JPH0231131A - Method of industrial analysis of coal and infrared heating oven - Google Patents

Abstract

PURPOSE:To heat a sample rapidly and uniformly the reflecting the infrared rays from an infrared heater by a reflecting surface formed from a rotary curved surface and irradiating the whole of a crucible with infrared rays. CONSTITUTION:Finely divided coal adjusted to a constant humidity state is received in a crucible 50 to be placed on a sample stand 62 and an upper oven body 10 is placed on a lower oven body 20. Next, the coal sample is heated by an infrared heater 30 to evaporate moisture and the wt. reduction quantity thereof regarded as the water of the sample is measured. Subsequently, the sample is heated in a nitrogen gas atmosphere in the same way and the temp. at this time is held to evaporate volatile components and the wt. reduction quantity regarded as the volatile components of the sample is measured. Next, the sample is returned to an oxygen gas atmosphere to keep the temp. and fixed carbon is burnt while the residual quantity is measured to be set to the ash of the sample. The fixed carbon of the sample is set to the remaining value obtained by subtracting water, the volatile component and ash from the original sample. The nitrogen and oxygen gases are supplied from a gas supply port 46 and discharged to the outside from the upper end 43 of upper protective glass.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an industrial analysis method for coal in which moisture, volatile content, and ash content are sequentially measured in the same sample. Regarding analysis methods.

The present invention also relates to an infrared heating furnace of a type in which infrared rays from an annular infrared heater are reflected on a rotating curved surface and irradiated onto a sample.

[Prior Art] An industrial analysis method for coal is specified in JIS M8812. According to this method, separate samples are prepared and measured for each component of moisture, volatile matter, and ash. Therefore, measuring one type of coal sample for each component takes approximately 6 hours at a time.

Therefore, in order to shorten the analysis time, a thermobalance was used to
A method (hereinafter referred to as the thermobalance method) for sequentially measuring all items of moisture, volatile matter, and ash in the same sample has been developed (Japanese Patent Application Laid-open No. 58-162840@ and Japanese Patent Application Laid-open No. 62-187239).
(see @).

In the thermobalance method described above, a resistance heating furnace and an infrared heating furnace may be used as the heating furnace. However, in a resistance heating furnace, it is not possible to increase the temperature of the sample at a very high rate, and it takes time to cool the furnace and take out the sample.

Therefore, in order to shorten the analysis time, it is preferable to use an infrared heating furnace. By the way, although it is not used for industrial analysis of coal, an infrared heating furnace that can efficiently heat samples is known as an infrared heating furnace that reflects infrared rays from an annular infrared heater on an annular elliptical reflective surface ( Japanese Patent Application Publication No. 5
6-9999C1).

[Problems to be Solved by the Invention] In the above-mentioned thermobalance method, if an infrared heating furnace having an annular elliptical reflective surface is used as the heating furnace, the temperature of the sample will increase quickly, which may seem convenient. It seems to me. in this case,
Infrared rays from an infrared heater placed at one focal point of the ellipse are reflected by the elliptical reflecting surface and concentrated on a sample placed at the other focal point of the ellipse. The sample will be placed in a crucible, and the infrared rays will be concentrated at one specific point of the crucible (the position of the other focal point of the ellipse). Then, the temperature distribution in the crucible becomes non-uniform, and there is a possibility that the temperature of the sample will not be raised uniformly. This is especially true when the crucible is relatively large.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an industrial analysis method for coal that allows a sample to be heated quickly and uniformly.

Another object of the present invention is to provide an infrared heating furnace that can heat a sample quickly and uniformly.

[Means for Solving the Problems] In order to achieve the above object, in the industrial coal analysis method according to the present invention, an annular infrared heater is used to heat the sample, and the infrared rays from this infrared heater are transmitted to a rotating curved surface. The infrared rays are reflected by the reflective surface formed by the crucible, and the entire crucible is irradiated with infrared rays.

Here, the term "rotated curved surface" refers to a curved surface that occurs when a certain planar curve is rotated around a straight line on the same plane.

Preferably, at least a part of the rotational curved surface is formed by rotating the parabola around an axis inclined with respect to the main axis of the parabola (hereinafter referred to as a parabolic rotational curved surface), and the infrared heater The crucible is placed at the focal point of the parabola, and the crucible is placed on the main axis of the parabola.

Further, in the infrared heating furnace according to the present invention, in the infrared heating furnace of the type in which the infrared rays from the annular infrared heater are reflected on a rotating curved surface and irradiated onto the sample, at least a part of the rotating curved surface is a parabolic rotating curved surface. The infrared heater is arranged at the focal point of the parabola, and the sample is arranged on the main axis of the parabola.

