JPS61228096A - Production of woody solidified fuel - Google Patents

Abstract

PURPOSE:To obtain an woody solidified fuel without forming clinker by consolidation of fuel ash, by incorporating a specific amount of a calcium compound with a woody fuel prepared by forming and granulating wood meal of scrap wood. CONSTITUTION:Wood meal of woody scrap wood from a sawmill, e.g. mills ends, sawdust, bark, thinned wood, damaged scrap wood of pine weevil, etc., is formed and granulated into the form of pellets at high temperatures under high pressure to give a woody fuel, which is then incorporated with 0.2-3.2wt% calcium compound (preferred example; calcium carbonate powder) to afford the aimed woody solidified fuel. EFFECT:The resultant fuel ash is easily utilized as a fertilizer, and the improvement in the fertilizer effect is expected by addition of Ca.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to the reforming of solidified wood fuel obtained by solidifying wood waste, and more specifically, the present invention relates to the reforming of solidified wood fuel obtained by solidifying wood waste, and more specifically, the present invention relates to the reforming of solidified wood fuel, which is made by solidifying wood waste, and more specifically, the present invention relates to the reforming of solidified wood fuel, which is made by solidifying wood waste. The present invention relates to a method for producing solidified wood fuel.

In recent years, biomass resources have been reconsidered as an alternative fuel to oil.
The need for effective use of wood is increasing, and one way to use it is to crush wood waste such as bark, thinned wood, and construction waste, which has not been used effectively in the past, and form it into pellets. Easy-to-combust solid fuels have been put into practical use, and the development of combustion technology suitable for burning such solidified fuels has progressed rapidly. It has come to be used in boilers, etc.

[Prior Art] Wood waste materials such as sawmill scraps, sawdust, bark, thinned wood, waste wood damaged by pine beetles, etc. are first crushed, then dried in a dryer, and further finely crushed. The obtained wood powder is granulated into pellets using a granulator under high temperature and pressure.
It is commercialized as solidified fuel.

This pelletized wood fuel has excellent ignitability, moisture resistance, and storage stability, as well as high density and homogenization, so it has twice the weight per unit weight compared to raw material waste wood, and the per unit volume. It has four times the calorific value, has high combustion efficiency, and can be combusted with automatic supply, just like oil.

The production of this type of pelletized wood fuel is carried out in Toyama Prefecture, which is an area where a large amount of northern ocean timber is accumulated. It has been put into practical use as a subsidized project.

[Problem to be solved by the invention] As mentioned above, wood fuel is made into pellets.

Because the calorific value per unit volume is large and the combustion efficiency is high,
The combustion temperature is quite high, and as a result, the ash produced by combustion tends to melt and form clinker.Furthermore, the raw materials for solidified wood fuel are bark, fallen trees, waste wood, etc., and various pollutants are mixed in. In particular, when northern ocean wood perc is used as a raw material, the perk contains a considerable amount of seawater due to sea transportation and wood storage, and clinker tends to form low-melting substances when producing ash. The ash content of the solidified fuel obtained from Hokuyo Timber Park, which is easy to generate, is 3 to 4z, and it is necessary to remove the ash as the combustion progresses, but clinker begins to be generated at a combustion temperature of around 800℃, and the combustion equipment It is necessary to remove this clinker, as it blocks the grate, obstructs ventilation, and reduces combustion efficiency. Further, in some cases, the continuation of combustion is inhibited, and clinker must be removed by stopping combustion. When combustion is stopped, the clinker becomes a large lump due to the temperature drop in the combustion furnace, which not only requires a great deal of effort to remove, but also may lead to damage to the combustion machine.

Furthermore, although the ash obtained from the combustion of woody materials is used as fertilizer, the generation of clinker impedes this use and causes problems in waste disposal.

[Means for Solving the Problem] As a result of conducting research to improve the drawbacks of the above-mentioned solidified wood fuel, the present inventor focused on the composition of combustion ash and discovered that the ash could be used as fertilizer. The present invention was achieved by discovering that it is possible to change the composition of ash, prevent ash from melting and solidifying under normal combustion conditions, and suppress the formation of clinker by incorporating a substance that does not reduce the fertilizer effect. It is.

That is, the present invention provides a method for producing solidified wood fuel by molding and granulating wood powder, in which a
This is a method for producing a solidified wood fuel characterized by blending ~3.2% by weight of a calcium compound.

The material for the solidified wood fuel of the present invention is not particularly limited, but
As mentioned above, the present invention is particularly effective for materials that are contaminated with seawater components, such as northern ocean wood parks, or materials that contain soil components, such as fallen trees, because they tend to generate clinker when burned.

Any calcium compound can be used in the present invention, but calcium carbonate powder is particularly preferred mainly because it is easily available and because of the disintegration effect of ash by carbon dioxide gas decomposed and generated at high temperatures.

The blending ratio of calcium compounds to wood fuel varies depending on the combustion conditions such as combustion temperature and atmosphere, the ash content and composition of the raw material, or the shape of pellets when solidified, but is usually 0. It ranges from 2 to 3.2% by weight. If the amount added is less than 0.2% by weight, no clinker formation suppressing effect can be expected, while if the amount added is more than 3.2% by weight, it tends to lower the melting temperature of the ash, and is also economically disadvantageous. It is.

