JPS6364708B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing argon in an argon production process that is combined with or independent of an air separation process, and in particular, a process in which crude argon to be supplied to a purified argon column is recovered as a liquid from the crude argon column. , the rectification utility of the purified argon column is prepared within the argon production process, so that the argon production operation can be performed under conditions independent from the air separation process, increasing the stability of the operation, and This is designed to improve the operating economy of the air separation process.

The production of argon is generally carried out according to the flow shown in FIG. That is, FIG. 1 particularly shows the flow after the main rectification column, and shows a configuration in which the air separation step (a) is combined with the argon production step (b). Feed air cooled to near the liquefaction point by known means is introduced from path 1 to the bottom of the lower main rectifying column 3, and is then introduced into the bottom of the main rectifying column 2 (the top 4 of the main rectifying upper column 4).
a) contains high-purity nitrogen gas, and the middle part 4a and bottom part 4c of the upper column 4 of the main rectification column contain argon-containing (approximately 12%) gas and high-purity liquid oxygen, respectively. 2 bottom (bottom 3b of main rectification column lower column 3)
The oxygen-enriched liquid air is separated and stored in each of the two tanks.

The argon-containing gas accumulated in the middle part 4b of the upper column 4 of the main rectification column is supplied to the bottom of the crude argon column 6 through the route 5. The argon-containing gas is rectified in the crude argon column 6, and the bottom side of the condenser (hereinafter simply referred to as "top condenser") 10 installed at the top of the column is filled with argon-rich gas (hereinafter referred to as "crude condenser") containing a small amount of oxygen and nitrogen. ``argon gas'') is separated,
An oxygen-enriched liquid is also separated at the bottom of the column. This oxygen-enriched liquid fraction is returned to a suitable part of the main rectification column upper column 4 via route 7. On the other hand, the crude argon gas in the upper part of the crude argon column 6 is taken out from the route 8, passes through the argon heat exchanger 17, reaches room temperature, and further passes through the oxygen removal equipment 50, which will be described later, and then is sent to the purified argon column 9.
supply to. The top condenser 10 of the crude argon column 6 is supplied with oxygen-enriched liquid air accumulated at the bottom 3b of the lower column 3 of the main rectification column from a path 11 to the liquid air filter 1.
2 and supercooler 13, and is further expanded under reduced pressure by expansion valve 14 and supplied to the upper part of crude argon column 6 from route 15. The gas evaporated in top condenser 10 is sent from route 16 to main rectification column upper column 4. Supply near the middle of. On the other hand, from route 8 to argon heat exchanger 17
The crude argon gas that has passed through is mixed with an appropriate amount of high-purity hydrogen gas supplied from route 18, and then sent to catalyst column 19. In this catalyst tower 19,
Oxygen contained in the crude argon gas reacts with hydrogen and is converted to water. Next, this argon gas containing moisture and having a changed composition (hereinafter referred to as "modified argon gas") is sent to the dryer 20 and completely dehumidified, and then passed through the argon heat exchanger 17 again to be sufficiently cooled. The purified argon is supplied to the purified argon column 9. Nitrogen and hydrogen contained in the modified argon gas are then rectified and separated in the purified argon column 9, and the separated nitrogen and hydrogen are passed through the passage 2 at the top of the column.
It is extracted as waste gas from the argon heat exchanger 17, reaches room temperature, and is released into the atmosphere. Further, high-purity liquid argon is taken out from the bottom of the column via a path 22 as it is as a liquid or gaseous product argon.