Preferably, a part of the rotational curved surface is formed by the parabolic rotational curved surface, and both sides of the parabolic rotational curved surface are formed by rotating the ellipse around an axis inclined with respect to the main axis of the ellipse (hereinafter referred to as a curved surface). (referred to as an elliptic surface of revolution).

[Function] In the invention of the industrial coal analysis method, an annular infrared heater is used and infrared rays are reflected by a rotating curved surface.
Infrared radiation can be collected into a crucible. However, instead of concentrating the infrared rays on one point on the crucible, the infrared rays are concentrated over the entire crucible. This makes the crucible −
The temperature distribution of the sample becomes uniform.

In order to uniformly irradiate the crucible with infrared rays, at least a portion of the rotating curved surface can be configured as a parabolic rotating curved surface. Then, an annular infrared heater is placed at the focal point of the parabola, and the crucible is placed on the main axis of the parabola. In this way, the part of the infrared rays emitted from the infrared heater is reflected by the parabola and becomes a parallel ray, which hits the entire crucible.

In the invention of the infrared heating furnace, the infrared rays from the annular infrared heater are reflected by the rotating curved surface and hit the sample. At this time, the infrared rays reflected by the parabolic rotation curved surface become parallel rays and head towards the sample. Therefore, the sample is heated uniformly.

Roughly speaking, if a part of the rotational surface is made up of a parabolic rotational surface, and both sides of this parabolic rotational surface are made up of elliptical rotational surfaces, the infrared rays reflected by the parabolic rotational surface become parallel rays, while the elliptical rotational surface on the outside Infrared rays reflected by the curved surface are concentrated on the sample.

[Example〕 Next, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a vertical sectional view showing an example of a heating furnace of a thermobalance for implementing the analysis method according to the present invention. This heating furnace can be divided into an upper furnace body 10 and a lower furnace body 20. The inner wall surface of the upper furnace body 10 serves as a reflective surface 12 for reflecting infrared rays.

Cooling water passages 14 and 16 are formed inside the upper furnace body 10. Similarly, a reflecting surface 22 and cooling water passages 24 and 26 are formed in the lower furnace body 20. Two annular infrared heaters 30 are arranged one above the other inside the furnace surrounded by the reflective surfaces 12.degree. 22 of the upper furnace body 10 and the lower furnace body 20.

The lower furnace body 20 has its lower part fixed to a frame 28, and the upper furnace body 10 is vertically movable.

A balance 60 is disposed below the lower furnace body 20, and a sample stage holder 64 extends upward from the balance 60. There is a sample stand 62 at the upper end of the sample stand holder 64, on which the crucible 50 is placed. Crucible 50
A coal sample 52 can be accommodated inside. An upper protective glass 42 is fixed to the center of the upper furnace body 10, so that the sample stage 62 and the crucible 50 can be covered. A lower protective glass 44 is also fixed to the center of the lower furnace body 20, so that the sample stage holder 64
can be covered. When the upper furnace body 10 is lowered and combined with the lower furnace body 20, the lower end of the upper protective glass 42 comes very close to the flat upper end surface of the lower protective glass 44.

A gas supply port 46 is arranged inside the lower protective glass 44 so that nitrogen gas or oxygen gas can be supplied around the crucible 50.

The specific configuration of the above-described annular infrared heater 30 is as follows. The outer diameter of the entire heater is 85 mm. The protection tube 32 is made of quartz glass and has a diameter of about 10 mm. The internal heater coil 34 is made of tungsten and has a coil diameter of about 2 mm. When a heating furnace is used as shown in FIG. 1, the sample can be heated to 1000° C. by setting the rated power of the heater to 1.2 kW.

Moreover, the specific structure of the above-mentioned crucible 50 is as follows. The crucible is made of milky white ceramic and is approximately 7 cm.
There is a volume of 3, and its internal volume is approximately 3 cc. The inner diameter of the upper part of the crucible is 2 cm, which is larger than conventional crucibles. This increases the contact area between the sample and oxygen gas during ashing, and reduces the time required for ash content measurement. The weight of the crucible is approximately 20 grams, and 1 gram of pulverized coal is placed therein as a coal sample.

By the way, with a normal thermobalance, the crucible is small and small.
It is designed to hold 10 to 100 milligrams of sample. Therefore, when using a large crucible as in this example, uniformity of sample temperature becomes more important.

Next, the shape of the reflective surface 22 will be explained with reference to FIG. Note that the reflecting surface 12 of the upper furnace body 10 and the reflecting surface 22 of the lower furnace body 20 have the same shape. Therefore, in the following explanation, only the reflecting surface 22 of the lower furnace body 20 will be explained.

