JP2010012367A - Oxygen-producing method and oxygen-producing apparatus according to pressure swing adsorption method that employs oxygen-selective adsorbent - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oxygen-producing method and an oxygen-producing apparatus according to a pressure swing adsorption method that employs an oxygen-selective adsorbent. <P>SOLUTION: The oxygen-producing method and the oxygen-producing apparatus for practicing the method employ a Perovskite-type oxide i.e., BaFeO<SB>3-δ</SB>with Y or In doped therein as its adsorbent, in which oxygen-producing process and oxygen-producing apparatus, oxygen is adsorbed by the adsorbent at an adsorption temperature of 200 to 350°C which is the lowest adsorption temperature for a Perovskite-type oxide, heat is recovered from high-temperature nitrogen upon causing nitrogen to flow through the adsorbent, and heat is also recovered from high temperature oxygen upon desorbing oxygen from the adsorbent. By virtue of the highly efficient heat recovery, electricity consumption can be minimized and oxygen can economically be produced. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method and apparatus for separating oxygen and nitrogen using an oxygen selective adsorbent for separating, removing or concentrating oxygen in the air.

The biggest problem in the separation, removal, or concentration process of oxygen from air is that the raw material cost is usually required for air, and there is no raw material cost. (A) Equipment provided for separation and concentration Cost (b) Various power costs required to operate the device (c) When a separation medium is required, it depends on its price and replenishment cost.

  Regarding the separation, concentration, and removal of oxygen, from the standpoint of power consumption among the various power costs required to operate the equipment, conventionally, the higher the purity of oxygen to be produced, the more cryogenic cooling of the air is. The cryogenic separation process is used because it enables energy-saving and efficient oxygen production. On the other hand, when producing oxygen with relatively low purity, pressure swing adsorption (PSA) using molecular sieves as adsorbent is used. ) The process has been adopted because it allows energy efficient and efficient oxygen production.

  The PSA process has become widespread in a wide range of fields in recent years because the apparatus used is more compact than the cryogenic separation process, and can be easily installed and is relatively easy to maintain. However, the PSA process has a lower product recovery rate than the cryogenic separation process, which is disadvantageous in terms of production cost. Therefore, in order to further spread the PSA process, it is desired in the art to find an adsorbent with high adsorption performance.

The present inventors have, for structural formula _{La x Sr 1-x Co y} Fe 1-y O 3-δ oxygen-selective adsorbent performance obtained by doping various metals in cubic perovskite oxide represented by It examined (for example, refer patent document 1). The reversible oxygen adsorption amount q _rev of LSCF1991 (La: Sr: Co: Fe = 1: 9: 9: 1) at an adsorption temperature of 400 ° C. is 9 ml N / g, which is the most oxygen adsorption type of existing oxygen selective adsorbents. It becomes 30 times the reversible oxygen adsorption amount of 25 vol. C and 21 vol% of the large amount of activated carbon-based oxygen selective adsorbent MSC-3A. Further, when MSC-3A is used as an oxygen-selective adsorbent from an oxygen-nitrogen binary system, the oxygen separation coefficient α (the same oxygen, the oxygen at the nitrogen partial pressure, the nitrogen adsorption amount ratio (qo ₂ / Co ₂ ) / (Qn ₂ / Cn ₂ )) is about 3 and performance degradation due to co-adsorption of nitrogen is inevitable, but Y and In-doped BaFeO _3-δ hardly adsorbs nitrogen, so α> 100 or more It has been found that it exhibits complete oxygen adsorptivity, and has been disclosed to be an excellent adsorbent for PSA.

In the method of separating oxygen and air from air by PSA using perovskite type oxide that adsorbs oxygen selectively as an adsorbent under high temperature conditions, the power unit for oxygen production is the smallest value in the current oxygen production method 0.2 kWh / m ³ N is expected to be lower than 0.31 kWh / m ³ N of the cryogenic separation method.

  However, when a perovskite type oxygen selective adsorbent is actually used, this adsorbent has conventionally had a tendency to increase the amount of reversible adsorption of oxygen at a temperature of about 300 ° C. or higher. Must be used, effective heat transfer to the adsorbent, recovery of oxygen after separation, heat from nitrogen, heat resistance to change the flow path at high temperature, oxygen resistant valve, dew point from raw air -40 ° C It is necessary to solve the following dehumidification issues.

For this reason, if the apparatus is configured only with the currently known knowledge, a very large burden is caused in terms of peripheral technologies other than oxygen / nitrogen separation from air, and it is difficult to achieve the above-mentioned power consumption rate and it is stable. Oxygen / nitrogen separation is also difficult.
Japanese Unexamined Patent Publication No. 2005-079441

  The present invention improves the above-described drawbacks of the perovskite type oxygen selective adsorbent, maximizes the oxygen adsorption capacity of the oxygen selective type adsorbent at a relatively low temperature, and allows the oxygen selective adsorbent to be used at a relatively low temperature. Oxygen / nitrogen that provides an oxygen-selective adsorbent with excellent oxygen selectivity by efficiently utilizing the heat it has, and that can easily produce oxygen with a small amount of power unit using the adsorbent A process and an apparatus for separating the components are provided.

