Waste heat boiler and descaling method thereof

Abstract

The invention relates to the technical field of waste heat boiler descaling, and discloses a waste heat boiler which comprises a boiler barrel divided into an upper boiler barrel body and a lower boiler barrel body, a steam separation device is arranged in the upper boiler barrel body, and a periodic blowdown device is arranged on the lower boiler barrel body; the third-stage heat exchange module consists of a serpentine tube bundle, a spiral guide plate and a honeycomb heat exchanger; the intelligent adjusting system is provided with an infrared temperature sensor and a PID controller, and smoke flow distribution is adjusted in real time; the descaling method of the waste heat boiler comprises the following steps that S1, chemical pre-cleaning is conducted, specifically, a citric acid solution with the pH being 9.5-10 is injected into the boiler, and circulating cleaning is conducted for 28-30 min; according to the system, scale can be effectively removed through multi-stage cleaning, the service life of the boiler is prolonged, efficient recovery and utilization of flue gas waste heat can be achieved by comprehensively using the efficient heat exchange module and the dust deposition prevention measure of the intelligent regulation and control technology, and the heat efficiency and the operation reliability are improved.

Description

Technical Field

[0001] This invention relates to the field of waste heat boiler descaling technology, specifically to a waste heat boiler and its descaling method. Background Technology

[0002] Waste heat boilers play an important role in industrial production and energy conversion. Their main function is to utilize the waste heat in the flue gas that has already been used to improve the utilization rate of thermal energy and reduce energy waste and pollution emissions.

[0003] Currently available waste heat boilers often suffer from incomplete heat recovery, leading to energy waste, increased operating costs, and the accumulation of fine dust and scale on heat exchange surfaces, severely impacting heat exchange efficiency. This dust and scale further accelerate surface wear, causing a decline in equipment thermal performance and necessitating frequent cleaning or component replacement, thus increasing system maintenance and operating costs. These problems are particularly pronounced under high-temperature and complex operating conditions, significantly affecting waste heat utilization. Therefore, this paper proposes a waste heat boiler and its descaling method. Summary of the Invention

[0004] (a) Technical problems to be solved

[0005] To address the shortcomings of existing technologies, this invention provides a waste heat boiler and its descaling method, which solves the problems that existing waste heat boilers often suffer from incomplete heat recovery and the accumulation of fine dust and scale in flue gas on the heat exchange surface, thus seriously affecting heat exchange efficiency.

[0006] (II) Technical Solution

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A waste heat boiler includes the following components:

[0009] The boiler drum is divided into an upper boiler drum and a lower boiler drum. The upper boiler drum has a built-in steam separation device, and the lower boiler drum is equipped with a periodic sewage discharge device.

[0010] Three-stage heat exchange module: composed of serpentine tube bundle, spiral guide plate and honeycomb heat exchanger;

[0011] Intelligent control system: Equipped with an infrared temperature sensor and a PID controller, it adjusts the flue gas flow distribution in real time;

[0012] Anti-dust accumulation structure: The heat exchange tube surface is sprayed with a nano-dust-reducing coating, combined with a high-frequency acoustic cleaning device.

[0013] Furthermore, in the three-stage heat exchange module, the serpentine tube bundle is made of 316L stainless steel with a wall thickness of 2.5mm and a tube spacing of 1.8 times the tube diameter; the spiral guide plate has an inclination angle of 30° and is made of high-temperature resistant ceramic composite material.

[0014] Based on the aforementioned scheme, the intelligent adjustment system includes an infrared temperature sensor array, with one sensor arranged every 500 mm along the flue gas flow direction; the PID controller is linked with the industrial PLC via the Modbus protocol, with a response time ≤0.5s.

[0015] As a further embodiment of the present invention, the nano-ash-repellent coating in the anti-ash-accumulation structure is composed of SiO2-TiO2 composite particles and a silicone resin matrix, with a contact angle ≥150°; the frequency of the acoustic cleaning device is 20kHz, and the power adjustment range is 200-500W.

