JP2510084B2 - Sensible heat recovery method for molten slag - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method of granulating molten slag discharged from a blast furnace by a granulating device and recovering sensible heat of the slag particles by a heat exchanger or the like.

Conventional technology and its problems As a granulating apparatus for stirring and granulating the molten slag discharged from the blast furnace, a molten slag inlet (1-2) and a granulated slag outlet (1- 3) and a stirring blade for transferring the molten slag to the discharge port (1-3) while stirring and granulating the molten slag in a long granulating drum (1-1) having a cooling medium passage on the outside. A structure having (1-5) and a rotating shaft (1-4) provided with a cooling medium passage therein is known (Japanese Patent Laid-Open No. 58-199034).
This granulating apparatus is capable of stirring and granulating molten blast furnace slag in a non-oxidizing atmosphere to continuously connect granular slag having a particle size of 80 mm or less. The produced slag particles are cooled by a slag cooling device, and the heated gas is introduced into a heat exchanger or the like to recover heat.

The molten slag treatment technology has an excellent feature that high-quality slag particles with few pores can be obtained because the molten slag is cooled in the non-oxidizing atmosphere, but it is obtained by changing the slag flow rate. There was a problem that the temperature of slag particles changed greatly and slag particles with a target temperature of 1000 to 1050 ° C could not be stably obtained, and sensible heat lost in the process of solidifying to the target temperature could not be efficiently recovered. .

OBJECT OF THE INVENTION The present invention has been made in order to solve the problems of the conventional molten slag processing technology, and can obtain slag particles having a target temperature even if the slag flow rate fluctuates, and perform heat exchange. It is an object of the present invention to propose a method for recovering sensible heat of molten slag capable of increasing the sensible heat recovery rate in a vessel or the like.

Configuration of the Invention The sensible heat recovery method of the molten slag according to the present invention, the molten slag is fed into the granulating drum of the cooling structure having the rotating shaft of the cooling structure having the stirring blades on the outer periphery, and the stirring blades are After stirring and granulating, in the method of cooling the slag particles and recovering the slag sensible heat by a heat exchanger or the like, the flow rate and temperature of the molten slag supplied into the granulating drum are measured,
Based on the above measured values, the discharge temperature of the granulating drum is 1000 to 1050 ℃
It is characterized in that the cooling slag is mixed with the molten slag so as to be supplied.

 Hereinafter, the method of the present invention will be described in detail.

In the method of granulating the molten slag by stirring in a non-oxidizing atmosphere, as shown in FIG. 6 which shows the relationship between the molten slag amount (blast furnace slag amount) and the granulation temperature, Granulation temperature fluctuates greatly. Therefore, in this invention, the cooling slag is mixed into the molten slag based on the flow rate and the temperature of the molten slag supplied to the granulating device, and the sensible heat of the solidification granulation process of the molten slag is applied to the cooling slag to thereby recover the amount of heat. The number is increased, and at the same time, the fluctuation of the processing amount processed in the granulating apparatus is absorbed.

FIG. 1 shows an apparatus configuration example for carrying out the method of the present invention. (1) is a slag granulating apparatus, (2) is a slag particle cooling apparatus, and (3) is a heat exchanger for sensible heat recovery. , (4)
(5) is a bunker, (6) is a dust remover, and these are existing equipment. According to the method of the present invention, a slag flow meter (7), a slag thermometer (8), a cooling slag amount setting controller (9), and a cooling slag amount regulator are provided in a molten slag supply system to the granulating device (1) of the equipment. It can be carried out by installing (10) and the cooling slag hopper (11).

That is, the molten slag (12) and the cooling slag (13) are supplied to the slag granulating device (1) to obtain hot slag particles at 1000 to 1050 ° C and stored in the bunker (4). Next, the slag cooling device (2) is charged with a certain amount from the bunker (4),
The sensible heat is recovered from the heated gas by cooling with the circulating gas (14) and the heat exchanger (3). On the other hand, the cooled product slag is discharged after being stored in the bunker (5), but part of it is sent to the molten slag supply system as cooling slag, mixed with the molten slag (12), and again fed to the slag granulator (1). Charge. Needless to say, the cooling slag mixed in the molten slag is not limited to the slag particles and may be supplied from other sources.

