Low-temperature and low-pressure steam jet vacuum pump unit system

Abstract

The invention discloses a low-temperature and low-pressure steam jet vacuum pump unit system, comprising: a vacuum degassing device, a steam accumulator, a steam superheater, a first jet pump, a mixed gas inlet of which is connected to the gas outlet of the vacuum degassing device, a second jet pump, a mixed gas inlet of which is connected to the mixed gas outlet of the first jet pump, a first condenser, a primary side inlet of which is connected to the mixed gas outlet of the second jet pump, and a secondary side inlet and a secondary side outlet of which are both connected to a first circulation system, the first circulation system comprising: a first hot water tank, a low-temperature water tank, the first circulation system is used for: cooling the outlet water of the first condenser and re-entering the first condenser through the low-temperature water tank for circulation; the invention reduces the energy consumption of steam superheating, reduces the cost of the accumulator and the high-speed filter, and the combined application of the first circulation system and the low-pressure working steam system makes a qualitative leap in the steam jet vacuum pump system of the prior art.

Description

Technical Field

[0001] The invention belongs to the technical field of vacuum refining, and in particular relates to a low-temperature and low-pressure steam jet vacuum pump unit system. Background Art

[0002] The existing vacuum refining molten steel vacuum degassing process uses the principle that the gas in the molten steel is easy to escape under vacuum conditions, so that the harmful components such as hydrogen, oxygen, nitrogen and oxidized slag in the molten steel to be treated are reduced to a very small degree. This treatment method is called molten steel vacuum degassing or pure steel refining, such as vacuum degassing (VD method), vacuum cycle degassing (RH method), vacuum oxygen blowing degassing (VOD method), vacuum casting (VC method), etc., which occupies a very important position in the current production of special steel and high-quality steel. my country is a large steel country but not a strong steel country. The main gap is that the output and quality of special steel and high-quality steel and the purity of molten steel components are low. In this refining process, the steam jet vacuum pump system is the decisive factor in ensuring the purity of molten steel production with guaranteed quality and quantity. It is urgent to ensure the vacuum pump's suction volume and vacuum capacity while minimizing the consumption of steam and cooling water, reducing water pollution, and reducing the price of the vacuum pump system.

[0003] Under the stirring of inert gas argon, harmful gases such as hydrogen, oxygen, and nitrogen escape from the molten steel in the vacuum degassing device, are sucked by high-speed steam jets and discharged into the atmosphere with step-by-step pressure increase. The content of hydrogen, oxygen, and nitrogen in the vacuum degassing molten steel must be lower than 2ppm, 10ppm, and 30ppm respectively. Excessive harmful gases seriously affect the quality of steel.

[0004] In the prior art, in order to ensure the operation of the molten steel vacuum degassing device, a steam jet vacuum pump unit with a large suction capacity must be set up, which consumes a large amount of superheated steam and cooling water. Therefore, a steam accumulator is set to ensure steam supply, a full steam superheater is set to ensure the quality of superheated steam, and a high-speed filter is set to prevent water pollution.

[0005] At present, the steam jet vacuum pump system used in the steel liquid vacuum degassing equipment at home and abroad is as follows Figure 1As shown, molten steel at about 1600℃ enters the vacuum degassing device, and high-pressure argon is blown into the bottom to make the molten steel churn continuously. Under vacuum conditions, the oxide inclusions in the molten steel float on the liquid surface and are discharged together with the slag, while harmful gases escape from the molten steel and enter the first condenser through the connecting pipeline through the first jet pump, the second jet pump, and the third jet pump. The working steam of the three jet pumps at the front stage is condensed by the cooling water on the top of the condenser and discharged into the hot water tank through the drain pipe. The non-condensable gas is drawn into the fourth jet pump and the fifth jet pump and enters the second condenser, and the condensable gas is condensed by the cooling water on the top of the second condenser and discharged into the hot water tank through the drain pipe. The non-condensable gas is drawn into the sixth jet pump and the seventh jet pump to enter the third condenser and discharged into the atmosphere. The purity of the molten steel treated by vacuum degassing is greatly improved, and its strength and toughness are much better than ordinary steel in various physical and chemical indicators.

[0006] In order to save energy, reduce emissions and meet the needs of negative energy steelmaking, the electric furnace and converter in the previous process are equipped with waste heat recovery devices. The produced steam is stored in the accumulator, and a steam superheater and a steam drum are installed at the back to send it to the jet pump. The condenser cooling water carries a lot of dust during the condensation process. Generally, a large high-speed filter is installed to remove dust and reduce cooling water pollution. For example, the 120T-RH vacuum degassing device has a steam consumption of 25,400 kg / h and a cooling water consumption of 1,200 t / h, which makes the required steam accumulator, steam superheater and high-speed filter expensive and requires huge investment.