  As a result of intensive studies to achieve the above-mentioned problems, the present inventors have found that a specific perovskite oxygen selective adsorbent surprisingly absorbs oxygen by reversible adsorption at a relatively low temperature of 200 to 350 ° C. It was found that a large amount was adsorbed and the adsorption rate was high, and that oxygen was easily adsorbed and desorbed by simply increasing or decreasing the pressure. In addition, by efficiently utilizing the heat of the relatively high temperature product oxygen and nitrogen, it is possible to reduce the oxygen production power intensity and easily produce high-purity oxygen with a very low power intensity. As a result, the present invention has been made.

In the present invention, the perovskite oxide includes an oxide having a cubic, hexagonal and orthorhombic perovskite oxide structure, an oxide having a brown mirrorlite structure, and an oxide having a 2H—BaNiO ₃ structure. Collectively say.

Thus, according to the present invention, the following inventions 1 to 11 are provided:
1. Perovskite-type oxidation in which BaFeO _3-δ used as a heat storage material, mixed gas-nitrogen heat exchanger, mixed gas heater, or high temperature oxygen selective adsorbent is doped with Y or In. The mixture gas is supplied to the adsorption tower filled with the material under a relatively high pressure condition, the mixed gas and the heat storage material are brought into contact with each other to raise the temperature of the mixed gas, and then the mixed gas is mixed with a mixed gas-nitrogen heat exchanger at the tower outlet nitrogen. The temperature is raised by exchanging heat with the gas, and then the mixed gas is brought into contact with the mixed gas heater to set the adsorption temperature, and then brought into contact with the oxygen selective adsorbent to adsorb oxygen and separated from nitrogen. Pressure-adsorption method (PSA) of oxygen and nitrogen, in which oxygen-selective adsorbent that adsorbs oxygen is introduced to a relatively low pressure condition, oxygen is desorbed, and heat is recovered from high-temperature oxygen by contact with oxygen and a heat storage material Separation method by.
2. Oxygen-adsorbed adsorbent that has adsorbed oxygen is mixed with oxygen-selective adsorbent, which is brought into contact with oxygen-selective adsorbent to adsorb oxygen under relative high-pressure conditions and separate from nitrogen. 2. The method for separating oxygen and nitrogen by PSA as described in 1 above, wherein oxygen is further desorbed by purging at a atmospheric pressure or under reduced pressure as a purge gas.
3. A moisture adsorbent is installed upstream of the heat storage material in the flow direction of the mixed gas, and moisture is adsorbed under a relatively high pressure condition to prepare a dry mixed gas, which is then supplied to the oxygen selective adsorbent. The high-temperature oxygen adsorbed by oxygen and brought into contact with the heat storage material by contacting the high-temperature oxygen desorbed under a relative reduced pressure condition, recovering heat from the oxygen, and desorbing the adsorbed moisture from the concentrated oxygen lowered, Of oxygen and nitrogen by PSA.
4). The adsorption tower after completion of the adsorption process and the adsorption tower after completion of the desorption process are connected at the rear of the tower, and oxygen remaining in the adsorption tower after completion of the adsorption process is supplied to the adsorption tower after completion of the desorption process and recovered. The method for separating oxygen and nitrogen according to any one of 1 to 3 by PSA.
5). A pressure swing adsorption device for supplying a mixed gas mainly composed of oxygen and nitrogen under a relatively high pressure condition to separate oxygen and nitrogen, in the flow direction of the mixed gas,
(1) A heat storage material for recovering heat from the adsorbed high-temperature oxygen and imparting the recovered heat to the mixed gas;
(2) The mixed gas that has passed through the separated heat storage material flows on one side of the heat exchanger, and the high-temperature nitrogen product gas that flows out of the packed tower flows on the other side of the heat exchanger and is mixed from the high-temperature nitrogen product gas. A mixed gas-nitrogen heat exchanger that recovers heat to the gas and raises the temperature of the mixed gas flowing out of the heat exchanger,
(3) A heater for heating the mixed gas heated through a heat exchanger with nitrogen to an adsorption temperature,
(4) 2 parallel packed towers equipped with an adsorbent bed that selectively adsorbs oxygen by allowing nitrogen to pass through after selectively adsorbing oxygen through the mixed gas-nitrogen heat exchanger. A pressure swing adsorption device that includes more than a tower and separates oxygen and nitrogen contained in a heat insulation chamber to keep the packed tower warm.
6). As the oxygen selective adsorbent, a perovskite oxide in which BaFeO _3-δ is doped with Y in a Y / Fe molar ratio of 0.001 or more or In is doped in In / Fe with a molar ratio of 0.002 or more is used. The method for separating oxygen and nitrogen by PSA according to any one of claims 1 to 5, which is carried out at an adsorption temperature of ~ 350 ° C.

  Perovskite-type oxide is used at the lowest temperature of 200 to 350 ° C, oxygen is adsorbed in a large amount by reversible adsorption, and the reversible adsorption rate is large, making it easy to adsorb and desorb oxygen by simply increasing or decreasing the pressure. It can be carried out. Moreover, by efficiently utilizing the heat of the high-temperature product oxygen and nitrogen, the oxygen production power intensity can be reduced, and high-purity oxygen can be easily produced with an extremely low power intensity.

