KR101772669B1 - Chemical cleaning waste fluid recycling system and method for boilers tube in thermal power plant - Google Patents

Abstract

The present invention relates to a system and a method for recycling chemical cleaning wastewater for steam touched boiler tubes, the system and the method which are capable of minimizing the generation of wastewater due to chemical cleaning by recycling the chemical cleaning wastewater used in removing scales of the steam touched boiler tubes such as a thermoelectric power plant, thereby reusing the recycled chemical cleaning wastewater as a chemical cleaning solution. To this end, a system for recycling chemical cleaning wastewater for steam touched boiler tubes according to the present invention comprises: a vacuum evaporation concentrator which vacuums and evaporates the chemical cleaning wastewater for steam touched boiler tubes to concentrate the chemical cleaning wastewater for steam touched boiler tubes; a reaction agent feeder which feeds magnesium oxide to the vacuum evaporation concentrator; an ammonia recovery device which recovers ammonia generated from the vacuum evaporation concentrator by magnesium oxide fed by the reaction agent feeder; a first reactor which makes ammonia received in the ammonia recovery device react with ethylene diamine tetraacetic acid (EDTA) to produce a metal-EDTA cleaning agent; and a vacuum pump which is connected to the ammonia recovery device to enable the inside of the vacuum evaporation concentrator to be maintained in a negative pressure state by suction of air.

Description

Technical Field [0001] The present invention relates to a chemical cleaning wastewater recycling system and method for boiler tubes,

The present invention relates to a chemical cleaning wastewater recycling system and method for steam-based boiler tubes, and more particularly, to a method and system for recycling chemical cleaning wastewater used to remove scale of a boiler tube, such as a thermal power plant, And to a system and method for the chemical cleaning wastewater recovery for a steam-based boiler tube capable of minimizing the generation of wastewater by chemical cleaning.

The steam tube used in the thermal power plant is connected to the boiler, and the scale tube is formed inside the tube with the operation time. The generated scale has a low thermal conductivity, which reduces the overall thermal efficiency. In addition, the scale may cause overheating of the piping, shortening the life of the power generation system, or even causing an accident that the piping ruptures.

That is, the wall tube material of the boiler water pipe of the thermal power plant is carbon steel, and the reheating and superheater tube material is 12% chromium steel and the main component is iron (Fe). Because such iron materials are thermodynamically unstable, corrosion can not be suppressed even with pure water.

Table 1 shows the metal components of boiler tubes used in thermal power plants.

ingredient Fe ₃ O ₄ SiO ₂ Al ₂ O ₃ Na ₂ O CaO MgO MnO NiO ZnO CuO Other wt,% <95 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5

Therefore, the power plant uses high purity (over 18 MΩ) water and various water treatment methods in order to minimize the corrosion of the boiler tube, but steam system boiler is operated under high temperature and high pressure conditions (water system: 180 ~ 255㎏ / , Steam system: 180 ~ 255㎏ / ㎠, 540 ℃), scale of 20 ~ 100mg / ㎠ is generated on the inner side of the boiler tube due to accumulation of usage time (2 ~ 5 years). This scale has a low thermal conductivity of 1/40 to 1/50 compared to carbon steel or 12% chrome steel. Therefore, when a scale is attached to a large scale, the thermal efficiency is lowered and the tube is overheated and ruptured, Particle Erosion, so the scale attached to the side of the tube must be removed.

AX-434, AX-424 (Minsan Technology, Korea) and Vertan-665, Vertan-675 [Hydrochem, USA] and Ebafose (Korea) were attached to the inner surface of the steam- (EDTA) (hereinafter referred to as "EDTA") such as Ebara-500, Ebafose-510 [Ebara, Japan]

As one of the methods for removing scale generated on the inner side of a tube of a steam system boiler by using the EDTA, Japanese Patent Application Laid-Open No. 10-0827789 discloses a chemical cleaning agent and a chemical cleaning method for a steam system boiler.

The above-mentioned technique is a method of cleaning by using a chemical cleaning agent to dissolve the scale (rust) adhered to the inner surface of the superheater tube and the reheating of the thermal power boiler for power generation, and a method of cleaning the inner surface of the superheater tube An air blowing method for discharging foreign matter such as a granular scale or a piece of iron introduced during the construction of a boiler to the atmosphere within 5 seconds by using high-pressure air, and an air blowing system used in this method.

