A flue gas desulfurization system for a side-blown reduction smelting furnace

Abstract

The application discloses a flue gas desulfurization system for a side-blown reduction smelting furnace, and belongs to the field of industrial flue gas purification. The system adopts a washing tower, a first desulfurization tower and a second desulfurization tower which are directly connected with an air tower by a frequency conversion induced fan, and each tower is provided with an external ring pipe spraying layer; the second desulfurization tower is provided with a gas lifting cap layer to isolate backwashing water from desulfurization slurry to form a closed loop circulation; an aeration device is arranged at the bottom of the first desulfurization tower and in an independent oxidation tank to form a two-stage oxidation system; and a wet type electric demister is directly installed at the top of the second desulfurization tower. The application can significantly reduce system resistance, realize free disassembly and assembly of a spraying assembly into the tower, continuously operate backwashing without blockage, improve the utilization rate of a desulfurizing agent and realize ultra-low emission of particulate matters.

Description

Technical Field

[0001] This invention belongs to the field of industrial flue gas purification technology, specifically relating to a flue gas desulfurization system for a side-blown reduction smelting furnace. Background Technology

[0002] The existing desulfurization system for the side-blown reduction smelting furnace uses a lime-gypsum desulfurization process, consisting of two-stage dynamic wave desulfurization towers connected in series. Its long-term operation has revealed the following technical defects:

[0003] (1) The resistance of the desulfurization system is very high (>4000pa), which causes the existing desulfurization booster fan to be severely pressurized and the fan bearing to leak flue gas. The sulfur dioxide and other polluting gases in the leaked flue gas seriously affect the fan room and the surrounding environment.

[0004] (2) The existing flat plate demister in the second-stage dynamic wave desulfurization tower is often blocked, which leads to poor flue gas emission of the entire system and thus affects the production operation of the entire production system. In addition, only one layer of flat plate demister is installed in the second-stage dynamic wave desulfurization tower, which can no longer meet the current emission standards for particulate matter (concentration <10mg / Nm³).

[0005] (3) The existing desulfurization system has a low desulfurizing agent utilization rate and adopts the aeration oxidation method in the desulfurization tower circulation tank. Due to the frequent switching of circulating liquid in the desulfurization circulation tank, the oxidation time is insufficient and the oxidation efficiency is low. On the one hand, a large amount of effective components in the desulfurization liquid are wasted before entering the filter; on the other hand, the oxidation is insufficient, and most of the desulfurized liquid exists in the form of calcium sulfite, resulting in a high water content in the gypsum filter cake after pressure filtration. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a flue gas desulfurization system and method for a side-blown reduction smelting furnace, thereby solving the problems of high resistance, easy clogging, poor oxidation, and difficulty in meeting emission standards in the desulfurization process of a side-blown reduction smelting furnace.

[0007] To achieve the above-mentioned technical objectives, the present invention is implemented through the following technical solution:

[0008] The flue gas desulfurization system for a side-blown reduction smelting furnace of the present invention includes:

[0009] The flue gas conveying unit includes a variable frequency induced draft fan, the outlet of which is connected to the flue gas inlet of the scrubbing tower, without a booster fan in between;

[0010] The desulfurization unit includes a scrubbing tower, a first desulfurization tower, and a second desulfurization tower connected in series.

[0011] The washing tower, the first desulfurization tower and the second desulfurization tower all adopt an external ring pipe spray layer, which includes a spray main pipe arranged on the outer wall of the tower body, multiple spray branch pipes inserted radially into the tower from the tower wall, and nozzles installed at the end of each spray branch pipe.

[0012] The washing tower is equipped with a washing circulation pump, the inlet of which is connected to the liquid outlet of the liquid storage section of the washing tower, and the outlet of which is connected to the main spray pipe of the washing tower through the washing tower circulation pipeline.

[0013] The first desulfurization tower is equipped with a first-stage desulfurization circulation pump, and the second desulfurization tower is equipped with a second-stage desulfurization circulation pump. The inlet of each desulfurization circulation pump is connected to the liquid outlet of the storage section of the corresponding desulfurization tower, and its outlet is connected to the spray main pipe of the corresponding desulfurization tower.

