Laser ignition method for fluidized bed boilers

Abstract

This invention discloses a laser ignition method for a fluidized bed boiler, comprising: calculating the amount of ignition bed material, wherein the bed material includes bed material and fuel, wherein the fuel includes mineral fuel or non-mineral fuel, and the non-mineral fuel mainly includes at least one of biomass fuel and combustible municipal solid waste; guiding an indicator light for indicating the laser beam to a target area on the bed surface of the furnace, and defining the target area as the laser scanning area; laying multiple ignition layers in the furnace, wherein the multiple ignition layers include the bed material and the fuel; and after each ignition layer is laid, scanning the ignition layer in the laser scanning area with the laser beam. The above laser ignition method, without involving any modification to the boiler body, neither consumes additional fuel nor fails to meet the process requirements for heating large-volume bed material, achieving safe, reliable, and efficient laser ignition, combustion assistance, and stable combustion.

Description

Technical Field

[0001] This disclosure relates to the field of high-power thermal combustion, and in particular to a laser ignition method for fluidized bed boilers. Background Technology

[0002] Thermal power generation is a typical application of high-power thermal combustion. At present, thermal power generation is still the most important way to provide electricity. Because coal-fired power generation has good economic benefits, "coal power" accounts for a large proportion of "thermal power". Especially in developing countries, it is also one of the main sources of air pollution. At present, there are a considerable number of fluidized bed coal-fired boilers, as well as a certain number of biomass and combustible waste boilers.

[0003] With the urgent need to reduce greenhouse gas emissions globally increasing dramatically, high-power thermal combustion technology will inevitably develop in line with the direction of "green combustion" that is more efficient, energy-saving, and has lower emissions. It is necessary to further improve the level of combustion technology. On the basis of refined combustion and intelligent control, it is also necessary to innovate energy beam ignition methods. Summary of the Invention

[0004] According to the embodiments of this disclosure, a laser ignition method for fluidized bed boilers is provided. This method does not involve any modification to the boiler body, does not consume additional fuel, and meets the process requirements for heating large-volume bed materials, thereby achieving safe, reliable, and efficient laser ignition, combustion assistance, and stable combustion.

[0005] The laser ignition method for a fluidized bed boiler provided according to an embodiment of this disclosure includes: calculating the amount of ignition bed material, wherein the bed material includes bed material and fuel, wherein the fuel includes mineral fuel or non-mineral fuel, and the non-mineral fuel mainly includes at least one of biomass fuel and combustible municipal solid waste; guiding an indicator light for indicating a laser beam to a target area on the bed surface within the furnace, and defining the target area as a laser scanning area; laying multiple ignition layers within the furnace, wherein the multiple ignition layers include the bed material and the fuel; and after each ignition layer is laid, scanning the ignition layer in the laser scanning area with the laser beam.

[0006] In at least some embodiments, the bed material and the fuel are mixed in a layered or blended manner in the plurality of ignition layers.

[0007] In at least some embodiments, the bed material and the fuel are mixed in the layered mixing manner, and the plurality of ignition layers include a plurality of bed material layers and a plurality of fuel layers.

[0008] The step of laying multiple ignition layers in the furnace includes: conveying the bed material to form the bed material layer; conveying the fuel to form the fuel layer on the bed material layer; and alternately conveying the bed material and the fuel multiple times to form the multiple fuel layers and the multiple bed material layers arranged alternately in the longitudinal direction of the furnace.

[0009] In at least some embodiments, the bed material and the fuel are mixed in the layered mixing manner, and the plurality of ignition layers include a bed material layer and a plurality of fuel layers. The laying of the plurality of ignition layers in the furnace includes: laying the bed material in one go to form a bed material layer; and conveying fuel multiple times to form the plurality of fuel layers on the bed material layer.

[0010] In at least some embodiments, the bed material and the fuel are mixed in the blending manner, and the plurality of ignition layers include a plurality of mixed fuel layers; wherein, laying the plurality of ignition layers in the furnace includes: mixing the bed material and the fuel in a proportion to form a mixed fuel; and repeatedly conveying the mixed fuel to form the plurality of mixed fuel layers.

[0011] In at least some embodiments, the step of scanning the ignition layer in the laser scanning area with the laser beam after each ignition layer is laid includes: scanning the fuel layer or the mixed fuel layer in the laser scanning area with the laser beam after each fuel layer or the mixed fuel layer is formed.

[0012] In at least some embodiments, calculating the amount of ignition substrate includes: calculating the amount of fuel in the substrate, wherein: the total calorific value Q required for ignition is calculated based on the total calorific value Q' required to heat a predetermined amount of coal slag to a predetermined temperature in conventional diesel ignition, which includes: obtaining the amount of diesel P used in conventional diesel ignition and the average calorific value Q0 of diesel based on experience, and calculating the total calorific value Q required for ignition with the fuel: Q = Q' = Q0 × P; and calculating the amount of fuel Dr based on the total calorific value Q and the average calorific value Q1 of the fuel in the substrate: Dr = Q ÷ Q1.

[0013] In at least some embodiments, calculating the amount of ignition substrate further includes: calculating the amount of bed material in the substrate, wherein: when the fuel is mineral fuel, the amount of mineral fuel residue Dz generated during combustion of the mineral fuel Dr is calculated: Dz = Dr × a, where a is the generation coefficient of mineral fuel residue, and the amount of bed material Dc is calculated based on the amount of mineral fuel residue Dz: Dc = T - Dz; when the fuel is non-mineral fuel, the amount of bed material Dc ≈ T is calculated, where T is the amount of coal ash used for conventional diesel ignition.

[0014] In at least some embodiments, the laser ignition method further includes: using the calculated amount of bed material Dc as the total amount of bed material in the plurality of ignition layers; and using the calculated amount of fuel Dr as the total amount of fuel in the plurality of ignition layers.

[0015] In at least some embodiments, the laser ignition method further includes: supplying air into the furnace to microfluidize the bed material and the fuel; increasing the air pressure and air volume of the supplied air to enhance the fluidization degree of the bed material and the fuel; continuing to scan the laser scanning area with the laser beam to apply the laser beam to the plurality of ignition layers to continue heating the bed material and the fuel; and withdrawing the laser beam from the furnace. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the accompanying drawings of the embodiments will be briefly described below. Obviously, the drawings described below only relate to some embodiments of this disclosure and are not intended to limit this disclosure.

[0017] Figure 1 A flowchart of a laser ignition method for a fluidized bed boiler provided in this embodiment of the disclosure;

[0018] Figure 2 A cross-sectional schematic diagram of a fluidized bed boiler provided in an embodiment of this disclosure;

[0019] Figure 2A This is a schematic diagram of the process for laying multiple ignition layers provided in an embodiment of the present disclosure;

[0020] Figure 2B A cross-sectional schematic diagram of a fluidized bed boiler provided in another embodiment of this disclosure;

[0021] Figure 3 This is a schematic diagram of the laser scanning area in a fluidized bed boiler provided in an embodiment of the present disclosure;

[0022] Figure 4 A cross-sectional schematic diagram of a fluidized bed boiler provided in another embodiment of this disclosure;

[0023] Figure 4A A schematic diagram of the process for laying multiple ignition layers provided in another embodiment of this disclosure;

[0024] Figure 5 A cross-sectional schematic diagram of a fluidized bed boiler provided in yet another embodiment of this disclosure;

[0025] Figure 5A A schematic diagram of the process for laying multiple ignition layers provided in yet another embodiment of this disclosure;

[0026] Figure 6This is a schematic diagram of the process for adjusting the laser beam according to an embodiment of the present disclosure. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. All other embodiments obtained by those skilled in the art based on the described embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0028] Unless otherwise defined, the technical or scientific terms used herein shall have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms “first,” “second,” and similar terms used in this patent application specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as “comprising” or “including” indicate that the element or object preceding “comprising” or “including” encompasses the element or object listed following “comprising” or “including” and its equivalents, and do not exclude other elements or objects. Terms such as “connected” or “linked” are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. Terms such as “upper,” “lower,” “left,” and “right” are used only to indicate relative positional relationships, and these relative positional relationships may change accordingly when the absolute position of the described object changes.

[0029] Lasers represent the highest power (energy) density energy beam achievable through engineering to date. Currently, high-energy laser beams with infrared wavelengths used in industrial processing can reach 10... 7 w / cm 2 The above power density or 10 7 j / cm 2 With energy densities exceeding these levels, it can generate temperatures in the thousands of degrees Celsius, and both theoretical and engineering practices have proven its ability to ignite all combustible materials. As an ignition energy beam, it is safer, more economical, environmentally friendly, and convenient for ignition, combustion assistance, and stabilization in high-power thermal combustion, and has a wide range of applications and promising development prospects.

