A flue structure for a waste incineration boiler with different calorific values

Abstract

The present invention provides a first flue structure applicable to waste incineration boilers with different calorific values, which successively includes Region 1, Region 2 and Region 3 from top to bottom; the Region 1, Region 2 and Region 3 are independently paved with SiC-Si3N4 refractory bricks; the SiC-Si3N4 refractory bricks are prepared from SiC-Si3N4 refractory materials; the SiC-Si3N4 refractory materials are selected from one or more of SiC50 refractory materials, SiC65 refractory materials and SiC75 refractory materials. Compared with the prior art, in view of the problems such as overheating of the subsequent heating surface and tube explosion caused by the single composition and arrangement method of the refractory materials in the current first flue, the present invention adopts the design of the refractory material composition and its arrangement method according to different waste calorific values. By selecting different SiC-Si3N4 refractory materials, while ensuring environmental protection indicators, the radiant heating surface of the first flue is fully utilized, and the boiler investment is reduced; the obtained first flue structure applicable to waste incineration boilers with different calorific values realizes that the inlet flue gas temperature of the subsequent heating surface does not exceed the limit value, ensuring the long-term stable and safe operation of the boiler.

Description

Technical Field

[0001] The present invention relates to the technical field of waste incineration boilers, and more specifically, to a first-pass flue structure suitable for waste incineration boilers with different calorific values. Background Art

[0002] Domestic waste classification is one of the core measures for the country to promote ecological civilization construction. With the gradual advancement of domestic waste classification, the calorific value of waste has gradually increased significantly. This is because after classification, the proportion of kitchen and fruit waste in the incoming waste decreases, the proportion of paper and rubber waste increases, and the leachate production rate decreases. After the implementation of the domestic waste classification policy in Shanghai in July 2019, research shows that compared with mixed disposal, the density of dry waste decreases by about 36.4%, the moisture content decreases by about 36%, and the lower calorific value of dry waste suddenly increases to 13160 kJ / kg.

[0003] The increase in calorific value has posed challenges to the lifespan of the refractory materials in the first-pass flue of waste incineration. In existing technical solutions, the entire first-pass flue of waste incineration boilers is made of conventional materials with compositions of SiC-SiO2 type or Al2O3-SiO2 type, and has the following disadvantages: (1) There are problems of poor thermal conductivity and weak oxidation resistance. The refractory material plays a role in protecting the heating surface of the first-pass flue. If the refractory material in the first-pass flue is oxidized and degraded, there is a risk of tube explosion on the heating surface; (2) There are problems of low density, high porosity, and poor compressive strength. On-site construction cannot ensure uniform composition of the refractory material, and the baking time is prolonged; (3) Using a single material layout method, there is a problem that the radiant heating surface of the first-pass flue cannot be fully utilized, resulting in the inlet flue gas temperature of the subsequent heating surface exceeding the limit value, thereby causing problems such as tube explosion. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a first-pass flue structure suitable for waste incineration boilers with different calorific values, which can reliably adapt to the characteristics of different calorific values, thermal conductivity, and oxidation resistance, ensure environmental protection indicators, fully utilize the radiant heating surface of the first-pass flue, and reduce the boiler investment.

[0005] The present invention provides a first-pass flue structure suitable for waste incineration boilers with different calorific values, which sequentially includes Region 1, Region 2, and Region 3 from top to bottom; said Region 1, Region 2, and Region 3 are independently laid with SiC-Si3N4 refractory bricks;

[0006] The SiC-Si3N4 refractory bricks are prepared from SiC-Si3N4 type refractory materials;

[0007] The SiC-Si3N4 type refractory materials are selected from one or more of SiC50 type refractory materials, SiC65 type refractory materials, and SiC75 type refractory materials.

[0008] Preferably, the dimensions of the region 1 are width × depth × height of (9000 - 9200) mm × (5900 - 6000) mm × (2900 - 3100) mm;

[0009] The dimensions of the region 2 are width × depth × height of (9000 - 9200) mm × (5900 - 6000) mm × (2700 - 2800) mm;

[0010] The dimensions of the region 3 are width × depth × height of (9000 - 9200) mm × (5900 - 6000) mm × (5000 - 5200) mm.

[0011] Preferably, the dimensions of the SiC - Si3N4 refractory brick are length × width × thickness of (200 - 300) mm × (200 - 300) mm × (35 - 45) mm.

