EP3811012A1 - Système de contrôle d'un débit d'argon en sortie d'une colonne de distillation - Google Patents
Système de contrôle d'un débit d'argon en sortie d'une colonne de distillationInfo
- Publication number
- EP3811012A1 EP3811012A1 EP19740621.8A EP19740621A EP3811012A1 EP 3811012 A1 EP3811012 A1 EP 3811012A1 EP 19740621 A EP19740621 A EP 19740621A EP 3811012 A1 EP3811012 A1 EP 3811012A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- argon
- distillation column
- level
- assembly
- argon flow
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
- F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
- F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
- F25J3/04763—Start-up or control of the process; Details of the apparatus used
- F25J3/04769—Operation, control and regulation of the process; Instrumentation within the process
- F25J3/04793—Rectification, e.g. columns; Reboiler-condenser
- F25J3/048—Argon recovery
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
- F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
- F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
- F25J3/04406—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air using a dual pressure main column system
- F25J3/04412—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air using a dual pressure main column system in a classical double column flowsheet, i.e. with thermal coupling by a main reboiler-condenser in the bottom of low pressure respectively top of high pressure column
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
- F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
- F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
- F25J3/04642—Recovering noble gases from air
- F25J3/04648—Recovering noble gases from air argon
- F25J3/04654—Producing crude argon in a crude argon column
- F25J3/04666—Producing crude argon in a crude argon column as a parallel working rectification column of the low pressure column in a dual pressure main column system
- F25J3/04672—Producing crude argon in a crude argon column as a parallel working rectification column of the low pressure column in a dual pressure main column system having a top condenser
- F25J3/04678—Producing crude argon in a crude argon column as a parallel working rectification column of the low pressure column in a dual pressure main column system having a top condenser cooled by oxygen enriched liquid from high pressure column bottoms
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
- F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
- F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
- F25J3/04763—Start-up or control of the process; Details of the apparatus used
- F25J3/04769—Operation, control and regulation of the process; Instrumentation within the process
- F25J3/04848—Control strategy, e.g. advanced process control or dynamic modeling
Definitions
- the field of the invention relates to the control of a flow of argon at the outlet of a distillation column.
- the modification of the argon flow rate of a fluid at the outlet of a distillation column makes it possible to modify the oxygen content of this fluid and thus to improve its purity in argon. Distillation is carried out at cryogenic temperatures.
- Distillation is a process for separating the different constituents of a homogeneous liquid mixture.
- these constituents generally have separate boiling temperatures (or vaporization temperatures) so that, under the effect of the increase in temperature, the constituents of the liquid mixture will transform into gases at different temperatures, which allows to separate them from each other.
- Argon is an inert gas, for example it is used as an atmosphere for chemical reactions. Argon is also widely used in the manufacture of incandescent bulbs since it has the advantage of not reacting with the filament of the bulb.
- the purity of argon is very often characterized by the content of residual oxygen in the argon fluid obtained at the outlet of a distillation column and the improvement of the purity of argon is therefore a recurring problem.
- the methods and systems for improving the purity of argon do not take into account certain criteria such as the level of oxygen at the outlet of the distillation column, the delay inherent in the operation of the distillation column, external disturbances. or the bias introduced by the regulator (s) usually used.
- the present invention improves the situation.
- the invention in question here relates to a system for controlling a flow of argon from a fluid leaving a set of at least one distillation column in order to reach a target level of oxygen.
- the system includes:
- a sensor arranged to measure a level of oxygen in a fluid comprising argon at the outlet of the assembly of at least one distillation column
- a regulator arranged to determine a variation of argon flow required as a function of the difference between the level of oxygen measured by the sensor and a level of target oxygen
- a controller arranged to generate a control signal relating to a targeted argon flow rate, said targeted argon flow rate being determined as a function of the variation of required argon flow rate determined by the regulator and of variations in the dioxygen level measured by the sensor and
- a valve controlled by said controller, arranged to modify the argon flow rate of the fluid leaving the assembly of at least one distillation column to obtain the targeted argon flow rate.
- Variations in the flow rate of the fluid comprising argon at the outlet of the assembly of at least one distillation column have a direct impact on the oxygen level of this fluid.
- the system described here determines an argon flow, namely the targeted argon flow, to reach the target oxygen level.
- the assembly of at least one distillation column is supplied with an air fluid, the target argon flow rate determined by the controller being determined also as a function of a predictive value of the Argon flow rate as a function of the air flow rate at the inlet of the assembly of at least one distillation column and of the efficiency of said assembly.
