KR20200024582A - Apparatus and method for purifying ammonia to UHP(Ultra High Purity) grade using distillation - Google Patents

Abstract

The present invention discloses an apparatus and a method for purifying ammonia using distillation. More specifically, the apparatus and the method for purifying ammonia using distillation not only store and pressure-reinforce low purity ammonia (NH_3) for an industrial purpose in a storage tank to regenerate the purification capacity of a distillation tower but also purify the low purity ammonia with ammonia of a purity of 99.99% or more and impurity moisture of 50 ppb or less by separating high and low boiling materials. The present invention is a process for purifying ultra high purity ammonia by using a distillation theory using different degrees of volatility of a mixture of multi-components without applying any adsorption process (zeolite, activated carbon, alumina, etc.). The present invention has effects of enabling convenient installation by being formed in a simple structure, having a low operating cost, and performing moisture removal and purification with ultra high purity of less than 10 ppb from ammonia raw material gas even when purifying not only a small capacity but also a high capacity by selective operation of a purification tower.

Description

Apparatus and method for purifying ammonia to UHP (Ultra High Purity) grade using distillation

The present invention relates to an apparatus and method for purifying ultra-high purity ammonia using distillation, and more particularly, to purifying industrial low-purity ammonia (NH₃) in a storage tank after vaporizing the liquid, thereby reducing the pressure to increase the purification capacity of the distillation column. In addition, the present invention relates to an apparatus and method for purifying ammonia using distillation to purify ammonia having a purity of 99.99999% or more and an impurity moisture of 50 ppb or less by separating a high boiling point and a low boiling point material.

Ammonia is widely used as a raw material for forming a nitride film or as a raw material for chemical industry in jewelry, cemented carbide and semiconductor manufacturing industries. The remaining ammonia after use is converted to inexpensive or valuable materials, which may be subject to exhaust gas treatment, or large amounts of useful ammonia may be released during the ammonia use phase without some treatment.

For example, in a synthetic semiconductor manufacturing process such as gallium nitride film, a considerable amount of ammonia is released from the synthetic semiconductor manufacturing apparatus at high concentration without reaction. In this case, the removal of harmful substances is very expensive and requires ammonia recovery in terms of environmental engineering and effective use of useful resources.

Among the known ammonia-containing exhaust gas treatment methods, there are a combination of a combustion treatment method, a wet absorption method, a dry adsorption method, a decomposition treatment method, a decomposition and a dry adsorption method.

However, the current method of removing water from ammonia gas has been to remove water by using zeolite (MS 4A, 5A, etc.) or by using manganese oxide or getter method. Considering that the instantaneous usage amounted to several hundred Nm3 / hr, the purification method used up to now is a small-capacity tablet of 5-100 Nm3 / hr or less and its capacity is very insufficient, and at least 100 to several hundred Nm3 / hr There is a disadvantage that not only decreases the purification efficiency due to the large capacity, but also causes a lot of problems in manufacturing and operation to achieve an even distribution of the fluid.

In order to solve such a problem, as shown in FIG. 1, in JP 2000-0062180 (ammonia recovery method and apparatus), at least one shell and also ammonia adsorbent are respectively filled with a heat transfer medium to perform heat exchange through an adsorption tube. A multi-tubular adsorber equipped with a plurality of adsorption tubes equipped with a flow mechanism for the installation, ammonia-containing gas passes through the adsorption tube and at the same time the inside of the adsorption tube is cooled by a heat transfer medium to absorb the ammonia in the gas cylinder and the adsorbate. A method for recovering ammonia has been proposed, wherein the collected ammonia is then collected through a desorption reaction and at the same time the inside of the adsorption tube is heated with a heat transfer medium under reduced pressure.

However, by using the same adsorption process (zeolite, activated carbon, alumina, etc.) as described above, it is quite difficult to purify the ultrapure water of 50ppb or less in moisture, and there is a risk of lowering the quality due to deterioration of the adsorption performance. Increasing the investment required for the construction of two adsorption towers for operation, dust and particles generated from the adsorbent itself are constantly occurring.

The present invention is to solve the above problems, by storing and pressure-increasing the industrial low-purity ammonia (NH₃) in the storage tank to not only regenerate the purification capacity of the distillation column, but also by separating the high boiling point and low boiling point material purity It is an object of the present invention to provide an apparatus and a method for purifying ammonia using distillation for purifying with ammonia of more than 99.99999% and less than 50 ppb of impurity moisture.

