Digestion agent preparation method, and method and system for removing iron-containing colloidal sediments

Abstract

The invention relates to the technical field of nuclear power station equipment, in particular to a digesting agent preparation method and a method and system for removing iron-containing colloidal deposits, and the target digesting agent is obtained by synthesizing 4-aminobenzoic acid through a melt polycondensation method by using acetic acid as a catalyst. The method disclosed by the invention has the beneficial effects that the poly (aminobenzoic acid) serving as the target digestion agent is synthesized by taking 4-aminobenzoic acid as a monomer and adopting cheap and environment-friendly acetic acid as a catalyst through a melt polycondensation method for the first time. According to the innovation, the traditional synthesis process is simplified, the production cost is reduced, and the stability and efficiency of the target digesting agent in a high-temperature and high-pressure environment are also remarkably improved.

Description

Technical Field

[0001] The invention relates to the technical field of nuclear power plant equipment, in particular to a method for preparing a digester, and a method and a system for removing iron-containing colloidal sediments. Background Art

[0002] During the operation of a nuclear power plant, the deposits on the secondary side of the horizontal steam generator will gradually increase, which not only affects the heat transfer performance of the equipment, but also causes serious corrosion, threatening the safe and stable operation of the steam generator. Therefore, it is necessary to efficiently clean the deposits on the secondary side of the steam generator to ensure the safe and stable operation of the steam generator. Summary of the invention

[0003] In view of the above problems or problems existing in the prior art, the present invention is proposed.

[0004] To solve the above technical problems, the present invention provides the following technical solutions: a method for preparing a digester, which comprises using acetic acid as a catalyst to synthesize 4-aminobenzoic acid by a melt polycondensation method to obtain a target digester.

[0005] As a preferred embodiment of the method for preparing the digester of the present invention, wherein: under the protection of an inert gas, the 4-aminobenzoic acid monomer is dried at 60° C. for at least 12 hours, wherein the purity of the 4-aminobenzoic acid monomer is greater than or equal to 97%;

[0006] Add the dried 4-aminobenzoic acid monomer and acetic acid catalyst into a reaction kettle, heat to a molten state of 160-200° C. under nitrogen protection, and maintain the temperature for 8-12 hours with stirring;

[0007] After the reaction is completed, the crude polymer is washed with deionized water and ethanol and then dried in a vacuum drying oven at 60-80° C. for 24-36 hours to obtain the target digester.

[0008] As a preferred embodiment of the method for preparing the digester of the present invention, the dried 4-aminobenzoic acid monomer and the acetic acid catalyst are added to a reaction kettle, comprising:

[0009] 1% to 5% by mass of acetic acid based on the mass of the dried 4-aminobenzoic acid monomer is added into the reaction kettle as a catalyst.

[0010] A method for removing iron-containing colloidal sediments, comprising obtaining a target digester by the above digester preparation method;

[0011] During the continuous operation of the steam generator, the target digester is continuously or intermittently added to the feed water on the secondary side of the steam generator;

[0012] The target digester forms a stable complex with the iron ions in the iron-containing colloidal sediment, causing the sediment to decompose.

[0013] As a preferred embodiment of the method for removing iron-containing colloidal deposits of the present invention, the method further comprises:

[0014] Under the flushing action of the circulating water flow, the decomposed sediments are peeled off from the secondary side surface of the steam generator and discharged with the water flow.

[0015] As a preferred embodiment of the method for removing iron-containing colloidal deposits of the present invention, the method further comprises:

[0016] Cooling water containing exfoliated sediment is filtered to ensure that the water quality meets the reuse standards.

[0017] As a preferred embodiment of the method for removing iron-containing colloidal deposits of the present invention, the steam generator is a steam generator of a pressurized water reactor, and the pressurized water reactor operates at a pressure of 2.0 to 5.0 MPa.

[0018] A cleaning system, comprising a steam generator: for receiving a target digester obtained by the above-mentioned digester preparation method;

[0019] Sampling port: used to monitor the water quality and sediment content in the steam generator through the monitoring device.

[0020] As a preferred embodiment of the method for preparing the digester of the present invention, the cleaning system comprises:

[0021] Filter device: used to filter cooling water containing exfoliated sediments.

