JPS60161309A - Production of oxygen-enriched gas - Google Patents

Abstract

PURPOSE:To produce O2-enriched gas with high efficiency by combining specified processes utilizing adsorption under varied pressure and separating N2 from a gaseous mixture consisting essentially of O2 and N2. CONSTITUTION:Three adsorption towers packed with adsorbent are used. A primary pressure equalizing process is proceeded by connecting a tower A with another tower B or C at the end parts of produced gas of each tower wherein pressurized gaseous mixture is fed from an end part of the feed gas of the tower A, and the tower B or C has been already pressurized by the gaseous mixture to a specified pressure and discharges produced O2-enriched gas. Further, a purging process is performed for cleaning the inside of the adsorption towers by introducing O2-enriched gas from other tower from the produced gas end of the tower while the tower is evacuated from the feed gas end and desorption of N2 is being carried out. Thus, O2-enriched gas as product is discharged continuously without interruption during the cycles of the processes.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to a method for producing oxygen-rich gas. More specifically, the present invention uses an adsorbent that selectively adsorbs nitrogen to adsorb and remove nitrogen from a mixed gas containing oxygen and nitrogen, such as air, by pressure fluctuation adsorption to produce oxygen-rich gas. Regarding the method.

Conventional technology adsorbents such as synthetic zeolite and natural zeolite for nitrogen! It is known that an oxygen-rich gas can be produced by separating an oxygen/nitrogen mixed gas such as air by pressure fluctuation adsorption using selective adsorption (for example, Japanese Patent Publication No. 51-40
549 and 51-40550, and JP-A-56-fi3
804 and 58-84020). In producing oxygen-enriched gas using this method, nitrogen is adsorbed and removed by introducing an oxygen/g element mixed gas into a plurality of adsorption towers each containing a bed of adsorbent. The gas enriched with concentrated oxygen adsorbed by the chicks is made conductive from the adsorption tower to become a product gas.Then, pressure reduction, injection, exhaust, etc. are performed to regenerate the adsorbent in the adsorption tower. The step and the adsorption/separation step are sequentially switched in each adsorption tower.

However, in the conventionally known method for producing oxygen-rich gas using pressure fluctuation adsorption, there are problems such as insufficient oxygen separation and recovery efficiency and high energy consumption per product gas produced. There are still problems, and there is still room for improvement.

OBJECTS OF THE INVENTION The present invention mainly provides a method for producing oxygen-rich gas by pressure fluctuation adsorption, which has higher oxygen separation and recovery efficiency than conventional methods and consumes less energy per amount of product produced. The purpose is to

According to the invention, three adsorption towers filled with a bed of adsorbent that selectively adsorbs nitrogen are used, and a mixed gas containing oxygen and nitrogen is made to flow through the adsorption towers to remove nitrogen. A method is provided for producing oxygen-rich gas by adsorption and removal. In this method according to the present invention, in the first adsorption tower, (1) a pressurized mixed gas is introduced from the end of the raw material, and at the same time, oxygen-rich gas from the second adsorption tower is introduced from the end of the product; (2) Introducing pressurized mixed gas from the end of the raw material to selectively adsorb nitrogen, and at the same time leading out oxygen-rich gas from the end of the product. (3) The introduction of the pressurized mixed gas is stopped, and the oxygen-rich gas is drawn out from the end of the product. (4) Deriving oxygen-rich gas from the product 4j (fl) and supplying the oxygen-rich gas to the /Z of the second adsorption tower; (5) evacuation from the end of the raw material under reduced pressure, and (6) while evacuation from the end of the raw material, supplying the product to the product end of the second adsorption tower. A step of purging the inside of the column by introducing oxygen-rich gas from the end of the product, and during this step, the process cycle is carried out with the phase changed in each of the second and third adsorption columns. It is characterized by

DETAILED DESCRIPTION OF THE INVENTION The present invention utilizes pressure fluctuation adsorption to extract nitrogen from a mixed gas mainly containing oxygen and nitrogen, such as air.
ltL, to obtain oxygen-rich gas. That is, a pressurized mixed gas is supplied to an adsorption tower filled with an adsorbent such as synthetic ceolide or natural zeolite, and the adsorbent adsorbs nitrogen, concentrating oxygen and releasing it as a product gas. . Next, the nitrogen adsorbed by the adsorbent is desorbed by vacuuming the adsorption column filled with the adsorbent adsorbing nitrogen from the raw material end side.