Purification apparatus and method of ammonia using distillation according to the present invention for achieving the above object, in the ultra-high purity ammonia purification apparatus for purifying low-purity ammonia to ultra high purity by using distillation, 9 A storage tank apparatus unit including a low purity raw material storage tank storing the saturated liquid at a pressure of 11 to 11 kg / cm² and a temperature of 25 to 30 ° C., and a plurality of heaters provided below the storage tank; The ammonia of the storage tank portion is connected to the pipe introduced and drawn out, a reboiler for heating and evaporating the liquid in the distillation column, a distillation tower for evaporating the ammonia component by the reboiler heating and a condenser for condensing the ammonia and condensed A high boiling point material separation device including a reflux container for collecting ammonia and a circulation pump for supplying ammonia liquid required for energy contact inside the distillation column; and a reboiler connected in series with the high boiling point material removal distillation column and heating and evaporating the liquid inside the distillation column. A low boiling point material separation device including a distillation column for evaporating the ammonia component by heating the reboiler and a condenser for condensing the ammonia; It is installed with the reboiler of the low boiling point material separation device, the ultra-high purity storage tank unit is provided with a storage tank for condensing the generated gas through a condenser and condensed ammonia vaporized therein; .

The expected effects due to the above-described features of the present invention include distillation theory using different volatilities of multi-component mixtures without any adsorption process (zeolite, activated carbon, alumina, etc.). It is a process to purify ultra high purity ammonia by using, simple structure, easy installation, low running cost, and 50ppb removal of water from ammonia source gas even in small capacity and high capacity purification by selective operation of refinery tower. There is an effect that can be purified to less than ultra high purity.

1 is a schematic view showing an example of a conventional ammonia recovery apparatus.
Figure 2 is a schematic configuration diagram of an ammonia gas purification apparatus according to an embodiment of the present invention.
Figure 3 is a view showing a low purity raw material storage tank device portion according to an embodiment of the present invention.
4 is a view showing a high boiling point material removing apparatus according to an embodiment of the present invention.
5 is a view showing a low boiling point material removing apparatus according to an embodiment of the present invention.
6 is a view showing the ammonia storage tank device according to an embodiment of the present invention.
7 is a view showing a jacket-type level gauge according to an embodiment of the present invention.
8 is a view showing the moisture analysis results using a HALO analyzer according to an embodiment of the present invention.
9 is a view showing the results of moisture analysis using the MTO analyzer according to an embodiment of the present invention.

In order to fully understand the present invention, preferred embodiments of the present invention will be described with reference to the accompanying drawings. Embodiment of the present invention may be modified in various forms, the scope of the invention should not be construed as limited to the embodiments described in detail below.

In addition, detailed description of well-known functions and configurations that are determined to unnecessarily obscure the subject matter of the present invention will be omitted.

Prior to explaining the apparatus and method for purifying ammonia using distillation of the present invention in detail, the present invention uses only the adsorption process generated when the adsorption process (zeolite, activated carbon, alumina, etc.), which is a conventionally applied process, is used. Purification to ultra high purity of 50ppb or less is quite difficult, and there is a risk of lowering quality due to deterioration of adsorption performance, increased investment cost required for the construction of two adsorption towers for continuous operation, and dust generated from the adsorbent itself. And the proposed technique to solve the problem of difficult to remove the particles (Particles).

The present invention is a process for purifying ultra-high purity ammonia using pure distillation theory using different volatilities of multi-component mixtures, and stopping operation for replacing adsorbents when reducing water removal performance according to adsorbent life. It is an optimal method considering the increase in investment cost of heater and the like required for the regeneration process and impurity nitrogen invasion which may be generated by using nitrogen.

As shown in FIG. 3, the apparatus and method for purifying ammonia using distillation according to the present invention stores liquid low-purity ammonia (about 99.5 to 99.8%) in a saturated liquid state of about 10 to 11 kg / cm 2 g and 30 ° C. In order to prevent the liquid gas ammonia from being liquefied according to the external temperature in winter by vaporizing saturated gas to the amount to produce the stored liquid ammonia, the pressure is reduced to about 9kg / cm²g and overheated. After a gas ammonia is produced, a flow control process is performed to control the exact flow rate.

At this time, the liquid ammonia, moisture and oil may be separated from each other due to the difference in density, which may cause water or oil to collect under the storage tank. Install under the storage tank as much as possible.

