JP2593072B2 - Roll temperature control method in continuous casting machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Object of the Invention> The present invention relates to a method for cooling a roll in a continuous casting machine.
Specifically, prior to casting, the cooling water is heated by steam injection or the like, and the roll is heated to a temperature equal to or higher than the transition temperature of the base material by the circulation of the hot water, and then casting is started. The present invention relates to a method for adjusting the temperature by mixing a part, but not all, of the warmed return water with cold ring water and returning it to a roll as cooling water to prevent overcooling of the roll and save energy.

2. Description of the Related Art As shown in FIG. 2, a system diagram of a cooling water for a continuous casting roll, which has been conventionally implemented, is such that the ring water whose temperature has risen by cooling the lower roll 1 is returned by a return water pump 19 through a tank 2. The collected water is collected in the water collecting tank 13, returned to the water pumping station, cooled to a predetermined temperature by the cooling tower 17 or the like, and then supplied again as cooling water for the roll 1 by the water supply pump 18. The cooling water supplied to the upper roll 1 is processed by a route returning to the water collecting tank 13. In this case, the water may be directly collected in the water collecting tank 13 without using the return water pump 18.

The conventional cooling method as described above has the following problems. (1) When the continuous casting machine is started after being stopped for a long time or when the roll temperature is extremely low in winter, that is, when the casting is started from a state at or below the transition temperature, the impact value of the roll base material is extremely high. , Which is a major cause of roll breakage.

(2) The ring water whose temperature has risen after passing through the rolls is cooled to a predetermined temperature (15 to 30) by the cooling tower of the ring water pumping station in preparation for the next supply.
℃).

(3) Since the supply of cooling water for the rolls was performed in one system, a pump with a very large capacity was required to supply the cooling water to all the rolls. , Piping resistance was large.

Problems to be Solved by the Invention The present invention aims to solve these problems, and specifically, by circulating hot water through the rolls before starting the casting of the continuous casting machine, to prevent the rolls from being supercooled. Therefore, it is an object of the present invention to provide a roll temperature control method capable of preventing breakage of a roll base material and saving energy.

<Structure of the Invention> Means for Solving the Problems and Their Actions That is, in the method of the present invention, when the roll is cooled while circulating the cooling water in the roll of the continuous casting machine, the steam in the cooling water is blown. The temperature is raised to hot water, and by circulating this hot water, the roll is heated to the transition temperature of the base material or higher, and then casting is started.During subsequent casting, the roll is cooled and heated. A part of the returned water is mixed with cold ring water to adjust the temperature within a range of 20 to 100 ° C., and this is returned to the roll as cooling water.

Hereinafter, the configuration and operation of the present invention will be described with reference to the drawings.

FIG. 1 is a system diagram of roll hot water cooling according to the present invention, and FIG. 2 is a system diagram of roll cooling by conventional cold ring water.

First, one feature of the method of the present invention is that the roll is heated and heated in advance when the temperature of the roll is extremely low at the start of casting, thereby preventing a roll breakage accident due to a drop in impact value.

The requirements for achieving the object of the present invention are as follows.

(1) Hot water (20 to 100 ° C.) is used for cooling the roll of the continuous casting machine.

(2) The circulation of hot water is performed in a closed circuit, and the temperature is controlled by a control valve using steam and cold water to keep the temperature constant.

(3) The hot water is supplied to the roll before the start of casting, and the roll temperature is changed to a transition temperature (for example, 20 to
(Approximately 40 ° C) or higher to improve the impact value.

(4) The hot water is maintained at a predetermined temperature during casting, and is again supplied as it is for cooling the rolls.

FIG. 1 is an example of a system diagram of roll cooling by hot water for carrying out the present invention, and an embodiment of the method of the present invention will be described with reference to the drawings.

The hot water used for roll cooling is supplied to the temperature control tank 2
(Hereinafter referred to as a tank) at a predetermined temperature (20 ° C.) by steam blown from the steam pipe 3 through the silencer 6.
~ 100 ° C). At this time, the flow rate of the steam supply is controlled by the flow rate control valve 4 attached to the steam pipe 3 in accordance with the instruction of the thermometer 5 installed near the water intake 21 so that the feedwater temperature is controlled to be constant.

The return water heated by passing through the inside of the roll 1 is returned to the tank 2 from the upper surface of the tank 2. It enters the receiving tank 10, overflows from the hot water receiving tank 10, and enters the tank 2. At this time, a considerable portion of the return water is short-circuited, overflows from the return water outlet 22, and is returned to the conventional water collection tank 13 via the drainage pump 9 and the flow control valve 12.