- the predictive value of the argon flow rate is a function of a delayed air flow rate relative to the air flow rate at the inlet of the assembly of at least one distillation column, said d ' delayed air being defined as follows:
- Air Q * (0 Q C as air 3 ⁇ 4 ue Qair Qair CO O ⁇ S ⁇ R
- Qair (t) is the flow of air entering the set of at least one distillation column at time t
- R is a positive predetermined threshold
- the predictive value of the argon flow at a given instant is determined as follows:
- Qpred (t) is the predictive value of the argon flow at a given time t
- A is the proportion of argon in the air flow entering the assembly of at least one distillation column
- the efficiency of the assembly of at least one distillation column is determined by applying a predetermined function to a factor characterizing an amount of energy used for the operation of the assembly d '' at least one distillation column.
- the predetermined function is determined by a learning algorithm on the basis of a set of data relating to a plurality of distillation processes implemented according to different values of quantity of energy requested.
- the predetermined function is polynomial.
- the target argon flow rate is determined as a function of an anticipation parameter relating to variations in the level of oxygen measured by the sensor, said anticipation parameter taking discrete values in a set of predetermined values.
- the level of oxygen measured by the sensor is that of the fluid comprising argon at the outlet of the assembly of at least at least one distillation column.
- This fluid therefore comes from the upper part of a distillation column where the level of oxygen varies non-linearly.
- the regulator and more particularly a PID regulator, is not adapted to non-linearity and therefore does not make it possible to regulate satisfactorily the level of dioxygen leaving the assembly of at least one distillation column.
- such an anticipation parameter is complementary to the regulator and therefore corrects the approximations due to the non-linearity of the oxygen content in the upper part of a distillation column.
- the anticipation parameter relating to variations in the level of oxygen is defined as follows: or :
- P (t) is the value of the anticipation parameter relating to variations in the level of oxygen measured by the sensor at time t
- PV (t) is the value of the oxygen level measured by the sensor at time t
- the variations in the oxygen level when it is regulated by a regulator, and more specifically a PID regulator, are known in advance and therefore make it possible to determine the possible values of the anticipation parameter.
- the anticipation parameter relating to variations in the level of oxygen measured by the sensor is a corrective flow, the targeted argon flow being determined as follows:
- Qargon is the target argon flow
- Qpred is the predictive value of the argon flow
- a regui is a variation of argon flow required
- the anticipation parameter relating to the variations in the level of oxygen measured by the sensor is a weighting coefficient of the predictive value of the argon flow, the targeted argon flow being determined as follows :
- a regui is a variation of argon flow required
- the predictive value of argon flow rate is weighted by a corrective factor relating to disturbances of the assembly of at least one distillation column, said corrective factor being determined as a function of the difference between the oxygen level measured by the sensor and the target oxygen level.
- the corrective factor is defined as follows: r
- K K 2 if T 2 ⁇ PV (t) - SP ⁇ Ti
- Ki, K 2 and K 3 are possible predetermined values of the corrective factor, and Ti and T 2 are predetermined thresholds.
- the regulator is a PID regulator (“Proportional-Integral-Derivative”) configured so that the values of the parameters respectively relating to the proportional and integral contributions of the PID regulator are multiplied by two when the level of oxygen measured by the sensor is higher than the target oxygen level.
- PID regulator Proportional-Integral-Derivative
- the PID regulator is a PI regulator.
- the target oxygen level of the argon fluid leaving the assembly of at least one distillation column is less than 2 ppm.
- the target oxygen content of the argon fluid leaving the assembly of at least one distillation column is between 0.9 ppm and 2 ppm.
- the target oxygen level of the argon fluid leaving the assembly of at least one distillation column is equal to 0.9 ppm.
- the ratio of argon recovered at the outlet of the assembly of at least one distillation column depends directly on the level of dioxygen at the outlet of this assembly.
- a dioxygen level of 0.9 ppm represents the minimum value making it possible to reach a maximum ratio of argon recovered between the outlet fluid of the last distillation column of the assembly and the inlet fluid of this last column.
- the invention further relates to a method for controlling a flow of argon from a fluid leaving a set of at least one distillation column in order to reach a target level of oxygen.
- the method includes: - measuring a level of dioxygen in a fluid comprising argon at the outlet of the assembly of at least one distillation column,
- the invention also relates to a computer program comprising instructions for implementing the method described above, when these instructions are executed by at least one processor.
