JPH0140078B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a coal granulation device that granulates and recovers coal particles in a coal/water slurry into pellets with low power consumption and in a short time. [Conventional technology] In recent years, due to the instability of oil supply, the development of technology to effectively utilize coal has been progressing. In order to reduce the cost of transporting coal, it is effective to transport coal in slurry, and for this reason, there is a current demand for the development of equipment that can efficiently recover coal particles transported in slurry at low cost and in a short time. be. Conventionally, a method of transporting slurry of coal directly from a coal-producing area has been carried out in the United States and the Soviet Union, and has been reported in the literature. Conventionally, as shown in Japanese Unexamined Patent Publication No. 56-73557, pulverized coal slurry containing an oil-based binder is introduced into a sedimentation separation chamber 8 in a refining tank 1 from a raw material inlet 2, and its surface a ₁ is covered with a dense screen 11. The level is maintained to such an extent that only the base end of the coal is immersed, and the raw material is allowed to settle in the sedimentation separation chamber 8, where fine particles of the oil-based binder adhere to the surface of the lipophilic pulverized coal, and furthermore, such particles adhere to each other. They form a cohesive state, which floats to the upper layer of the raw material as floating matter d.
A device has been proposed in which non-oleophilic ash is allowed to settle and separate into a lower layer. Furthermore, in JP-A-56-73558, a pulverized coal slurry containing a particulate oil-based binder is introduced from the raw material inlet 7 of a refining tank 1 through a cylindrical screen 2, and the oil-based binder is deposited on the surface of the oleophilic pulverized coal. Fine particles adhere to each other, and these particles adhere to each other to form an agglomerated state, which floats up as floating matter and stays in the upper part of the cylindrical screen 2, and the ash, which is non-oleophilic, settles and separates. A device is described in which the ash slurry passes through a cylindrical screen 2 and is discharged through an ash slurry outlet 11. Furthermore, in Japanese Patent Application Laid-Open No. 56-122893, a slurry of coal particles is supplied from a line 16 to an aggregation vessel 10, a binder is supplied from a line 18 to a line 16, and the slurry and binder are turbulent by a rotating mixing blade 12. A method is described in which the mixture is subjected to intermixing and then allowed to flow through the annular space between the rotating drum 14 and the wall 20 of the agglomeration vessel to form pellets due to high shear stress. [Problems to be Solved by the Invention] In the conventional method described above, the separation of coal particles and water after transporting the slurry is performed using a centrifugal separator, and although the energy consumption is large, the coal particles after dehydration are There are disadvantages such as high water content in the particles (approximately 25-39%). Furthermore, in the apparatus described in JP-A-56-73557, the coal is turned into aggregates by the oil binder, but not into granules. Furthermore, in the device described in JP-A-56-73558, the aim is to achieve a rolling granulation effect of coal particle aggregates on the surface of a rotating cylindrical screen.
Unable to obtain satisfactory results in terms of efficiency. Furthermore, in the method described in JP-A No. 56-122893, the aim is to obtain a rolling granulation effect of coal particle aggregates in a rotating cylindrical drum, but even if the drum rotation speed is increased, the aggregates remain on the drum surface. Because of this, there is a limit to the granulation speed. The present invention was made in view of the above points, and the transported coal/water slurry is supplied to the first stage mixing tank, and heavy oil and a granulation accelerator are added and stirred to coat the surface of the coal with heavy oil and granulation. After being coated with the grain accelerator, it is transferred to the second stage granulator and stirred to form a mixed pellet of coal particles and heavy oil, and then the product is passed through a simple solid-liquid separator such as a vibrating sieve. By separating the mixed pellets into wastewater containing ash, the coal particles in the coal/water slurry can be recovered in a short time with low power consumption, and the dewatering efficiency is also high (the coal particles after dewatering are The purpose of the present invention is to provide a coal granulation device that can separate and remove a portion of the ash contained in the coal (approximately 20 to 25% water content) and also a portion of the ash contained in the coal. [Means and operations for solving the problems] The coal granulation device of the first invention of the present application will be described with reference to FIGS. 6 and 7. The coal/water slurry supply pipe 15 and the heavy oil - A vertical mixing tank 18 to which the granulation accelerator supply pipe 16 is connected and has stirring blades 17 inside; one end is connected to the lower part of this vertical mixing tank via a mixed liquid extraction pump 20; It consists of a horizontal granulator 23 having a stirring blade 21 at one end and a produced pellet/waste water outlet 22 at the other end, and a solid-liquid separator 24 connected to the produced pellet/waste water outlet of this horizontal granulator. It is characterized by Further, the coal granulation device of the second invention of the present application will be described with reference to FIG. 8, in which a coal/water slurry supply pipe 15 and a heavy oil/granulation accelerator supply pipe 16 are connected, Vertical mixing tank 1 with blades 17
8, one end is connected to the lower part of this vertical mixing tank via a mixed liquid extraction pump 20, and a stirring blade 2 is installed inside.