[0012] Preferably, the preparation method of the SiC - Si3N4 refractory brick is specifically as follows:

[0013] The SiC - Si3N4 refractory material is subjected to high - temperature firing to obtain the SiC - Si3N4 refractory brick.

[0014] Preferably, the firing temperature of the high - temperature firing is 1400°C - 1500°C, the firing pressure in the furnace is slightly negative pressure, the firing atmosphere is N2, and the concentration of the N2 is 98% - 99.99%.

[0015] Preferably, the SiC50 refractory material includes the following components:

[0016] SiC 48wt% - 53wt%;

[0017] Si3N4 14wt% - 17wt%;

[0018] SiO2 4wt% - 9wt%;

[0019] Antioxidant rare - earth oxide 3wt% - 7wt%;

[0020] The balance is Al2O3;

[0021] The thermal conductivity of the SiC50 refractory material is 3 w / (m×k) - 4 w / (m×k).

[0022] Preferably, the SiC65 refractory material includes the following components:

[0023] SiC 63wt% - 68wt%;

[0024] Si3N4 15wt% - 18wt%;

[0025] SiO2 3 wt% - 6 wt%;

[0026] Antioxidant rare earth oxide 3 wt% - 6 wt%;

[0027] The balance is Al2O3;

[0028] The thermal conductivity of the SiC65 type refractory material is 5 w / (m×k) - 7 w / (m×k).

[0029] Preferably, the SiC75 type refractory material comprises the following components:

[0030] SiC 72 wt% - 76 wt%;

[0031] Si3N4 13 wt% - 16 wt%;

[0032] SiO2 2 wt% - 4 wt%;

[0033] Antioxidant rare earth oxide 2 wt% - 3 wt%;

[0034] The balance is Al2O3;

[0035] The thermal conductivity of the SiC75 type refractory material is 9 w / (m×k) - 11 w / (m×k).

[0036] Preferably, the antioxidant rare earth oxide is Y2O3.

[0037] Preferably, the single furnace waste treatment capacity is greater than or equal to 700 t / d.

[0038] The present invention provides a first flue structure applicable to waste incineration boilers with different calorific values, which successively includes Region 1, Region 2 and Region 3 from top to bottom; the Region 1, Region 2 and Region 3 are independently paved with SiC - Si3N4 refractory bricks; the SiC - Si3N4 refractory bricks are prepared from SiC - Si3N4 type refractory materials; the SiC - Si3N4 type refractory materials are selected from one or more of SiC50 type refractory materials, SiC65 type refractory materials and SiC75 type refractory materials. Compared with the prior art, aiming at the problems of subsequent heating surface overheating and tube explosion caused by the single composition and layout method of the first flue refractory material at present, the present invention adopts the refractory material composition design and its layout method according to different waste calorific values. By selecting different SiC - Si3N4 type refractory materials, while ensuring environmental protection indicators, the radiant heating surface of the first flue is fully utilized, and the boiler investment is reduced; the first flue structure applicable to waste incineration boilers with different calorific values obtained realizes that the inlet flue gas temperature of the subsequent heating surface does not exceed the limit value, ensuring the long - term stable and safe operation of the boiler. Brief Description of the Drawings

[0039] Figure 1 Schematic diagram of the first flue structure applicable to waste incineration boilers with different calorific values in the embodiments of the present invention;

[0040] Figure 2 Physical diagram of the first flue structure applicable to waste incineration boilers with different calorific values in the embodiments of the present invention;

[0041] Figure 3 Physical diagram of the first flue structure arranged with conventional traditional SiC - SiO₂ type castable refractory materials in Comparative Example 1;

[0042] Figure 4 Comparison chart of the oxidation weight gain rate of the first flue structure between Embodiments 1 - 6 and Comparative Document 1;

[0043] Figure 5 Comparison chart of the volume change rate of the first flue structure between Embodiments 1 - 6 and Comparative Document 1;

[0044] Figure 6 Change characteristics of the SiC - Si₃N₄ type material and the conventional material in the comparative example during the oxidation erosion process in the present invention. Specific Embodiments

[0045] Next, in combination with the embodiments of the present invention, the technical solutions of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0046] The present invention provides a first flue structure applicable to waste incineration boilers with different calorific values, which successively includes Region 1, Region 2, and Region 3 from top to bottom; the Region 1, Region 2, and Region 3 are independently laid with SiC - Si₃N₄ refractory bricks;

[0047] The SiC - Si₃N₄ refractory bricks are prepared from SiC - Si₃N₄ type refractory materials;

[0048] The SiC - Si₃N₄ type refractory materials are selected from one or more of SiC50 type refractory materials, SiC65 type refractory materials, and SiC75 type refractory materials.

