RU2299090C2 - Method of the automatic control over hydrodynamics of the column of the target component production - Google Patents

Abstract

FIELD: chemical industry; petrochemical industry; methods of the automatic control over the hydrodynamics of the target component production column.

SUBSTANCE: the invention is pertaining to the field of chemical industry and petrochemical industry and may be used at production of the stable isotopes, for example, O¹⁸, by the method of the low-temperature distillation. The method provides for feeding of the columns with the separable mixture, the depleted mixture piling withdrawal of the enriched product, heating of the separable mixture up to the temperature of its liquid phase vaporization by means of the heater-evaporator of the lower section and condensation of the produced vapors of the separable mixture by the cooler located above the upper section. The supervision and the automatic control over the circulatory streams are exercised with the help of the powers scattered by the heaters-evaporators in the lower section, the upper section and the intermediate section of the column due to additional variation of the power of the appropriate heaters-evaporators. The power of the heating in the lower section is determined from the conditions of the automatic stabilization of the liquid phase level in the heater-evaporator of the lower section, measure the power really consumed by it and compare it in the power automatic control device of the intermediate section with the preset value of the power scattered by the heater-evaporator of the lower section. Then measure the really consumed power of the heater-evaporator of the intermediate section, compare it in the power automatic control device of the upper section with the preset value of the power scattered by the heater-evaporator of the intermediate section. Measure the really consumed power of the heater-evaporator of the upper section, compare it in the power automatic control device of the piling flow with the preset power scattered by the heater-evaporator of the upper section. The received signal is fed to one of the inputs of the regulator of the automatic stabilization system of the piling flow as the set value and to the other input of the indicated regulator they feed the signal proportional to the running piling flow. The preset power on the heater-evaporator of the intermediate section chose preferentially of the greater value, than the value of the preset power on the heater-evaporator of the lower section, and of the smaller value, than the value of the preset power on the heater-evaporator of the upper section. The invention ensures production of the target component of the high concentration, stabilization of the hydrodynamic processes in the column, preventing of flooding or exhaustion of the column.

EFFECT: the invention ensures production of the target component of the high concentration, stabilization of the hydrodynamic processes in the column, prevention of flooding or exhaustion of the column.

3 cl, 1 dwg

Description

The invention relates to a technology for obtaining the target product, such as a stable isotope O ¹⁸ , by the method of low-temperature distillation of nitric oxide NO in a 3-section column.

A known method of automatically controlling the hydrodynamics of a single-section column for obtaining the target component, including feeding the column with a separated mixture, a lean mixture dump, selecting the enriched product, heating the liquid phase to the vaporization temperature by the lower section heater-evaporator, and condensing the vapors obtained by the condenser-cooler located above the upper section, control and maintaining the technological parameters of the power flows, selection and dump at a given level depending on the level of the liquid phase in the lower sections using an electronic control logic controlling the dump flow regulator (see G.N. Muskhelishvili. Elements, devices and systems for automatic control of stable isotope concentration processes in packed columns, Tbilisi University Press, Tbilisi, 1978, p. 18 -21, p. 147-151).

The disadvantage of this method of automatic control of the hydrodynamics of the column is that

- the flow balance is proposed to be implemented by controlling the supply flows, selection and dump using an electronic logic circuit depending on the change in the level of the liquid phase, the relationship of which with the value of the dump flow is unknown;

- the thermal power of the heater-evaporator, which determines the magnitude of the circulation flow, is fixed, as a result of which the disturbing effect on the change in the thermal power of the heater-evaporator inevitably changes the value of the steady-state circulation flow in the column;

- control of the balance of flows is carried out by the relay law of control of the dump stream, which creates an oscillatory regime of changes in the circulation flow in the column, which is unacceptable, for example, for the process of producing the O ¹⁸ isotope (together with O ¹⁷ and N ¹⁵ ) by the method of low-temperature distillation of nitric oxide NO;

