A two-stage desulfurization wastewater treatment process

Abstract

A two-stage desulfurization wastewater treatment process includes a flue gas evaporation and drying process section and a wastewater concentration process section; in the flue gas evaporation and drying process section, after ultra-low emission treatment of sintering flue gas, part of the flue gas with a higher temperature of 100°C is mixed and heated with the circulating reflux flue gas, and the concentrated wastewater is dried in a spray drying tower. In the wastewater concentration process section, in the concentration tower, the sprayed wastewater contacts with the flue gas in countercurrent, evaporates the water, and performs a cooling and concentration process. After the wastewater is concentrated to a certain concentration, it is transported to the spray drying tower for evaporation and drying to achieve zero wastewater discharge. The present invention has simple process, no pollution, energy saving and emission reduction, and a wide range of applications.

Description

Technical Field

[0001] The invention relates to the technical field of desulfurization, and in particular to a two-stage desulfurization wastewater treatment process. Background Art

[0002] The existing desulfurization wastewater treatment process has low efficiency, high emission pollution, is unsafe and not environmentally friendly. Summary of the invention

[0003] (I) Purpose of the invention

[0004] In order to solve the technical problems existing in the background technology, the present invention proposes a two-stage desulfurization wastewater treatment process, which has simple process, no pollution, energy saving and emission reduction, and wide application range.

[0005] (II) Technical solution

[0006] In order to solve the above problems, the present invention proposes a two-stage desulfurization wastewater treatment process, including a flue gas evaporation and drying process section and a wastewater concentration process section; specifically, the following steps are included:

[0007] S1: Introducing high temperature flue gas with ultra-low emission from sintering as heat source;

[0008] S2: The relatively high temperature flue gas is mixed with the high temperature reflux flue gas and enters the spray drying tower for drying;

[0009] S3: The rotary atomizer at the top of the spray drying tower atomizes the concentrated wastewater into droplets;

[0010] S4: In the spray drying tower, the high-temperature flue gas evaporates the wastewater droplets and dries them into solid particles; some large particles fall to the bottom of the tower, and some fine particles enter the bag filter with the cooled flue gas;

[0011] S5: In the bag filter, the dusty flue gas is filtered, the dust enters the ash hopper, and the clean flue gas is sent to the induced draft fan;

[0012] S6: The products in the spray drying tower and bag filter are discharged into the dry product storage bin, and then packaged by the packaging machine and loaded onto trucks for transportation;

[0013] S7: The flue gas after dust removal is sent out through the induced draft fan and divided into two routes:

[0014] Route A: reflux, after being heated to a preset temperature by a flue gas heater, mixed with the original flue gas, enters the spray drying tower, and then repeats the S2 process;

[0015] Route B: Flue gas is transported to the evaporation and concentration tower and enters the evaporation and concentration section;

[0016] S8: In the evaporation and concentration tower, the flue gas contacts the desulfurization wastewater under spraying in countercurrent, part of the water is evaporated, and the wastewater is concentrated; then, the flue gas is dehydrated and demisted, and then discharged from the chimney on the top of the tower;

[0017] S9: The wastewater is discharged into the circulation pool and sent to the spray layer of the evaporation concentration tower by the concentration circulation pump, and then the S8 process is repeated;

[0018] S10: The original desulfurization wastewater is added with seed crystals and then sent to the circulation pool of the evaporation concentration tower

[0019] Preferably, it includes a rotary atomizer, a spray drying tower, a first ash discharge valve, a bag filter, a second ash discharge valve, a dry product storage bin, a baler, an induced draft fan, a drying and conveying pump, an evaporation and concentration tower, a concentration circulation pump, a flue gas damper door and a flue gas heater;

[0020] The rotary atomizer is arranged at the top of the spray drying tower; the particle discharge end at the bottom of the spray drying tower is connected to the first ash discharge valve, and the first ash discharge valve is connected to the dry product storage bin; the air outlet end of the spray drying tower is connected to the air inlet end of the bag dust collector;

