JPS60231402A - Production of oxygen with ca-na-a and na-x-alo3 in n2 adsorption tower - Google Patents

Abstract

PURPOSE:To produce O2 with inexpensive adsorbents by packing the upper stream side of an adsorption tower with Ca-Na-A type zeolite and the downstream side with alumina added Na-X type zeolite so as to reduce the consumption unit of power required and the amount of the adsorbents required. CONSTITUTION:A gaseous mixture contg. O2 and N2 as principal components is introduced into an N2 adsorption tower at a temp. below room temp. under atmospheric pressure -3atm. N2 is selectively adsorbed in the tower, high purity O2 or O2 enriched gas is discharged, and the tower contg. the adsorbed N2 is evacuated to 0.045-0.55atm. to carry out regeneration. In this method, the upper stream side of the tower where the concn. of O2 does not exceed 50% is packed with Ca-Na-A type zeolite, and the downstream side is packed with alumina added Na-X type zeolite. The Ca-Na-A type zeolite adsorbs a larger amount of N2 than the Na-X type zeolite by 18-20% in the region where the concn. of O2 does not exceeds 50% while maintaining N2 selectivity comparable to that of the Na-X type zeolite, so O2 is produced with the N2 adsorption tower adsorbing a large amount of N2 and maintaining high N2 selectivity as a whole in the N2 adsorption tower.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention utilizes an N2 adsorbent that selectively adsorbs KN2 from a mixed gas mainly composed of O, , N2, such as air. A mixed gas whose main component is N2'I 02 +
The present invention relates to a method for separating N2.

The N2 adsorption separation method from air using a N2 adsorbent has the advantage that the equipment is small and simple, and almost no maintenance is required, which is close to unmanned operation.
,000 Nm-o, ./h have been increasingly used as small and medium-sized devices in recent years, and alternatives to cases in which liquid oxygen produced in cryogenic separation devices is transported and used are progressing.

Let me give an overview of the typical devices.

The apparatus consists of an air compressor, two or more N2 adsorption towers, and in some cases a vacuum pump. In this device, when compressed air is sent to one column, the N
2. N2 in the air is adsorbed and removed by the adsorption agent, and the remaining high pressure O2 flows out to the rear of the adsorption tower and is recovered. On the other hand, in other towers, the adsorbed N2 is released under reduced pressure conditions (sometimes a part of the product O2 is flowed in a countercurrent, or a vacuum pump is used to forcefully release the N2).
2) Regeneration. This is repeated alternately to separate continuous [o, , N2.

A typical N2 adsorbent packed in the adsorption tower mentioned above is Na-A, which was put into practical use by Union Carbide.
It is a 60-70% C11 exchanger of type zeolite and has +02
．． It selectively adsorbs N2 from a mixed gas containing two N2 components, and the co-adsorption of 02 under air conditions is 1 of the amount of N2 adsorption.
It is estimated to be less than 0%.

As mentioned above, the 02 and N2 separation equipment using this adsorption is advantageous in small and medium-sized areas, but it takes 0.7 to produce 1Nm of 02.
The power consumption is larger than 0.45 Kwll of 02, which is produced by large-capacity cryogenic separation method.

Also, there is little merit of scale for increasing equipment capacity (, 8
,000NIT? It is said that in the region of -02/h or higher, it cannot compete with cryogenic separation methods.

Therefore, various methods can be considered to improve these drawbacks, but when describing the improvement methods in connection with the present invention, the following problems usually occur.

First, in order to reduce power consumption, it is possible to lower the blowing pressure and perform the adsorption operation at low pressure, but since the amount of N2 adsorption decreases almost in proportion to the pressure, the capacity of the device increases significantly. Next, in order to increase the amount of adsorption, it is possible to perform the adsorption operation under low temperature conditions, but in this case, N2
Although the amount of adsorption increases, the rate of adsorption and desorption decreases significantly, so the concentration of product 02 at the same column length is actually lower than at room temperature. In addition, as the temperature decreases, the amount of O2 co-adsorbed during N2 adsorption increases, so in the process of conducting intensive research and experiments on a high-performance o, + N2 separation method under powered low-pressure adsorption conditions, we are currently conducting research and experiments at low temperatures.

