Flue gas treatment system and flue gas treatment method for smelting ferronickel by using RKEF method

Abstract

The invention provides a flue gas treatment system and a flue gas treatment method 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 present invention relates to the technical field of flue gas treatment, and in particular to a flue gas treatment system and a flue gas treatment method for smelting nickel-iron by 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 are mutually dissolved 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 contains raw coal 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 basically adopts the method of treating the flue gas from the ore-heating furnace, the flue gas from the rotary kiln and the flue gas from the drying kiln separately. The raw gas produced by the ore-heating furnace adopts the process of "cooling + bag dust collector" to produce clean gas, the flue gas produced by the rotary kiln adopts the process of "cyclone / electrostatic precipitator + SCR denitrification", and the flue gas produced by the drying kiln adopts the process of "electrostatic precipitator / bag dust collector + wet desulfurization". This flue gas treatment method uses multiple sets of cyclones, bag and electrostatic precipitators. In order to balance the pressure between the various equipment, multiple sets of additional and balancing fans are also required.

[0004] The Chinese patent application with the patent application publication number CN108411116A proposes a comprehensive flue gas treatment system and method for the RKEF smelting process of laterite nickel ore, which uses "submersible furnace, water-cooled flue, first bag dust collector, rotary kiln, cyclone dust collector, combustion air mixing chamber, dryer, and second bag dust collector" to treat and comprehensively utilize the RKEF flue gas. The coal gas of the submersible furnace is purified by the first bag dust collector and sent to the rotary kiln through the fan as fuel gas. The hot flue gas generated by the rotary kiln is sent to the combustion air mixing chamber of the drying kiln as hot air supplement after passing through the cyclone dust collector and the fan. The flue gas generated by the drying kiln is finally purified by the second bag dust collector. This process flow uses the coal gas of the submersible furnace to the rotary kiln, and the flue gas of the rotary kiln is used to supplement the heat of the drying kiln to comprehensively utilize the flue gas. Its disadvantage is that additional fans need to be set between the submersible furnace and the rotary kiln, and between the rotary kiln and the drying kiln, and the overall energy consumption is high. 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] The Chinese patent application with the patent application publication number CN214371794U proposes a comprehensive flue gas treatment system for the RKEF nickel-iron production process, which uses "submersible furnace, settling chamber, mixing chamber, first cyclone dust collector, denitrification device, drying kiln, second cyclone dust collector, wet desulfurization tower" to treat the flue gas generated by RKEF. This process mixes the purified submersible furnace gas and rotary kiln flue gas and passes them into the drying kiln as hot air for supplementary heat. The process uses cyclone dust collectors throughout, with low dust removal efficiency, and it is difficult for flue gas dust emissions to meet standards. An SCR denitrification device is added between the mixing chamber and the drying kiln to make full use of high temperature for denitrification. The problem is that the SCR reactor is a high-resistance device, and a pressure regulating fan needs to be added to adjust the system pressure balance, which increases equipment investment and system energy consumption.

[0006] The Chinese patent application with the patent application publication number CN213942674U proposes a flue gas denitrification system for the RKEF smelting process of laterite nickel ore, which utilizes the high-temperature flue gas generated by the mixture of the submerged arc furnace and the rotary kiln for denitrification. The SCR denitrification system does not need to add a supplementary heat device, and the denitrification efficiency is high. The disadvantage is that the flue gas is not dust-removed, and the SCR catalyst is easy to clog. The SCR denitrification operation resistance is high, and a booster fan needs to be set up to adjust the pressure balance, which has high energy consumption and requires a separate SCR denitrification tower, which is more complicated.