[0007] In summary, the existing production system has the following problems:

[0008] 1. Six steam accumulators are required, each with a capacity of 200 cubic meters, an output steam pressure of 1.0-1.5MPa, and an output steam volume of 25,400kg. The accumulators occupy a large area, have high energy consumption, and require a large amount of steam;

[0009] 2. All steam entering the vacuum jet pump is heated by setting a pre-steam superheater to obtain superheated steam, resulting in high energy consumption;

[0010] 3. By setting up a high-speed filter, the outlet water of the condenser is separated to produce turbid circulating water, which is highly polluting. In addition, the cost of the high-speed filter is high, and each high-speed filter costs about 300,000 yuan;

[0011] 4. Existing condensers all use normal temperature water of about 35 degrees, which puts a heavy burden on the cooling system and causes high energy consumption. Summary of the invention

[0012] The purpose of the present invention is to provide a low-temperature and low-pressure steam jet vacuum pump unit system to solve the problems of large steam consumption, high energy consumption, high cost of using high-speed filters and heavy burden on the cooling system of the vacuum pump unit system.

[0013] The present invention adopts the following technical scheme: a low-temperature and low-pressure steam jet vacuum pump unit system, comprising:

[0014] The vacuum degassing device has a gas outlet and contains molten steel.

[0015] The steam accumulator, whose inlet is connected to the steam source, is used to store high-temperature and high-pressure steam.

[0016] The steam superheater, whose inlet is connected to the outlet of the steam accumulator, is used to heat the steam to produce superheated steam.

[0017] The first jet pump has a water vapor port, a mixed gas inlet, and a mixed gas outlet.

[0018] Its steam outlet is connected to the outlet of the steam superheater.

[0019] The mixed gas inlet is connected to the gas outlet of the vacuum degassing device.

[0020] The second jet pump has a water vapor port, a mixed gas inlet, and a mixed gas outlet.

[0021] Its water vapor port is connected to the outlet of the steam accumulator.

[0022] Its mixed gas inlet is connected to the mixed gas outlet of the first jet pump,

[0023] The first condenser has a primary side inlet, a primary side outlet, a secondary side inlet, and a secondary side outlet, and is used to condense and unload the condensable gas in the mixed gas.

[0024] Its primary side inlet is connected to the mixed gas outlet of the second jet pump.

[0025] Its secondary side inlet and secondary side outlet are both connected to the first circulation system.

[0026] The first circulation system includes:

[0027] The first hot water tank has an inlet connected to the secondary side outlet of the first condenser,

[0028] The low-temperature water tank has an inlet connected to the outlet of the first hot water tank through the refrigeration equipment, and its outlet is connected to the secondary side inlet of the first condenser.

[0029] The first circulation system is used to cool the outlet water of the first condenser and then re-enter the first condenser through the low-temperature water tank for circulation.

[0030] Furthermore, it also includes:

[0031] The third jet pump has a water vapor port, a mixed gas inlet, and a mixed gas outlet.

[0032] Its water vapor port is connected to the outlet of the steam accumulator.

[0033] Its mixed gas inlet is connected to the primary side outlet of the first condenser.

[0034] The second condenser has a primary side inlet, a primary side outlet, a secondary side inlet, and a secondary side outlet, and is used to condense and unload the condensable gas in the mixed gas.

[0035] Its primary side inlet is connected to the mixed gas outlet of the third jet pump.

[0036] Its secondary side inlet and secondary side outlet are both connected to the second circulation system.

[0037] The fourth jet pump has a water vapor port, a mixed gas inlet, and a mixed gas outlet.

[0038] Its water vapor port is connected to the outlet of the steam accumulator.

[0039] Its mixed gas inlet is connected to the primary side outlet of the second condenser.

[0040] The third condenser has a primary side inlet, a primary side outlet, a secondary side inlet, and a secondary side outlet, and is used to condense and unload the condensable gas in the mixed gas.

[0041] Its primary side inlet is connected to the mixed gas outlet of the fourth jet pump.

[0042] Its secondary side inlet and secondary side outlet are both connected to the second circulation system.

[0043] The system is composed of a first jet pump, a second jet pump, a first condenser, a third jet pump, a second condenser, a fourth jet pump, and a third condenser, which cooperate with each other to form a maintenance system, thereby maintaining the vacuum degree in the vacuum degassing device ≤67Pa.

[0044] Further, the second circulation system comprises:

[0045] The second hot water tank has an inlet connected to the secondary side outlets of the second condenser and the third condenser.

