Flue gas treatment system for smelting ferronickel by using RKEF method

Abstract

The utility model provides a flue gas treatment system for smelting ferronickel by using an RKEF method. The flue gas treatment system comprises a submerged arc furnace, a water cooling flue, a first settling chamber, a rotary kiln, a drying kiln, a PNCR denitration device, a first dust removal device, a desulfurization device and a second dust removal device. The water cooling flue and the first settling chamber are arranged to cool the high-temperature raw gas generated by the submerged arc furnace and remove dust in the raw gas, so that the risk of flue gas treatment is reduced. By arranging the PNCR denitration device, the solid denitration agent is sprayed into the drying kiln to remove NOx in the second flue gas generated by the drying kiln, and devices such as an ammonia system and a denitration tower do not need to be added, so that the reduction of the flue gas treatment cost is facilitated. The flue gas treatment system is not provided with a heat exchange device, a waste heat utilization device and a coal gas recovery device, the number of devices in the system is small, and therefore the occupied area of the flue gas treatment system can be reduced, and the flue gas treatment cost can be reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of flue gas treatment, in particular to a flue gas treatment system for smelting nickel iron using a RKEF method. Background Art

[0002] Laterite nickel ore accounts for 70% of the total land-based nickel reserves, among which the RKEF (rotary kiln-submerged arc furnace) process is currently the most mature smelting process for processing laterite nickel ore. The RKEF process uses laterite nickel ore and semi-coke as raw materials to reduce nickel oxide, and the nickel and iron generated by the reaction dissolve into each other to form nickel-iron products. The main equipment includes a drying rotary kiln, a roasting and reduction rotary kiln, and a closed / semi-closed submerged arc furnace. The RKEF smelting of laterite nickel ore produces raw gas generated by the submerged arc furnace, and the high-temperature flue gas generated by the rotary kiln and the drying kiln contains a large amount of dust, SO2, CO and NO x and other pollutants.

[0003] The current mainstream flue gas treatment process essentially treats the flue gases from submerged arc furnaces, rotary kilns, and drying kilns separately. Submerged arc furnaces produce clean gas using a "cooling + bag filter" process. Rotary kiln flue gas is treated using a "cyclone / electrostatic precipitator + SCR denitrification" process. Drying kiln flue gas is treated using an "electrostatic precipitator / bag filter + wet desulfurization" process. This flue gas treatment method utilizes multiple cyclones, bag filters, and electrostatic precipitators. To balance the pressure between these devices, multiple additional fans are also required.

[0004] Chinese patent application publication number CN108411116A proposes a comprehensive flue gas treatment system and method for the RKEF (Reinforced Kerosene-Energy (RKEF)) smelting process of laterite nickel ore. This system utilizes a submerged arc furnace, a water-cooled flue, a first bag filter, a rotary kiln, a cyclone dust collector, a combustion air mixing chamber, a dryer, and a second bag filter to treat and comprehensively utilize the RKEF flue gas. The submerged arc furnace gas is purified by the first bag filter and then delivered to the rotary kiln via a fan for fuel. The hot flue gas from the rotary kiln is then passed through a cyclone dust collector and a fan to the combustion air mixing chamber of the drying kiln for supplemental heating. The drying kiln flue gas is ultimately purified by a second bag filter. This process utilizes the submerged arc furnace gas by applying it to the rotary kiln and then using the rotary kiln flue gas to supplemental heat in the drying kiln. However, a disadvantage of this process is the need for additional fans between the submerged arc furnace and the rotary kiln, and between the rotary kiln and the drying kiln, resulting in high overall energy consumption. The entire process system does not take into account the desulfurization and denitrification processes, making it difficult to achieve SO2 and NO x Emissions meet standards.

[0005] A Chinese patent application, published as CN214371794U, proposes a comprehensive flue gas treatment system for the RKEF nickel-iron production process. The system utilizes a "submersible furnace, settling chamber, air mixing chamber, first cyclone dust collector, denitrification device, drying kiln, second cyclone dust collector, and wet desulfurization tower" to treat the flue gas generated by the RKEF. This process combines purified submersible furnace gas with rotary kiln flue gas, which are then introduced into the drying kiln as hot air for supplemental heat. The process utilizes cyclone dust collectors throughout, resulting in low dust removal efficiency and difficulty meeting flue gas dust emission standards. An SCR denitrification device is added between the air mixing chamber and the drying kiln to fully utilize high temperatures for denitrification. However, the SCR reactor is a high-resistance device, requiring the addition of a pressure-regulating fan to adjust the system pressure balance, increasing equipment investment and system energy consumption.

[0006] A Chinese patent application, publication number CN213942674U, proposes a flue gas denitrification system for the RKEF (Relative Kiln Emitting Furnace) smelting process of laterite nickel ore. This system utilizes the high-temperature flue gas generated by the combined effects of a submerged arc furnace and a rotary kiln for denitrification. The SCR (Solidified Reactor) denitrification system eliminates the need for additional heat recovery, resulting in high denitrification efficiency. However, the SCR catalyst is susceptible to clogging due to the lack of dust removal from the flue gas. The SCR denitrification system also suffers from high operating resistance, requiring a booster fan to balance pressure, resulting in high energy consumption and the need for a separate SCR denitrification tower, which is complex.

[0007] Chinese patent application publication number CN107747873A proposes a gas purification and recovery system for a submerged arc furnace (SAC) using the RKEF process to smelt Nitrite. This system uses a combined cyclone and bag filter system to purify the raw gas generated by the furnace. The system utilizes multiple cyclone and bag filters, achieving excellent gas dust removal and high efficiency. However, the system requires multiple components, resulting in high overall resistance, the need for additional fans to balance system pressure, and high energy consumption. Utility Model Content

[0008] The main purpose of the utility model is to provide a flue gas treatment system for smelting nickel iron using the RKEF method, so as to solve the problems of complex equipment, high energy consumption and complex operation in the flue gas treatment process for smelting nickel iron using the RKEF method in the prior art.