Since the capacity of the vaporizer heater is supplied with a low temperature when filling the raw ammonia, even in this case, a sufficient amount of heat is supplied to maintain a constant temperature. Here, two heaters were installed so that one was operated during normal operation and two heaters were operated when supplying raw ammonia from the tank lorry to the storage tank.

At this time, in the present invention, the quantity of the heater installed in the storage tank has been described as two, but it is preferable that the quantity of the heater is at least one or more depending on the capacity of the tank and other environments.

Meanwhile, the flow control valve and the pressure control valve are selectively installed on the ammonia supply pipe and the discharge pipe of the present invention to open and close the flow path for supplying and blocking ammonia, and the flow control valve and the pressure control valve are introduced with ammonia or When derived, it is configured to appropriately adjust for abrupt pressure changes or gas flow rates, so that the storage tanks and distillation towers, etc., are gradually closed to prevent damage or degradation. Each valve may also be actuated by pneumatic, hydraulic, or electrical signals.

4 shows an apparatus for removing high boiling point substances (mainly oil and water) in industrial low purity ammonia (NH 3) using a distillation process. Industrial low purity ammonia (NH 3) is a major impurity such as oil (oil) and water. It contains components such as (H 2 O), hydrogen (H 2), nitrogen (N 2), oxygen (O 2), and methane (CH 4). Among them, oil and water, which are high boiling point materials, were subjected to distillation separation using the Liquid-Vapor Equilibrium theory at an operating pressure of 7 kg / cm2g and an operating temperature of 16 to 17 ° C.

8 to 9 and Table 1 as a process simulation (Process Simulation) program ASPEN PLUS Ver. 7.3 was used, and the level of impurity oil was applied to the continuous distillation process to remove non-detectable levels and water below 50 ppb. The NRTL, Peng-Robinson and SRK (Soave-Redlich-Kwong) After verifying three equations, it is revealed that SRK is applied as shown in Table 2.

The operating condition is determined by the selected condition equation SRK. The relative volatilities of ammonia and water are different and the temperature and pressure can be used efficiently.

At this time, 300mm was applied to HETP (Height Equivalent to Theoretical Plate) for SS316 Flexipac 1.4Y Structured Packing, and the upper part of 11 stages of theoretical stages and the lower stage of 1 stages of theoretical stages and the reflux of circulation pumps were applied regularly. Reflux Ratio 0.3 was applied to successfully remove the high boiling point material.

The condenser has a condenser temperature of 16.8 ℃, and a cold energy source used to satisfy this is used a mixture of 40% Ethylene Glycol and 60% H2O. At this time, the operating temperature of the provided refrigerant is from 0 ℃ to 4 ℃. It was.

The distillation separation process may include a distillation column, a packing, a condenser, a condenser, a reflux drum, a reboiler, and a reflux pump.

The distillation column is applied to theoretical equation SRK and SS316 Flexipac 1.4Y Structured Packing, which is the theoretical stage, to select the fill height and to design the diameter of the distillation column by applying flooding factor 0.4 ~ 0.6. In order to apply a liquid distributor (Liquid Distributor).

The reflux container is designed to be prepared for fluctuations in flow rate of about 3 to 5 minutes in order to minimize instability that may occur due to fluctuations in operating flow and errors in the instrument. It is used to supply the ammonia liquid needed for contact and to transfer the liquid quantitatively to the next process.

Quality analysis was performed using Tiger Optics' MTO and HALO analyzers for the liquid phase after the circulating pump (measurement of the amount of water as impurities) and the liquid phase under the distillation column (measurement of the amount of concentrated water).

On the other hand, the HETP (Height Equivalent to Theoretical Plate) means the length of the separation tube corresponding to the theoretical singular or 1 theoretical stage.

HETP = L / n,

N (theoretical stage) = 16 x (tR / W) ² = 5.55 (tR / W½) ²

tR: Length from sample introduction point to peak maximum (remaining time)

W: The length of the baseline that the tangent cuts at the left and right inflection points of the peak.

5 shows an apparatus for removing low-boiling substances (hydrogen, nitrogen, oxygen, methane, etc.) in ammonia from which high-boiling substances (mainly oil and water) are removed by a distillation process, and connected in series with a high-boiling substance removing distillation column. Hydrogen (H2), nitrogen (N2), oxygen (O2), and methane (CH4), which are low-boiling materials, were used at the operating pressure of 7.0kg / cm2g and the operating temperature of 15.5 ~ 16.5 ℃. Distillation Separation is a continuous distillation process that removes nitrogen and other low boiling point substances below 10ppb.

