Combustion method for mixing biomass fuel and grate-fired furnace

Abstract

The invention provides a combustion method for mixing biomass fuel and a grate-fired furnace, and relates to the technical field of biomass combustion. The combustion method of the blended biomass fuel comprises the following steps: mixing high-quality biomass and low-quality biomass to form blended biomass; and the mixed biomass is placed in a grate-fired furnace to be burnt, and when flames are stable, mixed biomass fuel powder is sprayed into the grate-fired furnace till the mixed biomass is burnt out. The burn-off rate of the blended biomass is high, and compared with single combustion of low-quality biomass fuel, the emission amount of CO is reduced by 10%-20%, and the emission amount of NO is reduced by about 30%; after the grate-fired combustion is stable, the mixed biomass fuel powder is sprayed to support combustion in a suspension mode, an efficient combustion mode combining grate-fired combustion and suspension combustion is obtained, the heat efficiency of the grate-fired furnace is improved, and compared with non-suspension combustion-supporting combustion and suspension combustion-supporting combustion, the emission amount of CO and NO in a hearth is reduced by 35%-45%, and the emission amount of NO is almost unchanged. High-efficiency and clean combustion of the blended biomass can be realized through blending of high-quality and low-quality biomass and suspension combustion supporting, and the environment-friendly cost is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of biomass combustion, and in particular to a method for burning mixed biomass fuel in a grate-burning furnace and a grate-burning furnace for burning the mixed biomass fuel. Background Art

[0002] Biomass is a natural renewable energy source with a wide range of sources, abundant reserves and renewability. During its growth, it solidifies CO2 in the air through photosynthesis and re-emitted it into the atmosphere during its utilization. The overall process can be regarded as near-zero carbon emissions. However, biomass has a low calorific value and is prone to problems such as poor combustion effect and incomplete combustion that produces a large amount of CO and NO during direct combustion or layer combustion, which limits the development and application of biomass energy. Summary of the invention

[0003] The problem solved by the invention is that the biomass has a poor combustion effect due to its low calorific value and produces a large amount of CO and NO due to incomplete combustion.

[0004] In order to solve the above problems, the present invention provides a combustion method of mixed biomass fuel and a grate burning furnace.

[0005] In a first aspect, the present invention provides a method for burning a blended biomass fuel, comprising the following steps:

[0006] S1: Mix high-quality biomass and low-quality biomass to form a mixed biomass, wherein the high-quality biomass includes at least one of sawdust, waste paper, waste wood and papermaking sludge, and the low-quality biomass includes at least one of peanut shells, rice husks and corn stalks;

[0007] S2: placing the granular mixed biomass in a layer combustion furnace and layer burning for 4-8 minutes;

[0008] S3: Spraying mixed biomass powder into the grate furnace to suspend and assist combustion until the granular mixed biomass on the grate of the grate furnace is completely burned out.

[0009] Optionally, the high-quality biomass is sawdust, the low-quality biomass is peanut shells, and the mass ratio of sawdust to peanut shells is 1:3.

[0010] Optionally, the burning time in step S3 is 25-35 minutes.

[0011] Optionally, in step S3, the mixed biomass powder is sprayed into the position where the CO content of the combustion product is the highest in the grate furnace.

[0012] Optionally, in step S3, mixed biomass powder is sprayed into the middle of the grate furnace.

[0013] Optionally, a throat is provided in the middle of the grate furnace, the inner diameter of the throat is smaller than the inner diameter of other positions of the grate furnace, and the mixed biomass powder is sprayed into the grate furnace at 0.1-0.3 meters below the throat.

[0014] In a second aspect, the present invention provides a grate-burning furnace for blending biomass fuel, which is used to implement the combustion method of blending biomass fuel as described in any of the above items, and has a material injection device for conveying blended biomass powder into the grate-burning furnace.

[0015] Optionally, the material injection device is located in the middle of the grate furnace.

[0016] Optionally, a throat is provided in the middle of the grate-burning furnace, the inner diameter of the throat is smaller than the inner diameter of other positions of the grate-burning furnace, and the material injection device is arranged 0.1-0.3 meters below the throat.

[0017] Optionally, the material injection device has a nozzle, and the diameter of the nozzle is 0.1-0.2 meters.

