JP2013053829A - Boiler with corrosion inhibition apparatus and method for inhibiting corrosion of boiler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a boiler with a corrosion inhibition apparatus that can effectively inhibit the corrosion of a superheater tube.SOLUTION: The boiler with the corrosion inhibition apparatus includes: a third gas duct 22 through which combustion exhaust gas passes; the superheater tube 27 arranged in the third gas duct 22; and the corrosion inhibition apparatus 59 for inhibiting the corrosion of the superheater tube 27 by blowing corrosion inhibiting particles having a particle diameter of 0.1 μm or larger and smaller than 10 μm into a second gas duct 21 and attaching the particles to a face surface of the superheater tube 27.

Description

  TECHNICAL FIELD The present invention relates to a boiler with a corrosion suppression device including a corrosion suppression device for preventing corrosion of a boiler, particularly a superheater tube, and a boiler corrosion suppression method.

  As a conventional boiler, there is a boiler that burns fuel in a combustion furnace and superheats steam with a superheater by heat of combustion exhaust gas generated by the combustion to generate high-temperature and high-pressure superheated steam. This superheated steam can be used for power generation.

Here, in recent years, from the viewpoint of CO ₂ reduction and waste heat utilization, it is possible to use, for example, biomass such as construction waste wood and waste such as waste tires and plastic as fuel for boilers. It is being advanced.

In such biomass fuel and waste fuel, the fuel contains salts such as NaCl and KCl, and heavy metals such as lead and zinc. Accordingly, the combustion in the combustion furnace generates a low melting point (about 300 ° C.) molten salt composed of, for example, KCl, NaCl, ZnCl ₂ , K ₂ SO ₄ , Na ₂ SO _{4, and the} like. Flows along with the combustion ash to the superheater on the downstream side. Since this superheater generates high-temperature and high-pressure steam used for the power generation, the gas temperature is set higher than the steam temperature, and KCl, NaCl, ZnCl ₂ that has flowed in. , K ₂ SO ₄ , Na ₂ SO _4, etc. cause a problem that the superheater tube corrodes due to the molten salt adhering to the surface of the superheater tube constituting the high temperature superheater of 300 ° C. or higher. ing.

  Next, an example of a conventional boiler corrosion prevention method for solving the problem that the superheater tube corrodes in this way will be described (for example, see Patent Document 1).

  In this boiler corrosion prevention method, a predetermined amount of predetermined particles (corrosion prevention particles) are supplied into a combustion furnace, and the corrosion prevention particles are converted into molten salt particles (molten salt particles) generated in the combustion furnace. ). By this mixing, the molten salt particles are well dispersed so that the surface of the molten salt particles is surrounded by the corrosion preventing particles, and the molten salt particles can be diluted with the corrosion preventing particles. Since the diluted molten salt particles adhere to the surface of the superheater tube on the downstream side, the concentration and the contact area of the molten salt particles adhering to the surface of the superheater tube are reduced by the corrosion preventing particles. can do. This is to suppress the corrosion of the superheater tube.

  The corrosion preventing particles have a melting point higher than the combustion temperature of the combustion furnace, do not melt in the vicinity of the combustion furnace and the superheater, and have a chlorine concentration, Na concentration, K concentration, and heavy metal concentration of 1000 ppm or less, respectively. Therefore, it contains almost no molten salt component.

  And the average particle diameter of a corrosion prevention particle is prescribed | regulated to 10-20 micrometers. The average particle diameter is defined in this way because when the average particle diameter exceeds 20 μm, the corrosion prevention particles are too large and the molten salt particles are difficult to be surrounded by the corrosion prevention particles, and the corrosion prevention particles are placed in the superheater tube. It becomes difficult to adhere. In addition, if the average particle size of the corrosion prevention particles is smaller than 10 μm, the corrosion prevention particles are too small to get on the combustion exhaust gas flow and go around the superheater tube, and it is difficult for the corrosion prevention particles to adhere to the superheater tube. ing.

JP 2006-308179 A

  However, in the conventional boiler corrosion prevention method, the corrosion prevention particles are adhered to the surface of the molten salt particles generated in the combustion furnace so that the molten salt particles do not directly adhere to the superheater tube. In order to prevent corrosion of the superheater tube, it is necessary to supply a large amount of corrosion prevention particles into the combustion furnace according to the amount of molten salt particles generated in the boiler, and the cost of the corrosion prevention particles is reduced. In addition to increasing the cost, the cost for treating the combustion ash containing the corrosion-inhibiting particles also increases.

  By the way, the inventor of the present application clarifies that among the incinerated ash adhering to the superheater tube, the substance that becomes the main factor corroding the superheater tube is very fine particles having a particle diameter of 0.1 to 10 μm. doing.

  As described above, the reason why extremely fine particles having a particle diameter of 0.1 to 10 μm are the main factor corroding the superheater tube is that the chlorides of Na and K that cause corrosion have a particle diameter of This is because there are many particles having a particle size of 0.1 to 10 μm, and the number of particles exceeding 10 μm is extremely small.

  Then, according to the conventional corrosion prevention method for boilers, even if the conventional corrosion prevention particles having an average particle diameter of 10 to 20 μm can adhere to the surface of the superheater tube, When molten salt particles having a particle diameter of 0.1 to 10 μm smaller than that adhere to the surface, the molten salt particles having a smaller particle diameter diffuse and pass through the gaps between the corrosion preventing particles having a larger particle diameter to cause overheating. It will adhere to the surface of the vessel.

