Ash removal device
The ash removal device uses an injection system with aqueous sulfite solution and controlled water injection to physically remove ash and chemically decompose residual chlorides, addressing corrosion issues in furnaces by enhancing corrosion resistance and reducing sulfidation corrosion.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- IHI CORP
- Filing Date
- 2022-05-26
- Publication Date
- 2026-06-30
AI Technical Summary
Existing ash removal devices in furnaces, such as boilers, are inadequate in fully removing adhering ash, leading to corrosion due to residual ash and chlorides, which exacerbates furnace degradation.
An ash removal device equipped with an injection unit, water and sulfite supply sources, and a control system to inject an aqueous sulfite solution followed by water, physically removing ash and chemically decomposing residual chlorides, while minimizing corrosion risks.
Effectively suppresses furnace corrosion by physically removing ash and chemically decomposing chlorides, enhancing corrosion resistance and reducing sulfidation corrosion in the device's flow path.
Smart Images
Figure 0007881986000001 
Figure 0007881986000002 
Figure 0007881986000003
Abstract
Description
Technical Field
[0001] The present disclosure relates to an ash removal device.
Background Art
[0002] In a furnace such as a boiler, ash is generated along with the combustion of fuel. The generated ash adheres to the inner surface of the furnace wall of the furnace or the surface of a device (for example, a superheater) inside the furnace. The ash adhering in the furnace contains chlorides such as potassium chloride (KCl) or sodium chloride (NaCl). Therefore, the portion where ash adheres in the furnace may be corroded by the ash. In order to suppress corrosion by ash in the furnace, for example, as disclosed in Patent Document 1, an ash removal device that sprays water onto the ash adhering in the furnace to remove the ash is used. Such an ash removal device is also called a soot blower.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] In the above ash removal device that sprays water, there are cases where the ash adhering in the furnace cannot be sufficiently removed. The ash remaining without being removed becomes a factor for promoting the corrosion of the furnace. Therefore, it is desirable to more appropriately suppress the corrosion by ash in the furnace.
[0005] An object of the present disclosure is to provide an ash removal device capable of suppressing corrosion by ash in a furnace.
Means for Solving the Problems
[0006] To solve the above problems, the ash removal apparatus of this disclosure comprises an injection unit facing the inner surface of the furnace wall of a furnace or the surface of an apparatus inside the furnace, a water supply source connected to the injection unit which is a water supply source, and a sulfite supply source connected to the injection unit which is a sulfite supply source, A control device that performs a first injection control to inject an aqueous sulfite solution, in which sulfite is dissolved in water, from an injection unit, Equipped with The control device then performs a second injection control, which involves injecting water without dissolved sulfites from the injection nozzle after performing the first injection control. .
[0009] Sulfite may be replaced with sodium sulfite. [Effects of the Invention]
[0010] According to this disclosure, corrosion caused by ash in a furnace can be suppressed. [Brief explanation of the drawing]
[0011] [Figure 1] Figure 1 is a schematic diagram showing a boiler according to an embodiment of the present disclosure. [Figure 2] Figure 2 is a schematic diagram showing an ash removal device according to an embodiment of the present disclosure. [Figure 3] Figure 3 is a schematic diagram showing the first injection control being performed in an ash removal device according to an embodiment of this disclosure. [Figure 4] Figure 4 is a schematic diagram showing how the second injection control is performed in the ash removal device according to the embodiment of this disclosure. [Modes for carrying out the invention]
[0012] Embodiments of this disclosure will be described below with reference to the attached drawings. The dimensions, materials, and other specific numerical values shown in the embodiments are merely examples for the purpose of facilitating understanding and do not limit this disclosure unless otherwise specified. In this specification and drawings, elements having substantially the same function or configuration are denoted by the same reference numerals to avoid redundant explanations, and elements not directly related to this disclosure are omitted from the illustrations.
[0013] Figure 1 is a schematic diagram showing a boiler 1 according to this embodiment. As shown in Figure 1, the boiler 1 comprises a furnace 2, a flue 3, and a burner 4.