[0014] The outlet pipeline of the first-stage desulfurization circulation pump is equipped with a desulfurization circulation branch;

[0015] The second desulfurization tower has a rising cap layer between the spray section and the backwash layer. The rising cap layer divides the space inside the tower into an upper demisting zone and a lower spraying zone. The backwash layer is set in the demisting zone. The water from the backwash layer is discharged out of the tower through the drain port at the edge of the rising cap layer, enters an independent backwash circulation tank, and is then pumped back to the backwash layer by the backwash pump to form a closed-loop backwash circulation.

[0016] The oxidation unit includes a first aeration device located at the bottom of the liquid storage section of the first desulfurization tower, and an independently set oxidation tank, wherein a second aeration device is provided in the oxidation tank; the liquid inlet of the oxidation tank is connected to the desulfurization circulation branch; the first aeration device and the second aeration device together form a two-stage oxidation system.

[0017] The deep purification unit includes a wet electrostatic precipitator, which is installed at the top of the second desulfurization tower. Its flue gas inlet is connected to the top outlet of the second desulfurization tower, and a chimney is installed at its top.

[0018] The lime slurry preparation and storage unit includes a lime powder storage silo, a screw feeder, a lime mixing tank, a lime mixing pump, a lime slurry storage tank, and a lime slurry pump. The outlet of the lime slurry pump is connected to a first desulfurization tower and a second desulfurization tower.

[0019] The scrubbing tower and the first desulfurization tower are each equipped with 2-4 layers of external ring pipe spraying layers, and the second desulfurization tower is equipped with 1-3 layers of external ring pipe spraying layers.

[0020] The diameter of the liquid storage section of the washing tower, the first desulfurization tower, and the second desulfurization tower is larger than the diameter of the spray section.

[0021] The gas lifting cap layer includes at least one gas lifting cap, which allows flue gas to pass upward while preventing liquid from dripping downward; the drain outlet is located at the lowest point of the edge of the gas lifting cap layer.

[0022] The oxidation tank is modified from the first-stage dynamic wave desulfurization tower in the original side-blown reduction smelting furnace flue gas desulfurization system. It is equipped with an oxidation tank induced draft fan at the top. The inlet of the oxidation tank induced draft fan is connected to the top of the oxidation tank, and its outlet is connected to the flue gas inlet of the second desulfurization tower, which is used to draw the aeration tail gas in the oxidation tank back to the second desulfurization tower.

[0023] The desulfurization system also includes a slurry settling and reuse unit; the slurry settling and reuse unit includes a washing settling tank and a washing settling liquid transfer pump, the inlet of the washing settling tank is connected to the outlet of the washing tower, the inlet of the washing settling liquid transfer pump is connected to the supernatant outlet of the washing settling tank, and its outlet is connected to the storage section of the washing tower.

[0024] The desulfurization system also includes an emergency spray unit, which includes a high-level water tank. The inlet of the high-level water tank is connected to the process water tank, and its outlet is connected to the flue gas inlet pipe of the scrubbing tower.

[0025] The desulfurization system also includes a gypsum dewatering unit, a process water unit, and a wastewater collection unit; the gypsum dewatering unit includes a cyclone pump, a hydrocyclone separator, a vacuum belt filter, and a vacuum pump connected in sequence by pipelines, as well as a clear liquid tank and a clear liquid pump. The vacuum pump is connected to a circulating cooling water pipeline, the inlet of the clear liquid tank is connected to the filtrate outlet of the vacuum belt filter, and the outlet of the clear liquid pump is connected to a lime slurry mixing tank.

[0026] The process water unit includes a process water tank and a process water pump. The outlet of the process water pump is connected to the lime slurry mixing tank, the elevated water tank, and various flushing points within the system.

[0027] The wastewater collection unit includes a sump and a sump pump, with the inlet of the sump pump connected to the sump and its outlet connected to a lime mixing tank.

[0028] This invention also provides a flue gas desulfurization method utilizing the above system, comprising the following steps:

[0029] S1. The flue gas flows sequentially through the scrubbing tower, the first desulfurization tower, and the second desulfurization tower, where it comes into contact with the lime slurry sprayed in each tower to remove sulfur dioxide.