On the other hand, chemical cleaning wastewater is generated by cleaning in the chemical cleaning method of the thermal power plant boiler using EDTA, and the generated chemical wastewater is stored in the large waste water storage tank. The stored chemical cleaning wastewater was collected at different times and treated at a separate site.

There are physical and chemical methods for the treatment of collected chemical cleaning wastewater. Physical methods include pyrolysis incineration method using high temperature plasma, evaporation concentration method and supercritical water treatment method, and the chemical method includes Fenton oxidation method using hydrogen peroxide and acid / alkali precipitation method.

As one of techniques for chemically treating the chemical washing wastewater, Japanese Patent Application Laid-Open No. 10-0919771 discloses a chemical washing waste treatment method and apparatus for a nuclear power plant steam generator containing a chelating agent and a radioactive substance.

The technique includes a first step of separating low-concentration or high-concentration chelate materials and radioactive liquid wastes containing heavy metals into pure water and contaminants through an evaporation / concentration apparatus, and a step of adding hydrogen peroxide to the concentrated waste solution in the evaporation / A second step of treating the organic matter in the Fenton reactor, a third step of sending untreated organic matter from the Fenton reactor to the evaporation tank, a fourth step of separating the solid matter from the water by providing an evaporation precipitation space in the evaporation tank, A fifth step of treating the untreated organic matter in the vapor generated in the evaporation tank with a catalyst in a catalytic apparatus, and a sixth step of cooling the vapor to be separated from the vapor discharged from the catalytic apparatus.

These conventional wastewater treatment methods require a separate large-sized waste water storage tank and are required to be reheated after being treated using a heat exchanger or the like in order to treat the discharged cleaned wastewater. Therefore, the cost of wastewater treatment such as construction cost and heating cost is increased .

In addition, since the ammonia gas, NH ₄ -EDTA, M-EDTA, and Fe-EDTA contained in the washing wastewater are disposed of by disposing of resources, the chemical cleaning process and the wastewater treatment must be separated and processed separately, The time required for the processing is long and a large-sized system is required.

KR 10-0827789 B1 (Apr. 29, 2008) KR 10-0919771 B1 (2009.09.24)

It is an object of the present invention to solve the problems of the prior art as described above, and it is an object of the present invention to provide a method and apparatus for recovering chemical cleaning wastewater generated by removing scale of a steam boiler tube, And to provide a chemical cleaning wastewater recovery system and method.

Another problem to be solved by the present invention is to provide a chemical cleaning wastewater recovery system and method capable of increasing the recovery rate without supplying external heat source by concentrating the chemical cleaning wastewater using the process heat of the chemical cleaning wastewater generated during cleaning I have to.

In order to solve the above problems, the present invention provides a chemical cleaning wastewater recycling system for a steam boiler tube, comprising: a vacuum evaporator concentrating the chemical washing wastewater for boiler tubes by vacuum and evaporation; A reactant supply unit for supplying magnesium oxide to the vacuum evaporator; An ammonia recovery unit for recovering ammonia generated in the vacuum evaporator by the magnesium oxide supplied by the reactant supply unit; A first reactor for reacting the ammonia recovered in the ammonia recovery unit with ethylene diamine tetraacetic acid (EDTA) to produce a metal-EDTA cleaning agent; And a vacuum pump connected to the ammonia recovery device for maintaining the inside of the vacuum evaporator to be in a negative pressure state by suction of air.

At this time, the metal-EDTA complex generated in the vacuum evaporation concentrator is supplied by the magnesium oxide supplied by the reactant supply unit, and the metal-EDTA complex is reacted with the caustic soda to produce a refractory metal-EDTA A second reactor; And a solid-liquid separator for separating the lean metal-EDTA and water (H ₂ O) produced in the second reactor.

In addition, the vacuum evaporation concentrator may include an injection nozzle installed on the inner side of the vacuum evaporator to spray the chemical cleaning wastewater; And a mist eliminator provided on the spray nozzle to agglomerate and remove moisture and solid matter generated therein.