[0030] As is well known, the most significant characteristic of fluidized bed boilers is the use of high-heat-capacity materials as the heat storage and transfer medium in the bed. First, a certain volume or weight of bed material is heated to the ignition temperature of the solid fuel used, ensuring that the total stored heat energy is sufficient to reliably ignite the scattered cold fuel. Stable combustion is then achieved in the fluidized bed environment, offering numerous advantages such as high burnout rates. However, significant drawbacks also exist. For example, regardless of whether it's a bubbling or circulating fluidized bed, whether it's bed-side, bed-side, or combined bed-side ignition, and whether it uses coal, biomass, or combustible waste, additional fuels (such as diesel) are required for ignition. This not only increases ignition costs but also causes severe air pollution from the initial fuel exhaust. To overcome these drawbacks, it is essential to research new methods of laser high-energy beam ignition.

[0031] Furthermore, fluidized bed boilers have a unique shape and structure. The fluidization of the bed material ensures that the furnace is under positive pressure throughout the entire process of ignition, combustion, and stable combustion. Without modifying the boiler itself, and without consuming additional fuel, the process requirements for heating large-volume bed materials must be met, achieving safe, reliable, and efficient laser ignition, combustion, and stable combustion.

[0032] Furthermore, the introduction of an ignition laser beam must not only adapt to the characteristics of a fluidized bed boiler, but also to the characteristics of laser transmission. This is to avoid significant attenuation of laser energy before ignition, while also completely preventing harmful damage caused by direct irradiation of the furnace body, heat exchanger surfaces, and other components by the high-energy laser beam, and to determine the safe zone for laser ignition.

[0033] Furthermore, the energy conversion efficiency of the ignition laser beam acting directly or indirectly on the target object differs. Direct irradiation of the target object results in the highest energy conversion efficiency due to the combined effect of light and heat energy. However, it is essential to precisely control the laser energy density and the duration of action. By precisely controlling parameters such as laser power, spot diameter, and scanning rate, coking and slag formation during the ignition process can be completely eliminated, thereby preventing these coking and slag formations from affecting or damaging the "fluidization properties".

[0034] In conclusion, exploring new methods, technologies, devices, and processes for laser ignition, combustion assistance, and stable combustion in fluidized bed boilers is a major engineering project with social significance, economic benefits, and real market demand. At the same time, it is also a highly technical and complex system engineering project.

[0035] This disclosure provides a laser ignition method for a fluidized bed boiler, comprising: calculating the amount of ignition bed material, wherein the bed material includes bed material and fuel, wherein the fuel includes mineral fuel or non-mineral fuel, and the non-mineral fuel mainly includes at least one of biomass fuel and combustible municipal solid waste; guiding an indicator light for indicating a laser beam to a target area on the bed surface of the boiler, and defining the target area as a laser scanning area; laying multiple ignition layers inside the boiler, wherein the multiple ignition layers include the bed material and the fuel; and after each ignition layer is laid, scanning the ignition layer in the laser scanning area with the laser beam.

[0036] The laser ignition method for fluidized bed boilers provided in the above-described embodiments focuses on the key step of fluidized bed boiler ignition. With the innovative idea of ​​consuming only the original solid fuel without consuming other fuels (such as diesel), it actively explores the technical approach of high-energy laser beam ignition and specifically proposes a laser ignition method for fluidized bed boilers. The above-described laser ignition method is applicable to the ignition, combustion assistance and stable combustion of various solid fuel fluidized bed boilers, and can significantly reduce ignition costs and improve the environmental friendliness and economy of ignition.

[0037] Compared to existing diesel ignition methods, the laser ignition method described above uses laser irradiation to achieve ignition, combustion assistance, and stable combustion. It can achieve this without modifying the boiler body and without consuming additional diesel fuel, thus reducing ignition costs and eliminating exhaust fumes caused by fuel combustion. This meets the process requirements for heating large-volume bed materials and achieves safe, reliable, and efficient laser ignition, combustion assistance, and stable combustion.

[0038] In addition, in the above-mentioned laser ignition method, before the formal laser ignition, the laser scanning area (i.e. the laser ignition safety area) is determined by the indicator light, which can completely prevent the harmful damage caused by the high-energy laser beam directly irradiating the furnace body, the surface of the heat receiver and other components.

[0039] The laser ignition method for fluidized bed boilers provided in the above-described embodiments is inspired by the traditional wood-burning stove used for "roasting sweet potatoes in red ash". The overall design concept is safety, reliability, economy, environmental protection and simplicity. It innovates the ignition mechanism, and the ignition energy is taken from the original solid fuel without consuming other fuels (for example, there is no need to use diesel), which greatly reduces the ignition cost.

[0040] In the above-described embodiments of the present disclosure, before the circulating fluidized bed boiler is started, a certain thickness of ignition material is laid on the air distribution plate. The ignition material is referred to as the bottom material, which includes bed material and fuel.

[0041] In some embodiments, the bed material in the substrate serves for insulation and heat transfer. For example, the bed material includes fuel residue from fossil fuels, such as coal ash. Of course, the bed material may also include other materials such as sand, ash, limestone, etc., and this disclosure does not limit this aspect.

[0042] In some embodiments, the fuel in the substrate is used for laser ignition. For example, the fuel is solid fuel, meaning the substrate includes a bed material and solid fuel.

[0043] In existing diesel ignition processes, a bed material is usually laid inside the boiler without fuel. The bed material is heated by diesel fuel to achieve ignition.

[0044] In the laser ignition method of this disclosure, a "base material" (bed material + fuel) is used, that is, fuel that is conducive to laser ignition is added to the bed material, and laser ignition is achieved by irradiating the fuel with a laser, thereby eliminating the need for diesel ignition, greatly reducing ignition costs, and also having economic and environmental benefits.

[0045] In addition, in this embodiment, the amount of bed material and fuel in the base material can be dynamically adjusted according to the volume and mass of the heat storage and heat transfer medium bed material during the ignition process, thereby organically integrating heat storage, heat transfer and combustion, thereby further improving and enhancing the laser ignition effect.

[0046] In some embodiments, the fuel includes fossil fuels or non-fossil fuels. For example, fossil fuels mainly include coal, and non-fossil fuels mainly include at least one of biomass fuels and combustible municipal solid waste. However, fossil fuels and non-fossil fuels are not limited to the materials mentioned above, and other suitable materials are also included within the scope of embodiments of this disclosure.

[0047] In this embodiment of the disclosure, "substance A mainly includes material B" means that material B has a high mass percentage in substance A. For example, the mass percentage of material B accounts for more than 60% of the mass percentage of substance A, further, the mass percentage of material B accounts for more than 80% of the mass percentage of substance A, and even further, the mass percentage of material C accounts for more than 90% of the mass percentage of substance A.

[0048] In some embodiments, biomass fuel refers to the combustion of biomass materials as fuel, generally mainly agricultural and forestry waste (such as straw, sawdust, bagasse, rice husks, etc.). The application of biomass fuel mainly refers to biomass molding fuel (BMF), which is a new type of clean fuel that can be directly burned by using agricultural and forestry waste as raw materials and processing them through crushing, mixing, extrusion, drying and other processes.

[0049] In some embodiments, combustible household waste refers to household waste that can be burned, including plant waste, paper waste (newspapers, book paper, packaging paper, office paper, advertising paper, cardboard boxes), plastic waste (various plastic bags, plastic foam, plastic packaging, disposable plastic lunch boxes and tableware, hard plastics, etc.), and textile waste (old textiles and textile products, discarded clothes, tablecloths, washcloths, school bags, etc.).

[0050] The present disclosure will now be described through specific embodiments. To keep the following description of the embodiments of the present disclosure clear and concise, detailed descriptions of known functions and components may be omitted. When any component of an embodiment of the present disclosure appears in more than one drawing, the component may be represented by the same reference numerals in each drawing.

[0051] Figure 1 A flowchart of a laser ignition method for a fluidized bed boiler provided in an embodiment of this disclosure. Figure 2 This is a cross-sectional schematic diagram of a fluidized bed boiler provided in an embodiment of this disclosure. Figure 3 This is a schematic diagram of the laser scanning area in a fluidized bed boiler provided in an embodiment of this disclosure.

