JP2018169199A - Evaluation method of coal degradation - Google Patents

Abstract

To provide a method to easily evaluate degradation characteristics during bulk transportation of coal without a large scale facility.SOLUTION: This degradation evaluation method has a volume breaking step of volumetrically breaking coal and a surface breaking step of breaking the surface of fallen coal. In the volume breaking step, 0.5-5 kg of the coal is placed in a cloth bag and fallen from a height of 8-10 m. In the surface breaking step, the fallen coal is charged into a rotary machine of φ300 mm or more and rotated 500-1000 times at 30-50 rpm.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a coal pulverization evaluation method, and more particularly, to a coal pulverization evaluation method that can easily evaluate coal pulverization characteristics without requiring a large-scale facility.

  In general, reformed coal obtained by molding lignite etc. is bulk transported (loading and unloading to ships, transporting by vehicle, horizontal holding in a storage yard) with existing coal infrastructure facilities, and to the target landing site Shipped. During bulk transportation, it is expected that the product will be powdered by impact such as dropping or rubbing.

  Therefore, the product to be shipped is required to have sufficient pulverization characteristics to withstand bulk transportation. In addition, as what evaluates the pulverization characteristic of coal, there exists a JISZ8841 granulated material-strength test method. In addition, in patent document 1, it evaluates with the method of sieving after a rotation test.

JP 2014-19746

  By the way, when it is going to evaluate the pulverization characteristic in the bulk transport of coal, conventionally, evaluation with a large-scale installation is required and complicated as described later with reference to the drawings. Moreover, the evaluation method of patent document 1 does not assume the powdering at the time of bulk transport, and does not evaluate powdering at the time of bulk transport appropriately.

  Therefore, an object of the present invention is to provide a coal pulverization evaluation method that can easily evaluate pulverization characteristics during bulk transportation of coal without requiring a large-scale facility.

The powder evaluation method of one form of the present invention for solving the above problems is as follows:
A volume destruction process for destroying the volume of coal;
A method for evaluating the pulverization characteristics of coal, the method comprising: a surface breaking step of breaking the surface of the dropped coal,
In the volume destruction step, 0.5-5 kg of the coal is put into a cloth bag and dropped from a height of 8-10 m,
In the surface breaking step, the dropped coal is charged into a rotating machine having a diameter of 300 mm or more and 1400 mm or less and rotated at 500 rpm to 1000 rpm at 30 to 50 rpm.

  ADVANTAGE OF THE INVENTION According to this invention, the coal pulverization evaluation method which can evaluate the pulverization characteristic of coal simply without requiring a large-scale installation can be provided.

It is a flowchart of the pulverization evaluation method concerning one form of the present invention. It is a graph which shows the result of having implemented the pulverization evaluation method concerning one form of the present invention. It is a figure which shows the shape of a bag typically, (a) is an empty state, (b) shows the state which put the sample. It is a figure which shows typically the structure of the rotation part of a rotation testing machine, (a) is a front view, (b) is a perspective view. It is a figure which shows typically the structure of a large-scale handling equipment. It is a graph which shows the result of the pulverization evaluation method using the installation of FIG.

(1. Evaluation method for pulverization in handling equipment)
An example of the handling equipment is schematically shown in FIG. The handling facility 1 includes, for example, a receiving hopper 11, a belt conveyor 12, a hopper 13, an extraction belt conveyor 15, a biaxial paddle mixer 17, and belt conveyors 18 to 20. When handling equipment 1 supplies a sample of coal to receiving hopper 11, it is conveyed to hopper 13 by belt conveyor 12, and then hopper 13, belt conveyor 15, biaxial paddle mixer 17, belt conveyors 18 to 20, belt conveyor. The sample is circulated in the order of twelve.

  Chute 20-1 to 20-3 are provided at the connecting portion of the belt conveyors 18 and 19, the connecting portion of the belt conveyors 19 and 20, and the connecting portion of the belt conveyors 20 and 12, respectively, and the coal falls through this chute. It is supposed to be. The coal pulverization characteristics are evaluated using such handling equipment 1.

(Reference Example 1)
The pulverization evaluation of Reference Example 1 is performed by the following procedure as an example.
(I) First, the formed coal is supplied to the circulation path of the handling facility 1 and is circulated and conveyed for a predetermined time. (Ii) Thereafter, a sample is taken and the particle size distribution is measured. The degree of pulverization due to the circulation time is not limited, but the evaluation is based on a mass passing through a 2 mm sieve.

The handling capacity of the handling facility 1 is 50 t / h as an example. The coal to be circulated is, for example, Indonesian subbituminous coal A. The sample amount is 2 m ^{3 as} an example. Table 1 shows the particle size distribution of the molded coal in Reference Example 1 (before the pulverization evaluation test and after the evaluation test in the handling facility 1).

