CN-117070744-B - Sintering method for reducing CO content in sinter flue gas

CN117070744BCN 117070744 BCN117070744 BCN 117070744BCN-117070744-B

Abstract

The invention relates to a sintering method for reducing CO content in sinter flue gas, which greatly reduces the content of carbon monoxide in discharged flue gas by reasonably matching measures such as material layer thickness, material distribution mode, flue gas recycling composite oxygen-enriched sintering, flue gas carbon monoxide catalytic oxidation and the like in each step, thereby greatly improving the environmental friendliness of flue gas discharge.

Inventors

LI XIAOHAI
ZHANG CHENCHEN
LIU SUTAO
SHE XUEFENG
WANG YANJIANG
Han Meidan
LIU PENG
XU PEIXIANG
MENG YANJUN
LI YINGTAO
GE ZHIBIN

Assignees

德龙钢铁有限公司
北京科技大学

Dates

Publication Date: 20260508
Application Date: 20230829

Claims (8)

1. The sintering method for reducing the CO content in the sintering ore flue gas is characterized by comprising the following steps of: (1) Preparing 85-95 parts by weight of iron ore powder with TFe of 50-68wt%, 3-6 parts by weight of quicklime, 1-2 parts by weight of dolomite and 5-9 parts by weight of coke powder as sintering raw materials; (2) Primary mixing, namely placing the sintering raw material prepared in the step (1) into a mixer, and then spraying 3-5 parts by weight of water for primary mixing for 5-9min; (3) Secondary mixing granulation, namely placing the mixture obtained by primary mixing in the step (2) into a secondary strong mixer, and spraying 3-5 parts by weight of water at the same time to perform secondary mixing granulation to obtain sintering raw material particles, wherein the particle size range of the sintering raw material particles is 0.5-12mm; (4) The material bed cloth comprises a single-layer multi-roller distributor, wherein the multi-roller distributor is obliquely arranged above a material bed, the advancing direction of the multi-roller distributor is opposite to the advancing direction of the material bed, the bottom end of the multi-roller distributor is arranged to face forwards, the top end of the multi-roller distributor faces backwards, the included angle between the multi-roller distributor and the horizontal direction is 33-46 degrees, a round roller feeder is arranged above the top end of the multi-roller distributor, the turning direction of round rollers of the round roller feeder is opposite to the turning direction of each roller of the multi-roller distributor, the rotating speed of the round rollers is 5-8 r/min, the rotating speed of each roller in the multi-roller distributor is 10-r/min, the moving speed of the material bed is 1.9-2.5m/min, the sintering raw material particles prepared in the step (3) are quickly paved at the bottom of the material bed through the round roller feeder, the raw material particles with larger particle sizes slowly move between the rollers of the multi-roller distributor, and finally the main body is arranged at the top end of the material layer, so that the proportion of the sintering raw material particles with the particle sizes of 5-12% to the top layer is 3-96 mm, and the sintering raw material particles with the particle sizes of the top layer in the material layer is in the material layer with the proportion of 5-6wt% to 7wt% to the sintering raw material; the bottom layer of the material layer is arranged at the position from the bottommost end of the material layer to the 1/3 height upwards, the top layer of the material layer is arranged at the position from the topmost end of the material layer to the 1/3 height downwards, and the middle layer of the material layer is arranged between the bottom layer of the material layer and the top layer of the material layer, wherein the thickness of the material layer of the cloth is 890-960mm; (5) Recycling flue gas and sintering with oxygen enrichment; a smoke hood is arranged above the material bed, mixed smoke is arranged at the top of the smoke hood and discharged into a pipeline, a plurality of bellows are arranged below the material layer, through extracting negative pressure, gas flows downwards from the top of the material layer through the material layer and is discharged from the bottom of the bellows, the material bed continuously distributes materials in the mode of the step (4) while igniting and starts sintering, a mixing chamber is connected with an ignition furnace, the