[0049] See Figure 1 As shown, the present invention provides a first flue structure applicable to waste incineration boilers with different calorific values, which successively includes Region 1, Region 2, and Region 3 from top to bottom; the Region 1, Region 2, and Region 3 are independently laid with SiC - Si₃N₄ refractory bricks.

[0050] In the present invention, the dimensions of the region 1, width × depth × height, are preferably (9000 - 9200) mm × (5900 - 6000) mm × (2900 - 3100) mm, more preferably 9090 mm × 5940 mm × 3000 mm; the dimensions of the region 2, width × depth × height, are preferably (9000 - 9200) mm × (5900 - 6000) mm × (2700 - 2800) mm, more preferably 9090 mm × 5940 mm × 2780 mm; the dimensions of the region 3, width × depth × height, are preferably (9000 - 9200) mm × (5900 - 6000) mm × (5000 - 5200) mm, more preferably 9090 mm × 5940 mm × 5175 mm. On this basis, the dimensions of the overall structure of the first flue of the waste incineration boiler applicable to different calorific values, width × depth × height, are preferably (9000 - 9200) mm × (5900 - 6000) mm × (10600 - 11100) mm, more preferably 9090 mm × 5940 mm × 10955 mm.

[0051] In the present invention, the SiC - Si3N4 refractory brick is prepared from SiC - Si3N4 type refractory material; the dimensions of the SiC - Si3N4 refractory brick, length × width × thickness, are preferably (200 - 300) mm × (200 - 300) mm × (35 - 45) mm, more preferably (230 - 250) mm × (230 - 250) mm × 40 mm.

[0052] In the present invention, the preparation method of the SiC - Si3N4 refractory brick is preferably specifically as follows:

[0053] The SiC - Si3N4 type refractory material is subjected to high - temperature firing to obtain the SiC - Si3N4 refractory brick.

[0054] In the present invention, the firing temperature of the high - temperature firing is preferably 1400°C - 1500°C, more preferably 1450°C; the firing pressure in the furnace during the high - temperature firing is preferably slightly negative pressure, more preferably - 30 Pa - - 10 Pa; the firing atmosphere of the high - temperature firing is preferably N2, and the concentration of the N2 is preferably 98% - 99.99%, more preferably 99%.

[0055] In the present invention, the SiC - Si3N4 type refractory material is selected from one or more of SiC50 type refractory material, SiC65 type refractory material and SiC75 type refractory material, preferably SiC50 type refractory material, SiC65 type refractory material or SiC75 type refractory material.

[0056] In the present invention, the SiC50 type refractory material preferably comprises the following components:

[0057] SiC 48 wt% - 53 wt%;

[0058] Si3N4 14 wt% - 17 wt%;

[0059] SiO2 4 wt% - 9 wt%;

[0060] Antioxidant rare earth oxide 3 wt% - 7 wt%;

[0061] The balance is Al2O3;

[0062] More preferably:

[0063] SiC 50 wt%;

[0064] Si3N4 15 wt%;

[0065] SiO2 5 wt%;

[0066] Antioxidant rare earth oxide 4 wt%;

[0067] Al2O3 26 wt%.

[0068] In the present invention, the thermal conductivity of the SiC50 type refractory material is preferably 3 W / (m×K) - 4 W / (m×K), and more preferably 3.5 W / (m×K).

[0069] In the present invention, the SiC65 type refractory material preferably comprises the following components:

[0070] SiC 63 wt% - 68 wt%;

[0071] Si3N4 15 wt% - 18 wt%;

[0072] SiO2 3 wt% - 6 wt%;

[0073] Antioxidant rare earth oxide 3 wt% - 6 wt%;

[0074] The balance is Al2O3;

[0075] More preferably:

[0076] SiC 65 wt%;

[0077] Si3N4 16 wt%;

[0078] SiO2 5 wt%;

[0079] Antioxidant rare earth oxide 4 wt%;

[0080] Al2O3 10 wt%.