[0016] This invention also proposes a method for descaling a waste heat boiler, comprising the following steps:

[0017] S1: Chemical pre-cleaning, inject citric acid solution with pH 9.5-10 into the boiler and circulate for 28-30 minutes;

[0018] S2: Mechanical scraping, using a carbon fiber rotary brush to clean the pipe wall with low damage;

[0019] S3: Ultrasonic enhancement, injecting EDTA complexing agent into a 40kHz ultrasonic field for 20 minutes;

[0020] S4: Passivation treatment, spraying phosphate solution to form a protective film;

[0021] S5: Drying and corrosion prevention, introducing hot nitrogen and injecting vapor phase corrosion inhibitor.

[0022] Furthermore, in S2, the diameter of the carbon fiber rotary brush bristles is 0.15-0.25 mm, the rotation speed is controlled at 300-500 rpm, and the axial feed speed is 20-40 mm / min; the contact pressure between the brush body and the pipe wall is 0.3-0.5 MPa, and compressed air with a pressure of 0.2-0.4 MPa is injected synchronously during the cleaning process. After cleaning, the pipe wall roughness Ra is ≤1.6 μm when inspected with an endoscope; the surface of the carbon fiber rotary brush bristles is inlaid with diamond micro powder with a particle size of 5-10 μm.

[0023] Based on the aforementioned scheme, in step S3, the ultrasonic frequency is 35-45kHz, the EDTA concentration is 0.8-1.2wt%, and the ultrasonic power density is 0.5-1.0W / cm³. 2 .

[0024] As a further embodiment of the present invention, the phosphate solution in S4 is a composite solution of trisodium phosphate and zinc salt, with a pH value of 10-11.

[0025] Furthermore, the vapor phase corrosion inhibitor in S5 is a mixture of dicyclohexylamine nitrite and sodium benzoate, with an injection amount of 0.5-1.0 g / m³. 3 .

[0026] (III) Beneficial Effects

[0027] Compared with the prior art, the present invention provides a waste heat boiler and a descaling method thereof, which has the following beneficial effects:

[0028] 1. In this invention, a chemical pre-cleaning step is used to initially soften and dissolve some scale, providing favorable conditions for subsequent cleaning. A thin layer of scale on the pipe wall surface is removed with low damage by a carbon fiber rotating brush through mechanical scraping. Diamond micro powder further improves the removal efficiency of hard scale. Ultrasonic cleaning accelerates the dissolution of scale and improves cleaning efficiency. Passivation treatment forms a protective film to prevent metal corrosion and further consolidates the descaling effect. The drying and anti-corrosion step forms a vapor phase corrosion inhibitor protective layer, ensuring that the boiler still has good anti-corrosion performance after drying. By combining chemical cleaning with mechanical and physical methods, scale is effectively removed and the service life of the boiler is extended.

[0029] 2. The waste heat boiler of this invention achieves efficient recovery and utilization of waste heat from flue gas by comprehensively utilizing high-efficiency heat exchange modules and intelligent control technology to prevent ash accumulation, thereby improving thermal efficiency and operational reliability.

[0030] 3. This invention utilizes a three-stage heat exchange module with serpentine tube bundles, spiral guide plates, and honeycomb heat exchangers to achieve multi-level recovery of waste heat from flue gas, significantly improving energy utilization efficiency; the intelligent regulation system is equipped with an infrared temperature sensor and a PID controller, which can monitor and precisely control the flue gas flow rate in real time, ensuring that the heat exchange efficiency of each stage is maximized.

[0031] 4. In this invention, the anti-ash accumulation structure is coated with a nano-ash-repellent coating on the surface of the heat exchange tube and combined with a high-frequency acoustic cleaning device, which effectively prevents dust and particulate matter in the flue gas from adhering to the tube wall, reducing the thermal resistance and corrosion risk caused by ash accumulation. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the composition and structure of a waste heat boiler proposed in this invention;

[0033] Figure 2 This is a schematic diagram of the process structure of a waste heat boiler descaling method proposed in this invention. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Example 1

[0036] Reference Figures 1-2 A waste heat boiler, comprising the following components:

[0037] The boiler drum is divided into an upper boiler drum and a lower boiler drum. The upper boiler drum has a built-in steam separation device, such as a cyclone separator or a louvered separator, while the lower boiler drum is equipped with a periodic sewage discharge device.

