JPS59161668A - Method of liquefying and separating air - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an air liquefaction separation method for collecting argon along with oxygen and nitrogen.

Generally, crude argon is obtained by 4B distillation separation,
After removing the oxygen contained in this argon by chemical treatment, highly pure argon is obtained by distillation separation. To explain this with reference to Figure 1, which shows a conventional air separation method for collecting crude argon, an air compressor (not shown) produces approximately 5 kg/
The raw air compressed to ca. / cnt, and is supplied to the lower part of the lower cylinder 4 of the double rectifier through the tube 3. In the lower column 4, preliminary +N storage is performed, and nitrogen is separated at the top, and the liquid nitrogen separated at the top is extracted from the tank 5 and introduced into the top of the lower column 6. The liquid air at the bottom of the upper tube 4 is extracted from the tube 7 and introduced into the middle of the upper curve 6, and flows down the upper tube 6 as a reflux liquid. -Do it.

The flowing reflux liquid comes into gas-liquid contact with the rising gas in each so-called shelf, and rectification is performed, and liquid oxygen is separated in the condenser 8, and L mature tree gas is separated directly above it. The separated oxygen gas is led out through the pipe 9 and enters the reversing heat exchanger 2, where the raw air is cooled to room temperature and sent out as product oxygen gas. -The vaporized gas rising inside the upper cylinder 6 is d
! From the top of the upper quotient 6, the nitrogen gas is led out to the pipe 10, where it exchanges heat with the raw material air in the prefertilization purging heat exchanger 2, and becomes room temperature and is sent out as a product nitrogen gas.

Further, in the argon cylinder 11, 8 to 12% argon, a trace amount of nitrogen, and the remainder acid
The argon (argon) i from the pipe 12, the family gas B'
Introduced to the lower part of MT11. A part of the liquid air extracted from the bottom of the lower cylinder 4 is branched into the condenser 13 of the argon tank 11 and introduced through the argon tank 14, and the argon gas rises completely inside the argon tank 11 to form the argon gas. Most of the argon source gas is condensed through heat exchange with the raw material gas, and the self-sphere is vaporized and introduced into the intermediate stage of the upper cylinder 6 before 1715. 13 condensing side)
The argon raw material gas condensed in step 1 flows down completely in the crude argon cylinder 11 as a reflux liquid, and the gap between it and the rising gas is 1/l.
The crude argon having a composition of 95 to 98 parts argon, 1 to 3 parts oxygen, and about 1 to 3 parts is led out from the top of the crude argon straw 11 to the tank 16, and is subjected to a known argon refining process ( (not shown) and produced as high purity argon. In addition, the bottom liquid remaining at the bottom of the crude argon cylinder 11, which is mostly liquid oxygen, passes through the tube 17 and is returned to the upper cylinder 6 at almost the same position as the position from which the argon raw material gas r was discharged. .

In order to compensate for the cold required for the operation of these devices, a part of the compressed air is branched to g18 to reheat the reheat flow of the reversing heat exchanger 2. After entering the pipe and being reheated, the air is further adiabatically expanded in the expansion turbine 19 to generate cold air, and then blown into the middle stage of the upper cylinder 6 through the pipe 20.

Argon extraction by the conventional vapor liquefaction separation method is usually carried out as described above, but there are 3 cases, 6 cases. For example, in general ++? ? *r In r71, the rust surface efficiency is better when the ratio L/V of lower reflux liquid and upward vaporization is 5>1゛ in the rice section (upper part); It is known that the smaller the L/V, the higher the 1N storage efficiency.However, when considering the 1./V of the upper cylinder 6 in the above conventional air separation method,戊t!,'
In 6, since the system that returns from the bottom of the crude argon node 11 is a liquid, the upper rats t;Ij6
to +', the part below the ri part is L/V by this amount
is getting bigger. -1: In the folded part, the tube part 4
Part of the liquid air flowing from the bottom to the upper TFIJ cylinder 6 is vaporized by the argon tank 11 condenser 13, and then blown into the upper cylinder 6 from the first pipe 15, resulting in a shortage of reflux liquid, and the raw air 'i7 after being depressurized and expanded by the expansion turbine 19
．． 20, so the rising gas in this part is 1
．． :, 91 Pump 2 1)/V1 direct is made small 13 Therefore, the small upper part: Introducing the liquid into the so-called 6 Blowing of gas It is difficult to harvest argon from bamboo because it reduces efficiency! It is very unfavorable because the renal condition is "demanded".

