Control method, device and system for argon system using liquid air as cooling source in air separation unit

Abstract

The present invention provides a control method, device and system for an argon system of an air separation device with liquid air as a cold source, and belongs to the field of automatic control technology of air separation devices. The automatic control method comprises: in the system startup stage, setting the first valve to an automatic mode so that the liquid level in the crude argon tower is automatically accumulated to a preset liquid level within a preset time; when the liquid level in the crude argon tower reaches the preset liquid level, starting the argon pump, and setting the second valve to an automatic control mode so that the liquid in the crude argon tower flows into the pure argon tower; when the liquid flows into the pure argon tower, a PID controller based on pressure and flow rate is used to select a low strategy, and the flow rate entering the pure argon tower is adjusted by controlling the third valve; when a stop signal is received, the argon system is controlled to stop running. The present invention can reduce labor intensity through one-button operation, avoid misoperation accidents through automatic and precise control, and can optimize control to reduce energy consumption and avoid energy waste.

Description

Technical Field

[0001] The invention relates to the technical field of automatic control of air separation devices, and in particular to a control method, device and system for an argon system of an air separation device using liquid air as a cold source. Background Art

[0002] With the rapid development of industrial production, air separation units, as key equipment for obtaining high-purity gases, are widely used in many fields such as steel, chemical industry, electronics, etc. Among them, the stable and efficient operation of the argon system is crucial to ensure the overall performance of the air separation unit and meet the stringent requirements of downstream high-end industries for argon purity.

[0003] In the prior art, the control methods of argon systems are mainly divided into pure manual control and semi-automatic control. Pure manual control relies on operators to rely on local instruments and experience to control valves, motors, etc. to complete production. Although the equipment investment is low, it requires multiple people for startup and debugging, and the labor cost is high. The operating accuracy is greatly affected by the experience of the operators, which can easily cause product fluctuations and imbalances in process conditions. Semi-automatic control relies on the DCS system, and the operators operate the computer in the control room. The manpower for startup and debugging is reduced to 2-3 people, and the equipment movement accuracy is improved. However, its startup time is affected by the experience of the operators, which can easily cause energy waste. In addition, the operator needs to confirm the startup conditions of the single machine on site when starting the machine, which poses a safety risk. Summary of the invention

[0004] The present invention provides a control method, device and system for an argon system of an air separation unit using liquid air as a cold source, which are used to solve the problems of high labor cost, low operation accuracy, high startup energy consumption and high personnel safety risk existing in the prior art.

[0005] In order to achieve the above-mentioned purpose, an embodiment of the present invention provides an automatic control method for the operation of an argon system of an air separation unit using liquid air as a cold source, wherein the argon system comprises a crude argon tower, a pure argon tower, an argon pump arranged on a connecting pipe between the crude argon tower and the pure argon tower, a first valve arranged at a preset position of an inlet of the crude argon tower, a second valve arranged at a preset position of the argon pump, and a third valve at a preset position of an outlet of the crude argon tower, wherein the automatic control method comprises: in a system startup phase, setting the first valve to an automatic mode so that the liquid level in the crude argon tower automatically accumulates to a preset liquid level within a preset time; when the liquid level in the crude argon tower reaches the preset liquid level, starting the argon pump, and setting the second valve to an automatic control mode so that the liquid in the crude argon tower flows into the pure argon tower; when the liquid flows into the pure argon tower, a PID controller low selection strategy based on pressure and flow is used, and the flow rate of the liquid entering the pure argon tower is adjusted by controlling the third valve; and when a stop signal is received, controlling the argon system to stop running.

[0006] Optionally, the step of causing the liquid level in the crude argon tower to automatically accumulate to a preset liquid level within a preset time includes: utilizing the first valve to perform stage-by-stage speed control for different liquid level intervals in the crude argon tower.

[0007] Optionally, before starting the argon pump, the automatic control method further includes: pre-cooling the argon pump, including checking the temperature of the pump body, the sealing condition, and the pipeline connection status.

