KR200436513Y1 - A Compact Type High Efficient System for Dissolved Oxygen Removal - Google Patents

Abstract

The present invention relates to an integrated dissolved oxygen removal device, the configuration is a reservoir for desalination water; A pretreatment filter for filtering the treated water discharged from the reservoir; And a degassing membrane for primaryly removing dissolved oxygen in the treated water supplied from the pretreatment filter, and an dissolved oxygen having integrally activated carbon fibers for secondaryly removing the dissolved oxygen from the water discharged from the degassing membrane. It comprises a; removing means.

According to the present invention, while maintaining the efficiency of the high efficiency hybrid dissolved oxygen removal device while maintaining the integrated module through the simplification of the process there is an effect that can increase the applicability and ease of maintenance.

Dissolved oxygen, treated water, degassing membrane, dissolved oxygen removal device

Description

A Compact Type High Efficient System for Dissolved Oxygen Removal}

1 is a block diagram showing a dissolved oxygen removal apparatus of the present invention.

2 is a cross-sectional view showing the dissolved oxygen removing means shown in FIG.

Figure 3 is a block diagram showing another embodiment of the dissolved oxygen removal apparatus of the present invention.

Figure 4 is a graph showing the dissolved oxygen concentration change in the inlet and outlet side dissolved oxygen removal apparatus of the present invention.

5 is a graph showing the dissolved oxygen concentration change and removal rate according to the operating time of the dissolved oxygen removal apparatus of the present invention.

<Explanation of symbols for the main parts of the drawings>

10: dissolved oxygen removing apparatus 20: reservoir

30: pretreatment filter 40: dissolved oxygen removal means

41 housing 42: degassing membrane

43: activated carbon fiber 44: water inlet

45: hydrogen supply port 46: vacuum exhaust port

47: injection nozzle 50: valve

60 control module

The present invention relates to an integrated dissolved oxygen removal device, and more particularly, to maintain the efficiency of the high efficiency hybrid dissolved oxygen removal device while maintaining the efficiency of the integrated module by simplifying the process while increasing the applicability and convenience of maintenance. An integrated dissolved oxygen removal device is provided.

The method used to remove dissolved oxygen in the current power plant is as follows.

1. Physical dissolved oxygen removal method

Physical dissolved oxygen removal method is a method of using only the change in the physical properties of oxygen according to the operating conditions without accompanying chemical reactions. Lowering the pressure or increasing the temperature lowers the solubility of oxygen, which can be used to remove dissolved oxygen.

a. Thermal Deaeration

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 in a heating degasser and mixing it with high pressure steam. At the top of the heating deaerator there is a spray chamber where countercurrent contact between water and steam occurs. Degassed water is stored in the lower reservoir and then supplied to the boiler system. Dissolved oxygen can be lowered to 7 ppb or less in the deaerator during normal operation, but the oxygen removal capacity is significantly reduced when starting or stopping without a steam heat source. 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. Normally, the temperature of the reservoir is operated within the range of 120 ~ 170 ℃. At this temperature, the reaction of hydrazine and dissolved oxygen easily occurs and is below the decomposition temperature of hydrazine. Therefore, when the heating degassing apparatus is used together with the hydrazine, excellent degassing effect can be obtained. Although the equipment cost of the heating degassing apparatus is not expensive, it requires a large installation space and high energy costs due to the use of a large amount of water vapor. In addition, there is a problem that requires the installation of additional steam supply equipment for the operation of the heating degassing in the operation stop state.

b. Vacuum Deaeration

To date, it is the most applied method to remove dissolved oxygen in power supply of power plant. 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. Using this method, the dissolved oxygen is removed by reducing the partial pressure of the non-condensable gas by spraying water from the upper part of the packed column maintained in vacuum. In order to increase the dissolved oxygen removal rate of the vacuum degassing process, a packed tower may be installed in two or more stages. Dissolved oxygen removal rate is affected by vacuum level, packed tower size, operating temperature, etc. Fillings preferably have a large specific surface area and influence the size of the packed column. Unlike the degassing method, the vacuum degassing method has the advantage of being able to operate independently regardless of steam supply, but the initial installation cost is expensive, a large installation space is required, and the energy consumption is high due to the operation of a vacuum pump. There are disadvantages. Dissolved oxygen removal performance is good at 30 ~ 40 ppb when the device is operated well, but it is difficult to completely remove it to maintain less than 10 ppb dissolved oxygen.