In the present invention, three adsorption towers filled with adsorbent are used, and while pressurized mixed gas is supplied from the raw end of one tower, the pressure has already been increased to a predetermined pressure by the mixed gas. Then, a pressure equalization process is performed in which the product end is connected to another column which is discharging oxygen-enriched product gas, and the pressure between the two columns is equalized. In addition, while nitrogen is being desorbed by vacuum suction from the raw material end, a purge process is carried out in which oxygen-rich gas from another tower is introduced from the product end of the tower to clean the inside of the tower. . The product oxygen-rich gas is then released continuously during the process cycle.

Therefore, by supplying oxygen-rich gas from the product end of the adsorption tower to equalize the pressure, it is possible to shorten the nitrogen adsorption front in the tower and increase the acid-oxygen concentration in the resulting gas. .・Year is enriched during vacuum desorption of nitrogen.
By supplying enzyme gas from the end of the product and passing it through the column, the partial pressure of the 9 elements in the column is lowered, increasing the desorption effect, and reducing the time for vacuum desorption, reducing power costs. It has the effect of

According to the method of the present invention having such a configuration, it is possible to produce an oxygen-rich gas with a high oxygen concentration, particularly an oxygen concentration of 90 to 93 or more, with extremely high efficiency and efficiency. The vacuum pump is also turned off and remains active throughout the cycle.

Hereinafter, the method of the present invention will be specifically explained with reference to FIG. 1, but it should be understood that the operations shown below are merely examples and are not limited to these operations.

In operation, oxygen-rich gas is continuously released by sequentially repeating the six steps described below. Further, the operation time of each step can be arbitrarily controlled by a timer.

'Step 1 The valve 1A is opened, the pressurized air 20 is dehumidified by the mist separator 21, and is supplied from the lower part of the A tower, that is, the end of the raw material. At the same time, valves 2A and 2C are opened, and while the pressure is increased to a predetermined pressure by the air already pressurized in the previous step (step 86), valve 12C is opened to release the oxygen-rich gas of the product. The pressure between the A column and the C column is equalized by connecting the columns with a pipe 18 and introducing oxygen-rich gas from the upper part of the C column, that is, the product end, to the product end of the A column. (equal pressure). At this time, the outflow rate of oxygen-rich gas from the C tower is controlled by valves 6A and 6C.

On the other hand, the valve 4B is opened to reduce the pressure, and the B tower is evacuated by the vacuum pump 7'19.

Step 2 Valve 2A and 12C are closed and at the same time valve 12A is opened, and product gas is discharged from A column. While releasing product gas, tower A is supplied with pressurized air through valve IA, and the pressure inside the tower is gradually increased. on the other hand,
The valve 3B is opened, and oxygen-rich gas is supplied from the product end of the C tower to the product end of the B tower, and is discharged to the outside of the system by the vacuum bonder 19 while washing the inside of the B tower in the countercurrent direction.・Coutts).

The C tower supplies oxygen-rich gas to the B tower while further reducing the pressure. The feed rate of oxygen-enriched gas from the C column is controlled by valve 17.

Step 3 Valves IA, 2C, and 4B are closed, and valve IB is newly opened to supply pressurized air from the raw material end of the B column.

At the same time, valves 2A and 2B are opened, and oxygen-rich gas is supplied from the product end of the A column to the product end of the B column.
The pressure between the columns is equalized (pressure equalization). This 119. ,A
The rate of extraction of oxygen-rich gas from the column is controlled by valves 6A and 6B. On the other hand, the valve 3B does not close, but the valve 4C opens, and the C tower is depressurized and exhausted by the depressurized direct air/input pump 19.