Oa Na A-type zeolite (hereinafter referred to as Oa-
It is written as N a-A. ) is also at least 50 when examined in detail.
In the 02 concentration range not exceeding 1.0%, the patent application (hereinafter referred to as Na-X) maintains approximately the same N2 selectivity. N2
It was found that the amount of adsorption was 18 to 20% greater. That is, the present invention provides a method for controlling a mixed gas containing oxygen and nitrogen as main components at a pressure of at least atmospheric pressure and at most 8 ata at a temperature below room temperature.
2. The nitrogen contained in the mixed gas is selectively adsorbed by flowing into an adsorption tower, and high-purity oxygen or oxygen-enriched gas is discharged from the outlet of the adsorption tower, while the adsorption tower that has adsorbed nitrogen is heated to 0.
In the separation of oxygen and nitrogen from a mixed gas under low temperature and low pressure conditions where the pressure is reduced to 0.45 aha or more and 0.55 ata or less and regenerated, the O2 concentration in the column does not exceed 50% on the upstream side of the adsorption tower. Oa-Na-A is packed, and at least 59 or more sodium aluminate and Na-X are mixed on the downstream side of the adsorption tower. Other binders (e.g. kaolinite, halloysite etc.
) and pelletized adsorbent (hereinafter referred to as N
By filling the adsorption tower with N2e1. This paper proposes a method for producing oxygen from a mixed gas using a deposition tower.

The method of the present invention will be explained in detail below with reference to Examples.

EXAMPLE In order to demonstrate the effectiveness of the present invention, an attempt was made to separate 02 + N2 from air using a N2 adsorbent using the air separation apparatus shown in FIG.

The details of the implementation will be explained below based on FIG.

1.05 to 8 ata in compressor 2 through inlet side line 1
The pressurized air enters the dehumidification/dehumidification 002 tower 4 through the flow path 3, and becomes extremely clean pressurized air.

The pulp 5 installed in the upper stream of the channel 8' is open, and clean pressurized air enters the adsorption tower 8 through the channel 6 and the open pulp 7. The pressurized air that has entered the adsorption tower 8 has N2 adsorbed and removed by the N2 adsorbent 9, and the air flows backwards.
concentration increases. After this, the pressurized air is supplied to the valve 10 in the open state.
, 11, 12 and the product 02 tank 13 inserted between the nokurupu 11 and 12. On the other hand, a part of the product 02 is depressurized by the pressure reducing valve 15 located in the middle of the flow path 14, and enters the adsorption tower 8' through the open valve 10'. The adsorption tower 8' is depressurized and drawn by the vacuum pump 18 connected through the open valve 16 and flow path 17, so that part of the product 02 in the direction opposite to the air flow in the adsorption tower 8' is under negative pressure. The N2 that had been adsorbed on the adsorbent 9' in the adsorption tower 8' is easily separated from the adsorbent 9' in the adsorption tower 8'.
' is played in a short time. Generally, product 02 purge line 14. The pressure reducing valve 15 meets the parabolic purging conditions P/F.
There is a description of the ratio. ) When filled with Na-X or in the adsorption process of an adsorption tower where the 02 concentration does not exceed 50%, the upstream side is filled with Ca-Na-A, and the downstream side 1c
When filled with Na-X-A 1 203, the product 02 purge line 14 and the product 02 recirculation loop using the pressure reducing valve 15 are unnecessary, and regeneration can be performed simply by reducing the pressure.

The N2 adsorbent 9 in the adsorption tower 8 is saturated, while the N2 adsorbent 9 in the adsorption tower 8'
When N2 is removed from the adsorbent 9' and regeneration is completed, the inlet air flow path 6 is switched to 6', and the method described above is alternately performed to continuously recover the product 02. In addition.

A heat exchanger 19 is provided between the clean pressurized air line 3' at the inlet and the gas line 17 whose main component is separated N2.

Heat exchange is possible between product 02 line 21 and flow path 3.
′ can also be exchanged with the heat exchanger 22.

