阅读说明：本技术 改性煤的制造方法 (Method for producing modified coal ) 是由 今村彰伸 小菅克志 小水流广行 谷奥亘 于 2018-10-16 设计创作，主要内容包括：提供一种改性煤的制造方法,其具有：于300～650℃对煤进行干馏而得到干馏煤的干馏工序；以及,以大于200℃且为240℃以下的温度范围对干馏煤进行10～60分钟氧化处理的氧化处理工序。(Provided is a method for producing modified coal, which comprises: a carbonization step of carbonizing coal at 300 to 650 ℃ to obtain carbonized coal; and an oxidation treatment step of subjecting the carbonized coal to oxidation treatment at a temperature of more than 200 ℃ and 240 ℃ or less for 10 to 60 minutes.)

1. A method for producing modified coal, comprising:

a carbonization step of carbonizing coal at 300 to 650 ℃ to obtain carbonized coal; and the number of the first and second groups,

and an oxidation treatment step of subjecting the carbonized coal to oxidation treatment at a temperature of more than 200 ℃ and 240 ℃ or less for 10 to 60 minutes.

2. The method for producing modified coal according to claim 1, comprising a drying step of drying coal at 150 ℃ or lower before the carbonization step,

in the dry distillation step, the coal dried in the drying step is dry distilled.

3. The method for producing modified coal according to claim 1 or 2, wherein the moisture content of the coal is 50% by mass or more.

4. The method for producing modified coal according to any one of claims 1 to 3, wherein the volatile matter content of the carbonized coal obtained in the carbonization step is 10 to 30% by mass.

5. The method for producing modified coal according to any one of claims 1 to 4, wherein the volatile matter content of the modified coal obtained in the oxidation treatment step is 5 to 30% by mass.

6. The method for producing modified coal according to any one of claims 1 to 5, comprising a combustion step of combusting a gas containing volatile components generated by carbonization of the coal in a combustion furnace,

in the oxidation treatment step, the carbonized coal is subjected to oxidation treatment using oxygen-containing exhaust gas from the combustion furnace.

Technical Field

The present invention relates to a method for producing modified coal.

Background

In order to modify low-quality coal such as lignite or subbituminous coal, a technique of drying and carbonizing the low-quality coal is known. However, it is known that when coal is modified by this technique, the surface thereof is activated and spontaneously ignited by the heat of reaction with oxygen in the air. As a technique for preventing spontaneous combustion, there has been proposed a technique for deactivating coal at a temperature in the range of 40 to 95 ℃ using a treatment gas containing oxygen (see patent document 1).

Disclosure of Invention

Problems to be solved by the invention

It is considered that the carbonized coal can be deactivated to some extent by performing the conventional deactivation treatment as described in patent document 1. However, according to the studies of the present inventors, it has been found that the spontaneous combustibility cannot be sufficiently reduced even by performing the conventional deactivation treatment. On the other hand, if the deactivation treatment is excessively performed to reduce the spontaneous combustibility, the volatile matter is reduced, and the fuel cannot be effectively used. Accordingly, an object of the present invention is to provide a method for producing a modified coal, which can produce a modified coal having a sufficiently suppressed spontaneous combustibility at a high yield.

Means for solving the problems

The present invention provides a method for producing modified coal, comprising: a carbonization step of carbonizing coal at 300 to 650 ℃ to obtain carbonized coal; and an oxidation treatment step of subjecting the carbonized coal to oxidation treatment at a temperature of more than 200 ℃ and 240 ℃ or less for 10 to 60 minutes.

The method comprises oxidizing raw material coal at a temperature of more than 200 ℃ and less than 240 ℃ for 10 to 60 minutes. When the oxidation treatment is performed under such conditions, it is considered that the self-heat property is reduced and the self-combustion property is suppressed because the surface components of the raw material coal are oxidized and the surface state is stabilized. Further, the disappearance by spontaneous combustion can be suppressed, and the yield can be improved.

The above production method has a carbonization step of carbonizing coal to obtain carbonized coal before the oxidation treatment step. Dry distillation of coal is effective as a means for improving the quality of coal. Here, when coal is dry distilled at 650 ℃ or lower, the yield during dry distillation is improved, while spontaneous combustibility tends to be improved. In the above-described manufacturing method, the self-heating property can be reduced by the oxidation treatment step. Therefore, pyrophoricity can be suppressed even when the carbonization temperature in the carbonization step is 650 ℃ or lower. Therefore, it is possible to produce a modified coal having a high quality and sufficiently suppressed spontaneous combustibility at a high yield.

The above-mentioned production method may further comprise a drying step of drying the coal at 150 ℃ or lower before the oxidation treatment step. Since the moisture content of the coal can be reduced, a modified coal of higher quality can be obtained by the oxidation treatment step or the carbonization step and the oxidation treatment step.

