JPH01194A - pH adjustment method in coal-water slurry production - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field] The non-invention is coal-water slurry (hereinafter abbreviated as CWU)
This invention relates to an OWM p)I adjustment method applied to corrosion prevention of component equipment in manufacturing and OWM quality improvement.

[Conventional technology]

FIG. 2 is an explanatory diagram of a pH adjustment method in conventional OWMa production.

In the figure, raw coal is crushed by a crusher 2 from a raw coal bunker 1, and is supplied to a wet tube mill 3.
Milled at 50%. At this time, the pH drops to about 4 to 5 depending on the type of coal. Thereafter, it is diluted to a concentration of 50% in a collect tank 4, and separated into a coarse slurry 7 and a fine slurry 6 by a classifier 5. Coarse slurry 7
is returned to the wet tube mill 3 on the upstream side. On the other hand, the fine slurry 6 is supplied to the vacuum dehydrator 8,
The dewatered cake conveyor 9 supplies the slurry to the next slurry conditioning system.

That is, the slurry is first sent to the first slurry conditioning tank 10 and adjusted to a slurry with additives 30 and water 40. The slurry obtained in the first slurry adjustment tank 10 is supplied to the second slurry adjustment tank 11 through the first rhinomixer 12t, and a part of the slurry that has exited the second slurry adjustment tank 11 is transferred to the second slurry adjustment tank 11. After passing through the rhino mixer 13, the other part goes directly to the recirculation pipe 1.
4 to the first slurry adjustment tank 10, and the remaining slurry is extracted as a product by the OWM delivery bong 15.

In the above 70-, the so-called low-concentration slurry thread equipment from the wet tube mill 3 to the dehydrated cake conveyor 9 is constantly in contact with the slurry having a pH of 4 to 5.

Conventional pH adjustment is performed by adding a p.p.
Na from the H adjuster tack 16 to the pH adjuster pump 17
Add OH@ pH adjuster to adjust pH from 4 to 5 to pH 8 to 9
It was adjusted to

The slurry adjustment method for this conventional high concentration slurry yarn is as follows:
The stability of pH adjustment was high because the slurry was sufficiently circulated and mixed using a line mixer, etc. However, when problems occurred due to the lifespan of the pH adjuster pump 17 and overcurrent trips, the pH suddenly decreased. OWM
As a result, the viscosity of the liquid becomes too thick, and the CWU production has to be stopped. An example is shown in FIG. The plot in FIG. 3 is the measurement result using a Haake viscometer (off-line), and it can be seen that the characteristics of OWM tend to show an increase in viscosity in an acidic region, while a tendency to show a decrease in viscosity in an alkaline region.

[Problems to be Solved by the Invention] The above pH adjustment method in the conventional OWM backing has the following drawback fc.

(1) Since the pH of only the high-concentration slurry yarn is adjusted, the low pH of the low-concentration slurry yarn causes corrosion of the component equipment.

(2) As mentioned above, in the conventional pH adjustment method, the circulation of the slurry and the mixing of the slurry by a stirrer etc. were sufficient, and the stability of pH adjustment was high, but there were problems due to the life span of the pH adjuster pump 17 and overcurrent trip occurs, suddenly p
H decreases and the viscosity of OWM increases too much.

(3) Although pH adjustment is performed using a highly concentrated slurry system,
This fine adjustment is difficult.

(4) When adjusting the pH of a highly concentrated slurry system, an OWM sample is collected and analyzed in a timely manner, and then fed back to the pH control, which results in a wide adjustment range and requires a large amount of time.

The object of the present invention is to provide an OWM that eliminates the drawbacks of the above-mentioned conventional methods.
It is an object of the present invention to provide a pH adjustment method that can be used in manufacturing.

The present invention is a wet tube mill for crushing raw coal.

In the method for adjusting the pH of a coal-water slurry production system, which includes a dehydrator for dewatering the slurry obtained in the mill, and nine slurry adjustment tanks for adjusting the slurry using a dehydrated cake, the wet tube of a low concentration system is provided. On-line pH adjustment system in which the amount of pH adjuster input into each system is set at the dehydrator and the slurry adjustment tank outlet in the slurry adjustment tank of the mill and high concentration system.
The present invention relates to a method for adjusting pH in coal-water slurry production, which is characterized by adding a pH adjuster while automatically adjusting the pH using a meter.

[Effect]

The present invention has two pH adjustment points, one for the wet mill inlet for the low concentration system, instead of one for the conventional high concentration system, and adjusts the pH for both the low concentration yarn and the high concentration yarn. Adjustments are made automatically using the on-rifle H meter.

〔Example〕

FIG. 1 is an explanatory diagram showing an embodiment of the method of the present invention.

As mentioned above, in the present invention, pH control is performed at two locations: a low concentration system and a high concentration system.

pH adjustment of the low concentration system is carried out by a pH adjuster tank 16, a pH adjuster pump 17', a pH adjuster flow meter 18', and an online pH meter 20. In a low concentration system, the pH is controlled from 4 to 6 in the acidic range to 7, which is outside the corrosive range. This pH control is performed by detecting the pH of the slurry in the tank with an online pH meter 20 installed in the slurry tank in the vacuum dehydrator 8, and adjusting the amount of pEI adjuster input with the pH adjuster pump 17'. pH to tube mill 3
This is done by adding a conditioning agent.

On the other hand, like the low concentration system, the high concentration system also includes a pH adjuster tack 16, a pH adjuster pump 17, a pH adjuster flow meter 18,
The pH is adjusted using an offline pH meter 19. For high concentration systems, pH control from pH 7 to pH 8-9. This OPH control detects the pH of the high concentration slurry that has exited the first slurry adjustment tank 10 using an online pH meter 19,
This is carried out by adjusting the amount of pH adjuster input with the pH adjuster pump 17 and charging the pH adjuster into the first slurry adjustment tank 10.

As a result, the pH of the low concentration system immediately before the first slurry adjustment tank 10 from the wet tube mill 3 is adjusted to 7, and the pH of the high concentration system after the first slurry adjustment tank 10 is adjusted to pH 8 to 9.

〔Effect of the invention〕

According to the present invention, the following effects can be achieved.

(1) Corrosion can be prevented not only in high concentration systems but also in low concentration system components.

(2) pH adjustment can be performed automatically (1) using an online pH meter, allowing fine and highly accurate adjustment of pH.

(3) By adjusting the pH in two places, the low concentration system and the high concentration system, there is no sudden pH drop that would occur when adjusting only with the conventional high concentration system, and when used in combination with the automation described above, 5p ■
Adjustment accuracy is greatly improved.

(4) Through the above (1) to (3), it is possible to improve the quality of the OWM product.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing one embodiment of the method of the present invention, and FIG.
The figure is an explanatory diagram of a conventional method. FIG. 3 is a chart showing an example of the relationship between pH and viscosity of OWM.

Claims (1)

[Claims] In a pH adjustment method for a coal-water slurry production system that includes a wet tube mill for crushing raw coal, a dehydrator for dehydrating the slurry obtained by the mill, and a slurry adjustment tank for adjusting the slurry using a dehydrated cake. , the amount of pH adjuster added to the wet tube mill for a low concentration system and the slurry adjustment tank for a high concentration system is automatically determined using an online pH meter installed at the dehydrator and the outlet of the slurry adjustment tank. A method for adjusting pH in coal-water slurry production, characterized by adding a pH adjuster while adjusting the pH.