[0022] As a preferred embodiment of the method for preparing the digester of the present invention, the cleaning system further comprises:

[0023] Sewage pipe: used to discharge or recycle treated cooling water.

[0024] The beneficial effects of the present invention are as follows: a method for synthesizing poly(aminobenzoic acid) as a target digester using 4-aminobenzoic acid as a monomer, through a melt polycondensation method and for the first time using cheap and environmentally friendly acetic acid as a catalyst. This innovation not only simplifies the traditional synthesis process and reduces production costs, but also significantly improves the stability and efficiency of the target digester in a high-temperature and high-pressure steam generator environment. By forming a stable complex with the iron ions in the iron-containing colloidal sediment through specific functional groups, the present invention effectively destroys the electrostatic attraction between the sediment particles, achieves rapid dispersion, dissolution and conversion of the sediment, and significantly improves the removal efficiency. In addition, the good permeability and dispersibility of the target digester ensure the deep decomposition and stripping of the sediment, further enhancing the cleaning effect. More importantly, the present invention completely eliminates the potential corrosion risk of catalyst residues to the secondary side and metal pipelines of the steam generator by optimizing the selection and dosage of the catalyst, and supplemented by a sophisticated post-treatment process, thereby ensuring the safe operation and long-term stability of the equipment. At the same time, this technical solution provides a flexible range of target digester usage, which is suitable for sediment removal needs of different scales, and can exhibit excellent dispersion activity under the conventional operating pressure of a pressurized water reactor, further expanding its scope of application and practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0026] Figure 1 Schematic diagram of the cleaning system.

[0027] In the figure: 810, nuclear power plant; 812, reactor; 813, reactor outlet heat pipe; 814, steam generator; 815, heat pipe; 816, steam generator secondary side; 818, steam generator drum; 819, steam duct; 820, turbine; 822, generator; 824, condenser; 826, cooling water duct; 827, high-pressure heater; 829, water pump; 830, sewage pipe; 832, filter device; 836, condensation duct; 838, emission storage; 840, sampling port. DETAILED DESCRIPTION

[0028] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0029] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0030] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0031] Example 1

[0032] This embodiment provides a method for preparing a digester, which includes using acetic acid as a catalyst to synthesize 4-aminobenzoic acid through a melt polycondensation method to obtain a target digester.

[0033] It should be noted that acetic acid, as a mild organic acid, not only plays a catalytic role in this reaction, but also helps to adjust the pH value of the reaction system and promote the condensation reaction.

[0034] Further, under the protection of an inert gas, the 4-aminobenzoic acid monomer is dried at 60° C. for at least 12 hours, wherein the purity of the 4-aminobenzoic acid monomer is greater than or equal to 97%;

[0035] It should be noted that under the protection of inert gas nitrogen, oxidation of 4-aminobenzoic acid monomer can be prevented during the reaction.

[0036] Preferably, the amount of 4-aminobenzoic acid monomer used in each reaction batch is 500 g to 2 kg.

[0037] It should be noted that when the amount of 4-aminobenzoic acid monomer is in the range of 500 g to 2 kg, the reaction can achieve a higher conversion rate and yield, because within this range, the concentration of the reactants is moderate, neither too diluted nor too concentrated, which is conducive to the effective collision between the reactants and the improvement of the reaction rate.

[0038] The dried 4-aminobenzoic acid monomer and acetic acid catalyst are added to a reactor, heated to a molten state of 160-200°C under nitrogen protection, and the temperature is maintained for stirring and reacting for 8-12 hours. A glass or stainless steel reactor with an agitator, a thermometer, a nitrogen inlet and a vacuum interface should be used, and the reactor needs to be purged with an inert gas in advance to exclude air.

[0039] It should be noted that under nitrogen protection, the dried 4-aminobenzoic acid monomer was added to the reactor, and then the acetic acid catalyst was slowly added. The reactor was closed and heating was started, preferably at a heating rate of 5°.

