CN111234885A

CN111234885A - Hot rolling mill gas purification material and device and method for reducing oxidation burning loss of steel billets

Info

Publication number: CN111234885A
Application number: CN201911389444.8A
Authority: CN
Inventors: 潘荣汉; 李雷; 汪洋; 陈晓文
Original assignee: Shanghai Jueyou Energy Conservation And Environmental Protection Technology Co Ltd
Current assignee: Shanghai Jibo Laser Technology Co ltd
Priority date: 2019-12-30
Filing date: 2019-12-30
Publication date: 2020-06-05
Anticipated expiration: 2039-12-30
Also published as: CN111234885B

Abstract

The invention relates to the technical field of gas purification and billet heating of hot rolling mills, and discloses a material for adsorbing sulfides, nitrogen oxides and water vapor in gas of hot rolling mills and a device for reducing oxidation burning loss in a billet heating process by using the adsorbing material, wherein the adsorbing material consists of 85-98% of pellet ore and 2-15% of active alumina in volume ratio, the device comprises at least two biconical adsorbing cylinders, each biconical adsorbing cylinder consists of a middle straight cylinder, a top conical cylinder and a bottom conical cylinder, the middle straight cylinder is filled with the adsorbing material, and the top and the bottom of the middle straight cylinder are respectively provided with a stainless steel plate with honeycomb holes. Coal gas enters from the conical cylinder at the bottom of the adsorption cylinder, flows out from the conical cylinder at the top after diffusing and flowing through the adsorption material in the straight cylinder at the middle part, and sulfides, nitrogen oxides and water vapor in the coal gas are adsorbed by the adsorption material, so that the coal gas is purified, and the oxidation rate is greatly reduced when the purified coal gas enters into a heating furnace for combustion.

Description

Hot rolling mill gas purification material and device and method for reducing oxidation burning loss of steel billets

Technical Field

The invention relates to the technical field of hot rolling mill gas purification and billet heating, in particular to a hot rolling mill gas purification material, and a device and a method for reducing the thickness of an oxide scale in the heating process of a hot rolling billet.

Background

By 2018, the steel yield in China reaches 8 hundred million tons, wherein the capacity of the hot rolled plate strip reaches 3 hundred million tons/year, the hot rolled plate strip is a product with higher added value in steel products and is widely applied to automobile skins, electronic product shells, mechanical structural parts and the like, the production process of the hot rolled plate strip needs to be heated for many times, after the continuous casting billet is produced, heating is needed during rough rolling and cogging, multiple times of heating are needed during the middle rolling process, the heating temperature range in the heating furnace is 1100-1250 ℃, the heating time is 0.5-3 h, oxide skin is formed on the surface of the billet during each heating, oxidation burning loss is generated, the oxidation burning loss is 1-2.5%, calculated according to the average burning loss of 1.5%, if the oxidation burning loss can be reduced by 50%, 225 million tons of hot rolled plate strips can be saved every year, and 135 million yuan can be saved according to the average 6000 yuan/ton of the hot rolled plate strips, so that the method has great economic benefit and social benefit. Steel rolling billets are heated by adopting gas, but the gas source is complex, mainly byproduct gas generated by steel plant coking, iron making and steel making is mixed gas of coke oven gas, blast furnace gas and converter gas, wherein the coke oven gas generated by coking has the highest heat value which can reach 16720-18810 kJ/m3, the proportion is also the largest, but the coke oven gas contains a certain amount of sulfides (H2S, SO2, carbonyl S, CS2 and the like) and nitrogen oxides (NO, NO2 and the like), the blast furnace gas generated by iron making also contains a certain amount of sulfides (H2S, SO2 and the like), the content of sulfides and nitrogen oxides can be greatly reduced after the gas is subjected to temperature reduction, dust removal, naphthalene removal, oil removal, ammonia washing, benzene washing, desulfurization, denitrification and the like, the gas is stored in a cabinet after being treated, although the gas is subjected to desulfurization and denitrification treatment, the gas after being put in the cabinet still contains a certain amount of sulfides and nitrogen oxides (NO, NO2, etc.) concentration is generally 300-500 mg/m3, sulfide (H2S, SO2, etc.) concentration is 100-400 mg/m3, and the treated gas contains a certain amount of water vapor because water is used many times during the treatment process.