- the known method for automatic control of the column hydrodynamics is not applicable, for example, for a 3-section column designed to produce a highly enriched oxygen isotope O ¹⁸ by low-temperature distillation of nitric oxide NO, in which the joints between intermediate and adjacent (upper and lower) sections are equipped with phase reversal devices located in the lower parts of the sections - heaters-evaporate the elements ("dividers of the circulation flow"), designed to return to the corresponding section of the part of the stream that does not come in the form of power to the next section, and the thermal capacities of the heaters-evaporators in the sections differ by more than 30 times and each of the heaters is a source of disturbing effects conditions when to provide high concentrations of the isotopes ¹⁸ O (O together with n ¹⁷ and ¹⁵⁾ in the 3-cell column subject to special high requirements for precision stabilization profiled circulation n current in the absence of vibrational processes in the column.

In addition, with any, but always with finite accuracy, instruments for stabilizing the power flows, dump, selection, setting the heat output of heaters-evaporators, in the hydrodynamic processes of the column there is inevitably a tendency either to exhaust the content or to choke the column due to that when the balance of readings of stabilizing instrument flows imperfect in metrology is lacking, there is no real material balance of the incoming / outgoing flows in the column. This trend should be continuously analyzed by technologists during the normal operation of the column and promptly eliminated by coordinating the ratio of supply flows, dump and selection. These actions require highly qualified staff and due to the significant inertia of the processes and time delays of reactions, changes in external flows to the process of accumulation or depletion of the substance in the column in the manual control mode are inaccurate, with deterioration of technological and economic indicators of isotope separation processes and obtaining the target component, for example stable isotope O ¹⁸ , up to the loss of the concentration function of the target component.

The objective of the patented invention is to ensure the stability of hydrodynamic processes in the column necessary to create an effective and stable isotope exchange process in order to obtain the target component - nitrogen and oxygen isotopes of high concentration, eliminating flooding or exhaustion of the column.

The technical result of the invention is the quantitative measurement and automatic stabilization of the circulation flows in the column specified through the power of the heater-evaporators in the sections of the column.

The specified task and technical result is achieved by a method of automatically controlling the circulation flows in a 3-section column to obtain the target component, including feeding the column with the initial mixture, dumping the depleted mixture, selecting the enriched product, heating the separated mixture to the evaporation temperature of the liquid phase of the separated mixture by the heater-evaporator of the lower section and condensation of the vapors of the mixture to be separated by a cooler located above the upper section, the reduction of the circulation flow with by the power of the heater-evaporator (circulating flow divider) in the lower part of the intermediate section, monitoring and maintaining the technological parameters of the power flows, selection and dump at a given level.

In the specified method, the control and automatic maintenance of the specified values of the circulation flows in the sections of the column, determined by the power dissipated by the heater-evaporators in these sections of the column, is carried out by additional changes in the power of the heater-evaporators in the upper and intermediate sections, and the heating power in the lower section is determined from the conditions of automatic stabilization of a given level of the liquid phase in the heater-evaporator of the lower section,

and the predetermined power dissipated by the heater-evaporator of the intermediate section is changed using an automatic power regulator of the heater-evaporator of the intermediate section according to the results of comparing the real and specified power consumption by the heater-evaporator of the lower section,

and the predetermined power dissipated by the heater by the evaporator of the upper section is changed using an automatic power controller of the heater-evaporator of the upper section according to the results of comparing the real and given power consumption by the heater-evaporator of the intermediate section,

and the blade flow rate is changed using the blade flow controller according to the results of comparing the real and predetermined power consumption by the heater-evaporator of the upper section.

The specified task and the technical result are also achieved by the fact that the set power on the heater-evaporator of the intermediate section is set larger than the set power on the heater of the lower section and smaller than the set power on the heater-evaporator of the upper section.

And also by the fact that the target product is the O ¹⁸ isotope.

An example of setting a profiled circulation mode of a 3-section column

In the lower section, the circulating flow of liquid NO G3 = 15 g / ml

In the intermediate section, the circulating flow of liquid NO G2 = 61 g / ml.

