JPH03282182A - Air liquefying separator and controlling method therefor - Google Patents

Abstract

PURPOSE:To automate a part requiring an operator's judgement and to efficiently alter an operation mode by recognizing a present operation pattern based on the flow rate, concentration, etc., of air and liquid of respective sections of an apparatus, inferring, calculating and controlling optimum operation data of the sections based on it. CONSTITUTION:Control means 9 is composed of a distributed controller 9a and inferring and calculating means 9b made of an expert system. The controller 9a supplies various input information such as flow rate, concentration, pressure, temperature and product collecting target value, etc., to be obtained from various devices and operates control units based on the flow rate set values of the sections output from the means 9b. The means 9b recognizes a present operation pattern based on various information received from the controller 9a, infers an optimum operation pattern from operating conditions such as a previous operation command, latest operation command and operating capacity of devices for forming an apparatus, calculates and controls operation data of the sections such as optimum product collecting amount, circulating liquid amount, expansion turbine flow rate, etc., based on the inference.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method for controlling an air liquefaction separation device, and more specifically, the present invention relates to a method for controlling an air liquefaction separation device, and more specifically, to convert products such as oxygen and nitrogen into gaseous and/or The present invention relates to a control method for an air liquefaction separation device that can increase or decrease the production amount, change the operating mode, etc. efficiently in a short time in a device that produces liquid, and can obtain the optimum production amount.

[Conventional technology]

BACKGROUND ART Conventionally, a distributed control system (DCS) has been widely used as a means for controlling the flow rate of each part of an air liquefaction separation apparatus to a predetermined value depending on the output amount of a product.

In conventional control using DCS, when the target product output amount increases or decreases due to demand fluctuations, for example, when increasing or decreasing the amount of oxygen gas to be extracted, the DCS uses the changed amount of oxygen gas to be extracted.
Enter the feed air amount.

The amount of turbine fluid, the amount of nitrogen extracted, and the flow rates of other parts are set to predetermined values commensurate with the changed oxygen amount, and the valves of each part are controlled according to a predetermined time constant so that they reach the set value. Furthermore, after reaching the Se Soto value, any deviations in product purity or heat balance are corrected using a feedback method.

[Problem to be solved by the invention]

However, with the control method that only changes the amount of product sampled as described above, although it is possible to automatically change the operation, the operation mode is extremely limited, and the deviations in product purity and heat balance that occur after correction. You may have to make multiple revisions based on
In order to obtain the optimum operating conditions, it may take a long time or it may be necessary to perform operations at the expense of yield.

Therefore, when changing the operating mode, understand the current operating state, consider conditions such as the equipment's weight loss limit and the necessity of liquid production, and ensure that the change target is met and the operation after the change is optimal. It is desirable to set operating conditions in such a way as to make detailed judgments and to perform operations based on these judgments, such as setting operating conditions in the shortest possible time. However, at present, these judgments and operations largely depend on the skills of skilled operators, and the lack of successors has become a problem.

The present invention has been developed in view of the above-mentioned circumstances.The present invention aims to improve operational accuracy by automating parts that conventionally require judgment based on the operator's experience. The purpose of this invention is to provide a device and a method for controlling the same.

[Means to solve the problem]

In order to achieve the above object, the air liquefaction separation device of the present invention separates compressed, purified, and cooled raw material air by liquefaction rectification to derive product gases such as oxygen and nitrogen, product liquefied gases, and exhaust gases. In the liquefaction separation equipment, (a) flow rate and/or purity of each part such as air volume, product volume, turbine volume, reflux liquid volume, etc. for detecting the real-time operating state of the equipment;

means for measuring the liquid level; (b) calculation means for recognizing the operating state of the device based on the information from the measuring means and inferring optimal operating conditions and operation transition operation method in the shortest time based on the operating command; (c) The apparatus is characterized by comprising: a control means for commanding the control of each part of the apparatus according to the calculation result; and a controller for controlling operating specifications such as flow rate of each part of the apparatus according to signals from the control means.