[0008] Optionally, setting the second valve to automatic control mode includes: loading the frequency of the argon pump to a given frequency value according to a preset time; if the frequency of the argon pump is greater than a frequency threshold during loading, or the pressure of the second valve is lower than a pressure threshold and the duration exceeds a given value, the startup fails, the valve is unloaded, and the pre-cooling confirmation is performed again; if the frequency reaches the given frequency value, the second valve is set to automatic control mode.

[0009] Optionally, the PID controller based on pressure and flow adopts a low-selection strategy, and adjusts the flow entering the pure argon tower by controlling the third valve, including: monitoring the flow and pressure at the outlet of the crude argon tower; comparing the flow and pressure with the set values, and controlling the opening of the third valve by low-selection to adjust the flow entering the pure argon tower.

[0010] Optionally, when a stop signal is received, controlling the argon system to stop operation includes: resetting the liquid level setting value of the crude argon tower to an initial value according to the stop signal, so that the load of the crude argon tower is automatically exited until the operation is stopped.

[0011] Optionally, the automatic control method further comprises: isolating the crude argon tower when the argon pump fails or cavitation occurs.

[0012] Optionally, determining that the argon pump fails includes: the liquid level in the lower tower of the crude argon tower is greater than an alarm value, and the pressure of the second valve is lower than a given value; or an operating signal of the argon pump is lost.

[0013] On the other hand, the present invention also provides a control device, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement any one of the above-mentioned automatic control methods.

[0014] On the other hand, the present invention also provides an automatic control system for the operation of an argon system using liquid air as a cold source in an air separation unit, the argon system comprising a crude argon tower, a pure argon tower, an argon pump arranged on a connecting pipe between the crude argon tower and the pure argon tower, a first valve arranged at a preset position of an inlet of the crude argon tower, a second valve arranged at a preset position of the argon pump, and a third valve at a preset position of an outlet of the crude argon tower, the automatic control system comprising: a DCS control unit, comprising the above-mentioned control device, for receiving a manual start-up instruction and controlling the automatic operation of the crude argon tower; a liquid level monitoring and control module, electrically connected to the first valve and the second valve, for monitoring and controlling the liquid level in the crude argon tower; an argon pump control module, for adjusting the frequency of the argon pump; a dual controller low selection module, comprising a pressure controller and a flow controller, the control device is also used for a PID controller low selection strategy based on pressure and flow, and adjusts the flow entering the pure argon tower by controlling the dual controller low selection module and the third valve; a fault detection and processing module, for monitoring the operating state of the argon pump, and automatically cutting off the crude argon tower when the argon pump fails.

[0015] The control method, device and system of the argon system of the air separation unit with liquid air as the cold source provided by the present invention simplify the cumbersome start-stop operation into a one-button operation, reduce the demand for professionals during startup debugging and operation, and optimize the control strategy so that the system can use energy more reasonably during startup and operation, and avoid safety accidents caused by human error through precise automatic control. The present invention establishes a method for fully automatic operation of the argon system through the above method, realizes full process automation from manual startup, greatly improves operation efficiency, greatly reduces the labor intensity and work difficulty of operators, and reduces losses caused by shutdown due to failure. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the prior art description. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. In the drawings: Figure 1 It is a flow chart of an automatic control method for operation of an argon system using liquid air as a cold source in an air separation unit provided by an embodiment of the present invention; Figure 2 It is a schematic diagram of the status of valves related to the pure argon tower provided in an embodiment of the present invention; Figure 3 is a flow chart of starting an argon system provided by an embodiment of the present invention; Figure 4is a flowchart of starting an argon pump provided by an embodiment of the present invention; Figure 5 is a flow chart of argon pump loading determination provided by an embodiment of the present invention; Figure 6 It is a working schematic diagram of the low selection strategy of the two PID controllers of pressure and flow provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0017] The specific implementation of the embodiment of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the embodiment of the present invention, and is not used to limit the embodiment of the present invention.

