JPH07198250A - Oxygen and nitrogen gas manufacturing device - Google Patents

Abstract

PURPOSE:To provide a superior oxygen gas and nitrogen gas manufacturing device in which oxygen gas and nitrogen gas being pressurized can be manufactured at low cost and efficiently and a sufficient accommodation for unexpected increasing in demand can be obtained. CONSTITUTION:Liquid oxygen 71 accumulated at an upper tower 59 of a refining tower 58 is taken out, the oxygen is pressurized under its liquid state, thereafter the oxygen is inputted into a heat exchanger 57, then fed into the first expansion turbine 75 to perform a thermal insulating expansion operation and cold heat is generated by it. In addition, a part of liquid nitrogen is taken out of a second return flow pipe 64, the liquid nitrogen is pressurized under its liquid state, thereafter the liquid nitrogen is inputted into the heat exchanger 57, then fed into the second expansion turbine 93 to perform a thermal insulating expansion and cold heat is generated. Both generated cold heats are transmitted to the heat exchangers 56, 57 to cause these heat exchangers to act as a cold heat source for the device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oxygen / nitrogen gas production apparatus capable of obtaining oxygen gas and nitrogen gas under pressure.

[0002]

2. Description of the Related Art Conventionally, oxygen gas and nitrogen gas are
It is manufactured by using an air separation device and separating them using the difference in boiling points of nitrogen and oxygen. As shown in FIG. 3, a typical air separation device of this type sucks raw material air from a raw material air suction pipe 1, compresses the raw material air with an air compressor 2, and passes the first air through a pipe 3 into a first and a second air. It is cooled via the heat exchangers 4 and 5, and further via the pipe 7 to the rectification tower 8
It is adapted to be introduced into the lower tower 8'of the above in a state of being cooled to near the liquefaction point. In this lower tower 8 ',
Fractionation of air takes place, liquid air enriched with oxygen collects at the bottom of the lower column 8 ', nitrogen moves upwards in the gaseous state and is discharged by pipe 10 from the top of the lower column 8'. The derived nitrogen gas is heat-exchanged in the second and first heat exchangers 5 and 4 to become product nitrogen gas near room temperature, and is discharged from the pipe 33. A part of the nitrogen gas discharged from the top of the lower tower 8 ′ is introduced into the condenser 16 of the upper tower 8 ″ through the pipe 17, and is liquefied here to become liquid nitrogen, and then from the pipe 18 to the lower tower. It flows down into 8'and becomes the reflux liquid. Oxygen-rich liquid air is introduced into the upper tower 8 "from the bottom of the lower tower 8'through a pipe 12 equipped with an expansion valve 12 '. In the upper tower 8 ″, rectification of liquid air is performed, liquid oxygen 9 is accumulated in the bottom, and nitrogen-rich exhaust gas is discharged from the top of the tower by a pipe 21. This discharged exhaust gas is used for the second heat exchange. Via the pipe 5, via the pipe 24 and the valve 25, into the expansion turbine 26, where it undergoes adiabatic expansion to generate the refrigeration necessary for the device, and then via pipe 29 the second and first heat exchangers 5, 5. 4, where cold is added to the feed air, which itself is released into the atmosphere through pipe 31. Valve 32 provided in pipe 29
Due to the liquid level in the upper tower 8 ″, the passage 2 of the expansion turbine 26
The amount of exhaust gas supplied to 1 is controlled. Liquid oxygen is led out from the bottom of the upper tower 8 ″ by a pipe 10 ′, vaporized through the second and first heat exchangers 5 and 4 to become oxygen gas, and then pressurized by the pressure pump P, It becomes the product oxygen gas under pressure and is used for demand.

[0003]

In the air separation apparatus of this type, when it is necessary to obtain the product gas under pressure,
The gas taken out as a product must be pressurized in a gaseous state by a pressure pump. However, in order to pressurize the above-mentioned gas in a gas state, considerable energy is required and there is a drawback that the cost becomes high. In addition, in the above device, the cold balance during operation is usually controlled to be appropriately maintained, and therefore, even if the raw material air supply amount per unit time is increased in order to meet an unscheduled increase in demand, expansion is performed. Since there is a time delay in increasing the amount of cold generated by the turbine, there is also a problem that the purity of the product oxygen gas decreases.

