JPS5974189A - Stabilization of coal - Google Patents

Abstract

PURPOSE:To reduce the activity of a low-grade coal and prevent its spontaneous ignition, by heating the coal to a specified temperature to reduce the water content and then subjecting it to an oxidation treatment. CONSTITUTION:Coal, mainly low-grade coal such as peat, brown coal or sub- bituminous coal, is heated at 100-350 deg.C until its water content is reduced substantially to 0% and is then subjected to an oxidation treatment. For example, the water content of the coal is lowered to 15-20wt% by drying in the sun, etc. and the oxidation treatment is performed for 10min-3hr in an inert gas such as nitrogen gas. When necessary, the coal after the heat treatment is formed into shape under heat and pressure and is oxidized at 10-200 deg.C for 30min-5hr with oxygen in the concentration of 1-21vol.%. The method produces coal for fuel with excellent resistance to spontaneous ignition and a high calorific value.

Description

[Detailed Description of the Invention] The present invention relates to a method for stabilizing coal, and more specifically, to reduce the moisture content of low-grade coal such as peat, lignite, and subliminal coal, and to reduce its activity to prevent spontaneous combustion. Concerning methods for stabilizing coal.

Low-grade coal such as lignite has a high moisture content, which makes it uneconomical to transport.It is also highly active and tends to spontaneously ignite during transportation and storage. tl is limited to the vicinity.

In view of these circumstances, research has been conducted on dehydration of these low-rank coals and prevention of spontaneous combustion, and various proposals have been made. For example, as a certified copying method, ■evaporation method, ■mechanical dehydration method, etc. are known, and as a spontaneous combustion prevention method, ■air blocking method (underwater coal storage 2 coal surface coating, coal storage surface coating, compressed coal storage, inert coal storage, etc.) is known. gas seal, etc.),
■Cooling method, ■Removal of pulverized coal, ■Z-briquetting, etc.
One measure is being taken.

However, these methods were not always satisfactory because sufficient effects were not obtained or the operations were complicated.

An object of the present invention is to provide a coal stabilization method that simultaneously dehydrates low-rank coal and prevents spontaneous combustion using relatively simple operations.

In the present invention, 1 coal is heated to 100% until the water content becomes substantially G%.
This is a method for stabilizing coal, which is characterized by heat treatment for 7 Jll at a temperature of ~550°C and then oxidation treatment.

Among coals, peat is the most likely to spontaneously ignite;
It is known that the order is submersible, double charcoal, and bituminous. Low-grade coal such as ma/ζ, peat, lignite, and sub-bituminous coal has a high moisture content and has poor transportation efficiency.

Therefore, the present invention is intended primarily to stabilize kneaded low-rank coal.

In putting the present invention into practice, coal is dried in advance in the sun.
It is desirable to reduce the moisture content to 15-20% by drying.

Coal heating treatment β (1 is carried out at a temperature of 100 to 350"C, preferably in an inert gas such as V hydrogen gas,
This progresses until the moisture content becomes substantially 0%. Processing time: 1. Decide by taking into account the type of coal bucket, power 11, heat temperature, etc., or carry out the treatment for 10 minutes to 5 hours. This heat treatment removes water vapor and combustible gases, improving its spontaneous ignition resistance compared to raw coal. However, if the heat treatment temperature exceeds 550"C, the temperature at which carbon dioxide gas is generated becomes low, and the oxygen The amount of absorption increases, and sufficient effects cannot be obtained.

After the heat treatment, the coal is shaped if desired.

Forming can be done by simply heating and compressing the heat-treated coal.
If necessary, wet tar, pitch, etc. can be used as a binder.

The next oxidation treatment is aimed at improving the spontaneous ignition resistance of the coal, and is usually carried out under heating, especially at 10%
Excellent effects are obtained when carried out at temperatures between 0 and 200°C. Oxidation treatment I-L oxygen concentration) Volume % or more, usually 1 to 2
It is carried out at 1% by volume, preferably 4 to 1% by volume, for 5 minutes to 5 hours, preferably 2 to 5 hours. The oxidation treatment can be carried out using air, but preferably a mixed gas containing oxygen and nitrogen in a predetermined ratio is used.

