Method for solving blockage of tail end wastewater pipeline

Abstract

The invention discloses a method for solving blockage of a tail-end wastewater pipeline. The method comprises the following steps: performing segmented treatment on the wastewater pipeline; selecting a cleaning mode according to the scaling thickness; the cleaned pipeline is subjected to protection treatment; a scale inhibitor is added in daily operation; and the pipeline scaling condition is monitored regularly, and the maintenance strategy is adjusted. The method has the beneficial effects that the wastewater pipeline is subjected to segmented treatment, and the cleaning mode is selected according to the scaling thickness, so that the targeted and efficient cleaning process is realized, and the time and the cost of traditional pipe section replacement are greatly reduced. The vibrator and the pipe plug are heated, and reaction gas pressure is combined to assist acid pickling, so that the cleaning efficiency and safety are remarkably improved, and meanwhile, the using amount of acid liquor and environmental pollution are reduced. And the cleaned pipeline is subjected to protection treatment, and a composite protection film with silicate compactness and phosphate anti-scaling performance is formed. EDTA (Ethylene Diamine Tetraacetic Acid) is added as a scale inhibitor in daily operation, so that the formation of scaling is continuously inhibited.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater pipeline cleaning, in particular to a method for solving the blockage of a terminal wastewater pipeline. Background Art

[0002] At present, the main method to solve the blockage of the wastewater pipeline of the terminal wastewater evaporator is to replace the blocked pipe section. The pipe section is made of 2205 stainless steel, and the replacement cost is high. If the blockage location cannot be confirmed and the entire section is replaced, the labor costs such as welding and hoisting will increase, and the working hours will be long.

[0003] The flue gas produced after coal combustion contains sulfur oxides, nitrogen oxides, hydrogen chloride and hydrogen fluoride, etc., which react when passing through the desulfurization absorption tower to form desulfurization waste liquid containing F-, SO42-, SO32-, Cl-, S2-, S2O62-, NO3-, and NO2-. The main component of limestone is CaCO3, which contains various impurities such as MgO, Fe2O3, Al2O3, SiO2, etc. These impurities are the main components of suspended solids in desulfurization wastewater. The main reason for the blockage or reduced flow of wastewater pipelines is that the suspended solids in desulfurization wastewater adhere to the pipe wall, reducing the flow until it is completely blocked. The main method to solve the blockage of the wastewater pipeline of the terminal wastewater evaporator is to replace the blocked pipe section. Because the wastewater pipeline is long, it is difficult to confirm the specific location of the blockage, and there are many bends in the pipeline. It is a common phenomenon that the inner diameter of the pipeline is reduced due to sediment. If all are replaced, the labor costs of welding, hoisting, scaffolding, etc. will increase significantly, and the maintenance cycle will be long, affecting the use of equipment. Summary of the invention

[0004] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0005] In view of the above problems or problems existing in the prior art, the present invention is proposed.

[0006] Therefore, the purpose of the present invention is to provide a method for solving the blockage of terminal wastewater pipelines, which can solve the problem of time-consuming, labor-intensive and costly traditional replacement of pipe sections by segmented treatment and the use of heating, vibration or pickling methods for different scaling thicknesses; use of specially designed pipe plugs and reaction gas pressure-assisted pickling to improve cleaning efficiency and safety; and by forming a composite protective film after cleaning and adding scale inhibitors on a daily basis, effectively extending the service life of the pipeline.

[0007] To solve the above technical problems, the present invention provides the following technical solutions: a method for solving the blockage of terminal wastewater pipelines, which includes segmenting the wastewater pipelines; selecting a cleaning method according to the thickness of the scale; performing protective treatment on the cleaned pipelines; adding scale inhibitors during daily operation; regularly monitoring the scaling of the pipelines and adjusting the maintenance strategy.

[0008] As a preferred solution of the method for solving the blockage of the terminal wastewater pipeline of the present invention, the wastewater pipeline is processed in sections, which includes:

[0009] Disconnect the wastewater pipe inlet section from the spray pump;

[0010] Install multiple shut-off valves and vent valves on the wastewater pipeline to divide the pipeline into multiple sections that can be treated independently;

[0011] Connect the vent valve to the sewage tank to discharge the reaction liquid.

[0012] As a preferred solution of the method for solving the blockage of the terminal wastewater pipeline of the present invention, the cleaning method is selected according to the thickness of the scaling, including:

[0013] When the scale thickness is less than 1mm, use heating and vibration to clean it;

[0014] When the scale thickness is not less than 1mm and less than 2mm, use 8% citric acid for pickling and cleaning;

[0015] When the scale thickness is greater than or equal to 2mm, use 5% dilute hydrochloric acid for pickling and cleaning.

[0016] As a preferred solution of the method for solving the blockage of the terminal wastewater pipeline of the present invention, the heating and rapping method includes:

[0017] Use specially designed heated rappers fixed to the pipe, especially at elbows that are prone to clogging;

[0018] Wrap the heating coil around the pipe, 4-6cm apart;

[0019] Wrap the pipes with insulation;

[0020] Heat to above 100°C and keep warm for 15-30 minutes;

[0021] Start the vibrator to hit the scale until it falls off;

[0022] Use fire water to flush out the dislodged scale.

