JPS5863791A - Solid fuel - Google Patents

Abstract

PURPOSE:A safe solid fuel, prepared from coal, coke or charcoal as a main raw material, and having plural specific holes, and discharging a waste gas having good characteristics of toxic gases, e.g. CO or a hydrocarbon. CONSTITUTION:A solid fuel, prepared from coal, coke or charcoal as a main raw material, and having plural holes 2 with 10-200mm.<2>/hole cross-sectional area and 25-70% hole area ratio in a platy form. The shape of the hole is circular, square, hexagonal, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a solid fuel used in a solid fuel combustor, and the present invention relates to a solid fuel used in a solid fuel combustor. The aim is to obtain a solid fuel that is safe and has excellent exhaust gas characteristics.

In recent years, from the viewpoint of oil resource depletion, carbonaceous fuels, mainly coal, have been reconsidered as an alternative energy source. is being reviewed. However, coal fuel, which is typified by the combustion of carbonaceous fuels, has many problems in handling, combustion methods, combustion conditions, etc. because it is not liquid like petroleum fuel.

The present invention aims to improve these drawbacks of solid fuels, and is particularly effective in reducing harmful gases, particularly carbon oxides and hydrocarbons, generated when solid fuels are burned. .

The most well-known conventional solid fuels are coal-based briquettes and charcoal for household use, and fuels other than coke include charcoal made by carbonizing wood. The present invention aims to improve the structure (shape) and properties, particularly the combustion exhaust gas properties, of these conventionally well-known solid fuels whose main raw materials are coal, coke or charcoal.

Table 1 shows the structure and characteristics of conventional solid fuels.

(Left below) As is clear from Table 1, each solid fuel has different characteristics. However, they all have one thing in common: poor exhaust gas characteristics. Factors that affect exhaust gas characteristics are listed below, and each will be specifically explained.

(1) Effects of the composition of solid fuels In the production of solid fuels, the binder, desulfurizer, ignition accelerator (oxidizer), etc. added to the carbonaceous fuel have an influence, but the types and blending ratio of additives are It must be used with due consideration. These binders produce harmful gases (smoke, bad odor) when burned.
This is the main cause of deterioration of combustion exhaust gas characteristics.

Next, the sulfur compounds contained in the solid fuel are fixed,
Desulfurization agents that are usually added for the purpose of reducing sulfur compounds in exhaust gas include calcium carbonate, calcium hydroxide, barium carbonate, etc., but these desulfurization agents can also be used depending on the purpose and use. It is necessary that it be added. For example, when a desulfurizing agent such as calcium carbonate, calcium hydroxide, or barium carbonate is used, the desulfurization chemical reaction formula can be considered as shown below, and the sulfur content is fixed in the solid fuel.

CaCO3+S+5/202→CaSO4+CO2Ca
(OH)2+S-1-sfi O2→Ca5o4+H2
OBaCO3+ S +5/2.02-+ BaSO4
+Co2 In the above reaction equation, the simplest way to efficiently desulfurize sulfur in fuel is to increase the amount of desulfurization agent added, but increasing the amount of desulfurization agent added increases the amount of coal that is the main raw material. Alternatively, the proportion of carbonaceous fuel such as charcoal may be reduced, which is a major factor that adversely affects the combustion of solid fuel. Therefore, when adding a desulfurizing agent, it is necessary to carefully examine the amount added, the type of additive, etc. Further, ignition accelerators (oxidizers, etc.) must be taken into consideration as they are a factor that greatly affects the combustion of solid fuel.

(2) Influence of solid fuel composition method Exhaust gas characteristics are affected by solid fuel configuration, including its shape, etc. It is important that In particular, in the combustion of homogeneous fuels, since the surface layer is in contact with the air during surface combustion, a major factor is how to increase the surface area of the solid fuel and supply the necessary amount of air. If sufficient air is not supplied, incomplete combustion will occur, and some portions will remain as fuel components without being combusted.

Normally, combustion air has a theoretical air amount (the theoretical amount of air required for complete combustion of fuel) and an excess air amount (air used when the fuel is combusted). The air that is present is called excess air, and in order to combust solid fuel in a state close to complete combustion, it is usually necessary to supply a large amount of this excess air. This occurs because combustion of solid fuel is not as easy to mix with air as is the case with combustion of gaseous fuel. Generally, excess air is gaseous fuel.

