JPH03157493A - Molding of low grade coal by utilization of vegetable fibrous material - Google Patents

Abstract

PURPOSE:To obtain a molded coal having extremely high collapsing strength, excellent ignitability and combustibility without generating harmful gas nor collapsing during combustion by mixing a low grade crushed coal, a vegetable fibrous material and slaked lime, further adding a molasses, mixing and press molding. CONSTITUTION:(A) A crushsed coal of low grade coal having <=5500kcal/kg heat generation crushed to <=3mm grain size is mixed with (B) 10-30wt.% vegetable fiber such as crops or vegetables dried and crushed to <=3mm size and (C) 3-5wt.% slaked lime and further (D) 3-8wt.% molasses (>=60wt.% to the component C), then stirred, thus reaction of the component C and the component D is accelerated to obtain mixed raw material powder and a resultant mixture is press-molded under a pressure of 1-4 ton/cm<2> to afford the aimed molded coal.

Description

Detailed Description of the Invention "Field of Industrial Application" The present invention relates to a method for forming low-grade coal using vegetable fibers, and in particular, to a method for forming low-grade coal using plant fibers, and in particular, a method for forming low-grade coal using plant fibers, and in particular, a method for forming low-grade coal using plant fibers. The present invention relates to a method of forming low-grade coal using vegetable fibers suitable for obtaining briquette coal with extremely high crushing strength.

``Conventional technology J Conventionally, the binders used in the production of briquette coal include organic materials and inorganic materials. Typical organic materials include pitch, tar, molasses, starch, and various resins. Cement and the like are known as inorganic materials, and various attempts have been made to use these alone or in combination to obtain briquettes with excellent combustibility and high crushing strength.

``Problem solved by the invention 1 However, it is known that the conventional method of using an inorganic material as a binder deteriorates combustion as the inorganic material has a calorific value of 0.

In addition, when organic materials such as tar, pitch, and various petroleum-based synthetic resins are used, these organic materials have a calorific value and do not inhibit combustion, but they may generate harmful gases during combustion or have poor heat resistance. As the combustion process progresses, the binder itself (various petroleum-based synthetic resins, molasses, etc.) melts and the briquettes crumble or dissolve, blocking the gaps in the grate and causing unburned It is known that it has the drawback of falling directly under the grate.

In addition, a method has been proposed that uses only organic materials, such as wood powder made by drying and pulverizing waste wood or chips, and forming it under heat and high pressure. There are limits to the production of this flour, and it may be difficult to obtain raw materials unless you live in a certain region.

Furthermore, as a method using only organic materials, a method has been proposed in which unpulverized plant fibers are used as aggregate and heated and high-pressure molded, but this method involves energy loss due to heating as well as the above. Although it has good ignitability because it contains a large amount of vegetable fiber, it has the disadvantage that it burns out in a short time.

In addition, the conventional method of using organic and inorganic materials in combination, which uses wood flour or powdered plant fibers made by drying and pulverizing waste wood/chips, and cement as a binding material, is a method that uses curing and drying after molding. It requires processes such as drying, takes a long time to produce, and has the disadvantage of requiring a large amount of energy for curing and drying.

In particular, in the method of using both organic and inorganic materials, the amount of powdered vegetable fiber is increased to approximately 60% by weight, and the amount of cement used is reduced as much as possible (approximately 10% by weight).
Recently, the method of drying has been attracting attention, but this method requires much longer drying time (requires a large amount of drying energy loss).
It had the disadvantage of being a fuel with poor fire retention, burning out in a short period of time.

That is, lignite and brown coal, which are numerically referred to as low-rank coal, have low coalification, contain a large amount of humic acid and sulfur, and have a large content soluble in aqueous alkaline solutions. As shown in Table 1, Turkish domestic lignite A imported to Japan (calorific value 4190Kcal/K
g), B (calorific value 5120 Kcal/Kg), and C (calorific value 4430 Kcal/Kg) were ground to a size of 1 mm or less, and mixed with 2.5 times the weight of water t and f.
After stirring and measuring the pH after 30 minutes, it was found that A=
2.8. B=4.9. A result of C=6.1 was obtained. A
Lignite is strongly acidic, and any type of binder is not effective. When using type A alone, a molding test was conducted using cement as a binder, but the strong acidity hindered the reaction of the cement and the strength suitable for handling could not be obtained. There wasn't.

In addition, lignite B was easily molded using cement as a binding material, but as shown in Table 1 of the appendix (raw coal ash content 18.51
%, calorific value 5120 Kcal/Kg, while briquette coal has ash content of 28.93% and calorific value 4280 Kcal/Kg.
K g, and the combustion test results show that the boiler efficiency is raw coal 7.
Compared to 8%, the briquettes had a lower value of 69.3%. Lignite C has an ash content of 14.82% and a calorific value of 4.430 Kc.
The quality of lignite (al/Kg) was medium, but it had extremely strong heat absorbing properties, and when cement was used as a binder and mixed with water, it absorbed water and swelled, inhibiting the hydration reaction, making it difficult to cure and When drying, it shrinks and becomes brittle with many large cracks, and the crushing strength of the briquette is B, lignite 45kgf.
However, it was only 3° OKgf, which was not suitable for handling.