[0023] As a preferred solution of the method for solving the blockage of the terminal wastewater pipeline of the present invention, wherein: the pickling method includes pickling using a specially designed pipe plug, and the pipe plug includes an acid liquid inlet, a fire water inlet, a stop valve, a check valve, a mixing pipe, a plurality of adapters and a plurality of lockers;

[0024] Among them, the acid liquid inlet is connected with a variety of adapters through a flange, which is suitable for various types of acid-resistant pumps; the fire water inlet is connected with a variety of adapters through a pipe thread, which is suitable for various types of fire water joints, and can also be used to connect compressed gas for purging.

[0025] As a preferred solution of the method for solving the blockage of the terminal wastewater pipeline of the present invention, the pipe plug further comprises:

[0026] Stop valve, used to cut off acid and fire water, and can also be used to adjust the flow of fire water;

[0027] Check valves are used to prevent acid and fire water from flowing back and causing harm to personnel and equipment;

[0028] The mixing pipe is composed of an outer pipe for fire water inlet, an inner pipe for acid inlet and a joint. The Bernoulli principle and the Venturi effect are used to reduce the outlet and improve the pickling efficiency.

[0029] Locking device, used to form a seal at various pipe thread connections to prevent acid leakage.

[0030] As a preferred solution of the method for solving the blockage of the terminal wastewater pipeline of the present invention, the pickling method also includes:

[0031] Pour acid into the inlet pipeline to make the acid react with the scale and generate gases such as carbon dioxide;

[0032] Close the pipe plug valve so that the pipe section has only one outlet, the vent valve;

[0033] The acid liquid is squeezed toward the vent valve by using the pressure of the gas such as carbon dioxide generated by the reaction;

[0034] As the acid moves forward, it continues to react with the newly contacted pipe section, further accelerating the cleaning process;

[0035] When the reaction gas pressure is insufficient, use compressed air or fire water to propel the acid and flush the inner wall of the pipeline at the same time;

[0036] Repeat the above process until the vent valve no longer discharges black turbid liquid.

[0037] As a preferred solution of the method for solving the blockage of the terminal wastewater pipeline of the present invention, the protective treatment of the cleaned pipeline includes:

[0038] A mixed liquid consisting of 0.5% sodium silicate and 1% sodium hexametaphosphate is injected into the pipeline;

[0039] Sodium silicate forms a dense protective layer on the inner wall of the pipeline to prevent further corrosion and pollution of the inner wall of the pipeline;

[0040] Sodium hexametaphosphate can exert its anti-scaling performance to inhibit and prevent the re-formation of scale.

[0041] As a preferred solution of the method for solving the blockage of the terminal wastewater pipeline of the present invention, the scale inhibitor is added in the daily operation, which includes:

[0042] Add 1% EDTA (ethylenediaminetetraacetic acid) as a scale inhibitor to the desulfurization wastewater;

[0043] EDTA can effectively prevent CaCO3 from forming scale in pipelines and equipment;

[0044] EDTA has good anti-scaling effect at both room temperature and high temperature, and is suitable for the operating temperature range of wastewater pipelines and the maximum flue gas temperature of 190°C inside the terminal wastewater evaporator.

[0045] As a preferred solution of the method for solving the blockage of the terminal wastewater pipeline of the present invention, it also includes: regularly monitoring the scaling of the pipeline, recording the scaling thickness and formation speed;

[0046] Adjust cleaning frequency and methods based on monitoring results;

[0047] Compare the scaling conditions of pipes treated with this method with those of untreated pipes to evaluate the effectiveness of the method;

[0048] Based on the evaluation results, optimize the protective film formula and antiscalant concentration to extend the service life of the pipeline and improve the operating efficiency of the system;

[0049] The method is applicable to wastewater pipes with a diameter of 32 mm and made of 316L stainless steel.

[0050] Beneficial effects of the present invention: The present invention realizes a targeted and efficient cleaning process by treating the wastewater pipeline in sections and selecting the cleaning method according to the thickness of the scale, thereby greatly reducing the time and cost of traditional replacement of pipe sections. By using specially designed heating vibrators and pipe plugs, combined with the innovative method of reaction gas pressure-assisted pickling, the cleaning efficiency and safety are significantly improved, while the amount of acid and environmental pollution are reduced. The cleaned pipeline is protected to form a composite protective film with silicate density and phosphate scale resistance, which effectively extends the service life of the pipeline. EDTA is added as a scale inhibitor during daily operation to continuously inhibit the formation of scale and maintain the pipeline in good condition. By establishing a regular monitoring and maintenance strategy adjustment mechanism, a comprehensive, dynamic and continuous solution to the problem of wastewater pipeline blockage is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0052] Figure 1 The overall process diagram of the method for solving the blockage of the terminal wastewater pipeline is shown. DETAILED DESCRIPTION

[0053] 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.

[0054] 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.

[0055] 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.

[0056] Example 1

[0057] Reference Figure 1 , which is the first embodiment of the present invention, and provides a method for solving the blockage of the terminal wastewater pipeline, which includes a method for solving the blockage of the terminal wastewater pipeline, which is suitable for wastewater pipelines with a diameter of 32mm and a material of 316L stainless steel.

[0058] Divide the wastewater pipeline into sections:

[0059] First, disconnect the inlet section of the wastewater pipeline from the spray pump. Install a stop valve and a vent valve every 20 meters to divide the entire pipeline into multiple sections that can be processed independently. Connect each vent valve to the sewage tank to discharge the reaction liquid in the subsequent cleaning process.

[0060] Select the cleaning method according to the scaling thickness:

[0061] Use an endoscope or other detection equipment to check the scale in the pipeline. When the scale thickness is less than 1mm, use heating and vibration to clean it; when the scale thickness is not less than 1mm and less than 2mm, use 8% citric acid for pickling and cleaning; when the scale thickness is greater than or equal to 2mm, use 5% dilute hydrochloric acid for pickling and cleaning.

