Waste incineration waste heat boiler

Abstract

The utility model discloses a waste incineration waste heat boiler which comprises a hearth provided with a heating surface tube panel, and the hearth is provided with a first flue and a second flue in the smoke flowing direction. The first flue comprises a first flue section and a second flue section; the first flue first section and the first flue second section are arranged in the flue gas flowing direction, the first flue first section is provided with a refractory pouring layer on the heating surface tube panel, the first flue second section is provided with a surfacing layer on the heating surface tube panel, and the second flue comprises a second flue first section and a second flue second section; the second flue first section and the second flue second section are arranged in the flue gas flowing direction, the second flue first section is provided with an induction remelting layer on a heating surface tube panel, and the second flue second section is provided with a graphene anti-corrosion layer on the heating surface tube panel; therefore, the accidents that the service life of the heating surface of the waste heat boiler is shortened due to high-temperature chlorine corrosion and the tube panel of the heating surface leaks frequently are avoided, and safe and stable operation of a waste incineration power plant can be guaranteed to the maximum extent.

Description

Technical Field

[0001] This utility model relates to the anti-corrosion design of the heating surface of the waste heat boiler in a waste incineration power plant, and in particular to a waste incineration waste heat boiler. Background Technology

[0002] A waste heat boiler (also known as a recovery boiler or waste heat boiler) is a device that uses high-temperature waste gas, waste liquid, or other waste heat resources from industrial processes to generate steam. Its main function is to recover this waste heat and convert it into usable energy, thereby improving energy efficiency and reducing energy waste.

[0003] Waste incineration has a history of over 100 years, but the development of modern incineration began after the 1960s. Incineration can reduce waste volume by over 85% and weight by over 75%, highlighting its characteristics of volume reduction and harmlessness. Equipped with waste heat boilers as heat recovery devices, it generates high-temperature, high-pressure steam for power generation, thus achieving resource recovery. However, existing waste heat boilers generally suffer from corrosion of the heating surfaces. Corrosion shortens the lifespan of these boilers and leads to frequent leaks in the heating surface tubes, posing a significant threat to the safe and stable operation of waste-to-energy plants. Utility Model Content

[0004] The purpose of this utility model is to solve the technical problem that the heating surface of existing waste heat boilers is easily corroded, and to propose a waste heat boiler for waste incineration.

[0005] The technical problem of this utility model is solved by the following technical solution:

[0006] A waste incineration waste heat boiler includes a furnace with a heat-receiving tube screen. The furnace is provided with a first flue, a second flue, a third flue, a horizontal flue, and an economizer along the flue gas flow direction. The economizer is connected to the horizontal flue, and the flue gas flows out from the outlet of the economizer. The first flue includes a first section and a second section. The first and second sections are arranged along the flue gas flow direction. The first section has a refractory casting layer on the heat-receiving tube screen, and the second section has a weld overlay layer on the heat-receiving tube screen. The second flue includes a first section and a second section. The first and second sections are arranged along the flue gas flow direction. The first section has an induction remelting layer on the heat-receiving tube screen, and the second section has a graphene anti-corrosion layer on the heat-receiving tube screen.

[0007] In some embodiments, the following technical features are also included:

[0008] A base layer is also provided between the heated surface tube screen of the second section of the second flue and the graphene anti-corrosion layer to form a transition between the thermal expansion coefficients of different materials.

[0009] The base layer is made of metal ceramic, and the thickness of the base layer is 100-150 micrometers.

[0010] The thickness of the graphene anti-corrosion layer is 200-250 micrometers.

[0011] The thickness of the refractory casting layer is 50-70mm, and the refractory casting layer is made of silicon carbide or aluminum oxide.

[0012] The thickness of the weld overlay is 1.6-2 mm.

[0013] The chemical composition of the weld overlay includes chromium, nickel, iron, niobium, and molybdenum, with chromium accounting for ≥20.5% of the total mass, iron accounting for ≤5% of the total mass, niobium accounting for ≥3.2% of the total mass, and molybdenum accounting for ≥8% of the total mass.

[0014] The thickness of the induction remelting layer is 0.6-1 mm.

[0015] The chemical composition of the induction remelting layer includes chromium, nickel, and iron, with chromium accounting for ≥10% of the total mass, nickel accounting for ≥70% of the total mass, and iron accounting for <5% of the total mass.