The reflective surface 22 is formed of a rotating curved surface. Here, the term "rotated curved surface" refers to a curved surface that occurs when a certain planar curve is rotated about a straight line on the same plane, as described above. In the reflecting surface 22 of this embodiment, a combination of a parabola and an ellipse is used as the plane curve. That is, only a predetermined length portion at the center of the plane curve is a parabolic portion 22a, and both sides thereof are lateral inner portions 22b. Then, by rotating this plane curve around the axis 23, the reflective surface 22 can be formed. The main axis 22G of the parabolic portion 22a is inclined at approximately 45 degrees with respect to the rotation axis 23. This creates a space that accommodates the annular infrared beam 30.

That is, if the parabolic portion 22a as a planar shape is rotated about the axis 23 inclined with respect to the main axis 22c, the parabolic rotation curved surface is obtained by 1q.

Moreover, if the horizontal inner portion 22b as a planar shape is rotated about an axis 23 inclined with respect to its main axis, an elliptical rotation curved surface can be obtained. In this embodiment, the rotating curved surface serving as the reflecting surface consists of a parabolic rotating curved surface at the center and elliptical rotating curved surfaces on both sides thereof.

The infrared heater 30 has a heater coil having a parabolic portion 2.
It is arranged so as to be located at the focal point A of 2a. The main axis of the lateral inner portion 22b is aligned with the main axis 22G of the parabolic portion 22a, and one focal point of the lateral inner portion 22b is located at the same position as the focal point A of the parabolic portion 22a. Lateral inner part 22b
The other focal point B is near the center of the crucible 50.

The infrared rays reflected by the parabolic portion 22a become parallel rays 35 and uniformly impinge on the crucible 50.

On the other hand, the infrared rays reflected by the lateral inner portion 22b are the focused light beam 3
6 and head towards focal point B. Reflective surface 22 in this embodiment
Here, the length of the parabolic portion 22a is 20 mm, which is about the same size as the crucible 50. As a result, parallel light rays are generated in a size range that is approximately the same as the size of the crucible, and the crucible is heated uniformly. Even if the range of the parallel rays is made wider than the size of the crucible, the outer parallel rays do not directly contribute to the heating of the crucible. Therefore, the outside of the parabolic part 22a is made into a horizontal inner part 22b, and the infrared rays coming outside the length are directed toward the crucible. This allows infrared rays to be used effectively. That is, by forming the reflecting surface 22 in such a shape, it is possible to simultaneously direct infrared rays toward the crucible and to irradiate the entire crucible with infrared rays.

In industrial analysis of coal, if only a specific part of the sample is heated, there are disadvantages such as volatile matter evaporating during moisture measurement, for example. Moreover, even except for such extreme cases, if the sample is heated non-uniformly, the reliability of the analytical data decreases. Therefore, in the present invention, as described above, the entire crucible is heated almost uniformly in order to avoid such inconvenience.

The reflective surface 22 is formed by plating copper on an aluminum base and further plating gold thereon, and has a mirror surface.

Note that the shape of the reflecting surface 22 can be modified in various ways other than that shown in FIG. For example, the outer lateral inner portion 22
The position of the other focal point B of b can be placed at the front or rear of the crucible 50 instead of being located near the center of the crucible 50. In this way, the infrared rays reflected by the lateral inner portion 22b will also hit the entire crucible, making the temperature of the crucible more uniform.

Further, the reflecting surface 22 can also be formed only from a parabolic portion. In this way, all the infrared rays reflected by the reflective surface 22 become parallel rays. As a result, the outer parallel light rays do not directly hit the crucible, and the rate of temperature rise of the sample becomes slightly slower. However, this outer parallel light beam is reflected many times within the furnace, serves to increase the temperature of the entire furnace, and contributes to some extent to the uniformity of the crucible temperature.

Next, a method for industrially analyzing coal using the heating furnace shown in FIG. 1 will be described. FIG. 3 is a graph showing changes in sample temperature and sample weight at this time. First, 1 gram of humidified pulverized coal is placed in the crucible 50 and placed on the sample stage 62, and the upper furnace body 10 is moved to the lower furnace body 201. : Overlap. Next, in a nitrogen gas atmosphere, the sample is heated to 107° C. at a temperature increase rate of 30° C./min and this temperature is maintained to evaporate water. Then, when the Φ amount change rate becomes within 0.2 milligrams/20 seconds, the weight loss in m at that time is measured, and this is taken as the water content of the sample.

Next, in the same nitrogen gas atmosphere, the temperature increase rate was increased to 110%.
The sample is heated to 950° C. and maintained at this temperature to evaporate the volatiles. Then, after holding at 950° C. for 3 minutes, the weight loss for 4 minutes is measured, and this is taken as the volatile content of the sample.