[0081] In the present invention, the thermal conductivity of the SiC65 refractory material is preferably 5 W / (m×K) to 7 W / (m×K), and more preferably 6 W / (m×K).

[0082] In the present invention, the SiC75 refractory material preferably comprises the following components:

[0083] SiC 72 wt% to 76 wt%;

[0084] Si3N4 13 wt% to 16 wt%;

[0085] SiO2 2 wt% to 4 wt%;

[0086] Antioxidant rare earth oxide 2 wt% to 3 wt%;

[0087] The balance of Al2O3;

[0088] More preferably:

[0089] SiC 75 wt%;

[0090] Si3N4 14 wt%;

[0091] SiO2 2 wt%;

[0092] Antioxidant rare earth oxide 2 wt%;

[0093] Al2O3 7 wt%.

[0094] In the present invention, the thermal conductivity of the SiC75 refractory material is preferably 9 W / (m×K) to 11 W / (m×K), and more preferably 10 W / (m×K).

[0095] In the present invention, the antioxidant rare earth oxide is preferably Y2O3.

[0096] On this basis, the present invention can obtain different types of SiC-Si3N4 refractory bricks, including SiC50 type, SiC65 type, and SiC75 type; the present invention further arranges different types of SiC-Si3N4 refractory bricks in a 3×3 environmental temperature measurement point area of a flue; through the arrangement of the flue by the present invention, under the condition of ensuring antioxidant property, a flue structure applicable to waste incineration boilers with different calorific values is obtained, and the outlet flue gas temperature in the uppermost area is preferably 800°C to 1100°C, more preferably 850°C to 1000°C, and the flue gas residence time is preferably greater than 2 s.

[0097] In the present invention, the waste treatment capacity of the flue structure applicable to waste incineration boilers with different calorific values is preferably not less than 700 t / d per furnace, and more preferably 750 t / d per furnace.

[0098] In a preferred embodiment of the present invention, the calorific value of the garbage is lower than 1400 kcal / kg; on this basis, the regions 1, 2, and 3 are all paved with SiC50 refractory bricks.

[0099] In another preferred embodiment of the present invention, the calorific value of the garbage is 1400 kcal / kg - 1600 kcal / kg; on this basis, the regions 1, 2, and 3 are paved with SiC65, SiC50, and SiC50 refractory bricks respectively.

[0100] In another preferred embodiment of the present invention, the calorific value of the garbage is 1600 kcal / kg - 1800 kcal / kg; on this basis, the regions 1, 2, and 3 are paved with SiC75, SiC65, and SiC50 refractory bricks respectively.

[0101] In another preferred embodiment of the present invention, the calorific value of the garbage is 1800 kcal / kg - 2000 kcal / kg; on this basis, the regions 1, 2, and 3 are paved with SiC75, SiC65, and SiC65 refractory bricks respectively.

[0102] In another preferred embodiment of the present invention, the calorific value of the garbage is 2000 kcal / kg - 2200 kcal / kg; on this basis, the regions 1, 2, and 3 are paved with SiC75, SiC75, and SiC65 refractory bricks respectively.

[0103] In another preferred embodiment of the present invention, the calorific value of the garbage is higher than 2200 kcal / kg; on this basis, the regions 1, 2, and 3 are all paved with SiC75 refractory bricks.

[0104] The present invention relates to the field of protection of the heating surface of urban domestic waste incineration boilers. By specifically designing the composition and layout of refractory materials, a first-pass flue structure suitable for waste incineration boilers with different calorific values is obtained. This first-pass flue structure can adapt to changes in the calorific value of different garbage, helps to make full use of the heat transfer capacity of the radiant heating surface of the first-pass flue, improves the service life of refractory materials, and limits the inlet flue gas temperature of the subsequent heating surface not to exceed the limit value, ensuring the long-term safe and stable operation of the boiler, that is, helping to prevent the boiler tube explosion caused by the over-temperature of the inlet flue gas temperature of the subsequent heating surface.