[0052] Combination Figure 1 , Figure 2 and Figure 3 The laser ignition method for fluidized bed boilers provided in this disclosure includes:

[0053] S1: Calculate the amount of ignition bed material. The bed material includes bed material and fuel. The fuel includes mineral fuel or non-mineral fuel. Non-mineral fuel mainly includes at least one of biomass fuel and combustible municipal solid waste.

[0054] S2: Guide the indicator light used to indicate the laser beam L to the target area on the bed surface of the furnace 1, and define the target area as the laser scanning area T;

[0055] S3: Multiple ignition layers 10 are laid in the furnace 1, the multiple ignition layers 10 including the bed material and the fuel;

[0056] S4: After each ignition layer 10 is laid, the ignition layer 10 in the laser scanning area T is scanned with a laser beam L.

[0057] In the laser ignition method of the above embodiments, the fuel in the ignition layer 10 can be either a mineral fuel such as coal, or a non-mineral fuel such as biomass fuel or combustible waste. Since the ignition layer 10 is more easily ignited by the laser beam L, adding fuel to the base material makes it more advantageous to achieve laser ignition.

[0058] In existing diesel ignition methods, coal ash is used as the bed material, and no fuel is present. This not only requires a considerable amount of diesel fuel but also increases ignition costs. Furthermore, diesel combustion emits pollutants, easily polluting the environment. Diesel is a non-renewable fossil fuel. Replacing diesel with coal means the fuel cannot be reused after combustion.

[0059] The laser ignition method described in the above embodiments, by using bed material and fuel as the base material, offers several advantages over diesel ignition. Firstly, by incorporating fuel (or solid fuel, such as coal, biomass fuel, or combustible municipal solid waste) that facilitates laser beam ignition into the base material, the amount of bed material required can be reduced. Secondly, using a laser beam for ignition eliminates the need for diesel fuel, lowering ignition costs, and the laser beam itself does not pollute the environment. Furthermore, the laser beam can be used for repeated ignition, further reducing the combustion costs of fluidized bed boilers.

[0060] In the laser ignition method provided in this embodiment, the order of each step can be adjusted according to the actual situation. For example, step S2 can be performed after laying the first ignition layer 10 in step S3, which can also achieve the purpose of this invention.

[0061] In at least some embodiments, the bed material and fuel are mixed in a layered or blended manner in multiple ignition layers. The mixing method between the bed material and fuel varies depending on the type of fuel used.

[0062] In some embodiments, when the difference in specific gravity between the fuel and the bed material is small, they can be mixed using either a layering method or a blending method. When the difference in specific gravity between the fuel and the bed material is large, blending is not suitable, and layering is more recommended, and even more preferably... Figure 4 The layering method shown is used for mixing. Specific gravity, also known as relative density, is the density of a solid compared to the density of water at standard atmospheric pressure and 3.98°C (999.972 kg / m³). 3 The ratio of ).

[0063] For example, when the fuel is fossil fuel, the difference in specific gravity between the bed material and the fossil fuel is small, and they can be mixed in layers or blended.

[0064] For example, when the fuel is non-mineral fuel, the specific gravity difference between the bed material and the non-mineral fuel is significant, making layered mixing a more recommended approach, especially... Figure 4 The layer mixing method shown is used for mixing.

[0065] In at least some embodiments, the bed material and fuel are mixed in a layered manner. Figure 2A This is a schematic diagram illustrating the process of laying multiple ignition layers according to an embodiment of this disclosure. For example, as... Figure 2 and Figure 2AAs shown, the multiple ignition layers 10 include multiple bed material layers 11 and multiple fuel layers 12 (two bed material layers 11 and two fuel layers 12 are used as an example in the figure); at this time, the step S3 of laying multiple ignition layers 10 in the boiler includes:

[0066] S301: Convey bed material to form bed material layer 11;

[0067] S302: Transport fuel to form a fuel layer 12 on the bed layer 11;

[0068] S303: Multiple bed materials and multiple fuels are alternately conveyed to form multiple alternating fuel layers 12 and multiple bed material layers 11 in the longitudinal direction (Z direction shown in the figure) of the furnace 1. That is, the multiple fuel layers 12 and multiple bed material layers 11 are alternately and stacked in the Z direction. For example, after each fuel conveying forms a bed material layer 11, fuel is conveyed to form a fuel layer 12. After multiple repeated conveyings, multiple alternating fuel layers 12 and multiple bed material layers 11 are formed.

[0069] In this embodiment, the bed material layer 11 serves as insulation and heat transfer, while the fuel layer 12 is easily ignited by a laser, thus serving as an ignition source. However, with only one bed material layer 11 and one fuel layer 12, the bed material layer 11 is relatively thin, failing to provide adequate insulation and also making it difficult to ensure high temperatures for the fuel layer 12 and the bed surface. Furthermore, the thin fuel layer 12 makes reliable ignition difficult.

[0070] In this embodiment of the present disclosure, by setting up multiple alternating fuel layers 12 and multiple bed material layers 11, that is, laying a fuel layer 12 after laying each bed material layer 11, not only is heat transfer between the multiple bed material layers 11 and the multiple fuel layers 12 utilized to ensure a high bed surface temperature, but also the multiple fuel layers 12 are scanned layer by layer by laser beam L, thereby further improving the reliability and stability of laser ignition.

[0071] In at least some embodiments, the plurality of bed layers 11 include a first bed layer 11a (i.e., the bed layer directly laid on the wind cap 3 in the figure and with a thickness exceeding that of the wind cap 3, also called the base bed layer) and at least one second bed layer 11b located above the first bed layer 11a; the plurality of fuel layers 12 include a first fuel layer 12a and at least one second fuel layer 12b located above the first fuel layer 12a; wherein, the first fuel layer 12a is located between the first bed layer 11a and the second bed layer 11b, and the second bed layer 11b is located between the first fuel layer 12a and the second fuel layer 12b; at this time, the formation of the alternately arranged plurality of fuel layers 12 and plurality of bed layers 11 in step 303 above further includes:

[0072] S3031: First, a first bed material layer 11a is formed, which covers the wind cap 3;

[0073] S3032: Then form a first fuel layer 12a on the first bed material layer 11a;

[0074] S3033: A second bed material layer 11b is formed on the first fuel layer 12a;

[0075] S3034: A second fuel layer 12b is formed on the second bed material layer 11b.

[0076] In this embodiment, by first forming a first bed material layer 11a and covering the wind cap 3, it is beneficial to fluidize the bed material in the first bed material layer 11a when the wind cap 3 supplies air, thereby further fluidizing the first fuel layer 12a, the second bed material layer 11b, and the second fuel layer 12b. In some embodiments, the height of the first bed material layer 11a is higher than the top of the wind cap 3.

[0077] In this embodiment of the disclosure, "fluidization" refers to the air blown from the vent cap 3 passing through the gaps between the bed material or fuel, causing the bed material or fuel to become loose or be blown up so that it flows within the furnace 1.

[0078] In this embodiment of the present disclosure, the air cap 3 is located at the bottom of the furnace 1, and air can be supplied into the furnace 1 through the air cap 3. The air supply direction can be any direction such as upward or outward. Figure 2 The following description uses five wind caps 3 as an example. It is understood that the number of wind caps 3 and their air delivery direction are not limited in the embodiments disclosed herein.

[0079] In some embodiments, the bed material in the bed layer 11 mainly comprises coal slag, and the fuel in the fuel layer 12 mainly comprises coal. In other embodiments, the bed material in the bed layer 11 mainly comprises coal slag, and the fuel in the fuel layer 12 mainly comprises at least one of biomass fuel and combustible municipal solid waste. Further, for example, the fuel mainly comprises: biomass fuel, or combustible municipal solid waste, or both biomass fuel and combustible municipal solid waste.

[0080] In this embodiment of the disclosure, existing conveying devices or components of the boiler can be used for conveying fuel or bed material, thus eliminating the need for additional conveying devices and reducing the cost of modifying existing boilers. For example, when slag and coal are mixed in a layered manner, it can be... Figure 2 Coal is fed through feed port 2, and coal slag is conveyed through the observation furnace door, with each layer being conveyed alternately. When biomass (or combustible waste) and coal slag are mixed in layers, biomass (or combustible waste) can be directly fed through feed port 2, and then coal slag can be conveyed through the observation furnace door, with each layer being conveyed alternately, to achieve layer mixing.

[0081] In at least some embodiments, the bed material and fuel can be mixed in an alternative layering manner. Figure 4A cross-sectional schematic diagram of a fluidized bed boiler provided for another embodiment of this disclosure. Figure 4A This is a schematic diagram of the process of laying multiple ignition layers according to another embodiment of the present disclosure.