[0046] The cooling tower has an inlet connected to the outlet of the second hot water tank, and an outlet connected to the secondary side inlets of the second condenser and the third condenser through a water separator, so as to circulate the pollution-free water.

[0047] Further, the second circulation system comprises:

[0048] The second hot water tank has an inlet connected to the secondary side outlets of the second condenser and the third condenser.

[0049] The heat exchanger has a primary side inlet, a primary side outlet, a secondary side inlet, and a secondary side outlet.

[0050] Its primary side inlet is connected to the outlet of the second hot water tank.

[0051] Its primary side outlet is connected to the secondary side inlet of the second condenser and the third condenser through the water separator.

[0052] The cooling tower has an inlet connected to the secondary outlets on both sides of the heat exchanger, and an outlet connected to the secondary inlets on both sides of the heat exchanger, and is used to circulate polluted water.

[0053] Furthermore, the primary side inlet of the second condenser is also connected to the primary side outlet of the first condenser through a fast vacuum pipeline.

[0054] Also includes:

[0055] The fifth jet pump has a water vapor port, a mixed gas inlet, and a mixed gas outlet.

[0056] Its water vapor port is connected to the outlet of the steam accumulator.

[0057] Its mixed gas inlet is connected to the primary side outlet of the second condenser.

[0058] Its mixed gas outlet is connected to the primary side inlet of the third condenser.

[0059] The system is composed of a first jet pump, a second jet pump, a first condenser, a third jet pump, a second condenser, a fourth jet pump, and a third condenser, which cooperate with each other to form a maintenance system, and the first jet pump, the second jet pump, the first condenser, a fast vacuum pipeline, and a fifth jet pump cooperate with each other to form a starting system, and the vacuum degree of the vacuum degassing device is reduced from atmospheric pressure to 67Pa in 3-5 minutes, and then the vacuum conductance between the first condenser and the second condenser is increased during oxygen degassing.

[0060] Furthermore, a plurality of baffles are provided in the low-temperature water tank, each baffle is vertically arranged, the lower end of which is fixedly connected to the bottom of the low-temperature water tank, and the upper end thereof extends upward, and divides the low-temperature water tank into a plurality of overflow cavities, and the plurality of overflow cavities are used to precipitate dust. The inlet of the low-temperature water tank is connected with the outlet of the first hot water tank through a refrigeration device, and is used to cool the hot water in the first hot water tank through the refrigeration device and then transport it to the low-temperature water tank, and then enter the first condenser for circulation.

[0061] Further, the primary side outlet of the third condenser is connected to a front-stage vacuum pump group, which includes a first vacuum circulation pump, a second vacuum circulation pump, and a third vacuum circulation pump which are connected in sequence and are all connected to the outside, and the front-stage vacuum pump group is used to provide pre-vacuum for the fourth jet pump and the fifth jet pump;

[0062] The fore vacuum pump unit has a water vapor inlet, a gas outlet, and a cooling water inlet.

[0063] Its water vapor inlet is connected to the primary side outlet of the third condenser.

[0064] Its gas outlet is connected to the outside world.

[0065] The cooling water inlet is connected with the outlet of the low-temperature water tank.

[0066] The beneficial effects of the present invention are:

[0067] 1. The present invention adopts low-temperature water and low-pressure steam to drive the steam jet vacuum pump, which can reduce the steam and cooling water consumption by 30-60%, eliminate the full steam superheater, and only set a trace steam superheater for the first jet pump, eliminate the high-speed filter, greatly reduce the cost, and use the heat exchanger and low-temperature water tank to isolate the turbid circulating water and the clean circulating water to eliminate water pollution; the water in the low-temperature water tank is recycled and recycled through the first condenser, saving the cost of equipment;

[0068] 2. The present invention is mainly used in the fields of steel liquid vacuum degassing device, aerospace high-altitude simulation, wind tunnel, non-ferrous metal refining, molecular distillation, chemical vapor deposition, etc., especially in the application of steel liquid vacuum degassing device, it will greatly reduce the consumption of steam and cooling water, reduce the materials of manufacturing equipment, reduce investment costs, reduce carbon dioxide emissions, and obtain dual benefits of enterprise and social effects;

[0069] 3. The present invention adopts 0.3-0.6MPa.G low-pressure working steam, which increases the storage capacity of the steam accumulator by 3 times, and reduces six 200m³ accumulators to two; greatly reduces energy consumption and saves costs; the present invention changes the full 25400kg / h steam superheater to only provide superheated steam for the first jet pump 1200kg / h trace steam, saving more than 90% of the heating steam superheating energy consumption. Theoretically, the jet pump with a suction pressure of more than 200Pa can use saturated steam with a humidity of 95%, which can ensure the required vacuum index, and the suction pressure of the second jet pump exceeds 400Pa;

