JP3306516B2 - Rectification column for air liquefaction separation unit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rectification column for an air liquefaction / separation device, and more particularly to an air liquefaction / separation device in which a regular packing material is filled in the column and a rising gas and a reflux liquid are brought into countercurrent gas-liquid contact. For rectification towers.

[0002]

2. Description of the Related Art An air liquefaction / separation apparatus introduces compressed, purified and cooled raw material air into a rectification column to perform liquefaction / rectification separation.
It separates oxygen, nitrogen, argon, etc., which are air components. As a rectification tower used in such an air liquefaction separation device, instead of a rectifying tower in which rectification plates are arranged in multiple stages in the vertical direction, an ultra-thin metal sheet or the like is formed according to a certain rule. A packed rectification column using a processed structured packing material has begun to be used (Japanese Patent Application Laid-Open Nos. 50-16670 and 6-163).
0-238101, 63-151331, etc.). This packed rectification column has the advantage that the pressure loss is significantly lower than the conventional tray rectification column,
It is possible to reduce the power cost.

[0003]

However, in the packed rectification column, the liquid (reflux liquid) which flows down in a thin film form from the upper liquid distributor onto the surface of the structured packing material and which rises from the lower side. The rectification is performed by bringing the incoming gas (rising gas) into countercurrent gas-liquid contact. At this time, the thickness of the liquid film flowing down the surface of the packing material is at most several tens to several hundreds μm,
Therefore, there is a disadvantage that the liquid film thickness is affected by the fluctuation of the liquid amount supplied to the column, and as a result, the rectification / separation performance is sensitively changed.

[0004] In particular, when a high-purity product on the order of ppm or more is collected by a packed rectification column, fluctuations in the amount of reflux liquid greatly affect the product purity. Was difficult.

Accordingly, the present invention provides a rectification column for an air liquefaction / separation apparatus which can supply a reflux liquid stably to the ordered packing portion of the packed rectification column and can perform a stable operation. It is intended to be.

[0006]

In order to achieve the above object, a rectification column for an air liquefaction / separation apparatus according to the present invention has, as a first configuration, at least one plate-stage type in a reflux liquid introduction section. Along with disposing a rectifying plate, at the bottom of the plate-type rectifying plate,
A liquid distributor for uniformly supplying a reflux liquid to the ordered packing material is provided.

A second structure is that the reflux liquid introduction section has a vertical section almost entirely within the column, and has a rising gas rising section and a large number of through-holes for flowing the liquid, and a predetermined amount of liquid is provided on the upper surface thereof. It is characterized in that a perforated plate type liquid distributor capable of storing the reflux liquid is provided.

[0008] A third configuration is that a partition plate having a large number of small-diameter through holes for partitioning the liquid into the reflux liquid introducing section and substantially the entire cross section of the tower is provided above and below the partition plate. A perforated plate-type liquid collecting / distributing device provided with a rising gas passage and a refluxing liquid holding gas vent having a height at which the reflux liquid can be collected and stored and an upper lid portion.

In a fourth structure, the column is filled with a structured packing material, and the rising gas and at least a part of the rising gas are liquefied by a plate-fin condenser to flow into a reflux liquid flowing down the column. In the rectification column for the air liquefaction and separation device to be brought into contact with flowing gas and liquid, the condensed gas introduction portion of the plate fin type condenser,
The flow rate of the condensed gas is adjusted so that the level of the condensed liquid condensed in the condenser in a path from the top of the plate fin type heat exchanger of the condenser to the reflux liquid inlet of the rectification column is kept constant. It is characterized by the fact that a control valve is provided.

A fifth configuration is that the condenser in the condensate outlet of the plate fin condenser is provided in the path from the top of the plate fin heat exchanger of the condenser to the reflux inlet of the rectification column. A control valve for adjusting the flow rate of the condensed liquid is provided so as to keep the level of the condensed liquid condensed in step (1).