Furthermore, according to the conventional method shown in Figure 2111, P in the 4th part of the lower part)
When the L body and air are supplied to the upper I4 and K6 through the diode F7, a portion of the air is branched to the same du, and is sent to the condenser J at the top of the coarse argon cylinder 11.
After being evaporated, the argon gas is blown into the upper space 6, so changes in the operating conditions of the main argon cylinder and coarse argon cylinder are caused by A1j.
However, because the cooling source of the crude argon cylinder condenser is liquid air, the increase in crab element content in the argon raw material gas is sufficient. There were also 3 failures such as not being cooled.

The present invention has been developed from the above. Nitrogen discharged from the top of the upper cylinder is pressurized, liquefied by heat exchange, and used as a cooling source for the coarse argon condenser at the top. The liquid oxygen derived from the above is exchanged with the nitrogen, vaporized and returned to the upper cylinder, and the pressurized nitrogen is further expanded in a no-forming turbine to generate refrigeration, which is then used in a reversing heat exchanger). By recovering cold water, the rectification efficiency of the upper cylinder is greatly increased, and the purity and purity of oxygen and nitrogen are improved.
This is an air liquefaction separation method that makes it possible to greatly improve the argon yield without reducing the yield.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 2 is a system diagram showing one embodiment of the present invention, and the same reference numerals and explanations are used for co-traced parts as in FIG. 1.
A part of the nitrogen drawn out from the top of i+j 6 branches into pipe 22. The nitrogen is introduced into the circulating nitrogen heat exchanger 24 through the pipe 23, where it is exchanged with pressurized nitrogen flowing countercurrently and heated at room temperature.
Derived from the circulating nitrogen compressor 26 and put about 5 K4
/ C++! Compress it into The pressurized 9 elements led out of the circulating nitrogen compressor 26 enter the circulating heat exchanger 624 through the pipe 27,
After exchanging heat with the low temperature chamber ≦ζ gas from the front tube 23 and cooling it to the saturation temperature and leading out to the tube 28, it is divided into two parts, one of which is passed through the tube 29.
The crude argon enters the heat exchanger 30 through the bottom of the crude argon cylinder 11 through the pipe 17 and is liquefied by countercurrent heat exchange with the liquid oxygen introduced. It is introduced into the top condenser 13.

In the coarse argon condenser 13, the crude argon rises in the cylinder l1 and exchanges heat with the rice gas to liquefy it to produce a reflux liquid, which is vaporized and led out through the pipe 32, and then 22 and a confluent pipe 23 into a heat exchanger 24. It is circulated to the circulating nitrogen pressure machine 26.

On the other hand, the crude argon cylinder 1 is extracted from the bottom of the heat exchanger 30.
The liquid oxygen that has entered is vaporized in the heat exchanger 3o, and is blown into a stage slightly lower than the stage from which the argon raw material gas in the upper cylinder 6 was extracted through the pipe 33. With this, the argon cylinder 1
Oxygen that normally returns in liquid form to the upper cylinder 6 from the bottom part of the cylinder 6 can be returned in gaseous form, so the L/V value at the lower part of the upper cylinder (recovery part) becomes smaller and the nitrification efficiency increases. Another argon cylinder! A
Since the cooling of the condenser 13 in the section is performed by circulating liquid nitrogen, the operation of the main phase reservoirs 4 and 6 and the operation of the argon section 11 are not affected by each other.

Next, the pre-6 recirculation nitrogen heat exchanger 24 is obtained, and part of the gas is branched off in the pipe 28, and the other nitrogen flow passes through the pipe 34 and enters the reheat flow path 35 of the reversing heat exchanger 2. After the temperature is raised by the expansion turbine 19, the temperature is lowered to approximately atmospheric pressure -180
It becomes about °C and goes to tube 36 2! Air output, FliT convex top 81S1 Tsuji 6 top group, connects with one side of the air flow which is divided into two, connects to the reversing heat exchanger 2 through pipe 37, and gives the raw air an outer layer. After that, it is sent to the device group Y.