[0018] The beneficial effect of the combustion method of a blended biomass fuel in a layer-burning furnace of the present invention is: high-quality biomass and low-quality biomass are mixed to form a blended biomass, and the advantages of high-quality biomass fuel, such as high volatility, flammability, and low ash content, are utilized to produce a synergistic effect with low-quality biomass fuel, thereby improving the conditions of high ash content and incomplete combustion when low-quality biomass is burned. Compared with the single combustion of low-quality biomass fuel, the burnout rate of the blended biomass fuel is high, CO emissions are reduced by 10%-20%, and NO emissions are reduced by about 30%; after the layer-burning combustion is stable, the blended biomass fuel powder is sprayed in for suspension combustion assistance, thereby obtaining an efficient combustion mode combining layer-burning with suspension combustion, thereby improving the thermal efficiency of the layer-burning furnace, and compared with the non-suspended combustion assistance, the suspended combustion assistance reduces 35%-45% of CO in the furnace, and the NO emissions remain almost unchanged. By blending high-quality and low-quality biomass and suspending combustion assistance, efficient and clean combustion of the blended biomass can be achieved, thereby reducing environmental protection costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a flow chart of a combustion method of a blended biomass fuel according to an embodiment of the present invention;

[0020] Figure 2 This is a cloud diagram of the fluent results of CO in the furnace of the grate-fired furnace of Example 1 of the present invention;

[0021] Figure 3 This is a program diagram of the fluent software for calculating the PPM value of CO at the outlet in Example 1 of the present invention;

[0022] Figure 4 This is a program diagram of the fluent software for calculating the oxygen concentration ratio at the outlet in Example 1 of the present invention;

[0023] Figure 5This is a cloud diagram of the fluent results of NO in the furnace of the grate-fired furnace of Example 1 of the present invention;

[0024] Figure 6 This is a program diagram of the fluent software for calculating the PPM value of NO at the outlet in Example 1 of the present invention;

[0025] Figure 7 This is a cloud diagram of the fluent results of CO in the furnace of the grate-fired furnace of Comparative Example 1 of the present invention;

[0026] Figure 8 This is a fluent software program diagram for calculating the PPM value of CO at the outlet of Comparative Example 1 of the present invention;

[0027] Fig. 9 This is a program diagram of the fluent software for calculating the oxygen concentration ratio at the outlet of comparative example 1 of the present invention;

[0028] Fig.10 This is a cloud diagram of the fluent results of NO in the furnace of the grate-fired furnace of Comparative Example 1 of the present invention;

[0029] Fig.11 This is a program diagram of the fluent software for calculating the PPM value of NO at the outlet of Comparative Example 1 of the present invention;

[0030] Fig.12 This is a cloud diagram of the fluent results of CO in the furnace of the grate-fired furnace of Comparative Example 2 of the present invention;

[0031] Fig.13 This is a fluent software program diagram for calculating the PPM value of CO at the outlet of comparative example 2 of the present invention;

[0032] Fig.14 This is a program diagram of the fluent software for calculating the oxygen concentration ratio at the outlet of comparative example 2 of the present invention;

[0033] Fig.15 This is a cloud diagram of the fluent results of NO in the furnace of the grate-fired furnace of Comparative Example 2 of the present invention;

[0034] Fig.16 This is a program diagram of the fluent software for calculating the PPM value of NO at the outlet of Comparative Example 2 of the present invention;

[0035] Fig.17 This is a cloud diagram of the fluent results of CO in the furnace of the grate-fired furnace of Comparative Example 3 of the present invention;

[0036] Fig.18 This is a program diagram of the fluent software for calculating the PPM value of CO at the outlet of Comparative Example 3 of the present invention;

[0037] Fig.19This is a program diagram of the fluent software for calculating the oxygen concentration ratio at the outlet of comparative example 3 of the present invention;

[0038] Fig. 20 This is a cloud diagram of the fluent results of NO in the furnace of the grate-fired furnace of Comparative Example 3 of the present invention;

[0039] Fig.21 This is a program diagram of the fluent software for calculating the PPM value of NO at the outlet of Comparative Example 3 of the present invention;

[0040] Description of reference numerals:

[0041] 1. Furnace; 2. Throat position; 3. Material injection device position. DETAILED DESCRIPTION

[0042] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. Although certain embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be interpreted as being limited to the embodiments described herein. On the contrary, these embodiments are provided to provide a more thorough and complete understanding of the present invention. It should be understood that the drawings and embodiments of the present invention are only for exemplary purposes and are not intended to limit the scope of protection of the present invention.

