A large-capacity and high-load dual-furnace waste incineration device

Abstract

The present invention discloses a large-capacity and high-load dual-furnace waste incineration device, which includes a primary air system, a secondary air system, a feeding system, a furnace, a flue and an ash discharge outlet. The left and right sides of the furnace are respectively connected to the front wall and the rear wall of the feeding system. The top of the furnace is connected to the flue through a flue inlet, and the bottom of the furnace is connected to the ash discharge outlet. The primary air system is connected to the bottom of the furnace, and the secondary air system is connected to the top of the furnace. The furnace includes an arch wall, side walls, a drying grate and a burnout grate. The arch wall is arranged in the upper part of the furnace, the side walls are arranged on the left and right sides of the furnace, and the drying grate and the burnout grate are arranged at the bottom of the furnace, jointly forming a combustion space of the furnace. The large-capacity and high-load dual-furnace waste incineration boiler of the present invention has a large waste treatment capacity, a high unit heat load and flue gas temperature of the furnace, a high system thermal efficiency, and can effectively reduce the emission of pollutants such as dioxins.

Description

Technical Field

[0001] The present invention relates to a waste incineration device, and particularly to a double-furnace waste incineration device with a large capacity and high load, belonging to the technical field of boilers. Background Art

[0002] Waste incineration power generation technology can achieve the reduction, harmlessness, and resource utilization of waste. With the continuous development of this technology, people's attention to waste incineration technology focuses on three aspects: waste treatment capacity, energy recovery rate, and pollutant emissions. The optimization and improvement of the above three aspects are all based on a good furnace structure and an optimized combustion control strategy. At present, the waste treatment capacity of waste incineration has reached a scale of ~1000t / D, and the width of the incinerator has reached 12m. Continuing to increase the width of the furnace to improve the waste treatment capacity poses difficulties for the design of a single furnace structure and the layout of subsequent heating surfaces. The increase in the furnace width does not significantly increase the heat load per unit volume in the furnace, does not bring an increase in characteristic values such as the main steam parameters of the unit, and cannot improve the thermal efficiency of the unit and the heat transfer efficiency in the furnace. Moreover, the diversity of waste in terms of composition and calorific value is obvious, and the increase in the furnace width will exacerbate the thermal deviation of the flue gas and heating surfaces in the furnace.

[0003] Therefore, designing an incineration device with a large capacity and high load has an important promoting effect on waste treatment and energy recovery. Summary of the Invention

[0004] The technical problem to be solved by the present invention is: to provide a double-furnace waste incineration grate boiler with a large capacity and high load, and to improve the combustion speed of waste fuel in the furnace and the heat load per unit volume through a new furnace structure and combustion organization method to achieve the purpose of large capacity and high load.

[0005] To solve the above technical problem, the technical solution of the present invention is to provide a double-furnace waste incineration device with a large capacity and high load, including a primary air system, a secondary air system, a feeding system, a furnace, a flue, and an ash discharge outlet, characterized in that: the waste incineration device is symmetrically arranged along the depth direction of the furnace, and is of a double-furnace structure, forming two symmetrically distributed combustion centers on the grate at the bottom of the furnace. The left and right sides of the furnace are respectively connected to the front wall and the rear wall of the feeding system. The top of the furnace is connected to the flue through a flue inlet, and the bottom of the furnace is connected to the ash discharge outlet. The primary air system is connected to the bottom of the furnace, and the secondary air system is connected to the top of the furnace. The furnace includes an arch wall, side walls, a drying grate, and a burnout grate; the arch wall is arranged at the upper part of the furnace, the side walls are arranged on the left and right sides of the furnace, and the drying grate and the burnout grate are arranged at the bottom of the furnace, jointly forming a combustion space of the furnace.