Also, since a compression refrigerator 20 is installed in the flow path 3',
Very efficiently the adsorption columns 8 and 8' are cooled and set to low temperature conditions. In addition, when switching the adsorption tower, it is necessary to not only simply switch from flow path 6 to 6' (or vice versa), but also to prevent inlet air from blowing away due to pressure increase immediately after switching, and to prevent air from remaining at the rear of the adsorption tower. In order to minimize the release of pressurized air from the
o, i5. to' is fully opened and a portion of the remaining 02 at the rear of the adsorption tower 8 immediately after adsorption is transferred to the adsorption tower 8' immediately after regeneration. At this time, if the pressure of the adsorption tower 8 is PO (ata) and the pressure of the adsorption tower 8' is PH (ata), then the pressure of the adsorption tower 8 after pressure equalization is
' is product 02 tank 1 with valves 10' and 11' open.
3 and the adsorption tower are equalized in pressure, and the adsorption tower 8' is filled with even higher pressure 02. Pressure P2 (a
La) is the dead volume of the adsorption towers 8 and 8' (volume of the space not occupied by adsorbent in the adsorption tower), V + (1), product 02
Assuming that the capacity of the tank is V2(1) and the pressure of product 02 tank 13 before pressure equalization is approximately equal to Po(ata),
The equalization pressure P2 (ata) is approximately ■I+v2, and is simply calculated from the pH (ata) at the time of switching the tower.
P for operations above 1 compared to the rapid pressure increase to Q(,1,a).

Po ten P.

(ata), (ata), P2(ata),
Since the pressure is gradually increased to Po(ata), the remaining o2. Measures can be taken to minimize the release of high-pressure air outside the system.

Air separation was carried out using the air separation apparatus shown in FIG. 1 using the above operating method. The operating specifications of the device are shown in Table 1.

Table 1 Adsorption device specifications Table 2 shows the mode of the filled adsorbent.

Table 2: Filling mode of adsorbent In this case, 70 parts by weight of Na-X, 15 parts by weight of sodium aluminate, and 15 parts by weight of kaolinite were mixed and fired at 450°C for 1 hour to form pellets. X
Al 203 was used.

+CaNa-A and Na prior to all Examples
In order to understand the adsorption characteristics of X at low temperature and low pressure, the separation characteristics were investigated under the test conditions shown in Table 3.

Table 3 operating conditions are adsorption tower pressure 12ata + desorption pressure 0211t
a+adsorption tower temperature -15°C, other conditions are the same as in Table 1. The results obtained under these conditions are shown in Table 4.

From the results of Table 4 to
02 with extremely high separation characteristics under low temperature and low pressure conditions of a-X
The headline is that it is concentration dependent. That is.

■ Ca-Na at least up to the 02 concentration range of around 50%
It can be seen from the comparison of the 02 concentration in the desorbed gas that there is no significant difference in N2 selectivity between -A and Na-X.

■ At least up to the 02 concentration region of around 50%, considering the results in (■), 0a-Na-A adsorbs about 20% more N2 than Na-X, so this is extremely important in terms of adsorption tower design. It will be advantageous.

■ In the 02 concentration range exceeding 50%, r Na XO has considerably higher N2 selectivity than 0a-Na-A.

Product 02 is excellent in both concentration and mass balance.

It can be summarized as follows.

Considering this from the economical point of view of the adsorption tower, the upstream side has Ca-
This further adds to the validity of the method of installing Na-A and Na-X on the downstream side.

Here, when comparing Ca-Na-A and Na-X.

■ Ca-Na-A is used in larger quantities than Na-X because the requirements for θ are larger, and the mass production effect is greater.

(2) Hydrothermal synthesis of Q a-N a-A is easier than that of Na-xK.

For these reasons, 0a-Na-A, Na-X, and l:'fl are also supplied at about 30% cheaper prices. However, using an aluminum source such as sodium aluminate as an additive increases the price by about 10%.

For this reason, the filling modes shown in Table 2 are evaluated based on the price of the adsorbent.

Na-X', 1/2Ca-Na A+1/2Na-
x-A1203=1,'0.9.

It is advantageous to be able to reduce the cost of the adsorbent while maintaining the same properties.

