Sintering flue gas recycling system

Abstract

The utility model provides a kind of sintering flue gas recycling system, including hearth, cyclone separator and tail flue, hearth has primary air inlet, secondary air inlet, coal feeding port, desulfurizer feed port, discharge port and return material inlet, primary air inlet is connected air fan, secondary air inlet is connected sintering machine head flue gas feeding device, the return material air port of cyclone separator is located below the return valve of cyclone separator, return material air port is connected air fan, cyclone separator is connected tail flue.The utility model is introduced into hearth combustion by sintering flue gas, latent heat and chemical energy of sintering flue gas are used to reduce boiler fuel consumption, realize the waste heat recovery of sintering flue gas and pollutant collaborative treatment.Through the return material air port being set in cyclone separator and being connected with air fan, it can prevent bed material accumulation blockage at return valve.

Description

Technical Field

[0001] This utility model relates to the field of flue gas treatment and energy recovery technology, and in particular to a sintering flue gas recovery and utilization system. Background Technology

[0002] Under normal circumstances, producing one ton of sintered ore generates 4000-6000 Nm³ of nitrogen oxides. 3 Sintering flue gas is characterized by its complex composition, wide temperature range (120-180℃), high oxygen content (above 13%), and high moisture content. It contains various pollutants such as SO2, NOx, PM, and dioxins. Notably, it also contains approximately 5000 ppm CO, which can be used as a low-concentration fuel to recover its combustion heat. Simple calculations show that for every ton of sinter produced, the sintering flue gas carries away 0.72 GJ of waste heat, accounting for about 50% of the total energy input of the sintering process. In particular, the waste heat from the sintering flue gas accounts for as much as 19%-35% of the total energy consumption. Therefore, simultaneously treating multiple pollutants in the sintering flue gas and recovering and utilizing the aforementioned waste heat and a certain concentration of combustible components' combustion heat is of great significance for reducing the total energy consumption of the steel production process.

[0003] Existing end-of-pipe treatment technologies for sintering flue gas mostly employ a series connection of devices such as SCR denitrification, SNCR denitrification, semi-dry desulfurization, wet desulfurization, bag filter dust collection, and activated carbon adsorption to remove pollutants from the sintering flue gas. If an additional step is added to remove CO from the sintering flue gas and recover waste heat, additional heat input is often required. Some existing technologies combine sintering flue gas pollutant treatment with power generation, using boiler combustion to treat the sintering flue gas. However, these technologies do not consider problems such as equipment blockage and pipe wear caused by the complex composition of pollutants in sintering flue gas, nor do they pay attention to the setting of boiler operating parameters, resulting in insufficient removal of pollutants from the sintering flue gas. Utility Model Content

[0004] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, embodiments of this invention provide a sintering flue gas recovery and utilization system, which can effectively recover and utilize sintering flue gas.

[0005] This utility model embodiment proposes a sintering flue gas recovery and utilization system, including: a furnace, a cyclone separator and a tail flue. The furnace has a primary air inlet, a secondary air inlet, a coal feed inlet, a desulfurizing agent feed inlet, a discharge outlet and a return material inlet. The primary air inlet is located at the bottom of the furnace and is connected to an air fan through a primary air inlet pipe. The secondary air inlet is located above the primary air inlet and is connected to the flue gas feeding device at the head of the sintering machine through a secondary air inlet pipe.

[0006] The cyclone separator has a feed inlet, an air outlet, a return outlet, and a return air inlet. The feed inlet of the cyclone separator is connected to the discharge outlet of the furnace through a discharge pipe. The return outlet of the cyclone separator is connected to the return inlet of the furnace through a return pipe. The return air inlet of the cyclone separator is located below the return valve of the cyclone separator and is connected to the air fan through a primary air inlet pipe.

[0007] The tail flue has an air inlet and an air outlet. The air inlet of the tail flue is connected to the air outlet of the cyclone separator, and the air outlet of the tail flue is connected to the chimney.

[0008] In some embodiments, the interior of the tail flue is provided with a secondary air preheater and a primary air preheater. The secondary air inlet pipe passes through the secondary air preheater to preheat the secondary air, and the primary air inlet pipe passes through the primary air preheater to preheat the primary air.

[0009] In some embodiments, a superheater, an economizer, and an SCR reactor are provided inside the tail flue upstream of the secondary air preheater and the primary air preheater. The superheater, economizer, SCR reactor, secondary air preheater, and primary air preheater are arranged sequentially from the air inlet to the air outlet of the tail flue.