  Therefore, the conventional boiler corrosion prevention method cannot effectively suppress the corrosion of the superheater tube.

  The present invention has been made in order to solve the above-described problems, and provides a boiler with a corrosion suppressing device capable of effectively suppressing corrosion of a superheater tube and a method for suppressing corrosion of a boiler. It is aimed.

  The boiler with a corrosion inhibitor according to the present invention includes an exhaust gas passage through which combustion exhaust gas passes, a superheater pipe provided in the exhaust gas passage, and corrosion inhibitor particles having a particle diameter of 0.1 μm or more and less than 10 μm. It is provided with the corrosion suppression apparatus for suppressing the corrosion of the said superheater pipe | tube by blowing in a passage and making it adhere to the surface of the said superheater pipe | tube.

  Before describing the operation of the present invention, first, the basic principle of the boiler with a corrosion inhibiting device according to the present invention will be described. The inventor of the present application has a particle diameter of 0.1 to 10 μm scattered in the exhaust gas passage, and corrosive particles containing Na or K chloride are formed on the metal interface of the superheater tube or the outer surface thereof. It was found that the corrosion of the superheater tube proceeds by adhering to the surface of the corrosion layer (hereinafter sometimes simply referred to as “the metal interface of the superheater tube”). Therefore, 0.1-10 μm by corroding corrosion-inhibiting particles having a particle size comparable to the corrosive particles of 0.1 μm or more and less than 10 μm into the exhaust gas passage and adhering to the metal interface of the superheater tube. The corrosion weight of the superheater tube adheres to the metal interface of the superheater tube or the like, and the adhesion area and the adhesion area are reduced to suppress the progress of corrosion of the superheater tube.

  According to the boiler with a corrosion inhibiting device according to the present invention, the corrosion inhibiting particles are blown into the exhaust gas passage by blowing the corrosion inhibiting particles having a particle diameter of 0.1 μm or more and less than 10 μm using the corrosion inhibiting device. It can be attached to the metal interface of the superheater tube by thermophoresis or inertial collision. As a result, the corrosive particles having a particle diameter of 0.1 to 10 μm scattered in the exhaust gas passage can reduce the adhesion weight and adhesion area adhering to the metal interface of the superheater tube, and the corrosion of the superheater tube. Can be suppressed.

  In the boiler with a corrosion inhibiting apparatus according to the present invention, the corrosion inhibiting particles may be a compound having at least one element as a main component among Ca, Si, Al, Mg and Fe.

  Thus, the progress of the corrosion of the superheater tube can be suppressed by using a compound whose main component is a relatively easily available element.

  In the boiler with a corrosion inhibiting device according to the present invention, the corrosion inhibiting particles are mixed with a slurry-like mixed material obtained by mixing the corrosion inhibiting particles with a liquid, or powder having a particle diameter larger than the corrosion inhibiting particles. The powdery mixed material obtained in this way is preferably blown into the exhaust gas passage using the corrosion inhibitor.

  In this way, even when the weight of the corrosion-inhibiting particles to be blown into the exhaust gas passage is small, it is possible to accurately blow the desired weight of the corrosion-inhibiting particles into the exhaust gas passage using the corrosion suppressing device. . The liquid in which the corrosion inhibiting particles are mixed can be reduced in cost by using an easily available and inexpensive liquid. In addition, by using a powder having a particle diameter larger than that of the corrosion-inhibiting particles and cheaper, for example, incineration ash, as the powder mixed with the corrosion-inhibiting particles, the cost of the powder can be reduced.

  In the boiler with a corrosion inhibiting device according to the present invention, the melting point of the corrosion inhibiting particles is 800 ° C. or more, and the region where the corrosion inhibiting device blows the corrosion inhibiting particles is at a gas temperature in the exhaust gas passage from 800 ° C. In which the corrosive particles having a particle diameter of 0.1 to 10 μm pass through the exhaust gas passage in which the superheater tube is provided. It is preferable that the weight is substantially equal to or larger than the hit weight.

  In this way, by blowing the corrosion-inhibiting particles having a melting point of 800 ° C. or higher into a region where the gas temperature in the exhaust gas passage is lower than 800 ° C., the corrosion-inhibiting particles are melted and bonded to each other, and the components in the gas It is possible to prevent the particle diameter from becoming large by condensing a part of the corrosion-inhibiting particles as nuclei. It can be adhered to the entire surface of the corrosion layer formed on the outer surface. Thereby, the progress of the corrosion of the entire surface of the superheater tube can be effectively suppressed.

  In the boiler with a corrosion inhibitor according to the present invention, the boiler has a pair of electrodes provided in the exhaust gas passage, and detects the degree of corrosion of the superheater tube based on a change in electrical resistance between the pair of electrodes. Corrosion detection means for generating a corrosion detection signal corresponding to the degree of corrosion, and the corrosion suppression device is controlled based on the corrosion detection signal generated by the corrosion detection means, and the weight of the corrosion-inhibiting particles blown in It is good to provide a control part which controls.