A sixth configuration is a rectification column for an air liquefaction / separation apparatus, in which a column is filled with a structured packing material, and a rising gas and a reflux liquid supplied through a conduit are brought into countercurrent gas-liquid contact.
A liquid reservoir is provided in the conduit, and a flow control valve for controlling a flow rate of a reflux liquid introduced into the rectification column is provided between the liquid reservoir and a liquid introduction section of the rectification column. And

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to the embodiments shown in the drawings. In the following description, the entire configuration of the air liquefaction separation device and the configuration of the rectification column itself,
For example, double rectification column or single rectification column, crude argon column,
The high purity argon column or the like is not particularly limited, and the shape of the ordered packing material filled in the column is also arbitrary,
The present invention can be applied to rectification columns for various types and configurations of well-known air liquefaction / separation devices. The description is omitted.

FIG. 1 is a sectional view of an essential part of a rectification column showing an embodiment corresponding to the first configuration. This embodiment is of a type in which a liquefied gas is introduced from the conduit 2 to the top of the rectification column 1 to form a reflux liquid, and the product gas is led out from the conduit 3. For example, the upper column of the double rectification column It corresponds to the top and the like.

The rectification column 1 is provided above the structured packing 4
A three-stage rectifying plate 5 is provided, and a liquid distributor 6 is provided below the rectifying plate 5. The rising gas from the ordered packing material 4 is After being rectified by the tray-type rectification plate 5, the rectified product is led out from the conduit 3.

One of the reflux liquids flows down from the conduit 2 to a liquid storage portion 5a provided at one end of the uppermost plate-type rectification plate 5, and flows to the rectification portion 5b to contact the rising gas. The rectifying operation is performed, and the rectification flows down from the downstream portion 5c at the other end to the liquid storage portion 5d of the lower shelf rectification plate 5. And, the bottom shelf type rectifying plate 5
From the downstream part 5e to the liquid distributor 6, and from the liquid distributor 6 to the layer of the ordered packing material 4 uniformly.

By arranging the tray type rectifying plate 5 above the structured packing material 4 as described above, the fluctuation of the gas purity at the part of the structured packing material 4 can be reduced. It can be absorbed by rectification, and the purity of the product gas can be stabilized. That is, a liquid having a clarified liquid depth of 5 to 10 mm is constantly stored on the tray-type rectification plate 5, and even if the flow rate of the liquid supplied from the conduit 2 fluctuates, it is like the regular packing material 4. The effect of the above is that the contact between the rising gas and the reflux liquid is ensured, so that the purity of the gas derived from the conduit 3 can be stabilized.

The shelf-type rectifying plate 5 is not limited to a well-known sieve tray or a bubble-bell rectifying plate.
It is sufficient if the liquid is placed on the plate and gas-liquid contact with the rising gas is possible. The number of stages of the shelf-type rectification plate 5 is one.
Sufficient effects can be expected with only the stage, and it may be appropriately selected according to the product purity and the throughput.

Next, FIG. 2 shows an embodiment corresponding to the second configuration, in which a perforated plate type liquid distributor 11 is disposed at the introduction portion of the reflux liquid above the structured packing material 4. is there. The perforated plate type liquid distributor 11 is formed by a perforated plate 13 having a large number of through-holes 12 for liquid flow evenly formed on substantially the entire surface thereof. The size of the perforated plate 13 is formed by using the entire cross section of the rectification column 1 so as to partition up and down substantially the entire area in the rectification column 1 so as to form a liquid pool area as large as possible. the porous plate 13, cylindrical or square tubular ascending vapor rising portion for passing the ascending gas (vent pipe) 1 5 is provided.

The diameter and the number of the through-holes 12 for liquid flow are determined by the amount of liquid (the amount of processing) supplied from the conduit 2. As described above, it is preferably set so that the reflux liquid can be held at a liquid depth of several hundred mm or more.

As described above, by disposing the perforated plate type liquid distributor 11 having a large liquid storage area in the reflux liquid introduction section above the ordered packing material 4, fluctuations in the amount of liquid supplied from the conduit 2 ( Pulsation) can be mitigated as minute vertical movements of the liquid depth on the perforated plate type liquid distributor 11, and flow down from the many through holes 12 of the perforated plate type liquid distributor 11 toward the ordered packing material 4. It is possible to stabilize the amount of the reflux liquid.

Therefore, the rectification and separation at the part of the structured packing material 4 is stabilized, and the perforated plate type liquid distributor 11 is separated from the structured packing material 4.
The purity of the gas derived from the conduit 3 via the rising gas rising portion 13 can be stabilized.

