CN104593547A - Vacuumizing control method and system of VD mechanical pump - Google Patents
Vacuumizing control method and system of VD mechanical pump Download PDFInfo
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- CN104593547A CN104593547A CN201510015898.4A CN201510015898A CN104593547A CN 104593547 A CN104593547 A CN 104593547A CN 201510015898 A CN201510015898 A CN 201510015898A CN 104593547 A CN104593547 A CN 104593547A
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- 238000000034 method Methods 0.000 title claims abstract description 107
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 254
- 239000010959 steel Substances 0.000 claims abstract description 254
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 410
- 229910052786 argon Inorganic materials 0.000 claims description 205
- 238000005086 pumping Methods 0.000 claims description 103
- 238000007664 blowing Methods 0.000 claims description 53
- 239000007789 gas Substances 0.000 claims description 44
- 239000001257 hydrogen Substances 0.000 claims description 38
- 229910052739 hydrogen Inorganic materials 0.000 claims description 38
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 36
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 33
- 238000001514 detection method Methods 0.000 claims description 24
- 238000009489 vacuum treatment Methods 0.000 claims description 21
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 18
- 239000001301 oxygen Substances 0.000 claims description 18
- 229910052760 oxygen Inorganic materials 0.000 claims description 18
- 229910052757 nitrogen Inorganic materials 0.000 claims description 17
- 230000003749 cleanliness Effects 0.000 abstract description 9
- 239000012535 impurity Substances 0.000 abstract description 4
- 238000009849 vacuum degassing Methods 0.000 description 55
- 238000012545 processing Methods 0.000 description 13
- 239000002893 slag Substances 0.000 description 13
- 238000007670 refining Methods 0.000 description 9
- 238000010586 diagram Methods 0.000 description 7
- 238000003756 stirring Methods 0.000 description 7
- 238000006243 chemical reaction Methods 0.000 description 6
- 230000000694 effects Effects 0.000 description 5
- 150000002431 hydrogen Chemical class 0.000 description 5
- 238000007872 degassing Methods 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 229910001873 dinitrogen Inorganic materials 0.000 description 2
- 238000002955 isolation Methods 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007123 defense Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- 238000004886 process control Methods 0.000 description 1
- 230000000750 progressive effect Effects 0.000 description 1
- 238000011897 real-time detection Methods 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 239000002436 steel type Substances 0.000 description 1
- 238000009628 steelmaking Methods 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 238000009423 ventilation Methods 0.000 description 1
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- Treatment Of Steel In Its Molten State (AREA)
Abstract
The embodiment of the invention discloses a vacuumizing control method and system of a VD mechanical pump. The vacuumizing control method of the VD mechanical pump comprises the following steps: detecting a position of a tank cover used for covering a vacuum tank after a steel ladle enters the vacuum tank, judging whether the tank cover reaches a preset position in the vacuum tank, when the tank cover reaches the preset position in the vacuum tank, performing pre-vacuumizing treatment in the vacuum tank, and orderly performing in-tank pressure-holding treatment, deep vacuumizing treatment, pre-vacuum-breaking treatment and vacuum-breaking treatment in the vacuum tank after the pre-vacuumizing treatment. The vacuumizing treatment is performed on the molten steel in the steel ladle in the vacuum tank through the vacuumizing control method of the VD mechanical pump, the equipment damage caused by molten steel slag-overflow in the steel ladle is effectively avoided, the impurities and a large amount of gas in the molten steel can be effectively removed, the cleanliness of the molten steel and the quality of the manufactured steel can be effectively improved.
Description
Technical Field
The invention relates to the technical field of steel making, in particular to a vacuumizing control method and a vacuumizing control system of a VD mechanical pump.
Background
The VD (Vacuum Degassing) refining method is also called ladle Vacuum refining method, and the VD mechanical pump is a method for removing the content of gas (hydrogen and nitrogen) in molten steel by putting ladles containing molten steel into a sealable Vacuum tank together for Vacuum pumping operation and matching with ladle bottom blowing gas stirring and utilizing the formed Vacuum environment and strong bottom blowing gas stirring.
With the development of science and technology, especially the requirements of industries such as aerospace, national defense, traffic, petroleum and automobile on the performance of steel are increasingly strict, and in order to meet the requirements of high strength, long service life, corrosion resistance and working in severe environment, the requirements on the aspects of high purity, high uniformity, fine grain size and the like of steel are increasingly high. One of the main methods commonly used in the prior art to improve the cleanliness of steel is to reduce the gas (e.g., hydrogen, nitrogen) content in the steel.
In the prior art, the method for reducing the gas content in the steel is limited by VD refining process equipment, and the vacuumizing operation of the steel ladle filled with the molten steel is completed mainly by one-line operation personnel, such as manual control on parameters of a starting sequence of a vacuum pump, argon flow control, vacuum maintaining time, minimum vacuum degree and the like. At present, in the manual control to argon gas flow control process, generally carry out evacuation work in advance to the ladle at the initial stage of evacuation to guarantee that the argon gas flow is lower, then directly improve the argon gas flow, and carry out the evacuation work of degree of depth, thereby get rid of the gas in the molten steel.
However, during the process of manually controlling the ladle to be vacuumized, high-flow argon is directly introduced into the bottom of the ladle to blow argon, so that molten steel in the ladle is easy to overflow, safety accidents such as equipment damage and the like can be caused, and isolation protection of the refining slag on the molten steel and the atmosphere after the molten steel in the ladle is broken and impurity absorption of the refining slag in the molten steel are not facilitated, so that the cleanliness of steel is reduced, and the quality of the steel is influenced.
Disclosure of Invention
The embodiment of the invention provides a vacuumizing control method and a vacuumizing control system of a VD mechanical pump, which are used for solving the problems that in the prior art, during the vacuumizing process of a ladle through manual control, high-flow ladle bottom blowing argon is directly introduced, so that molten steel in the ladle is easy to overflow slag, safety accidents such as equipment damage and the like are caused, and the isolation protection of molten steel and atmosphere by refining slag after the molten steel in the ladle is broken and the impurities in the molten steel are adsorbed by the refining slag, so that the cleanliness of steel is reduced, and the quality of the steel is influenced.
In order to solve the technical problem, the embodiment of the invention discloses the following technical scheme:
the invention provides a vacuum pumping control method of a VD mechanical pump, which comprises the following steps:
detecting the position of a ladle cover for covering the vacuum tank after the ladle enters the vacuum tank;
judging whether the position of the tank cover reaches a preset position of the vacuum tank or not;
when the position of the tank cover reaches the preset position of the vacuum tank, pre-vacuumizing treatment is carried out in the vacuum tank;
after the pre-vacuumizing treatment, performing in-tank pressure maintaining treatment on the vacuum tank;
after the pressure maintaining treatment in the vacuum tank, deep vacuumizing treatment is carried out in the vacuum tank;
after the deep vacuum pumping treatment, pre-breaking vacuum treatment is carried out in the vacuum tank;
and after the pre-vacuum breaking treatment, carrying out vacuum breaking treatment on the molten steel in the ladle.
Optionally, the performing of the pre-vacuuming treatment in the vacuum tank includes:
when the position of the tank cover reaches the preset position of the vacuum tank, controlling a first-stage vacuum pump set to work;
and controlling the argon flow of the argon blown from the bottom of the steel ladle to be a first preset flow.
Optionally, the above-mentioned pair the vacuum tank carries out jar internal pressure maintaining, include:
when the argon flow of the ladle bottom blowing argon subjected to the pre-vacuumizing treatment is a first preset flow, starting timing to obtain timing duration;
judging whether the timing time length is equal to a first preset time length or not;
and when the timing duration is equal to a first preset duration, controlling the argon flow of the argon bottom blowing of the steel ladle to be a second preset flow, wherein the second preset flow is greater than the first preset flow.