[0040] C / min, until the reaction mixture reaches a molten state, the temperature is controlled between 160 and 200 ° C, preferably 180 ° C, and further, the reaction rate increases with the increase of temperature. However, too high a temperature may lead to an increase in side reactions, reducing the yield and purity of the target product. It was found through experiments that 180 ° C can enable the reaction to proceed efficiently and selectively, and the temperature controlled at 180 ° C can ensure that the reactants will not decompose into other by-products.

[0041] It should be further noted that, in the molten state, the reaction temperature is kept constant, and the stirrer is turned on to fully mix the 4-aminobenzoic acid monomer and the catalyst. The reaction time is determined according to the desired polymer molecular weight, and usually requires a reaction of several hours to more than ten hours, and the preferred reaction time is 8 to 12 hours. During this period, samples can be taken regularly to detect the monomer conversion rate to monitor the reaction progress.

[0042] Preferably, under the protection of inert gas nitrogen, oxidation of 4-aminobenzoic acid monomer can be prevented during the reaction.

[0043] After the reaction is completed, the crude polymer is washed with deionized water and ethanol and then dried in a vacuum drying oven at 60-80° C. for 24-36 hours to obtain the target digester.

[0044] It should be noted that deionized water and ethanol were used for washing to remove unreacted monomers and catalyst residues.

[0045] Further, the dried 4-aminobenzoic acid monomer and acetic acid catalyst are added into a reaction kettle, comprising:

[0046] 1% to 5% by mass of acetic acid based on the mass of the dried 4-aminobenzoic acid monomer is added into the reaction kettle as a catalyst.

[0047] It should be noted that the main function of the catalyst is to accelerate the reaction rate while maintaining the selectivity of the reaction as much as possible, that is, to generate as much target product as possible and reduce the generation of by-products. It was found through experiments that when the amount of the catalyst is in the range of 1% to 5% of the mass of the 4-aminobenzoic acid monomer, the catalytic efficiency is high and good selectivity can be maintained. Within this range, the active sites of the catalyst can fully contact the reactants and promote the reaction.

[0048] Preferably, 3% by mass of acetic acid based on the mass of the dried 4-aminobenzoic acid monomer is added into the reactor as a catalyst.

[0049] Preferably, when the catalyst dosage is 3% of the mass of the 4-aminobenzoic acid monomer, it can avoid the problem of increased side reactions caused by excessive catalyst, thereby reducing the purity and yield of the target product, and can also solve the problem of poor catalytic effect, slow reaction rate or decreased conversion rate caused by insufficient catalyst.

[0050] In summary, the beneficial effect of the digester preparation method of the present invention is to use 4-aminobenzoic acid as a monomer, synthesize poly (aminobenzoic acid) as a target digester by melt polycondensation method and use cheap and environmentally friendly acetic acid as a catalyst for the first time. This innovation not only simplifies the traditional synthesis process and reduces production costs, but also significantly improves the stability and efficiency of the target digester in a high temperature and high pressure environment.

[0051] Example 2

[0052] This embodiment provides a method for removing iron-containing colloidal deposits, which includes:

[0053] The target digester is obtained by the preparation method of Example 1;

[0054] During the continuous operation of the steam generator, the target digester is continuously or intermittently added to the feed water on the secondary side of the steam generator;

[0055] It should be noted that the dosage of the target digester is adjusted within the range of 1 g to 1000 g of the target digester per 1 g of iron-containing colloidal sediment treated.

[0056] The target digester forms a stable complex with the iron ions in the iron-containing colloidal sediment, causing the sediment to decompose.

[0057] It should be noted that the obtained target digester contains an amino functional group, which has a lone pair of electrons and can react with iron ions (such as Fe 2+ or Fe 3+ ) to form a stable complex. This complexation can destroy the electrostatic attraction between sediment particles, because the iron ions may originally combine with other components in the colloidal particles (such as oxygen, hydroxide, etc.) through electrostatic interaction to form a stable sedimentation structure. When the amino functional group coordinates with the iron ions, it changes the charge distribution and coordination environment of the iron ions, thereby weakening the interaction between sediment particles. In addition, the amino functional group interacts with other components in the sediment through intermolecular forces such as hydrogen bonds and van der Waals forces, further promoting the dispersion, dissolution and transformation of the sediment. Under the combined effect of these effects, poly (aminobenzoic acid) can be used as a target digester to efficiently remove iron-containing colloidal sediments.

