JPH078322B2 - Control method for simulated moving bed - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a method for controlling a simulated moving bed for individually separating each component in a liquid to be treated containing two or more components, and more particularly to a liquid supply position. The present invention also relates to a method of controlling the pump for circulation by reproducing the best control state in the previous step when the steps of moving the liquid take-out position are completed.

[Background of the Invention] Conventionally, a simulated moving bed is known as an apparatus for continuously separating each component in a liquid to be treated containing two or more components.

This is an endless series connection of a number of unit-packed beds filled with a solid sorbent material having different sorption capacities for one component and another component in a liquid to be treated containing two or more components. Then, the liquid is circulated in one direction in the endless unit packed bed, and the liquid to be treated containing two or more kinds of components is supplied in accordance with the flow direction of the circulating liquid, to the solid sorbent. The liquid containing a component that is difficult to be sorbed, the supply of an eluent, and the liquid containing a component that is easily sorbed are taken out at intervals in the endlessly connected unit packed beds, and the liquid to be treated and the eluent are treated. Of the liquid containing the component which is difficult to be sorbed and the liquid containing the component which is easily sorbed are intermittently moved along the flow direction of the circulating liquid. . In the following description, moving the supply / removal position to the next position is referred to as a step, and one cycle of the circulation system is referred to as one cycle.

By the way, when one process is completed and the process is switched to the next process, the viscosity and the like of the liquid in the circulation system are changed, so that the flow rate and pressure of the circulation system are instantaneously changed. Control is performed to change the number of discharge pumps or to install a pressure control valve on the discharge side of the circulation pump to adjust the discharge pressure of the circulation pump.

However, in such a control method, since the control of each circulation pump is performed for each process each time, it takes time for the flow rate and pressure in the circulation system to stabilize, and the liquid collection efficiency is low. There was a problem.

[Object of the Invention]

The present invention has been made in order to solve such a conventional problem, and from the moment when the process is switched by reflecting the best control state in each process in the previous cycle to each identical process in the subsequent cycle. It is an object of the present invention to provide a control method for a simulated moving bed, which controls a circulation pump so that the flow rate and pressure of the circulation system are optimized in a short time.

[Outline of Invention]

A method for controlling a simulated moving bed according to the present invention is a unitized bed which is formed by connecting a plurality of unit-packed beds filled with a solid sorbent material in an endless series to form a circulation channel, and the unitized bed in the circulation channel. A plurality of one circulation pumps are arranged for each one or a plurality of them to circulate the liquid in the circulation flow path in one direction, and the circulation flow path further contains two or more components. An inlet and an outlet for introducing a treatment liquid and an eluent, and at the same time taking out a liquid rich in sorbate and a liquid rich in non-sorbate from the circulation flow path to the solid sorbent In a simulated moving bed which is sequentially arranged along the flow direction and whose position is intermittently moved according to a preset process, the flow rate of each circulation pump is controlled so that the flow rate from each circulation pump becomes a target flow rate value. Flow control signal for controlling and the inlet pressure of each circulation pump While controlling the rotation speed of each circulation pump or the discharge side pressure of each circulation pump by a control signal including a pressure control signal for controlling the inlet pressure of each circulation pump so as to be an average value of all inlet pressures. The flow rate control signal includes a flow rate coefficient for each process corresponding to each circulation pump, and a corrected flow rate coefficient is obtained from the ratio of the average value of each control signal and each control signal in a stable flow rate state, It is characterized in that each of the corrected flow rate coefficients is used as a flow rate coefficient in the same process in the next cycle.

Example of Invention

Hereinafter, the present invention will be described in detail based on the embodiments shown in the drawings.

FIG. 1 shows a schematic diagram of a simulated moving bed in which the method according to the invention can be effectively implemented.

In the figure, LC1 to LC12 are unit packed beds filled with a solid sorbent material, which are connected endlessly in series as shown. PR1, PR3,
PR5, PR7, PR9, and PR11 are circulation pumps, which are arranged for every two continuous unit packed beds, and circulate the liquid supplied in the unit packed beds in the arrow direction. RC1, RC3, RC5, RC7, RC9, RC11
Is a rotation control device for controlling the number of revolutions of the circulation pump, and is provided for each circulation pump.

PD is a supply pump that supplies the liquid to be treated D to the circulation system, and PF is a supply pump that supplies the liquid to be eluted F to the circulation system, so that the liquid to be treated D and the eluent F are supplied to the circulation system at constant flow rates. The feed position shown in the figure is the first step, and the liquid (hereinafter referred to as non-sorbate liquid) E containing components that are difficult to sorb taken out from the circulation system is the unit packed beds LC3 and LC4.
The liquid (hereinafter referred to as sorbate liquid) R, which is taken out from between and is easily sorbed, is a unit packed bed LC9 and LC10.
It is taken out from between. FIC indicates a flow rate detector that detects the flow rate of the circulation system.

1 is a control device composed of, for example, a microcomputer,
Pressure detectors PG1, PG3, which detect the inlet pressure of each circulation pump
The pressure signals P1, P3, P5, P7, P9, P11 from PG5, PG7, PG9, PG11 are input, the flow rate signal F1 is input from the flow rate detector FIC, and the rotation speed control device RC1, RC3, RC5,
Control signals X1, X3, X5, X7, X9, and X11 are output to RC7, RC9, and RC11, respectively.