[0043] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention;

[0044] The term "including" and its variations used in this article are open inclusions, that is, "including but not limited to"; the term "based on" is "based at least in part on"; the term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one other embodiment"; the term "some embodiments" means "at least some embodiments"; the term "optionally" means "optional embodiments". The relevant definitions of other terms will be given in the following description. It should be noted that the concepts of "first" and "second" mentioned in the present invention are used to distinguish different objects, rather than to describe a specific order or a primary and secondary relationship. In addition, the terms "first" and "second" are used only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, the meaning of "multiple" is two or more.

[0045] In view of the problems existing in the above-mentioned related technologies, this embodiment provides a combustion method of mixed biomass fuel and a grate burning furnace.

[0046] like Figure 1 As shown, a combustion method of a mixed biomass fuel provided by an embodiment of the present invention comprises the following steps:

[0047] S1: Mix high-quality biomass and low-quality biomass to form a mixed biomass, wherein the high-quality biomass includes at least one of sawdust, waste paper, waste wood and papermaking sludge, and the low-quality biomass includes at least one of peanut shells, rice husks and corn stalks;

[0048] S2: placing the granular mixed biomass in a layer combustion furnace and layer burning for 4-8 minutes;

[0049] S3: Spraying mixed biomass powder into the grate furnace to suspend and assist combustion until the granular mixed biomass on the grate of the grate furnace is completely burned out.

[0050] In this embodiment, high-quality biomass and low-quality biomass are mixed to form a blended biomass. The advantages of high-quality biomass fuel, such as high volatile matter, flammability and low ash content, are used to produce a synergistic effect with low-quality biomass fuel to improve the high ash content and incomplete combustion of low-quality biomass. Compared with the single combustion of low-quality biomass fuel, the burnout rate of the blended biomass fuel is high, CO emissions are reduced by 10%-20%, and NO emissions are reduced by about 30%. When the layer combustion is stable, the powder of the blended biomass fuel is sprayed in for suspension combustion, and an efficient combustion mode combining layer combustion and suspension combustion is obtained, which improves the thermal efficiency of the layer combustion furnace. Compared with the non-suspended combustion, the suspended combustion reduces 35%-45% of CO in the furnace, and the NO emissions remain almost unchanged. By mixing high-quality and low-quality biomass and suspending the combustion, efficient and clean combustion of the blended biomass can be achieved, and the environmental protection cost can be reduced.

[0051] Optionally, in step S2, the granular mixed biomass may be placed in a grate furnace.

[0052] Specifically, according to the actual layer combustion situation, after 4-8 minutes of layer combustion of the mixed biomass, the combustion can proceed stably.

[0053] Based on the above, in a possible implementation, the high-quality biomass is sawdust, the low-quality biomass is peanut shells, and the mass ratio of sawdust to peanut shells is 1:3. The industrial analysis data table of sawdust and peanut shells is shown in Table 1.

[0054] Table 1 Industrial analysis data of sawdust and peanut shells

[0055]

[0056] In Table 1, the advantages of high-quality biomass sawdust, such as high volatile matter, flammability and low ash content, produce a synergistic effect with low-quality biomass peanut shells, improving the high ash content and incomplete combustion of peanut shells. The blended biomass fuel has a high burnout rate and less CO and NO emissions.

[0057] Optionally, the burning time in step S3 is 25-35 minutes.

[0058] In this optional embodiment, under the high-efficiency combustion combining layer combustion and suspension combustion, after 25-35 minutes of combustion, the granular mixed biomass on the grate of the layer combustion furnace can be burned out, and the combustion process ends.

[0059] Optionally, in step S3, the mixed biomass powder is sprayed into the position where the CO content of the combustion product is the highest in the grate furnace.

