KR100765409B1 - Apparatus and method for dissolved oxygen removal - Google Patents

Abstract

The present invention is to provide a dissolved oxygen removal apparatus and method, the water supply unit for receiving the water to remove the remaining impurities; Including the dissolved oxygen removal unit for receiving the water from the water supply unit to remove the dissolved oxygen with the degassing membrane membrane and metal-supported ACF module, by using the optimum combination of the degassing membrane membrane and metal-supported ACF at room temperature Will be almost completely eliminated.

Dissolved Oxygen, ACF, Membrane, Vacuum Pump, Hydrogen Generator, Removal, Degassing

Description

Apparatus and method for dissolved oxygen removal

1 is a process chart of a dissolved oxygen removal apparatus by a vacuum degassing method according to the related art.

2 is a process chart of a dissolved oxygen removing apparatus by a conventional heat degassing method.

Figure 3 is a block diagram of a dissolved oxygen removal apparatus according to an embodiment of the present invention.

4 is a detailed process diagram of FIG. 3.

FIG. 5 is a diagram illustrating an example in which a partition wall is installed in the metal-supported ACF module in FIG. 4.

FIG. 6 is a diagram illustrating an example of a membrane electrode assembly of a hydrogen generator in FIG. 4.

FIG. 7 is a graph showing dissolved oxygen removal efficiency at a 6ton / hr flow rate of the dissolved oxygen removing device of FIG. 3.

FIG. 8 is a graph showing dissolved oxygen removal efficiency at 15 ton / hr flow rate of the dissolved oxygen removing device of FIG. 3.

FIG. 9 is a graph showing dissolved oxygen removal efficiency at various flow rates at 6 bar pressure of the dissolved oxygen removing device of FIG. 3.

10 is a flowchart illustrating a dissolved oxygen removing method according to an embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

10: water supply unit 11: raw water supply pump (FP)

12: Free Filter 13: Flow Controller (HT)

14, 24, 29: dissolved oxygen measuring instrument (DO) 15, 26: thermometer (T)

16, 23, 27, 28: pressure gauge (PI) 20: dissolved oxygen removal unit

21: degassing membrane membrane 22: vacuum pump (VP)

25: dissolved hydrogen measuring instrument (DH) 30: metal support ACF module

31: partition 41, 42, 43, 44, 45, 46: valve

47, 48, 49: check valve 50: hydrogen generator (H2G)

51 membrane electrode assembly 60 control unit

The present invention relates to an apparatus for removing dissolved oxygen and a method thereof, and in particular, to almost completely remove dissolved oxygen in water even at room temperature by using an optimal combination of a degassing membrane membrane and a metal-supported activated carbon fiber (ACF). The present invention relates to an apparatus for removing dissolved oxygen and a method thereof.

In general, dissolved oxygen removal apparatus is used to prevent corrosion of metals by dissolved oxygen in nuclear power plant primary and secondary side water, various industrial boilers, cooling facilities, semiconductor manufacturing process, and the like.

Here, various gases such as oxygen, nitrogen, and carbon dioxide are dissolved in water in a certain ratio, and molecular oxygen dissolved in water is called dissolved oxygen. The following Table 1 shows the concentration of dissolved oxygen in water according to the water temperature, and contains about 8 to 10 ppm of dissolved oxygen at room temperature when exposed to the air, and the dissolved oxygen decreases gradually with increasing temperature of water. Known.

Dissolved Oxygen Concentration with Water Temperature Water temperature (℃) 10 21 32 43 54 66 77 88 99 Dissolved oxygen (ppm) 11.43 8.87 7.45 6.15 5.44 4.43 3.43 2.15 1.43

Dissolved oxygen, in addition to these properties, dissolves in the fluid and moves inside the metal pipe, causing corrosion through the oxidation of the inner wall of the pipe, causing turbidity of the water and shortening the life of the pipe.

In the case of a nuclear power plant, even in the presence of several ppb of dissolved oxygen in piping and grid water, it causes corrosion in the form of magnetite (Fe ₃ O ₄ ) at the fluid contact part of the system material, which shortens the life of the power plant such as material corrosion and radiation shielding ability. It has a serious impact on the safety of the nuclear power plant.

In order to solve such causes and problems, a degassing apparatus of dissolved oxygen in water of Korean Patent Application No. 1990-0011791 has been proposed to efficiently remove dissolved oxygen contained in water. The degassing device of dissolved oxygen in the water is a process in which the water filled in the degassing tank is discharged to the outside through the precipitation pipe to generate a vacuum pressure, and the water in the tank is introduced into the degassing tank through the water supply nozzle provided at the upper part of the degassing tank. Degassing is made to collect in the upper part of the degassing tank, the degassed oxygen is to be discharged to the outside by operating a vacuum pump, to obtain a certain amount of degassed water. However, this prior art is to stop the degassing in the process of supplying the water in the tank to the degassing tank by operating a separate pump to completely discharge the degassing oxygen remaining in the degassing tank to maintain the vacuum again. Accordingly, there was an inefficient problem of lowering the degassing rate.