The above production method may further include a combustion step of combusting a gas containing volatile components generated by carbonization of coal in a combustion furnace. In this case, in the oxidation treatment step, the carbonized coal is preferably subjected to oxidation treatment by using an oxygen-containing off gas from a combustion furnace. This can reduce the production cost of the modified coal and improve the efficiency and safety of the oxidation treatment.

ADVANTAGEOUS EFFECTS OF INVENTION

The present invention can provide a method for producing modified coal, which can produce modified coal having sufficiently suppressed spontaneous combustibility at a high yield.

Drawings

Fig. 1 is a flowchart showing an example of a method for producing modified coal.

FIG. 2 is a graph showing the results of the spontaneous combustibility evaluation tests of examples 1 and 2, reference examples 1 and 2, and comparative examples 1 to 4.

FIG. 3 is a graph showing the change with time in the calorific value of the carbonized coal in comparative examples 5 to 8 having different carbonization degrees.

FIG. 4 is a graph showing the change with time in the calorific values of the modified coals of example 3, reference example 4 and comparative examples 9 and 10 and the carbonized coal of comparative example 6, which have different oxidation treatment temperatures.

FIG. 5 is a graph showing the concentrations of carbon monoxide and carbon dioxide in the exhaust gas during the oxidation treatment in examples 5 and 6, reference example 7, and comparative examples 11 to 13.

Fig. 6 is a graph showing the results of infrared spectroscopic analysis of comparative example 6, comparative example 14, and comparative example 15.

FIG. 7 is a graph showing the results of thermogravimetric analysis of comparative examples 16 to 19, examples 8 and 9, and reference example 10, in which the oxidation treatment temperature was different.

FIG. 8 is a graph showing the results of differential thermal analysis of comparative examples 16 to 19, examples 8 and 9, and reference example 10, in which the oxidation treatment temperature was different.

FIG. 9 is a graph showing the relationship between the oxidation treatment temperature and the height of the maximum peak in the results of differential thermal analysis of comparative examples 16 to 19, examples 8 and 9, and reference example 10, in which the oxidation treatment temperatures are different.

Fig. 10 is a graph showing the results of the spontaneous combustibility evaluation test.

Detailed Description

Embodiments of the present invention will be described below with reference to the drawings. However, the following embodiments are examples for illustrating the present invention, and the present invention is not intended to be limited to the following.

The method for producing modified coal of the present embodiment includes: a carbonization step of carbonizing coal at 300 to 650 ℃ to obtain carbonized coal; and an oxidation treatment step of oxidizing the carbonized coal at a temperature in a range of more than 200 ℃ and 240 ℃ or less. Generally, there is a tendency for retorted coal to be more pyrophoric than dried coal of coal. In the present embodiment, the carbonized coal having a different surface state from the coal and the dried coal thereof can be subjected to an oxidation treatment step under predetermined conditions, whereby a modified coal having sufficiently suppressed spontaneous combustibility can be obtained from the carbonized coal.

The carbonization step is a step of carbonizing the coal at 300 to 650 ℃ to obtain carbonized coal. The carbonization step may be performed without performing a drying step described later. At this time, the moisture content of the coal decreases in the initial stage of the carbonization step. The dry distillation step is preferably carried out at a temperature of 300 to 600 ℃. Thereby, the coal can be sufficiently carbonized and the high yield can be maintained. The carbonization step can be performed by using a general carbonization furnace such as a vertical blast furnace, a coke oven, or a tunnel kiln.

The Volatile Matter (VM) of the carbonized coal obtained in the carbonization step is preferably 10 to 30 mass%. The carbonized coal generally has high spontaneous combustibility, but in the present embodiment, spontaneous combustibility can be suppressed by performing the oxidation treatment step after the carbonization step. Therefore, high yield can be achieved.

The coal may comprise low quality coal or high quality coal. When low-quality coal is contained, a drying step described later is preferably performed before the oxidation treatment step. However, the drying step is not necessarily required. The particle size of the raw coal may be, for example, 50mm or less, 30mm or less, or 10mm or less.

In the oxidation treatment step, the surface of the carbonized coal can be sufficiently modified by setting the temperature at which the carbonization treatment of the carbonized coal is performed (oxidation treatment temperature) to a range of more than 200 ℃. By setting the oxidation treatment temperature to 240 ℃ or lower, the reduction of volatile components in the oxidation treatment step can be suppressed, and the modified coal can be produced with a high yield.