(Reference Example 2)
In the evaluation method of Reference Example 2, the test was performed with the same apparatus and conditions as in Reference Example 1 except that the sample was changed to modified coal. The reformed coal is obtained by crushing and compression-molding B coal, Indonesian lignite. Table 2 shows the particle size distribution of the modified coal in Reference Example 2 (before the pulverization evaluation test and after the evaluation test in the handling facility 1).

(result)
The results of Reference Examples 1 and 2 are shown in FIG. Moreover, in the graph of FIG. 6, a horizontal axis | shaft is the circulation time (min) in the handling equipment 1, and a vertical axis | shaft is 2 mm sieve passage mass percentage (mass%).

  Both the coal and the reformed coal are crushed by the impact during handling as the circulation time becomes longer. Naturally, the fine powder (mass percentage passing through the 2 mm sieve) increases, but the reformed coal (Reference Example 2) is coal. There is less fine powder than (Reference Example 1). From this result, it can be seen that the reformed coal is less pulverized than the coal. Moreover, it turns out that progress of pulverization stops in about 50 minutes after circulation also in any sample of the reference examples 1 and 2.

  From this, it was found that if processing was performed for 50 minutes with the same equipment, the limit of pulverization during bulk transport of the modified coal could be confirmed.

(2. Evaluation method according to this embodiment)
The pulverization characteristics of coal is an important quality evaluation item, but it is difficult to use a large-scale testing machine as shown in Fig. 5 in the development stage of reformed coal from the viewpoint of securing a sample amount. There are many people and heavy equipment for evaluation. In order to quickly optimize the production method of modified coal and the like, it is desirable to evaluate the pulverization characteristics of a plurality of samples simply and in a short time with a minimum amount of samples.

  Therefore, the present inventors examined an evaluation method capable of reproducing the results obtained with a handling test apparatus (circulation treatment for 50 minutes) as shown in FIG. 5 on a small sample / laboratory scale. Specifically, it is considered that volume destruction and surface destruction are performed in combination for coal or modified coal during bulk transportation, and surface destruction after dropping from a high place to give volume destruction. It was decided to reduce the scale and simplification of the evaluation equipment and procedure by performing the rotation process to give As a result of various studies, it has been found that the following evaluation method is useful. The evaluation method according to the present embodiment has two processes, a volume destruction process (step S1) and a surface destruction process (step S2) (see also FIG. 1).

  Step S1 is a volume destruction process. In this step, a sample of coal or modified coal is placed in a bag and dropped from a predetermined height. The bag is made of cloth as an example. The amount put in the bag is, for example, 0.5 kg or more and 5.0 kg or less. The “predetermined height” is, for example, 8 m or more and 10 m or less. The number of times of dropping is, for example, 5 times or more and 25 times or less. Any material can be used for the bag, but it is preferable that the fabric is thin enough to prevent a drop impact from being transmitted to the contents, and is sufficiently strong so as not to break. Moreover, what is lightweight is also preferable.

  Step S2 is a surface destruction process. In this step, the sample dropped in the above step is put in a predetermined rotation testing machine and rotated at a predetermined rotation speed by a predetermined number of rotations. The apparatus used for the surface destruction process is not limited to a rotary testing machine, and any apparatus can be used as long as it can provide surface destruction.

  As the predetermined rotation tester, for example, a rotating unit having an inner diameter of 300 mm or more may be used. The predetermined rotation speed is, for example, 30 rpm or more and 50 rpm. The predetermined number of rotations is, for example, 500 rotations or more and 1000 rotations or less. A configuration example of the testing machine will be described later with reference to other drawings.

  The pulverization evaluation method according to one embodiment of the present invention was performed under the following specific conditions.

  As Step S1, 1 kg of a sample of coal (Example 1) or modified coal (Example 2) was dropped 20 times from a height of 8.6 m. In addition, since it is necessary to collect the entire sample after dropping, the sample was packed in a cloth bag and dropped together with the bag. In dropping, the cloth bag containing the sample was dropped by gravity and collided with the ground concrete surface.

The bag used for the drop test is shown in FIG. The shape of the bag 41 is as follows.
-Material: PE woven fabric (used as a flexible container bag. Breathable.)
・ Shape: Cylindrical shape with flat bottom diameter of φ500mm and height (depth) of 500mm ・ Capacity (before packing, as cylinder): 79.5 liters

  Regarding the filling of the sample into the bag, 1 kg was filled per bag. A sample was put in an empty bag (having a string at the upper end opening) as shown in FIG. 3 (a), and the bag was closed in a form as shown in FIG. 3 (b).

  The filling amount (volume) of 1 kg of the sample is 1.1 to 2.0 liters when the bulk density is 0.5 to 0.9 kg / liter. The filling rate of the sample is therefore in the range of 1.4 to 2.5% (“ab” indicates a to b). Note that in one embodiment of the present invention, the filling rate may be in the range of 1.0 to 10%.