[0018] It should be noted that the acquisition, transmission, storage, use, and processing of data in the technical solution of this application are in compliance with the relevant provisions of national laws and regulations. In the embodiments of this application, some existing solutions in the industry such as certain software, components, and models may be mentioned, which should be considered as exemplary. Their purpose is only to illustrate the feasibility of implementing the technical solution of this application, but it does not mean that the applicant has or will necessarily use the solution.

[0019] In the process of industrial development, air separation units are widely used in many fields. However, the traditional argon system only provides two control modes: pure manual and semi-automatic. The labor cost is high, the safety risk is high, and it is easy to cause energy waste. Therefore, it is necessary to improve the automation level of the argon system operation in order to reduce labor costs and ensure the safe, efficient and automatic operation of the argon system.

[0020] To address this problem, the present invention provides a control method, device and system for an argon system of an air separation unit using liquid air as a cold source, which simplifies complicated start and stop operations into one-button operations, greatly reducing the labor intensity and work difficulty of operators, and avoiding safety accidents caused by human errors through precise automatic control. In addition, by optimizing the control strategy, the argon system can use energy more reasonably during startup, operation and shutdown.

[0021] Combine the following Figure 1-Figure 6 The present invention is described in detail.

[0022] Figure 1 It is a flow chart of an automatic control method for operation of an argon system of an air separation unit using liquid air as a cold source provided by an embodiment of the present invention.

[0023] like Figure 1As shown, an automatic control method for the operation of an argon system of an air separation unit using liquid air as a cold source provided in an embodiment of the invention, the argon system may include a crude argon column, a pure argon column, an argon pump provided on a connecting pipe between the crude argon column and the pure argon column, a first valve provided at a preset position of an inlet of the crude argon column, a second valve provided at a preset position of the argon pump, and a third valve provided at a preset position of an outlet of the crude argon column, the automatic control method may include the following steps: Step 101: During the system startup phase, the first valve is set to an automatic mode so that the liquid level in the crude argon column is automatically accumulated to a preset liquid level within a preset time; Step 102: When the liquid level in the crude argon column reaches the preset liquid level, start the argon pump and set the second valve to an automatic control mode so that the liquid in the crude argon column flows into the pure argon column; Step 103: When the liquid flows into the pure argon tower, the PID controller based on pressure and flow rate selects a low strategy, and adjusts the flow rate of the liquid entering the pure argon tower by controlling the third valve; Step 104: When the stop signal is received, the argon system is controlled to stop running.

[0024] The automatic control method for the operation of the argon system with liquid air as a cold source in an air separation unit provided by the present invention can realize full-process automatic control after startup. The first valve accurately controls the liquid level according to the program and automatically controls the condensation process of accumulated liquid. At the same time, the startup loading of the argon pump is automated, and the frequency and pressure are closely monitored during loading to ensure the stable operation of the argon pump to establish the argon circulation volume. Furthermore, the third valve uses a dual-controller low-selection strategy to intelligently and accurately adjust the opening according to the flow and pressure requirements, eliminate hidden dangers such as nitrogen accumulation and overpressure, and maintain the stable operation of the crude argon tower. The automatic control method simplifies the start-stop operation into a one-button operation, and there is no need for the operator to pay attention to and manually operate various valves, motors and other equipment at all times, which greatly reduces the labor intensity and work difficulty of the operator, reduces the demand for professionals during startup debugging and operation, and saves a lot of labor costs. Through precise automatic control, safety accidents caused by human error are avoided.

[0025] In a preferred embodiment of the present invention, the first valve is, for example, a crude argon condenser liquid-to-vacuum return valve, which is used to control the flow rate of liquid entering the crude argon tower. The second valve is, for example, an argon pump outlet reflux valve, which is used to control the flow rate of liquid in the argon pump. The third valve is, for example, a crude argon tower vent valve, which is used to control the pressure at the outlet of the crude argon tower.