At present, in the process of heating steel billets by burning mixed gas in a steel mill, sulfides and nitrogen oxides can cause corrosion of steel on the one hand, and more importantly, the sulfides and the nitrogen oxides in the gas can also permeate into the grain boundary of the steel billets to destroy the formed compact oxide skin on the surface layer, so that the formed oxide skin is loose and porous, more oxygen is promoted to react with iron, the oxide skin is thickened, and the oxidation burning loss is increased. On the other hand, research shows that water vapor in the coal gas not only can cause the heat value of the coal gas to be reduced, but also can cause the oxide skin to be loose and porous, so that the oxidation burning loss is increased. Therefore, the invention provides a material capable of adsorbing sulfides, nitrogen oxides and water vapor in the coal gas of a hot rolling mill, a device and a method for reducing the thickness of an oxide scale in the heating process of a hot rolling billet by using the material.

Disclosure of Invention

Technical problem to be solved

Aiming at the defects of the prior art, the invention provides a mixed material for adsorbing sulfide, nitrogen oxide and water vapor in coal gas, and a device and a method for applying the material to reduce the thickness of an oxide scale in the heating process of a hot-rolled steel billet, so that the problems that the sulfide, the nitrogen oxide and the water vapor can cause corrosion of steel on one hand and penetrate into a billet grain boundary to destroy a formed compact oxide scale on the surface layer in the process of heating the steel billet by burning the coal gas, the formed oxide scale is loose and porous, more oxygen is promoted to react with iron, the oxide scale is thickened, and the oxidation burning loss is increased are solved.

(II) technical scheme

In order to achieve the purpose of reducing the oxidation burning loss in the heating process of the hot-rolled steel billet, the invention provides the following technical scheme: the adsorbing material is a mixture consisting of pellet particles and porous active alumina particles for blast furnace ironmaking, the sum of the pellet particles and the active alumina particles is spherical, the particle diameter is larger than 5mm and smaller than 30mm, the volume ratio of the active alumina particles in the mixture is 2-15%, and the volume ratio of the pellet particles is 85-98%.

A device for reducing the thickness of oxide scale in the heating process of hot-rolled steel billets comprises at least two biconical adsorption cylinders and a connecting gas pipeline, wherein the biconical adsorption cylinders are characterized in that: the whole straight shape by the middle part adsorbs a section of thick bamboo, a top toper section of thick bamboo and a bottom toper section of thick bamboo and constitutes, through mounting flange fixed connection between a straight shape adsorbs a section of thick bamboo, a top toper section of thick bamboo and the bottom toper section of thick bamboo, between top toper section of thick bamboo and the gas pipeline of being connected and between a bottom toper section of thick bamboo and the gas pipeline all through flange fixed connection, the equal fixed mounting in top and the bottom of a straight shape adsorption section of thick bamboo has honeycomb holes corrosion resistant plate, the inside adsorption material that all fills of well straight shape adsorption section of thick bamboo.

Preferably, the top conical cylinder on the left side is connected with the bottom conical cylinder on the right side through a gas pipeline, and the flowing direction of gas is from bottom to top.

Preferably, the straight adsorption cylinder, the top conical cylinder and the bottom conical cylinder are all stainless steel cylinders, and the top conical cylinder and the bottom conical cylinder can be detached independently.

Preferably, the honeycomb holes of the honeycomb stainless steel plate are a plurality of through holes along the thickness direction of the plate, the diameter of each through hole is larger than 2mm and smaller than 4mm, and the thickness of the stainless steel plate is larger than 20 mm.

Another technical problem to be solved by the present invention is to provide a method for reducing the thickness of oxide scale in the heating process of hot-rolled steel billets, comprising the following steps:

1) introducing coal gas into the left straight adsorption cylinder through a coal gas conveying pipeline and the left bottom conical cylinder;

2) the first purification treatment, after the coal gas enters the inside of the left straight adsorption cylinder, the coal gas is purified by utilizing an adsorption material;

3) transferring, after the first purification treatment is finished, conveying the coal gas to the inside of the right-side bottom conical cylinder by using the left-side top conical cylinder and a connecting coal gas pipeline, and introducing the coal gas into the inside of the right-side straight adsorption cylinder;

4) multiple purification treatment, namely, after the coal gas enters the right straight adsorption cylinder, performing multiple purification treatment on the coal gas by using the adsorption material again;

5) after the purification is finished, the hot rolled steel billet of the heating furnace is heated by burning the coal gas introduced into the hot rolled steel billet by using the tapered cylinder at the top of the right side and the gas conveying pipeline after the multiple purification treatment is finished.