The present invention has been made in view of the above circumstances, and it is possible to efficiently produce pressurized oxygen gas and nitrogen gas at low cost, and also to sufficiently meet an unplanned increase in demand. Excellent oxygen that can respond
The purpose is to provide a nitrogen gas production apparatus.

[0005]

In order to achieve the above object, an oxygen / nitrogen gas production apparatus of the present invention comprises an air compression means for compressing raw material air, and a heat exchange means for cooling the compressed air to an ultralow temperature. , A lower rectification column for introducing compressed air cooled to the ultra-low temperature and liquefying oxygen by liquefaction separation to hold nitrogen in a gaseous state, and liquid air taken out from the bottom of the lower rectification column in the column An upper rectification column that introduces and liquefies oxygen by liquefaction separation and stores it in the bottom, a liquid oxygen take-out path that takes out liquid oxygen from the bottom side of the upper rectification tower, and a heat exchange means that extends from the tip of the liquid oxygen take-out path A product oxygen gas take-out path that vaporizes the liquid oxygen via the gas and takes it out as a product, and a part of the gaseous nitrogen in the lower rectification column provided in the upper rectification column is introduced and condensed to liquefy Means and this condensation means From the tip of the liquid nitrogen take-out path, the liquid nitrogen reflux path for returning the liquid nitrogen taken out from the liquid to the lower rectification column, the liquid nitrogen take-out path for taking out a part of the liquid nitrogen via the liquid nitrogen return path, And a nitrogen gas take-out passage for taking out the liquid nitrogen as product nitrogen gas by vaporizing the liquid nitrogen via the heat exchange means, and the liquid oxygen take-out passage is provided with a first pressurizing means for pressurizing liquid oxygen. In addition, the flow path on the downstream side of the pressurizing means is formed to have a structure in which cold is applied through the heat exchanging means and then through the first expander for generating cold heat and again through the heat exchanging means. In addition, a second pressurizing means for pressurizing liquid nitrogen is provided in the liquid nitrogen take-out path, and a flow path downstream of the pressurizing means passes through the heat exchanger and then the second pressurizing means. Re-expansion via the expander for cold heat generation A configuration that is formed in the structure to impart cold through the heat exchange means.

[0006]

In other words, the apparatus of the present invention has a rectification tower which is placed at the upper and lower sides.
Divided into columns, liquid oxygen produced in the upper rectification column (hereinafter referred to as "upper column") is taken out, pressurized in a liquid state, then sent to a heat exchanger, and then introduced into an expander for cold heat generation. Adiabatic expansion is performed to generate cold, and the cold generated is sent to a heat exchanger to serve as a cold source for the device. Thus, pressurizing oxygen in a liquid state can significantly reduce the pressurization cost as compared with the case of pressurizing in a gas state (for example, 1 mol of oxygen is 2 mol if it is gas).
Liquid is only 16 grams of oxygen, compared to 2.4 liters). Moreover, in the present invention, as described above, oxygen is pressurized in a liquid state and then vaporized by a heat exchanger, and this pressure is used to drive an expander for cold heat generation such as an expansion turbine to obtain cold, The energy used for pressurizing oxygen can be used for cold generation,
As a result, the product cost can be reduced. This is the greatest feature of this invention. Besides,
In the present invention, a part of the reflux liquid nitrogen introduced into the lower rectification column (hereinafter abbreviated as "lower column") is taken out in order to obtain product nitrogen gas, which is also pressurized in a liquid state,
Then, it is vaporized by a heat exchanger, introduced into an expander for generating cold heat and adiabatically expanded to generate cold, and the cold generated is sent to the heat exchanger again and used as a cold source of the apparatus. Therefore, since the pressurizing energy of the product nitrogen gas can be applied to the driving energy of the expander for generating cold heat, the cost of the product nitrogen gas can be significantly reduced.

Next, the present invention will be described in detail based on embodiments.

