JPH0781779B2 - Cryogenic separator for carbon monoxide - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for cryogenic separation of carbon monoxide from a mixed gas containing at least carbon monoxide and hydrocarbons.

[0002]

2. Description of the Related Art In general, gases obtained by reforming hydrocarbons such as propane and butane are carbon monoxide and hydrogen,
Hydrocarbons such as methane are contained at a ratio of several percent or less,
When the product carbon monoxide gas is to be obtained from such a mixed gas, not only the separation of hydrogen but also the separation of the above hydrocarbons is necessary.

Conventionally, such a separation of hydrocarbons, cryogenic separation method according rectification column is often used (for example, Nippon Sanso Technical Report No.1 (1982) "in the C ₁ chemistry cryogenic Separation "
reference). In such a cryogenic separation method, carbon monoxide gas, which is a product gas, is generally taken out from the top of the rectification column. Therefore, in order to increase the purity of the product gas, the reflux gas supplied to the top of the column is used. It is extremely effective to increase the purity of the liquid.

As an apparatus for increasing the purity of such a reflux liquid, there is known one as shown in FIGS. 8 and 9. In the apparatus shown in FIG. 8, the rectification column 90 is composed of a lower column 91 and an upper column 92.
And a condenser 93 of the lower tower 91 which also functions as a reboiler of the upper tower 92 is provided between the both towers 91 and 92, and the raw material gas is first purified in the lower tower 91. It is extracted from the top of the lower tower 91 and supplied to the top of the upper tower 92 as a reflux liquid. In addition, FIG.
In the apparatus shown in (1), part of the product gas extracted from the top of the rectification column 90 is passed through a condenser 94, and this is reduced to the top of the column as a reflux liquid.

[0005]

In the device shown in FIG. 8,
Since the double-column rectification column in which the lower column 91 and the upper column 92 are connected must be used, the structure of the rectification column becomes complicated and expensive. In addition, since the tower length is large, the size of the entire cool box for accommodating the tower is also increased, which hinders downsizing of the device.

On the other hand, in the apparatus shown in FIG. 9, since a part of the product gas once purified is returned to the rectification column 90 as a reflux liquid, the processing amount of the rectification column 90 is increased by the returned amount. Becomes inefficient.

In view of such circumstances, the present invention efficiently purifies the high-purity reflux liquid supplied to the top of the rectification column, thereby obtaining a high-purity product carbon monoxide gas. An object is to provide a cryogenic separation device for carbon oxide.

[0008]

The present invention comprises a rectification column for separating carbon monoxide from a mixed gas containing at least carbon monoxide and hydrocarbons, and a reboiler for evaporating the bottom liquid of the rectification column. In the equipped cryogenic separator of carbon monoxide,
A plurality of vertically extending partition plates are installed side by side in the reboiler, and a plurality of column bottom liquid evaporation passages and a plurality of mixed gas passages are alternately formed between these partition plates, and a fluid flowing vertically in both passages. The reboiler is configured so that heat exchange is performed between the two, and a raw material gas introduction passage for introducing a raw material gas into the mixed gas passage from its lower portion and a rectification in the mixed gas passage from the upper portion of the mixed gas passage. A reflux liquid supply passage is provided for introducing the rectified gas thus generated and liquefying it into the top of the rectification column as a reflux liquid.

[0009]

According to the above construction, the raw material gas is passed through the mixed gas passage of the reboiler from its lower portion, and the raw material gas is vaporized by heat exchange between the raw material gas and the bottom liquid flowing in the bottom liquid vaporization passage. At the same time, a part of the raw material gas is condensed and descends, and the descending condensate and the rising raw material gas come into contact with each other to rectify the raw material gas. Therefore, a purified gas having a high carbon monoxide purity is taken out from the upper part of the reboiler, and the gas is liquefied and supplied as a reflux liquid to the upper part of the rectification column, whereby a product carbon monoxide gas having a high purity is obtained. Refined.

More specifically, the column bottom liquid evaporation passage and the mixed gas passage are formed between a plurality of vertically extending partition plates, and the column bottom liquid and the raw material gas are passed through the partition plates. Good rectification is promoted by efficient heat exchange, and a rectified gas having a relatively high purity is generated in the upper part of the mixed gas passage. Therefore, by liquefying this rectified gas and using it as the above-mentioned reflux liquid, high-purity carbon monoxide gas is purified in the rectification column.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the overall structure of a deep-chill separation system equipped with the device of the present invention. This system uses a reformed gas such as propane or butane as a raw material and separates carbon monoxide gas from this gas. The method and apparatus of the present invention contain at least carbon monoxide and hydrocarbons. It is widely applicable when separating carbon monoxide from a mixed gas.