The latter increases in order of liquid fuel and solid fuel, and the more excess air is better when considered only from the standpoint of achieving complete combustion. However, if there is too much excess air, the following problems will occur.

(a) The amount of combustion gas increases, impeding ventilation and worsening exhaust gas characteristics.

Naka) Lowers the combustion temperature and tends to cause incomplete combustion.

As mentioned above, even if there is too much excess air, incomplete combustion will occur and the combustion exhaust gas characteristics will deteriorate. Also, if it is too small, incomplete combustion will occur. It is already a well-known fact that combustion conditions change due to excess air, but in the case of solid fuel, unlike liquid or gaseous fuel,
It is difficult to maintain a constant state of combustion in dogs due to changes in combustion over time.

However, it is possible to achieve stable combustion (complete combustion) by regulating the composition of the solid fuel, and it is possible to achieve stable combustion (complete combustion) by regulating the composition of the solid fuel. It is necessary to

(3) Impact of solid fuel combustor No matter how good the solid fuel is used, if an imperfect combustor is used, the exhaust gas characteristics will deteriorate.For example, if the insulation material of the combustion part is Exhaust gas characteristics change depending on the type used or not, and whether or not a secondary combustion chamber is provided.

D) Impact of solid fuel manufacturing method This is due to differences in solid fuel manufacturing conditions, etc.
For example, even if the press pressure is different, the exhaust gas characteristics will change drastically, and the higher the press pressure, the more
Exhaust gas characteristics deteriorate. These are the effects of manufacturing conditions on exhaust gas characteristics.

The above four factors greatly affect exhaust gas performance. Under these conditions, the present invention particularly improves the solid fuel composition method (2).

Briquettes are the closest to the structure of the present invention. If we compare this as a conventional example, coal.

It is the same as the present invention in that it is composed of a solid fuel made of carbonaceous fuel whose main raw material is coke or charcoal and has a plurality of through holes, but the cross-sectional area of the plurality of through holes is (-j) Alternatively, the conventional structure differs from the present invention in the size of the through-hole aperture, and due to this difference, the conventional structure has poor exhaust gas characteristics. The present inventors have established optimal structural conditions for a solid fuel with excellent exhaust gas characteristics.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the present invention will be compared with a conventional structure and explained below with reference to the drawings.

Figs. 1 and 2 show the structure of a conventional briquette, and Figs. 3 and 4 show a plate-shaped solid fuel according to the present invention.

Comparing the two, the basic configuration is the same, but the arrangement of the through holes 2 is different.

The method of setting the through holes 2 in the solid fuel 1 of the present invention is such that the cross-sectional area of the plurality of through holes 2 is 10 to 2oO-7, and all the through holes are open (the solid fuel volume including the through holes is It is characterized in that the porosity of all the pores is 26 to 70%. The cross-sectional area of the through-holes 2' of the conventional charcoal briquette 1' is 8o-7, and the through-hole porosity is about 10%.

The example shown in FIGS. 3 and 4 is a solid fuel in the form of a rectangular plate having a large number of through holes. Here, the pore cross-sectional area refers to the area of the round hole in the hole shown in the plan view of FIG. It refers to the total cross-sectional area of all open pores relative to the total cross-sectional area of solid fuel including pores.

In this example, the hole shape is a round hole, but it is a square hole.

A hexagonal hole or the like is also acceptable. Furthermore, the overall shape of the solid fuel is not necessarily rectangular.

6 to 6 show one having a hexagonal hole, and FIG. 6 shows one having a square hole, both of which have a flat plate shape as described above.

Hereinafter, the present invention will be explained in detail according to Examples.

Example 1 The solid fuel composition shown in Table 2 was molded into 2 pieces using a press molding machine.
It was formed into a rectangular plate-like body having round holes of various aperture ratios and cross-sectional areas under a pressure of 0 kf//14. The plate size is 116W square and the height is 50ran.

These various solid fuels were burned under the same conditions using the combustor shown in FIG. 7, and the solid fuels were evaluated based on exhaust gas characteristics.

Regarding the exhaust gas characteristics in Table 2, the amount of carbon monoxide generated was measured. The measurement method is to examine the change in carbon monoxide concentration over time when solid fuel is burned in a closed chamber (11.7 ml). went.

In Figure 7, 1 is the sample solid fuel, 3 is the insulation material,
4 is the exterior, 6 is the primary air port, 6 is the secondary air port, 7 is the handle, and 8 is the trivet.

~The above evaluation results are shown in Table 3 and Figures 8 and 9.