[0062] Protect the cleaned pipeline:

[0063] A mixed liquid consisting of 0.5% sodium silicate and 1% sodium hexametaphosphate is injected into the pipeline. A specially designed pipe plug is used to inject the mixed liquid into the pipeline to ensure that the inner wall of the pipeline is evenly covered. Sodium silicate forms a dense protective layer on the inner wall of the pipeline to prevent further corrosion and pollution of the inner wall of the pipeline; sodium hexametaphosphate exerts its anti-scaling properties to inhibit and prevent the formation of scale again.

[0064] Add antiscalant in daily operation:

[0065] Add 1% EDTA (ethylenediaminetetraacetic acid) as a scale inhibitor to the desulfurization wastewater. EDTA can effectively prevent CaCO3 from forming scale in pipelines and equipment, and has a good scale inhibition effect at both normal and high temperatures (up to 190°C), and is suitable for the full temperature range of wastewater pipelines.

[0066] Regularly monitor pipeline scaling and adjust maintenance strategies:

[0067] Use an endoscope or other detection equipment to check the scaling in the pipeline every month, and record the scaling thickness and formation speed. According to the monitoring results, adjust the cleaning frequency and method, optimize the protective film formula and the concentration of the scale inhibitor. At the same time, compare the scaling of the pipeline treated with this method with that of the untreated pipeline, evaluate the effectiveness of the method, and make further optimization accordingly.

[0068] Furthermore, the wastewater pipeline is divided into sections for treatment, including:

[0069] Disconnect the wastewater pipe inlet section from the spray pump;

[0070] Install multiple shut-off valves and vent valves on the wastewater pipeline to divide the pipeline into multiple sections that can be treated independently;

[0071] Connect the vent valve to the sewage tank to discharge the reaction liquid.

[0072] Further, the cleaning method selected according to the scaling thickness includes:

[0073] When the scale thickness is less than 1mm, use heating and vibration to clean it;

[0074] When the scale thickness is not less than 1mm and less than 2mm, use 8% citric acid for pickling and cleaning;

[0075] When the scale thickness is greater than or equal to 2mm, use 5% dilute hydrochloric acid for pickling and cleaning.

[0076] Further, the heating and rapping method includes:

[0077] Use specially designed heated rappers fixed to the pipe, especially at elbows that are prone to clogging;

[0078] Wrap the heating coil around the pipe, 4-6cm apart;

[0079] Wrap the pipes with insulation;

[0080] Heat to above 100°C and keep warm for 15-30 minutes;

[0081] Start the vibrator to hit the scale until it falls off;

[0082] Use fire water to flush out the dislodged scale.

[0083] Further, the pickling method includes pickling using a specially designed pipe plug, the pipe plug including an acid inlet, a fire water inlet, a stop valve, a check valve, a mixing pipe, a plurality of adapters and a plurality of lockers;

[0084] Among them, the acid liquid inlet is connected with a variety of adapters through a flange, which is suitable for various types of acid-resistant pumps; the fire water inlet is connected with a variety of adapters through a pipe thread, which is suitable for various types of fire water joints, and can also be used to connect compressed gas for purging.

[0085] Furthermore, the pipe plug also includes:

[0086] Stop valve, used to cut off acid and fire water, and can also be used to adjust the flow of fire water;

[0087] Check valves are used to prevent acid and fire water from flowing back and causing harm to personnel and equipment;

[0088] The mixing pipe is composed of an outer pipe for fire water, an inner pipe for acid and a joint. The Bernoulli principle and the Venturi effect are used to reduce the outlet and improve the pickling efficiency.

[0089] Locking device, used to form a seal at various pipe thread connections to prevent acid leakage.

[0090] Preferably, a pipe plug specially used for pickling is designed, which is mainly composed of an acid liquid inlet, a fire water inlet, a stop valve, a check valve, a mixing pipe, a variety of adapters, and a variety of lockers. The acid liquid inlet can be connected to a variety of adapters through a flange, and is suitable for various types of acid-resistant pumps. The fire water inlet is connected to a variety of adapters through a pipe thread, and is suitable for various types of fire water joints, and can also be purged with compressed gas. The function of the stop valve is to cut off the acid liquid and the fire water, and can also be used to adjust the flow of the fire water. The function of the check valve is to prevent the acid liquid and the fire water from flowing back and causing damage to personnel and equipment. The function of the mixing pipe is to mix the acid liquid with the fire water, and to assist the fire water in pushing the acid liquid forward. The function of the locker is to form a seal at the connection of various pipe threads to prevent acid liquid from leaking.

[0091] Furthermore, the pickling method also includes:

[0092] Pour acid into the inlet pipeline to make the acid react with the scale and generate gases such as carbon dioxide;

[0093] Close the pipe plug valve so that the pipe section has only one outlet, the vent valve;

[0094] The acid liquid is squeezed toward the vent valve by using the pressure of the gas such as carbon dioxide generated by the reaction;

[0095] As the acid moves forward, it continues to react with the newly contacted pipe section, further accelerating the cleaning process;

[0096] When the reaction gas pressure is insufficient, use compressed air or fire water to propel the acid and flush the inner wall of the pipeline at the same time;

[0097] Repeat the above process until the vent valve no longer discharges black turbid liquid.