In the upper section, the circulating flow of liquid NO G1 = 581 ml _w / min.

To evaporate the flow of liquid NO 1 g / ml / min, a thermal power of 10 W is required.

To provide the intermediate section of the circulation flow zh.ml G2 = 61 / min, it is necessary to vaporize in a heater-evaporator top section 581 ml _w / min - 61 zh.ml / min = 520 zh.ml / min liquid phase NO heater-evaporator top sections with a thermal power of 5200 watts.

In order to provide G3 = 15 g / ml / min in the lower section of the circulation flow, it is necessary to evaporate 61 g / ml / min - 15 g / ml / min = 46 g / ml of the liquid phase NO by the heater-evaporator of the intermediate section with a thermal power of 460 Tue

For complete evaporation in the lower section of the liquid phase stream G3 = 15 g / ml / min, the power of the heater-evaporator of the lower section is 150 W.

The drawing shows a diagram of a 3-section column for obtaining the target product, such as, for example, an oxygen isotope O ¹⁸ , by low-temperature distillation and a structure that implements the patented method for automatically controlling the hydrodynamics of this column.

The column for obtaining the target product, for example, the oxygen isotope O ¹⁸ , consists of a lower section 3, an upper section 1 and an intermediate section 2 located between the lower 3 and upper 1 sections of the column. In the lower parts of each of these sections of the column are heaters-evaporators 4, 5 and 6, for example, of the electric type. A cylindrical vessel 7 is mounted in the heater-evaporator 4 of section 1. In the upper part of the vessel 7 there is a level sensor 8, which is connected to the regulator 9 with an integral component in the regulation law that controls the heat power dissipated by the heater-evaporator 4. The power dissipated by the heater-evaporator 4 is measured by a sensor 10 connected to the output of the regulator 9.

The level sensor 8, the regulator 9 and the heater-evaporator 4 with the vessel 7 form a system for automatically stabilizing the level of a liquid product, for example liquid NO, in the lower section 3.

The automatic power controller 9, consumed by the heater-evaporator 4, operates on the basis of the mismatch (controlled by the mismatch) of the H signals from the level sensor 8 and the given signal of the Hz level.

The power sensor 10 is also connected to a power controller 11 (with an integral component in the law of regulation) dissipated by the heater-evaporator 5.

The power regulator 11, consumed by the heater-evaporator 5, operates on the basis of the mismatch (controlled by the mismatch) of signals N3 from the power sensor 10 and a given power signal N3з. The power sensor 12 measures the power consumed by the heater-evaporator 5.

The power sensor 12 is connected to a power controller 13 (with an integral component in the law of regulation) consumed by the heater-evaporator 6. The controller operates on the basis of the mismatch (controlled by the mismatch) of the N2 signals from the power sensor 12 and a given power signal N2з.

The power sensor 14 measures the power consumed by the heater-evaporator 6.

The power sensor 14 is connected to the blade flow regulator 15, the output of which is connected to the regulator 16 of the automatic stabilization system (specified by the output signal of the regulator 15) of the blade flow 17, which also includes a flow meter 18 and an electrically controlled valve 19 installed in series on the dump pipeline.

The controller 15 operates on the basis of a mismatch of the signals N1 from the power sensor 14 and the specified power signal Nlз and has an output signal that defines the blade stream Wз, which is fed to one of the inputs of the controller 16 of the automatic stabilization system for the blade stream 17, the other input of which receives a signal proportional to the current the dump stream W from the flow meter 18. The output of the controller 16 is connected to the control circuit of the valve 19.

The upper section 1 of the column also contains a system 20 for automatic power stabilization, a system 21 for automatic pressure stabilization near the condensation surface, a system 22 for automatic pressure stabilization in the intermediate heat exchanger of the condenser-cooler 28 located above the upper part of the upper section 1, and the lower section 3 of the column contains a system 23 automatic stabilization of the flow of selection.