[0014] The furnace 2 is a furnace that generates combustion heat by burning fuel. Examples of fuels used in the furnace 2 include biomass. However, as will be described later, fuels other than biomass may be used in the furnace 2. The furnace 2 has a cylindrical shape, such as a rectangular cylinder extending in the vertical direction. High-temperature combustion gases are generated in the furnace 2 when the fuel burns. An outlet 2a is provided at the bottom of the furnace 2 to discharge the ash generated by the combustion of the fuel to the outside.
[0015] Flue 3 is a passage that guides the combustion gases generated in the furnace 2 to the outside as exhaust gas. Flue 3 is connected to the top of the furnace 2. Flue 3 has a horizontal flue 3a and a rear flue 3b. The horizontal flue 3a extends horizontally from the top of the furnace 2. The rear flue 3b extends downward from the end of the horizontal flue 3a.
[0016] Boiler 1 is equipped with multiple superheaters 5. The superheaters 5 are located at the top of the furnace 2 or in the flue 3. Water flows inside the superheaters 5. Heat exchange takes place between the combustion heat generated in the furnace 2 and the water inside the superheaters 5. This generates steam. Boiler 1 may also be equipped with various devices such as economizers or air preheaters, which are not shown in Figure 1.
[0017] The burner 4 is located on the lower wall of the furnace 2. Multiple burners 4 are installed in the furnace 2 at intervals in the circumferential direction of the furnace 2. Although not shown in Figure 1, the multiple burners 4 are also installed at intervals in the vertical direction, which is the direction in which the furnace 2 extends. The burner 4 injects fuel into the internal space 2b of the furnace 2. When the fuel injected from the burner 4 burns, a flame F is formed in the internal space 2b of the furnace 2. The furnace 2 is also equipped with an ignition device (not shown) that ignites the fuel injected from the burner 4.
[0018] FIG. 2 is a schematic diagram showing the ash removal device 10 according to the present embodiment. The ash removal device 10 is provided in the boiler 1 to remove the ash A generated along with the combustion in the furnace 2 and adhering to the inside of the furnace 2. The surface where the ash A adheres in the furnace 2 is any surface facing the internal space 2b among the surfaces inside the furnace 2. Specifically, the surface where the ash A adheres in the furnace 2 is the inner surface of the furnace wall 2c of the furnace 2 or the surface of a device (for example, the superheater 5) inside the furnace 2. In the example described below, an example in which the ash removal device 10 removes the ash A adhering to the surface 5a of the superheater 5 will be described. However, the ash removal device 10 may remove the ash A adhering to a location other than the surface 5a of the superheater 5. For example, the ash removal device 10 may remove the ash A adhering to the inner surface of the furnace wall 2c of the furnace 2 (in the example of FIG. 2, the left surface of the furnace wall 2c), or the ash A adhering to the surface of a device inside the furnace 2 other than the superheater 5.
[0019] As shown in FIG. 2, the ash removal device 10 includes an injection unit 11, a water supply source 12, a first pipe 13, a first valve 14, a sulfite supply source 15, a second pipe 16, a second valve 17, and a control device 18.
[0020] As will be described later, the injection unit 11 injects a liquid (specifically, an aqueous sulfite solution or water) supplied to the injection unit 11 through the first pipe 13. The injection unit 11 has a substantially cylindrical shape and is a nozzle for injecting a liquid. The injection unit 11 is attached to penetrate the furnace wall 2c of the furnace 2. The injection port 11a of the injection unit 11 is disposed inside the internal space 2b of the furnace 2. The opening 11b on the side opposite to the injection port 11a side of the injection unit 11 is disposed outside the furnace 2. The first pipe 13 is connected to the opening 11b. The liquid is supplied from the first pipe 13 into the injection unit 11 through the opening 11b, and the liquid is injected from the injection port 11a. The injection port 11a faces the surface 5a of the superheater 5. Therefore, the liquid is injected from the injection port 11a toward the surface 5a of the superheater 5. Thus, the injection unit 11 faces the surface 5a of the superheater 5.