  In this way, the corrosion detecting means can detect the electrical resistance between the pair of electrodes in a situation where the combustion ash adheres to the electrodes, and detect the degree of corrosion of the electrodes based on the change in the electrical resistance. And a corrosion detection signal corresponding to the degree of corrosion of the electrode can be generated. Thus, by placing the electrode in a situation where it corrodes as much as the superheater tube, this corrosion detection signal can be used as a signal representing the degree of corrosion of the superheater tube. And a control part can control a corrosion suppression apparatus based on the corrosion detection signal which a corrosion detection means produces | generates, and can control the blowing weight of corrosion suppression particles. As a result, for example, when the corrosion of the superheater tube is fast, the control unit can increase the blowing weight of the corrosion-inhibiting particles, and when the corrosion of the superheater tube is slow, the control unit suppresses the corrosion. Particle blowing weight can be reduced. In this way, corrosion-inhibiting particles having an appropriate weight can be blown into the exhaust gas passage according to the degree of corrosion of the superheater tube, and corrosion of the superheater tube can be reliably suppressed.

  In the boiler with a corrosion inhibiting apparatus according to the present invention, the corrosion inhibiting particles may be combustion ash generated by a boiler, and the particle diameter may be more than 2 μm and less than 10 μm.

  In this way, by blowing combustion ash having a particle size of more than 2 μm and less than 10 μm into the exhaust gas passage, the progress of corrosion of the superheater tube can be suppressed when the particle size is 0.1 μm or more. This is because combustion ash having a particle size of 2 μm or less has a strong corrosive power, but a combustion ash having a particle diameter of more than 2 μm and less than 10 μm has a weak corrosive power. Therefore, the corrosive force of the combustion ash generated in the boiler can be reduced by blowing the combustion ash having a particle size having a weak corrosive force exceeding 2 μm and less than 10 μm into the exhaust gas passage.

  In the method for inhibiting corrosion of a boiler according to the present invention, corrosion inhibiting particles having a particle size of 0.1 μm or more and less than 10 μm are blown into an exhaust gas passage and adhered to the surface of a superheater tube provided in the exhaust gas passage. The corrosion of the superheater tube is suppressed.

  The method for inhibiting corrosion of a boiler according to the present invention works in the same manner as the boiler with a corrosion inhibiting apparatus according to the present invention.

  In the boiler with a corrosion inhibitor according to the present invention, the corrosion inhibitor particles having a particle diameter of 0.1 μm or more and less than 10 μm are adhered to the surface of the superheater tube, so that the corrosive particles of 0.1 to 10 μm are superheater tube. The adhesion weight and adhesion area adhering to the metal interface or the like are reduced, thereby suppressing the corrosion of the superheater tube. Therefore, the progress of corrosion of the superheater tube can be suppressed more effectively than in the past. Therefore, the maintenance and inspection costs of the superheater tube can be reduced, and the boiler can be used stably for a long period of time.

It is a schematic perspective view which shows the internal structure of the boiler with a corrosion inhibitor which concerns on one Embodiment of this invention. It is a block diagram which shows the control structure of the boiler which concerns on the same embodiment. It is a schematic diagram which shows the corrosion detection apparatus provided in the boiler which concerns on the same embodiment. It is a figure for demonstrating the boiler which concerns on the same embodiment, and is a figure which shows each component ratio in the combustion ash from which particle diameter differs. It is a figure for demonstrating the boiler which concerns on the same embodiment, and is a figure which shows the corrosion amount of the metal piece on the conditions which simulated the superheater pipe | tube by the combustion ash from which particle diameter differs. It is a figure for demonstrating the boiler which concerns on the same embodiment, and is a figure which shows the relationship between the addition ratio of a corrosion inhibitor particle, and the corrosion amount of the metal piece on the conditions which simulated the superheater pipe | tube. It is a figure for demonstrating the boiler which concerns on the embodiment, and is a figure which shows the relationship between the addition rate of combustion ash, and the corrosion amount of the metal piece on the conditions which simulated the superheater pipe | tube.

  First, the basic principle of the boiler with a corrosion inhibitor according to the present invention will be described. The inventor of the present application has a particle diameter of 0.1 to 10 μm scattered in the third flue 22 of the boiler 19 shown in FIG. 1, and corrosion containing Na or K chloride (for example, NaCl, KCl). The inventors investigated that the corrosion of the superheater tube 27 progresses when the conductive particles (particles as the oxidizing agent) adhere to the surface of the superheater tube 27 provided in the third flue 22.

  Therefore, the combustion ash is produced by blowing the corrosion-inhibiting particles having the same particle size (0.1 μm or more and less than 10 μm) as the corrosive particles, for example, into the second flue 21 and adhering to the surface of the superheater tube 27. The corrosion weight of the superheater tube 27 is reduced by reducing the adhesion weight and the adhesion area of the corrosive particles having a particle diameter of 0.1 to 10 μm contained in the surface of the superheater tube 27. did.

Furthermore, the corrosion inhibition mechanism by the corrosion inhibition particles will be described in detail.
(1) Corrosive particles having a particle size of 0.1 to 2 μm Corrosive particles having a particle size of 0.1 to 2 μm adhere to the metal interface of the superheater tube 27 mainly by thermophoresis. Of the particles scattered in the third flue 22, there are many corrosive particles containing Na or K chloride in the particles having a particle size of 0.1 to 2 μm. The corrosive particles have a high corrosive power.

  Therefore, corrosion occurs when these corrosive particles adhere to the metal interface of the superheater tube 27 or the like.