- Figure 1 illustrates a set of at least one distillation column and a system according to the invention comprising a sensor for measuring the oxygen level of a fluid in outlet of the assembly of at least one distillation column, a regulator, a controller and a valve;
- FIG. 2 illustrates the variations in the flow of an air fluid entering the assembly of at least one distillation column, as well as the variations in a delayed air flow used by the controller to determine a target argon flow rate of the fluid leaving the assembly of at least one distillation column;
- Figure 3 illustrates variations in the level of oxygen measured by the sensor at the outlet of the assembly of at least one distillation column
- FIG. 4 illustrates the regulator according to an embodiment in which the regulator is of the PID type
- Figure 5 illustrates the argon yield obtained as a function of the oxygen level of the fluid leaving the assembly of at least one distillation column
- Figure 6 illustrates a method of controlling the flow of argon from the fluid leaving the assembly of at least one distillation column according to the invention.
- Figure 1 illustrates an assembly 1 of at least one distillation column and a system 3 for controlling a flow of argon from a fluid leaving the assembly 1.
- the assembly 1 of at least one distillation column is arranged to implement one or more distillation processes of a homogeneous mixture of which one of the constituents is argon (chemical element of notation "Ar" in the periodic table of elements).
- the assembly 1 comprises several successive distillation columns, each implementing a distillation process, so that the fluid entering a distillation column is the fluid leaving the preceding distillation column.
- the assembly 1 is supplied, for example, by an air fluid.
- the air does indeed include argon.
- the argon content in the air is about 0.93%. It is therefore understood that this air fluid is injected as an inlet to the first distillation column 5 of the assembly 1 of at least one distillation column.
- other homogeneous mixtures comprising argon can be used as an entry for set 1.
- the assembly 1 comprises two distillation columns, namely a first distillation column 5 and a second distillation column 7.
- the first distillation column 5 is arranged to be supplied by an air flow 100 characterized by an air flow Q air .
- the air flow rate Q air of this fluid can be variable over time.
- FIG. 2 illustrates variations in the air flow rate Q air at the inlet of the assembly 1 of at least one distillation column, and more exactly at the inlet of the first distillation column 5.
- the first distillation column 5 is further arranged to implement a distillation process so as to emit a fluid 110.
- This fluid 110 has a higher argon content than the air fluid 100 at the inlet of the first distillation column 5.
- the second distillation column 7 is arranged to be supplied by the fluid 110.
- the fluid 110 is a gas at the outlet of the first distillation column 5 but is a liquid at the inlet of the second distillation column 7.
- the second distillation column 7 is further arranged to carry out a distillation process so as to emit, as illustrated in Figure 1, a fluid 120 at the outlet. This fluid has a higher argon content than the inlet fluid 110.
- the system 3 is arranged to control the flow of argon from the fluid 120 at the outlet of the assembly 1 of at least one distillation column.
- the fluid 120 corresponds to the fluid leaving the second distillation column 7.
- the control of the argon flow results in the modification of the oxygen content of the fluid 120.
- system 3 is in fact designed to reach a target level of oxygen in the fluid 120 by modifying the flow of argon in the fluid 120.
- controlling the flow of argon is the lever used, by means of system 3, to improve the purity of the argon at the outlet of the assembly 1 of at least one distillation column.
- the system 3 comprises a sensor 9, a regulator 11, a controller 13 and a valve 15.
- the sensor 9 is arranged to measure the level of oxygen in the fluid 120 leaving the assembly 1 of at least one distillation column.
- the PV value of the oxygen level of the fluid 120 is measured in real time.
- the sensor 9 is positioned at the outlet of the second distillation column 7. More precisely, it is therefore understood that the sensor 9 is positioned at the top of the second distillation column 7, namely the part of the second distillation column 7 from which the fluid 120 is extracted.
- FIG. 3 illustrates an example of variations in the level of oxygen measured PV by the sensor 9 at the outlet of the assembly 1 of at least one distillation column.
- the sensor 9 is further arranged to transmit the value PV (t) of oxygen content measured to the regulator 11 at the instant t.
- the sensor 9 is also designed to transmit the measured oxygen level value PV (t) to the controller 13.
- the sensor 9 comprises a memory 17 and a processor 19.
- the memory 17 is configured to store instructions, the implementation of which by the processor 19 results in the operation of the sensor 9.
- the memory 17 is further arranged to store data relating to variations in the level of oxygen in the fluid 120 measured at the outlet of the assembly 1 of at least one distillation column.
