KR20180031888A - Energy Saving of High Purity Ammonia Separation Method - Google Patents

Abstract

Disclosed is a high purity ammonia purification method which is capable of greatly reducing production costs of ammonia by using cooling water and waste heat water in a plant without using an additional apparatus for condensation of ammonia. The present invention provides an energy saving type high purity ammonia purification method comprising the steps of: (a) primarily heating an ammonia mixture in a first heat exchanger to supply the primarily heated ammonia mixture to a first separation column; (b) discharging a low boiling point material through the top of the column and discharging a high boiling point material and ammonia through the bottom of the column in the first separation column; (c) supplying a mixture of the high boiling point material and ammonia to a second separation column; (d) discharging ammonia through the top of the column and discharging a high boiling point material through the bottom of the column in the second separation column; and (e) cooling ammonia discharged from the second separation column in a second heat exchanger to obtain liquid ammonia.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high purity ammonia purification method,

The present invention relates to an energy-saving purification method for high purity ammonia, and more particularly, to a method for reducing the cost of production of ammonia by using cooling water and waste heat water in a plant without using an additional apparatus for condensing ammonia The present invention relates to a method for purification of high purity ammonia.

Recently, nanostructures such as Quantum Well (QW), Quantum Dot (QD), and NanoWire (NW) have been reported as methods to reduce defects in semiconductors and increase LED luminous efficiency. . LEDs using semiconductor nanostructures can be confirmed by many announcements that the light conversion efficiency is higher than the conventional thin film type. GaN / ZnO nanorods and GaN nanotubes: GaN / ZnO coaxial nanorods are formed by epitaxial growth of GaN on top of ZnO nanorods. That is, a ZnO nanorod having a diameter of less than 10 nm to be used as a core is formed using Zn (C ₂ H ₅ ) ₂ and O ₂ in advance, and GaN is deposited on the nanorod using Ga (CH ₃ ) ₃ and NH ₃ . The purity of ammonia is very important.

Therefore, a purification process for effectively removing impurities such as moisture and low boiling point gases in ammonia gas is very important. Conventionally, a method of adsorbing and removing synthetic zeolite, activated carbon, activated alumina and the like using an adsorbent has been widely used. The use of such an adsorbent has the advantage of a relatively small amount of energy to be used but has a risk of secondary heavy metal contamination by the adsorbent and has a limit in mass production since the adsorbent must be continuously exchanged.

Korean Patent No. 1423090 discloses an ammonia purification system. In this invention, although high purity ammonia is obtained by using the adsorption unit, it is difficult to continuously operate due to the exchange of the adsorbent used in the adsorption unit, which is disadvantageous in that it is not suitable for mass production of ammonia.

Compared with the ammonia purification process using an adsorbent, the purification process using distillation has a large amount of energy consumption but is advantageous for a mass production process.

Korean Patent No. 1125770 discloses a method and an apparatus for producing high purity ammonia. In this invention, the purity of ammonia is increased by using three distillation columns, but the energy used for operating the distillation column and the energy for condensing the produced ammonia are large, and the three distillation columns are used.

Korean Patent Publication No. 2008-0100579 discloses a method and an apparatus for purifying ammonia. In the present invention, the high-boiling material-mingling low-boiling-point material is separately separated using two columns. However, since the condenser is operated at a temperature of 3.1 ° C and -2.0 ° C, the energy used for cooling is large.

The present invention solves the above-mentioned problems. In the ammonia separation process, quench water is used as a heat source and cooling water, which is commonly used in a factory, is used for cooling. To improve the thermal efficiency of the process, thereby maximizing the economical efficiency.

(A) heating the ammonia mixture in a first heat exchanger and supplying the ammonia mixture to a first separation column; (b) discharging the low boiling point material to the upper portion of the column and the high boiling point material and ammonia to the lower portion of the column in the first separation column; (c) feeding the mixture of high boiling point material and ammonia to a second separation column; (d) discharging ammonia in the second separation column to the upper portion of the column and discharging the high boiling substance to the lower portion of the column; And (e) cooling the ammonia discharged from the second separation column in a second heat exchanger to obtain liquid ammonia.

And the first heat exchanger uses waste water in the factory as a heat source.

And the second heat exchanger condenses ammonia using cooling water in a factory.

And the second separation column and the second heat exchanger have an internal pressure of 10 to 20 atm.

And a third heat exchanger and a fourth heat exchanger for heating the ammonia mixture in the separation column are further provided below the first separation column and the second separation column.