FIG. 1 shows an embodiment of the present invention.
In the figure, 51 is an air compressor for compressing raw material air, 5
2 is a drain separator, 53 is a Freon cooler, and 54 is a set of two adsorption towers. The adsorption tower 54 is filled with a molecular sieve, and adsorbs and removes impurities such as H ₂ O, CO ₂ and CO in the air compressed by the air compressor 51. Reference numeral 55 is a compressed air supply pipe that sends compressed air from which impurities have been adsorbed and removed. Reference numeral 56 is a first heat exchanger to which compressed air from which impurities have been adsorbed and removed by the adsorption tower 54 is sent. 57 is a 2nd heat exchanger, and the compressed air which passed the 1st heat exchanger 56 is sent in. Reference numeral 58 is a rectification column including an upper column 59 and a lower column 60.

The lower tower 60 is cooled to an ultra-low temperature by the first and second heat exchangers 56 and 57, further cools the compressed air sent through the pipe 55, liquefies a part of the compressed air, and the liquid air 61. As a result, nitrogen is stored in the bottom part, and nitrogen is stored in the upper part in a gas state. A condenser 62 is built in at the bottom side of the upper tower 59, and a part of the nitrogen gas accumulated in the upper part of the lower tower 60 is fed in through the first reflux pipe 63. The pressure inside the upper tower 59 is lower than that in the lower tower 60, and the stored liquid air (N ₂ 50 to 70%, O ₂ 30 to 50%) 61 at the bottom of the lower tower 61 has a pipe with the expansion valve 65. It is sent in at 66 and vaporized to cool the internal temperature of the upper tower 59 to a temperature below the boiling point of liquid nitrogen. By this cooling, the nitrogen gas sent into the condenser 62 is liquefied. This liquid nitrogen is introduced as a reflux liquid into the upper part of the lower tower 60 through the second reflux pipe 64, and this flows down through the liquid nitrogen reservoir 67 in the lower tower 60, and from the bottom of the lower tower 60. It is designed to come into contact with rising compressed air in a countercurrent manner and to cool and partly liquefy it. In this process, the high boiling point oxygen gas in the compressed air is liquefied and stored in the bottom portion of the lower tower 60, and the low boiling point nitrogen gas is stored in the upper portion of the lower tower 60. 64a is a gas-liquid separator. 90 is the second
A part of the liquid nitrogen that is refluxed is taken out by the liquid nitrogen extraction pipe that branches from the reflux pipe 64.

On the other hand, the liquid air accumulated at the bottom of the lower tower 60 is sent to the upper part of the upper tower 59 through the pipe 66, and undergoes a rectification action in the upper tower 59, Oxygen of the high boiling point component in the liquid air is liquefied by this and is accumulated as liquid oxygen 71 at the bottom of the upper tower 59. Reference numeral 80 is a pipe for supplying liquid oxygen into the upper tower 59 when the oxygen gas production apparatus is started up and when the liquid oxygen in the upper tower 59 is low. The pipe 80 extends from a liquid oxygen storage tank (not shown). This tank stores liquid oxygen produced by the device or liquid oxygen produced by another device and transported by a tank truck or the like. Reference numeral 81 denotes a liquid oxygen supply control valve which is opened to supply cold liquid oxygen when the cold balance during operation tends to be insufficient due to the liquid level of the liquid level gauge 82 to constantly maintain the liquid level of liquid oxygen. It is controlled to be constant and balances rectification. The low boiling point component gas including nitrogen gas is discharged as exhaust gas from the top of the upper tower 59 by a pipe 70, and the second and first heat exchangers 57 and 56 are discharged.
It is designed to be released into the atmosphere via. Further, the liquid oxygen 71 accumulated at the bottom of the upper tower 59 is led out by the liquid oxygen lead-out pipe 72, pressurized by the first pressurizing pump 73, and in the second heat exchanger 57 in a pressurized state. And is vaporized into product oxygen gas, which is taken out from the product oxygen gas extraction pipe 74.