[0105] The present invention provides a first flue duct structure applicable to waste incineration boilers with different calorific values, which successively includes Region 1, Region 2 and Region 3 from top to bottom; the Region 1, Region 2 and Region 3 are independently paved with SiC-Si3N4 refractory bricks; the SiC-Si3N4 refractory bricks are prepared from SiC-Si3N4 refractory materials; the SiC-Si3N4 refractory materials are selected from one or more of SiC50 refractory materials, SiC65 refractory materials and SiC75 refractory materials. Compared with the prior art, aiming at the problems of subsequent heating surface over-temperature, tube explosion, etc. caused by the single composition and layout method of the refractory materials in the first flue duct at present, the present invention adopts the refractory material composition design and its layout method for different waste calorific values. By selecting different SiC-Si3N4 refractory materials, while ensuring environmental protection indicators, the radiant heating surface of the first flue duct is fully utilized, and the boiler investment is reduced; the first flue duct structure applicable to waste incineration boilers with different calorific values realizes that the inlet flue gas temperature of the subsequent heating surface does not exceed the limit value, ensuring the long-term stable and safe operation of the boiler.

[0106] In order to further illustrate the present invention, the following detailed description is given through the following embodiments. In the following embodiments of the present invention, the SiC-Si3N4 refractory materials include SiC50 type, SiC65 type and SiC75 type. Among them, the composition of the SiC50 refractory material: the SiC content is 50 wt%, the Si3N4 content is 15 wt%, the SiO2 content is 5 wt%, the antioxidant rare earth oxide Y2O3 content is 4 wt%, the Al2O3 content is 26 wt%, and the thermal conductivity is 3.5 w / (m×k);

[0107] The composition of the SiC65 refractory material: the SiC content is 65 wt%, the Si3N4 content is 16 wt%, the SiO2 content is 5 wt%, the antioxidant rare earth oxide Y2O3 content is 4 wt%, the Al2O3 content is 10 wt%, and the thermal conductivity is 6 w / (m×k);

[0108] The composition of the SiC75 refractory material: the SiC content is 75 wt%, the Si3N4 content is 14 wt%, the SiO2 content is 2 wt%, the antioxidant rare earth oxide Y2O3 content is 2 wt%, the Al2O3 content is 7 wt%, and the thermal conductivity is 10 w / (m×k);

[0109] The specific preparation method adopts the method of firing into bricks at high temperature in the factory. The firing temperature is 1450 °C, the firing pressure in the furnace is slightly negative pressure, specifically -20 Pa, the N2 concentration in the firing atmosphere is 99%, the size of the formed brick is length×width of 250 mm×250 mm, and the thickness of the formed brick is 40 mm;

[0110] The first flue duct structure applicable to waste incineration boilers with different calorific values is shown in Figure 1As shown in the figure, different types of SiC-Si3N4 refractory bricks are arranged in a 3×3 environmental protection temperature measurement point area of a flue. Specifically, the size of area 1 is width×depth×height = 9090mm×5940mm×3000mm; the size of area 2 is width×depth×height = 9090mm×5940mm×2780mm; the size of area 3 is width×depth×height = 9090mm×5940mm×5175mm. By arranging the refractory materials in the above flue, the outlet flue gas temperature in the uppermost area reaches 850°C - 1000°C, and the flue gas residence time is greater than 2s.

[0111] Example 1

[0112] For the case of a single furnace with a waste treatment capacity of 750t / d and a waste calorific value of 1200kcal / kg, the size of the 3×3 environmental protection temperature measurement point area of the flue is width×depth×height = 9090mm×5940mm×10955mm. The refractory bricks prepared from the above SiC50 type refractory materials are arranged in areas 1, 2, and 3 (sorted from top to bottom). For the physical diagram, see Figure 2 shown.

[0113] Example 2

[0114] For the case of a single furnace with a waste treatment capacity of 750t / d and a waste calorific value of 1500kcal / kg, the size of the 3×3 environmental protection temperature measurement point area of the flue is width×depth×height = 9090mm×5940mm×10955mm. The refractory bricks prepared from SiC65 type, SiC50 type, and SiC50 type refractory materials are arranged in areas 1, 2, and 3 respectively.

[0115] Example 3

[0116] For the case of a single furnace with a waste treatment capacity of 750t / d and a waste calorific value of 1700kcal / kg, the size of the 3×3 environmental protection temperature measurement point area of the flue is width×depth×height = 9090mm×5940mm×10955mm. The refractory bricks prepared from SiC75 type, SiC65 type, and SiC50 type refractory materials are arranged in areas 1, 2, and 3 respectively.

