Flue gas desulfurization system in sintering method aluminum oxide production

Abstract

The utility model relates to the technical field of flue gas desulfurization and dust removal, in particular to a flue gas desulfurization system in sintering method aluminum oxide production. The device comprises a lime furnace, a cloth bag dust removal device, a desulfurization tower, a carbon component mother liquor storage tank and a heat preservation circulating liquid tank, the flue gas of the lime furnace is subjected to dust removal through the cloth bag dust removal device and then subjected to desulfurization through the desulfurization tower, and circulating liquid in the desulfurization tower and carbon component mother liquor in the carbon component mother liquor storage tank are mixed in the heat preservation circulating liquid tank; meanwhile, metering instruments such as a flow meter, a pressure gauge, a PH meter and a thermometer are arranged on the pipeline among the desulfurizing tower, the carbon component mother liquor storage tank and the heat preservation circulating liquid tank, and the metering instruments, a stop valve, a circulating pump and a feeding pump are connected to a DCS (Distributed Control System) in an electric control manner; the liquid level of the desulfurization tower and the temperature, flow and PH value of circulating liquid can be automatically controlled in an interlocking manner, so that more efficient desulfurization is realized. The system disclosed by the utility model is relatively low in cost and relatively high in desulfurization efficiency, and has a relatively good application prospect.

Description

Technical Field

[0001] This utility model relates to the field of flue gas desulfurization and dust removal technology, specifically to a flue gas desulfurization system in sintering alumina production. Background Technology

[0002] In the sintering process of alumina production, the raw material used in the lime furnace is high-quality limestone, and the fuel is anthracite (sulfur content <1%). The produced lime is used for ash preparation in alumina production. Since anthracite contains a small amount of sulfur, sulfur dioxide will be produced after combustion. Therefore, in order to meet emission standards, desulfurization treatment is required.

[0003] In existing technologies, commonly used desulfurization processes in industrial production mainly include: Ca(OH)2 semi-dry desulfurization, limestone-gypsum desulfurization, sodium-calcium double-alkali method, and seawater scrubbing method. Among these, semi-dry and gypsum desulfurization require large investments and are costly; the sodium-calcium double-alkali method generates additional gypsum, increasing the difficulty of treatment; and seawater scrubbing is not suitable for certain geographical locations. Therefore, there is a need to develop a flue gas desulfurization system that is simple in process, low in cost, and has high SO2 absorption efficiency. Currently, wet spray desulfurization is commonly used, but this process requires additional desulfurizing agents, resulting in additional costs, and its SO2 absorption efficiency is not high; the SO2 concentration in the flue gas after absorption is typically around 900 mg / m³. 3 about. Utility Model Content

[0004] To address the problems of existing technologies, this invention proposes a flue gas desulfurization system for sintering alumina production, the specific solution of which is as follows:

[0005] A flue gas desulfurization system for sintering alumina production includes: a lime furnace, a bag filter, a desulfurization tower, a carbon mother liquor storage tank, and a heat-insulated circulating liquid tank. The bag filter has a flue gas outlet at the top and a flue gas inlet at the bottom, and a pneumatic valve is installed at the flue gas outlet. The desulfurization tower includes a tower body, within which, from top to bottom, are arranged a defoaming baffle, a spray pipe, and three layers of gas-liquid exchange baffles. A desulfurization flue gas outlet is located at the top of the desulfurization tower, and a dust removal flue gas inlet and a circulating liquid outlet are located at the bottom. A level gauge is installed between the dust removal flue gas inlet and the circulating liquid outlet. The unit has a sulfur-rich liquid outlet; the lime furnace is connected to the flue gas inlet, the flue gas outlet is connected to the dust removal flue gas inlet, the circulating liquid outlet is connected to the insulated circulating liquid tank via a first pipeline, the first pipeline being equipped with a densitometer, a pressure gauge and a first pH meter; the insulated circulating liquid tank is connected to the spray pipe via a second pipeline via a circulating pump, the second pipeline being equipped with a second pH meter, a second thermometer and a second flow meter; the carbon mother liquor storage tank is connected to the insulated circulating liquid tank via a third pipeline via a feeding pump, the third pipeline being equipped with a first thermometer and a first flow meter; both the second and third pipelines are covered with an insulation layer.