- the regulator 11 is arranged to receive the PV value of the oxygen content measured by the sensor 9.
- the regulator 11 receives the PV value of the oxygen content in real time.
- the regulator 11 also receives as an input a target value SP of oxygen content.
- This target oxygen level SP is a predetermined value corresponding to the desired oxygen level for the fluid 120 leaving the assembly 1.
- This target value SP can also be described as a setpoint.
- the level of target oxygen is less than or equal to 2 ppm.
- the level of target oxygen is between 0.9 ppm and 2 ppm.
- the target oxygen level is equal to 0.9 ppm.
- the regulator 11 is further arranged to determine a variation A re of argon flow required as a function of the difference between the level of dioxygen PV measured by the sensor 11 and the rate of target oxygen SP.
- the output of regulator 11 is therefore a flow corresponding to a required variation in the flow of argon.
- the regulator 11 is further arranged to transmit the variation A re gui of argon flow required to the controller 13.
- PID Proportional-Integral-Derivative
- the variation A re gui of argon flow required is of the following form, after application of the Laplace transform: It is also known that the determination of the output of a PID regulator may include other operations in addition to the determination of the proportional, integral and derived responses.
- the regulator 11 is configured so that the values of the parameters G p and Gi respectively relating to the proportional and integral contributions of the regulator 11 are multiplied by two when the level of dioxygen PV measured by the sensor 9 is higher than the rate of target oxygen MS.
- G p + and Gi + in the case where the level of dioxygen PV measured is greater than the rate of target oxygen SP
- G p and Gi- in the case where the level of dioxygen PV measured is lower than the target dioxygen level SP
- the regulator 11 is a PI ("Proportional-Integral") regulator.
- the regulator 11 is arranged to determine a proportional response and an integral response to the difference e between the measured oxygen level PV and the target oxygen level SP.
- the regulator 1 1 is a PID regulator whose derived response is zero.
- the regulator 11 comprises a memory 25 and a processor 27.
- the memory 25 is arranged to store instructions, the implementation of which by the processor 27 results in the operation of the regulator 11.
- the controller 13 is arranged to receive the variation A regui of required argon flow determined by the regulator 11. Furthermore, as explained above, the controller 13 is also coupled to the sensor 9 so that the controller 13 is further arranged to receive the PV value of the oxygen level of the fluid 120 measured by the sensor 9 at the outlet of the assembly 1 of at least one distillation column. Advantageously, these data are received by the controller 13 in real time. At a given time t, the controller 13 therefore receives the value PV (t) of oxygen content measured by the sensor 9 and the variation A regui (t) of required argon flow rate determined by the regulator 11.
- the controller 13 is further arranged to generate a control signal relating to a target argon flow rate Q argon .
- the controller 13 is further arranged to transmit the control signal to the valve 15.
- the modification of the flow of argon at the outlet of the assembly 1 directly impacts the oxygen content of this fluid 120.
- the flow d the targeted argon Q argon determined by the controller 13 is therefore determined with a view to reaching the target dioxygen level SP at the outlet of the assembly 1.
- the target value SP of dioxygen level is advantageously equal to 0, 9 ppm.
- FIG. 5 illustrates, as a function of the oxygen content of the fluid 120 at the outlet of the assembly 1, the quantity of argon recovered, in fluid 120 therefore, relative to the amount of argon in fluid 110 supplying the last distillation column of assembly 1.
- the last distillation column of assembly 1 corresponds to the second distillation column 7.
- FIG. 5 illustrates the ratio of argon recovered between the fluid 110 at the inlet of the last distillation column of the assembly 1 and the fluid 120 at the outlet of the last distillation column of the assembly 1
- this ratio increases when the oxygen level increases to 0.9 ppm. From 0.9 ppm, this ratio is substantially constant.
- too high a level of oxygen in the fluid leaving the assembly 1 is also not desirable since it must be as pure as possible. Consequently, it is particularly advantageous to have a dioxygen level of between 0.9 ppm and 2 ppm in order to achieve a maximum ratio of recovered argon equal to 77%.
- the level of dioxygen is equal to 0.9 ppm, namely the minimum value of level of oxygen allowing to reach a maximum ratio of recovered argon.
- the targeted argon flow Qargon is determined as a function of the variation A re of required argon flow determined by the regulator 11 and of the variations in the level of dioxygen PV measured by the sensor 9.