(III) advantageous effects

Compared with the prior art, the invention provides a hot rolling mill gas purification material and a device and a method thereof for reducing oxidation burning loss of steel billets, and the device and the method have the following beneficial effects:

the invention relates to a coal gas purifying material for a hot rolling steel mill, which is formed by mixing pellet ore and active alumina through an adsorbing material, wherein the pellet ore is a charging material for iron making of a blast furnace of the hot rolling steel mill, the main component of the charging material is Fe2O3, and the charging material contains a certain amount of FeO, TiO2, SiO2, Al2O3, MgO, CaO, V2O5, MnO, P2O5 and the like, and has the characteristics of multiple micropores, high porosity, good air permeability and large specific surface area. Therefore, the material of the invention can adsorb sulfide and nitrogen oxide in coal gas, and can also adsorb water vapor in coal gas, thereby achieving the purpose of purifying coal gas. The pellet ore is the furnace charge for blast furnace ironmaking in the hot rolling steel mill, the source is convenient, the used adsorbing material can be directly used for blast furnace ironmaking without any treatment, and the resource is fully utilized, so that compared with other materials and methods for purifying coal gas, the material provided by the invention is derived from the ironmaking furnace charge of the steel mill, can be directly used for ironmaking after adsorption, and is extremely low in cost.

The invention relates to a device and a method for reducing the thickness of oxide scale in the heating process of hot rolling billets, wherein an adsorbing material only needs to be arranged in a double-cone adsorbing cylinder, gas can pass through the double-cone adsorbing cylinder, the installation is convenient, the existing gas conveying system of a steel rolling mill does not need to be greatly modified, only a gas outlet pipeline part needs to be connected with the device, a straight adsorbing cylinder 1 is connected with a top cone cylinder 2 and a bottom cone cylinder 3 through flanges, the fast filling and replacement of the adsorbing cylinder and the adsorbing material are convenient, when the adsorption efficiency is reduced, the whole adsorbing cylinder can be replaced by a new double-cone adsorbing cylinder, the adsorbing material 4 in the detached double-cone adsorbing cylinder can be replaced, the adsorbing material 4 in the inner part is taken out, the new adsorbing material 4 is arranged in the adsorbing cylinder, and the replaced adsorbing material can be used for blast furnace iron making. The material and the device of the invention can greatly reduce the contents of sulfide, nitrogen oxide and water vapor in the mixed gas of a steel mill, thereby reducing the oxidation rate of hot rolling steel billets in a gas heating furnace, greatly reducing the oxidation burning loss of the steel billets and achieving the purpose of reducing the oxidation burning loss of hot rolling steel plates.

Drawings

FIG. 1 is a schematic structural view of an apparatus for reducing the thickness of an oxide scale during a heating process of a hot rolled steel slab according to the present invention.

In the figure: the device comprises a straight adsorption cylinder 1, a conical cylinder at the top of 2, a conical cylinder at the bottom of 3, an adsorption material 4, a connecting flange 5, a stainless steel plate with honeycomb holes 6, a mounting flange 7, a gas pipeline 8 and a gas pipeline 9.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The low-cost adsorption material capable of purifying coal gas of a hot rolling mill can adsorb sulfides, nitrogen oxides and water vapor in the coal gas, the adsorption material is a mixture of pellet ore and porous active alumina for blast furnace ironmaking, the volume ratio of active alumina particles in the mixture is 2-15%, the volume ratio of pellet ore particles is 85-98%, the shapes of the pellet ore particles and the active alumina particles are spherical, and the particle diameter is larger than 5mm and smaller than 30 mm.