  Furthermore, by installing a moisture adsorbent on the front part of the heat storage material, it is possible to simultaneously remove moisture in the raw material air in the separation of oxygen and nitrogen. Can be easily manufactured.

  Install a unit with a high heat recovery rate, an automatic valve that is difficult to operate in the high temperature part, a current blower, a vacuum pump, etc. in the low temperature part, and highly efficient and reliable oxygen from the air. A method for separating nitrogen can be provided.

EMBODIMENT OF THE INVENTION Below, the form for implementing this invention is demonstrated, referring an accompanying drawing.
An example of an apparatus for carrying out the invention is shown in FIGS.

  1 and 2 show a pressure swing adsorption device for separating oxygen and nitrogen for carrying out the present invention. The pressure swing adsorption device is configured such that packed towers 4 a and 4 b are accommodated in a heat insulation chamber 24.

The packed towers 4a and 4b are sequentially arranged in the flow direction of the mixed gas.
(1) Heat storage materials 19a, 19b for recovering heat from the adsorbed high-temperature oxygen and applying the recovered heat to the mixed gas
(2) The mixed gas that has passed through the heat storage material flows on one side of the heat exchanger, and the high-temperature nitrogen product gas that flows out of the packed tower flows on the other side of the heat exchanger. A mixed gas-nitrogen heat exchanger 20a, b, which raises the temperature of the mixed gas flowing out of the heat exchanger by recovering heat
(3) Heaters 21a, 21b for heating the mixed gas heated through the heat exchanger with nitrogen to an adsorption temperature,
(4) Adsorbent beds 5a and 5b that selectively adsorb oxygen by selectively adsorbing oxygen through a mixed gas that has passed through a mixed gas-nitrogen heat exchanger.
Is housed inside.

  As the heat storage materials 19a and 19b, any commercially available materials may be used, but it is preferable to use a material that minimizes the pressure loss when the gas passes and has a large heat storage amount. An example of such a heat storage material is a stainless steel heat storage material honeycomb having a liner pitch of about 2 mm and a flat plate thickness of about 0.5 mm.

  As the mixed gas-nitrogen heat exchangers 20a and 20b, any commercially available one may be used. However, it is preferable to use one having a minimum pressure loss when the gas passes and a high heat exchange rate. preferable. An example of such a heat exchanger is a group of tube tubes with fins through which high-temperature nitrogen flows. Since the mixed gas flowing outside flows through the finned tube tube group, the area in contact with the high temperature increases, and the heat exchange rate increases.

  The heaters 21a and 21b are for raising the temperature of the mixed gas to a temperature at which the adsorbent exhibits optimum adsorption ability, and any commercially available one may be used, but the gas passes through. It is preferable to use a material that minimizes the pressure loss and has a high heat exchange rate. An example of such a heater is a finned tube into which an electric heater is inserted. It is preferable to install a thermocouple in the adsorbent bed and control the heat from the heater according to the temperature detected by the thermocouple so as to maintain a set temperature.

  The adsorbent beds 5a and 5b used in the present invention adsorb a large amount of oxygen by reversible adsorption at a relatively high temperature and have a high reversible adsorption rate. It is preferable to use a perovskite oxide as such an adsorbent.

An adsorbent suitable for use in the present invention is a perovskite oxide in which In is doped with a structural formula of BaFe _y O _3-z in an In / Fe molar ratio of 0.002 or more, and is disclosed in Patent Document 1. BaFeO _3-δ doped with In can be produced by the production method. (The preparation method is described in Example Synthesis Method 1.)

Also, a perovskite oxide of Y in the formula BaFeO _3-δ-doped 0.02 or more Y / Fe molar ratio, doped with Y in the production method disclosed in Patent Document 1, BaFeO _3-δ Can be manufactured. (The preparation method is described in Example Synthesis Method 2.)

  FIG. 1 shows a first embodiment of the present invention using air as a mixed gas, and Table 1 shows a sequence.

First step [packing tower 4a, packed tower 4b-pressure equalizing step between towers]
In FIG. 1, when the packed column 4a with an adsorption pressure of 100 to 200 kPa after completion of the adsorption step and the packed column 4b with a regeneration pressure of 2 to 20 kPa after completion of the regeneration step are opened, the valves 8a and 6a are opened behind the packed column 4a. The nitrogen concentration remaining in the packed column 4b moves to the packed column 4b, and the oxygen concentration in the packed column 4a, which shifts to the desorption step, increases significantly. In addition, since the pressure in the packed tower 4a and packed tower 4b is equalized, smooth pressure increase for the adsorption process and smooth pressure decrease for the pressure reduction process proceed.

Second step [packed tower 4a-pressurizing process, packed tower 4b-depressurizing process]
When the packed tower 4a increased in pressure equalization and the product tank 12 are connected by a valve 8b, product nitrogen is adsorbed from the rear of the packed tower 4a through the flow path 17a, the air-nitrogen heat exchanger 20a, and the flow path 22a. The adsorption pressure of the packed tower 4a is increased to a place close to 100 to 200 kPA. When the packed tower 4b, which has been decompressed to about equal pressure, is connected to a vacuum pump through a valve 9b, the pressure in the tower is reduced and adsorbed oxygen is desorbed. At this time, as described above, the heat storage material is in contact with the honeycomb 19b, the temperature of the heat storage material is increased, the desorption oxygen is decreased, and the heat of the desorption oxygen is efficiently recovered.