c. Membrane Deaeration

Membrane degassing device is a device that can use the hydrophobic membrane to prevent the aqueous solution from contacting the membrane while allowing the gas to pass freely, effectively separating and removing the dissolved gas from the aqueous solution. The hydrophobic membrane functions to separate the liquid phase and the gas phase well between the fine pores of the membrane and at the same time serves as a support for forming the flow path. Water flows through one side of the hydrophobic membrane and a vacuum is applied on the other side of the membrane to remove dissolved oxygen from the aqueous solution through the membrane's longitudinal section. At this time, water cannot pass through the membrane due to the hydrophobicity of the degassing membrane. Therefore, the membrane degassing method has the advantage of low energy consumption and removal of dissolved oxygen up to the ppb level.

2. Chemical dissolved oxygen removal method (deoxidant treatment method)

The chemical dissolved oxygen removal method is a method of removing and replacing oxygen with another compound through chemical reaction by adding an additive called deoxidant. The final product form of oxygen is usually water. At this time, it can be classified as follows according to the type of deoxidant or additive.

a. Hydrazine (N ₂ H ₄ )

Colorless hydrazine with ammonia odor is the most frequently used as a dissolved oxygen removal chemical as a flammable liquid. Hydrazine has a hydrogen bond, so it is easily dissolved in a solvent such as water, alcohol, amine, etc., so it is convenient to use. 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 blowing agents, agricultural pesticides, and rocket fuels. If the hydrazine concentration is 63% or more, it may be ignited in the atmosphere, but if it is less than 40%, it will not be ignited at a temperature below 100 ° C. The reduction reaction of hydrazine and oxygen molecule is as follows.

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, there is a disadvantage that strong toxicity to the human body, if inhaled irritate the skin, eyes, respiratory system, may cause damage to the lungs, liver, kidneys when repeated exposure. In Germany, the maximum allowable concentration in the atmosphere is set at 0.1 to 0.3 ppm for the health of workers.

b. Carbohydrazide

Carbohydrazide, commercialized as a dissolved oxygen remover in boiler systems in 1980, is a white crystal that dissolves and decomposes in the temperature range of 153-154 ° C. The solubility at 25 ° C. is 32 g / 100 ml-H ₂ O and shows good hydrolytic stability at around 100 ° C. The molecular formula of carbohydrazide is as follows.

            O

            ∥

NH ₂ -NH-C-NH-NH ₂

The overall equation of oxygen removal is as follows.

(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 at high temperatures and does not increase the conductivity. 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, since the reaction rate is very slow at a low temperature of the water and there is no dissolved oxygen removing effect, the water must be heated using a separate heat source.

c. Catalysis

A catalyst can be used to improve the performance of the deoxidizer. By applying the catalyst, it is possible to use a hydrogen gas as the deoxidizer. In the case of using hydrogen gas, since the product is nothing but water and the additive is in gaseous form, it is easy to separate and does not affect the system. When the existing oxygen scavenger is applied as it is, there is a homogeneous catalyst technology that enhances the oxygen removal effect even at low temperatures by injecting a liquid (organic drug) or ionic (metal ion) additive into the aqueous solution of oxygen scavenger. As a representative example, the reaction between oxygen and hydrazine may be promoted by injecting divalent copper ions into the catalyst. In addition, by adding about 0.1% of hydroquinone as a catalyst for the content of hydrazine, an excellent catalytic reaction effect can be obtained, and treatment performance is remarkably improved depending on operating conditions. However, in the high temperature and high pressure system as in power generation facilities, there are disadvantages such as precipitation of metal ions used as additives, pyrolysis of additives themselves, and generation of corrosion products. Therefore, the method using hydrogen gas may be advantageous if only the catalytic action is well implemented in this respect. Commercially available homogeneous catalysts include arylamines and organochemical metals. These liquid catalysts are known to be used together with hydrazine to promote the reaction of dissolved oxygen with hydrazine.