In addition, in the control method of the air liquefaction separation device of the present invention, raw air is compressed, purified, cooled, and introduced into a rectification column, and product gases such as oxygen and nitrogen, product liquefied gas, and exhaust gas are produced by liquefaction rectification separation. In a method of controlling an air liquefaction separation device to extract
The raw material air and product gas.

In addition to recognizing the current operating pattern based on the operating specifications such as the flow rate of each part of the product liquefied gas and exhaust gas, it also recognizes the operating conditions such as the previous operating command, the latest operating command, and the operating capacity of the equipment that makes up the equipment. Infer optimal driving patterns,
Calculate and control the operating specifications of each part, such as the optimal product collection amount, reflux liquid volume, expansion turbine flow rate, etc. based on this inference. Recognize the current operating pattern based on the flow rate of each part, such as product liquefied gas and exhaust gas. At the same time, the optimal operation pattern is inferred from the latest operation command, the operation pattern at the time of the command, the target amount of product to be collected, and the operating conditions such as the operating capacity of the equipment that makes up the device, and the optimal amount of product to be collected is determined based on the inference. , the flow rate of each part, such as the amount of reflux liquid and the flow rate of the expansion turbine, is calculated.

Furthermore, the apparatus and method of the present invention are characterized in that the amount of product in the product storage tank attached to the air liquefaction separation apparatus and/or the product storage tank supplied with the product from the apparatus can also be controlled.

〔Example〕

Hereinafter, the present invention will be explained in more detail based on an embodiment shown in the drawings.

This air liquefaction separation device 1 includes a compressor 2. Purification stage #3. Feed air A cooled to near the liquefaction point via the main heat exchanger 4
an argon column 6 connected to the upper column 5a of the double rectification column 5, a main condenser-evaporator 7 disposed at the bottom of the upper column 5a, and an upper column 5b of the double rectification column 5. The expansion turbine 8 uses nitrogen gas to be separated as a working fluid.

As is well known, the air liquefaction separator 1 performs liquefaction rectification separation using air as a raw material, and the products are oxygen gas GO at the bottom of the upper column, nitrogen gas GN at the top of the upper column, liquefied oxygen LO at the bottom of the upper column, and main condensate. Main condenser generator liquefied liquefied nitrogen LN,
Crude argon AR is produced in the upper part of the argon column, and exhaust gas W is discharged from the upper part of the upper column, and nitrogen gas N is discharged from the upper part of the lower column via an expansion turbine 8.

In the present invention, in order to maintain the air liquefaction separation apparatus 1 configured as described above in an optimal operating state according to product demand, various controllers, measuring instruments 1 analyzers, etc. are arranged in each part, and these It is equipped with a control means 9 that operates each of the measurement controllers and controls the flow rate of each part based on information obtained from each device and each predetermined setting value. This control means 9 uses a control computer and/or an expert system. In addition, d in the figure is data (information)
Indicates input and output.

First, the pipe line 10 that supplies the raw material air A is provided with a measurement controller 30 that includes a flow meter 30a that measures the flow rate of the raw material air A and a guide vane 30b. This measurement controller 30 controls the flow rate of the raw material air A and the guide vane 30b.
outputs the opening degree to the control means 9, and opens and closes the guide vane 30b according to instructions from the control means 9 to control the supply amount of the raw material air A, and is calculated according to the production amount of the product oxygen gas GO. The value set is the set value. Note that the flow rate can be controlled in the same manner by providing an automatic valve in the conduit instead of the guide vane 30b.

A measurement controller 31 consisting of a flow meter 31a and an automatic valve 31b for measuring the flow rate of the product oxygen gas GO is provided in the conduit 11 that leads out the product oxygen gas Go. This measurement controller 31 controls the flow rate of the product oxygen gas GO and the automatic valve 31.
The opening degree of b is output to the control means 9, and the automatic valve 31b is opened and closed according to instructions from the control means 9 to control the production amount of the product oxygen gas GO, depending on the demand for the product oxygen gas GO. The calculated value becomes the set value, and the oxygen purity is finely adjusted to maintain the specified value. In connection with the product oxygen gas measurement controller 31, an analyzer 31C for measuring the purity of the product oxygen gas GO is provided near the product oxygen gas outlet of the upper column 5a. It is output to.