Optionally, the first preset time period is 7 minutes, the first preset flow rate is 5-10NL/min, and the second preset flow rate is 18-22 NL/min.
Optionally, the performing deep vacuum pumping treatment in the vacuum tank includes:
starting timing when the argon flow of the argon blown from the bottom of the steel ladle subjected to pressure maintaining treatment in the ladle is a second preset flow, so as to obtain timing duration;
judging whether the timing time length is equal to a second preset time length or not;
and when the timing duration is equal to a second preset duration, controlling the argon flow of the argon bottom blowing of the steel ladle to be a third preset flow.
Optionally, the second preset time period is 3 minutes, the second preset flow rate is 18 to 22NL/min, and the third preset flow rate is 70 to 120 NL/min.
Optionally, the vacuum pumping control method of the VD mechanical pump further includes:
when the position of the tank cover reaches a preset position of a vacuum tank, detecting the vacuum degree in the vacuum tank;
judging whether the vacuum degree in the vacuum tank reaches a first preset vacuum degree or not;
when the vacuum degree in the vacuum tank reaches a first preset vacuum degree, controlling a secondary vacuum pump set to work;
judging whether the vacuum degree in the vacuum tank reaches a second preset vacuum degree, wherein the second preset vacuum degree is higher than the first preset vacuum degree;
and when the vacuum degree in the vacuum tank reaches a second preset vacuum degree, controlling the three-stage vacuum pump set to work.
Optionally, the first preset vacuum degree is 7000pa, and the second preset vacuum degree is 4000 pa.
Optionally, the pre-breaking vacuum treatment performed in the vacuum tank includes:
when the argon flow of the ladle bottom blowing argon subjected to deep vacuum-pumping treatment is a third preset flow, starting timing to obtain timing duration;
judging whether the timing duration is equal to a third preset duration or not;
and when the timing duration is equal to a third preset duration, controlling the argon flow of the argon bottom blowing of the steel ladle to be a fourth preset flow.
Optionally, the third preset time period is 9 to 16 minutes, the third preset flow rate is 70 to 120NL/min, and the fourth preset flow rate is 8 to 12 NL/min; wherein,
when the third preset time period is 9 minutes or 12 minutes, the third preset flow rate is 70-100 NL/min;
and when the third preset time period is 16 minutes, the third preset flow rate is 80-120 NL/min.
Optionally, the vacuum breaking treatment of the molten steel in the ladle comprises:
when the argon flow of the ladle bottom blowing argon subjected to the pre-breaking vacuum treatment is a fourth preset flow, starting timing to obtain timing duration;
judging whether the timing time length is equal to a fourth preset time length or not;
when the timing duration is equal to a fourth preset duration, controlling a third-stage vacuum pump set, a second-stage vacuum pump set and a first-stage vacuum pump set to stop working in sequence;
controlling a vacuum breaking system to introduce nitrogen or air into the vacuum tank, and detecting the air pressure in the vacuum tank;
and when the air pressure in the vacuum tank is equal to the external atmospheric pressure, controlling the tank cover of the vacuum tank to be opened.
Optionally, the fourth preset time period is 1 minute, and the fourth preset flow rate is 8 to 12 NL/min.
Optionally, the vacuum pumping control method of the VD mechanical pump further includes:
detecting the temperature and the hydrogen content of molten steel in the ladle after the ladle enters the vacuum tank and before a tank cover covers the vacuum tank and after the ladle breaks vacuum;
detecting the argon flow and the argon pressure of the argon blown from the bottom of the steel ladle after the steel ladle reaches a preset position in the vacuum tank;
and recording the time after the steel ladle reaches the preset position in the vacuum tank and the argon flow and the argon pressure corresponding to the time.
The invention also provides a vacuum pumping control system of the VD mechanical pump, which comprises the following components: a vacuum tank, a steel ladle for storing and transferring molten steel, a first-stage vacuum pump set, a second-stage vacuum pump set, a third-stage vacuum pump set and a PLC (programmable logic controller), wherein,
the vacuum tank comprises a tank body and a tank cover, the tank body is used for containing the steel ladle, and the tank cover is used for closing the tank body in a closed manner;
a preset position detection device is arranged in the vacuum tank and used for detecting whether the steel ladle reaches a preset position or not, and the preset position detection device is connected with the PLC;
the PLC controller comprises a signal receiving circuit, a signal sending circuit, a timer, a memory and a CPU module, wherein the CPU module is respectively connected with the signal receiving circuit, the signal sending circuit, the timer and the memory, and the PLC controller is respectively connected to the primary vacuum pump group, the secondary vacuum pump group and the tertiary vacuum pump group through the signal sending circuit;
the bottom of the ladle is provided with two air inlets for bottom blowing argon, and the air inlets for bottom blowing argon are used for connecting argon.
Optionally, the vacuum pumping control system of the VD mechanical pump further comprises a temperature measuring device, an argon gas control device, a vacuum degree detecting device, a hydrogen determination instrument and an oxygen determination instrument, wherein,
the temperature measuring device, the argon gas control device and the vacuum degree measuring device are respectively connected with the PLC;
the hydrogen analyzer and the oxygen analyzer are respectively used for measuring the hydrogen content and the dissolved oxygen content in the molten steel in the steel ladle;
the temperature measuring device is used for measuring the temperature of the molten steel in the steel ladle, the argon control device is used for measuring the argon flow and the argon pressure of the argon blown from the bottom of the steel ladle, and the vacuum degree detecting device is used for measuring the vacuum degree in the vacuum tank.
Optionally, the vacuum pumping control system of the VD mechanical pump further includes: the display screen is respectively connected with the hydrogen determinator, the oxygen determinator and the PLC; wherein,
the display screen is used for displaying the hydrogen content and the dissolved oxygen content of the molten steel in the steel ladle, the argon flow, the argon pressure and the molten steel temperature.
According to the technical scheme, after a steel ladle enters a preset position in a vacuum tank and a tank cover of the vacuum tank is closed, a primary vacuum pump set, a secondary vacuum pump set and a tertiary vacuum pump set are sequentially controlled to work along with the vacuum degree in the tank, vacuumizing operation is performed, the argon flow of argon gas blown from the bottom of the steel ladle is respectively controlled within the pre-vacuumizing time, the pressure maintaining time in the tank, the deep vacuumizing time and the pre-breaking vacuum time, and gas in molten steel is removed under the vacuum condition, so that the phenomenon that the molten steel in the steel overflows from slag due to the fact that the high-flow argon gas is directly blown from the bottom of the steel ladle is prevented; not only can avoid the safety accidents such as equipment damage caused by a large amount of overflowing slag, but also can play a role in isolating and protecting molten steel and atmosphere by refining slag in the ladle after the molten steel in the ladle is broken empty, and can adsorb impurities in the molten steel, thereby effectively improving the cleanliness of the molten steel and the quality of steel production.
Furthermore, by the vacuum pumping control method of the VD mechanical pump, the problem that key parameters such as argon flow, vacuum pumping time, vacuum degree and the like are easy to intervene in the manual control vacuum pumping process is avoided, the standardized process control of molten steel is achieved, and the stability of the molten steel quality is met; meanwhile, the flow intensity of bottom-blown argon is controlled according to different time periods, the degassing effect of molten steel in the vacuumizing process is ensured, and gases such as hydrogen and nitrogen in the molten steel in a steel ladle are fully discharged, so that the discharging effect of the gases in the molten steel subjected to vacuumizing treatment is effectively improved, the cleanliness of the molten steel is further improved, and the quality of manufactured steel is effectively improved.