Meanwhile, as another method for removing dissolved oxygen contained in water, an apparatus for removing dissolved oxygen in water by an activated carbon fiber catalyst of Korean Patent Application No. 10-1997-0052910 has been proposed. However, this also lowers the filtration rate in the ion exchange resin tower as the foreign substances removed from the treated water are trapped in the filtering device while water from which impurities in the treated water are removed as ions passes through the treated water filtering device and the turbidity component is removed. The inconvenience of having to clean the filtration device regularly was followed.

Looking at the conventional treatment method used in the current nuclear power plant in detail according to the type is as follows.

1. Mechanical degassing

a. Vacuum deaeration

Vacuum degassing is the most widely used method to remove dissolved oxygen in the feed water of nuclear power plants. The operating principle is to remove dissolved oxygen by spraying water from the top of the packed column maintained in vacuum to reduce the partial pressure of non-condensable gases. In order to improve the oxygen removal efficiency of the vacuum degassing apparatus, a packed tower may be installed in two or more stages.

1 is a process chart of a dissolved oxygen removal apparatus by a vacuum degassing method according to the related art.

Therefore, dissolved oxygen removal efficiency is affected by vacuum degree, packed tower size, inlet water temperature, etc. The packing is preferably of a large surface area per unit volume and determines the size of the packed column. Depending on the type of filling, the porosity in the tower and the differential pressure at the inlet and outlet change. There should be no elution of impurities from the packing used, and the vacuum of the device and the vacuum ejector should be maintained at a certain level so that oxygen, nitrogen and carbon dioxide can be sufficiently removed from the packed column. The amount of water vapor removed with non-condensable gases is affected by temperature and vacuum degree. Vacuum pump has watertight sealing and oiltight sealing method depending on the sealing method, but watertight sealing is adopted to avoid contamination by oil.

However, unlike the vacuum degassing method, the vacuum degassing method has the advantage of being able to operate independently regardless of the steam supply, but the initial installation cost is expensive, a large installation space is required, and the operation cost due to the vacuum pump operation ( In particular, electrical energy costs) are disadvantageous. Dissolved oxygen removal performance is about 30 ~ 40 ppb when the device is operating well, it is difficult to completely remove the dissolved oxygen (less than 10 ppb).

b. Thermal deaeration

Gas solubility in water is proportional to the partial pressure of the gas according to Henry's law. Therefore, the dissolved gas can be removed from the aqueous solution by lowering the partial pressure of the gas. In addition, the solubility of gas decreases with increasing temperature under the influence of temperature. By applying this principle, it is possible to remove dissolved gas by lowering the non-condensable gas partial pressure in water by heating the feed water with steam and mixing it with high-pressure steam in the heating degasser.

2 is a process chart of a dissolved oxygen removing apparatus by a conventional heat degassing method.

Thus, there is a spray chamber at the top of the heating degassing apparatus, in which a countercurrent contact between water and steam is made. Degassed water is stored in the bottom reservoir and fed to the boiler system. Dissolved oxygen can be lowered to less than 7 ppb in the deaerator during normal operation, but deoxygenation performance is reduced at stop or start without steam heat sources. The operation of the heating deaerator requires the proper supply of steam for optimal function and the normality of the heating deaerator should be checked by measuring the outlet temperature of the heating deaerator. In addition, it is necessary to design the reservoir to increase the residence time of the water and to retain as much water as possible so that the reaction between hydrazine and dissolved oxygen can proceed fully. Usually the temperature of the reservoir is operated within the range of 120 ~ 170 ℃, the reaction of hydrazine and dissolved oxygen easily occurs at this temperature, below the decomposition temperature of hydrazine. Therefore, by using a heating degassing machine with hydrazine can obtain an excellent degassing effect.

However, although the apparatus cost of the heating deaerator is not expensive, it requires a large installation space and has a disadvantage of requiring a large amount of energy by using a large amount of steam. In addition, there was also a problem such as the need to install additional auxiliary steam supply equipment for the operation of the heating degassing in the operation stop state.

2. Deoxygenation Treatment

a. Hydrazine

Hydrazine, the most widely used dissolved oxygen remover, is a colorless, ammonia-smelling pyrophoric liquid with hydrogen bonds that dissolves in solvents such as water, alcohol, and amines. Since hydrazine is a strong reducing agent, it is used not only as an anticorrosive agent for high temperature and high pressure boilers, but also for polymer foaming agents, agricultural pesticides, rocket fuels, and the like. If the concentration of N ₂ H ₄ is 63% or more, it may be ignited in the atmosphere. If it is less than 40%, it will not be ignited at a temperature of 100 ° C or less.

Reduction formula of the hydrazine and oxygen molecules is represented by the following formula (1).

N ₂ H ₄ + O _2- > N ₂ + 2H ₂ O (ΔH ^o = -586 kJ / mol)

Hydrazine has a great advantage that it does not generate impurities in water in a high temperature and high pressure boiler, so it is widely used as a treatment agent for energy and nuclear power plant.