Large-scale steel mills have iron-making and steel-making processes, and the iron-making process comprises the following steps: the purchased concentrate powder is roasted into pellet ore or sinter ore, the pellet ore, the sinter ore and coke are added into a blast furnace, and the pellet ore and the sinter ore are smelted into molten iron. After molten iron is subjected to ladle, the molten iron is processed into molten steel after component preparation, degassing, impurity removal and other treatment, then the molten steel is continuously cast into steel billets, the steel billets are heated to 1100-1250 ℃ for rough rolling and medium rolling, and finally, cold finish rolling is carried out. The pellet ore and the sinter ore are both methods for agglomeration of fine ore, and both methods are characterized in that purchased fine iron ore powder is prefabricated into a ball shape or a block shape with a certain size, and the fine iron powder is made into a block body which can be put into a blast furnace for iron making and is convenient to transport. Compared with the sintered ore, the energy consumption for producing the pellet ore is 40-50% lower than that of the sintered ore, the pellet ore has high strength, more micropores and high porosity, and is convenient for reduction reaction in a blast furnace, so that the existing newly-built factory is generally a pellet ore production factory, and the pellet ore and the sintered ore can be added into the blast furnace for iron making independently or can be mixed according to a certain proportion for use. The particle size of the concentrate powder for producing the pellet is small, the specific surface area is 1500-3000 cm2/g between minus 325 and plus 200 meshes (44-74 mu m), a binder is required to be added for producing the pellet, the binder is generally bentonite, slaked lime and limestone, the concentrate powder is processed into a sphere by a ball making machine, Fe3O4 in the pellet is oxidized and recrystallized into Fe2O3 in the roasting process under certain temperature and atmosphere, the Fe2O3 microcrystal is diffused and formed to form microcrystal bonds, and the grown particles in the green pellet are adhered together by the microcrystal bonds to form the high-strength, porous and air-permeable pellet which becomes a blast furnace ironmaking furnace burden. The main component of the pellet is Fe2O3, and simultaneously contains a certain amount of FeO, TiO2, SiO2, Al2O3, MgO, CaO, V2O5, MnO, P2O5 and the like, wherein the total Fe content is generally more than 60 wt%, and the specific component content is different according to different mineral powder production areas. The pellet is a spherical blast furnace burden with multiple micropores, high porosity, good air permeability and large specific surface area, and has high adsorption capacity to gas due to the large specific surface area and the multiple micropores. Therefore, the iron-smelting pellet blast furnace burden in a steel mill can be used for adsorbing sulfides and nitrides in coal gas, the adsorption is the combined action of physical adsorption and chemical adsorption, the adsorption mechanism is that the main component Fe2O3 of porous pellets is a metal oxide which is an n-type semiconductor (electron type semiconductor) with free electrons as main carriers, when the porous pellets are exposed to gas, the gas molecules are adsorbed on the surface of the material, the free electrons are abstracted by the gas molecules, and the gas molecules also become negative ions due to the gained electrons, such as oxidizing gas, for example, chemical adsorption NO2 molecules capture electrons and react: NO2+ e- → NO2-, thereby further generating nitrite or nitrate, and for SO2 gas, the reaction occurs after capturing electrons: SO2+ e- → SO2 "to further produce sulfite or sulfate, and also calcium oxide in the pellets has a desulfurizing action, CaO + SO2 → CaSO3, and on the other hand MnO in the pellets is also a metal oxide n-type semiconductor having a similar action to Fe2O3 to adsorb sulfide and nitrogen oxide and produce salts. As for the hydrogen sulfide gas, the following chemical reactions exist, Fe2O3+3H2S → Fe2S3+3H2O, or Fe2O3+3H2S → 2FeS +3H2O, in the process of adsorbing H2S, trace water is generated, Al2O3, CaO and P2O5 in the pellet ore are excellent drying agents and can adsorb water vapor, so that the synergistic corrosion effect of sulfide, nitrogen oxide and water vapor is avoided, therefore, a plurality of oxides in the pellet ore can act synergistically, the contents of sulfide and nitrogen oxide in coal gas can be greatly reduced, and the oxidation loss amount of billets in the combustion process is reduced. Furthermore, a certain amount of activated alumina is added into the adsorbing material 4, the adding amount is 2-15% of the total volume of the adsorbing material 4, the adding purpose is to adsorb water in the coal gas, and because a certain amount of water is generated in the process of adsorbing H2S gas by the pellet, although the pellet has the existence of excellent drying agents such as Al2O3, CaO and P2O5, the content of the drying agents is unstable, and a certain amount of activated alumina is added into the pellet to remove water in the coal gas. The active alumina (gamma-Al 2O3) is a porous substance, has high activity and strong adsorption capacity, stable chemical property, good pressure resistance, wear resistance and heat resistance, and strong affinity with water, is a strong drying agent, because the content of Al2O3, CaO and P2O5 of the pellet produced by different manufacturers is different, the water absorption capacity of the pellet per se is changed, when the content of the added active alumina is less than 2 percent, the water absorption effect is not good, after the adding amount exceeds 15 percent, the material is excessive, and the cost is increased, therefore, the adsorbent consists of the pellet and the active alumina, wherein the pellet accounts for 85 to 98 percent and the active alumina accounts for 2 to 15 percent according to the volume ratio, the pellet produced by a steel mill has various diameters, the diameters of the pellet and the active alumina pellet used in the invention are 5 to 30mm and less than 5mm, the clearance between the spheres is too small, the gas passing resistance is large and is more than 30mm, the specific surface area is small, the clearance is too large, the adsorption capacity is weakened, the adsorbing material 4 formed by mixing the pellet and the activated alumina is uniformly mixed and then added into the stainless steel adsorption cylinder, and after the gas in the hot rolling mill is subjected to purification treatment by the material, the content of nitrogen oxides and sulfides in the gas is reduced by at least 70%, and the oxidation burning loss is reduced by at least more than 50%.

