CN109628708B - Environment-friendly and energy-saving stainless steel strip annealing and pickling method - Google Patents
Environment-friendly and energy-saving stainless steel strip annealing and pickling method Download PDFInfo
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- CN109628708B CN109628708B CN201811644973.3A CN201811644973A CN109628708B CN 109628708 B CN109628708 B CN 109628708B CN 201811644973 A CN201811644973 A CN 201811644973A CN 109628708 B CN109628708 B CN 109628708B
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/26—Methods of annealing
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
- C21D9/54—Furnaces for treating strips or wire
- C21D9/56—Continuous furnaces for strip or wire
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
- C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
- C23G1/02—Cleaning or pickling metallic material with solutions or molten salts with acid solutions
- C23G1/08—Iron or steel
- C23G1/086—Iron or steel solutions containing HF
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25F—PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
- C25F1/00—Electrolytic cleaning, degreasing, pickling or descaling
- C25F1/02—Pickling; Descaling
- C25F1/04—Pickling; Descaling in solution
- C25F1/06—Iron or steel
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Abstract
The invention discloses an environment-friendly and energy-saving stainless steel strip annealing and pickling method, which comprises the following steps: (1) annealing the cold-rolled stainless steel strip; (2) cooling the heated stainless steel band to below 180 ℃ through an air cooling section; (3) cooling the stainless steel band after air cooling to below 70 ℃ through a water cooling section; (4) removing water from the water-cooled stainless steel band; (5) drying the stainless steel band by using smoke and waste heat generated by a heating area; (6) the stainless steel band is processed by electrolysis through an electrolytic bath; (7) carrying out three-stage pickling treatment on the stainless steel strip through a pickling tank; (8) 4-6 stages of cascade rinsing are carried out on the stainless steel band, and the stainless steel band is dried; (9) and (4) straightening and flattening the pickled stainless steel band to obtain a finished stainless steel band product. By adopting the invention, the heat energy loss can be reduced in the annealing process, the acid discharge and the electric energy loss can be reduced in the acid washing process, and the discharged waste water and waste gas can be recycled, thereby realizing energy conservation and emission reduction.
Description
Technical Field
The invention relates to the technical field of stainless steel, in particular to an environment-friendly and energy-saving stainless steel strip annealing and pickling method.
Background
The stainless steel band is an extension of the ultrathin stainless steel plate, is a narrow and long steel plate produced by meeting the requirements of different industrial departments for industrially producing various types of metal or mechanical products, is widely applied to high-technology industry, IT industry and aviation and aerospace industry, and has high added value.
In order to remove the stress generated after rolling, an annealing process is mostly used, and scale or oxide layers are formed on the surface of the strip steel during the rolling and annealing processes of the stainless steel and the acid-resistant alloy steel, so that the strip steel needs to be pickled after the annealing process. However, the annealing temperature of the existing annealing process is high, the consumed heat energy is large, and the existing annealing process is not beneficial to energy conservation and environmental protection. Moreover, the pickling process discharges a large amount of wastewater and waste gas, and how to solve the problem of environmental pollution in the annealing and pickling processes of the stainless steel strip becomes a problem to be solved urgently.
Disclosure of Invention
The invention aims to solve the technical problem of providing an environment-friendly and energy-saving stainless steel strip annealing and pickling method, wherein the annealing process can reduce heat energy loss, the pickling process can reduce acid emission and electric energy loss, and the discharged wastewater and waste gas are recycled to realize energy conservation and emission reduction.
In order to solve the problems, the invention provides an environment-friendly and energy-saving stainless steel strip annealing and pickling method, which comprises the following steps:
(1) conveying the cold-rolled stainless steel strip to a heating section of an annealing furnace, wherein the heating section of the annealing furnace sequentially comprises an inlet sealing section, a preheating zone, a heating zone and an outlet sealing section,
conveying the cold-rolled stainless steel strip to an inlet sealing section of an annealing furnace, and preheating the stainless steel strip in a preheating zone by using convection and radiation of flue gas generated in a heating zone so as to heat the stainless steel strip from 30 ℃ to T1，T1＝250-300℃；
The preheated stainless steel band is conveyed to a heating zone and is heated by flame sprayed from a burner so as to enable the stainless steel band to be heated from T1Heating to 1160 ℃ for at least 15 seconds at a temperature of above 1080 ℃, and then conveying the heated stainless steel belt to an outlet sealing section;
(2) cooling the heated stainless steel band to below 180 ℃ through an air cooling section;
(3) cooling the stainless steel band after air cooling to below 70 ℃ through a water cooling section;
(4) removing water on the surface of the stainless steel strip by the water-cooled stainless steel strip through a wringing roller;
(5) drying the stainless steel band by using flue gas and waste heat generated in a heating zone, and treating the flue gas after drying treatment by using a flue gas and waste gas washing tower;
(6) the dried stainless steel strip is processed by electrolysis through an electrolytic bath with Na as a medium2SO4The solution is electrolyzed and then first waste gas and first wastewater are discharged, the first waste gas is treated by a first waste gas treatment system, and the first wastewater is treated by a first wastewater treatment system;
(7) carrying out three-stage pickling treatment on the stainless steel strip by a pickling tank, wherein the medium of the pickling tank is HNO3And HF, discharging second waste gas and second waste water after acid washing treatment, wherein the second waste gas is treated by a second waste gas treatment system, and the second waste water is treated by second waste waterThe processing system carries out processing;
(8) 4-6 stages of cascade rinsing are carried out on the stainless steel band, and the stainless steel band is dried;
(9) and (4) straightening and flattening the pickled stainless steel band to obtain a finished stainless steel band product.
As an improvement of the scheme, the first waste gas treatment system comprises a fan, a deep spraying area, a liquid drop separator and a demister, waste gas generated by electrolysis treatment and sodium sulfate regeneration is guided to the deep spraying area through the fan, the first waste gas is contacted with a washing solution in the deep spraying area, and liquid drop separation is realized through the liquid drop separator and the demister, wherein the washing solution in the deep spraying area is desalted water.
As an improvement of the scheme, the second waste gas treatment system comprises a hydrofluoric acid washing tower and a denitrification device, acid components in the second waste gas are removed through the hydrofluoric acid washing tower until the acid components are reduced to a limit value, and then the nitrogen oxides are reduced through the denitrification device.
As the improvement of the scheme, the flue gas and waste gas washing tower comprises a collecting disc, a washing tower, a fog collector, a chemical centrifugal pump and a radial fan, wherein flue gas vertically passes through the washing tower from the collecting disc upwards under the action of the radial fan, and is in large-area contact with washing liquid under the action of the chemical centrifugal pump, and then is collected through the fog collector.
As a modification of the above, the first wastewater treatment system includes a first wastewater discharge device and a first wastewater recovery device, and the second wastewater treatment system includes a second wastewater discharge device and a second wastewater recovery device.