[0030] S2, the lime slurry pump delivers fresh lime slurry into the first desulfurization tower and the second desulfurization tower respectively; the circulating slurry at the bottom of the storage section of the second desulfurization tower is transferred to the first desulfurization tower through a connecting pipe;

[0031] S3. Part of the circulating slurry at the bottom of the first desulfurization tower storage section is sent to the oxidation tank through the desulfurization circulation branch, and works together with the first aeration device at the bottom of the first desulfurization tower storage section and the second aeration device in the oxidation tank to carry out two-stage oxidation; the oxidized slurry is dewatered by a cyclone pump, a hydrocyclone separator, and a vacuum belt filter, and the filtrate enters the clear liquid tank, and is then sent back to the lime slurry mixing tank for reuse by the clear liquid pump.

[0032] S4. The slurry discharged from the washing tower enters the washing settling tank for settling. The supernatant is sent back to the storage section of the washing tower by the post-set liquid transfer pump for recycling. In the second desulfurization tower, the backwash pump draws backwash water from the backwash circulation tank and sends it to the backwash layer. The water after rinsing returns to the backwash circulation tank through the drain port at the edge of the air cap layer, forming a closed loop.

[0033] The beneficial effects of this invention are:

[0034] Compared with existing technologies, this invention replaces the small-throat power wave tower with a large-diameter empty tower spray, effectively reducing the total system resistance. Combined with a single-stage variable frequency induced draft fan direct connection scheme, it significantly reduces energy consumption. The external ring pipe structure allows the spray components to be disassembled and cleaned outside the tower, shortening maintenance time from days to hours. The rising cap layer physically isolates backwash water from the desulfurization circulating liquid, allowing backwashing to operate continuously without affecting the water balance and preventing demister blockage. The two-stage oxidation system extends the total oxidation residence time of the slurry. Combined with the stepped utilization method of feeding fresh slurry into the secondary tower and pre-consumed slurry into the primary tower, it improves the utilization rate of the desulfurizing agent. The integrated wet electrostatic precipitator at the top of the tower performs secondary capture of aerosols and fine particulate matter in the wet flue gas, ensuring that the outlet particulate matter concentration is consistently below 10 milligrams per standard cubic meter. Simultaneously, it maximizes the reuse of existing equipment, resulting in a compact structure and reduced investment. Attached Figure Description

[0035] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments are briefly introduced below.

[0036] Figure 1 This is a schematic diagram of the process pipeline connection of the flue gas desulfurization system for a side-blown reduction smelting furnace in an embodiment of the present invention.

[0037] Figure 2 A schematic diagram of the desulfurization tower in this embodiment of the invention (including an external ring pipe and a gas-lifting cap layer).

[0038] Figure 3 A front view of the flue gas desulfurization system for a side-blown reduction smelting furnace in an embodiment of the present invention.

[0039] In the attached diagram, the structural names represented by each number are as follows:

[0040] 1-Variable frequency induced draft fan; 2-Scrubbing tower; 3-First desulfurization tower; 4-Second desulfurization tower; 5-Wet electrostatic precipitator; 6-Chimney; 7-Oxidation tank; 8-Oxidation blower; 9-Cyclone separator; 10-Vacuum belt filter; 11-Vacuum pump; 12-Oxidation tank induced draft fan; 13-Backwash circulation tank; 14-Backwash pump; 15-Lime powder storage silo; 16-Screw feeder; 17-Lime slurry mixing tank; 18-Lime slurry storage tank; 19-Scrubbing settling tank; 20-Clear liquid tank; 21-Process water tank; 22-High-level water tank; 23-Pit; 24-Washing 25-First-stage desulfurization circulation pump; 26-Second-stage desulfurization circulation pump; 27-Lime slurry mixing pump; 28-Lime slurry pump; 29-Washing sedimentation liquid transfer pump; 30-Clear liquid pump; 31-Process water pump; 32-Sump pump; 33-Swirl pump; 34-Spray main pipe; 35-Spray branch pipe; 36-Nozzle; 37-Flange; 38-Storage section; 39-Spray section; 40-Side agitator; 41-Gas lift cap layer; 42-Gas lift cap; 43-Backwash layer; 44-Drain outlet; 45-Scrubber circulation pipeline; 46-Desulfurization circulation branch. Detailed Implementation