[0009] In order to achieve the above-mentioned purpose, according to one aspect of the present invention, a flue gas treatment system for smelting nickel iron using the RKEF method is provided, the flue gas treatment system comprising: an ore-heating furnace having a high-temperature raw gas outlet, the ore-heating furnace generating high-temperature raw gas; a water-cooled flue having a high-temperature raw gas inlet and a low-temperature raw gas outlet; the high-temperature raw gas outlet is connected to the high-temperature raw gas inlet; the water-cooled flue is used to cool the high-temperature raw gas to obtain low-temperature raw gas; a first settling chamber having a low-temperature raw gas inlet and a purified raw gas outlet, the low-temperature raw gas outlet is connected to the low-temperature raw gas inlet, and the first settling chamber is used to cool the low-temperature raw gas The rotary kiln is provided with a purified raw gas inlet and a first flue gas outlet, the purified raw gas outlet is connected to the purified raw gas inlet, and the rotary kiln is used to use the purified raw gas as an auxiliary fuel to produce a first flue gas; the drying kiln is provided with a first flue gas inlet, an outlet and a solid denitrification agent inlet, the first flue gas outlet is connected to the first flue gas inlet, and the drying kiln is used to use the first flue gas as an auxiliary hot air to produce a second flue gas; the PNCR denitrification device is provided with a solid denitrification agent outlet, the solid denitrification agent outlet is connected to the solid denitrification agent inlet, and the denitrification device is used to spray the solid denitrification agent into the drying kiln to remove NO in the second flue gas. x to obtain denitrification flue gas; a first dust removal device, having a denitrification flue gas inlet and a purified denitrification flue gas outlet, the denitrification flue gas outlet is connected to the denitrification flue gas inlet, and the dust removal device is used to perform a first dust removal on the denitrification flue gas to obtain purified denitrification flue gas; a desulfurization device, having a purified denitrification flue gas inlet and a desulfurization flue gas outlet, the purified denitrification flue gas outlet is connected to the purified denitrification flue gas inlet, and the desulfurization device is used to remove sulfur dioxide from the purified denitrification flue gas to obtain desulfurized flue gas; a second dust removal device, having a desulfurization flue gas inlet and a purified gas outlet, the desulfurization flue gas outlet is connected to the desulfurization flue gas inlet, and the second dust removal device is used to perform a second dust removal on the desulfurization flue gas to obtain purified gas.

[0010] Furthermore, the low-temperature raw gas outlet is connected to the low-temperature raw gas inlet via a first flue, and a first regulating valve is provided on the first flue for regulating the pressure of the low-temperature raw gas outlet.

[0011] Furthermore, the purified raw gas outlet and the purified raw gas inlet are connected via a second flue, and the second flue is composed of 2 to 4 branch pipes.

[0012] Furthermore, the flue gas treatment system further includes a combustion chamber, which is arranged on the flow path connecting the first flue gas outlet and the first flue gas inlet, and the combustion chamber is used to remove residual carbon monoxide in the first flue gas.

[0013] Furthermore, the rotary kiln and the combustion chamber are connected via a third flue, and a second regulating valve is provided on the third flue for regulating the pressure of the first flue gas outlet; an emergency exhaust device is provided on the third flue.

[0014] Furthermore, the above-mentioned first dust removal device includes: a second settling chamber, which is used to perform coarse dust removal on the denitrification flue gas to obtain coarsely purified denitrification flue gas, and the second settling chamber has a denitrification flue gas inlet and a coarsely purified denitrification flue gas outlet; an electrostatic precipitator, which has a coarsely purified denitrification flue gas inlet and a purified denitrification flue gas outlet, and the coarsely purified denitrification flue gas outlet is connected to the coarsely purified denitrification flue gas inlet, and the electrostatic precipitator is used to perform fine dust removal on the coarsely purified denitrification flue gas to obtain purified denitrification flue gas.

[0015] Furthermore, the above-mentioned flue gas treatment system also includes a fan, which is arranged on the flow path connecting the purified denitrification flue gas outlet and the purified denitrification flue gas inlet, and is used to provide power for the entire flue gas purification system.

[0016] Furthermore, an emergency discharge device and an explosion relief valve are provided on the top of the first settling chamber.

[0017] Furthermore, a carbon monoxide monitoring device is provided at the denitrification flue gas inlet.

[0018] Furthermore, the flue gas treatment system further includes a chimney, which is arranged at the purified gas outlet and is used to discharge the purified gas.

[0019] By applying the technical solution of the present utility model, the present application cools down the high-temperature raw gas generated by the electric arc furnace and removes large particles of dust in the raw gas by setting a water-cooled flue and a first settling chamber, thereby helping to reduce the danger of flue gas treatment. The purified raw gas outlet is connected to the purified raw gas inlet, and the purified raw gas is introduced into the rotary kiln as an auxiliary fuel, which helps to reduce the consumption of natural gas in the rotary kiln, and does not require the addition of gas purification equipment and pressure-regulating fans. The first flue gas outlet is connected to the first flue gas inlet, and the first flue gas generated by the rotary kiln is introduced into the drying kiln as auxiliary hot air, which helps to further reduce energy loss, and does not require the addition of dust removal and denitrification devices and pressure-regulating fans. By setting up a PNCR denitrification device, a solid denitrification agent is sprayed into the drying kiln to remove NO in the second flue gas generated by the drying kiln. x , there is no need to add an ammonia system and a denitrification tower, thus helping to reduce the cost of flue gas treatment. The flue gas treatment system of the present application does not have heat exchange, waste heat utilization and coal gas recovery devices. The system has fewer equipment, which helps to reduce the floor space of the flue gas treatment system and reduce the cost of flue gas treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings constituting part of this application are provided to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are provided to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0021] Figure 1 A schematic structural diagram of a flue gas treatment system in an embodiment of the present application is shown;

[0022] The above drawings include the following reference numerals:

[0023] 10. Submerged arc furnace; 20. Water-cooled flue; 30. First settling chamber; 40. Rotary kiln; 50. Drying kiln; 60. PNCR denitrification device; 70. First dust removal device; 71. Second settling chamber; 72. Electrostatic precipitator; 80. Desulfurization device; 90. Second dust removal device; 100. Combustion chamber; 110. Fan; 120. Chimney. DETAILED DESCRIPTION

[0024] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0025] As analyzed in the background technology of this application, the flue gas treatment process for smelting nickel iron using the RKEF method in the prior art has problems such as complex equipment, high energy consumption and complex operation. In order to solve the above problems, this application provides a flue gas treatment system for smelting nickel iron using the RKEF method.

[0026] It should be noted that PNCR is the abbreviation for polymer selective catalytic reduction.