[0082] For example, such as Figure 4 and Figure 4A As shown, the multiple ignition layers 10 include a bed material layer 11' and multiple fuel layers 12; at this time, step S3, laying multiple ignition layers 10 in the boiler, includes:

[0083] S301': Lay out the bed material in one go to form a bed material layer 11';

[0084] S302': Fuel is fed multiple times to form multiple fuel layers 12 on a bed material layer 11'. That is, the bed material layer 11' and the multiple fuel layers 12 are stacked in the Z direction of the furnace 1.

[0085] Compared to Figure 2 In this embodiment, by laying the bed material in one go, multiple bed material layers 11 are formed. This reduces the number of times the bed material is sprinkled while ensuring a high bed surface temperature to guarantee the stability of laser ignition, thereby reducing the complexity of operation.

[0086] Typically, the amount of bed material used in multiple ignition layers 10 is relatively fixed. In some embodiments, when the bed material is laid multiple times to form multiple bed material layers 11, the thickness of each bed material layer 11 will be relatively small, thus forming... Figure 2 The diagram shows multiple bed material layers 11. In this case, the total thickness of the multiple bed material layers 11 = the thickness of each bed material layer 11 × the number of bed material layers 11. In other embodiments, when the bed material is laid in one go, the thickness of the bed material layers can be relatively large, thus forming... Figure 4 The example shown is a bed material layer 11'. At this time, the thickness of the bed material layer 11' is equal to the total thickness of the plurality of bed material layers 11.

[0087] For example, such as Figure 4 As shown, multiple air caps 3 are located at the bottom of the furnace chamber 1, and the thickness of the bed material layer 11' is set to have a vertical distance d above the top of the air caps 3, which is 5-200mm, further 80-120mm, and further approximately 100mm.

[0088] In some embodiments, the bed material in the bed layer 11' mainly comprises coal slag, and the fuel in the fuel layer 12 mainly comprises coal. In other embodiments, the bed material in the bed layer 11' mainly comprises coal slag, and the fuel in the fuel layer 12 mainly comprises at least one of biomass fuel and combustible municipal solid waste. Further, for example, the fuel mainly comprises: biomass fuel, or combustible municipal solid waste, or both biomass fuel and combustible municipal solid waste.

[0089] When using coal, for example, in Figure 4 When the fuel is coal, only the bed material layer 11' needs to be laid, and then coal is gradually spread and fed layer by layer. The laser beam L scans the newly laid coal bed surface layer by layer to ignite it. Since new coal slag is produced after the coal burns, and the new coal slag remains in the fluidized bed, it is continuously replenished to the bed material layer 11'. The characteristic of the above method is that the laser beam only acts on the coal bed, and the bed material is heated only after the coal is ignited and burning.

[0090] In at least some embodiments, the bed material and fuel are mixed in an blending manner. Figure 5 A cross-sectional schematic diagram of a fluidized bed boiler provided in another embodiment of this disclosure. Figure 5A This is a schematic diagram of the process of laying multiple ignition layers according to another embodiment of the present disclosure.

[0091] For example, such as Figure 5 and Figure 5A As shown, the multiple ignition layers 10 include multiple mixed fuel layers 13.

[0092] At this point, step S3, which involves laying multiple ignition layers 10 inside the furnace 1, includes:

[0093] S301”: Mixing bed material and fuel in a certain proportion to form a mixed fuel;

[0094] S302”: Multiple mixing of fuel is fed to form multiple mixing fuel layers 13 (four mixing fuel layers are shown as an example in the figure). That is, multiple mixing fuel layers 13 are stacked in the Z direction of the furnace 1.

[0095] Compared to layered mixing, in this embodiment, the bed material and fuel are mixed together, forming a mixed fuel layer with each application. Thus, when the laser beam L irradiates the mixed fuel, it heats both the bed material and ignites the fuel, further reducing the total number of applications while maintaining a high bed surface temperature to ensure stable laser ignition. Therefore, the above method is a preferred embodiment of the present invention.

[0096] In some embodiments, the bed material in the mixed fuel layer 13 mainly includes coal slag, and the fuel mainly includes coal. When biomass fuel or non-mineral fuels such as combustible municipal solid waste are used as fuel, due to the large difference in specific gravity between them and the bed material, they are prone to separation during the spreading process after being mixed.

[0097] In this embodiment of the disclosure, non-mineral fuels (biomass fuels or combustible municipal solid waste) are more suitable for mixing with the bed material in a layered mixing manner, especially Figure 4 The layering method shown avoids separation of the bed material and fuel during the spreading process.

[0098] In some embodiments, the bed material and fuel can be mixed in various ways. For example, coal slag and coal can be pre-mixed and then loaded into the bottom of the feeding device (e.g., a hopper), or they can be mixed in real time in the hopper, i.e., mixed while filling the bottom of the hopper.

[0099] In at least some embodiments, after each ignition layer is laid, scanning the ignition layer in the laser scanning area with the laser beam in step S4 includes: after each fuel layer 12 or mixed fuel layer 13 is formed, scanning the fuel layer 12 or mixed fuel layer 13 in the laser scanning area with the laser beam L.

[0100] For example, combining Figure 2 , Figure 3 , Figure 4 After each fuel layer 12 is laid, a laser beam L scans the fuel layer 12 in the laser scanning area T to ignite the fuel in the fuel layer 12 using laser ignition.

[0101] For example, combining Figure 3 and Figure 5 After each layer of mixed fuel 13 is laid, the mixed fuel layer 13 in the laser scanning area T is scanned with a laser beam L to ignite the mixed fuel in the mixed fuel layer 13 with laser.

[0102] In at least some embodiments, after each ignition layer is laid, scanning the ignition layer in the laser scanning area with the laser beam in step S4 further includes: after each bed material layer 11 or bed material layer 11' is laid, scanning the bed material layer 11 or bed material layer 11' in the laser scanning area T with the laser beam L.

[0103] In this embodiment of the disclosure, regardless of whether the bed material is laid multiple times or once, the bed material layer can be heated by scanning the laser scanning area T with a laser beam L after the bed material layer is formed. This not only helps to increase the bed surface temperature, but also helps to achieve heat preservation and heat transfer effects on the fuel layer or mixed fuel layer.

[0104] Furthermore, in order to reduce ignition costs, the bed material layer closest to the wind cap 3 or the bottom of the furnace 1 can be heated without heating the bed material layer formed later.

[0105] For example, such as Figure 2 As shown, after the first bed material layer 11a is formed, the first bed material layer 11a in the laser scanning area T can be scanned with a laser beam L to heat the first bed material layer 11a. The second bed material layer 11b formed subsequently does not need to be scanned with a laser beam again. Since both the first fuel layer 12a and the second fuel layer 12b, which are close to the second bed material layer 11b, are scanned by the laser, it is sufficient to maintain the temperature of the second bed material layer 11b.

[0106] For example, such as Figure 4 As shown, since only one bed material layer 11' is formed, after forming one bed material layer 11', the bed material layer 11' in the laser scanning area T can be scanned with a laser beam L.

[0107] In at least some embodiments, the indicator light used to indicate the laser beam L in step S2 can be visible light that travels along the same optical path as the laser beam L, such as red light.

[0108] In this embodiment of the present disclosure, by using an indicator light to indicate the transmission path and target area of ​​the laser beam L in advance, the operator can see the target scanning area of ​​the indicator light before the laser beam L officially scans, which is beneficial to determining the laser scanning area T of the laser beam L on the bed surface of the furnace 1.

[0109] Without a pointer light, if the laser beam L is turned on and the irradiated area is located in an unsafe zone, it may pose a safety hazard. Moreover, for accurate irradiation, precise positioning of the target area is required. In this embodiment, by first simulating the target irradiation area of ​​the laser beam L using a pointer light, not only is the safety of using the laser beam improved, but the precise positioning of the laser beam on the target area is also improved.

[0110] Figure 6 This is a schematic diagram illustrating the process of adjusting the laser beam according to an embodiment of this disclosure. In at least some embodiments, such as... Figure 6 As shown, step S2, which involves guiding the indicator light used to indicate the laser beam to the target area on the boiler bed, may include:

[0111] S201: A laser guiding component is provided for guiding the laser beam or indicator light;

[0112] S202: Adjusting the extension and rotation angle of the laser guiding component within the furnace to achieve scanning of the laser beam L onto the laser scanning area T; and

[0113] S203: Adjust the pitch and rotation angles of the laser guiding component outside the furnace to achieve scanning of the laser beam L onto the laser scanning area T.

