head to jam.
2. Isolation air: filling the nitrogen or argon into the purifying box, ensure that the pressure in the box being positive, isolation foreign air, in order to prevent graphite rotor oxidation.
3. Rotor immersion depth: the reasonable depth of graphite rotor dipping aluminum melt , makes the rotor rod goes beyond about 80mm above the aluminum liquid, immersion length is 60 mm or so, which can effectively increase the rotor oxidation loss and scour
4, drive system being smooth: graphite rotor and drive system are connected through connecting rod (tube), connecting rod deformed because of long-term high temperature , or drive equipment related parts loose, which will affect the rotor's neutral and running stability, easy to make graphite rotor break or knock.
5.Argon or nitrogen should be pure: if the line, joint etc causeing the gas leakage will make argon gas or nitrogen gas in the aluminum melt is not pure,which can make the rotor upper severe oxidation, or even make the lower rotor jet holes oxidation, this will greatly shorten the service life of the rotor.
Economic aspects of the rotor:
Reducing the processing cost is very important for aluminum alloy foundry and aluminium factory. our graphite rotor can bring the following benefits.
1, reduce the processing cost
2, reduce the inert gas consumption
3, reduce the aluminum content in the slag
4, improve performance, more longer eplacement cycle
5, improve the reliability, reduce the maintenance costs.
The main reason for the damage of the graphite rotor:
1. High temperature oxidation: graphite ingredients are mainly carbon, graphite will be oxidized in more than 600 ℃ air condition, carbon oxidation reaction will produce CO and CO2, the gas could not protective the rotor; Generally speaking, gas box can't fully close, and most of the cavity without charging protection gas , graphite rotor oxidation is inevitable. The oxidation of the rotor will make shaft diameter become smaller, until the fracture scrap.
2. Liquid aluminum scouring: graphite rotor immerse in the aluminum liquid,it generally rotates with 200 r/min to 400 r/min speed rotation and strongly agitates liquid aluminum, aluminum liquid and the rotor will produce strong erosion, friction. Especially the contact parts of liquid level and rotor bar will be thin and fracture.
3. The influence of the drive system: drive system is not smooth, especially connection with the rotor is different heart, rotor swings in the running process, on the one hand, the friction between rotor and sealing plug causes damage; On the other hand,it increases liquid tumbled, rotor oxidation, scour intensifies,which speed up the rotor loss.