Third step [packed tower 4a-adsorption process, packed tower 4b-regeneration process]
Dry air is supplied from the channel 1 to the oxygen selective adsorbent packed tower 4a through the blower 2 and the valve 3a. The packed tower 4a is sequentially filled with a heat storage material honeycomb 19a, an air-nitrogen heat exchanger 20a, an air heater 21a, and an oxygen selective adsorbent honeycomb 5a in the flow direction of the supplied dry air. The frontmost part of the packed tower 4a is filled with a heat storage material honeycomb 19a. The temperature of the heat storage material honeycomb 19a is increased by contact with air, and the heat storage material honeycomb 19a is cooled to recover the heat quantity of the desorbed oxygen. Raise the temperature. Next, the heated air is brought into contact with the mixed gas-nitrogen heat exchanger 20a through which high-temperature nitrogen flows, the air is heated, and the nitrogen in the tube group 20a is cooled to flow through the nitrogen. The amount of heat is recovered and the temperature of the air rises. If the adsorbent does not reach a suitable adsorption temperature, the air heater 21a comes into contact with air and reaches a suitable adsorption temperature. The air that has passed through the heater 21a and then contacted with the oxygen-selective adsorbent honeycomb floor 5a adsorbs oxygen, and the nitrogen that has passed through the bed then flows out from the back of the packed tower 4a. Since the flowing out nitrogen is high at the adsorbent bed set temperature, it is supplied from the flow path 22a to the air-nitrogen heat exchanger 20a, and is brought into contact with the air being heated to recover heat. Here, the oxygen adsorption zone of the oxygen selective adsorbent honeycomb 5a moves from the front of the tower to the rear, and the supply of air is stopped immediately before oxygen flows from the rear of the packed tower 4a. The packed tower 4b is in a state in which the oxygen adsorption zone has moved to the rear of the tower, and the product nitrogen supplied from the flow path 17a is supplied from the rear of the tower through the pressure reducing valve 18 and the valve 8b, and the oxygen selective adsorbent honeycomb. Oxygen is desorbed by countercurrent contact with 5b. The desorbed oxygen passes through the air heater 21b and the air-nitrogen heat exchanger (so far, heat recovery of the desorbed oxygen is hardly measured) and comes into contact with the heat storage material honeycomb 19b, and the heat storage material is heated. The desorbed oxygen is cooled and the heat of the desorbed oxygen is recovered efficiently. The desorbed oxygen concentration is concentrated to about 50 vol% or more.

  Since this oxygen-nitrogen separation is operated at a high temperature of 200 to 800 ° C., the oxygen-selective adsorbent packed towers 4a and 4b need to be maintained at the temperature shown on the left. 24 to minimize heat loss.

  Here, the same operations as those in the first to third steps are changed in the packed tower 4a and the packed tower 4b, and the operations in the fourth to sixth steps are performed.

  Next, a second embodiment of the present invention using air as a mixed gas will be described.

  In the first embodiment, oxygen recovery was performed by the inter-column pressure-pressure-adsorption-adsorption in the “adsorption step”, and the column pressure-reduction-counter-current purge was performed in the “regeneration step”. Further, since product nitrogen is used as a purge gas in the countercurrent purge, and nitrogen remains in the adsorption tower after completion of the adsorption process, it is difficult to recover high concentration oxygen of about 99 vol%. As a method of removing nitrogen from the recovered oxygen, when the oxygen recovered from the front of the tower is purged into the adsorption tower after completion of the adsorption process in the “regeneration process”, the nitrogen remaining in the adsorption tower is replaced with oxygen, and the rear of the tower Nitrogen flows from the catalyst, and the oxygen concentration in the desorption process increases remarkably.

  FIG. 2 shows the flow sheet of the apparatus at this time, and Table 2 shows the apparatus flow sheet. In the figure, the same reference numerals as those in FIG. 1 denote the same components. In FIG. 2, when the vacuum pump 11 is used as a blower from the gas tank 26 to the packed tower 4 b after the adsorption step and the valves 27, 28, 3 b, 6 b are opened, nitrogen remaining in the tower flows and flows from the flow path 29. It is returned to the flow path 1 and collected.

This operation is called a cocurrent purge. When the desorption gas amount is G2 (m ³ N / h) and the cocurrent purge gas flow rate is G4 (m ³ N / h), the cocurrent purge rate K is
K = G4 / G2
Define in. The desorption gas amount G3 is G3 = G2-G4.
Hereinafter, the present invention will be described specifically by way of examples, but these are not intended to limit the present invention.

Synthesis Example 1 Synthesis of InFe _- doped BaFeO _3-δ with an In / Fe ratio of 0.02 Powders of barium nitrate, indium nitrate and iron nitrate were mixed at a molar ratio of 100: 98: 2 and dissolved in pure water. After heating to 350 ° C. in air and evaporating to dryness, calcining in air at 800 ° C. for 2 hours and further firing at 1200 ° C. for 6 hours to obtain BaFe _0.98 In _0.02 O ₃ the _-δ perovskite oxide powder was prepared. It was confirmed by X-ray diffraction analysis (XRD) using CuKα rays that the oxide powder had a perovskite structure. A perovskite oxide raw material cake was prepared by adding 4 g of kaolin, 4 g of cellulose, and 2 g of pure water to 16 g of this powder, and a load of 100 kg was applied to an extruder to obtain pellets having a diameter of 1.6 mmφ. The pellets were heated to 800 ° C. at 200 ° C./hour in the air and held for 1 hour to prepare activated perovskite oxide pellets.