Therefore, according to the boiler 19 with a corrosion inhibiting device according to the present invention, the particle size is reduced to 0. 0 using the corrosion inhibiting device 59 (in FIG. 1, the blowing port 59a of the corrosion inhibiting device 59 appears). By blowing corrosion-inhibiting particles of 1 μm or more and less than 10 μm into the second flue 21, the blown corrosion-inhibiting particles are made against the metal interface of the superheater tube 27 provided in the third flue 22. Can be attached by thermophoresis. As a result, the corrosive particles having a particle diameter of 0.1 to 2 μm in the third flue 22 can reduce the adhesion weight and adhesion area adhering to the metal interface of the superheater tube 27, and the superheater tube. The progress of the corrosion of 27 can be suppressed.
(2) Corrosive particles having a particle diameter of 2 to 10 μm Some corrosive particles having a particle diameter of 2 to 10 μm adhere to the metal interface of the superheater tube 27 by thermophoresis, but inertial collision Therefore, there are many that adhere to the metal interface of the superheater tube 27.

  Of the particles (combustion ash) scattered in the third flue 22, the particles having a particle diameter of 2 to 10 μm are chlorinated with Na or K as compared with the particles having a particle diameter of 0.1 to 2 μm. It can be said that the corrosive force with respect to the superheater tube 27 is smaller than that in the case of (1) because many corrosive particles are contained in the corrosive particles.

Further, in order for the corrosion to proceed, it is necessary for the corrosive particles to continuously adhere to the metal interface or the like of the superheater tube 27, but the particle size is 0.1 μm or more using the corrosion suppression device 59. When corrosion-inhibiting particles of less than 10 μm are blown into the second flue 21 and the blown-in corrosion inhibiting particles adhere to the metal interface of the superheater tube 27 by inertial collision or thermophoresis, the superheater tube 27 It is possible to prevent the corrosive particles adhering to the metal interface or the like due to inertial collision or the like from diffusing and adhering to the metal interface of the superheater tube 27. Thereby, the progress of corrosion of the superheater tube 27 can be suppressed.
(3) Corrosion-inhibiting particles having a particle size of 10 μm or more (corrosion-inhibiting particles excluded from the present invention)
Using the corrosion suppression device 59, the corrosion suppression particles having a particle diameter of 10 μm or more were blown into the second flue 21 to adhere the blown corrosion suppression particles to the metal interface of the superheater tube 27 or the like. In this case, there is a high possibility that corrosive particles having a particle diameter of 0.1 to 10 μm enter from a gap between the corrosion-inhibiting particles having a particle diameter of 10 μm or more and adhere to the metal interface of the superheater tube 27. Therefore, when the corrosion-inhibiting particles having a particle diameter of 10 μm or more are used, the corrosion of the superheater tube 27 can hardly be suppressed.

  Accordingly, in the present invention, the superheater tube is formed by blowing the corrosion-inhibiting particles having the same particle size (0.1 μm or more and less than 10 μm) as the corrosive particles having a particle size of 0.1 to 10 μm into the second flue 21. By adhering to the surface of the superheater tube 27, it is possible to reduce the weight and area of adhesion of the corrosive particles of 0.1 to 10 μm to the surface of the superheater tube 27, thereby suppressing the progress of corrosion of the superheater tube 27. I made it.

  Next, one embodiment of the boiler 19 with a corrosion inhibitor and the method for inhibiting corrosion of a boiler according to the present invention will be described with reference to FIGS. A boiler with a corrosion suppression device (hereinafter sometimes simply referred to as a “boiler”) 19 shown in FIG. 1 burns fuel in a combustion furnace 10, and superheater tubes are heated by the heat of combustion exhaust gas generated by the combustion. 27 can be heated to generate high-temperature and high-pressure superheated steam.

  And this boiler 19 is provided with the corrosion suppression apparatus 59, and this corrosion suppression apparatus 59 blows the corrosion suppression particle in the 2nd flue 21, The overheating provided in this downstream side Corrosion of the vessel tube 27 can be suppressed. The boiler 19 is an exhaust heat boiler that uses, for example, a waste incinerator as the combustion furnace 10, and further generates power using high-temperature and high-pressure superheated steam obtained through the superheater tube 27. Machine 11 is provided.

  As shown in FIG. 1, the waste incinerator (combustion furnace) 10 includes a hopper 12 for supplying waste. The hopper 12 is connected to the main combustion chamber 14 via the chute 13, and the dust supplied from the hopper 12 is sent to the main combustion chamber 14 through the chute 13. The main combustion chamber 14 is provided with a dry stoker 15, a combustion stoker 16, and a post-combustion stoker 17. Primary air is sent from below the stokers 15, 16, and 17, and secondary air is sent from the ceiling 14 a of the main combustion chamber 14.

  The garbage in the main combustion chamber 14 shown in FIG. 1 is first sent to the drying stoker 15 and dried and ignited by the primary air and the radiant heat of the main combustion chamber 14. The ignited garbage is sent to the combustion stoker 16. In addition, combustible gas is generated from the ignited garbage by thermal decomposition. This combustible gas is sent to the gas layer above the main combustion chamber 14 by the primary air, and flame burns with the secondary air in this gas layer. The temperature of the dust is further increased by the heat radiation accompanying the flame combustion. A part of the ignited garbage is combusted by the combustion stoker 16, and the remaining unburned portion is sent to the post-combustion stoker 17. Unburned waste is burned by the post-combustion stoker 17, and the incineration ash remaining after the combustion is discharged from the chute 18 to the outside.