[0007] The Chinese patent application with the patent application publication number CN107747873A proposed a gas purification and recovery device for a submerged arc furnace for smelting Nitrate using the RKEF method, and a cyclone dust collector + bag dust collector combined process was used to purify the raw gas produced by the submerged arc furnace. The process uses a combination of multiple cyclone dust collectors and bag dust collectors, with good gas dust removal effect and high dust removal efficiency. The disadvantages are that there are many devices, the overall resistance is high, and a fan needs to be added to adjust the system pressure balance, which results in high energy consumption. Summary of the invention

[0008] The main purpose of the present invention is to provide a flue gas treatment system and a flue gas treatment method 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, and the flue gas treatment system comprises: an ore-heating furnace having a high-temperature raw coal gas outlet, and the ore-heating furnace produces high-temperature raw coal gas; a water-cooled flue having a high-temperature raw coal gas inlet and a low-temperature raw coal gas outlet; the high-temperature raw coal gas outlet is connected to the high-temperature raw coal gas inlet; the water-cooled flue is used to cool the high-temperature raw coal gas to obtain low-temperature raw coal gas; a first settling chamber has a low-temperature raw coal gas inlet and a purified raw coal gas outlet, the low-temperature raw coal gas outlet is connected to the low-temperature raw coal gas inlet, and the first settling chamber is used to settle the low-temperature raw coal gas The rotary kiln has a purified raw coal gas inlet and a first flue gas outlet, the purified raw coal gas outlet is connected to the purified raw coal gas inlet, and the rotary kiln is used to use the purified raw coal gas as an auxiliary fuel to produce a first flue gas; the drying kiln has 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 has 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 in 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 above-mentioned low-temperature raw coal gas outlet is connected to the low-temperature raw coal 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 coal gas outlet within -20Pa to -60Pa.

[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 above-mentioned flue gas treatment system also 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 is connected to the combustion chamber via a third flue, a second regulating valve is provided on the third flue for controlling the pressure of the first flue gas outlet at -150Pa to -250Pa, and 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 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 to control the pressure of the purified denitrification flue gas outlet at -1500Pa~-2000Pa.

[0016] Furthermore, an emergency discharge device and an explosion relief valve are arranged 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 above-mentioned flue gas treatment system also includes a chimney, which is arranged at the purified gas outlet and is used to discharge the purified gas.

[0019] According to another aspect of the present invention, a flue gas treatment method for smelting nickel iron using the RKEF method is provided, wherein the flue gas treatment system mentioned above is used to treat the flue gas, and the flue gas treatment method comprises: step S1, cooling the high-temperature raw coal gas generated by the ore-fired furnace to obtain low-temperature raw coal gas; step S2, settling the low-temperature raw coal gas to obtain purified raw coal gas; step S3, using the purified raw coal gas as an auxiliary fuel in a rotary kiln to generate a first flue gas; step S4, using the first flue gas as an auxiliary hot air in a 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, subjecting the denitrification flue gas to a first dust removal to obtain purified denitrification flue gas; step S7, removing sulfur dioxide from the purified denitrification flue gas to obtain desulfurized flue gas; step S8, subjecting the desulfurized flue gas to a second dust removal to obtain purified gas.

[0020] Furthermore, the temperature of the low-temperature raw coal gas does not exceed 700°C; and / or the temperature of the high-temperature raw coal gas is 800-1000°C; and / or the flow rate of the low-temperature raw coal gas is 4-8m / s.

[0021] Furthermore, the first settling chamber is used to settle the low-temperature raw coal gas to obtain purified raw coal gas. The wind speed of the cylinder section of the first settling chamber is 3-5m / s, and the residence time of the low-temperature raw coal gas in the first settling chamber exceeds 2s.

[0022] Furthermore, the flow rate of the purified raw gas is 4 to 8 m / s.

[0023] Furthermore, the flow rate of the first flue gas is 4-8 m / s.

[0024] Furthermore, 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.

[0025] Furthermore, the first dust removal comprises: 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.

[0026] Furthermore, 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 3-5m / s, and the denitrification flue gas stays in the second settling chamber for more than 2s; 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 0.5-1.0m / s.

[0027] Furthermore, in the above step S7, a desulfurizer is used to remove sulfur dioxide in the purified denitrification flue gas to obtain desulfurized flue gas. Preferably, the desulfurizer is a calcium-based desulfurizer or a sodium-based desulfurizer; further preferably, the desulfurizer is selected from any one or more of calcium hydroxide, calcium oxide and sodium hydroxide.