Example 1
As the oxygen-selective adsorbent honeycombs 5a and 5b of the packed towers 4a and 4b, the InFe _- doped BaFeO _3-δ having an In / Fe ratio of 0.02 prepared in Synthesis Example 1 is used. An embodiment was implemented. PSA operating conditions and separation performance in separation of oxygen and nitrogen from air (product oxygen concentration, power intensity during production of oxygen (kWh / m ³ N—O ₂ ), oxygen adsorption load (m ³ N—O ₂ / h / ton) was evaluated.

First step [packing tower 4a, packed tower 4b-pressure equalizing step between towers]
The adsorption pressure of the packed tower 4a after the adsorption process was 120 kPa, and the regeneration pressure after the regeneration process was 5 kPa. The pressure inside the packed tower 4a and packed tower 4b after pressure equalization was 60 kPa.

Second step [packed tower 4a-pressurizing process, packed tower 4b-depressurizing process]
When the packed column 4a and the product tank 12 which are pressurized to about 60 kPa are connected by the valve 8b, the product nitrogen is heated up to the adsorption temperature from the back of the packed column 4a and supplied, and the adsorption pressure of the packed column 4a is 120 kPa. Boosted to a close range. When the packed tower 4b decompressed to about 60 kPa was connected to a vacuum pump through the valve 9b, the pressure in the tower was reduced to 10 kPa or less and the adsorbed oxygen was desorbed.

Third step [packed tower 4a-adsorption process, packed tower 4b-regeneration process]
100 m ³ N / h of dry air was supplied from the channel 1 to the oxygen selective adsorbent packed column 4a. The packed tower 4a has a diameter of 30 cm and a height of 150 cm. This is filled with a 20-liter heat storage material honeycomb 19a, an air-nitrogen heat exchanger 20a, an air heater 21a, and an 80-liter oxygen selective adsorbent honeycomb 5a. (The superficial velocity is 0.5 m / sec and the adsorption load is 650 m ³ N / h / ton.) In the forefront portion of the packed tower 4a, a stainless steel heat storage with a liner pitch of 2 mm and a flat plate thickness of 0.5 mm is provided. The material honeycomb 19a is filled in a shape with a diameter of 30 cm and a layer height of 20 cm, the temperature of the air rises by contact with air, the temperature of the heat storage material honeycomb 19a drops and the amount of heat of desorbed oxygen is recovered, and the temperature of the air rises To do. Next, the inside is brought into contact with the finned tube group 20a through which high-temperature nitrogen flows, the temperature of the air rises, the temperature of the nitrogen in the group 20a drops, and the amount of heat of the flowing nitrogen is recovered to raise the temperature of the air. To do. This raises the temperature up to 90% of the adsorption tower set temperature of 250 ° C., 225 ° C., but does not reach the highest temperature of 250 ° C., so the finned tube 21a with the electric heater inserted is in contact with the air, Reach 250 ° C. Oxygen in the air in contact with the 80 liter oxygen selective adsorbent honeycomb 5 is adsorbed, and nitrogen flows from the rear of the tower. Since the flowing nitrogen is at a high temperature of 250 ° C., it is supplied from the flow path 22a to the air-nitrogen heat exchanger 20a and comes into contact with the air being heated to recover heat. Here, the oxygen adsorption zone of the oxygen selective adsorbent honeycomb 5a moves from the front of the tower to the rear, and the supply of air is stopped immediately before oxygen flows from the rear of the packed tower 4a. The packed tower 4b is in a state in which the oxygen adsorption zone has moved to the rear of the tower, and 4 m ³ N / h of product nitrogen supplied from the flow path 17 is supplied through the pressure reducing valve 18 and the valve 8b, and the oxygen selective adsorbent honeycomb 5b. Oxygen is desorbed by countercurrent contact with. The desorbed oxygen passes through the air heater 21b and the air-nitrogen heat exchanger (so far, heat recovery of the desorbed oxygen is hardly measured) and comes into contact with the heat storage material honeycomb 19b, and the heat storage material is heated. The desorbed oxygen is cooled and the heat of the desorbed oxygen is recovered efficiently. The desorbed oxygen concentration is concentrated to 50 vol% or more.

  Since this oxygen-nitrogen separation is operated at a high temperature of 200 to 350 ° C., it is necessary to keep the oxygen selective adsorbent packed towers 4a and 4b at the temperature described on the left. 24 to minimize heat loss.

  Here, the same operation as the first to third steps is performed in the fourth to sixth steps by changing the packed tower 4a and the packed tower 4b.

Table 3 shows separation performance when the adsorption pressure, regeneration pressure, cycle time, and adsorption temperature are changed (product oxygen concentration, power intensity during oxygen production (kWh / m ³ N—O ₂ ), oxygen adsorption load (m ³ N—O ₂ / h / ton)).

