Novel hearth structure for retarding coking of garbage incinerator and garbage incinerator

Abstract

The novel hearth structure comprises a water cooling wall and a high-heat-conductivity-coefficient corrosion-resistant castable layer which are sequentially arranged from outside to inside, and a sealing high-temperature fused salt layer is further arranged between the water cooling wall and the high-heat-conductivity-coefficient corrosion-resistant castable layer. By the adoption of the hearth structure, when the temperature in the incinerator suddenly rises, due to the fact that the heat storage capacity of the fused salt layer is large, a large amount of heat is immediately absorbed for buffering, the temperature in the incinerator is reduced, meanwhile, large fluctuation of boiler loads is reduced, and the coking condition of the boiler can be effectively relieved.

Description

Technical Field

[0001] The utility model relates to the field of garbage incinerators, in particular to a new type of furnace structure for slowing down coking of garbage incinerators and a garbage incinerator. Background Art

[0002] With the improvement of residents' living standards, the calorific value of garbage entering the furnace has increased significantly, resulting in an increase in the volumetric heat load of the furnace and an increase in the temperature inside the incinerator. The increase in the calorific value of garbage has promoted the increase in the temperature inside the incinerator, causing serious coking inside the incinerator. Since the main test is on the elements that cause coking, in the test results of the coke sample, the content of alkali metal elements K, Ca, and Na accounted for 24.38%, and the element with the highest content among the remaining elements was Si, accounting for 9.63%; in the oxide content test, the oxides with the highest content were SiO2 and CaO, accounting for 34.5% and 31.99% respectively, and the oxide with the second highest content was Al2O3, accounting for 13.05%. The alkali metal content is high, and the free alkali metal ions and sulfates form alkali metal salts with low melting points. The alkali metals in the form of oxides are easy to combine with oxides such as SiO2 and MgO to form complexes with low melting points. These substances are in a molten state at high temperatures and are easy to adhere to the wall to form coking. The presence of Fe elements will make silicate powders at high temperatures easily form low melting point compounds such as iron olivine, iron calcium aluminum silicate, calcium ferrite, calcium iron olivine, etc. with FeO, which adhere to the heated surface to form coking. From the analysis of the coke sample composition, it can be seen that the alkali metals, Si, Al elements and their oxides contained in the coke sample are high, which can easily cause garbage to coke in the furnace. In actual operation, the working conditions of the incinerator of the garbage power plant are subject to the influence of the garbage fermentation time, the load fluctuates at any time, and there is a certain amount of reducing gas in the furnace. The melting point of fly ash will be reduced by 100-200℃. Under high temperature conditions, fly ash is more likely to be molten, providing conditions for the intensification of coking.

[0003] In summary, existing waste incinerators are prone to coking when processing domestic waste, and coking will bring great challenges to the safe operation of the boiler. Coking in the water-cooled furnace affects the efficiency of the boiler's radiation heat exchange, and has an adverse effect on the water circulation safety of the natural circulation boiler and the thermal deviation of the water-cooled wall of the forced circulation boiler; when the coke blocks on the upper part of the furnace fall, they may damage the grate, causing the furnace to extinguish the fire or block the slag discharge port, and will also cause hidden dangers to the safety of workers who stop the furnace to clean the coke; and coking is easy to form a large number of large coke blocks, and large coke slag falls into the cold slag bucket and accumulates. If it cannot be removed in time, the boiler will be forced to stop operating. Utility Model Content

[0004] In order to solve the problems existing in the prior art, the utility model provides a new furnace structure for slowing down coking of a garbage incinerator and a garbage incinerator, and reduces the occurrence of coking through the new furnace structure design.

[0005] In order to achieve the above purpose, the utility model adopts the following scheme:

[0006] The utility model provides a novel furnace structure for slowing down coking of a garbage incinerator, comprising a water-cooled wall and a high thermal conductivity corrosion-resistant castable layer arranged in sequence from outside to inside, wherein a sealed high-temperature molten salt layer is also arranged between the water-cooled wall and the high thermal conductivity corrosion-resistant castable layer.