The system shown in FIG. 1 includes a refrigerator 10, a gas-liquid separator 11, an MS (molecular sieve) adsorption device 12,
And a cool box 14, and inside the cool box 14, a main heat exchanger 16, a rectification column 18, a reboiler 20, condensers 22 and 2 are provided.
8, a first gas-liquid separator 24, a second gas-liquid separator 25, a third gas-liquid separator 26, a heat exchanger 27, a nitrogen gas-liquid separator 30 and the like.

The MS adsorption device 12 comprises a main heat exchanger 16
It is connected to the bottom of the reboiler 20 via a source gas introduction pipe 32 passing through. The bottom of the reboiler 20 is connected to the middle abdomen of the first gas-liquid separator 24 via a transfer pipe 34, and in the middle of the transfer pipe 34, the heat exchanger 27,
A condenser 28 and an expansion valve 36 are provided. The bottom part of the first gas-liquid separator 24 is connected to the middle part of the rectification column 18 via a condenser 22.

The top of the reboiler 20 is connected to the middle part of the second gas-liquid separator 25 via the purified gas transfer pipes 38 and 40, and the condenser 22 is provided in the middle of the purified gas transfer pipes 38 and 40. , 28 are connected. The bottom portion of the second gas-liquid separator 25 has the purified liquid transfer pipe 42.
Is connected to the middle abdomen of the third gas-liquid separator 26, and the bottom of the third gas-liquid separator 26 is connected to the top of the rectification column 18 via the purified liquid transfer pipe 46. An expansion valve 44 is provided in the middle of the liquid transfer pipe 42. Further, the reboiler 20 includes the bottom liquid outlet pipe 48 and the gas reflux pipe 4
It is connected via 9 to the bottom of the rectification column 18.

Next, the structure of the reboiler 20 will be described with reference to FIGS.

As shown in FIG. 2, the reboiler 20 has a heat exchange section 50. A tower bottom liquid inlet port 51 is attached to the lower side surface of the heat exchange section 50, and a reflux gas outlet port 52 is similarly provided to the upper side surface of the heat exchange section 50.
A raw material gas inlet port 53 is mounted on the lower end surface, and a purified gas outlet port 54 is mounted on the upper end surface. Then, the tower bottom liquid outlet port 48 is connected to the tower bottom liquid inlet port 51.
Similarly, the gas reflux pipe 49 is connected to the reflux gas outlet port 52, and the purified gas transfer pipe 38 is connected to the purified gas outlet port 54. Further, a gas-liquid separation pipe 56 having a bottom is connected to the raw material gas inlet port 53, the transfer pipe 34 is connected to the bottom of the gas-liquid separation pipe 56, and the above-mentioned transfer pipe 34 is provided at a position above the transfer pipe 34. A source gas introduction pipe 32 is connected.

As shown in FIGS. 3 to 7, the heat exchanging section 5 is used.
No. 0 is equipped with a large number of partition plates 58 made of aluminum or the like, which are arranged in parallel to each other. Between these partition plates 58, a column bottom liquid evaporation passage 59a and a raw material gas passage (mixed gas passage) are provided. And 59b are formed alternately.

As shown in FIG. 4, the bottom liquid evaporation passage 59a.
A pair of L-shaped side bars 60 around the step forming the
a is provided. As shown in FIG. 6, these side bars 60a are arranged between both partition plates 58 so as to be in close contact with them. These sidebars 60a
The upper and lower ends of the tower bottom liquid evaporation passage 59a and part of the side ends thereof are blocked, and an opening 62a is formed in the lower part of one side end.
Is formed, and an opening 63a is formed in the upper part of the other side end. Then, the tower bottom liquid inlet port 51 is attached to a position that closes the opening 62a, and the reflux gas outlet port 52 is attached to a position that closes the opening 63a.

A corrugated fin 64a extending in the vertical direction is provided in the middle part of the raw material gas passage. A fin 65 extending obliquely upward from the opening 62a to the fin 64a is provided below the fin 64a, and a fin 66 extending obliquely upward from the fin 64a to the opening 63a is provided above the fin 64a. There is. These fins 64a, 65, 66 are made of aluminum or the like, and are joined to the surface of the partition plate 58 by welding or the like as shown in FIG.