However, these hydrazines are highly toxic and irritate the skin, eyes and respiratory system when inhaled in large amounts by the human body, and may cause damage to the lungs, liver and kidneys when repeatedly exposed. In Germany, the maximum allowable concentration in the air is set at 0.1 to 0.3 ppm for worker health.

b. Carbohydrazide

Carbohydrazide was commercialized in 1980 as a dissolved oxygen remover in boiler systems. Carbohydrazide is a white crystal that dissolves in the temperature range of 153 ~ 154 ℃. The solubility at 25 ° C. is 32 g / 100 ml_H ₂ O and shows excellent hydrolytic stability at around 100 ° C. The molecular formula of carbohydrazide is shown in the following formula (2).

O

∥

NH ₂ -NH-C-NH-NH ₂

In addition, the overall oxygen removal reaction formula is shown in the following formula (3).

(H ₂ N-NH) ₂ CO + 2O _2- > 2N ₂ + 3H ₂ O + CO ₂

Carbohydrazide can be used for boiler feedwater treatment because it decomposes into volatiles and does not increase electrical conductivity at high temperatures. When carbohydrazide is used, there is an anticorrosive action of metal surfaces in feedwater and plural systems, which greatly reduces the concentrations of iron and copper ions in boiler system water.

However, such carbohydrazide has a disadvantage in that the temperature of the water is very low at low temperature, so the dissolved oxygen is not removed and the water must be heated using a separate heat source.

3. Removal by membrane

Gas and liquid separation technology using membrane degassers can easily separate and remove dissolved oxygen, hydrogen, etc. from water, and thus have a wide range of applications such as power plants and semiconductors. Degassing itself is similar to vacuum degassing, which is a mechanical degassing method, but mechanical degassing is energy consuming because it uses a partial pressure difference at high temperatures, and it is impossible to perform sophisticated degassing. Therefore, it is known that the use of a degassing membrane can control the ppb level even with a small energy cost.

However, such membrane removal is not suitable in a continuous manner and has the disadvantage of maintaining a circulation cycle in a closed system.

As described above, the gas and liquid separation technology using the membrane degassing device can easily separate and remove dissolved oxygen, hydrogen, etc. from water, but there is a disadvantage in maintaining a circulation cycle in a closed system, and the mechanical degassing method at a high temperature. Since the degassing is carried out using a partial pressure difference, energy is consumed a lot and sophisticated degassing cannot be performed. The electrochemical catalytic reduction reaction has disadvantages such as high cost compared to high efficiency.

Accordingly, the present invention has been proposed to solve the conventional problems as described above, and an object of the present invention is to completely remove dissolved oxygen in water even at room temperature using an optimal combination of a degassing membrane membrane and a metal-supported ACF. Disclosed is an apparatus for removing dissolved oxygen and a method thereof.

Dissolved oxygen removal apparatus according to an embodiment of the present invention to achieve the above object,

A water supply unit receiving water to remove residual impurities; It is characterized in that the technical configuration consisting of a dissolved oxygen removal unit for receiving the water from the water supply unit to remove the dissolved oxygen to the degassing membrane membrane and the metal-supported ACF module.

Dissolved oxygen removal method according to an embodiment of the present invention to achieve the above object,

A first step of receiving water to remove residual impurities; And a second step of removing dissolved oxygen from the water with the degassing membrane membrane and the metal-supported ACF module after the first step.

Hereinafter, an embodiment according to the present invention as described above, a dissolved oxygen removing device and a method thereof will be described with reference to the accompanying drawings.

Figure 3 is a block diagram of a dissolved oxygen removal apparatus according to an embodiment of the present invention, Figure 4 is a detailed process of Figure 3, Figure 5 is a view showing an example in which the partition wall is installed in the metal support ACF module in FIG. 6 is a view showing an example of the membrane electrode assembly of the hydrogen generating portion in FIG.

3 and 4, the water supply unit 10 receives the water to remove the remaining impurities; Including a dissolved oxygen removal unit 20 for receiving the water from the water supply unit 10 to remove the dissolved oxygen with the degassing membrane membrane 21 and the metal-supported ACF (Activated Carbon Fiber) module 30 Characterized in that configured.

The water supply unit 10 includes a feeder pump (FP) 11 for supplying water; A free filter 12 for removing residual impurities from the water supplied through the feed water pump 11; A flow controller (HT) 13 for measuring and controlling a set flow rate of the water passing through the prefilter 12; A dissolved oxygen meter (DO) 14 for measuring dissolved oxygen of the water passing through the prefilter 12; A thermometer (T) 15 for measuring the temperature of the water passing through the prefilter 12; It is characterized in that it comprises a pressure gauge (Pressure Indicator, PI) 16 for measuring the pressure of the water passing through the pre-filter 12.

The dissolved oxygen removing unit 20 is characterized in that the degassing membrane membrane 21 and the metal-supported ACF module 30 is configured to be combined in series.

The dissolved oxygen removal unit 20 is characterized in that the dissolved oxygen removal sharing capacity by the degassed membrane membrane 21 and the metal-supported ACF module 30 is 8: 2.