[0006] Furthermore, the bag filter dust collector includes a housing, inside which, from top to bottom, are arranged a blowpipe, a tube sheet, a bag filter assembly, and a spiral dust conveying system connected to the bottom of the housing. The flue gas inlet is located below the bag filter assembly, and the flue gas outlet is located above the blowpipe.

[0007] Furthermore, the bottom of the desulfurization tower is filled with circulating liquid, the dust removal flue gas inlet is located below the gas-liquid exchange baffle and above the circulating liquid surface, and the circulating liquid outlet is located below the circulating liquid surface.

[0008] Furthermore, a first shut-off valve is provided on the first pipeline.

[0009] Furthermore, it also includes a batching system, wherein the sulfur-rich liquid outlet is connected to the batching system in the sintering alumina production system via a fourth pipeline, and a second shut-off valve is installed on the fourth pipeline.

[0010] Furthermore, both the first and second shut-off valves are solenoid valves, and all the thermometers, densitometers, pressure gauges, pH meters, level gauges, shut-off valves, circulating pumps, and feed pumps are electrically connected to the DCS control system.

[0011] The beneficial effects of this utility model are as follows:

[0012] (1) This utility model uses carbon mother liquor generated in the sintering alumina production process as a desulfurizing agent. The main component of the carbon mother liquor is Na2CO3. The operating and maintenance costs are low, no additional desulfurizing agent needs to be purchased, and the absorption of SO2 by Na2CO3 solution will not produce gypsum or other products that are difficult to treat.

[0013] (2) This utility model adopts the wet spray desulfurization process and sets up three layers of gas-liquid exchange baffles in the desulfurization tower. It uses carbon mother liquor as the circulating liquid for spraying, which can fully absorb SO2 in flue gas. At the same time, pH meters are set on the pipelines before and after the heat-insulated circulating liquid pool to accurately control the pH of the spray circulating liquid, so as to achieve the best absorption effect while saving raw materials.

[0014] (3) Both the pipeline for conveying the circulating liquid and the insulated circulating liquid tank of this utility model have a heat preservation effect. The pipeline achieves the heat preservation effect by setting an insulation layer on the outer layer. The carbon mother liquor has a high temperature. Through the setting of the insulation layer and the insulated storage tank, the circulating liquid entering the desulfurization tower has a high temperature. The absorption effect of SO2 can be further improved without additional heating and energy consumption, realizing the full utilization of carbon mother liquor materials and energy. Finally, the average measured concentration of SO2 in the flue gas is less than 35 mg / m³. 3 ;

[0015] (4) This utility model sets thermometers, densitometers, pressure gauges, pH meters, level gauges, shut-off valves, etc. on the pipeline and connects them to the DCS system for electrical control, which can realize the automatic control and regulation of the system and ensure the efficient desulfurization of the desulfurization system. Attached Figure Description

[0016] The embodiments of this utility model will be further described below with reference to the accompanying drawings, wherein:

[0017] Figure 1 A schematic diagram of the system structure of this utility model is shown.

[0018] Among them, the components are: bag filter - 1, blow pipe - 2, tube sheet - 3, bag filter - 4, spiral dust conveying system - 5, flue gas inlet - 6, pneumatic valve - 7, desulfurization tower - 8, desulfurization flue gas outlet - 9, demister - 10, spray pipe - 11, gas-liquid exchange baffle - 12, dust removal flue gas inlet - 13, sulfur-rich liquid outlet - 14, circulating liquid outlet - 15, first shut-off valve - 16, and second shut-off valve - 17. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the scope of the present utility model.