[0016] The first section of the first flue is in the flue gas temperature range of 850℃-1200℃, the second section of the first flue is in the flue gas temperature range of 850℃-950℃, the first section of the second flue is in the flue gas temperature range of 750℃-850℃, and the second section of the second flue is in the flue gas temperature range of 700℃-750℃.

[0017] The beneficial effects of this utility model compared with the prior art include:

[0018] This utility model proposes a waste incineration waste heat boiler. By setting a refractory casting layer in the first section of the first flue, a weld overlay layer in the second section of the first flue, an induction remelting layer in the first section of the second flue, and a graphene anti-corrosion layer in the second section of the second flue, different anti-corrosion technologies are used for different areas according to the design calorific value of the waste incineration power plant. This avoids the shortened lifespan of the waste heat boiler's heating surface due to high-temperature chlorine corrosion and frequent accidents such as leakage of the heating surface tubes and screens, thus maximizing the safe and stable operation of the waste incineration power plant.

[0019] Other beneficial effects of the embodiments of this utility model will be further described below. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of a waste incineration waste heat boiler in the existing technology;

[0021] Figure 2 This is a schematic diagram of the waste incineration waste heat boiler in an embodiment of this utility model.

[0022] Figure label:

[0023] 1. First section of flue 1; 2. Second section of flue 1; 3. First section of flue 2; 4. Second section of flue 2. Detailed Implementation

[0024] The embodiments of this utility model are described in detail below. It should be emphasized that the following description is merely exemplary and not intended to limit the scope and application of this utility model.

[0025] It should be noted that when a component is referred to as being "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component. Furthermore, a connection can be used for fixing, coupling, or communication.

[0026] It should be understood that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inner", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0027] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0028] Over the past decade, with the continuous development of the national economy and the gradual improvement of people's living standards, the calorific value of municipal solid waste has also been increasing. As the calorific value of the waste entering the furnace increases, the flue gas temperature at the outlet of the waste heat boiler, initially designed to be around 850℃, has gradually risen to around 950℃ during operation. This dramatic temperature increase has led to severe thinning of the heating surface due to high-temperature chlorine corrosion. The water-cooled walls of the waste heat boiler in the waste incineration power plant use 5mm thick 20G material. With wall material temperatures exceeding 400℃, the corrosion rate has accelerated dramatically, causing frequent leaks in the water-cooled walls of the waste heat boiler. Figure 1As shown, the existing waste heat boiler only uses refractory materials to line the water-cooled wall in the first section 1 of the flue. This easily leads to a shortened lifespan of the waste heat boiler's heating surface due to high-temperature chlorine corrosion, and frequent accidents such as leakage of the heating surface tubes.

[0029] This utility model proposes a waste heat boiler for waste incineration, such as Figure 2 As shown, this can improve the safety and stability of waste heat boiler operation. Specifically, the waste incineration waste heat boiler includes a furnace with a heated surface tube screen. The furnace is provided with a first flue, a second flue, a third flue, a horizontal flue, and an economizer along the flue gas flow direction. The economizer is connected to the horizontal flue, and the flue gas flows out from the outlet of the economizer. The first flue includes a first flue section 1 and a second flue section 2. The first flue section 1 and the second flue section 2 are arranged along the flue gas flow direction. The first flue section 1 has a refractory casting layer on the heated surface tube screen, and the second flue section 2 has a weld overlay layer on the heated surface tube screen. The second flue includes a second flue section 3 and a second flue section 4. The second flue section 3 and the second flue section 4 are arranged along the flue gas flow direction. The first flue section 3 has an induction remelting layer on the heated surface tube screen, and the second flue section 4 has a graphene anti-corrosion layer on the heated surface tube screen.

