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

A vacuum system and mechanical vacuum pump technology, applied in the field of high vacuum for iron and steel metallurgy, can solve the problems of being easily affected by external factors, burning cloth bags of dust collectors, and rising operating temperature of vacuum pumps, so as to eliminate the phenomenon of burning cloth bags, ensure low failure rate, The effect of improving the operating life

Pending Publication Date: 2020-11-06

JIANGSU HUAXI ENERGY SAVING EQUIP CO LTD

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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 ...

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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.

Technology Topic

Pumping vacuumFlue gas +6

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Examples

Experimental program(1)

Example Embodiment

[0053] see Figures 1~4 The present invention relates to a dry mechanical vacuum system for a molten steel high-vacuum refining furnace. The dry mechanical vacuum system for a molten steel high-vacuum refining furnace comprises a molten steel refining furnace 101 and a flue gas cooling primary filter device which are connected in sequence. 1. The flue gas bag-type fine filter device 2 and the mechanical vacuum pump group 3; the molten steel refining furnace 101 is a VD furnace, a VOD furnace or a RH furnace;

[0054] The flue gas cooling and primary filtration device 1 includes a ash cleaning bin 1.1 arranged below, a heat exchange bin 1.2 set above, and a heat exchanger 1.3 set in the heat exchange bin 1.2, and the heat exchanger 1.3 is a welded type Finned tube heat exchanger; the ash cleaning bin 1.1 and the heat exchange bin 1.2 are connected up and down; the side of the ash cleaning bin 1.1 is provided with a flue gas inlet 201; the top side of the heat exchange bin 1.2 is provided with flue gas The outlet 202, the side of the heat exchange bin 1.2 is provided with the cooling water inlet 203 and the cooling water outlet 204 of the heat exchanger 1.3; the bottom of the flue gas cooling primary filtration device 1 is provided with an ash truck 205;

[0055] The flue gas bag-type fine filter device 2 includes a tank body 2.1 and a nitrogen cleaning device 2.2, an ultrafine filter device 2.3, a cyclone dust removal and cooling device 2.4 and a water-cooled ash hopper 2.5, which are arranged in sequence from top to bottom inside the tank body 2.1; The nitrogen cleaning device 2.2 includes a nitrogen bag 2.2.1 and a plurality of pulse cleaning valves 2.2.2 evenly arranged on the nitrogen bag 2.2.1; the ultrafine filtering device 2.3 includes a bag cage 2.3.1 and a bag cage 2.3 installed on the bag cage 2.3 The ultra-fine filter bag 2.3.2 in .1; the filtration accuracy of the ultra-fine filter bag 2.3.2 is not greater than 5 microns; the cyclone dust removal cooling device 2.4 and the water-cooled ash hopper 2.5 are provided with interconnected water-cooled walls 2.4 .1; the top side of the tank body 2.1 is provided with a flue gas outlet 202; the side of the tank body 2.1 at the cyclone dust removal and cooling device 2.4 is provided with a flue gas cyclone inlet 200 and a cooling water outlet 204; the water-cooled ash hopper 2.5 The side of the tank body 2.1 is provided with a cooling water inlet 203; the cooling water inlet 203 and the cooling water outlet 204 are connected through the water cooling wall 2.4.1; car 205;

[0056] The mechanical vacuum pump group 3 includes a first-stage vacuum pump group 3.1, a second-stage vacuum pump group 3.2, a third-stage vacuum pump group 3.3 and a fore-stage vacuum pump group 3.4 connected in sequence; the first-stage vacuum pump group 3.1 includes a plurality of parallel connected The ordinary Roots pump 301; the two-stage vacuum pump group 3.2 includes a plurality of air-cooled Roots pumps 302 connected in parallel; the three-stage vacuum pump group 3.3 includes a plurality of air-cooled Roots pumps 302 connected in parallel; the front stage The pump group 3.4 includes at least one screw vacuum pump 303 and a plurality of water ring vacuum pumps 304 connected in parallel;

[0057] Further, the dry mechanical vacuum system for the molten steel high vacuum refining furnace includes at least one set of mechanical vacuum pump sets 3, and multiple sets of mechanical vacuum pump sets 3 are connected in parallel;

[0058] Further, a furnace-side vacuum gauge 102, a furnace-side thermometer 103 and a furnace-side vent valve 104 are provided on the pipeline connecting the molten steel refining furnace 101 and the flue gas cooling primary filtration device 1;

[0059] A furnace-side thermometer 103 and a furnace-side cut-off valve 105 are provided on the pipeline connecting the flue gas cooling primary filter device 1 and the flue gas bag-type fine filter device 2;

[0060] A pump-side vacuum shut-off valve 106, a pump-side thermometer 107, a pump-side vacuum gauge 108 and a pump-side air-breaking valve 109 are provided on the pipeline connecting the flue gas bag-type fine filter device 2 and the mechanical vacuum pump set 3;

[0061] A pump port check valve 110 and a pump port cut-off valve 111 are provided on each vacuum pump air inlet pipeline of the fore-stage pump group 3.4.