[0021] The upper air outlet of the bag filter is connected to the induced draft fan, the particle discharge end at the bottom of the bag filter is connected to the second ash discharge valve, and the second ash discharge valve is connected to the dry product storage bin;

[0022] The exhaust end of the induced draft fan is connected to a three-way pipe, and both exhaust ends of the three-way pipe are provided with smoke damper doors, wherein one exhaust end of the three-way pipe is connected to the exhaust end of the spray drying tower, and the other exhaust end of the three-way pipe is connected to the exhaust end of the evaporation concentration tower;

[0023] A chimney is arranged on the top of the evaporation and concentration tower; a spray layer and a circulation pool are arranged inside the evaporation and concentration tower, and the circulation pool is located below the spray layer;

[0024] The circulation pool includes a feed end, a discharge end and a waste discharge port, wherein the discharge end is connected to the feed end of the concentrated circulation pump; the discharge end of the circulation pump 11 is connected to the spray layer; the original desulfurization wastewater is connected to the feed end of the circulation pool through a pipeline.

[0025] Preferably, in S1, the temperature of the flue gas is above 100°C.

[0026] Preferably, the spray particle size of the rotary atomizer is 30-80 um.

[0027] Preferably, in S4, the residence time of the flue gas in the spray drying tower is 8-12s, and the exhaust gas temperature is 150-200°C.

[0028] Preferably, the dust emission of the bag filter is less than 10 mg / m 3 .

[0029] Preferably, in S7, the proportion of flue gas reflux accounts for 20-50% of the total flue gas; the flue gas reflux heating method is: blast furnace gas or coke oven gas of the steel plant is used as fuel, and a flue gas heater is used for heating, and the temperature is controlled at 300-500°C.

[0030] Preferably, in S8, the liquid-to-gas ratio of concentrated evaporation is controlled between 0.5-1.5, the solid slurry concentration after concentration is 10-20%, and the exhaust gas temperature is above 80°C.

[0031] Preferably, in S9, the spray layer of the evaporation concentration tower adopts a large-particle nozzle, and the atomization particle size is between 1600-2400um.

[0032] Preferably, in S10, the seed crystal is desulfurized gypsum; wherein the wastewater concentration in the circulation pool is controlled at 2-4%.

[0033] In the present invention, S1-S6 are flue gas evaporation and drying process sections, and S8-S10 are wastewater concentration process sections;

[0034] In the flue gas evaporation and drying process section, the higher temperature flue gas of 100°C (or 280°C before GGH clean flue gas after SCR denitrification) after ultra-low emission treatment of sintering flue gas is mixed and heated with the circulating reflux flue gas, and then the concentrated wastewater is dried in the spray drying tower.

[0035] In the wastewater concentration process, in the concentration tower, the sprayed wastewater contacts the flue gas in countercurrent, evaporates the water, and performs a cooling and concentration process. After the wastewater is concentrated to a certain concentration, it is transported to the spray drying tower for evaporation and drying to achieve zero wastewater discharge.

[0036] The invention has the advantages of simple process, no pollution, energy saving and emission reduction, and wide application range. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a schematic diagram of the system structure of the two-stage desulfurization wastewater treatment process proposed in the present invention. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0039] like Figure 1 As shown, the present invention proposes a two-stage desulfurization wastewater treatment process, including a flue gas evaporation and drying process section and a wastewater concentration process section; specifically, the following steps are included:

[0040] S1: Introducing high temperature flue gas with ultra-low emission from sintering as heat source;

[0041] S2: The relatively high temperature flue gas is mixed with the high temperature reflux flue gas and enters the spray drying tower 2 for drying;

[0042] S3: The rotary atomizer 1 at the top of the spray drying tower 2 atomizes the concentrated wastewater into droplets;