[0030] In a preferred embodiment, this invention proposes a waste-to-energy boiler based on corrosion protection of the heating surface. According to the design calorific value of the waste-to-energy power plant, different corrosion protection technologies are used for different areas to maximize the safe and stable operation of the plant. Specifically, the first section of the first flue has a flue gas temperature range of 850℃-1200℃, the second section of the first flue has a flue gas temperature range of 850℃-950℃, the first section of the second flue has a flue gas temperature range of 750℃-850℃, and the second section of the second flue has a flue gas temperature range of 700℃-750℃. Different corrosion protection layers are designed for different areas with varying flue gas temperatures. Generally, the outlet temperature of the second section 2 of the first flue is around 850℃-950℃, and the outlet temperature of the second section 4 of the second flue is around 750℃-700℃. The first section 1 of the waste heat boiler flue (preferably the lower part of the flue) is generally covered with 50-70mm thick refractory castable on the heating surface tube screen to form a refractory castable layer, ensuring that the waste heat boiler flue gas meets the requirements of 850℃ and 2S residence time. The left and right side walls, front walls, rear walls and ceiling of the second section 2 of the flue (preferably the upper part of the flue) are protected against corrosion with a 1.6-2mm thick weld overlay layer. The left and right side walls, front walls and rear walls of the first section 3 of the second flue (preferably the flue gas temperature line area of ​​the second flue of 750℃-850℃) are protected against corrosion with an induction remelting layer of 0.6-1mm thickness. The left and right side walls, rear walls and front walls of the second section 4 of the second flue (preferably the lower part of the second flue) are protected against corrosion with 200-350 micrometer graphene. Preferably, a 2mm thick weld overlay layer and a 0.6mm thick induction remelting layer are provided and completed in the processing workshop. Since the flue gas temperature is relatively low in the lower part of the second flue, a 300-400 micrometer thick graphene anti-corrosion layer is used. Depending on the operation of the production plant after it is put into operation, it can be selectively implemented in the furnace. It has the advantages of strong operability, simple process and small amount of construction.

[0031] In a preferred embodiment, a refractory casting layer is provided in the first section 1 of a flue inside the furnace. The thickness of the refractory casting layer is 50-70mm. The refractory casting material used is silicon carbide or aluminum oxide, and the thermal conductivity is generally controlled at 2-8W / m·K. Its main function is to prevent the heated surface from being corroded by the high-temperature flue gas.

[0032] In a preferred embodiment, a weld overlay layer is provided in the second section 2 of a flue inside the furnace. The weld overlay material is mainly a chromium (Cr) and nickel (Ni) alloy, with a thickness of approximately 2 mm and a heat-affected zone hardness of less than 250 HV. The weld overlay is performed in a layered manner, and the dilution rate is measured using a photospectral analyzer (PMI). The results show that the dilution rate is extremely low: the percentage of iron (Fe) by total mass is generally around 5%. The chemical composition requirements for the weld overlay surface are: Cr ≥ 20.5% by total mass, Fe ≤ 5% by total mass, niobium (Nb) ≥ 3.2% by total mass, and molybdenum (Mo) ≥ 8% by total mass.

[0033] In a preferred embodiment, an induction remelting layer is provided in the first section 3 of the second flue in the furnace. Induction remelting is an optimization of the manual flame spraying technology, employing electro-induction remelting, which has advantages such as small deformation of the tube screen and stronger bonding with the base material. The entire process involves automatic sandblasting, automatic spraying, and automatic induction remelting. After induction welding, the percentage of Cr on the tube screen surface is ≥10% of the total mass, the percentage of Nickel (Ni) is ≥70% of the total mass, and the percentage of Fe is <5% of the total mass, with the thickness controlled at approximately 0.6 mm. The material after induction welding has a strong metallurgical bond with the base material, and the bonding strength between the induction remelting layer and the substrate is more than 10 times that of thermal spraying. Furthermore, the depth of the heat-affected zone on the substrate is small, and the original structure and mechanical properties of the substrate are not altered, resulting in no deformation of the workpiece.

[0034] In a preferred embodiment, a graphene anti-corrosion layer is provided in the second section 4 of the second flue in the furnace: the surface is sandblasted to remove slag, achieving a surface cleanliness standard of Sa2.0, controlling the surface roughness of the tube screen. A 100-150 micrometer thick metal-ceramic layer is sprayed onto the tube screen surface as a base layer, primarily to create a gradient in the coefficient of thermal expansion between the substrate and the functional layer. Then, a 200-250 micrometer thick graphene layer is sprayed as the functional layer (graphene anti-corrosion layer), achieving the coating's anti-corrosion function. The total thickness of the graphene anti-corrosion base layer and the functional layer is controlled at approximately 300-400 micrometers. Here, the substrate refers to the parent material, and the base layer is the bottom layer for the graphene anti-corrosion coating, ensuring better bonding between the graphene coating and the parent material. The coefficient of thermal expansion is highest in the heated tube screen (metal), followed by the base layer, and finally the functional layer. The heated tube screen, base layer, and functional layer together form a transition in the coefficient of thermal expansion.