[0041] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0042] Example 1

[0043] See Figures 1 to 3 As shown, this embodiment is based on the modification of the original flue gas desulfurization system of a side-blown reduction smelting furnace in a smelting enterprise. The original system adopted a two-stage dynamic wave desulfurization tower series process, including one induced draft fan (air volume 42,000 cubic meters per hour, air pressure 5,000 Pa, power 90 kW) and one desulfurization booster fan (air volume 14,532 standard cubic meters per hour, air pressure 7,200 Pa, power 160 kW), as well as auxiliary facilities such as two-stage dynamic wave desulfurization towers, lime slurry preparation, and gypsum dewatering. This invention modifies the system, and the modified system mainly consists of a flue gas conveying unit, a desulfurization unit, an oxidation unit, a gypsum dewatering unit, a lime slurry preparation and storage unit, a slurry settling and reuse unit, a process water and emergency spray unit, a wastewater collection unit, and a deep purification unit.

[0044] The flue gas conveying unit includes a variable frequency induced draft fan 1, with parameters of 60,000 cubic meters per hour, 7,000 Pa, and a motor power of 160 kW, and is equipped with variable frequency control. The inlet of the variable frequency induced draft fan 1 is connected to the outlet of the front-end bag filter through a flue, and its outlet is directly connected to the flue gas inlet of the scrubbing tower 2 through a flue. The desulfurization booster fan in the original system has been removed and eliminated, and the original induced draft fan has been replaced by this variable frequency induced draft fan 1.

[0045] The desulfurization unit includes a scrubbing tower 2, a first desulfurization tower 3, and a second desulfurization tower 4 connected in series. The flue gas outlet of scrubbing tower 2 is connected to the flue gas inlet of the first desulfurization tower 3 via a flue, and the flue gas outlet of the first desulfurization tower 3 is connected to the flue gas inlet of the second desulfurization tower 4 via a flue. All three are empty tower spray towers made of FRP material.

[0046] The lower part of each tower is a liquid storage section 38 with a diameter of 4000 mm; the upper part is a spray section 39 with a diameter of 3000 mm. A side agitator 40 is installed in the liquid storage section 38 to prevent slurry sedimentation.

[0047] Each tower employs an external ring-pipe spray layer: the main spray pipe 34 is arranged in a ring along the outer wall of the tower body, and multiple spray branch pipes 35 are inserted radially into the tower from the tower wall. Each spray branch pipe 35 has a nozzle 36 installed at its end. Each spray branch pipe 35 is connected to a flange seat welded to the tower wall via a flange 37. When the nozzle 36 becomes clogged, simply loosen the flange 37 to remove the entire spray branch pipe 35 from the tower for cleaning; no need to enter the tower or stop the tower for liquid drainage.

[0048] The washing tower 2 is equipped with a washing circulation pump 24. Its inlet is connected to the liquid outlet of the liquid storage section 38 of the washing tower 2 through a pipeline, and its outlet is connected to the spray main pipe 34 of the washing tower 2 through the washing tower circulation pipeline 45. It is used to transport the circulating slurry at the bottom of the washing tower 2 to the spray section 39 for circulating spraying.

[0049] The first desulfurization tower 3 is equipped with a first-stage desulfurization circulation pump 25, whose inlet is connected to the outlet of the liquid storage section 38 of the first desulfurization tower 3 via a pipeline, and whose outlet is connected to the main spray pipe 34 of the first desulfurization tower 3 via a pipeline. The second desulfurization tower 4 is equipped with a second-stage desulfurization circulation pump 26, whose inlet is connected to the outlet of the liquid storage section 38 of the second desulfurization tower 4 via a pipeline, and whose outlet is connected to the main spray pipe 34 of the second desulfurization tower 4 via a pipeline.

[0050] A connecting pipe is provided between the liquid storage section 38 of the second desulfurization tower 4 and the liquid storage section 38 of the first desulfurization tower 3, which is used to transfer the circulating slurry with reduced pH value at the bottom of the second desulfurization tower 4 to the first desulfurization tower 3 for continued use.

[0051] A desulfurization circulation branch line 46 is also provided on the outlet pipeline of the first-stage desulfurization circulation pump 25, which is connected to the oxidation tank 7 through a pipeline.