(Left below) JP-A-58-63791 (4) Carbon monoxide concentration when varied from 0 to 260π
Fig. 9 shows the carbon monoxide concentration (ppm) when the pore area is varied from 0 to 90% with a pore cross-sectional area of 1oo-. show.

From Figure 8, it is clear that carbon monoxide increases dramatically when the cross-sectional area of the through-hole is set to 10 mm or less, and carbon monoxide increases similarly even when the cross-sectional area of the through-hole is set to 200 mm or more. increases, and exhaust gas characteristics worsen. In both cases, it is clear that the pore cross-sectional area has inflection points at 10 and 2001, and the optimum pore cross-sectional area ranges from 10 to 200 rU/piece.

Next, from Figure 9, if the through-hole porosity is set to 26% or less,
-The carbon oxide concentration is extremely increased and the pore size is reduced to 70%.
% or more, the carbon monoxide concentration will similarly increase dramatically. It can be seen that when the porosity is 26% to 70%, the exhaust gas characteristics are good and the range is optimal for use.

16.- Regarding the through-hole porosity, to explain the reason why the carbon monoxide concentration increases at 26% or less, when the through-hole porosity is 25% or less,
This is thought to be due to insufficient air supply required for complete combustion. A characteristic of combustion in this case is that the exhaust gas characteristics are good in the initial stage of combustion, but the exhaust gas characteristics are poor thereafter. At the beginning of combustion, the combustion exhaust gas characteristics near the surface layer of the solid fuel are good; this is easily understood from the fact that solid fuel burns on the surface, and combustion progresses inside the solid fuel. It is understood that the efficiency of contact with air decreases as the temperature increases, leading to incomplete combustion and deteriorating exhaust gas characteristics.

Next, if the porosity is 70% or more, the above-mentioned porosity 26
% or less, in which the air necessary for complete combustion is supplied sufficiently, but since a larger amount of air is injected than the ideal amount, the exhaust gas characteristics are deteriorated, and excessive This can be said to be a negative effect of having too much air. Too much excess air reduces the combustion temperature of the solid fuel, and increases the amount of exhaust gas, which obstructs ventilation.
Deteriorates exhaust gas characteristics.

On the other hand, in the range of the porosity of 26 to 7o%, combustion air is supplied in an ideal form, so the solid fuel is ideally combusted, and as a result, it can be said that the exhaust gas characteristics are good.

The reason why the exhaust gas characteristics change depending on the cross-sectional area of the pores is the same as that explained with the pore area ratio. This is because sufficient air is not supplied for a long time for combustion, and when the number is 200-7 or more, a larger amount of combustion air than the ideal amount is supplied, resulting in incomplete combustion. It is thought that this is caused.

Example 2 In the conventional briquette shape shown in FIG. 1, the combustion exhaust gas characteristics were investigated by changing the pore size. The results are shown in FIG. The solid fuel composition is in Table 2. Furthermore, the evaluation method and measurement method for exhaust gas characteristics are also the same as in Example 1. The dimensions of the hardboard fuel used were 116rIr in diameter.
The IR1 was 17-cylindrical with a height of 12 oran, and had a cross-sectional area of 7 holes f 80 mj, and the porosity was changed by increasing the number of holes.

As can be seen from Fig. 10, excellent combustion was achieved when the pore area ratio was 26 to 70%.

As described above, according to the present invention, a solid fuel that has the most ideal combustion can be obtained.

[Brief explanation of the drawing]

Figure 1 is a plan view showing a conventional example of charcoal briquettes, Figure 2 is Figure 1 U
3 is a plan view of the solid fuel according to the present invention, FIG. 4 is a sectional view taken along line mV-N' in FIG. 3, and FIGS. 5 and 6 are plan views showing other examples. FIG. 7 is a longitudinal cross-sectional view of the combustor used in the example, and FIGS. 8 to 10 show the relationship between the pore cross-sectional area or aperture ratio of the solid fuel and the carbon monoxide concentration. Name of agent: Patent attorney Toshio Nakao and 1 other person #4
Figure 2 Figure 3 Figure 5 Figure 6 Figure 7 Figure 8 Figure 1 111

Claims (1)

[Claims] A solid fuel whose main raw material is coal, coke, or charcoal, and has a plurality of through holes, and the cross-sectional area of the through holes is 10 to 10.
A solid fuel with 20o-7 pores and a porosity of 26 to 7o%.