[0043] S4: In the spray drying tower 2, the high-temperature flue gas evaporates and dries the wastewater droplets into solid particles; some large particles fall to the bottom of the tower, and some fine particles enter the bag filter 4 with the cooled flue gas;

[0044] S5: In the bag filter 4, the dusty flue gas is filtered, the dust enters the ash hopper, and the clean flue gas is sent to the induced draft fan 8;

[0045] S6: The products in the spray drying tower 2 and the bag filter 4 are discharged into the dry product storage bin 6, and then packaged by the packaging machine 7 and loaded onto trucks for transportation;

[0046] S7: The dust-removed flue gas is sent out through the induced draft fan 8 and divided into two routes:

[0047] Route A: reflux, after being heated to a preset temperature by the flue gas heater 14, mixed with the original flue gas, enters the spray drying tower 2, and then repeats the S2 process;

[0048] Route B: The flue gas is transported to the evaporation concentration tower 10 and enters the evaporation concentration section;

[0049] S8: In the evaporation concentration tower 10, the flue gas contacts the desulfurization wastewater under spraying in countercurrent, part of the water is evaporated, and the wastewater is concentrated; then, the flue gas is discharged from the chimney 12 at the top of the tower after being dehydrated and demisted;

[0050] S9: The wastewater is discharged into the circulation pool and sent to the spray layer of the evaporation concentration tower 10 by the concentration circulation pump 11, and then the S8 process is repeated;

[0051] S10: Seed crystals are added to the original desulfurization wastewater, and then sent to the circulation pool of the evaporation concentration tower 10.

[0052] In an optional embodiment, it includes a rotary atomizer 1, a spray drying tower 2, a first ash discharge valve 3, a bag filter 4, a second ash discharge valve 5, a dry product storage bin 6, a baler 7, an induced draft fan 8, a drying delivery pump 9, an evaporation concentration tower 10, a concentration circulation pump 11, a flue gas damper door 13 and a flue gas heater 14;

[0053] The rotary atomizer 1 is arranged at the top of the spray drying tower 2; the particle discharge end at the bottom of the spray drying tower 2 is connected to the first ash discharge valve 3, and the first ash discharge valve 3 is connected to the dry product storage bin 6; the air outlet end of the spray drying tower 2 is connected to the air inlet end of the bag dust collector 4;

[0054] The upper air outlet of the bag filter 4 is connected to the induced draft fan 8, the particle discharge end at the bottom of the bag filter 4 is connected to the second ash discharge valve 5, and the second ash discharge valve 5 is connected to the dry product storage bin 6;

[0055] The exhaust end of the induced draft fan 8 is connected to a three-way pipe, and both exhaust ends of the three-way pipe are provided with a smoke damper door 13, wherein one exhaust end of the three-way pipe is connected to the exhaust end of the spray drying tower 2, and the other exhaust end of the three-way pipe is connected to the exhaust end of the evaporation concentration tower 10;

[0056] A tower chimney 12 is provided on the top of the evaporation and concentration tower 10; a spray layer and a circulation pool are provided inside the evaporation and concentration tower 10, and the circulation pool is located below the spray layer;

[0057] The circulation pool includes a feed end, a discharge end and a waste discharge port, wherein the discharge end is connected to the feed end of the concentrated circulation pump 11; the discharge end of the circulation pump 11 is connected to the spray layer; the original desulfurization wastewater is connected to the feed end of the circulation pool through a pipeline.

[0058] In the present invention, S1-S6 are flue gas evaporation and drying process sections, and S8-S10 are wastewater concentration process sections;

[0059] In the present invention, in the flue gas evaporation and drying process section, the relatively high temperature flue gas of 100°C (or 280°C before the GGH clean flue gas after SCR denitrification) after ultra-low emission treatment of the sintering flue gas is mixed and heated with the circulating reflux flue gas, and then the concentrated wastewater is dried in a spray drying tower.