[0052] The second desulfurization tower 4 has a rising cap layer 41 between the spray section 39 and the backwash layer 43. The rising cap layer 41 includes at least one rising cap 42, which only allows flue gas to pass upwards, while preventing liquid from leaking downwards. The rising cap layer 41 divides the space inside the tower into an upper demisting zone and a lower spraying zone. The backwash layer 43 is provided in the demisting zone.

[0053] After being sprayed down from the backwash layer 43, the backwash water does not fall into the spray area below, but instead collects along the slope of the riser cap layer 41 to the drain port 44 at the edge. The drain port 44 is connected to the backwash circulation tank 13 via a pipeline. The water in the backwash circulation tank 13 is returned to the backwash layer 43 via the backwash pump 14 and pipeline, forming a completely independent closed-loop circulation. Backwashing can operate continuously without affecting the water balance of the desulfurization tower.

[0054] The oxidation unit includes a first aeration device at the bottom of the storage section 38 of the first desulfurization tower 3. The oxidation tank 7 is a modified version of the original single-stage dynamic wave desulfurization tower, and it is equipped with a second aeration device. The outlet of the oxidation blower 8 is connected to both the first and second aeration devices via pipelines, supplying air to both simultaneously. The parameters of the oxidation blower 8 are: air volume of 35 cubic meters per minute, air pressure of 65 kPa, and motor power of 75 kW. The first and second aeration devices together form a two-stage oxidation system, extending the total oxidation residence time of the slurry.

[0055] The inlet of oxidation tank 7 is connected to the outlet of the storage section 38 of the first desulfurization tower 3 and the desulfurization circulation branch line 46 via pipelines. The slurry with pH value reduced to 5 to 6 in the first desulfurization tower 3 and the waste slurry discharged from the washing tower 2 are both sent to oxidation tank 7 for deep oxidation.

[0056] The oxidation tank 7 is equipped with an oxidation tank exhaust fan 12 at the top. Its inlet is connected to the top of the oxidation tank 7 through a pipe, and its outlet is connected to the flue gas inlet of the second desulfurization tower 4 through a pipe, so as to draw the aeration tail gas back to the system for treatment and avoid secondary pollution.

[0057] The gypsum dewatering unit includes a cyclone pump 33, a hydrocyclone 9, a vacuum belt filter 10, and a vacuum pump 11, all connected in sequence via pipes, as well as a clear liquid tank 20 and a clear liquid pump 30. The inlet of the cyclone pump 33 is connected to the outlet of the oxidation tank 7 via a pipe. The underflow outlet of the hydrocyclone 9 is connected to the vacuum belt filter 10 via a pipe. The vacuum pump 11 is connected to the vacuum belt filter 10 via a vacuum pipe, providing vacuum power to the filter. The vacuum pump 11 is also connected to a circulating cooling water system via a pipe. The circulating cooling water continuously flows through the cooling jacket of the vacuum pump 11 to remove the heat generated during operation.

[0058] After being pre-concentrated by hydrocyclone 9, the oxidized gypsum slurry enters vacuum belt filter 10 for dewatering, resulting in a gypsum filter cake with low moisture content. The filtrate outlet of vacuum belt filter 10 is connected to clear liquid tank 20 via a pipeline. The filtrate in clear liquid tank 20 is then pumped back to lime mixing tank 17 for reuse by clear liquid pump 30 via a pipeline.

[0059] The lime slurry preparation and storage unit includes a lime powder storage silo 15, a screw feeder 16, a lime slurry mixing tank 17, a lime slurry mixing pump 27, a lime slurry storage tank 18, and a lime slurry pump 28. The inlet of the screw feeder 16 is connected to the outlet of the lime powder storage silo 15, and its outlet is connected to the lime slurry mixing tank 17. A process water pump 31 draws process water from the process water tank 21 and delivers it to the lime slurry mixing tank 17 via a pipeline. The inlet of the lime slurry mixing pump 27 is connected to the lime slurry mixing tank 17 via a pipeline, and its outlet is connected to the lime slurry storage tank 18 via a pipeline. The inlet of the lime slurry pump 28 is connected to the lime slurry storage tank 18 via a pipeline, and its outlet is connected to the first desulfurization tower 3 and the second desulfurization tower 4 via pipelines, respectively, to replenish the desulfurization system with fresh lime slurry.