[0098] Preferably, pickling cleaning:

[0099] For pipe sections with scale thickness greater than or equal to 1mm, use specially designed pipe plugs for pickling. The pipe plugs include the following components:

[0100] Acid inlet: connected with various adapters through flange, suitable for various types of acid-resistant pumps;

[0101] Fire water inlet: connected with various adapters through pipe threads, suitable for various types of fire water joints, and can also be used to connect compressed gas for purging;

[0102] Stop valve: used to cut off acid and fire water, and can also be used to adjust the flow of fire water;

[0103] Check valve: prevents acid and fire water from flowing back, protecting personnel and equipment;

[0104] Mixing pipe: It consists of an outer pipe for fire water, an inner pipe for acid and a joint. It uses the Bernoulli principle and the Venturi effect to reduce the outlet and improve the pickling efficiency.

[0105] Various locking devices: used to form a seal at various pipe thread connections to prevent acid leakage.

[0106] The pickling process is as follows:

[0107] Pour acid (8% citric acid or 5% hydrochloric acid, depending on the thickness of the scale) into the inlet pipeline;

[0108] Close the pipe plug valve so that the pipe section has only one outlet, the vent valve;

[0109] The acid is squeezed toward the vent valve by using the gas pressure of carbon dioxide and other gases generated by the reaction of acid and scaling;

[0110] As the acid moves forward, it continues to react with the newly contacted pipe section, accelerating the cleaning process;

[0111] When the reaction gas pressure is insufficient, use compressed air (0.5-1MPa) or fire water (0.6-0.8MPa) to propel the acid and flush the inner wall of the pipeline at the same time;

[0112] Repeat the above steps until the vent valve no longer discharges black turbid liquid.

[0113] Preferably, first disconnect the inlet section of the wastewater pipeline from the spray water pump, check the scaling in the pipeline, and when the scaling thickness is less than 1mm, install a heating vibrator to heat the pipeline, vibrate the scaling and flush to solve the blockage problem; when the scaling thickness is not less than 1mm, install a pipe plug and pickle in sections to solve the blockage problem. The pickling liquid is 5% dilute hydrochloric acid. Take the pickling waste liquid for inspection every 2-3 hours. When the waste liquid concentration is higher than 4% and there is little suspended matter, the pickling is completed. After the scaling is cleaned, add a mixed liquid of sodium silicate and sodium hexametaphosphate to the pipeline to form a protective film. In daily work, scale inhibitors are added to the desulfurization wastewater to reduce scaling in the pipe.

[0114] Preferably, a specially designed pipe plug is used to inject acid into the inlet pipeline. The acid reacts with the scale to generate gases such as carbon dioxide. At this time, the pipe plug valve is closed, and the pipe section has only one outlet, which is the vent valve. The pressure of gases such as carbon dioxide generated by the reaction gradually increases, squeezing the acid toward the vent valve. At the same time, as the acid moves forward, it continues to react with the newly contacted pipe section, further accelerating the process. The vent valve is connected to the sewage tank, and the reaction liquid is discharged from the vent valve.

[0115]

[0116] By comparing and analyzing four different pickling methods, we can clearly see that the pipe plug reaction gas pressurization method proposed in this invention has significant advantages and innovations. This method cleverly balances multiple key factors such as efficiency, cost, safety and environmental protection, and provides a new solution for industrial pipeline cleaning and maintenance.

[0117] First, from the perspective of efficiency, the pipe plug reaction gas pressurization method is slightly inferior to the acid-resistant water pump pressurization method, but it is significantly better than the traditional acid addition and fire water pressurization methods. It promotes the cleaning process by utilizing the gas pressure generated by the reaction of acid and scaling, which not only improves the cleaning efficiency but also achieves efficient use of resources. This innovative design not only reduces the demand for external energy, but also maximizes the efficiency of acid use.

[0118] Secondly, in terms of cost control, this method performs well. Compared with the acid-resistant water pump pressurization method, it avoids high equipment investment and operating costs; compared with traditional methods, it improves efficiency and reduces labor costs and safety risks. This cost advantage makes the pipe plug reaction gas pressurization method particularly suitable for small and medium-sized enterprises and pipeline systems that require frequent maintenance.

[0119] Safety is the top priority in industrial cleaning processes. The pipe plug reaction gas pressurization method greatly reduces the risk of operators being exposed to hazardous chemicals through a closed system design. Compared with the serious safety hazards of the traditional acid addition method, this method provides a safer operating environment. At the same time, it also avoids the waste of resources and the impact on the normal fire protection system caused by the fire water pressurization method.

[0120] This method also performs well in terms of environmental protection. By efficiently utilizing the acid and the gases produced by the reaction, the amount of chemicals used and the generation of waste liquid are reduced. Compared with the environmental burden caused by the large amount of acid dilution caused by the fire water pressurization method, the pipe plug reaction gas pressurization method is more in line with the increasingly stringent environmental protection requirements.

[0121] Another advantage of this method is its wide applicability. It can effectively handle various degrees of blockage and is suitable for pipe systems of different types and sizes. The operation is relatively simple, which reduces the dependence on professionals, making it easy for small and medium-sized enterprises to adopt an efficient pipe cleaning method.

[0122] In summary, the pipe plug reaction gas pressurization method has achieved an excellent balance in efficiency, cost, safety, environmental protection and applicability. It greatly improves the efficiency and safety of pipeline cleaning, while reducing the operating costs and environmental impact of enterprises, making an important contribution to the sustainable development of industrial production.