And a fifth heat exchanger and a sixth heat exchanger for lowering the temperature of the material discharged to the upper portion of the column are further provided on the first separation column and the second separation column.

According to the present invention, since evaporation and cooling of ammonia are performed using waste heat water and cooling water easily available in the factory, high purity ammonia can be recovered at a high yield while using less cost than the conventional ammonia refining method , It can have a large ripple effect on the semiconductor industry and the cooling apparatus industry using ammonia.

1 is a schematic diagram showing an apparatus and a process for carrying out the present invention;

Hereinafter, preferred embodiments of the present invention will be described in detail. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Throughout the specification, when an element is referred to as "including " an element, it means that it can include other elements, not excluding other elements, unless specifically stated otherwise.

The present inventors have observed that the conventional ammonia purification method uses a large amount of money for evaporation and condensation of ammonia. As a result of intensive studies to solve this problem, the present inventors have found that ammonia The present invention has been completed.

Hereinafter, the present invention will be described in detail.

In order to solve the above problems, the present invention provides an apparatus for refining ammonia with high purity from an ammonia mixture feed containing 1 to 20%, preferably 5 to 10% of water.

The ammonia mixture flows into the first heat exchanger 110 used as a heat source as waste heat, and the ammonia mixture having an increased temperature flows into the first separation column. The temperature of the ammonia mixture supplied to the first separation column may be 30 to 60 ° C, preferably 40 to 50 ° C, and more preferably 44 to 46 ° C.

In the first separation column 130, the low boiling point material flows out to the upper part of the column and the high boiling point material and the ammonia flow into the second separation column 170 through the lower part. At this time, it is preferable that a pressure difference is provided between the separation columns so that the ammonia mixture can be moved without a pump. In this case, the operation pressure is preferably 16 to 20 atm, and more preferably 16 to 18 atm. Also, the separation plate of the first separation column may have a single number of 10 to 30, preferably 15 to 20. It is also possible to move the ammonia using a pump in consideration of the amount of ammonia and the distance between the columns.

In the first separation column 130, a feed of the temperature-increased by the first heat exchanger 110, which uses the ammonia mixture as a heat source as waste heat, is introduced into the third heat exchanger 120) to reduce the heat supply. As the heat source used in the third heat exchanger 120, electricity, hot water, steam, or the like may be used, but it is preferable to use steam that is commonly used. At this time, the lower part of the first separation column is maintained at 30 to 60 ° C, preferably 45 to 50 ° C by the third heat exchanger, so that the low boiling point material among the ammonia mixture therein can be separated.

In the second separation column 170, ammonia is separated from the high boiling point compound and flows into the upper part. In the conventional purification method, the second separation column is operated at a low pressure and a refrigerant having a low temperature is produced using the refrigerator Since the ammonia is liquefied by using a refrigerator but it requires a lot of energy, in the present invention, it is preferable to keep the operation pressure of the column as high as 10 to 20 atm so as to sufficiently liquefy ammonia with the coolant of the cooling water level, The operating pressure may be between 13 and 18 atm. Also, the lower part of the second separation column is maintained at 60 to 150 ° C, preferably 80 to 120 ° C by the third heat exchanger, so that the ammonia inside can be evaporated and separated. In addition, the separation plate of the second separation column may have 10 to 30 single, preferably 15 to 20 single plates.

Ammonia in the ammonia mixture introduced into the second separation column 170 is separated into the upper portion and the high boiling substance is separated into the lower portion. The ammonia introduced into the upper part can not be completely condensed in the partial condenser 190 and is completely condensed through the second heat exchanger 200 using the cooling water as a heat source. The highly condensed high purity ammonia can be introduced into the ammonia tank via the first drum 210. At this time, since the operation pressure of the second separation column and the second heat exchanger is maintained as high as 10 to 20 atm, the ammonia can be cooled to 38 to 40 ° C and condensed. In general, the cooling water used in the process can lower the temperature of the raw material to 38 to 40 ° C, so that the ammonia can be condensed in the second heat exchanger 200 using the cooling water as the refrigerant without using the additional cooling device .

  The apparatus for producing high purity ammonia according to the present invention is provided with a plurality of sensors for controlling and maintaining the gas control valve, the temperature and the gas flow rate at a set value in order to efficiently control the apparatus, But the present invention is not limited thereto.

 Hereinafter, the present invention will be described in more detail with reference to specific examples and comparative examples.