The present invention is carried out as described above, and its features and effects are as follows. First, the cooling liquid of the crude argon simple condenser is made into circulating nitrogen, and the liquid oxygen extracted from the bottom MS of the crude argon cylinder is heat exchanged with the circulating nitrogen, so that the oxygen is returned to the upper cylinder as a gas. The L/V value of the recovery section (lower half) of the upper cylinder 6 became smaller, the rust surface condition improved, the separation efficiency of the plating/chamber system improved as well as the argon yield, and the production increased to 0T. . In addition, since the crude argon gj condenser is cooled and the vaporized nitrogen is circulated without being returned to the main tank 1z, there is no need to blow gas into the upper part of the upper cylinder that accompanies conventional argon sampling. This has a positive effect on the L/V value at the cylinder misconstriction, improving the rectification conditions and improving the argon yield. Furthermore, coarse argon is introduced: liquid air is not consumed in the reformer, so that amount is introduced into the middle of the upper cylinder] There is no decrease in the JJ flow liquid, and therefore the conditions in the sheath part will deteriorate when argon extraction and transport are not carried out. The argon yield can be totally improved without reducing the oxygen yield and purity. Second, since we adopted the one-nim self-circulation system and used liquid WA as the cooling source for the crude argon condenser, the amount of water accumulated in the argon raw material gas increased, as in equipment 1 that uses liquid air. However, the argon source gas can now be discharged from the argon peak point of the main reservoir without the argon cylinder becoming unstable. Furthermore, even if the operating conditions of the raw silk oil cylinder or the operating conditions of the argon cylinder are changed, there is no shadow of %9J between them, and operation has become very easy. Thirdly, after a part of the circulating nitrogen is removed from the reheat circuit of the reversing heat exchanger, the expansion chamber is
By generating cold air by cooling the air and passing it through the reparsing heat exchanger to cool the raw air,
The blowing of expanded gas into the upper cylinder was stopped, eliminating the cause of difficulty in improving the argon yield. Fourthly, since the liquid oxygen led out from the bottom of the crude argon cylinder is heat-exchanged, vaporized, and returned to the middle of the upper cylinder, the installation position of the coarse argon cylinder can be lowered, and the equipment construction cost can be reduced accordingly.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing 1'ρIJ of a conventional air separation method for collecting *jl 'J' rugone, and FIG. 2 is a system diagram showing an embodiment of the present invention. 4 is the F section, 6 is directly above, 11 is the rough argon front, 19
24 is a circulating heat exchanger, 26 is a circulating nitrogen compressor, and 30 is a heat exchanger.

Claims (1)

[Claims] i. Air that is liquefied and rectified to separate oxygen and nitrogen, and at the same time extracts argon raw material gas from the middle of the upper cylinder of a double coffin cylinder and introduces it into the argon column to produce argon. In the liquefaction separation method, a part of the nitrogen gas discharged from the upper part of the upper cylinder is branched, and after pressurizing the branched nitrogen gas, a part of it is heat-exchanged with liquid oxygen extracted from the bottom of the crude argon cylinder. Air liquefaction separation characterized in that the gas is vaporized and introduced into the upper cylinder, and after being liquefied, it is introduced into an argon cylinder condenser to cool it, and after being vaporized and led out, it is combined with the branched nitrogen gas. Method. 2. An air separation method in which air is liquefied and rectified to separate L and nitrogen, and argon raw material gas is extracted from the middle of the upper cylinder of a double-type blue distillation cylinder and placed in the outer argon cylinder by four people to produce crude argon. At the top of the upper cylinder (1), a part of the nitrogen gas that is extracted is combined with the phase argon (described later) and the nitrogen gas that is extracted from the rice cooker, and the nitrogen gas is divided into two parts after the external pressure by nitrogen compression. One side of the crude argon was extracted from the bottom and exchanged heat with liquid oxygen to vaporize it and put it into the upper cylinder, and after liquefying it, it was introduced into the argon cylinder condenser to cool it. After being vaporized and discharged, it is circulated, and the other nitrogen gas beam, which has been divided into two parts, is heated in the reheat flow path of the purging heat exchanger, and then expanded by an expansion turbine. of nitrogen, and discharged after hard cooling recovery by the reparsing heat exchanger.
: Air liquefaction separation method with percentage characteristics.