In general, various gases such as oxygen, nitrogen, and carbon dioxide are dissolved in water at a predetermined ratio, and molecular oxygen dissolved in water is called dissolved oxygen.

Dissolved oxygen concentration varies with water temperature and is known to be approximately 8-10 ppm at room temperature. However, even a small amount of dissolved oxygen causes corrosion through the oxidation of the inner wall of the pipe in the process of dissolving and moving in the fluid in the metal pipe, causing turbidity of the water and shortening the life of the pipe. Particularly, in the case of power plants, even in the presence of several ppb of dissolved oxygen in piping and system water, the magnetite (Fe ₃ O ₄ ) form corrosion occurs at the fluid contact portion of the system material under high temperature and high pressure conditions. This can seriously affect the safety of the power plant and shorten the life of the plant, such as corrosion of pipes and poor radiation shielding capacity. In order to solve these causes and problems, Patent Document No. 7213 (1995.7.4) entitled 'Dissolved oxygen removal apparatus in water' has been proposed to efficiently remove dissolved oxygen contained in water. This device uses the gas solubility change according to the gas partial pressure of dissolved oxygen, so that the water filled in the degassing tank is discharged to the outside through the downcomer and generates a vacuum pressure. Degassing was performed in the course of the water inside the degassing tank. The degassed oxygen is discharged to the outside through a vacuum pump to obtain a certain amount of degassed water.

However, there has been an inefficient problem that a separate pump must be operated in order to keep the degassing tank in a vacuum state after exhausting the degassing oxygen remaining in the degassing tank completely.

The present invention has been made to solve the above problems, the object of the present invention is to maintain the efficiency of the high efficiency hybrid dissolved oxygen removal device while maintaining the efficiency of the integrated module by simplifying the process while maintaining the applicability and ease of maintenance It is to provide an integrated dissolved oxygen removal apparatus that can be increased.

The present invention is implemented by the embodiment having the following configuration in order to achieve the above object.

An integrated dissolved oxygen removal device of the present invention, the reservoir tank for fresh water treatment; A pretreatment filter for filtering the treated water discharged from the reservoir; And a degassing membrane for primaryly removing dissolved oxygen in the treated water supplied by the pretreatment filter, and an dissolved oxygen having integrally activated carbon fibers for secondaryly removing the dissolved oxygen from the water discharged from the degassing membrane. It comprises a; removing means.

In addition, the degassing membrane is located in the inside of the activated carbon fiber, the dissolved oxygen removing means is located inside the housing and the degassing membrane and activated carbon fibers, the treated water feed port is introduced into one side of the degassing membrane, the other side An injection nozzle is provided so that the hydrogen supply port is disposed adjacent to the injection nozzle side.

And a valve between the dissolved oxygen removing means and the hydrogen supply port, and provided with a control module for controlling the valve to adjust the hydrogen supply, and the activated carbon fiber further contains a metal catalyst. desirable.

Hereinafter, with reference to the accompanying drawings will be described a preferred embodiment of the present invention.

As shown in FIG. 1 or 2, the dissolved oxygen removing apparatus 10 includes a reservoir 20, a pretreatment filter 30, and a dissolved oxygen removing means 40.

The reservoir 20 is generally for desalination of the treated water, and the reservoir 20 may be a facility for removing dissolved oxygen.

The pretreatment filter 30 is for filtering foreign matter contained in the treated water.

The dissolved oxygen removing means 40 includes a housing 41, a degassing membrane 42, an activated carbon fiber 43, a water supply port 44, a hydrogen supply port 45, a vacuum exhaust port 46, and an injection nozzle 47. ).