In addition, the briquette C in Table 1 of the appendix refers to the briquette charcoal produced by the method of the present invention
Corn stalks 16.2% 9 Coal 73.3% (C raw coal), molasses 5%, slaked lime 3%, added water 2.5% and molded under pressure (3 ton/cIT If) .

Purpose: Therefore, the present invention was made in view of the above drawbacks, and uses a conventionally known vegetable fiber as a binder and a reaction product of molasses and slaked lime, which has not been used in the past, and has a high crushing strength. It is an object of the present invention to provide a method for forming low-grade coal using vegetable fibers that has good ignitability and combustibility, does not generate harmful gases, and furthermore can obtain briquette coal that does not melt or crumble unburned during combustion. This is the purpose.

"Means for Solving the Problems" In accordance with the above-mentioned object, the structure of the present invention as summarized in the above-mentioned claims, in order to solve the above-mentioned problems, as a first step: Pulverized charcoal obtained by pulverizing low-grade coal of 1/Kg or less to a size of 3 mm or less, and 10 to 30% by weight of vegetable fibers such as grains, vegetables, or weeds are dried and pulverized to a size of 3 mm or less. Vegetable fibers crushed into grains, slaked lime with a weight ratio of 3 to 5%, and a weight ratio of 3 to 8% with a weight ratio of 6 to the slaked lime.
In the second step, the crushed charcoal prepared in the first step, vegetable fiber, and slaked lime are mixed, and then the molasses prepared in the first step is mixed and stirred. The slaked lime and molasses are reacted to form a mixed raw material powder, and in the third step, the mixed raw material is press-molded at a pressure of 1 to 4 tons/crn. There it is.

``Function'' The method of forming low-rank coal using plant fibers of the present invention exhibits the following functions.

First, as in the past, mixed plant fibers are smuggled between coal powders by being pressurized and crushed, changing the overall tissue structure to a dense one, and exhibiting a binding effect (binder effect). It is known that the binder effect of this vegetable fiber is extremely strong, and furthermore, it does not generate harmful gases during combustion and has the effect of improving ignitability and combustibility.

However, the use of only vegetable fibers has the disadvantage that, as mentioned above, the ignitability is good if the amount of vegetable fibers is increased, but it burns out in a short time. Since there are many regions where such quantities are not available, it is not realistic to increase the contamination rate unnecessarily.

Therefore, in the present invention, a reactant of molasses and slaked lime is mixed together with vegetable fiber. That is, when the crushed charcoal prepared in the first step, vegetable fiber, and slaked lime are mixed, and the molasses prepared in the first step is further mixed and stirred to cause the slaked lime and molasses to react, calcilum tri・Saccharide (C+□H*wO□) s ' Ca O is produced, and this calcium tri-saccharide has strong viscosity (before solidification), resistance to water, poor water solubility, and high heat resistance strength. It has high quality.

In addition, when slaked lime and molasses are reacted, calsulam,
Di-saccharide (C+xHzgO++) * ・Ca O is also considered to be produced, and this calcium di-saccharide is also highly viscous, somewhat resistant to water, and has high heat-resistant strength. Calsulam di-saccharide is produced when the water content is high, and in molasses with a low moisture content, calsulam tri-saccharide is mainly produced (in this application, calsulam tri-saccharide and calsulam di-saccharide are included) A reaction was observed in which Ca-carbohydrate conjugates) were produced.

Therefore, Ca, which is a reaction product of this molasses and slaked lime,
The carbohydrate conjugate will act as a binder.

Specifically, in cases where vegetable fiber is weak (for example, beet pulp) or in areas where it is difficult to obtain vegetable fiber, it is necessary to reduce the amount of vegetable fiber to 10% or less. In this case, as a reinforcing agent, slaked lime is reacted with molasses (calorific value is 2800 Kcal/Kg at 12% water content) and mixed to form a Ca/carbohydrate bond with strong heat resistance and low water solubility, and the crushing strength is improved compared to plant fiber alone. 4 than that of
It is possible to amplify the signal by a factor of 10 to 10 times.

The crushing strength of conventional briquette coal is usually 50 to 6 when lying on its side.
0 Kgf, but by mixing Ca/carbohydrate conjugates, in the case of pressure molding at 3t/crn", the thickness is 20 mm and the horizontal area of 16.6 crn" is 40gr (the shape of the molded coal is the diameter It has a cylindrical shape of 46 mm and a thickness of 20 mm) and has a gf of over 4000.

