JPS59169506A - Rotary disk extracting tower - Google Patents

Abstract

PURPOSE:To perform efficient and stable operation of an extracting tower, in a rotary disk type extracting tower with a stirrer, by measuring the differential pressure of the pressure at a tower bottom part and reference head pressure while performing the adjustment of the rotation number of a rotary disk corresponding to the variation of the differential pressure. CONSTITUTION:A light liquid and a heavy liquid are respectively introduced into a rotary disk type extracting tower 21 with a stirrer from pipes 22, 23 and liquid column corresponding to a total liquid height 27 is formed in a reference head pressure arranged pipe 30 by opening a valve 35 to set reference head pressure while the upper end of said pipe 30 is connected to the gas phase part of the tower 21 and the pressure thereof is made equal to that of the gas phase part to open said upper end to the atmosphere. In the next step, the valve 35 is closed to perform the operation of the extracting tower 21 and the differential pressure of the liquid side pressure of the tower 21 and the reference head pressure of the pipe 30 generated in a pneumatic differential pressure transmitter 31 is read while the change with the elapse of time of a hold-up ratio is determined by the above mentioned differential pressure corresponding to the change of the specific gravity of the heavy liquid in the tower to control the rotation number of the rotary shaft of the tower 21. By this method, the efficient and stable operation of the extracting tower 21 is enabled.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rotating disk extraction column, and in the rotating disk extraction column, under conditions for efficient extraction,
Another object of the present invention is to provide a rotating disk extraction tower that can grasp the holdup over time and maintain extraction appropriately in order to ensure steady operation.

Rotating disk extraction column (also called RDC extraction column, hereinafter referred to as RDO)
A column (abbreviated as "column" for short) is a typical liquid-liquid extraction device equipped with a stirrer, and its structure is schematically shown in FIG. That is, inside the upright cylindrical tower body l, a large number of annular fixing plates fixed horizontally at substantially equal intervals are provided, dividing the inside of the tower into a plurality of compartments. A rotating shaft 3 is provided at the central axis position of the tower body l, and this rotating shaft 3 has five disc-shaped rotating plates μ for stirring, one for each compartment partitioned by the fixed plate. Many sheets are provided.

Among the liquid phases used in liquid-liquid extraction, the liquid with low density (light liquid) is placed in the inlet pipe at the bottom of the column! The liquid with higher density (heavy liquid) is introduced from the introduction pipe A at the top of the tower, and the two liquids come into contact with each other in countercurrent flow inside the tower to perform extraction. At this time, the light liquid rising in the tower or the descending heavy liquid is rotated by rotating plate <46
The rotation results in fine dispersed droplets, which as they ascend in an annular manner achieve a good contact effect.

The heavy liquid and light liquid that have come into contact with each other at the extraction section indicated by 8 in the lit diagram pass through the heavy liquid clarification section indicated by B and the light liquid clarification section indicated by C in the figure, respectively, and then pass through the heavy liquid phase outlet pipe 7 and the light It is taken out of the system through the liquid phase outlet pipe. In the figure, RI and IO are grid, // is liquid level,
/2 is the interface.

Note that if strict separation is required or if separation is relatively difficult, a separate aftersettler may be installed.

This liquid-liquid extraction is often operated with a light dispersed phase, and in this case the interface between the 1 and 2 liquids occurs in the clarification section at the top of the column. Steady operation of the extractor is achieved by automatically or manually controlling the extraction of the heavy liquid so as to keep the position of this interface constant.

The efficiency of extraction (degree of mass transfer per contact length) is increased by increasing the contact interfacial area of the dispersion droplets, i.e. the smaller the droplet size of the dispersion, the better the extraction efficiency.However, if the unrestricted liquid The miniaturization of the droplet size leads to an increase in the residence time of the droplets in each compartment in the column, which eventually leads to the emulsion of the λ liquid, which impedes clarification at the top and bottom of the column, and increases the retention time of the droplets in each compartment in the column. Light liquid or heavy liquid may be mixed into the light liquid and withdrawn, making normal mass transfer operations impossible.

In other words, flooding will occur.