The degassing membrane 42 is a portion that primarily removes dissolved oxygen in the treated water introduced through the feed port 44. The degassing membrane 42 is formed in a hollow fiber form so that the inside is subjected to a vacuum and the treated water flows to the outside in contact with the membrane. Both ends of the hollow fiber have an epoxy finish to prevent water from entering.

The activated carbon fibers 43 pass through the activated carbon fibers in the first treatment water from which dissolved oxygen is removed from the degassing membrane 42. The activated carbon fiber is further obtained with a metal catalyst, thereby using it to remove dissolved oxygen remaining in the treated water. Preferred embodiments of the metal catalyst may be selected from palladium (Pd) or platinum (Pt), and the metal catalyst may be any one as long as it induces hydrogen / oxygen coupling reaction.

In addition, the degassing membrane 42 is preferably positioned inside the activated carbon fiber 43.

The water inlet 44 is introduced into the treated water to remove dissolved oxygen through the supply pump. The water supply unit measures the temperature and flow rate of the treated water flowing into the dissolved oxygen removing unit, and also measures the dissolved oxygen concentration in the treated water with a dissolved oxygen measuring instrument.

The hydrogen supply port 45 serves to supply hydrogen to remove dissolved oxygen through hydrogen reaction in the activated carbon fiber 43. The hydrogen may be supplied through an external cylinder or through a hydrogen supply device (not shown) using electrolysis. In addition, the end of the hydrogen supply port 45 is installed in the injection nozzle 47 discharged to the activated carbon fiber 43, the primary treated water through the deaeration membrane 42 for smooth mixing between the hydrogen and the treated water. do. This is a simple and efficient implementation of the function of the mixer separately installed in the existing hybrid type dissolved oxygen removal device to ensure that hydrogen is completely mixed by the flow rate of the primary degassing membrane. In addition, the hydrogen supply amount may be controlled by measuring the dissolved oxygen concentration of the treated water that is finally processed by the dissolved oxygen removing unit 40. In order to increase the dissolved oxygen removal rate, excess hydrogen is supplied to the dissolved oxygen required for the reaction.

Meanwhile, the hydrogen supply port 45 is a part for implementing a function of selecting an operation mode of the dissolved oxygen removing device 10. That is, as shown in FIG. 3, the valve 50 is disposed between the hydrogen supply port and the dissolved oxygen removing means 40, and the hydrogen supply flow rate is provided by providing a control module 60 connected to the valve 50. It is possible to control the supply or cut off the supply so that the second degassing operation mode by the catalytic reaction can be selected according to the operation mode.

The vacuum vent 46 serves to discharge the dissolved oxygen removed from the degassing membrane 42 to the outside through a vacuum pump.

The housing 41 includes a structure including the degassing membrane 42 and the activated carbon fibers 43 and an external pipe, and the treated water from which dissolved oxygen is removed by the degassing membrane and the activated carbon fibers. Fresh water is discharged to the outside.

For example, the degassing membrane 42 is provided inside, and the activated carbon fibers 43 are provided outside. The water inlet 44 is introduced into the degassing membrane 42, and hydrogen is introduced into the middle of the degassing membrane 42 and the activated carbon fibers 43. Therefore, dissolved oxygen is first removed from the degassing membrane, where the dissolved oxygen is released to the outside by a vacuum pump. The remaining dissolved oxygen not removed in the degassing membrane 42 is secondarily removed by catalytic reaction with hydrogen in the activated carbon fibers 43.

3 shows another embodiment according to the present invention, after measuring the dissolved oxygen concentration in the treated water coming out of the dissolved oxygen removing means 40, the control to control the amount of hydrogen supply by opening and closing the valve 50 Module 60 has applied. Hydrogen is supplied at the beginning of operation with high dissolved oxygen concentration, and as the dissolved oxygen concentration decreases gradually, the hydrogen supply can be reduced and the hydrogen consumption can be reduced while satisfying the requirements of dissolved oxygen. Even when the hydrogen supply is completely shut off, the function of the degassing membrane is still maintained. However, since there may be some dissolved oxygen in the treated water passing through the degassing membrane, the use of the valve 50 is determined according to the driving purpose.