[0060] In this optional embodiment, the location with the highest CO content of the combustion product in the layer burning furnace is the area with the most incomplete combustion. Mixed biomass powder is sprayed here to assist combustion, thereby obtaining an efficient combustion method that combines layer burning with suspended combustion, improving the thermal efficiency of the layer burning furnace, and completely burning the fuel, thereby reducing the generation of CO in the furnace.

[0061] Optionally, in step S3, mixed biomass powder is sprayed into the middle of the grate furnace.

[0062] In this optional embodiment, due to the structure of the biomass layer burning furnace, the biomass fuel is ignited at the front arch, and then the burned ash is sent out of the rear arch along with the transmission of the chain grate in the layer burning furnace. Therefore, the middle part of the furnace is the part with the most incomplete combustion, and then mixed biomass powder suspension is sprayed into the middle part of the layer burning furnace to assist combustion, so that the fuel is completely burned, thereby reducing the generation of CO in the furnace.

[0063] Optionally, a throat is provided in the middle of the grate furnace, the inner diameter of the throat is smaller than the inner diameter of other positions of the grate furnace, and the mixed biomass powder is sprayed into the grate furnace at 0.1-0.3 meters below the throat.

[0064] In this optional embodiment, the part of the furnace where the most CO is produced is 0.1-0.3 meters below the throat. Mixed biomass powder suspension is sprayed into the layer burning furnace 0.1-0.3 meters below the throat to aid combustion, so that the granular fuel on the layer burning grate is completely burned, thereby reducing the production of CO in the furnace.

[0065] The embodiment of the present invention provides a grate-burning furnace for blending biomass fuel, which is used to implement the combustion method of blending biomass fuel as described above, and has a material injection device for conveying blended biomass powder into the grate-burning furnace. Figure 2 shown.

[0066] In this embodiment, the material injection device sprays mixed biomass powder into the layer combustion furnace for suspended combustion, thereby obtaining an efficient combustion mode combining layer combustion with suspended combustion, improving the thermal efficiency of the layer combustion furnace, and improving the combustion effect of the fuel, thereby reducing the generation of CO in the furnace 1, achieving efficient and clean combustion of mixed biomass, and reducing environmental protection costs.

[0067] Optionally, the material injection device is located in the middle of the grate furnace.

[0068] In this optional embodiment, due to the structure of the biomass layer burning furnace, the biomass fuel is ignited at the front arch, and then the burned ash is sent out of the rear arch along with the transmission of the structure inside the layer burning furnace. Therefore, the middle part of the furnace 1 is the part with the most incomplete combustion. Then, a material injection device is arranged in the middle part of the layer burning furnace to inject mixed biomass powder for suspended combustion, so that the fuel is completely burned, thereby reducing the generation of CO in the furnace 1.

[0069] Optionally, the layer combustion furnace has a throat in the middle, the inner diameter of the throat is smaller than the inner diameter of other positions of the layer combustion furnace, and the material injection device is arranged 0.1-0.3 meters below the throat. Figure 2 .

[0070] In this optional embodiment, the part of the furnace 1 where the most CO is produced is 0.1-0.3 meters below the throat. A material injection device is set 0.1-0.3 meters below the throat to spray mixed biomass powder into the layer combustion furnace to suspend and assist combustion, so that the fuel is completely burned, thereby reducing the production of CO in the furnace 1.

[0071] Optionally, the material injection device has a nozzle, and the diameter of the nozzle is 0.1-0.2 meters.

[0072] In this optional embodiment, the nozzle diameter is 0.1-0.2 meters, which can ensure that the fuel is completely burned while the amount of mixed biomass powder injected will not be excessive.

[0073] The present invention is further described below in conjunction with specific embodiments.

[0074] Example 1

[0075] Take 75kg of sawdust and 225kg of peanut shell particles to form a mixed biomass, put it in a layer burning furnace, and after 6 minutes of layer burning, spray the mixed powder of sawdust and peanut shells into the layer burning furnace through the material injection device for suspended combustion for 28 minutes. The layer burning furnace can use DZL1-0.7-S layer burning boiler, and install the material injection device in the middle of the DZL1-0.7-S layer burning boiler. The nozzle diameter of the material injection device is 0.12 meters.

[0076] Comparative Example 1

[0077] 75kg of sawdust and 225kg of peanut shell particles are used to form a granular mixed biomass, which is placed in a layer-burning furnace and layer-burned for 34 minutes. The layer-burning furnace can use a DZL1-0.7-S layer-burning boiler.