The apparatus may further include a condenser installed between the ammonia collector and the vacuum pump, for condensing the air introduced by the vacuum pump to generate condensed water.

In order to solve the above problems, the present invention provides a method for regenerating a chemical cleaning wastewater for a boiler tube, comprising the steps of: Washing wastewater concentration step; A first reaction step of producing ammonia by mixing magnesium oxide in the chemical cleaning wastewater concentrated in the chemical washing wastewater concentration step; A regeneration step of reacting ammonia produced in the first reaction step with ethylenediamine tetraacetic acid (EDTA) to produce a metal-EDTA detergent; A second reaction step of reacting the metal-EDTA complex produced in the first reaction step with caustic soda to produce refractory metal-EDTA; And a solid-liquid separation step of separating the poorly soluble metal-EDTA and water (H ₂ O) produced in the second reaction step.

According to the present invention, there is an advantage that environmental pollution can be prevented and resources can be recycled by reusing chemical cleaning wastewater physically or chemically discarded.

In addition, since the use of the high temperature of the chemical cleaning wastewater can reduce the supply of external heat source due to the regeneration of the chemical cleaning wastewater, the cost for regeneration can be reduced and the byproduct generated during the regeneration can be utilized as a raw material There are advantages.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a general schematic diagram of a chemical cleaning wastewater recovery system for a steam-based boiler tube according to the present invention. FIG.
2 is a configuration diagram of a condenser applied to a chemical cleaning wastewater recovery system for a steam-based boiler tube according to the present invention.
3 is a configuration diagram of a solid-liquid separator applied to a chemical washing wastewater recovery system for a steam-based boiler tube according to the present invention.
4 is a flow chart of a method for recycling chemical cleaning wastewater for a steam-based boiler tube according to the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The present invention relates to a chemical cleaning method for a boiler tube which can minimize the generation of wastewater by chemical cleaning by recycling chemical cleaning wastewater used for removing scale of a steam boiler tube such as a thermal power plant and reusing it as a chemical cleaning liquid To a system and method for recovering wastewater.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a general block diagram of a chemical cleaning wastewater recovery system for a steam-based boiler tube according to the present invention.

1, a chemical washing wastewater recovery system for a steam boiler tube according to the present invention includes a vacuum evaporator 10, a reactant supply unit 20, an ammonia recovery unit 30, a first reactor 40, A vacuum pump 50, a condenser 60, a second reactor 70, a solid-liquid separator 80 and a heat exchanger 90.

Further, the first to third pumps P1, P2, and P3 are configured to transfer or circulate the wastewater in the above configuration.

The vacuum evaporation concentrator 10 concentrates the chemical washing wastewater for the steam boiler tube by vacuum / evaporation, and supplies the chemical washing wastewater used for removing the scale of the boiler tube from the first pump P1 and concentrates it.

Ammonium-EDTA (NH ₄ -EDTA) is generally used as the chemical cleaner used to remove the scale produced on the inner side of the steam system boiler tube.

That is, when a chemical cleaning agent is injected into the tube and the chemical cleaning is performed by circulating or reversing the circulation for 20 hours or more at a temperature of 90 ° C ± 5 and a flow rate of 0.2-0.8 m / sec, (Metal oxide) formed on the inner surface of the tube so that the metal oxide is desorbed from the inner side of the tube.

At this time, the chemical reaction formula of iron, magnesium and copper in the chemical cleaning agent and scale (metal oxide) is represented by the following chemical formula 1.

(1)

That is, the chemical cleaning agent reacts with the metal oxide at a high temperature to desorb the metal oxide from the inner side of the tube, and when the cleaning is completed, the chemical cleaning liquid becomes the chemical cleaning wastewater containing the metal oxide.

The chemical cleaning wastewater generated by the cleaning is supplied to the vacuum evaporation concentrator 10 by the first pump P1.

At this time, the chemical washing wastewater supplied to the vacuum evaporation concentrator 10 by the pumping of the first pump P1 is supplied through the injection nozzle 11 installed in the upper part of the inside of the vacuum evaporation concentrator 10.