[0060] The slurry settling and reuse unit includes a washing settling tank 19 and a washing settling liquid transfer pump 29. The drain outlet of the washing tower 2 is connected to the washing settling tank 19 via a pipeline. The supernatant outlet of the washing settling tank 19 is connected to the inlet of the washing settling liquid transfer pump 29 via a pipeline, and the outlet of the washing settling liquid transfer pump 29 is connected to the storage section 38 of the washing tower 2 via a pipeline, returning the settled supernatant to the washing tower for recycling. The sediment at the bottom of the washing settling tank 19 is periodically cleaned and transported off-site.

[0061] The process water unit includes a process water tank 21 and a process water pump 31. The inlet of the process water pump 31 is connected to the process water tank 21 via a pipeline, and its outlet is connected to the lime slurry mixing tank 17, the elevated water tank 22, and various flushing points within the system via pipelines.

[0062] The emergency spray unit includes an elevated water tank 22. The inlet of the elevated water tank 22 is connected to the process water tank 21 via a pipe, and its outlet is connected to the flue gas inlet pipe of the scrubbing tower 2 via a pipe. An electric valve is installed on this pipe, and the electric valve is interlocked with a temperature transmitter installed at the flue gas inlet of the scrubbing tower 2. When the flue gas temperature exceeds a set value, the electric valve automatically opens, and the water in the elevated water tank 22 flows into the flue gas duct by gravity for emergency spray cooling, preventing high-temperature flue gas from damaging the tower body.

[0063] The wastewater collection unit includes a sump 23 and a sump pump 32. The sump 23 collects leaked slurry and flushing wastewater from the system. The inlet of the sump pump 32 is connected to the bottom of the sump 23 via a pipe, and its outlet is connected to the lime mixing tank 17 via a pipe to reuse the collected liquid.

[0064] The deep purification unit includes a wet electrostatic precipitator 5, which is directly installed on top of the second desulfurization tower 4, with the flue gas inlet connected to the top outlet of the second desulfurization tower 4. The wet electrostatic precipitator 5 uses 99 hexagonal anode tubes made of C-FRP material, with a processing capacity of 40,000 cubic meters per hour. An exhaust chimney 6 is installed on top of the wet electrostatic precipitator 5, with a diameter of 1100 mm and a height of 31 meters. After deep purification by the wet electrostatic precipitator 5, the submicron-sized aerosols and fine particulate matter carried by the flue gas are efficiently captured, achieving ultra-low emissions.

[0065] In this embodiment, the flue gas desulfurization system processes 27,000 standard cubic meters of flue gas per hour (50,000 cubic meters per hour under normal operating conditions), with an inlet sulfur dioxide concentration not exceeding 23,000 milligrams per standard cubic meter. The flue gas flows sequentially through scrubbing tower 2, the first desulfurization tower 3, and the second desulfurization tower 4, where it comes into contact with the lime slurry sprayed in each tower to remove sulfur dioxide. Lime slurry pump 28 delivers fresh lime slurry to the first desulfurization tower 3 and the second desulfurization tower 4. The circulating slurry at the bottom of the storage section 38 of the second desulfurization tower 4 is transferred to the first desulfurization tower 3 via a connecting pipe. A portion of the circulating slurry at the bottom of the storage section 38 of the first desulfurization tower 3 is sent to the oxidation tank 7 through the desulfurization circulation branch 46, where it undergoes two-stage oxidation in conjunction with the first and second aeration devices. The oxidized slurry is dewatered by a cyclone pump 33, a hydrocyclone 9, and a vacuum belt filter 10. The filtrate enters the clear liquid tank 20 and is then returned to the lime slurry mixing tank 17 by the clear liquid pump 30 for reuse. The slurry discharged from the washing tower 2 enters the washing settling tank 19 for settling, and the supernatant is sent back to the storage section 38 of the washing tower 2 by the washing settling liquid transfer pump 29 for recycling. In the second desulfurization tower 4, the backwash pump 14 draws backwash water from the backwash circulation tank 13 and sends it to the backwash layer 43. The water after rinsing returns to the backwash circulation tank 13 through the drain port 44 at the edge of the air riser layer 41, forming a closed loop circulation.