- the assembly 1 of at least one distillation column is supplied by the fluid 100 comprising argon.
- the fluid 100 is an air fluid with a variable flow over time.
- the targeted argon flow rate Q argon determined by the controller 13 is also determined as a function of a predictive value Q pre d of the argon flow rate depending on the air flow rate Q air at the inlet of set 1 of at least one distillation column and of a yield p of set 1.
- the predictive value Q pre d of the argon flow is a function more exactly of a delayed air flow Q * a ir relative to the air flow Q air at the inlet of the assembly 1. It is therefore understood here that , in this particular embodiment, the value of air flow used for determining the predictive value Q pre d is, not the actual air flow Q air at the inlet of set 1, but a flow d delayed air Q * air . The use of this quantity makes it possible to take into account the delay inherent in the operation of the assembly 1 in general and of the distillation columns, here the distillation columns 5 and 7, in particular.
- the delayed air flow Q * a ir is illustrated in Figure 2 and will be explained in the following description.
- the controller 13 comprises a memory 25 and a processor 27.
- the memory 25 is arranged to store instructions, the implementation of which by the processor 27 results in the operation of the controller 13.
- the valve 15 is arranged to modify the argon flow rate of the fluid 120 at the outlet of the assembly 1 of at least one distillation column in order to obtain the targeted argon flow rate Q arg on determined by the controller 13.
- the modification of the argon flow rate of the fluid 120 induces a change in the oxygen content of this same fluid 120.
- FIG. 3 illustrates such variations in the level of dioxygen.
- valve 15 includes an actuator and a conduit (not shown in Figure 1) ⁇
- the actuator is arranged to modify the flow rate of the fluid, here the fluid 120 leaving the assembly 1, flowing along the conduit of the valve 15 so as to obtain the desired flow rate.
- the position of the valve actuator is controlled by the control signal sent by the controller 13.
- the position of the actuator is a function of the targeted argon flow .
- the assembly 1 of at least one distillation column is supplied by the fluid 100 comprising argon.
- the fluid 100 is an air fluid.
- the air flow rate of the fluid 100 varies over time.
- a distillation process is carried out in the first distillation column 5 so as to obtain a fluid 110 whose oxygen content is higher than that of the fluid 100.
- the fluid 110 is then injected at the inlet of the second distillation column 7 within which a distillation process is also carried out .
- the fluid 120 at the outlet of the second distillation column 7, therefore of the assembly 1, is the fluid treated by the system 3.
- the sensor 9 measures the value PV (t) of the oxygen content of the fluid 120 at an instant t.
- the level of oxygen in the fluid 120 is advantageously measured in real time.
- the PV value (t) of the oxygen content measured by the sensor 9 is transmitted to the regulator 1 1 and to the controller 13.
- the regulator 11 receives the value PV (t) of the level of oxygen measured by the sensor 9 at time t. Furthermore, the regulator 11 also receives the target value SP of the target oxygen level, namely the level of oxygen satisfying the requirement of argon purity of the fluid 120.
- the regulator 11 determines the difference e between the measured value PV (t) of the oxygen content and the target value SP, also called the setpoint.
- this variation being determined, it too, in real time, it can also be noted A re gui (t) in the following description to designate the value of the variation in argon flow required in response to the measured value PV (t) of the oxygen content at time t.
- the regulator 11 is a PID regulator.
- the variation A re gui (t) of argon flow required includes a proportional response, an integral response and a derivative response to the difference e between the value PV (t) of measured oxygen content and the SP value of target oxygen level.
- the regulator 11 is a PI regulator and the derived response is therefore zero.
- the delayed air flow Q * air is determined as a function of the air flow Q air .
- the air flow Q air of the air fluid 100 at the inlet of the assembly 1 of at least one distillation column varies as a function of time. These variations in the air flow Q air have an impact on the argon flow of the fluid 120 at the outlet of the assembly 1 and therefore on the oxygen level of the fluid 120.
- the distillation process or processes successively implemented have a certain delay inherent in the assembly 1. For example, a an increase in the air flow at the inlet of 100 m 3 / h will not be passed on at the outlet of assembly 1 until after approximately 40 minutes. It is therefore advantageous to use a value of delayed air flow rate Q * air (t) rather than the value of the actual air flow rate Q air (t) for the calculations detailed in the rest of the process.