[0123] Furthermore, the protective treatment of the cleaned pipeline includes:

[0124] A mixed liquid consisting of 0.5% sodium silicate and 1% sodium hexametaphosphate is injected into the pipeline;

[0125] Sodium silicate forms a dense protective layer on the inner wall of the pipeline to prevent further corrosion and pollution of the inner wall of the pipeline;

[0126] Sodium hexametaphosphate can exert its anti-scaling performance to inhibit and prevent the re-formation of scale.

[0127] Further, the addition of antiscalants in daily operation includes:

[0128] Add 1% EDTA (ethylenediaminetetraacetic acid) as a scale inhibitor to the desulfurization wastewater;

[0129] EDTA can effectively prevent CaCO3 from forming scale in pipelines and equipment;

[0130] EDTA has good anti-scaling effect at both room temperature and high temperature, and is suitable for the operating temperature range of wastewater pipelines and the maximum flue gas temperature of 190°C inside the terminal wastewater evaporator.

[0131] Furthermore, it also includes regular monitoring of pipeline scaling and recording of scaling thickness and formation rate;

[0132] Adjust cleaning frequency and methods based on monitoring results;

[0133] Compare the scaling conditions of pipes treated with this method with those of untreated pipes to evaluate the effectiveness of the method;

[0134] Based on the evaluation results, optimize the protective film formula and antiscalant concentration to extend the service life of the pipeline and improve the operating efficiency of the system;

[0135] The method is applicable to wastewater pipes with a diameter of 32 mm and made of 316L stainless steel.

[0136] Preferably, after a thorough cleaning of the scale inside the system, a special mixed liquid consisting of 0.5% sodium silicate and 1% sodium hexametaphosphate is injected into the pipeline. This unique combination can form a composite protective film on the inner wall of the pipeline, which has both the compactness of silicate and the anti-scaling property of phosphate. Specifically, the addition of sodium silicate can provide a dense protective layer, effectively preventing the inner wall of the pipeline from further corrosion and contamination. Sodium hexametaphosphate can exert its excellent anti-scaling performance, effectively inhibiting and preventing the re-formation of scale. In this way, the service life and operating efficiency of the pipeline will be significantly improved, ensuring the stable operation of the entire system.

[0137] During routine maintenance work, EDTA (ethylenediaminetetraacetic acid), ATMP (aminotrimethylenephosphonic acid) or HEDP (hydroxyethylidene diphosphonic acid) is added to the desulfurization wastewater as a scale inhibitor. Considering that the working temperature of the wastewater pipeline is room temperature, the maximum flue gas temperature inside the terminal wastewater evaporator is 190°C, and the pH value of the desulfurization wastewater is neutral, the main impurity is CaCO3. At the same time, considering that the dry product of the desulfurization wastewater cannot cause pollution to the environment after discharge and must meet environmental protection requirements, 1% concentration of EDTA is selected as a scale inhibitor and added to the desulfurization wastewater. EDTA is a widely used scale inhibitor that can effectively prevent CaCO3 from forming scale in pipelines and equipment, thereby extending the service life of the equipment and improving the operating efficiency of the system. In addition, EDTA has good scale inhibition effects at both normal and high temperatures.

[0138] In summary, the present invention realizes a targeted and efficient cleaning process by treating the wastewater pipeline in sections and selecting the cleaning method according to the thickness of the scale, greatly reducing the time and cost of traditional pipe segment replacement. By using specially designed heating vibrators and pipe plugs, combined with the innovative method of reaction gas pressure-assisted pickling, the cleaning efficiency and safety are significantly improved, while reducing the amount of acid and environmental pollution. The cleaned pipeline is protected to form a composite protective film with silicate density and phosphate scale resistance, which effectively extends the service life of the pipeline. EDTA is added as a scale inhibitor during daily operation to continuously suppress the formation of scale and maintain the pipeline in good condition. By establishing a regular monitoring and maintenance strategy adjustment mechanism, a comprehensive, dynamic and continuous solution to the problem of wastewater pipeline blockage is achieved.

[0139] Example 2

[0140] This embodiment provides a method for solving the blockage of the terminal wastewater pipeline, which includes studying the inhibitory effect of the composite protective film and the scale inhibitor on the scale formation of the wastewater pipeline.

[0141] This example aims to verify the inhibitory effect of the composite protective film and scale inhibitor on the scaling of the wastewater pipeline. The experiment selected two terminal wastewater evaporators (#3 furnace and #4 furnace) of the same model in a thermal power plant as the research object, and the wastewater pipelines of both were made of 316L stainless steel with a diameter of 32mm.

[0142] Experimental preparation and process:

[0143] First, the wastewater pipelines of furnaces #3 and #4 were thoroughly cleaned. A 5% hydrochloric acid solution was used for pickling using the pipe plug reaction gas pressurization method. During the pickling process, the acid injection volume was 4000ml per 100 meters of pipeline, and the reaction time was 3 hours. Fire water was then used to flush the pipeline until the pH value of the discharged liquid returned to neutral.

[0144] After cleaning, the #4 boiler wastewater pipeline was specially treated: a protective liquid was prepared by dissolving 5kg of sodium silicate (0.5%) and 10kg of sodium hexametaphosphate (1%) in 1000L of deionized water. The protective liquid was injected into the pipeline using a specially designed pipe plug device to ensure uniform coverage of the entire inner wall of the pipeline. The injection speed was controlled at 0.5m / s to ensure that the liquid could fully contact the pipe wall. After the injection was completed, it was left to stand for 2 hours to allow the protective film to fully form.