In Table 3, Run 1, 2, 3, and 4 are set at a regeneration pressure of 5 kPa, a cycle time of 2 minutes, an adsorption temperature of 523 K (250 ° C.), and the separation performance when changing the adsorption pressure to 110 to 200 kPa (product oxygen concentration, oxygen Electric power consumption at the time of manufacture (kWh / m ³ N—O ₂ ), oxygen adsorption load (m ³ N—O ₂ / h / ton) Product oxygen concentration shows a high value of 96 vol%, increasing the pressure As a result, the oxygen adsorption load increases and the power consumption rate also rises, so a low adsorption pressure should be adopted to keep the power consumption rate low, and a high adsorption rate to reduce the amount of adsorbent used. It turns out that pressure should be adopted.

Runs 5 and 6 are set to an adsorption pressure of 120 kPa, a cycle time of 2 minutes, an adsorption temperature of 523 K (250 ° C.), and a separation performance when the regeneration pressure is changed to 5 to 15 kPa (product oxygen concentration, unit of electric power during oxygen production ( kWh / m ³ N—O ₂ ) and oxygen adsorption load (m ³ N—O ₂ / h / ton) As the regeneration pressure increases, the product oxygen concentration, oxygen adsorption load, and power intensity also decrease. Therefore, a high regeneration pressure should be adopted to keep the power consumption rate low, but a low regeneration pressure should be adopted to reduce the amount of adsorbent used and keep the product oxygen concentration high. I understand.

Runs 7 and 8 are set to adsorption pressure of 120 kPa, regeneration pressure of 5 kPa, adsorption temperature of 523 K (250 ° C.), and separation performance when changing the cycle time to 3 to 5 minutes (product oxygen concentration, power intensity during oxygen production ( kWh / m ³ N—O ₂ ) and oxygen adsorption load (m ³ N—O ₂ / h / ton) Although the product oxygen concentration and the power consumption rate do not change as the cycle time increases, the oxygen adsorption load decreases. For this reason, it can be seen that the cycle time should be shortened in order to reduce the amount of adsorbent used, provided that the oxygen adsorption performance of this apparatus is defined by the oxygen desorption rate, and the In / Fe ratio is 0.02. In the case of BaFeO _3-δ doped with In, the cycle time is considered to be about 2 minutes (desorption time is about 1 minute).

Runs 9 and 10 are set to an adsorption pressure of 120 kPa, a regeneration pressure of 5 kPa, and a cycle time of 2 minutes, and the separation performance when the adsorption temperature is changed to 473 to 673 K (product oxygen concentration, unit of electric power during oxygen production (kWh / m ³⁾ _N-O 2), oxygen adsorption load _{^{(m 3 N-O 2 /}} h / ton). after the highest concentration in the product oxygen concentration with increasing adsorption temperature rises 523K, product oxygen concentration decreases As a result, the power consumption increases and the oxygen adsorption load decreases, so it is clear that the operation at 473 to 623 K (200 to 350 ° C.) is desirable for this PSA. A high-temperature material such as Ni or Cr is required as a constituent material of the apparatus, and the economy has been lowered. However, in this apparatus, a normal heat-resistant material such as stainless steel can be used. Also heat recovery more than 80% for the heat recovery unit can be easily achieved.

Run 11 is set to an adsorption pressure of 120 kPa, a regeneration pressure of 5 kPa, a cycle time of 2 minutes, an adsorption temperature of 673 K, and the separation performance when the pressure equalization between the columns is not performed (product oxygen concentration, power intensity during oxygen production (kWh / m ³ N—O ₂ ) and oxygen adsorption load (m ³ N—O ₂ / h / ton) By not performing the inter-tower pressure equalization, the power intensity increases and the oxygen adsorption load also increases. Therefore, it can be seen that, in this PSA, the basic unit of power between the towers can basically reduce the electric power consumption.

Example 2
First embodiment of the present invention using InFe _- doped BaFeO _3-δ having an In / Fe ratio of 0.02 prepared in Synthesis Example 1 as the oxygen-selective adsorbent honeycombs 5a and b of the packed towers 4a and b Carried out.
Table 4 shows the relationship between the cocurrent purge rate and the product oxygen concentration.

  As the cocurrent purge rate increases, the product oxygen concentration rises, reaching an oxygen concentration of 99% at a cocurrent purge rate of 70%, and reaching an oxygen concentration of 99.5% at a cocurrent purge rate of 80%.

Synthesis Example 2 Synthesis method of BaFeO _3-δ doped with Y having a Y / Fe ratio of 0.01.
Powders of barium nitrate, yttrium nitrate and iron nitrate were mixed at a molar ratio of 100: 99: 1, dissolved in pure water, evaporated to dryness at 350 ° C. in air, and then 800 in air. Ba2 _0.99 Y _0.01 O _3-δ perovskite type oxide powder was prepared by calcining at 1200 ° C. for 2 hours and further firing at 1200 ° C. for 6 hours. It was confirmed by X-ray diffraction analysis (XRD) using CuKα rays that the oxide powder had a perovskite structure. A perovskite oxide raw material cake was prepared by adding 4 g of kaolin, 4 g of cellulose, and 2 g of pure water to 16 g of this powder, and a load of 100 kg was applied to an extruder to obtain pellets having a diameter of 1.6 mmφ. The pellets were heated to 800 ° C. at 200 ° C./hour in the air and held for 1 hour to prepare activated perovskite oxide pellets.

