JP2016159200A - Cooling method and cooling device of mist nozzle spray type - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling method of a mist nozzle spray type capable of reducing consumption of pressurized gas, while maintaining similarly a cooling capacity.SOLUTION: In a cooling method of a mist nozzle spray type using a mist nozzle for miniaturizing and spraying liquid by mixing together two fluids of the liquid and pressurized gas, the liquid is supplied continuously to the mist nozzle, and the pressurized gas is supplied thereto in a pulsed manner.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a mist nozzle spraying cooling method using a mist nozzle that mixes two fluids of liquid (mainly water) and pressurized gas (mainly compressed air) to atomize the liquid and sprays the same. It relates to the cooling device.

  The mist nozzles of the mist nozzle spray cooling system used for cooling the blast furnace core of steelworks and slabs in continuous casting facilities are generally liquid (mainly water) and pressurized gas (mainly compressed air). 2) is continuously supplied to make the liquid finer and ejected. In order to refine the liquid so as to obtain the required cooling capacity, the pressure and flow rate of the pressurized gas corresponding to the nozzle characteristics and the liquid flow rate are required (see Patent Document 1).

  By the way, in recent years, there has been a demand for reducing the consumption of pressurized gas due to the demand for energy saving. However, the reduction of pressurized gas consumed by a mist nozzle is usually mainly based on the selection of the nozzle. If only the pressure and flow rate of the pressurized gas are lowered without changing the liquid flow rate, the droplet diameter becomes coarse, and it becomes difficult to obtain a predetermined cooling capacity and spray pattern.

  As a mist nozzle that reduces the consumption of pressurized gas, it has a structure that can simultaneously open and close the liquid / gas discharge flow path with the built-in needle valve, and by opening and closing the needle valve at high speed, the mist nozzle Is commercially available (for example, a 1/4 JAU series manufactured by Spraying System Co., Ltd. described in Patent Document 2).

JP 2010-253525 A Japanese Patent Laid-Open No. 10-319630

  However, since this needle valve type mist nozzle also supplies liquid (water) in a pulsed manner, the amount of cooling water decreases. Therefore, the consumption of pressurized gas (compressed air) per cooling capacity can hardly be reduced. In addition, this needle valve type mist nozzle is more expensive than a normal mist nozzle due to its large number of parts, and the drive part is involved in both liquid and gas. Is likely to occur.

  Therefore, an object of the present invention is to propose a mist nozzle spray type cooling method and cooling device that can reduce the consumption of pressurized gas while maintaining the same cooling capacity with a simple, inexpensive and reliable configuration. It is in.

  The mist nozzle spray cooling method of the present invention, which aims to advantageously solve the above-mentioned problems, is a mist nozzle using a mist nozzle that atomizes and atomizes a liquid by mixing two fluids, a liquid and a pressurized gas. In the spray-type cooling method, the liquid is continuously supplied to the mist nozzle and the pressurized gas is supplied in a pulse shape.

  Moreover, the mist nozzle spray type cooling device of the present invention aiming to solve the above-mentioned problem advantageously includes a mist nozzle for atomizing and spraying a liquid by mixing two fluids, a liquid and a pressurized gas. In the mist nozzle spray type cooling device, a pulse valve for pulsing the pressurized gas is interposed between the mist nozzle and the supply source of the pressurized gas.

  A general mist nozzle aims to obtain a required droplet diameter, cooling capacity, and spray pattern by continuously supplying a liquid and a pressurized gas together to refine the liquid. However, the supply of pressurized gas does not necessarily have to be continuous, and the present inventor has confirmed by experiment that liquid can be miniaturized in the same way as when it is supplied continuously even when it is supplied in pulses. did.

  The mist nozzle spray type cooling method and the mist nozzle spray type cooling device of the present invention continuously supply liquid to the mist nozzle and supply pressurized gas in pulses based on the above knowledge of the present inventors. As a result, the consumption of pressurized gas for spraying can be greatly reduced while maintaining the same cooling performance without reducing the amount of coolant.

  Moreover, since the liquid is continuously supplied to the mist nozzle and the pressurized gas is supplied in a pulsed manner, only the pressurized gas acts on the pulse valve. It is possible to increase the reliability of the cooling device by reducing the possibility of valve clogging and failure.

  In the mist nozzle spray cooling method of the present invention, the pressurized gas supply pressure may be higher than the liquid supply pressure by 0.1 MPa or more. This is preferable because the change in droplet diameter can be suppressed to such an extent that the cooling capacity is not affected.