[0145] In daily operation, 1% EDTA is continuously added to the desulfurization wastewater of #4 furnace as a scale inhibitor. Prepare EDTA solution: dissolve 10kg EDTA in 1000L desulfurization wastewater. Use a precision metering pump to continuously add EDTA solution to the wastewater treatment system. The pump flow rate is set to 0.5L / h to keep the EDTA concentration in the system constant at 1%.

[0146] In order to monitor the scaling, an ultrasonic thickness gauge probe was installed every 50 meters on the wastewater pipes of the two furnaces, with a total of 10 probes installed. Thickness measurements were taken at these points every month to record the scaling thickness. At the same time, an endoscope inspection was carried out every two months to observe the distribution and color of scaling on the inner wall of the pipe.

[0147] The experiment lasted for 6 months, during which the operating parameters of the two furnaces were kept the same, including the wastewater flow rate (10m 3 / h), wastewater temperature (60±5℃) and pH value (7.0±0.5). Wastewater samples were taken and analyzed monthly to monitor calcium ion concentration and total hardness.

[0148] The experimental data are shown in the following table:

[0149]

[0150] By comparing the experimental data of furnace #3 and furnace #4, we can clearly see the significant effects of the composite protective film and EDTA scale inhibitor:

[0151] In the first month of the experiment, the #3 furnace had 0.5mm of scaling, while the #4 furnace had only 0.1mm, and the inhibition effect reached 80%. As time went on, this difference became more obvious. By the sixth month, the scaling thickness of the #3 furnace reached 5.4mm, while the #4 furnace was only 2.1mm, and the inhibition effect remained at around 61%. This shows that the combination of composite protective film and EDTA not only effectively inhibits scaling in the early stage, but also can maintain this effect for a long time.

[0152] The calcium concentration of furnace #4 was always lower than that of furnace #3. In the first month, the calcium concentration of furnace #4 (150 mg / L) was 46% lower than that of furnace #3 (280 mg / L). By the sixth month, although the calcium concentration of both furnaces had increased, furnace #4 (210 mg / L) was still 46% lower than furnace #3 (390 mg / L). This shows that EDTA effectively chelates calcium ions and prevents them from depositing and forming scale.

[0153] The total hardness data also reflects the effectiveness of the treatment. Throughout the experiment, the total hardness of furnace #4 remained at a low level. At the 6th month, the total hardness of furnace #4 (4.1mmol / L) was 43% lower than that of furnace #3 (7.2mmol / L). This further confirms the synergistic effect of the composite protective film and EDTA in softening water and preventing scaling.

[0154] It can be calculated that the average scaling rate of furnace #3 is 0.9 mm / month, while that of furnace #4 is only 0.35 mm / month. This means that after adopting the method of the present invention, the scaling rate is reduced by 61%. This significant reduction not only prolongs the cleaning cycle of the equipment, but also greatly reduces maintenance costs and downtime.

[0155] It is worth noting that even in the 6th month, the indicators of furnace #4 are still significantly better than those of furnace #3. This shows that the method of the present invention has good durability and can continue to play a role in long-term operation.

[0156] The combined use of composite protective film and EDTA scale inhibitor showed a significant synergistic effect. The dense protective layer formed by sodium silicate effectively prevented the corrosion of the pipe wall, and sodium hexametaphosphate inhibited the initial formation of scale. The continuous addition of EDTA further chelated the calcium ions in the water, reducing the possibility of scaling from the source. This multiple protection mechanism ensures that the system is effectively protected at all links.

[0157] In summary, the method of using the composite protective film and EDTA scale inhibitor in combination proposed in the present invention has shown excellent anti-scaling effect in practical applications. It not only significantly reduces the scaling rate and extends the cleaning cycle of the equipment, but also improves the operating efficiency of the entire system by improving water quality indicators. The innovation of this method lies in the organic combination of physical barriers (composite protective film) and chemical treatment (EDTA scale inhibition) to achieve all-round and long-term protection of pipelines. Compared with traditional single treatment methods, the present invention shows obvious advantages in both effect durability and comprehensive performance, providing a new, efficient, economical and environmentally friendly option for the maintenance of industrial wastewater pipelines.

[0158] Example 3

[0159] This embodiment provides a method for solving the blockage of the terminal wastewater pipeline, which includes the optimization of the pickling method and the study of the scaling removal efficiency.

[0160] This example aims to study the cleaning effect of different pickling methods on 316L stainless steel wastewater pipelines and their impact on the pipe wall. The experiment selected the wastewater pipeline of the wastewater evaporator at the end of a thermal power plant as the research object, with a pipe diameter of 32mm and a material of 316L stainless steel. The main component of the scale in the pipeline is CaCO3, and it also contains a small amount of CaSO4, MgO, Fe2O3, Al2O3, SiO2, etc.

[0161] Experimental preparation and process:

[0162] First, five pipe sections of 1 meter in length were cut from the wastewater pipeline and numbered A, B, C, D, and E. The scale components on the inner wall of these five pipe sections were analyzed using an X-ray fluorescence spectrometer (XRF) to ensure that the initial conditions were consistent. Subsequently, an ultrasonic thickness gauge was used to measure the scale thickness of each pipe section, and the average scale thickness was determined to be 3 mm.

[0163] Next, different pickling methods were used for the five sections of pipe:

[0164] Section A: 10% sodium bicarbonate solution was used as the control group;

[0165] Section B: Use 8% citric acid solution;

[0166] Section C: Use 5% hydrochloric acid solution;

[0167] Section D: Use 3% hydrochloric acid solution;

[0168] Section E: Using the method of the present invention, firstly use 5% hydrochloric acid for preliminary cleaning, and then use 8% citric acid for fine cleaning.