[0020] In one embodiment, a flue gas desulfurization system for sintering alumina production includes: a lime furnace, a bag filter 1, a desulfurization tower 8, a carbon mother liquor storage tank, and a thermally insulated circulating liquid tank. The bag filter includes a shell, within which, from top to bottom, are arranged a blowpipe 2, a perforated plate 3, a bag filter 4, and a spiral dust conveying system 5 connected to the bottom of the shell. A flue gas inlet 6 is located below the bag filter 4, and a flue gas outlet is located above the blowpipe 2. A pneumatic valve 7 is installed at the flue gas outlet. The desulfurization tower 8 has a diameter of φ1800 and is made of corrosion-resistant carbon steel. It includes a tower body, within which, from top to bottom, are arranged a defoaming baffle 10, a spray pipe 11, and a three-layer gas-liquid exchange baffle 12. A desulfurization flue gas outlet 9 is located at the top of the desulfurization tower, and a dust removal flue gas inlet 13 and a circulating liquid outlet 15 are located at the bottom. Circulating liquid is contained at the bottom of the desulfurization tower. The dust removal flue gas inlet 13 is located at the gas-liquid exchange baffle. Below 12 and above the circulating liquid surface, the circulating liquid outlet 15 is located below the circulating liquid surface. A level gauge is installed between the dust removal flue gas inlet 13 and the circulating liquid outlet 15. A sulfur-rich liquid outlet 14 is opened at the bottom of the desulfurization tower. The lime furnace is connected to the flue gas inlet, and the flue gas outlet is connected to the dust removal flue gas inlet. The circulating liquid outlet 15 is connected to the heat-insulated circulating liquid tank via a first pipeline. The first pipeline is equipped with a density meter, a pressure gauge, a first pH meter, and a first shut-off valve 16. The heat-insulated circulating liquid tank is connected to the spray pipe 11 via a second pipeline via a circulating pump. The second pipeline is equipped with a second pH meter, a second thermometer, and a second flow meter. The carbon mother liquor storage tank is connected to the heat-insulated circulating liquid tank via a third pipeline via a feeding pump. The carbon mother liquor storage tank has a size of φ3000×3000mm. The third pipeline is equipped with a first thermometer and a first flow meter. Both the second and third pipelines are covered with a heat-insulating layer. The system also includes a batching system. The sulfur-rich liquid outlet 14 is connected to the batching system in the sintering alumina production system via a fourth pipeline, which is equipped with a second shut-off valve 17. Both the first and second shut-off valves are solenoid valves. All thermometers, densitometers, pressure gauges, pH meters, level gauges, shut-off valves, circulating pumps, and feed pumps are electrically connected to the DCS control system for interlocking control. The circulating pumps and feed pumps are variable frequency speed regulated.

[0021] The concentration of Na₂CO₃ in the carbon mother liquor is approximately 65 g / L, and the concentration of NaOH is approximately 0 g / L. The Na₂CO₃ in the carbon mother liquor is used as a desulfurizing agent. The specific gravity of the carbon mother liquor is 1.15, the temperature is 80℃, and the flow rate is controlled at 60 m³ / s. 3 / h.

[0022] The carbon mother liquor from the sintering alumina production system is sent to a carbon mother liquor storage tank, then pumped to a thermally insulated circulating liquid storage tank. The prepared circulating liquid is then pumped into the spray pipes and sprayed into the tower. SO2 in the flue gas enters from the bottom of the desulfurization tower, diffuses upwards, and enters the liquid phase from the gas phase through the gas-liquid exchange baffle. The gas phase further rises, passes through the defoaming baffle to remove water, and is discharged through the desulfurization flue gas outlet. The concentration of SO2 in the desulfurization flue gas was measured to be 5 mg / m³. 3 In the liquid phase, sodium carbonate reacts with SO2 to form sodium sulfite, which further reacts with sulfur dioxide to form sodium bisulfite. The chemical reactions are as follows:

[0023] Na2CO3+2SO2+H2O==2NaHSO3+CO2.

[0024] The SO2-absorbed solution flows to the bottom of the tower and enters the insulated circulating liquid storage tank through the circulating liquid outlet to mix with the carbon mother liquor for further preparation and reuse in the desulfurization tower. Additionally, the level gauge installed in the desulfurization tower, controlled by a DCS system, automatically increases the opening of the first shut-off valve when the liquid level is too high and decreases or closes it when the level is too low, thus regulating the liquid level to form a continuous circulation. Furthermore, changes in the flow meters, pressure gauges, thermometers, and pH meters in the pipeline between the circulating liquid outlet and the insulated circulating liquid storage tank correspondingly adjust the speeds of the circulating pump and the feed pump. When the flow rate and pressure are high, the circulating pump speed is reduced; when the temperature and pH value are low, the feed pump speed is increased. Simultaneously, the parameters of the thermometers, pH meters, and flow meters on the first and second pipelines are interlocked to regulate the speeds of the feed pump and circulating pump, as well as the opening and closing degree of the first shut-off valve, ensuring that the temperature and pH value of the circulating liquid entering the spray pipe are maintained above the set temperature and value, and the circulating liquid level in the desulfurization tower remains within a suitable range. Furthermore, when the pH value is too low and falls below the baseline setting, the first shut-off valve is closed and the second shut-off valve is opened to discharge the sulfur-rich liquid and send it back to the alumina sintering batching system. After sintering in the clinker kiln, FeS is generated and finally discharged into the red mud dump for environmentally friendly storage.