Example 3
Packed column 4a, a first embodiment of the present invention using the BaFeO _3-δ where oxygen-selective adsorbent honeycomb 5a, a Y of Y / Fe ratio 0.01 prepared in Synthesis Example 2 as b doped of b Was carried out in the same manner as in Example 1. PSA operating conditions and separation performance in separation of oxygen and nitrogen from air (product oxygen concentration, power intensity during production of oxygen (kWh / m ³ N—O ₂ ), oxygen adsorption load (m ³ N—O ₂ / h / ton) was evaluated.
The results are shown in Table 5 below.

In the La-Sr-Co-Fe-O-based sample, the reversible decrease in the oxygen adsorption rate appears remarkably at low temperatures, but as a result of replacing various substances based on SrFeO _3-δ , a certain amount of Ba is replaced. Thus, the reversible oxygen adsorption rate at a low temperature can be improved, and when Y and In are doped, a stable oxygen adsorption amount and oxygen adsorption rate can be secured even at a low temperature of 300 ° C. or lower. FIG. 3 shows the reversible oxygen adsorption amount of BaFeO _3-δ (hereinafter abbreviated as BFY0.01) doped with Y having a Y / Fe ratio of 0.01 at an oxygen concentration of 21 vol% and a measurement temperature of 100 to 600 ° C. FIG. 4 shows the oxygen adsorption rate. As shown in FIG. 3, the oxygen adsorption amount is 8 ml N / g, which is the highest, and twice as much oxygen as the conventional La _0.1 Sr _0.9 Co _0.9 Fe _0.1 O _3-δ sample (abbreviated as LSCF1991). The amount of adsorption is shown. Further, as shown in FIG. 4, the oxygen adsorption rate is 2.5 times as high as the oxygen adsorption rate at 250 ° C., and it can be seen that Y-doping is effective for shifting the optimum oxygen adsorption temperature to a low temperature.
From the above, practical applicable to oxygen separation from _air, improvement of reversible oxygen adsorption amount and oxygen adsorption rate is seen to have been achieved.

Next, FIG. 5 shows the reversible oxygen adsorption amount at an oxygen concentration of 21 vol% and FIG. 6 shows the oxygen adsorption rate when the Y doping amount is changed from 0 to 0.3 at an adsorption temperature of 250 ° C. Oxygen adsorption amount as shown in FIG. 5 shows the maximum value 8mlN / g at adsorption temperature 250 ° C., the oxygen adsorption rate is about as compared to the untreated BaFeO _3-δ at Y / Fe ratio 0.001 5 times the adsorption rate.

FIG. 7 shows the reversible oxygen adsorption amount of BaFeO _3-δ (hereinafter abbreviated as BFI 0.02) doped with In having an In / Fe ratio of 0.02 at an oxygen concentration of 21 vol% and a measurement temperature of 100 to 600 ° C. FIG. 8 shows the oxygen adsorption rate. As shown in FIG. 7, the oxygen adsorption amount is 9 ml N / g, which is 2.2 times the oxygen adsorption amount of the conventional LSCF1991 sample, and the oxygen adsorption rate is 5 times the adsorption rate. Is effective in shifting the optimum oxygen adsorption temperature to a low temperature.

Next, FIG. 8 shows the reversible oxygen adsorption amount at an oxygen concentration of 21 vol% and FIG. 9 shows the oxygen adsorption rate when the In doping amount is changed from the In / Fe ratio of 0 to 0.1 at an adsorption temperature of 250.degree. As shown in FIG. 8, the oxygen adsorption amount is In / Fe = 0.02 and the maximum value is 9 ml N / g, and the In / Fe ratio is 0.002 or more, compared with undoped BaFeO _3-δ. The oxygen adsorption rate is also 6 times the oxygen adsorption rate.

The oxygen-selective adsorbent of the present invention has a very wide range of application. For example, when applied to an oxygen separation / concentration apparatus using an oxygen-selective adsorbent, it can be applied to PSA, and the conventional N ₂ adsorption This far surpasses the adsorption performance of the type molecular sieves and opens the way to downsizing the equipment and reducing the cost of oxygen separation and concentration.
In addition, if the oxygen-selective adsorbent of the present invention is used for oxygen removal, extremely inexpensive nitrogen production can be provided.