[0035] The biggest advantage of graphene anti-corrosion coating is that it is simple and convenient to construct in the furnace. It can be selectively implemented according to the subsequent production and operation of the production plant, with a large range of operational options. It can also be used for emergency repairs after the heating surface has been thinned.

[0036] The above description, in conjunction with specific / preferred embodiments, provides a further detailed explanation of the present invention and should not be construed as limiting the specific implementation of the present invention to these descriptions. For those skilled in the art, various substitutions or modifications can be made to these described embodiments without departing from the concept of the present invention, and all such substitutions or modifications should be considered within the protection scope of the present invention. In the description of this specification, the reference to terms such as "an embodiment," "some embodiments," "preferred embodiment," "example," "specific example," or "some examples," etc., indicates that the specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the described specific features, structures, materials, or characteristics can be combined in a suitable manner in any one or more embodiments or examples. Without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification and the features of different embodiments or examples. Although embodiments of the present invention and their advantages have been described in detail, it should be understood that various changes, substitutions and alterations may be made herein without departing from the scope of protection of the patent application.

Claims

1. A waste incineration waste heat boiler, characterized in that, The furnace includes a furnace with a heated surface tube screen. The furnace is equipped with a first flue, a second flue, a third flue, a horizontal flue, and an economizer along the flue gas flow direction. The economizer is connected to the horizontal flue, and flue gas flows out from the economizer's outlet. The first flue includes a first section and a second section. The first and second sections are arranged along the flue gas flow direction. The first section has a refractory casting layer on the heated surface tube screen, and the second section has a weld overlay layer on the heated surface tube screen. The second flue includes a first section and a second section. The first and second sections are arranged along the flue gas flow direction. The first section has an induction remelting layer on the heated surface tube screen, and the second section has a graphene anti-corrosion layer on the heated surface tube screen.

2. The waste incineration waste heat boiler as described in claim 1, characterized in that, A base layer is also provided between the heated surface tube screen of the second section of the second flue and the graphene anti-corrosion layer to form a transition between the thermal expansion coefficients of different materials.

3. The waste incineration waste heat boiler as described in claim 2, characterized in that, The base layer is made of metal ceramic, and the thickness of the base layer is 100-150 micrometers.

4. The waste incineration waste heat boiler as described in claim 3, characterized in that, The thickness of the graphene anti-corrosion layer is 200-250 micrometers.

5. The waste incineration waste heat boiler as described in claim 1, characterized in that, The thickness of the refractory casting layer is 50-70mm, and the refractory casting layer is made of silicon carbide or aluminum oxide.

6. The waste incineration waste heat boiler as described in claim 1, characterized in that, The thickness of the weld overlay is 1.6-2 mm.

7. The waste incineration waste heat boiler as described in claim 6, characterized in that, The chemical composition of the weld overlay includes chromium, iron, niobium, and molybdenum, with chromium accounting for ≥20.5% of the total mass, iron accounting for ≤5% of the total mass, niobium accounting for ≥3.2% of the total mass, and molybdenum accounting for ≥8% of the total mass.

8. The waste incineration waste heat boiler as described in claim 1, characterized in that, The thickness of the induction remelting layer is 0.6-1 mm.

9. The waste incineration waste heat boiler as described in claim 8, characterized in that, The chemical composition of the induction remelting layer includes chromium, nickel, and iron, with chromium accounting for ≥10% of the total mass, nickel accounting for ≥70% of the total mass, and iron accounting for <5% of the total mass.

10. The waste incineration waste heat boiler as described in claim 1, characterized in that, The first section of the first flue is in the flue gas temperature range of 850℃-1200℃, the second section of the first flue is in the flue gas temperature range of 850℃-950℃, the first section of the second flue is in the flue gas temperature range of 750℃-850℃, and the second section of the second flue is in the flue gas temperature range of 700℃-750℃.

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