JPH10170144A - Device and method for cleaning raw air of air liquefaction and separation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the power cost and the equipment cost in cleaning the air by removing the water and carbon dioxide in the raw air in an air liquefaction and separation device by an adsorber. SOLUTION: A refrigerant heat exchanger 33 to perform the heat exchange between the pressurized raw air and the low-temperature refrigerant is provided between a raw air compressor 1 and an adsorber 4, a water separator 34 to separate the condensed water in the low-temperature raw air passing from the refrigerant heat exchanger 33 and an air heat exchanger 35 to perform the heat exchange between the dried raw air passing from the water separator 34 and the pressurized raw air before entering the refrigerant heat exchanger 33 are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for purifying raw material air for an air liquefaction / separation apparatus. More specifically, the present invention relates to a method for compressing, purifying and cooling raw material air and introducing the compressed air into a rectification column. The present invention relates to an apparatus for purifying raw air and a method for purifying raw air in an air liquefaction separation apparatus for producing oxygen, nitrogen and the like as products by rectification separation.

[0002]

2. Description of the Related Art In an air liquefaction / separation apparatus that produces air components such as oxygen and nitrogen as products, water and carbon dioxide, which are impurities in raw air, are adsorbed and removed by an adsorbent. When the adsorbent removes moisture and carbon dioxide in the air, the adsorption performance of the adsorbent increases as the adsorption temperature decreases, and the treatment can be performed with a small amount of adsorbent.

For this reason, as shown in FIG. 4, raw air compressed to a predetermined pressure by a raw air compressor 1 is cooled to about 40 ° C. by removing heat of compression by an aftercooler 2, and is further cooled by freon refrigeration equipment. After cooling to 5 to 10 ° C. in 3, the mixture was introduced into the adsorber 4. That is, the raw air is cooled by exchanging heat with the low-temperature refrigerant of the Freon refrigerator in the heat exchanger 5 in the Freon refrigeration facility 3, and after condensed water generated by the cooling is separated by the water separator 6, It is introduced into the adsorber 4.

[0004] Therefore, the raw material air introduced into the adsorber 4 contains a substantially saturated amount of water at the inlet temperature of the adsorber 4, and in the adsorber 4, the water is first adsorbed. The raw material air is heated by the heat of adsorption. Therefore, the next adsorption of carbon dioxide gas is performed in a state where the temperature of the raw material air is high, and accordingly, the adsorption performance of the adsorbent is reduced. In particular, when the inlet temperature of the adsorber 4 is high, the temperature rise of the raw material air becomes extremely large because of the large water content.

[0005] For example, when the raw material air pressure is 5 kg / cm ² G
When the adsorber inlet temperature is 5 ° C., the water content is 0.0012 kgH ₂ O / m ³ air, the temperature rise due to the heat of water adsorption is about 3 ° C. ,
It will operate at a temperature of about 8 ° C.

On the other hand, recently, a method has been adopted in which the compressed raw material air is cooled to 25 to 40 ° C. with cooling water in an aftercooler without providing the Freon refrigeration equipment, and condensed water is separated and then introduced into an adsorber. It is becoming. That is, the specifications of the adsorber are determined so as to adapt to the raw material air conditions, and an apparatus is being manufactured. However, when the adsorber inlet temperature is 40 ° C., the water content is 0.010 kgH ₂ O / m ³ air, and the temperature rise due to the heat of water adsorption is about 22 ° C. Operation at ℃.

[0007]

However, when the atmospheric temperature approaches 40.degree. C. in summer, the temperature of the cooling water cooled by the cooling tower may exceed 35.degree. Cannot be maintained at 40 ° C. or lower. In particular, when the raw material air is cooled by air cooling, it is difficult to lower the temperature of the raw material air to a predetermined adsorber inlet temperature or lower, and it has been necessary to cool the raw material air using a refrigerator or the like.

When a refrigerator is used to cool the raw material air, when the temperature is reduced from 40 ° C. to 10 ° C., the amount of heat required for the cooling is 1 Nm ³ / h of air, and the heat of condensation of the contained moisture (5.0 kcal / Nm ^3). ) And the sensible heat of air at 30 ° C. (9.3 kcal / Nm ³ ), which is 14.3 k.
cal / h. Furthermore, there is no versatility of cooling equipment,
Pre-cooling equipment such as a cooler was manufactured by order for each air liquefaction separator.

Accordingly, the present invention provides a raw material air purification apparatus for an air liquefaction / separation apparatus which can reduce power and equipment costs in purifying water and carbon dioxide in the raw material air by an adsorber in the air liquefaction / separation apparatus. And a method.

[0010]

Means for Solving the Problems To achieve the above object, a raw material air purification apparatus for an air liquefaction / separation apparatus according to the present invention comprises:
In a raw material air refining apparatus for an air liquefaction / separation apparatus having a raw material air compressor for compressing raw air to a predetermined pressure and an adsorber for removing moisture and carbon dioxide in the compressed pressurized raw air, A refrigerant heat exchanger for exchanging heat between the pressurized raw material air and the low-temperature refrigerant of the refrigerator, and separating condensed water in the low-temperature raw material air derived from the refrigerant heat exchanger. Water separator, characterized by having provided an air heat exchanger for heat exchange between the dried raw material air derived from the water separator and the pressurized raw material air before being introduced into the refrigerant heat exchanger, In a stage preceding the adsorber, a compression means for further increasing the pressure of the dry raw material air led out of the air heat exchanger, that is, a compressor or a compression stage of the raw material air compressor is provided.