  As step S2, processing was performed for 10 minutes with the rotation tester (40 rpm) after that. The rotational strength was measured using the rotational strength tester specified in the JISZ8841 granulated product-strength test method. However, in order to increase the impact force, two lifters with a height of 60 mm were placed inside (positions at 0 ° and 180 °). ) Was used.

  Specifically, the rotational strength tester has a rotating part as schematically shown in the front view of FIG. 4A and the perspective view of FIG. The rotating part has a cylindrical member 45 that rotates by putting a sample therein. The cylindrical member 45 has an inner diameter of 350 mm and an inner axial length of 175 mm. Lifters 45 a and 45 a having a height of 60 mm were installed at two locations (positions of 0 ° and 180 °) inside the cylindrical member 45. In the JIS standard, the height of the lifter is 10 mm. The lifter 45a is a flat plate-like member, and is arranged so as to extend in the radial direction as shown in FIG. 4A. More specifically, the lifter 45a extends from the inner peripheral surface toward the center side. Further, as shown in FIG. 4B, the lifter 45 a is formed to be 175 mm like the cylindrical member 45. The thickness of the lifter 45a is 10 mm in this example.

  FIG. 2 is a plot of the ratio (mass%) of those passing through a 2 mm sieve after the processing of steps S1 and S2. Reference examples 1 and 2 are also shown for comparison. The sample of Example 1 is A coal used in Reference Example 1, and the sample of Example 2 is modified coal of B coal used in Reference Example 2. Table 1 shows the particle size distribution of the sample in Example 1, and Table 2 shows the particle size distribution of the sample in Example 2.

  In FIG. 2, the evaluation conditions of Examples 1 and 2 (dropping 20 times from a height of 8.6 m and rotating at 40 rpm for 20 minutes) are the same as the evaluation conditions of Reference Examples 1 and 2 (circulation time 50 minutes in handling equipment 1). ) And described as equivalent. Therefore, the horizontal axis in FIG. 2 is the same as that in FIG. 6 (circulation time in the handling facility 1). In FIG. 6, both Examples 1 and 2 show the same behavior as Reference Examples 1 and 2.

  From the above, the pulverization characteristics during the bulk transportation of the modified coal could be evaluated by the laboratory test method corresponding to the impact for 50 minutes in the handling test (20 turns of falling 8.6 m, 20 minutes of rotation at 40 rpm). In addition, the sample amount necessary for evaluation could be reduced to 1 kg.

(Appendix)
This application discloses the following inventions:
1. A volume destruction process for destroying the volume of coal;
A method for evaluating the pulverization characteristics of coal, the method comprising: a surface breaking step of breaking the surface of the dropped coal,
In the volume destruction step, 0.5-5 kg of the coal is put into a cloth bag and dropped from a height of 8-10 m,
In the surface destruction step, the dropped coal is charged into a rotating machine having a diameter of 300 mm or more and rotated at 500 rpm to 1000 rpm at 30 to 50 rpm.

  According to such a method, the following effects can be obtained. In other words, a certain amount of coal is pulverized during handling, but by performing the above test, the amount of pulverization until mining, shipping, transportation, landing, transportation, etc. is used at a power plant, etc. is highly accurate. It is possible to estimate and evaluate the powdering characteristics. In particular, since it is not necessary to use a large-scale facility as shown in FIG. 5, the powdering characteristics can be easily evaluated.

2. In the above pulverization property evaluation method, the height in the volume breaking step is 8.6 m. Specifically, the present invention can be implemented by dropping from such a height.

3. In the surface destruction step, a rotating machine having a diameter of 350 mm is used and the method is performed by rotating 800 times at 40 rpm. Specifically, the present invention can be implemented by performing such a rotation test.

  4). The method for evaluating coal pulverization characteristics as described above, wherein the coal is modified coal. According to this method, it is possible to evaluate the pulverization characteristics of the modified coal using the above method.

41 bag 45 cylindrical member 45a lifter

Claims (4)

A volume destruction process for destroying the volume of coal;
A method for evaluating the pulverization characteristics of coal, the method comprising: a surface breaking step of breaking the surface of the dropped coal,
In the volume destruction step, 0.5-5 kg of the coal is put into a cloth bag and dropped from a height of 8-10 m,
In the surface breaking step, the dropped coal is charged into a rotating machine having a diameter of 300 mm or more and 1400 mm or less and rotated at 500 rpm to 1000 rpm at 30 to 50 rpm. In the coal pulverization characteristic evaluation method according to claim 1,
The height in the said volume destruction process is 8.6 m. The coal pulverization characteristic evaluation method characterized by the above-mentioned. In the coal pulverization characteristic evaluation method according to claim 1 or 2,
In the surface destruction step, a pulverizing characteristic evaluation method for coal, wherein a rotating machine with a diameter of 350 mm is used and the rotating speed is 800 rpm at 40 rpm. In the coal pulverization characteristic evaluation method according to any one of claims 1 to 3,
The method for evaluating coal pulverization characteristics, wherein the coal is modified coal.