[0006] Preferably, the furnace is enclosed by a drying grate, a burnout grate, a slag inlet at the slag outlet, side walls, arch walls, and a flue inlet, and is symmetrically arranged. The furnace, flue, and slag outlet are coaxially arranged. The drying grate and the burnout grate are symmetrically arranged on both sides of the bottom of the furnace. The drying grate is arranged above the burnout grate and is inclinedly connected. The drying grate and the burnout grate respectively correspond to two independent processes of pyrolysis and combustion reactions of the garbage in the material layer.

[0007] Preferably, the arch walls include a front arch wall and a rear arch wall that can directly reflect the heat released by garbage combustion to the material layer of the grate below in the form of radiation. The front arch wall is located above the drying section and the burnout section near the front wall. The rear arch wall is located above the drying section and the burnout section near the rear wall.

[0008] Preferably, the primary air system is provided with a primary air inlet one connected to the drying grate, a primary air inlet two connected to the burnout grate, and a primary air inlet three connected to the slag outlet. The oxidants passed through by the primary air inlet one, the primary air inlet two, and the primary air inlet three are different.

[0009] Preferably, the oxidant passed through by the primary air inlet one is a mixture of high-temperature circulating flue gas and high-temperature preheated air. The temperature range of the mixture is 350°C - 650°C, the air rate is 25% - 35%, the oxygen concentration in the mixture is 10% - 15%, and the source of the mixture is the flue gas in the high-temperature flue and the high-temperature air at the outlet of the air preheater. The oxidant passed through by the primary air inlet two is an oxygen-enriched oxidant, and the source is the high-temperature air at the outlet of the air preheater and high-concentration oxygen, where the oxygen concentration is 25% - 35%, the air rate is 55% - 65%, and the temperature range is 150°C - 350°C. The oxidant passed through by the primary air inlet three is primary preheated air, which comes from the outlet of the air preheater, the air rate is 5% - 10%, and the temperature range is 150°C - 250°C.

[0010] Preferably, the secondary air nozzles of the secondary air system are located at the outlet of the furnace. The secondary air nozzles are arranged in a multi-layer structure. The secondary air nozzle at the bottom layer is the secondary air nozzle two, which is arranged on the arch wall. The secondary air nozzles outside the bottom layer are the secondary air nozzles one, which are all arranged on the vertical flue, and the number of layers of the secondary air nozzles one arranged on the flue is not less than 3 layers.

[0011] Preferably, the flue is located directly above the slag outlet, and its vertical projection will cover all of the slag outlet and part of the burnout grate, and the covered area of the vertical projection is not greater than 1 / 4 of the area of the burnout grate.

[0012] Preferably, the slag outlet is of a reduced orifice structure, and a primary air nozzle and a baffle structure are provided on the reduced orifice structure.

[0013] Preferably, the arch wall, side wall and flue are all structured in the form of water-cooled walls, without air-cooled walls, and the fire-facing surface is lined with SiC refractory materials.

[0014] Preferably, the flue gas temperature above the drying grate is 900°C - 1100°C, the flue gas temperature above the burnout grate is 1200°C - 1400°C, and the flue gas temperature at the ash discharge outlet is 250 - 350°C.

[0015] Preferably, the flue is surrounded by membrane water-cooled walls, the fire-facing side is lined with SiC refractory materials, and is connected to the water-cooled wall outlets of the arch wall and side wall in the form of headers.

[0016] Preferably, the secondary air enters the furnace through secondary air nozzles, and the secondary air nozzles are arranged in multiple rows along the furnace width direction, and the source is conventional air.

[0017] Preferably, the CaO powder enters through the secondary air nozzles arranged on the arch wall, enters the furnace under the action of gravity and the entrainment of the fluid, and reacts with the acidic gases in the flue gas.

[0018] Preferably, the source of the high-temperature flue gas is selected from the flue position without heating surfaces, and the selected circulating flue gas fan adopts variable frequency design to adjust the flow rate and speed of the circulating flue gas.

