JPS5889694A - Fuel composition and its preparation - Google Patents

Abstract

PURPOSE:To obtain a fuel composition which can be gasified and burnt as a solid in a remarkably shortened time, and can be transported, stored and burnt in the same manner as dry powdered coal, by impregnating a methanol fuel into the micropores of coal particle. CONSTITUTION:The objective solide granular fuel composition is prepared by essentially impregnating (A) about 3-35 (wt)% methanol fuel into (B) the micropores of about 65-95% coal particles having the size of usually <=1,000mu (the major part thereof is <=300mu). The preparation of the composition can be carried out e.g. by the combination of mechanical separation and heat evaporation of the solid-liquid suspension of coal particle and methanol fuel, to separate the excess methanol fuel.

Description

DETAILED DESCRIPTION OF THE INVENTION With the rise in prices of petroleum-based fuels such as heavy oil and kerosene, there has been a movement in recent years to switch from petroleum-based fuels to coal in power plants and other industrial combustion furnaces. Additionally, the use of coal in newly constructed combustion furnaces has increased significantly.

However, a major drawback in the design of combustion furnaces using coal is poor combustibility, which is mainly caused by the extremely slow combustion speed 1 of coal particles compared to petroleum-based fuels. Therefore, taking a pulverized coal combustion boiler for power generation as an example, in the case of heavy oil combustion, the combustion chamber heat release rate (the amount of heat supplied per hour per combustion chamber volume L-D) is approximately soo, ooo ~ 2,000. .0
00 keel/jh is small, while for coal it is approximately Woo, 000 to 200.0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 for coal-fired boilers, it is approximately 150. Generally, it is .000Ke&l/d h or less. This means that if you want to generate the same amount of heat as when burning heavy oil, you will need to make the boiler several tens of times larger with coal, and with COM, which is a mixed fuel of coal and heavy oil, the calorific value is higher than the unit weight. Although the combustion chamber heat release rate can be higher than that of coal because of the fact that it is larger than that of coal, the combustibility of coal particles has not been improved as usual.

The present invention improves the combustion rate of coal particles, thereby
The aim is to improve the combustibility of coal and alleviate the disadvantages of coal combustion compared to heavy oil.

As is well known, the combustion of coal particles involves gasification combustion in which the volatile matter in the coal is gasified and combusted, and residual solid combustion (
Although two-stage combustion (residual carbon combustion) is performed, the combustion rate of the latter half is very slow and the overall combustion time is longer. On the other hand, liquid fuels such as heavy oil and methanol have a small solid combustible portion or a large amount of heat, so the combustion rate is fast. In the case of a mixture of coal and liquid, for example, if COM is a mixture of coal and heavy oil, the heavy oil does not penetrate into the micropores of the coal particles but instead wets or envelops the surface of the coal particles.

On the other hand, in the fuel composition of coal and methyl fuel mixture,
Compared to heavy oil, methyl fuel has a lower molecular weight, surface tension, and viscosity1, and has greater compatibility with water, so there is a phenomenon in which it penetrates into the micropores of coal particles and replaces water in the same micropores. . The present invention was achieved by discovering that methyl fuel in these microbores has an effect on improving the combustion rate [7]
In other words, the present invention provides "a combustible solid powder fuel composition consisting of coal particles and methyl fuel, in which the methyl fuel substantially permeates into the micropores of the coal particles, and a method for producing the same."
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According to the combustion test of the fuel composition of the present invention, it is recognized that the combustion behavior is two-stage combustion similar to that of coal particles. Analyzing the behavior of individual combustions, we find that in coal combustion, a stable luminous flame is formed during the first stage of gasification combustion, and there is almost no change in the volume-based specific surface area diameter of the grains between the early and final stages of combustion. Instead, the process shifts to 82-stage solid combustion. Also, C
In the combustion of OM, there are two stages of combustion similar to coal, but during the first stage of gasification combustion, a long, stable and bright flame is observed, which is longer than that of coal, and the volume-based specific surface area diameter of the droplets or particles is similar to that of coal. As in the case of Kit, there is almost no change and no fragmentation of the remaining enclosure is observed, leading to the transition to the second stage.