[0038] The three-stage heat exchange module consists of a serpentine tube bundle, a spiral guide plate, and a honeycomb heat exchanger. It realizes the cascade recovery of waste heat from flue gas. The serpentine tube bundle is made of 316L stainless steel with a wall thickness of 2.5mm and a tube spacing of 1.8 times the tube diameter. The spiral guide plate has an inclination angle of 30° and is made of high-temperature resistant ceramic composite material. Through the three-stage heat exchange module, the serpentine tube bundle, spiral guide plate, and honeycomb heat exchanger realize multi-level recovery of waste heat from flue gas, which significantly improves energy utilization efficiency. The boiler drum is connected to the three-stage heat exchange module through a balance pipe.

[0039] Intelligent control system: Equipped with infrared temperature sensors and PID controllers, it adjusts the flue gas flow distribution in real time. The infrared temperature sensor array is arranged every 500mm along the flue gas flow direction; the PID controller is linked with the industrial PLC via Modbus protocol, with a response time of ≤0.5s. The intelligent control system is equipped with infrared temperature sensors and PID controllers, which can monitor and accurately control the flue gas flow in real time to ensure the maximum heat exchange efficiency of each link.

[0040] Anti-ash accumulation structure: A nano-ash-repellent coating is sprayed onto the surface of the heat exchange tubes, and a high-frequency acoustic cleaning device is used. The nano-ash-repellent coating is composed of SiO2-TiO2 composite particles and a silicone resin matrix, with a contact angle ≥150°. The acoustic cleaning device has a frequency of 20kHz and a power adjustment of 200W. The anti-ash accumulation structure, by spraying a nano-ash-repellent coating onto the surface of the heat exchange tubes and using a high-frequency acoustic cleaning device, effectively prevents dust and particulate matter in the flue gas from adhering to the tube wall, reducing the thermal resistance and corrosion risk caused by ash accumulation.

[0041] This invention also proposes a method for descaling a waste heat boiler, comprising the following steps:

[0042] S1: Chemical pre-cleaning, injecting a citric acid solution with a pH of 9.5 into the boiler and circulating it for 30 minutes to achieve preliminary softening and dissolution of some scale;

[0043] S2: Mechanical scraping, using a carbon fiber rotary brush for low-damage cleaning of the pipe wall. The carbon fiber rotary brush has a bristle diameter of 0.15mm, a rotation speed controlled at 300rpm, and an axial feed speed of 20mm / min. The contact pressure between the brush body and the pipe wall is 0.3MPa to avoid scratching the metal substrate. During the cleaning process, compressed air at a pressure of 0.24MPa is injected simultaneously to peel off loose scale and carry away debris. After cleaning, endoscopic inspection is used to check that the pipe wall roughness Ra≤1.6μm. The surface of the carbon fiber rotary brush bristles is inlaid with diamond micro-powder with a particle size of 5μm, which can improve the removal efficiency of hard scale.

[0044] S3: Ultrasonic enhancement, EDTA complexing agent is injected into a 40kHz ultrasonic field for 20 minutes, the ultrasonic frequency is 35kHz, the EDTA concentration is 0.8wt%, and the ultrasonic power density is 0.5W / cm³. 2 This accelerates the dissolution of scale and improves cleaning efficiency;

[0045] S4: Passivation treatment, spraying phosphate solution to form a protective film. The phosphate solution is a composite solution of trisodium phosphate and zinc salt, with the pH value controlled at 10-11 to prevent metal corrosion and further consolidate the descaling effect.