[0028] Furthermore, 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-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 Felike.

[0029] By applying the technical solution of the present invention, in this 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 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 devices 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 ammonia system and denitrification tower and other devices, which helps 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 gas recovery devices, and 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

[0030] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0031] Figure 1 A schematic diagram of the structure of a flue gas treatment system in an embodiment of the present application is shown;

[0032] The above drawings include the following reference numerals:

[0033] 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

[0034] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present 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.

[0035] 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 and a flue gas treatment method for smelting nickel iron using the RKEF method.

[0036] It should be noted that PNCR is the abbreviation for polymer selective catalytic reduction.

[0037] 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 1As shown, the flue gas treatment system includes: an ore-heating furnace 10, having a high-temperature raw coal gas outlet, and the ore-heating furnace 10 generates high-temperature raw coal gas; a water-cooled flue 20, having a high-temperature raw coal gas inlet and a low-temperature raw coal gas outlet; the high-temperature raw coal gas outlet is connected to the high-temperature raw coal gas inlet; the water-cooled flue 20 is used to cool the high-temperature raw coal gas to obtain low-temperature raw coal gas; a first settling chamber 30, having a low-temperature raw coal gas inlet and a purified raw coal gas outlet, the low-temperature raw coal gas outlet is connected to the low-temperature raw coal gas inlet, and the first settling chamber 30 is used to settle the low-temperature raw coal gas to obtain purified raw coal gas; a rotary kiln 40, having a purified raw coal gas inlet The rotary kiln 40 is used to use the purified raw coal gas as an auxiliary fuel to generate the first flue gas; the drying kiln 50 has a first flue gas inlet, a denitrification flue gas outlet and a solid denitrification agent inlet, 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 an auxiliary hot air to generate the second flue gas; the PNCR denitrification device 60 has 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 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 in 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.

[0038] 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 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 to 2), there is no need to add ammonia systems and denitrification towers, etc., which helps 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 gas recovery devices, and 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.

[0039] The water-cooled flue can adopt a vaporization cooling flue or a membrane water-cooled wall, including but not limited to, the 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.

[0040] 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 to -60Pa.

[0041] The first regulating valve is provided to help control the flow rate of the low-temperature raw coal gas, thereby helping to improve the settling efficiency of the low-temperature raw coal gas and the safety of flue gas treatment.

[0042] 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 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 inner lining thickness of the first flue is >50mm, the inner lining is made of 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 The first regulating valve adopts butterfly valve type, and the valve body and valve plate are made of 310s stainless steel.

[0043] In order to control the flow rate of the purified raw coal gas, in one embodiment of the present application, it is preferred that the above-mentioned purified raw coal gas outlet is connected to the purified raw coal 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 .

[0044] 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 also includes a combustion chamber 100, which is 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 the residual carbon monoxide in the first flue gas.

[0045] In order to control the flow rate of the first flue gas, in one embodiment of the present application, it is preferred that the rotary kiln 40 and the combustion chamber 100 are connected via a third flue, and a second regulating valve is provided on the third flue to control the pressure of the first flue gas outlet at -150Pa to -250Pa, and an emergency discharge device is provided on the third flue to help temporarily discharge accidental flue gas. The direction of the third flue is inclined, and the inclination angle of the third flue to the horizontal direction is not less than 60°. The material of the outer wall of the third flue is Q345 or 20G carbon steel, and the thickness of the outer wall of the third flue is ≥8mm. The second regulating valve adopts a butterfly valve type, and the valve body and valve plate are made of 304 / 310s stainless steel.

[0046] 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.

[0047] The second settling chamber and the electrostatic precipitator are provided to further reduce the dust concentration in the purified denitrification flue gas. The electrostatic precipitator is preferably a high-temperature electrostatic precipitator with a temperature resistance of ≥420°C. The box body and the outer wall of the ash hopper of the second settling chamber are made of carbon steel, the thickness of the outer wall of the ash hopper is ≥10mm, and the inclination angle of the bottom ash hopper is ≥60°C.

