JPH02145463A - Method for control water content in crushing unit for granulated slag - Google Patents

Abstract

PURPOSE:To stabilize the quality of the products with labor saving by effecting the measurement of water content in the starting granulated slag continuously and automatically. CONSTITUTION:The granulated slag is weighed with the feed conveyer scale 5 and introduced into the roller mill 7 and crushed, while the hot air from the hot air generator 10 is fed into the roller mill 7 and the fine powder of the slag is pneumatically sent to the product conveyer scale 16. At this time, the weight values from the feed conveyer scale 5 and the product conveyer scale 16 are sent to the arithmetic unit 27, respectively, and the values are compared with the set values form the setting unit 28. The output is sent to the display memory 29 to conduct automatic control of the feed rate, feed accumulation, production rate and product accumulation and the water content of the feedstock slag. In the meantime, the output from the arithmetic unit 27 is input to the controlling unit 80 and the output signals from the controlling unit 30 controls the motor 31 driving the feed conveyer scale 5 whereby the feed rate of the granulated slag to the roller mill 7 is controlled to prevent the load fluctuation in the mill.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for controlling moisture in the production of granulated granulated slag powder, which is a raw material for blast furnace cement and the like.

[Prior Art] In recent years, problems such as alkaline aggregate reaction in concrete have become a problem, and there is an increasing demand for inexpensive and strong blast furnace cement that is free from such problems. Granulated slag powder is a raw material for this blast furnace cement, and with the practical use of vertical roller mills, many mills for producing this powder have been installed.

By the way, granulated slag contains a relatively large amount of water (approximately 8 to 18 wt%), and since the water content fluctuates widely, fluctuations in the load of the fine powder mill and fluctuations in the amount of fine powder produced become a problem. .

The load fluctuation of the mill is determined by the specific surface area (generally the Bullen value, ci
/g), resulting in deterioration of product quality. Conventionally, for quality control purposes, the amount of raw materials supplied has been artificially controlled by taking a sample about once an hour and measuring its moisture content.

[Problem to be Solved by the Invention 1] However, with the artificial control of water content as in the prior art, it is only possible to perform intermittent measurements, and the moisture content of the raw material cannot be grasped quickly and accurately. Mill operating conditions such as the amount of raw materials supplied to the mill and the amount of hot air supplied to the mill cannot be accurately controlled. For this reason, product quality becomes unstable and product production volume cannot be adequately controlled.

In addition, it is time-consuming to artificially measure the moisture content of the raw material granulated slag.

Therefore, the main purpose of the present invention is to continuously and automatically measure the water content of raw material granulated slag, thereby stabilizing product quality and saving labor.

[Means for Solving the Problems] The present invention for solving the above problems involves cutting out a predetermined amount of raw material granulated slag, weighing it on a cutting conveyor scale, supplying it to a mill, pulverizing it, and then passing it through a bag filter. In the method for obtaining fine powder of granulated slag through the process of It is characterized by measuring the amount of moisture inside.

[Function] In the present invention, since the water content in the raw material granulated slag is determined by comparing and calculating the measured value on the cut-out conveyor scale and the measured value on the product conveyor scale, the water content is continuously calculated. Moreover, it can be measured automatically, which makes it possible to automatically control the amount of raw materials supplied to the mill and the amount of hot air supplied to the mill, making it possible to stabilize product quality. Furthermore, continuous moisture measurement on the product conveyor scale has made it possible to automatically manage product production volume.

[Specific structure of the invention] The present invention will be explained in more detail below based on the drawings.

First, with reference to FIG. 2, an outline of an example of equipment for producing a product granulated slag powder from granulated slag according to the present invention will be explained. Granulated slag, which is a raw material, is supplied from a dump truck to a charging hopper 2, then passed through a conveyor 3 and stored in an intermediate bin 4. A predetermined amount of granulated slag is cut out from the intermediate bin 4 and placed on a cut-out conveyor scale 5, where its weight is measured, and then guided to a roller mill 7 via a conveyor 6. In this mill 7, the granulated slag is crushed into fine powder by a roller 7a driven by a motor M, while air and fuel 9 from a combustion air fan 8 are supplied to a hot air generating furnace 10, and a dilution fan 1
1 is introduced from the bottom of the mill 7 through a duct 12.

The obtained granulated slag powder is dried by the hot air and conveyed by air through the mill outlet duct 13, and is supplied to the product collecting bag filter 14, and then passed through the rotary valve 15.
The product is cut out onto the product conveyor scale 16 via.

The granulated slag powder weighed by the product conveyor scale 16 is then transferred to the product tank 19 via conveyors 17 and 18.
The fuel is stored in the storage area and then shipped by tank truck 20.