Furthermore, an increase in the dispersed phase beyond a certain level does not lead to improvement in effectiveness and may result in the so-called "kokuku mixing" phenomenon, and therefore should not be tolerated indefinitely.

The retention amount of the dispersed phase in the tower, which is determined by the size of the dispersed droplets as described above, is generally called the hold up.The factors that control this hold up are the diameter of the rotating plate and the annular fixed plate forming the compartment. In addition to the geometrical shape of the tower, such as the inner diameter, the length of the compartments, and the distance between the annular fixed plate and the earth, it is believed that operational factors such as the feed flow rate and the volume ratio of the feed liquid are involved.

However, in an extraction device such as an RDC tower in which the contact moving part is changed by a rotating body, among various factors, the number of rotations per unit time of the rotating body is a major factor governing dispersed phase hold-up. The relationship shown in FIG. 2 is generally known between the rotational speed of the rotating body and the holdup. That is, in FIG. 2, the horizontal axis shows the number of rotations per unit time, and the vertical axis shows the hold-up of the dispersed phase.
This graphically shows the relationship between hold-up and rotational speed. As shown in this figure, the hold up initially decreases as the rotational speed increases, in the area marked I, then in the area where it does not change much (the area marked ■), and then holds as the rotational speed increases to 0. It is divided into areas with thick edges (areas marked with ■).

The river area can be further divided into area A, where the increase in hold up is relatively small, and area A, where the increase is rapid. Regarding the operation of the RDq tower, the ■ area is usually selected in terms of extraction efficiency and operability.

As the rotation speed increases further, it will finally reach the flooding region (
The area marked with ■) is reached, and driving becomes impossible.

As mentioned above, it is well known that it is fundamentally important to control the hold-up by the rotational speed of the rotating body of the tower. However, the relationship between this rotation speed and the hold up is determined by other equipment conditions that affect the hold up, such as the diameter of the rotor disk, the length of the compartment, the open diameter of the annular plate, and the diameter of the column. It is assumed that the charging flow rate and the charging flow rate ratio of light and heavy liquids are constant. Therefore, in order to operate the existing equipment of this type efficiently and stably, it is necessary to
It has become extremely important to understand how the rotational speed of the rotating body affects the holdup in the column under conditions of changing the amount (processing capacity) and liquid ratio (related to extraction efficiency). For example, when increasing the charging flow rate to raise the processing lid, the hold-up usually tends to increase due to the inflow energy amplification port.If this increase is considered to be near flooding, the rotation speed of the rotating body should be adjusted appropriately. Flooding can be prevented by lowering the rotation speed to 8 degrees.Furthermore, if this 8 degree reduction in rotation speed is not too low, the drop in efficiency can be kept to a minimum.Also, when the composition of the processing solution changes, especially when the emulsifier is used, the droplet dispersion may be influenced by its concentration. In such cases, it is important to understand the hold up as a guideline to ensure stability of operation. desirable.

As mentioned above, knowing about VC hold up is R.
Although this method is extremely effective for dynamic use of DO towers, there is still no known method for effectively determining hold-up on an industrial scale.

Therefore, as a result of various studies while proceeding with the operation of an RDO tower on an industrial scale, the inventors of the present invention have determined that, as a means of grasping the hold-up during operation over time, they have developed a method for controlling the dispersion phase and continuous phase. We have found that it is practical to utilize the density difference and use it as a representative value for hold-up, and have completed the present invention.

To explain the operation of the present invention in principle, as the proportion of the amount of the dispersed phase increases, the total liquid density in the column changes depending on the volume ratio of the dispersed phase to the continuous phase. It attempts to capture minute changes as changes in hold up. This amount of change varies depending on the height of the column and the density difference of the extracted heavy liquid, but it is generally minute compared to the liquid pressure of the entire RDC column, so it is generally not possible to detect the pressure at the bottom of the RDO column. Extremely impractical. In addition, there is no particular problem when the same type of extraction is always performed in the RDO tower (extracting the same extractable material with the same light or heavy liquid), but when switching to a different type of extraction, practical problems arise. The difficulty increases further.