[0066] Testing revealed the following: total system resistance was 1850 Pa (original system was 4200 Pa); outlet sulfur dioxide concentration did not exceed 45 mg / m³; outlet particulate matter concentration did not exceed 6 mg / m³; desulfurizing agent (lime) utilization rate increased from 62% to 86%; gypsum filter cake moisture content decreased from 35% to 18%; and the system operated continuously for 6 months without any nozzle or demister clogging failures.

[0067] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not describe all details exhaustively, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification.

Claims

1. A flue gas desulfurization system for a side-blown reduction smelting furnace, characterized in that, include: The flue gas conveying unit includes a variable frequency induced draft fan (1), whose outlet is connected to the flue gas inlet of the scrubbing tower (2), without a booster fan in between; The desulfurization unit includes a washing tower (2), a first desulfurization tower (3), and a second desulfurization tower (4) connected in series. The washing tower (2), the first desulfurization tower (3), and the second desulfurization tower (4) all adopt an external ring pipe spray layer, which includes a spray main pipe (34) arranged on the outer wall of the tower body, multiple spray branch pipes (35) inserted radially from the tower wall into the tower, and nozzles (36) installed at the end of each spray branch pipe (35). The washing tower (2) is equipped with a washing circulation pump (24), whose inlet is connected to the liquid outlet of the liquid storage section (38) of the washing tower (2), and whose outlet is connected to the spray main pipe (34) of the washing tower (2) through the washing tower circulation pipeline (45). The first desulfurization tower (3) is equipped with a first-stage desulfurization circulation pump (25), and the second desulfurization tower (4) is equipped with a second-stage desulfurization circulation pump (26). The inlet of each desulfurization circulation pump is connected to the outlet of the liquid storage section (38) of the corresponding desulfurization tower, and its outlet is connected to the spray main pipe (34) of the corresponding desulfurization tower. The first-stage desulfurization circulation pump (25) has a desulfurization circulation branch (46) on its outlet pipeline. The second desulfurization tower (4) has a rising cap layer (41) between the spray section (39) and the backwash layer (43). The rising cap layer (41) divides the space inside the tower into an upper demisting zone and a lower spraying zone. The demisting zone is equipped with a backwash layer (43). The water from the backwash layer (43) is discharged out of the tower through the drain port (44) at the edge of the rising cap layer (41), enters an independent backwashing circulation tank (13), and is then sent back to the backwash layer (43) by the backwash pump (14) to form a backwashing closed-loop circulation. The oxidation unit includes a first aeration device located at the bottom of the liquid storage section (38) of the first desulfurization tower (3) and an independently set oxidation tank (7), wherein a second aeration device is provided in the oxidation tank (7); the liquid inlet of the oxidation tank (7) is connected to the desulfurization circulation branch (46); the first aeration device and the second aeration device together form a two-stage oxidation system. The deep purification unit includes a wet electrostatic precipitator (5), which is installed at the top of the second desulfurization tower (4), with its flue gas inlet connected to the top outlet of the second desulfurization tower (4), and a chimney (6) installed at its top. The lime slurry preparation and storage unit includes a lime powder storage silo (15), a screw feeder (16), a lime mixing tank (17), a lime mixing pump (27), a lime slurry storage tank (18), and a lime slurry pump (28), the outlet of which is connected to a first desulfurization tower (3) and a second desulfurization tower (4).

2. The flue gas desulfurization system for a side-blown reduction smelting furnace according to claim 1, characterized in that, The spray sections (39) of the washing tower (2) and the first desulfurization tower (3) are respectively provided with 2-4 layers of external ring pipe spray layers, and the spray section (39) of the second desulfurization tower (4) is provided with 1-3 layers of external ring pipe spray layers.

3. The flue gas desulfurization system for a side-blown reduction smelting furnace according to claim 1, characterized in that, The diameter of the liquid storage section (38) of the washing tower (2), the first desulfurization tower (3), and the second desulfurization tower (4) is larger than the diameter of the spray section (39).

4. The flue gas desulfurization system for a side-blown reduction smelting furnace according to claim 1, characterized in that, The gas lifter layer (41) includes at least one gas lifter (42), which allows flue gas to pass upward while preventing liquid from dripping downward; the drain outlet (44) is located at the lowest point of the edge of the gas lifter layer (41).