[0078] Comparative Example 2

[0079] Take 300kg of peanut shell particles and place them in a layer-burning furnace. After 6 minutes of layer burning, spray peanut shell powder into the layer-burning furnace through a material injection device for suspended combustion for 28 minutes. The layer-burning furnace can use a DZL1-0.7-S layer-burning boiler. Install a material injection device in the middle of the DZL1-0.7-S layer-burning boiler. The nozzle diameter of the material injection device is 0.12 meters.

[0080] Comparative Example 3

[0081] Take 300kg of peanut shell particles, place them in a layer-burning furnace, and burn them for 34 minutes. The layer-burning furnace can use a DZL1-0.7-S layer-burning boiler.

[0082] Effect Example

[0083] The fluent software was used to model the layer-burning furnace and simulate the working conditions. The fluent software and fluent result cloud map were used to calculate the CO and NO contents at the outlet of the layer-burning furnace. The CO and NO contents were expressed in PPM values. PPM (Parts Per Million) is a concentration unit, which means the mass of CO and NO accounts for parts per million of the total gas mass.

[0084] The calculation process of the CO and NO contents at the outlet of Example 1 is as follows:

[0085] according to Figure 2 From the percentage value on the left side of the fluent result cloud chart, we can know that the highest CO percentage is 16.0%. However, due to the change in the mixing ratio of the burning biomass and whether the suspended combustion is used, the change in the atmosphere content inside the layer combustion furnace is affected. This value cannot be compared horizontally. In this case, formula 1 needs to be input into the fluent software to calculate the CO concentration at the outlet, such as Figure 3 As shown, the PPM value of CO at the outlet is 150.741;

[0086]

[0087] Among them, CO mol is the molar concentration of CO, H2O mol is the molar concentration of H2O, obtained using fluent software.

[0088] Substituting the PPM value of 150.741 into Formula 2, the CO concentration at the outlet is 188.42625 mg / m 3 .

[0089]

[0090] Where [CO] OP is the CO concentration at the outlet, C mol is the molar mass of C, O mol is the molar mass of O.

[0091]

[0092] According to the emission standards for layer-fired furnaces, the reference oxygen content [O2] std Calculated as 9%, [O2] std 9%, [O2] op This is the oxygen concentration ratio at the outlet of the fluent software simulation result, such as Figure 4 As shown [O2] op is 5.84%, [CO] OP Substituting into equation 3, the baseline CO content is 149.150 mg / m 3 , that is, the CO content at the outlet is 149.150 mg / m 3 .

[0093] according to Figure 5 From the percentage values ​​on the left side of the fluent result cloud chart, we can know that the highest NO percentage is 0.07%, which is consistent with the CO content calculation process. Enter formula 4 into the fluent software to calculate the NO concentration at the outlet, as follows: Figure 6 As shown, the PPM value of NO at the outlet is 270.8872.

[0094]

[0095] Substituting the PPM value of 270.8872 into Formula 5, we get the NO concentration at the outlet to be 362.7953 mg / m 3 .

[0096]

[0097] Where [NO] OP is the NO concentration at the outlet, N mol is the molar mass of N, O mol is the molar mass of O.

[0098]

[0099] According to the emission standards for layer-fired furnaces, the reference oxygen content [O2] std Calculated as 9%, [O2] std 9%, [O2] opThis is the oxygen concentration ratio at the outlet of the fluent software simulation result, such as Figure 4 As shown [O2] op is 5.84%, [NO] OP Substituting into formula 6, the baseline NO content is 287.173 mg / m 3 , that is, the NO content at the outlet is 287.173 mg / m 3 .

[0100] The calculation process of the CO and NO contents at the outlet of Comparative Example 1 is as follows:

[0101] according to Figure 7 From the percentage value on the left side of the fluent result cloud chart, we can know that the highest CO percentage is 15.0%. However, due to the change in the mixing ratio of the burning biomass and whether the suspended combustion is used to affect the change in the atmosphere content inside the layer combustion furnace, this value cannot be compared horizontally. In this case, we need to input formula 1 into the fluent software to calculate the CO concentration at the outlet, such as Figure 8 As shown, the PPM value of CO at the outlet is 245.065;

[0102]

[0103] Among them, CO mol is the molar concentration of CO, H2O mol is the molar concentration of H2O, obtained using fluent software.