[0048] In one embodiment of the present application, the flue gas treatment system further includes 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 and control the pressure of the purified denitrification flue gas outlet at -1500Pa to -2000Pa.

[0049] The entire flue gas treatment system of the present application is provided with only one fan, and the positive pressure at the fan outlet is 2500-3000Pa, which helps to make the pressure loss of the entire flue gas treatment system less than 5000Pa, 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%.

[0050] In one embodiment of the present application, an emergency discharge device and an explosion relief valve are arranged at the top of the first settling chamber 30. The cylinder of the first settling chamber is cylindrical, the bottom ash hopper of the cylinder has an inclination angle of ≥60°, the outer wall of the cylinder is made of carbon steel, the outer wall thickness of the cylinder is ≥10mm, the lining thickness of the cylinder is >50mm, 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 >2.0g / cm 3 .

[0051] An emergency discharge device is provided at the top of the first settling chamber 30 to help temporarily discharge accidental smoke. 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 smoke treatment system.

[0052] In one embodiment of the present application, a carbon monoxide monitoring device is provided at the above-mentioned denitrification flue gas inlet.

[0053] By installing a carbon monoxide monitoring device at the inlet of the denitrification flue gas and stopping the fan when the volume concentration of CO is greater than 2%, the probability of CO being discharged out of the system is reduced.

[0054] In one embodiment of the present application, the flue gas treatment system further includes a chimney 120, which is disposed at the purified gas outlet and is used to discharge the purified gas.

[0055] This application discharges the purified gas by setting a chimney.

[0056] In one embodiment of the present application, when the drying kiln is shut down, the PNCR denitrification device is connected to the rotary kiln, the PNCR denitrification device provides 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, and a carbon monoxide monitoring device is arranged on the fourth pipe. When the volume concentration of CO is greater than 2%, the operation of the fan is stopped, which helps to reduce the probability of CO being discharged out of the system.

[0057] 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 treatment system mentioned above is used to treat the flue gas. The flue gas treatment method includes: step S1, cooling the high-temperature raw coal gas generated by the ore-fired furnace to obtain low-temperature raw coal gas; step S2, settling the low-temperature raw coal gas to obtain purified raw coal gas; step S3, using the purified raw coal gas as an auxiliary fuel in a rotary kiln to generate a first flue gas; step S4, using the first flue gas as an auxiliary hot air in a drying kiln to generate a second flue gas; step S5, spraying a solid denitrification agent into the second flue gas for NO removal. xto obtain denitrification flue gas; step S6, subjecting the denitrification flue gas to a first dust removal to obtain purified denitrification flue gas; step S7, removing sulfur dioxide from the purified denitrification flue gas to obtain desulfurized flue gas; step S8, subjecting the desulfurized flue gas to a second dust removal to obtain purified gas.

[0058] 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 danger of flue gas treatment. In step S3, 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. 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 there is no need to add 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.

[0059] In order to improve the safety of flue gas treatment, in one embodiment of the present application, it is preferred that the temperature of the above-mentioned low-temperature raw coal gas does not exceed 700°C; and / or the temperature of the high-temperature raw coal gas is 800-1000°C; and / or the flow rate of the low-temperature raw coal gas is 4-8m / s.

[0060] 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 coal gas to obtain purified raw coal 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 coal gas in the first sedimentation chamber exceeds 2s.

[0061] 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.

[0062] In order to improve the utilization rate of the first flue gas, in one embodiment of the present application, it is preferred that the flow rate of the first flue gas is 4 to 8 m / s.

[0063] 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.

[0064] In one embodiment of the present application, the first dust removal comprises: 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.

[0065] Preliminarily subjecting the denitrification flue gas to coarse dust removal and then fine dust removal can help to further reduce the concentration of dust in the purified denitrification flue gas.