The automatic power stabilization system 20 includes a flowmeter 24 and a regulator 25 sequentially installed in the pipeline, made, for example, in the form of an electrically controlled valve controlled by a regulator 26 (with an integral component in the regulation law) according to the error signal F from the flowmeter 24 and a given flow signal Fз .

The system 21 for automatic pressure stabilization P _NO near the condensation surface of the condenser-cooler 28 located above the upper section 1 includes an electrically controlled valve 29 mounted on the pipeline 27 of the condenser-cooler 28, controlled from the regulator 30 (with an integral component in the regulation law) by the signal P _NO from a pressure sensor 31 and a predetermined pressure signal P _NO .

System 22 for automatic stabilization of gas pressure (argon) in the intermediate condenser-heat exchanger 28 includes a pressure sensor 32, a regulator 33, and electrically operated valves 34 and 35, respectively installed on the gas supply and gas discharge pipelines and whose electrical circuits are connected to the regulator 33, which controls valves for the mismatch of the signal PAr from the pressure sensor 32 and a given pressure signal PArz.

Automatic stabilization stream selection system 23 comprises a conduit mounted on selection flowmeter 36 and the regulator 37 in the form of an electrically valve, which are interconnected through flow regulator 38 selection which is controlled by the error signal from the flowmeter Rotb 36 and predetermined stream selection signal Rotb _h.

The method is as follows:

The regulator 9 ensures that the level H of liquid NO in the vessel 7 of liquid nitric oxide (NO) remains constant at a predetermined level of Нз.

For example, with a flow of NO G3 = 15 ml _w / min, a heater-evaporator 4 dissipates 150 watts, sufficient to completely evaporate the incoming liquid NO, i.e. the constancy of the level of NO in the vessel 7 of the lower section 1 at a given power N3z of the heater-evaporator 4, while N = Nz.

When the flow of circulation G ₃ in the lower section 3 changes, for example, an increase, the level of liquid NO in the vessel 7 increases, which, due to the operation of the regulator 9 with the integral component in the regulation law, leads to a smooth increase in the power of N3 on the heater-evaporator 4 until the previous set level Нз of liquid NO in the vessel 7 of the lower section will not be restored. The power supplied to the heater-evaporator 4 will increase, which is indicated by the output signal of the power sensor 10, corresponding, for example, to a power of 160 W.

Due to the fact that the level of liquid NO is measured in the tank 7, which is a vertical vessel with a cross-sectional area A, in which the accumulation of the volume A dH of liquid NO per unit time dt is determined by the material balance of the incoming volume of liquid NO equal to G3 _w (t) dt, and vaporized NO equal to G3 g (t) dt, i.e. (in deviations from the nominal mode):

A dH = G3 _w (t) dt-G3 _w (t) dt

A dH / dt = G3 _g (t) -G3 _g (t), whence

H = [G3 _x (t) -G3 _g (t)] t / A.

Therefore, the level of liquid NO in the vessel 7 is unchanged only in the case of complete complete evaporation of the incoming liquid G3 _g due to the thermal power of the heater-evaporator 4, which is measured by the power sensor 10 (accurate to the additive component of the heat loss on the heater-evaporator 4).

Thus, when a system of automatic stabilization of the Н level of liquid NO is introduced into the lower section 1 in a cylindrical vessel 7 mounted in a heater-evaporator 4, a power signal N3 is dissipated by the heater-evaporator 4, which is proportional to the circulation flow G3 (accurate to the additive component heat loss of the heater) inside the column, removed from the column, and additional measuring tools are not required to determine the magnitude of the circulation flow.

Let us further consider the implementation of the control method in the mode of working out disturbing influences.

In the initial state of the column, a nominal mode takes place. The circulation flows G1, G2 and G3 in the upper, intermediate and lower sections correspond to the set powers N1з, N2з and N3з on heaters 6, 5 and 4, respectively.

The condensation surface of the condenser-cooler 28 is rated and stable.