[0046] S5: Drying and corrosion prevention, introducing hot nitrogen gas and injecting a vapor phase corrosion inhibitor, which is a mixture of dicyclohexylamine nitrite and sodium benzoate, at a dosage of 0.5 g / m³. 3 This forms a protective layer of vapor phase corrosion inhibitor, ensuring that the boiler retains good corrosion resistance even after drying.

[0047] Example 2

[0048] Reference Figures 1-2 A waste heat boiler, comprising the following components:

[0049] The boiler drum is divided into an upper boiler drum and a lower boiler drum. The upper boiler drum has a built-in steam separation device, such as a cyclone separator or a louvered separator, while the lower boiler drum is equipped with a periodic sewage discharge device.

[0050] The three-stage heat exchange module consists of a serpentine tube bundle, a spiral guide plate, and a honeycomb heat exchanger, enabling the cascade recovery of waste heat from flue gas.

[0051] Intelligent control system: Equipped with infrared temperature sensor and PID controller, the system can adjust the flue gas flow distribution in real time, and monitor and control the flue gas flow in real time to ensure the maximum heat exchange efficiency of each link.

[0052] Anti-ash accumulation structure: A nano-ash-repellent coating is sprayed on the surface of the heat exchange tube, and a high-frequency acoustic cleaning device is used to prevent dust and particulate matter in the flue gas from adhering to the tube wall, reducing the thermal resistance and corrosion risk caused by ash accumulation.

[0053] In the three-stage heat exchange module: the serpentine tube bundle is made of 316L stainless steel with a wall thickness of 2.5mm and a tube spacing of 1.8 times the tube diameter; the spiral guide plate has an inclination angle of 30° and is made of high-temperature resistant ceramic composite material; in the intelligent regulation system, an infrared temperature sensor array is arranged every 500mm along the flue gas flow direction; the PID controller is linked with the industrial PLC via Modbus protocol, with a response time ≤0.5s; in the anti-ash accumulation structure, the nano-ash-repellent coating is composed of SiO2-TiO2 composite particles and a silicone resin matrix, with a contact angle ≥150°; the acoustic cleaning device has a frequency of 20kHz and a power adjustment of 500W. Through the comprehensive application of high-efficiency heat exchange modules and intelligent regulation technology to prevent ash accumulation, the efficient recovery and utilization of waste heat from the flue gas is achieved, improving thermal efficiency and operational reliability.

[0054] This invention also proposes a method for descaling a waste heat boiler, comprising the following steps:

[0055] S1: Chemical pre-cleaning, injecting a citric acid solution with a pH of 9.5 into the boiler and circulating it for 30 minutes to achieve preliminary softening and dissolution of some scale;

[0056] S2: Mechanical scraping, using a carbon fiber rotary brush to clean the pipe wall with low damage;

[0057] S3: Ultrasonic enhancement, injecting EDTA complexing agent into a 40kHz ultrasonic field for 20 minutes to accelerate scale dissolution and improve cleaning efficiency.

[0058] S4: Passivation treatment, spraying phosphate solution to form a protective film, preventing metal corrosion and further consolidating the descaling effect;

[0059] S5: Drying and corrosion prevention involves introducing hot nitrogen and injecting a vapor phase corrosion inhibitor to form a protective layer, ensuring that the boiler retains good corrosion resistance after drying.

[0060] It should be noted that in S2, the carbon fiber rotary brush has a bristle diameter of 0.25mm, a rotation speed controlled at 500rpm, and an axial feed speed of 40mm / min; the contact pressure between the brush body and the pipe wall is 0.5MPa to avoid scratching the metal substrate; compressed air at a pressure of 0.4MPa is injected simultaneously during the cleaning process to peel off loose scale and carry away debris; after cleaning, endoscopic inspection shows that the pipe wall roughness Ra≤1.6μm; the surface of the carbon fiber rotary brush bristles is inlaid with diamond micropowder with a particle size of 10μm, which can improve the removal efficiency of hard scale. In S3, the ultrasonic frequency is 45kHz, the EDTA concentration is 1.2wt%, and the ultrasonic power density is 1.0W / cm³. 2 In S4, the phosphate solution is a composite solution of trisodium phosphate and zinc salt, with the pH value controlled at 11. In S5, the vapor phase corrosion inhibitor is a mixture of dicyclohexylamine nitrite and sodium benzoate, with an injection volume of 1.0 g / m³. 3 By combining chemical cleaning with mechanical and physical methods, scale can be effectively removed and the service life of boilers can be extended.