It should be noted that this oxygen gas extraction pipe 7
No. 4 is provided with a first expansion turbine 75, which produces cold by using the pressurizing pressure of the product oxygen gas as a driving source. That is, the product oxygen gas is 35 kg / c until it enters the first expansion turbine.
The pressure of about m ² was changed to 10 kg / cm inside.
By expanding to ² and performing a thermodynamic external work, the temperature becomes extremely low and cold is generated, and in that state, it enters the second heat exchanger 57 again and further enters the first heat exchanger 56 and enters the raw material. The generated cold is applied to the raw material air by exchanging heat with the air, and the raw material air itself becomes normal temperature and is taken out as a product from the tip of the product oxygen gas extraction pipe 74. Since the first expansion turbine 75 uses the pressurized product oxygen gas as a driving source, it is difficult to react with oxygen, for example, a material such as (copper alloy, for example brass, nickel alloy (Ni-Cr-Fe)). , Stainless steel (SUS316
L) and an aluminum alloy (Al-Zn)), the occurrence of a disaster such as an explosion is prevented.

On the other hand, a part of the refluxed liquid nitrogen taken out from the liquid nitrogen take-out pipe 90 is part of the second pressurizing pump 9.
It is pressurized by 1 and is introduced into the second heat exchanger 57 in a pressurized state to be vaporized into nitrogen gas, which is then introduced into the product nitrogen gas extraction pipe 92. The product nitrogen gas extraction pipe 92 is provided with a second expansion turbine 93, which uses the pressurization pressure of nitrogen gas as a drive source and produces cold as in the expansion turbine 75. Then, the nitrogen gas again enters the second heat exchanger 57, and further enters the first heat exchanger 56 to exchange heat with the raw material air to impart the generated cold to the raw material air,
The temperature of itself becomes room temperature, and the product nitrogen gas extraction pipe 92 is adapted to be taken out from the tip thereof.

A fin type heat exchanger 100 is provided at the tip end side of the product oxygen gas take-out pipe 74 and the tip end side of the product nitrogen gas take-out pipe 92, respectively. This is to prevent the liquid oxygen or liquid nitrogen at ultra-low temperature from being taken out as it is if the cold balance in the heat exchangers 56 and 57 is lost.

Using this apparatus, product oxygen gas and product oxygen gas can be produced, for example, as follows. That is, first, the raw material air is compressed by the air compressor 51, and the raw material air is drained by the drain separator 52, the Freon cooler 53, the adsorption tower 54 for removing impurities, and the first and second portions.
Via the heat exchangers 56 and 57 of (1) and cooled to an ultra-low temperature state and fed into the lower column 60 of the rectification column 58.

In the lower tower 60, the compressed air introduced is brought into contact with the liquid nitrogen overflowing from the liquid nitrogen reservoir 67 countercurrently to cool it, and a part of it is liquefied to form a liquid at the bottom of the lower tower. Store as air 61. In this process, the difference between the boiling points of nitrogen and oxygen (boiling point of oxygen -183 ° C, boiling point of nitrogen -196)
(° C), oxygen, which is a high boiling point component in the compressed air, is liquefied and nitrogen remains as a gas. Then, a part of the nitrogen gas accumulated in the ceiling portion of the lower tower 60 is part of the first reflux pipe 6
3 is introduced into the condenser 62 provided in the upper tower 59, is cooled and liquefied by the liquid oxygen accumulated in the bottom of the upper tower 59, and is passed through the second reflux pipe 64. It is led out to the reflux liquid reservoir 67 of the lower tower 60.