Step 4 Valve 2B and 12A are closed, and at the same time valve 12B is opened to release the product gas from the column Il''jXB. While the B column releases the product gas, it also releases the pressurized air through Group IB. The pressure inside the column is gradually increased.Meanwhile, valve 3C is opened, and oxygen-rich gas is supplied from the product end of the A column to the product end of the C column. While being washed in the countercurrent direction, it is discharged out of the system by the X'9 chimp 19 (throw).

Tower A further reduces the pressure while supplying oxygen-rich gas to tower C. The supply rate of oxygen-rich oxygen-/fs from A tower is determined by valve 1.
Controlled by 7.

Step 5 Valves IB, 2A, and 4C are closed, valve IC is newly opened, and pressurized air is supplied from the raw material end of the C tower.

At the same time, valves 2B and 2C are opened, and oxygen-rich gas is supplied from the product stream Ib of the B column to the product end of the C column, so that the pressure between the B column and the C column is equalized (pressure equalization). At this time, the outflow rate of oxygen-enriched gas from the B tower is controlled by valves 5B and 6C. Meanwhile, valve 3C is closed and valve 4
A is opened and depressurized, and the A column is evacuated by the vacuum pump 19.

Step 6: At the same time as valves 2C and 12B are closed, valve 12C' is opened and product gas is released from the C tower. 1i in C tower,
While discharging the product gras, the respective pressures are gradually increased as pressurized air is supplied through valve ICf.Meanwhile, valve 3A is opened and the product gra from column B is released.
Oxygen-rich gas is supplied from the A section to the product section of the A tower, and
While cleaning the inside of the tower in the anti-perspirant direction, it is discharged outside the system by the direct air pump 19 (park).

While supplying oxygen-rich gas to tower B and tower A, the pressure is gradually reduced. 41 of the oxygen-rich gas from the B tower (valve 1 to the degree of freezing)
Controlled by 7.

In FIG. 1, 22 indicates the outflow of oxygen-rich gas as a product, and 23 indicates the outflow of nitrogen that has been removed.

As can be understood from the above explanation, the above 6 steps are:
Steps 1 and 2 are treated as one unit, and the steps are repeated while changing the phase of each column one by one. FIGS. 2 and 3 are schematic diagrams illustrating these two basic steps (steps 1 and 2).

As explained above, in the method of the present invention, the pressure within each column is constantly fluctuating and never remains at a constant pressure for a moment. This is to improve the oxygen yield by reducing the amount of oxygen discharged outside the system as much as possible by exchanging oxygen between each column. Even if the maximum adsorption pressure and the ultimate vacuum pressure are set in a high range, the average pressure and the average vacuum pressure are kept as low as possible to reduce the power cost.

In addition, although purge is an essential operation for stably producing product gas with a high oxygen concentration (1), controlling the maximum park amount does not require knowing the absolute amount; It can be considered as the amount of pressure drop (represented by .xi.-di.DELTA.P) in the column that supplies the . Nonoji ΔP is usually in the range of 01 to 10 kP/i, and the best oxygen concentration and recovery rate are determined for each maximum adsorption pressure, ultimate vacuum pressure, and cycle time.

The factors that evaluate the efficiency of the acid-rich gas production process using pressure fluctuation adsorption are oxygen concentration and yield, but there is also one other factor.
One factor is the ratio of the amount of adsorbent, such as a molecular sieve, to the oxygen-producing bone per unit time.

In the following examples, this factor will be referred to as the ped size factor ('B, S, F,), and its units will be (kl?
・MS)/(t-0,,/d) [(kg・molecular sieve)/(ton・100 units 02/day)] These B, S, F, and kt are factors related to the quality of the process and the molecular sieve, but when molecular sieves of the same quality are used, they serve as factors for evaluating the process. As is clear from the above units, a process in which B, S, and F exhibit small values can be considered a preferable process.