Example  One

  1 is a view showing an energy saving ammonia purification apparatus according to a first embodiment of the present invention. The purification experiment of ammonia was carried out using the same apparatus as in Fig. The experimental apparatus used in this embodiment is as follows.

First Heat Exchanger: Heat to 45 ° C using waste heat water generated from a naphtha cracking center (NCC)

First separation column: lower temperature 45 캜, internal pressure 18 atm, separation plate 18, heating with steam

Second separation column: bottom temperature 100 캜, internal air pressure 16 atm, separation plate 18 stages, heating with steam

Second heat exchanger: Using cooling water as a refrigerant, cooling the ammonia to 40 ° C

An ammonia mixture (Table 1) produced in the factory was fed to the first heat exchanger to conduct a purification experiment.

Raw material Flow rate (kg) ratio(%) ammonia 241 89.6 moisture 24 8.9 carbon monoxide 0.78 0.3 carbon dioxide 0.48 0.2 nitrogen 1.2 0.4 Oil component 1.6 0.6

Comparative Example  One

Experiments were carried out in the same manner as in Example 1 except that the first heat exchanger and the second heat exchanger were directly heated and cooled by using electricity.

Comparative Example  2

The same experiment as in Example 1 was carried out, but experiments were carried out using the following conditions.

First heat exchanger: Direct heating using electricity up to 45 ° C

First separation column: lower temperature 45 캜, internal pressure 18 atm, separation plate 18, heating with steam

Second separation column: lower temperature 20 캜, internal air pressure 8 atm, separation plate 18, heating with steam

Second heat exchanger: Ammonia cooled to -2 캜 using electricity

Experimental Example

The amount of energy used and the cost of each of the examples and comparative examples were measured and are shown in Table 2.

The first heat exchanger The first separation column The second separation column The second heat exchanger Total Energy (Kcal) cost
(won) Energy (Kcal) cost
(won) Energy (Kcal) cost
(won) Energy (Kcal) cost
(won) Energy (Kcal) cost
(won) Example 1 5240 100 7580 150 8260 170 6250 130 27330 550 Comparative Example 1 5240 1100 7580 150 8260 170 6250 1400 27330 2820 Comparative Example 2 5240 1100 1290 50 570 10 4680 900 11780 2060

As shown in Table 2, the purification method of ammonia according to the present invention requires a lot of energy compared with the conventional method using the low pressure separation column (Comparative Example 2), but the energy supplied to the heat exchanger using the most energy It can be seen that the cost is greatly reduced by using waste water and factory cooling water. In particular, this difference is expected to increase in the future, as industrial electric charges are expected to increase.

Further, ammonia purification was performed through the apparatus, and as a result, the ammonia recovery rate was 97% and the purity was 99.999% or more.

The preferred embodiments of the present invention have been described in detail above. It will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Accordingly, the scope of the present invention is defined by the appended claims rather than the foregoing detailed description, and all changes or modifications derived from the meaning, range, and equivalence of the claims are included in the scope of the present invention Should be interpreted.

110: first heat exchanger 120: third heat exchanger
130: first separation column 140: fourth heat exchanger
150: first partial condenser 160: fifth heat exchanger
170: second separation column 180: sixth heat exchanger
160: Second partial condenser 170: Second heat exchanger

Claims (6)

An energy saving high purity ammonia purification method comprising the steps of:
(a) feeding the ammonia mixture into a first separation column by first heating in a first heat exchanger;
(b) discharging the low boiling point material to the upper portion of the column and the high boiling point material and ammonia to the lower portion of the column in the first separation column;
(c) feeding the mixture of high boiling point material and ammonia to a second separation column;
(d) discharging ammonia in the second separation column to the upper portion of the column and discharging the high boiling substance to the lower portion of the column; And
(e) cooling the ammonia discharged from the second separation column in a second heat exchanger to obtain liquid ammonia. The method according to claim 1,
Wherein the first heat exchanger uses waste heat in a factory as a heat source. The method according to claim 1,
Wherein the second heat exchanger condenses ammonia using cooling water in the plant. The method according to claim 1,
Wherein the second separation column and the second heat exchanger have an internal pressure of 10 to 20 atm. The method according to claim 1,
And a third heat exchanger and a fourth heat exchanger for heating the ammonia mixture in the separation column are further provided below the first separation column and the second separation column. The method according to claim 1,
Wherein a fifth heat exchanger and a sixth heat exchanger are further provided on the first separation column and the second separation column to lower the temperature of the material discharged to the upper portion of the column.

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