That is, the chemical cleaning wastewater supplied to the vacuum evaporation concentrator 10 contains predetermined water. However, since the chemical cleaning wastewater is sprayed through the nozzle and the heat of the chemical cleaning wastewater, a part of the water contained in the chemical cleaning wastewater is evaporated .

At this time, the internal pressure of the vacuum evaporator (10) is relatively lower than the atmospheric pressure, and the water contained in the chemical washing wastewater is more actively evaporated.

Accordingly, the inside of the vacuum evaporator 10 may be configured to maintain a vacuum state.

Here, a mist eliminator 12 is installed inside the vacuum evaporator 10 in order to collect and remove moisture to be evaporated.

The mist eliminator 12 removes impurities including moisture and dust generated by evaporation, and is installed at a position higher than the spray nozzle 11. [

Accordingly, the chemical cleaning wastewater supplied to the vacuum evaporation concentrator 10 is concentrated by the action of heat, vacuum, spray, or the like.

The reactant supply unit 20 supplies the first reactant to the vacuum evaporation concentrator 10, wherein EDTA used as a chemical cleaning agent is removed from the scale of the inner side of the tube by EDTA as a metal-EDTA complex To change. At this time, the first reactant is made of magnesium oxide.

The magnesium oxide may be one selected from magnesium oxide (MgO) or magnesium hydroxide (Mg (OH) ₂ ), or a mixture thereof.

Here, the chemical reaction formula between unreacted EDTA and magnesium oxide contained in the chemical washing wastewater is represented by the following chemical formula (2).

(2)

The unreacted chemical cleaning solution (NH ₄ -EDTA) contained in the chemical cleaning wastewater reacts with the magnesium oxide to form magnesium-EDTA (Mg-EDTA), ammonia (NH ₃ ), and water (H ₂ O). At this time, ammonia (NH ₃ ) is converted into a gas form.

The ammonia recovery unit 30 recovers the ammonia generated in the vacuum evaporation concentrator by the magnesium oxide supplied by the reactant supply unit 20.

That is, when the magnesium oxide is supplied to the chemical washing wastewater concentrated in the vacuum evaporator 10 according to the formula (2), the chemical washing wastewater reacts with the magnesium oxide to generate ammonia (NH ₃ ) gas. NH ₃ ) gas contains gases of other substances.

The ammonia recovery unit 30 sucks the gas of the vacuum evaporation concentrator 10 to recover ammonia (NH ₃ ).

The first reactor 40 performs a function of reacting the ammonia recovered in the ammonia recovery unit with EDTA (Ethylene Diamine Tetraacetic Acid) to produce a metal-EDTA detergent.

The EDTA (C ₁₀ H ₁₆ N ₂ O ₈ ) is a compound composed of four carboxylic acid salts and two amine groups, which can form a water-soluble chelate in which almost all metal ions and several ligands are coordinated to each other have. Here, the chelate means a compound having two or more coordinated coordinating atoms and having a ring structure to surround coordination atoms.

Accordingly, ammonium-EDTA (NH ₄ -EDTA) is produced when ammonia and EDTA are combined and reacted.

Here, the first reactor (40) is provided with a stirrer (41) for activating the reaction between ammonia and EDTA.

The stirrer 41 may include a motor and an impeller, and the motor may be configured to be capable of normal / reverse rotation according to design conditions. That is, by using a motor capable of normal / reverse rotation, the impeller can be driven by normal rotation and reverse rotation so that the remaining alkali aqueous solution, the supplied aqueous alkali solution, and water are stirred and mixed evenly.

The agitator 41 may be configured to operate at a different driving speed from a point of time when the EDTA is introduced and a point of time when the EDTA is not inserted.

For example, in a typical reaction, the mixture is mixed while being rotated at 100 to 300 rpm while alternating between forward rotation and reverse rotation. When the EDTA is introduced, the driving speed of the agitator 41 is controlled by the supplied EDTA and ammonia May be rotated at 500 to 800 rpm to such an extent that the stirring can be performed.

The ammonia supplied to the first reactor 40 may be supplied to the lower side of the first reactor 40 so that the supplied ammonia may be directly contacted with the EDTA contained in the first reactor 40 have.

The ammonium-EDTA produced in the first reactor 40 is used as a chemical cleaner.