A measurement controller 32 consisting of a flow meter 32a and an automatic valve 32b for measuring the flow rate of the product nitrogen gas GN is provided in the pipe line 12 that leads out the product nitrogen gas GN. This measurement controller 32 controls the automatic valve 32 along with the flow rate of the product nitrogen gas GN.
The opening degree of b is output to the control means 9, and the automatic valve 32b is opened and closed according to instructions from the control means 9 to control the production amount of product nitrogen gas GN, which is calculated according to the supply amount of raw material air A. The value set is the set value.

Crude argon A is connected to the pipe line 13 that leads out crude argon AR.
A measurement controller 33 consisting of a flow meter 33a for measuring the flow rate of R and an automatic valve 33b, and an analyzer 33c for measuring the oxygen concentration in the crude argon are provided. The measurement controller 33 outputs the flow rate of the crude argon AR and the opening degree of the automatic valve 33b to the control means 9, and controls the output amount of the crude argon AR by opening and closing the automatic valve 33b according to instructions from the control means 9. The value calculated according to the supply amount of raw air A becomes the set value, and the crude argon AR is Finely tuned to maximize production.

In addition, a liquefied crude argon tank (L A T + ) 50 a fr is attached to this air liquefaction separation device 1.
<If provided and/or a liquefied crude argon tank (LAT2) to which liquefied crude argon is supplied from the device
If 50b is provided, these lff115
A means for detecting and measuring the amount of crude argon AR of 0 a, 50 b is provided, such as a liquid level gauge, a pressure gauge, etc., and the data obtained by the measuring means is also transmitted to the control means 9, and the data related to each of the above data is The device can be configured to control each part of the device by controlling the device.

A measurement controller 34 consisting of a flow meter 34a and an automatic valve 34b for measuring the flow rate of the liquefied oxygen LO is provided in the conduit 14 that leads out the liquefied oxygen LO.

This measurement controller 34 outputs the flow rate of liquefied oxygen LO and the opening degree of the automatic valve 34b to the control means 9, and opens and closes the automatic valve 34b according to instructions from the control means 9 to control the output amount of liquefied oxygen LO. It is controlled to maintain a preset value or cold balance.

In addition, like the liquefied crude argon mentioned above, a liquefied oxygen tank (LOT+) is attached to this air liquefaction separation bag f1.
51a and/or a liquefied oxygen tank (LOT2) 5 supplied with liquefied oxygen LO from the device.
1b, these storage tanks 51a, 5
A means for detecting and measuring the amount of liquefied oxygen LO of 1b is provided, such as a liquid level gauge, a pressure gauge, etc., and the data obtained by the measuring means is also transmitted to the control means 9, and each part of the apparatus is can be configured to control the

A measurement controller 35 consisting of a flow meter 35a and an automatic valve 35b for measuring the flow rate of the liquefied nitrogen LN is provided in the conduit 15 that leads out the liquefied nitrogen LN.

This measurement controller 35 outputs the flow rate of liquefied nitrogen LN and the opening degree of the automatic valve 35b to the control means 9, and opens and closes the automatic valve 35b according to a command from the control means 9 to control the output amount of liquefied nitrogen LN. The flow rate of the expansion turbine fluid is controlled to a preset value or to maintain the refrigeration balance and purity, and also to maintain the purity of the refluxed liquefied nitrogen in the lower column 5b. Controlled by

In the case of liquefied nitrogen LN, the air liquefaction separation device 1 is also provided with a liquefied nitrogen tank (LNT+) 52a as an accessory equipment, and/or the liquefied nitrogen tank (LNT2) 52b receives the liquefied nitrogen LN from the device. is provided, a means for detecting and measuring the amount of liquefied nitrogen LN in these storage tanks 52a and 52b, such as a liquid level gauge or a pressure gauge, is provided, and the data obtained by the measuring means is also controlled by the control means. 9 and control each part of the apparatus in association with each of the above-mentioned data.