Cooling ring water cooled in the ring water system is supplied through a watering header 16 in order to lower the temperature in the tank 2. The supply amount of cold ring water is controlled by a flow control valve 12 that opens and closes according to an instruction of a thermometer 11 in the tank. That is, cold ring water is supplied from the upper part of the temperature adjusting tank 2 in a shower form from the header 16, mixed with the return water heated by the roll 1 and returned through the hot water receiving tank 10 in the tank 2, Maintain the temperature in the tank at 20-100 ° C.

At this time, the return water, which has passed through the roll 1 and has been heated, is not directly put into the tank 2, but is supplied to the tank 2
The reason is that if the whole amount is directly put into the tank 2, the temperature in the tank becomes too high, and the amount of cold water increases to control the temperature to a predetermined temperature, so that it is impractical.

If the roll temperature is lowered due to a long stoppage, or if the roll temperature is lowered during the stoppage in winter or the like, at the start of casting, the cooling water in the tank 2 is circulated through the roll while heating the cooling water in the tank 2 through steam. Roll
After the temperature is raised to 20 to 100 ° C., casting is started. When the temperature of the roll is increased by the slab and the cooling water is heated, the steam is shut off, and if necessary, the cooling water is automatically supplied into the tank 2 to control the temperature in the tank.

Further, the liquid level in the tank 2 is detected by the level meters 14 and 15 and an alarm is issued, and at the same time, the supply valve is controlled by controlling the main valve of the cooling water.

As described above, in the method of the present invention, heat is directly exchanged in the tank with steam and cold water, but as a method of heat exchange, various heaters can be used instead of steam. It is also possible to indirectly exchange heat using a heat exchanger. Furthermore, it is also possible to install a mixer in a pipe without using a tank and perform heat exchange directly in the pipe.

 The advantages of the present invention include the following.

(1) By increasing the temperature of the roll in advance compared to starting the casting with the roll temperature kept low, the roll base material can be maintained at the transition temperature or higher, the impact value can be increased, and the roll breakage can be prevented. .

(2) Since only the necessary roll cooling water is circulated, the amount of cooling water for cooling can be reduced, and the power for the water pumping station can be reduced.

(3) Normal circulation water temperature (15
Up to 30 ° C) using a cooling tower.
Energy loss can be reduced, and equipment costs can be reduced.

<Effects of the Invention> As described above, the present invention, prior to casting,
After the roll of the continuous casting machine has been heated to a temperature equal to or higher than the transition temperature of the roll base material by temperature circulation, casting is started,
Mix part of the heated return water during casting with cold water
The temperature is adjusted to 20 to 100 ° C, and this is returned to the roll as roll cooling water.

For this reason, since the roll is kept at the transition temperature or higher, the impact value of the roll base material does not decrease and the roll breakage can be prevented.

In addition, since cooling water is circulated with warm water of 20 ° C or more, it is not necessary to cool to normal ring water temperature (15 to 30 ° C), and the amount of cold ring water used can be reduced. In addition, there is an advantage that the energy is extremely advantageous and the equipment cost is low.

[Brief description of the drawings]

FIG. 1 is a system diagram of hot water cooling of a roll according to the present invention,
The figure is a system diagram of conventional roll cooling using cold ring water. Symbol 1 Roll 2 Temperature control tank 3 Steam pipe 4 Flow control valve 5 Thermometer 6 Silencer 7 Strainer 8 Circulation pump 9 Drain pump 10 Hot water receiver Tank 11 Thermometer 12 Flow control valve 13 Water collecting tank 14 Upper alarm switch 15 Lower alarm switch 16 Sprinkler header 17 Cooling tower 18 Water pump 19 Return water Pump 20: Sluice (for overflow) 21: Intake port 22: Return water outlet

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-58-23546 (JP, A) JP-A-52-90418 (JP, A)

Claims (1)

(57) [Claims] When cooling a roll while circulating cooling water through the roll of a continuous casting machine, the steam in the cooling water is blown to raise the temperature to make hot water. After the material is heated to the transition temperature or higher, casting is started, and during the subsequent casting, a part of the return water that has been subjected to cooling of the roll and that has been heated and returned has been mixed with cold ring water to reach a temperature. A method of cooling a roll in a continuous casting machine, wherein the temperature is adjusted to a range of 20 to 100 ° C., and this is returned to a roll as cooling water.