Drawings
In order to more clearly illustrate the embodiments or technical solutions in the prior art of the present invention, the drawings used in the description of the embodiments or prior art will be briefly described below, and it is obvious for those skilled in the art that other drawings can be obtained based on these drawings without creative efforts.
Fig. 1 is a schematic flow chart of a vacuum pumping control method of a VD mechanical pump according to an embodiment of the present invention;
fig. 2 is a schematic flow chart of another method for controlling the vacuum pumping of the VD mechanical pump according to an embodiment of the present invention;
fig. 3 is a schematic flow chart of another vacuum pumping control method for a VD mechanical pump according to an embodiment of the present invention;
fig. 4 is a schematic flow chart of another vacuum pumping control method for a VD mechanical pump according to an embodiment of the present invention;
fig. 5 is a schematic flow chart of a vacuum pumping control method of a VD mechanical pump according to an embodiment of the present invention;
fig. 6 is a schematic flow chart of another method for controlling vacuum pumping of the VD mechanical pump according to an embodiment of the present invention;
fig. 7 is a schematic flow chart of another vacuum pumping control method for a VD mechanical pump according to an embodiment of the present invention;
fig. 8 is a schematic flow chart of a vacuum pumping control method of a VD mechanical pump according to another embodiment of the present invention;
fig. 9 is a schematic structural diagram of a vacuum pumping control system of a VD mechanical pump according to an embodiment of the present invention;
fig. 10 is a schematic structural diagram of another vacuum pumping control system of a VD mechanical pump according to an embodiment of the present invention.
Detailed Description
In order to make those skilled in the art better understand the technical solution of the present invention, the technical solution in the embodiment of the present invention will be clearly and completely described below with reference to the drawings in the embodiment of the present invention, and it is obvious that the described embodiment is only a part of the embodiment of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1, a schematic flow chart of a vacuum pumping control method of a VD mechanical pump according to an embodiment of the present invention is provided.
As shown in the figure, the vacuum pumping control method of the VD mechanical pump provided by this embodiment includes:
step S100: detecting the position of a ladle cover for covering the vacuum tank after the ladle enters the vacuum tank;
wherein, in molten steel processing, need get rid of the gas (like hydrogen, nitrogen gas) in the molten steel through evacuation processing, improve the purity of molten steel, in transporting the ladle of storing transportation molten steel to the vacuum tank in carrying out the evacuation processing in-process, place this ladle behind the vacuum tank, detect the position of this vacuum tank's cover through the default position detection device that is used for detecting whether the vacuum tank covers to detect the position of this vacuum tank's cover through this default position detection device, treat this cover and reach the default position of vacuum tank, carry out further evacuation operation.
Step S200: judging whether the position of the tank cover reaches a preset position of the vacuum tank or not;
in order to ensure that gas is removed from molten steel in the ladle in a vacuum state while the cover is moved to the vacuum tank, the cover is moved completely to a port (i.e., a predetermined position) of the vacuum tank, and the cover is moved to a rail end while the vacuum tank is closed and the molten steel in the ladle is in a vacuum state by vacuuming the cover, so that the cover of the vacuum tank is closed to the port (predetermined position) of the vacuum tank, thereby performing the operation of step S300.
Step S300: when the position of the tank cover reaches the preset position of the vacuum tank, pre-vacuumizing treatment is carried out in the vacuum tank;
when the cover reaches the preset position, the cover of the vacuum tank moves to the tail end of the rail along the rail and covers the vacuum tank, the preset position detection device for detecting the cover sends a cover covering signal, the cover covering signal indicates that the cover for covering the vacuum tank reaches the preset position of the vacuum tank, and the cover of the vacuum tank covers the vacuum tank, so that the vacuum tank is controlled to be subjected to pre-vacuumizing treatment.
Referring to fig. 2, a schematic flow chart of a vacuum pumping control method of a VD mechanical pump is shown, specifically, a schematic flow chart of performing a pre-vacuum process on a vacuum tank when a tank cover of the vacuum tank reaches a preset position of the vacuum tank, where the pre-vacuum process includes:
step S301: when the position of the tank cover reaches the preset position of the vacuum tank, controlling a first-stage vacuum pump set to work;
when the cover of the vacuum tank moves to the tail end of the rail along the rail, namely the cover of the vacuum tank reaches the preset position of the vacuum tank and covers the vacuum tank, the PLC connected with the vacuum control system receives a cover covering signal, the sealing in the vacuum tank is ensured, the internal air pressure of the vacuum tank is still atmospheric pressure, and the working pressure of the first-stage vacuum pump set is atmospheric pressure, so that the first-stage vacuum pump set is controlled to work, and the vacuum tank is vacuumized.
Step S302: controlling the argon flow of the ladle bottom blowing argon to be a first preset flow;
when the cover of the vacuum tank is completely closed, the first-level vacuum pump set is controlled to work, vacuumizing operation is performed in the vacuum tank, meanwhile, argon flow of argon blown from the bottom of the steel ladle is controlled to slightly stir molten steel in the steel ladle, specifically, the argon flow is a first preset flow, and in order to prevent the molten steel in the steel ladle after the first-level vacuum pump set is started and the stirring amplitude of the molten steel is large, the molten steel is oxidized by air in the vacuum tank, the first preset flow is controlled to be 5-10 NL/min.
In the process of pre-vacuumizing, the pre-vacuumizing treatment needs to be timed, namely, a timer is used for timing while a primary vacuum pump set works, when the timing time reaches the preset time, the pre-vacuumizing treatment in the vacuum tank is stopped, and then the pressure maintaining treatment in the vacuum tank is carried out, so that the condition that slag overflow of molten steel in the steel ladle due to high argon flow of argon blown from the bottom of the steel ladle when the deep vacuumizing treatment is directly carried out is avoided; the time for this preliminary vacuum treatment was 7 minutes.
Step S400: after the pre-vacuumizing treatment, performing in-tank pressure maintaining treatment on the vacuum tank;
after the pre-vacuumizing treatment, in order to ensure that the argon flow of the argon blown from the bottom of the steel ladle is directly subjected to deep vacuumizing treatment, the molten steel in the steel ladle is subjected to slag overflow, and short-time in-tank pressure maintaining treatment needs to be performed in the vacuum tank.
Referring to fig. 3, a schematic flow chart of a vacuum pumping control method of a VD mechanical pump according to an embodiment of the present invention is specifically a schematic flow chart of an in-tank pressure maintaining process performed in a vacuum tank, where the in-tank pressure maintaining process includes:
step S401: when the argon flow of the ladle bottom blowing argon subjected to the pre-vacuumizing treatment is a first preset flow, starting timing to obtain timing duration;
when the argon flow of argon gas blown from the bottom of the ladle subjected to pre-vacuumizing treatment is a first preset flow, pre-vacuumizing treatment is started in the vacuum tank, so that timing is performed through a timer, the pre-vacuumizing treatment is completed within the pre-vacuumizing time, and when the pre-vacuumizing time is over, pressure maintaining treatment in the tank is performed.
Step S402: judging whether the timing time length is equal to a first preset time length or not;
the first preset duration is the time for performing the pre-vacuum treatment (or called pre-vacuum time), and in the process of timing by the timer, the timer can start timing from zero or count down, and the duration of the pre-vacuum time is set in advance and set as the first preset duration; it should be noted that the first preset time period is 7 minutes, so that the timer is used for timing, and if the timed time period reaches 7 minutes, the timed time period is equal to the preset pre-vacuum time, that is, the pre-vacuum processing in step S200 is completed.