As an improvement of the above, the second wastewater discharge device controls HNO3The amount of waste of the mixture with HF is V and the volume of the steel strip in the medium of the pickling tank is V1, then
V＝(4ml/m3-6ml/m3)*V1。
As a modification of the above solution, the electrolytic bath comprises a first electrolytic bath, and the pickling bath comprises a first pickling bath, a second pickling bath, and a third pickling bath, wherein,
na of the first electrolytic tank2SO4The concentration of the solution is less than 200g/L, the concentration of metal ions is less than 15g/L, the temperature is 75-85 ℃, and the current density is 0-20A/dm2The concentration of hexavalent chromium is less than 5g/L, and the content of suspended matters is less than 4 g/L;
HNO of the first pickling tank3The concentration of the metal ions is 80-150g/L, the concentration of HF is 3-40g/L, the concentration of the metal ions is less than 35g/L, and the temperature is 40-65 ℃;
HNO of the second acid wash tank3The concentration of the metal ions is 80-150g/L, the concentration of HF is 3-40g/L, the concentration of the metal ions is less than 35g/L, and the temperature is 40-65 ℃;
HNO of the third pickling tank3The concentration of the metal ions is 80-150g/L, the concentration of HF is 3-40g/L, the concentration of the metal ions is less than 35g/L, and the temperature is 40-65 ℃.
As an improvement of the scheme, the thickness of the stainless steel belt is 0.3-3mm, and the transmission speed is 100-200 m/min.
As an improvement of the scheme, the length of the annealing furnace is 240m for 200-;
the first plate thermometer is arranged at a position 90-100m away from the inlet of the annealing furnace and is used for controlling the temperature at 580-620 ℃;
the second plate thermometer is arranged at a position which is 115-125m away from the inlet of the annealing furnace and is used for controlling the temperature to be 1080 ℃;
the third plate thermometer is arranged at the position of 135-145m away from the inlet of the annealing furnace and is used for controlling the temperature at 1100-1160 ℃;
the fourth plate thermometer is arranged at the position which is 150-155m away from the inlet of the annealing furnace and is used for controlling the temperature at 950-980 ℃;
the fifth plate thermometer is arranged at a position 180-188m away from the inlet of the annealing furnace and is used for controlling the temperature at 400-460 ℃;
the sixth plate thermometer is arranged at a position 200-210m away from the inlet of the annealing furnace and is used for controlling the temperature to be between room temperature and 180 ℃;
the seventh plate thermometer is arranged at a position which is 220m away from the inlet of the annealing furnace and is used for controlling the temperature to be between room temperature and 70 ℃.
As an improvement of the scheme, the fourth plate thermometer and the fifth plate thermometer are both arranged in an air cooling section of the annealing furnace, the air cooling section between the fourth plate thermometer and the fifth plate thermometer is arranged, and the cooling rate of the stainless steel band is more than 50 ℃/s;
the second plate temperature meter and the third plate temperature meter are both arranged in the heating section of the annealing furnace, the heating section between the second plate temperature meter and the third plate temperature meter, and the heating rate of the stainless steel band is maintained at 8-12 ℃/s.
The implementation of the invention has the following beneficial effects:
(1) according to the environment-friendly and energy-saving stainless steel strip annealing and pickling method provided by the invention, the convection and radiation of flue gas are utilized to slowly heat from 30 ℃ to 300 ℃ in 250-.
(2) The heating section in the annealing process comprises a preheating zone and a heating zone, wherein a heat source used in the preheating zone is flue gas convection and radiation generated by flame sprayed by a burner, so that the cyclic utilization of high-temperature waste gas in the furnace zone is realized, and the energy-saving effect is remarkable by utilizing the waste heat of the flue gas and applying preheated combustion-supporting air to combustion supporting. And moreover, the flue gas and the waste heat generated in the heating zone can also be used for drying the stainless steel band, and the flue gas after drying is treated by a flue gas and waste gas washing tower.
(3) According to the invention, by setting the arrangement position of the plate thermometer, the actual temperature of the steel strip can be accurately measured, and the furnace temperature setting and the speed setting are adjusted according to the actual temperature of the steel strip, so that the correct execution of a heat treatment process is ensured, and the stable mechanical property of the steel strip is ensured.
(4) The pickling process of the invention is characterized in that the relation between the waste discharge V of the pickling tank and the volume V1 of the steel strip in the medium of the pickling tank is set, wherein V is (4 ml/m)3-6ml/m3) V1, so as to be able to operate according toThe speed and the thickness of the stainless steel strip are used for obtaining the real-time volume of the steel strip in the pickling medium, then the waste discharge amount is adjusted in real time, and a balance is achieved between the consumption of metal ions and the consumption of acid, so that the acid discharge is reduced, the power consumption is reduced, and the energy conservation and emission reduction are realized.
(5) The invention can also carry out HNO treatment on the first pickling tank, the second pickling tank and the third pickling tank according to the waste discharge amount3And HF are added in an amount adjusted to efficiently remove the scale layer and the chrome-free belt.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail below.
The invention provides an environment-friendly and energy-saving stainless steel strip annealing and pickling method, which comprises the following steps:
(1) and conveying the cold-rolled stainless steel strip to a heating section of an annealing furnace, and directly heating the stainless steel strip by flame sprayed by a burner so that the stainless steel strip is heated from 30 ℃ to 1160 ℃ for at least 15 seconds at the temperature of above 1080 ℃.
The stainless steel strip is subjected to cold rolling treatment before annealing, and the cold rolling treatment comprises the following steps:
carrying out first cold rolling on the stainless steel strip blank through a first cold rolling mill, wherein the tension at the inlet of the first cold rolling mill is 240-260 KN, the tension at the outlet of the first cold rolling mill is 490-650 KN, the rolling force of the first cold rolling mill is 9600-9800 KN, and the rolling speed of the first cold rolling mill is 60-110 m/min;
carrying out second-pass cold rolling on the stainless steel strip blank subjected to the first-pass cold rolling through a second cold rolling mill, wherein the tension at the outlet of the second cold rolling mill is 440-700 KN, the rolling force of the second cold rolling mill is 10000-11000 KN, and the rolling speed of the second cold rolling mill is 80-150 m/min;
carrying out third cold rolling on the stainless steel strip blank subjected to the second cold rolling pass through a third cold rolling mill, wherein the tension at the outlet of the third cold rolling mill is 390-650 KN, the rolling force of the third cold rolling mill is 9400-9600 KN, and the rolling speed of the third cold rolling mill is 90-220 m/min;
carrying out fourth-pass cold rolling on the stainless steel strip blank subjected to the third-pass cold rolling through a fourth cold rolling mill, wherein the tension at the outlet of the fourth cold rolling mill is 340-600 KN, the rolling force of the fourth cold rolling mill is 9100-9350 KN, and the rolling speed of the fourth cold rolling mill is 110-280 m/min;
carrying out fifth-pass cold rolling on the stainless steel strip blank subjected to fourth-pass cold rolling through a fifth cold rolling mill, wherein the tension at the outlet of the fifth cold rolling mill is 310-560 KN, the rolling force of the fifth cold rolling mill is 8900-9100 KN, and the rolling speed of the fifth cold rolling mill is 120-310 m/min;
carrying out sixth cold rolling on the stainless steel strip blank subjected to fifth cold rolling through a sixth cold rolling mill, wherein the tension at the outlet of the sixth cold rolling mill is 230-500 KN, the rolling force of the sixth cold rolling mill is 8700-9000 KN, and the rolling speed of the sixth cold rolling mill is 130-400 m/min;
and cleaning the stainless steel strip blank subjected to the sixth cold rolling.