[0070] 4. The present invention uses a heat exchanger to isolate the jet pump condensed turbid circulating water and the clean circulating water of the cooling tower; the present invention uses a labyrinth overflow design of the low-temperature water tank partition wall to regularly precipitate dust, and the effect meets the water requirements of the jet pump;

[0071] 5. The present invention sets a first circulation system to reduce the working temperature of the first condenser to about 10°C, and the second circulation system ensures that the working temperature of the second condenser and the third condenser is about 35°C; the first condenser uses low-temperature water of 1-20 degrees for condensation, and the other condensers use normal temperature water for cooling circulation, which reduces energy consumption. Only 10500kg / h of low-pressure steam is needed to maintain the vacuum degree of the vacuum degassing device at 67Pa, which greatly reduces energy consumption and saves costs; the front-stage vacuum pump group of the present invention requires the circulating cooling water temperature to be 15°C. The normal temperature water system of the prior art cannot meet the requirement, making its vacuum performance unstable. The present invention can ensure the water requirement of 15°C and the vacuum performance requirement;

[0072] 6. The present invention reduces the energy consumption of steam superheating, reduces the cost of heat accumulator and high-speed filter, and the combined application of the first circulation system and the low-pressure working steam system makes a qualitative leap in the steam jet vacuum pump system of the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0073] Figure 1 It is a schematic diagram of the system of the present invention;

[0074] Figure 2 This is a system schematic diagram of the prior art in Example 1 of the present invention.

[0075] Among them: 1. Vacuum degassing device; 2. Steam superheater; 3. First jet pump; 4. Second jet pump; 5. First condenser; 6. Third jet pump; 7. Second condenser; 8. Fourth jet pump; 9. Fifth jet pump; 10. Third condenser; 11. Fore vacuum pump group; 12. Cooling tower; 13. Heat exchanger; 14. Second hot water tank; 15. Fast vacuum pipeline; 16. First hot water tank; 17. Refrigeration equipment; 18. Low-temperature water tank; 19. Steam accumulator; 20. Steam source; 21. Steam drum; 22. Water drum. DETAILED DESCRIPTION

[0076] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0077] The present invention discloses a low temperature and low pressure steam jet vacuum pump unit system, such as Figure 1 As shown, it includes: a vacuum degassing device 1, a steam accumulator 19, a steam superheater 2, a first jet pump 3, a second jet pump 4, and a first condenser 5.

[0078] The vacuum degassing device 1 has an outlet. Molten steel is stored in the vacuum degassing device 1. The inlet of the steam accumulator 19 is connected to the steam source 20. The steam accumulator 19 is used to store high-temperature and high-pressure steam.

[0079] The inlet of the steam superheater 2 is connected to the outlet of the steam accumulator 19, and the steam superheater 2 is used to heat the steam to generate superheated steam.

[0080] The first jet pump 3 has a steam port, a mixed gas inlet, and a mixed gas outlet. The steam port of the first jet pump 3 is connected to the outlet of the steam superheater 2 , and the mixed gas inlet of the first jet pump 3 is connected to the gas outlet of the vacuum degassing device 1 .

[0081] The second jet pump 4 has a steam port, a mixed gas inlet, and a mixed gas outlet. The steam port of the second jet pump 4 is connected to the outlet of the steam accumulator 19 , and the mixed gas inlet of the second jet pump 4 is connected to the mixed gas outlet of the first jet pump 3 .

[0082] The first condenser 5 has a primary side inlet, a primary side outlet, a secondary side inlet, and a secondary side outlet. The first condenser 5 is used to condense and unload the condensable gas in the mixed gas in the vacuum degassing device 1. The primary side inlet of the first condenser 5 is connected to the mixed gas outlet of the second jet pump 4, and the secondary side inlet and the secondary side outlet of the first condenser 5 are both connected to the first circulation system.

[0083] The first circulation system includes: a first hot water tank 16 and a low-temperature water tank 18. The inlet of the first hot water tank 16 is connected to the secondary side outlet of the first condenser 5. The inlet of the low-temperature water tank 18 is connected to the outlet of the first hot water tank 16 through the refrigeration equipment 17. The outlet of the low-temperature water tank 18 is connected to the secondary side inlet of the first condenser 5.

[0084] The first circulation system is used to cool the outlet water of the first condenser 5 and then re-enter the first condenser 5 through the low-temperature water tank 18 for circulation.