[0021] The water supply source 12 is a source of water connected to the injection unit 11. For example, the water supply source 12 is a tank for storing water. However, the water supply source 12 may be any device that generates water. The water supply source 12 is connected to the opening 11b of the injection unit 11 via the first pipe 13. The water supply source 12 communicates with the inside of the injection unit 11 via the first pipe 13. Thereby, water can be supplied from the water supply source 12 to the injection unit 11 via the first pipe 13.
[0022] A first valve 14 is provided in the first pipe 13. The first valve 14 can open and close the first pipe 13. By opening and closing the first valve 14, the state in which water is supplied from the water supply source 12 to the injection unit 11 and the state in which the supply of water from the water supply source 12 to the injection unit 11 is stopped can be switched. The supply of water from the water supply source 12 to the injection unit 11 is realized, for example, by a pump (not shown) provided in the first pipe 13. Note that the opening degree of the first valve 14 may be adjustable. By adjusting the opening degree of the first valve 14, the amount of water supplied from the water supply source 12 to the injection unit 11 is adjusted.
[0023] The sulfite supply source 15 is a source of sulfite connected to the injection unit 11. For example, the sulfite supply source 15 is a tank for storing sulfite. However, the sulfite supply source 15 may be any device that generates sulfite. The sulfite supply source 15 is connected to the first pipe 13 via the second pipe 16. Specifically, the second pipe 16 is connected to a portion of the first pipe 13 on the injection unit 11 side of the first valve 14. The sulfite supply source 15 communicates with the inside of the first pipe 13 via the second pipe 16. Thereby, sulfite can be supplied from the sulfite supply source 15 to the first pipe 13 via the second pipe 16. Examples of the sulfite supplied from the sulfite supply source 15 include sodium sulfite (Na2SO3) or potassium sulfite (K2SO3).
[0024] A second valve 17 is provided in the second pipe 16. The second valve 17 can open and close the second pipe 16. By opening and closing the second valve 17, it is possible to switch between a state in which sulfite is supplied from the sulfite supply source 15 to the first pipe 13 and a state in which the supply of sulfite from the sulfite supply source 15 to the first pipe 13 is stopped. The supply of sulfite from the sulfite supply source 15 to the first pipe 13 is achieved, for example, by a fan (not shown) provided in the second pipe 16. When water is supplied from the water supply source 12 to the injection unit 11, sulfite is supplied from the sulfite supply source 15 to the first pipe 13, causing the sulfite to dissolve in the water in the first pipe 13 and produce an aqueous sulfite solution. The aqueous sulfite solution produced in the first pipe 13 is supplied to the injection unit 11 via the first pipe 13. The opening degree of the second valve 17 may be adjustable. The amount of sulfite supplied from the sulfite supply source 15 to the first pipe 13 is adjusted by adjusting the opening degree of the second valve 17.
[0025] The control device 18 includes a central processing unit (CPU), a ROM containing programs, RAM as a work area, and other components, and controls the entire ash removal device 10. In particular, the control device 18 controls the operation of the first valve 14 and the second valve 17, respectively. As a result, the control device 18 can switch between a state in which water is supplied from the water supply source 12 to the injection unit 11 and a state in which the supply of water from the water supply source 12 to the injection unit 11 is stopped. The control device 18 can also switch between a state in which sulfite is supplied from the sulfite supply source 15 to the first pipe 13 and a state in which the supply of sulfite from the sulfite supply source 15 to the first pipe 13 is stopped.
[0026] As described above, the control device 18 can control the supply state of liquid to the injection unit 11 by controlling the operation of the first valve 14 and the second valve 17, respectively. This allows the control device 18 to switch whether or not liquid is injected by the injection unit 11, and to switch the type of liquid injected from the injection unit 11.
[0027] Figure 3 is a schematic diagram showing the first injection control being performed in the ash removal device 10 according to this embodiment. As shown in Figure 3, the control device 18 performs the first injection control to inject an aqueous sulfite solution SW, in which sulfite S is dissolved in water W, from the injection unit 11. In the first injection control, the control device 18 opens both the first valve 14 and the second valve 17. As a result, water W is supplied from the water supply source 12 to the injection unit 11 via the first pipe 13. Furthermore, sulfite S is supplied from the sulfite supply source 15 to the first pipe 13 via the second pipe 16. Therefore, sulfite S dissolves in water W within the first pipe 13 to generate an aqueous sulfite solution SW.