That is, ammonium-EDTA (NH ₄ -EDTA), which is a chemical cleaning agent used for scale cleaning on the inner side of the tube, is connected to the vacuum evaporator 10, the reactant supplier 20, the ammonia collector 30, and the first reactor 40, And then reproduced.

The vacuum pump 50 is for maintaining the inside of the vacuum evaporator 10 at a negative pressure which is relatively lower than the atmospheric pressure. The vacuum pump 50 is connected to the ammonia collector 30 and is connected to the vacuum evaporator 10) to keep the inside of negative pressure.

That is, the internal gas of the vacuum evaporator 10 is pumped and discharged through the ammonia collector 60 according to the operation of the vacuum pump 50.

At this time, depending on the operation of the vacuum pump 50, the gas flowing into the ammonia collecting device 30 also contains gas of other materials including ammonia (NH ₃ ), and has a high thermal energy.

Therefore, a construction for condensing high-temperature thermal energy is required.

The condenser 60 is installed between the ammonia collector 30 and the vacuum pump 50 and functions to condense the air introduced by the vacuum pump 50 to generate condensed water.

FIG. 2 is a schematic view showing the construction of a condenser applied to a chemical cleaning wastewater recovery system for a steam-based boiler tube according to the present invention.

2, a condenser 60 applied to the chemical cleaning wastewater recovery system for a steam boiler tube according to the present invention includes a transfer pipe 61 that is installed in a zigzag fashion to transfer a gas, A condensed water discharge pipe 63 for discharging the condensed water condensed in the lower side bending portion of the transfer pipe 61, a cooling water inlet 64 for flowing the cooling water into the inside thereof, And a cooling water outlet 65.

That is, in the condenser 60, a transfer pipe 61 for transferring a gas having a high thermal energy is disposed in a zigzag manner, and cooling water flows around the transfer pipe. Thus, the gas is condensed while being flowed through the transfer pipe (61) to be converted into liquid, and the converted liquid is discharged through the condensed water discharge pipe (63).

Referring to FIGS. 1 and 2, in the vacuum evaporator 10, Fe-EDTA, Mg-EDTA, and Cu-EDTA, which are metal-EDTA complexes reacted with metal scale during cleaning, Reaction EDTA is reacted to produce the resulting metal-EDTA complex (Mg-EDTA).

In the vacuum evaporator 10, Mg-EDTA and Cu-EDTA reacted with the metal scale at the time of cleaning are very small, but the unreacted EDTA and Fe-EDTA generated during the washing are mixed with the first reactant A large amount of Mg-EDTA produced by mixing is included.

Thus, a construction for treating the resulting metal-EDTA complex (Fe-EDTA, Mg-EDTA) is required.

The second reactor 70 is supplied with the metal-EDTA complex supplied by the vacuum evaporator 10 and reacts the supplied metal-EDTA complex with caustic soda (NaOH) to produce an insoluble metal-EDTA .

At this time, the metal-EDTA complex of the vacuum evaporator 10 is in a liquid form and is supplied to the second reactor 70 by the pumping operation of the pump P2.

When the metal-EDTA complex (Fe-EDTA, Mg-EDTA) and caustic soda (NaOH) are chemically reacted, insoluble metal-EDTA and water (H ₂ O) are produced.

At this time, the poorly soluble metal-EDTA is NaFe-EDTA and NaMg-EDTA and exists in a solid state.

Like the first reactor 40, an agitator 71 may be installed in the second reactor 70.

The solid-liquid separator 80 separates and discharges the poorly soluble metal-EDTA and water (H ₂ O) generated in the second reactor 70, and FIG. 3 is a schematic diagram of the chemical- Liquid separator applied to the regeneration system according to the present invention.

At this time, the poorly soluble metal-EDTA and water (H ₂ O) generated in the second reactor 70 are supplied to the solid-liquid separator 80 by the pumping operation of the third pump P3.