On the other hand, the fuel composition of the present invention undergoes two-stage combustion like the first two, but the methyl fuel that has permeated into the micropores of the coal particles is gradually and rapidly released from near the surface during the first-stage gasification combustion. It evaporates and expands, crushing and scattering solid particles and combusts explosively, forming a bright flame accompanied by sparks and significantly reducing the volume-based specific surface area diameter. Therefore, the gasification combustion time is shortened, and the solid combustion time is also greatly shortened. Therefore,
When comparing the overall combustion time with coal alone under the same conditions, there are some differences depending on the type of coal, but it is approximately 2/3 ~
1/! It can be shortened to

Currently, when coal particles are sprayed and burned in a combustion furnace, in order to maintain the drying efficiency, the size of the coal particles is approximately 60 to 80 wt. Common. However, the power required to pulverize coal is large, and the smaller the size of the coal particles in the pulverized firefly, the greater the power cost. On the other hand, the coal particles of the present invention have a particle size of 1000 μm or less, and most of them may have a particle size of 300 μm or less, so the manufacturing cost of the coal particles is significantly reduced.

If the size of the coal particles exceeds 300 μm, the amount of methyl fuel penetrating into the micropores of the coal particles decreases, and the desired improvement in combustibility cannot be expected and the object of the present invention cannot be achieved.

Furthermore, if the methyl fuel mixed with coal is less than Fi5 wt-, it will be difficult to achieve a uniform mixture with coal particles, and further improvement in the combustibility of coal cannot be expected. Also, although it varies greatly depending on the type of coal, methyl fuel
If it exceeds 5vt91, the coal will become wet and there is a high possibility that storage and spraying into the combustion furnace will be hindered.

That is, when the fuel composition of the present invention is transported, stored, and burned,
It can be said to be an excellent solid powder fuel that can be handled as easily as pulverized coal that has been dried to a moisture content of 1011 or less.

The coal particles mentioned in this specification refer to all particles produced by pulverizing coal such as anthracite coal, bituminous coal, subbituminous coal, and brown coal. Methyl fuel may be composed of methanol alone, or if it consists mostly of methanol, it may be a mixture with oxygen-containing compounds such as lower alcohols having 2 to 4 carbon atoms, or even about 20 methanol. It contains water at wt * 1 and cannot be used as a tortoise.

There are two methods for producing the fuel composition of the present invention.

1. As shown in FIG. 1, a liquid-solid suspension consisting of methyl fuel and coal is supplied from a storage tank 1 to a methyl fuel separator 2. A liquid-solid suspension consisting of methyl fuel and coal ii. Use quality products produced and transported in coal-producing regions in Japan and abroad. As a methyl fuel separator, one that mainly uses gravity is not preferable because separation is not sufficient, but one that mainly uses centrifugal force is preferable. Furthermore, it is effective to use a combination of mechanical separation, such as using centrifugal force, and thermal evaporation separation.

However, adding a large amount of heat is undesirable because it dissipates the methyl fuel in the micropores of the coal and reduces the effect of fragmentation and combustion of coal particles during combustion. The methyl fuel discharged from the methyl fuel separator 2 is partially separated, and the fuel composition of the present invention is stored in a storage tank 3, and the methyl fuel is stored in a storage tank 4.
Each is transported to the consumption area and consumed.

2nd Fi, as shown in Figure 2, the coal is heated to the desired temperature in the crusher 1.
The particles K are adjusted and then sent to the mixer 2. The mixer mixes it with methyl fuel sent from another system. It is preferable that coal particles and methyl fuel are mixed uniformly, and for this reason, a particle suspension agitation type mixer such as a fluidized ima combiner, a rotating circle *m mixer, or an air flow type mixer must be used. It won't happen. From the mixer 2, the fuel composition of the present invention is stored in a storage tank 3, transported to a consumption point, and consumed.

Next, the present invention will be further clarified with reference to Example Combustion Tests 1 to 3 and Comparative Example Combustion Tests 1 to 9.

Examples Combustion Tests 1 to 3, Comparative Examples Combustion Tests 1 to 9 Suspension rate droplet and grain combustion tests by forced ignition were carried out on the fuel compositions of the present invention and heavy oil and C0M1 coal as a comparison. The test was conducted using combustion air of 800 to 1000
Heating to a constant temperature within the range of ℃, 0.76 Kl/wi
A mass flow rate of −s is applied to the sample. Forced ignition was used to ignite the sample, and the combustion behavior was measured by burning it in the aforementioned high-temperature air flow. The test results regarding the burning rate are shown in Table 3 and Figure 3. Table 3 and FIG. 3 are graphs showing the relationship between the overall combustion rate coefficient .゛ and the residual solid content -ReIJj-.

00 Ko is defined by the equation α).

Do: Volume-based specific surface area of droplets or grains at the initial stage of combustion)
(m) Dn: Volumetric ratio of ash after combustion! I! Area 1
K(■) to: Required time for combustion (8) On the other hand, -1 ssi represents the amount of residual isomer contained in sample 1 which is combusted as a solid after being combusted to 0G gas.