In order to solve this difficulty, the present invention uses a set of differential pressure gauges in order to grasp the liquid pressure derived from fine density. One of the differential pressure gauges is connected to the liquid pressure of the entire RDO tower (it does not necessarily need to be connected to the lowest position of the tower (it can be connected to a fixed position at the bottom of the tower), and the other is the reference pressure, that is, the pressure that does not change. Therefore, it is possible to connect the pressure to one that exhibits a pressure that is not significantly different from the tower liquid pressure in the operating state of the RDO tower.By doing so, changes in the bottom pressure during RDC tower operation can be sufficiently detected as a difference from the standard pressure. be.

The standard pressure can be set by using the hydrostatic pressure head of the continuous phase body of the RDO tower, or by using a certain liquid (t)t.
may be connected to a hydraulic head of any liquid (for example, a water leg) or may be connected to a certain gas (e.g., air) pressure head.

In this way, the change over time in the liquid pressure of the entire RDO tower can be known by the difference from the reference pressure, and this can be recorded on the time recorder, or can be known only on the display meter.

It is also possible to feedback-control this change over time to the rotational speed of the rotating body of the RDO tower to measure changes in operation.

As described above, according to the present invention, a hold-up can be quickly and accurately viewed in four directions. Compared to a distillation column that performs the same mass transfer operation, it is difficult to apply instrumentation equipment to RD.
Conventionally, with Oi5, it is difficult to judge the process from a hold-up abnormality to a flattening. However, with the present invention, it has become possible to understand the hold-up, which is a fundamentally important factor in continuous extraction equipment.
Decrease in extraction efficiency due to flooding or lower operating load is now prevented.

Embodiments of the present invention will be described in conjunction with a description of the next aspect.

Figure 3 is a schematic diagram of the entire apparatus related to the invention, in which 27 is the column main body, 2.2 is the light liquid introduction pipe, 3 is the heavy liquid introduction pipe 1.24' is the NtL phase outlet pipe 1.21 is the light liquid phase outlet pipe 1.2 is the interface, λ7 is the liquid level, 2g and λ are the grids, 30 is the reference head pressure piping, 31 is the pneumatic differential pressure transmitter, 3- is the entire tower Piping connected to the differential pressure transmitter 31, 33 is a pipe connecting the reference pressure of the reference head queen 'U to the differential pressure transmitter 31, 3≠ is a bypass pipe, 3j is a valve, 36
is piping. Although the rotating shaft, rotating plate, and fixed plate in the RDC tower are not shown in this figure, they are installed according to the structure of the apparatus shown in FIG. 7.

First, as shown in Figure 3, we created a total of several interfaces, heavy liquid, and light liquid, and installed three bypass pipe valves. j; no b
(and reference head pressure piping 30VchDO tower total liquid height (
A liquid that meets t'C can be produced. The other end of the reference head pressure pipe 30 is connected to I (DC!) so that the pressure is the same as that of the gas phase of the column main body.
Connect with pipe 3 and open to the atmosphere through 70 meters or vent condenser. The distance between the position of the 3 pipes in the tower body 1 (1 (the position of DI-3 tower ≠ θθ from the bottom) and the interface, 2 OJ is /l♂tOJ, the interface -6 and the liquid space, 27, a liquid column corresponding to the total liquid of this RDO tower is created in the standard head pressure piping 3Q.If a liquid column is created in the standard head pressure piping 3o, the valve 3j is
"Jill." Then, the RDC tower hydraulic pressure side force of the three pneumatic differential pressure transmitters (Y//, tA-LS, 2/GAS-FM manufactured by Yokogawa Electric) is PL, and the same is the standard head pressure on the piping side. When the pressure tPH is determined, PL=PH, and the differential pressure generated at the transmitter 3/ is 0.

The specific gravity of the heavy liquid is 7, and the specific gravity of the light liquid is 0. If r7, PL=/61tO×0.970+4tjO￥, 0.17
0': tA 7413.7MmH2O, P
H is also / 47 g and 7 g @ R20, and the PHO liquid column height is / A 7 F! , 710. ri70=17J Otsu3
．． It becomes lr@@.