[0104] Substituting the PPM value of 245.065 into Formula 2, the CO concentration at the outlet is 306.33125 mg / m 3 .

[0105]

[0106] Where [CO] OP is the CO concentration at the outlet, C mol is the molar mass of C, O mol is the molar mass of O.

[0107]

[0108] According to the emission standards for layer-fired furnaces, the reference oxygen content [O2] std Calculated as 9%, [O2] std 9%, [O2] op This is the oxygen concentration ratio at the outlet of the fluent software simulation result, such as Fig. 9 As shown [O2] op is 6.47%, [CO] OPSubstituting into formula 3, the baseline CO content is 252.992 mg / m 3 , that is, the CO content at the outlet is 252.992 mg / m 3 .

[0109] according to Fig.10 From the percentage values ​​on the left side of the fluent result cloud chart, we can see that the highest NO percentage is 0.075%, which is consistent with the CO content calculation process. Enter formula 4 into the fluent software to calculate the NO concentration at the outlet, as follows: Fig.11 As shown, the PPM value of NO at the outlet is 248.3902.

[0110]

[0111] Substituting the PPM value of 248.3902 into Formula 5, we get the NO concentration at the outlet to be 332.6654 mg / m 3 .

[0112]

[0113] Where [NO] OP is the NO concentration at the outlet, N mol is the molar mass of N, O mol is the molar mass of O.

[0114]

[0115] According to the emission standards for layer-fired furnaces, the reference oxygen content [O2] std Calculated as 9%, [O2] std 9%, [O2] op This is the oxygen concentration ratio at the outlet of the fluent software simulation result, such as Fig. 9 As shown [O2] op is 6.47%, [NO] OP Substituting into formula 6, the baseline NO content is 274.741 mg / m 3 , that is, the NO content at the outlet is 274.741 mg / m 3 .

[0116] Comparative Example 1 is a mixture of sawdust and peanut shell particles placed in a layer combustion furnace for combustion. Compared with the example in which sawdust and peanut shell particles are mixed and their powder is suspended for combustion, the CO content at the outlet of Example 1 is reduced by 41.05% compared with Comparative Example 1, and the NO content is almost unchanged.

[0117] The calculation process of the CO and NO contents at the outlet of Comparative Example 2 is as follows:

[0118] according to Fig.12From the percentage value on the left side of the fluent result cloud chart, we can know that the highest CO percentage is 15.0%. However, due to the change in the mixing ratio of the burning biomass and whether the suspended combustion is used, the change in the atmosphere content inside the layer combustion furnace is affected. This value cannot be compared horizontally. In this case, formula 1 needs to be input into the fluent software to calculate the CO concentration at the outlet, such as Fig.13 As shown, the PPM value of CO at the outlet is 189.3763;

[0119]

[0120] Among them, CO mol is the molar concentration of CO, H2O mol is the molar concentration of H2O, obtained using fluent software.

[0121] Substituting the PPM value 189.3763 ​​into formula 2, the CO concentration at the outlet is 236.7204 mg / m 3 .

[0122]

[0123] Where [CO] OP is the CO concentration at the outlet, C mol is the molar mass of C, O mol is the molar mass of O.

[0124]

[0125] According to the emission standards for layer-fired furnaces, the reference oxygen content [O2] std Calculated as 9%, [O2] std 9%, [O2] op This is the oxygen concentration ratio at the outlet of the fluent software simulation result, such as Fig.14 As shown [O2] op is 5.26%, [CO] OP Substituting into equation 3, the baseline CO content is 180.473 mg / m 3 , that is, the CO content at the outlet is 180.473 mg / m 3 .

[0126] according to Fig.15 From the percentage values ​​on the left side of the fluent result cloud chart, we can see that the highest NO percentage is 0.075%, which is consistent with the CO content calculation process. Enter formula 4 into the fluent software to calculate the NO concentration at the outlet, as follows: Fig.16 As shown, the PPM value of NO at the outlet is 393.6829.