[0027] In a typical embodiment of the present application, a flue gas treatment system for smelting nickel iron using the RKEF method is provided, such as Figure 1 As shown, the flue gas treatment system includes: an ore-heating furnace 10, having a high-temperature raw gas outlet, and the ore-heating furnace 10 generates high-temperature raw gas; a water-cooled flue 20, having a high-temperature raw gas inlet and a low-temperature raw gas outlet; the high-temperature raw gas outlet is connected to the high-temperature raw gas inlet; the water-cooled flue 20 is used to cool the high-temperature raw gas to obtain low-temperature raw gas; a first settling chamber 30, having a low-temperature raw gas inlet and a purified raw gas outlet, the low-temperature raw gas outlet is connected to the low-temperature raw gas inlet, and the first settling chamber 30 is used to settle the low-temperature raw gas to obtain purified raw gas; a rotary kiln 40, having a purified raw gas inlet The rotary kiln 40 is configured to use the purified raw gas as an auxiliary fuel to generate the first flue gas; the drying kiln 50 has a first flue gas inlet, a denitrified flue gas outlet, and a solid denitrifying agent inlet, the first flue gas outlet is connected to the first flue gas inlet, and the drying kiln 50 is configured to use the first flue gas as auxiliary hot air to generate the second flue gas; the PNCR denitrification device 60 has a solid denitrifying agent outlet, the solid denitrifying agent outlet is connected to the solid denitrifying agent inlet, and the denitrification device 60 is configured to spray the solid denitrifying agent into the drying kiln 50 to remove NO in the second flue gas. xto obtain denitrification flue gas; a first dust removal device 70, having a denitrification flue gas inlet and a purified denitrification flue gas outlet, the denitrification flue gas outlet is connected to the denitrification flue gas inlet, and the dust removal device 70 is used to perform a first dust removal on the denitrification flue gas to obtain purified denitrification flue gas; a desulfurization device 80, having a purified denitrification flue gas inlet and a desulfurization flue gas outlet, the purified denitrification flue gas outlet is connected to the purified denitrification flue gas inlet, and the desulfurization device 80 is used to remove sulfur dioxide from the purified denitrification flue gas to obtain desulfurized flue gas; a second dust removal device 90, having a desulfurization flue gas inlet and a purified gas outlet, the desulfurization flue gas outlet is connected to the desulfurization flue gas inlet, and the second dust removal device 90 is used to perform a second dust removal on the desulfurization flue gas to obtain purified gas.

[0028] In the present application, a water-cooled flue and a first settling chamber are provided to cool the high-temperature raw gas (temperature of 800-1000°C) generated by the electric arc furnace to obtain low-temperature raw gas (temperature of no more than 700°C), and the large particles of dust in the low-temperature raw gas are removed, thereby helping to reduce the danger of flue gas treatment. The purified raw gas outlet is connected to the purified raw gas inlet, and the purified raw gas is introduced into the rotary kiln as an auxiliary fuel, which helps to reduce the consumption of natural gas in the rotary kiln, and there is no need to add gas purification equipment and pressure-regulating fans. The first flue gas outlet is connected to the first flue gas inlet, and the first flue gas generated by the rotary kiln is introduced into the drying kiln as auxiliary hot air, which helps to further reduce energy loss, and there is no need to add dust removal and denitrification equipment and pressure-regulating fans. By providing a PNCR denitrification device, a solid denitrification agent is sprayed into the drying kiln to remove NO in the second flue gas generated by the drying kiln. x (nitrogen oxides, x is usually 1-2), eliminating the need for additional ammonia systems and denitrification towers, thereby helping to reduce flue gas treatment costs. The flue gas treatment system of the present application does not require heat exchange, waste heat utilization, or gas recovery equipment. The system has fewer devices, thereby helping to reduce the footprint of the flue gas treatment system and reduce the cost of flue gas treatment.

[0029] The above-mentioned water-cooled flue can adopt the method of vaporization cooling flue or membrane water-cooled wall, including but not limited to, the above-mentioned desulfurization device is a wet desulfurization tower, and the second dust removal device is a wet electrostatic precipitator, which helps to remove droplets and solid alkali in the desulfurized flue gas.

[0030] In one embodiment of the present application, the above-mentioned low-temperature raw gas outlet is connected to the low-temperature raw gas inlet through a first flue, and a first regulating valve is provided on the first flue to control the pressure of the low-temperature raw gas outlet at -20Pa~-60Pa.

[0031] Providing the first regulating valve helps to control the flow rate of the low-temperature raw gas, thereby helping to improve the settling efficiency of the low-temperature raw gas and the safety of flue gas treatment.

[0032] In order to further improve the settling efficiency of low-temperature raw coal gas and the safety of flue gas treatment, in one embodiment of the present application, it is preferred that the direction of the above-mentioned first flue is vertical or inclined, the inclination angle of the first flue to the horizontal direction is not less than 60°, the outer wall of the first flue is made of carbon steel, the outer wall thickness of the first flue is ≥8mm, the lining thickness of the first flue is greater than 50mm, the lining material is heavy refractory castable, the mass proportion of Al2O3 in the refractory castable is greater than 75%, and the volume density of the refractory castable is greater than 2.0g / cm 3 The first regulating valve adopts butterfly valve type, and the material of valve body and valve plate is 310s stainless steel.

[0033] In order to control the flow rate of the purified raw gas, in one embodiment of the present application, it is preferred that the above-mentioned purified raw gas outlet is connected to the purified raw gas inlet through a second flue, and the second flue is composed of 2 to 4 branch pipes. The branch pipes are evenly distributed around the kiln head combustion system (natural gas nozzle / coal powder nozzle) of the rotary kiln. The direction of each branch pipe is inclined, and the inclination angle of each branch pipe to the horizontal direction is not less than 60°. If a straight pipe section is set, it should be shortened as much as possible. The material of the outer wall of the branch pipe is carbon steel, the thickness of the outer wall is ≥8mm, the thickness of the inner lining of the branch pipe is >50mm, and the material of the inner lining is heavy refractory castable. The mass proportion of Al2O3 in the refractory castable is >75%, and the volume density of the refractory castable is >2.0g / cm 3 .

[0034] In order to further reduce the carbon monoxide content in the first flue gas, in one embodiment of the present application, the flue gas treatment system further includes a combustion chamber 100, which is arranged on the flow path connecting the first flue gas outlet and the first flue gas inlet, and the combustion chamber 100 is used to remove the residual carbon monoxide in the first flue gas.

[0035] In order to control the flow rate of the first flue gas, in one embodiment of the present application, the rotary kiln 40 is preferably connected to the combustion chamber 100 via a third flue. The third flue is provided with a second regulating valve for controlling the pressure of the first flue gas outlet between -150Pa and -250Pa. The third flue is also provided with an emergency exhaust device to facilitate the temporary discharge of emergency flue gas. The third flue is tilted, with an inclination angle of not less than 60° to the horizontal direction. The outer wall of the third flue is made of Q345 or 20G carbon steel, with a thickness of ≥8mm. The second regulating valve is a butterfly valve, and the valve body and valve plate are made of 304 / 310s stainless steel.

