JP3151627B2 - Oxygen production apparatus and method for heating raw material air - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for producing oxygen and a method for raising the temperature of the raw material air, and more particularly, to an oxygen production apparatus for separating oxygen from air into nitrogen by pressure fluctuation type adsorption separation to obtain product oxygen. Equipment, especially when the raw material air pressure is 1 kg /
The present invention relates to a means for heating a raw material air to a temperature suitable for an adsorption / separation operation in a large-sized apparatus having a size of cm ² G or less.

[0002]

2. Description of the Related Art An oxygen production apparatus (hereinafter referred to as oxygen PSA) which obtains product oxygen by separating oxygen in air from nitrogen by a pressure fluctuation type adsorption separation method is, for example, a component which hardly adsorbs oxygen and easily adsorbs nitrogen. A plurality of adsorption towers filled with an adsorbent such as zeolite as a component, and for the plurality of adsorption towers, an adsorption step of adsorbing nitrogen in the raw material air to the adsorbent to obtain oxygen, After the end of the process, the pressure inside the adsorption tower is reduced, and then the regeneration operation of purging and desorbing the nitrogen content adsorbed on the adsorbent using a part of the product gas is repeated in order to produce oxygen by repeating the basic operation. It is.

For example, FIG. 3 shows an oxygen P having three adsorption towers.
The feed air supplied from the air blower 1 is supplied to the inlet valves 2a, 2a of the adsorption towers A, B, C.
The product oxygen gas introduced into the adsorption tower from one of b and 2c and led out from the upper part of the adsorption tower is pressurized by the compressor 3 to a predetermined pressure. At this time, the product oxygen rises in temperature as the pressure rises, so it is cooled by the aftercooler 4 and supplied to the demand destination.

For example, when the adsorption tower A is in the adsorption step,
The other two adsorption towers B and C are in the pressurizing step or the vacuum depressurizing step, and these are switched by the inlet valves 2a and 2b.
b, 2c, the vacuum exhaust valves 5a, 5b, 5c, and the product take-out valves 6a, 6b, 6c are sequentially opened and closed in a predetermined order. The gas in the adsorption tower during the vacuum depressurization step is discharged to the outside air via the vacuum pump 7 and the silencer 8.

Various adsorbents have been used in such an oxygen PSA, and there is an optimum operating temperature for separating oxygen and nitrogen depending on the adsorption characteristics and the operating pressure. FIG. 4 shows the general characteristics of the adsorbent with respect to the temperature. As shown by the line A, the adsorption amount per unit amount of the adsorbent increases as the temperature decreases, but the separation coefficient (O ₂
/ N ₂ ), as indicated by the line B, becomes higher as the temperature becomes higher. The yield of the product oxygen obtained from the oxygen PSA was determined by the relationship between the adsorption amount and the separation coefficient, as shown in line C.
It shows the maximum value at a certain temperature.

On the other hand, in an oxygen PSA in which regeneration is performed using a vacuum pump, the suction amount of the vacuum pump is set by determining a value at a certain temperature. When the ambient temperature (raw material air temperature) becomes lower than the set temperature, the amount of adsorption increases, and the amount to be sucked increases. Conversely, when the temperature becomes high, the opposite phenomenon occurs.

[0007] Further, also in the case of an oxygen PSA in which purge regeneration is performed using a part of the product gas without performing vacuum regeneration, when the temperature is lowered, the amount of raw material air increases, and the amount of adsorbent adsorbed increases. Therefore, a large amount of purge product gas is required for regeneration, and the amount of product is reduced. At higher temperatures, the opposite decrease occurs.

In consideration of all of these various factors, an optimum temperature that minimizes the operation cost of the apparatus is obtained.
It will be around 30 ° C. In a large-sized apparatus having an air pressure of 1 kg / cm ² G or less, the temperature is usually set to 30 to 40 ° C. This is because the temperature of the raw material air supplied from the air blower 1 becomes approximately + 5 ° C. outside air temperature due to heat of compression and the like, and when air is taken in from the room where the device is installed, it is approximately + 10 ° C. outside air temperature. It is because it becomes. This is because if the operating temperature is set low, expensive equipment such as a refrigerator is required in the summer, which is not economical.

If the pressure of the raw material air is increased, the temperature is also increased. However, not only a refrigerator is required, but also the equipment cost of each component such as the adsorption tower increases with the increase of the pressure. Since the operating cost of the compressor also increases, in a large-scale apparatus, as described above, the raw material air pressure is set to 1 kg / cm.
Generally, it is set to ² G or less.