volume content of industrial pure oxygen in the mixing chamber is set to be 23-26%, the ignition is carried out by adopting oxygen-enriched gas in the mixing chamber, the ignition temperature is 1165-1180 ℃, and simultaneously a fan is started to enable the material layer to form negative pressure below the material layer through the plurality of bellows; the flue gas discharged from the bottom of the bellows is respectively communicated with a flue gas treatment pipeline and a flue gas recycling pipeline, the outlet end of the flue gas recycling pipeline is communicated with the inlet end of a mixed flue gas discharging pipeline, the inlet end of the mixed flue gas discharging pipeline is simultaneously communicated with an oxygen discharging pipeline, oxygen and flue gas are mixed in the mixed flue gas discharging pipeline and then discharged to the surface of a material layer through a smoke cover, the volume content of oxygen in the mixed flue gas discharging pipeline is set to be 25-28%, flue gas recycling and oxygen-enriched sintering are carried out to obtain a sintered mineral product, the oxygen content in gas in a discharged material layer is 17-22%, the middle and rear part of the material layer in the smoke cover are independently provided with an oxygen-enriched air pipeline, oxygen-enriched air is sprayed towards the material layer, the oxygen content in the oxygen-enriched air is 29-38%, a hydrogen nozzle is vertically arranged on the smoke cover in a penetrating manner, the hydrogen nozzle is arranged above the front part of the material bed and is positioned at the rear part of an ignition point, the volume concentration of hydrogen gas is 0.52-0.91%, the sintering speed is controlled to be 20.82-25.2mm/min, the ignition point is A point, the midpoint position of the material bed is B point, the midpoint between the A point and the B point is C point, and the number of the hydrogen nozzles arranged between the A point and the C point is 2-5 times of the number arranged between the B point and the C point; (6) The flue gas treatment device comprises a flue gas treatment pipeline, an electrostatic precipitator, an active carbon desulfurization component, a carbon monoxide catalytic oxidation device, an SCR denitration component and a circulating fan are sequentially arranged on the flue gas treatment pipeline, the carbon monoxide catalytic oxidation device comprises an air guiding pipe, an inlet bent pipe, a catalytic oxidation kiln, a catalytic oxidation block, an outlet bent pipe and an air return pipe, the air guiding pipe and the air return pipe are closed pipes with two pipe ends, the air guiding pipe and the air return pipe are arranged in parallel or approximately in parallel, the air guiding pipe and the air return pipe are all arranged in a non-parallel manner with the flue gas treatment pipeline, a flue gas inlet and a flue gas outlet are formed in the side wall of the air guiding pipe, the flue gas inlet is communicated with the tail end of the front section of the flue gas treatment pipeline, the flue gas outlet is communicated with the inlet end of the inlet bent pipe, the outlet of the air guiding pipe is communicated with the top end of the catalytic oxidation kiln, a plurality of catalytic oxidation blocks are arranged in the catalytic oxidation kiln, the bottom end opening of the catalytic oxidation kiln is communicated with the inlet end of the outlet bent pipe, the catalytic gas inlet and the catalytic gas outlet are formed in the side wall of the pipe, the outlet end of the outlet is communicated with the catalytic gas inlet of the flue gas inlet of the pipe, the flue gas inlet of the flue gas outlet is communicated with the flue gas outlet, and the flue gas outlet is communicated with the tail end of the flue gas treatment pipeline.
2. The method according to claim 1, wherein the plurality of windboxes in step (5) are divided into five windboxes from front to back in this order, the direction close to the ignition point is the front, the number of windboxes in the first windbox group is 10-15% of the total number of windboxes, the number of windboxes in the second windbox group is 20-25%, the number of windboxes in the third windbox group is 35-40%, the number of windboxes in the fourth windbox group is 20-25%, the number of windboxes in the fifth windbox group is 5-9%, the flue gas discharged from the bottoms of the windboxes in the first windbox group, the third windbox group and the fifth windbox group is communicated with the flue gas recycling pipeline, and the volume ratio of the flue gas amount entering the flue gas recycling pipeline to the flue gas amount entering the flue gas recycling pipeline is (65-75): (25-35).