[0007] In some embodiments, the high thermal conductivity corrosion-resistant castable layer is a silicon carbide castable layer.

[0008] In some embodiments, a screen secondary air outlet device is also included, which is used to form a layer of low-temperature oxidizing screen secondary air on the inner side of the high thermal conductivity corrosion-resistant castable layer.

[0009] In some embodiments, a temperature sensor is also included. The temperature sensor is arranged between the high thermal conductivity corrosion-resistant castable layer and the sealed high-temperature molten salt layer, and is used to monitor the surface temperature of the water-cooled wall. When the temperature sensor detects a temperature exceeding the coking set temperature, the screen secondary air outlet device is automatically controlled to increase the secondary air volume and reduce the temperature at the furnace throat until the operating conditions return to normal.

[0010] In some embodiments, the temperature sensor includes a plurality of sensors disposed at different locations.

[0011] In some embodiments, the sealed high-temperature molten salt layer is composed of one or more of nitrates, chlorides, and carbonates.

[0012] In some embodiments, the sealed high-temperature molten salt layer is a potassium carbonate-based high-temperature molten salt.

[0013] In some embodiments, the high thermal conductivity corrosion-resistant castable layer has a thickness of 95 mm, and the sealed high-temperature molten salt layer has a thickness of 75 mm.

[0014] In some embodiments, the water-cooled wall includes a wall and a light pipe disposed in the wall, and the light pipe is made of carbon steel.

[0015] The utility model also provides a garbage incinerator, comprising the above-mentioned novel furnace structure for slowing down the coking of the garbage incinerator.

[0016] Beneficial effects:

[0017] The utility model provides a novel furnace structure and a garbage incinerator for slowing down the coking of a garbage incinerator. A sealed high-temperature molten salt layer is arranged between a water-cooled wall and a high thermal conductivity corrosion-resistant castable layer. When the temperature in the incinerator suddenly rises, the molten salt layer immediately absorbs a large amount of heat for buffering due to its large heat storage capacity, thereby reducing the temperature in the incinerator and reducing the large fluctuation of the boiler load, thereby effectively slowing down the occurrence of boiler coking.

[0018] In some embodiments, a boundary screen secondary air is set in the furnace throat area, so that a layer of low-temperature oxidizing screen secondary air is formed on the surface of the furnace wall in the furnace throat area, thereby increasing the ash melting point, reducing the furnace wall temperature in this area, avoiding flames and ash particles from hitting the wall, and further preventing coking. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the structure of an embodiment of the utility model;

[0020] In the figure, 1-heat-resistant layer, 2-high-temperature molten salt layer, 3-temperature sensor system, 4-light pipe, 5-wall. DETAILED DESCRIPTION

[0021] In order to make the technical solution and advantages of the utility model clearer, the technical solution of the embodiment of the utility model will be fully described below in conjunction with the drawings in the utility model. Obviously, the described embodiment is a part of the embodiment of the utility model, not all of the embodiments. Based on the embodiment of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0022] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0023] In the prior art, waste incinerators suffer from serious coking, which directly affects the normal operation of waste power plants. Shutdowns for inspection and decoking often take up a lot of time, often requiring half a year or more, greatly affecting the long-term and efficient operation of power plants. During the decoking process, the life safety of maintenance personnel is also greatly affected. How to slow down or avoid the occurrence of coking is an important issue to ensure safe and efficient production.

[0024] The utility model provides a new furnace structure for slowing down the coking of a waste incinerator, comprising a water-cooled wall and a high thermal conductivity corrosion-resistant castable layer arranged in sequence from the outside to the inside, wherein a sealed high-temperature molten salt layer is also arranged between the water-cooled wall and the high thermal conductivity corrosion-resistant castable layer. It also comprises a screen secondary air outlet device, which is used to form a layer of low-temperature oxidizing screen secondary air on the inner side of the high thermal conductivity corrosion-resistant castable layer. It also comprises a temperature sensor, which is arranged between the high thermal conductivity corrosion-resistant castable layer and the sealed high-temperature molten salt layer, and is used to monitor the surface temperature of the water-cooled wall. When the temperature sensor detects a temperature exceeding the coking set temperature, it automatically controls the screen secondary air outlet device to increase the secondary air volume and reduce the temperature at the furnace throat until the working condition returns to normal. The temperature sensor comprises a plurality of sensors at different positions. The high thermal conductivity corrosion-resistant castable layer is a silicon carbide castable layer.