Step S403: when the timing duration is equal to a first preset duration, controlling the argon flow of the argon bottom blowing of the steel ladle to be a second preset flow, wherein the second preset flow is larger than the first preset flow;
when the timing duration of the step S401 is equal to a first preset duration, the pre-vacuum-pumping treatment in the vacuum tank is completed, so that the argon flow of the argon bottom-blown from the steel ladle is controlled to be a second preset flow, and the second preset flow is greater than the first preset flow, so that the pressure maintaining treatment is performed in the vacuum tank; in the implementation process, the argon flow of argon blown from the bottom of the steel ladle during pressure maintaining treatment in the ladle is slightly larger than that of argon blown from the bottom of the steel ladle during pre-vacuumizing treatment, and meanwhile, the argon flow of the argon blown from the bottom of the steel ladle does not reach higher flow, so that the situation that the argon flow of the argon blown from the bottom of the steel ladle is directly increased to higher flow strength when deep vacuumizing treatment is carried out on molten steel in the steel ladle is avoided, the molten steel in the steel ladle is intensively stirred, and the molten steel in the steel ladle does not overflow slag; in practice, the first predetermined period is 7 minutes, the first predetermined flow rate is 5-10NL/min, and the second predetermined flow rate is 18-22 NL/min. The processing time of the in-tank pressure maintaining process was 3 minutes, and after the pressure maintaining process in the vacuum tank was completed, the operation of step S500 was performed to perform the deep vacuum pumping operation on the vacuum tank.
Step S500: after the pressure maintaining treatment in the vacuum tank, deep vacuumizing treatment is carried out in the vacuum tank;
referring to fig. 4, a schematic flow chart of a vacuum pumping control method of a VD mechanical pump according to an embodiment of the present invention, specifically, a schematic flow chart of deep vacuum pumping processing, where the operating step of performing deep vacuum pumping processing on a vacuum tank includes:
step S501: starting timing when the argon flow of the argon blown from the bottom of the steel ladle subjected to pressure maintaining treatment in the ladle is a second preset flow, so as to obtain timing duration;
when the pressure maintaining treatment in the vacuum tank is started, and the argon flow of argon blowing at the bottom of the steel ladle is the second preset flow, timing is carried out through a timer, and the timer can carry out timing on the basis of the timing time of the pre-vacuumizing treatment or can carry out timing again.
Step S502: judging whether the timing time length is equal to a second preset time length or not;
when the timer starts to count, whether the timing time reaches a preset second preset time is determined according to the timing time of the timer, wherein the second preset time is the time (or called dwell time) for the ladle to perform in-tank dwell processing in the vacuum tank, in the vacuum pumping control method of the VD mechanical pump of the embodiment, the second preset time is 3 minutes, that is, when the timing time reaches 3 minutes, the in-tank dwell processing is completed, and further, deep vacuum pumping processing is performed in the vacuum tank.
Step S503: when the timing duration is equal to a second preset duration, controlling the argon flow of the ladle bottom argon blowing to be a third preset flow;
wherein, when the timing length equals the second when predetermineeing the length of time, carry out the operation completion of jar pressurize processing in the vacuum chamber, the argon gas flow that carries out the argon gas of blowing at the bottom of the control ladle is the third and predetermine the flow, stirs the molten steel in the ladle through the bottom-blown argon gas of high flow, makes the molten steel circulation flow under the promotion of bottom-blown argon gas to accelerate the mass transfer of molten steel in the ladle, even molten steel's composition temperature makes the harmful gas in the molten steel, if: a large amount of gases such as hydrogen, nitrogen and the like quickly overflow, so that the aim of refining molten steel and the aim of improving the cleanliness of the molten steel are fulfilled; and in the process of deep vacuumizing treatment in the vacuum tank, controlling the argon flow of the argon blown from the bottom of the steel ladle to be 70-120NL/min, namely controlling the third preset flow to be 70-120 NL/min.
In the vacuum-pumping control method of the VD mechanical pump of this embodiment, in the process of performing the deep vacuum-pumping treatment in the vacuum tank, the time of the deep vacuum-pumping treatment is 9 to 16 minutes, wherein the time of the deep vacuum-pumping treatment may be set according to the steel type of the steel material required: the length of the deep vacuum treatment time is controlled according to the required hydrogen content and nitrogen content of the steel (the hydrogen content in the steel is inversely proportional to the nitrogen content and the deep vacuum treatment time, and refer to the detailed description of the embodiment of step S600).
Meanwhile, in the process of vacuumizing the vacuum tank by the primary vacuum pump set, when the vacuum degree in the vacuum tank reaches a certain vacuum degree, the secondary vacuum pump set or the tertiary vacuum pump set can be started to work for vacuumizing operation, as shown in fig. 5, the specific flow schematic diagram of the work of the secondary vacuum pump set and the tertiary vacuum pump set specifically comprises:
step S504: when the position of the tank cover reaches a preset position of a vacuum tank, detecting the vacuum degree in the vacuum tank;
wherein, it is higher in order to guarantee the vacuum in the vacuum chamber, hydrogen in the molten steel is detached to the argon gas flow through controlling the end blowing argon gas, nitrogen gas, need carry out the evacuation operation through second grade vacuum pump group and tertiary vacuum pump group, because second grade vacuum pump group and tertiary vacuum pump group need start just can reduce the vacuum in the vacuum chamber fast under certain vacuum, consequently, when the position of cover reaches the preset position of vacuum chamber, can be through the vacuum in the vacuum chamber of vacuum degree detection device real-time detection, start second grade vacuum pump group and tertiary vacuum pump group according to the vacuum in the vacuum chamber.
Step S505: judging whether the vacuum degree in the vacuum tank reaches a first preset vacuum degree or not;
the method comprises the steps that a first preset vacuum degree is set in advance according to the working vacuum degree of a secondary vacuum pump set, and whether the vacuum degree in a vacuum tank reaches the first preset vacuum degree or not is judged according to the vacuum degree in the vacuum tank detected by a vacuum degree detection device; in this embodiment, the first predetermined vacuum degree is 7000pa, that is, when the vacuum degree in the vacuum tank reaches 7000pa, the secondary vacuum pump set is put into operation to perform vacuum pumping.
Step S506: when the vacuum degree in the vacuum tank reaches a first preset vacuum degree, controlling a secondary vacuum pump set to work;
after the first-stage vacuum pump set is started, the vacuum tank is quickly vacuumized, so that the vacuum tank is in a vacuum state, when the vacuum degree detected by the vacuum degree detection device in the step S505 reaches 7000pa, the PLC controller controls the second-stage vacuum pump set to work, and deep vacuumizing treatment is performed on the vacuum tank.
Step S507: judging whether the vacuum degree in the vacuum tank reaches a second preset vacuum degree, wherein the second preset vacuum degree is higher than the first preset vacuum degree;
the vacuum degree detection device continuously detects the vacuum degree in the vacuum tank after the vacuum degree in the vacuum tank reaches 7000pa, and judges whether the vacuum degree in the vacuum tank reaches the second preset vacuum degree or not according to the vacuum degree detected by the vacuum degree detection device; in the VD mechanical pumping vacuum control method of this embodiment, the second predetermined vacuum degree is 4000pa, that is, when the vacuum degree in the vacuum tank reaches 4000pa, the three-stage vacuum pump set is started to operate.
Step S508: and when the vacuum degree in the vacuum tank reaches a second preset vacuum degree, controlling the three-stage vacuum pump set to work.
After the second-stage vacuum pump set is started, the vacuum tank is quickly vacuumized, so that the vacuum degree in the vacuum tank reaches 4000pa, the PLC controller controls the third-stage vacuum pump set to work, and deep vacuumizing treatment is performed on the vacuum tank.