  Moreover, in the mist nozzle spray type cooling device of this invention, you may determine the upper limit of the pulse frequency of pressurized gas according to the internal volume of piping from a pulse valve to a mist nozzle. If the pulse frequency of the pressurized gas is too high for the internal volume of the pipe from the pulse valve to the mist nozzle, the next pulse will come before the residual pressure of the pulse is released in the pipe, and the pressurized gas The effect of pulsing is reduced. If the upper limit of the pulse frequency of the pressurized gas is determined according to the internal volume of the pipe from the pulse valve to the mist nozzle, it is preferable because the effect of pulsing the pressurized gas can be utilized.

  In this case, if the relationship between the internal volume X (L) of the pipe from the pulse valve to the mist nozzle and the upper limit Y (Hz) of the pulse frequency of the pressurized gas is Y = 0.11 / X, This is preferable because the effect of pulsing can be utilized.

It is a side view showing typically composition of a mist nozzle spray type cooling device of one embodiment of the present invention using a mist nozzle spray type cooling method of one embodiment of the present invention. (A), (b) is the front view and side view which show the example of the mist nozzle used with the mist nozzle spray type cooling device of the said embodiment. It is a relationship diagram which shows the change state with the passage of time of the flow volume of the compressed air supplied to a mist nozzle in the mist nozzle spray type cooling device of the said embodiment. It is explanatory drawing which compares and shows the particle diameter of the water sprayed in the continuous spray of the mist nozzle which supplies compressed air continuously, and the pulse spray which supplies compressed air in pulses. It is a relationship diagram which shows the relationship between the volume in piping, and the minimum pulse frequency which can ensure the pulsing effect.

  FIG. 1 is a side view schematically showing the configuration of a mist nozzle spray cooling device according to an embodiment of the present invention using the mist nozzle spray cooling method according to an embodiment of the present invention. b) It is the front view and side view which show the example of the mist nozzle used with the mist nozzle spray type cooling device of the said embodiment. The mist nozzle spray-type cooling device of this embodiment includes a mist nozzle 1 that atomizes water by mixing two fluids of water as a liquid and compressed air as a pressurized gas, and sprays the water from the spray port 1a. A water supply pipe 2 that supplies water from a water supply source (not shown) to the nozzle 1, a compressed air supply pipe 3 that supplies compressed air from a compressed air supply source (not shown) to the mist nozzle 1, and a compressed air supply pipe 3. And an intervening pulse valve 4.

  Here, the mist nozzle 1 is used for cooling a relatively low temperature target such as a blast furnace iron skin, and by supplying compressed air from the rear and supplying water from the side, water droplets are sheared with an air flow to make fine The normal type.

  Here, the pulse valve 4 may be of an external pilot type or an internal pilot type, and is of a type that discharges pulsed compressed air by repeatedly opening and closing the main valve with the pilot pressure of the continuously supplied compressed air. However, it may be of a type that discharges pulsed compressed air by repeatedly opening and closing the main valve with a pilot pressure of compressed air supplied intermittently by opening and closing of the electromagnetic valve. In any type, the pulse frequency of the compressed air to be discharged can be arbitrarily set.

  The mist nozzle spray cooling method of the above embodiment performed by the mist nozzle spray cooling device of this embodiment continuously supplies water from the water supply pipe 2 to the mist nozzle 1 and pulses from the compressed air supply pipe 3. Compressed air pulsed by the valve 4 is supplied. FIG. 3 is a relationship diagram showing a change state of the flow rate of the compressed air supplied from the pulse valve 4 to the mist nozzle 1 over time. Here, the supply pressure of the compressed air is preferably higher than the supply pressure of water by 0.1 MPa or more.

  That is, a general mist nozzle is a system in which a liquid is discharged into a turbulent flow of a high-speed air flow to make a droplet fine. In addition, when supplying a liquid under pressure, a method of further miniaturizing the liquid itself by the discharge pressure and flow velocity with an air flow is also common. For this reason, the supply pressure of the pressurized gas is generally set to be the same as or higher than that of the liquid.

  On the other hand, in the experiment of supplying compressed air in a pulsed form performed by the present inventor, as shown in FIG. 4, the supply pressure A of compressed air is set to 0.3 to 0.45 MPa, and 0.1 to 0.3 MPa. When the water supply pressure W is set to 0.1 MPa or more higher than the case where the compressed air is continuously supplied, the Sauter average water droplet diameter is equal to or greater than 1.2 times, which affects the cooling capacity. It was possible to suppress the change in the water droplet diameter to the extent that there was not. On the other hand, when the compressed air supply pressure A and the water supply pressure W are set to the same 0.3 MPa, the Sauter average water droplet diameter is 1.5 times or more compared to the case of continuous supply, and the water droplets become coarse. The tendency to do was seen.