[0010] In some embodiments, the secondary air inlet duct is connected to an air bypass.

[0011] In some embodiments, an induced draft fan and a sintering flue gas dust removal device are connected to the secondary air inlet duct.

[0012] In some embodiments, the discharge pipe has a burnout air inlet and an SNCR ammonia injection port.

[0013] In some embodiments, a dust collector and a desulfurization tower are connected between the exhaust outlet of the tail flue and the chimney.

[0014] In some embodiments, an air distribution plate is provided above the primary air inlet of the furnace, and multiple air outlets are evenly distributed on the air distribution plate, with the secondary air inlet located above the air distribution plate.

[0015] In some embodiments, each air vent is connected to a vent cap.

[0016] In some embodiments, the outer wall of the furnace and the outer wall of the cyclone separator are both covered with a heat insulation layer. Attached Figure Description

[0017] The above and / or additional aspects and advantages of this invention will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings.

[0018] in:

[0019] Figure 1This is a schematic diagram of the sintering flue gas recovery and utilization system in an embodiment of this utility model;

[0020] Figure label:

[0021] 1. Circulating fluidized bed boiler; 2. Dust collector; 3. Desulfurization tower; 4. Chimney; 5. Furnace; 6. Cyclone separator; 7. Return valve; 8. Tail flue; 9. Superheater; 10. Economizer; 11. SCR reactor; 12. Secondary air preheater; 13. Primary air preheater; 14. Air fan; 15. Sintering machine head flue gas inlet device; 16. Secondary air inlet; 17. Primary air inlet; 18. Return air outlet; 19. Coal feed inlet; 20. Desulfurizing agent inlet; 21. Combustion air inlet; 22. SNCR ammonia injection port; 23. Induced draft fan; 24. Sintering flue gas dust removal device. Detailed Implementation

[0022] The embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0023] The sintering flue gas recovery and utilization system of this utility model is described below with reference to the accompanying drawings.

[0024] like Figure 1 As shown in the figure, this utility model embodiment proposes a sintering flue gas recovery and utilization system, including: a furnace 5, a cyclone separator 6 and a tail flue 8. The furnace 5 has a primary air inlet 17, a secondary air inlet 16, a coal feed inlet 19, a desulfurizing agent feed inlet 20, a discharge outlet and a return material inlet. The primary air inlet 17 is located at the bottom of the furnace 5 and is connected to an air fan 14 through a primary air inlet pipe. The secondary air inlet 16 is located above the primary air inlet 17 and is connected to a sintering machine head flue gas feeding device 15 through a secondary air inlet pipe.

[0025] Cyclone separator 6 has a feed inlet, an air outlet, a return outlet, and a return air inlet 18. The feed inlet of cyclone separator 6 is connected to the discharge outlet of furnace 5 through a discharge pipe. The return outlet of cyclone separator 6 is connected to the return inlet of furnace 5 through a return pipe. The return air inlet 18 of cyclone separator 6 is located below the return valve 7 of cyclone separator 6. The return air inlet 18 of cyclone separator 6 is connected to the air fan 14 through a primary air inlet pipe.

[0026] The tail flue 8 has an air inlet and an air outlet. The air inlet of the tail flue 8 is connected to the air outlet of the cyclone separator 6, and the air outlet of the tail flue 8 is connected to the chimney 4.

[0027] The system of this utility model embodiment takes a circulating fluidized bed boiler 1 as the main body, and integrates a furnace 5, a cyclone separator 6 and a tail flue 8 to form a closed-loop circulating combustion system.

[0028] This embodiment of the invention introduces sintering flue gas into the furnace 5 for combustion, utilizing the sensible heat and chemical energy (CO combustion exothermics) of the sintering flue gas to reduce boiler fuel consumption, thereby achieving waste heat recovery and co-treatment of pollutants from the sintering flue gas.

[0029] It should be noted that CO in sintering flue gas is a combustible gas that reacts with oxygen in the circulating fluidized bed. Since the temperature of the fluidized bed reactor is high enough for CO oxidation and the gas residence time is long, the reaction of CO with O2 releases heat to the boiler, which also saves some of the boiler's heat input and further saves fuel. This achieves the removal of pollutant CO from sintering flue gas and the utilization of combustion heat.

[0030] This embodiment of the invention achieves in-furnace desulfurization by adding a desulfurizing agent into the furnace chamber 5, thereby improving desulfurization efficiency and saving the cost of subsequent tail gas desulfurization.