[0114] In this embodiment, the laser guiding component includes, for example, optical components. By providing optical components, the scanning area or scanning angle of the laser beam L can be flexibly adjusted while ensuring laser ignition. For example, in areas with low bed surface temperature, the scanning angle of the laser can be adjusted to repeatedly scan a certain area, thereby helping to increase the temperature of the local area.

[0115] Optical components suitable for laser transmission and the characteristics of fluidized bed boilers can be selected to guide the laser beam. Effective technical measures are taken to minimize energy attenuation caused by suspended particulate matter (PMx) during the laser beam transport process and by water absorption, ensuring sufficient ignition energy at the set location.

[0116] By setting the aforementioned optical components, the positive pressure characteristics of the fluidized bed boiler furnace can be adapted, and the laser beam L can be introduced without altering the boiler body or other conditions. This allows for a simple method to achieve large-area bed surface scanning ignition, combustion assistance, and stable combustion, and also facilitates the easy removal of the laser guiding components after ignition is completed.

[0117] For example, such as Figure 3 As shown, in a horizontal plane perpendicular to the Z direction (e.g., the XY plane), the area of ​​the laser scanning region T is smaller than the area of ​​the cross-section of the furnace 1. That is, the laser scanning region T falls completely into the furnace 1, which avoids damage to the furnace wall 1A of the furnace 1.

[0118] For example, the shape of the laser scanning area T matches the shape of the cross-section of the furnace chamber 1. For example, if the cross-section of the furnace chamber 1 is rectangular, the shape of the laser scanning area T is also rectangular. Furthermore, each side of the laser scanning area T has a set safety distance s between itself and the furnace wall 1A, which is, for example, greater than 50 mm, and further, for example, between 50 mm and 150 mm, thereby further preventing the laser beam L from irradiating the furnace wall 1A during the scanning process.

[0119] The above description uses the example of rectangular shapes for both the laser scanning area T and the cross-section of the furnace 1. However, the embodiments disclosed herein are not limited to this.

[0120] For example, the laser beam L has Figure 3 The light spot LP shown can be a collection of one or more laser beams. During scanning, the light spot LP can move linearly multiple times in the same direction within the laser scanning area T, or it can reciprocate, to irradiate as much as possible every part of the bed surface in the defined scanning area, thereby improving the uniformity of heating. This disclosure does not limit the movement method of the light spot LP.

[0121] In this embodiment of the present disclosure, the incident angle of the laser beam L onto the bed surface is adjustable. Figure 2B A cross-sectional schematic diagram of a fluidized bed boiler provided for another embodiment of this disclosure. (See diagram below.) Figure 2B As shown, the laser beam L' can be obliquely incident on the bed surface inside the furnace chamber 1. For example, the incident angle between the incident direction of the laser beam L' and the bed surface is an acute angle, and further, this incident angle is, for example, 25 degrees. In this way, the purpose of laser scanning can also be achieved. Therefore, the embodiments of this disclosure do not limit the incident angle of the laser.

[0122] In at least some embodiments, calculating the amount of the bottom material for ignition includes calculating the amount Dc of the bed material in the bottom material and calculating the amount Dr of the fuel in the bottom material.

[0123] For example, when calculating the amount Dr of the fuel in the bottom material, the following steps are included:

[0124] S101: According to the total calorific value Q' required to raise a predetermined amount of cinder to a predetermined temperature during traditional diesel ignition, calculate the total calorific value Q required for ignition, which includes: obtaining the amount P of diesel used in traditional diesel ignition and the average calorific value Q0 of diesel according to experience, and calculating the total calorific value Q required for ignition with the fuel: Q = Q' = Q0×P; and

[0125] S102: According to the total calorific value Q and the average calorific value Q1 of the fuel, calculate the amount Dr of the fuel in the bottom material: Dr = Q÷Q1.

[0126] During traditional diesel ignition, it is necessary to heat a certain volume or weight of cinder with diesel and then ignite it after reaching the preset temperature. In order to calculate the amount of fuel in the bottom material of the present application, first obtain the amount P of diesel used in traditional diesel ignition and the average calorific value Q0 of diesel according to experience, and calculate the total calorific value Q' = Q0×P required to raise a predetermined amount of cinder to a predetermined temperature. Then, make the total calorific value Q required for ignition with the fuel equal to the total calorific value Q', that is, Q = Q'. Thus, the total calorific value Q required for ignition with the fuel in the present application can be determined. Through the above calculation process, the calculation method of the present application is more scientific, which is conducive to actual production, and the calculated data is also more reliable and true.

[0127] For example, when calculating the amount Dc of the bed material, the calculation method is slightly different according to the type of fuel used. In the embodiments of the present disclosure, assume that the amount of cinder used in traditional diesel ignition is T.

[0128] For example, when the fuel in the bottom material is a mineral fuel (such as coal), the amount Dc of the bed material is < T; when the fuel in the bottom material is a non-mineral fuel (such as biomass or combustible domestic waste), the amount Dc of the bed material is ≈ T.

[0129] For example, when the fuel is a mineral fuel, first calculate the amount Dz of the mineral fuel slag generated during the combustion of the mineral fuel with the amount Dr: Dz = Dr×a, where a is the generation coefficient of the mineral fuel slag; then, according to the amount Dz of the mineral fuel slag, calculate the amount Dc of the bed material: Dc = T - Dz. For the convenience of calculation, Dc, Dr, Dz, and T are all measured in weight or volume.

[0130] For example, when the fuel is a non-mineral fuel, the amount of bed material Dc is determined to be approximately equal to the amount of coal ash T used for diesel ignition.

[0131] In this embodiment, following the law of conservation of energy, the total calorific value Q required for the entire process of ignition, combustion, and stable combustion is calculated based on the quantity and calorific value of other fuels consumed by traditional ignition methods. Traditional ignition methods conventionally use a certain amount (e.g., volume or weight) T of bed material (e.g., coal ash) and heat it with a quantity P of diesel fuel. These are important reference values ​​that have been proven through long-term engineering practice to reliably ignite cold fuels. Calculating the total calorific value Q first, using the diesel fuel quantity P as a benchmark, and then calculating the bed material quantity Dc and fuel quantity Dr in the bottom material based on the total calorific value Q, is more scientific, practical, and convenient.

[0132] In at least some embodiments, the laser ignition method further includes: using the calculated bed material amount Dc as the total bed material amount in the plurality of ignition layers, and using the calculated fuel amount Dr as the total fuel amount in the plurality of ignition layers.

[0133] For example, in the case of Figure 2 When the mixture is layered, the total amount of bed material in all bed layers 11 should be equal to the aforementioned bed material amount Dc, and the total amount of fuel in all fuel layers 12 should be equal to the aforementioned fuel amount Dr.

[0134] For example, in the case of Figure 4 When the mixture is mixed in layers, the total amount of bed material in bed layer 11' should be equal to the aforementioned amount of bed material Dc, and the total amount of fuel in all fuel layers 12 should be equal to the aforementioned amount of fuel Dr.

[0135] For example, in the case of Figure 5 When blending, the total amount of fuel and the total amount of bed material in all blended fuel layers 13 should be equal to the aforementioned fuel amount Dr and the aforementioned bed material amount Dc, respectively. For example, bed material with an amount of Dc and fuel with an amount of Dr are mixed in proportion to prepare blended fuel.

[0136] In this embodiment of the disclosure, by controlling the fuel consumption Dr and the bed material consumption Dc, the amount of bottom material required for ignition can be calculated in advance, thereby calculating the production cost required for ignition. This allows fluidized bed manufacturers to make better cost comparisons when selecting different ignition schemes, thus enabling them to make a better choice.

[0137] In at least some embodiments, after calculating the amount of ignition substrate, the laser ignition method further includes: adjusting the amount of bed material and fuel in the substrate so that the ratio between the amount of bed material and the amount of fuel is a non-constant value.

[0138] In this embodiment of the disclosure, the ratio between the amount of bed material Dc and the amount of fuel Dr can be constant or non-constant.

[0139] The ignition process is a complex process involving heating, combustion, heat transfer, and heat storage, during which the bed material can undergo quantitative changes. For example, when coal is used as fuel, the combustion of a certain amount of coal (Dr) produces a certain amount of fuel slag (i.e., coal slag, also known as bed material). This coal slag can be returned to the boiler, meaning the bed material is continuously replenished based on the amount (Dc). Therefore, the amount of bed material used gradually increases. In this case, the ratio between the amount of bed material (Dc) and the amount of fuel (Dr) is not a fixed value.