[0085] The present invention also includes: a third jet pump 6, a second condenser 7, a fourth jet pump 8, and a third condenser 10. The third jet pump 6 has a water vapor port, a mixed gas inlet, and a mixed gas outlet. The water vapor port of the third jet pump 6 is connected to the outlet of the steam accumulator 19, and the mixed gas inlet of the third jet pump 6 is connected to the primary side outlet of the first condenser 5.

[0086] The second condenser 7 has a primary side inlet, a primary side outlet, a secondary side inlet, and a secondary side outlet, and the second condenser 7 is used to condense and unload the condensable gas in the mixed gas in the vacuum degassing device 1. The primary side inlet of the second condenser 7 is connected to the mixed gas outlet of the third jet pump 6, and the secondary side inlet and the secondary side outlet of the second condenser 7 are both connected to the second circulation system.

[0087] The fourth jet pump 8 has a steam port, a mixed gas inlet, and a mixed gas outlet. The steam port of the fourth jet pump 8 is connected to the outlet of the steam accumulator 19 , and the mixed gas inlet of the fourth jet pump 8 is connected to the primary side outlet of the second condenser 7 .

[0088] The third condenser 10 has a primary side inlet, a primary side outlet, a secondary side inlet, and a secondary side outlet. The third condenser 10 is used to condense and unload the condensable gas in the mixed gas in the vacuum degassing device 1. The primary side inlet of the third condenser 10 is connected to the mixed gas outlet of the fourth jet pump 8, and the secondary side inlet and the secondary side outlet of the third condenser 10 are both connected to the second circulation system. The system is composed of the first jet pump 3, the second jet pump 4, the first condenser 5, the third jet pump 6, the second condenser 7, the fourth jet pump 8, and the third condenser 10, which cooperate with each other to form a maintenance system, thereby maintaining the vacuum degree in the vacuum degassing device 1 ≤67Pa.

[0089] In the first case:

[0090] The second circulation system includes: a second hot water tank 14 and a cooling tower 12. The inlet of the second hot water tank 14 is connected to the secondary side outlets of the second condenser 7 and the third condenser 10. The inlet of the cooling tower 12 is connected to the outlet of the second hot water tank 14. The outlet of the cooling tower 12 is connected to the secondary side inlets of the second condenser 7 and the third condenser 10 through a water distribution bag 22. The cooling tower 12 is used to recycle unpolluted water.

[0091] In the second case:

[0092] The second circulation system includes: a second hot water tank 14, a heat exchanger 13, and a cooling tower 12. The inlet of the second hot water tank 14 is connected to the secondary side outlets of the second condenser 7 and the third condenser 10. The heat exchanger 13 has a primary side inlet, a primary side outlet, a secondary side inlet, and a secondary side outlet. The primary side inlet of the heat exchanger 13 is connected to the outlet of the second hot water tank 14. The primary side outlet of the heat exchanger 13 is connected to the secondary side inlets of the second condenser 7 and the third condenser 10 through a water separation bag 22. The inlet of the cooling tower 12 is connected to the secondary outlets on both sides of the heat exchanger 13. The outlet of the cooling tower 12 is connected to the secondary inlets on both sides of the heat exchanger 13. The cooling tower 12 is used to recycle polluted water.

[0093] The primary side inlet of the second condenser 7 is also connected to the primary side outlet of the first condenser 5 through the fast vacuum pipeline 15. The present invention also includes: a fifth jet pump 9, the fifth jet pump 9 has a water vapor port, a mixed gas inlet, and a mixed gas outlet. The water vapor port of the fifth jet pump 9 is connected to the outlet of the steam accumulator 19, the mixed gas inlet of the fifth jet pump 9 is connected to the primary side outlet of the second condenser 7, and the mixed gas outlet of the fifth jet pump 9 is connected to the primary side inlet of the third condenser 10. The system is composed of the first jet pump 3, the second jet pump 4, the first condenser 5, the third jet pump 6, the second condenser 7, the fourth jet pump 8, and the third condenser 10, which cooperate with each other to form a maintenance system, and the first jet pump 3, the second jet pump 4, the first condenser 5, the fast vacuum pipeline 15, and the fifth jet pump 9 cooperate with each other to form a starting system, and the vacuum degree of the vacuum degassing device 1 is reduced from atmospheric pressure to 67Pa in 3-5 minutes, and then when blowing oxygen for degassing, the vacuum conductance between the first condenser 5 and the second condenser 7 is increased.

[0094] A plurality of baffles are arranged in the low-temperature water tank 18, each baffle is arranged vertically, the lower end of each baffle is fixedly connected to the bottom of the low-temperature water tank 18, the upper end of each baffle extends upward, and divides the low-temperature water tank 18 into a plurality of overflow cavities, and the plurality of overflow cavities are used to precipitate dust. The inlet of the low-temperature water tank 18 is connected with the outlet of the first hot water tank 16 through the refrigeration equipment 17, which is used to refrigerate the hot water in the first hot water tank 16 through the refrigeration equipment 17 and then transport it to the low-temperature water tank 18, and then enter the first condenser 5 for recycling.

