JPH0731002B2 - Air liquefaction separation device - Google Patents

Description

The present invention relates to an air liquefaction separation device.

[Conventional technology]

FIG. 4 shows a conventional air liquefaction / separation device for collecting nitrogen using a single rectification column, and a condenser 2 is integrally provided on the upper part of the single rectification column 1. This condenser 2 is for expanding the liquefied air LA at the bottom of the tower with the expansion valve 3 to a low temperature and liquefying the nitrogen gas GN at the top of the tower.
The liquefied nitrogen LN liquefied in 1 flows down to the top of the single rectification column 1 by its own weight and becomes the reflux liquid of the single rectification column 1.

The raw material air A is cooled by the heat exchanger 4 and introduced into the lower part of the single rectification column 1, and is contacted with the reflux liquid flowing down from the upper part of the single rectification column 1 to be rectified, and nitrogen gas GN at the top of the column. And liquefied air LA enriched with oxygen at the bottom of the column. The liquefied air LA is introduced into the condenser 2 through the expansion valve 3, vaporized and vaporized into exhaust gas W, and is discharged from the upper portion of the condenser 2. Exhaust gas W
Is introduced into the expansion turbine 5 after raising its temperature in the heat exchanger 4 to generate cold, and is introduced into the heat exchanger 4 again to serve as a cooling source of the raw material air A.

On the other hand, the nitrogen gas GN at the top of the single rectification column 1 is discharged from the top of the column and a part of the nitrogen gas GN exchanges heat with the raw material air A in the heat exchanger 4, the temperature is recovered, and the product nitrogen gas PGN is collected. The remaining nitrogen gas GN is introduced into the nitrogen chamber of the condenser 2 and cooled by the liquefied air LA to be condensed and liquefied to become liquefied nitrogen LA.

A part of this liquid nitrogen LN is collected as product liquid nitrogen PLN, and the rest flows down to the top of the single rectification column 1 by its own weight to become a reflux liquid.

The low-temperature equipment such as the single rectification tower 1, the condenser 2, the heat exchanger 4 and the like are housed in the outer tank 6 as shown in FIG.
It is insulated from the outside.

Next, FIG. 6 shows an air liquefaction / separation device for collecting nitrogen and oxygen using a double rectification column, in which a condenser 13 is arranged between an upper column 11 and a lower column 12 of the double rectification column 10. It is set up.

The raw material air A is cooled to near the liquefaction point by the heat exchanger 14 and introduced into the lower part of the lower tower 12, and nitrogen gas GN at the top of the lower tower 12
And liquefied air LA enriched with oxygen at the bottom of the column. Further, a part of the raw material air A is introduced into the expansion turbine 15 from the intermediate portion of the heat exchanger 14, is expanded and becomes a low temperature, and is introduced into the middle stage of the upper tower 11.

The liquefied air LA at the bottom of the lower tower 12 is cooled by the subcooler 16 and the expansion valve 17
Is introduced into the middle stage of the upper tower 11 through the expansion turbine 15
Along with the raw material air A introduced into the upper tower 11 via the above, it is further rectified to become high-purity nitrogen gas HGN at the top of the tower and liquefied oxygen LO at the bottom of the tower. This liquefied oxygen LO is evaporated and vaporized in the condenser 13 to become oxygen gas GO, a part of which is led out from the lower part of the upper tower 11, the temperature is recovered in the heat exchanger 14 and collected as product oxygen gas PGO, and the remaining The oxygen gas GO becomes the rising gas of the upper tower 11. In addition, part of the liquefied oxygen LO is discharged as a liquid,
It is taken as product liquefied oxygen PLO through the subcooler 16.

On the other hand, the nitrogen gas GN at the top of the lower tower 12 is introduced into the nitrogen chamber of the condenser 13 and cooled by the liquefied oxygen LO to be condensed and liquefied into liquefied nitrogen LN. The liquefied nitrogen LN is partially introduced as a reflux liquid to the top of the lower tower 12, the rest is branched after passing through the subcooler 16, and a part is collected as product liquid nitrogen PLN, and the rest is the expansion valve 18. After that, it is introduced to the top of the upper tower 11 and becomes the reflux liquid of the upper tower 11.