The dissolved oxygen removal unit 20 includes: a degassing membrane (21) for removing dissolved oxygen by receiving water from the water supply unit 10; A vacuum pump (VP) 22 connected to the degassing membrane membrane 21 to remove dissolved oxygen from the water supplied to the degassing membrane membrane 21 according to Henry's law on gas; A metal-supported ACF module 30 for removing dissolved oxygen from the water passed through the degassing membrane membrane 21; Dissolved oxygen measuring instruments (DO) (24, 29) for measuring the dissolved oxygen of the water in the dissolved oxygen removing unit 20; Dissolved hydrogen meter (DH) (25) for measuring the hydrogen of the water in the dissolved oxygen removal unit 20; A thermometer (T) 26 for measuring the temperature of the water in the dissolved oxygen removing unit 20; A pressure gauge (PI) (23, 27, 28) for measuring the pressure of the water in the dissolved oxygen removing unit 20; It is characterized in that it comprises a valve 41, 42, 43, 44, 45, 46 and the check valve 47, 48, 49 for controlling the flow of water in the dissolved oxygen removal unit 20.

The metal-supported ACF module 30, as shown in Figure 5, characterized in that it comprises a partition 31 that can relieve high pressure when water is introduced.

The dissolved oxygen removal apparatus, as shown in Figure 3 and 4, further comprises a hydrogen generator (H ₂ Generator, H2G) (50) for generating hydrogen to provide the dissolved oxygen removal unit 20 Characterized in that configured.

The hydrogen generator 50 is connected between the degassing membrane brain 21 and the metal-supported ACF module 30 in the dissolved oxygen removing unit 20 to supply hydrogen.

As illustrated in FIG. 6, the hydrogen generator 50 generates hydrogen using a membrane electrode assembly (MEA) 51 having a pressure resistance.

3 and 4, the dissolved oxygen removing device is connected to the water supply unit 10 and the dissolved oxygen removal unit 20, to monitor the water quality of the water, the water supply unit 10 And a control unit 60 for controlling the operation of the dissolved oxygen removing unit 20.

The controller 60 may measure measured values of the flow controller (HT) 13 and the dissolved oxygen measuring unit 14 in the water supply unit 10, and the dissolved oxygen measuring units 24 and 29 in the dissolved oxygen removing unit 20. And performing automatic recording of the measured value of the dissolved hydrogen measuring device (DH) 25 for each preset time and displaying the generation capacity of hydrogen as a reducing agent.

10 is a flowchart illustrating a dissolved oxygen removing method according to an embodiment of the present invention.

As shown therein, a first step (ST1) of supplying water to remove residual impurities; After the first step, a degassing membrane membrane 21 and a metal-supported ACF module 30 may be used to remove dissolved oxygen from the water (ST2, ST3, ST4).

In the second step, the dissolved oxygen removal sharing capacity of the degassing membrane membrane 21 and the metal-supported ACF module 30 is 8: 2.

The second step may include a third step (ST2) of removing dissolved oxygen from water with the degassing membrane membrane (21) after the first step; A fourth step (ST3) of supplying hydrogen to the water from which dissolved oxygen has been removed to the degassing membrane membrane (21) in the third step; And a fifth step (ST4) of removing dissolved oxygen from the water supplied with hydrogen in the fourth step with the metal-supported ACF module 30.

Referring to the accompanying drawings of the dissolved oxygen removal apparatus and the method according to the present invention configured as described above in detail as follows.

First, the present invention intends to almost completely remove dissolved oxygen in water even at room temperature by using an optimal combination of a degassing membrane and a metal-supported ACF.

Therefore, the present invention minimizes the occurrence of corrosion of metal pipes by extremely removing dissolved oxygen in water of industrial boilers and power plant systems, thereby prolonging the life of devices and facilities, and in particular, of nuclear power plants that cannot be tolerated even small accidents. The removal performance of dissolved oxygen to ensure safe operation is perfect.

To this end, the present invention comprises a water supply unit 10 and the dissolved oxygen removal unit 20. In addition to this, the hydrogen generating unit 50 or the control unit 60 may be added.

Thus, the water supply unit 10 receives water to remove residual impurities.

In the water supply unit 10, the water supply pump 11 causes the water to be supplied into the water supply unit 10 to move the water to the prefilter 12.

The prefilter 12 removes residual impurities from the water supplied through the feed water pump 11 so that the impurities are primarily filtered.

In addition, the flow controller 13 measures and controls the set flow rate of the water passing through the prefilter 12. At this time, the control operation may be performed under the control of the controller 60.

In addition, the dissolved oxygen measuring unit 14 measures the dissolved oxygen of the water passing through the prefilter 12. And the measured value is transmitted to the control unit 60 so that the water quality monitoring and control can be performed.

In addition, the thermometer 15 measures the temperature of the water passing through the prefilter 12. At this time, the measured temperature is transmitted to the controller 60 so that water quality monitoring and control can be performed.

In addition, the pressure gauge 16 measures the pressure of the water passing through the prefilter 12. At this time, the measured pressure is transmitted to the control unit 60 so that water quality monitoring and control can be performed.

Meanwhile, the dissolved oxygen removing unit 20 receives water from the water supply unit 10 to remove dissolved oxygen with the degassing membrane membrane 21 and the metal-supported ACF module 30.