[0117] Example 4

[0118] For the case of a single furnace with a waste treatment capacity of 750t / d and a waste calorific value of 1900kcal / kg, the size of the 3×3 environmental protection temperature measurement point area of the flue is width×depth×height = 9090mm×5940mm×10955mm. The refractory bricks prepared from SiC75 type, SiC65 type, and SiC65 type refractory materials are arranged in areas 1, 2, and 3 respectively.

[0119] Example 5

[0120] For the case where the single-furnace waste treatment capacity is 750 t / d and the waste calorific value is 2100 kcal / kg, the dimensions of the 3×3 environmental temperature measurement point area in the first flue are width × depth × height = 9090 mm × 5940 mm × 10955 mm. Refractory bricks made of SiC75 type, SiC75 type, and SiC65 type refractory materials are arranged in regions 1, 2, and 3 respectively.

[0121] Example 6

[0122] For the case where the single-furnace waste treatment capacity is 750 t / d and the waste calorific value is 2400 kcal / kg, the dimensions of the 3×3 environmental temperature measurement point area in the first flue are width × depth × height = 9090 mm × 5940 mm × 10955 mm. Refractory bricks made of the above-mentioned SiC75 type refractory materials are arranged in regions 1, 2, and 3.

[0123] Comparative Example 1

[0124] For the case where the single-furnace waste treatment capacity is 750 t / d and the waste calorific value is 2100 kcal / kg, the dimensions of the 3×3 environmental temperature measurement point area in the first flue are width × depth × height = 9090 mm × 5940 mm × 10955 mm. Conventional traditional SiC-SiO2 type castable refractory materials are arranged in regions 1, 2, and 3. See the physical diagram in Figure 3 shown; The composition of the conventional traditional SiC-SiO2 type castable refractory material: the SiC content is 50 wt%, the SiO2 content is 30 wt%, and the rest is Al2O3 with a content of 20 wt%, and the thermal conductivity is 2 w / (m×k).

[0125] The comparison of the outlet flue gas temperature of the first flue structure between Examples 1 to 6 and Comparative Document 1 is shown in Table 1.

[0126] Table 1 Comparison data of the outlet flue gas temperature of the first flue structure between Examples 1 to 6 and Comparative Document 1

[0127]

[0128]

[0129] At the same time, the mass and volume change rates after oxidation of the first flue structure between Examples 1 to 6 and Comparative Document 1 are shown in Figures 4 - 5 shown. From the results of Table 1 and Figures 4 - 5 it can be seen that by arranging the SiC-Si3N4 type refractory bricks in the 3×3 environmental temperature measurement point area of the first flue in the way of the present invention, the best heat transfer effect of the radiation heating surface can be obtained, thereby reducing the outlet flue gas temperature of the first flue and ensuring the long-term operation of the boiler.

[0130] In addition, through Figures 2 - 3It can be clearly seen from the comparison that in terms of the refractory lining of the waste heat boiler, conventional refractories need to be dried and formed with the furnace, while the arrangement of refractory bricks prepared from refractory materials in the present invention can ensure properties such as density and compressive strength, and can fully meet the environmental protection requirements (850 °C, 2 s), that is, the temperature is higher than 850 °C within the 2-s travel of the flue gas; at the same time, the heat of the flue gas can be efficiently absorbed by the working medium in the pipe, so as to design an economically appropriate radiant heating surface.

[0131] If the heat in the high-temperature flue gas cannot be efficiently absorbed by the working medium in the pipe, resulting in over-temperature in the furnace, conventional refractory materials will show serious failure forms such as degradation and cracking; at this time, corrosive substances in the flue gas will erode the water-cooled wall, resulting in high-temperature corrosion, thus bringing challenges to the long-term stable operation of the waste heat boiler of the waste incinerator; in order to adapt to different waste calorific values, the material of the refractory in the first flue of the waste heat boiler needs to be designed and adjusted at present; at the same time, the components of corrosive substances in the waste incinerator are complex, and the silicon carbide (SiC) material with neutrality has outstanding resistance to acid and alkali component erosion; therefore, the refractory material in the first flue of the waste heat boiler in the present invention is a refractory material with SiC-Si3N4 as the main body; Table 2 lists the performance comparison and analysis of the refractory materials in two ways, and it can be seen that the SiC-Si3N4 type refractory material in the present invention is superior to the conventional material in terms of porosity, mechanical properties, and density.