[0066] In order to further improve the efficiency of the first dust removal, in one embodiment of the present application, it is preferred that the 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 3-5 m / s, and the denitrification flue gas stays in the second settling chamber for more than 2 s; 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 0.5-1.0 m / s.

[0067] In order to improve the desulfurization efficiency, in one embodiment of the present application, in the above step S7, a desulfurizer is preferably 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; further preferably, the desulfurizer is selected from any one or more of calcium hydroxide, calcium oxide and sodium hydroxide.

[0068] In order to improve the desulfurization efficiency, in one embodiment of the present application, in the above step S5, the temperature of the solid denitrification agent is preferably ≥ 750°C, preferably the temperature of the solid denitrification agent is 800°C ~ 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 Felike.

[0069] The beneficial effects of the present application will be further illustrated below in conjunction with embodiments.

[0070] Example 1

[0071] 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 is 900℃, dust content is 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 .

[0072] Use Figure 1The flue gas treatment system shown treats the flue gas generated as described above. In the flue gas treatment system, the ore furnace 10 has a high-temperature raw coal gas outlet, the water-cooled flue 20 has a high-temperature raw coal gas inlet and a low-temperature raw coal gas outlet; the high-temperature raw coal gas outlet is connected to the high-temperature raw coal gas inlet; the first settling chamber 30 has a low-temperature raw coal gas inlet and a purified raw coal gas outlet, and the low-temperature raw coal gas outlet is connected to the low-temperature raw coal gas inlet; the rotary kiln 40 has a purified raw coal gas inlet and a first flue gas outlet, and the purified raw coal gas outlet is connected to the purified raw coal 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, which are 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, which are 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, which are 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 is connected to the combustion chamber 100 through a third flue, a second regulating valve is provided on the third flue, and an emergency exhaust device is provided on the third flue. The fan 110 is arranged on the flow path connecting the outlet of the purified denitrification flue gas and the inlet of the purified denitrification flue gas. An emergency exhaust device and an explosion relief valve are arranged 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 arranged at the inlet of the denitrification flue gas. When the volume concentration of CO is greater than 2%, an alarm is issued and the fan operation is stopped. The chimney 120 is arranged at the outlet of the purified gas.

[0073] Step S1, cooling the high-temperature raw coal gas generated by the ore-fired furnace 10 by using a water-cooled flue 20 to obtain low-temperature raw coal gas;

[0074] Step S2, settling the low-temperature raw coal gas in the first settling chamber 30 to obtain purified raw coal gas;

[0075] Step S3, using the purified raw gas as auxiliary fuel in the rotary kiln 40 to generate first flue gas;

[0076] 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;

[0077] Step S5: using the PNCR denitration device 60 to spray a solid denitration agent into the second flue gas to remove NO x to obtain denitrified flue gas;

[0078] Step S6, the first dust removal device 70 includes a second settling chamber 71 and an electrostatic precipitator 72, the denitrification flue gas is subjected to rough dust removal in the second settling chamber 71 to obtain roughly purified denitrification flue gas; the roughly purified denitrification flue gas is subjected to fine dust removal in the electrostatic precipitator 72 to obtain purified denitrification flue gas;

[0079] Step S7, sending the purified denitrified flue gas to the desulfurization device 80 (wet desulfurization tower) through the fan 110 to remove sulfur dioxide in the purified denitrified flue gas to obtain desulfurized flue gas;

[0080] 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 discharged to the outside through a chimney 120 .

[0081] Among them, the temperature of the cooled raw coal gas is 700℃, the pressure of the low-temperature raw coal 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.

[0082] The water-cooled flue adopts a patterned water-cooled wall method.

[0083] The flow rate of low-temperature raw coal 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 an outer wall thickness of 10mm and an inner lining thickness of 100mm. The inner lining is made of heavy refractory castables. 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.