Incidentally, the conventional perforated plate type liquid distributor is usually used only when the tower diameter is small and a tube type or box type liquid distributor cannot be installed. When the perforated plate type liquid distributor is used when the liquid flow rate pulsates, the liquid pool part on the upper surface serves as a buffer tank, so that the amount of liquid flowing down from the through hole depends on the pulsation of the supply amount. And almost stable even if the gas discharged from the top of the rectification column is of high purity compared to the case where a tube type or box type with a small liquid pool area is used as the liquid distributor. Can be

Further, in order to absorb the pulsation of the supply liquid amount, a liquid reservoir having a large liquid reservoir area is formed by a flat plate and a vent pipe, and the liquid collected here is provided below the ordinary liquid reservoir. Even if it is configured to flow down to the liquid distributor, substantially the same effect can be obtained.

FIGS. 3 to 7 show an embodiment corresponding to the third configuration, in which the perforated plate type liquid distributor of FIG. 2 is further provided with a function of a liquid collector. . Similar to FIG. 2, in the figure, reference numeral 1 denotes a rectification column, which represents, for example, the vicinity of the oxygen-enriched liquefied air introduction portion in the middle of the upper column of the double rectification column. Reference numeral 2 denotes a conduit for introducing oxygen-enriched liquefied air into the rectification column 1, and reference numerals 4a and 4b denote ordered packings, respectively.

The perforated plate type liquid collecting / distributing device 11 'provided here has a large number of through holes 1 for liquid flow evenly over substantially the entire surface thereof.
2 is formed by a perforated plate 13 having a perforated plate 2 and a vent 15 for an ascending gas passage with an upper lid 14 provided in the shape of the perforated plate 13.

The vent portion 15 for the ascending gas passage is formed of a cylindrical or rectangular tubular member having a height capable of sufficiently holding the liquid to be retained. For example, FIG.
, The vent portion 15 for the rising gas passage is cylindrical (chimney shape)
FIG. 5 is a diagram in which a vent portion 15 is formed by a rectangular tubular member having a rectangular cross section, and a roof-like upper cover 14 is provided above the umbrella-shaped upper cover 14. is there.

FIGS. 6 and 7 show a double tube type in which a space for gas rise is formed between the inner peripheral wall of the rectification column 1 and the inside diameter of the rectification column 1. A perforated plate 13 having a smaller diameter is supported by support members 13a provided at appropriate intervals, and a cylindrical member 15a having an outer diameter smaller than the inner diameter of the rectification tower 1 is rectified on the outer peripheral edge of the perforated plate 13. A concentric circle is provided with the tower 1, and a space between the cylindrical member 15 a and the inner peripheral wall of the rectification tower 1 is defined as a vent portion 15.
Above 5, a ring-shaped upper lid 14 is provided such that its inner peripheral edge is inclined downward toward the center.

In the embodiment shown in FIGS. 6 and 7, the rectification column 1 is used as the outer tube of the double tube, but the rectification column 1 is provided with a member for forming the outer tube. It may be a heavy pipe structure,
The inside of the rectification column 1 may be divided into a plurality of sections, and a plurality of perforated plate type liquid collecting / distributing units 11 'having a double pipe structure may be provided.

Each of the perforated plate type liquid collecting and distributing units 11 'is
While temporarily holding the reflux liquid from the upper part of the upper column filled with the ordered packing material 4a, the oxygen-enriched liquefied air introduced from the conduit 2 is retained on the perforated plate 13 to form a through hole composed of many small holes. From 12, the indwelling liquid is supplied uniformly to the lower part of the upper column filled with the ordered packing material 4 b.

In this case, for example, when the amount of oxygen-enriched liquefied air supplied from the conduit 2 fluctuates or the amount of reflux liquid from the upper part of the upper column fluctuates, the regulation below the oxygen-enriched liquefied air supply stage is reduced. The rectification conditions of the filler 4b also fluctuate accordingly, adversely affecting rectification separation performance. The amount of the reflux liquid supplied from the conduit 2 or the like is changed by performing quantitative adjustment depending on the operating conditions, and the amount of the reflux liquid in the portion filled with the structured filler 4b is appropriately changed according to the change. I have to do it. The perforated plate-type liquid collecting / distributing device 11 ′ appropriately sets the liquid depth by appropriately setting the diameter of the through-hole 12 and the liquid holding height of the vent portion 15, thereby reducing the amount of the reflux liquid. In addition to preventing pulsation, it is possible to provide a function capable of appropriately coping with the change in the turndown ratio described above.