[0025] In some embodiments, the sealed high-temperature molten salt layer is composed of one or more of nitrates, chlorides, and carbonates, and the sealed high-temperature molten salt layer is preferably a potassium carbonate-based high-temperature molten salt.

[0026] In some embodiments, the high thermal conductivity corrosion-resistant castable layer has a thickness of 95 mm, and the sealed high-temperature molten salt layer has a thickness of 75 mm.

[0027] The utility model also provides a garbage incinerator, comprising the above-mentioned novel furnace structure for slowing down the coking of the garbage incinerator.

[0028] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0029] like Figure 1The heat-resistant layer 1 is a SiC (silicon carbide) corrosion-resistant casting material with high thermal conductivity, which can significantly increase the heat absorption of the furnace radiation, and use its own high thermal conductivity to improve the wall temperature, thereby inhibiting coking; the high-temperature molten salt layer 2 is a high-temperature molten salt, generally referring to nitrates, chlorides, carbonates and their eutectics, with the advantages of "four highs and three lows", that is, high operating temperature, high thermal stability, high specific heat capacity, high convection heat transfer coefficient, low viscosity, low saturated vapor pressure, low price, and a certain phase change latent heat, and its heat transfer and heat storage properties are excellent. The temperature sensing system 3 consists of three temperature sensors. When any temperature sensor exceeds the coking set temperature, the secondary air volume is automatically increased to reduce the temperature at the throat of the furnace until the working condition returns to normal; in some embodiments, it can also be composed of other numbers of temperature sensors, depending on the actual position of the furnace where coking is prone to occur. The light pipe 4 is a carbon steel water-cooled wall pipe with a thickness of 5mm, which is used to hold a steam-water mixture and absorb external heat to transfer it to the internal flowing medium. In addition to the above measures, screen secondary air is also arranged to form a layer of low-temperature oxidizing screen secondary air on the surface of the furnace wall in the furnace throat area, thereby increasing the ash melting point, reducing the temperature of the furnace wall in this area, avoiding flames and ash particles from hitting the wall, and preventing slagging.

[0030] The effect of the utility model is explained below in conjunction with a specific application: In one embodiment, a domestic waste incinerator with a waste processing capacity of 400t / d and a calorific value of 7524kJ / kg of waste entering the furnace is taken as an example.

[0031] When 95mm (thickness from surface to fin) SiC corrosion-resistant castable is laid on the outside of the water-cooled wall, and the material used for the high-temperature molten salt layer is potassium carbonate-type high-temperature molten salt, its thickness is 75mm (the calorific value of the garbage entering the furnace is 7524kJ / kg, the primary air temperature is 180℃, the secondary air temperature is 20℃, and the air excess coefficient is 1.4), the maximum temperature in the furnace can be reduced from 1280℃ to 1165℃, and the temperature fluctuation time can be delayed by about 10 minutes. If the new incineration furnace is not used, when the furnace flue gas overheats, the flue gas temperature rises, and the heat cannot be absorbed by the water-cooled wall in time, causing the furnace to overheat. After exceeding the melting point of fly ash, the viscosity of fly ash increases, and it is easy to adhere to the furnace wall and repeatedly sinter to form coke blocks. After adopting the new anti-coking furnace, when the flue gas temperature rises, the excess heat is stored in the molten salt layer in time, and the flue gas temperature drops accordingly. At this temperature, the fly ash will not become molten, the viscosity is reduced, and it will not easily stick to the wall, and the boiler is not easy to coke.