[0084] The cylinder of the first settling chamber is cylindrical, with a wind speed of 5m / s in the cylinder section and a residence time of 2.5s for low-temperature raw coal gas. The bottom ash hopper has an inclination angle of 60°, an outer wall of carbon steel, an outer wall thickness of 12mm, an inner lining thickness of 100mm, and an inner lining material of heavy refractory castables. The mass proportion of Al2O3 in the refractory castables is 80%, and the volume density of the refractory castables is 2.6g / cm 3 ;

[0085] The second pipeline consists of 4 branches, which are evenly distributed around the natural gas nozzle of the rotary kiln. The flow rate of the purified raw gas in the branch pipe is 8m / s. The pipeline is arranged at an angle, and the inclination angle of the pipeline to the horizontal direction is 60°. The end of the branch pipe is connected to the kiln head of the rotary kiln with a straight pipe section, and the length = 1.4m. The outer wall of the branch pipe is made of carbon steel, the thickness of the outer wall is 10mm, the thickness of the inner lining is 100mm, and the material of the inner lining is 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 .

[0086] The flow rate of the first flue gas is 6m / s, the third pipe is arranged as a herringbone pipe, the inclination angle of the third pipe to the horizontal direction is 60°, the material of the outer wall is 20G carbon steel, the thickness of the outer wall is 10mm, the second regulating valve is a butterfly valve type, and the material of the valve body and valve plate is 304 stainless steel.

[0087] 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°.

[0088] The filtration wind speed of the electrostatic precipitator is 0.6m / s.

[0089] The fan's air volume and pressure loss margin coefficient is 20%, and the air volume is 600000m 3 / h, wind pressure is 5500Pa.

[0090] 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℃.

[0091] Example 2

[0092] 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 390000Nm 3 / h, temperature is 150℃, SO2 is 1000mg / Nm 3 , dust content is 10g / Nm 3 , NO x 400mg / Nm 3 .

[0093] Use Figure 1 The flue gas treatment system shown treats the flue gas generated as described above. In the flue gas treatment system, the ore furnace 10 has a high-temperature raw coal gas outlet, the water-cooled flue 20 has a high-temperature raw coal gas inlet and a low-temperature raw coal gas outlet; the high-temperature raw coal gas outlet is connected to the high-temperature raw coal gas inlet; the first settling chamber 30 has a low-temperature raw coal gas inlet and a purified raw coal gas outlet, and the low-temperature raw coal gas outlet is connected to the low-temperature raw coal gas inlet; the rotary kiln 40 has a purified raw coal gas inlet and a first flue gas outlet, and the purified raw coal gas outlet is connected to the purified raw coal 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, which are 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, which are 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, which are 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 is connected to the combustion chamber 100 through a third flue, a second regulating valve is provided on the third flue, and an emergency exhaust device is provided on the third flue. The fan 110 is arranged on the flow path connecting the outlet of the purified denitrification flue gas and the inlet of the purified denitrification flue gas. An emergency exhaust device and an explosion relief valve are arranged 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 arranged at the inlet of the denitrification flue gas. When the volume concentration of CO is greater than 2%, an alarm is issued and the fan operation is stopped. The chimney 120 is arranged at the outlet of the purified gas.

[0094] Step S1, cooling the high-temperature raw coal gas generated by the ore-fired furnace 10 by using a water-cooled flue 20 to obtain low-temperature raw coal gas;

[0095] Step S2, settling the low-temperature raw coal gas in the first settling chamber 30 to obtain purified raw coal gas;

[0096] Step S3, using the purified raw gas as auxiliary fuel in the rotary kiln 40 to generate first flue gas;

[0097] 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;

[0098] Step S5: using the PNCR denitration device 60 to spray a solid denitration agent into the second flue gas to remove NO x to obtain denitrified flue gas;

[0099] Step S6, the first dust removal device 70 includes a second settling chamber 71 and an electrostatic precipitator 72, the denitrification flue gas is subjected to rough dust removal in the second settling chamber 71 to obtain roughly purified denitrification flue gas; the roughly purified denitrification flue gas is subjected to fine dust removal in the electrostatic precipitator 72 to obtain purified denitrification flue gas;

[0100] Step S7, sending the purified denitrified flue gas to the desulfurization device 80 (wet desulfurization tower) through the fan 110 to remove sulfur dioxide in the purified denitrified flue gas to obtain desulfurized flue gas;

[0101] 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 discharged to the outside through a chimney 120 .