The rolled finished product enters an annealing furnace for annealing treatment, the heating treatment is carried out through a heating section, and the cooling treatment through an air cooling section and a water cooling section is carried out, so that the mechanical processing performance after cold rolling can be greatly improved only by one-time annealing treatment.
The heating section of the annealing furnace sequentially comprises an inlet sealing section, a preheating zone, a heating zone and an outlet sealing section, preferably, the length of the inlet sealing section is 1-3m, the length of the preheating zone is 25-35m, the length of the heating zone is 55-80m, and the length of the outlet sealing section is 2-5 m. The inlet sealing section is inlet sealing equipment, the inlet sealing section is provided with a waste gas circulating system and used for discharging the flue gas in the heating area to the inlet sealing section, and part of heat in the flue gas is recovered by the preheating section through convection and radiation. The outlet sealing section is outlet sealing equipment.
The heat treatment of the step (1) specifically comprises:
inlet seal for conveying cold rolled stainless steel strip to annealing furnaceA section for preheating the stainless steel strip by convection and radiation of flue gas in a preheating zone to heat the stainless steel strip from 30 ℃ to T1，T1＝250-300℃；
Conveying the preheated stainless steel strip to a heating area, and heating by flame sprayed from a burner so as to ensure that the stainless steel strip is heated from T1Heating to 1160 deg.C, and maintaining the temperature of the stainless steel band above 1080 deg.C for at least 15 s;
and conveying the heated stainless steel band to an outlet sealing section.
The stainless steel strip is slowly heated from 30 ℃ to 250-. And the annealing process is simplified, the high-temperature annealing time is shortened, and the production efficiency is improved.
Specifically, the length of the annealing furnace is 200-240m, the transmission speed of the stainless steel band is 160-220m/min, and the annealing furnace is provided with at least 7 sets of plate thermometers, including a first plate thermometer, a second plate thermometer, a third plate thermometer, a fourth plate thermometer, a fifth plate thermometer, a sixth plate thermometer and a seventh plate thermometer;
the first plate thermometer is arranged at a position 90-100m away from the inlet of the annealing furnace and is used for controlling the temperature at 580-620 ℃;
the second plate thermometer is arranged at a position which is 115-125m away from the inlet of the annealing furnace and is used for controlling the temperature to be 1080 ℃;
the third plate thermometer is arranged at the position of 135-145m away from the inlet of the annealing furnace and is used for controlling the temperature at 1100-1160 ℃;
the fourth plate thermometer is arranged at the position which is 150-155m away from the inlet of the annealing furnace and is used for controlling the temperature at 950-980 ℃;
the fifth plate thermometer is arranged at a position 180-188m away from the inlet of the annealing furnace and is used for controlling the temperature at 400-460 ℃;
the sixth plate thermometer is arranged at a position 200-210m away from the inlet of the annealing furnace and is used for controlling the temperature to be between room temperature and 180 ℃;
the seventh plate thermometer is arranged at a position which is 220m away from the inlet of the annealing furnace and is used for controlling the temperature to be between room temperature and 70 ℃.
According to the invention, by setting the arrangement position of the plate thermometer, the actual temperature of the steel strip can be accurately measured, and the furnace temperature setting and the speed setting are adjusted according to the actual temperature of the steel strip, so that the correct execution of a heat treatment process is ensured, and the stable mechanical property of the steel strip is ensured.
The fourth plate thermometer and the fifth plate thermometer are both arranged in an air cooling section of the annealing furnace, and in the air cooling section between the fourth plate thermometer and the fifth plate thermometer, the cooling rate of the stainless steel band is more than 50 ℃/s, so that the phenomenon of intercrystalline sensitization of the stainless steel band can be avoided.
The second plate thermometer and the third plate thermometer are both arranged in the heating section of the annealing furnace, the heating speed of the stainless steel band is maintained at 8-12 ℃/s in the heating section between the second plate thermometer and the third plate thermometer, dynamic recrystallization of all crystal phase tissues is ensured, and the stress reaches a stable value.
Specifically, the heating zone comprises a first heating subarea, a second heating subarea, a third heating subarea, a fourth heating subarea, a fifth heating subarea, a sixth heating subarea, a seventh heating subarea, an eighth heating subarea, a ninth heating subarea and a tenth heating subarea, wherein each heating subarea is provided with a burner, and the burners spray flames to heat the stainless steel strip.
The number of the burners of the first heating subarea is 10-16, the power of the burners is 6500-7000kw, and the temperature of the furnace top is 1200-1280 ℃;
the number of the burners of the second heating subarea is 10-16, the burner power is 6300-6800kw, and the furnace top temperature is 1200-1280 ℃;
the number of the burners of the third heating subarea is 10-16, the power of the burners is 5400-6000kw, and the temperature of the furnace top is 1200-1280 ℃;
the number of the burners of the fourth heating subarea is 10-16, the power of the burners is 4800-5300kw, and the temperature of the furnace top is 1200-1280 ℃;
the number of the burners of the fifth heating subarea is 10-16, the burner power is 4000-4300kw, and the furnace top temperature is 1200-1280 ℃;
the number of the burners of the sixth heating subarea is 10-16, the power of the burners is 3500-4000kw, and the temperature of the furnace top is 1200-1280 ℃;
the number of the burners of the seventh heating subarea is 10-16, the power of the burners is 2500-3200kw, and the temperature of the furnace top is 1190-1260 ℃;
the number of the burners of the eighth heating subarea is 10-16, the power of the burners is 1400-2000kw, and the temperature of the furnace top is 1150-1220 ℃;
the number of the burners of the ninth heating subarea is 10-16, the power of the burners is 1200-1800kw, and the temperature of the furnace top is 1150-1220 ℃;
the number of the burners of the tenth heating partition is 10-16, the power of the burners is 1200-1800kw, and the temperature of the furnace top is 1150-1220 ℃.
The invention realizes the heating control of the stainless steel band through 10 heating subareas, and the heating control is accurate. Moreover, the burner power of the 10 heating subareas is set according to the performance of the stainless steel strip, the burner power is gradually reduced, and the mechanical property of the stainless steel strip can be ensured through stable heating.
Preferably, in order to ensure the heating effect, the heating zone is further provided with a combustion fan and an exhaust fan, and the flow rate of the combustion fan is 60000-68000m3The pressure is 12-18KPa, and the air inlet temperature is 20-30 ℃; the flow rate of the exhaust fan is 180000-210000m3The pressure is 2-3KPa, and the air outlet temperature is 150-.
The furnace top of the heating zone is provided with a ceramic fiber module, the porosity of which is 93-98%, and the thickness of which is 200-500 mm. The ceramic fiber is a fibrous light refractory material, and has the advantages of light weight, high temperature resistance, good thermal stability, low thermal conductivity, small specific heat, mechanical shock resistance and the like. According to the invention, the ceramic fiber module is additionally arranged on the top of the furnace, so that the heat insulation effect and the heat resistance effect of a heating area can be improved, the heat insulation performance is good, the production safety is ensured, and the environment of a production workshop is improved.
(2) Cooling the heated stainless steel band to below 180 ℃ through an air cooling section;
the air cooling section is provided with a variable frequency fan, and air is blown to the stainless steel strip through an air pipe, so that the stainless steel strip is cooled to below 180 ℃ from the annealing temperature.
Preferably, step (2) comprises:
cooling the heated stainless steel band through a first air cooling unit;
cooling the stainless steel strip cooled by the first air cooling unit through a second air cooling unit;
cooling the stainless steel strip cooled by the second air cooling unit through a third air cooling unit;
cooling the stainless steel strip cooled by the third air cooling unit through a fourth air cooling unit;
cooling the stainless steel strip cooled by the fourth air cooling unit through a fifth air cooling unit;
cooling the stainless steel strip cooled by the fifth air cooling unit through a sixth air cooling unit;
cooling the stainless steel strip cooled by the sixth air cooling unit through a seventh air cooling unit;
and cooling the stainless steel strip cooled by the seventh air cooling unit by an eighth air cooling unit.
The air cooling section is realized by 8 control units, the length of the air cooling section is 8 x (6m-9m) -48 m-72m, preferably 8 x 7 m-56 m, the flatness of the strip steel is ensured by smooth cooling, carbide precipitation is avoided, and the quality of a stainless steel finished product is ensured.
Wherein the smoke discharge flow of the first air cooling unit and the second air cooling unit is 180000-220000m3The exhaust temperature of the exhaust gas is 180-200 ℃, and the pressure is 140-160 daPa; and the cooling conditions of the first air cooling unit and the second air cooling unit are the same.
The exhaust gas flow rates of the third air cooling unit and the fourth air cooling unit are 250000 and 280000m3The exhaust temperature of the exhaust gas is 110-140 ℃, and the pressure is 140-160 daPa; and the cooling conditions of the third air cooling unit and the fourth air cooling unit are the same.
The smoke discharge flow rates of the fifth air cooling unit and the sixth air cooling unit are 240000-260000m3The exhaust temperature of the exhaust gas is 80-100 ℃, and the pressure is 140-; and the cooling conditions of the fifth air cooling unit and the sixth air cooling unit are the same.
The exhaust gas flow rates of the seventh air cooling unit and the eighth air cooling unit are 230000-250000m3The exhaust temperature of the exhaust gas is 60-85 ℃, and the pressure is 140-160 daPa. And the cooling conditions of the seventh air cooling unit and the eighth air cooling unit are the same.
Preferably, the flow rate of the exhaust smoke, the exhaust temperature of the exhaust smoke and the pressure of the exhaust smoke of the first air cooling unit are the same as those of the exhaust smoke of the second air cooling unit; the third air cooling unit and the fourth air cooling unit have the same smoke discharge flow, the same smoke discharge temperature and the same smoke discharge pressure; the flow rate of the smoke discharged by the fifth air cooling unit and the sixth air cooling unit is the same as the discharge temperature and the pressure of the smoke discharged by the sixth air cooling unit; the flow rate of the exhaust smoke, the discharge temperature of the exhaust smoke and the pressure of the exhaust smoke of the seventh air cooling unit are the same as those of the exhaust smoke of the eighth air cooling unit.
The air cooling section is realized by 8 control units, the cooling conditions of two adjacent air cooling units are innovatively set to be the same, the flatness of the strip steel is ensured by stable cooling, carbide precipitation is avoided, the plasticity of the strip steel is increased, the elongation can reach 60-70%, and the stainless steel finished product is small in surface roughness, bright and straight. Moreover, the cooling of the stainless steel strip can be adjusted according to the heat requirement, so that the pressure of the input end of the fan is adjusted, and the stainless steel strip is prevented from deforming. The set value of the pressure can be automatically corrected according to the temperature of the stainless steel band measured by an infrared pyrometer, and the infrared pyrometer is arranged at the outlet of the air cooling section.
(3) Cooling the stainless steel band after air cooling to below 70 ℃ through a water cooling section;
the length of the water cooling section is 6-7m, the water cooling section comprises a spraying box, the length of the spraying box is 2-3m, cooling water and compressed air are introduced into the spraying box, and the flow rate of the cooling water is 15-25m3/h，The flow rate of the compressed air is 1200-1800Nm3H is used as the reference value. The spraying box cools the stainless steel band to 80 ℃ to realize the second cooling treatment.
(4) Removing water on the surface of the stainless steel strip by the water-cooled stainless steel strip through a wringing roller;
the wringing roller is used for removing water brought by water quenching on the surface of the stainless steel belt. The wringing roller typically includes upper and lower rollers that are each driven by a cylinder and that can be adjusted manually or electrically.
(5) The stainless steel band is dried by using the smoke and the waste heat generated in the heating area, and the smoke after the drying treatment is treated by a smoke waste gas washing tower.
The stainless steel band is dried by using the smoke and waste heat generated in the heating area, so that the environment is protected and the energy is saved.
The stainless steel strip can be dried by a hot air blower with a flow rate of 20000-3The pressure is 800-1200 daPa. The length of the hot air drying section is 6-10m, but is not limited thereto.
The flue gas exhaust gas scrubbing tower includes catch tray, scrubbing tower, fog collector, chemical centrifugal pump and radial fan, and the flue gas is from the catch tray under the radial fan effect upwards through the scrubbing tower perpendicularly to under the chemical centrifugal pump effect, make flue gas and washing liquid form large tracts of land contact, then collect through the fog collector.
(6) The dried stainless steel strip is processed by electrolysis through an electrolytic bath with Na as a medium2SO4The solution is electrolyzed and then first waste gas and first wastewater are discharged, the first waste gas is treated by a first waste gas treatment system, and the first wastewater is treated by a first wastewater treatment system;
the electrolytic tank comprises a first electrolytic tank, and the medium of the first electrolytic tank is Na2SO4Solution, Na2SO4The concentration of the solution is less than 200g/L, the concentration of metal ions is less than 15g/L, the temperature is 75-85 ℃, and the current density is 0-20A/dm2The concentration of hexavalent chromium is less than 5g/L, and the content of suspended matters is less than 4 g/L.
Preferably, Na of the first electrolytic cell2SO4The concentration of the solution is 150-200g/L, the concentration of metal ions is less than 15g/L, the temperature is 75-85 ℃, and the current density is 5-10A/dm2The concentration of hexavalent chromium is 0.5-1.5g/L, and the content of suspended matters is less than 4 g/L.
The scale layer portion of the stainless steel strip is composed of an iron-based oxide and can be effectively removed by an electrolytic process. The acid wash takes place in an aqueous solution of sodium sulfate electrolyte. The process uses a dc power supply. Electrolyte descaling is the result of alternating polarization of the strip anode and cathode by a neutral conductor system. Therefore, the stainless steel strip passes through the first electrolytic bath, and Fe can be removed2O3NiO and Cr2O3Corresponding metal ion (Fe)3+、Cr3+、Ni2+) Hydroxides are formed in the neutral solution by hydrolysis, i.e. dissolved scale, iron ions and a part of the nickel and chromium ions precipitate as hydroxide sludge, with the formation of chromates. After electrolytic pickling, the surface of the strip steel is rinsed and scrubbed in a brushing unit, and scale residues and hydroxide sludge particles are removed.
The first waste gas treatment system comprises a fan, a deep spraying area, a liquid drop separator and a demister, waste gas generated by electrolysis treatment and sodium sulfate regeneration is guided to the deep spraying area through the fan, the first waste gas in the deep spraying area is contacted with a washing solution, liquid drop separation is realized through the liquid drop separator and the demister, and the washing solution in the deep spraying area is desalted water.
The first wastewater treatment system comprises a first wastewater discharge device and a first wastewater recovery device, and is used for discharging and recovering the electrolyzed wastewater.
(7) Carrying out three-stage pickling treatment on the stainless steel strip by a pickling tank, wherein the medium of the pickling tank is HNO3And HF, discharging second waste gas and second wastewater after acid washing treatment, wherein the second waste gas is treated by a second waste gas treatment system, and the second wastewater is treated by a second wastewater treatment system;
the pickling tank comprises a first pickling tank, a second pickling tank and a third pickling tank, wherein,
the medium of the first pickling tank is a mixture of HNO3 and HF, and HNO is injected into the first pickling tank through a feeding mechanism3And HF and discharging part of HNO through a waste discharging mechanism3And HF, so that the medium of the first pickling tank flows in a circulating manner;
HNO of the first pickling tank3The concentration of the metal ions is 80-150g/L, the concentration of HF is 3-40g/L, the concentration of the metal ions is less than 35g/L, and the temperature is 40-65 ℃. Preferably, the HNO in the first pickling tank3The concentration of the metal ion is 100-130g/L, the concentration of HF is 10-40g/L, the concentration of the metal ion is less than 25g/L, and the temperature is 45-60 ℃.
The first pickling tank is used for carrying out first-stage pickling treatment, the iron scale remained after the first-stage pickling treatment consists of complex iron, chromium and nickel oxides, and the invention uses a mixture of nitric acid and hydrofluoric acid to remove the complex oxides and the chromium-free layer.
The medium of the second acid washing tank is HNO3And HF, and injecting HNO into the second acid washing tank through a feeding mechanism3And HF and discharging part of HNO through a waste discharging mechanism3And HF, so as to circulate the medium of the second acid washing tank;
HNO of the second acid wash tank3The concentration of the metal ions is 80-150g/L, the concentration of HF is 3-40g/L, the concentration of the metal ions is less than 35g/L, and the temperature is 40-65 ℃. Preferably, the HNO of the second acid wash tank3The concentration of the metal ion is 100-130g/L, the concentration of HF is 10-40g/L, the concentration of the metal ion is less than 25g/L, and the temperature is 45-60 ℃.
The medium of the third pickling tank is HNO3And HF, and injecting HNO into a third pickling tank through a feeding mechanism3And HF and discharging part of HNO through a waste discharging mechanism3And HF, so that the medium of the third pickling tank flows in a circulating manner;
HNO of the third pickling tank3The concentration of the metal ions is 80-150g/L, the concentration of HF is 3-40g/L, the concentration of the metal ions is less than 35g/L, and the temperature is 40-65 ℃. Preferably, HNO of the third pickling tank3The concentration of (a) is 100-130g/L, the concentration of HF10-40g/L, the concentration of metal ions is less than 25g/L, and the temperature is 45-60 ℃.
Due to the high quality requirement of strip steel pickling, the mixed acid process is carried out in three stages. The last oxide is removed in the last pickling tank. And meanwhile, the surface is leveled, and high-quality acid washing is ensured by the strongly oxidized nitric acid.
The parameter settings of the media of the first electrolytic tank, the first pickling tank, the second pickling tank and the third pickling tank are set according to different section bars, so that the optimal pickling effect is achieved.
Preferably, when the stainless steel strip is 304, the medium of the first electrolytic tank is Na2SO4Solution, Na2SO4The concentration of the solution is less than 200g/L, the concentration of metal ions is less than 15g/L, the temperature is 75-85 ℃, and the current density is 10-20A/dm2The concentration of hexavalent chromium is less than 5g/L, and the content of suspended matters is less than 4 g/L;
HNO in the first pickling tank, the second pickling tank and the third pickling tank3The concentration of the metal ions is 80-150g/L, the concentration of HF is 10-40g/L, the concentration of the metal ions is less than 35g/L, and the temperature is 60-65 ℃.
Preferably, when the stainless steel band is 200, the medium of the first electrolytic tank is Na2SO4Solution, Na2SO4The concentration of the solution is less than 200g/L, the concentration of metal ions is less than 15g/L, the temperature is 75-85 ℃, and the current density is 10-20A/dm2The concentration of hexavalent chromium is less than 5g/L, and the content of suspended matters is less than 4 g/L;
HNO in the first pickling tank, the second pickling tank and the third pickling tank3The concentration of the metal ions is 80-150g/L, the concentration of HF is 3-10g/L, the concentration of the metal ions is less than 35g/L, and the temperature is 45-50 ℃.
The second waste gas treatment system comprises a hydrofluoric acid washing tower and a denitrification device, acid components in the second waste gas are removed through the hydrofluoric acid washing tower until the acid components are reduced to a limit value, and then the nitrogen oxides are reduced through the denitrification device.
The second wastewater treatment system comprises a second wastewater discharge device and a second wastewater recovery device, and is used for discharging and recovering the wastewater after pickling.
The inventor surprisingly found in the innovation that when the waste discharge and the volume of the steel strip in the medium of the pickling tank reach a certain relation value, a balance can be achieved between the consumption of metal ions and the consumption of acid, so that the scale layer and the chromium-free strip can be effectively removed, and the emission of acid can be reduced. Specifically, the second wastewater discharge device controls HNO3The amount of waste of the mixture with HF is V and the volume of the steel strip in the medium of the pickling tank is V1, then
V＝(4ml/m3-6ml/m3)*V1。
When V is less than 4ml/m3When V1 is adopted, the consumption of metal ions is too large, the removal effect of the scale layer and the chromium-free belt is influenced, and the power consumption is also large; when V is more than 6ml/m3V1, the consumption of acid is too large, the emission of acid is increased, and the effects of energy conservation and emission reduction cannot be achieved.
Most preferably, when the amount of scrap discharged from the first pickling tank, the second pickling tank, and the third pickling tank is V, and the volume of the steel strip in the medium in the first pickling tank, the second pickling tank, and the third pickling tank is V1, V is 5ml/m3V1. The real-time volume of the steel belt in the pickling medium can be obtained according to the speed and the thickness of the stainless steel belt, then the waste discharge amount is adjusted in real time, the optimal balance point between the consumption of metal ions and the consumption of acid is achieved, the acid discharge is greatly reduced, the electric energy consumption is reduced, the energy conservation and emission reduction are realized, and the scale layer and the chromium-free belt are effectively removed.
When the thickness of the stainless steel strip is d, the width is a, and the speed is V, V1 is d a V, and the unit is m3/min。
The thickness of the stainless steel belt is preferably 0.3-3mm, and the conveying speed is preferably 100-200 m/min. The conveying speed and the pickling time of the stainless steel strip in the pickling process should be optimally adjusted according to different profiles.
Preferably, when the stainless steel band is 200, the transmission speed is 200m/min, the total length of the first electrolytic tank is 90-100m, the length of the anode segment is 35-38m, the total treatment time is 28-30s, and the anodic treatment time is 9-11 s; the total length of the first pickling tank, the second pickling tank and the third pickling tank is 75-85m, and the pickling time is 22-26 s.
Preferably, when the stainless steel strip is 304, the conveying speed is 200m/min, the total length of the first electrolytic tank is 90-100m, the length of the anode segment is 35-38m, the total treatment time is 28-30s, and the anodizing treatment time is 9-11 s; the total length of the first pickling tank, the second pickling tank and the third pickling tank is 75-85m, and the pickling time is 22-26 s.
Preferably, when the stainless steel strip is 316, the conveying speed is 160m/min, the total length of the first electrolytic tank is 90-100m, the length of the anode segment is 35-38m, the total treatment time is 34-39s, and the anodic treatment time is 11-16 s; the total length of the first pickling tank, the second pickling tank and the third pickling tank is 75-85m, and the pickling time is 28-32 s.
As a preferable embodiment, the waste discharge amount of the first pickling tank is 25-40ml/min, the waste discharge amount of the second pickling tank is 15-30ml/min, and the waste discharge amount of the third pickling tank is 15-30 ml/min.
Adding HNO into the first pickling tank3And HF in an amount of 35-55g/L, and adding HNO to the second acid washing tank3The amount of the mixture of HF and HNO is 35-55g/L, and HNO is added into the third pickling tank3And the amount of the mixture of HF is 30 to 50 g/L.
As a better embodiment, the waste discharge amount of the first pickling tank is 30-35ml/min, the waste discharge amount of the second pickling tank is 20-25ml/min, and the waste discharge amount of the third pickling tank is 20-25 ml/min.
Adding HNO into the first pickling tank3And HF in an amount of 40-45g/L, and adding HNO to the second acid washing tank3The amount of the mixture of HF and HNO is 40-45g/L, and HNO is added into the third pickling tank3And the amount of the mixture of HF is 35 to 40 g/L.
Therefore, the invention can obtain the real-time volume of the steel belt in the pickling medium according to the speed and the thickness of the stainless steel belt, and then adjust the waste discharge in real time, so as to achieve a balance between the consumption of metal ions and the consumption of acid, thereby reducing the acid discharge, reducing the power consumption and realizing the energy conservation and emission reduction. Compared with the prior art, the hair conditionerThe acid discharge amount can be reduced by 10-20%, and the electric energy consumption can be reduced by 5-10%. In addition, the HNO in the first pickling tank, the second pickling tank and the third pickling tank can be treated according to the waste discharge amount3And the addition amount of the mixture of HF and the mixture of HF is adjusted, so that the scaly layer and the chromium-free belt are efficiently removed, and the removal rate of the scaly layer and the chromium-free belt is as high as 99.9%.
Most of the existing pickling processes are simply provided with pickling conditions, stainless steel belts with different speeds or thicknesses are easy to fluctuate the concentration of acid, and cannot reach a balance between the consumption of metal ions and the consumption of acid, so that the acid discharge amount of the pickling process is large.
(8) 4-6 stages of cascade rinsing are carried out on the stainless steel band, and the stainless steel band is dried;
preferably, the stainless steel strip is rinsed through 6 stages of cascade rinsing, comprising in sequence:
rinsing the stainless steel strip through a first spray rinse tank, the first spray rinse tank comprising a single recycle tank;
rinsing the stainless steel strip through a second spray rinse tank, the second spray rinse tank comprising a single recycle tank;
rinsing the stainless steel band by a double-brush machine;
rinsing the stainless steel strip through a third spray rinse tank, the third spray rinse tank comprising a single recycle tank;
rinsing the stainless steel strip through a thermal spray rinsing tank, wherein the thermal spray rinsing tank comprises a single circulating tank, and the temperature of rinsing water is less than 95 ℃;
after 6-stage cascade rinsing, the concentration of total acid is less than 10 mg/L.
After the stainless steel band is subjected to 6-stage cascade rinsing, substances remained after electrolysis and acid pickling can be removed, and a flat and bright stainless steel band product is obtained.
(9) And (4) straightening and flattening the pickled stainless steel band to obtain a finished stainless steel band product.
The stainless steel band finished product prepared by the invention comprises the following components in percentage by weight:
0.01-0.05% of C, 6.0-9.5% of Ni, 16.5-20.0% of Cr, 0.1-3.0% of Mn, 0.01-0.2% of Cu, 0.15-1.0% of Si, 0.01-0.2% of P, 0.01-0.1% of S, 0.02-0.15% of N, and the balance of Fe and inevitable impurities.
Specifically, 0.01-0.05% of C and 0.15-1.0% of Si can promote austenite formation, stabilize austenite structure, improve the strength of the stainless steel, obtain good forming performance and be suitable for a cold rolling process. And by matching with 0.1-3.0% of Mn and 6.0-9.5% of Ni, the austenite can be stabilized, the mechanical property of the stainless steel strip can be improved, the forming property of the stainless steel strip can be improved, and the method is suitable for a cold rolling process and lays a foundation for obtaining a good plate type subsequently. The stainless steel strip contains 16.5-20.0% of Cr, so that the stainless steel strip has good corrosion resistance. The stainless steel strip contains 0.02-0.15% of N, austenite can be stabilized, and meanwhile, the strength and the corrosion resistance of the stainless steel strip are improved. 0.01-0.2% of Cu, and can reduce the stacking fault energy of an austenite phase and improve the plasticity and the forming performance of the stainless steel band.
Preferably, the stainless steel strip finished product prepared by the cold rolling method comprises the following components in percentage by weight:
0.03-0.04% of C, 7.0-9.0% of Ni, 17.5-19.0% of Cr, 0.5-2.0% of Mn, 0.02-0.08% of Cu, 0.40-0.80% of Si, 0.02-0.05% of P, 0.01-0.05% of S, 0.02-0.06% of N, and the balance of Fe and inevitable impurities.
The mechanical properties of the stainless steel band finished product are as follows:
| item | Numerical value |
| Thickness of | 0.3-3mm |
| Yield strength | 300-350MPa |
| Tensile strength | 700-750MPa |
| Elongation of stretching | 60-70％ |
| Hardness of | 170-190HV |
| Surface roughness | 0.15-0.25μm |
The invention is further illustrated by the following specific examples
The preparation method of the stainless steel comprises the following steps:
1. selecting a stainless steel strip blank with a certain thickness;
2. coiling the stainless steel strip blank;
3. the rolled stainless steel band blanks are transmitted to a laser welding machine through an inlet loop, and laser welding is carried out on different rolled stainless steel band blanks;
4. carrying out first cold rolling on the stainless steel strip blank subjected to laser welding through a first cold rolling mill;
5. carrying out second-pass cold rolling on the stainless steel strip blank subjected to the first-pass cold rolling through a second cold rolling mill;
6. carrying out third cold rolling on the stainless steel strip blank subjected to the second cold rolling through a third cold rolling mill;
7. carrying out fourth cold rolling on the stainless steel strip blank subjected to the third cold rolling through a fourth cold rolling mill;
8. carrying out fifth-pass cold rolling on the stainless steel strip blank subjected to the fourth-pass cold rolling through a fifth cold rolling mill;
9. carrying out sixth cold rolling on the stainless steel strip blank subjected to the fifth cold rolling through a sixth cold rolling mill;
10. cleaning the stainless steel strip blank subjected to the sixth cold rolling;
11. conveying the cleaned stainless steel strip blank to the next procedure through an outlet loop, and drying and cleaning to obtain a semi-finished stainless steel strip;
12. and annealing the dried stainless steel strip semi-finished product, wherein the annealing comprises the following steps:
(1) conveying the stainless steel strip to an inlet sealing section of an annealing furnace, and preheating the stainless steel strip in a preheating zone by convection and radiation of flue gas so that the stainless steel strip is heated from 30 ℃ to T1Preheating time is t 1;
(2) conveying the preheated stainless steel strip to a heating area, and heating by flame sprayed from a burner so as to ensure that the stainless steel strip is heated from T1Heating to 1160 ℃, wherein the retention time of the stainless steel belt at the temperature of above 1080 ℃ is t 2; the heating zone comprises a first heating subarea, a second heating subarea, a third heating subarea, a fourth heating subarea, a fifth heating subarea, a sixth heating subarea, a seventh heating subarea, an eighth heating subarea, a ninth heating subarea and a tenth heating subarea; the 10 heating zones are provided with burners, combustion-supporting fans and exhaust fans, wherein the number of the burners is 12, the power of the burners is shown in the following table, and the flow of the combustion-supporting fans is 60000-68000m3The pressure is 12-18KPa, and the air inlet temperature is 20-30 ℃; the flow rate of the exhaust fan is 180000 and 210000m3The pressure is 2-3KPa, and the air outlet temperature is 150-;
(3) conveying the heated stainless steel band to an outlet sealing section;
(4) cooling the heated stainless steel band to T through an air cooling section2The air cooling section comprises a first air cooling unit, a second air cooling unit, a third air cooling unit, a fourth air cooling unit, a fifth air cooling unit, a sixth air cooling unit, a seventh air cooling unit and an eighth air cooling unit;
(5) cooling the stainless steel band after air cooling to T through a water cooling section3；
(6) Removing water on the surface of the stainless steel strip by the water-cooled stainless steel strip through a wringing roller;
(7) and drying the stainless steel band.
13. Electrolyzing and pickling the annealed stainless steel strip semi-finished product, which specifically comprises the following steps:
(1) carrying out electrolytic treatment on the stainless steel strip by a first electrolytic cell;
(2) carrying out acid washing treatment on the stainless steel strip through a first acid washing tank;
(3) carrying out acid washing treatment on the stainless steel strip through a second acid washing tank;
(4) carrying out acid washing treatment on the stainless steel strip through a third acid washing tank;
(5) rinsing the stainless steel band by 6 stages in cascade and drying;
14. and (4) straightening and flattening the pickled stainless steel band semi-finished product to obtain a stainless steel band finished product.
(II) the annealing process parameters are as follows:
(III) the acid washing process parameters are as follows:
and (IV) the properties of the finished stainless steel strip are as follows:
while the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.
Claims (9)
1. An environment-friendly and energy-saving stainless steel strip annealing and pickling method is characterized by comprising the following steps:
(1) conveying the cold-rolled stainless steel strip to a heating section of an annealing furnace, wherein the heating section of the annealing furnace sequentially comprises an inlet sealing section, a preheating zone, a heating zone and an outlet sealing section,
conveying the cold-rolled stainless steel strip to an inlet sealing section of an annealing furnace, and preheating the stainless steel strip in a preheating zone by using convection and radiation of flue gas generated in a heating zone so as to heat the stainless steel strip from 30 ℃ to T1，T1＝250-300℃；
The preheated stainless steel band is conveyed to a heating zone and is heated by flame sprayed from a burner so as to enable the stainless steel band to be heated from T1Heating to 1160 ℃ for at least 15 seconds at a temperature of above 1080 ℃, and then conveying the heated stainless steel belt to an outlet sealing section;
(2) cooling the heated stainless steel band to below 180 ℃ through an air cooling section;
(3) cooling the stainless steel band after air cooling to below 70 ℃ through a water cooling section;
(4) removing water on the surface of the stainless steel strip by the water-cooled stainless steel strip through a wringing roller;
(5) drying the stainless steel band by using flue gas and waste heat generated in a heating zone, and treating the flue gas after drying treatment by using a flue gas and waste gas washing tower;
(6) the dried stainless steel strip is processed by electrolysis through an electrolytic bath with Na as a medium2SO4Solution, discharging first waste after electrolytic treatmentThe system comprises gas and first waste water, wherein the first waste gas is treated by a first waste gas treatment system, and the first waste water is treated by a first waste water treatment system;
(7) carrying out three-stage pickling treatment on the stainless steel strip by a pickling tank, wherein the medium of the pickling tank is HNO3And HF, discharging second waste gas and second wastewater after acid washing treatment, wherein the second waste gas is treated by a second waste gas treatment system, and the second wastewater is treated by a second wastewater treatment system;
(8) 4-6 stages of cascade rinsing are carried out on the stainless steel band, and the stainless steel band is dried;
(9) straightening and flattening the stainless steel band after the pickling to obtain a finished stainless steel band;
the length of the annealing furnace is 240m for 200 and the transmission speed of the stainless steel band is 220m/min for 160 and 220m/min, and the annealing furnace is provided with at least 7 sets of plate thermometers, including a first plate thermometer, a second plate thermometer, a third plate thermometer, a fourth plate thermometer, a fifth plate thermometer, a sixth plate thermometer and a seventh plate thermometer;
the first plate thermometer is arranged at a position 90-100m away from the inlet of the annealing furnace and is used for controlling the temperature at 580-620 ℃;
the second plate thermometer is arranged at a position which is 115-125m away from the inlet of the annealing furnace and is used for controlling the temperature to be 1080 ℃;
the third plate thermometer is arranged at the position of 135-145m away from the inlet of the annealing furnace and is used for controlling the temperature at 1100-1160 ℃;
the fourth plate thermometer is arranged at the position which is 150-155m away from the inlet of the annealing furnace and is used for controlling the temperature at 950-980 ℃;
the fifth plate thermometer is arranged at a position 180-188m away from the inlet of the annealing furnace and is used for controlling the temperature at 400-460 ℃;
the sixth plate thermometer is arranged at a position 200-210m away from the inlet of the annealing furnace and is used for controlling the temperature to be between room temperature and 180 ℃;
the seventh plate thermometer is arranged at a position which is 220m away from the inlet of the annealing furnace and is used for controlling the temperature to be between room temperature and 70 ℃.
2. The method for annealing and pickling an environment-friendly and energy-saving stainless steel strip according to claim 1, wherein the first waste gas treatment system comprises a fan, a deep spraying zone, a liquid drop separator and a demister, waste gases from electrolysis treatment and sodium sulfate regeneration are introduced to the deep spraying zone through the fan, the first waste gas is contacted with a washing solution in the deep spraying zone, and liquid drop separation is realized through the liquid drop separator and the demister, wherein the washing solution in the deep spraying zone is desalted water.
3. The method for annealing and pickling an environmentally friendly and energy saving stainless steel strip according to claim 1, wherein the second exhaust gas treatment system comprises a hydrofluoric acid scrubber and a denitrification device, the hydrofluoric acid scrubber removes acid components in the second exhaust gas until the acid components are reduced to a limit value, and the denitrification device reduces nitrogen oxides.
4. The annealing and pickling method for the environment-friendly and energy-saving stainless steel strip as claimed in claim 1, wherein the flue gas exhaust gas washing tower comprises a collecting tray, a washing tower, a mist collector, a chemical centrifugal pump and a radial fan, flue gas vertically passes through the washing tower from the collecting tray upwards under the action of the radial fan, and is in large-area contact with washing liquid under the action of the chemical centrifugal pump and then is collected through the mist collector.
5. The method for annealing and pickling an environmentally friendly and energy saving stainless steel strip according to claim 1, wherein the first wastewater treatment system comprises a first wastewater discharge device and a first wastewater recovery device, and the second wastewater treatment system comprises a second wastewater discharge device and a second wastewater recovery device.
6. The method for annealing and pickling an environmental friendly and energy saving stainless steel strip according to claim 5, wherein the second wastewater discharge device controls HNO3The amount of waste of the mixture with HF is V and the volume of the steel strip in the medium of the pickling tank is V1, then
V＝(4ml/m3-6ml/m3)*V1。
7. The method for annealing and pickling an environmentally friendly and energy saving stainless steel strip as recited in claim 1 wherein said electrolytic bath comprises a first electrolytic bath, and said pickling bath comprises a first pickling bath, a second pickling bath, and a third pickling bath, wherein,
na of the first electrolytic tank2SO4The concentration of the solution is less than 200g/L, the concentration of metal ions is less than 15g/L, the temperature is 75-85 ℃, and the current density is 0-20A/dm2The concentration of hexavalent chromium is less than 5g/L, and the content of suspended matters is less than 4 g/L;
HNO of the first pickling tank3The concentration of the metal ions is 80-150g/L, the concentration of HF is 3-40g/L, the concentration of the metal ions is less than 35g/L, and the temperature is 40-65 ℃;
HNO of the second acid wash tank3The concentration of the metal ions is 80-150g/L, the concentration of HF is 3-40g/L, the concentration of the metal ions is less than 35g/L, and the temperature is 40-65 ℃;
HNO of the third pickling tank3The concentration of the metal ions is 80-150g/L, the concentration of HF is 3-40g/L, the concentration of the metal ions is less than 35g/L, and the temperature is 40-65 ℃.
8. The annealing and pickling method for stainless steel strip with environmental protection and energy saving as claimed in claim 1, wherein the thickness of the stainless steel strip is 0.3-3 mm.
9. The annealing and pickling method for stainless steel strip with environmental protection and energy saving as claimed in claim 1, wherein the fourth plate temperature meter and the fifth plate temperature meter are both arranged in the air cooling section of the annealing furnace, the air cooling section between the fourth plate temperature meter and the fifth plate temperature meter has a cooling rate of the stainless steel strip of more than 50 ℃/s;
the second plate temperature meter and the third plate temperature meter are both arranged in the heating section of the annealing furnace, the heating section between the second plate temperature meter and the third plate temperature meter, and the heating rate of the stainless steel band is maintained at 8-12 ℃/s.
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|---|---|---|---|---|
| JPS59157288A (en) * | 1983-02-25 | 1984-09-06 | Nippon Stainless Steel Co Ltd | Method for pickling stainless steel strip |
| CN103191928B (en) * | 2013-04-10 | 2015-06-24 | 张家港浦项不锈钢有限公司 | 304 stainless steel strip and production method thereof |
| CN104032318B (en) * | 2014-06-16 | 2016-06-01 | 中冶南方工程技术有限公司 | A kind of 409L cold rolled strip annealing and pickling production method |
| CN106244783B (en) * | 2016-08-11 | 2018-10-30 | 武汉乾冶工程技术有限公司 | A kind of stainless steel strip continuous producing method |
| CN107130090A (en) * | 2017-04-28 | 2017-09-05 | 武汉市杰精精密电子有限公司 | The n 2 annealing equipment and method for annealing of a kind of stainless steel battery case |
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2018
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Denomination of invention: An environment-friendly and energy-saving annealing and pickling method for stainless steel strip Effective date of registration: 20220328 Granted publication date: 20210212 Pledgee: Agricultural Bank of China Limited Foshan Gaoming sub branch Pledgor: FOSHAN CHENGDE NEW MATERIAL Co.,Ltd. Registration number: Y2022980003388 |
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