[0095] The primary side outlet of the third condenser 10 is connected to the front-stage vacuum pump group 11, which includes a first vacuum circulation pump, a second vacuum circulation pump, and a third vacuum circulation pump which are connected in sequence and are all connected to the outside. The front-stage vacuum pump group 11 is used to provide pre-vacuum for the fourth jet pump 8 and the fifth jet pump 9.

[0096] The front vacuum pump group 11 has a water vapor inlet, a gas outlet, and a cooling water inlet. The water vapor inlet of the front vacuum pump group 11 is connected to the primary side outlet of the third condenser 10, the gas outlet of the front vacuum pump group 11 is connected to the outside, and the cooling water inlet of the front vacuum pump group 11 is connected to the outlet of the low-temperature water tank 18.

[0097] The molten steel enters the vacuum degassing device 1, and under the stirring of high-pressure argon gas, the oxide slag inclusions float up and are discharged, and the harmful gases escape and become waste gas.

[0098] The steam from the steam source 20 is stored in the steam accumulator 19 and enters each jet pump through the steam drum 21. The steam entering the first jet pump 3 needs to be heated by the steam superheater 2 to become superheated steam before entering. The steam drives the exhaust gas to enter the first jet pump 3 and the second jet pump 4 to enter the first condenser 5.

[0099] The 1-20℃ low-temperature water from the low-temperature water tank 18 enters the first condenser 5, condenses the condensable gas therein and discharges it into the first hot water tank 16 and is sent to the refrigeration equipment 17 for cooling, enters the low-temperature water tank 18, and then is sent to the first condenser 5 to complete the low-temperature water condensation cycle.

[0100] The non-condensable gas enters the third jet pump 6, the fast vacuum pipeline 15, the second condenser 7, the fourth jet pump 8, the fifth jet pump 9, the third condenser 10 in turn, and is discharged into the atmosphere through the front vacuum pump group 11.

[0101] The condensable gas is condensed by the 20-40°C normal temperature water at the top of the second condenser 7 and the third condenser 10 and discharged into the second hot water tank 14 , and then sent to the cooling tower 12 for cooling and pumped into the water distribution bag 22 to be sent to the second condenser 7 and the third condenser 10 .

[0102] The low-temperature water in the low-temperature water tank 18 enters the working cycle of the front-stage vacuum pump group 11 and is discharged into the first hot water tank 16, which meets the water temperature requirement of 15°C, improves the vacuum degree and exhaust capacity, and avoids cavitation damage at high water temperature.

[0103] In the low-temperature water state, the vacuum conductance of the third jet pump 6 is 1 / 3 of that in the normal-temperature water state, which cannot meet the vacuum conductance requirements of rapid startup and high-intensity oxygen blowing period. A fast vacuum pipeline 15 is set, and its vacuum conductance is increased by 2-5 times to meet the vacuum conductance requirements of large exhaust volume.

[0104] The present invention reduces steam consumption and steam pressure, which will lead to a significant reduction or even elimination of steam accumulators, steam superheaters and high-speed filters, thereby greatly reducing energy consumption, pollution and operating costs of the steam jet vacuum pump system. Example

[0105] A famous steel enterprise's 120T-RH molten steel vacuum degassing device introduced a German steam jet vacuum pump, with a molten steel processing capacity of 120 tons / furnace, a pumping capacity of 700kg / h at 67Pa, and a time of 3-4min for pumping 250m³ volume from atmospheric pressure to 67Pa, a steam consumption of 25.4t / h, a steam pressure of 1.3MPa.G, and a turbid ring cooling water consumption of 1300m³ / h. The annual production of special steel is 600,000 tons, and the enterprise has five similar production lines.

[0106] Figure 2It is a structural schematic diagram of the prior art: wherein 1-1 is a vacuum degassing device; 1-2 is a first jet pump; 1-3 is a second jet pump; 1-4 is a third jet pump; 1-5 is a first condenser; 1-6 is a fourth jet pump; 1-7 is a fifth jet pump; 1-8 is a second condenser; 1-9 is a sixth jet pump; 1-10 is a seventh jet pump; 1-11 is a third condenser; 1-12 is a cooling tower; 1-13 is a cold water tank; 1-14 is a high-speed filter; 1-15 is a hot water tank; 1-16 is a steam accumulator; 1-17 is a steam source; 1-18 is a steam superheater; 1-19 is a steam drum; 1-20 is a water drum.