In this case, the dissolved oxygen removing unit 20 may be configured such that the degassing membrane membrane 21 and the metal-supported ACF module 30 are combined in series. In addition, the degassing membrane membrane 21 and the metal-supported ACF module 30 may be configured to be combined in parallel. Of course, if the degassing membrane membrane 21 and the metal-supported ACF module 30 are configured to be combined in parallel, water passes through only one, and thus the dissolved oxygen removal efficiency is reduced, but may be used where a low dissolved oxygen removal effect is required. have.

The dissolved oxygen removing unit 20 may set the dissolved oxygen removing allocating capacity by the degassing membrane membrane 21 and the metal-supported ACF module 30 to 8: 2. These sharing capacities can be set to other values.

Thus, the degassing membrane membrane 21 in the dissolved oxygen removal unit 20 receives water from the water supply unit 10 to remove dissolved oxygen.

The vacuum pump 22 is also connected to the deaeration membrane 21 to remove dissolved oxygen from the water supplied to the deaeration membrane 21 according to Henry's law for gas.

The metal-supported ACF module 30 removes dissolved oxygen from the water passing through the degassing membrane membrane 21. At this time, when the hydrogen generating unit 50 is installed between the degassing membrane membrane 21 and the metal-supported ACF module 30, the deoxidizing membrane 21 is a reducing agent in the water from which dissolved oxygen is removed at a rate of 8/10. Hydrogen is added. Then, the metal-supported ACF module 30 removes the remaining dissolved oxygen in the remaining 2/10 of the water to which hydrogen is added as a reducing agent.

In addition, the metal-supported ACF module 30 includes a partition wall 31 to relieve the high pressure (eg, 8 kg / cm 2) when the water in which hydrogen is dissolved flows in.

In addition, the dissolved oxygen measuring device of reference numeral 24 measures the dissolved oxygen of the water directly passing through the degassing membrane membrane 21 or to which hydrogen is added by the hydrogen generator 50. And the measured value can be transmitted to the control part 60.

In addition, the dissolved oxygen measuring device of reference number 29 measures the dissolved oxygen of the water passing through the metal-supported ACF module 30. And the measured value can be transmitted to the control part 60.

The dissolved hydrogen measuring device 25 measures the hydrogen of the water to which hydrogen is added by the hydrogen generating unit 50. And the measured value can be transmitted to the control part 60.

In addition, the pressure gauges 23, 27 and 28 measure the water temperature at each point in the dissolved oxygen removing unit 20. The measured value can then be transmitted to the control unit 60. L

In addition, the valves 41, 42, 43, 44, 45, 46 and the check valves 47, 48, and 49 provided at the respective points in the dissolved oxygen remover 20 are used to control the flow of water in the dissolved oxygen remover 20. To control.

Meanwhile, the hydrogen generating unit 50 generates hydrogen to provide hydrogen to the dissolved oxygen removing unit 20. The hydrogen generating unit 50 generates hydrogen using the membrane electrode assembly 51 designed for breakdown voltage.

In addition, the controller 60 is connected to the water supply unit 10 and the dissolved oxygen removal unit 20 to monitor the water quality of the water, and to control the operation of the water supply unit 10 and the dissolved oxygen removal unit 20. Thus, the control unit 60 measures the measured values of the flow controller (HT) 13 and the dissolved oxygen measuring unit 14 in the water supply unit 10, and the dissolved oxygen measuring units 24 and 29 and the dissolved hydrogen side in the dissolved oxygen removing unit 20. The measured value of the periodic (DH) 25 is automatically recorded for each preset time, and the generation capacity of hydrogen as a reducing agent is displayed.

Referring back to the overall operation of the present invention as follows.

As such, the water supplied to the water supply unit 10 through the inlet is transferred into the water supply unit 10 through the water supply pump 11, and the remaining impurities are primarily filtered out of the prefilter 12 and the flow controller The set flow rate is measured at 13, and after measuring the dissolved oxygen in the dissolved oxygen measuring instrument 14, the degassed membrane membrane 21 in the dissolved oxygen removing unit 20 is passed through the thermometer 15 and the pressure gauge 16. Will be transferred to.

The water supplied to the dissolved oxygen removal unit 20 is first supplied to the degassing membrane membrane 21 and dissolved in the degassing membrane membrane 21 by Henry's Law by the vacuum pump 22. Oxygen is removed and partly enters the hydrogen generating unit 50 by the valves 43 and 44 divided into two branches after the pressure gauge 23, and is mixed with the hydrogen to exit through the check valve 48. It is mixed with water coming out through 44). Thereafter, the dissolved oxygen measuring device 24, the dissolved hydrogen measuring device 25, the temperature 26, and the pressure gauge 27 are measured before being transferred to the metal-supported ACF module 30. % Of dissolved oxygen is removed while passing through the metal-supported ACF module 30, and once again finally passed through the pressure gauge 28 and dissolved oxygen measuring instrument 29, the final result is measured and discharged through the outlet (Outlet) .