[0140] In at least some embodiments, such as Figure 1 As shown, the above-mentioned laser ignition method also includes:

[0141] S5: Bring air into furnace 1 to microfluidize the bottom material, bed material and fuel.

[0142] In this embodiment of the disclosure, "microfluidization" refers to the primary air being sent into the furnace through the air cap, causing the bed material or fuel to move slightly and be in a micro-fluid state, thereby playing a role in combustion assistance and temperature equalization.

[0143] For example, step S5 can be performed simultaneously with step S4, that is, during the scanning process of the laser beam, air is sent into the furnace 1 to assist combustion and equalize the temperature.

[0144] In one example, with Figure 2 For example, multiple ignition layers 10 are set as n ignition layers, where n is an integer greater than or equal to 10. After the bed material or fuel is fed to form the m-th ignition layer (m is an integer greater than or equal to 3 and less than or equal to 10), the laser beam L completely scans the bed surface of the m-th ignition layer more than once. Then, the laser beam L continues to scan, while the auxiliary air supply is turned off and the primary air supply is turned on. The boiler system supplies air from bottom to top with the minimum flow rate and minimum air pressure to assist combustion and homogenize the temperature, performing microfluidic combustion and temperature equalization. When the bed surface temperature reaches the set value, the bed material or fuel is fed again to form the (n+1)-th ignition layer 10.

[0145] In at least some embodiments, such as Figure 1 As shown, the above-mentioned laser ignition method also includes:

[0146] S6: Increase the air pressure and air volume of the air supply to enhance the fluidization of the bed material and fuel.

[0147] For example, after the (n+1)th ignition layer is formed, the laser beam L continues to scan the new bed surface of the (n+1)th ignition layer more than once. While continuing the scan, the primary air volume and pressure are gradually increased to enhance fluidization, combustion, and temperature equalization. This process continues until the designed amount of bed material or fuel has been completely delivered, or the accumulated amount of bed material conveyed from the furnace door reaches the required level. At this point, the volume or weight of the bed material reaches the preset value, the average temperature reaches the ignition value of the solid fuel used, and the total stored thermal energy is sufficient to ignite the delivered cold fuel. During this step, auxiliary air supply can be turned on or off. Auxiliary air supply is used to aid combustion, while primary air serves both fluidization and combustion enhancement.

[0148] In at least some embodiments, such as Figure 1 As shown, the above-mentioned laser ignition method also includes:

[0149] S7: Continue scanning the laser scanning area T with the laser beam L, so that the laser beam L acts on the plurality of ignition layers 20 to continue heating the bed material and fuel.

[0150] Step S7 aims to enhance combustion and stabilize combustion using the laser beam L. After laser ignition, for a period after normal fuel jetting, the laser beam L continues to scan the bed surface. This allows the combined light and heat energy to act on the cold fuel, working in conjunction with the high temperature provided by the bed material to further enhance combustion and stabilize combustion. The irradiation time and intensity of the laser beam L are determined according to actual needs.

[0151] In at least some embodiments, such as Figure 1 As shown, the above-mentioned laser ignition method also includes:

[0152] S8: Remove laser beam L from furnace chamber 1.

[0153] For example, after laser ignition is completed and combustion is stable within the furnace 1 for a period of time, the laser beam L can be removed from the boiler. This removal of the laser beam L may include shutting off the laser beam L or removing the laser guiding component from the boiler.

[0154] In some examples, after the boiler reliably reaches a stable combustion state, it undergoes normal fluidization and feeding combustion to complete the laser ignition process. Under the premise of ensuring that the combustion conditions are not affected and that no high temperature or dust overflows, the laser ignition guiding component is safely removed so that the laser beam L can be withdrawn.

[0155] In the laser ignition method mentioned in the above embodiments of this disclosure, the steps described therein may not necessarily be performed in the order of the steps, and may be adjusted according to the actual situation.

[0156] For example, step S2 can be performed during the execution of step S3. Figure 2 For example, this can be performed after the first bed material layer 11a is formed. The following is in conjunction with... Figure 2The structure is explained, illustrating the formation process of each ignition layer and the scanning process of the indicator light and laser beam:

[0157] 1) Form the first bed material layer 11a (i.e., the basic bed material layer).

[0158] For example, the thickness of the first bed material layer 11a is set to be 5-200mm higher than the top of the hood 3, which serves to insulate and retain heat at the bottom.

[0159] 2) Turn on the indicator light that is transmitted along the same optical path as the laser beam L and guide it to the first bed material layer 11a. Perform a full static scan on the first bed material layer 11a to determine the target area (i.e., the laser scanning area T).

[0160] For example, by scanning the target area with an indicator light, electrical and mechanical limits can be set on the laser guiding device to strictly limit the scanning of the ignition laser beam within a safe zone away from the furnace wall, accurately determining the safe zone for laser ignition. Here, "fully static" specifically refers to the boiler being in a completely silent state with only the indicator light on. Visual pre-ignition via visible light (e.g., red or green light) transmitted along the same optical path as the laser beam can improve the safety of laser ignition.

[0161] 3) Scan the first bed material layer 11a with a laser beam L to heat the first bed material layer 11a;

[0162] 4) A first fuel layer 12a is formed on the first bed material layer 11a, and the first fuel layer 12a is scanned by a quasi-static laser beam L for initial ignition.

[0163] For example, when using coal as fuel, the thickness of the first fuel layer 12a is 10-200 mm; when using biomass or combustible waste as fuel, the thickness of the first fuel layer 12a is 20-300 mm. The laser beam L scans the first fuel layer 12a with initial process parameters for initial ignition, and simultaneously begins testing parameters such as the bed surface temperature gradient and temperature. Based on actual test data and needs, the initial laser power, scanning rate, and other parameters are adjusted appropriately. The bed surface is then scanned again with the new settings. At this time, auxiliary air supply is activated to enhance the transfer of high temperature to the deeper layers of material or fuel below the bed surface, thickening the high-temperature layer. Laser beam scanning continues until the overall average temperature of the bed surface reaches the set value, at which point subsequent bed material or fuel is introduced.

[0164] 5) A first bed of fuel 11b is formed on the first fuel bed 12a;

[0165] 6) A second fuel layer 12b is formed on the first bed material layer 11b. The new bed surface formed by the second fuel layer 12b is continuously scanned by the laser beam L for laser ignition. After the new bed surface is scanned, auxiliary air is supplied until the ignition process is completed and stable combustion is formed in the boiler.

[0166] If there are more fuel layers or bed material layers on the first fuel layer 12a, the bed material can be continued to be fed to form a third bed material layer when the average temperature of the bed surface of the first fuel layer 12a reaches the set value, and then steps 3) to 6) above can be repeated.

[0167] To facilitate understanding of the laser ignition method provided in the embodiments of this application, specific examples are given below.

[0168] Example 1: Laser ignition method for a 75t / h fluidized bed boiler in a small coal-fired power unit, wherein the bed material is coal slag and the fuel is coal.

[0169] (1) Calculate the amount of coal Dr and the amount of coal slag Dc in the bottom material.

[0170] First, a field survey was conducted to obtain empirical data: When igniting traditional light diesel oil, coal ash is used as the bed material, with a volume of 3.6 × 2.5 × 0.8 = 7.2 cubic meters. Assuming an average density of 0.8, the amount of coal ash used for traditional light diesel oil ignition is T = 9 tons. The total calorific value required to heat the coal ash to the predetermined temperature using light diesel oil is Q', and the amount of diesel oil required for one ignition is approximately 5.3 tons P.

[0171] Secondly, based on the amount of diesel used for conventional diesel ignition, P (e.g., P = 5.3 tons) and the average calorific value of diesel, Q0 (e.g., Q0 = 10200 kcal / kg), the total calorific value Q required for ignition is calculated: Q = Q' = Q0 × T, that is, Q = 5300 × 10200 = 54060000 kcal.

[0172] Secondly, based on the total calorific value Q and the average calorific value Q1 of the coal (for example, Q1 = 5600 kcal / kg), calculate the amount of coal Dr: Dr = Q ÷ Q1, that is, Dr = 54060000 ÷ 5600 = 9653.57 kg ≈ 9.7 tons.