[0036] In one embodiment of the present application, the above-mentioned first dust removal device 70 includes: a second settling chamber 71, which is used to perform coarse dust removal on the denitrification flue gas to obtain coarsely purified denitrification flue gas, and the second settling chamber 71 has a denitrification flue gas inlet and a coarsely purified denitrification flue gas outlet; an electrostatic precipitator 72, which has a coarsely purified denitrification flue gas inlet and a purified denitrification flue gas outlet, and the coarsely purified denitrification flue gas outlet is connected to the coarsely purified denitrification flue gas inlet, and the electrostatic precipitator 72 is used to perform fine dust removal on the coarsely purified denitrification flue gas to obtain purified denitrification flue gas.

[0037] The installation of a second settling chamber and an electrostatic precipitator (ESP) helps further reduce dust concentration in the purified denitrification flue gas. The ESP is preferably a high-temperature ESP with a temperature resistance of 420°C or higher. The second settling chamber's housing and ash hopper's outer wall should be made of carbon steel, with an ash hopper outer wall thickness of 10mm or higher and a bottom hopper inclination angle of 60° or higher.

[0038] In one embodiment of the present application, the above-mentioned flue gas treatment system also includes a fan 110, which is arranged in the flow path connecting the purified denitrification flue gas outlet and the purified denitrification flue gas inlet, and is used to provide power for the entire flue gas purification system and control the pressure of the purified denitrification flue gas outlet at -1500Pa~-2000Pa.

[0039] The flue gas treatment system of this application is equipped with only one fan, and the positive pressure at the fan outlet is 2500-3000 Pa, which helps to reduce the pressure loss of the entire flue gas treatment system to less than 5000 Pa, thereby helping to reduce energy consumption. The fan is preferably a variable frequency speed-regulating fan, and the air volume and pressure loss margin coefficient of the variable frequency speed-regulating fan is ≥20%.

[0040] In one embodiment of the present application, an emergency discharge device and an explosion relief valve are provided at the top of the first settling chamber 30. The cylinder of the first settling chamber is cylindrical, the inclination angle of the ash hopper at the bottom of the cylinder is ≥60°, the outer wall of the cylinder is made of carbon steel, the outer wall thickness of the cylinder is ≥10 mm, the lining thickness of the cylinder is >50 mm, and the lining material is heavy refractory castable, the mass proportion of Al2O3 in the refractory castable is >75%, and the volume density of the refractory castable is >2.0 g / cm 3 .

[0041] An emergency discharge device is provided at the top of the first settling chamber 30 to help temporarily discharge accidental flue gas. An explosion relief valve is provided at the top of the first settling chamber 30. When the pressure is ≥5000Pa, the explosion relief valve is activated, which helps to improve the safety of the flue gas treatment system.

[0042] In one embodiment of the present application, a carbon monoxide monitoring device is provided at the above-mentioned denitrification flue gas inlet.

[0043] By installing a carbon monoxide monitoring device at the denitrification flue gas inlet, the fan will be stopped when the volume concentration of CO is greater than 2%, which helps reduce the probability of CO being discharged from the system.

[0044] In one embodiment of the present application, the flue gas treatment system further includes a chimney 120 , which is provided at the purified gas outlet and is used to discharge the purified gas.

[0045] This application discharges the purified gas by setting up a chimney.

[0046] In one embodiment of the present application, when the drying kiln is shut down, the PNCR denitrification device is connected to the rotary kiln, and the PNCR denitrification device provides a solid denitrification agent to the rotary kiln. The first flue gas outlet is connected to the denitrification flue gas inlet through a fourth pipe. The flue gas generated by the rotary kiln is passed into the first dust removal device. A carbon monoxide monitoring device is provided on the fourth pipe. When the volume concentration of CO is greater than 2%, the fan is stopped, which helps to reduce the probability of CO being discharged out of the system.

[0047] In another typical embodiment of the present application, a flue gas treatment method for smelting nickel iron using the RKEF method is provided, and the flue gas is treated by the aforementioned flue gas treatment system. The flue gas treatment method includes: step S1, cooling the high-temperature raw gas generated by the ore-fired furnace to obtain low-temperature raw gas; step S2, settling the low-temperature raw gas to obtain purified raw gas; step S3, using the purified raw gas as auxiliary fuel in the rotary kiln to generate a first flue gas; step S4, using the first flue gas as auxiliary hot air in the drying kiln to generate a second flue gas; step S5, spraying a solid denitrification agent into the second flue gas to remove NO x to obtain denitrification flue gas; step S6, performing a first dust removal on the denitrification flue gas to obtain purified denitrification flue gas; step S7, removing sulfur dioxide from the purified denitrification flue gas to obtain desulfurized flue gas; step S8, performing a second dust removal on the desulfurized flue gas to obtain purified gas.

[0048] In step S1 and step S2, the high-temperature raw gas generated by the ore-fired furnace is cooled and large particles of dust in the raw gas are removed, thereby helping to reduce the risk of flue gas treatment. In step S3, the purified raw gas is introduced into the rotary kiln as auxiliary fuel, which helps to reduce the consumption of natural gas in the rotary kiln and does not require additional gas purification equipment and pressure-regulating fans. In step S4, the first flue gas generated by the rotary kiln is introduced into the drying kiln as auxiliary hot air, which helps to further reduce energy loss and does not require additional dust removal and denitrification equipment and pressure-regulating fans. In step S5, the solid denitrification agent removes NO in the second flue gas. x Reduced to N2 and H2 O. The flue gas treatment method of the present application has the advantages of simple process and low cost.

[0049] In order to improve the safety of flue gas treatment, in one embodiment of the present application, the temperature of the above-mentioned low-temperature raw gas is preferably not more than 700°C; and / or the temperature of the high-temperature raw gas is 800-1000°C; and / or the flow rate of the low-temperature raw gas is 4-8m / s.

[0050] In order to improve the sedimentation efficiency, in one embodiment of the present application, it is preferred that the first sedimentation chamber is used to sediment the low-temperature raw gas to obtain purified raw gas, the wind speed of the cylinder section of the first sedimentation chamber is 3 to 5 m / s, and the residence time of the low-temperature raw gas in the first sedimentation chamber exceeds 2s.

[0051] In order to improve the efficiency of converting carbon monoxide in the purified raw gas into carbon dioxide, in one embodiment of the present application, the flow rate of the purified raw gas is 4 to 8 m / s.

[0052] In order to improve the utilization rate of the first flue gas, in one embodiment of the present application, the flow rate of the first flue gas is preferably 4 to 8 m / s.

[0053] In order to further reduce the carbon monoxide content in the first flue gas, in one embodiment of the present application, in the above step S4, the first flue gas is burned and used as auxiliary hot air in the drying kiln to generate the second flue gas.

[0054] In one embodiment of the present application, the first dust removal includes: step S61, performing coarse dust removal on the denitrification flue gas to obtain coarsely purified denitrification flue gas; step S62, performing fine dust removal on the coarsely purified denitrification flue gas to obtain purified denitrification flue gas.