The liquid air stored at the bottom of the lower tower 60 is fed into the upper tower 59 in adiabatic expansion state via a pipe 66 and an expansion valve 65, and is subjected to a rectification action. Then, oxygen, which is a high-boiling point component, is liquefied and accumulated at the bottom, and low-boiling point component gas containing nitrogen gas is sent out as exhaust gas from the top of the upper column 59 via the pipe 70. The discharged exhaust gas passes through the second and first heat exchangers 57 and 56, is heated to near room temperature, and is discharged into the atmosphere. Upper tower 5
The liquid oxygen 71 collected at the bottom of 9 is passed through the pipe 72, pressurized in the liquid state by the first pressurizing pump 73, and then introduced into the second heat exchanger 57, where heat is exchanged. It is gasified and introduced into the product oxygen gas extraction pipe 74. Then, the introduced oxygen gas is adiabatically expanded by the first expansion turbine 75 provided in the product oxygen gas extraction pipe 74 to generate the amount of cold required for the entire device, and again to the second expansion turbine 75.
Into the first heat exchanger 56 and exchanges heat with the raw material air in both the heat exchangers 57, 56, and becomes itself oxygen gas at room temperature, and the product oxygen gas extraction pipe 74 Taken out from the tip of. A part of the refluxed liquid nitrogen extracted by the liquid nitrogen extraction pipe 90 is pressurized in the liquid state by the second pressure pump 91 and then introduced into the second heat exchanger 57, where It is gasified by heat exchange and introduced into the product nitrogen gas extraction pipe 92. Then, the introduced nitrogen gas is adiabatically expanded by the second expansion turbine 93 provided in the product nitrogen gas extraction pipe 92 to generate cold, and again the second heat exchanger 5
7 and further into the first heat exchanger 56, where heat is exchanged with the raw material air in both heat exchangers 57 and 56, and the nitrogen gas itself becomes room temperature, and the product nitrogen gas extraction pipe 74
Taken out from the tip of.

Therefore, according to this apparatus, since the liquid oxygen is pressurized as it is, the pressurized product oxygen gas can be obtained at low cost. Moreover, since the pressurized liquid oxygen is vaporized and then introduced into the first expansion turbine 75, the gas pressure before entering the expansion turbine 75 becomes high,
As a result, the efficiency of adiabatic expansion can be greatly improved. In this case, since the pressurizing pressure of the pressurizing pump 73 for pressurizing the product oxygen gas can be utilized, effective use of energy can be realized and the cost of the product pressurizing gas can be considerably reduced. On the other hand, since the product nitrogen gas take-out line has the same configuration as described above, it is possible to considerably reduce the cost of the product nitrogen gas.

In the apparatus of the above embodiment, the liquid level gauge 82
Is provided to control the liquid oxygen supply control valve 81. Therefore, when the demand amount of the product oxygen gas or the product nitrogen gas sharply increases and the raw material air supply amount is correspondingly increased, the cold generation generated can be rapidly increased by the expansion turbines 75 and 93. However, at this time, the control valve 81 is actuated by the output signal from the liquid level gauge 82 to quickly supply the liquid oxygen to the upper tower 59 to eliminate the lack of cold.

However, in the above embodiment, the liquid level gauge 82 reads the liquid level height of the liquid oxygen in the upper tower 59. However, the liquid level gauge 82 is provided on the lower tower 60 side and the lower tower 60 is provided. There is no problem even if the liquid level height of the liquid air accumulated inside is read.

In the above embodiment, a part of the liquid nitrogen is taken out from the second reflux pipe 64, but it may be taken out from the liquid nitrogen reservoir 67.

FIG. 2 shows an apparatus according to another embodiment of the present invention. In this device, the first pressurizing pump 73 is housed in a hermetically sealed casing 73c, and liquid oxygen is introduced into the casing 73c to pressurize it and lead it out to the pipe 72. Then, the return pipe 2 that returns the oxygen gas vaporized from the upper portion of the casing 73c to the upper tower 59.
3b is provided. Further, the second pressurizing pump 91 is housed in the hermetically-sealed casing 91c.
Liquid nitrogen is introduced into the inside, pressurized, and led out to the pipe 90. A return pipe 91b for returning the nitrogen gas vaporized from the upper portion of the casing 91c to the lower tower 60 is provided. The other parts are the same as those of the apparatus shown in FIG. With this configuration, it is possible to prevent the occurrence of a situation in which gas bubbles are sucked and the first pressure pumps 73 and 2 of the first pressure pump 91 run idle (gas trapping phenomenon).