1 and a produced pellet/waste water outlet 22 at the other end.
a horizontal granulator 23 with
4, and is characterized in that a gas supply pipe 34 is connected to the lower part of the vertical mixing tank 18. Coal/water slurry is supplied into the first-stage mixing tank, heavy oil and granulation accelerator are added, and after turbulent agitation, the slurry is sent to the second-stage granulator where it is stirred to form coal particles. Form mixed pellets with heavy oil. The product is then sent to a solid-liquid separator, such as a vibrating screen, to separate the mixed pellets and ash-containing wastewater. Hereinafter, the configuration of the present invention will be explained based on the drawings. FIG. 1 shows an example of the apparatus of the present invention. 1
is a first-stage mixing tank equipped with stirring blades 2, and a coal/water slurry supply pipe 3, a heavy oil supply pipe 4, a granulation accelerator supply pipe 5, and a mixed liquid extraction pipe 6 are connected to this mixing tank 1. has been done. The mixed liquid extraction pipe 6 is connected to a second stage granulator 10 equipped with stirring blades 8 via a mixed liquid extraction pump 7.
The granulator 10 is further connected to a solid-liquid separator 12 of a simple structure such as a vibrating screen via a mixed pellet/wastewater discharge pipe 11. 1
3 is a mixed pellet extraction line, and 14 is a waste water extraction pipe. It is preferable that the stirring blade 2 in the mixing tank 1 has a rotation speed such that the tip speed is 1 to 4 m/sec, particularly 2 to 3 m/sec, and the stirring blade 8 in the granulator 10 has a tip speed of 1.5 to 9 m/sec. /second, especially 3
It is preferable to set the rotation speed to 8 m/sec. In the device configured as described above, first
The coal/water slurry is supplied into the mixing tank 1 in the second stage, heavy oil and a granulation accelerator are added, and after stirring them thoroughly with turbulent flow, the mixed liquid is transferred to the second stage granulator 10. The pellets are fed and stirred to form mixed pellets of coal particles and heavy oil. The product is then sent to a solid-liquid separator 12, such as a vibrating screen, where it is separated into mixed pellets and wastewater containing ash. The separated mixed pellets are either transported again or burned in a boiler. In the mixing tank 1, just before the power consumption or the viscosity of the slurry increases rapidly,
That is, it is allowed to stay up to the first stage of the granulation mechanism (the left straight part in FIG. 2, which will be described later), and thereafter it is kept in the granulator 10. Coal in mixing tank 1
When supplying a water slurry, heavy oil, and a granulation accelerator, instead of supplying each separately as shown in Figure 1, the granulation accelerator may be added to the coal/water slurry in advance, or the granulation accelerator may be added to the heavy oil in advance. In some cases, it is added and supplied as an emulsion. Normally, the concentration of coal in coal/water slurry transported from coal producing areas is often 40 to 50%, especially 43 to 47% on a dry basis, and the present invention can process coal/water slurries with these concentrations. suitable for. The heavy oil used in the present invention must have a viscosity necessary as a binder during granulation and must be relatively inexpensive. From this meaning, C
Heavy oil, B heavy oil, atmospheric distillation column bottom oil, etc. are suitable. Also, the amount of heavy oil added is 4% of that of coal on a dry basis.