Further, in the method for purifying raw material air of the air liquefaction separation apparatus according to the present invention, the raw material air is compressed to a predetermined pressure by a raw material air compressor, and moisture and carbon dioxide gas in the compressed pressurized raw material air are removed by an adsorber. In the method for purifying raw material air of an air liquefaction / separation apparatus, the compressed pressurized raw material air is cooled by an aftercooler, and then further cooled by heat exchange with a low-temperature refrigerant of a refrigerator. Water is separated by a water separator, and heat exchange is performed between the dried raw material air from which the water has been separated and the pressurized raw air cooled by the aftercooler to cool the pressurized raw air and raise the temperature of the dry raw air. Then, the heated raw material air is introduced into the adsorber. Further, in the method of the present invention, the temperature of the low-temperature raw material air cooled by heat exchange with the low-temperature refrigerant is equal to or higher than a temperature at which the water content at the predetermined pressure does not freeze, that is, approximately 0 ° C. or higher and 15 ° C. or lower, It is characterized in that the temperature of the dry raw material air introduced into the adsorber is set to 60 ° C. or lower.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a system diagram showing an example of a raw material air purification device of an air liquefaction / separation device of the present invention, and FIG. It is a system diagram.

First, the air liquefaction / separation apparatus shown in FIG. 2 includes, as pretreatment equipment, a raw air compressor 1 for compressing raw air to a predetermined pressure, and a compression heat of pressurized raw air compressed by the raw air compressor 1. An aftercooler 2 for removing pressurized raw material air to about 40 ° C. to remove depressurized raw material air from the aftercooler 2 to lower the dew point by performing dehumidification (drying). An adsorber 4 is provided for adsorbing and removing impurities such as moisture and carbon dioxide in the dried raw material air. The raw material air purified by the adsorber 4 is introduced into the cold box 11.

In a cold box 11, a main heat exchanger 12 for cooling the raw material air to near the liquefaction temperature, a rectification column 16 provided with an upper column 13, a lower column 14, and a main condensation evaporator 15; Turbine 17, subcooler 18, expansion valve 1
The raw material air is separated into nitrogen, oxygen, and the like by a rectification operation in the rectification column 16.

The drying device 30 provided between the raw material air compressor 1 and the adsorber 4 functions as shown in FIG.
As shown in FIG.
1, a refrigerant heat exchanger (evaporator) 33 for exchanging heat between the low-pressure refrigerant and the pressurized raw material air introduced into the refrigerant condenser 32 and the drying device 30, and the low-temperature raw material cooled by the refrigerant heat exchanger 33 A water separator 34 for separating condensed water in the air; and an air heat exchanger for exchanging heat between the dry raw material air derived from the water separator 34 and the pressurized raw material air before being introduced into the refrigerant heat exchanger 33. 35.

In the raw material air compressor 1, for example, 5 kg / cm
^The pressurized raw material air compressed to ² G and cooled to about 40 ° C. by the aftercooler 2 is introduced into the refrigerant heat exchanger 33 via the air heat exchanger 35 of the drying device 30, where it is used for the refrigeration cycle. By exchanging heat with a low-temperature refrigerant, it is cooled to 0 to 15 ° C, for example, 10 ° C. The low-temperature raw material air cooled by the refrigerant heat exchanger 33 is then supplied to the water separator 3
After being condensed by the cooling, the condensed water generated by the cooling is introduced into the air heat exchanger 35. In the air heat exchanger 35, the dried raw material air led out of the water separator 34 and the pressurized raw material air exchange heat. For example, while the pressurized raw material air is cooled to 10 ° C, the dry raw material air is cooled to 35 ° C. Temperature.

The adsorber 4 drawn out of the drying device 30
In this case, the temperature of the raw material air to be introduced is 35 ° C. and the dew point is 10 ° C. The temperature is high but the amount of water is small, so the temperature rise due to the heat of adsorption of water in the adsorber 4 is about 3.8 ° C. The gas adsorption section operates at about 38.8 ° C.

At this time, since the pressurized raw material air has already been cooled to 15 ° C. in the air heat exchanger 35, the amount of heat of condensation of the moisture (5.0 kcal) per 1 Nm ³ / h of air is reduced. / Nm ³ ) and the sensible heat of air for 5 ° C. (1.6 kcal / Nm ³ ), which is 6.6 kc.
al / h.

Therefore, the operating temperature in the carbon dioxide gas adsorption section can be reduced, the carbon dioxide adsorption capacity can be improved, and the treatment can be performed with a small amount of adsorbent as compared with a conventional water-cooled type apparatus without a Freon refrigerator. Can be.