Further, similar control can be performed not only for liquid products but also for gas products. Regarding each product tank mentioned above, a tank attached to a device means a tank connected to the device by piping, and a tank to which the product is supplied refers to a tank that may receive the product by lorry, etc. This refers to a tank with a tank that is supplied with products only from this device, as well as tanks that are supplied with products from multiple air liquefaction separation devices.

The pipe line 16 that introduces nitrogen gas N into the expansion turbine 8 includes
Flowmeter 368 and automatic valve 3 for measuring the flow rate of the nitrogen gas N
A measurement controller 36 consisting of 6b is provided. This measurement controller 36 controls the flow rate of nitrogen gas N and the automatic valve 36.
The opening degree of b is output to the control means 9, and the automatic valve 36b is opened and closed according to instructions from the control means 9 to control the amount of fluid introduced into the expansion turbine, and the value calculated from the amount of raw air becomes the set value. It is controlled by a value set in relation to the refrigeration liquefied nitrogen flow rate depending on the cooling balance and the operational purpose.

The pipe line 17 that introduces the reflux liquid into the upper column 5a includes the pipe line 1.
A measurement controller 37 consisting of a flow meter 37a and an automatic valve 37b for measuring the flow rate of liquefied nitrogen in the tank 7 is provided. This measurement controller 37 controls the automatic valve 37 along with the flow rate of liquefied nitrogen.
The opening degree of b is output to the control means 9, and the automatic valve 37b is opened and closed according to instructions from the control means 9 to control the amount of reflux liquid, and the value calculated from the raw material air amount becomes the set value and is controlled. Ru.

The pipe line 18 that introduces the liquefied air at the bottom of the lower column 5b into the upper column 5a is provided with an automatic valve 38b that controls the flow rate of the liquefied air, and a liquid valve is installed at the bottom of the lower column to measure the liquid level at the bottom. A face meter 38c is provided. This automatic valve 38
A measurement controller 38 consisting of a liquid level gauge 38a and a liquid level gauge 38a controls the opening degree of the automatic valve 38 according to the liquid level height of the liquefied air at the bottom of the lower column, so that the liquid level at the bottom of the lower column remains constant. controlled by.

In addition, in the pipe line 19 that introduces the liquefied air at the bottom of the lower column to the condenser 6a of the crude argon column 6, there is a measurement controller 3 that includes a flow meter 39a that measures the flow rate of the liquefied air and an automatic valve 39b.
9 is provided. This measurement controller 39 is connected to the condenser 6
The opening degree of the automatic valve 39b is outputted to the control means 9 together with the flow rate of the liquefied air introduced into the a, and the automatic valve 39b is opened and closed according to instructions from the control means 9 to control the amount of liquefied air.
The value calculated from the raw material air amount becomes the set value and is controlled.

An analyzer 4o for measuring the oxygen concentration in the exhaust gas is provided in the pipe 2o that discharges the exhaust gas W from the upper part of the upper column, and the oxygen concentration contained in the exhaust gas in the pipe 20 is sent to the control means 9. Output. Further, the pipe line 20 is provided with a measurement controller 41 consisting of a flow meter 418 and an automatic valve 41b for controlling the flow rate of exhaust gas.

The control means 9 is composed of a distributed control device 9a and an inference calculation means 9b consisting of an AI station (expert system).

The distributed control device 9a supplies various input information such as flow rate, concentration, pressure, temperature, and product sampling target value obtained from the various devices mentioned above to the inference means 9b, and also inputs information from each section outputted from the inference calculation means 9b. The respective controllers are operated based on the flow rate set value.