~20% by weight, preferably 10-15% by weight. Furthermore, the granulation accelerator used in the present invention is
Anionic, nonionic, and cationic surfactants are used alone or in combination, and are appropriately selected depending on the type of coal. Specifically, anionic surfactants include alkylbenzene sulfonates, alkyl sulfate ester salts, polyoxyethylene alkyl (alkylphenol) sulfate ester salts, alkyl phosphate ester salts, dialkyl sulfosuccinate ester salts, acrylic acid and/or and maleic anhydride copolymers, polycyclic aromatic sulfonates, or formalin compounds, etc. As cationic surfactants, alkyl amine salts, quaternary amine salts, etc. are used, and nonionic surfactants Polyoxyalkyl ethers, polyoxyethylene alkyl phenol ethers, oxyethylene/oxypropylene block polymers, polyoxyethylene alkyl amines, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, etc. are used as amphoteric surfactants. For example, alkyl betaines are used, and amine compounds such as 1, 2, and 3 monoamines and diamines are used.
Also, the amount of granulation accelerator added is on a dry basis.
0.01-5.0% by weight, preferably 0.05-2.0% by weight. Some types of coal, such as Blairsall coal from Australia, are acidic, and in such cases, a neutralizing agent such as Ca(OH) ₂ is added to the coal/water slurry. and pH 6.5~
After adjusting the temperature to 10, preferably 7 to 9, heavy oil and a granulation accelerator are added. In addition, while adding heavy oil and granulation accelerator to the coal/water slurry, Ca
There is no problem in adjusting the pH to 6.5-10, preferably 7-9 by adding a neutralizing agent such as (OH) ₂ . It is thought that granulation in the present invention is carried out by the following process. First, the heavy oil and granulation accelerator added to the coal/water slurry are dispersed, and the granulation accelerator adsorbs onto the surface of the coal particles to modify the surface of the coal particles.Then, the heavy oil adheres to the surface of the coal particles. An oil film is formed, and then the coal particles adsorbed with the heavy oil and granulation accelerator collide and come into contact with each other, using the oil as a binder to coagulate and combine to form and grow flocs, which are further consolidated to form pellets. In the two-stage continuous granulation method apparatus of the present invention, the power required to simultaneously process 100 pieces of coal/water slurry was measured and compared with the measured value in the one-stage continuous granulation method. The results were as shown in Table 1.

〔Example〕

Next, an embodiment of the coal granulating apparatus of the present invention will be described based on FIGS. 6 to 8. FIG. 6 shows a two-stage granulation device formed by connecting a vertical mixing tank and a horizontal granulator, in which a coal/water slurry supply pipe 15 and a heavy oil/granulation accelerator supply pipe 16 are connected. Vertical mixing tank 18 with stirring blades 17 inside
A mixed liquid extraction pump 20 is installed in this vertical mixing tank 18.
A horizontal granulator 23 is connected at one end, has a stirring blade 21 inside, and has a produced pellet/waste water outlet 22 at the other end, and a produced pellet/waste water outlet 22 of this horizontal granulator 23. The solid-liquid separator 24 has a simple structure such as a vibrating sieve connected to the solid-liquid separator 24. 25 is a baffle plate, 26 is a mixed liquid outlet, 27
is the mixed liquid inlet, 28 is the pellet extraction line, 30
is a waste water discharge pipe, and 31 and 32 are motors. The waste water extraction pipe 30 is branched and connected to the inlet side of the mixed liquid extraction pump 20, and the outlet side of the mixed liquid extraction pump 20 is also connected to the upper part of the vertical mixing tank 18. Note that instead of the heavy oil/granulation accelerator supply pipe 16, a heavy oil supply pipe and a granulation accelerator supply pipe may be connected separately. In the first-stage vertical mixing tank 18, heavy oil containing a granulation accelerator or its emulsion is added to the coal water slurry, stirred and mixed thoroughly, and then extracted from the mixed liquid outlet 26 at the bottom, and the mixed liquid extraction pump 2
0, it is transferred to the second stage horizontal granulator 23. A plurality of baffle plates 25 are installed in the vertical mixing tank 18, and the rotation of the stirring blades 17 generates an up-and-down circulating flow, creating a turbulent flow state. As for the shape of the stirring blade 17, it is desirable to use one that causes upstream and downstream movement, such as a propeller type or a tilted fan turbine type. In addition, the number of installation stages of stirring blades is 1.