On the other hand, the high efficiency dissolved oxygen removal effect of the present invention is very important for the smooth control and solubility of hydrogen. In the present invention, while using hydrogen as a reducing agent of the metal catalyst of the high-efficiency dissolved oxygen removal device, the hydrogen generator 50 has been developed and equipped with more safe and simple control. Assuming that the flow rate of water is 6 ton / hr (100 L / min), the required amount of hydrogen as the oxygen reducing agent is expressed by the following equation (1).

Pg = Hxg

Here, the equilibrium, or saturation, of the gas dissolved in the liquid is a function of the fractionation of the gas in contact with the liquid. (This relationship is called Henry's law.)

In addition, each meaning is as follows.

Pg: partial pressure of gas, atm

H: henry constant, atm / mol fraction

Xg: Mole fraction of gas, mol gas (ng) / (mol gas (ng) + mol water (nw))

Where the H Henry's constant is a function of the type, temperature and composition of the liquid. Henry's constants of hydrogen and oxygen are shown in Table 2 below.

Henry's Constant with Temperatures of Hydrogen and Oxygen H ㅧ 10 ^-4 , atm / mol fraction T, ℃ H ₂ O ₂ 0 5.79 2.55 10 6.36 3.27 20 6.83 4.01 30 7.29 4.75 40 7.51 5.35 50 7.65 5.88 60 7.65 6.29

1. Hydrogen Solubility

Assuming that the proportion of hydrogen droplet hydrogen is 100%, the partial pressure of hydrogen in the droplet is P _H2 = 8 kg / cm 2 × 1 = 8 kg / cm 2.

If 8 kg / cm 2 is corrected in atm, it is 7.74 atm. The Henry's constant of hydrogen gas at liquid 15 ° C is 6.61 × 10 4 atm / mol fraction as shown in Table 2 above.

2. Calculation of the concentration of hydrogen gas (ppm)

Thus, Equation 2 is equal to Equation 3.

This results in the following equation (4).

In addition, since 1L of water is 1000/18 = 55.6 mol, the following Equations 5 to 7 are derived.

Therefore, when the water pressure is 8 kg / cm 2 and the water temperature is 15 ° C, the hydrogen concentration becomes 13 ppm as in Equation (7).

3. The amount of oxygen to remove and the amount of hydrogen to provide

The experimental flow rate of the pump installed in the device is 100 L / min. In addition, in the degassing membrane type hydrogen removing apparatus (Demiwater) in front of the hydrogen generating unit 50 to remove 6 ppm to 8 ppm-> 2 ppm. Therefore, assuming that 2 ppm should be removed from the hydrogen removal reactor 50 using a metal catalyst, which is a post-process, the total amount of oxygen to be removed is expressed by Equation 8 below.

So, as in Equation 8, it is necessary to remove 200 mg of oxygen per minute.

If 200mg / min is converted into moles, the following equation (9) is obtained.

의 양을 촉매 반응을 통하여 물로 전환하기 위한 수소의 몰수는 2배인 0.0125 mol/min 이다. 이 양은 25 mg/min 으로 산소를 제거하기 위해 공급해야 할 수소의 양은 분당 25 mg 의 수소가 필요하다.Oxygen

The number of moles of hydrogen for converting the amount of water into water through a catalytic reaction is 0.0125 mol / min, which is twice. This amount is 25 mg / min, and the amount of hydrogen supplied to remove oxygen requires 25 mg of hydrogen per minute.

In conclusion, the required 25 mg / min of hydrogen is 0.25 ppm at 100 L / min of operating flow.

4. The amount of hydrogen produced at the hydrogen generator

I = m × z × F / (t × M × η)

Here, each meaning in Equation 10 is as follows.

m: mass (g)

z: ion electron

F: Faraday constant (96485 mol / c)

t: time (sec)

M: molecular weight (g / mol)

η: Efficiency (actual generation amount / theoretical generation amount)

mol = m / M

Thus, the number of moles of hydrogen generated in unit time in Equation 11 is as shown in Equations 12 to 14 under the following conditions.

Working current: 50A

Current efficiency: 0.9 (assumed hydrogen production efficiency using MEA)

That is, as shown in Equation 14, the number of moles of hydrogen generated in unit time is 27.96 mg / min.

<Example 1>

In order to evaluate the effect on the dissolved oxygen dissolved in water using the dissolved oxygen removal apparatus of the present invention was carried out as follows.

-Water to be used: pure water (resistance = 18MΩ · cm, water temperature 20 ℃)

Flow rate: 6 ton / hr

System pressure: 6 bar

Initial dissolved oxygen concentration: 8 ppm

-Degassing Membrane: CELGARD G333

-Platinum (Pt) supported ACF module: 20 platinum supported modules of 2 wt%

-Operation condition: Once-through, discharged from 10 ton water storage tank to water supply of dissolved oxygen removal device and discharged after dissolved oxygen removal process

Dissolved oxygen removal efficiency results of the dissolved oxygen removal device in Example 1 are shown in Figure 7 and Table 3.

FIG. 7 is a graph showing dissolved oxygen removal efficiency at a 6ton / hr flow rate of the dissolved oxygen removing device of FIG. 3.

As a result, it showed high removal efficiency over 99.9% on average and reached stable efficiency of 99% within 4 minutes of operation.