- the delayed flow Q * air is defined as follows according to the actual air flow Q air :
- Q air (t) is the air flow at the inlet of all of at least one distillation column at time t
- R is a positive predetermined threshold
- the delayed air flow Q * air is distinct from the real air flow Q air when the real air flow Q air increases with a high slope, ie ie a slope greater than or equal to a predetermined value, namely here ⁇ / g.
- a high slope is detected, the value of the delayed air flow Q air (t) is kept constant for a predetermined period of time, here denoted l.
- FIG. 2 illustrates the variations in the air flow rate Q air at the inlet of the assembly 1 of at least one distillation column.
- d 1 min
- This portion of the curve of the actual air flow Q air is identified by the ends A and B. Since the slope is steep, the delayed flow Q * air is distinct from the real air flow Q air . More precisely, the delayed air flow Q * air is delayed by 40 minutes, period during which the value of the delayed air flow Q * air is kept constant, whatever the variations of the real air flow Q air on this time interval.
- the measurement indicates that the increase in flow over 1 minute is greater than the predetermined threshold R.
- step S3 the value of delayed air flow rate Q * air (t) is determined at time t.
- This value is for example determined by the controller 13 which therefore receives, in this embodiment, the measurement of the air flow Q air at the inlet of the assembly 1 of at least one distillation column.
- the value of the delayed air Q * air (t) is directly transmitted to the controller 13.
- the controller 13 determines the predictive value Q pred (t) of the argon flow as a function of the air flow Q air at the inlet of the assembly 1 of at least one distillation column and d 'a return on the set 1.
- the predictive value Q pred (t) is more precisely determined as a function, not of the air flow Q air entering the assembly 1, but of the delayed air flow Q * a ir and of the efficiency of the assembly 1.
- the predictive value Q pred (t) of the argon flow rate is determined by the controller 13 as follows:
- Qpred (t) is the predictive value of the argon flow at a given time t
- A is the proportion of argon in the air flow entering the assembly of at least one distillation column
- the proportion of argon a in the air flow at the inlet of the assembly of at least one distillation column is approximately 0.93%.
- the predetermined function is determined by a learning algorithm on the basis of a set of data relating to a plurality of distillation processes implemented according to different values of quantity of energy requested.
- the predetermined function is determined by carrying out several distillation processes by varying, from one process to another, the quantity of energy required. We then obtain a set of energy-efficiency quantity points.
- a learning algorithm such as an extrapolation of these different points makes it possible to determine the function F.
- the predetermined function is polynomial.
- a predetermined function is a polynomial function of degree less than or equal to 2.
- the predictive value Q pr ed (t) of argon flow at an instant t is weighted by a corrective factor K relating to disturbances of the set 1 of at least one column of distillation.
- the corrective factor K is determined as a function of the difference between the dioxygen level measured PV (t) by the sensor 9 and the target dioxygen level SP.
- the corrective factor K is defined as follows:
- K K 2 if T 2 ⁇ PV (t) - SP ⁇ Ti
- Ki, K 2 and K 3 are possible predetermined values of the corrective factor, and Ti and T 2 are predetermined thresholds.
- FIG. 3 illustrates an example of variations in the level of dioxygen PV measured by the sensor 9 at the outlet of the assembly 1.
- predetermined conditions have been defined:
- the value of the corrective factor K is Ki when the PV value (t) of the argon flow measured by the sensor 9 is greater than or equal to 0.95 ppm.
- the value of the corrective factor K is K 2 .
- the value of the corrective factor K is K 3 when the PV value (t) of the argon flow measured by the sensor 9 is less than or equal to 0.85 ppm.
- an anticipation parameter P relating to the variations in the level of dioxygen PV measured by the sensor 9 is determined, for example by the controller 13.
- the anticipation parameter P takes discrete values in a set of predetermined values.
- the system 3 uses a regulator 11 which is typically a PID regulator. The use of such a regulator induces a variation in the argon flow rate of the fluid 120, namely the variation A re gui discussed so far.
- the evolution over time of the level of oxygen in the fluid 120 at the outlet of the assembly 1 has a profile similar to that of the curve illustrated in FIG. 3. Typically, four points of inflection are observed, denoted respectively by W , X, Y and Z in Figure 3.
- point W marks the beginning of a strong increase in the level of oxygen
- point X marks the end of this strong increase and the beginning of a phase during which the level of oxygen is substantially constant.
- Point Y marks the start of a sharp decrease in the level of oxygen
- point Z marks the end of this sharp decrease and the start of a phase during which the level of dioxygen is again substantially constant.