[0169] During the pickling process, each pipe section is placed vertically, and acid is injected from the top to control the liquid level to be constant at 80 cm. Samples are taken every 10 minutes to measure the pH value and scaling concentration until the pH value and scaling concentration no longer change significantly. At the same time, a high-speed camera is used to record the scaling dissolution process and observe the bubble generation and scaling shedding state.

[0170] For section E, the pipe plug reaction gas pressurization method of the present invention is adopted. First, 5% hydrochloric acid is injected, the pipe section is sealed, and the CO2 gas pressure generated by the reaction is used to promote the acid liquid circulation for 30 minutes. Then the acid liquid is discharged, and 8% citric acid solution is injected, and the pipe section is sealed again and the reaction gas pressure is used to promote the circulation for 50 minutes.

[0171] After pickling, each pipe section was rinsed with deionized water until it was neutral. Subsequently, an endoscope was used to check the cleanliness of the inner wall of the pipeline, and an ultrasonic thickness gauge was used again to measure the remaining scale thickness. Finally, a scanning electron microscope (SEM) was used to observe the surface morphology of the pipe wall and evaluate the impact of pickling on the pipe wall.

[0172] The experimental data are shown in the following table:

[0173]

[0174] By comparing the experimental data of different pickling methods, the following analysis results can be obtained:

[0175] The method of the present invention exhibits the highest removal efficiency, reaching 96.7%, far exceeding other single pickling methods. Although 5% hydrochloric acid is second in efficiency (93.3%), it has serious tube wall corrosion problems. The removal efficiencies of 8% citric acid and 3% hydrochloric acid are relatively low, at 83.3% and 86.7%, respectively. As a control group, 10% sodium bicarbonate has a removal efficiency of only 6.7%, confirming its limitations in treating severe scaling.

[0176] The method of the present invention only causes 1 μm of corrosion on the pipe wall, which is similar to 8% citric acid (2 μm) and 3% hydrochloric acid (3 μm), but much lower than the 8 μm corrosion caused by 5% hydrochloric acid. This shows that the method protects the pipe wall to the greatest extent while ensuring high cleaning efficiency. Although sodium bicarbonate does not cause corrosion, its cleaning effect is minimal.

[0177] The total time of the method of the present invention is 80 minutes, which is not the fastest, but considering its high cleaning efficiency and low corrosivity, this time is very reasonable. 5% hydrochloric acid takes the shortest time (26 minutes), but its corrosiveness makes it difficult to be widely used in practice. The cleaning time of 8% citric acid and 3% hydrochloric acid is 82 minutes and 47 minutes respectively, which is not as efficient and time-consuming as the method of the present invention.

[0178] The residual scale of the method of the present invention is the smallest, only 0.1mm, which means that the pipeline is almost restored to its original state after cleaning. In contrast, even the more effective 5% hydrochloric acid leaves 0.2mm of residual scale. This small difference may lead to significant performance differences in long-term operation.

[0179] First, use strong acid (5% hydrochloric acid) to quickly dissolve most of the scale, and then use mild acid (8% citric acid) for fine cleaning, which not only ensures cleaning efficiency but also reduces damage to the pipe wall. The CO2 gas pressure generated by the reaction of acid and carbonate enhances the penetration ability and circulation efficiency of the acid liquid, which is not available in traditional methods. The closed environment created by the pipe plug not only improves the cleaning efficiency, but also reduces the pollution of acid mist to the environment.

[0180] Although the initial time investment of the method of the present invention is slightly higher, considering its excellent cleaning effect and minimal damage to the pipe wall, it will greatly extend the service life of the pipeline in the long run and reduce maintenance frequency and cost. For example, assuming that the pipeline life is inversely proportional to the corrosion depth, then compared with the 5% hydrochloric acid method, this method can extend the pipeline life by about 8 times.

[0181] In summary, the two-step pickling method combined with reaction gas pressurization proposed in the present invention shows obvious advantages in cleaning efficiency, pipe wall protection, cleaning time and residual scaling. It cleverly balances cleaning efficiency and pipeline protection, providing a new efficient, safe and economical option for industrial pipeline maintenance. This method not only solves the problem of low efficiency or strong corrosiveness of traditional pickling methods, but also improves the cleaning effect through innovative gas pressurization technology.

[0182] Importantly, it should be noted that the construction and arrangement of the present application shown in a plurality of different exemplary embodiments are only exemplary. Although only a few embodiments are described in detail in this disclosure, it should be readily understood by those who refer to this disclosure that many modifications are possible (e.g., the size, scale, structure, shape and proportion of various elements, and parameter values ​​(e.g., temperature, pressure, etc.), installation arrangement, use of materials, color, directional changes, etc.) without substantially departing from the novel teachings and advantages of the subject matter described in the application. For example, the element shown as integrally formed can be composed of multiple parts or elements, the position of the element can be inverted or otherwise changed, and the nature or number or position of the discrete element can be changed or changed. Therefore, all such modifications are intended to be included in the scope of the present invention. The order or sequence of any process or method steps can be changed or reordered according to alternative embodiments. In the claims, any "device plus function" clause is intended to cover the structure of performing the function described herein, and is not only structurally equivalent but also equivalent structure. Without departing from the scope of the present invention, other replacements, modifications, changes and omissions can be made in the design, operating conditions and arrangement of the exemplary embodiments. Therefore, the invention is not limited to a specific embodiment, but extends to numerous modifications still falling within the scope of the appended claims.