Dissolved oxygen removal efficiency over time Elapsed time (min) Primary experiment removal efficiency (%) Secondary 3rd 4th 0 0 0 0 0 2 80.96633 83.17544 63.42593 97.67222 4 95.38799 94.57895 89.90741 97.94444 6 98.06735 99.1193 97.63889 98.01667 8 98.84334 98.67368 98.71605 98.04444 10 99.21816 98.96667 99.17747 97.92778 12 99.36018 99.10351 99.39506 98.12778 14 99.48902 99.19825 99.47685 98.1 16 99.52269 99.3193 99.54938 97.96667 18 99.5798 99.40877 99.58796 97.99444 20 99.5798 99.48772 99.86667 97.98889 22 99.61493 99.54386 99.78827 98.18333 24 99.98419 99.54737 99.80679 98.03889 26 99.96515 99.86842 99.91142 98.25 28 99.92518 99.97193 99.92222 98.27222 30 99.9754 99.90351 99.92994 98.26111 32 99.9388 99.95614 99.93765 98.21111 34 99.94319 99.96316 99.95463 98.32778 36 99.99048 99.92632 99.92716 98.26667 38 99.96018 99.98947 99.97778 98.17222 40 99.947 99.91228 99.93858 98.25556

FIG. 8 is a graph showing dissolved oxygen removal efficiency at 15 ton / hr flow rate of the dissolved oxygen removing device of FIG. 3. That is, the result of testing the dissolved oxygen removal efficiency of the dissolved oxygen removal apparatus by giving a change of pressure was shown.

At 1, 3, and 6 bar, respectively, the higher the pressure, the higher the dissolved oxygen removal efficiency. At higher pressures, the solubility of hydrogen generated in the system is increased, which results in an increase in the activity of hydrogen as a reducing agent, which in turn affects the efficiency of dissolved oxygen (DO) removal.

<Example 2>

In order to evaluate the effect on the dissolved oxygen dissolved in water at various treatment flow rates using the apparatus of the present invention was performed as follows.

-Water to be used: pure water (resistance = 18MΩ · cm, water temperature 20 ℃)

Flow rate: 3 ton / hr to 15 ton / hr

System pressure: 6 bar

Initial dissolved oxygen concentration: 8 ppm

-Degassing Membrane: CELGARD G333

-Platinum (Pt) supported ACF module: 20 platinum supported modules of 2 wt%

-Operation condition: Once-through, discharged from 10 ton water storage tank to water supply of dissolved oxygen removal device and discharged after dissolved oxygen removal process

FIG. 9 is a graph showing dissolved oxygen removal efficiency at various flow rates at 6 bar pressure of the dissolved oxygen removing device of FIG. 3.

The pressure in the system was changed to the flow rate of 3, 6, 9, 12, and 15 ton / hr, respectively.

The results are shown in Table 4 below.

Dissolved Oxygen Removal Efficiency According to Flow Rate Elapsed time (min) 3 ton / hr removal efficiency (%) 6 ton / hr removal efficiency (%) 9 ton / hr removal efficiency (%) 12 ton / hr removal efficiency (%) 15 ton / hr removal efficiency (%) 0 0 0 0 0 0 2 85.93496 80.45113 78.95288 77.38589 74.91228 4 94.47154 88.27068 89.29319 84.83402 84.5614 6 96.99187 93.73434 92.27749 90.04149 88.90351 8 97.59756 97.2782 96.7801 92.28216 91.88596 10 98.49797 98.53885 98.09162 94.70954 94.73684 12 98.92683 99.0802 98.75654 97.32365 95.65351 14 99 99.34837 99.01832 97.32365 96.83772 16 99.20732 99.46867 99.26178 96.74274 97.76316 18 99.36992 99.5589 99.38482 97.32365 98.30263 20 99.31301 99.57143 99.46335 97.56432 98.39035 22 99.39634 99.61404 99.5288 98.12656 98.63596 24 99.91243 99.91536 99.57853 98.44606 98.76754 26 99.98423 99.89126 99.6178 98.62241 98.7807 28 99.52439 99.94753 99.84561 98.69917 99.94235 30 99.95231 99.96243 99.94301 99.92604 99.94264

As shown in the results shown in Table 4, the higher the operating flow, the longer it took for the efficiency to stabilize, but after approximately 6 minutes after the start of operation, the efficiency was maintained at 90% or higher at all flow conditions. Since then, the removal efficiency at all conditions has remained stable and consistently over 99%.

As a result of evaluating dissolved oxygen (DO) removal efficiency through the above two examples, the removal efficiency of 99.9% or more showed very excellent removal efficiency. At this time, the removal efficiency by the temperature was hardly affected, and it was confirmed that the amount of hydrogen supplied to maintain the activity by preventing oxidation of the metal catalyst was a very important variable.

As such, the present invention almost completely removes dissolved oxygen in water even at room temperature by using an optimal combination of a degassed membrane and a metal-supported ACF.

Although the preferred embodiment of the present invention has been described above, the present invention may use various changes, modifications, and equivalents. It is clear that the present invention can be applied in the same manner by appropriately modifying the above embodiments. Therefore, the above description does not limit the scope of the invention defined by the limitations of the following claims.