In order to purify gas and reduce oxidation burning loss of hot-rolled steel billets by using the adsorbing material, the invention provides a device for reducing the thickness of oxide scale in the heating process of the hot-rolled steel billets, and please refer to fig. 1, the device is composed of at least two biconical adsorbing cylinders and a connecting gas pipeline 8, and the biconical adsorbing cylinders are characterized in that: the integral structure of the gas-liquid separator is characterized by integrally comprising a middle straight adsorption cylinder 1, a top conical cylinder 2 and a bottom conical cylinder 3, wherein the straight adsorption cylinder 1, the top conical cylinder 2 and the bottom conical cylinder 3 are connected through a mounting flange 7, the top conical cylinder 2 and the bottom conical cylinder 3 are connected with a gas pipeline 8 and a gas pipeline 9 through a connecting flange 5, honeycomb hole stainless steel plates 6 are installed at the top and the bottom of the straight adsorption cylinder 1, the honeycomb hole stainless steel plates 6 are stainless steel plates with a plurality of through holes along the thickness direction of the plate, the diameter of each through hole is larger than 2mm and smaller than 4mm, the thickness of each stainless steel plate is larger than 20mm, the stainless steel plates need to bear the weight of the adsorption material 4, the thickness of each stainless steel plate is not smaller than 20mm, the gas does not need to pass through the stainless steel plates at the same time, holes need to be formed in the stainless steel plates along the thickness direction, and the, the diameter of the honeycomb holes on the desired stainless steel plate is not more than 4mm, on the other hand, if the hole diameter is less than 2mm, the gas is difficult to pass through, so the diameter of the through holes needs to be more than 2mm, and the interior of the middle straight adsorption cylinder 1 is filled with the adsorption material 4. The left top conical cylinder 2 is connected with the right bottom conical cylinder 3 through a gas pipeline 8, and the gas flows from bottom to top. The straight adsorption cylinder 1, the top conical cylinder 2 and the bottom conical cylinder 3 are all stainless steel cylinders, the three sections are connected through mounting flanges 7, and the top conical cylinder 2 and the bottom conical cylinder 3 can be detached independently.