[0173] Then, calculate the amount of slag Dz produced during the combustion of coal with the dosage Dr: Dz = Dr × a, where a is the generation coefficient of mineral fuel slag. In this embodiment, a = 32.5%, Dz = 9.7 × 0.325 ≈ 3.2 tons.

[0174] Finally, based on the amount of slag Dz, the amount of coal Dc is calculated: Dc = T - Dz, that is, T - Dz = 9 - 3.2 = 5.8 tons.

[0175] (2) Mix Dc=5.8 tons of coal slag with Dr=9.7 tons of coal evenly to make 15.5 tons of mixed fuel (i.e. bottom material), and place it at the bottom of the feeding hopper;

[0176] (3) A dynamic sealing auxiliary device is adopted, and a laser beam or an indicator light that is transmitted in the same optical path as the laser beam is introduced from the observation door. The indicator light is used to determine the 3m×2m laser scanning area T and control the pitch angle and rotation angle of the optical components for scanning.

[0177] (4) Discharge the mixed fuel from the discharge port to form a first mixed fuel layer, the thickness of which is set to be approximately 120 mm above the top of the wind cap; for example, see Figure 5 This forms the bottom layer of mixed fuel 13.

[0178] (5) Scan the bed surface of the first mixed fuel layer using a laser beam. After the scan is completed, lay the next mixed fuel layer. Repeat this step until 14 mixed fuel layers are laid. The thickness of each subsequent mixed fuel layer is, for example, about 180 mm.

[0179] (6) The laser ignition process ends after about 245 minutes.

[0180] During the above process, the laser scanning parameters can be set according to the actual situation. For example, the laser scanning rate can be set to 10mm / s to 100mm / s, and further, it can be set to 10mm / s, 20mm / s, 50mm / s, 100mm / s, etc.

[0181] During the above process, air can be supplied to the boiler simultaneously with laser scanning, i.e., auxiliary air supply can be activated. The rate of auxiliary air supply can be set according to actual conditions, for example, 5-15 m / s. 3 / min, or more specifically, 9m 3 / min.

[0182] The inventors calculated the cost of the aforementioned laser ignition process. The amount of diesel fuel used for ignition is approximately 5.3 tons, with each ton of diesel costing 8560 yuan / ton, and the cost of the mixed fuel being 1487 yuan / ton. Therefore, the cost reduction = 5.30 tons × 8560 yuan / ton - 15.50 tons × 1487 yuan / ton = 45368 - 23048.50 = 22319.50 yuan. It is evident that compared to the traditional diesel ignition method, the laser ignition method of this disclosure reduces ignition costs by approximately 49.19%.

[0183] Example 2: Laser ignition of a 75t / h fluidized bed boiler in a small coal-fired power unit, where the bed material is coal slag and the fuel is biomass.

[0184] (1) Calculate the amount of biomass Dr and the amount of coal slag Dc in the bottom material.

[0185] First, a field survey was conducted to obtain empirical data: When igniting traditional light diesel oil, coal ash is used as the bed material, with a volume of 3.6 × 2.5 × 0.6 = 5.4 cubic meters. Assuming an average density of 0.8, the amount of coal ash used for traditional light diesel oil ignition is T = 6.75 tons. The total calorific value required to heat the coal ash to the predetermined temperature using light diesel oil is Q', and the amount of diesel oil required for one ignition is approximately 3.6 tons.

[0186] Secondly, based on the amount of diesel used for conventional diesel ignition, P (e.g., P = 3.6 tons) and the average calorific value of diesel, Q0 (e.g., Q0 = 10200 kcal / kg), the total calorific value required for ignition, Q, is calculated: Q = Q' = Q0 × T, that is, Q = 3600 × 10200 = 36720000 kcal.

[0187] Then, based on the total calorific value Q and the average calorific value Q1 of biomass (e.g., Q1 = 2300 kcal / kg), the amount of biomass used, Dr, is calculated: Dr = Q ÷ Q1, i.e., Dr = 36,720,000 ÷ 2300 = 15,965.21 kg ≈ 15.96 tons. When biomass is used as fuel, the amount of coal ash used, Dc, can be basically equal to the amount of coal ash used for conventional diesel ignition, T, i.e., Dc ≈ T = 6.75 tons.

[0188] (2) Lay out 6.75 tons of bed material at once; the thickness of this bed material layer 11' is set to be approximately 100mm above the top of the vent cap; for example, see Figure 4 This forms a bed material layer 11'.

[0189] (3) A dynamic sealing auxiliary device is adopted, and a laser beam or an indicator light that is transmitted in the same optical path as the laser beam is introduced from the observation door. The indicator light is used to determine the 3m×2m laser scanning area T and control the pitch angle and rotation angle of the optical components for scanning.

[0190] (4) Scan the surface of the bed material layer 11' using a laser beam. After the scanning is completed, lay the fuel layer; for example, Figure 4 Fuel layer 12 in the middle.

[0191] (5) Scan the bed surface of fuel layer 12 with a laser beam. After the scan is completed, lay the next fuel layer. Repeat this step until 16 fuel layers are laid. The thickness of each fuel layer is, for example, about 300 mm.

[0192] (6) The laser ignition process is completed and takes about 200 minutes.

[0193] During the above process, the laser scanning parameters can be set according to the actual situation. For example, the laser scanning rate can be set to 20mm / s to 150mm / s, and further, it can be set to 20mm / s, 50mm / s, 150mm / s, etc.

[0194] During the above process, air can be supplied to the boiler simultaneously with laser scanning, i.e., auxiliary air supply can be activated. The rate of auxiliary air supply can be set according to actual conditions, for example, 5-15 m / s. 3 / min, or more specifically, 6m 3 / min.

[0195] The inventors calculated the cost of the aforementioned laser ignition process. The amount of diesel fuel used for ignition is approximately 3.6 tons, with a cost of 8560 yuan / ton for diesel and 380 yuan / ton for biomass. Therefore, the cost reduction = 3.60 tons × 8560 yuan / ton - 15.96 tons × 380 yuan / ton = 30816 - 6064.80 = 24751.20 yuan. It is evident that compared to the traditional diesel ignition method, the laser ignition method of this disclosure reduces ignition costs by approximately 80.32%.

[0196] The following are precautions for operation:

[0197] (1) First, turn on only the indicator light and visualize the whole process and the whole scene for "pre-ignition" to observe the on-site situation and make necessary fine adjustments to the system as needed;

[0198] (2) Scan the indicator light to determine the ignition safety zone;

[0199] (3) Set appropriate laser power density and scanning rate to prevent coking and slagging from affecting fluidization;

[0200] (4) After the cold material is thrown, laser-enhanced combustion and stable combustion must be carried out;

[0201] (5) After the laser system is stabilized, shut it off and prevent high-temperature smoke and dust from escaping when removing the laser guiding components.

[0202] This disclosure also provides a laser ignition method for a fluidized bed boiler, comprising:

[0203] S10: Calculate the amount of ignition bed material, wherein the bed material includes bed material and fuel, wherein the fuel includes mineral fuel or non-mineral fuel, and the non-mineral fuel mainly includes at least one of biomass fuel and combustible municipal solid waste;

[0204] S20: Guide the indicator light used to indicate the laser beam to the target area on the bed surface of the furnace, and define the target area as the laser scanning area;

[0205] S30: Multiple ignition layers are laid in the furnace, the multiple ignition layers including the bed material and the fuel;

[0206] S40: The laser beam scans the first ignition layer of the plurality of ignition layers with initial process parameters to perform initial ignition, and at the same time begins to test bed surface parameters such as bed surface temperature gradient and temperature.

[0207] S50: Based on the tested bed surface parameters, adjust the laser power, laser scanning rate, and other laser parameters of the laser beam, and continue scanning the bed surface with the laser beam using the adjusted laser parameters until the average temperature of the bed surface reaches the set value. Then, lay the next ignition layer on the first ignition layer. Repeat the steps of adjusting laser parameters and scanning laser beam until the multiple ignition layers have been scanned.

[0208] S60: Air is supplied into the furnace to microfluidize the bed material and the fuel;

[0209] S70: Increase the air pressure and air volume of the air supply to enhance the fluidization degree of the bed material and the fuel;

[0210] S80: Continue scanning the laser scanning area with the laser beam, so that the laser beam acts on the plurality of ignition layers to continue heating the bed material and the fuel; and

[0211] S90: The laser beam is withdrawn from the furnace.