  Therefore, by making the supply pressure of the compressed air higher than the supply pressure of water by 0.1 MPa or more, it is possible to suppress the change in the water droplet diameter to the extent that the cooling capacity is not affected.

  The upper limit of the pulse frequency of the compressed air that is pulsed by the pulse valve 4 is preferably determined according to the internal volume of the compressed air supply pipe 3 from the pulse valve 4 to the mist nozzle 1.

  That is, when supplying compressed air in a pulse form, if the distance from the pulse valve 4 to be supplied in a pulse form to the mist nozzle 1 becomes long, the pulsed pressure wave gradually attenuates and finally there is no pressure fluctuation. Since it becomes a continuous flow, and then it becomes the same as the case of continuous supply at a reduced pressure, in order to utilize the effect of pulsing, the piping distance from the pulse valve 4 to the mist nozzle 1 is appropriately selected. There is a need. Also, the pulsing effect tends to attenuate as the frequency increases. From the results of the experiment, the inventor has found that the pulsing effect (the lowest value of the compressed air supplied to the mist nozzle 1 is the highest value) according to the internal volume of the compressed air supply pipe 3 from the pulse valve 4 to the mist nozzle 1. The upper limit of the frequency that can secure the pulsation of 50% or less) was clarified.

  FIG. 5 is a relationship diagram showing the upper limit of the frequency (Hz) that can ensure the pulsing effect according to the internal volume (L: liter) of the compressed air supply pipe 3. As a result of the experiment, the present inventor has found that when the upper limit of the frequency is Y and the pipe volume is X, the relationship is approximately Y = 0.1 / X as shown in the figure.

  According to the mist nozzle spray cooling device and the mist nozzle spray cooling method of the above embodiment, the amount of compressed air used is reduced from 30% compared to the conventional method of using a mist nozzle that continuously supplies compressed air. The maximum reduction is 50%.

(Example)
The method of using a mist nozzle that continuously supplied water and compressed air in the blast furnace cooling was changed to a method of supplying only compressed air in a pulsed manner using a pulse valve while continuously supplying water. As a result, the amount of compressed air used for cooling the skin could be reduced by 40%, and great energy saving was achieved. At that time, as a result of measuring the iron skin temperature of the cooling point with a thermoviewer, the temperature change is ± 5% or less compared to the case of continuous spraying, and the cooling capacity of pulsed spraying is almost the same as that of continuous spraying It was confirmed that.

  The mist nozzle spray cooling method and the mist nozzle spray cooling device of the present invention are not limited to the above examples, but may be changed as appropriate within the scope of the claims. For example, when the present invention is applied to cooling a relatively high temperature object such as a slab in a continuous casting facility, the mist nozzle 1 is supplied with water from the rear and compressed from the side. It is good also as a thing of the large water quantity type which accelerates | stimulates with an airflow and further refines | miniaturizes, after making a water droplet refine | miniaturize by a self-water pressure by supplying air.

  If necessary, the liquid to be sprayed may be other than water such as cooling oil, and the pressurized gas may be other than air such as an inert gas.

  According to the mist nozzle spray cooling method and the mist nozzle spray cooling device of the present invention, the consumption of pressurized gas for spraying can be significantly reduced while maintaining the cooling performance equal without reducing the amount of coolant. In addition, the cooling device can be configured easily and inexpensively, and the reliability of the cooling device can be increased by reducing the possibility of clogging or failure of the pulse valve.

1 Mist nozzle 1a Spray port 2 Water supply piping 3 Compressed air supply piping 4 Pulse valve

Claims (5)

In a mist nozzle spraying cooling method using a mist nozzle that atomizes and sprays a liquid by mixing two fluids, a liquid and a pressurized gas,
A mist nozzle spray cooling method, wherein the liquid is continuously supplied to the mist nozzle and the pressurized gas is supplied in a pulsed manner.   The mist nozzle spray cooling method according to claim 1, wherein a supply pressure of the pressurized gas is set to be 0.1 MPa or more higher than a supply pressure of the liquid. In a mist nozzle spray type cooling device comprising a mist nozzle that atomizes and atomizes a liquid by mixing two fluids, a liquid and a pressurized gas,
The mist nozzle using the cooling method according to claim 1, wherein a pulse valve for pulsing the pressurized gas is interposed between the mist nozzle and the supply source of the pressurized gas. Spray cooling device.   The mist nozzle spray type cooling device according to claim 3, wherein an upper limit of a pulse frequency of the pressurized gas is determined according to an internal volume of a pipe from the pulse valve to the mist nozzle.   The relationship between the internal volume X (L) of the pipe from the pulse valve to the mist nozzle and the upper limit Y (Hz) of the pulse frequency of the pressurized gas is Y = 0.11 / X, The mist nozzle spray type cooling device according to claim 4.

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