High-purity nitrogen gas HGN at the top of the upper tower 11 is collected as product nitrogen gas PGN through the supercooler 16 and the heat exchanger 14, and low-purity nitrogen gas WGN is discharged from the middle stage of the upper tower 11. After passing through the subcooler 16 and the heat exchanger 14, it is used for regenerating an adsorber (not shown).

The one using this double rectification column 10 is also housed in an outer tank which is insulated from the outside like the above-mentioned single rectification column (not shown).

[Problems to be solved by the invention]

However, in the above-mentioned one, the liquefied nitrogen LN liquefied in the condensers 2 and 13 is introduced into the top of the single rectification column 1 (the lower column 12 in the case of the double rectification column 10) by its own weight (liquid head), Since it is a reflux liquid, it was necessary to install the condensers 2 and 13 above the single rectification column 1 (lower column 12).

As a result, the height of the single rectification column 1 (double rectification column 10) becomes higher than that of other equipment housed in the outer tub 6, and a dead space 7 is formed above the heat exchanger in the outer tub 6. Had (the fifth
Figure).

Therefore, an object of the present invention is to provide an air liquefaction / separation device that can effectively use the space in the outer tank and can reduce the power consumption.

[Means for solving problems]

In order to achieve the above-mentioned object, the present invention provides compression, purification,
Air liquefaction separation for rectifying and separating oxygen, nitrogen, etc. by contacting the raw material air that is cooled and introduced into the lower part of the rectification tower with the reflux liquid that is liquefied in the condenser and flows down from the upper part of the rectification tower In the apparatus, the condenser is arranged on the side of the rectification column, and a thermosiphon heat exchanger for pumping liquid for introducing the liquefied gas liquefied in the condenser as a reflux liquid into the upper part of the rectification column is provided. The hot fluid of the thermosiphon heat exchanger is the raw material air, or product nitrogen heated after being discharged from the rectification column, low-purity nitrogen, exhaust gas, or the like.

[Action]

Therefore, since the condenser can be arranged in the part that has been a dead space in the past, the space in the outer tank can be effectively used,
The outer tank can be made smaller to reduce heat loss,
Since liquid is pumped up by a thermosiphon heat exchanger using raw air or the like as a warm fluid, power for a liquefied gas pump or the like is not required and power cost does not increase. When the outer tank has the same volume, the rectification column can be made high, that is, the number of rectification stages can be increased, so that the separation efficiency can be improved as compared with the conventional air liquefaction separation device.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. The same elements as those of the conventional example are designated by the same reference numerals, and detailed description thereof will be omitted.

First, FIG. 1 shows an air liquefaction / separation apparatus using a single rectification column, and corresponds to the air liquefaction / separation apparatus shown in FIG.

In this air liquefaction separation device 20, a condenser 21 is arranged laterally above the single rectification column 22 and above the heat exchanger 4, and a thermostat is provided between the condenser 21 and the single rectification column 22. Siphon heat exchanger 23
Are installed.

The condenser 21, like the conventional example, introduces the liquefied air LA at the bottom of the single rectification column 22 and the nitrogen gas GN at the top of the single rectification column 22 to evaporate the liquefied air LA and condense the nitrogen gas GN. The liquefied air LA evaporated from the upper part of the condenser 21 is discharged as the exhaust gas W, and the liquid nitrogen LN is discharged from the lower part.

Further, the thermosiphon heat exchanger 23 is for introducing the liquid nitrogen LN condensed in the condenser 21 to the top of the single rectification column 22 as a reflux liquid, and a part of the raw material air A is used as a warm fluid for the liquid. Part of the nitrogen LN is evaporated, and the liquid nitrogen LN is pumped by the ascending force of bubbles generated during evaporation.

Further, a liquid reservoir 24 for obtaining a liquid head of liquid nitrogen LN to be introduced into the thermosiphon heat exchanger 23 is provided below the condenser 21.

The apparatus will be described below according to the flow of gas and liquid.

The raw material air A cooled by the heat exchanger 4 branches after leaving the heat exchanger 4, and a part of the raw material air A is introduced into the thermosiphon heat exchanger 23 from above by a conduit 25, and a part of the liquid nitrogen LN is partly introduced. While evaporating, the liquid itself is slightly cooled and the liquefaction rate is increased, and is led out by the conduit 26 and introduced into the lower part of the single rectification column 22. The amount of the raw material air A introduced into the thermosiphon heat exchanger 23 is adjusted by the valve 27 provided at the introduction part of the single rectification column 22.