[0061] In the description herein, it should be noted that relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

Claims

1. A waste heat boiler, characterized in that, It includes the following components: The boiler drum is divided into an upper boiler drum and a lower boiler drum. The upper boiler drum has a built-in steam separation device, and the lower boiler drum is equipped with a periodic sewage discharge device. The three-stage heat exchange module consists of a serpentine tube bundle, a spiral guide plate, and a honeycomb heat exchanger; The intelligent control system is equipped with an infrared temperature sensor and a PID controller to adjust the flue gas flow distribution in real time. The structure prevents dust accumulation by spraying a nano-dust-repellent coating on the surface of the heat exchange tubes, combined with a high-frequency acoustic cleaning device.

2. A waste heat boiler according to claim 1, characterized in that, The serpentine tube bundle in the three-stage heat exchange module is made of 316L stainless steel with a wall thickness of 2.5mm and a tube spacing of 1.8 times the tube diameter; the spiral guide plate has an inclination angle of 30° and is made of high-temperature resistant ceramic composite material.

3. A waste heat boiler according to claim 1, characterized in that, The intelligent control system includes an infrared temperature sensor array, with one sensor arranged every 500 mm along the flue gas flow direction. The PID controller is linked with the industrial PLC via the Modbus protocol, with a response time of ≤0.5s.

4. A waste heat boiler according to claim 1, characterized in that, The anti-dust accumulation structure has a nano-dust-repellent coating composed of SiO2-TiO2 composite particles and a silicone resin matrix, with a contact angle ≥150°. The acoustic cleaning device has a frequency of 20kHz and a power adjustment range of 200-500W.

5. The descaling method for a waste heat boiler according to claim 1, characterized in that, Includes the following steps: S1: Chemical pre-cleaning, inject citric acid solution with pH 9.5-10 into the boiler and circulate for 28-30 minutes; S2: Mechanical scraping, using a carbon fiber rotary brush to clean the pipe wall with low damage; S3: Ultrasonic enhancement, injecting EDTA complexing agent into a 40kHz ultrasonic field for 20 minutes; S4: Passivation treatment, spraying phosphate solution to form a protective film; S5: Drying and corrosion prevention, introducing hot nitrogen and injecting vapor phase corrosion inhibitor.

6. The descaling method for a waste heat boiler according to claim 5, characterized in that, The carbon fiber rotary brush in S2 has a bristle diameter of 0.15-0.25 mm, a rotation speed controlled at 300-500 rpm, and an axial feed speed of 20-40 mm / min. The contact pressure between the brush body and the pipe wall is 0.3-0.5 MPa. Compressed air with a pressure of 0.2-0.4 MPa is injected synchronously during the cleaning process. After cleaning, the pipe wall roughness Ra is ≤1.6 μm when inspected with an endoscope. The surface of the carbon fiber rotary brush bristles is inlaid with diamond micro powder with a particle size of 5-10 μm.

7. The descaling method for a waste heat boiler according to claim 5, characterized in that, In S3, the ultrasonic frequency is 35-45kHz, the EDTA concentration is 0.8-1.2wt%, and the ultrasonic power density is 0.5-1.0W / cm³. 2 .

8. The descaling method for a waste heat boiler according to claim 5, characterized in that, The phosphate solution in S4 is a composite solution of trisodium phosphate and zinc salt, with a pH value of 10-11.

9. A method for descaling a waste heat boiler according to claim 5, characterized in that, The vapor phase corrosion inhibitor in S5 is a mixture of dicyclohexylamine nitrite and sodium benzoate, with an injection volume of 0.5-1.0 g / m³. 3 .

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