[0019] The features of the present invention are as follows:

[0020] 1. The large-capacity and high-load double-furnace waste incineration boiler has a large waste treatment capacity, high unit heat load and flue gas temperature in the furnace, high system thermal efficiency, and can effectively reduce the emissions of pollutants such as dioxins. The increase in the unit heat load of the furnace makes the furnace structure more compact, making it possible to adopt high parameters for the subsequent evaporation system.

[0021] 2. Compared with the existing single-furnace combustion structure, the flow field and temperature field distribution of the double-furnace are more uniform after symmetric arrangement, especially the flow field and temperature field in the outlet flue are more uniform.

[0022] 3. The grate is divided into two parts: drying and burnout, and independent control strategies are adopted respectively. Different oxidant combinations are used in different stages, and the temperature and flow rate of the oxidant are adjusted according to the calorific value of the fuel, effectively regulating and controlling the parameters of the high-temperature flue gas entering, and improving the adaptability of the unit to load changes, combustion instability and fuel diversity.

[0023] 4. The design of the ash discharge outlet can well ensure and maintain the negative pressure in the furnace, reducing the problem of large fluctuations in the furnace pressure caused by slag discharge. Description of the Drawings

[0024] Figure 1 It is a schematic diagram of a large-capacity and high-load double-furnace waste incineration device;

[0025] Figure 2 It is a top-down schematic diagram of the furnace;

[0026] Figure 3 It is a layout sketch of the secondary air nozzles;

[0027] Figure 4 It is a schematic diagram of the structure of the ash discharge outlet. Specific implementation manners

[0028] To make the present invention more obvious and understandable, preferred embodiments are hereby described in detail in conjunction with the accompanying drawings as follows.

[0029] Such as Figures 1 to 4As shown in the figure, a large-capacity and high-load double-furnace waste incineration device includes a primary air system 100, a secondary air system 200, a feeding system 300, a furnace 400, a flue 500, and an ash discharge outlet 600. The waste incineration device of the present invention is symmetrically arranged along the depth direction of the furnace 400, and is of a double-furnace structure, forming two symmetrically distributed combustion centers on the grate at the bottom of the furnace 400. The left and right sides of the furnace 400 are respectively connected to the front wall 301 and the rear wall 302 of the feeding system 300 up and down. The top of the furnace 400 is connected to the flue 500 through a flue inlet 501. The bottom of the furnace 400 is connected to the ash discharge outlet 600. The primary air system 100 is connected to the bottom of the furnace 400, and the secondary air system 200 is connected to the top of the furnace 400. The furnace 400 includes an arch wall, side walls 402, a drying grate 410, and a burnout grate 420. The arch wall is arranged at the upper part of the furnace 400, the side walls 402 are arranged on the left and right sides of the furnace 400, and the drying grate 410 and the burnout grate 420 are arranged at the bottom of the furnace 400, jointly forming a combustion space of a furnace. The furnace 400 is surrounded by the drying grate 410, the burnout grate 420, the ash inlet 601 of the ash discharge outlet 600, the side walls 402, the arch wall, and the flue inlet 501, and is symmetrically arranged. The furnace 400, the