Then, the raw material air A introduced into the lower part of the single rectification column 22 is
Nitrogen gas GN at the top of the column and liquefied air enriched with oxygen at the bottom of the column are separated by rectification by contact with the reflux liquid flowing down in the single rectification column 22.
Become LA. The liquefied air LA passes through the expansion valve 3 and then the condenser 21.
And is vaporized to become exhaust gas W, which is led out from the upper part of the condenser 2. The exhaust gas W is heated in the heat exchanger 4 and then introduced into the expansion turbine 5 to generate cold, and then introduced into the heat exchanger 4 again to become a cooling source of the raw material air A and then discharged.

On the other hand, a part of the nitrogen gas GN derived from the top of the single rectification column 22 is introduced into the heat exchanger 4 to recover the temperature and is collected as product nitrogen gas PGN. The rest of the nitrogen gas GN is the condenser 2
It is introduced into the nitrogen chamber 1 and cooled by the liquefied air LA, condensed and liquefied into liquid nitrogen LN, which is stored in the liquid retainer 24. A part of this liquid nitrogen LN is collected as product liquefied nitrogen PLN, and the remaining part is introduced into the thermosiphon heat exchanger 23 to exchange heat with the raw material air A, and a part is evaporated and foamed to pump the liquid. And is introduced as a reflux liquid at the top of the single rectification column 22. At this time, the liquid nitrogen LN in the thermosiphon heat exchanger 23 is introduced by the liquid head in the liquid reservoir 24 in an amount necessary for pumping.

FIG. 2 shows a state in which the vapor-air liquefaction separation device 20 is housed in the outer tub 28. In the dead space portion (see reference numeral 7 in FIG. 5) that has conventionally been formed above the heat exchanger 4. Since the condenser 21 and the thermosiphon heat exchanger 23 can be arranged,
The space in the outer tank 28 can be effectively used, and the condenser 21 that is integrally disposed above the single rectification column 22 is located laterally of the single rectification column 22. The height can be made to correspond to the height of only the rectification column 22, and can be made lower than in the past. As a result, the volume and surface area of the outer tub 28 can be reduced, the device can be made compact, heat loss can be reduced, and power consumption can be reduced.

When the outer tank 28 is formed to have the same size as the conventional one by setting the size of the outer tank 28 to the maximum size during transportation, the single rectification column 22 can be made higher, and the number of rectification stages is increased accordingly. Can be a lot. As a result, the rectification efficiency is improved, the amount of the raw material air A can be reduced, and the power consumption rate can be reduced.

Next, FIG. 3 shows an example using a double rectification column, which corresponds to the air liquefaction separation apparatus shown in FIG.

In this air liquefaction separation device 30, a condenser 31 is arranged laterally of the double rectification column 32 and above the subcooler 16, and a thermostat is provided between the condenser 31 and the double rectification column 32. A siphon heat exchanger 33 is arranged.

This makes it possible to obtain the same effects as in the case of the air liquefaction separation device using the single rectification column.

Hereinafter, the flow of gas and liquid in the main part will be described.

The raw material air A is branched and used in three directions. First, the raw material air A1 branched in the middle of the heat exchanger 14 is the expansion turbine.
The raw air A2, which has been introduced into the upper tower 32 via 15 and branched before being introduced into the bottom of the lower tower 34, is used as a warm fluid of the thermosiphon heat exchanger 33, and then the lower tower 34 It is introduced at the bottom. And the remaining raw material air A3
Is introduced into the lower part of the lower tower 34, the flow rate of which is adjusted by the valve 37.

The nitrogen gas GN at the top of the lower tower 34 and the liquid nitrogen LO at the bottom of the upper tower 35 are introduced into the condenser 31, and the nitrogen gas GN condenses to liquid nitrogen LN, and the liquefied oxygen LO evaporates to produce oxygen gas.
Become GO. This oxygen gas GO is introduced from the upper part of the condenser 31 and returned to the lower part of the upper tower 35, part of which becomes ascending gas of the upper tower 35, and the remaining part is led out of the upper tower 35, and the heat exchanger 14
It is collected as a product oxygen gas PGO.