FIGS. 8 and 9 show an embodiment in which a liquid liquefied by a plate fin condenser is introduced into the column as a reflux liquid. FIG. 8 shows one embodiment corresponding to the fourth structure. FIG. 9 shows an embodiment corresponding to the fifth configuration, and corresponds to, for example, the top of a single rectification column or the bottom of a double rectification column.

8 and 9, the gas which has risen to the top of the rectification column 1 is led out to the conduit 3 and a part is led out from the conduit 21 as product gas, and the remainder branches off to the conduit 22 to be condensed. 23 is introduced as a condensed gas. Condenser 23
Is immersed in the liquefied gas supplied from the conduit 24, the liquefied gas and the condensed gas perform heat exchange, and the liquefied gas is vaporized and led out from the conduit 25, and the condensed gas is liquefied. Condensate is led to conduit 26.

A part of the condensate discharged to the conduit 26 branches off to a conduit 27, is discharged via a valve 28, and the rest is introduced into the rectification column 1 by a conduit 30 having a valve 29, and is condensed by a liquid. It flows down from the vessel 6 to the layer of the ordered packing material 4 as a reflux liquid.

As described above, the plate-fin condenser 2
In the case of the rectification column in which No. 3 is combined, even if each conduit and valve are appropriately designed based on the amount of condensed liquid, a gas-liquid two-phase flow due to heat intrusion into each part and the like, resulting in an unexpected pulsating flow. However, when such a pulsation occurs, the supply state of the reflux liquid becomes unstable, the liquid film thickness and distribution state on the surface of the ordered packing material 4 become unstable, and the purity of the product gas led out from the conduit 21 is increased. Becomes unstable.

In order to avoid such a pulsation of the condensed liquid, the rectification column 1 is connected to the path from the condenser 23 to the conduit 30, that is, from the top of the plate fin type heat exchanger of the condenser 23.
A liquid reservoir having a certain liquid height may be provided in a path leading to the reflux liquid introduction section to absorb pulsation and provide a substantially constant liquid head to the reflux liquid.

As means for providing a liquid reservoir for providing a substantially constant liquid head, in the apparatus shown in FIG. 8, a flow control valve 31 is provided in the conduit 22 on the gas inlet side of the condenser 23 so that the rectification column 1 By adjusting the pressure difference between the pressure and the pressure on the gas inlet side of the condenser 23, the condensed liquid level is kept constant. 9, a flow control valve 32 is provided in the conduit 26 on the condensed liquid outlet side of the condenser 23, and the valve 3
By adjusting the flow resistance in 2, the condensate level is kept constant.

The position for holding the liquid level is appropriately set according to the required processing capacity.
The condensed liquid level may always be held in the lower part of the condensing passage. If there is room in the conduit 26, the liquid level may be set in the middle of the conduit 26.

Means for adjusting the opening of the flow control valves 31, 32 in order to maintain the liquid level at a predetermined position includes:
A flow meter (not shown) is provided in the reflux liquid supply conduit 30 to directly confirm that the flow rate of the reflux liquid is stable and adjust the opening degree, or to adjust the liquid level by the liquid level meter 33. The method of monitoring the state of the reflux liquid indirectly by monitoring the fluctuation state of the flow rate or monitoring the purity of the product gas by the analyzer 34 and thereby adjusting the opening of the flow rate control valves 31 and 32 is adopted. can do.

Further, in both of the embodiments shown in FIGS. 8 and 9, the flow control valves 31 and 32 are separately provided. However, both the flow control valves 31 and 32 may be provided at the same time. .

Here, the result of an experiment for confirming the effect of the flow control valve will be described. That is, in the apparatus shown in FIG. 9, the amount of condensed liquefied nitrogen flowing through the conduit 26 was set to 470 Nm ³ / h by adjusting the flow control valve 32, and the flow was stabilized. The oxygen concentration in the derived nitrogen gas is 31 to 33 pp
m.