[0055] Performing coarse dust removal on the denitrification flue gas first and then fine dust removal can help further reduce the concentration of dust in the purified denitrification flue gas.

[0056] In order to further improve the efficiency of the first dust removal, in one embodiment of the present application, it is preferred that the above-mentioned second settling chamber is used to perform coarse dust removal on the denitrification flue gas to obtain coarsely purified denitrification flue gas, the wind speed of the box section of the second settling chamber is 3 to 5 m / s, and the denitrification flue gas stays in the second settling chamber for more than 2 seconds; and / or, an electrostatic precipitator is used to perform fine dust removal on the coarsely purified denitrification flue gas to obtain purified denitrification flue gas, and the filtration wind speed of the electrostatic precipitator is 0.5 to 1.0 m / s.

[0057] In order to improve the desulfurization efficiency, in one embodiment of the present application, it is preferred that in the above step S7, a desulfurizer is used to remove sulfur dioxide in the purified denitrification flue gas to obtain desulfurized flue gas, and the desulfurizer is preferably a calcium-based desulfurizer or a sodium-based desulfurizer; it is further preferred that the desulfurizer is selected from any one or more of calcium hydroxide, calcium oxide and sodium hydroxide.

[0058] In order to improve the desulfurization efficiency, in one embodiment of the present application, it is preferred that in the above step S5, the temperature of the solid denitrification agent is ≥750°C, preferably the temperature of the solid denitrification agent is 800°C to 900°C, and / or the solid denitrification agent is a polymer solid denitrification agent; preferably, the polymer solid denitrification agent is selected from any one or more of the powdered polymer solid denitrification agent of Jutai, the granular polymer solid denitrification agent of Juyibang and the spherical polymer solid denitrification agent of Felix.

[0059] The beneficial effects of the present application will be further illustrated below with reference to examples.

[0060] Example 1

[0061] The RKEF process is used to smelt laterite nickel ore to produce nickel-iron alloy. The submerged arc furnace produces high-temperature raw gas with a flue gas volume of 60,000 Nm 3 / h, temperature 900℃, dust content 26.5g / Nm 3 , CO volume fraction is 30%. The rotary kiln produces the first flue gas, the flue gas volume is 205000Nm 3 / h, temperature is 350℃, dust content is 28g / Nm 3 The drying kiln produces the second flue gas, with a flue gas volume of 306000Nm 3 / h, temperature is 160℃, SO2 is 650mg / Nm 3 , dust content is 17.5g / Nm 3 , NO x 450mg / Nm 3 .

[0062] Use Figure 1The flue gas treatment system shown treats the flue gas generated above. In the flue gas treatment system, the ore-fired furnace 10 has a high-temperature raw gas outlet, the water-cooled flue 20 has a high-temperature raw gas inlet and a low-temperature raw gas outlet; the high-temperature raw gas outlet is connected to the high-temperature raw gas inlet; the first settling chamber 30 has a low-temperature raw gas inlet and a purified raw gas outlet, and the low-temperature raw gas outlet is connected to the low-temperature raw gas inlet; the rotary kiln 40 has a purified raw gas inlet and a first flue gas outlet, and the purified raw gas outlet is connected to the purified raw gas inlet; the drying kiln 50 has a first flue gas inlet, a denitrification flue gas outlet and a solid denitrification agent inlet, and the first flue gas outlet is connected to the first flue gas inlet; the PNCR denitrification device 60 has a solid denitrification agent outlet, and the solid denitrification agent outlet is connected to the solid denitrification agent inlet; the first dust removal device 70 has a denitrification flue gas inlet and a purified denitrification flue gas outlet, and the denitrification flue gas outlet is connected to the denitrification flue gas inlet; the first dust removal device 70 includes a second settling chamber 71 and an electrostatic precipitator 72. 2. The second settling chamber 71 has a denitrification flue gas inlet and a roughly purified denitrification flue gas outlet. The electrostatic precipitator 72 has a roughly purified denitrification flue gas inlet and a purified denitrification flue gas outlet. The roughly purified denitrification flue gas outlet is connected to the roughly purified denitrification flue gas inlet. The desulfurization device 80 has a purified denitrification flue gas inlet and a desulfurization flue gas outlet. The purified denitrification flue gas outlet is connected to the purified denitrification flue gas inlet. The second dust removal device 90 has a desulfurization flue gas inlet and a purified gas outlet. The desulfurization flue gas outlet is connected to the desulfurization flue gas inlet. The low-temperature raw coal gas outlet is connected to the low-temperature raw coal gas inlet through a first flue. A first regulating valve is provided on the first flue. The purified raw coal gas outlet is connected to the purified raw coal gas inlet through a second flue. The combustion chamber 100 is provided on the flow path connecting the first flue gas outlet and the first flue gas inlet. The rotary kiln 40 and the combustion chamber 100 are connected through a third flue. A second regulating valve is provided on the third flue. An emergency exhaust device is provided on the third flue. The fan 110 is arranged on the flow path connecting the purified denitrification flue gas outlet and the purified denitrification flue gas inlet. An emergency exhaust device and an explosion relief valve are set on the top of the first settling chamber 30. When the pressure is ≥5000Pa, the explosion relief valve is started. A carbon monoxide monitoring device is set at the denitrification flue gas inlet. When the volume concentration of CO is greater than 2%, an alarm is issued and the fan operation is stopped. The chimney 120 is set at the purified gas outlet.

[0063] Step S1, cooling the high-temperature raw gas generated by the ore-fired furnace 10 through the water-cooling flue 20 to obtain low-temperature raw gas;

[0064] Step S2, settling the low-temperature raw gas in the first settling chamber 30 to obtain purified raw gas;

[0065] Step S3, using the purified raw gas as auxiliary fuel in the rotary kiln 40 to generate first flue gas;

[0066] Step S4, burning the first flue gas in the combustion chamber 100 and using it as auxiliary hot air in the drying kiln 50 to generate second flue gas;

[0067] Step S5: Use the PNCR denitrification device 60 to spray the solid denitrification agent into the second flue gas to remove NO x to obtain denitrified flue gas;

[0068] In step S6, the first dust removal device 70 includes a second settling chamber 71 and an electrostatic precipitator 72, and the denitrified flue gas is subjected to rough dust removal in the second settling chamber 71 to obtain roughly purified denitrified flue gas; and the roughly purified denitrified flue gas is subjected to fine dust removal in the electrostatic precipitator 72 to obtain purified denitrified flue gas;

[0069] Step S7: The purified denitrified flue gas is sent to the desulfurization device 80 (wet desulfurization tower) by the fan 110 to remove sulfur dioxide from the purified denitrified flue gas to obtain desulfurized flue gas;

[0070] In step S8 , the desulfurized flue gas is subjected to a second dust removal in a second dust removal device 90 (wet electrostatic precipitator) to obtain purified gas, which is then discharged to the outside through a chimney 120 .