<Example 1>

Dissolved oxygen removal experiment was performed by applying the dissolved oxygen removal device produced through the present invention. Dissolved oxygen removal means applied to this was used to carry a palladium (Pd) catalyst on the activated carbon fiber of 77 mm in diameter and 225 mm in length. The operating conditions were 1 ml per minute throughput and 10 ml / min hydrogen at 25 ° C and 38 ° C. At this time, the degree of vacuum applied to the degassed membrane was about 10 ^-3 torr. Dissolved oxygen reached a steady state in about 10 minutes after the operation of the device and the dissolved oxygen concentration was measured at this time. 5 is a diagram showing the dissolved oxygen concentration measured at the inlet side and the outlet side of the dissolved oxygen removing means during this experiment. In terms of dissolved oxygen concentration, dissolved oxygen removal efficiency was more than 99%.

<Example 2>

By applying the dissolved oxygen removal device manufactured by the present invention, the dissolved oxygen concentration change and the dissolved oxygen removal rate according to the operation time were measured. Dissolved oxygen removal rate was based on the initial dissolved oxygen concentration.

In this experiment, platinum catalyst was applied to activated carbon fiber. FIG. 6 is a graph showing dissolved oxygen concentration of degassed water according to the passage of time. After about 10 minutes, more than 99% of the dissolved oxygen in the initial concentration was removed, and the dissolved oxygen concentration in the degassed water dropped to 0.08 ppm or less. After approximately 30 minutes or more, dissolved oxygen of 99.9% or more of the initial concentration is removed, and the dissolved oxygen concentration in the degassed water can be reduced to 0.008 ppm or less.

Therefore, as shown in Examples 1 and 2, when the degassing membrane and the catalyst-supported activated carbon fiber are used integrally, the operation mode can be selected by adjusting the hydrogen supply amount according to the dissolved oxygen allowable concentration in the system.

The present invention is not limited to the embodiments described above, and various modifications and changes can be made by those skilled in the art, which are included in the spirit and scope of the present invention defined in the appended claims.

According to the present invention, while maintaining the efficiency of the high efficiency hybrid dissolved oxygen removal device while maintaining the integrated module through the simplification of the process there is an effect that can increase the applicability and ease of maintenance.

On the other hand, like the existing hybrid type high efficiency dissolved oxygen removing device, it is possible to minimize the occurrence of corrosion of metal pipes by dissolved oxygen in the water of industrial boilers and power plant systems, which can be expected to extend the life of equipment and facilities.

Claims (5)

A reservoir for desalination of treated water; A pretreatment filter for filtering the treated water discharged from the reservoir; And Dissolved oxygen removal, which is integrally provided with a degassing membrane for primaryly removing dissolved oxygen in the treated water supplied from the pretreatment filter, and an activated carbon fiber for secondaryly removing dissolved oxygen from the water discharged from the degassing membrane. Integrated dissolved oxygen removal device characterized in that it comprises a means. The method of claim 1, The degassing membrane is integrated dissolved oxygen removal device, characterized in that located in the interior of the activated carbon fiber. The method of claim 1, The dissolved oxygen removing means is located within the housing of the degassing membrane and the activated carbon fiber, the treated water inlet is introduced into one side of the degassing membrane, and the injection nozzle is provided to the other side so that the hydrogen supply port is adjacent to the injection nozzle side. Integral dissolved oxygen removing device, characterized in that arranged to be. The method of claim 3, wherein And a valve provided between the dissolved oxygen removing means and the hydrogen supply port, and provided with a control module for controlling the valve to adjust the hydrogen supply. The method of claim 3, wherein Integral dissolved oxygen removal apparatus, characterized in that the activated carbon fiber is further supported by a metal catalyst.

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