On the other hand, as shown in FIG. 5, a side bar 60b is provided at the side end of the step forming the source gas passage 59b to close the side end over the entire area in the vertical direction. These side bars 60b are also the side bars 60 described above.
Similar to a, it is arranged between both partition plates 58 so as to be in close contact with them. As a result, openings 62b and 63b are formed at the lower end and the upper end of this step, respectively, and the source gas inlet port 5 is provided at a position where the opening 62b is closed.
3 is mounted, and the purified gas outlet port 54 is mounted at a position that closes the opening 63b. Also, both sidebars 6
A corrugated plate-shaped fin 64b extending in the up-down direction is provided between 0b, and the fin 64b is also joined to the surfaces of the joining plates 58 by welding or the like.

Therefore, the heat exchange section 50 shown here includes the partition plate 58, the fins 64a, 65, 66, the partition plate 58,
The fins 64b, the partition plates 58, ... Are laminated in this order.

Next, the deep-chill separation method of carbon monoxide carried out in this apparatus will be explained.

First, the raw material gas (mixed gas) is the refrigerator 10.
The water that has been cooled by the above method and condensed here is separated by the gas-liquid separator 11. The remaining gas is sent to the MS adsorption device 12, where moisture and carbon dioxide are removed, and then introduced into the cold insulation box 14 through the raw material gas introduction pipe 32.

This gas exchanges heat with the return gas in the main heat exchanger 16, is cooled, and then is introduced into the raw material gas inlet port 53 of the reboiler 20 through the gas-liquid separation pipe 56 shown in FIG. Since only the opening 62b shown in FIGS. 3 (b) and 5 faces the raw material gas inlet port 53, the gas is fed from the opening 62b into the raw material gas evaporation passage 59b in the heat exchange section 50, that is, both of them. It flows upward into the passage surrounded by the side bar 60b (arrow B).

On the other hand, the bottom liquid of the rectification column 18 is introduced into the bottom liquid inlet port 51 of the reboiler 20 through the bottom liquid introducing pipe 48. Since only the opening 62a shown in FIGS. 3B and 4 faces the tower bottom liquid inlet port 51, the tower bottom liquid passes through the opening 62a and the heat exchange section 5
0 bottom liquid evaporation passage 59a, that is, both side bars 6
It flows into the passage surrounded by 0a (arrow A).

With the introduction of these, as shown in FIG.
Column bottom liquid evaporation passage 59a and raw material gas passage 5 adjacent to each other
The vaporized gas (arrow A) and the raw material gas (arrow B) of the column bottom liquid respectively flow in 9b, and heat exchange is performed between them.
By this heat exchange, the bottom liquid in the bottom liquid evaporation passage 59a is heated and evaporated, and the evaporated gas is returned to the bottom of the rectification column 18 through the reflux gas outlet port 52 and the reflux gas passage 49 (arrow AG). ). At the same time, the raw material gas in the raw material gas passage 59b cooled by the heat exchange is partially condensed and descends, and the descending condensate and the rising raw material gas are contacted to rectify the raw material gas. Purified gas having a high carbon monoxide concentration is generated at the top of the raw material gas passage 59b.

Here, the condensate collects from the raw material gas inlet port 53 to the bottom of the gas-liquid separation pipe 56, passes from the bottom to the heat exchanger 27 along the transfer pipe 34 (arrow BL),
It is introduced into the capacitor 28. Liquid nitrogen, which is a cold source, is supplied to the condenser 28 from a nitrogen gas-liquid separator 30, and the raw material gas is cooled by heat exchange with this and the first vapor-liquid separation through the expansion valve 36. Sent to the container 24. The liquid at the bottom of the first gas-liquid separator 24 is
It is introduced into an appropriate portion of the rectification column 18 through a condenser 22.

On the other hand, the purified gas that has risen to the top of the reboiler 20 enters the purified liquid transfer pipe 38 from the purified gas outlet port 54, is cooled by the condensers 22 and 28, and
It is introduced into the second gas-liquid separator 25. Then, from the bottom of the second gas-liquid separator 25 to the purified liquid transfer pipe 42 and the expansion valve 4
4 to the third gas-liquid separator 26, and is supplied as a reflux liquid from the bottom of the second gas-liquid separator 26 to the top of the rectification column 18 through the purified liquid transfer pipe 46.