In the deep vacuum-pumping process of the vacuum tank, when the pressure maintaining process in the vacuum tank is finished, the vacuum degree detection device is controlled to detect the vacuum degree and the argon flow rate of the ladle bottom blowing argon is controlled to be 70-120NL/min, and the vacuum degree detection device is used for detecting the vacuum degree in the vacuum tank and controlling the argon flow rate of the bottom blowing argon simultaneously.
In addition, in the VD mechanical pump vacuum pumping control method provided by this embodiment, the primary vacuum pump set includes 16 oil-sealed rotary-vane vacuum pumps with the same power, and the primary vacuum pump set is started to operate under atmospheric pressure; the secondary vacuum pump set comprises 8 Roots vacuum pumps with the same power, and the secondary vacuum pump set is started to work when the vacuum degree is 7000 pa; the three-stage vacuum pump set comprises 20 roots vacuum pumps with the same power, and the three-stage vacuum pump set is started to work when the vacuum degree is 4000pa, so that the vacuum tank is vacuumized, the argon flow of argon blown at the bottom of the steel ladle is controlled, hydrogen, argon and the like in molten steel in the steel ladle are discharged, the cleanliness of the molten steel is improved, and the quality of steel made of the molten steel is improved. After the deep vacuum process is performed in the vacuum tank, the operation of step S600 may be performed.
Step S600: after the deep vacuum pumping treatment, pre-breaking vacuum treatment is carried out in the vacuum tank;
after deep vacuum-pumping treatment, in order to avoid secondary oxidation caused by molten steel exposure due to direct emptying and violent stirring of molten steel caused by high argon flow of argon blown from the bottom of the steel ladle, the argon flow of the argon blown from the bottom of the steel ladle needs to be controlled to be in a soft blowing state; referring to fig. 6, a schematic flow chart of a vacuum pumping control method of the VD mechanical pump provided in this embodiment is specifically a schematic flow chart of a pre-vacuum breaking process, where the pre-vacuum breaking process includes:
step S601: when the argon flow of the ladle bottom blowing argon subjected to deep vacuum-pumping treatment is a third preset flow, starting timing to obtain timing duration;
and when the third preset flow is 70-120NL/min, the PLC controls the timer to time, and in the timing process, the timing time of the hold-down time can be kept on timing, so that the timing duration is obtained.
Step S602: judging whether the timing duration is equal to a third preset duration or not;
and when the timing duration is equal to the preset 9-16 minutes, controlling the argon flow of argon blowing at the bottom of the ladle in the pre-breaking vacuum treatment. In the vacuum pumping control method for the VD mechanical pump provided in this embodiment, the third preset time period may be set to 9 minutes, 12 minutes, or 16 minutes, so as to control the production of steel products with different hydrogen content requirements according to the time for deep vacuum pumping; specifically, if the time for the deep vacuum treatment is longer, the hydrogen content of the steel material is lower, for example:
when the third preset time is 9 minutes, namely the time of deep vacuum-pumping treatment is 9 minutes, and the argon flow for blowing argon at the bottom of the ladle is controlled to be 70-100NL/min during the deep vacuum-pumping treatment, marking the steel made of the corresponding molten steel as a first type of steel;
when the third preset time is 12 minutes, namely the time of deep vacuum-pumping treatment is 12 minutes, and the argon flow for blowing argon at the bottom of the ladle is controlled to be 70-100NL/min during the deep vacuum-pumping treatment, marking the steel made of the corresponding molten steel as a second type of steel;
when the third preset time is 16 minutes, namely the time of deep vacuum-pumping treatment is 16 minutes, and the argon flow for blowing argon at the bottom of the ladle is controlled to be 80-120NL/min during the deep vacuum-pumping treatment, marking the steel made of the corresponding molten steel as a third type of steel;
wherein, this first type steel grade, second type steel grade and the corresponding hydrogen content and the nitrogen content of third type steel grade reduce in proper order to can adapt to the quality demand of different steel, promptly in the production different types of steel grade in-process, can increase or reduce the time of degree of depth evacuation processing according to the difference of the required hydrogen content of steel or nitrogen content.
Step S603: when the timing duration is equal to a third preset duration, controlling the argon flow of the ladle bottom argon blowing to be a fourth preset flow;
the method comprises the steps of starting timing during deep vacuum pumping, entering pre-breaking vacuum processing when the timing duration of the deep vacuum pumping is equal to preset 9-16 minutes, and controlling the argon flow of argon blowing from the bottom of the steel ladle to be a fourth preset flow, wherein the fourth preset flow is a soft blowing flow, and in the VD mechanical pump vacuum pumping control method provided by the embodiment, the fourth preset flow is 8-12NL/min, so that the situation that the molten steel in the steel ladle is violently stirred by the argon of the high-flow strong argon blowing from the bottom of the steel ladle during the deep vacuum pumping in the step S500 to cause secondary oxidation of the exposed molten steel is avoided.
It should be noted that the time of the pre-breaking vacuum treatment is 1 minute, that is, the total vacuum pumping time (including the pre-vacuum pumping time, the pressure maintaining time in the ladle, the deep vacuum pumping time, and the pre-breaking vacuum time) performed on the molten steel in the ladle reaches a preset time, that is, three total vacuum pumping times are respectively preset according to the difference of the deep vacuum pumping times: 20 minutes, 23 minutes, and 27 minutes; therefore, after the total timing time reaches the total vacuumizing time, vacuum breaking operation is further carried out on the molten steel in the steel ladle.
Step S700: after the pre-breaking vacuum treatment, breaking vacuum in the vacuum tank;
after the time of pre-breaking vacuum treatment is finished, the three-stage vacuum pump set, the two-stage vacuum pump set and the one-stage vacuum pump set can be closed, and then the vacuum breaking operation of the molten steel in the vacuum tank is finished;
referring to fig. 7, a schematic flow chart of a vacuum pumping control method of a VD mechanical pump provided in this embodiment is specifically a schematic flow chart of a vacuum breaking process, where the vacuum breaking process includes:
step S701: when the argon flow of the ladle bottom blowing argon subjected to the pre-breaking vacuum treatment is a fourth preset flow, starting timing to obtain timing duration;
and when the deep vacuum-pumping time is finished and the argon gas blown from the bottom of the steel ladle subjected to the pre-vacuum-breaking treatment is controlled to be 8-12NL/min, timing by a timer, and in the timing process, timing can be carried out on the basis of the timing time of the deep vacuum-pumping treatment in the step S600, so that the timing time is obtained.
Step S702: judging whether the timing time length is equal to a fourth preset time length or not;
in the vacuum pumping control method of the VD mechanical pump provided in this embodiment, the fourth preset time is set to 1 minute, so as to determine whether the timing time of step S701 reaches 1 minute.
Step S703: when the timing duration is equal to a fourth preset duration, controlling a third-stage vacuum pump set, a second-stage vacuum pump set and a first-stage vacuum pump set to stop working in sequence;
when the timing time reaches 1 minute, namely after the pre-breaking vacuum treatment is finished, the PLC controls a third-stage vacuum pump set, a second-stage vacuum pump set and a first-stage vacuum pump set in the VD mechanical pump to stop working, and when the vacuum pump sets are controlled to stop working, the vacuum pump needs to be controlled to stop working one by one, namely the third-stage vacuum pump set is closed first, then the second-stage vacuum pump set is closed, and finally the first-stage vacuum pump set is closed, so that the damage of the third-stage vacuum pump set, the second-stage vacuum pump set or the first-stage vacuum pump.