  Further, as shown in FIG. 1, the main combustion chamber 14 is connected to a radiation chamber 20 provided in the boiler 19, and combustion exhaust gas generated by combustion of garbage is transferred from the main combustion chamber 14 to the radiation chamber 20. Will be sent. This combustion exhaust gas is burned again in the radiation chamber 20 and then led to the third flue 22 through the second flue 21 of the boiler 19 and then detoxified by an exhaust gas treatment facility (not shown). Then released into the atmosphere.

  The boiler 19 shown in FIG. 1 is provided with a plurality of water pipes 23 connected to a boiler drum 24 on each of walls defining the radiation chamber 20 and the second flue 21. The water pipe 23 is formed of, for example, carbon steel (for example, STB340), and water sent from the boiler drum 24 flows therein. The water in the water pipe 23 recovers waste heat from the radiation chamber or the second flue 20, 21, and part of it is evaporated to become brackish water and returned to the boiler drum 24. A part of the brackish water returning to the boiler drum 24 is vaporized to become steam. The steam is sent from the boiler drum 24 to a superheater 25 provided in the third flue 22 to be superheated. The superheated steam that has been heated up to high temperature and high pressure is sent to the turbine 26 and drives the generator 11.

  According to the boiler 19 configured as described above, the substances that volatilized during combustion and a part of the incineration ash (collectively referred to as “incineration ash etc.”) are caused by the combustion exhaust gas to the radiation chamber and the second flue 20. , 21, and the third flue 22, and deposit on the water tube 23 and the superheater tube 27 of the superheater 25. Such incineration ash and the like have high corrosiveness, and cause corrosion of the superheater tube 27 of the high-temperature superheater 25.

  Next, the corrosion inhibitor 59 will be described. The corrosion suppression device 59 is a device for suppressing the corrosion of the superheater tube 27 shown in FIG. 1, and is provided on the side wall portion that forms the second flue 21 of the boiler 19. The corrosion suppressing device 59 is a particle supply device that can blow the corrosion suppressing particles into the second flue 21. FIG. 1 shows a blower for blowing the corrosion suppressing particles into the second flue 21. The entrance 59a appears.

The corrosion-inhibiting particles are particles having a particle size of 0.1 μm or more and less than 10 μm, and are compounds containing at least one element of Ca, Si, Al, Mg, and Fe as a main component, for example, CaO, SiO ₂ It is.

  The corrosion inhibiting particles have a melting point of 800 ° C. or higher. The area where the corrosion inhibiting device 59 blows in the corrosion inhibiting particles is such that the corrosion inhibiting particles are not melted and bonded to each other by the combustion exhaust gas in the blown area, or (and) some of the components in the gas are This is a gas temperature region in which the particle size is not increased by concentrating the corrosion-inhibiting particles as nuclei. That is, in this embodiment, the corrosion-inhibiting particles are blown into the second flue 21, and the second flue 21 is a region where the gas temperature of the combustion exhaust gas flowing inside thereof is lower than 800 ° C. .

  Further, in this embodiment, the corrosion-inhibiting particles are added to a slurry-like mixed material obtained by mixing the corrosion-inhibiting particles with a liquid such as water, or a powder (for example, incineration ash) having a particle diameter larger than that of the corrosion-inhibiting particles. The powdery mixed substance obtained by mixing is blown into the second flue 21 using the corrosion suppressing device 59.

  Next, the corrosion detection device 30, the control unit 100, and the corrosion suppression device 59 shown in FIGS. 1 and 2 will be described.

  As shown in FIG. 1, the corrosion detection device 30 is provided on the side wall portion of the third flue 22 of the boiler 19 and on the upstream side of the superheater 25 in the flow direction of the combustion exhaust gas. Located in the third flue 22. The corrosion detection device 30 has a pair of electrodes 45 and 47 (a detection unit, see FIG. 3 described later) provided in the third flue 22, and the electrical resistance between the pair of electrodes 45 and 47 is Based on the change, the degree of corrosion of the superheater tube 27 is detected, and a corrosion detection signal corresponding to the degree of corrosion is generated.

  The control unit 100 controls the corrosion suppression device 59 based on the corrosion detection signal generated by the corrosion detection device 30 to control the blowing weight of the corrosion suppression particles.

Next, the operation of the boiler 19 with a corrosion inhibitor configured as described above will be described. According to the boiler 19 with a corrosion inhibiting device according to this embodiment, the corrosion inhibiting device 59 shown in FIG. 1 is used to corrode corrosion inhibiting particles (for example, CaO, SiO ₂ ) having a particle diameter of 0.1 μm or more and less than 10 μm. 2 By blowing into the flue 21, the blown corrosion-inhibiting particles are heated against the metal interface of the superheater tube 27 and the surface of the corrosion layer formed on the outer surface thereof (such as the metal interface of the superheater tube 27). It can be attached by electrophoresis or inertial collision. As a result, the corrosive particles (for example, KCl, NaCl) having a particle diameter of 0.1 to 10 μm scattered in the third flue 22 reduce the adhesion weight and adhesion area adhering to the metal interface of the superheater tube 27. The progress of corrosion of the superheater tube 27 can be suppressed.

  Therefore, the progress of corrosion of the superheater tube 27 can be suppressed more effectively than in the past. Therefore, maintenance and inspection costs for the superheater tube 27 can be reduced, and the boiler 19 can be used stably for a long period of time.