In order to determine the amount of calcium compound mixed more accurately, it is preferable to use the ash content as a standard.In other words, the target solidified wood fuel or its raw material is incinerated at a temperature of about 600℃, and the resulting ash contains calcium. Mix compound powder,
The effective amount of addition can be determined by measuring its heat resistance using the Seegel cone test. For example, in the case of North Pacific Wood Park, adding 10 parts by weight of calcium carbonate powder to 100 parts by weight of ash increases the heat resistance at 1200°C. improvement can be seen.

The heat resistance of ash can be further improved by adding other ingredients. For example, the addition of aluminum compounds such as aluminum hydroxide improves the heat resistance of ash, and the amount of calcium carbonate added can be increased. A synergistic effect is observed in that the tendency for heat resistance to decrease due to an increase in the amount of calcium carbonate is prevented, and on the contrary, heat resistance improves as the amount of calcium carbonate increases. Particularly when combustion is carried out in a reducing atmosphere, the combination of aluminum hydroxide and miniram is effective.

[Function] Although the mechanism by which the addition of calcium compounds, particularly calcium carbonate, prevents clinker formation or agglomeration is not necessarily clear, calcium carbonate thermally decomposes into calcium oxide and carbon dioxide gas at 970°C. The products of this pyrolysis change the composition of the combustion ash, increasing its melting temperature and
This is thought to prevent the generated ash from melting and solidifying. It is also believed that physical changes during thermal decomposition have the effect of preventing clinker from clumping.

Aluminum hydroxide is dehydrated at temperatures above 300°C,
It is thought that the alumina produced changes the composition of the ash and improves its heat resistance, but the mechanism of the effect of combined use with calcium carbonate is not clear.

The calcium compound blended in the present invention prevents the generation of clinker during combustion without impairing the properties that solidified wood fuel should have.

[Effects of the Invention] The advantages of producing solidified wood fuel according to the present invention are as follows.

(1) Since the generation of clinker is suppressed during combustion, the grate is not clogged with combustion ash and combustion efficiency does not decrease.

(2) The automatic combustion function of the combustor will be fully utilized, the labor required for its maintenance and management will be reduced, and the quality of solidified wood fuel as an oil alternative fuel will be improved, making it possible to expand its use. - (3) Even when used in a normal combustion device, troubles in removing ash and damage to the device due to clinker generation are prevented.

(4) Since the obtained combustion ash does not contain any lumps, it can be easily used as a fertilizer, and the addition of calcium is expected to improve the fertilizer effect.

[Example] The solidified wood fuel used in the following examples was made from northern sea wood perc, and an example of the composition and properties of a conventional product is shown in Table 1.

Here, the ash content is the amount of ash obtained by incinerating the material at a temperature of 600° C. or lower, and its composition is shown in Table 2.

In addition, in these tables and the following description, % means % by weight, and parts mean parts by weight.

Example 1 Calcium carbonate was blended with the woody fuel in the woody fuel according to the mixing ratio shown in Table 3, and then the woody solidified fuel of the same shape was molded, and the combustion amount, burning rate, and burning time shown in the table. The test fuel was combusted. The generated ash was subjected to a particle size test and passed through a 1B mesh standard sieve (ASTM).
The particles were sorted into particles that passed through the ash, particles that did not pass through the ash, and clinker, which is a sintered body of 2 m or more, and each was expressed as a weight ratio (z) to the total weight of the ash. The results are also shown in Table 3.

Example 2 Solidified wood fuels of the same shape were formed using wood fuels containing calcium carbonate and wood fuels containing no calcium carbonate, and were used as test twists and materials. The blending ratio of calcium carbonate to wood fuel is 2.8z. A combustion continuity test was conducted using the combustion amount, combustion rate, and combustion time shown in Table 4. The combustion machine used was a heating machine manufactured by Company C (15,000 Kcal/H). After the combustion was completed, the same particle size test as in Example 1 was conducted on the generated ash. Table 4 shows the results for unmixed wood fuel.
The results for the calcium carbonate blended fuel are shown in Table 5. Figure 1 shows the change in the weight ratio of clinker in the combustion ash with respect to the combustion time based on the results in Tables 4 and 5.

Example 3 Wood solidified fuel was incinerated at 800°C or lower, and charcoal calcium powder was blended in an amount of 20 to 80% by weight 2 based on the weight of particles that passed through sieve number 130 (ASTM).
Test cones were made according to IS-R2204. The pedestal is made by blending 1 oz of chamotte powder with clay clay and molding it in water.

The test cone was placed in a pedestal together with a standard Zegel cone according to JIS-R2204, held at 1200° C. for 3 hours, then allowed to cool naturally to room temperature, and its cutting angle was measured. The relationship between the blending ratio of calcium carbonate to combustion ash (heavy NZ) and the cutting angle of the test cone is shown in Figure 2.123
The melting test at 0°C also gave almost the same results.

[Brief explanation of drawings]

Fig. 1 is a graph showing the clinker production ratio with respect to the combustion time of solidified wood fuel, and Fig. 2 shows the results of a cutting test of a Zegel drill made by blending calcium carbonate with the combustion ash of wood fuel.

Claims (2)

[Claims] (1) In a method for producing solidified wood fuel by molding and granulating wood powder, the
A method for producing a solidified wood fuel, which comprises blending a calcium compound in an amount of % by weight. (2) The method according to claim 1, wherein the calcium compound is calcium carbonate.