A method of reducing the thickness of scale during heating of a hot rolled steel slab comprising the steps of:

1) introducing coal gas, introducing the coal gas into the left straight adsorption cylinder 1 through a coal gas conveying pipeline 9 and the left bottom conical cylinder 3, wherein after the coal gas enters the conical cylinder 3 from the coal gas conveying pipeline 9, the sectional area is increased, the pressure is reduced, the flow rate of the coal gas is reduced, the coal gas is in full contact with the adsorption material 4, and the adsorption effect is increased;

2) the first purification treatment, after the coal gas enters the inside of the left straight adsorption cylinder 1, the coal gas is purified by the adsorption material 4;

3) transferring, after the first purification treatment is finished, conveying the coal gas to the inside of the right bottom conical cylinder 3 by using the left top conical cylinder 2 and a connecting coal gas pipeline 8, and introducing the coal gas into the inside of the right straight adsorption cylinder 1;

4) multiple purification treatment, namely, after the coal gas enters the right straight adsorption cylinder 1, performing multiple purification treatment on the coal gas by using the adsorption material 4 again;

5) after purification is finished, the gas is led out by using the right top conical barrel 2 and the gas conveying pipeline 9 after multiple purification treatments are finished, and is led into a hot rolling billet heating furnace for combustion.

The first embodiment is as follows:

heating 20 steel billets, wherein the thickness of the steel billets is 220mm, the width of the steel billets is 300mm, the volume percentage of pellet ore in the double-cone adsorption cylinders is 98%, the volume percentage of active alumina is 2%, the SO2 content in original mixed gas is 30mg/m3, the H2S content is 80mg/m3, the carbonyl sulfur content is 102mg/m3, the CS2 content is 192mg/m3, the NO content is 441mg/m3, the NO2 content is 52mg/m3, the water content is 40.1g/m3, and after the steel billets pass through the double-cone adsorption cylinders, the SO2 content in the mixed gas is 2mg/m3, the H2S content is 5mg/m3, the carbonyl sulfur content is 10mg/m3, the CS2 content is 3mg/m3, the NO content is 5mg/m3, the NO2 content is 2mg/m3, and the water content is 10g/m 3. Heating 20 steel billets by using coal gas purified by a double-conical adsorption cylinder, wherein the heating system is 1150 ℃ multiplied by 90min, cooling the steel billets to room temperature by using water spraying after heating, and measuring the thickness of an oxide scale to be 0.32 mm.

Comparative example one:

heating 20 steel billets, wherein the thickness of the steel billets is 220mm, the width of the steel billets is 300mm, the SO2 content in original mixed gas is 30mg/m3, the H2S content is 80mg/m3, the carbonyl sulfide content is 102mg/m3, the CS2 content is 192mg/m3, the NO content is 441mg/m3, the NO2 content is 52mg/m3, and the water content is 40.1g/m3, heating the 20 steel billets by the original mixed gas, wherein the heating system is 1150 ℃ multiplied by 90min, after heating is finished, cooling the steel billets to room temperature by adopting water spray, and measuring the thickness of an oxide scale to be 0.81 mm.

Example two:

a42 CrMoV steel billet is heated, the thickness of the steel billet is 150mm, the width of the steel billet is 240mm, the volume ratio of pellets in a double-cone-shaped adsorption cylinder is 90%, the volume of active alumina is 5%, the SO2 content in original mixed gas is 30mg/m3, the H2S content is 80mg/m3, the carbonyl sulfur content is 102mg/m3, the CS2 content is 192mg/m3, the NO content is 441mg/m3, the NO2 content is 52mg/m3, the water content is 40.1g/m3, after the mixed gas passes through the double-cone-shaped cylinder, the SO2 content in the mixed gas is 2.2mg/m3, the H2S content is 4.5mg/m3, the carbonyl sulfur content is 10.61mg/m3, the CS2 content is 2.6mg/m3, the NO content is 6.2mg/m3, the NO2 content is 1.8mg/m3, and the water content is 5g/m3 g/m. The 42CrMoV steel billet is heated by adopting coal gas purified by a biconical adsorption cylinder, the heating system is 1200 ℃ multiplied by 120min, after the heating is finished, the temperature of the steel billet is cooled to room temperature by adopting water spraying, and the thickness of the oxide scale is measured to be 0.23 mm.

Comparative example two: heating 42CrMoV steel billets with the thickness of 150mm and the width of 240mm, wherein the SO2 content in original mixed gas is 30mg/m3, the H2S content is 80mg/m3, the carbonyl sulfide content is 102mg/m3, the CS2 content is 192mg/m3, the NO content is 441mg/m3, the NO2 content is 52mg/m3, the water content is 40.1g/m3, heating the 42CrMoV steel billets by using the original mixed gas with the heating system of 1200 ℃ multiplied by 120min, cooling the steel billets to room temperature by using water spray after heating is finished, and measuring the thickness of an oxide scale to be 0.93 mm.