At this time, the process simulation program is ASPEN PLUS Ver. 7.3 was used and three equations of NRTL, Peng-Robinson and SRK (Soave-Redlich-Kwong) were verified as a state equation applied to the continuous distillation process in which the impurity concentration of low boiling point substances was removed below 10 ppb. SRK was applied as shown in Table 2.

The operating conditions are determined by the selected state equation SRK, which is determined by temperature and pressure, which have a large difference in the relative volatilities of ammonia and INET materials, especially nitrogen and water, and can make efficient use of energy.

Filled SS316 Flexipac 1.4Y Structured Packing has 300mm HETP (Heavy Equivalent to Theoretical Plate), and the upper part applies theoretical number of stages and the third level of theoretical stages. Applied to successfully remove the low boiling point material. At this time, the reflux was supplied to the condenser while maintaining a certain level by using potential energy through height difference.

In addition, the distillation column was applied to theoretical equation SRK and SS316 Flexipac 1.4Y Structured Packing, which is the theoretical stage, to select the fill height and to design the diameter of the distillation column by applying the flooding factor 0.4 ~ 0.6. A Liquid Distributor was applied for the contact.

The refrigerant used as a cold energy source to maintain the condenser temperature at 16.3 ℃ was 40% Ethylene Glocol and 60% H2O. The operating temperature is 0 ℃ ~ 4 ℃. It was made.

Distillation process consists of a distillation column (Distillation Column), packing (Packing), condenser (Condenser), reboiler (Reboiler). At this time, the process of transferring the high purity liquid from the condenser to the distillation column is applied by the method of the difference of potential energy, and the quality analysis is the GOW-MAC Instrument for measuring the amount of impurities (hydrogen, nitrogen, oxygen, methane, etc.) under the distillation column. Gas Chromatograph was used.

6 is a liquid ultra high purity [UHP (Ultra High Purity), purity of more than 99.99999% and impurity moisture less than 50ppb] produced by the process drop the saturated liquid ammonia to the storage pressure 5.5kg / cm²g Joule-Thomson effect A certain amount of gas is generated. At this time, the generated gas condenses and condenses ammonia vaporized in the storage tank.

At this time, as the refrigerant used, it is possible to liquefy and store gaseous ammonia vaporized by external temperature using chilled water (Ethylene Glycol 4% + H2O 60%).

In addition, the investment tank was optimized by storing the storage tank as a single tank structure instead of a double tank.

At this time, the above-mentioned Joule-Thomson effect means that at room temperature and atmospheric pressure, all gases except hydrogen and helium are cooled when they are expanded. This phenomenon is often used to prepare liquid air or to liquefy the gas to keep the refrigerator low temperature. Hydrogen and helium refers to the cooling effect upon expansion only when their initial temperature is very low.

More specifically, if the actual gas, which is not an ideal gas, expands at constant enthalpy (no heat transfer to or from the gas, no external work, etc.), it is cooled by expansion or Can be heated.

Also known as the Joule-Thomson Coefficient, which is the time-dependent change in pressure and temperature in a Joule-Thomson process (ie constant enthalpy), this coefficient is the volume of the gas, the specific heat at a constant temperature (Cp). And in terms of the coefficient of thermal expansion is expressed as Table 3 below.

Where JT stands for Joule-Thomson and is usually omitted and uses only μ, and this coefficient varies with the gas type and the temperature and pressure values of the gas before expansion.

On the other hand, in the present invention, as shown in Figure 7, the boiling point at atmospheric pressure: -33 ° C and ammonia having a vapor pressure of 1MPa at 25 ° C is an external temperature and when installing a level gauge for viewing the liquid level, such as storage tanks or containers In order to solve the problem that it is difficult for the driver to check the liquid level through the level gauge, in this case, the level gauge is manufactured in the form of a jacket to allow the coolant to flow outside. The internal ammonia is prevented from vaporizing so that the liquid level can be easily checked from the outside.

On the other hand, in Figure 8, all of the processes of the present invention uses a program to perform special functions such as logic, sequencing, timing, counting, calculation, etc. through a digital or input / output module, not the operator's manual, Fully automatic construction using PLC (Programmable Logic Controller), a digital operation electronic device that controls the processor, and in case of an emergency, it is constructed to solve the emergency state automatically instead of the driver's operation.