[0032] In summary, the utility model provides a new furnace structure and a garbage incinerator for slowing down the coking of garbage incinerators. By combining high-temperature molten salt with good heat transfer and heat storage properties with high thermal conductivity corrosion-resistant casting materials, on the one hand, the cooling capacity of the water-cooled wall can be enhanced, and on the other hand, the adaptability of the water-cooled wall to temperature fluctuations caused by changes in working conditions can be enhanced, thereby reducing the temperature in the incinerator and reducing the occurrence of coking. The surface temperature of the water-cooled wall is monitored by a temperature sensor. When the temperature of the temperature sensor exceeds the coking set temperature, the temperature at the throat of the furnace is reduced by increasing the secondary air volume. A boundary screen secondary air is set in the throat area of ​​the furnace, so that a layer of low-temperature oxidizing screen secondary air is formed on the surface of the furnace wall in the throat area of ​​the furnace, thereby increasing the ash melting point, reducing the temperature of the furnace wall in this area, avoiding flames and ash particles from hitting the wall, and preventing slagging.

[0033] In the description of this specification, reference to the terms "one embodiment" and "example" means that the specific features, structures or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the utility model. In this specification, the schematic description of the above terms does not necessarily refer to the combination in a suitable manner in the relative embodiment or example.

[0034] It must be pointed out that the description of the above embodiments is not intended to be limiting but only to help understand the core idea of ​​the utility model. For ordinary technicians in this technical field, any improvements to the utility model and alternatives equivalent to the product, without departing from the principles of the utility model, also fall within the scope of protection of the claims of the utility model.

Claims

1. A new furnace structure for slowing down coking in a garbage incinerator, characterized in that: It comprises a water-cooled wall and a high thermal conductivity corrosion-resistant castable layer which are arranged in sequence from the outside to the inside, wherein a sealed high-temperature molten salt layer is also arranged between the water-cooled wall and the high thermal conductivity corrosion-resistant castable layer.

2. The novel furnace structure for slowing down coking in a garbage incinerator according to claim 1 is characterized in that: The high thermal conductivity corrosion-resistant castable layer is a silicon carbide castable layer.

3. The novel furnace structure for slowing down coking in a garbage incinerator according to claim 1 or 2 is characterized in that: It also includes a screen secondary air outlet device for forming a layer of low-temperature oxidizing screen secondary air inside the high thermal conductivity corrosion-resistant castable layer.

4. The novel furnace structure for slowing down coking in a garbage incinerator according to claim 3 is characterized in that: It also includes a temperature sensor, which is arranged between the high thermal conductivity corrosion-resistant castable layer and the sealed high-temperature molten salt layer, and is used to monitor the surface temperature of the water-cooled wall. When the temperature sensor detects a temperature exceeding the coking set temperature, the screen secondary air outlet device is automatically controlled to increase the secondary air volume and reduce the temperature at the furnace throat until the operating conditions return to normal.

5. The novel furnace structure for slowing down coking in a garbage incinerator according to claim 4 is characterized in that: The temperature sensor includes a plurality of sensors arranged at different positions.

6. The novel furnace structure for slowing down coking in a garbage incinerator according to claim 1 or 2, characterized in that: The sealed high-temperature molten salt layer is composed of one or more of nitrates, chlorides and carbonates.

7. The novel furnace structure for slowing down coking in a garbage incinerator according to claim 6 is characterized in that: The sealed high-temperature molten salt layer is a potassium carbonate-based high-temperature molten salt.

8. The novel furnace structure for slowing down coking in a garbage incinerator according to claim 7 is characterized in that: The thickness of the high thermal conductivity corrosion-resistant castable layer is 95 mm, and the thickness of the sealed high-temperature molten salt layer is 75 mm.

9. The novel furnace structure for slowing down coking in a garbage incinerator according to claim 1 or 2, characterized in that: The water-cooled wall comprises a wall and a light pipe arranged in the wall, and the light pipe is made of carbon steel.

10. A garbage incinerator, characterized in that: It comprises a novel furnace structure for slowing down coking in a waste incinerator as described in any one of claims 1 to 9.

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