- the anticipation parameter P relating to the variations in the rate of dioxygen PV measured by the sensor 9 is based on the fact that these variations, largely due to the operating mode of the regulator 11, have a profile known in advance and which can therefore be anticipated. Furthermore, the PID regulator is very often not suitable for regulating non-linear variations, which is the case here, as illustrated in FIG. 3, with the variations in the level of dioxygen at the outlet of the assembly 1. This non linearity is mainly due to the fact that the measured oxygen level corresponds to the level of oxygen in the fluid 120 extracted from the upper part of the distillation column, here the second distillation column 7.
- the anticipation parameter P aims to compensate for the relative inability of the regulator 11 to regulate in the case of non-linearity.
- the anticipation parameter P is defined to take discrete values from a set of predetermined values as a function of the current position on the curve of the measured dioxygen PV level.
- the anticipation parameter P relating to variations in the level of oxygen is defined as follows: or :
- P (t) is the value of the anticipation parameter relating to variations in the level of oxygen measured by the sensor at time t
- PV (t) is the value of the oxygen level measured by the sensor at time t
- the set of predetermined values therefore comprises a first predetermined value Pi, a second predetermined value P 2 and a third predetermined value P 3 .
- the anticipation parameter P takes the value Pi on the portion of the curve before point W, between point X and point Y, and after point Z.
- the anticipation parameter P takes the value P 2 on the portion of curve between point W and point X.
- the anticipation parameter P takes the value P 3 on the portion of curve between point Y and point Z.
- this anticipation parameter may be of a different nature depending on the embodiments and therefore be used differently from one embodiment to another in the determination, by the controller 13, of the argon flow rate Q argon targeted. .
- the anticipation parameter P relating to the variations in the level of PV oxygen measured by the sensor 9 is a corrective flow.
- the discrete values by the anticipation parameter P are the following:
- the anticipation parameter P relative to the variations in the level of dioxygen PV measured by the sensor 9 is a weighting coefficient of the predictive value Q pre d of the argon flow.
- the controller 13 determines the argon flow rate Q argon targeted. It will also be understood from the above that the targeted argon flow rate Q argon is advantageously determined in real time since it depends on the variation A re of required argon flow rate determined by the regulator and variations in the rate of PV oxygen measured by sensor 9 in real time.
- the anticipation parameter P relating to the variations in the level of dioxygen PV measured by the sensor 9 is, according to one embodiment, a corrective flow.
- the target argon flow Q argon is then determined as follows:
- a regui is a variation of argon flow required
- the flow of argon Q argon is determined as follows:
- the anticipation parameter P relating to the variations in the level of dioxygen PV measured by the sensor 9 is a weighting coefficient of the predictive value Q pre d of the argon flow.
- the target argon flow Q argon is then determined as follows: Qargon Qpred XP + D regul
- a regui is a variation of argon flow required
- the controller 13 then generates a control signal at the target argon flow rate Q determined argon . This control signal is sent to the valve 15 of the system 3.
- the valve 15 receives the control signal sent by the controller 13.
- This control signal is characteristic of the targeted argon flow Qargon.
- the position of the actuator of the valve 15 is modified so that the flow rate of the fluid 120, flowing in the conduit of the valve 15, reaches the target flow rate of argon Q argon .
- the modification using the valve 15 controlled by the controller 13, makes it possible to directly impact the oxygen level of the fluid 120 in order to reach the target oxygen level SP.
- the level of target oxygen is typically less than 2 ppm, preferably equal to 0.9 ppm.
- the use of the oxygen level value measured at the outlet of the assembly of at least one distillation column makes it possible to have more relevant data for determining the argon flow rate making it possible to reach the target oxygen level.
- the anticipation parameter makes it possible to anticipate the variations in the oxygen level induced by the use of a regulator, and more specifically a PID regulator, and therefore achieve the target oxygen level more quickly and more reliably.
- This anticipation parameter therefore makes it possible to compensate for the bias introduced by the use of a regulator.
- the level of oxygen used here is non-linear since it is measured on the outlet fluid, therefore the fluid from the upper part of a distillation column.
- a regulator, and more particularly a PID regulator is not suitable for managing this non-linearity, hence the use of the anticipation parameter in addition to the regulator, this anticipation parameter being adapted to the non-linearity the oxygen content of the fluid leaving the assembly of at least one distillation column.
- column 5 is a double air separation column comprising a medium pressure column thermally coupled to a low pressure column, the low pressure column being supplied by a fluid enriched in nitrogen and a fluid enriched in oxygen originating of the medium pressure column.