RC: Total residual solid content (vtlG) L: Sample! l(J'/, 1) The fuel composition used in the combustion test was manufactured as follows.Canadian C charcoal, American 1iM charcoal, and Indonesian charcoal were each used separately, and after drying, the particle size was determined. The powder is crushed to a particle size of 70 wtll K or less, mixed with the same amount of methanol per weight to form a liquid-solid suspension of methanol and coal, and then separated from the coal and methanol using a centrifuge. A solid fuel composition of 80 wtlG of coal and 20 vtlG of methanol was produced.For the test, a small basket was made with a pt-pt-ith thermocouple (plain wire @ a l mφ), and in it a A sample was prepared by charging the fuel composition of the present invention so that the fuel composition of the present invention was obtained.

Samples of 900M, heavy oil, and coal used for comparative combustion tests were prepared as follows. For COM, Canadian coal was dried and ground to a particle size of 4J or less, 7 O'vt1g, and mixed with the same amount of heavy oil C per weight. The sample is pt
-pt-iih A droplet with a diameter of about L3 to 25 was created by hanging from the tip of a thermocouple (wire diameter α1■φ).

The C heavy oil sample produced droplets similar to COM.

Single coal samples were the aforementioned Canadian coal, American coal, and Indonesian coal, which were crushed to a particle size of 2-3cm.
It was charged into a basket in the same manner as the @O fuel composition of the present invention.

Tables 1 and 2 show the physical properties of the coal used in the combustion tests of the examples and comparative combustion tests of the present invention.

11th! The display of moisture, ash, volatile matter, and fixed carbon is JI8M8812, and the total sulfur is JI8M8813.
The calorific value is based on JI8M8814. Table 2 shows JIg
According to M8813.

As is clear from the test results F'i in Table 3 and Figure 3, COM, heavy oil, and coal were all K.

is proportional to -R64' K n to the minus power,
00 The fuel composition of the present invention has a high value, indicating that it burns in a different mechanism from other fuels and therefore does not conform to general principles and has excellent flammability. Observing the combustion behavior of the fuel composition of the present invention, it is found that in the case of COM and coal, there is no splitting of coal particles during gasification combustion, and the coal particles are burned as - droplets or grains, whereas the fuel composition of the present invention splits. burn while doing so. Therefore, it is thought that the tortoise exhibits a high burning rate coefficient despite having a large amount of residual solids.

1st I! Coal industrial analysis values, etc. Table 2 Coal elemental analysis values (unit: vtll) Table 3 Table corresponding to Figure 111E3

[Brief explanation of drawings]

Figure 1 and Figure IF5 are flow sheets of an example of the method for producing the fuel composition of the present invention. In Fig. I11, 1 shows a storage tank for a suspended liquid-solid body consisting of methyl fuel and coal, 2 shows a separator, 3 shows a fuel composition storage tank, and 4 shows a separated 9-methyl fuel storage tank. In Figure 2, 1... Coal crusher, 2...
- Mixer, 3... indicates a fuel composition storage tank. FIG. 3 represents the Example 91 combustion test and the Comparative Example combustion test of the fuel composition of the present invention. In the figure, Ko-...Overall combustion rate coefficient (-/8)5. ．． ．． Sample 1 - Represents the amount of residual solids (j'/7) that burn at 0G solids after gasification combustion contained in sample 1. Applicant: Mitsui Mining Co., Ltd. No. J111 $2tffi No. 31 “” (11/cd) O0

Claims (1)

[Scope of Claims] (1) A combustible solid powder fuel composition in which the coal particles are made of methyl fuel, and the methyl fuel substantially permeates into the micropores of the coal particles. e) The proportion of coal particles and methyl fuel is 65-96 respectively.
WtlG, 5-36 VT-T6!41 The fuel composition according to Section 8, Paragraph 1 of 111. (3) The fuel composition according to claim 1 or 2, wherein the coal particles have a size of 1000J1 or less, and most of the coal particles have a size of 300μ or less. . (4) A method for producing a fuel composition according to claim 4, characterized in that excess methyl fuel is separated from a liquid-solid suspension consisting of coal particles and methyl fuel. (5) Mechanical separation and heating evaporation of methyl fuel
5. A method for producing a fuel composition according to claim 4, in which the fuel composition is used in combination with the following. (6) Coal is pulverized to obtain desired particles, an appropriate amount of methyl fuel is added to the wrinkled particles, and the mixture is mixed in a particle suspension agitation mixer. A method for producing a fuel composition.