  Since the corrosion-inhibiting particles are compounds mainly composed of at least one element of Ca, Si, Al, Mg, and Fe, a compound mainly composed of relatively easily available elements is used for overheating. The progress of corrosion of the vessel tube 27 can be suppressed.

  Also obtained by mixing the corrosion-inhibiting particles into a slurry-like mixed material obtained by mixing the corrosion-inhibiting particles with a liquid such as water, or powder (for example, incineration ash) having a particle diameter larger than that of the corrosion-inhibiting particles. Since the powdery mixed substance is blown into the second flue 21 using the corrosion inhibitor 59, the weight of the corrosion inhibiting particles to be blown into the second flue 21 is small. However, the corrosion suppression device 59 can be used to accurately blow the corrosion suppression particles having a desired weight into the second flue 21. If water is used as the liquid in which the corrosion inhibiting particles are mixed, the water is economical because it is easily available and inexpensive. In addition, by using an inexpensive powder having a particle diameter larger than that of the corrosion-inhibiting particles, such as incineration ash, the powder can be reduced in cost.

  Furthermore, corrosion inhibiting particles having a melting point of 800 ° C. or higher are employed. By blowing such corrosion inhibiting particles into the second flue 21 having a gas temperature lower than 800 ° C., the particle size of the corrosion inhibiting particles is increased. The corrosion-inhibiting particles can be adhered to the entire surface of the corrosion layer formed on the metal interface of the superheater tube 27 and its outer surface in a state where the particle diameter is originally small. it can. Thereby, the progress of corrosion on the entire surface of the superheater tube 27 can be effectively suppressed.

  Then, according to the corrosion detection device 30 shown in FIG. 2, in the situation where combustion ash adheres to the electrodes 45, 47 provided in the corrosion detection device 30, the electrical resistance between the pair of electrodes 45, 47 is detected, The degree of corrosion of the electrodes 45 and 47 can be detected based on the change in electrical resistance, and a corrosion detection signal corresponding to the degree of corrosion of the electrodes 45 and 47 can be generated. Therefore, the corrosion detection signal can be used as a signal indicating the degree of corrosion of the superheater tube 27 because the electrodes 45 and 47 are corroded to the same degree as the superheater tube 27. .

  And the control part 100 can control the corrosion suppression apparatus 59 based on the corrosion detection signal which the corrosion detection apparatus 30 produces | generates, and can control the blowing weight of corrosion suppression particles. Accordingly, the controller 100 can increase the blowing weight of the corrosion-inhibiting particles when the corrosion of the superheater tube 27 is fast, and when the corrosion of the superheater tube 27 is slow, for example. Further, it is possible to reduce the blowing weight of the corrosion-inhibiting particles. In this way, the corrosion can be suppressed according to the degree of corrosion of the superheater tube 27 (for example, the amount of corrosion and the corrosion rate), and the corrosion-inhibiting particles having an economical weight can be blown into the second flue 21. And corrosion of the superheater tube 27 can be reliably suppressed.

  Next, the corrosion detection device 30 used in this embodiment will be described in more detail with reference to FIG. The corrosion detection device 30 includes a corrosion sensor 31, an electrochemical measuring device 32, a terminal device 33, a blower 34, a flow rate regulator 35, and a valve 36. The blower 34 and the flow rate regulator 35 constitute a cooling mechanism 37 that cools the electrodes.

  The corrosion sensor 31 includes a long cylindrical protective tube 40 made of stainless steel. The protective tube 40 is formed with a cooling passage 40a for flowing cooling air through its inner wall. One end of the sample electrode 45, the reference electrode 46, and the counter electrode 47, which are detection units, is exposed in the boiler 19 on the peripheral surface on the tip side of the protective tube 40. The corrosion sensor 31 is a side wall portion of the third flue 22 of the boiler 19 and is provided upstream of the superheater 25 in the flow direction of the combustion exhaust gas, and a tip detection portion is located in the third flue 22. doing.

  The lead wires 51, 54, 55 connected to the electrodes 45, 46, 47 are led out of the base end portion of the protective tube 40 located outside the boiler 19 through the protective tube 40, and subjected to electrochemical measurement. It is electrically connected to the device 32. Similarly, the sample electrode thermocouple 53, the protective tube thermocouple 56, and the gas temperature thermocouple 57 are drawn out to the outside of the base end portion of the protective tube 40 through the protective tube 40, and are electrically connected to the flow rate regulator 35. It is connected to the. Further, a blower 34 for sending cooling air to the cooling passage 40 a in the protective tube 40 is connected to the proximal end portion of the protective tube 40.

  The blower 34 is provided with a flow rate regulator 35 for controlling the flow rate from the blower 34. A valve 36 for adjusting the amount of air is provided between the blower 34 and the cooling passage 40a. As described above, the flow rate regulator 35 is connected to the thermocouple 53, and the valve 36 is opened so that the temperature of the sample electrode 45 becomes equal to a predetermined temperature in accordance with the output from the thermocouple 53. And the flow rate of the cooling air from the blower 34 is controlled. In the present embodiment, the temperature of the sample electrode 45 is controlled to be equal to the temperature of the superheater tube 27. As a result, the environment in which the sample electrode 45 is placed and the environment in which the superheater tube 27 is placed can be brought into the same state, so that the corrosion state of the superheater tube 27 can be estimated more accurately.