- the flow 110 is a flow enriched in argon coming from the low pressure column which is sent to the argon column 7.
- the fluid 120 rich in argon is produced by the argon column 7.
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Mechanical Engineering (AREA)
- Thermal Sciences (AREA)
- General Engineering & Computer Science (AREA)
- Oxygen, Ozone, And Oxides In General (AREA)
- Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)
- Separation By Low-Temperature Treatments (AREA)
Abstract
Description
Claims
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR1855605A FR3082923B1 (fr) | 2018-06-22 | 2018-06-22 | Systeme de controle d'un debit d'argon en sortie d'une colonne de distillation |
| PCT/FR2019/051169 WO2019243681A1 (fr) | 2018-06-22 | 2019-05-22 | Système de contrôle d'un débit d'argon en sortie d'une colonne de distillation |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| EP3811012A1 true EP3811012A1 (fr) | 2021-04-28 |
Family
ID=63209573
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP19740621.8A Withdrawn EP3811012A1 (fr) | 2018-06-22 | 2019-05-22 | Système de contrôle d'un débit d'argon en sortie d'une colonne de distillation |
Country Status (6)
| Country | Link |
|---|---|
| US (1) | US11946693B2 (fr) |
| EP (1) | EP3811012A1 (fr) |
| CN (1) | CN112424550B (fr) |
| FR (1) | FR3082923B1 (fr) |
| SG (1) | SG11202012920UA (fr) |
| WO (1) | WO2019243681A1 (fr) |
Family Cites Families (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA2142318A1 (fr) * | 1994-02-24 | 1995-08-25 | Horst Corduan | Methode et appareil pour la recuperation d'argon pur |
| US5522224A (en) * | 1994-08-15 | 1996-06-04 | Praxair Technology, Inc. | Model predictive control method for an air-separation system |
| JP3451453B2 (ja) * | 1994-11-25 | 2003-09-29 | 日本酸素株式会社 | 空気液化分離装置及びその制御方法 |
| EP0962638B1 (fr) * | 1998-06-05 | 2006-01-11 | Toyota Jidosha Kabushiki Kaisha | Moteur à combustion interne |
| JP4279540B2 (ja) * | 2002-11-13 | 2009-06-17 | 大陽日酸株式会社 | 空気分離装置の制御方法 |
| US7204101B2 (en) * | 2003-10-06 | 2007-04-17 | Air Liquide Large Industries U.S. Lp | Methods and systems for optimizing argon recovery in an air separation unit |
| JP2009257195A (ja) * | 2008-04-16 | 2009-11-05 | Toyota Motor Corp | 車両の制御装置 |
| CN101634837A (zh) * | 2009-08-17 | 2010-01-27 | 浙江大学 | 空分装置制氩系统氮塞的防控方法 |
| US8795409B2 (en) * | 2011-08-25 | 2014-08-05 | Praxair Technology, Inc. | Air separation plant control |
| US10018413B2 (en) * | 2015-07-31 | 2018-07-10 | Praxair Technology, Inc. | Method and apparatus for increasing argon recovery in a cryogenic air separation unit integrated with a pressure swing adsorption system |
| CN106642992A (zh) * | 2016-07-27 | 2017-05-10 | 杭州杭氧股份有限公司 | 一种空分装置制氩系统的氮塞防控方法 |
-
2018
- 2018-06-22 FR FR1855605A patent/FR3082923B1/fr active Active
-
2019
- 2019-05-22 EP EP19740621.8A patent/EP3811012A1/fr not_active Withdrawn
- 2019-05-22 US US17/253,583 patent/US11946693B2/en active Active
- 2019-05-22 WO PCT/FR2019/051169 patent/WO2019243681A1/fr not_active Ceased
- 2019-05-22 SG SG11202012920UA patent/SG11202012920UA/en unknown
- 2019-05-22 CN CN201980047109.1A patent/CN112424550B/zh active Active
Also Published As
| Publication number | Publication date |
|---|---|
| CN112424550B (zh) | 2022-11-11 |
| FR3082923B1 (fr) | 2020-10-16 |
| US20210222949A1 (en) | 2021-07-22 |
| FR3082923A1 (fr) | 2019-12-27 |
| CN112424550A (zh) | 2021-02-26 |
| US11946693B2 (en) | 2024-04-02 |
| SG11202012920UA (en) | 2021-01-28 |
| WO2019243681A1 (fr) | 2019-12-26 |
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