Taking these effects into consideration, the operating conditions listed in Table 1 are as follows: from Ye to Q2 concentration of 50%, He, Ca-Na-A on the upstream side in the adsorption process of the adsorption tower, and N on the downstream side.
The main improvements of the separation method filled with a-X-A 1 203 over the conventional method filled with Qa Na A alone or Na-X alone will be explained.

Figure 2 shows the results for product 02 concentration 92%, adsorption pressure 12 ata + desorption pressure 0.2 ata + cycle time 4 minutes 10 seconds, and temperature 25 to -50°C, where the horizontal axis is the adsorption temperature and the vertical axis is the SV. Show value. Product 02 with Sv value of 92%
When recovering the inlet air amount [Nd-air/h], the adsorption tower capacity of the entire device [,? ).

In the diagram, ◎ indicates 2 1/2 Ca-Na-All/2Na of the present invention.
In the case of X-A1203, the 0 mark indicates the case of Na-X, and the * mark indicates the case of Ca-Na-.A.

There is no big difference among the eight at room temperature, but as the temperature decreases, 1/20a-Na-A + 1/2Na X Al203
However, it also shows a 3V value that is about 10% larger than the other two. (It is needless to say that the Sv value is a factor that simply indicates the amount of air processed and needs to be evaluated in conjunction with the 02 recovery rate and the 02 production amount.) In Figure 3, the horizontal axis represents the temperature; The vertical axis shows the product 02 recovery rate.

In addition, the recovery rate R (%) of product 02 is.

Define it as .

The operating conditions are the same as in FIG. Symbols in the diagram ◎,
The marks ○ and ・ are also the same as in Figure 2.

In Figure 8, as the temperature decreases, the product recovery rate decreases for 0a-Na2L-A, but increases for Na-X! This is a reconfirmation of % Gansho-58-54626, but what should be noted here is 1/20 a-N a-A+
1/2Na-XAl203 is several % more than Na-X
This shows a large 02 recovery rate. Considering the results in Figure 2, l/20a-Na"A+1/2Na
-X-A1203 maintains a product 02 recovery rate that is several percent higher than Na -X, and the results are -aO~+15
℃ range. )The above is evaluated as the amount of adsorbent required to produce a unit capacity of 02, and if Na-X is 1, then N
a-X: 1/2Ca-Np, -A+1/2Na-X
-A7203 = 1: 0.759. Compared to the case of using Na-X alone, the cost of the adsorbent is reduced by nearly 25%.

Next, 1/20a-Na-A+1/2N by adsorption pressure
In order to investigate the characteristics of a did.

The results are shown in FIG. In FIG. 4, the horizontal axis shows the adsorption pressure, and the vertical axis shows the product 02 recovery rate R (%).

◎ in the figure is l/2Ca-Na-A+1/2Na-X Al
The case of 203 is shown, and ◯ shows the case of Nu-X.

As is clear from FIG. 4, the product 02 recovery rate is almost constant up to aa'ta, but it decreases above that point. This is because the increase in the amount of N2 adsorption as the pressure increases slows down, but the increase in the amount of +02 adsorption does not slow down much.
It seems that the decrease in selectivity and the increase in the amount of air remaining in the column due to pressure increase are effective. The properties are not much different from Na-X.

Next, l/2 CII-N a-A+ 1 due to desorption pressure
/2N In order to investigate the characteristics of a-X-A1203, the other operating conditions were the same as in Figure 4, and the adsorption pressure was 1.2.
aLa and desorption pressure only from l Torr to 0.5at
Changed up to a.

In FIG. 5, the horizontal axis shows the desorption pressure, and the vertical axis shows the product 02 recovery rate. Also, the symbols in the figure are the same as in FIG. 4.

As is clear from FIG. 5, the product 02 recovery rate significantly increases as the desorption pressure decreases.

This is because in the pressure swing method, while the desorption pressure decreases, the amount of N2 adsorption increases significantly.

Since the amount of 02 adsorption does not change much, it is thought that this is because the lower the pressure is, the higher the N2 selectivity is.

(This was discovered by measuring the amount of desorbed gas and its 02 concentration when collecting data in Figure 5. l/20a-Na
-A+1/2Na-x-A7. , some of the results for o3 are shown in Table 5.