This did not apply to the production of other ultrapure ammonia, but also ensures consistent production and quality at all times. In other words, the process parameters are automatically adjusted before moving out of the selected process elimination conditions so that constant operation is possible.

Those skilled in the art will appreciate that the present invention can be implemented in a modified form without departing from the essential features of the present invention. The described embodiments are not intended to limit the invention but to illustrate the invention. Therefore, those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

10 Storage tank unit 11 Low purity raw material storage tank
12 Heater 20 High boiling point material separator
21 High boiling point distillation column reboiler 22 High boiling point distillation column
23 High boiling point distillation column condenser 24 High boiling point distillation column reflux vessel
25 High boiling point distillation column circulation pump 30 Low boiling point material separator
31 Low boiling point distillation column reboiler 32 Low boiling point distillation column
33 Low boiling point distillation column condenser 40 Ultra-high purity storage tank
41 Ultra high purity condenser 42 Ultra high purity product storage tank
51 Flow control valve 52 Pressure control valve

Claims (5)

In the ultra high purity ammonia purification apparatus for purifying low purity ammonia to ultra high purity using distillation,
Low-purity raw material storage tank device including a low-purity raw material storage tank for storing the liquid ammonia in a saturated liquid state of 9 to 11kg / cm² pressure and 25 to 30 ℃ temperature, and a plurality of heaters provided below the storage tank. ;
The ammonia of the storage tank portion is connected to the pipe introduced and drawn out, a reboiler for heating and evaporating the liquid in the distillation column, a distillation tower for evaporating the ammonia component by the reboiler heating and a condenser for condensing the ammonia and condensed A high boiling point material separation device including a reflux container for collecting ammonia and a circulation pump for supplying ammonia liquid required for energy contact inside the distillation column; and
A low boiling point material separation device connected in series with the high boiling point material removal distillation column and including a reboiler for heating and evaporating the inside of the distillation column, a distillation column for evaporating the ammonia component by heating the reboiler, and a condenser for condensing the ammonia;
The ultra-high purity storage tank is installed with the reboiler of the low boiling point material separation device, the storage tank for condensing the generated gas through the condenser and condensing ammonia vaporized therein; distillation comprising a Purification apparatus of ammonia using. The method of claim 1,
The distillation column condensation temperature of the high boiling point material separation device and the low boiling point material separation device is 15 to 18 ℃, the operating temperature of the refrigerant is 0 to 4 ℃ refining apparatus using ammonia. The method of claim 1,
Filled SS316 (Flexipac 1.4Y Structured Packing) of the high boiling point material separation device HETP is applied 300mm, the upper stage 11 stages, the lower stage is applied to the theoretical stage of the first stage and the reflux constant circulation rate (Reflux Refining apparatus for ammonia using distillation, characterized in that the ratio 0.3 is applied. The method of claim 1,
Filler SS316 (Flexipac 1.4Y Structured Packing) of the low boiling point material separation device is HETP 300mm is applied, the upper stage of the first stage, the lower stage of the three stages of the theoretical stage characterized in that the purification of ammonia using distillation. In the ammonia purification method using distillation to purify ammonia into ultra-high purity ammonia using distillation,
Stores low-purity ammonia in a liquid state in a saturated liquid state, and vaporizes it in a saturated gas state to produce the stored liquid ammonia so that the pure gaseous ammonia is liquefied according to the external temperature to decrease the pressure to overheat. A first step for adjusting the exact flow rate after making the gas ammonia state of the;
A second step of distilling the low-purity ammonia of the first step from oil and water, which are high boiling point substances, by applying a gas-liquid equilibrium theory;
In order to remove the low boiling point material in the ammonia from which the high boiling point material was removed in the second step by distillation, the low boiling point material was connected in series with the high boiling point material removal distillation column to distill and separate the low boiling point material using gas-liquid equilibrium theory. A third step of removing the concentration of other low boiling point substances below 10 ppb;
When the liquid ultra-high purity saturated liquid ammonia produced through the second and third steps is dropped to a storage pressure of 5.5kg / cm2g, a certain amount of gas is generated by the Joule-Thomson effect according to the pressure drop, which condenses the generated gas. At the same time the fourth step of condensing the ammonia vaporized in the storage tank; Purification method of ammonia using distillation, characterized in that consisting of.

Images