On the other hand, by fixing the opening of the flow control valve 32,
That is, when the experiment was performed in the same manner as without the flow control valve 32, the flow rate of the condensed liquefied nitrogen flowing through the conduit 26 was 38
Vigorously in the range of 0 to 500 Nm ³ / h,
The oxygen concentration in the nitrogen gas derived from
pm.

FIG. 10 and FIG. 11 show an embodiment corresponding to the fifth configuration, and a conduit 41 for supplying a reflux liquid.
A liquid reservoir 42 is disposed in the
A flow control valve 43 for controlling the flow rate of the reflux liquid is provided in a conduit 41a between the liquid introduction section and the liquid introduction section.

First, in FIG. 10, the reflux liquid supplied to the rectification column 1 is supplied from the top of the rectification column 1 and introduced into the condenser 44 in the same manner as in FIGS. It is obtained by condensing and liquefying. That is, the gas at the top of the rectification column 1 is led out to the conduit 45, a part of the gas is collected from the conduit 46 as product gas, and the remainder is introduced from the conduit 47 to the condenser 44 to be condensed and liquefied. It is led out and introduced into the liquid reservoir 42. Note that a cold source for condensing the gas is introduced into the condenser 44 from the conduit 48 and
Is derived.

A certain amount of liquid is always stored in the liquid reservoir 42, and the liquid in the liquid reservoir 42 is supplied to the liquid distributor 6 at a constant flow rate via the flow control valve 43.
The liquid in the liquid reservoir 42 is partially converted into a liquefied gas by the conduit 5.
The gas derived from 0 through the valve 51 and evaporated in the liquid reservoir 42 is guided to the conduit 52 and merges with the gas guided to the conduit 45.

In the above configuration, if the level of the liquid in the liquid reservoir 42 changes greatly, a flow indicator controller (FIC) 53 may be provided to adjust the opening of the flow control valve 43. Although a pulsation occurs, the flow rate control valve 43 may be manually adjusted when the time-averaged liquid volume is stable and there is almost no change in the liquid level in the liquid reservoir 42.

FIG. 11 shows a case where the liquid is supplied to the middle stage of the rectification column 1, and corresponds to, for example, a portion for introducing oxygen-enriched liquefied air to the middle stage of the upper column of the double rectification column. Thus, even when supplying the reflux liquid to the middle stage of the rectification column,
When the amount of the supply liquid fluctuates, the amount of the reflux liquid in the part of the structured packing below the reflux liquid introduction part fluctuates, which affects the rectification and separation performance.

As in the case of FIG.
2. Flow indication controller 53, flow control valve 43, conduit 41a
The liquid whose flow rate has been adjusted through is supplied to the upper surface of a liquid collector 61 provided in the rectification column 1 first. The liquid collector 61 is provided with a partition plate 62 for vertically dividing the inside of the rectification column 1.
Is provided with a vent pipe 63 having an upper lid through which a rising gas is passed, and a liquid distributor which mixes a liquid flowing down from the upper part of the structured packing material 4a and a liquid supplied from the conduit 41, and 6.

With this configuration, the conduit 41
Pulsation of the liquid supplied from the
It is possible to stabilize the amount of reflux liquid in the part of the ordered packing material 4b below the introduction part, and to perform stable rectification and separation.

The gas evaporated in the liquid reservoir 42 is introduced into the rectification column via the conduit 41b.

It is also possible to carry out the above embodiments in combination, and it is possible to adopt an appropriate structure depending on the type of the rectification column and the position of the top, the middle, and the like.

[0051]

As described above, according to the present invention,
It is possible to stabilize the amount of reflux liquid supplied to the ordered packing material filled in the rectification column, and it is possible to greatly improve and stabilize the rectification separation performance of this type of rectification column. This makes it possible to easily collect gases or liquids of high purity on the order of ppm or more as products, and reduce the power cost of the air-liquid or separator for producing these high-purity products.

[Brief description of the drawings]

FIG. 1 is a system diagram showing one embodiment of a first configuration of the present invention.

FIG. 2 is a system diagram showing one embodiment of the second configuration.