[0127]

[0128] Substituting the PPM value of 393.6829 into Formula 5, we get the NO concentration at the outlet of 527.254 mg / m 3 .

[0129]

[0130] Where [NO] OP is the NO concentration at the outlet, N mol is the molar mass of N, O mol is the molar mass of O.

[0131]

[0132] According to the emission standards for layer-fired furnaces, the reference oxygen content [O2] std Calculated as 9%, [O2] std 9%, [O2] op This is the oxygen concentration ratio at the outlet of the fluent software simulation result, such as Fig.14 As shown [O2] op is 5.26%, [NO] OP Substituting into formula 6, the baseline NO content is 401.972 mg / m 3 , that is, the NO content at the outlet is 401.972 mg / m 3 .

[0133] Comparative Example 2 is a process in which peanut shell particles are placed in a layer combustion furnace and burned, and their powder is sprayed into the furnace for combustion assistance after the combustion is stable. Compared with the example in which sawdust and peanut shell particles are mixed and their powder is suspended for combustion assistance, the CO content at the outlet of Example 1 is reduced by 17.36%, and the NO content is reduced by 28.56%.

[0134] The calculation process of the CO and NO contents at the outlet of Comparative Example 3 is as follows:

[0135] according to Fig.17 From the percentage value on the left side of the fluent result cloud chart, we can know that the highest CO percentage is 13.0%. However, due to the change in the mixing ratio of the burning biomass and whether the suspended combustion is used, the change in the atmosphere content inside the layer combustion furnace is affected. This value cannot be compared horizontally. In this case, formula 1 needs to be input into the fluent software to calculate the CO concentration at the outlet, such as Fig.18 As shown, the PPM value of CO at the outlet is 296.393;

[0136]

[0137] Among them, CO mol is the molar concentration of CO, H2O molis the molar concentration of H2O, obtained using fluent software.

[0138] Substituting the PPM value of 296.393 into Formula 2, we get the CO concentration at the outlet to be 370.49125 mg / m 3 .

[0139]

[0140] Where [CO] OP is the CO concentration at the outlet, C mol is the molar mass of C, O mol is the molar mass of O.

[0141]

[0142] According to the emission standards for layer-fired furnaces, the reference oxygen content [O2] std Calculated as 9%, [O2] std 9%, [O2] op This is the oxygen concentration ratio at the outlet of the fluent software simulation result, such as Fig.19 As shown [O2] op is 5.53%, [CO] OP Input into the fluent software and import formula 3 to obtain the baseline CO content of 287.388 mg / m 3 , that is, the CO content at the outlet is 287.388 mg / m 3 .

[0143] according to Fig. 20 From the percentage values ​​on the left side of the fluent result cloud chart, we can see that the highest NO percentage is 0.1%, which is consistent with the CO content calculation process. Enter formula 4 into the fluent software to calculate the NO concentration at the outlet, as follows: Fig.21 As shown, the PPM value of NO at the outlet is 381.0494.

[0144]

[0145] Substituting the PPM value of 3381.0494 into Formula 5, we get the NO concentration at the outlet of 510.334 mg / m 3 .

[0146]

[0147] Where [NO] OP is the NO concentration at the outlet, N mol is the molar mass of N, O mol is the molar mass of O.

[0148]

[0149] According to the emission standards for layer-fired furnaces, the reference oxygen content [O2] std Calculated as 9%, [O2] std 9%, [O2] op This is the oxygen concentration ratio at the outlet of the fluent software simulation result, such as Fig.19 As shown [O2] op is 5.53%, [NO] OP Substituting into formula 6, the baseline NO content is 395.863 mg / m 3 , that is, the NO content at the outlet is 395.863 mg / m 3 .

[0150] Comparative Example 3 is a method of burning peanut shell particles in a layer combustion furnace. Compared with Example 1 in which sawdust and peanut shell particles are mixed and their powder is suspended for combustion, Example 1 has a 48.1% lower CO content and a 27.46% lower NO content at the outlet than Comparative Example 3.