Next, in an oxygen gas atmosphere, the sample temperature is returned to 850° C. at a cooling rate of 50° C./min, and this temperature is maintained to burn the fixed carbon. Then, when the amount change v1 is within 0.2 milligrams/8 seconds, the remaining weight at that time is measured, and this is taken as the ash content of the sample. The fixed carbon of a sample is the value remaining after moisture, volatile matter, and ash are subtracted from the original sample.

Both the nitrogen gas and oxygen gas mentioned above are supplied from the gas supply port 46 at a flow rate of 1.2 liters/minute. These gases are discharged to the outside from the upper end 43 of the upper protective glass 42.

The time required for the above analysis is approximately 5 minutes for moisture measurement, approximately 10 minutes for volatile content measurement, and approximately 15 minutes for ash content measurement, for a total of approximately 30 minutes. Furthermore, since it takes about 10 to 15 minutes to cool down the furnace, it takes about 40 to 45 minutes to remove the sample from the furnace.
It takes minutes. That is, the cycle time for analyzing one sample is 40-45 minutes.

The analytical data obtained by the thermobalance method is subjected to predetermined corrections as necessary in order to convert it into data obtained by the JIS method.

[Effects of the Invention] As explained above, in this invention, in order to heat the coal sample in the crucible, the infrared rays from the annular infrared heater are reflected by the rotating curved surface, so the infrared rays can be collected in the crucible. . Moreover, since the infrared rays are concentrated over the entire crucible instead of being concentrated at one point on the crucible, the temperature of the crucible increases quickly and uniformly, resulting in a uniform temperature distribution in the coal sample.

Furthermore, in the invention according to claim 2, in order to uniformly irradiate the crucible with infrared rays, at least a part of the rotating curved surface is configured as a parabolic rotating curved surface.

As a result, the infrared portion reflected by the parabolic rotation curved surface becomes a parallel beam of light that uniformly hits the entire crucible.

Further, in the infrared heating furnace according to the present invention, at least a part of the rotating curved surface as a reflecting surface is constituted by a parabolic rotating curved surface, so that the infrared rays reflected by the parabolic rotating curved surface become parallel rays and strike the sample. can be heated quickly and uniformly.

Roughly speaking, in the invention set forth in claim 4, since both sides of the parabolic rotation curved surface are constituted by elliptic rotation curved surfaces, the infrared rays reflected by the parabolic rotation curved surface become parallel rays, and the infrared rays reflected by the elliptic rotation curved surface outside the parabolic rotation curved surface become parallel rays. concentrates on the sample. Therefore, by limiting the parallel rays to a range of dimensions comparable to the sample,
The sample can be efficiently irradiated with the outer infrared rays.

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional view of an example of a heating furnace of a thermobalance used in the analysis method according to the present invention, Fig. 2 is a vertical cross-sectional view illustrating the configuration and function of the reflective surface of this heating furnace, and Fig. 3 is a graph showing the temperature increase process of the analysis method using this heating furnace. 12.22...Reflection surface 22a...Parabolic portion 22b...Ellipse portion 22c
...Principal axis 23 of the parabolic part ...Rotation axis 30 of the rotating curved surface ...Infrared heater 50 ...Crucible 52 ...Coal sample △ ・
...Focus of the parabola

Claims (4)

[Claims] (1) In an industrial coal analysis method in which moisture, volatile content, and ash content are sequentially measured in the same sample by heating the sample coal in a crucible and measuring the weight change, A method for industrial analysis of coal, characterized in that an annular infrared heater is used, the infrared rays from the infrared heater are reflected by a reflecting surface formed by a rotating curved surface, and the entire crucible is irradiated with infrared rays. . (2) At least a part of the rotational curved surface is formed by rotating the parabola around an axis inclined with respect to the main axis of the parabola, and the infrared heater is arranged at a focal point of the parabola. 2. The method for industrial analysis of coal according to claim 1, wherein the crucible is placed on the main axis of the parabola. (3) In an infrared heating furnace in which the infrared rays from an annular infrared heater are reflected on a rotating curved surface and irradiated onto the sample, at least a portion of the rotating curved surface rotates around an axis inclined with respect to the main axis of the parabola. The sample is composed of a curved surface formed by rotating the parabola (hereinafter referred to as a parabolic rotation curved surface), the infrared heater is disposed at a focal point of the parabola, and the sample is disposed on the main axis of the parabola. Infrared heating furnace. (4) A part of the rotational curved surface is composed of the parabolic rotational curved surface, and both sides of the parabolic rotational curved surface are composed of curved surfaces formed by rotating the ellipse around an axis inclined with respect to the main axis of the ellipse. The infrared heating furnace according to claim 3, characterized in that: