JPS62169891A - Production of highly concentrated coal slurry - Google Patents

Abstract

PURPOSE:To attain a stable operation of a dehydrator, by a process comprising pulverizing and deashing coal, adding adjusting water to be deashed slurry and dehydrating the slurry, wherein the solid concn. and flow rate of the deashed slurry fed into the dehydrator are measured to keep them constant. CONSTITUTION:Pulverized coal is fed into a floatation machine 1 for deashing. A part of the deashed slurry a is fed into a frothing vessel 4 while the remaining part is fed into a concn. adjusting stirring vessel 3, mixed with adjusting water 7 and stirred to attain a uniform particle diameter distribution. The deashed slurry is fed from the stirring vessel 3 into a dehydrator 2 to dehydrate it, thereby preparing a highly concentrated coal slurry c. In the above step, the solid concn. and flow rate of the slurry fed into the dehydrator 2 are measured with a densitometer 10 and a flowmeter 11. The amt. of the adjusting water 7 and the amt. of the slurry fed from frothing vessel 4 for storing froth a of the deashed slurry into the stirring vessel 3 are controlled based on the measurements, thereby keeping the solid concn. and flow rate of the slurry fed into the dehydrator 2 constant.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Industrial Application Field This invention relates to a method for producing a highly concentrated coal slurry used in thermal power generation and the like.

(2) Conventional technology In the production of highly concentrated coal slurry (CWM), deashing is generally carried out by flotation method.
The most important thing in the production of M is to ensure a stable particle size distribution and moisture content in the product cake.

What is shown in Figure 2 is the conventional CWM! This is an example of the A construction method. In the drawing, 1 grain size is 1200 mesh (0, 5a
The coal, which has been pulverized into relatively fine particles (less than ++a), is introduced into a flotation machine 1 at a solids concentration of 10 to 25% and deashed. Deashed coal.

In other words, the slurry containing clean coal has a solids concentration of 15 to 30%.
The flotation floss has a flow fluctuation of about ±50%, and is introduced into a thickener 21 for flotation floss via a line 20. The slurry is now somewhat concentrated and passes through line 22 to a solids concentration of 30-40.
% is led to a dehydrator 2 such as a filter, where it is dehydrated and becomes CWM with a solid concentration of 60% or more. Note that a is the flotation floss, b is the flotation tail, and C is the product cake.

(3) Problems that the invention attempts to solve By the way, the Shirafuna 21 has a classification function.

Therefore, the slurry supplied to the dehydrator 2 is divided into coarse particles and fine particles by the Shirafuna 21.

Particle size is classified into fine particles, and fluctuations in particle size distribution cannot be avoided. Moreover, the solid concentration and flow rate were not constant.

That is, the slurry supplied to the dehydrator 2 has a particle size distribution,
There were always variations in solids concentration and flow rate. Therefore, the load fluctuation of the dehydrator 2 increases, which not only affects the performance (capacity, dewatering rate) of the dehydrator over time, but also
There was a problem that the dehydrator could not operate stably.

Therefore, the technical object of the present invention is to reliably prevent variations in particle size distribution, solid concentration, and flow rate of slurry supplied from a flotation machine to a dehydrator.

(4) Means for Solving the Problems In order to solve the above-mentioned problems, the method for producing a high concentration coal slurry of the present invention involves introducing finely ground coal into a flotation machine to The deashing slurry and adjusted water are then introduced into a concentration adjustment stirring tank and stirred to maintain a state where there is no change in particle size distribution, and the solid concentration of the slurry supplied from the stirring tank to the dehydrator is adjusted. and the flow rate, and according to the measured values, control the amount of the adjusted water and the amount of slurry introduced from the floss tank storing the demineralized slurry froth to the stirring tank, and supply the slurry from the flotation machine to the dewatering machine. It is characterized by keeping the solid concentration and flow rate of the slurry constant.

(5) Embodiments In the embodiments shown below, the same members as those in the conventional system are given the same reference numerals, and the explanation thereof will be omitted.

FIG. 1 shows one embodiment of the invention. In the drawing, part of the slurry containing deashed coal is introduced into a concentration adjustment stirring tank 3 via a line 5. The slurry introduced into the stirring tank 3 is stirred by a stirring blade in the tank together with conditioning water introduced from a line 7 having an on-off valve 6, so that the slurry has no particle size distribution. On the other hand, stirring tank 3 and dehydrator 2
A concentration meter 10 and a flow meter 11 are installed in the line 8, and the solid concentration and flow rate of the slurry flowing through the line 8 are measured by these meters. If the concentration of solids in the slurry flowing through the line 8 is low, the opening degree of the on-off valve 6 is reduced, and if the solid concentration is high, the opening degree of the on-off valve 6 is increased, and the line 8 is increased. 7. The amount of conditioning water introduced is controlled so that the solids concentration of the slurry is constant. Further, if the flow rate of the slurry flowing through the line 8 is small as determined by the measurement by the flow meter 11, the slurry previously stored in the floss tank 4 is passed through the line 12.
Introduced into the stirring m3 by the pump 13 provided in the line,
On the other hand, if there are many meteors, the operation of the pump 13 is stopped to stop the introduction of slurry from the floss tank 4 to the stirring tank 3, and at the same time, the slurry that overflows in the stirring tank 3 flows out to the floss tank 4 through the line 14. The flow rate of the slurry is controlled to be constant.

In this way, the stirring tank 3 is operated so as to always overflow. Therefore, the slurry from the stirring tank 3 has no particle size distribution, and is kept constant in both solid concentration and flow rate, and is supplied to the dehydrator 2 via the line 8 by the pump 15 provided in the line. Note that the slurry overflowing from the dewatering machine 2 is discharged into the stirring tank 3 through a line 16, and a part of the slurry from the flotation machine 1 containing the deashed coal is introduced into the floss tank 4 through a line 17. and stored. This slurry storage is for emergency use.

In this embodiment, when the flow rate of the slurry flowing through the line 8 is large, the operation of the pump 13 is stopped to stop introducing the slurry from the floss tank 4 to the stirring tank 3, and at the same time, the overflowing slurry is frossed by the stirring M3. Although the flow rate is controlled by flowing the slurry into the tank 4, the method is not limited to this method. For example, if the pump 13 is a variable displacement pump and the flow rate of the slurry flowing through the line 8 is small, Needless to say, the flow rate may be controlled by introducing a small volume, if large, from the floss tank 4 into the stirring tank 3.

(6) Effects of the Invention As described above, according to the present invention, it is possible to reliably prevent variations in particle size distribution, solid concentration, and flow rate that have conventionally occurred in coal slurry supplied from a flotation machine to a dehydrator. It has the excellent effect of allowing stable operation of the dehydrator without affecting the performance of the dehydrator.

[Brief explanation of drawings]

Figure 1 is a flow sheet showing one embodiment of this invention;
The figure is a flow sheet showing a conventional example.

Claims (1)

[Claims] 1. Finely pulverized coal is introduced into a flotation machine to remove the ash contained in the coal, and then the deashing slurry and adjusted water are introduced into a concentration adjustment stirring tank and stirred to ensure no fluctuation in particle size distribution. At the same time, the solid concentration and flow rate of the slurry supplied from the stirring tank to the dehydrator are measured, and the amount of adjusted water and the froth of the deashing slurry are stirred from the stored floss tank according to the measured values. A method for producing a high-concentration coal slurry, characterized by controlling the amount of slurry introduced into a tank and keeping the solid concentration and flow rate of the slurry supplied from a flotation machine to a dehydrator constant.