[0107] By setting up 6 200m³ steam accumulators 1-16, with a steam charging pressure of 1.8MPa.G and a steam discharge pressure of 1.4MPa.G, 30 tons of steam can be stored for use. In addition, a steam superheater 1-18 is set at the rear side of the steam accumulator 1-16 to heat all 25.4t / h of steam and output 25.4t / h of superheated steam. The turbid circulating water is treated and recycled by setting up three high-speed filters 1-14 with a price of RMB 300,000 / unit. Three condensers, three booster jet pumps and four jet pumps are set up, with a total construction cost of more than RMB 20 million. The system consumes about 36kg / h of high-pressure superheated steam to extract 1kg of dry air in the vacuum degassing device 1-1.

[0108]

[0109]

[0110] After the improvement of the system of the present invention, as shown in Table 1 and Table 2, the working steam pressure is 0.3-0.6MP.G, the consumption is 10.5t / h, and only two 200m³ steam accumulators 19 are needed to meet the needs. Under the premise of the new design theory that only the first jet pump 3 needs superheated steam, only the 1.2t / h steam input to the first jet pump 3 needs to be heated, and the heating energy is reduced by about 90%. The saturated steam used by the remaining six jet pumps comes from the steam accumulator 19 and does not need to be heated.

[0111] Secondly, only the cooling water entering the first condenser 5 is subjected to low-temperature treatment through the refrigeration equipment 17, so that low-temperature water of 1-20 degrees enters the first condenser 5, while the second condenser 7 and the third condenser 10 only use room temperature water. The system only consumes 15kg / h of saturated steam to extract 1kg of dry air in the vacuum degassing device 1.

[0112] In addition, after the low-temperature water of the first condenser 5 is washed, there is little dust entering the normal temperature water system, and the high-speed filter can be eliminated by only setting up a heat exchanger 13 to isolate the turbid circulating water and the clean circulating water of the cooling tower 12. As long as the sedimentation tank is cleaned regularly, the turbid circulating water can be circulated internally, avoiding the pollution of the clean circulating water.

[0113] The most important thing about the present invention is to design the first circulation system and the second circulation system and to use low-pressure working steam, thereby achieving the purpose of low steam consumption and low cost under the premise of ensuring vacuum performance.

[0114] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A steam jet vacuum pump unit system of low temperature and low pressure type, characterized in that, it includes: A vacuum degassing device (1) with an air outlet, in which molten steel is stored, A steam accumulator (19), whose inlet is connected to a steam source (20) for storing high-temperature and high-pressure steam; A steam superheater (2), whose inlet is connected to the outlet of the steam accumulator (19) for heating the steam to generate superheated steam, A first ejector pump (3) with a steam port, a mixed gas inlet, and a mixed gas outlet, its steam port is connected to the outlet of the steam superheater (2), its mixed gas inlet is connected to the air outlet of the vacuum degassing device (1), A second ejector pump (4) with a steam port, a mixed gas inlet, and a mixed gas outlet, its steam port is connected to the outlet of the steam accumulator (19), its mixed gas inlet is connected to the mixed gas outlet of the first ejector pump (3), A first condenser (5) with a primary side inlet, a primary side outlet, a secondary side inlet, and a secondary side outlet for condensing and unloading the condensable gas in the mixed gas, its primary side inlet is connected to the mixed gas outlet of the second ejector pump (4), its secondary side inlet and secondary side outlet are both connected to the first circulation system, The first circulation system includes: A first hot water tank (16), whose inlet is connected to the secondary side outlet of the first condenser (5), A low-temperature water tank (18), whose inlet is connected to the outlet of the first hot water tank (16) through a refrigeration device (17), and whose outlet is connected to the secondary side inlet of the first condenser (5), The first circulation system is used for: after cooling the water discharged from the first condenser (5), it re-enters the first condenser (5) through the low-temperature water tank (18) for recycling.

2. The steam jet vacuum pump unit system of low temperature and low pressure type according to claim 1, characterized in that, it further includes: A third ejector pump (6) with a steam port, a mixed gas inlet, and a mixed gas outlet, its steam port is connected to the outlet of the steam accumulator (19), its mixed gas inlet is connected to the primary side outlet of the first condenser (5), A second condenser (7) with a primary side inlet, a primary side outlet, a secondary side inlet, and a secondary side outlet for condensing and unloading the condensable gas in the mixed gas, its primary side inlet is connected to the mixed gas outlet of the third ejector pump (6), its secondary side inlet and secondary side outlet are both connected to the second circulation system, A fourth ejector pump (8) with a steam port, a mixed gas inlet, and a mixed gas outlet, its steam port is connected to the outlet of the steam accumulator (19), its mixed gas inlet is connected to the primary side outlet of the second condenser (7), A third condenser (10) with a primary side inlet, a primary side outlet, a secondary side inlet, and a secondary side outlet for condensing and unloading the condensable gas in the mixed gas, its primary side inlet is connected to the mixed gas outlet of the fourth ejector pump (8), its secondary side inlet and secondary side outlet are both connected to the second circulation system, The first ejector pump (3), the second ejector pump (4), the first condenser (5), the third ejector pump (6), the second condenser (7), the fourth ejector pump (8), and the third condenser (10) cooperate with each other to form a maintenance system, thereby maintaining the vacuum degree in the vacuum degassing device (1) ≤ 67 Pa.