FIG. 3 is a system diagram showing an embodiment of a third configuration according to the present invention.

FIG. 4 is a partial cross-sectional plan view of a perforated plate type liquid collecting and distributing device provided with a cylindrical vent portion.

FIG. 5 is a partial cross-sectional plan view of a perforated plate type liquid collecting and distributing device provided with a rectangular cylindrical vent portion.

FIG. 6 is a partial cross-sectional plan view of a double tube type perforated plate type liquid collecting and distributing device.

FIG. 7 is a longitudinal sectional view of the same.

FIG. 8 is a system diagram showing one embodiment of a fourth configuration of the present invention.

FIG. 9 is a system diagram showing an example of the fifth configuration.

FIG. 10 is a system diagram showing one embodiment of the sixth configuration.

FIG. 11 is a system diagram showing another embodiment of the sixth configuration.

[Explanation of symbols]

1: rectification tower 4: ordered packing material 5: tray type rectification plate
Reference Signs List 6: Liquid distributor 11: Perforated plate type liquid distributor 11 '... Perforated plate type liquid collecting / distributing device 12: Through hole 13: Ascending gas rising part 23: Condenser 31, 32
... Flow control valve 33 ... Level gauge 34 ... Analyzer 42 ... Liquid reservoir 43
... Flow control valve 44 ... Condenser 53 ... Flow indication controller 61 ... Liquid collector 62 ... Partition plate 63 ... Vent pipe

Claims (6)

(57) [Claims] 1. A rectification column for an air liquefaction / separation apparatus in which a column is filled with a structured packing material and a rising gas and a reflux liquid are brought into countercurrent gas-liquid contact with each other. Air liquefaction separation, wherein a tray type rectification plate is provided, and a liquid distributor for uniformly supplying a reflux liquid to the structured packing material is provided below the plate type rectification plate. Equipment rectification tower. 2. A rectification column for an air liquefaction / separation apparatus in which a column is filled with a structured packing material and an ascending gas and a reflux liquid are brought into countercurrent gas-liquid contact with each other. The whole area is divided up and down, it has a rising gas rising part and a large number of through holes for liquid flowing down, and a perforated plate type liquid distributor capable of holding a predetermined amount of reflux liquid is disposed on the upper surface thereof. Rectification tower for air liquefaction separation unit. 3. A rectification column for an air liquefaction / separation device in which a column is filled with a structured packing material and a rising gas and a reflux liquid are brought into countercurrent gas-liquid contact with each other. A partition plate having a plurality of small-diameter through-holes for partitioning substantially the entire area up and down and having a large number of small-diameter through-holes, and a rising gas passage having a height and an upper lid portion capable of collecting and retaining a predetermined amount of reflux liquid on the partition plate. A rectification column for an air liquefaction / separation apparatus, comprising a perforated plate type liquid collecting / distributing device provided with a gas vent for holding a reflux liquid. 4. The column is filled with a structured packing material, and a rising gas and a reflux liquid which liquefies at least a part of the rising gas by a plate fin condenser and flows down the column flow in countercurrent gas-liquid contact. In the rectification column for an air liquefaction / separation device, the flow rate of the condensed gas is adjusted so that the level of the condensed liquid condensed in the condenser is kept constant in the condensed gas introduction section of the plate fin condenser. A rectification column for an air liquefaction separation device, comprising a control valve. 5. A column is filled with a structured packing material, and a rising gas and a reflux liquid which liquefies at least a part of the rising gas in a plate fin condenser and flows down in the column are in countercurrent gas-liquid contact. In the rectification column for an air liquefaction / separation apparatus, the flow rate of the condensed liquid is adjusted so that the level of the condensed liquid condensed in the condenser is kept constant at the condensed liquid outlet of the plate fin condenser. A rectification column for an air liquefaction separation device, comprising a control valve. 6. A rectification column for an air liquefaction / separation apparatus in which a column is filled with a structured packing material and an ascending gas and a reflux liquid supplied via a conduit are brought into countercurrent gas-liquid contact with each other. Air liquefaction, wherein a reservoir is provided and a flow control valve for controlling a flow rate of a reflux liquid introduced into the rectification column is provided between the liquid reservoir and a liquid introduction section of the rectification column. Rectification column for separation equipment.