The moisture content of the coal to which the method of the present invention has been applied has been significantly reduced.
Furthermore, it has superior spontaneous ignition resistance compared to raw coal and Australian briquettes. In addition, when used as a solvent, it has a high calorific value and has properties suitable as charcoal for melting.

Next, examples of the present invention will be shown.

Examples 1 to 5 Air-dried Yarun lignite (pulverized to a particle size of 50 or less)
Charge 2 and 9 into a packed tower and add 2 t/h of preheated nitrogen gas.
The lignite was dried by flowing it through a packed tower at rnin, and after reaching a predetermined temperature, it was heat-treated for 3 hours. Thereafter, the brown coal was cooled to room temperature and was taken out and stored in an airtight container.

The heat-treated lignite 2001 was charged into a packed tower, and a mixed gas of nitrogen and oxygen with an oxygen concentration adjusted to 6 container % was preheated and passed through the packed tower at 500 mA'/win, after reaching a predetermined temperature. Then, oxidation treatment was performed for 6 hours.

Thereafter, the temperature was lowered to room temperature, and nine pieces of lignite were taken out and stored in a sealed container.

The above lignite is crushed and classified into two categories: particle size O15-05 and particle % 70.15wn or less.
The spontaneous ignition resistance was evaluated by measuring the O2 gas generation temperature and the amount of oxygen absorbed. We also measured the elemental analysis value, industrial analysis value, and calorific value of the latter. The results are shown in Tables 1 and 2.
Shown in the table.

Comparative Examples 1 to 5 Comparative Examples 1 to 5 were carried out in the same manner as Examples 1 to 5 except that the oxidation treatment was omitted. The results are shown in Tables 1 and 2.

Table 1 Table 2 Table 1 Raw coal dried under reduced pressure at 50°C - Example of values based on the moisture content of the arriving coal rather than the constant humidity moisture of 2J Engineering S In this example, the effect of oxidation treatment time I looked into it.

In other words, the heat treatment temperature is 200°C, the oxidation treatment temperature is 1
50°C The treatment was carried out in the same manner as in Example 1 except that the oxygen concentration was 6% by volume and the oxidation treatment time was changed. The results are shown in Table 3.

Table 6 Examples 11 to 15 In this example, in order to examine the influence of oxygen concentration during oxidation treatment, the heat treatment temperature was 600°C, the oxidation treatment temperature was 150°C, and the oxygen concentration was varied. was treated in the same manner as in Example 1. The results are shown in Table 4.

Table 4 Examples 16-20 In this example, regarding the influence of oxidation treatment temperature, Ml, l
Δ solid. That is, since the heat treatment temperature was set at 500°C, the oxygen concentration was kept at 6% by volume, and the oxidation treatment temperature was changed (
was treated in the same manner as in Example 1. The results are shown in Table 5.

Table 5 Comparative Examples 6 and 7 Raw coal (Yalun lignite) dried under pressure at 50°C (Comparative Example 6) and Xiangzhou Bu 1 Can) (Jt 4)
9 cases 7) and the particle size is 0. The CO2 gas generation temperature and oxygen absorption amount were measured for the +5 to [15M categories. The thread fruit is shown in Table 6.

Comparative Examples 8 and 9 The heat treatment temperature was 400°C, and the oxidation treatment j11 (
Example 1 and 1i-iJ were treated in the same manner as Example 1 (comparative example day), except that the heat treatment temperature was 400°.
The CQ2 gas generation temperature and the oxygen absorbing liquid were measured for a sample treated in the same manner as in Example 1 (Comparative Example 9) except that the C1 oxidation treatment temperature was 150°C. The results are shown in Table 6.

Patent applicant: Idemitsu Kosan Co., Ltd. (,A9-

Claims (4)

[Claims] (1) Boil the coal until the moisture content becomes substantially 0%. A method for stabilizing coal, characterized by heat treatment at a temperature of ~550°C and then oxidation treatment. (2) The method according to claim 1, wherein the coal is low-rank coal. (3) The method according to claim 1, wherein the coal is lignite. (4) The method according to claim 1, wherein the oxidation treatment is performed at a temperature of +on to 200°C and an oxygen concentration of 1 to 21%.