Further, the liquid nitrogen LN is discharged from the lower part of the condenser 31, introduced into the thermosiphon heat exchanger 33 via the liquid reservoir 36, pumped to the top of the lower tower 34, and becomes the reflux liquid of the lower tower 34. A part of the liquid nitrogen LN is branched through the subcooler 16, one of which is introduced as a reflux liquid at the top of the upper tower 32, and the other is the product liquid nitrogen.
Collected as PLN.

The high-purity nitrogen gas HGN, which is the product (PGN), is collected from the top of the upper tower 32, and the low-purity nitrogen gas WGN is collected from the middle stage.
Has been derived.

Further, in both of the above embodiments, the liquid reservoir provided between the condenser and the thermosiphon heat exchanger can be omitted when the liquid head of the thermosiphon heat exchanger can be obtained by other means. For example, when the diameter of the pipe on the outlet side of the condenser is sufficiently larger than the other pipes, this can be replaced. Also, each device, piping, etc. are appropriately set depending on the type, purity, and sampling amount of the product.

The above example is as a warm fluid of the thermosiphon heat exchanger,
This is the case where raw material air is used, but as this warm fluid, another fluid, for example, in the case of a single rectification column, exhaust gas heated by a heat exchanger after vaporization by a condenser may be used, or In the case of a rectification tower, product nitrogen, low-purity nitrogen, etc., which have been heated by a subcooler, a main heat exchanger, etc. after being discharged from the upper tower may be used.

Further, when a crude argon column or a high-purity argon column is attached to the double rectification column, the tops of these argon columns are conventionally set to be higher than the top of the double rectification column. According to the invention, each condenser of the crude argon column or the high-purity argon column can be installed beside each column, and the height of the outer tank can be similarly reduced.

〔The invention's effect〕

As described above, according to the present invention, a condenser is disposed on the side of a rectification column, which has conventionally been a dead space in an outer tank, and the liquefied gas liquefied by the condenser is subjected to thermosiphon heat exchange. Since it is pumped up by the vessel to make the reflux liquid of the rectification column,
When the same rectification tower as the conventional one is used, the outer tank can be made smaller and heat loss can be reduced, and when the same outer tub as the conventional one is used, the rectification tower is raised and the number of rectification stages is increased. And the separation efficiency can be improved. Furthermore, since power is not required for pumping the liquefied gas, the power cost does not increase, and the power consumption of the air liquefaction separation device can be reduced by reducing the heat loss or improving the separation efficiency.

[Brief description of drawings]

1 to 3 show an embodiment of the present invention.
The figure is a system diagram of an air liquefaction separation device using a single rectification column, No. 2
FIG. 3 is an explanatory view showing a state where the same device is housed in an outer tank,
The figure is a system diagram of an air liquefaction separation device using a double rectification column, No. 4
FIGS. 6 to 6 show a conventional example, FIG. 4 is a system diagram of an air liquefaction separation apparatus using a single rectification column, and FIG. 5 is an explanatory view showing a state in which the apparatus is housed in an outer tank. , FIG. 6 is a system diagram of an air liquefaction separation apparatus using a double rectification column. 20,30 …… Air liquefaction separator, 21,31 …… Condenser, 22 ……
Single rectification tower, 23,33 …… Thermosiphon heat exchanger, 28 ……
Outer tank, 32 ... Double rectification tower, A ... Raw material air, GN ... Nitrogen gas, GO ... Oxygen gas, LN ... Liquefied nitrogen, LO ... Liquefied oxygen

Claims (3)

[Claims] 1. A raw material air which is compressed, purified and cooled and introduced into a lower part of a rectification column and a reflux liquid which is liquefied in a condenser and flows down from the upper part of the rectification column are brought into contact with each other to obtain oxygen and nitrogen. In an air liquefaction / separation device for rectifying and separating the rectification etc., the condenser is arranged laterally of the rectification column, and a liquefied gas liquefied by the condenser is introduced as a reflux liquid into the upper part of the rectification column. An air liquefaction separation device, characterized in that a thermosiphon heat exchanger for liquid is provided. 2. The warm fluid of the thermosiphon heat exchanger comprises:
The air liquefaction separation apparatus according to claim 1, wherein the air is raw material air. 3. The warm fluid of the thermosiphon heat exchanger comprises:
The air liquefaction separation apparatus according to claim 1, which is product nitrogen, low-purity nitrogen, or exhaust gas that has been heated after being discharged from the rectification tower.