[0212] The laser ignition method provided in the above-described embodiments adopts the following technical approach: laying multiple ignition layers. The laser beam scans the ignition layers one by one, and the combined light and heat energy causes the bottom material to heat up, ignite, and burn, or causes the bed material to heat up; slight (weak) fluidization to aid combustion and equalize temperature; gradually increasing fluidization to aid combustion and equalize temperature; laser-enhanced combustion to stabilize combustion; and finally, normal fluidization combustion to complete the ignition process, after which the laser system is removed.

[0213] In some embodiments, the multiple ignition layers include multiple bed layers and multiple fuel layers arranged alternately, wherein the multiple bed layers include a first bed layer (as a base bed layer) and multiple second bed layers. In other embodiments, the multiple ignition layers include a bed layer and multiple fuel layers. In still other embodiments, the multiple ignition layers include multiple mixed fuel layers, each mixed fuel layer including bed material and fuel.

[0214] Compared to existing diesel ignition methods, the laser ignition method described above uses laser irradiation to achieve ignition, combustion assistance, and stable combustion. It can achieve this without modifying the boiler body and without consuming additional diesel fuel, thus reducing ignition costs and eliminating exhaust fumes caused by fuel combustion. This meets the process requirements for heating large-volume bed materials and achieves safe, reliable, and efficient laser ignition, combustion assistance, and stable combustion.

[0215] In general, the laser ignition method provided in this disclosure can achieve dynamic proportioning between bed material and fuel; it incorporates the characteristics of a fluidized bed boiler and laser transmission to introduce the laser beam; the entire process of laser ignition, combustion assistance, stable combustion, and final withdrawal adapts to the positive pressure environment of the furnace; it provides visualized laser pre-ignition, accurately locates the laser beam scanning area, and ensures boiler equipment safety; it precisely determines the ignition laser energy density, preventing coking and slagging from affecting fluidization; in the initial stage of ignition, only the laser and auxiliary air supply device are activated, while the original boiler system remains silent, reducing energy consumption and pollution. This invention preferably employs a mixing method for bed material and fuel, by laying multiple mixed fuel layers (also called mixed bottom material), and also scattering the mixed bottom material during ignition. The laser beam acts simultaneously on both the bed material and fuel (e.g., coal), heating the coal for combustion while simultaneously heating the bed material.

[0216] Furthermore, the laser ignition method provided in this disclosure has the following technical effects:

[0217] First, lasers are the highest energy (power) density energy beam that can be engineered to date. They can easily achieve power densities of 107 W / cm² or higher, or energy densities of 107 J / cm² / s or higher, generating temperatures in the thousands of degrees, far exceeding the ignition temperature of coal powder or even extremely lean coal powder of about 600°C. They can ignite all combustible materials and ensure ignition in terms of energy and temperature, maximizing the safety and reliability of ignition, combustion support, and stable combustion. They can completely eliminate the risk of major safety hazards caused by ignition errors or failures.

[0218] Secondly, it is easy to control the ignition laser energy, easy to set the ignition zone position as needed, and easy to precisely control the ignition, combustion, and stable combustion processes. It can quickly complete the entire process from ignition and combustion to stable combustion with the maximum dT / dt and dP / dt gradients that the thermoelectric system can withstand, laying a solid foundation for the revolutionary progress of thermoelectric technology.

[0219] Third, lasers are flexible high-energy beams that are easy to interface with existing thermoelectric systems, requiring less engineering modification and lower costs. Laser ignition, combustion enhancement, and stable combustion have superior environmental protection and economic benefits.

[0220] Fourth, it provides a "pre-ignition" method before actual ignition, with the indicator light clearly showing the laser transmission path and ignition spatial position, providing a panoramic and full-process visualization of the laser ignition process in advance, thereby improving the safety, reliability, and convenience of actual ignition operation;

[0221] Fifth, it is economically significant. Replacing fuel oil with solid fuel for ignition can significantly reduce ignition costs, with a maximum reduction of over 80%.

[0222] The following points should be noted in this article:

[0223] (1) The accompanying drawings of the embodiments of this disclosure only involve the structures involved in the embodiments of this disclosure. Other structures can be referred to the general design.

[0224] (2) Where there is no conflict, the embodiments of this disclosure and the features in the embodiments can be combined with each other to obtain new embodiments.

[0225] (3) The above description is merely an exemplary embodiment of this disclosure and is not intended to limit the scope of protection of this disclosure. The scope of protection of this disclosure is determined by the appended claims.

Claims

1. A laser ignition method for a fluidized bed boiler, comprising: calculating an amount of ignition material, the ignition material comprising bed material and fuel, the fuel comprising at least one of mineral fuel or non-mineral fuel, the non-mineral fuel mainly comprising at least one of biomass fuel and combustible domestic waste; directing an indicator light for indicating a laser beam to a target area on a bed surface in a hearth, and determining the target area as a laser scanning area; laying a plurality of ignition layers in the hearth, the plurality of ignition layers comprising the bed material and the fuel; scanning the ignition layer in the laser scanning area with the laser beam after each of the ignition layers is laid, wherein, in the plurality of ignition layers, the bed material and the fuel are mixed in a layer-mixed manner, the plurality of ignition layers comprising a plurality of bed material layers and a plurality of fuel layers, wherein, laying the plurality of ignition layers in the hearth comprises: delivering the bed material to form the bed material layers; delivering the fuel to form the fuel layers on the bed material layers; alternately delivering the bed material and the fuel for a plurality of times to form the plurality of fuel layers and the plurality of bed material layers arranged alternately in a longitudinal direction of the hearth, wherein, after each of the bed material layers is formed by delivering the bed material, the fuel layer is formed by delivering the fuel, and the plurality of fuel layers and the plurality of bed material layers arranged alternately are formed by delivering the bed material and the fuel for a plurality of times, wherein, the plurality of fuel layers and the plurality of bed material layers arranged alternately comprise a first bed material layer, a first fuel layer, a second bed material layer and a second fuel layer formed in sequence from bottom to top, the first bed material layer covers a plurality of air caps on a bottom of the hearth, and a thickness of the first bed material layer is set to be 5-200 mm higher than a top of each of the air caps; wherein, the laser beam has a spot, the spot moves in a same direction in the laser scanning area for a plurality of times in a straight line or reciprocating motion, wherein, an area of the laser scanning area is less than an area of a cross section of the hearth, and each edge of the laser scanning area has a set safety distance from a wall of the hearth, the safety distance is more than 50 mm. 2.The laser ignition method for the fluidized bed boiler according to claim 1, wherein the scanning the ignition layer in the laser scanning area with the laser beam after each of the ignition layers is laid, comprises: the scanning the fuel layer in the laser scanning area with the laser beam after each of the fuel layers is formed.

3. The laser ignition method for fluidized bed boilers according to claim 1, wherein, the calculating the amount of ignition material, comprises: calculating an amount of fuel in the ignition material, wherein: calculating a total heat value Q required for ignition according to a total heat value Q’ required for heating a predetermined amount of coal residue to a predetermined temperature in traditional diesel ignition, comprising: calculating the total heat value Q required for ignition with the fuel according to an amount P of diesel used in the traditional diesel ignition and an average heat value Q0 of the diesel: Q= Q’=Q0×P; and calculating the amount Dr of the fuel according to the total heat value Q and an average heat value Q1 of the fuel in the ignition material: Dr=Q÷Q1.

4. The laser ignition method for fluidized bed boilers according to claim 3, wherein, the calculating the amount of ignition material, further comprises: calculating an amount of bed material in the ignition material, wherein: When the fuel is a fossil fuel, first calculate the amount Dz of fossil fuel slag generated when the amount Dr of fossil fuel is combusted: Dz = Dr x a, where a is the generation coefficient of fossil fuel slag, and then calculate the amount Dc of the bed material according to the amount Dz of fossil fuel slag: Dc = T - Dz; When the fuel is a non-fossil fuel, calculate the amount Dc of the bed material: Dc ≈ T, where T is the amount of coal slag used for traditional diesel ignition.

5. The laser ignition method for fluidized bed boilers according to claim 4, further comprising: taking the calculated amount Dc of the bed material as the total amount of bed material in the multiple ignition layers; taking the calculated amount Dr of the fuel as the total amount of fuel in the multiple ignition layers.

6. The laser ignition method for fluidized bed boilers according to claim 1, further comprising: blowing air into the furnace to micro-fluidize the bed material and the fuel; increasing the air pressure and air volume of the blowing air to enhance the fluidization degree of the bed material and the fuel; continuing to scan the laser scanning area with the laser beam so that the laser beam acts on the multiple ignition layers to continue heating the bed material and the fuel; and withdrawing the laser beam from the furnace.

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