Next, the operation of the control device 1 will be described based on the block diagram shown in FIG. Reference numeral 10 is a flow controller, which compares a preset target flow rate value with the flow rate value detected by the flow rate detector FIC, and calculates the difference proportionally and integralally to calculate a coefficient multiplier 20, 21, 22, 23. Enter in 24, 25. Reference numeral 11 denotes a first pressure controller, which compares the pressure average value of the inlet pressures of all the circulation pumps with the input pressure value of the circulation pump PR1, and calculates the difference between them by proportional calculation and integral calculation and outputs them to the adder 30. 12 is a second pressure controller, 13 is a third pressure controller, 14 is a fourth pressure controller, 15 is a fifth pressure controller, and 16 is a sixth pressure controller.
The 6th pressure controller is the same as the 1st pressure controller 11, and the pressure average value of the inlet pressure of all circulation pumps and the circulation pumps PR3, PR5, PR.
7, PR9, PR11 inlet pressure value is compared, and the difference is added by adder 3
Output to 1,32,33,34,35.

That is, a control signal obtained by adding the flow rate control signal and the pressure control signal for controlling the circulation pump PR1 from the adder 30.
X1 is output to the rotation speed control device RC1 via the polarity reversing device 40, and the control for controlling the other circulation pumps PR3, PR5, PR7, PR9, PR11 in the same manner from the other adders 31 to 35. Signal X
3, X5, X7, X9, and X11 are output to the rotation speed control devices RC3, RC5, RC7, RC9, and RC11 via the polarity reversing devices 41 to 45, respectively, to constantly control the inlet pressure of each circulation pump and circulate. The flow rate of the system is controlled to reach the flow rate target value.

By the way, when the process is switched as described above, the state of the circulation system changes, so that each coefficient multiplier 20, 21, 22, 23, 24, 25
The coefficient value in 1 can be changed for each step as shown in the table below.

a, b, c, d are coefficients.

This coefficient value is used in the first cycle when the simulated moving bed is started. The coefficient values in each step after the second cycle are related to the stable flow rate in the same step in the previous cycle. Replaced with a number.

The replacement of the coefficient value is such that the control signals X1, X3, X5, X7, X9, when the flow rate in the circulation system reaches the predetermined flow rate target value after a certain time has passed after switching to each process. Obtain the average value of X11, calculate the ratio of the average value and the control signal respectively, and store this, and store the coefficients corresponding to the same step in the previous cycle after the time when the step next progressed. Replace with the coefficient that was used.

When each process is switched to the next process, the integral value in the control calculation used to compensate the pressure loss of each circulation pump is reset to zero.

That is, the flow rate of the circulation system of each process at the time of starting the simulated moving bed becomes stable after a considerable time has elapsed from the time of switching the process, as shown in FIG. By calculating the ratio of the average value of each control signal to each control signal and setting this as the coefficient value in the same step of the next cycle, as shown in FIG. The liquid can be circulated stably at a value.

Further, since the control signal includes the pressure control signal, the newly replaced coefficient value becomes a compensation coefficient that allows for an increase in pressure loss, and the increase in pressure loss is automatically suppressed.

In the above embodiment, the control of the flow rate in the circulation system and the control of the inlet pressure of each circulation pump are performed by controlling the rotation speed of each circulation pump, but a pressure control valve is provided on the discharge side of each circulation pump. Alternatively, it may be arranged and the valve opening of this pressure control valve may be adjusted.

In addition, the circulation pump is 1 for every 2 consecutive packed beds.
Although they are arranged on a table, they may be arranged for each unit packed bed.

〔The invention's effect〕

As described above, according to the present invention, the best control state in each process can be reflected in each identical process in the next cycle, so that the circulation flow path can be changed in a short time from the moment the process is switched. The flow rate can be stabilized, the increase in pressure loss is automatically compensated, and various components can be efficiently separated from the liquid to be treated, and the practical benefit thereof is great.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a simulated moving bed in which the present invention can be effectively implemented, FIG. 2 is a block diagram, and FIGS. 3 and 4 are diagrams showing flow rates in respective steps. LC1 to LC12: Unit packed bed PR1, PR3, PR5, PR7, PR9, PR11: Circulation pump RC1, RC3, RC5, RC7, RC9, RC11: Rotation speed controller PG1, PG3, PG5, PG7, PG9, PG11: Pressure Detector PD, PF: Supply pump, F1C: Flow rate detector 1: Control device, 10: Flow controller 11 to 16: Pressure controller 20 to 25: Coefficient multiplier 30 to 35: Adder 40 to 45: Polarity inversion vessel

Claims (1)

[Claims] 1. A unitized bed filled with a solid sorbent is used in an endless series to form a circulation flow path, and one or a plurality of the unitized beds are provided in the circulation flow path. 1 for each
A plurality of pedestal circulation pumps are arranged to circulate the liquid in the circulation flow path in one direction, and a liquid to be treated and an eluent containing two or more components are introduced into the circulation flow path, and the circulation is performed at the same time. An inlet and an outlet for taking out a liquid rich in sorbate and a liquid rich in non-sorbate from the flow path to the solid sorbent are sequentially arranged along the flow direction of the circulating liquid, and their positions are set. In a simulated moving bed that is intermittently moved according to a preset process, a flow rate control signal for controlling the flow rate of each circulation pump so that the flow rate from each circulation pump becomes a target flow rate value, and each circulation pump. And a discharge side pressure of each circulation pump by a control signal including a pressure control signal for controlling the inlet pressure of each circulation pump so that the inlet pressure of each circulation pump becomes an average value of all inlet pressures. And control The flow rate control signal includes a flow rate coefficient for each process corresponding to each circulation pump, and a corrected flow rate coefficient is obtained by the ratio between the average value of each control signal and each control signal in a stable flow rate state, A control method characterized in that each of the corrected flow rate coefficients is used as a flow rate coefficient in the same process in the next cycle.