Step S704: controlling a vacuum breaking system to introduce nitrogen or air into a vacuum tank, and detecting the air pressure in the vacuum tank;
the vacuum breaking system is a compression device or ventilation equipment for introducing nitrogen or air into the vacuum tank, and the nitrogen or air is introduced into the vacuum tank through the vacuum breaking system so as to eliminate the vacuum state in the vacuum tank; meanwhile, an air pressure detection device needs to be arranged in the vacuum tank and connected with the PLC, so that the air pressure in the vacuum tank after the nitrogen or air is introduced into the vacuum breaking system is detected, and whether the vacuum state in the vacuum tank is eliminated or not is confirmed.
Step S705: when the air pressure in the vacuum tank is equal to the external atmospheric pressure, controlling the tank cover of the vacuum tank to be opened;
because the vacuum tank processed in step S600 is still in a vacuum state, the vacuum tank is in a negative pressure state, so that the tank cover of the vacuum tank cannot be opened, or the vacuum tank or the tank cover may be damaged when the tank cover of the vacuum tank is forcibly opened; therefore, after the vacuum breaking system is filled with nitrogen in the vacuum tank, the air pressure value in the vacuum tank can be measured through the air pressure detection device or the vacuum degree detection device, when the air pressure in the vacuum tank is atmospheric pressure, the cover of the vacuum tank can be controlled to be opened, so that the molten steel in the steel ladle in the vacuum tank is broken in vacuum, and meanwhile, the bottom-blown argon of the steel ladle is still in a soft-blowing state (namely the argon flow of the bottom-blown argon of the steel ladle is 8-12 NL/min).
By adopting the vacuumizing control method of the VD mechanical pump provided by the embodiment, after a steel ladle for storing and transferring molten steel reaches a preset position in a vacuum tank, the vacuumizing operation is carried out in the vacuum tank by respectively controlling the work of the first-stage vacuum pump set, the second-stage vacuum pump set and the third-stage vacuum pump set, wherein when the vacuumizing operation is carried out in the vacuum tank, the deep vacuumizing operation from the low-flow bottom-blowing argon vacuumizing treatment to the high-flow bottom-blowing argon is carried out, and the in-tank pressure maintaining treatment is carried out in the vacuum tank by carrying out the argon flow which is greater than the bottom-blowing argon during the pre-vacuumizing treatment after the pre-vacuumizing treatment, so that the condition that the slag overflow of the molten steel occurs due to the fact that the argon flow of the steel ladle bottom-blowing argon is directly.
Further, in the vacuum-pumping control method of the VD mechanical pump provided in this embodiment, when the molten steel in the ladle in the vacuum tank is vacuumized, by controlling the deep vacuum-pumping time of the molten steel, that is, increasing the argon flow of argon blown from the bottom of the ladle while vacuuming, gases such as hydrogen and nitrogen contained in the molten steel can be discharged when the argon flow circularly stirs the molten steel, and the amount of discharged gases is increased according to the length of the deep vacuum-pumping time (the deep vacuum-pumping time is inversely proportional to the gas content in the molten steel), so that the cleanliness of the molten steel is improved, and the quality of steel manufactured from the molten steel is improved; further, the time for the deep vacuum treatment can be controlled according to the amount of hydrogen contained in the steel material.
In the vacuum pumping control method of the VD mechanical pump provided in this embodiment, the vacuum pumping control method of the VD mechanical pump further includes measuring parameters of molten steel in a ladle, so as to display a parameter history curve according to each parameter measurement, specifically referring to fig. 8, another flow diagram of the vacuum pumping control method of the VD mechanical pump provided in this embodiment of the present invention includes:
step S801: detecting the temperature and the hydrogen content of molten steel in the steel ladle before the steel ladle enters the vacuum tank and after the steel ladle breaks vacuum;
when the molten steel in the steel ladle is vacuumized, the temperature and the hydrogen content (dissolved oxygen content and the like) of the molten steel in the steel ladle can be measured before the steel ladle filled with the molten steel enters a vacuum tank and vacuumized (namely before a tank cover is sealed), and the temperature and the hydrogen content (dissolved oxygen content and the like) of the molten steel in the steel ladle can be measured after the molten steel in the steel ladle is vacuumized, so that the degassing rate of the molten steel in the steel ladle can be judged according to the temperature, the hydrogen content or the dissolved oxygen content of the molten steel in the steel ladle measured before and after the vacuumizing operation, and the effect of vacuumizing the molten steel in the steel ladle is verified.
Step S802: detecting the argon flow and the argon pressure of bottom-blown argon after the ladle enters the vacuum tank;
when the ladle enters the preset position of the vacuum tank, the tank cover of the vacuum tank is controlled to be closed, the argon flow and the argon pressure of argon blowing at the bottom of the ladle are controlled, and the argon flow and the argon pressure of the argon blowing at the bottom of the ladle are detected through the argon control device when the argon flow of the argon blowing at the bottom of the ladle is controlled.
Step S803: recording the time of the steel ladle entering the vacuum tank and the argon flow and the argon pressure corresponding to the time;
in the vacuumizing control method of the VD mechanical pump of the present embodiment, the pre-vacuumizing treatment, the in-tank pressure maintaining treatment, the deep vacuumizing treatment, the pre-vacuum breaking treatment, and the like are performed on the molten steel in the ladle, and the time is counted by the timer during the treatment process, so that the time from the start of the pre-vacuumizing treatment to the end of the pre-vacuum breaking treatment in the vacuum tank is recorded, and the argon flow and the argon pressure of the argon bottom-blown into the ladle corresponding to the time are measured, so that the effect of the vacuum-pumping treatment on the molten steel in the ladle can be determined according to the time and the corresponding argon flow.
In the vacuum-pumping control method of the VD mechanical pump provided by this embodiment, it is possible to determine whether the molten steel in the ladle reaches the vacuum-pumping standard during the vacuum-pumping process according to each parameter corresponding to the recorded time by recording the time for the molten steel in the ladle to be evacuated in the vacuum tank, and the corresponding argon flow and argon pressure for blowing argon at the bottom of the ladle, and measuring the temperature and hydrogen content of the molten steel in the ladle.
According to the vacuumizing control method of the VD mechanical pump provided by the embodiment, the vacuumizing treatment is carried out in the vacuum tank by automatically controlling the vacuum pump group, and the flow of the pressure gas of argon blown from the bottom of the steel ladle is controlled, so that the gas in the molten steel in the steel ladle is removed; therefore, the influence on the quality of the molten steel caused by slag overflow or low degassing rate of the molten steel in the steel ladle due to manual intervention during vacuumizing treatment of the molten steel in the steel ladle in the prior art is avoided; and by recording the temperature, the dissolved oxygen amount and the like of the molten steel, a key process parameter historical curve can be established according to the recorded data, so that the effect of vacuum treatment is monitored.
Corresponding to the embodiment of the vacuum pumping control method of the VD mechanical pump provided by the invention, the invention also provides a vacuum pumping control system of the VD mechanical pump.
Referring to fig. 9, a schematic structural diagram of a vacuum pumping control system of a VD mechanical pump according to an embodiment of the present invention is provided, specifically, a structural block diagram of the vacuum pumping control system.