  The electrochemical measuring device 32 is a device that measures the corrosion rate of the sample electrode 45 by a known electrochemical impedance method.

  The corrosion rate of the superheater tube 27 estimated using the corrosion sensor 31 as described above and the corrosion amount (corrosion detection signal) obtained by calculating this corrosion rate are obtained from the terminal device 33 of the corrosion detection device 30. It is transmitted to the control unit 100.

  Next, FIGS. 4 to 7 will be described. FIG. 4 shows the ratio of each component in the combustion ash having different particle diameters. In FIG. 4, the total of Ca (calcium), Cl (chlorine), and Na + K (sodium, potassium) is represented as 1. The particles having a small particle diameter are particles having a particle diameter Dp ≦ 2 μm. The particles having a medium particle size are particles having a particle size of 2 μm <particle size Dp <10 μm. The particles having a large particle size are particles having a particle size Dp> 10 μm.

  As can be seen from FIG. 4, the combustion ash (particles) having a small particle diameter is composed of Cl and Na + K having a strong corrosive power, and a slight amount of inactive Ca having no corrosive power. Yes. Therefore, it can be said that the combustion ash with a small particle diameter has extremely strong corrosive power.

  About 62% of the combustion ash having a medium particle size is composed of Cl and Na + K having strong corrosive power, and the remaining 38% is composed of Ca having no corrosive power. Therefore, it can be said that the combustion ash having a medium particle diameter has a lower corrosive power than the combustion ash having a small particle diameter.

  Combustion ash having a large particle size is composed of approximately 38% Cl and Na + K having strong corrosive power, and the remaining approximately 62% is composed of Ca having no corrosive power. Therefore, it can be said that the combustion ash having a large particle diameter has a corrosive force smaller than that of the combustion ash having a small particle diameter and medium.

  FIG. 5 shows the amount of corrosion of a metal piece (hereinafter referred to as “simulated superheater tube”) under the conditions of simulating the superheater tube 27 with combustion ash having different particle diameters. As can be seen from FIG. 5, it can be said that the combustion ash having a small particle diameter has extremely strong corrosive power as compared with the combustion ash having a medium particle diameter. And it can be said that the combustion ash with a medium particle diameter has weak corrosive power. Although not shown in the figure, the combustion ash having a large particle size has extremely weak corrosive power.

  FIG. 6 is a diagram showing the relationship between the addition ratio of the corrosion-inhibiting particles and the corrosion amount of the simulated superheater tube. In other words, when adding corrosion inhibiting particles with a small particle size to combustion ash with a small corrosive particle size, increasing the addition ratio of the corrosion inhibiting particles increases the simulated superheater tube. It can be seen that the amount of corrosion decreases. As can be seen from this figure, when the addition ratio of the corrosion-inhibiting particles is about 50%, the amount of corrosion can be reduced to about 2/5 compared with the case where the corrosion-inhibiting particles are not added. An effect can be obtained.

  FIG. 7 is a diagram showing the relationship between the addition ratio of combustion ash and the amount of corrosion of the simulated superheater tube. In FIG. 6, the corrosion-inhibiting particles having a small particle size are added to the combustion ash having a small corrosive particle size. In FIG. 7, the combustion ash having a medium particle size is added to the combustion ash having a strong corrosive particle size. An example of addition to small combustion ash is shown. As can be seen from FIG. 5, the combustion ash having a medium particle size is extremely weak in corrosiveness. Therefore, it can be seen that when the addition ratio is about 50%, a large corrosion inhibition effect can be obtained.

  However, in the above embodiment, as shown in FIG. 1, for example, the waste incinerator 10 is given as an example of the combustion furnace 10 of the boiler 19, but other combustion furnaces can be applied, for example, heavy oil as fuel A combustion furnace can be applied.

  And in the said embodiment, as shown in FIG. 1, although the stoker type combustion furnace was mentioned as an example as the combustion furnace 10 of the boiler 19, the combustion furnace of a format other than this can be applied, for example, A fluidized bed furnace in which fuel is burned while flowing in a fluidized bed can be applied.

  Moreover, in the said embodiment, although the degree of corrosion of the superheater pipe | tube 27 was detected using the corrosion detection apparatus 30 shown in FIG. 3, you may use the corrosion detection apparatus other than this.

  Furthermore, in the above embodiment, the corrosion-inhibiting particles having a particle size of 0.1 μm or more and less than 10 μm are blown into the second flue 21 upstream from the superheater tube 27, but instead, the superheater tube 27. You may make it blow in in the 3rd flue 22 provided.

  In the above embodiment, the corrosion-inhibiting particles having a particle size of 0.1 μm or more and less than 10 μm are blown into the second flue 21 upstream from the superheater tube 27, but instead, generated by the boiler 19. The combustion ash having a particle diameter exceeding 2 μm and less than 10 μm (combustion ash having a particle diameter of medium) is blown into the second flue 21 upstream of the superheater pipe 27. May be.

  Even in this way, the progress of the corrosion of the superheater tube 27 can be suppressed because, as shown in FIG. 5, combustion ash having a particle size of 0.1 μm or more and 2 μm or less (particle size is small). This is because the burning ash (combustion ash) has a strong corrosive power, but the combustion ash having a particle diameter of more than 2 μm and less than 10 μm (combustion ash having a medium particle diameter) has a weak corrosive power. Therefore, the corrosive force of the combustion ash generated in the boiler can be reduced by blowing the combustion ash having a particle size having a weak corrosive force into the second flue 21 (see FIG. 7).