[0071] Among them, the temperature of the cooled raw gas is 700℃, the pressure of the low-temperature raw gas outlet is controlled at -50Pa, the pressure of the first flue gas outlet is controlled at -160Pa, the negative pressure of the electrostatic precipitator outlet is controlled at -1600Pa, and the positive pressure of the fan outlet is controlled at 2600Pa.

[0072] The water-cooled flue adopts a patterned water-cooled wall method.

[0073] The flow rate of low-temperature raw gas is controlled at 6m / s. The first flue is tilted at an angle of 65° to the horizontal direction. The outer wall is made of carbon steel with a thickness of 10mm and an inner lining of 100mm. The inner lining is made of heavy refractory castable. The mass proportion of Al2O3 in the refractory castable is 80%, and the volume density of the refractory castable is 2.6g / cm 3 The first regulating valve adopts butterfly valve type, and the material of valve body and valve plate is 310s stainless steel.

[0074] The first settling chamber adopts a cylindrical shell, with a cross-section wind speed of 5m / s and a residence time of low-temperature raw gas of 2.5s. The bottom ash hopper has an inclination angle of 60°, an outer wall of carbon steel, an outer wall thickness of 12mm, and an inner lining thickness of 100mm. The inner lining material is heavy refractory castable, with Al2O3 accounting for 80% by mass and a bulk density of 2.6g / cm 3 ;

[0075] The second pipeline consists of 4 branches, evenly distributed around the natural gas nozzle of the rotary kiln. The flow rate of the purified raw gas in the branch is 8m / s. The pipeline is arranged at an angle of 60° to the horizontal direction. The end of the branch is connected to the kiln head of the rotary kiln with a straight pipe section with a length of 1.4m. The outer wall of the branch is made of carbon steel with a thickness of 10mm and a thickness of 100mm. The inner lining is made of heavy refractory castable. The mass proportion of Al2O3 in the refractory castable is 80%, and the volume density of the refractory castable is 2.6g / cm 3 .

[0076] The flow rate of the first flue gas is 6m / s. The third pipe is arranged as a herringbone pipe with an inclination angle of 60° to the horizontal direction. The outer wall is made of 20G carbon steel with a thickness of 10mm. The second regulating valve is a butterfly valve type, and the valve body and valve plate are made of 304 stainless steel.

[0077] The box body and outer wall of the ash hopper of the second settling chamber are made of Q345 carbon steel, the thickness of the outer wall is 12mm, the wind speed of the box section is 5m / s, the residence time of the denitrification flue gas is 2.6s, and the inclination angle of the bottom ash hopper is 60°.

[0078] The filtration wind speed of the electrostatic precipitator is 0.6m / s.

[0079] The fan's air volume and pressure loss margin coefficient is 20%, and the air volume is 600000m 3 / h, wind pressure is 5500Pa.

[0080] Calcium hydroxide is used as the desulfurizer, and the denitrification adopts the dry denitrification process of Changzhou Taiju Company. The solid denitrification agent is Jutai's powdered polymer solid denitrification agent, and the temperature of the solid denitrification agent is 800℃.

[0081] Example 2

[0082] The RKEF process is used to smelt laterite nickel ore to produce nickel-iron alloy. The submerged arc furnace produces high-temperature raw gas with a flue gas volume of 13000Nm 3 / h, temperature 1000℃, dust content 35g / Nm 3 , CO volume fraction is 55%. The rotary kiln produces the first flue gas, the flue gas volume is 190000Nm 3 / h, temperature is 300℃, dust content is 40g / Nm 3 The drying kiln produces the second flue gas, with a flue gas volume of 390,000 Nm 3 / h, temperature is 150℃, SO2 is 1000mg / Nm 3 , dust content is 10g / Nm 3 , NO x 400mg / Nm 3 .

[0083] Use Figure 1 The flue gas treatment system shown treats the flue gas generated above. In the flue gas treatment system, the ore-fired furnace 10 has a high-temperature raw gas outlet, the water-cooled flue 20 has a high-temperature raw gas inlet and a low-temperature raw gas outlet; the high-temperature raw gas outlet is connected to the high-temperature raw gas inlet; the first settling chamber 30 has a low-temperature raw gas inlet and a purified raw gas outlet, and the low-temperature raw gas outlet is connected to the low-temperature raw gas inlet; the rotary kiln 40 has a purified raw gas inlet and a first flue gas outlet, and the purified raw gas outlet is connected to the purified raw gas inlet; the drying kiln 50 has a first flue gas inlet, a denitrification flue gas outlet and a solid denitrification agent inlet, and the first flue gas outlet is connected to the first flue gas inlet; the PNCR denitrification device 60 has a solid denitrification agent outlet, and the solid denitrification agent outlet is connected to the solid denitrification agent inlet; the first dust removal device 70 has a denitrification flue gas inlet and a purified denitrification flue gas outlet, and the denitrification flue gas outlet is connected to the denitrification flue gas inlet; the first dust removal device 70 includes a second settling chamber 71 and an electrostatic precipitator 72. 2. The second settling chamber 71 has a denitrification flue gas inlet and a roughly purified denitrification flue gas outlet. The electrostatic precipitator 72 has a roughly purified denitrification flue gas inlet and a purified denitrification flue gas outlet. The roughly purified denitrification flue gas outlet is connected to the roughly purified denitrification flue gas inlet. The desulfurization device 80 has a purified denitrification flue gas inlet and a desulfurization flue gas outlet. The purified denitrification flue gas outlet is connected to the purified denitrification flue gas inlet. The second dust removal device 90 has a desulfurization flue gas inlet and a purified gas outlet. The desulfurization flue gas outlet is connected to the desulfurization flue gas inlet. The low-temperature raw coal gas outlet is connected to the low-temperature raw coal gas inlet through a first flue. A first regulating valve is provided on the first flue. The purified raw coal gas outlet is connected to the purified raw coal gas inlet through a second flue. The combustion chamber 100 is provided on the flow path connecting the first flue gas outlet and the first flue gas inlet. The rotary kiln 40 and the combustion chamber 100 are connected through a third flue. A second regulating valve is provided on the third flue. An emergency exhaust device is provided on the third flue. The fan 110 is arranged on the flow path connecting the purified denitrification flue gas outlet and the purified denitrification flue gas inlet. An emergency exhaust device and an explosion relief valve are set on the top of the first settling chamber 30. When the pressure is ≥5000Pa, the explosion relief valve is started. A carbon monoxide monitoring device is set at the denitrification flue gas inlet. When the volume concentration of CO is greater than 2%, an alarm is issued and the fan operation is stopped. The chimney 120 is set at the purified gas outlet.

