CN115074741B - A process for removing scale and rust by pickling - Google Patents

Abstract

The invention discloses a process for removing scale by pickling, which comprises the following steps: S1, adding a secondary pickling tank behind the 4# rinse tank and connecting the exhaust system; S2, adding a second rinse behind the secondary pickling tank tank; S3, set the air blowing air pipe in the secondary rinse tank; S4, set the control valve Vg and connect the acid liquid supply pipeline of the secondary pickling tank; S5, set the control valve V1 control valve, V2 control valve, V3 control valve and V4 control valve; S6, setting the secondary pickling tank to return the acid pipe; S7, setting the water supply pipeline for the secondary rinsing; S8, connecting the pipeline for the secondary rinsing to the flushing water tank, a pickling of the present invention In the descaling process, a secondary pickling tank and a secondary rinsing tank are added behind the original rinsing tank, which can completely eliminate the defects of parking scale, and the process of descaling is completely included in the normal startup and shutdown process. Additional human operation process and time are required to stop the equipment and improve the production efficiency of the equipment.

Description

A process for removing scale by pickling

technical field

The invention relates to the technical field of pickling descaling technology, in particular to a pickling descaling process.

Background technique

Pickling (see Figure 1 of the specification for details) is the previous process of cold-rolled strip steel. It is to remove the oxide scale by passing the uncoiled hot-rolled strip steel through 85-88°C acid in 3 pickling tanks, and then pass through 4 pickling tanks. A rinsing tank with 70°C rinsing water to remove residual acid on the surface. 4 rinsing tanks with a total length of 20m, each tank stores 3-4m ^{3 of} water, and 4 circulation pumps PS1 circulation pump, PS2 circulation pump, PS3 circulation pump and PS4 circulation pump draw the rinsing water from the bottom of the tank and spray it to the belt Steel upper and lower surfaces. 2 to 3 spray pipes are arranged above and below each tank, and 15 to 20 water nozzles are fixed on the spray pipes. Fresh water is added from the 4# rinsing tank, and it overflows step by step against the forward direction of the strip to the 1# rinsing tank, and then to the rinse water tank. The free acid concentration of the rinsing water in the 1# rinsing tank is 12g/L, 1#→2#→ The concentration of free acid in the rinsing water of 3#→4# rinse tank decreases step by step, and the cleanliness increases step by step.

When the strip steel stops for some reason, the strip steel staying in the rinsing section will produce dark brown or black water rust under the fumigation of water vapor. ), before the strip steel restarts operation, the strip steel in the rinsing section is reversed to the 3# pickling tank, the scale is removed by hydrochloric acid, and then the strip steel operation is started immediately. When the scale retreats into the 3# pickling tank completely, along with the strip steel moving backwards as a whole, the strip steel in the 1# pickling tank will also carry the acid solution and exit backwards. For preventing from polluting the environment and equipment, prior art In front of the 1# pickling tank, set up a 10m-long strip steel reverse flushing tank, equipped with a spray pipe and a squeeze roller, and remove the acid liquid brought out of the strip steel from the 1# acid tank by spraying and squeezing.

In order to prevent the steel strip from running off, the system sets the jogging speed of the strip steel to move backwards very low, only 10m/min. In addition to the length of the 4# overflow tank, it takes 2 half the time. Calculated according to the average number of shutdowns, the cumulative time for descaling in a year is 65 hours. For a unit with an annual output of 2 million tons, the conservative hourly output is 260 tons, so the annual production will be reduced by 16,900 tons, which is a quantity that cannot be ignored. The technical problem to be solved by the invention is: to use a new method to eliminate the water rust defect of parking, and the strip steel does not need to move backward.

Contents of the invention

In order to solve the technical problems existing in the background technology, the present invention proposes a process for removing scale by pickling, which uses a new method to eliminate the defects of parking scale and does not require the strip steel to move backwards. The problem.

For this reason, the invention provides a kind of pickling descaling process, comprises the following steps:

S1. Add a secondary pickling tank behind the 4# rinsing tank and connect the exhaust system, and set four spray beams in the secondary pickling tank, 2 above the strip steel, 2 below the strip steel, each spray There are 8 first nozzles on the beam, the source of the acid solution is 3# acid tank, the injection power comes from the PS3 circulation pump, the function of the 9# squeeze roller is to reduce the strip steel carrying water into the secondary pickling tank, and the 10# squeeze roller The function is to reduce the acid from the strip to the secondary rinse tank;

S2. Add a secondary rinsing tank behind the secondary pickling tank: the secondary rinsing tank is equipped with 11# squeezing rollers, 12# squeezing rollers, 13# squeezing rollers and 14# squeezing rollers, which function to reduce The strip carries water in the forward direction to improve the rinsing effect. The PP pipe is connected with the exhaust system to discharge the hot and humid gas. It also includes 24 injection pipes, 12 above the strip and 12 below the strip. The rinsing water comes from the original rinsing The rinsing water in the tank is sprayed from the PS1 circulation pump, PS2 circulation pump, PS3 circulation pump and PS4 circulation pump of the primary rinsing tank. Capacity ≥ 250m ³ /h, to ensure no accumulation of rinsing water in the secondary rinsing tank;

S3. Set air blowing air pipes in the secondary rinsing tank: 8 air pipes in total, 4 above the strip steel and 4 below the strip steel, respectively arranged behind the R1 line, R2 line, R3 line and R4 line, Before the strip steel stops, it is rinsed once and squeezed by 9# and 10# squeeze rollers. After the strip steel stops running, air purge is put in to ensure that the surface of the strip steel in the second rinsing tank is dry;

S4. Set the control valve Vg and connect the acid liquid supply pipeline of the secondary pickling tank: one end of the pipeline is connected to the acid liquid inlet of the 3# acid tank, and the other end is connected to the secondary pickling tank through the 1# line, and two groups are connected in parallel Acid spray beam, with Vg connected in series in the middle;

S5. Set control valves V1 control valve, V2 control valve, V3 control valve and V4 control valve: in a spray and rinse circuit, the outlet of the circulating pump is connected in series with control valves V1 control valve, V2 control valve, V3 control valve and V4 The function of the control valve is to block the first rinse when performing the second rinse, and supply all the rinse water to the second rinse;

S6. Set the return acid pipe of the secondary pickling tank: one end of the pipeline is connected to the return port of the secondary pickling tank, and the other end is connected to the 3# acid tank, and the acid solution of the secondary pickling is returned to the 3# acid tank;

S7. Set up the water supply pipeline for secondary rinsing: the outlet of PS1 is connected to R1 for spraying, the middle is connected to V5 in series, the outlet of PS2 is connected to R2 for spraying, the middle is connected to V6 in series, the outlet of PS3 is connected to R3 for spraying, the middle is connected to V7 in series, and the outlet of PS4 is connected to R4 Spray, V8 connected in series in the middle;

S8. The pipeline connecting the secondary rinsing to the flushing water tank: connect the return port of the secondary rinsing to the flushing water tank through the 3# line, and guide the rinsing water after the secondary rinsing into the flushing water tank.

Preferably, in the above S1 step: the material of the first nozzle is fiber reinforced composite plastic, the total injection velocity of the first nozzle is 50m ³ /h, and the injection pressure is 10Kpa.

Preferably, in the above S2 step: each of the injection pipes is provided with 8 second nozzles, the material of the second nozzles is fiber reinforced composite plastic, and the injection pipes are divided into 4 groups, with 3 upper and lower nozzles as a group. group, the injection flow rate of the injection pipes in each group is 60m ³ /h, and the injection pressure is 15Kpa.

Preferably, in the above S3 step: each of the air blowing air pipes is provided with 8 air nozzles, the blowing pressure of the air nozzles is 0.4Mpa, and the air blowing air pipes are positioned along the width of the strip steel. The direction is inclined to both sides at an angle of 30°, among which 4 said air nozzles are inclined to the left, and the other 4 said air nozzles are inclined to the right; the residual water on the surface of the strip is blown to the edge of the strip and falls into the secondary rinse In the groove, in the strip length direction, the tuyere is inclined at an angle of 45° against the advancing direction of the strip.

Preferably, in the above S4 step: after the secondary spraying and rinsing, the V1 control valve, the V2 control valve, the V3 control valve and the V4 control valve are opened, and the state of the primary rinsing and normal rinsing is restored, and the V1 control valve is implemented during the secondary rinsing. , V2 control valve, V3 control valve and V4 control valve are closed.

Preferably, the inner width of the secondary pickling tank is 2.4m, the length is 8m, and the height is 1.85m, and the inner width of the secondary pickling tank is 2.4m, the height is 1.85m, and the length is 2m.

Preferably, the function of the secondary pickling tank is to spray acid solution to the surface of the strip, and remove the parking rust produced by the strip in the rinsing tank when the strip starts to move forward, and the function of the secondary rinsing tank is to spray the acid solution on the strip surface. Spray rinsing water on the surface to remove the residual acid solution on the strip surface after the secondary pickling, and the function of the control valve Vg is to control the acid supply from the acid solution in the 3# acid tank to the secondary pickling tank.

The invention proposed by the present invention proposes a pickling descaling process, by arranging a spray rinsing when the strip steel is regressing in front of the 1# pickling tank, and adding a secondary pickling tank and A secondary rinsing tank, with a blow-drying air duct in the secondary rinsing tank, to ensure that the strip steel in the secondary rinsing tank does not produce scale during parking, so that the defects of parking scale can be completely eliminated, and the process of removing scale is completely included in the During the normal start and stop process, no additional human operation process and time are required to stop the equipment, improve the production efficiency of the equipment, and generate higher economic benefits.

Description of drawings

Fig. 1 is the flow chart of pickling of the present invention;

Fig. 2 is the flow chart of the present invention's regressive steel strip derusting;

Fig. 3 is the sectional view of secondary pickling tank of the present invention;

Fig. 4 is the sectional view of secondary rinse tank of the present invention;

Fig. 5 is a sectional view of the air blowing duct of the present invention;

Fig. 6 is a flowchart of the present invention.

Detailed ways

Below, the technical solution of the present invention will be described in detail through specific examples.

With reference to Fig. 1-6, the present invention proposes a kind of pickling descaling process, comprises the following steps:

S1. Add a secondary pickling tank behind the 4# rinsing tank and connect the exhaust system, and set four spray beams in the secondary pickling tank, 2 above the strip steel, 2 below the strip steel, each spray There are 8 first nozzles on the beam, the source of the acid solution is 3# acid tank, the injection power comes from the PS3 circulation pump, the function of the 9# squeeze roller is to reduce the strip steel carrying water into the secondary pickling tank, and the 10# squeeze roller The function is to reduce the acid from the strip to the secondary rinse tank;

S2. Add a secondary rinsing tank behind the secondary pickling tank: the secondary rinsing tank is equipped with 11# squeezing rollers, 12# squeezing rollers, 13# squeezing rollers and 14# squeezing rollers, which function to reduce The strip carries water in the forward direction to improve the rinsing effect. The PP pipe is connected with the exhaust system to discharge the hot and humid gas. It also includes 24 injection pipes, 12 above the strip and 12 below the strip. The rinsing water comes from the original rinsing The rinsing water in the tank is sprayed from the PS1 circulation pump, PS2 circulation pump, PS3 circulation pump and PS4 circulation pump of the primary rinsing tank. Capacity ≥ 250m ³ /h, to ensure no accumulation of rinsing water in the secondary rinsing tank;

S3. Set air blowing air pipes in the secondary rinsing tank: 8 air pipes in total, 4 above the strip steel and 4 below the strip steel, respectively arranged behind the R1 line, R2 line, R3 line and R4 line, Before the strip steel stops, it is rinsed once and squeezed by 9# and 10# squeeze rollers. After the strip steel stops running, air purge is put in to ensure that the surface of the strip steel in the second rinsing tank is dry;

S4. Set the control valve Vg and connect the acid liquid supply pipeline of the secondary pickling tank: one end of the pipeline is connected to the acid liquid inlet of the 3# acid tank, and the other end is connected to the secondary pickling tank through the 1# line, and two groups are connected in parallel Acid spray beam, with Vg connected in series in the middle;

S5. Set control valves V1 control valve, V2 control valve, V3 control valve and V4 control valve: in a spray and rinse circuit, the outlet of the circulating pump is connected in series with control valves V1 control valve, V2 control valve, V3 control valve and V4 The function of the control valve is to block the first rinse when performing the second rinse, and supply all the rinse water to the second rinse;

S6. Set the return acid pipe of the secondary pickling tank: one end of the pipeline is connected to the return port of the secondary pickling tank, and the other end is connected to the 3# acid tank, and the acid solution of the secondary pickling is returned to the 3# acid tank;

S7. Set up the water supply pipeline for secondary rinsing: the outlet of PS1 is connected to R1 for spraying, the middle is connected to V5 in series, the outlet of PS2 is connected to R2 for spraying, the middle is connected to V6 in series, the outlet of PS3 is connected to R3 for spraying, the middle is connected to V7 in series, and the outlet of PS4 is connected to R4 Spray, V8 connected in series in the middle;

S8. The pipeline connecting the secondary rinsing to the flushing water tank: connect the return port of the secondary rinsing to the flushing water tank through the 3# line, and guide the rinsing water after the secondary rinsing into the flushing water tank.

In use, in step S1: the material of the first nozzle is fiber-reinforced composite plastic, the total injection velocity of the first nozzle is 50m ³ /h, and the injection pressure is 10Kpa.

During use, in the S2 step: each injection pipe is provided with 8 second nozzles, and the material of the second nozzles is fiber reinforced composite plastics, and the injection pipes are divided into 4 groups, each of which is 3 up and down is a group, and each group of injection pipes The injection flow rate is 60m ³ /h, and the injection pressure is 15Kpa.

When in use, in step S3: each air blowing duct is provided with 8 air nozzles, the blowing pressure of the air nozzles is 0.4Mpa, and the air nozzles are inclined 30° to both sides of the air blowing duct along the strip width direction. 4 air nozzles are inclined to the left, and the other 4 air nozzles are inclined to the right; the residual water on the surface of the strip is blown to the edge of the strip and falls into the secondary rinse tank. In the direction of the length of the strip, the air nozzles It is inclined at an angle of 45° against the forward direction of the strip.

When in use, in step S4: after the secondary spraying and rinsing, the V1 control valve, V2 control valve, V3 control valve and V4 control valve are opened, returning to the primary rinsing and normal rinsing state, and the V1 control valve, V1 control valve, The V2 control valve, V3 control valve and V4 control valve are closed.

When in use, the inner width of the secondary pickling tank is 2.4m, the length is 8m, and the height is 1.85m, and the inner width of the secondary pickling tank is 2.4m, the height is 1.85m, and the length is 2m.

When in use, the role of the secondary pickling tank is to spray acid solution on the surface of the strip to remove the parking scale generated by the strip in the rinsing tank when the strip starts to move forward, and the role of the secondary rinsing tank is to spray rinsing water on the surface of the strip To remove the residual acid solution on the strip surface after the secondary pickling, the function of the control valve Vg is to control the acid supply from the acid solution in the 3# acid tank to the secondary pickling tank.

When this embodiment is specifically used, it is divided into a normal operation process (see accompanying drawing 6 of the description for details), a parking process (see accompanying drawing 1 of the description for details) and a strip steel operation start-up process in the process section (see accompanying drawing 6 of the description for details);

1. Normal operation process (see attached drawing 6 of the manual for details)

1. The acid liquid circulation pump works, the 1# pickling tank, the 2# pickling tank, the 3# pickling tank and the acid circulation tank (1#～3# acid tank) circulate between the acid liquid one-time pickling, and the strip steel Run, pickling through the acid solution in the acid tank.

2. Vg is off, the secondary pickling does not work, and there is no acid spray.

3.4# squeeze roll, 5# squeeze roll, 6# squeeze roll, 7# squeeze roll, 8# squeeze roll, 9# squeeze roll and 10# squeeze roll clamp the strip.

4. The V1 control valve, V2 control valve, V3 control valve and V4 control valve are opened, the PS1 circulation pump, PS2 circulation pump, PS3 circulation pump and PS4 circulation pump work, and the strip is sprayed and rinsed in the primary rinse tank.

5. After the steel strip passes through the 9# and 10# squeezing rollers, the surface moisture is basically squeezed dry.

6. V5 control valve, V6 control valve, V7 control valve and V8 control valve are closed, 11# squeeze roller, 12# squeeze roller, 13# squeeze roller and 14# squeeze roller are in loose state, two There is no spray rinse in the secondary rinse tank.

2. Parking process (see Figure 1 in the manual for details)

1. The strip steel stops → the acid circulation PS1 circulation pump, PS2 circulation pump and PS3 circulation pump stop;

2. PS1 circulation pump, PS2 circulation pump, PS3 circulation pump and PS4 circulation pump stop → the upper rollers of all squeeze rollers are lifted;

3. V1 control valve, V2 control valve, V3 control valve and V4 control valve are closed; V5 control valve, V6 control valve, V7 control valve and V8 control valve are opened to prepare for the secondary rinse;

4. A1 compressed air pipe, A2 compressed air pipe, A3 compressed air pipe and A4 compressed air pipe are opened, and the upper and lower surfaces of the strip are blown for 10 seconds to ensure that the surface of the strip stays in the secondary rinsing tank and is dry;

After 5.5 minutes, the steel strip staying in the primary rinsing tank will produce black water rust under the action of high hot water vapor;

6. The acid liquid in each acid tank is discharged into the circulation tank by its own gravity.

3. The start-up process of strip steel operation in the process section is also called the descaling process (see Figure 6 of the manual for details)

1. PS1 circulation pump, PS2 circulation pump and PS3 circulation pump start → 3 to 5 minutes later, 1# pickling tank, 2# pickling tank and 3# pickling tank are filled with acid solution (with strip steel operating conditions) ;

2. Start the strip steel operation in the process section → the upper rollers of all the squeeze rollers fall down to clamp the strip steel;

3. The Vg control valve is opened, and the acid liquid enters the spray pipe in the secondary pickling tank through the 1# line→the acid liquid is sprayed on the upper and lower surfaces of the strip steel→the acid liquid falls into the bottom of the tank→the acid liquid returns to the secondary pickling tank through the 2# line 3# acid tank;

4. PS1 circulation pump, PS2 circulation pump, PS3 circulation pump and PS4 circulation pump start, R1 line, R2 line, R3 line and R4 line pass water, in the secondary rinse tank, rinse water is sprayed onto the upper and lower surfaces of the strip;

5. The strip steel runs forward → when the strip steel in the primary rinsing tank passes through the secondary pickling tank, the scale is removed by the sprayed acid solution;

6. The strip continues to move forward → enter the secondary rinse tank, the sprayed rinse water removes the acid solution remaining on the surface after the secondary pickling, the rinse water falls into the bottom of the tank, and returns to the rinse water tank through the 3# line. At this time, no water is sprayed in the primary rinse tank;

7. After the strip advances 25m, Vg is closed, and the secondary pickling stops;

8. The V1 control valve, V2 control valve, V3 control valve and V4 control valve are opened → a rinsing operation, spraying rinsing water to the upper and lower surfaces of the strip.

9. V5 control valve, V6 control valve, V7 control valve and V8 control valve are closed, the secondary rinse is stopped, 10# squeeze roller, 11# squeeze roller, 12# squeeze roller, 13# squeeze roller and 14# The upper roller of the squeeze roller is lifted, and the descaling process is over.

The present invention is characterized in that, by setting a spray rinsing when the steel strip is reversing in front of the 1# pickling tank, a secondary pickling tank and a secondary rinsing tank are added behind the original rinsing tank, and the secondary pickling tank The function of the tank is to spray acid liquid on the surface of the strip, and remove the parking scale generated by the strip steel in the rinsing tank when the strip starts to move forward. For the residual acid on the steel surface, a blow-drying air duct is installed in the secondary rinsing tank to ensure that the strip steel in the secondary rinsing tank does not produce rust during parking, so that the defects of parking rust can be completely eliminated, and the process of removing rust completely includes In the normal start and stop process, no additional human operation process and time are required to stop the equipment, improve the production efficiency of the equipment, and generate higher economic benefits.

The above is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto, any person familiar with the technical field within the technical scope disclosed in the present invention, according to the technical solution of the present invention Any equivalent replacement or change of the inventive concepts thereof shall fall within the protection scope of the present invention.

Claims (6)

1. a process for removing scale by pickling, is characterized in that, comprises the following steps: S1. After uncoiling, the hot-rolled steel strip goes through 1# pickling tank, 2# pickling tank, and 3# pickling tank to remove scale, and then goes through 1# rinsing tank, 2# rinsing tank, 3# rinsing tank, 4# The rinsing tank removes residual acid on the surface, and a secondary pickling tank is added behind the 4# rinsing tank and connected to the exhaust system, and four spray beams are installed in the secondary pickling tank, 2 above the strip steel and below the strip steel 2, each spray beam is equipped with 8 first nozzles, the acid source is 3# acid tank, the injection power is from the circulation pump, and the role of the 9# squeeze roller is to reduce the water carried by the strip steel into the secondary pickling tank , the function of the 10# squeeze roller is to reduce the acid from the strip to the secondary rinse tank; S2. Add a secondary rinsing tank behind the secondary pickling tank: the secondary rinsing tank is equipped with 11# squeezing rollers, 12# squeezing rollers, 13# squeezing rollers and 14# squeezing rollers, which function to reduce The strip carries water in the forward direction to improve the rinsing effect. The PP pipe is connected with the exhaust system to discharge the hot and humid gas. It also includes 24 injection pipes, 12 above the strip and 12 below the strip. The rinsing water comes from the original rinsing The rinsing water in the tank is sprayed from the PS1 circulation pump, PS2 circulation pump, PS3 circulation pump and PS4 circulation pump of the primary rinsing tank. Capacity ≥ 250m ³ /h, to ensure no accumulation of rinsing water in the secondary rinsing tank; S3. Set air blowing air pipes in the secondary rinsing tank: 8 air pipes in total, 4 above the strip steel and 4 below the strip steel, respectively arranged behind the R1 line, R2 line, R3 line and R4 line, Before the strip steel stops, it is rinsed once and squeezed by 9# and 10# squeeze rollers. After the strip steel stops running, air purge is put in to ensure that the surface of the strip steel in the second rinsing tank is dry; S4. Set the control valve Vg and connect the acid liquid supply pipeline of the secondary pickling tank: one end of the pipeline is connected to the acid liquid inlet of the 3# acid tank, and the other end is connected to the secondary pickling tank through the 1# line, and two groups are connected in parallel Acid spray beam, with Vg connected in series in the middle; S5. Set control valves V1 control valve, V2 control valve, V3 control valve and V4 control valve: in a spray and rinse circuit, the outlet of the circulating pump is connected in series with control valves V1 control valve, V2 control valve, V3 control valve and V4 The function of the control valve is to block the first rinse when performing the second rinse, and supply all the rinse water to the second rinse; S6. Set the return acid pipe of the secondary pickling tank: one end of the pipeline is connected to the return port of the secondary pickling tank, and the other end is connected to the 3# acid tank, and the acid solution of the secondary pickling is returned to the 3# acid tank; S7. Set up the water supply pipeline for secondary rinsing: the outlet of PS1 is connected to R1 for spraying, the middle is connected to V5 in series, the outlet of PS2 is connected to R2 for spraying, the middle is connected to V6 in series, the outlet of PS3 is connected to R3 for spraying, the middle is connected to V7 in series, and the outlet of PS4 is connected to R4 Spray, V8 connected in series in the middle; S8. The pipeline connecting the secondary rinsing to the flushing water tank: connect the return port of the secondary rinsing to the flushing water tank through the 3# line, and guide the rinsing water after the secondary rinsing into the flushing water tank. 2. a kind of pickling descaling process as claimed in claim 1, is characterized in that, in above-mentioned S1 step: the material of described first nozzle is fiber-reinforced composite plastics, and the total jet velocity of described first nozzle is 50m ³ /h, injection pressure is 10Kpa. 3. a kind of pickling descaling process as claimed in claim 1, is characterized in that, in the above-mentioned S2 step: each described injection pipe is provided with 8 second nozzles, and the material of described second nozzles is fiber Reinforced composite plastics, the injection pipes are divided into 4 groups, each with 3 upper and lower groups. The injection flow rate of the injection pipes in each group is 60m ³ /h, and the injection pressure is 15Kpa. 4. a kind of pickling descaling process as claimed in claim 1, is characterized in that, in above-mentioned S3 step: each described air blowing duct is provided with 8 air nozzles, and the blowing of described air nozzles The pressure is 0.4Mpa, and the air nozzles are inclined at an angle of 30° to both sides along the width direction of the strip in the air blowing duct, wherein 4 of the air nozzles are inclined to the left, and the other 4 of the air nozzles are inclined to the right Inclined: the residual water on the surface of the strip is blown to the edge of the strip and falls into the secondary rinsing tank. In the direction of the length of the strip, the air nozzle is inclined at an angle of 45° against the forward direction of the strip. 5. A kind of pickling descaling process as claimed in claim 1, characterized in that, in the above step S4: the V1 control valve, the V2 control valve, the V3 control valve and the V4 control valve are opened after the secondary spraying and rinsing finishes , return to the first rinse, the normal rinse state, and the V1 control valve, V2 control valve, V3 control valve and V4 control valve are closed during the second rinse. 6. A kind of pickling descaling process as claimed in claim 1, characterized in that, the secondary pickling tank is used to spray acid solution to the surface of the strip, and remove the strip in the rinsing tank when the strip starts to move forward. For the parking water rust produced by steel, the function of the secondary rinsing tank is to spray rinsing water to the surface of the strip steel to remove the residual acid solution on the surface of the strip steel after the secondary pickling, and the function of the control valve Vg is to control the 3# acid tank Acid supply from medium acid solution to secondary pickling tank.

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