[0132] Table 2 Performance comparison of refractory materials in two ways

[0133] <![CDATA[SiC-SiO2 type or Al2O3-SiO2 type]]> <![CDATA[SiC-Si3N4 type]]> Apparent porosity (%) 18 ≤15 <![CDATA[Apparent density (g / cm 3 )]]> ≥2.4 ≥2.68 Cold crushing strength (MPa) ≥58.8 ≥147.1 Linear change rate after re - firing (1000°C) ≤0.5 ≤0.45 Crack resistance (quenched in water at 1000°C) ≥25 ≥30

[0134] Figure 6 are the change characteristics of the SiC-Si3N4 type material and the conventional material of the comparative example in the oxidation erosion process in the present invention, where (a) is the SiC-Si3N4 type material and (b) is the conventional material; from Figure 6 it can be seen that due to the lower density of the conventional material than that of the SiC-Si3N4 type material and the obvious volume expansion during the oxidation process, the conventional material finally cracks, accelerating the material degradation; for the SiC-Si3N4 type material, antioxidant additives are added during the brick-making process in the factory, and at the same time, the brick-burning atmosphere is regulated. Therefore, the SiC-Si3N4 type material has a stable volume, is not easy to crack / peel off, and thus has an antioxidant ability far higher than that of the conventional material. At the same time, the higher the density of the material, the stronger the antioxidant degree.

[0135] In summary, in the current existing technology, only a single material layout method is adopted for the refractory material of the first flue of the waste incineration boiler, and the conventional composition of the refractory material is of the SiC-SiO2 type or the Al2O3-SiO2 type. There are problems such as poor heat conduction performance of the heating surface, poor oxidation resistance, and insufficient utilization of the radiant heating surface of the first flue, resulting in over-temperature bursting of the boiler heating surface. The present invention provides a composition design and layout method for the refractory material of the first flue of a waste incineration boiler suitable for different calorific values. In order to make full use of the radiant heating surface of the first flue and at the same time ensure environmental protection indicators, the composition design is based on heat conduction performance and oxidation resistance, mainly including silicon carbide SiC and silicon nitride Si3N4. At the same time, the SiC-Si3N4 type refractory material is prefabricated into bricks at high temperature in the factory, effectively improving the density and compressive strength of the refractory material; the layout method involves the layout of different types of SiC-Si3N4 refractory bricks in the 3×3 environmental temperature measurement point area of the first flue. The present invention aims at the problems such as over-temperature and bursting of the subsequent heating surface caused by the single composition and layout method of the refractory material of the first flue, and adopts a composition design and layout method for the refractory material according to different waste calorific values, realizing that the inlet flue gas temperature of the subsequent heating surface does not exceed the limit value, and ensuring the long-term stable and safe operation of the boiler.

[0136] The beneficial effects of the present invention are as follows:

[0137] (1) Aiming at the problem that the conventional composition of the refractory material of the first flue of the waste incineration boiler is of the SiC-SiO2 type or the Al2O3-SiO2 type, with poor heat conduction performance and weak oxidation resistance, a SiC-Si3N4 type refractory material suitable for different waste calorific values is developed and designed, and the composition design is adjusted according to different calorific values, mainly divided into SiC50 type, SiC65 type, and SiC75 type. Under the condition of ensuring oxidation resistance, SiC-Si3N4 type refractory materials with different thermal conductivities are designed;

[0138] (2) Aiming at the problem that the conventional refractory material of the first flue of the waste incineration boiler is constructed on-site and dried with the furnace, with low density, high porosity, and poor compressive strength, the developed and designed SiC-Si3N4 type refractory material is prefabricated into bricks at high temperature in the factory, ensuring the stable composition of the refractory material, thereby extending the actual service life of the refractory material;

[0139] (3) Aiming at the problem that the refractory material of the first flue of the waste incineration boiler adopts a single material layout method, resulting in insufficient utilization of the radiant heating surface of the first flue, leading to the inlet flue gas temperature of the subsequent heating surface exceeding the limit value, thus causing problems such as bursting, a layout method of different SiC-Si3N4 type refractory materials is proposed, which helps to ensure environmental protection indicators while making full use of the radiant heating surface of the first flue and reducing the boiler investment.

