JPH0338632Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a nitrogen production apparatus using a liquefaction cryogenic separation method.

[Background of the idea]

A conventional nitrogen production apparatus using the liquefaction cryogenic separation method will be explained with reference to FIG.

The raw air from which moisture and carbon dioxide have been removed is introduced into the rectification column 2 through the air heat exchanger 1 and the conduit 12 from the conduit 11, and is purified into nitrogen gas and oxygen-rich waste liquid using the boiling point difference. It is distilled and separated. Nitrogen gas is collected from the upper part of the rectification column through a conduit 13 in a gaseous state, and a part of it is passed through a conduit 14, an air heat exchanger 1,
is sent out through conduit 15. However, since the separation method uses the difference in boiling points, hydrogen, which has a lower boiling point than nitrogen, is concentrated about three times as much as the atmospheric content and mixes into the nitrogen gas. The equipment was constructed only to reduce the contamination of hydrogen, and no consideration was given to the removal of hydrogen. Incidentally, related devices of this type include, for example, Utility Model Application No. 184354/1983.

[Purpose of invention]

The purpose of this nitrogen is to provide a nitrogen production device that extracts nitrogen gas with reduced hydrogen content.

[Summary of the idea]

In this invention, nitrogen gas extracted from the top of the rectification column is condensed and liquefied through a first nitrogen condenser and a second nitrogen condenser and returned to the top of the rectification column, and hydrogen is extracted from the top of the column and subjected to rectification. The liquid nitrogen extracted from the upper part of the tower is introduced into the gas-liquid separator through the expansion valve, and the gas nitrogen vaporized in the gas-liquid separator is taken out as waste gas, and the liquid nitrogen in the gas-liquid separator is condensed into the first nitrogen condenser. The waste liquid taken out from the bottom of the rectification column is passed through an expansion valve and vaporized through a second nitrogen condenser to be discharged as waste gas.

[Example of idea]

An embodiment of the present invention will be described below with reference to FIG. In FIG. 1, raw air from which moisture and carbon dioxide have been removed is passed through a conduit 11 to an air heat exchanger 1,
The liquid is introduced into the rectifying column 2 through a conduit 12, and is separated by rectification into nitrogen gas and an oxygen-rich waste liquid using the difference in boiling points. Nitrogen gas is passed from the top of the rectification column 2 to conduit 13
The first nitrogen condenser 3, the conduit 1
4. The entire amount is condensed and liquefied through the second nitrogen condenser 4 and returned to the upper part of the rectification column 2 through the conduit 15. A portion of this liquid nitrogen is extracted from the conduit 16, reduced in pressure by the expansion valve 32, and then introduced into the gas-liquid separator 5. From the gas-liquid separator 5, the liquid nitrogen is passed through the conduit 18 to the first nitrogen condenser 3.
The liquid nitrogen introduced into the column is cooled by exchanging heat with the nitrogen gas extracted from the upper part of the rectification column 2 through the conduit 13, and is completely gasified and passed through the conduit 19 and the air heat exchanger 1. Then, the nitrogen gas is extracted from the conduit 20 as nitrogen gas. In this case, the hydrogen contained in the nitrogen gas at the top of the rectification column 2 has a low boiling point of about 253°C, so
It gradually accumulates at the top of the rectification column 2 and is withdrawn through a conduit 28 in a fixed amount. On the other hand, the hydrogen-containing gaseous nitrogen taken out from the gas-liquid separator 5 through the conduit 26 is depressurized by the expansion valve 33 and then transferred to the conduits 27 and 2.
4. It passes through the air heat exchanger 1 and is discharged as waste gas through the conduit 25. Further, the waste liquid taken out from the bottom of the rectification column 2 through the conduit 21 is depressurized by the expansion valve 31 and then introduced into the second nitrogen condenser 4 through the conduit 22.
It condenses and liquefies it by heat exchange with the nitrogen gas coming from the conduit 14, and gasifies it to join the waste gas line of the conduit 24 through the conduit 23. In addition, in this example,
Although the first nitrogen condenser 3 and the second nitrogen condenser 4 have been described, the present invention is not limited thereto. That is, these may be combined into one nitrogen condenser.

According to the embodiment described above, nitrogen can be collected in liquid form from the upper part of the rectification column, and the liquid nitrogen can be gasified and collected, reducing the hydrogen content to about 1/45 compared to conventional nitrogen production equipment. It is possible to collect nitrogen gas reduced to

[Effect of idea]

According to the present invention, hydrogen is extracted from the top of the rectification column, and after removing hydrogen contained in the liquid nitrogen extracted from the top of the rectification column, the nitrogen sampled in liquid form is gasified and extracted as nitrogen gas. Accordingly, a nitrogen production device capable of extracting nitrogen gas with reduced hydrogen content can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing an embodiment of a nitrogen production device according to the present invention, and FIG. 2 is a system diagram showing an example of a conventional nitrogen production device. 1... Air heat exchanger, 2... Rectification column, 3... First nitrogen condenser, 4... Second nitrogen condenser, 5... Gas-liquid separator, 11-28... Conduit, 31- 33...
expansion valve.

Claims (1)

[Claim for Utility Model Registration] An air heat exchanger that cools raw air by exchanging heat with low-temperature return gas, and a rectification column that extracts nitrogen from the raw air cooled by the air heat exchanger by cryogenic separation. In the nitrogen production apparatus, a pipe line is provided for extracting hydrogen from the top of the rectification column, and the nitrogen gas extracted from the top of the rectification column is heat-exchanged through a first nitrogen condenser and a second nitrogen condenser to form liquid nitrogen. A pipe line is provided to return a part of the liquid nitrogen returned to the upper part of the rectification column to the upper part of the rectification column, and a pipe line for extracting a part of the liquid nitrogen returned to the upper part of the rectification column from the upper part of the rectification column and introducing it into the gas-liquid separator via an expansion valve. , a pipe line for taking out gaseous nitrogen vaporized by the gas-liquid separator as waste gas, and a pipe line for vaporizing liquid nitrogen separated by the gas-liquid separator through the first nitrogen condenser and taking it out as nitrogen gas. and a pipe line for passing the waste liquid taken out from the bottom of the rectification column through the second nitrogen condenser via an expansion valve to vaporize it and release it as waste gas.