Engineering activities concerning designing and commissioning of melting-casting equipment for aluminium alloys production
Fabrication and supply of electrical heating systems for the equipment of metallurgical purposes
One of the most important component of electric holding and melting furnaces is a heating system. RPC Magnetic hydrodynamics Ltd. engineers have developed two types of electric heating elements, which are used in the furnaces:
1 heating elements, installed inside a heat-conducting ceramics;
2 heating elements, installed inside heatproof protective steel tube.
Heating elements and protective tubes
Heating element, installed inside a heat-conducting ceramics:
A heating element shielded with heat-conducting ceramics and installed into the roof grooves, has been industrially tested within a stationary aluminium holding furnace of 35 tons capacity. Measurements which have been taken during industrial tests have shown the increase of the furnace heat efficiency by 25%.
A further development of the heating system with a heating element shielded with heat-conducting ceramics is heating elements installation inside a furnace roof refractory lining layer.
The present technical solution enables to solve the following problems:
exclude gas corrosion of metallic heating elements;
significantly decrease a deposition on the roof reflective surface;
reduce temperature on the heating elements surface and keep thermal effectiveness of the heating system at very high level;
replace heating elements without cooling of a holding furnace.
Positive effect is achieved by the following::
optimization and redistribution of thermal streams inside the heating system and in the furnace chamber;
furnace roof refurbishment;
application of high-temperature resistance alloys for heating elements (in perspective ceramic heating elements);
application of power supply devices with PID controllers — control of heating element power.
Realization of the above technical solutions and procedures provides the following:
increase of the furnace thermal efficiency by twice, which will lead to the increase of the melting-casting equipment output and reduction of specific consumption of electric energy;
increase of reliability of the furnace heating system operation, which will reduce expenses on its repairs.
Heating element, installed inside heatproof protective steel tube:
Heating elements shielded with a steel protective tube are widely used in stationary and tilting furnaces. Such a construction helps to protect a heating element from extrenal exposure and prolong its lifetime.
• The increase of heating elements' lifetime up to the 18 month during aluminium alloys preparation into aggressive chlorine and fluorine-containing media.
• The increase of thermal effectiveness due to the absence of significant dross build up of protective steel tubes.
• The increase of heating elements' lifetime becuase of power source devices, which allows to control current strength.
Tubular radiation heating elements, manufactured from local materials, have proved high maintenance reliability under arduous conditions of alloys preparation, which form aggressive environment in furnaces of various capacities.
Presently RPC Magnetic hydrodynamics Ltd. have developed the manufacture of similar heating elements for filtration systems (PDBF type) and refining systems (SNIFF type) for aluminium alloys from local materials, which surpass their foreign analogues in their properties.
Heating elements are supplied:
- over Russia to ferrous and non-ferrous processing enterprises;
- CIS (Kazakhstan and Armenia).
Created production capacity for manufacture of electric heating elements enables to perform orders for the shortest lead time.
Electrolyzer cathode sections pre-heating device
The technology of achieving reliable electric contact between a cathode block and a current-conducting steel bar of electrolyzer cathode sections is confined in pre-heating of cathode block up to the temperature of (250-500)°С and successive liquid cast iron casting into a groove.
In 2014 RPC Magnetic hydrodynamics Ltd. in cooperation with RUS-Engineering Ltd. designed, manufactured and commissioned electrolyzer cathode sections pre-heating device at RUSAL Irkutsk Aluminium Smelter. This device is able to preheat 4 cathode sections simultaneously. At rated power of 600 kW such a device provides the productivity of 24-26 cathode section per shift, considering that cathode sections are pre-heated up to 350-410°C and current-conducting steel bars are pre-heated up to 430-550°C.
The device for electrical pre-heating of electrolyzer cathode sections
Thermal calculation for the device for electrical pre-heating of electrolyzer cathode sections
The exploitation of the equipment within two years confirmed high efficiency and reliability of implemented design solutions in electrical heating system, control system and power source.
In RUSAL, electrically heated furnaces are the main process equipment, in which 100% of the aluminum produced in electrolysers is processed. Since 2002, there has been a replacement of furnaces for equipment with modern electric heating systems based on tubular radiation electric heaters, the supplier of which was a foreign firm. Since 2006, at RUSAL's plants have implemented Russian tubular radiation heaters, which are being developed and manufactured in RPC Magnetic Hydrodynamics LLC (Krasnoyarsk). According to their characteristics, domestic electric heaters are not inferior to the characteristics of electric heaters of import manufacturers, and by some, they are superior. The implementation of electric heaters by "RPC Magnetic Hydrodynamics" allowed to solve positively the problem of import substitution of expensive equipment. At present, RUSAL's demand for tubular radiation heaters is completely satisfied by supplies of RPC Magnetic Hydrodynamics LLC.
On the basis of tubular radiation heaters together with "RPC Magnetic Hydrodynamics" LLC and the branch of LLC "RUS-Engineering" in Krasnoyarsk, preheating units for cathode sections of electrolysers have been built, which have successfully passed the pilot-industrial tests. Based on the test results, a decision was made to introduce plants into production instead of previously planned gas and electric overseas installations.