[0026] like Figure 2As shown in the example, preferably, before step 101, the relevant valves on the pure argon tower can be opened manually to the specified positions, such as: the pure argon tower condenser pressure control valve PCV704 is fully opened, the pure argon tower liquid air valve HV706 is automatically set to the high limit of 40%, the pure argon tower liquid air return valve LCV703 is automatically set to the liquid level, the pure argon tower waste gas venting PCV703 is automatically set, the pure argon inlet solenoid valve FCV701 is energized, the valve is opened by 50% and the valve low limit is 30%, the pure argon tower bottom liquid level is automatically set, the pure argon inlet evaporator liquid level control valve LCV705 is automatically set to the liquid level, and the pure argon evaporator return valve FDV702 is opened by 50%.

[0027] like Figure 3 As shown in the example, preferably, in step 101, the liquid level in the crude argon tower is automatically accumulated to the preset liquid level within the preset time, including: adopting staged speed change control for different liquid level intervals in the crude argon tower; wherein the liquid level interval can be set to the interval from the plate immersion height to the preset liquid level.

[0028] For example, if the initial height is 0 mm and the plate immersion height is 600 mm, then in the two intervals from 0 mm to 600 mm and from 600 mm to the preset liquid level, the first valve automatically adjusts the size of its own opening to change the speed of the liquid level rise. For example, starting from a liquid level of 0 mm, the liquid level is increased at a relatively slow rate. At this stage, it is necessary to introduce cold energy more cautiously to avoid a sudden influx of cold energy into the crude argon tower. If the cold energy is introduced too quickly, it may have a greater impact on the temperature balance of the entire argon system, affect the normal operation of the main cooling, and may even cause problems such as the main cooling liquid level being too low. When the liquid level reaches 600 mm, it will be adjusted to another rate according to actual conditions during the process of rising to the preset liquid level.

[0029] like Figure 4 As shown in the example, preferably, before step 102, the automatic control method also includes: pre-cooling confirmation of the argon pump, including checking the pump body temperature confirmation, sealing condition and pipeline connection status confirmation, starting the argon pump, and making it load the frequency to a given frequency value according to the set time.

[0030] Preferably, setting the second valve to the automatic control mode includes: loading the frequency of the argon pump to a given frequency value according to a preset time; if the frequency of the argon pump is greater than a frequency threshold during loading, or the pressure of the second valve is lower than a pressure threshold and the duration exceeds a given value, the startup fails, the valve is unloaded, and the pre-cooling confirmation is performed again; if the frequency reaches the given frequency value, the second valve is set to the automatic control mode.

[0031] For example, Figure 5As shown in the example, when the frequency threshold is 30HZ, the pressure threshold is 0.15MPa, and the given time value is 180 seconds, during the loading process of the argon pump, if the frequency of the argon pump is greater than 30HZ and the outlet pressure of the pump is lower than 0.15MPa for 180 seconds, the argon pump will not start successfully. At this time, it is necessary to stop loading and re-precool the argon pump. In this way, the operating state of the argon pump can be accurately controlled.

[0032] Preferably, step 103 includes: monitoring the flow rate and pressure at the outlet of the crude argon tower; and controlling the opening of the third valve by low selection according to the comparison of the flow rate and pressure with the set value to adjust the flow rate entering the pure argon tower.

[0033] In a preferred embodiment of the present invention, the third valve adopts a dual controller low selection strategy. When controlling the flow into the pure argon tower, the given flow setting value is 50% of the design value. The PID action mode of the valve is that when the flow rate is lower than the set value, the valve opens wide, otherwise it closes narrowly; in terms of pressure control, the given pressure setting value is lower than 50% of the normal working pressure. When the flow control signal and the pressure control signal are considered at the same time, the low selection strategy can ensure that the system preferentially meets the control requirements with stricter constraints. For example, at a certain moment, according to the flow control calculation, the valve should be opened at 40%, and according to the pressure control calculation, the valve should be opened at 30%. Through the low selection strategy, the system will select an opening of 30% to control the third valve. The purpose of this is to prevent the crude argon tower from experiencing situations such as too low flow leading to nitrogen accumulation (nitrogen plugging), too high flow not conducive to oxygen washing, or too high pressure causing overpressure risks, thereby ensuring the safe and stable operation of the crude argon tower.