3, the solid-liquid separator 80 applied to the chemical washing wastewater recovery system for the steam-based boiler tube according to the present invention comprises a vibrating body 81 formed in a rectangular shape and installed in a fixed frame, An oscillator 82 positioned below the oscillator 82 for generating vibration and transmitting the generated oscillation to the oscillator 81, an insoluble metal-EDTA introduced by the vibration transmitted from the oscillator 82, ₂ O) the separated and obliquely downwardly arranged to discharge, integral with the vibrating body 81 doedoe plurality of drain hole is a vibrating screen perforations 83, in close contact with the lower the vibrating screen 83 to the surface A discharge tube 85 installed at the lower end of the vibration screen 83 and discharging the sparingly soluble metal-EDTA, a sparger-type metal- the EDTA and water (H ₂ O) in a mixed solid-liquid mixture is introduced It is configured to include a cleaning nozzle 87 for spraying the wash water feed pipe provided at the upper 86 and the vibrating screen (83).

As the washing water sprayed from the washing nozzle 87, condensed water condensed and discharged in the condenser 60 may be used.

Thus, the weakly soluble metal-EDTA NaFe-EDTA and NaMg-EDTA separated through the solid-liquid separator 80 can be used as a sulfidation corrosion inhibitor or a clinker inhibitor in a thermal power boiler.

In the present invention, the inner surface of the tube is cleaned with the chemical washing water heated to a high temperature, and the chemical washing wastewater generated in accordance with the washing is immediately regenerated. Therefore, the chemical washing wastewater flowing into the vacuum evaporation concentrator (10) Lt; RTI ID = 0.0 &gt; 5 C. &lt; / RTI &gt;

However, when the temperature of the chemical washing wastewater is lowered due to the transportation of the winter season or the wastewater, it is difficult to expect the water contained in the chemical washing wastewater to evaporate.

A heat exchanger (90) is installed to maintain the internal temperature of the vacuum evaporator (10) at a certain level.

The heat exchanger 90 detects the internal temperature of the vacuum evaporation concentrator 10 and operates when the detected internal temperature falls below 75 캜 so that the internal temperature of the vacuum evaporation concentrator 10 is maintained at 75 캜 or higher .

The chemical cleaning wastewater regeneration method for the steam-based boiler tube will be described with the above-described structure.

4 is a flow chart of a method for regenerating chemical cleaning wastewater for a steam-based boiler tube according to the present invention.

Referring to FIG. 4, the chemical cleaning wastewater reclamation method for steam-based boiler tubes according to the present invention includes a chemical washing wastewater concentration step S10, a first reaction step S20, a regeneration step S30, (S40) and a solid-liquid separation step (S50).

1. Chemical cleaning wastewater concentration step (S10)

The chemical cleaning wastewater concentration step S10 is a step of concentrating the chemical cleaning wastewater used for removing the scale of the boiler tube, while maintaining the predetermined temperature.

At this time, the concentration of the chemical washing wastewater is performed in a vacuum state to evaporate water contained in the chemical washing wastewater. In addition, the chemical cleaning wastewater may be evaporated when the chemical wastewater is evaporated.

2. First reaction step (S20)

The first reaction step (S20) is a step of producing ammonia which mixes the magnesium oxide with the chemical cleaning wastewater concentrated in the chemical washing wastewater concentration step.

The chemically cleaned wastewater will have unreacted EDTA that does not react with the scale on the side of the tube.

That is, a metal-EDTA complex (Fe-EDTA) generated in accordance with the washing and an unreacted ammonium-EDTA (NH ₄ -EDTA) are present in the chemical washing wastewater.

At this time, unreacted ammonium-EDTA (NH ₄ -EDTA) reacts with the charged magnesium oxide to produce a metal-EDTA complex (Mg-EDTA) and ammonia.

3. Playback step (S30)

The regeneration step S30 is a step of reacting the ammonia produced in the first reaction step S20 with ethylenediamine tetracetic acid (EDTA) to produce a metal-EDTA detergent.

That is, ammonium-EDTA is produced by reacting ammonia (NH ₃ ) with EDTA, and the resulting ammonium-EDTA is used as a detergent for cleaning.

4. Second reaction step (S40)

The second reaction step (S40) is a step of reacting the metal-EDTA complex produced in the first reaction step (S20) with caustic soda to produce refractory metal-EDTA.

Metal-EDTA cleaners that have been de-scaled or reacted with magnesium oxide produce metal-EDTA complexes (Fe-EDTA, Mg-EDTA).