The air separated by the product bag filter 14 passes through an exhaust gas duct 21 and is pressurized by an exhaust fan 22, a part of which is discharged from an exhaust tower 23, and the remainder is passed through a circulating gas duct 24 to a flow meter 25 and circulating gas flow rate adjustment. It is introduced into the hot air duct 12 via the valve 26 and used for circulation.

Next, the method for controlling the moisture content of granulated slag powder according to the present invention will be explained in detail with reference to FIG. As described above, in the present invention, the granulated slag raw material is cut out and weighed on the conveyor scale 5, and then introduced into the roller mill 7 and pulverized.
Hot air is supplied to the roller mill 7, and the obtained granulated slag powder is air conveyed and supplied to the product conveyor scale 16. In this case, the weighed value from the cut-out conveyor scale 5 and the weighed value from the product conveyor scale 16 are led to a weighing calculator and compared with the production amount set value from the setting device 28. The output is displayed on the storage device 29
Continuous automatic management of raw material input amount, raw material input total, production volume, production volume total, and raw material moisture. On the other hand, the metric calculator 2
The output from 7 is input to the control device 30, and the output signal controls the drive motor 31 of the cutting conveyor scale 5.
is controlled to control the amount of granulated slag supplied to the roller mill 7, thereby preventing fluctuations in the load of the mill. Furthermore, the opening and closing of the circulating gas flow rate regulating valve 26 is adjusted based on the output from the control device 30, thereby controlling the amount of circulating gas to be circulated to the mill 7.

The moisture content of the raw material granulated slag in the present invention can be obtained using the following formula: Measured value on the cutting conveyor scale (L/Irwb) Measured value on the product conveyor scale (t/l-1dry) = Moisture content (t/H) [Example] Next, an example will be described.

(1) Measurement of water content in raw material granulated slag When the water value measured by a Hermes moisture meter (a general moisture meter that measures the difference in weight before and after drying) is positive, the results shown in Table 1 were obtained.

However, since the Hermes moisture meter requires time (about 5 minutes) to obtain the moisture value, there is some discrepancy.

is given by Here, wb indicates wet basis.

Automatic control of the raw material supply amount (cutting conveyor scale amount (t/Hwb)) in the present invention is performed based on the following equation.

Further, the optimum amount of circulating gas in the present invention is determined from the correlation graph (FIG. 3) between the water content of the raw material granulated slag and the amount of circulating gas.

(2) Product specific surface area (Blen value) cut/g Table 2 shows the measurement results of the product specific surface area, which is an indicator of quality control. The mill operating conditions were constant, the target Blen value was 4300 CiI/g, and the measurement pitch was 1 time/hour (initially it was a measurement of 1% aO, but since it was stable, it was changed to 1 time/hour) Table 2 Table 3 (3) Product Moisture Content Next, Table 3 shows the measurement results of product moisture content.

In this case, the conditions are: exhaust gas amount 9600 ONm3/H1 circulating gas amount approximately 3000 ONm3/H (varies depending on moisture)
, the mill outlet exhaust gas temperature was 90°C, and the granulated slag was simply ground.

(Note) Moisture control value 0.1% or less [Effect of the invention] As described above, the present invention has the following effects.

(1) The water content of the raw material granulated slag can be measured continuously and automatically, eliminating the need for troublesome once-hourly artificial sampling and water content measurement.

(2) Automatic management of production volume has become possible.

(3) Since the operating conditions of the mill have become stable, it is only necessary to set the mill operating conditions when starting the mill, and there is almost no need for manual operation.

(4) It has become possible to automatically control the optimal amount of circulating gas, making it possible to stabilize product moisture and save energy.

(5) Since the raw material granulated slag supply amount does not vary depending on moisture, the mill vibration was stabilized at about 16 to 17 μ (both widths).

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a specific example of the production equipment for fine granulated slag powder according to the present invention, FIG. 2 is an explanatory diagram of the moisture control method according to the present invention, and FIG. %) and gas amount (X 10'Nm3/l (). 4... Intermediate bin, 5... Cutting conveyor scale,
7...Roller mill, 10...Hot air generating furnace, 12.
...Hot air duct, 14...Product collection bag filter-1
16...Product conveyor scale. ■

Claims (1)

[Claims] (1) Cut out a predetermined amount of raw material granulated slag, weigh it on a cut-out conveyor scale, and then supply it to a mill and crush it.
In a method for obtaining granulated slag powder through a bag filter; after the product taken out from the bag filter is placed on a product conveyor scale and weighed, the weighed value on the cut-out conveyor scale is compared with the weighed value on the cut-out conveyor scale; A method for controlling moisture in granulated slag crushing equipment, characterized by measuring the amount of moisture in slag.