The oxidation treatment temperature is preferably 210 to 240 ℃, and more preferably 220 to 240 ℃ from the viewpoint of achieving both suppression of spontaneous combustibility and improvement of yield at a higher level. The oxidation treatment step may not be performed at a fixed oxidation treatment temperature, and the oxidation treatment temperature may be varied within the above range. The time for the oxidation treatment step is 10 to 60 minutes from the viewpoint of producing the modified coal at a high yield. The time for the oxidation treatment step may be 15 to 60 minutes from the viewpoint of sufficiently suppressing spontaneous combustibility.

The atmosphere in the oxidation treatment step is not particularly limited as long as it is an atmosphere containing oxygen, and may be air or a mixed atmosphere of an inert gas such as nitrogen and oxygen. Further, the exhaust gas may be an exhaust gas from a combustion furnace. The oxygen concentration may be, for example, 2 to 13 vol%, or 3 to 10 vol%, from the viewpoint of safety and efficiency of oxidation treatment. The "volume%" is a volume fraction under the conditions of the standard state (25 ℃, 100 kPa).

In the oxidation treatment step, the functional groups on the surface of the raw material coal are oxidized. Thus, a modified coal in which the spontaneous heat caused by oxidation is reduced and the spontaneous combustion is sufficiently suppressed can be produced. From the viewpoint of improving the usefulness as a fuel, the Volatile Matter (VM) of the modified coal may be 5 mass% or more, or may be 10 mass% or more. On the other hand, from the viewpoint of further reducing the spontaneous combustibility, the Volatile Matter (VM) of the modified coal may be 30% by mass or less, or may be 25% by mass or less. In the present specification, the volatile component is a volatile component based on JIS M8812: value of dry basis measured by "Square electric furnace method" of 2006.

According to the production method of the present embodiment, the modified coal having sufficiently suppressed spontaneous combustibility can be produced at a high yield. The modified coal may also contain volatile components to some extent and thus can be effectively used as a fuel. It is clear that the coal can be safely stored in the open air and safely transported on land or on the sea from a coal production site, while having high usefulness as a fuel.

The method for producing modified coal according to another embodiment includes a drying step of drying coal at 150 ℃ or lower before the carbonization step. When low-quality coal having a high moisture content (for example, lignite or subbituminous coal having a moisture content of 50 mass% or more) is used, it is preferable to have a drying step as in the present embodiment.

In the drying step, the coal is heated to a temperature in the range of, for example, 40 to 150 ℃ to be dried. The drying step may be performed in air or in an inert gas atmosphere. Alternatively, the reaction may be carried out in the exhaust gas of a combustion furnace. In the drying step, the moisture content of the coal is reduced to, for example, 20 mass% or less. By performing this drying step, the modification effect by the dry distillation or oxidation treatment can be sufficiently obtained.

The drying step may be performed using a general electric furnace or the like, or may be performed using an indirect heater or an air fluidized bed dryer. The time of the drying step is not particularly limited, and may be adjusted according to the moisture content of the coal, the particle size of the coal, and the like.

According to the production method of the present embodiment, even when low-quality coal is used, modified coal having sufficiently suppressed spontaneous combustibility can be produced at a high yield. The particle diameter of the modified coal may be, for example, 50mm or less, or 10mm or less.

The modified coal obtained by the above-mentioned production method may be classified into modified coal in a granular form (for example, particles having a particle diameter of 3mm or more) and modified coal in a powdery form (for example, powder having a particle diameter of less than 3 mm). The pulverized modified coal (powder) obtained by classification may be formed with or without a binder, and mixed with granular modified coal (particles) obtained by classification as well. By increasing the average particle size of the reformed coal in this manner, the generation of dust during transportation and storage of the coal can be further reduced, and the operability of the reformed coal can be further improved.

Fig. 1 is a diagram showing an example of an apparatus configuration for carrying out the method for producing reformed coal according to the embodiment. In the example of fig. 1, the drying step is performed in the drying device 10, the dry distillation step is performed in the dry distillation device 20, and the oxidation treatment step is performed in the oxidation treatment device 30. The volatile component-containing gas generated by the retort 20 is consumed as a fuel gas in the combustion furnace 40 (combustion step). The drying device 10 may be, for example, a general dryer. The oxidation treatment apparatus 30 may be, for example, a normal electric furnace.

The exhaust gas generated by burning the fuel gas containing volatile components in the combustion furnace 40 usually contains about 5 to 10 vol% of oxygen. By utilizing the exhaust gas in the oxidation treatment device 30, the efficiency and safety of the oxidation treatment in the oxidation treatment step can be sufficiently improved. In addition, since the temperature of the exhaust gas can be effectively utilized, energy can be reduced. The exhaust gas generated in the combustion furnace 40 may be used as a heating gas in the drying apparatus 10. By effectively utilizing the heat generated in the carbonization step in this manner, the production cost of the modified coal can be reduced.

While the present invention has been described with reference to the embodiments, the present invention is not limited to the embodiments.