[0140] The foregoing description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A flue structure suitable for waste incineration boilers with different calorific values, characterized in that: From top to bottom, it includes area 1, area 2 and area 3; said area 1, area 2 and area 3 are independently paved with SiC-Si3N4 refractory bricks; The SiC-Si3N4 refractory bricks are made of SiC-Si3N4 type refractory materials; The SiC-Si3N4 type refractory material is selected from one or more of SiC50 type refractory material, SiC65 type refractory material and SiC75 type refractory material; When the calorific value of the garbage is lower than 1400 kcal / kg, the areas 1, 2 and 3 are all paved with refractory bricks made of SiC50 refractory material; When the calorific value of the garbage is 1400kcal / kg to 1600kcal / kg, the area 1, area 2 and area 3 are paved with refractory bricks made of SiC65 type, SiC50 type and SiC50 type refractory materials respectively; When the calorific value of the garbage is 1600kcal / kg to 1800kcal / kg, the area 1, area 2 and area 3 are paved with refractory bricks made of SiC75, SiC65 and SiC50 refractory materials respectively; When the calorific value of the garbage is 1800kcal / kg to 2000kcal / kg, the area 1, area 2 and area 3 are paved with refractory bricks made of SiC75 type, SiC65 type and SiC65 type refractory materials respectively; When the calorific value of the garbage is 2000kcal / kg to 2200kcal / kg, the area 1, area 2 and area 3 are paved with refractory bricks made of SiC75, SiC75 and SiC65 refractory materials respectively; When the calorific value of the garbage is higher than 2200 kcal / kg, the area 1, area 2 and area 3 are all paved with refractory bricks made of SiC75 type refractory material.

2. The flue structure applicable to waste incineration boilers with different calorific values according to claim 1 is characterized in that: The dimensions of the area 1 are (9000-9200) mm in width × (5900-6000) mm in depth × (2900-3100) mm in height; The dimensions of the area 2 are (9000-9200) mm in width × (5900-6000) mm in depth × (2700-2800) mm in height; The dimensions of the area 3 in terms of width×depth×height are (9000-9200) mm×(5900-6000) mm×(5000-5200) mm.

3. The flue structure applicable to waste incineration boilers with different calorific values according to claim 1 is characterized in that: The dimensions of the SiC-Si3N4 refractory brick are (200-300) mm in length×width×thickness×(200-300) mm×(35-45) mm.

4. The flue structure applicable to waste incineration boilers with different calorific values according to claim 1 is characterized in that: The preparation method of the SiC-Si3N4 refractory brick is specifically as follows: The SiC-Si3N4 refractory material is fired at high temperature to obtain SiC-Si3N4 refractory bricks.

5. The flue structure applicable to waste incineration boilers with different calorific values according to claim 4 is characterized in that: The firing temperature of the high-temperature firing is 1400° C. to 1500° C., the firing pressure in the furnace is slightly negative, the firing atmosphere is N2, and the concentration of N2 is 98% to 99.99%.

6. The flue structure applicable to waste incineration boilers with different calorific values according to claim 1 is characterized in that: The SiC50 refractory material comprises the following components: SiC 48wt%~53wt%; Si3N414wt%~17wt%; SiO2 4wt%~9wt%; 3wt% to 7wt% of antioxidant rare earth oxides; The balance is Al2O3; The thermal conductivity of the SiC50 refractory material is 3w / (m×k) to 4w / (m×k).

7. The flue structure applicable to waste incineration boilers with different calorific values according to claim 1 is characterized in that: The SiC65 refractory material includes the following components: SiC 63wt%~68wt%; Si3N415wt%~18wt%; SiO2 3wt%~6wt%; 3wt% to 6wt% of antioxidant rare earth oxides; The balance is Al2O3; The thermal conductivity of the SiC65 refractory material is 5w / (m×k) to 7w / (m×k).

8. The flue structure applicable to waste incineration boilers with different calorific values according to claim 1 is characterized in that: The SiC75 refractory material includes the following components: SiC 72wt%~76wt%; Si3N413wt%~16wt%; SiO2 2wt%~4wt%; 2 wt% to 3 wt% of antioxidant rare earth oxides; The balance is Al2O3; The thermal conductivity of the SiC75 refractory material is 9w / (m×k) to 11w / (m×k).

9. The flue structure applicable to waste incineration boilers with different calorific values according to any one of claims 6 to 8, characterized in that: The antioxidant rare earth oxide is Y2O3.

10. The flue structure applicable to waste incineration boilers with different calorific values according to claim 1, characterized in that: The waste processing capacity of a single furnace is greater than or equal to 700t / d.

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