[0031] In this embodiment of the invention, the particulate matter in the flue gas is removed by passing the flue gas from the tail flue 8 through the dust collector 2 before it is discharged into the atmosphere.

[0032] This embodiment of the utility model, by setting a return air inlet 18 in the cyclone separator 6 and connecting it to the air fan 14 through the primary air inlet pipe, can promote the discharge of bed material at the return valve 7 into the furnace 5, and prevent the bed material at the return valve 7 from accumulating and blocking.

[0033] Furthermore, the primary air inlet 17 and the secondary air inlet 16 are located at different positions. The primary air inlet 17 is located at the bottom of the furnace 5, and the secondary air inlet 16 is located on the side of the furnace 5 and above the primary air inlet 17. This separation of primary and secondary air allows the use of air for primary air and sintering flue gas for secondary air to avoid the problem of primary air duct blockage caused by sintering flue gas completely replacing air entering the furnace 5, which would prevent both primary and secondary air from entering the furnace 5 smoothly. It should be noted that sintering flue gas contains alkali metals (K / Na) and particulate matter, which can easily clog the duct area.

[0034] Furthermore, the proportion of sintering flue gas in furnace 5 is 40%-60%. The remainder is air, ensuring complete combustion of fuel in furnace 5.

[0035] Furthermore, the coal feed inlet 19 and the desulfurizing agent feed inlet 20 are located on the left side of the furnace 5.

[0036] In some embodiments, the interior of the tail flue 8 is provided with a secondary air preheater 12 and a primary air preheater 13. The secondary air inlet pipe passes through the secondary air preheater 12 to preheat the secondary air, and the primary air inlet pipe passes through the primary air preheater 13 to preheat the primary air.

[0037] Because the temperature of sintering flue gas is higher than that of cold air, within the range of 120 to 180°C, less heat is required to preheat the sintering flue gas to the same temperature, saving boiler fuel consumption and realizing the recovery and utilization of waste heat from sintering flue gas.

[0038] In some embodiments, a superheater 9, an economizer 10, and an SCR reactor 11 are provided inside the tail flue 8 upstream of the secondary air preheater 12 and the primary air preheater 13. The superheater 9, economizer 10, SCR reactor 11, secondary air preheater 12, and primary air preheater 13 are arranged sequentially from the air inlet to the air outlet of the tail flue 8.

[0039] Superheater 9 and economizer 10 absorb the heat from the flue gas after cyclone separation for power generation or heating. SCR reactor 11 is used for further denitrification of the flue gas. As the flue gas temperature in the tail flue duct 8 decreases, a secondary air preheater 12 and a primary air preheater 13 are further installed to heat the sintering flue gas introduced from the sintering machine and the air introduced by the induced draft fan 23, making full use of the waste heat of the flue gas. This is of great significance for optimizing the overall system energy structure and reducing the total energy consumption of the steel production process.

[0040] In some embodiments, the secondary air inlet duct is connected to an air bypass. When the sintering machine is under maintenance or the source of sintering flue gas is cut off, the source of secondary air is switched to air to ensure the continuity and reliability of the system.

[0041] Furthermore, the gas source can be switched by installing a reversing valve on the pipeline upstream of the induced draft fan 23. The two inlets of the reversing valve are for air and sintering flue gas, respectively. The switching method is simple and quick, further improving the continuity and reliability of the system.

[0042] In some embodiments, an induced draft fan 23 and a sintering flue gas dust removal device 24 are connected to the secondary air inlet duct.

[0043] Since the sintering flue gas is sent into the furnace 5 through the induced draft fan 23, a sintering flue gas dust removal device 24 is installed in front of the induced draft fan 23 to remove dust, which can alleviate the problem of severe wear of the induced draft fan 23 caused by excessive particulate matter content in the sintering flue gas.

[0044] In some embodiments, the discharge pipe has a burnout air inlet 21 and an SNCR ammonia injection port 22. The burnout air inlet 21 is used to perform supplementary combustion on the discharged flue gas, burning off the CO generated during combustion and the original CO in the sintering flue gas. The SNCR ammonia injection port 22 is used to achieve SNCR reaction denitrification at high temperature, further reducing nitrogen oxide emissions.

[0045] In some embodiments, a dust collector 2 and a desulfurization tower 3 are connected between the outlet of the tail flue 8 and the chimney 4. By installing the dust collector 2 and the desulfurization tower 3 before the chimney 4, dust and sulfides in the flue gas can be further removed, ensuring ultra-low SO2 emissions from the outlet flue gas.