On the other hand, the nitrogen-rich gas in the upper part 3a of the lower column 3 of the main rectification column is supplied from the path 31 to the bottom reboiler 23 of the purified argon column 9, which vaporizes a part of the high-purity liquid argon in the bottom and also vaporizes the nitrogen-rich gas itself. It is liquefied within the reboiler 23. This liquefied nitrogen-rich gas is expanded and depressurized to near atmospheric pressure via the path 24 by the expansion valve 25, and then
The nitrogen-rich gas fed to the top condenser 26 of the purified argon column 9 and evaporated in the condenser 26 is withdrawn as waste gas from the line 27 and is discharged after passing through the subcooler 13 or directly to the atmosphere. A portion of the nitrogen-rich liquid discharged from the middle of the lower column 3 of the main rectification column is also expanded and depressurized by the expansion valve 33 via the path 32, and then supplied to the top condenser 26 of the purification argon column 9. The condenser 26 is effectively cooled.

However, the above-mentioned flow, particularly in the argon production process B, has the following problems.

After the crude argon gas is recovered from the crude argon column 6, it is introduced into the oxygen removal equipment 50 and then into the purifying argon column 9. Therefore, if the operating conditions of the main rectification column 2 change, the crude argon gas is recovered from the crude argon column 6. The composition of the crude argon gas to be produced changes easily, and the operating conditions in the oxygen removal equipment 50 and the purified argon column 9 also change accordingly, making argon production extremely unstable.

Since the reboiler 23 and top condenser 26 of the purified argon column 9 use the nitrogen-rich gas and nitrogen-rich liquid from the main rectification column 2, respectively, if the amount of product argon collected changes, the nitrogen-rich gas and nitrogen-rich liquid from the main rectification column 2 change. The operating conditions will also change, and the main rectification column 2 must be designed and operated in such a way that it can produce excess nitrogen-rich gas and nitrogen-rich liquid necessary to collect the argon product. becomes uneconomical.

The present invention has been made in view of these circumstances, and its purpose is to improve the conventional argon production process combined with the air separation process, and in particular to supply purified argon to a purified argon column in the argon production process. While crude argon is recovered as a liquid from the crude argon column, the rectification utility of the purified argon column is prepared within the argon production process, so that argon production operation can be performed under conditions independent from the air separation process. The aim is to improve the stability of the air separation process as well as the operational economy of the air separation process itself.

However, the configuration of the present invention that has achieved these objectives is to recover crude argon in a liquid state from a crude argon column, and to supply the liquid crude argon once to the condenser at the top of the purified argon column for evaporation. After that, the evaporated crude argon gas is introduced into the oxygen removal equipment, while the crude argon gas from which oxygen has been removed by the equipment is supplied to the reboiler at the bottom of the purified argon column and liquefied, and then the liquefied crude argon gas is The key point is that argon is supplied to the middle and top condensers of the purified argon column.

The structure and effects of the present invention will be explained below based on the flow sheet of FIG. 2 showing an example. Particularly different from the conventional example, and the feature of the present invention lies in the configuration from the crude argon column 6 to the purified argon column 9. That is, the crude argon to be recovered from the crude argon column 6 was made into liquid crude argon in a liquid retainer 35 for reflux formation provided on the lower side of the top condenser 10, and the liquid crude argon was taken out through a path 36. Thereafter, it is once supplied to the top condenser 37 of the purified argon column 9 via the expansion valve 45 to be evaporated, and the evaporated crude argon gas is then introduced from the path 38 to the oxygen removal equipment 50 via the argon heat exchanger 17. do. The oxygen removal equipment 50
As in the past, oxygen is removed through a combustion reaction by adding high-purity hydrogen to produce modified argon gas. After the modified argon gas is sufficiently cooled in the argon heat exchanger 17, it is supplied to the reboiler 42 having a branch passage at the bottom of the purified argon column 9, where it is partially liquefied. The liquefied metamorphosed argon gas is route 3.
After being depressurized and expanded by the expansion valve 40 via 9,
A part of the liquefied and modified argon is supplied to the middle part of the purified argon column 9, and is joined to the path 36 via a path 39' branched from the middle of the path 39.
On the other hand, modified argon gas that is not liquefied is drawn out from the path 41 and merged into the path 38. As the reboiler 42 having branched flow paths as shown in the figure, for example, a plate-fin type heat exchanger is suitable.