It is a schematic explanatory drawing of the apparatus used in order to implement the 1st embodiment of this invention. It is a schematic explanatory drawing of the apparatus used in order to implement the 2nd embodiment of this invention. Oxygen concentration 21 vol%, showing a reversible oxygen adsorption amount of BaFeO _3-δ doped with Y in Y / Fe ratio 0.01 in the adsorption temperature 100 to 600 ° C.. The oxygen adsorption rate of BaFeO _3-δ doped with Y at a Y / Fe ratio of 0.01 at an oxygen concentration of 21 vol% and an adsorption temperature of 100 to 600 ° C. is shown. Exhibits a reversible oxygen adsorption amount of BaFeO _3-δ when the Y doping amount in the adsorption temperature 250 ° C. was changed in Y / Fe ratio to 0.3. The oxygen adsorption rate of BaFeO _3-δ when the Y doping amount at an adsorption temperature of 250 ° C. is changed with a Y / Fe ratio of 0 to 0.3 is shown. The reversible oxygen adsorption amount of BaFeO _3-δ doped with In at an In / Fe ratio of 0.02 at an oxygen concentration of 21 vol% and an adsorption temperature of 100 to 600 ° C. is shown. Oxygen concentration 21 vol%, an oxygen adsorption rate of BaFeO _3-δ doped with In by In / Fe ratio of 0.02 in the adsorption temperature 100 to 600 ° C.. The reversible oxygen adsorption amount of BaFeO _3-δ when the In doping amount at an adsorption temperature of 250 ° C. is changed with an In / Fe ratio of 0 to 0.1 is shown. The oxygen adsorption rate of BaFeO _3-δ when the In doping amount at an adsorption temperature of 250 ° C. is changed with an In / Fe ratio of 0 to 0.1 is shown.

Explanation of symbols

4a, b Packing tower 5a, b Adsorbent 12 Product tank 19a, 19b Heat storage material 20a, 20b Mixed gas-nitrogen heat exchanger 21a, 21b Mixed gas heater 26 Desorption gas tank

Claims (6)

Perovskite type oxidation in which Y or In is doped into BaFeO _3-δ used as a heat storage material, mixed gas-nitrogen heat exchanger, mixed gas heater, oxygen selective adsorbent, mixed gas mainly composed of oxygen and nitrogen The mixture gas is supplied to the adsorption tower filled with the material under a relatively high pressure condition, the mixed gas and the heat storage material are brought into contact with each other to raise the temperature of the mixed gas, and then the mixed gas is discharged from the tower with a mixed gas-nitrogen heat exchanger. The temperature is raised by exchanging heat with nitrogen, and then the mixed gas is brought into contact with a mixed gas heater to set the adsorption temperature, and then brought into contact with an oxygen-selective adsorbent to adsorb oxygen and separate from nitrogen, Pressure-adsorption method (PSA) of oxygen and nitrogen, in which oxygen-selective adsorbent that adsorbs oxygen is introduced to a relatively low pressure condition, oxygen is desorbed, and heat is recovered from high-temperature oxygen by contact with oxygen and a heat storage material Separation method by. A mixed gas composed mainly of oxygen and nitrogen is used as a high-temperature oxygen selective adsorbent, and BaFeO _3-δ is contacted with a perovskite oxide doped with Y or In to adsorb oxygen under relatively high pressure conditions. The oxygen-selective adsorbent that has adsorbed oxygen after being separated from nitrogen is purged under atmospheric pressure or reduced pressure conditions using product nitrogen as a purge gas to further desorb oxygen, according to the PSA of oxygen and nitrogen according to claim 1 Separation method. BaFeO ₃ used as a high-temperature oxygen adsorbent by installing a moisture adsorbent upstream of the heat storage material in the direction of the flow of the mixed gas, adsorbing moisture under a relatively high pressure condition to prepare a dry mixed gas _Concentrated by supplying oxygen to the perovskite oxide doped with Y or In at _-δ , adsorbing oxygen, bringing high-temperature oxygen desorbed under relative reduced pressure conditions into contact with the heat storage material, and recovering heat from oxygen The method for separating oxygen and nitrogen by PSA according to any one of claims 1 to 2, wherein adsorbed moisture is released from oxygen.   The adsorption tower after completion of the adsorption process and the adsorption tower after completion of the desorption process are connected at the rear of the tower, and oxygen remaining in the adsorption tower after completion of the adsorption process is supplied to the adsorption tower after completion of the desorption process and recovered. Item 4. A method for separating oxygen and nitrogen according to any one of Items 1 to 3 by PSA. A pressure swing adsorption device for supplying a mixed gas mainly composed of oxygen and nitrogen under a relatively high pressure condition to separate oxygen and nitrogen, in the flow direction of the mixed gas,
(1) A heat storage material for recovering heat from the adsorbed high-temperature oxygen and imparting the recovered heat to the mixed gas;
(2) The mixed gas that has passed through the separated heat storage material flows on one side of the heat exchanger, and the high-temperature nitrogen product gas that flows out of the packed tower flows on the other side of the heat exchanger and is mixed from the high-temperature nitrogen product gas. A mixed gas-nitrogen heat exchanger that recovers heat to the gas and raises the temperature of the mixed gas flowing out of the heat exchanger,
(3) A heater for heating the mixed gas heated through a heat exchanger with nitrogen to an adsorption temperature,
(4) 2 parallel packed towers equipped with an adsorbent bed that selectively adsorbs oxygen by allowing nitrogen to pass through after selectively adsorbing oxygen through the mixed gas-nitrogen heat exchanger. A pressure swing adsorption device that includes more than a tower and separates oxygen and nitrogen that are contained in a heat insulation chamber to keep the packed tower warm. As the oxygen selective adsorbent, a perovskite oxide in which BaFeO _3-δ is doped with Y in a Y / Fe molar ratio of 0.001 or more or In is doped in In / Fe with a molar ratio of 0.002 or more is used. The method for separating oxygen and nitrogen by PSA according to any one of claims 1 to 5, which is carried out at an adsorption temperature of ~ 350 ° C.

Images