[0084] Step S1, cooling the high-temperature raw gas generated by the ore-fired furnace 10 through the water-cooling flue 20 to obtain low-temperature raw gas;

[0085] Step S2, settling the low-temperature raw gas in the first settling chamber 30 to obtain purified raw gas;

[0086] Step S3, using the purified raw gas as auxiliary fuel in the rotary kiln 40 to generate first flue gas;

[0087] Step S4, burning the first flue gas in the combustion chamber 100 and using it as auxiliary hot air in the drying kiln 50 to generate second flue gas;

[0088] Step S5: Use the PNCR denitrification device 60 to spray the solid denitrification agent into the second flue gas to remove NO x to obtain denitrified flue gas;

[0089] In step S6, the first dust removal device 70 includes a second settling chamber 71 and an electrostatic precipitator 72, and the denitrified flue gas is subjected to rough dust removal in the second settling chamber 71 to obtain roughly purified denitrified flue gas; and the roughly purified denitrified flue gas is subjected to fine dust removal in the electrostatic precipitator 72 to obtain purified denitrified flue gas;

[0090] Step S7: The purified denitrified flue gas is sent to the desulfurization device 80 (wet desulfurization tower) by the fan 110 to remove sulfur dioxide from the purified denitrified flue gas to obtain desulfurized flue gas;

[0091] In step S8 , the desulfurized flue gas is subjected to a second dust removal in a second dust removal device 90 (wet electrostatic precipitator) to obtain purified gas, which is then discharged to the outside through a chimney 120 .

[0092] Among them, the temperature of the cooled raw gas is 700℃, the pressure of the low-temperature raw gas outlet is controlled at -30Pa, the pressure of the first flue gas outlet is controlled at -180Pa, the negative pressure of the electrostatic precipitator outlet is controlled at -1800Pa, and the positive pressure of the fan outlet is controlled at 2800Pa.

[0093] The water-cooled flue adopts a vaporization cooling flue method.

[0094] The flow rate of low-temperature raw gas is controlled at 5m / s. The first flue is tilted at an angle of 63° to the horizontal direction. The outer wall is made of carbon steel with a thickness of 10mm and an inner lining of 120mm. The inner lining is made of heavy refractory castable. The mass proportion of Al2O3 in the refractory castable is 82%, and the volume density of the refractory castable is 3.0g / cm 3 The first regulating valve adopts butterfly valve type, and the material of valve body and valve plate is 310s stainless steel.

[0095] The first settling chamber adopts a cylindrical shell, with a cross-section wind speed of 4m / s and a residence time of 3.0s for low-temperature raw gas. The bottom ash hopper has an inclination angle of 60°, an outer wall of carbon steel, an outer wall thickness of 12mm, and an inner lining thickness of 120mm. The inner lining is made of heavy refractory castable, with Al2O3 accounting for 82% by mass and a bulk density of 3.0g / cm3. 3 ;

[0096] The second pipeline consists of three branches, evenly distributed around the natural gas nozzle of the rotary kiln. The flow rate of the purified raw gas in the branch is 6m / s. The pipeline is arranged at an angle of 65° to the horizontal direction. The end of the branch is connected to the kiln head of the rotary kiln with a straight pipe section with a length of 1.1m. The outer wall of the branch is made of carbon steel with a thickness of 10mm and a thickness of 120mm. The material of the lining is heavy refractory castable. The mass proportion of Al2O3 in the refractory castable is 82%, and the volume density of the refractory castable is 3.0g / cm 3 .

[0097] The flow rate of the first flue gas is 5m / s. The third pipe is arranged as a herringbone pipe with an inclination angle of 62° to the horizontal direction. The outer wall is made of Q345 carbon steel with a thickness of 10mm. The second regulating valve adopts a butterfly valve type, and the material of the valve body and valve plate is 310s stainless steel.

[0098] The box body and outer wall of the ash hopper of the second settling chamber are made of Q345 carbon steel, the thickness of the outer wall is 12mm, the wind speed of the box section is 4m / s, the residence time of the denitrification flue gas is 3.1s, and the inclination angle of the bottom ash hopper is 60°.

[0099] The filtration wind speed of the electrostatic precipitator is 0.5m / s.

[0100] The fan's air volume and pressure loss margin coefficient is 20%, and the air volume is 730000m 3 / h, wind pressure is 5800Pa.

[0101] Sodium hydroxide is used as the desulfurizer, Jiangsu Juyibang dry denitrification process is used for denitrification, and the solid denitrification agent is Juyibang's granular polymer solid denitrification agent. The temperature of the solid denitrification agent is 900℃.

[0102] Example 3

[0103] The difference from Example 1 is that the pressure of the low-temperature raw gas outlet is controlled at -20Pa, the flow rate of the low-temperature raw gas is 4m / s, the pressure of the first flue gas outlet is controlled at -150Pa, the flow rate of the first flue gas is 4m / s, the flow rate of the purified raw gas is 4m / s, and the pressure of the purified denitrification flue gas outlet is controlled at -1500Pa, and purified gas is finally obtained.

[0104] Example 4

[0105] The difference from Example 1 is that the pressure of the low-temperature raw gas outlet is controlled at -60Pa, the flow rate of the low-temperature raw gas is 8m / s, the pressure of the first flue gas outlet is controlled at -250Pa, the flow rate of the first flue gas is 8m / s, the flow rate of the purified raw gas is 8m / s, and the pressure of the purified denitrification flue gas outlet is controlled at -2000Pa, and purified gas is finally obtained.

[0106] Example 5

[0107] The difference from Example 1 is that the pressure of the low-temperature raw gas outlet is controlled at -70Pa, the flow rate of the low-temperature raw gas is 9m / s, the pressure of the first flue gas outlet is controlled at -260Pa, the flow rate of the first flue gas is 9m / s, the flow rate of the purified raw gas is 9m / s, and the pressure of the purified denitrification flue gas outlet is controlled at -2100Pa, and purified gas is finally obtained.

[0108] Example 6

[0109] The difference from Example 1 is that the wind speed of the cylinder section of the first settling chamber is 3m / s, the residence time of the low-temperature raw coal gas in the first settling chamber is 3s, the wind speed of the box section of the second settling chamber is 3m / s, the residence time of the denitrification flue gas in the second settling chamber is 3s, and finally purified gas is obtained.

[0110] Example 7

[0111] The difference from Example 1 is that the wind speed of the cylinder section of the first settling chamber is 6m / s, the residence time of the low-temperature raw coal gas in the first settling chamber is 2s, the wind speed of the box section of the second settling chamber is 6m / s, the residence time of the denitrification flue gas in the second settling chamber is 2s, and finally purified gas is obtained.