[0151] It can be seen that the CO content at the outlet of a single low-quality biomass particle layer combustion with suspension combustion assistance is 37.2% lower than that of a single low-quality biomass particle layer combustion without suspension combustion assistance, the CO content at the outlet of a high-low quality biomass particle mixed layer combustion without suspension combustion assistance is 11.97% lower than that of a single low-quality biomass particle layer combustion without suspension combustion assistance, the CO content at the outlet of a single low-quality biomass particle layer combustion with suspension combustion assistance is 28.66% lower than that of a high-low quality biomass mixed layer combustion without suspension combustion assistance, the CO content at the outlet of a high-low quality biomass particle mixed layer combustion with suspension combustion assistance is 48.1% lower than that of a single low-quality biomass particle layer combustion without suspension combustion assistance, the CO content at the outlet of a high-low quality biomass particle mixed layer combustion with suspension combustion assistance is 41.05% lower than that of a high-low quality biomass mixed layer combustion without suspension combustion assistance, and the CO content at the outlet of a high-low quality biomass particle mixed layer combustion with suspension combustion assistance is 17.36% lower than that of a single low-quality biomass particle layer combustion with suspension combustion assistance. As for the NO emission simulation results, it can be seen that the mixing of high-quality and low-quality biomass can greatly improve the NO emission effect, and the effect of suspended combustion on NO emission is negligible. The NO content at the outlet of high-quality and low-quality mixed combustion is about 30% lower than that of single low-quality biomass combustion. Therefore, the mixed biomass composed of high-quality biomass and low-quality biomass has a high burnout rate and less CO and NO emissions; the efficient combustion method combining layer combustion with suspended combustion can also improve the thermal efficiency of the layer combustion furnace, and improve the combustion effect of the mixed biomass, realize efficient and clean combustion of the mixed biomass, and reduce environmental protection costs.

[0152] Although the present invention is disclosed as above, the protection scope of the present invention is not limited thereto. Those skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention, and these changes and modifications will fall within the protection scope of the present invention.

Claims

1. A combustion method of mixed biomass fuel, characterized in that: The following steps are involved: S1: Mix high-quality biomass and low-quality biomass to form a mixed biomass, wherein the high-quality biomass includes at least one of sawdust, waste paper, waste wood and papermaking sludge, and the low-quality biomass includes at least one of peanut shells, rice husks and corn stalks; S2: placing the granular mixed biomass in a grate burning furnace and performing grate burning for 4-8 minutes; S3: spraying the mixed biomass powder into the grate furnace to suspend and assist combustion until the mixed biomass on the grate of the grate furnace is completely burned out.

2. The combustion method of blended biomass fuel according to claim 1, characterized in that: The high-quality biomass is sawdust, and the low-quality biomass is peanut shells. The mass ratio of the sawdust to the peanut shells is 1:

3.

3. The combustion method of blended biomass fuel according to claim 1, characterized in that: The burning time in step S3 is 25-35 minutes.

4. The combustion method of blended biomass fuel according to claim 1, characterized in that: In the step S3, the mixed biomass powder is sprayed into the position where the CO content of the combustion product is the highest in the grate furnace.

5. The combustion method of blended biomass fuel according to claim 4, characterized in that: In the step S3, the mixed biomass powder is sprayed into the middle of the grate furnace.

6. The combustion method of blended biomass fuel according to claim 5, characterized in that: The layer-burning furnace has a throat in the middle, the inner diameter of the throat is smaller than the inner diameter of other positions of the layer-burning furnace, and the mixed biomass powder is sprayed into the layer-burning furnace at 0.1-0.3 meters below the throat.

7. A layer burning furnace burning mixed biomass fuel, characterized in that: A method for implementing the combustion method of the blended biomass fuel as described in any one of claims 1 to 6, comprising a material injection device for conveying the blended biomass powder into the grate furnace.

8. The grate-fired furnace for burning mixed biomass fuel according to claim 7, characterized in that: The material injection device is located in the middle of the layer combustion furnace.

9. The grate-fired furnace for burning mixed biomass fuel according to claim 8, characterized in that: The layer combustion furnace has a throat in the middle, the inner diameter of the throat is smaller than the inner diameter of other positions of the layer combustion furnace, and the material injection device is arranged 0.1-0.3 meters below the throat.

10. The grate-fired furnace for burning mixed biomass fuel according to claim 7, characterized in that: The material injection device has a nozzle, and the diameter of the nozzle is 0.1-0.2 meters.

Images