Table 5 [ Month ( Month ( Month ( Figure 6 is based on the material balance in Figure 5, 02 production volume 1.
(LNr in large capacity equipment of 10(l Non/h or more)
The power consumption required to manufacture 02 of d is calculated. The symbols in the figure are the same as in FIG. In this region, the efficiency of both the inlet blower and the detachable vacuum pump is 80 because the transmission loss between the motor and rotating equipment can be ignored.
Exceeds %. If 02 is manufactured with such a power configuration, in this region 0045 to 0.55 ata,
The power consumption is less than 0.6 Kwh/Nhf 02, and the conventional pressure swing method (e.g. Ca-N as adsorbent)
Using a-A, adsorption pressure 4ama, desorption pressure 0.1
ata r r! Power consumption at JL arrival temperature 25℃ 065
~ I Kwh/N resistance -02).

Especially near the minimum value (near 01 to 0.25 aha),
Power consumption is 0. a 5 Kwh/Nm-02, which is significantly lower than the cryogenic separation method.

Figure 7 is under the same operating conditions as Figures 2 and 8.

This figure shows the change in product 02 recovery rate when the desorption pressure is set to 0.2 ata and the purge gas amount ratio is changed.

What is the regeneration purge gas amount ratio P/F?

Defined by .

The symbols in the figure are the same as in FIG. 6.

As can be seen from Figure 7, 1/2Ca-Na-A+1/2N
It can be seen that for both a-X-A/203 and Na-X, there is no need to consume part of the product 02 for regeneration purge.

As explained in detail above, the present invention requires less power consumption and adsorbent amount than conventional adsorbent methods, and is a method of using inexpensive adsorbents that is very useful industrially for producing oxygen from mixed gases. This paper proposes a manufacturing method.

[Brief explanation of drawings]

Figure 1 is an illustration of an air separation device used to carry out the oxygen production method of the present invention, Figure 2 is a graph showing the relationship between temperature and SV value, and Figure 8 is a graph showing the relationship between temperature and product 02 recovery rate. Figure 4 is a graph showing the relationship between adsorption pressure and product 02 recovery rate, Figure 5 is a graph showing the relationship between desorption pressure and product 02 recovery rate, and Figure 6 is a graph showing the relationship between desorption pressure and product 02 recovery rate. Back
It is a graph showing the relationship between the power consumption required to manufacture 02/h and the power consumption. 2... Compressor, 4... Dehumidification/dehumidification CO2 tower, 8... Adsorption tower. 13... Product 02 tank, 18... Vacuum pump, 2
0...Compression refrigerator. 1st leap Figure 2nd 1st C0C) Ben Hiroshi C'C) 0 no observation pressure (afo) Desalination pressure (ata) Figure 6 8th stage Port pressure (afan Figure 7 PIF ratio (-) Procedure correction Document (method) Indication of the June 1985 incident 1985 Patent Application No. 236923 Name of the invention CaNa A, Incident of a person amending a method for producing oxygen using a N2 adsorption tower using Na-X-Al2O3 Relationship Patent applicant address 158-1115 Marunouchi, T+N-ku, Tokyo Name (620) Mitsubishi Heavy Industries, Ltd. kidnapping agent Date of amendment order (shipment date) May 28, 1975 El -+, - Specification No. 2
Insert the following sentence next to "Graph 1 Shown" on the 5th line of page 1.

Claims (1)

[Claims] In at least two adsorption towers filled with N2 adsorbent,
At a temperature below room temperature, a gas mixture containing oxygen and nitrogen as main components is caused to flow into an adsorption tower at a pressure above atmospheric pressure and below 8 at'a to selectively adsorb available nitrogen into the mixed gas, and the adsorption tower High purity oxygen or oxygen enriched gas flows out from the outlet;
On the other hand, the adsorption tower that adsorbed nitrogen was
・When adsorbing and separating N2 from a mixed gas under low-temperature, low-pressure conditions that is regenerated by reducing the pressure to 58 O a-N a-A, characterized in that it is filled with alumina-added Na-X type zeolite;
A method for producing oxygen using a N2 adsorption tower using Na-X-A1203.