[0028] The sulfite aqueous solution SW generated in the first pipe 13 is supplied to the injection unit 11 via the first pipe 13 and injected from the injection port 11a of the injection unit 11 toward the surface 5a of the superheater 5. In the first injection control, the injection of the sulfite aqueous solution SW may be performed sporadically for a predetermined time or intermittently. The sulfite aqueous solution SW injected from the injection port 11a of the injection unit 11 collides with the ash A adhering to the surface 5a of the superheater 5. The physical impact force caused by the collision of the sulfite aqueous solution SW with the ash A causes the ash A to fall off the surface 5a of the superheater 5. In this case, some of the ash A may remain on the surface 5a of the superheater 5 without falling off.
[0029] Ash A contains chlorides such as potassium chloride (KCl) or sodium chloride (NaCl). Therefore, there is a risk that the superheater 5 may be corroded by ash A that remains without falling off. On the other hand, the ash removal device 10 can decompose the chlorides contained in ash A remaining on the surface 5a of the superheater 5 by spraying the sulfite aqueous solution SW onto the surface 5a of the superheater 5. Specifically, the chlorides contained in ash A are decomposed by the reaction shown in the following formula (1).
[0030] 2KCl+SO2+1 / 2O2+H2O → K2SO4+2HCl ··· Formula (1)
[0031] Equation (1) shows an example in which potassium chloride contained in ash A is decomposed and released as hydrogen chloride (HCl). Specifically, potassium chloride is decomposed by reacting with sulfur dioxide (SO2) in the sulfite aqueous solution SW. Other chlorides contained in ash A are decomposed in the same way. As a result, corrosion of the superheater 5 by ash A is suppressed. The function of decomposing chlorides contained in ash A by the sulfite aqueous solution SW adhering to the surface 5a of the superheater 5 is maintained for a predetermined period even after the first injection control.
[0032] As described above, the ash removal device 10 sprays the sulfite aqueous solution SW from the spray unit 11, thereby physically removing the ash A adhering to the surface 5a of the superheater 5 by impact force, and then decomposes the chlorides contained in the ash A that remain without being removed. The sulfite aqueous solution SW is weakly alkaline. As a result, the corrosion resistance of the parts of the superheater 5 to which the sulfite aqueous solution SW is adhering is improved. Furthermore, the sulfite ions (SO3) in the sulfite aqueous solution SW 2- The dissolved oxygen reacts with the dissolved oxygen, removing it. This suppresses corrosion of the superheater 5 caused by dissolved oxygen.
[0033] Alternatively, it is conceivable to spray an aqueous sulfate solution, in which a sulfate such as sodium sulfate (Na2SO4) or potassium sulfate (K2SO4) is dissolved in water W, from the spray unit 11 to physically detach the ash A adhering to the surface 5a of the superheater 5, and then decompose the chlorides contained in the ash A that remains. However, the aqueous sulfate solution is neutral. As a result, the corrosion protection of the parts of the superheater 5 to which the aqueous sulfate solution adheres will be lower compared to when an aqueous sulfite solution SW is used. Furthermore, there is a risk that corrosion may progress due to the aqueous sulfate solution itself.
[0034] It is preferable that the concentration of the sulfite aqueous solution SW sprayed from the spray unit 11 be set to a concentration within an appropriate concentration range having a lower limit and an upper limit.
[0035] The lower limit of the concentration of the sulfite aqueous solution SW is preferably set so that almost all of the dissolved oxygen in the sulfite aqueous solution SW is removed. In other words, the lower limit of the concentration of the sulfite aqueous solution SW is preferably the lowest possible concentration that can almost completely remove the dissolved oxygen in the sulfite aqueous solution SW. For example, when sodium sulfite is used as the sulfite aqueous solution SW, the lower limit of the concentration of the sodium sulfite aqueous solution is set to 0.01%. By setting the lower limit of the concentration of the sulfite aqueous solution SW as described above, almost all of the dissolved oxygen in the sulfite aqueous solution SW is removed, and corrosion caused by dissolved oxygen is suppressed.