The metal-EDTA complex (Fe-EDTA, Mg-EDTA) chemically reacts with caustic soda (NaOH) to produce an insoluble metal-EDTA. At this time, the poorly soluble metal-EDTA is NaFe-EDTA and NaMg-EDTA and is present in a solid state.

5. Solid-liquid separation step (S50)

Solid-liquid separation step (S50) is a step of separating the insoluble metal -EDTA and water (H ₂ O) produced in the second reaction step (S40).

Separation of NaFe-EDTA and NaMg-EDTA according to the solid-liquid separation (S50) can be used as a sulphide corrosion inhibitor or a clinker inhibitor in a thermal power boiler.

According to the present invention, there is an advantage that environmental pollution can be prevented and resources can be recycled by reusing chemical cleaning wastewater physically or chemically discarded.

In addition, since the use of the high temperature of the chemical cleaning wastewater can reduce the supply of external heat source due to the regeneration of the chemical cleaning wastewater, the cost for regeneration can be reduced and the byproduct generated during the regeneration can be utilized as a raw material There are advantages.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

10: Vacuum evaporation concentrator 20: Reactant feeder
30: Ammonia recoverer 40: First reactor
41: stirrer 50: vacuum pump
60: condenser 61: transfer pipe
62: radiating fin 63: condensate discharging pipe
64: cooling water inlet 65: cooling water outlet
70: second reactor 71: stirrer
80: Solid-liquid separator 90: Heat exchanger
P1, P2, P3: first to third pumps

Claims (5)

Vacuum Evaporator for Vacuum and Evaporation of Chemical Cleaning Wastewater for Steam System Boiler Tube;
A reactant supply unit for supplying magnesium oxide to the vacuum evaporator;
An ammonia recovery unit for recovering ammonia generated in the vacuum evaporator by the magnesium oxide supplied by the reactant supply unit;
A first reactor for reacting the ammonia recovered in the ammonia recovery unit with ethylene diamine tetraacetic acid (EDTA) to produce a metal-EDTA cleaning agent; And
A vacuum pump connected to the ammonia recovery unit for maintaining the inside of the vacuum evaporator to be in a negative pressure state by suction of air;
Wherein the chemical cleaning wastewater recycling system for steam-based boiler tubes comprises:
The method according to claim 1,
EDTA complex generated in the vacuum evaporation concentrator by magnesium oxide supplied by the reactant supply unit and reacting the supplied metal-EDTA complex with caustic soda to produce a refractory metal-EDTA, A reactor; And
A solid-liquid separator for separating the poorly soluble metal-EDTA and water (H ₂ O) produced in the second reactor;
Further comprising: a chemical cleaning wastewater recovery system for a steam-based boiler tube.
The method according to claim 1,
In the vacuum evaporation concentrator,
An injection nozzle installed on the inner upper side for spraying the chemical cleaning wastewater; And
A mist eliminator provided on the spray nozzle to agglomerate and remove moisture and solid matter generated therein;
Wherein the chemical cleaning wastewater recycling system for steam-based boiler tubes comprises:
The method according to claim 1,
A condenser installed between the ammonia recovery unit and the vacuum pump, for condensing the air introduced by the vacuum pump to generate condensed water;
Further comprising: a chemical cleaning wastewater recovery system for a steam-based boiler tube.
A method of recycling a chemical cleaning wastewater for a steam-based boiler tube,
A chemical cleaning wastewater concentration step of concentrating the chemical wastewater used to remove the scale of the boiler tube, while maintaining the chemical wastewater at a predetermined temperature;
A first reaction step of producing ammonia by mixing magnesium oxide in the chemical cleaning wastewater concentrated in the chemical washing wastewater concentration step;
A regeneration step of reacting ammonia produced in the first reaction step with ethylenediamine tetraacetic acid (EDTA) to produce a metal-EDTA detergent;
A second reaction step of reacting the metal-EDTA complex produced in the first reaction step with caustic soda to produce refractory metal-EDTA; And
A solid-liquid separation step of separating the poorly soluble metal-EDTA produced in the second reaction step from water (H ₂ O);
Wherein the chemical cleaning wastewater recycling method for a steam-based boiler tube is performed.

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