[0025] Based on the SO2 content in the flue gas and the concentration of the carbon-alkali solution, the amount of carbon mother liquor used was calculated to be 1m³. 3 At a rate of / h, the SO2 concentration in the exhaust gas can be kept below 35mg / m³. 3 The carbon mother liquor supply capacity in the sintering alumina production process can reach 60m³. 3 / h, greatly meeting the desulfurization needs.

[0026] The foregoing description describes some exemplary embodiments of this utility model. It is understood that the above embodiments are only used to explain this utility model and do not constitute a limitation on the scope of protection of this utility model. The features in these embodiments can be recombine in a suitable manner, and the resulting solutions are still within the scope of protection claimed by this utility model. Based on the above embodiments, all other embodiments obtained by those skilled in the art without inventive effort, that is, all modifications, equivalent substitutions, and improvements made within the spirit and principles of this application, fall within the scope of protection claimed by this utility model.

Claims

1. A flue gas desulfurization system for sintering alumina production, characterized in that, include: The system includes a lime furnace, a bag filter (1), a desulfurization tower (8), a carbon mother liquor storage tank, and a heat-insulating circulating liquid tank. The bag filter (1) has a flue gas outlet at the top and a flue gas inlet (6) at the bottom. A pneumatic valve (7) is provided at the flue gas outlet. The desulfurization tower (8) includes a tower body. From top to bottom, the tower body is provided with a defoaming baffle (10), a spray pipe (11), and a three-layer gas-liquid exchange baffle (12). The top of the desulfurization tower (8) has a desulfurization flue gas outlet (9). The bottom of the desulfurization tower (8) has a dust removal flue gas inlet (13) and a circulating liquid outlet (15). A level gauge is provided between the dust removal flue gas inlet (13) and the circulating liquid outlet (15). The desulfurization tower has a sulfur-rich liquid outlet (14) at its lowest point; the lime furnace is connected to the flue gas inlet (6), the flue gas outlet is connected to the dust removal flue gas inlet (13), the circulating liquid outlet (15) is connected to the heat-insulating circulating liquid pool via a first pipeline, the first pipeline is equipped with a densitometer, a pressure gauge and a first pH meter, the heat-insulating circulating liquid pool is connected to the spray pipe (11) via a second pipeline via a circulating pump, the second pipeline is equipped with a second pH meter, a second thermometer and a second flow meter, the carbon mother liquor storage pool is connected to the heat-insulating circulating liquid pool via a third pipeline via a feeding pump, the third pipeline is equipped with a first thermometer and a first flow meter, and both the second pipeline and the third pipeline are covered with a heat-insulating layer.

2. The flue gas desulfurization system in sintering alumina production according to claim 1, characterized in that, The bag filter dust collector (1) includes a housing, and inside the housing, from top to bottom, there are a blow pipe (2), a tube sheet (3), a bag filter (4), and a spiral dust conveying system (5) connected to the bottom of the housing. The flue gas inlet (6) is located below the bag filter (4), and the flue gas outlet is located above the blow pipe (2).

3. The flue gas desulfurization system in sintering alumina production according to claim 1, characterized in that, The bottom of the desulfurization tower (8) is filled with circulating liquid. The dust removal flue gas inlet (13) is located below the gas-liquid exchange baffle (12) and above the circulating liquid surface. The circulating liquid outlet (15) is located below the circulating liquid surface.

4. The flue gas desulfurization system in sintering alumina production according to claim 1, characterized in that, The first pipeline is equipped with a first shut-off valve (16).

5. The flue gas desulfurization system in sintering alumina production according to claim 1, characterized in that, It also includes a batching system, wherein the sulfur-rich liquid outlet (14) is connected to the batching system in the sintering alumina production system via a fourth pipeline, and a second shut-off valve (17) is provided on the fourth pipeline.

6. A flue gas desulfurization system for sintering alumina production according to any one of claims 1-5, characterized in that, The first shut-off valve (16) and the second shut-off valve (17) are both solenoid valves. All thermometers, densitometers, pressure gauges, pH meters, level gauges, shut-off valves, circulating pumps and feed pumps are electrically connected to the DCS control system.

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