In the above configuration, crude argon is procured by liquid crude argon that is always stored in the upper part of the crude argon column 6 or in the liquid crude argon storage tank 55 independent from the crude argon column 6, and the purified argon column 9
The liquid crude argon is used in the condenser 37, while the reboiler 42 is equipped with oxygen removal equipment 50.
Modified argon gas from That is, the rectification utilities (heating source and cooling source) in the purified argon column 9 are configured so that they can be prepared in a closed circuit within the argon production process. Therefore, even if there is a change in operating conditions within the argon production process, it will not affect the main rectification column 2, so the composition conditions of the liquid crude argon recovered from the crude argon column 6 will hardly change. High-purity argon is stably produced without any particular fluctuation in the operating conditions in the oxygen removal equipment 50 or the purified argon column 9. Furthermore, the process can be simplified.

Furthermore, even if the amount of product argon to be collected changes, if the branch path 39 is provided as described above, the liquefied modified argon gas can be appropriately returned to the take-out path 36 for liquid crude argon, which is the raw material, and the argon production process can be continued. Since it is designed to be able to be used in circulation, the ratio of heating amount and cooling amount can be arbitrarily changed to the desired conditions, and it goes without saying that the operation of the purifying argon column 9 can be maintained stably. In order to avoid disturbing the operating conditions of the main rectification column 2, or to produce excess rectification utilities (nitrogen-rich gas, nitrogen-rich liquid, etc.) necessary for product argon extraction, the main rectification column 2 is installed in excess. It is also very economical because there is no need to design or increase the amount of operation.

Furthermore, in the above configuration, in addition to the circulation of the liquefied modified argon gas from the branch path 39', it is also possible to circulate the modified argon gas from the path 41, so that high-purity gas added in excess in the oxygen removal equipment 50 can be recycled. Hydrogen gas can be recovered and the consumption of high-purity hydrogen can be reduced.

The present invention is constructed as described above, but the point is that the conventional argon production process combined with the air separation process is improved, and in particular, as a rectification utility of the purification argon column, it is possible to improve the conventional argon production process combined with the air separation process. Since liquid crude argon from the crude argon tower and modified argon gas from the oxygen removal equipment are circulated in a closed circuit within the argon production process, without supplying nitrogen-rich gas or nitrogen-rich liquid, It is possible to stabilize the operation of both the argon production process and the air separation process, and further improve the operating economy of the air separation process itself, simplify the manufacturing process,
It has become possible to improve the economic efficiency of oxygen removal equipment by reducing hydrogen consumption.

[Brief explanation of drawings]

FIG. 1 is a flow sheet showing a conventional argon production method, and FIG. 2 is a flow sheet illustrating the argon production method of the present invention. 2... Main rectification column, 3... Crude argon column, 9...
Refining argon column, 17...Argon heat exchanger, 2
3, 42... Reboiler, 26, 37... Top condenser, 50... Oxygen removal equipment, 55... Liquid crude argon storage tank, A... Air separation process, B...
Argon manufacturing process.

Claims (1)

[Claims] 1. The argon-rich gas obtained by liquefying and separating air is supplied to a crude argon column, and crude argon is recovered by rectification.Then, the oxygen content in the crude argon is removed using oxygen removal equipment, and further impurities are removed. In a method for producing high purity argon by rectifying and removing nitrogen and hydrogen present in a purified argon column in a purified argon column, the crude argon is recovered in a liquid state from the crude argon column, and the liquid crude argon is After being once supplied to the condenser at the top of the purified argon column and evaporated, the evaporated crude argon gas is introduced into the oxygen removal equipment, while the modified argon gas from which oxygen has been removed by the equipment is sent to the purified argon tower. A method for producing argon, which comprises supplying the liquefied modified argon to a bottom reboiler and liquefying it, and then supplying the liquefied modified argon to a middle part of the purified argon column and a condenser at the top of the column.