3. The low-temperature and low-pressure steam jet vacuum pump unit system according to claim 2, characterized in that, the second circulation system includes: a second hot water tank (14), whose inlet is connected to the secondary side outlets of the second condenser (7) and the third condenser (10), a cooling tower (12), whose inlet is connected to the outlet of the second hot water tank (14), and whose outlet is respectively connected to the secondary side inlets of the second condenser (7) and the third condenser (10) through a water distribution header (22) for recycling the pollution-free water.

4. The low-temperature and low-pressure steam jet vacuum pump unit system according to claim 2, characterized in that, the second circulation system includes: a second hot water tank (14), whose inlet is connected to the secondary side outlets of the second condenser (7) and the third condenser (10), a heat exchanger (13) having a primary side inlet, a primary side outlet, a secondary side inlet, and a secondary side outlet, whose primary side inlet is connected to the outlet of the second hot water tank (14), whose primary side outlet is connected to the secondary side inlets of the second condenser (7) and the third condenser (10) through a water distribution header (22), a cooling tower (12), whose inlet is connected to the secondary side outlet of the heat exchanger (13), and whose outlet is connected to the secondary side inlet of the heat exchanger (13) for recycling the polluted water.

5. The low-temperature and low-pressure steam jet vacuum pump unit system according to claim 3 or 4, characterized in that, the primary side inlet of the second condenser (7) is further connected to the primary side outlet of the first condenser (5) through a quick vacuum pipeline (15), further comprising: a fifth ejector pump (9) having a steam port, a mixed gas inlet, and a mixed gas outlet, whose steam port is connected to the outlet of the steam accumulator (19), whose mixed gas inlet is connected to the primary side outlet of the second condenser (7), whose mixed gas outlet is connected to the primary side inlet of the third condenser (10), The first ejector pump (3), the second ejector pump (4), the first condenser (5), the third ejector pump (6), the second condenser (7), the fourth ejector pump (8), and the third condenser (10) cooperate with each other to form a maintenance system, and the first ejector pump (3), the second ejector pump (4), the first condenser (5), the quick vacuum pipeline (15), and the fifth ejector pump (9) cooperate with each other to form a startup system, and reduce the vacuum degree of the vacuum degassing device (1) from atmospheric pressure to 67 Pa within 3 - 5 minutes, thereby increasing the vacuum conductance between the first condenser (5) and the second condenser (7) during oxygen blowing degassing.

6. The low-temperature and low-pressure steam jet vacuum pump unit system according to claim 5, characterized in that, A plurality of baffles are arranged inside the low-temperature water tank (18). Each baffle is arranged vertically, with its lower end fixedly connected to the bottom of the low-temperature water tank (18), and its upper end extending upward, dividing the low-temperature water tank (18) into a plurality of overflow cavities. The plurality of overflow cavities are used for sedimenting dust. The inlet of the low-temperature water tank (18) is connected to the outlet of the first hot water tank (16) through a refrigeration device (17), so as to refrigerate the hot water in the first hot water tank (16) through the refrigeration device (17) and then transport it to the low-temperature water tank (18), and then enter the first condenser (5) for recycling.

7. The steam jet vacuum pump unit system of the low-temperature and low-pressure type according to claim 6, characterized in that the primary side outlet of the third condenser (10) is connected to the pre-stage vacuum pump group (11). The pre-stage vacuum pump group (11) includes a first vacuum circulation pump, a second vacuum circulation pump, and a third vacuum circulation pump connected in sequence, and all are connected to the outside. The pre-stage vacuum pump group (11) is used to provide pre-vacuum for the fourth ejector pump (8) and the fifth ejector pump (9); the pre-stage vacuum pump group (11) is provided with a water vapor inlet, a gas outlet, and a cooling water inlet, its water vapor inlet is connected to the primary side outlet of the third condenser (10), its gas outlet is connected to the outside, and its cooling water inlet is connected to the outlet of the low-temperature water tank (18).

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