The inference calculation means 9b recognizes the current driving pattern based on various information received from the distributed control device 9a, and also recognizes the previous driving command, the latest driving command, and the driving ability of the equipment constituting the device. The optimum operating pattern is inferred from the operating conditions, and based on the inference, the optimum operating specifications of each part, such as the optimum product collection amount, reflux liquid amount, and expansion turbine flow rate, are calculated and controlled.

That is, the distributed control device 9a is configured to provide data necessary for inference by the inference calculation means 9b to the inference calculation means 9b, and control each part based on the data received and received from the inference calculation means 9b. .

Here, the operation of the inference calculation means 9b when changing the driving mode will be explained. First, the inference calculation means 9b compares the operating specifications such as the flow rate of each part received from the distributed control device 9a with the optimum flow rate for each operating pattern set in advance, and recognizes the current operating pattern. After shifting to operation according to the new command, it is inferred whether the operation according to the previous command can be continued or whether it should be changed. This reasoning is based on priority matters, such as the purity and production amount of product oxygen, the amount of raw material air associated with this, and ensuring the optimal material balance and heat balance, such as the amount of product taken in each operation mode. The system selects the optimal operation pattern based on information such as the weight loss limit of the feed air compressor, the demand for liquefied gas products, and the previous operation command, and also adjusts the time constant until operation transition according to the amount of change. Set.

For example, if a command is given to reduce oxygen gas, and the previous command was for liquefied nitrogen sampling operation, the amount of nitrogen gas that should be secured when the amount of raw air is reduced according to the amount of oxygen gas collected, and the air compressor's reduction limit. Infer the flow rate of each part, such as the amount of liquefied nitrogen and reflux liquid collected from etc., the flow rate of the expansion turbine, etc. As a result, the flow rate of each part is controlled so that it reaches the value set by each time constant. In order to deal with deviations in product purity and heat balance that occur after the set values are reached, it is inferred from the current operating pattern which parts should be corrected and to what extent, and control is performed based on the results. For example, in the case of operation in which no liquid product is sampled, the turbine fluid position set value is finely adjusted in relation to the flow rate of each part so that the flow rate or valve opening of the heat balance adjustment system falls within a predetermined range.

In addition, the demand information for the above liquefied gas products is not limited to the storage tank attached to the air liquefaction separation device, but also the liquid storage capacity of multiple storage tanks, for example, many storage tanks at liquefied gas supply bases installed in various places. By incorporating amount information online, it is possible to set the amount of liquid product to be collected, including demand information based on fluctuations in the amount of liquid held.

By controlling the operating specifications such as the flow rate of each part in this manner, it becomes possible to efficiently collect various products, and it becomes possible to switch to the optimum operating state in a short time. In addition to changing the operating mode during equipment operation, it is also possible to control specifications such as the flow rate of each part when starting the equipment, reducing startup time and increasing the production efficiency of the air liquefaction separation equipment. can be significantly improved.

Note that the flow of gas and liquid in each part of the device is similar to that of a general air liquefaction separation device, so a detailed explanation will be omitted. In addition, the configuration of the air liquefaction separation device is not limited to the above-mentioned example, but can also be configured with various conventionally used capacity improvement equipment.
It is possible to apply the present invention, and the products mentioned in the examples are not all limited to those that are co-produced.

It goes without saying that the operating specifications can also be controlled not only in terms of flow rate, concentration (purity), and liquid level, but also in terms of temperature and pressure.

〔Effect of the invention〕

As explained above, the method for controlling the air liquefaction separation equipment of the present invention recognizes the current operating pattern based on the flow rate and concentration of gas and liquid in each part of the equipment, and based on this, the optimal operating pattern for each part. Since the source is inferred, calculated, and controlled, each product can be produced under the optimal operating conditions for each operating pattern, and the yield of each product can be improved. In particular, it is possible to quickly shift operating modes due to fluctuations in product demand or changes in the amount of product in the storage tank, and it is possible to take over the setting of complex operating conditions that previously relied on the skill level of operators, and as operators become older.

It can also respond to social demands such as the lack of successors.