As described above, the high-purity gas purified from the raw material gas in the reboiler 20 is introduced into the top of the rectification column 18 as a reflux liquid, so that the rectification column 18 has an extremely high-purity carbon monoxide. The gas is refined, and this gas is taken out to the outside of the cool box 14 as product carbon monoxide gas through the product gas outlet passage 47.

As described above, in this device, the cool box 14
The raw material gas introduced into the inside of the reboiler 20 is first introduced into the bottom portion of the reboiler 20, and heat exchange between the raw material gas and the bottom liquid of the reboiler 20 is performed to rectify the raw material gas in the raw material gas passage 59b. Since the high-purity purified gas thus obtained is liquefied and supplied as a reflux liquid to the top of the rectification column 18, a double rectification column may be used as in the conventional case.
By using the existing reboiler 20 also as gas rectification means without refluxing part of the product gas,
A high-purity reflux liquid can be efficiently generated, whereby a high-purity product CO gas can be obtained at low cost.

In particular, in this embodiment, a large number of partition plates 58 extending vertically in the reboiler 20 are arranged in parallel with each other, and the mixed gas passage (source gas passage) 59b and the tower bottom are provided between the partition plates 58. The liquid evaporation passages 59a are alternately formed, and the mixed gas and the bottom liquid are caused to flow through the passages 59b and 59a, respectively, so that heat can be efficiently exchanged between the two. Since it has a distillation function, a rectified gas of relatively high purity can be derived from the upper part of the mixed gas passage 59b of the reboiler 20. Therefore, by liquefying this rectified gas and using it as a reflux liquid, purification of particularly high-purity monocarbohydrate can be expected.

[0032]

As described above, according to the present invention, the mixed gas is first introduced into the bottom of the reboiler of the rectification column, and heat is exchanged between the mixed gas and the bottom liquid in the reboiler, whereby the mixed gas passage The mixed gas is rectified by the above, and the high-purity purified gas thus obtained is supplied to the top of the rectification column as a reflux liquid, and moreover, a plurality of partition plates are arranged in parallel in the reboiler. By installing the column bottom liquid evaporation passage and the mixed gas passage alternately between these partition plates,
Since the reboiler has an excellent rectification function,
By using the reboiler originally required for the equipment as a gas rectification means without using a double rectification column or refluxing part of the product gas as in the past, a highly purified reflux liquid can be efficiently used. It can be generated well, which has the effect of obtaining high-purity product CO gas at low cost.

[Brief description of drawings]

FIG. 1 is a flow sheet showing the overall configuration of a carbon monoxide cryogenic separation system according to an embodiment of the present invention.

FIG. 2 is an external front view of a reboiler in the cryogenic separation system.

FIG. 3A is a perspective view showing a state in which the reboiler is laid down, and FIG. 3B is a perspective view showing a state in which each port is removed from the reboiler.

FIG. 4 is a sectional view taken along the line CC of FIG.

5 is a cross-sectional view taken along line DD of FIG. 3 (b).

FIG. 6 is a sectional view taken along line EE of FIG.

FIG. 7 is a sectional view taken along line FF of FIG.

FIG. 8 is a flow sheet showing an example of a conventional carbon monoxide cryogenic separation device.

FIG. 9 is a flow sheet showing an example of a conventional carbon monoxide cryogenic separation device.

[Explanation of symbols]

 18 Fractionation tower 20 Reboiler 25,26 Gas-liquid separator 32 Raw material gas introduction pipe 38,40 Purified gas transfer pipe (reflux liquid supply passage) 42,46 Purified liquid transfer pipe (reflux liquid supply passage) 58 Partition plate 59a Tower bottom Liquid evaporation passage 59b Raw material gas passage (mixed gas passage)

Claims (1)

[Claims] 1. A rectification column for separating carbon monoxide from a mixed gas containing at least carbon monoxide and a hydrocarbon , and this rectification column.
Carbon monoxide with reboiler for evaporating bottom liquid of distillation column
In the cryogenic separation device of the element, extend vertically to the reboiler.
A plurality of partition plates are installed side by side, and between these partition plates
Alternating multiple bottom liquid evaporation passages and multiple mixed gas passages
Formed and heat exchange between the fluids flowing vertically in both passages.
In addition to configuring the reboiler so that
A raw material gas is introduced into the mixed gas passage from its lower part.
From the upper part of the gas introduction passage and the mixed gas passage.
The rectified gas rectified in the gas passage is discharged and liquefied.
Reflux liquid, which is introduced as a reflux liquid into the top of the rectification column in the above state.
A cryogenic separation device for carbon monoxide, comprising a supply passage .