Dry type mechanical vacuum system and vacuum pumping method for molten steel high-vacuum refining furnace

Abstract

The invention relates to a dry type mechanical vacuum system and a vacuum pumping method for a molten steel high-vacuum refining furnace. The dry type mechanical vacuum system for the molten steel high-vacuum refining furnace comprises the molten steel refining furnace (101), a flue gas cooling initial filtering device (1), a flue gas bag type fine filtering device (2) and a mechanical vacuum pumpset (3) which are connected in sequence. The vacuum pumping method for the molten steel high-vacuum refining furnace comprises the steps of starting water ring vacuum pumps (304), starting all sets of dry type mechanical vacuum pumps step by step, finally starting a screw type vacuum pump (303) and turning off the water ring vacuum pumps (304). According to the dry type mechanical vacuum system and the vacuum pumping method for the molten steel high-vacuum refining furnace, a filtering and cooling device of a novel structure is adopted, so that the temperature of high-temperature flue gas going into inlets of the vacuum pump set is greatly reduced to meet the use requirement of an RH furnace, and the operating life of the pump set is greatly prolonged. The failure rate is reduced. The high limiting vacuum degree can be reached within a short period of time. The requirement for smelting high-quality special steel is met.

Description

technical field [0001] The invention relates to a dry mechanical vacuum system and a vacuum pumping method for a molten steel high vacuum refining furnace, belonging to the high vacuum technical field for iron and steel metallurgy. Background technique [0002] The main purpose of vacuum refining of molten steel is to remove [H], [O], [C], [N] gases in steel, as well as to remove inclusions in steel, and to uniform the composition and temperature of molten steel. Refining furnaces with vacuum degassing function mainly include VD / VOD furnaces and RH furnaces. The vacuum degassing of these vacuum refining furnaces mainly uses steam jet pump vacuum degassing technology. [0003] In recent years, the new type dry mechanical vacuum pump vacuum degassing technology has been more and more applied in major domestic steel mills. Compared with the traditional steam jet pump vacuum degassing technology, it has the advantages of water saving, energy saving and stable pumping pressure. ...

AI Technical Summary

Problems solved by technology

[0006] In order to achieve a better degassing effect in the molten steel refining process, the ideal ultimate vacuum degree should reach 20~25Pa. The ultimate vacuum degree of the existing dry mechanical vacuum system can only reach 30Pa, and the inlet pressure of the vacuum unit is 18Pa. , the inlet pressure difference reached 12Pa

[0007] 2. When the screw pump is used as a backing pump, the failure rate is relatively high

[0008] Although the ultimate vacuum of the screw pump is relatively high when it is used as a backing pump, the particle size is limited by the filter accuracy of the dust bag to 10um, and the size of the particles in the gas is relatively large, resulting in a high failure rate of the screw pump.

[0009] 3. When the water ring pump is used as a backing pump, the ultimate vacuum degree is unstable

[0010] When the water ring pump is used as a backing pump, although the requirements for dust filtration accuracy are not high, the ultimate vacuum degree is changed by the change of the ambient temperature, and the temperature of the working fluid is unstable, which is easily affected by external factors, causing the ultimate vacuum degree to fluctuate up and down. Large changes, unable to meet the requirements of the vacuum refining process

[0011] 4. The gas inlet temperature of the vacuum pump is too high, resulting in a decrease in the efficiency of the vacuum pump and an increase in the failure rate

[0012] The gas inlet temperature of the vacuum pump is relatively high, especially in summer when the gas inlet temperature exceeds 100°C, even reaches 130°C, so the operating temperature of the vacuum pump also rises accordingly, which reduces the efficiency of the vacuum pump, and the high temperature accelerates the failure of the vacuum cooling oil, making the mechanical seal Accelerated wear, oil leakage and other failures

[0013] 5. If the temperature inside the dust collector is too high, it is easy to cause the bag burning phenomenon

[0014] Due to the high temperature of the gas, the phenomenon of burning the bag in the dust collector occurs from time to time, which poses a great safety hazard

[0015] 6. The effect is not good when applied to RH refining furnace vacuum degassing

[0016] The RH refining furnace is for continuous production, oxygen blowing and degassing, the temperature of the flue gas is higher, and the performance requirements of the vacuum system equipment are high. Due to the shortcomings of the above 1~5, the existing dry mechanical vacuum pump vacuum degassing technology cannot be compared Well applied to RH refining furnace vacuum degassing process

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