CN104525885B - A kind of strong cold water spray system of cast steel and strong refrigerating technology - Google Patents

Abstract

The invention provides a slab forced cooling spray system, which includes a water supply pressurization system (1), which is arranged near the continuous casting machine equipment, and is used to pressurize the low-pressure water into high-pressure water; the water volume adjustment system (2) , to calculate the amount of water needed to cool the slab to the target temperature, and output the required water spray; the pressure relief protection system (3), when the pressure at the pump port of the booster pump exceeds a certain set value, it will drain the water and reduce the pressure The spraying system (4) includes evenly arranged high-pressure nozzles (41), which fully atomize and spray the high-pressure cooling water to the surface of the slab; the slab temperature control system (5) uses a computer control model to calculate the The temperature field of the billet. The casting slab forced cooling system described in the present invention is simple, and the forced cooling process method has strong operability and is easy to implement. At the same time, the process method can well solve the external corner cracks of the slab, ensure the metal shrinkage rate of the slab, and reduce the workload of the slab repair and grinding, thereby producing good economic benefits.

Description

A cast steel strong cooling spray system and strong cooling process method

technical field

The invention relates to a slab forced cooling spray system used in the field of continuous steel casting and rolling in the metallurgical industry and a forced cooling process corresponding to the forced cooling spray system.

Background technique

In the metallurgical industry, a large proportion of continuous steel casting has been used to form molten steel, that is, molten steel is continuously cooled through a crystallizer to form a billet with a certain cross-sectional size. Specifically, when producing slabs, liquid molten steel is continuously poured into the mold from the upper part of the mold, and after being cooled and solidified by the mold, a slab shell with liquid steel inside is formed at the lower part of the inner cavity of the mold. Under the dragging action of the billet straightening machine installed under the mold, the billet is continuously output along the mold from top to bottom.

The existing advanced production technology of continuous steel casting is to install one or several rolling mills near the billet straightening machine to change the internal quality of the billet by changing the cross section of the billet. The specific realization process is: the billet passes through the crystallizer After cooling with the secondary cooling zone, a certain thickness or completely solidified high-temperature slab is formed. After the high-temperature slab is rolled by a rolling mill, the thickness is reduced to a certain extent and the quality problem of the center of the slab is solved.

At present, although the internal quality of the cast slab is good after rolling in the rolling mill, and the performance of various internal indicators is higher than that of the cast slab without high-temperature rolling, but the corner cracks appear on the cast slab after rolling, if it is to be used in the next process , the corner must be ground to remove a large number of corner crack areas, which directly leads to a reduction in metal yield and production efficiency, as well as an increase in operating costs.

The reason for cracks at the corners of the slab is that after the slab is cooled by the general and specific cooling method of the mold and the secondary cooling zone, the temperature on the cross-section has a center temperature greater than the edge temperature, and an edge temperature greater than the corner temperature. internal temperature. The casting slab is near the location of the rolling mill. In most cases, the temperature at the corner may be between 700 and 900 degrees. In this temperature range, the slab is overcooled in the secondary cooling zone and the surface is reheated. Circulation increases the amount of ALN precipitated and causes a decrease in steel shape. That is to say, in this case, it is not suitable to change the shape of the slab.

Contents of the invention

The object of the present invention is to provide a strong cooling spray system before continuous steel casting and rolling and a strong cooling method corresponding to the spray system. Through high-strength water spray cooling, the corners of the slab before entering the rolling mill The temperature is lowered to below 700 degrees (the specific process parameters need to be determined according to the steel type of the cast slab, the cross section of the cast slab, the rolling reduction and other conditions) to solve the problem that the corners before rolling are in the brittle zone.

In order to achieve the above object, the strong cooling spray system of the present invention includes,

The water supply pressurization system, which is installed near the continuous casting machine equipment, is used to pressurize the low-pressure water provided by the workshop to the required water supply pressure value;

The water volume adjustment system is used to calculate the water volume required to cool the slab to the target temperature, and at the same time adjust the final control water volume and output the required water spray through PID;

The pressure relief protection system is used to discharge water until the pump port pressure of the booster pump is lower than a certain set value when the pump port pressure of the booster pump exceeds a certain set value;

The spray system includes high-pressure nozzles arranged uniformly according to the shape of the slab, which fully atomizes and sprays high-pressure cooling water to the surface of the slab to uniformly cool the slab;

The slab temperature control system uses a computer control model to accurately calculate the temperature field of the slab.

Further, the water supply pressurization system includes a manual cut-off valve, a booster pump and a check valve. The cut-off valve is set on the side of the booster pump close to the water supply pipe. Adjust the side where the system is connected.

Further, the water supply pressurization system pressurizes the water supply pressure of 0.4-1.0 MPa in the continuous casting workshop to a final pressure of 1.8-2.5 MPa.

Further, the water volume adjustment system includes a manual cut-off valve, a flow meter, an automatic adjustment valve and a remote pressure gauge, the flow meter and the automatic adjustment valve form a closed-loop control system, and the automatic adjustment valve quickly responds to output the required water volume value.

The pressure relief protection system includes a manual cut-off valve, a remote pressure gauge, and an automatic pressure relief valve; the remote pressure gauge monitors the pressure at the output end of the booster pump.

Further, the plurality of high-pressure nozzles are installed in the heat preservation cover; the heat preservation cover is fixed on the roller table frame by pin wedges.

Further, the flow rate of the high-pressure nozzles of the forced cooling spray system is 6-15ml/min, and there are 4-10 rows of nozzles in total. The nozzles of the first 2-5 rows are flat nozzles, and the nozzles of the last 2-8 rows are shaped as Full cone or oval nozzle.

Further, the slab temperature control system includes a temperature field calculation model computer, which is used to accurately calculate the temperature field of the target slab, and the flowmeter is used to feed back the amount of cooling water actually used to the computer, and the computer calculates the temperature field, and then Correct the entire temperature field according to the control requirements of the process method, and give the required value of water quantity.

The present invention also provides a slab forced cooling process corresponding to the above-mentioned slab forced cooling spray system before the continuous steel casting and rolling process. The specific process is as follows:

Step 1: Calculate the temperature field of the cross-section of the slab to determine the amount of water required for forced cooling;

Step 2: Pressurize the low-pressure water provided by the workshop to the high-pressure water of the required pressure;

Step 3: Control the water volume through the regulating valve and flow meter to output the required water spray volume;

Step 4: Atomize the cooling water and spray it to the slab to cool and purge the slab.

Further, after the low-pressure water provided by the workshop is pressurized, when the pressure at the output end of the booster pump is greater than a certain value, the automatic pressure relief valve is opened and reduced to a set value, and then the automatic pressure relief valve is closed.

The casting slab forced cooling system described in the present invention is simple, and the forced cooling process method has strong operability and is easy to implement. At the same time, the process method can well solve the external corner cracks of the slab, ensure the metal shrinkage rate of the slab, and reduce the workload of the slab repair and grinding, thereby producing good economic benefits.

Description of drawings

Fig. 1 is the schematic diagram of the forced cooling spraying system used in the forced cooling process before the continuous steel casting and rolling of the present invention.

Fig. 2 is an assembly drawing of the thermal insulation cover and the roller table of the forced cooling spray system shown in Fig. 1 .

Fig. 3 is a nozzle layout diagram 1 of the forced cooling spray system shown in Fig. 1 .

Fig. 4 is a schematic diagram of the cross-section A-A of Fig. 1 of the nozzle layout of the forced cooling spray system shown in Fig. 3 .

detailed description

In order to better understand the purpose and structural features of the present invention, the structure and working process of specific embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings and actual working conditions.

Fig. 1 is the schematic diagram of the forced cooling spraying system used in the forced cooling process before the continuous steel casting and rolling of the present invention. As shown in Figure 1, the forced cooling spray system includes a water supply pressurization system 1, a water volume adjustment system 2, a pressure relief protection system 3, a spray system 4 and a billet temperature control system.

The water supply pressurization system 1 is arranged near the continuous casting machine equipment to realize the pressurization of the low-pressure water provided to the workshop to the required water supply pressure value. The water supply pressurization system includes a manual cut-off valve 11, a booster pump 12 and a check valve 13. The cut-off valve 11 is arranged on the side of the booster pump close to the water supply pipe, and the check valve 13 is arranged on the side of the booster pump. The side where the pressure pump is connected to the water volume regulating system. Generally, the water supply pressure of the continuous casting workshop is 0.4-1.0MPa, and the final pressure of the water system required by this process is 1.8-2.5MPa. Pressure value of high pressure water.

The water volume regulating system 2 includes a manual cut-off valve 21 , a flow meter 22 , an automatic regulating valve 23 and a remote pressure gauge 24 . According to the temperature field calculation model, the computer 51 calculates the amount of water required to cool the slab 42 to the target temperature, and sends the required water amount to the closed-loop control system formed by the flow meter 22 and the automatic regulating valve 23 for PID adjustment. The regulating valve 23 responds quickly to output the required water volume value.

The pressure relief protection system includes a manual cut-off valve 31 , a remote pressure gauge 32 and an automatic pressure relief valve 33 . The pressure at the output end of the booster pump 12 is monitored through the remote pressure gauge 32. When the pressure exceeds a certain set value, the automatic pressure relief valve 33 is opened for a few seconds to drain water. When the pressure is less than a certain set value, the automatic pressure relief valve 33 is closed. .

The spraying system includes a high-pressure nozzle 41 , a casting slab 42 and a roller table 43 . As shown in FIG. 2 , the high-pressure nozzle 41 is evenly installed on the spray water pipe fixed in the heat preservation cover 6 , and the heat preservation cover 6 is fixed on the roller table frame 7 in the form of pin shaft wedges. The function of the protective cover is to ensure that the steam evaporated by the cooling water can be effectively collected in the secondary cooling chamber while the surface temperature is uniform after the casting slab is cooled. As shown in Figures 3 and 4, 4 to 10 rows of nozzles are arranged on the insulation cover around the cast slab 42 before casting and rolling. Conical or elliptical nozzles, wherein there are 3-12 nozzles in each row, the working pressure of the high-pressure nozzles 41 is 1.8-2.5MPa, and the flow rate of each high-pressure nozzle 41 is 6-15ml/min. The high-pressure nozzles 41 are evenly arranged according to the cross-section of the slab, and the high-pressure nozzles are arranged in different forms for different shapes of slabs. The high-pressure cooling water is fully atomized under the action of the high-pressure nozzle, sprayed onto the surface of the casting slab 42, and uniformly cools the casting slab. Since the pressure of the water supply is pressurized by the booster system 1, the cooling water is sprayed to the surface of the casting slab 42. The speed on the surface is very fast, which can play the role of blowing away the oxide skin on the surface of the cast slab 42 .

The slab temperature control system 5 includes a temperature field calculation model computer 51 , feedback data from the flowmeter 22 and the slab 42 to be calculated. This system uses a computer control model to accurately calculate the temperature field of the slab. Feedback data from the flowmeter 22, that is, the actual amount of cooling water used, is given to the computer model, and the computer 51 calculates the actual temperature field, and then further corrects the entire temperature field according to the control requirements of the process method of the present invention, and gives the required value of water volume, and in actual production When the data changes, the temperature field model calculates the required value of water quantity in time. At the same time, the system has the function of saving historical data in real time for subsequent improvement and research use.

In the implementation of the present invention, an automatic water volume adjustment system is selected, such as the remote flowmeter shown in Figure 1 and the automatic regulating valve, both of which form a closed-loop control system, which can quickly respond to the needs of the system through PID adjustment. water volume. And it can carry out remote control in real time, provide monitoring and man-machine interface for operation, and save historical data in real time for analysis and research.

The forced cooling process before the rolling of the continuous cast steel described in the present invention is realized by the above-mentioned forced cooling system of the slab. Specifically, the water supply pressurization system 1 is used to pressurize the low-pressure water to the required pressure and then supply it to the subsequent process; The amount of sprayed water is controlled by a regulating valve and a flow meter to output the required amount of sprayed water; the pressure relief protection system is used to release the pressure when the outlet pressure of the booster pump increases to a certain level, In order to protect the booster pump; when the water volume adjustment system is adjusted, the change in the water volume will cause the pressure change at the outlet of the booster pump; the main function of the spray system is to use the nozzle to atomize the cooling water and spray it to the slab. It plays the role of cooling and purging; the main function of the slab temperature control system is to input the temperature field calculation model according to the feedback data on site, calculate the slab temperature field in real time, and output the required spray water volume according to the surface temperature control, And save historical data in real time for analysis and research.

The above-mentioned forced cooling process method has the following beneficial effects: the degree of automation is high, and the temperature field control model can be used to calculate the temperature field of the cross-section of the slab before rolling during the pouring process of the slab, so as to determine the amount of water required for forced cooling. The cooling system automatically adjusts the valve to achieve the purpose of setting a certain amount of water; the whole process of monitoring, operation and debugging provides man-machine interface screens, so as to facilitate maintenance; real-time online modification of process parameters, real-time storage of historical data, so as to ensure the quality of the billet is stable . This process can effectively purge and remove the iron oxide scale on the surface of the slab when the cooling water is sprayed under pressure, so that the surface quality of the slab after rolling is very high. This process effectively improves the plasticity and strength of the edges and corners of the slab, and at the same time improves the internal quality of the slab. This technological method improves the metal shrinkage rate of the billet, and then also improves the production efficiency. Through high-intensity cooling, the edges and corners of the slab shell form low-temperature fine equiaxed grain structure, and the plasticity is improved; through high-intensity cooling, when the slab shrinks, the center is still high-temperature slab or Liquid molten steel, there are some slab defects (center looseness, central shrinkage cavity), the shrinkage of the slab shell compresses the central slab or liquid steel to a certain extent, thereby improving the internal quality of the slab; through high-intensity cooling, in There is a temperature transition zone between the center of the slab and the slab shell, and the temperature range is between 700 and 900 degrees. This temperature transition zone forms a brittle layer, but due to the shrinkage of the slab shell, it has certain plasticity and strength. , bind the brittle layer so that the brittle layer will not appear brittle cracks.

The above is only a specific implementation of the forced cooling process in the continuous casting and rolling process of the present invention. It should be pointed out that for those skilled in the art, the Minor modifications and improvements should also be considered as belonging to the scope of protection of the invention.

Claims (9)

1. A slab forced cooling spray system: it is characterized in that it includes, The water supply pressurization system (1), which is installed near the continuous casting machine equipment, is used to pressurize the low-pressure water provided by the workshop to the required water supply pressure value, and the water supply pressure value is 1.8-2.5MPa; The water volume adjustment system (2) is used to calculate the water volume required to cool the slab to the target temperature, and at the same time adjust the final control water volume and output the required water spray through PID; The pressure relief protection system (3) is used for draining water until the pump port pressure of the booster pump is lower than a certain set value when the pump port pressure of the booster pump exceeds a certain set value; The spray system (4) includes high-pressure nozzles (41) uniformly arranged according to the shape of the slab, which fully atomize and spray the high-pressure cooling water to the surface of the slab to uniformly cool the slab; The slab temperature control system (5) uses a computer control model to accurately calculate the temperature field of the slab. 2. The slab forced cooling spray system according to claim 1, characterized in that the water supply pressurization system (1) includes a manual cut-off valve (11), a booster pump (12) and a check valve (13) , the cut-off valve (11) is arranged on the side of the booster pump close to the water supply pipe, and the check valve (13) is arranged on the side of the booster pump connected to the water volume regulation system. 3. The slab forced cooling spray system according to claim 1, characterized in that, the water volume regulating system includes a manual cut-off valve (21), a flow meter (22), an automatic regulating valve (23) and a remote The pressure gauge (24), the flow meter (22) and the automatic regulating valve (23) form a closed-loop control system, and the automatic regulating valve 23 responds quickly to output the required water value. 4. The slab forced cooling spray system according to claim 1, characterized in that, the pressure relief protection system (3) includes a manual cut-off valve (31), a remote pressure gauge (32), an automatic pressure relief pressure valve (33); the remote pressure gauge monitors the pressure at the outlet of the booster pump (12). 5. The cast slab forced cooling spray system according to claim 1, characterized in that, the high-pressure nozzle (41) is installed in the heat preservation cover; the heat preservation cover is fixed to the roller table frame by pin wedges superior. 6. The cast slab forced cooling spray system according to claim 5, characterized in that the flow rate of the high pressure nozzles (41) of the forced cooling spray system is 6 to 15 ml/min, and there are 4 to 10 rows of nozzles in total , The shape of the nozzles in the first 2 to 5 rows is flat nozzles, and the shape of the nozzles in the last 2 to 8 rows is full cone or oval nozzles. 7. The slab forced cooling spray system as claimed in claim 3, characterized in that, the slab temperature control system (5) includes a temperature field calculation model computer (51) to accurately calculate the temperature of the target slab field, the flow meter (22) is used to feed back the actual amount of cooling water used to the computer (51), the computer calculates the temperature field, and then corrects the entire temperature field according to the control requirements of the process method to give the required value of water quantity. 8. A slab forced cooling process method before the continuous steel casting and rolling process, which corresponds to the slab forced cooling spray system as claimed in claim 1, wherein: Step 1: Calculate the temperature field of the cross-section of the slab to determine the amount of water required for forced cooling; Step 2: pressurize the low-pressure water provided by the workshop to the high-pressure water of the required pressure, and the pressure value of the high-pressure water is 1.8-2.5MPa; Step 3: Control the water volume through the regulating valve and flow meter to output the required water spray volume; Step 4: Atomize the cooling water and spray it to the slab to cool and purge the slab. 9. The slab forced cooling process method as claimed in claim 8, wherein, after the water supply pressurization system (1) pressurizes the low-pressure water provided by the workshop, when the pressure at the output end of the booster pump is greater than a set value , reduce the opening of the automatic pressure relief valve (33) to the set value, and then close the automatic pressure relief valve (33).