[0060] In the present invention, in the wastewater concentration process section, in the concentration tower, the sprayed wastewater contacts the flue gas in countercurrent, evaporates the water, and performs a cooling and concentration process. After the wastewater is concentrated to a certain concentration, it is transported to the spray drying tower for evaporation and drying to achieve zero wastewater discharge.

[0061] The invention has the advantages of simple process, no pollution, energy saving and emission reduction, and wide application range.

[0062] In an optional embodiment, in S1, the temperature of the flue gas is above 100°C.

[0063] In an optional embodiment, the spray particle size of the rotary atomizer 1 is 30-80 um.

[0064] In an optional embodiment, in S4, the residence time of the flue gas in the spray drying tower 2 is 8-12s, and the exhaust gas temperature is 150-200°C.

[0065] In an optional embodiment, the dust emission of the bag filter 4 is less than 10 mg / m 3 .

[0066] In an optional embodiment, in S7, the proportion of smoke reflow accounts for 20-50% of the total smoke;

[0067] The flue gas reflux heating method is: the blast furnace gas or coke oven gas of the steel plant is used as fuel, and the flue gas heater 14 is used for heating, and the temperature is controlled at 300-500°C.

[0068] In an optional embodiment, in S8, the liquid-to-gas ratio of concentrated evaporation is controlled between 0.5-1.5, the solid slurry concentration after concentration is 10-20%, and the exhaust gas temperature is above 80°C.

[0069] In an optional embodiment, in S9, the spray layer of the evaporation concentration tower 10 uses a large-particle nozzle, and the atomization particle size is between 1600-2400 um.

[0070] In an optional embodiment, in S10, the seed crystal is desulfurized gypsum; wherein the wastewater concentration in the circulation pool is controlled at 2-4%.

[0071] It should be noted that the above optional embodiments improve the desulfurization efficiency, ensure pollution-free emissions, and are safer and more environmentally friendly.

[0072] It should be understood that the above specific embodiments of the present invention are only used to illustrate or explain the principles of the present invention, and do not constitute a limitation of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. In addition, the appended claims of the present invention are intended to cover all changes and modifications that fall within the scope and boundaries of the appended claims, or the equivalent forms of such scope and boundaries.

Claims

1. A two-stage desulfurization wastewater treatment process, characterized in that: It includes a flue gas evaporation and drying process section and a wastewater concentration process section; specifically includes the following steps: S1: Introducing high temperature flue gas with ultra-low emission from sintering as heat source; S2: The relatively high temperature flue gas is mixed with the high temperature reflux flue gas and enters the spray drying tower (2) for drying; S3: The rotary atomizer (1) at the top of the spray drying tower (2) atomizes the concentrated wastewater into droplets; S4: In the spray drying tower (2), the high-temperature flue gas evaporates the wastewater droplets and dries them into solid particles; some large particles fall to the bottom of the tower, and some fine particles enter the bag filter (4) along with the cooled flue gas; S5: In the bag filter (4), the dusty flue gas is filtered, the dust enters the ash hopper, and the clean flue gas is sent to the induced draft fan (8); S6: The products in the spray drying tower (2) and the bag filter (4) are discharged into the dry product storage bin (6), and then packaged by a packaging machine (7) and loaded onto trucks for transportation; S7: The dust-removed flue gas is sent out through the induced draft fan (8) and divided into two paths: Route A: reflux, after being heated to a preset temperature by a flue gas heater (14), mixed with the original flue gas, and enters the spray drying tower (2), and then the S2 process is repeated; Route B: The flue gas is transported to the evaporation concentration tower (10) and enters the evaporation concentration section; In S7, the proportion of flue gas recirculation accounts for 20-50% of the total flue gas; S8: In the evaporation concentration tower (10), the flue gas contacts the desulfurization wastewater under spraying in countercurrent, part of the water is evaporated, and the wastewater is concentrated; then, the flue gas is discharged from the chimney (12) on the top of the tower after being dehydrated and demisted; after the wastewater is concentrated to a certain concentration, it is transported to the spray drying tower (2) for evaporation and drying; S9: the wastewater is discharged into the circulation pool and sent to the spray layer of the evaporation concentration tower (10) by the concentration circulation pump (11), and then the S8 process is repeated; the circulation pool includes a feed end, a discharge end and a waste discharge port, and its discharge end is connected to the feed end of the concentration circulation pump (11); the discharge end of the circulation pump (11) is connected to the spray layer; the original desulfurization wastewater is connected to the feed end of the circulation pool through a pipeline; S10: seed crystals are added to the original desulfurization wastewater, and then sent to the circulation pool of the evaporation concentration tower (10); In S10, the seed crystal is desulfurized gypsum; wherein the wastewater concentration in the circulation pool is controlled at 2-4%.