[0034] Preferably, step 104 comprises: resetting the liquid level setting value of the crude argon tower to an initial value according to the stop signal; and automatically withdrawing the load of the crude argon tower until the operation stops.

[0035] In a preferred embodiment of the present invention, when the argon system receives a stop signal, the liquid level setting value of the crude argon column is reset to an initial value, such as 0, and then the liquid level decreases to 0 according to the set time, and the crude argon column load is automatically and slowly withdrawn. This slow stop method can make the crude argon column stop smoothly and avoid the system shock that may be caused by a sudden stop.

[0036] Preferably, the automatic control method further comprises: when the argon pump fails or cavitation occurs, the crude argon tower is cut off and the crude argon tower is isolated. The argon pump failure includes: the lower tower liquid level of the crude argon tower is greater than the alarm value, and the pressure of the second valve is lower than a given value; the operation signal of the argon pump is lost.

[0037] For example, Figure 3As shown in the example, the pressure setting value is 0.38Mpa, for example. When the liquid level in the lower tower of the crude argon tower is greater than the alarm value, and the pressure of the second valve is lower than 0.38Mpa, or the operation signal of the argon pump is lost, the pulse setting will be 0, that is, the entire argon system will be controlled to stop running. The above technology, by combining equipment operation data, can more accurately predict the failure and maintenance needs of the argon pump, perform maintenance and maintenance in advance, and avoid long-term downtime and production losses caused by argon pump failure.

[0038] The automatic control method for the operation of the argon system of the air separation unit with liquid air as the cold source provided by the present invention can realize the automatic control of the whole process, and no subsequent manual intervention is required from the start to the output of the argon product, which greatly improves the operation efficiency and reduces the human uncertainty; wherein, the first valve accurately accumulates the liquid level according to the program, automatically controls the accumulated liquid condensation process, slowly and accurately, effectively avoids the cold shock, and lays a solid foundation for the subsequent argon purification. At the same time, the argon pump precooling and start-up loading are all automated, and the frequency and pressure are closely monitored during loading to ensure stable operation to establish the argon circulation volume, and can automatically and quickly handle any faults; furthermore, the second valve uses a dual-controller low-selection strategy to intelligently and accurately adjust the opening according to the flow and pressure requirements, eliminates the hidden dangers of nitrogen accumulation and overpressure, maintains the stable operation of the crude argon tower and helps argon purification.

[0039] An embodiment of the present invention further provides a control device, which may include: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the above-mentioned automatic control method.

[0040] The embodiment of the present invention further provides an automatic control system for the operation of an argon system using liquid air as a cold source in an air separation unit, wherein the argon system comprises a crude argon tower, a pure argon tower, an argon pump arranged on a connecting pipe between the crude argon tower and the pure argon tower, a first valve arranged at a preset position of an inlet of the crude argon tower, a second valve arranged at a preset position of the argon pump, and a third valve at a preset position of an outlet of the crude argon tower. The automatic control system comprises: a DCS control unit, comprising the above-mentioned control device, for receiving a manual start-up instruction and controlling the automatic operation of the crude argon tower; a liquid level monitoring and control module, electrically connected to the first valve and the second valve, for monitoring and controlling the liquid level in the crude argon tower; an argon pump control module, for adjusting the frequency of the argon pump; a dual controller low selection module, comprising a pressure controller and a flow controller, the control device also being used for a PID controller low selection strategy based on pressure and flow, and adjusting the flow entering the pure argon tower by controlling the dual controller low selection module and the third valve; a fault detection and processing module, for monitoring the operating status of the argon pump, and automatically cutting off the crude argon tower when a fault occurs in the argon pump.

[0041] Preferably, the argon pump control module is connected to the frequency conversion controller, and the argon pump control module can send control instructions to the frequency conversion controller, and the frequency conversion controller adjusts the frequency of the argon pump according to the control instructions.

[0042] like Figure 6 As shown in the example, preferably, when the fault detection and processing module monitors the flow rate and pressure of the third valve, the pressure controller and the flow controller will respectively send control signals to the DCS control unit, and then the DCS control unit will compare the sizes of the two signals and then select the smaller signal to control the opening of the third valve.