The reference head pressure is set as described above, and the RDC tower is operated. The tracking of the measuring device as the hold-up rate changes from O% to /1% corresponds to the specific gravity of the heavy liquid in the column, that is, the value of PL is the value corresponding to the change in the specific gravity of the heavy liquid in the above formula. Become. However, the PH value changes over time (, /47&j
, 7MmH2O. The differential pressure that changes over time can be replaced by an air pressure signal and displayed on the recorder.

As an example of this, a differential pressure transmitter adjusted to a maximum differential pressure of 63 MmH2O (bold up/j%) is used.

At this 6th turn, the recorder indicates 100% when the hold is up/f%. When operating in this manner, the relationship among hold up, specific gravity of heavy liquid in the column, differential pressure, and recorder indications are as follows.

As described above, since the recorder shows the change in hold-up over time, the rotation speed of the rotating shaft of the RDO tower is adjusted based on this. This aspect is illustrated by flow silt in FIG. In the figure, aO is a pneumatic differential pressure transmitter, and l/ is a diaphragm capsule for differential pressure detection.

The hydraulic pressure of the RDO tower is transmitted from 12, the hydraulic pressure of the reference head pressure piping is transmitted from μ3, air is supplied from μt,
This is l! Then, as an air signal, the pneumatic recorder 4 is transmitted to O (hold up is recorded) (1 horizontal tube manufactured by the factory, NRP used). While watching this recorder QA, manually adjust the rotating shaft rotation speed adjustment volume 1iL7, and this is sent to the rotation speed controller Adjust the number. zi is an indicator of the number of revolutions about the rotation axis t.

In addition, although Fig. μ shows the case where the rotating shaft rotation speed adjustment polylambda 7 is operated manually, the pneumatic differential pressure transmitter 4tQ
It can also be automated by connecting the signal from the rotor to the rotation speed controller through a bold-up controller.

Although not shown in Fig. 3, the operating temperature of the RDC tower is raised to a temperature suitable for each extraction, and the liquid introduced into the standard head pressure piping is heated by the thermal IJI body to the standard head pressure piping. It is a good idea to keep the pipes warm 3. It is also a good idea to cover these pipes with a heat insulating material such as asbestos ribbon tape. Further, the reference head pressure piping is preferably provided with an outlet for discharging the liquid in the piping when changing the name of the extraction product.

What has been explained above and shown on page 1gI is related to typical examples to help the understanding of the present invention, and the present invention is not limited to these examples (other modifications and changes may be made within the gist of the invention). Modifications can be made.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of the structure of a rotating disc extraction tower, Fig. 2 is a chart showing the relationship between the rotation speed of the rotor and the hold-up in the rotating disc extraction tower, and Fig. 3 is a diagram of the rotary disc extraction tower of the present invention. The schematic diagram and ig diagram of the extraction tower are explanatory diagrams illustrating a mechanism for adjusting the rotational speed of the rotating body in response to changes in the holdup using the extraction tower of the present invention. In the figure, 2/ is the main body of the rotating disk extraction column, Noko is the light liquid introduction pipe, λ3 is the heavy liquid introduction pipe, and 211 is the heavy liquid phase outlet pipe 1.2j.
1. 2) is the light liquid phase lead-out pipe, 2) is the interface, 30 is the reference head pressure piping, and 3) is the pneumatic differential pressure transmitter. Kuzu 1 Ku Kuzu 2 Diagram ' times Kurumu Soft Man 4 Diagram

Claims (2)

[Claims] (1) It has multiple rotating discs inside, and light liquid is supplied from the bottom.
In an extraction tower where a heavy liquid is introduced from the top, a light liquid phase is taken out from the top, and a heavy liquid phase is taken out from the bottom, the pressure difference between the pressure at the bottom of the extraction tower and the standard head pressure is measured. Rotating disk extraction tower equipped with a pressure gauge (2) In an extraction tower that has a plurality of rotating disks inside, introduces light liquid from the lower part and heavy liquid from the upper part, and extracts the light liquid phase from the upper part and the heavy liquid phase from the lower part, this extraction tower A rotating disk extractor equipped with a differential pressure gauge that can measure the differential pressure between the pressure at the bottom of the column and the reference head pressure, and a mechanism that adjusts the rotation speed of the rotating disk according to fluctuations in the differential pressure of the differential pressure gauge. tower