It is common to have ~4 stages. Vertical mixing tank 18
The slurry (mixed liquid) that has been sufficiently mixed with heavy oil in advance and reached the first stage of the granulation mechanism (the state immediately before the power consumption or slurry viscosity increases rapidly) is
It is sent to the next horizontal granulator 23, and as the stirring blades 21 rotate within this horizontal granulator 23, granulation occurs under rolling action and shearing action.
As the stirring blades 21 of the horizontal granulator 23, it is preferable to use one that generates a radial flow or a rotational flow, such as a tilted fan turbine (angle of inclination 0 to 45 degrees). It is necessary to create a flow in the direction of. The pellets formed in the horizontal granulator 23 are withdrawn from the outlet 22 together with waste water and separated into pellets and waste water containing ash by a simple solid-liquid separator 24, for example a vibrating screen. In the device shown in FIG.
The ratio between the height H and the inner diameter _D1 of the vertical mixing tank 18, H/
D ₁ is about 1 to 3, the ratio of the width d ₁ of the stirring blade 17 to D ₁ ,
d ₁ /D ₁ is about 0.4 to 0.8, and the distance h ₁ between the bottom of the mixing tank 18 and the center of the lowest stirring blade is about 0.3d ₁ to 1.5d ₁ .
The interval _h2 of the stirring blades 17 is about _0.5d1 to _3d1 , and the ratio of the length L of the horizontal granulator ₂₃ to the inner diameter D2, L/ _D2 is about 3 to 3d1.
Approximately 10, ratio of width d ₂ of stirring blade 21 to D ₂ , d ₂ /D ₂
0.6 to 0.9, stirring blade 21 tip speed to 1.5 to 9.0
It is desirable that the interval h ₃ of the stirring blades 21 be approximately 0.5d ₂ to 3d ₂ . In addition, the baffle plate 25 of the vertical mixing tank has a perfect baffle condition (W/D ₁ ) ^1.2 nb=0.35
(nb: number of installed plates, w: width of baffle plate). The device shown in FIG. 6 is a first stage vertical mixing tank 18.
7, the heavy oil/granulation accelerator supply pipe 33 is connected to the horizontal granulator 23. The granulator 23 may also be configured to add heavy oil and granulation accelerator in portions. In this case, adding the heavy oil and the granulation accelerator in portions has the advantage that granulation and deashing are promoted. Other configurations and operations are similar to those of the device shown in FIG. FIG. 8 shows yet another embodiment of the device of the invention. This device has a vertical mixing tank 18 in the first stage.
A gas supply pipe 34 for blowing a gas such as air or nitrogen is connected to the lower part of the coal granulator to further shorten the coal granulation time. Stirring of coal/water slurry, heavy oil and granulation accelerator,
It is believed that when a gas such as air or nitrogen is blown during mixing, air bubbles adhere to the coal particles, making it easier for oil to be adsorbed, thereby shortening the granulation time. Note that the heavy oil/granulation accelerator supply pipe 33 of the horizontal granulator 23 may not be provided. Other configurations and operations are similar to those of the device shown in FIG. Next, an example of an experiment conducted by the present inventors will be shown. Experimental Example This experimental example was conducted using the apparatus shown in FIG.