The level of liquid NO in the vessel 7 of the lower section 3 is unchanged and equal to Нз.

Suppose that the power consumption of F. has increased.

Increasing the supply of F creates an additional stream ΔG of liquid NO. With a constant initial power N1 of the heater-evaporator 6, there occurs a “dip” of the excess, non-evaporated stream ΔG of liquid NO into the intermediate section 2.

When the rated power N2, dissipated by the heater-evaporator 5, the presence of an excess flow of liquid NO causes the “non-evaporated” flow of ΔG liquid NO to “sink” into the lower section 3, where the level of liquid NO in the vessel 7 of the heater-evaporator 4 increases.

The controller 9 of the system for automatic stabilization of the level Нз of liquid NO in the vessel 7 of the lower section 3 of the column increases the power of the heater-evaporator 4 in order to restore the specified level Нз.

In this case, a mismatch N3 ≠ N3z occurs at the input of the regulator 11 of the power N ₂ dissipated by the heater-evaporator 5. The controller 11 increases the power dissipated by the heater-evaporator 5, i.e. increases the amount of evaporated NO, as a result of which the flow G3 of liquid NO partially decreases.

At the same time, a mismatch N2 ≠ N2z occurs at the input of the power regulator 13 dissipated by the heater-evaporator 6, which is a flow divider in the upper section 1.

As a result, the power controller 13 of the heater-evaporator 6 in the upper section 1 of the column increases the power N1 dissipated by the heater-evaporator 6, which increases the amount of NO evaporated, as a result of which the disturbing part ΔG of the flow G2 decreases.

At the same time, a mismatch N1 ≠ N1z occurs at the input of the power regulator 15, the output of which is supplied as a task W from the system 17 for automatic stabilization of the blade flow W, increasing the blade flow rate W.

The increasing blade consumption W decreases the flow G1, as a result of which the part of the flow ΔG "falling through" into the intermediate section 2 of the column is reduced.

There is a gradual, determined by the settings of the regulators with an integral component in the laws of regulation, the process of restoring the circulation flows G1, G2, G3 to values corresponding to the given powers N1з, N2з, N3з.

The perturbation "in nutrition" passes unchanged from the point of supply of power throughout the column to "top to bottom" and causes the restoration of hydrodynamics (values of given circulation flows in sections) from bottom to top.

The heating power N ₃ on the heater-evaporator 4 at a constant level N of liquid NO in the vessel 7 of the lower section 3, provided by the operation of the automatic stabilization system of the N level (regulator 9), is an internal parameter of the column, quantitatively corresponding to the circulation flow in the lower section 3 of the column, at the use of which as regulated, and heaters-evaporators 5, 6, performing the function of controlled separators of the ratio of liquid / gaseous phases, and a controlled stabilizer of the blade stream 17 as means of action on the process, allows for automatic stabilization (automatic control) of the profile of the circulation flows G1, G2, G3 in sections 1, 2, 3 of the column according to the specified values of N1z, N2z, N3z with instability of thermal power dissipated by heaters-evaporators 4, 5, 6 , ambient temperatures, external flows of the column and eliminate the problem of flooding or exhaustion of the contents of the column in long-term operation modes, inevitable with the control method based on stabilization of input / output fetters, really always carried out with finite accuracy.

With automatic control of the column, the well-known technical means of instrumentation and control devices are used as measuring instruments and influencing the process.

General industrial regulators 11, 13, 15 - regulators of free programming of control laws that are able to implement an algorithm for automatic control of objects with significant net lag - "Smith Predator" (see, for example, P. Herriot. Regulation of production processes, M .: Energy, 1967, p. 249-257) or a technological controller of the TCM41 type as part of a multifunctional complex of software and hardware for building distributed control systems of the multifunctional complex "TECHNOKONT", LLC "SP TILLEV", Cheboksary, or the managing com Lex type "Experion PKS", HONEYWELL company (USA).

Pressure sensors - general industrial corrosion-resistant in the environment of an enriched product, for example, type "SAPFI-22MT" (OJSC "MANOMETR", Moscow, Russia), or type "METRAN 100" (Cheboksary PO "PROMPRIBOR", Russia), or ADZ-SML-10 series of the company "NAGANO" / Germany /.

Power meters are separate general industrial meters of electric power of the EP8504, EP8507 series (Russia).

If analog power amplifiers are used to control heaters-evaporators, such as, for example, a proportional thyristor amplifier type U13M manufactured by MZTA (Moscow), a unified control signal at the input of the amplifier U13M proportional to the output power of an amplifier running on active load.

In stabilization systems pos.20, 23, 17 it is also possible to use separately flow sensors from BRONKHORST HI-TEC or MKS - Inc, or Cole-Parmer International 'or EMERSON; or electrically controlled chokes from BRONKHORST HI- TEC "or" MKS Inc ", or" Cole-Parmer International "," EMERSON ", or OJSC" ARMAGUS "(Gus-Khrustalny), proportional electromagnetic chokes A-32 series of the company" Cole-Parmer Int. "(USA ); general industrial regulators 9, 16, 26, 38 - of the MINITERM 400 type, of the PROTAR type of production of the Moscow Thermal Automation Plant (MZTA, Moscow, Russia) or of the UDC6300, UDC2300, UDC1000, "UDC1500" of the company "HONEYWELL", or algor the results of the control of automatic regulators as part of the software for general industrial control complexes (for example, a control complex of the Experion PKS type by HONEYWELL), a technological controller of the TCM41 type as part of a multifunctional complex of software and hardware for building distributed control systems of the multifunctional complex Tekhnokont, Tillev LLC "(Cheboksary, Russia).

Level gauges 8 are general industrial, for example, capacitive type DUE-1 manufactured by JSC Staroruspribor Plant (Russia).

Regulatory bodies 34, 35, 29 - proportional solenoid valves of the A-32 series of Cole-Parmer International firm, or electrically controlled throttles manufactured by ARMAGUS LLC (Gus-Khrustalny city), or electrically controlled valves of KAMMER, SAMSON company (Germany), "REGADA" (Czech Republic).

Claims (3)

1. A method for automatically controlling the hydrodynamic flows of a column to obtain the target component, which includes feeding the column with a shared mixture, a lean mixture dump, selecting an enriched product, heating the shared mixture to the evaporation temperature of its liquid phase using the lower section heater-evaporator, and condensing the vapors of the separated mixture with a cooler, located above the upper section, control and maintenance of technological parameters of power flows, selection and dump at a given level, characterized in that o control and automatic control of the circulation flows using the capacities dissipated by the heaters-evaporators in the sections of the column is carried out by additionally changing the power of the heaters-evaporators in the upper section and the intermediate section located between the lower and upper sections, and the heating power in the lower section is determined from conditions of automatic stabilization of the liquid phase level in the heater-evaporator of the lower section, measure the actual power consumption of the heater-evaporator of the lower section and compare it in the automatic power regulator of the intermediate section with a given power dissipated by the heater-evaporator of the lower section, measure the actual consumed power of the heater-evaporator of the intermediate section, compare it in the automatic power regulator of the upper section with a given power dissipated by the heater-evaporator of the intermediate section, measure the actual power consumption of the heater-evaporator of the upper section, compare it in the automatic regulator of the blade flow with a given the power dissipated by the heater-evaporator of the upper section, the received signal is sent to one of the inputs of the controller of the automatic stabilization of the blade flow as a given one, and a signal proportional to the current blade flow is fed to the other input of the specified regulator. 2. The method according to claim 1, characterized in that the predetermined power on the heater-evaporator of the intermediate section is set larger than the specified power on the heater-evaporator of the lower section and smaller than the specified power on the heater-evaporator of the upper section. 3. The method according to claim 1, characterized in that as the target product receive isotope O ¹⁸ .