Example three:

heating a stainless steel 1Cr25Ni20Si2 billet, wherein the thickness of the billet is 260mm, the width is 300mm, the volume ratio of pellet ore in a double-cone adsorption cylinder is 85%, the volume of active alumina is 15%, the SO2 content in original mixed gas is 30mg/m3, the H2S content is 80mg/m3, the carbonyl sulfur content is 102mg/m3, the CS2 content is 192mg/m3, the NO content is 441mg/m3, the NO2 content is 52mg/m3, the water content is 40.1g/m3, after the mixed gas passes through the double-cone adsorption cylinder, the SO2 content in the mixed gas is 2.5mg/m3, the H2S content is 4.8mg/m3, the carbonyl sulfur content is 11.6mg/m3, the CS2 content is 3.7mg/m3, the NO content is 7.2mg/m3, the NO2 content is 1.5mg/m 3g/m and the water content is 3 g/m. Heating 1Cr25Ni20Si2 steel billet with coal gas passing through a biconical adsorption purification cylinder at 1250 deg.C for 120min, cooling the steel billet to room temperature by water spray after heating, and measuring the thickness of oxide scale to be 0.15 mm.

Comparative example three:

a stainless steel 1Cr25Ni20Si2 billet is heated, the thickness of the billet is 260mm, the width of the billet is 300mm, the SO2 content in the original mixed gas is 30mg/m3, the H2S content is 80mg/m3, the carbonyl sulfide content is 102mg/m3, the CS2 content is 192mg/m3, the NO content is 441mg/m3, the NO2 content is 52mg/m3, and the water content is 40.1g/m 3. Heating the steel billet by using original mixed gas, wherein the heating system is 1250 ℃ multiplied by 120min, cooling the steel billet to room temperature by using water spray after heating is finished, and measuring the thickness of an oxide scale to be 0.45 mm.

And (4) judging the standard:

comparing example 1 with comparative example 1, for the common 20 # steel with 0.2% carbon content, the purified gas and combustion air can reduce the oxide scale thickness from 0.81mm to 0.32mm, and the reduction of oxidation burning loss reaches 60%.

Comparing example 2 with comparative example 2, for 42CrMoV steel billet, the purified gas and combustion air can reduce the thickness of the oxide scale from 0.93mm to 0.15mm, and the reduction range of the oxidation burning loss reaches 83 percent.

Comparing example 3 with comparative example 3, for stainless steel 1Cr25Ni20Si2 billet, the purified gas and combustion air can reduce the thickness of the oxide scale from 0.45mm to 0.15mm, and the reduction range of the oxidation burning loss reaches 67%.

Therefore, the method has very obvious effect on reducing the oxidation burning loss.

The invention has the beneficial effects that: the invention has the beneficial effects that: the device and the method for reducing the thickness of oxide scale in the heating process of hot rolled steel billets are characterized in that the main body of the adsorbing material 4 is pellet blast furnace burden of a steel rolling mill, the adsorbing performance is high, the adsorbing material can be directly used for blast furnace ironmaking after adsorption, materials are not wasted, the cost is extremely low, the adsorbing material 4 only needs to be arranged in the straight adsorbing cylinder 1, and coal gas passes through the double-cone adsorbing cylinder, so that the installation is convenient, the existing coal gas conveying system of the steel rolling mill is not required to be greatly modified, only a cone-shaped adsorbing system needs to be additionally arranged on a coal gas outlet pipeline part, the adsorbing material 4 consists of pellet and active alumina, the main component of the pellet is Fe2O3 and contains a certain amount of mixed oxides of FeO, TiO2, SiO2, Al2O3, MgO, CaO, V2O5, MnO, P2O5 and the like, the sulfide and nitrogen oxide can be adsorbed, and the water in the coal gas can be adsorbed after a certain amount of porous active, the adsorption efficiency is high, the straight adsorption cylinder 1, the top conical cylinder 2 and the bottom conical cylinder 3 are connected through flanges, so that the double-conical adsorption cylinder can be integrally and quickly replaced, when the adsorption efficiency is reduced, the double-conical adsorption cylinder is integrally replaced by a new double-conical adsorption cylinder, the adsorption material 4 in the adsorption cylinder after being detached can be replaced, the adsorption material 4 in the adsorption cylinder is taken out, a new adsorption material 4 is loaded, and the replaced pellet ore can be used for blast furnace ironmaking, so that the contents of sulfide, nitric oxide and water vapor in mixed gas of a rolling mill are greatly reduced, the oxidation rate of hot rolling billets in a heating furnace is reduced, the oxidation burning loss of the billets is greatly reduced, the purpose of reducing the oxidation burning loss is achieved, the problem that the sulfide, the nitric oxide and the water vapor act together in the process of heating the billets through gas combustion is solved, on one hand, the corrosion of steel can be caused is solved, on the other, the formed compact oxide skin on the surface layer is damaged, so that the formed oxide skin is loose and porous, more oxygen is promoted to react with iron, and the problems of thickening of the oxide skin and increase of the oxidation burning loss are caused.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims

1. The adsorbing material for purifying the coal gas of the hot rolling mill is characterized by being formed by mixing pellets and porous active alumina particles for blast furnace ironmaking, wherein the pellets and the active alumina particles are spherical, the particle diameter is larger than 5mm and smaller than 30mm, the volume ratio of the active alumina particles in the mixture is 2-15%, and the volume ratio of the pellets is 85-98%.

2. The device for reducing the thickness of the oxide scale in the heating process of the hot-rolled steel billet comprises at least two biconical adsorption cylinders and a connecting gas pipeline (8), and is characterized in that: the whole straight adsorption cylinder (1), top toper section of thick bamboo (2) and bottom toper section of thick bamboo (3) of being directed by the middle part constitute, through mounting flange (7) fixed connection between straight adsorption cylinder (1), top toper section of thick bamboo (2) and the bottom toper section of thick bamboo (3), all through flange (5) fixed connection between top toper section of thick bamboo (2) and the connection gas pipeline (8) and between bottom toper section of thick bamboo (3) and the conveying gas pipeline (9), the equal fixed mounting in top and the bottom of straight adsorption cylinder (1) has honeycomb holes corrosion resistant plate (6), well straight adsorption cylinder (1) inside all is filled with adsorption material (4).

3. The apparatus of claim 2 wherein the scale is reduced during heating of the hot rolled steel slab by: the left top conical cylinder (2) is connected with the right bottom conical cylinder (3) through a gas pipeline (8), and the flowing direction of gas is from bottom to top.

4. The apparatus of claim 1 wherein the thickness of the scale is reduced during heating of the hot rolled steel slab by: the straight adsorption cylinder (1), the top conical cylinder (2) and the bottom conical cylinder (3) are all stainless steel cylinders, and the top conical cylinder (2) and the bottom conical cylinder (3) can be detached independently.

5. The apparatus of claim 1 wherein the thickness of the scale is reduced during heating of the hot rolled steel slab by: honeycomb hole corrosion resistant plate (6) are installed to the top and the bottom of straight shape adsorption cylinder (1), the honeycomb hole of honeycomb hole corrosion resistant plate (6) is numerous through-holes along the board thickness direction, and the through-hole diameter is greater than 2mm, is less than 4mm, corrosion resistant plate thickness is greater than 20 mm.

6. A method for reducing the thickness of scale during the heating of a hot rolled steel slab, comprising the steps of:

1) introducing coal gas into the left straight adsorption cylinder (1) through a coal gas conveying pipeline (9) and the left bottom conical cylinder (3);

2) the first purification treatment, after the coal gas enters the inside of the left straight adsorption cylinder (1), the adsorption material (4) is used for purifying the coal gas;

3) after the first purification treatment is finished, conveying the coal gas into the right bottom conical cylinder (3) by using the left top conical cylinder (2) and a connecting coal gas pipeline (8), and guiding the coal gas into the right straight adsorption cylinder (1);

4) multiple purification treatment, namely, after the coal gas enters the right straight adsorption cylinder (1), performing multiple purification treatment on the coal gas by using the adsorption material (4) again;

5) after purification is finished, the hot rolled steel billet of the heating furnace is introduced with gas by using the right top conical barrel (2) and the gas conveying pipeline (9) for combustion heating after the multiple purification treatment is finished.