3. The sintering method for reducing the content of CO in the sinter flue gas according to claim 1, wherein in the step (5), an electrostatic precipitator and a circulating fan are sequentially arranged on the flue gas recycling pipeline.
4. The sintering method for reducing the CO content in the sinter flue gas according to claim 1, wherein the catalytic oxidation block in the step (6) is a composite rectangular block body with zirconium-containing mullite honeycomb ceramics as a carrier and an aqueous solution compounded by copper nitrate and cerium nitrate as an active catalytic component, each zirconium-containing mullite honeycomb ceramic is provided with a plurality of vertical densely distributed through holes, the pore diameter of the densely distributed through holes is 1.5-2.5mm, the wall thickness between the through holes is 0.8-1.3mm, and the zirconium content of the zirconium-containing mullite honeycomb ceramics is 0.9-1.8wt%.
5. The sintering method for reducing CO content in sinter flue gas according to claim 4, wherein the preparation method of the catalytic oxidation block in the step (6) comprises the following steps of roasting zirconium-containing mullite honeycomb ceramics, preparing a compound aqueous solution of copper nitrate and cerium nitrate, placing the zirconium-containing mullite honeycomb ceramics obtained in the step I into the aqueous solution prepared in the step II, setting stirring paddles to enable the aqueous solution to form vortex, setting the dense through hole direction of the zirconium-containing mullite honeycomb ceramics to face the vortex flowing direction, carrying out impregnation for 10-15 hours, and roasting the catalytic oxidation block obtained in the step III.
6. The sintering method for reducing CO content in sinter flue gas according to claim 4 or 5, wherein the preparation method of the catalytic oxidation block in the step (6) comprises the steps of (I) placing the cleaned zirconium-containing mullite honeycomb ceramic into a roasting furnace for roasting at 380-620 ℃ and roasting time of 0.8-2.2 hours, (II) weighing Cu (NO 3 ) 2 ·6H 2 O and Ce (NO 3 ) 3 ·6H 2 O) according to the weight ratio of (1-6) (0.8-1.2), then mixing the mixture with deionized water to prepare a compound aqueous solution with the concentration of 0.38-2mol/L, III) placing the zirconium-containing mullite honeycomb ceramic obtained in the step (I) into the aqueous solution obtained in the step (II), forming vortex by arranging stirring paddles on the surface of the aqueous solution, placing the direction of through holes of the zirconium-containing mullite honeycomb ceramic towards the direction of vortex flow, taking out the impregnated catalytic oxidation block after 10-15 hours, IV placing the catalytic oxidation block obtained in the step (III) into the roasting furnace, heating the catalytic oxidation block in the inert gas protective atmosphere for 280-180 ℃ to obtain the catalytic oxidation block after cooling for 3-5 ℃ and cooling.
7. The sintering method for reducing the CO content of the sinter flue gas according to claim 1 or 4, wherein the catalytic oxidation blocks are arranged in a multi-layer mode in the catalytic oxidation kiln, the length and the width of each layer of catalytic oxidation blocks are unequal, gaps between adjacent catalytic oxidation blocks of any layer are not in the same vertical plane, or the catalytic oxidation blocks of each layer are arranged in a staggered mode, the gaps between the adjacent catalytic oxidation blocks of any layer are not in the same vertical plane, and the densely distributed through holes of all the catalytic oxidation blocks face to the bottom end opening and the top end opening of the catalytic oxidation kiln.
8. The sintering method for reducing the CO content of the sintering ore flue gas according to claim 1 or 4, wherein a supporting frame is arranged on the material bed, and the height of the supporting frame is such that the top end of the supporting frame is positioned at the bottom end of the sintering ore layer of the material layer and at the top end of the soft melting layer.