As shown in the drawings, the vacuum pumping control system of the VD mechanical pump provided by the embodiment of the present invention includes: the device comprises a vacuum tank 1, a steel ladle 2 for storing and transferring molten steel, a primary vacuum pump group 3, a secondary vacuum pump group 4, a tertiary vacuum pump group 5 and a PLC (programmable logic controller) 6; wherein,
vacuum tank 1: comprises a tank body and a tank cover, wherein the tank body is used for containing a ladle 2 for storing and transferring molten steel, and the tank cover is used for closing and covering the tank body (namely a tank opening of a vacuum tank); the vacuum degree tester is arranged in a pipeline which is communicated with the vacuum pump group and is used for measuring the vacuum degree in the vacuum tank 1 according to the vacuum pumping process of the vacuum tank 1 by the vacuum pump group, so that different vacuum pump groups are controlled to work and the vacuum tank 1 is vacuumized when a certain vacuum degree is reached in the vacuum tank 1, the preset position detection device is used for detecting the position of a tank cover of the vacuum tank, and when the tank cover of the vacuum tank is covered on the tank body of the vacuum tank, a first-level vacuum pump group is controlled to work; the preset position detection device and the vacuum degree tester are respectively connected with a PLC (programmable logic controller) 6 for controlling the argon flow of the ladle bottom blowing argon and controlling the work of a timer 14;
and (3) a steel ladle 2: molten steel is filled in the steel ladle 2 and is used for transporting the molten steel into the vacuum tank 1 to carry out vacuum-pumping treatment and remove residual gases (such as hydrogen, nitrogen and the like) in the molten steel, two air inlets for bottom blowing argon are arranged at the bottom of the steel ladle 2, and the air inlets for the bottom blowing argon are used for being connected with argon;
a first-stage vacuum pump group 3: the vacuum pump set comprises 16 oil seal rotary vane vacuum pumps with the same power, and the primary vacuum pump set 3 can be started under the atmospheric pressure so as to vacuumize the vacuum tank;
a secondary vacuum pump set 4: the vacuum pump system comprises 8 Roots vacuum pumps with the same power, wherein the secondary vacuum pump set 4 can be started only when the vacuum degree in the vacuum tank reaches a certain vacuum degree, and the working vacuum degree of the secondary vacuum pump set 4 is 7000 pa;
a third-stage vacuum pump set 5: the three-stage vacuum pump set 5 can be started only when the three-stage vacuum pump set 5 reaches a higher vacuum degree in the vacuum tank, wherein the working vacuum degree of the three-stage vacuum pump set 5 is 4000pa smaller than that of the two-stage vacuum pump set 4;
the PLC controller 6: the PLC controller 6 is respectively connected with the first-stage vacuum pump unit 3, the second-stage vacuum pump unit 4 and the third-stage vacuum pump unit 5, and when the vacuum degree in the vacuum tank 1 reaches a certain value, the PLC controller 6 respectively controls the first-stage vacuum pump unit 3, the second-stage vacuum pump unit 4 and the third-stage vacuum pump unit 5 to work; the PLC controller 6 includes a signal receiving circuit 12, a signal transmitting circuit 13, a timer 14, a memory 15, and a CPU module 11. Specifically, as shown in fig. 10, the PLC controller 6 has a schematic structural diagram, in which:
the signal receiving circuit 12 is configured to receive a tank cover closing signal, temperature information of molten steel in a steel ladle, argon flow information of bottom-blown argon, argon pressure information, and vacuum degree information, and send the received information to the CPU module 11; the signal sending circuit 13 is used for receiving a control signal of the CPU module 11, the control signal is a control signal for controlling the work of the first-stage vacuum pump unit 3, the second-stage vacuum pump unit 4 and the third-stage vacuum pump unit 5 and a control signal for controlling the argon flow of the argon bottom blowing of the steel ladle 2, and the control signal is sent to corresponding equipment through the signal sending circuit 13 so as to control the work of the corresponding equipment;
the timer 14 is used for calculating the time for carrying out the vacuumizing operation after the ladle enters the vacuum tank 1 and sending the timing time to the CPU module 11, wherein in the vacuumizing control system of the VD mechanical pump, the timer 14 may include a plurality of timers, the time for carrying out the pre-vacuumizing treatment, the in-tank pressure maintaining treatment, the deep vacuumizing treatment and the pre-breaking vacuum treatment in the vacuum tank 1 in sequence is controlled by the timing time of the timer 14 received by the CPU module 11, and the timing time is sent to the CPU module 11, and the CPU module 11 controls the argon flow of the ladle bottom-blown argon and the switch of the vacuum pump set according to the timing time;
the storage 15 is used for storing the preset vacuum degrees of the first-stage vacuum pump unit 3, the second-stage vacuum pump unit 4 and the third-stage vacuum pump unit 5, and storing the argon flow of argon blowing from the bottom of the steel ladle, specifically, the argon flow of pre-vacuumizing is 5-10NL/min, the argon flow of pressure maintaining treatment in the ladle is 18-22NL/min, the argon flow of deep vacuumizing treatment is 70-120NL/min, and the argon flow of pre-breaking vacuum treatment is 8-12 NL/min; the CPU module 11 is configured to receive information sent by the signal receiving circuit 12, and specifically, the CPU module 11 receives the temperature, the hydrogen content, and the dissolved oxygen content of the molten steel in the ladle 2, and the vacuum degree in the vacuum tank 1 and the timing time of the timer, so as to control the argon flow of the ladle bottom-blown argon, the second-stage vacuum pump group 4, and the third-stage vacuum pump group 5 to operate according to the preset time and the preset vacuum degree.
In the vacuum pumping control system of the VD mechanical pump provided in this embodiment, the vacuum pumping control system of the VD mechanical pump further includes: a display circuit, an analog-to-digital conversion circuit, and a digital-to-analog conversion circuit, wherein,
the analog-to-digital conversion circuit is connected with the signal receiving circuit 12, the digital-to-analog conversion circuit is connected with the signal sending circuit 13, the analog-to-digital conversion circuit is used for converting the analog signal received by the signal receiving circuit 12 into a digital signal, and the digital-to-analog conversion circuit is used for converting the digital signal sent to the signal sending module by the CPU module 11 into an analog signal and sending the analog signal through the signal sending module 13; the display circuit is connected with the CPU module 11, and receives the timing time of the timer 14 sent by the CPU module 11, the pressure gas flow of the argon gas blown from the bottom of the steel ladle corresponding to the timing time, and the temperature and the hydrogen content of the molten steel in the steel ladle detected by the temperature detection device.
The vacuumizing control system of the VD mechanical pump also comprises a temperature measuring device, an argon gas control device and a vacuum degree detection device, wherein the temperature measuring device is used for measuring the temperature of molten steel in a steel ladle, the argon gas control device is used for measuring the argon gas flow and the argon gas pressure of argon gas blown from the bottom of the steel ladle, the vacuum degree detection device is used for measuring the vacuum degree in the vacuum tank, and the temperature measuring device, the argon gas control device and the vacuum degree detection device are respectively connected with the CPU module through signal receiving circuits; and the vacuum tank is also internally provided with a hydrogen determination instrument and an oxygen determination instrument for measuring the molten steel in the steel ladle, so that the hydrogen content and the dissolved oxygen content in the molten steel in the steel ladle are respectively measured by the hydrogen determination instrument and the oxygen determination instrument.
The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, for apparatus or system embodiments, since they are substantially similar to method embodiments, they are described in relative terms, as long as they are described in partial descriptions of method embodiments. The above-described embodiments of the apparatus and system are merely illustrative, and the units described as separate parts may or may not be physically separate, and the parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.
It is noted that, in this document, relational terms such as "first" and "second," and the like, may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The foregoing are merely exemplary embodiments of the present invention, which enable those skilled in the art to understand or practice the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (16)
1. A vacuum pumping control method of a VD mechanical pump is characterized by comprising the following steps:
detecting the position of a ladle cover for covering the vacuum tank after the ladle enters the vacuum tank;
judging whether the position of the tank cover reaches a preset position of the vacuum tank or not;
when the position of the tank cover reaches the preset position of the vacuum tank, pre-vacuumizing treatment is carried out in the vacuum tank;
after the pre-vacuumizing treatment, performing in-tank pressure maintaining treatment on the vacuum tank;
after the pressure maintaining treatment in the vacuum tank, deep vacuumizing treatment is carried out in the vacuum tank;
after the deep vacuum pumping treatment, pre-breaking vacuum treatment is carried out in the vacuum tank;
and after the pre-vacuum breaking treatment, carrying out vacuum breaking treatment on the molten steel in the ladle.