5. The flue gas desulfurization system for a side-blown reduction smelting furnace according to claim 1, characterized in that, The oxidation tank (7) is modified from the first-stage power wave desulfurization tower in the original side-blown reduction smelting furnace flue gas desulfurization system. An oxidation tank induced draft fan (12) is provided on its top. The inlet of the oxidation tank induced draft fan (12) is connected to the top of the oxidation tank (7), and its outlet is connected to the flue gas inlet of the second desulfurization tower (4) to draw the aeration tail gas in the oxidation tank (7) back to the second desulfurization tower (4).

6. The flue gas desulfurization system for a side-blown reduction smelting furnace according to claim 1, characterized in that, It also includes a slurry settling and reuse unit; the slurry settling and reuse unit includes a washing settling tank (19) and a washing settling liquid transfer pump (29), the inlet of the washing settling tank (19) is connected to the outlet of the washing tower (2), the inlet of the washing settling liquid transfer pump (29) is connected to the supernatant outlet of the washing settling tank (19), and its outlet is connected to the storage section (38) of the washing tower (2).

7. The flue gas desulfurization system for a side-blown reduction smelting furnace according to claim 1, characterized in that, It also includes an emergency spray unit, which includes an elevated water tank (22), the inlet of which is connected to the process water tank (21), and its outlet is connected to the flue gas inlet pipe of the scrubbing tower (2).

8. The flue gas desulfurization system for a side-blown reduction smelting furnace according to claim 1, characterized in that, It also includes a gypsum dewatering unit, a process water unit, and a wastewater collection unit; The gypsum dewatering unit includes a cyclone pump (33), a hydrocyclone (9), a vacuum belt filter (10) and a vacuum pump (11) connected in sequence by pipes, as well as a clear liquid tank (20) and a clear liquid pump (30). The vacuum pump (11) is connected to a circulating cooling water pipeline. The inlet of the clear liquid tank (20) is connected to the filtrate outlet of the vacuum belt filter (10), and the outlet of the clear liquid pump (30) is connected to the lime slurry mixing tank (17). The process water unit includes a process water tank (21) and a process water pump (31). The outlet of the process water pump (31) is connected to the lime slurry mixing tank (17), the high-level water tank (22), and each flushing point in the system. The sewage collection unit includes a pit (23) and a pit pump (32), the inlet of which is connected to the pit (23) and the outlet of which is connected to the lime mixing tank (17).

9. The flue gas desulfurization method for a flue gas desulfurization system for a side-blown reduction smelting furnace according to any one of claims 1-8, characterized in that, Includes the following steps: S1. Flue gas flows sequentially through scrubbing tower (2), first desulfurization tower (3), and second desulfurization tower (4), and comes into contact with lime slurry sprayed in each tower to remove sulfur dioxide. S2, lime slurry pump (28) sends fresh lime slurry into the first desulfurization tower (3) and the second desulfurization tower (4) respectively; the circulating slurry at the bottom of the storage section (38) of the second desulfurization tower (4) is transferred to the first desulfurization tower (3) through the connecting pipe. S3. Part of the circulating slurry at the bottom of the storage section (38) of the first desulfurization tower (3) is sent to the oxidation tank (7) through the desulfurization circulation branch (46), and works together with the first aeration device at the bottom of the storage section (38) of the first desulfurization tower (3) and the second aeration device in the oxidation tank (7) to carry out two-stage oxidation; the oxidized slurry is dewatered by the cyclone pump (33), the hydrocyclone (9), and the vacuum belt filter (10), and the filtrate enters the clear liquid tank (20), and is then sent back to the lime slurry mixing tank (17) by the clear liquid pump (30) for reuse; S4. The slurry discharged from the washing tower (2) enters the washing settling tank (19) for settling. The supernatant is sent back to the storage section (38) of the washing tower (2) by the washing settling liquid transfer pump (29) for recycling. In the second desulfurization tower (4), the backwash pump (14) draws backwash water from the backwash circulation tank (13) and sends it to the backwash layer (43). The water after rinsing returns to the backwash circulation tank (13) through the drain port (44) at the edge of the air riser layer (41), forming a closed loop.

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