[0102] Among them, the temperature of the cooled raw coal gas is 700℃, the pressure of the low-temperature raw coal 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.

[0103] The water-cooled flue adopts a vaporization cooling flue method.

[0104] 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 an outer wall thickness of 10mm and an inner lining thickness of 120mm. The inner lining is made of heavy refractory castables. The mass proportion of Al2O3 in the refractory castables is 82%, and the volume density of the refractory castables 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.

[0105] The cylinder of the first settling chamber is cylindrical, with a wind speed of 4m / s in the cylinder section and a residence time of 3.0s for low-temperature raw coal gas. The bottom ash hopper has an inclination angle of 60°, an outer wall of carbon steel, an outer wall thickness of 12mm, an inner lining thickness of 120mm, and an inner lining material of heavy refractory castables. The mass proportion of Al2O3 in the refractory castables is 82%, and the volume density of the refractory castables is 3.0g / cm 3 ;

[0106] The second pipeline consists of 3 branches, which are evenly distributed around the natural gas nozzle of the rotary kiln. The flow rate of the purified raw gas in the branch pipe is 6m / s. The pipeline is arranged at an angle, and the inclination angle of the pipeline to the horizontal direction is 65°. The end of the branch pipe is connected to the kiln head of the rotary kiln with a straight pipe section, and the length = 1.1m. The outer wall of the branch pipe is made of carbon steel, the thickness of the outer wall is 10mm, the thickness of the inner lining is 120mm, and the material of the inner 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 .

[0107] The flow rate of the first flue gas is 5m / s, the third pipe is arranged as a herringbone pipe, the inclination angle of the third pipe to the horizontal direction is 62°, the material of the outer wall is Q345 carbon steel, the thickness of the outer wall is 10mm, the second regulating valve adopts a butterfly valve type, and the material of the valve body and valve plate is 310s stainless steel.

[0108] 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°.

[0109] The filtration wind speed of the electrostatic precipitator is 0.5m / s.

[0110] The fan's air volume and pressure loss margin coefficient is 20%, and the air volume is 730000m 3 / h, wind pressure is 5800Pa.

[0111] The desulfurizer is sodium hydroxide, the denitrification adopts Jiangsu Juyibang dry denitrification process, the solid denitrification agent is Juyibang's granular polymer solid denitrification agent, and the temperature of the solid denitrification agent is 900℃.

[0112] Example 3

[0113] 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.

[0114] Example 4

[0115] 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.

[0116] Example 5

[0117] 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.

[0118] Example 6

[0119] 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.

[0120] Example 7

[0121] 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.

[0122] Example 8

[0123] The difference from Example 1 is that the temperature of the solid denitrification agent is 900° C., and purified gas is finally obtained.

[0124] Example 9

[0125] The difference from Example 1 is that the temperature of the solid denitrification agent is 750° C. Finally, purified gas is obtained.

[0126] The dust concentration, SO2 concentration and NO concentration in the purified gas obtained in the example are x The concentration was measured and the results are shown in Table 1.

[0127] Table 1

[0128]

[0129] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0130] 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 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 , there is no need to add ammonia system and denitrification tower and other devices, which helps 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 gas recovery devices, and 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.

[0131] The above are only embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope 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 coal gas inlet and a low-temperature raw coal gas outlet; the high-temperature raw coal gas outlet is connected to the high-temperature raw coal gas inlet; the water-cooled flue (20) is used to cool the high-temperature raw coal gas to obtain low-temperature raw coal gas; A first settling chamber (30) having a low-temperature crude gas inlet and a purified crude gas outlet, wherein the low-temperature crude gas outlet is connected to the low-temperature crude gas inlet, and the first settling chamber (30) is used to settle the low-temperature crude gas to obtain purified crude gas; A rotary kiln (40) having a purified raw coal gas inlet and a first flue gas outlet, wherein the purified raw coal gas outlet is connected to the purified raw coal gas inlet, and the rotary kiln (40) is used to use the purified raw coal 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, wherein 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, 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, and the second dust removal device (90) is used to perform 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 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 within -20Pa to -60Pa.