[0046] In some embodiments, an air distribution plate is provided above the primary air inlet 17 of the furnace 5, and multiple air outlets are evenly distributed on the air distribution plate, with the secondary air inlet 16 located above the air distribution plate.

[0047] In some embodiments, each air vent is connected to a vent cap.

[0048] In some embodiments, the outer wall of the furnace 5 and the outer wall of the cyclone separator 6 are both covered with a heat insulation layer.

[0049] The method of using the system according to this embodiment of the utility model includes the following steps: Coal and desulfurizing agent are introduced into the furnace 5 of the circulating fluidized bed boiler 1, and primary air and secondary air are introduced. The primary air is sourced from air, and the secondary air is sourced from sintering flue gas. The flue gas formed after combustion in the furnace 5 is separated into a cyclone separator 6 after supplementary combustion and SNCR denitrification. The separated flue gas enters the tail flue 8, and the separated bed material is returned to the furnace 5. A small portion of the primary air is extracted and blown into the return valve 7 of the cyclone separator 6 to prevent bed material from accumulating and clogging the return valve 7. The flue gas in the tail flue 8 is discharged into the atmosphere after SCR denitrification, secondary air heat exchange, primary air heat exchange, desulfurization, and dust removal.

[0050] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0051] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this utility model, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0052] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0053] In this utility model, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0054] In this utility model, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of this utility model. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0055] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A sintering flue gas recovery and utilization system, characterized in that, include: The furnace has a primary air inlet, a secondary air inlet, a coal feed inlet, a desulfurizing agent feed inlet, a discharge outlet, and a return material inlet. The primary air inlet is located at the bottom of the furnace and is connected to an air fan through a primary air inlet pipe. The secondary air inlet is located above the primary air inlet and is connected to the flue gas feed device at the head of the sintering machine through a secondary air inlet pipe. A cyclone separator has a feed inlet, an air outlet, a return outlet, and a return air inlet. The feed inlet of the cyclone separator is connected to the outlet of the furnace through a discharge pipe. The return outlet of the cyclone separator is connected to the return inlet of the furnace through a return pipe. The return air inlet of the cyclone separator is located below the return valve of the cyclone separator. The return air inlet of the cyclone separator is connected to the air fan through the primary air inlet pipe. The tail flue has an air inlet and an air outlet. The air inlet of the tail flue is connected to the air outlet of the cyclone separator, and the air outlet of the tail flue is connected to the chimney.

2. The sintering flue gas recovery and utilization system according to claim 1, characterized in that, The tail flue is equipped with a secondary air preheater and a primary air preheater. The secondary air inlet pipe passes through the secondary air preheater to preheat the secondary air, and the primary air inlet pipe passes through the primary air preheater to preheat the primary air.

3. The sintering flue gas recovery and utilization system according to claim 2, characterized in that, The interior of the tail flue is equipped with a superheater, an economizer, and an SCR reactor upstream of the secondary air preheater and the primary air preheater. The superheater, the economizer, the SCR reactor, the secondary air preheater, and the primary air preheater are arranged sequentially from the air inlet to the air outlet of the tail flue.

4. The sintering flue gas recovery and utilization system according to claim 1, characterized in that, The secondary air inlet duct is connected to an air bypass.

5. The sintering flue gas recovery and utilization system according to claim 1, characterized in that, The secondary air inlet duct is connected to an induced draft fan and a sintering flue gas dust removal device.

6. The sintering flue gas recovery and utilization system according to claim 1, characterized in that, The discharge pipe has a burnout air inlet and an SNCR ammonia injection port.

7. The sintering flue gas recovery and utilization system according to claim 1, characterized in that, The exhaust duct at the tail end is connected to the chimney via a dust collector and a desulfurization tower.

8. The sintering flue gas recovery and utilization system according to claim 1, characterized in that, An air distribution plate is provided above the primary air inlet of the furnace, and multiple air outlets are evenly distributed on the air distribution plate. The secondary air inlet is located above the air distribution plate.

9. The sintering flue gas recovery and utilization system according to claim 8, characterized in that, Each of the aforementioned air vents is connected to an air cap.

10. The sintering flue gas recovery and utilization system according to claim 1, characterized in that, The outer wall of the furnace and the outer wall of the cyclone separator are both covered with a heat insulation layer.

Images