[0010]

However, as described above, when the operating temperature is set between 30 and 40 ° C., when the outside air temperature is low and the raw material air discharged from the air blower 1 is 30 ° C. or less, Since the specified performance cannot be obtained, it is necessary to heat the raw material air to a temperature of 30 ° C. or higher with a heater and introduce it into the adsorption tower. Not only heating equipment such as a heater, but also power and steam as a heating source, etc. Needed a utility.

Therefore, the present invention can heat the raw material air without using a heater using electric power or steam as a heat source, and can supply oxygen PS
It is an object of the present invention to provide a method for raising the temperature of oxygen PSA and raw material air, which can reduce the operating cost of A.

[0012]

In order to achieve the above-mentioned object, the oxygen producing apparatus of the present invention selectively adsorbs nitrogen.
While the plurality of adsorption towers filled with the adsorbent are switched to an adsorption step for separating nitrogen and oxygen in the raw material air and a regeneration step for desorbing the adsorbed components adsorbed on the adsorbent in the adsorption step. In the pressure fluctuation adsorption type oxygen production apparatus having a compressor that separates and collects oxygen from nitrogen and pressurizes the obtained product oxygen and supplies the product oxygen to a demand destination, the raw material air is pressurized by the compressor. A heat exchanger for exchanging heat with the product oxygen whose temperature has risen.

[0013] Further, in the method for raising the temperature of the raw material air of the present invention, in the above-mentioned oxygen production apparatus, as the heat source for heating the raw material air, product oxygen pressurized by the compressor and raised in temperature is used. .

[0014]

According to the above configuration, in the oxygen production method based on the pressure fluctuation type adsorption separation method in which the raw material air pressure is relatively low, the product oxygen heated and heated by the oxygen compressor is used as a heat source for heating the raw material air. Since it is used, utilities such as electric power and steam are not required, and energy can be saved.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail based on one embodiment shown in FIG. The same elements as those of the conventional example are denoted by the same reference numerals, and detailed description thereof will be omitted.

The oxygen PSA shown in the figure comprises three adsorption towers A, B, and C, an air blower 1, a compressor 3, an aftercooler 4, a vacuum pump 7, and a silencer 8 in substantially the same manner as in the conventional apparatus.
And inlet valves 2a, 2b, 2c for process switching, evacuation valves 5a, 5b, 5c, product take-out valves 6a, 6b, 6
c, etc., and switches each valve to open and close to continuously produce product oxygen.

In order to heat the raw material air discharged from the air blower 1, a heat exchange is performed on the discharge side of the air blower 1, in which the raw material air and the product oxygen pressurized by the compressor 3 are heat-exchanged. A vessel 11 is provided. Further, on the discharge side of the compressor 3, there are provided a path 12 for introducing pressurized product oxygen to the heat exchanger 11 and a bypass path 13 for bypassing the heat exchanger 11.

Further, a temperature indicator controller 14 for measuring the temperature of the raw air derived from the heat exchanger 11 is provided upstream of each inlet valve of the adsorption tower.
Is provided with a flow control valve 15 operated by the temperature indicating controller 14.

For example, a product oxygen gas having a pressure of 9.5 kg / cm ² G is supplied to the oxygen PSA having the above-mentioned structure at 1075 Nm ³ / hour.
In the case of the manufacturing apparatus, the product oxygen gas discharged from the compressor 3 has a temperature of about 170 ° C. This product oxygen gas is introduced into the heat exchanger 11 and heat-exchanged with the raw material air.
At 0 ° C., the specific heat of the oxygen gas is 0.3134 [kcal /
Nm ³ · ° C.], a calorific value of 1075 × 0.3134 × (170−40) = 43800 [kcal / h] is obtained.

On the other hand, the raw material air amount is 9200 Nm ³ / H, and the raw material air discharged from the air blower 1 has a heat exchanger 1.
Assuming that the heating temperature at 1 is x [° C.], the specific heat of air is 0.1.
Since it is 31 [kcal / Nm ³ · ° C.], x = 15 from 9200 × 0.31 × x = 43800.
[° C.] is obtained.

That is, the raw material air can be heated at 15 ° C. under the above conditions. If the lower limit temperature of the raw material air to be introduced into the adsorption tower is set at 25 ° C., even if the outside air temperature is 0 ° C., indoor air can be taken in. The product can be supplied with a minimum of compression power, and the product oxygen can be supplied with a minimum of utility without requiring a heater.