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) disposed on a flow path connecting the first flue gas outlet and the first flue gas inlet, wherein 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) is 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 to be between -150Pa and -250Pa. 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) is used for roughly removing dust from the denitrification flue gas to obtain roughly purified denitrification flue gas, and the second settling chamber (71) has an inlet for the denitrification flue gas and an outlet for roughly purified denitrification flue gas; 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 to perform fine dust removal on 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 also includes 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 and control the pressure of the purified denitrification flue gas outlet to -1500Pa to -2000Pa.

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 arranged 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) which is arranged at the purified gas outlet and is used to discharge the purified gas.

11. A flue gas treatment method for smelting nickel iron using the RKEF method, characterized in that: The flue gas treatment system according to any one of claims 1 to 10 is used to treat flue gas, and the flue gas treatment method comprises: Step S1, cooling the high-temperature raw coal gas generated by the ore-fired furnace to obtain low-temperature raw coal gas; Step S2, sedimenting the low-temperature raw coal gas to obtain purified raw coal gas; Step S3, using the purified raw coal gas as an auxiliary fuel in a rotary kiln to generate a first flue gas; Step S4, using the first flue gas as auxiliary hot air in a drying kiln to generate second flue gas; Step S5, spraying a solid denitrification agent into the second flue gas to remove NO x to obtain denitrified 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, subjecting the desulfurized flue gas to a second dust removal to obtain purified gas.

12. The flue gas treatment method according to claim 11, characterized in that: The temperature of the low-temperature raw coal gas does not exceed 700° C.; and / or the temperature of the high-temperature raw coal gas is 800-1000° C.; and / or the flow rate of the low-temperature raw coal gas is 4-8 m / s.

13. The flue gas treatment method according to claim 11 or 12, characterized in that: The low-temperature raw coal gas is settled in the first settling chamber to obtain purified raw coal gas. The wind speed of the cylinder section of the first settling chamber is 3-5m / s, and the residence time of the low-temperature raw coal gas in the first settling chamber exceeds 2s.

14. The flue gas treatment method according to any one of claims 11 to 13, characterized in that: The flow rate of the purified raw coal gas is 4 to 8 m / s.

15. The flue gas treatment method according to any one of claims 11 to 14, characterized in that: The flow rate of the first flue gas is 4-8 m / s.

16. The flue gas treatment method according to any one of claims 11 to 15, characterized in that: In the step S4, the first flue gas is burned and used as auxiliary hot air in the drying kiln to generate second flue gas.

17. The flue gas treatment method according to any one of claims 11 to 16, characterized in that: The first dust removal comprises: Step S61, roughly removing dust from the denitrification flue gas to obtain roughly purified denitrification flue gas; Step S62, subjecting the roughly purified denitrified flue gas to fine dust removal to obtain the purified denitrified flue gas.

18. The flue gas treatment method according to claim 17, characterized in that: A second settling chamber is used to roughly remove dust from the denitrification flue gas to obtain roughly purified denitrification flue gas, the wind speed of the box section of the second settling chamber is 3-5 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 carry out fine dust removal on the coarsely purified denitrification flue gas to obtain the purified denitrification flue gas, and the filtration wind speed of the electrostatic precipitator is 0.5-1.0 m / s.

19. The flue gas treatment method according to any one of claims 11 to 18, characterized in that: In step S7, a desulfurizer is used to remove sulfur dioxide in the purified denitrification flue gas to obtain desulfurized flue gas. Preferably, the desulfurizer is a calcium-based desulfurizer or a sodium-based desulfurizer; further preferably, the desulfurizer is selected from any one or more of calcium hydroxide, calcium oxide and sodium hydroxide.

20. The flue gas treatment method according to any one of claims 11 to 19, characterized in that: In 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 Felike.

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