[0183] Additionally, in order to provide a concise description of exemplary embodiments, all features of an actual embodiment (ie, those features that are not relevant to the best mode presently contemplated for carrying out the invention or those that are not relevant to implementing the invention) may not be described.

[0184] It will be appreciated that in the development of any actual implementation, as in any engineering or design project, numerous implementation-specific decisions may be made. Such a development effort may be complex and time-consuming, but will be a routine task of design, fabrication, and production for those of ordinary skill having the benefit of this disclosure without undue experimentation.

[0185] 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 solving the blockage of terminal wastewater pipelines, characterized in that: include, Divide the wastewater pipeline into sections; Select the cleaning method according to the thickness of the scale; Carry out protective treatment on the cleaned pipeline; Add antiscalant during daily operation; Regularly monitor pipeline scaling and adjust maintenance strategies.

2. The method for solving the blockage of the terminal wastewater pipeline according to claim 1, characterized in that: The segmented treatment of the wastewater pipeline comprises: Disconnect the wastewater pipe inlet section from the spray pump; Install multiple shut-off valves and vent valves on the wastewater pipeline to divide the pipeline into multiple sections that can be treated independently; Connect the vent valve to the sewage tank to discharge the reaction liquid.

3. The method for solving the blockage of the terminal wastewater pipeline according to claim 2, characterized in that: The cleaning method selected according to the scaling thickness includes: When the scale thickness is less than 1mm, use heating and vibration to clean it; When the scale thickness is not less than 1mm and less than 2mm, use 8% citric acid for pickling and cleaning; When the scale thickness is greater than or equal to 2mm, use 5% dilute hydrochloric acid for pickling and cleaning.

4. The method for solving the blockage of the terminal wastewater pipeline according to claim 3, characterized in that: The heating and rapping method includes: Use specially designed heated rappers fixed to the pipe, especially at elbows that are prone to clogging; Wrap the heating coil around the pipe, 4-6cm apart; Wrap the pipes with insulation; Heat to above 100°C and keep warm for 15-30 minutes; Start the vibrator to hit the scale until it falls off; Use fire water to flush out the dislodged scale.

5. The method for solving the blockage of the terminal wastewater pipeline according to claim 4, characterized in that: The pickling method includes pickling using a specially designed pipe plug, the pipe plug including an acid inlet, a fire water inlet, a stop valve, a check valve, a mixing pipe, a variety of adapters and a variety of lockers; Among them, the acid liquid inlet is connected with a variety of adapters through a flange, which is suitable for various types of acid-resistant pumps; the fire water inlet is connected with a variety of adapters through a pipe thread, which is suitable for various types of fire water joints, and can also be used to connect compressed gas for purging.

6. The method for solving the blockage of the terminal wastewater pipeline according to claim 5, characterized in that: The pipe plug also includes: Stop valve, used to cut off acid and fire water, and can also be used to adjust the flow of fire water; Check valves are used to prevent acid and fire water from flowing back and causing harm to personnel and equipment; The mixing pipe is composed of an outer pipe for fire water, an inner pipe for acid and a joint. The Bernoulli principle and the Venturi effect are used to reduce the outlet and improve the pickling efficiency. Locking device, used to form a seal at various pipe thread connections to prevent acid leakage.

7. The method for solving the blockage of the terminal wastewater pipeline according to claim 6, characterized in that: The pickling method also includes: Pour acid into the inlet pipeline to make the acid react with the scale and generate gases such as carbon dioxide; Close the pipe plug valve so that the pipe section has only one outlet, the vent valve; The acid liquid is squeezed toward the vent valve by using the pressure of the gas such as carbon dioxide generated by the reaction; As the acid moves forward, it continues to react with the newly contacted pipe section, further accelerating the cleaning process; When the reaction gas pressure is insufficient, use compressed air or fire water to propel the acid and flush the inner wall of the pipeline at the same time; Repeat the above process until the vent valve no longer discharges black turbid liquid.

8. The method for solving the blockage of the terminal wastewater pipeline according to claim 7, characterized in that: The protective treatment of the cleaned pipeline includes: A mixed liquid consisting of 0.5% sodium silicate and 1% sodium hexametaphosphate is injected into the pipeline; Sodium silicate forms a dense protective layer on the inner wall of the pipeline to prevent further corrosion and pollution of the inner wall of the pipeline; Sodium hexametaphosphate can exert its anti-scaling performance to inhibit and prevent the re-formation of scale.

9. The method for solving the blockage of the terminal wastewater pipeline according to claim 8, characterized in that: The addition of antiscalant in daily operation includes: Add 1% EDTA (ethylenediaminetetraacetic acid) as a scale inhibitor to the desulfurization wastewater; The EDTA can effectively prevent CaCO3 from forming scale in pipelines and equipment; The EDTA has good anti-scaling effect at both normal temperature and high temperature, and is suitable for the working temperature range of the wastewater pipeline and the maximum flue gas temperature of 190° C. inside the terminal wastewater evaporator.

10. The method for solving the blockage of the terminal wastewater pipeline according to claim 9, characterized in that: It also includes regular monitoring of pipeline scaling and recording scale thickness and formation rate; Adjust cleaning frequency and methods based on monitoring results; Compare the scaling conditions of pipes treated with this method with those of untreated pipes to evaluate the effectiveness of the method; Based on the evaluation results, optimize the protective film formula and antiscalant concentration to extend the service life of the pipeline and improve the operating efficiency of the system; The method is applicable to wastewater pipelines with a diameter of 32 mm and made of 316L stainless steel.

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