[0043] The detailed introduction content and technical effects of the automatic control system provided in the embodiment of the present invention are similar to those in the embodiment of the automatic control method. You can refer to the embodiment of the automatic control method and will not repeat them here.

[0044] The automatic control system also includes FB program blocks based on SIEMENS PCS 7, which are integrated in the DCS control unit to achieve adaptive adjustment and optimized operation of the system.

[0045] The FB program block based on SIEMENS PCS 7 can sense argon pump failure or other operating condition changes in real time, automatically cut off the crude argon tower and perform adaptive adjustments to maintain the cooling balance of the main tower, ensuring the continuous and stable operation of the entire air separation unit.

[0046] According to the control method, device and system of the argon system of the air separation unit with liquid air as the cold source provided by the invention, the whole process is automated and controlled, and no subsequent manual intervention is required from startup to the output of argon products, which greatly improves the operation efficiency and reduces human uncertainty. The first valve can automatically and accurately control the condensation process of accumulated liquid, slowly and accurately, and effectively avoids the shock of cold capacity. The precooling and startup loading of the argon pump are automated, and the frequency and pressure are closely monitored during loading to ensure stable operation to establish the argon circulation volume, and can automatically and quickly handle faults. The third valve can intelligently and accurately adjust the opening according to the flow and pressure requirements, eliminate hidden dangers such as nitrogen accumulation and overpressure, maintain the stable operation of the crude argon tower and assist in the purification of argon. The automatic control system can also sense the failure of the argon pump or other changes in operating conditions in real time, automatically cut off the crude argon tower, etc. for adaptive adjustments to ensure the balance of cold capacity of the main tower and maintain the stable operation of the entire air separation unit.

[0047] It should be understood that in various embodiments of the present invention, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0048] In addition, the terms "system" and "network" are often used interchangeably in this article. The term "and / or" in this article is only a description of the association relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0049] It should be understood that in the embodiment of the present invention, "B corresponding to A" means that B is associated with A, and B can be determined according to A. However, it should also be understood that determining B according to A does not mean determining B only according to A, and B can also be determined according to A and / or other information.

[0050] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in terms of function in the above description. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0051] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0052] In the several embodiments provided in the present application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, or it can be an electrical, mechanical or other form of connection.

[0053] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the embodiments of the present invention.

[0054] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0055] Through the description of the above embodiments, it can be clearly understood by those skilled in the art that the present invention can be implemented in hardware, firmware, or a combination thereof. When implemented using software, the above functions can be stored in a computer-readable medium or transmitted as one or more instructions or codes on a computer-readable medium. Computer-readable media include computer storage media and communication media, wherein the communication media include any medium that facilitates the transmission of computer programs from one place to another. The storage medium can be any available medium that can be accessed by a computer. Taking this as an example but not limited to: a computer-readable medium may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, disk storage medium or other magnetic storage device, or any other medium that can be used to carry or store the desired program code in the form of an instruction or data structure and can be accessed by a computer. In addition. Any connection can be appropriately a computer-readable medium. For example, if the software is transmitted from a website, server or other remote source using a coaxial cable, optical fiber cable, twisted pair, digital subscriber line (DSL) or wireless technologies such as infrared, radio and microwave, then the coaxial cable, optical fiber cable, twisted pair, DSL or wireless technologies such as infrared, wireless and microwave are included in the fixing of the medium. As used in the present invention, disk and disc include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and blue-ray disc, wherein disk usually reproduces data magnetically, while disc uses laser to reproduce data optically. The above combination should also be included in the scope of protection of computer-readable media.