flue 500, and the ash discharge outlet 600 are coaxially arranged. The drying grate 410 and the burnout grate 420 are both symmetrically arranged on both sides of the bottom of the furnace 400. The drying grate 410 is arranged above the burnout grate 420, and the two are inclined and connected. The drying grate 410 and the burnout grate 420 respectively correspond to two independent processes of pyrolysis and combustion reactions of the waste in the material layer. The arch wall includes a front arch wall 4011 and a rear arch wall 4012. The front arch wall 4011 is located above the drying section 4101 and the combustion burnout section 4201 close to the front wall 301, and can directly reflect the heat released by waste combustion to the material layer on the grate below in the form of radiation. The rear arch wall 4012 is located above the drying section 4102 and the combustion burnout section 4202 close to the rear wall 302, and can directly reflect the heat released by waste combustion to the material layer on the grate below. The range of the included angle α is 15° - 35°. The primary air system 100 is provided with a primary air inlet one 411 connected to the drying grate 410, a primary air inlet two 421 connected to the burnout grate 420, and a primary air inlet three 602 connected to the ash discharge outlet 600. The primary air system 100 adopts different control strategies for different air inlets and uses oxidants with different parameters. The oxidant passing through the primary air inlet one 411 is a mixture of high-temperature circulating flue gas and high-temperature preheated air. The temperature range of the mixture is 350°C - 650°C, the air rate is 25% - 35%, the oxygen concentration in the mixture is 10% - 15%, and the source of the mixture is the flue gas in the high-temperature flue and the high-temperature air at the outlet of the air preheater.The oxidant passing through the primary air inlet two 421 is the oxygen-enriched oxidant 101, which is sourced from the high-temperature air and high-concentration oxygen at the outlet of the air preheater. The oxygen concentration in the mixed gas is 25% - 35%, the air rate is 55% - 65%, and the temperature range is 150°C - 350°C. The oxidant passing through the primary air inlet three 602 is the conventional primary preheated air, which is sourced from the outlet of the air preheater. The air rate is 5% - 10%, and the temperature range is 150°C - 250°C. The secondary air nozzles of the secondary air system 200 are located at the outlet of the furnace 400 and are arranged in multiple layers. The secondary air nozzle at the bottom layer is the secondary air nozzle two 202, which is arranged on the arch wall and is used to adjust the flue gas temperature and flue gas components in the furnace 400 to prevent problems such as high-temperature coking. The other layers of secondary air nozzles are the secondary air nozzle one 201, which is arranged on the vertical flue, and the number of layers of the arranged secondary air nozzle one 201 is not less than 3 layers. The flue 500 includes a flue inlet 501, a flue water wall 502, and a flue outlet 503. The flue 500 is located directly above the ash discharge outlet 600, and its vertical projection will cover all of the ash discharge outlet 600 and part of the burned-out grate, and the covered area of the vertical projection is not greater than 1 / 4 of the area of the burned-out grate 420. The ash discharge outlet 600 adopts a reduced cross-section structure 603, and a primary air nozzle 611 and a baffle structure 610 are provided on the reduced cross-section structure 603. The inclination angle β of the reduced cross-section structure 603 ranges from 30° to 50°.