[Brief explanation of the drawing]

The figure is a system diagram of an air liquefaction separation device showing one embodiment of the present invention. 1... Air liquefaction separation device 2... Compressor 3.
...Refining equipment 4...Main heat exchanger 5...Double rectification column 6...Argon column 7...Main condensing evaporator
8... Expansion turbine 9... Control means 9a...
・Distributed control device 9b...Inference calculation means 30
, 31, 32.36, 34.35, 36, 37, 38.
39°41...Measurement controller 40...Analyzer
A... Raw air AR... Crude argon GO.
...Oxygen gas GN...Nitrogen gas LO...Liquefied oxygen LN...Liquefied nitrogen W...Exhaust gas

Claims (1)

[Scope of Claims] 1. In an air liquefaction separation device for extracting product gases such as oxygen and nitrogen, product liquefied gas, and exhaust gas by liquefaction rectification separation of compressed, purified, and cooled raw material air, (a) Means for measuring the flow rate and/or purity and liquid level of each part such as air volume, product volume, turbine volume, and reflux liquid volume to detect real-time operating conditions; (b) Based on information from the above measuring means; (c) a control means for instructing the control of each of the above parts based on the calculation results; and (c) a calculation means for recognizing the operating state of the device and inferring the optimum operating conditions and operation transition operation method in the shortest time based on the operation command. An air liquefaction separation device comprising: a controller that controls operating specifications such as flow rates of each part of the device based on signals from the control means. 2. The measuring means includes a raw material air flow rate measurement controller, a product oxygen gas flow rate measurement controller, a product nitrogen gas flow rate measurement controller, a liquefied oxygen flow rate measurement controller, a liquefied nitrogen flow rate measurement controller, and an expansion device. Turbine fluid flow rate measurement controller, upper column reflux liquid liquefied nitrogen amount measurement controller, upper column liquefied air flow rate measurement controller, lower column bottom liquid level measurement controller, exhaust gas oxygen concentration measurement The air liquefaction separation device according to claim 1, wherein the air liquefaction separation device is a gas purification analyzer and a product gas purity analyzer. 3. The air liquefaction separation device is a device having a product storage tank attached to the air liquefaction separation device and/or a product storage tank that receives product supply from the air liquefaction separation device, and the amount of gas stored in the storage tank and/or or means for detecting and measuring the amount of stored liquid;
The air liquefaction separation apparatus according to claim 1, further comprising means for transmitting information obtained from the measuring means to the inference calculation means. 4. The recognition inference calculation means includes a control electronic computer and/or
The air liquefaction separation device according to any one of claims 1 to 3, wherein the air liquefaction separation device is an expert system. 5. Compress, refine, and cool the raw air and introduce it into the rectification column,
In a method for controlling an air liquefaction separation device that derives product gases such as oxygen and nitrogen, product liquefied gas, and exhaust gas by liquefaction rectification separation, the operation of the flow rate of each part of the raw material air, product gas, product liquefied gas, exhaust gas, etc. In addition to recognizing the current driving pattern based on the specifications, the optimal driving pattern is inferred from the previous driving command, the latest driving command, and driving conditions such as the driving ability of the equipment that makes up the device, and the optimal driving pattern is determined based on the inference. 1. A method for controlling an air liquefaction separation device, which comprises calculating and controlling operating specifications of each part, such as the amount of product to be collected, the amount of reflux liquid, and the flow rate of an expansion turbine. 6. The product gas amount and/or product liquefied gas in the product storage tank is determined by the product amount detection and measurement means installed in the product storage tank attached to the air liquefaction separation device and/or the product storage tank that receives product supply from the device. A claim characterized in that the amount is detected and measured, information obtained thereby is simultaneously introduced into the current driving pattern recognition, an optimal driving pattern is inferred, and driving specifications of each part are calculated and controlled. 5. The method for controlling an air liquefaction separation device according to 5. 7. The method of controlling an air liquefaction separation device according to claim 5 or 6, wherein the recognition and inference calculation of the optimum driving pattern is performed by an expert system.