[0058] Furthermore, the method also includes,

[0059] Under the flushing action of the circulating water flow, the decomposed sediments are peeled off from the secondary side surface of the steam generator and discharged with the water flow.

[0060] Furthermore, the method also includes,

[0061] Cooling water containing exfoliated sediment is filtered to ensure that the water quality meets the reuse standards.

[0062] Furthermore, the steam generator is a steam generator of a pressurized water reactor, and the pressurized water reactor operates at a pressure of 2.0 to 5.0 MPa.

[0063] It should be noted that the design of the pressurized water reactor is based on strict safety standards and engineering principles. These standards generally specify the operating parameters of the reactor under different operating conditions, including pressure, temperature, flow rate, etc. Therefore, the pressure range of 2.0-5.0MPa is determined based on these safety standards and design principles. Secondly, in a pressurized water reactor, water flows under high pressure as a coolant to effectively take away the heat generated by the reactor core. The selection of this pressure range is closely related to the thermodynamic properties and fluid mechanics behavior of water. Within this pressure range, water can remain in a liquid state and has sufficient density and fluidity to ensure effective heat transfer.

[0064] In summary, the beneficial effect of a method for removing iron-containing colloidal deposits is to form a stable complex with the iron ions in the iron-containing colloidal deposits through specific functional groups, effectively destroy the electrostatic attraction between the sediment particles, achieve rapid dispersion, dissolution and transformation of the sediment, and significantly improve the removal efficiency. In addition, the good permeability and dispersibility of the target digester ensure the deep decomposition and peeling of the sediment, further enhancing the cleaning effect. More importantly, the present invention completely eliminates the potential corrosion risk of catalyst residues to the secondary side of the steam generator and the metal pipeline by optimizing the selection and dosage of the catalyst, and supplemented by a sophisticated post-treatment process, thereby ensuring the safe operation and long-term stability of the equipment. At the same time, the technical solution provides a flexible range of target digester usage, which is suitable for sediment removal needs of different scales, and can exhibit excellent dispersion activity under the conventional operating pressure of a pressurized water reactor, further expanding its scope of application and practicality.

[0065] Example 3

[0066] Reference Figure 1 , this embodiment provides a cleaning system, which includes a steam generator 814: for receiving the target digester obtained by the preparation method of embodiment 1;

[0067] Sampling port 840: used to monitor the water quality and sediment content in the steam generator through a monitoring device.

[0068] It should be noted that it also includes a water supply pipeline, which is used to add the target digestion agent to the steam generator;

[0069] Further, the cleaning system comprises,

[0070] The filtering device 832 is used to filter the cooling water containing the exfoliated sediment.

[0071] Furthermore, the cleaning system also includes,

[0072] The sewage pipe 830 is used to discharge or recycle the treated cooling water.

[0073] It should be noted that in the normal operation of the nuclear power plant, nuclear energy is converted into thermal energy through the reactor 812, and then the thermal energy is transferred to the steam generator 814 through the reactor outlet heat pipe 813. In the steam generator, the heat is further transferred to the water, causing it to evaporate into steam, and the steam then enters the turbine 820 through the steam conduit 819 to drive the generator 822 to generate electricity. After the steam does work in the turbine, it enters the condenser 824, is cooled by the cooling water and condenses into water, and then passes through the condensation conduit 836 and auxiliary equipment such as the high-pressure heater 827, and is finally sent back to the steam generator 814 by the water pump 829 to form a closed cycle.