[0112] Example 8

[0113] The difference from Example 1 is that the temperature of the solid denitrification agent is 900° C., and purified gas is finally obtained.

[0114] Example 9

[0115] The difference from Example 1 is that the temperature of the solid denitrification agent is 750° C. Finally, purified gas is obtained.

[0116] The dust concentration, SO2 concentration and NO x The concentration was measured and the results are shown in Table 1.

[0117] Table 1

[0118]

[0119] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0120] In the present application, a water-cooled flue and a first settling chamber are provided to cool the high-temperature raw gas generated by the electric arc furnace and remove large particles of dust in the raw gas, thereby helping to reduce the risk of flue gas treatment. The purified raw gas outlet is connected to the purified raw gas inlet, and the purified raw gas is introduced into the rotary kiln as an auxiliary fuel, which helps to reduce the consumption of natural gas in the rotary kiln, and there is no need to add gas purification equipment and pressure-regulating fans. The first flue gas outlet is connected to the first flue gas inlet, and the first flue gas generated by the rotary kiln is introduced into the drying kiln as auxiliary hot air, which helps to further reduce energy loss, and there is no need to add dust removal and denitrification equipment and pressure-regulating fans. By providing a PNCR denitrification device, a solid denitrification agent is sprayed into the drying kiln to remove NO in the second flue gas generated by the drying kiln. x , there is no need to add an ammonia system and a denitrification tower, thus helping to reduce the cost of flue gas treatment. The flue gas treatment system of the present application does not have heat exchange, waste heat utilization and coal gas recovery devices. The system has fewer equipment, which helps to reduce the floor space of the flue gas treatment system and reduce the cost of flue gas treatment.

[0121] The above are merely examples of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A flue gas treatment system for smelting nickel iron using the RKEF method, characterized in that: The flue gas treatment system comprises: The submerged arc furnace (10) has a high-temperature raw coal gas outlet, and the submerged arc furnace (10) generates high-temperature raw coal gas; The water-cooled flue (20) has a high-temperature raw gas inlet and a low-temperature raw gas outlet; the high-temperature raw gas outlet is connected to the high-temperature raw gas inlet; the water-cooled flue (20) is used to cool the high-temperature raw gas to obtain low-temperature raw gas; A first settling chamber (30) has a low-temperature raw gas inlet and a purified raw gas outlet, wherein the low-temperature raw gas outlet is connected to the low-temperature raw gas inlet, and the first settling chamber (30) is used to settle the low-temperature raw gas to obtain purified raw gas; A rotary kiln (40) having a purified raw gas inlet and a first flue gas outlet, wherein the purified raw gas outlet is connected to the purified raw gas inlet, and the rotary kiln (40) is used to use the purified raw gas as an auxiliary fuel to generate a first flue gas; A drying kiln (50) having a first flue gas inlet, an outlet, and a solid denitrification agent inlet, wherein the first flue gas outlet is connected to the first flue gas inlet, and the drying kiln (50) is used to use the first flue gas as auxiliary hot air to generate a second flue gas; A PNCR denitrification device (60) is provided with a solid denitrification agent outlet, the solid denitrification agent outlet is connected to the solid denitrification agent inlet, and the denitrification device (60) is used to spray the solid denitrification agent into the drying kiln (50) to remove NO in the second flue gas. x To obtain denitrified flue gas; a first dust removal device (70) having a denitrification flue gas inlet and a purified denitrification flue gas outlet, the denitrification flue gas outlet being connected to the denitrification flue gas inlet, the dust removal device (70) being used to perform a first dust removal on the denitrification flue gas to obtain purified denitrification flue gas; A desulfurization device (80) having a purified denitrification flue gas inlet and a desulfurization flue gas outlet, wherein the purified denitrification flue gas outlet is connected to the purified denitrification flue gas inlet, and the desulfurization device (80) is used to remove sulfur dioxide from the purified denitrification flue gas to obtain desulfurized flue gas; The second dust removal device (90) has a desulfurized flue gas inlet and a purified gas outlet, wherein the desulfurized flue gas outlet is connected to the desulfurized flue gas inlet. The second dust removal device (90) is used for performing a second dust removal on the desulfurized flue gas to obtain purified gas.

2. The flue gas treatment system according to claim 1, characterized in that: The low-temperature raw gas outlet is connected to the low-temperature raw gas inlet via a first flue. The first flue is provided with a first regulating valve for regulating the pressure of the low-temperature raw gas outlet.

3. The flue gas treatment system according to claim 2, characterized in that: The purified raw gas outlet is connected to the purified raw gas inlet via a second flue, and the second flue is composed of 2 to 4 branch pipes.

4. The flue gas treatment system according to claim 3, characterized in that: The flue gas treatment system further comprises a combustion chamber (100) arranged on a flow path connecting the first flue gas outlet and the first flue gas inlet, and the combustion chamber (100) is used to remove residual carbon monoxide in the first flue gas.

5. The flue gas treatment system according to claim 4, characterized in that: The rotary kiln (40) and the combustion chamber (100) are connected via a third flue. The third flue is provided with a second regulating valve for regulating the pressure of the first flue gas outlet; and the third flue is provided with an emergency exhaust device.

6. The flue gas treatment system according to claim 5, characterized in that: The first dust removal device (70) comprises: a second settling chamber (71) for roughly removing dust from the denitrification flue gas to obtain roughly purified denitrification flue gas, wherein the second settling chamber (71) has a denitrification flue gas inlet and a roughly purified denitrification flue gas outlet; The electrostatic precipitator (72) has a coarsely purified denitrification flue gas inlet and the purified denitrification flue gas outlet, wherein the coarsely purified denitrification flue gas outlet is connected to the coarsely purified denitrification flue gas inlet, and the electrostatic precipitator (72) is used for finely removing dust from the coarsely purified denitrification flue gas to obtain the purified denitrification flue gas.

7. The flue gas treatment system according to claim 6, characterized in that: The flue gas treatment system further comprises a fan (110), which is arranged on a flow path connecting the purified denitrification flue gas outlet and the purified denitrification flue gas inlet, and is used to provide power for the entire flue gas purification system.

8. The flue gas treatment system according to claim 7, characterized in that: An emergency discharge device and an explosion relief valve are arranged on the top of the first settling chamber (30).

9. The flue gas treatment system according to claim 8, characterized in that: A carbon monoxide monitoring device is provided at the denitrification flue gas inlet.

10. The flue gas treatment system according to claim 9, characterized in that: The flue gas treatment system further comprises a chimney (120) arranged at the purified gas outlet for discharging the purified gas.

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