When the outside air temperature is 0 ° C. or less in a cold region or the like, it is necessary to provide a heater, but the amount of utility used can be greatly reduced. In such a state, the operation of the cooler 4 can be stopped.
Cooling water can be saved.

As shown in the above embodiment, by providing the bypass passage 13, the temperature indicating controller 14, and the flow control valve 15, the product oxygen gas is introduced into the heat exchanger 11 when the raw material air temperature is sufficiently high. Without reducing the temperature of the raw material air, the yield can be prevented from being too low, and the oxygen gas is automatically transferred to the heat exchanger 11 as the temperature of the raw material air decreases.
And the raw material air can be heated to a temperature suitable for the operation of the equipment, so that it can be operated at the highest yield regardless of fluctuations in the outside air temperature, thereby reducing overall product costs Can be.

FIG. 2 shows another embodiment of the present invention. In the feed air supply circuit, a bypass path 22 for bypassing the heat exchanger 11 is provided.
In the same manner as described above, a flow control valve 15 operated by a temperature indicating controller 14 is provided, and the amount of the raw air passing through the heat exchanger 11 is adjusted to heat the raw air to a predetermined temperature. . With such a configuration, the same operation and effect as described above can be obtained. Further, both the product oxygen bypass path 13 and the raw air bypass path 22 may be provided.

Further, the configuration of the oxygen PSA is not limited to that of the above-described embodiment, and the number of adsorption towers is arbitrary, and the present invention can be applied to a purge regeneration system that does not use a vacuum pump for regeneration. It is possible.

[0026]

As described above, according to the present invention, in the oxygen production method by the pressure fluctuation adsorption separation method in which the raw material air pressure is relatively low, when the product oxygen is supplied at a high pressure, the raw material air is heated. Since the product oxygen gas, which has been compressed by the compressor and has become high temperature, is effectively used as a heat source for use, utilities such as electric power and steam are not required, energy can be saved, and the production cost of the product can be reduced.

[Brief description of the drawings]

FIG. 1 is a system diagram of an oxygen PSA showing one embodiment of the present invention.

FIG. 2 is a system diagram of a main part of an oxygen PSA showing another embodiment of the present invention.

FIG. 3 is a system diagram showing an example of a conventional oxygen PSA.

FIG. 4 is a diagram showing characteristics of an adsorbent with respect to temperature.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Air blower 3 ... Compressor 11 ... Heat exchanger
13: bypass path 14: temperature indicating controller 15: flow control valve A,
B, C: adsorption tower

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-54-90074 (JP, A) JP-A-1-176414 (JP, A) JP-A-62-148304 (JP, A) (58) Investigation Field (Int.Cl. ⁷ , DB name) C01B 13/02 B01D 53/04

Claims (5)

(57) [Claims] 1. A plurality of adsorption towers filled with an adsorbent for selectively adsorbing nitrogen are subjected to an adsorption step for separating nitrogen and oxygen in the raw material air, and an adsorbent component adsorbed on the adsorbent in the adsorption step. oxygen in the feed air with collected separately from nitrogen while switched between regeneration step to desorb, pressure fluctuation absorption with compressor supplied to the demand end to boost the oxygen product obtained
The oxygen production apparatus according to claim 1, further comprising a heat exchanger for exchanging heat between the raw air and the product oxygen that has been pressurized and heated by the compressor. 2. The oxygen producing apparatus according to claim 1, wherein the pressure of the raw material air is 1 kg / cm ² G or less. 3. A bypass path for bypassing the heat exchanger is provided, and a temperature detector for measuring a temperature of the raw material air after deriving the heat exchanger is provided, and the temperature of the heat exchanger is determined based on a detected value of the temperature detector. The oxygen production apparatus according to claim 1, wherein a flow control valve for controlling a flow rate of the product oxygen and / or the raw material air to be introduced is provided in the bypass path. 4. A plurality of adsorption towers filled with an adsorbent for selectively adsorbing nitrogen are subjected to an adsorption step for separating nitrogen and oxygen in the raw material air, and an adsorbent component adsorbed on the adsorbent in the adsorption step. While switching to the desorption regeneration step, oxygen in the raw material air is separated from nitrogen and collected, and the obtained product oxygen is pressurized by a compressor and supplied to the demand- variable adsorption-type oxygen. In the production apparatus, a method of raising the temperature of the raw material air in the oxygen production apparatus, wherein product oxygen whose pressure is raised by the compressor and whose temperature is raised is used as a heat source for heating the raw material air. 5. The method according to claim 4, wherein the pressure of the raw material air is 1 kg / cm ² G or less.