[0036] The upper limit of the concentration of the sulfite aqueous solution SW is preferably set so as to prevent some of the sulfite S from precipitating as a solid because it does not completely dissolve in the sulfite aqueous solution SW. In other words, the upper limit of the concentration of the sulfite aqueous solution SW is preferably the highest possible concentration that prevents some of the sulfite S from precipitating as a solid because it does not completely dissolve in the sulfite aqueous solution SW. For example, when sodium sulfite is used as the sulfite aqueous solution SW, the upper limit of the concentration of the sodium sulfite aqueous solution is set to 5%. By setting the upper limit of the concentration of the sulfite aqueous solution SW as described above, the precipitation of some of the sulfite S as a solid is prevented, and clogging of the spray section 11 by the precipitated sulfite S is suppressed.
[0037] The control device 18 performs the first injection control, for example, when a predetermined period has elapsed since the previous execution of the first injection control. In this case, the first injection control is repeated at predetermined intervals. Specifically, the predetermined period is the time it takes for a certain amount of ash A to accumulate on the surface 5a of the superheater 5.
[0038] Figure 4 is a schematic diagram showing the second injection control being performed in the ash removal device 10 according to this embodiment. As shown in Figure 4, after performing the first injection control, the control device 18 performs a second injection control in which water W in which sulfite S is not dissolved is injected from the injection unit 11. In the second injection control, the control device 18 opens the first valve 14 and closes the second valve 17. As a result, with the supply of sulfite S from the sulfite supply source 15 to the first pipe 13 stopped, water W is supplied from the water supply source 12 to the injection unit 11 via the first pipe 13. The water W supplied to the injection unit 11 is injected from the injection port 11a of the injection unit 11. In the second injection control, the injection of water W may be performed sporadically for a predetermined time or intermittently.
[0039] In the first injection control described above, the sulfite aqueous solution SW flows through a portion of the first pipe 13 (specifically, the portion of the first pipe 13 closer to the injection section 11 than the point where it merges with the second pipe 16) and inside the injection section 11. Therefore, the sulfite aqueous solution SW remains in a portion of the first pipe 13 and on the inner surface of the injection section 11, which may cause sulfidation corrosion of the first pipe 13 and the injection section 11. Sulfidation corrosion is corrosion caused by hydrogen sulfide (H2S) produced by the sulfite aqueous solution SW. By performing the second injection control described above after the first injection control, the sulfite aqueous solution SW remaining in a portion of the first pipe 13 and on the inner surface of the injection section 11 can be washed away with water W. This suppresses sulfidation corrosion in the flow path of the ash removal device 10.
[0040] In the second injection control, it is preferable that the water W injected from the nozzle 11a of the injection unit 11 does not reach the surface 5a of the superheater 5. For example, the control device 18 makes the flow rate of water W injected from the nozzle 11a in the second injection control smaller than the flow rate of the sulfite aqueous solution SW injected from the nozzle 11a in the first injection control. The flow rate of the liquid injected from the nozzle 11a can be adjusted, for example, by adjusting the output of a pump (not shown) provided in the first piping 13. By preventing the water W injected from the nozzle 11a from reaching the surface 5a of the superheater 5, the generation of thermal stress caused by contact between the water W and the superheater 5 is suppressed.
[0041] From the viewpoint of more effectively suppressing sulfur corrosion in the flow path of the ash removal device 10, it is preferable that the second pipe 16 be connected to the first pipe 13 as close as possible to the injection section 11. This narrows the range in which the sulfite aqueous solution SW remains after the first injection control is performed in the flow path of the ash removal device 10. Therefore, sulfur corrosion in the flow path of the ash removal device 10 is more effectively suppressed.