Here, the charging amount Xc of the cooling slag (13) is based on the value Xh measured by the slag flowmeter (7) and the temperature Th measured by the thermometer (8), and the slag particle temperature is changed to 1000 to 1050 ° C. The setting controller (9) determines that the cooling slag hopper (1
The amount of cooling slag cut out from 1) is adjusted by a cooling slag amount adjuster (10). The relationship between Xc, Xh, and Th is given by the following equation.

However, Tc: Temperature of cooling slag (product slag) A, B: Constant determined by the capacity and shape of the granulator k: k <1 Modified coefficient Note that the target temperature of the slag particles is 1000 to 1050 ℃ Was determined by looking at the safety factor at an upper limit temperature of 1100 ° C at which re-fusion after granulation did not occur.

As described above, the present invention mixes the cooling slag with the molten slag at a ratio determined by the flow rate and temperature of the molten slag supplied to the slag granulator, so that the molten slag solidifies in the granulator. The slag sensible heat in the granulation process is given to the cooling slag, and is cooled together with the granulation slag to recover the sensible heat. Therefore, the amount of slag sensible heat partial heat recovery in the solidification and granulation process of the molten slag increases, which has the effect of increasing the heat recovery rate.

Also, since the temperature of the slag particles granulated by the granulator can be adjusted by the amount of cooling slag so that it reaches the target temperature, it is possible to absorb the fluctuations in the flow rate of the slag discharged from the blast furnace, and the slag particle sensible heat It has an effect that can be stably recovered with high yield.

Example When targeting slag generated from a 5000 m ³ class blast furnace, the tapping rate is 10000 T / D and the tapping rate is AVe 2.1 T / min, MAX 6 T / min
Is. When this molten blast furnace slag was treated with the cooling slag by the granulating apparatus shown in FIG. 1, the initial 1/3 was excluded as the time and the initial 1/9 was excluded as the slag amount.
The granulation temperature could be kept constant at 1000 ° C. Further, the heat recovery amount could be increased by about 20% compared to the conventional method in which the cooling slag was not used.

The relationship between the molten slag amount and the granulation temperature in this example is shown in FIG. 2, and the slag generation pattern is shown in FIG.
Similarly, the granulation temperature patterns are shown in FIG. 4, respectively.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of the apparatus configuration for carrying out the method of the present invention, FIG. 2 is a view showing the relationship between the amount of molten slag and the granulation temperature in the embodiment of the present invention, and FIG. 3 is the same slag generation. The figure which shows a pattern, FIG. 4 is a figure which similarly shows a granulation temperature transition, FIG. 5 is the schematic which shows a slag granulator, FIG. 6 is a figure which shows the molten slag amount in the same apparatus, and the relationship of granulation temperature. Is. 1 ... Granulating device, 2 ... Cooling device, 3 ... Heat exchanger, 4,
5 …… Bunker, 7 …… Slag flowmeter, 8 …… Slag thermometer, 9 …… Cooling slag amount setting controller, 10 …… Slag amount adjuster, 11 …… Cooling slag hopper, 12 …… Melting slag, 13 …… Cooling slag.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tsutomu Ueno No. 3 Hikari, Kashima, Kashima-cho, Kashima-gun, Ibaraki Sumitomo Metal Industries, Ltd. (56) Reference JP-A-53-112295 (JP, A) JP 58-199034 (JP, A)

Claims (1)

(57) [Claims] 1. A method of collecting sensible heat after agitation of a molten slag by a granulator to granulate the slag, the flow rate and temperature of the molten slag supplied to the granulator are measured, and based on the measured values. A method for recovering sensible heat of molten slag, which comprises mixing cooling slag with molten slag and supplying the slag so that the discharge temperature of the granulating device becomes 1000 to 1050 ° C.