2. A method for controlling vacuum pumping of a VD mechanical pump according to claim 1, wherein the pre-vacuum process performed in the vacuum tank includes:
when the position of the tank cover reaches the preset position of the vacuum tank, controlling a first-stage vacuum pump set to work;
and controlling the argon flow of the argon blown from the bottom of the steel ladle to be a first preset flow.
3. A method for controlling vacuum pumping of a VD mechanical pump according to claim 1, wherein the performing of the in-tank pressure maintaining process on the vacuum tank comprises:
when the argon flow of the ladle bottom blowing argon subjected to the pre-vacuumizing treatment is a first preset flow, starting timing to obtain timing duration;
judging whether the timing time length is equal to a first preset time length or not;
and when the timing duration is equal to a first preset duration, controlling the argon flow of the argon bottom blowing of the steel ladle to be a second preset flow, wherein the second preset flow is greater than the first preset flow.
4. A method according to claim 3, wherein the first preset time period is 7 minutes, the first preset flow rate is 5-10NL/min, and the second preset flow rate is 18-22 NL/min.
5. A method for controlling vacuum pumping of a VD mechanical pump according to claim 1, wherein the deep vacuum pumping process in the vacuum tank comprises:
starting timing when the argon flow of the argon blown from the bottom of the steel ladle subjected to pressure maintaining treatment in the ladle is a second preset flow, so as to obtain timing duration;
judging whether the timing time length is equal to a second preset time length or not;
and when the timing duration is equal to a second preset duration, controlling the argon flow of the argon bottom blowing of the steel ladle to be a third preset flow.
6. A method according to claim 5, wherein the second preset time period is 3 minutes, the second preset flow rate is 18-22NL/min, and the third preset flow rate is 70-120 NL/min.
7. The method for controlling vacuum pumping by a VD mechanical pump according to claim 1, further comprising:
when the position of the tank cover reaches a preset position of a vacuum tank, detecting the vacuum degree in the vacuum tank;
judging whether the vacuum degree in the vacuum tank reaches a first preset vacuum degree or not;
when the vacuum degree in the vacuum tank reaches a first preset vacuum degree, controlling a secondary vacuum pump set to work;
judging whether the vacuum degree in the vacuum tank reaches a second preset vacuum degree, wherein the second preset vacuum degree is higher than the first preset vacuum degree;
and when the vacuum degree in the vacuum tank reaches a second preset vacuum degree, controlling the three-stage vacuum pump set to work.
8. A method according to claim 7, wherein the first predetermined vacuum level is 7000pa and the second predetermined vacuum level is 4000 pa.
9. A method for controlling vacuum pumping by a VD mechanical pump according to claim 1, wherein the pre-breaking vacuum process performed in the vacuum tank comprises:
when the argon flow of the ladle bottom blowing argon subjected to deep vacuum-pumping treatment is a third preset flow, starting timing to obtain timing duration;
judging whether the timing duration is equal to a third preset duration or not;
and when the timing duration is equal to a third preset duration, controlling the argon flow of the argon bottom blowing of the steel ladle to be a fourth preset flow.
10. A method for controlling vacuum pumping by a VD mechanical pump according to claim 8, wherein the third preset time period is 9 to 16 minutes, the third preset flow rate is 70 to 120NL/min, and the fourth preset flow rate is 8 to 12 NL/min; wherein,
when the third preset time period is 9 minutes or 12 minutes, the third preset flow rate is 70-100 NL/min;
and when the third preset time period is 16 minutes, the third preset flow rate is 80-120 NL/min.
11. The vacuum pumping control method for a VD mechanical pump according to claim 1, wherein the vacuum breaking treatment for the molten steel in the ladle comprises the following steps:
when the argon flow of the ladle bottom blowing argon subjected to the pre-breaking vacuum treatment is a fourth preset flow, starting timing to obtain timing duration;
judging whether the timing time length is equal to a fourth preset time length or not;
when the timing duration is equal to a fourth preset duration, controlling a third-stage vacuum pump set, a second-stage vacuum pump set and a first-stage vacuum pump set to stop working in sequence;
controlling a vacuum breaking system to introduce nitrogen or air into the vacuum tank, and detecting the air pressure in the vacuum tank;
and when the air pressure in the vacuum tank is equal to the external atmospheric pressure, controlling the tank cover of the vacuum tank to be opened.
12. A method for controlling vacuum pumping by a VD mechanical pump according to claim 11, wherein the fourth preset time period is 1 minute, and the fourth preset flow rate is 8-12 NL/min.
13. The method for controlling vacuum pumping by a VD mechanical pump according to claim 1, further comprising:
detecting the temperature and the hydrogen content of molten steel in the ladle after the ladle enters the vacuum tank and before a tank cover covers the vacuum tank and after the ladle breaks vacuum;
detecting the argon flow and the argon pressure of the argon blown from the bottom of the steel ladle after the steel ladle reaches a preset position in the vacuum tank;
and recording the time after the steel ladle reaches the preset position in the vacuum tank and the argon flow and the argon pressure corresponding to the time.
14. A vacuum pumping control system of a VD mechanical pump is characterized by comprising: a vacuum tank, a steel ladle for storing and transferring molten steel, a first-stage vacuum pump set, a second-stage vacuum pump set, a third-stage vacuum pump set and a PLC (programmable logic controller), wherein,
the vacuum tank comprises a tank body and a tank cover, the tank body is used for containing the steel ladle, and the tank cover is used for closing the tank body in a closed manner;
a preset position detection device is arranged in the vacuum tank and used for detecting whether the steel ladle reaches a preset position or not, and the preset position detection device is connected with the PLC;
the PLC controller comprises a signal receiving circuit, a signal sending circuit, a timer, a memory and a CPU module, wherein the CPU module is respectively connected with the signal receiving circuit, the signal sending circuit, the timer and the memory, and the PLC controller is respectively connected to the primary vacuum pump group, the secondary vacuum pump group and the tertiary vacuum pump group through the signal sending circuit;
the bottom of the ladle is provided with two air inlets for bottom blowing argon, and the air inlets for bottom blowing argon are used for connecting argon.
15. The vacuum pumping control system of a VD mechanical pump, as recited in claim 14, further comprising a temperature measuring device, an argon gas control device, a vacuum degree detection device, a hydrogen determination instrument, and an oxygen determination instrument, wherein,
the temperature measuring device, the argon gas control device and the vacuum degree measuring device are respectively connected with the PLC;
the hydrogen analyzer and the oxygen analyzer are respectively used for measuring the hydrogen content and the dissolved oxygen content in the molten steel in the steel ladle;
the temperature measuring device is used for measuring the temperature of the molten steel in the steel ladle, the argon control device is used for measuring the argon flow and the argon pressure of the argon blown from the bottom of the steel ladle, and the vacuum degree detecting device is used for measuring the vacuum degree in the vacuum tank.
16. The vacuum pumping control system of a VD mechanical pump according to claim 15, further comprising: the display screen is respectively connected with the hydrogen determinator, the oxygen determinator and the PLC; wherein,
the display screen is used for displaying the hydrogen content and the dissolved oxygen content of the molten steel in the steel ladle, the argon flow, the argon pressure and the molten steel temperature.
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