[0062] The vacuuming method for the molten steel high-vacuum refining furnace is realized based on the above-mentioned dry mechanical vacuum system for the molten steel high-vacuum refining furnace, and the vacuuming steps of the vacuuming method are:

[0063] Step 1. Start the water ring vacuum pump: start the water ring vacuum pump 304 to evacuate, so that the vacuum degree drops from the atmospheric pressure to the preset value (10KPa~50KPa);

[0064] Step 2. Start the three-stage vacuum pump group: when the vacuum degree of the water ring vacuum pump 304 drops from the atmospheric pressure to the preset value (10KPa~50KPa), start each air-cooled Roots pump 302 of the three-stage vacuum pump group 3.3 one by one;

[0065] Step 3. Start the secondary vacuum pump group: when the vacuum degree of the tertiary vacuum pump group 3.3 reaches the preset value (10KPa~50KPa), start each air-cooled Roots pump 302 of the secondary vacuum pump group 3.3 one by one;

[0066] Step 4. Start the primary vacuum pump group: when the vacuum degree of the secondary vacuum pump group 3.2 reaches the preset value (10KPa~50KPa), start each ordinary Roots pump 301 of the primary vacuum pump group 3.1 one by one;

[0067] Step 5. Start the screw pump: when the vacuum degree of the mechanical vacuum pump group 3 reaches the preset value (10KPa~50KPa), start the screw vacuum pump 303 of the pre-stage vacuum pump group 3.4, and close the pump port on the inlet pipeline of the water ring vacuum pump 304 The valve 111 is shut off, and the operation of the water ring vacuum pump 304 is stopped.

[0068] When the vacuum system is working, the high-temperature flue gas sucked from the VD furnace, VOD furnace or RH furnace is cooled by the welded finned tube heat exchanger 1.3 in the flue gas cooling primary filter device 1 and the ash cleaning bin 1.1 collects the settled dust, wherein The welded finned tube heat exchanger 1.3 can flexibly configure the required heat exchange area according to the cooling requirements, and the heat exchange capacity is not limited by the length of the pipeline;

[0069] The flue gas after preliminary cooling and filtering continues to enter the cyclone dust removal and cooling device 2.4 of the flue gas bag-type fine filter device 2. While the flammable dust is settled, the flue gas exchanges heat with the water wall 2.4.1 to cool down to ensure that The flammable dust will not spontaneously combust at low temperature; the flue gas after cooling and dust removal continues to enter the ultra-fine filter bag 2.3.2 of the ultra-fine filter device 2.3, so that the dust larger than 5 microns is filtered out; The pressure difference between the flue gas inlet and outlet of the filter device 2 sets the start and stop of the pulse cleaning valve 2.2.2. When cleaning the dust, the front and rear valves of the flue gas bag type fine filter device 2 are closed and then cleaned with nitrogen to prevent the entry of outside air and prevent phosphorus-containing The gas ignites spontaneously in contact with air;

[0070] The air-cooled Roots pump 302 of the two-stage vacuum pump group 3.2 and the third-stage vacuum pump group 3.3 passes through the gas cooling cycle when the gas is compressed to do work, so that the gas at the pump inlet and outlet does not heat up rapidly, so that the system operates at low temperature, ensuring the efficiency and low temperature of the unit. failure rate;

[0071] Front-stage vacuum pump group 3.4 adopts screw vacuum pump 303 and water ring vacuum pump 304 in parallel. When pumping from atmospheric pressure, the gas flow changes from large to small. At the beginning, the extraction of atmospheric volume and large dust volume is carried out by the relatively rough water ring vacuum pump. 304 assumes the responsibility. When the gas flow rate is relatively small and the dust content is relatively low when entering the preset value (10KPa~50KPa), the screw vacuum pump 303 is responsible for it; this can not only avoid the harm of dust to the screw vacuum pump 303, but also make up for the water ring The two major defects of the low ultimate vacuum degree of the vacuum pump 304 and the excessively fast drop of the pumping speed of the water ring vacuum pump 304 under high vacuum have achieved the requirement of quickly reaching a stable high ultimate vacuum degree.

[0072] The vacuum system is actually used by a VD furnace in a special steel plant. It only runs for 15 minutes. The ultimate vacuum degree in the VD furnace reaches 20Pa, the inlet vacuum pressure of the vacuum pump unit is 14Pa, and the pressure difference is only 6Pa. The smelting quality of special steel has been greatly improved. Improve, greatly shorten the vacuum smelting time, and save the cost significantly; the temperature of the gas reaching the inlet of the vacuum pump group is 60 degrees, and it is less than 80 degrees in summer.

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Description & Claims & Application Information

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Technical method for rapid gas extraction standard reaching in broken soft, low-permeability and outburst coal seam by replacing roadways with holes

InactiveCN111594258AAvoid harmAvoid pollutionFluid removalDirectional drillingPhysicsCoal

Owner:XIAN RES INST OF CHINA COAL TECH& ENG GROUP CORP

Classification and recommendation of technical efficacy words

Avoid harm
Increased operating life

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

AI-Extracted Technical Summary

Problems solved by technology

Abstract

Image

Examples

Example Embodiment

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Description & Claims & Application Information

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