2. The two-stage desulfurization wastewater treatment process according to claim 1 is characterized in that: It comprises a rotary atomizer (1), a spray drying tower (2), a first ash discharge valve (3), a bag filter (4), a second ash discharge valve (5), a dry product storage bin (6), a baler (7), an induced draft fan (8), a drying delivery pump (9), an evaporation concentration tower (10), a concentration circulation pump (11), a smoke damper door (13) and a smoke heater (14); The rotary atomizer (1) is arranged at the top of the spray drying tower (2); the particle discharge end at the bottom of the spray drying tower (2) is connected to a first ash discharge valve (3), and the first ash discharge valve (3) is connected to a dry product storage bin (6); the air outlet end of the spray drying tower (2) is connected to the air inlet end of a bag filter (4); The upper air outlet of the bag filter (4) is connected to the induced draft fan (8), the particle discharge end at the bottom of the bag filter (4) is connected to the second ash discharge valve (5), and the second ash discharge valve (5) is connected to the dry product storage bin (6); The exhaust end of the induced draft fan (8) is connected to a three-way pipe, and both exhaust ends of the three-way pipe are provided with smoke damper doors (13), wherein one exhaust end of the three-way pipe is connected to the exhaust end of the spray drying tower (2), and the other exhaust end of the three-way pipe is connected to the exhaust end of the evaporation concentration tower (10); A tower top chimney (12) is arranged at the top of the evaporation concentration tower (10); a spray layer and a circulation pool are arranged inside the evaporation concentration tower (10), and the circulation pool is located below the spray layer.

3. The two-stage desulfurization wastewater treatment process according to claim 1 is characterized in that: In S1, the temperature of the flue gas is 100°C or higher.

4. The two-stage desulfurization wastewater treatment process according to claim 1 is characterized in that: The spray particle size of the rotary atomizer (1) is 30-80 μm.

5. The two-stage desulfurization wastewater treatment process according to claim 1 is characterized in that: In S4, the residence time of the flue gas in the spray drying tower (2) is 8-12 seconds, and the exhaust gas temperature is 150-200°C.

6. The two-stage desulfurization wastewater treatment process according to claim 1 is characterized in that: Dust emission from bag filter (4) < 10 mg / m 3 .

7. The two-stage desulfurization wastewater treatment process according to claim 1 is characterized in that: The flue gas reflux heating method is: the blast furnace gas or coke oven gas of the steel plant is used as fuel, and the flue gas heater (14) is used for heating, and the temperature is controlled at 300-500°C.

8. The two-stage desulfurization wastewater treatment process according to claim 1 is characterized in that: In S8, the liquid-gas ratio of concentrated evaporation is controlled between 0.5-1.5, the solid slurry concentration after concentration is 10-20%, and the exhaust gas temperature is above 80°C.

9. The two-stage desulfurization wastewater treatment process according to claim 1, characterized in that: In S9, the spray layer of the evaporation concentration tower (10) adopts a large-particle nozzle, and the atomized particle size is between 1600-2400um.

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