Coal/water slurry with a coal concentration of 44% by weight using Blairsall coal with a particle size of 1 mm or less at 10/min (12.2 Kg/min)
In addition to feeding the vertical mixing tank at a ratio of
(OH) ₂ at 1g/min (equivalent to 0.2% by weight of coal)
The pH was adjusted to 8.0, and 644 g/min (viscosity 137.3 centistokes at 50°C, specific gravity (15/4°C) 0.9515) of Middle East C heavy oil (viscosity 137.3 centistokes at 50°C) was added (12
weight% equivalent) and 5.4 g/min of sodium dioctyl sulfosuccinate (equivalent to coal) as a granulation accelerator.
(equivalent to 0.1% by weight) and the rotation speed of the stirring blade
Mixing was carried out by stirring at 200 rpm and residence time of 15 minutes. The properties of Blairsall coal were as shown in Table 2.

〔Effect of the invention〕

As explained above, the coal granulation apparatus of the present invention coats the surface of coal particles with heavy oil and a granulation accelerator by stirring action in the first stage mixing tank, and rolling action in the second stage granulator. Granulation is carried out by use and shearing action 2
Since it is configured to perform a stage process, the residence time can be significantly shortened compared to a granulation process with only one stage, and the power consumption can be significantly reduced. It has the effect of being able to recover lime with high dewatering efficiency, and also being able to separate and remove a portion of the ash contained in lime.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an example of the coal granulation device of the present invention, FIG. 2 is a curve diagram showing the relationship between power consumption and time when batch granulation is performed in one tank, and FIG. Explanatory diagrams showing the relationship between power consumption and time in the case of continuous granulation in one tank, Figures 4 and 5 show the case where the two-stage granulation system of the present invention is used. Figure 4 is an explanatory diagram showing the relationship between power consumption and time in a mixing tank, Figure 5 is an explanatory diagram showing the relationship between power consumption and time in a granulator, and Figure 6 is an explanatory diagram showing the relationship between power consumption and time in a granulator. 2 connected horizontal granulators
Explanatory diagram showing an example of a stage type granulation device, No. 7
The figure shows another embodiment of the two-stage granulation device of the present invention, and is an explanatory diagram showing the case where heavy oil/granulation accelerator supply pipes are connected to the horizontal granulator. It is an explanatory view showing still another example, and showing a case where a gas supply pipe is connected to a vertical mixing tank. 1... Mixing tank, 2... Stirring blade, 3... Coal/water slurry supply pipe, 4... Heavy oil supply pipe, 5... Granulation accelerator supply pipe, 7... Mixed liquid extraction pump, 8... …
Stirring blade, 10... Granulator, 12... Solid-liquid separator,
13... Pellet extraction line, 15... Coal/water slurry supply pipe, 16... Heavy oil/granulation accelerator supply pipe, 17... Stirring blade, 18... Vertical mixing tank, 20
... Mixed liquid extraction pump, 21 ... Stirring blade, 22 ...
...Produced pellet/wastewater outlet, 23...Horizontal granulator, 24...Solid-liquid separator, 25...Baffle plate, 27
...Mixed liquid inlet, 28...Pellet extraction line,
33... Heavy oil/granulation accelerator supply pipe, 34... Gas supply pipe.

Claims (1)

[Scope of Claims] 1. A vertical mixing tank to which a coal/water slurry supply pipe and a heavy oil/granulation accelerator supply pipe are connected, and which has stirring blades inside, and a mixed liquid drawn out at the bottom of the vertical mixing tank. A horizontal granulator that is connected at one end via a pump, has a stirring blade inside, and has a pellet/waste water outlet at the other end;
A coal granulation device comprising: a solid-liquid separator connected to a wastewater outlet. 2. A vertical mixing tank to which a coal/water slurry supply pipe and a heavy oil/granulation accelerator supply pipe are connected, and which has stirring blades inside, and one end of the vertical mixing tank is connected to the bottom of the vertical mixing tank via a mixed liquid extraction pump. A horizontal granulator is connected to the horizontal granulator, which has a stirring blade inside and an outlet for produced pellets and waste water at the other end, and a solid-liquid separator connected to the outlet for produced pellets and waste water of this horizontal granulator. A coal granulation apparatus characterized in that a gas supply pipe is connected to the lower part of the vertical mixing tank.