[0030] A large-capacity and high-load double-furnace waste incineration boiler of the present invention includes a primary air system 100, a secondary air system 200, a fuel feeding system 300, a furnace 400, a segmented incinerator grate, a flue 500, and an ash discharge outlet 600. Municipal solid waste enters the furnace 400 through the feeding system 300 and is dried and pyrolyzed by the pusher and the drying grate 410 of the grate. As the pyrolysis is completed, the waste enters the burned-out grate 420 for combustion reaction until the combustion process ends, and then enters the ash inlet 601 under the operation of the grate. The flue gas generated after the waste combustion rises along the structure of the furnace 400 and enters the flue 500 at the outlet of the furnace 400 and is discharged from the flue outlet 503. Both the furnace 400 and the flue 500 are surrounded by a water wall structure. The flue inlet 501 is connected to the outlet of the furnace 400, and its inner wall is coated with refractory materials to ensure the safety of the water wall.

[0031] The entire combustion process is divided into two independent processes: drying and pyrolysis, and combustion and burnout, with different oxidants and control strategies adopted respectively. The primary air system 100 is connected to the primary air mixer 103 and the primary air mixer 104. The oxidants required during the combustion process enter different grates through the primary air inlets provided in the slag hopper. Among them, to enhance the garbage drying process of the drying grate 410, the drying grate 410 utilizes the combined action of high-temperature circulating flue gas convection and arch wall radiation heat transfer. High-temperature flue gas recirculation can also increase the concentration of CO2 in the furnace 400, adjust the oxygen concentration of the flue gas in the furnace 400, achieve staged combustion, and reduce the generation amount of nitrogen oxides. The source of the oxidant in the drying section is the mixed gas of high-temperature circulating flue gas and primary air from the air preheater. The oxygen concentration in the mixed gas is 10% - 15%, and the range of the high-temperature flue gas is 450°C - 650°C. The main process of combustion occurs in the combustion and burnout section. The oxidant passing through the second primary air inlet 421 is the oxygen-enriched oxidant 101. The oxygen concentration in the mixed gas is 25% - 35%, and the temperature range is 150°C - 350°C. The increase in oxygen concentration will significantly enhance the combustion intensity, increase the combustion temperature and the heat load in the furnace. The increase in oxygen concentration will also significantly reduce the combustion time and increase the garbage treatment capacity. The burned garbage enters the ash discharge outlet 600 under the action of the grate, and the discharge amount of the ash is controlled by the baffle structure 610. The primary air entering through the third primary air inlet 602 can improve the fluidity of the ash while adjusting the flow field and temperature field distribution of the flue gas in the center of the furnace 400. The baffle structure 610 can effectively improve the sealing performance of the furnace 400, reduce the strong impact on the furnace 400 pressure and flue gas components caused by a large amount of steam generated after the ash enters the slag pusher, and solve the problem of large pressure fluctuations in the furnace 400. At the same time, the increase in the oxygen concentration in the primary air of the drying grate 410 will strengthen the combustion process, increase the temperature at the combustion center, reduce the hydrocarbons (CmHn) generated due to insufficient oxygen, incomplete mixing, or low temperature, etc., and completely decompose them into carbon dioxide and water, reducing their combination with the chlorides in the garbage to form dioxins or their precursors, so as to achieve the purpose of controlling the generation of dioxins during the combustion process.

[0032] In addition to using high-temperature circulating flue gas and oxygen concentration to control the combustion temperature at the center of the furnace, the radiation heat transfer is strengthened through the arch wall to enhance the drying and combustion processes of the fuel and improve the burnout rate.

[0033] The secondary air system 200 is connected to the secondary air box 204. The CaO powder 203 enters the furnace 400 through the primary secondary air nozzles one 201 and two 202 arranged on the arch wall, enters the furnace area of the furnace 400, forms a "W"-shaped movement trajectory, and enters the subsequent process from the outlet of the flue 500. The addition of the CaO powder 203 can control the content of acidic gases in the flue gas during combustion, preventing the water-cooled wall and subsequent high-temperature heating surfaces from being corroded by acidic gases. It provides the possibility for setting subsequent high-temperature heating surfaces such as superheaters and reheaters and improving the steam parameters of the system.

[0034] The fan used in the circulating flue gas system 102 adopts a variable-frequency design, which can adjust the flow rate and speed of the circulating flue gas.