[0074] When in use, during the continuous operation of the steam generator 814, the prepared target digester is continuously or intermittently added to the water supply of the secondary side 816 of the steam generator through a specific water supply pipeline at an appropriate concentration. The addition point is set near the water supply inlet of the steam generator to ensure that the digester is evenly distributed in the entire secondary side system. With the addition of the target digester, the amino functional group quickly forms a stable complex with the iron ions in the iron-containing colloidal sediment on the surface and inside the secondary side 816 of the steam generator, reducing the surface charge of the sediment particles, destroying the electrostatic attraction between the particles, and making the sediment layer loose. At the same time, the good permeability and dispersibility of the target digester enable it to penetrate deep into the sediment, decompose large sediments into smaller particles, increase its suspension and fluidity in water, and under the flushing action of the circulating water flow, the decomposed sediment particles are gradually peeled off from the surface of the secondary side 816 of the steam generator, and enter the subsequent cooling water system through the heat pipe 815 with the water flow. During this period, the water quality and sediment content can be regularly monitored through the steam sampling port 819 and the sampling port 840 to evaluate the digestion effect. The cooling water containing the stripped sediment is filtered through the filter device 832 to further remove the suspended particles to ensure that the water quality meets the reuse standards. Finally, the filtered clean water is discharged through the sewage pipe 830 or returned to the system for recycling. For wastewater with a high sediment concentration, it can be temporarily stored in the emission storage facility 838 for centralized treatment.

[0075] On the other hand, the effect of the target digester is evaluated by regularly monitoring the sediment thickness, water quality parameters and equipment operating efficiency of the secondary side 816 of the steam generator. According to the evaluation results, the dosage, frequency and process parameters of the digester are adjusted in a timely manner to achieve the best sediment removal effect and equipment operating efficiency. At the same time, the operation data is collected, and the synthesis process and application technology of the target digester are continuously optimized and improved to provide strong guarantee for the safe and efficient operation of the nuclear power plant.

[0076] In summary, the cleaning system of the present invention demonstrates unique innovation and significant beneficial effects in improving the operating efficiency of the steam generator, ensuring equipment safety and extending its service life.

[0077] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for preparing a digester, characterized in that: include, Using acetic acid as a catalyst, 4-aminobenzoic acid was synthesized by melt polycondensation to obtain the target digester.

2. The method for preparing a digester according to claim 1, wherein: The method comprises, Under the protection of an inert gas, drying the 4-aminobenzoic acid monomer at 60° C. for at least 12 hours, wherein the purity of the 4-aminobenzoic acid monomer is greater than or equal to 97%; Add the dried 4-aminobenzoic acid monomer and acetic acid catalyst into a reaction kettle, heat to a molten state of 160-200° C. under nitrogen protection, and maintain the temperature for 8-12 hours with stirring; After the reaction is completed, the crude polymer is washed with deionized water and ethanol and then dried in a vacuum drying oven at 60 to 80° C. for 24 to 36 hours to obtain the target digester.

3. The method for preparing a digester according to claim 2, wherein: The step of adding the dried 4-aminobenzoic acid monomer and the acetic acid catalyst into a reaction kettle comprises: 1% to 5% by mass of acetic acid based on the mass of the dried 4-aminobenzoic acid monomer is added into the reaction kettle as a catalyst.

4. A method for removing iron-containing colloidal deposits, characterized in that: The method comprises, Obtaining the target digester by the digester preparation method according to any one of claims 1 to 3; During the continuous operation of the steam generator, the target digester is continuously or intermittently added to the feed water on the secondary side of the steam generator; The target digester forms a stable complex with the iron ions in the iron-containing colloidal sediment, so that the sediment is decomposed.

5. The method for removing iron-containing colloidal deposits as claimed in claim 4, characterized in that: The method further comprises, Under the flushing action of the circulating water flow, the decomposed sediments are peeled off from the secondary side surface of the steam generator and discharged with the water flow.

6. The method for removing iron-containing colloidal deposits according to claim 5, characterized in that: The method further comprises, Cooling water containing exfoliated sediment is filtered to ensure that the water quality meets the reuse standards.

7. The method for removing iron-containing colloidal deposits according to claim 6, characterized in that: The steam generator is a steam generator of a pressurized water reactor, and the pressurized water reactor operates at a pressure of 2.0-5.0 MPa.

8. A cleaning system, characterized in that: A steam generator (814) is used to receive a target digester obtained by the digester preparation method according to any one of claims 1 to 3; Sampling port (840): used to monitor the water quality and sediment content in the steam generator through a monitoring device.

9. The cleaning system according to claim 8, characterized in that: The cleaning system comprises: Filtering device (832): used for filtering cooling water containing exfoliated sediments.

10. The cleaning system according to claim 9, characterized in that: The cleaning system further comprises: Drain pipe (830): used to discharge or recycle the treated cooling water.

Images