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

Example 1 A three-base adsorption tower with an inner diameter of 81 cTL and a height of 25 cm was equipped with molecular sieve 13 as an adsorbent.
X° size 8-12 mesh beads per tower 9.
I used 9 out of 14. Under all operating conditions, the maximum adsorption pressure was 0.
5 k2AG, ultimate vacuum pressure 20 Q Torr.

When the cycle time was changed for each experiment number and continuous rotation was carried out according to the above-mentioned process, the results shown in Table 1 were obtained.

Below are blank spaces Example 2 Using the same three-base adsorption tower as in Example 1, the operating conditions were a maximum adsorption pressure of 0.5 kg/crn'', G, Jj,
Ultimate air pressure 360 Torr, zw-diΔP0.27 to φ/
d, cycle time f was changed for each frame number, and continuous operation was performed according to the above-mentioned process. The results shown in Table 2 were obtained.

Comparative Example 1 The following is a margin Comparative Example 1 Using the same adsorption tower as in Example 1, the operating conditions were a maximum adsorption pressure of 0.5 kg/crr? G, direct nitrogen ultimate pressure 200T
When the cycle time was changed for each experiment number and continuous operation was performed according to the process described above, the results shown in Table 3 were obtained. . In this experiment, the oxygen concentration did not exceed 85 coefficients, and the oxygen yield was also the value shown in Example 1. Comparative Example 2 Using the same adsorption tower as in Example 1, the operating conditions were ``high volume adsorption pressure 0''. The pressure of the .5 kg7 test was reduced by blowing it down under its own pressure without suctioning it into a vacuum (that is, keeping the vacuum f?7 f temporarily stopped). Purge ΔP
0.2 kg/ctrl! Continuous operation was performed by changing the closing and cycle time for each experiment number, and the results shown in Table 4 were obtained, but only extremely low concentrations and yields were obtained.

Below margin

[Brief explanation of the drawing]

FIG. 1 is a system diagram for explaining the method of the present invention, and FIGS. 2 and 3 are schematic diagrams showing the order of process operations of the method of the present invention, respectively. A, BX C... adsorption tower; IA~IC, 2A~2C
. 3A to 3C, 4A to 4C... Valve; 19... Vacuum pump. Mr. Kan, Patent Attorney, Showa Denko K.K., Patent Attorney, Akira Aoki, Patent Attorney, Kazuyuki Nishidate, Patent Attorney.

Claims (1)

[Claims] 1. Using three adsorption towers filled with beds of a binder that selectively adsorbs nitrogen, a mixed gas containing oxygen and nitrogen is flowed through the adsorption towers to adsorb and remove nitrogen. This is a method for producing oxygen-rich gas by: (1) introducing pressurized mixed gas from the end of the raw material in the adsorption tower of ty2 IJ; A step of introducing oxygen-rich gas from λ1 part of the product v and equalizing the pressure with the second adsorption tower, (2) Introducing pressurized polymerization gas from the raw material i>, I' BIX and selecting dVl from the q1 process. Let me suck it up, 111! Step of increasing the pressure inside the column while taking out two cores of oxygen-rich gas from the Cf% part of the even J product, (3) Stopping pressurized mixing and introduction of the resultant gas, and starting from the product ``'p'' flll+. While deriving the oxygen-rich gas, a part of this oxygen-rich gas is supplied to the product end of the adsorption tower in the 3rd column to equalize the pressure with the adsorption tower in the previous N', m 3, (4) a step of deriving oxygen-rich gas from the product end and supplying the oxygen-rich gas to the product end of the second adsorption tower for parts of the second adsorption tower; (5) evacuation from the raw material end under reduced pressure; and (6) a step of introducing oxygen-rich gas from the third adsorption tower to some part of the product to purge the inside of the tower while evacuation is performed from the end of the raw material, and further during that time, A method characterized in that the process cycle is carried out in different phases in each of the second and third adsorption towers.