Claims

1. A dual-furnace waste incineration device with a large capacity and high load, comprising a primary air system (100), a secondary air system (200), a feeding system (300), a furnace (400), a flue (500) and an ash outlet (600), characterized in that: The described waste incineration device is symmetrically arranged in the depth direction of the furnace chamber (400), and is a double furnace chamber structure. Two symmetrically distributed combustion centers are formed on the grate at the bottom of the furnace chamber (400). The left and right sides of the furnace chamber (400) are respectively connected to the front wall (301) and the rear wall (302) of the feeding system (300). The top of the furnace chamber (400) is connected to the flue (500) through the flue inlet (501). The bottom of the furnace chamber (400) is connected to the ash discharge outlet (600). The primary air system (100) is connected to the bottom of the furnace chamber (400), and the secondary air system (200) is connected to the top of the furnace chamber (400). The described furnace chamber (400) includes an arch wall, side walls (402), a drying grate (410), and a burnout grate (420); the arch wall is arranged in the upper part of the furnace chamber (400), the side walls (402) are arranged on the left and right sides of the furnace chamber (400), and the drying grate (410) and the burnout grate (420) are arranged at the bottom of the furnace chamber (400), jointly forming a combustion space of the furnace chamber (400). The described arch wall includes a front arch wall (4011) and a rear arch wall (4012) that can directly reflect the heat released by waste combustion in a radiation form onto the material layer of the grate below. The front arch wall (4011) is located above the drying section (4101) and the burnout section (4201) near the front wall (301); the described rear arch wall (4012) is located above the drying section (4102) and the burnout section (4202) near the rear wall (302). The described primary air system (100) is provided with a primary air inlet one (411) connected to the drying grate (410), the primary air system (100) is provided with a primary air inlet two (421) connected to the burnout grate (420), and the primary air system (100) is provided with a primary air inlet three (602) connected to the ash discharge outlet (600); the oxidants passed through by the primary air inlet one (411), the primary air inlet two (421), and the primary air inlet three (602) are different; the oxidant passed through by the primary air inlet three (602) is primary preheated air, which comes from the outlet of the air preheater. The described ash discharge outlet (600) is of a reduced diameter structure (603), and a primary air nozzle (611) and a baffle structure (610) are arranged on the reduced diameter structure (603). The discharge amount of ash is controlled through the baffle structure (610) to reduce the strong impact on the pressure of the furnace chamber (400) and the flue gas components caused by a large amount of steam generated after the ash enters the slag pusher. The oxidant passing through the primary air inlet one (411) is a mixture of high-temperature recycled flue gas and high-temperature preheated air. The temperature range of the mixture is 350°C - 650°C, the air rate is 25% - 35%, the oxygen concentration in the mixture is 10% - 15%, and the source of the mixture is the flue gas in the high-temperature flue and the high-temperature air at the outlet of the air preheater. The oxidant passing through the primary air inlet two (421) is an oxygen-enriched oxidant, and the source is the high-temperature air at the outlet of the air preheater and high-concentration oxygen, where the oxygen concentration is 25% - 35%, the air rate is 55% - 65%, and the temperature range is 150°C - 350°C. The oxidant passing through the primary air inlet three (602) is primary preheated air, which comes from the outlet of the air preheater, the air rate is 5% - 10%, and the temperature range is 150°C - 250°C.

2. The large-capacity and high-load dual-furnace waste incineration device according to claim 1, characterized in that, The described furnace (400) is enclosed by a drying grate (410), a burnout grate (420), an ash inlet (601) of the ash outlet (600), side walls (402), arch walls, and a flue inlet (501), and is symmetrically arranged. The furnace (400), the flue (500), and the ash outlet (600) are coaxially arranged. The drying grate (410) and the burnout grate (420) are symmetrically arranged on both sides of the bottom of the furnace (400). The described drying grate (410) is arranged above the burnout grate (420) and is inclined and connected.

3. A large-capacity and high-load dual-furnace waste incineration device according to claim 1, characterized in that, The secondary air nozzles of the described secondary air system (200) are located at the outlet of the furnace (400). The secondary air nozzles are arranged in a multi-layer structure. The secondary air nozzle at the bottom layer is the secondary air nozzle two (202), which is arranged on the arch wall. The secondary air nozzles other than the bottom layer are the secondary air nozzles one (201), which are all arranged on the vertical flue (500), and the number of layers of the secondary air nozzles one (201) arranged on the flue (500) is not less than 3 layers.

4. A large-capacity and high-load dual-furnace waste incineration device according to claim 1, characterized in that, The described flue (500) is directly above the ash outlet (600). Its vertical projection will cover all of the ash outlet (600) and part of the burnout grate, and the covered area of the vertical projection is not greater than 1 / 4 of the area of the burnout grate (420).

5. A large-capacity and high-load dual-furnace waste incineration device according to claim 1, characterized in that, The described arch walls, side walls (402), and flues (500) all adopt a water-cooled wall form of structure.

6. A large-capacity and high-load double-furnace waste incineration device according to claim 1, characterized in that, The flue gas temperature above the drying grate (410) is 900°C - 1100°C, the flue gas temperature above the burnout grate (420) is 1200°C - 1400°C, and the flue gas temperature at the ash outlet (600) is 250 - 350°C.

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