[0022]

As described above, in the oxygen / nitrogen gas production apparatus of the present invention, the rectification column is divided into upper and lower two columns, the liquid oxygen produced in the upper column is taken out, and pressurized in a liquid state. Then, it is sent to a heat exchanger, further introduced into an expander for generating cold heat, adiabatically expanded to generate cold, and the cold generated is sent to the heat exchanger to serve as a cold source for the device. As described above, pressurizing oxygen in a liquid state can significantly reduce the pressurization cost as compared with pressurizing in a gas state. Moreover, in the present invention, as described above, oxygen is pressurized in a liquid state and then vaporized by a heat exchanger, and this pressure is used to drive an expander for cold heat generation such as an expansion turbine to obtain cold, The energy used for oxygen pressurization can be used for cold generation, and as a result,
Product costs can be reduced. This is the greatest feature of this invention. Moreover, in the present invention, a part of the refluxed liquid nitrogen introduced into the lower column is taken out in order to obtain product nitrogen gas, which is also pressurized in a liquid state, and then vaporized in a heat exchanger to cool it. Introduced into a generating inflator and adiabatic expansion to generate cold,
The generated cold is sent to the heat exchanger again and used as a cold source for the entire apparatus. Therefore, for product nitrogen gas,
Since the pressurizing energy can be applied to the driving energy of the expander for generating cold heat, the cost of the product nitrogen gas can be significantly reduced. Due to these advantages, the device of the present invention can be effectively used in a wide range of fields such as steel manufacturing fields, chemical industry fields, and thermal power generation fields.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is a configuration diagram of another embodiment of the present invention.

FIG. 3 is a configuration diagram of a conventional example.

[Explanation of symbols]

 51 Air Compressor 56, 57 Heat Exchanger 58 Fractionation Tower 59 Upper Tower 60 Lower Tower 61 Liquid Air 71 Liquid Oxygen 72 Liquid Oxygen Extraction Pipe 73 First Pressurizing Pump 74 Product Oxygen Gas Extraction Pipe 75 First Expansion Turbine 90 Liquid nitrogen extraction pipe 91 Second pressurizing pump 92 Product nitrogen gas extraction pipe 93 Second expansion turbine

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] March 3, 1994

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

[Figure 1]

[Fig. 2]

[Figure 3]

Claims (3)

[Claims] 1. An air compression means for compressing raw material air, a heat exchange means for cooling the compressed air to an ultra low temperature, and a compressed air cooled to the ultra low temperature to introduce oxygen and liquefy oxygen to liquefy nitrogen by liquefaction separation. Lower rectification column to hold in a state, an upper rectification column to introduce liquid air taken out from the bottom of the lower rectification column into the column to liquefy and store oxygen in the bottom by liquefaction separation, and the upper rectification A liquid oxygen take-out passage for taking out liquid oxygen from the bottom side of the column, a product oxygen gas take-out passage extending from the tip of the liquid oxygen take-out passage to take out the liquid oxygen as a product through vaporization of the liquid oxygen, and the upper refinement. Condensing means provided in the distillation column for introducing and condensing a part of the gaseous nitrogen in the lower rectification column to liquefy, and liquid nitrogen for returning the liquid nitrogen taken out from the condensation means to the lower rectification column. Reflux path and above liquid Nitrogen gas taken out as a product nitrogen gas by evaporating the liquid nitrogen through the liquid nitrogen take-out path that takes out a part of the liquid nitrogen via the nitrogen reflux path and the tip of the liquid nitrogen take-out path through the heat exchange means. And a first outlet for pressurizing the liquid oxygen in the liquid oxygen outlet.
The pressurizing means is provided, and the flow path on the downstream side of the pressurizing means passes through the heat exchanging means, and then through the first expander for cold heat generation and again through the heat exchanging means. The liquid nitrogen take-out path is provided with a second pressurizing means for pressurizing liquid nitrogen, and a flow path downstream of the pressurizing means is provided with the heat exchange. An oxygen / nitrogen gas production apparatus having a structure in which cold is applied through the heat expansion means after passing through the second heat expansion means after passing through the second heat expansion device. 2. Liquid oxygen storage means for supplying liquid oxygen to the upper rectification column, and liquid oxygen supply from the liquid oxygen storage means so that the liquid level of the upper rectification column or the lower rectification column becomes constant. The oxygen / nitrogen gas production apparatus according to claim 1, further comprising control means for controlling the amount. 3. The oxygen / nitrogen gas production apparatus according to claim 1, wherein the first expander for cold heat generation is an expansion turbine made of a material having a low reactivity with oxygen.