On the other hand, in order to introduce the raw material air containing saturated moisture into the adsorber 4 without providing the drying device 30, the operating temperature of the carbon dioxide gas adsorbing section becomes 38.8 ° C. The adsorber inlet temperature is about 27.7 ° C (0.0047 kg
Must be in H ₂ O / m ³ air), cooling amount of heat required for the pre-cooling is attached to the same air 1 Nm ³ / h, moisture condensation heat (3.18kcal / Nm ³⁾ with air sensible heat (3. 9
kcal / Nm ³ ), which is 7.1 kcal / h.

Therefore, in this embodiment, the amount of cooling heat can be reduced by about 7%, and a general-purpose drying device can be used. It can be greatly reduced. In particular, it is suitable as a raw material air refining apparatus and method for an air liquefaction / separation apparatus in high temperature atmospheric conditions in summer or in a tropical region where cooling is difficult with conventional air-cooling or water-cooling systems.

The lower the temperature of the low-temperature raw material air cooled by exchanging heat with the low-temperature refrigerant in the refrigerant heat exchanger 33, the lower the moisture content, the lower the temperature of the low-temperature raw material air. Since it is necessary to increase the capacity of the drying device 30 when the temperature is lowered, the temperature is optimally in the range of 0 to 15 ° C., particularly around 10 ° C., including other conditions such as the amount of raw material air. Further, it is advantageous for the adsorber 4 that the temperature of the dry raw material air which is heated by the air heat exchanger 35 and introduced into the adsorber is lower, but if the temperature is 60 ° C. or less, a sufficient effect is obtained. Obtainable.

As shown in FIG. 3, a secondary compressor 21 and an aftercooler 22 may be provided at the subsequent stage of the drying device 30 to further increase the pressure of the dried material air before introducing it to the adsorber 4. it can. At this time, the secondary compressor 21 may be an independent compressor different from the raw material air compressor 1,
When the raw material air compressor 1 is a multi-stage compressor, it may be a part of the compression stage. The configuration of the drying device 30 and the like is as follows.
Since it can be formed in the same manner as in the first embodiment, the same reference numerals are given and the detailed description is omitted.

[0024]

As described above, according to the apparatus and method for purifying raw air in the air liquefaction / separation apparatus of the present invention, the power cost required for cooling the raw air in purifying the raw air using the adsorber. And equipment cost can be significantly reduced, and the purification efficiency in the adsorber can be improved. Thereby, the equipment cost etc. in an adsorber can also be reduced.

[Brief description of the drawings]

FIG. 1 is a system diagram showing one embodiment of a raw material air purification device of the present invention.

FIG. 2 is a system diagram showing an example of an air liquefaction / separation device to which the present invention is applied.

FIG. 3 is a system diagram showing another embodiment of the present invention.

FIG. 4 is a system diagram showing an example of a conventional raw material air purification device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Raw material air compressor, 2 ... After cooler, 4 ... Adsorber, 11 ... Cold box, 12 ... Main heat exchanger, 16
... rectification tower, 17 ... expansion turbine, 30 ... drying device, 31
... refrigerant compressor, 32 ... refrigerator condenser, 33 ... refrigerant heat exchanger, 34 ... water separator, 35 ... air heat exchanger

Claims (5)

[Claims] 1. A raw material air refining device for an air liquefaction / separation device having a raw material air compressor for compressing raw material air to a predetermined pressure, and an adsorber for removing moisture and carbon dioxide in the compressed pressurized raw material air. A refrigerant heat exchanger for exchanging heat between the pressurized raw air and the low-temperature refrigerant of the refrigerator is provided between the raw material air compressor and the adsorber, and a low-temperature raw material air from which the refrigerant heat exchanger is derived is provided. A water separator for separating condensed water, and an air heat exchanger for exchanging heat between the dried raw material air derived from the water separator and the pressurized raw material air before being introduced into the refrigerant heat exchanger are provided. A raw material air purification unit for an air liquefaction separation unit. 2. A raw material air purification apparatus for an air liquefaction / separation apparatus according to claim 1, wherein a compression means for further increasing the pressure of the dry raw material air derived from the air heat exchanger is provided at a stage preceding the adsorber. apparatus. 3. The raw material air refining method of an air liquefaction / separation apparatus in which raw air is compressed to a predetermined pressure by a raw air compressor and moisture and carbon dioxide in the compressed pressurized raw air are removed by an adsorber. After the pressurized raw material air was cooled by an aftercooler, it was further cooled by exchanging heat with a low-temperature refrigerant of a refrigerator, and condensed water in the cooled low-temperature raw material air was separated by a water separator, and the water was separated. The dried raw air and the pressurized raw air cooled by the after-cooler are heat-exchanged to cool the pressurized raw air and raise the temperature of the dry raw air, and then, the heated dry raw air is adsorbed by the adsorption. A method for purifying raw material air of an air liquefaction / separation apparatus, which is introduced into a vessel. 4. The method according to claim 3, wherein the temperature of the low-temperature raw material air cooled by heat exchange with the low-temperature refrigerant is 0 to 15 ° C. 5. The raw material air refining method for an air liquefaction / separation apparatus according to claim 3, wherein the temperature of the dry raw material air introduced into the adsorber is 60 ° C. or lower.