Description

Sintering method for reducing CO content in sinter flue gas Technical Field The invention relates to the technical field of sintering of steel smelting sintering ores, in particular to a sintering method for reducing CO content. Background The sintering process of the sinter is an important process at the front end in the steel smelting process, but a large amount of harmful smoke is generated by the sinter at the same time, and the proportion of the harmful smoke generated in the sintering process is close to 50% in the whole steel smelting process, so that the treatment of the smoke of the sinter is particularly important. The sinter flue gas mainly contains nitrogen oxides, sulfur oxides, particulate dust and carbon monoxide. At present, researches on particulate matters, nitrogen oxides and sulfur oxides are more sufficient, but relatively less researches on removing carbon monoxide are concerned. With the gradual rise of environmental awareness and the gradual rise of requirements for environmental management, besides the strict limitation of the content of harmful substances such as sulfur oxides, nitrogen oxides and particulate matters, the content limitation of carbon monoxide in harmful flue gas is gradually focused, the emission standard of carbon monoxide in certain areas is below 6000mg/m 3, and with the gradual rise of requirements for environmental emission, the lower limit of the standard can be predicted to be further strict in a short time. In the treatment of carbon monoxide in sintering flue gas, it is mainly necessary to minimize the generation of carbon monoxide in front-end treatment and to remove the generated carbon monoxide in back-end treatment. In the sintering process, carbon monoxide is generated by incomplete combustion of carbon in the solid fuel, and meanwhile, carbon dioxide generated by complete combustion is combined with carbon at different positions of a sintering layer to regenerate carbon monoxide, namely, CO 2 +C=2CO, so that the generation of carbon monoxide in the sintering process is reduced, the complete combustion is reasonably promoted, incomplete oxidation of carbon to carbon monoxide is reduced, and the carbon dioxide generated by complete combustion is prevented from reacting with carbon to regenerate carbon monoxide. In the back-end treatment process, the catalytic oxidation efficiency of carbon monoxide in the flue gas is the content of important attention of researchers, in the prior art, the main active components of the CO catalytic oxidant are noble metals such as platinum, rhodium and palladium, the process is a coating process, the surface active layer of the CO catalytic oxidant prepared by the coating process is worn and disappeared after being used for a period of time, the catalytic activity of the CO catalytic oxidant is obviously reduced, the efficiency is reduced, the maintenance cost is increased, the impregnation mode is increased by a small amount of researches, but the existing impregnation process has the phenomena of uneven and the like, so that the catalytic oxidation effect is greatly reduced. Chinese patent publication CN114733318a discloses a method for treating sintering flue gas, which uses a blast furnace to treat the sintering flue gas so as to achieve the effect of reducing various harmful substances including carbon monoxide in the sintering flue gas, but only focuses on the back-end treatment, and does not effectively combine the back-end treatment with the front-end treatment. Disclosure of Invention The invention aims to provide a sintering method for reducing the content of CO in sintering ore flue gas, thereby effectively reducing the content of CO generated in the sintering process. The invention solves the problems through the following technical proposal: a sintering method for reducing CO content in sinter flue gas comprises the following steps: (1) Preparing 85-95 parts by weight of iron ore powder with TFe of 50-68wt%, 3-6 parts by weight of quicklime, 1-2 parts by weight of dolomite and 5-9 parts by weight of coke powder as sintering raw materials; (2) Primary mixing, namely placing the sintering raw material prepared in the step (1) into a mixer, and then spraying 3-5 parts by weight of water for primary mixing for 5-9min; (3) Secondary mixing granulation, namely placing the mixture obtained by primary mixing in the step (2) into a secondary strong mixer, and spraying 3-5 parts by weight of water at the same time to perform secondary mixing granulation to obtain sintering raw material particles, wherein the particle size range of the sintering raw material particles is 0.5-12mm; (4) Material bed cloth: a single-layer multi-roller distributor is arranged above the material bed, the multi-roller distributor is obliquely arranged, the advancing direction of the multi-roller distributor is opposite to the advancing direction of the material bed, the bottom end of the multi-roller distributor is arranged to face forwards