[0056] In short, the above is only a preferred embodiment of the technical solution of the present invention, and is not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An automatic control method for the operation of an argon system of an air separation unit using liquid air as a cold source, characterized in that: The argon system includes a crude argon tower, a pure argon tower, an argon pump provided on a connecting pipe between the crude argon tower and the pure argon tower, a first valve provided at a preset position of an inlet of the crude argon tower, a second valve provided at a preset position of the argon pump, and a third valve provided at a preset position of an outlet of the crude argon tower. The automatic control method includes: During the system startup phase, the first valve is set to an automatic mode so that the liquid level in the crude argon column automatically accumulates to a preset liquid level within a preset time; When the liquid level in the crude argon column reaches the preset liquid level, starting the argon pump and setting the second valve to an automatic control mode so that the liquid in the crude argon column flows into the pure argon column; When the liquid flows into the pure argon tower, the PID controller based on pressure and flow rate selects a low strategy, and adjusts the flow rate of the liquid entering the pure argon tower by controlling the third valve; When the stop signal is received, the argon system is controlled to stop operating.

2. The automatic control method according to claim 1, characterized in that: The step of causing the liquid level in the crude argon column to automatically accumulate to a preset liquid level within a preset time includes: The first valve is used to control the different liquid level intervals in the crude argon tower by staged speed change.

3. The automatic control method according to claim 1, characterized in that: Before starting the argon pump, the automatic control method further comprises: The argon pump is pre-cooled and confirmed, including the pump body temperature, sealing condition and pipeline connection status.

4. The automatic control method according to claim 3, characterized in that: The step of setting the second valve to the automatic control mode comprises: According to the preset time, the frequency of the argon pump is loaded to a given frequency value; If the frequency of the argon pump during loading is greater than the frequency threshold, or the pressure of the second valve is lower than the pressure threshold and the duration exceeds a given value, the startup is unsuccessful, and the system is unloaded and the precooling confirmation is performed again; If the frequency reaches the given frequency value, the second valve is set to the automatic control mode.

5. The automatic control method according to claim 1, characterized in that: The PID controller low selection strategy based on pressure and flow, and regulating the flow rate of liquid entering the pure argon tower by controlling the third valve, includes: monitoring the flow rate and pressure at the outlet of the crude argon column; By comparing the flow rate and pressure with the set values, the opening of the third valve is controlled in a low-selective manner to adjust the flow rate of liquid entering the pure argon tower.

6. The automatic control method according to claim 1, characterized in that: When the stop signal is received, the argon system is controlled to stop running, comprising: According to the stop signal, the liquid level setting value of the crude argon column is reset to an initial value, The load of the crude argon column is automatically withdrawn until the operation is stopped.

7. The automatic control method according to claim 1, characterized in that: The automatic control method further comprises: When the argon pump fails or cavitation occurs, the crude argon column is isolated.

8. The automatic control method according to claim 7, characterized in that: Determining that the argon pump fails includes: The liquid level in the lower tower of the crude argon tower is greater than the alarm value, and the pressure of the second valve is lower than a given value; or The operating signal of the argon pump is lost.

9. A control device, characterized in that: The control device includes: a memory, a processor, and a computer program stored in the memory and executable on the processor, and the processor executes the computer program to implement the automatic control method according to any one of claims 1 to 7.

10. An automatic control system for the operation of an argon system in an air separation unit using liquid air as a cooling source, characterized in that: The argon system includes a crude argon tower, a pure argon tower, an argon pump provided on a connecting pipe between the crude argon tower and the pure argon tower, a first valve provided at a preset position of an inlet of the crude argon tower, a second valve provided at a preset position of the argon pump, and a third valve provided at a preset position of an outlet of the crude argon tower. The automatic control system includes: a DCS control unit, comprising the control device of claim 9, for receiving a manual start-up instruction and controlling the automatic operation of the crude argon column; a liquid level monitoring and control module, electrically connected to the first valve and the second valve, for monitoring and controlling the liquid level in the crude argon column; An argon pump control module, used for adjusting the frequency of the argon pump; A dual-controller low-selection module, including a pressure controller and a flow controller, wherein the control device is also used for a PID controller low-selection strategy based on pressure and flow, and adjusts the flow entering the pure argon tower by controlling the dual-controller low-selection module and the third valve; The fault detection and processing module is used to monitor the operating status of the argon pump and automatically cut off the crude argon tower when the argon pump fails.

Images