[0042] As described above, the ash removal device 10 comprises an injection unit 11 facing the inner surface of the furnace wall 2c of the furnace 2, or the surface of an internal device of the furnace 2 (in the above example, the surface 5a of the superheater 5), a water supply source 12 connected to the injection unit 11 which is a water W supply source, and a sulfite supply source 15 connected to the injection unit 11 which is a sulfite S supply source. As a result, an aqueous sulfite solution SW can be injected from the injection unit 11 to the areas in the furnace 2 where ash A has adhered, so that the ash A can be removed by physical impact force and the chlorides contained in the remaining ash A can be decomposed. Therefore, corrosion caused by ash A in the furnace 2 is suppressed.
[0043] Furthermore, in the ash removal device 10, the sulfite aqueous solution SW sprayed from the injection unit 11 is weakly alkaline, which improves corrosion resistance at locations in the furnace 2 where the sulfite aqueous solution SW adheres. In addition, the sulfite ions (SO3) in the sulfite aqueous solution SW 2-The solution reacts with dissolved oxygen, removing it. This suppresses corrosion caused by dissolved oxygen in the furnace 2. In addition, in the ash removal device 10, since the sulfite aqueous solution SW sprayed from the spray unit 11 is a liquid, clogging of the spray unit 11 is suppressed compared to when a slurry-like fluid is sprayed from the spray unit 11.
[0044] In particular, in the ash removal device 10, the control device 18 performs a first injection control, injecting a sulfite aqueous solution SW, in which sulfite S is dissolved in water, from the injection unit 11. This effectively removes the ash A adhering to the inside of the furnace 2 by physical impact force, and then decomposes the chlorides contained in the ash A that remain without being removed. Therefore, corrosion caused by ash A in the furnace 2 is effectively suppressed.
[0045] In particular, in the ash removal device 10, the control device 18 performs a second injection control, which involves injecting water W in which sulfite S is not dissolved from the injection unit 11 after performing a first injection control. This allows the sulfite aqueous solution SW remaining in the flow path of the ash removal device 10 after the first injection control to be washed away with water W. Therefore, sulfidation corrosion in the flow path of the ash removal device 10 is suppressed.
[0046] In particular, in the ash removal device 10, the sulfite S is sodium sulfite. This specifically enables the decomposition of chlorides contained in the ash A adhering to the inside of the furnace 2. Therefore, it specifically enables the suppression of corrosion caused by ash A in the furnace 2.
[0047] While embodiments of this disclosure have been described above with reference to the attached drawings, it goes without saying that this disclosure is not limited to such embodiments. It will be obvious to those skilled in the art that various modifications or alterations can be conceived within the scope of the claims, and these will naturally also fall within the technical scope of this disclosure.
[0048] The above describes an example in which biomass is used as fuel in furnace 2. In this case, ash A is particularly likely to be generated during combustion in furnace 2. Therefore, it is more important to remove ash A using the ash removal device 10 described above. However, the fuel used in furnace 2 may be a fuel other than biomass. For example, a fuel containing fossil fuels may be used in furnace 2.
[0049] This disclosure contributes to suppressing corrosion caused by ash in furnaces used in boilers and the like, and can therefore contribute, for example, to Sustainable Development Goal (SDG) 7, "Ensure access to affordable, reliable, sustainable and modern energy," and Goal 13, "Take urgent action to combat climate change and its impacts." [Explanation of symbols]
[0050] 2 Furnace 2c furnace wall 5. Superheater (device inside the furnace) 5a surface 10 Ash removal device 11 Injection part 12 Water sources 15. Sulfite sources 18 Control device S Sulfites SW sulfite solution W water
Claims
1. An injection unit facing the inner surface of the furnace wall of the furnace, or the surface of a device inside the furnace, A water supply source which is a water supply source connected to the injection unit, A sulfite supply source, which is a sulfite supply source connected to the injection unit, A control device that performs a first injection control to inject an aqueous sulfite solution, in which the sulfite is dissolved in the water, from the injection unit, Equipped with, The control device, after performing the first injection control, performs a second injection control to inject the water in which the sulfite is not dissolved from the injection unit. Ash removal equipment.
2. The aforementioned sulfite is sodium sulfite. The ash removal device according to claim 1.