As described above, the dissolved oxygen removing apparatus and the method according to the present invention have an effect of almost completely removing dissolved oxygen in water even at room temperature by using an optimal combination of a degassing membrane membrane and a metal-supported ACF.

At present, the system deaeration is used in combination with artificial level control of the volume control tank and mechanical degassing using vacuum. In advanced countries, instead of using chemicals to remove dissolved oxygen from feedwater and system water produced by nuclear power plants, dissolved oxygen is removed using catalyst-supported ion exchange resins or degassing membranes. It is operating the catalyst-supported ion exchange resin removal device, which is protected under the technology of Westinghouse (US). However, such equipment has very high dissolved oxygen removal efficiency, but the device is not only large but also has a disadvantage of having to pay a patent fee. In the case of occupying%, it will be able to obtain enormous economic effect by increasing utilization rate through improving operation safety of operating nuclear power plant. Also, dissolved oxygen removal device by ideal combination of degassing membrane and ACF is the cause of corrosion in main pipe of nuclear power plant. In addition to the removal of oxygen, it is believed that there will be some effects on the removal of radioactive gas, and due to its advantages in terms of economics and efficiency, it is expected to be highly applicable.

Claims (14)

A water supply pump for supplying water; A pre-filter for removing residual impurities from the water supplied through the feed water pump; A flow controller for measuring and controlling a set flow rate of water passing through the prefilter; Dissolved oxygen measuring device for measuring the dissolved oxygen of the water passed through the pre-filter; A thermometer measuring the temperature of the water passing through the prefilter; A water supply unit configured to include a pressure gauge measuring a pressure of water passing through the prefilter; Dissolved oxygen removal device comprising a dissolved oxygen removal unit for receiving the water from the water supply unit to remove the dissolved oxygen to the degassing membrane membrane and the metal-supported ACF module. delete The method according to claim 1, wherein the dissolved oxygen removing unit, Dissolved oxygen removing device, characterized in that configured to combine the degassing membrane membrane and the metal-supported ACF module in series. The method according to claim 1, wherein the dissolved oxygen removing unit, Dissolved oxygen removal unit by the degassing membrane membrane and the metal-supported ACF module, the dissolved oxygen removal device, characterized in that 8: 2. The method according to claim 1, wherein the dissolved oxygen removing unit, A degassing membrane membrane for receiving dissolved water to remove dissolved oxygen; A vacuum pump connected to the degassing membrane to remove dissolved oxygen from the water supplied to the degassing membrane according to Henry's law on gas; A metal-supported ACF module for removing dissolved oxygen from water passed through the degassing membrane; A dissolved oxygen measuring device for measuring dissolved oxygen of the water in the dissolved oxygen removing unit; A dissolved hydrogen measuring device for measuring hydrogen of the water in the dissolved oxygen removing unit; A thermometer measuring a temperature of water in the dissolved oxygen removing unit; A pressure gauge for measuring the pressure of the water in the dissolved oxygen removing unit; Dissolved oxygen removal device comprising a check valve and a valve for controlling the flow of water in the dissolved oxygen removal unit. The method of claim 5, wherein the metal-supported ACF module, Dissolved oxygen removal device characterized in that it comprises a partition that can relieve high pressure when water is introduced. The dissolved oxygen removing device according to any one of claims 1 to 3, wherein Dissolved oxygen removal device characterized in that it further comprises a hydrogen generating unit for generating hydrogen to provide to the dissolved oxygen removal unit. The method according to claim 7, wherein the hydrogen generating unit, Dissolved oxygen removal device characterized in that the hydrogen supply is connected between the degassing membrane brain and the metal-supported ACF module in the dissolved oxygen removal unit. The method according to claim 7, wherein the hydrogen generating unit, Dissolved oxygen removing device, characterized in that for generating hydrogen using a pressure-resistant designed membrane electrode assembly. The method according to claim 7, wherein the dissolved oxygen removing device, And a control unit connected to the water supply unit and the dissolved oxygen removal unit, configured to monitor the water quality of the water and to control the operation of the water supply unit and the dissolved oxygen removal unit. The method of claim 10, wherein the control unit, And automatically recording the measured values of the flow controller and the dissolved oxygen meter in the water supply unit, the measured values of the dissolved oxygen meter and the dissolved hydrogen meter in the dissolved oxygen removing unit for each preset time, and displaying the generation capacity of hydrogen as a reducing agent. Dissolved oxygen removal device, characterized in that performing. The first step of supplying water to remove residual impurities, After the first step, the dissolved oxygen is removed from the water with the degassing membrane membrane and the metal-supported ACF module, and the second step of dissolving oxygen removal capacity by the degassing membrane and the metal-supported ACF module is 8: 2. Dissolved oxygen removal method characterized in that it comprises a. delete The method of claim 12, wherein the second step, A third step of removing dissolved oxygen from water with the degassing membrane after the first step; A fourth step of supplying hydrogen to the water from which dissolved oxygen has been removed from the third step in the degassing membrane; And a fifth step of removing dissolved oxygen from the water supplied with hydrogen in the fourth step with the metal-supported ACF module.

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