  Moreover, in the said embodiment, although the control part 100 controlled the corrosion suppression apparatus 59 based on the corrosion detection signal which the corrosion detection apparatus 30 produced | generated, it controlled the blowing weight of the corrosion suppression particle | grains. Instead of this, the blowing weight of the corrosion-inhibiting particles may be controlled as follows.

  For example, the corrosion suppression device 59 blows the corrosion-inhibiting particles into the second flue 21, and the corrosive particles having a particle diameter of 0.1 to 10 μm contained in the combustion ash are superheaters. The weight may be substantially equal to or greater than the weight per unit time passing through the third flue 22 provided with the tube 27.

  As a method for determining the weight per unit time through which the corrosive particles having a particle diameter of 0.1 to 10 μm contained in the combustion ash pass through the third flue 22 provided with the superheater tube 27, for example, First, the combustion ash per unit time that actually passes through the third flue 22 is collected and obtained by measuring the weight of corrosive particles having a particle diameter of 0.1 to 10 μm contained in the combustion ash. be able to. Further, based on the weight data of the corrosive particles having a particle diameter of 0.1 to 10 μm, the particle diameter is 0.1 to 0.1 depending on the quality of the fuel supplied to the boiler, the supply amount, the combustion condition, the environment, and the like. It is possible to estimate the weight per unit time of 10 μm corrosive particles passing through the third flue 22 where the superheater tube 27 is provided.

  As described above, the boiler with a corrosion inhibitor and the method for inhibiting corrosion of a boiler according to the present invention have an excellent effect of effectively suppressing corrosion of a superheater tube, and are superheated like a waste incineration boiler. Suitable for boilers where corrosion of pipes is a concern.

10 Combustion furnace (garbage incinerator)
DESCRIPTION OF SYMBOLS 11 Generator 12 Hopper 13 Chute 14 Main combustion chamber 14a Ceiling 15 Dry stalker 16 Combustion stalker 17 Post combustion stalker 18 Chute 19 Boiler 20 Radiation chamber 21 Second flue 22 Third flue 23 Water pipe 24 Boiler drum 25 Superheater 26 Turbine 27 Superheater tube 30 Corrosion detection device 31 Corrosion sensor 32 Electrochemical measuring device 33 Terminal device 34 Blower 35 Flow controller 36 Valve 37 Cooling mechanism 40 Protection tube 40a Cooling passage 45 Sample electrode 46 Reference electrode 47 Counter electrode 51 Lead wire for sample electrode 53 Thermocouple for Sample Electrode 54 Reference Electrode Lead Wire 55 Counter Electrode Lead Wire 56 Protective Tube Thermocouple 57 Gas Temperature Thermocouple 59 Corrosion Inhibitor 59a Blow Inlet 100 Control Unit

Claims (7)

Exhaust gas passage through which combustion exhaust gas passes,
A superheater tube provided in the exhaust gas passage;
A corrosion inhibiting device for inhibiting corrosion of the superheater tube by blowing corrosion inhibiting particles having a particle diameter of 0.1 μm or more and less than 10 μm into the exhaust gas passage and adhering to the surface of the superheater tube; A boiler with a corrosion inhibitor characterized by comprising.   The boiler with a corrosion inhibiting device according to claim 1, wherein the corrosion inhibiting particles are a compound mainly containing at least one element of Ca, Si, Al, Mg and Fe.   A slurry-like mixed substance obtained by mixing the corrosion-inhibiting particles with a liquid, or a powder-like mixed substance obtained by mixing the corrosion-inhibiting particles with a powder having a particle diameter larger than that of the corrosion-inhibiting particles. The boiler with a corrosion suppressing device according to claim 1 or 2, wherein the corrosion suppressing device is used to blow into the exhaust gas passage. The melting point of the corrosion-inhibiting particles is 800 ° C. or higher,
The region where the corrosion inhibiting device blows the corrosion inhibiting particles is a region where the gas temperature in the exhaust gas passage is lower than 800 ° C.
The blowing weight per unit time of the corrosion-inhibiting particles is substantially equal to the weight per unit time through which the corrosive particles having a particle diameter of 0.1 to 10 μm pass through the exhaust gas passage where the superheater pipe is provided. The boiler with a corrosion inhibiting device according to any one of claims 1 to 3, wherein the boiler has a weight greater than or equal to the weight. A corrosion detection signal having a pair of electrodes provided in the exhaust gas passage, detecting the degree of corrosion of the superheater tube based on a change in electrical resistance between the pair of electrodes, and corresponding to the degree of corrosion Corrosion detection means for generating
The control part which controls the said corrosion suppression apparatus based on the said corrosion detection signal which the said corrosion detection means produces | generates, and controls the blowing weight of the said corrosion suppression particle | grain is provided. A boiler with a corrosion inhibitor according to any one of the above.   The boiler with a corrosion inhibiting device according to any one of claims 1 to 5, wherein the corrosion inhibiting particles are combustion ash produced by a boiler, and the particle diameter thereof is more than 2 µm and less than 10 µm.   Inhibiting corrosion of the superheater tube by blowing corrosion-inhibiting particles having a particle size of 0.1 μm or more and less than 10 μm into the exhaust gas passage and adhering it to the surface of the superheater tube provided in the exhaust gas passage. A method for inhibiting corrosion of a boiler.

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