Another function of the Ca-carbohydrate conjugate is to fix it in the residual ash as CaSO4, which is the sulfur content in coal, in small combustors such as stoves during combustion, and to suppress its release into the atmosphere as much as possible. (However, in high-temperature combustors such as boilers with a temperature of 1200 degrees or higher, the suppression effect decreases to about 40%.
(See table) Coal usually contains 0.5 to 1.5% sulfur depending on the coal production area, and low-rank coal in particular may have a high sulfur content of 2 to 4%. (Some of them are over 6%). These sulfur contents become SOl when burned, and become a gas harmful to the human body and the environment. Therefore, conventional briquette manufacturers have added slaked lime as a desulfurization agent. The Ca-carbohydrate conjugate used as a reinforcing binder in the present invention is CaO
Because it contains CaSO, it reacts with SO during combustion to form CaSO.
4, the sulfur content is fixed in the same way. (Comparing the combustible sulfur of briquette C in Table 1 with raw coal C) In other words, the Ca/carbohydrate complex of the present invention has both a strong binder action and a desulfurization action.

If the sulfur content of pulverized coal is low, it is economical because it is formed using only large amounts of inexpensive agricultural waste and plant fibers such as weeds without using other binders; The amount of sulfur released into the atmosphere is relatively small depending on the amount of sulfur in the mixture, so even in high-temperature combustion at 1200 degrees Celsius or higher, such as in large-scale combustion equipment such as boilers, the amount of sulfur released into the atmosphere is small.

When the 8% content of powdered coal is high, it is more advantageous to mix Ca-carbohydrate conjugate in addition to vegetable fibers, which also serves as a reinforcing agent.

That is, this production method has the advantage that it can be adapted to the sulfur content of raw coal, the calorific value, etc. by adjusting the relative increase or decrease of the two types of binders. However, slaked lime must be at least 60% of the amount of molasses by weight, and if it is less than 40%, the heat resistance is weak, and when molasses is used alone as a binder, unreacted free molasses will melt during combustion, such as in molded coal. Be careful, as the briquettes may lose their shape and fall under the grate while still burning.

“Example 1 Next, the present invention will be described in detail as follows.

First, the present invention is carried out as a first step.

■ Pulverized coal made by pulverizing low-grade coal with a calorific value of 5500 K cal / K g or less into a size of 3 mm or less,
■ 10 to 30% by weight of vegetable fibers obtained by drying plant fibers such as grains, vegetables, or weeds and pulverizing them to a size of 3 mm or less, and ■ 3 to 8% by weight of the above slaked lime. and molasses having a weight ratio of 60% or more.

Next, as a second step, the crushed charcoal prepared in the first step, vegetable fiber, and slaked lime are mixed, and the molasses prepared in the first step is mixed and stirred to cause the slaked lime and molasses to react. Promote mixed raw material powder and eggplant.

In this second step, molasses may be mixed at the same time as the pulverized coal, plant material #lH1, and slaked lime; however, the slaked lime should be mixed first, and after the slaked lime has thinly adhered to the surface of the coal. It is desirable to mix molasses because it makes mixing uniform and facilitates reaction. Also, if necessary, water is added for the reaction between slaked lime and molasses. If the crushed charcoal contains water,
It is not necessary to add this water if there is water attached to the pulverized coal (water is often added to prevent the coal from exploding or spontaneously igniting) or if the molasses has a high water content, but the weight ratio When the water content is adjusted to about 2.5%, the production of the above-mentioned R. trisaccharides is efficient, and furthermore,
By adding this water, it was possible to obtain a more reliable and stable reaction by dissolving the molasses with the desired amount of water and mixing it, rather than pouring water into the mixed raw material flour before mixing the molasses. However, once the reaction between slaked lime and molasses is complete, it will solidify.
In the present application, reaction promotion refers to promoting the reaction just before solidification begins.

Furthermore, in the present invention, as a third step, the mixed raw material is pressure-molded at a pressure of 1 to 4 tons/crn'. This third step is conventionally known. The shapes formed by this pressure are billow-shaped, egg-shaped,
Although the almond-shaped portion may be formed into any suitable shape, in this example, it was formed into a cylindrical shape with a diameter of 48 mm and a thickness of 20 mm.

The specific examples are shown in Table 2, but the table also includes comparative experimental examples marked with an asterisk (*) in the remarks column, so this comparative relationship will be explained below.

Examples 1 to 3 in Table 2 are follow-up examples of the conventional method and serve as a basis for comparison.
0Kcal/Kg), add corn stalks crushed to 3mm or less, and stir with a mixer for 7 minutes (20O
r pm), then a molded coal weighing about 40 g was obtained using a molding machine at a pressure of 3 tons/crn'. As a result, it was found that it is desirable to mix 25% or more of vegetable fiber, and that with about 10%, crushing strength suitable for handling cannot be obtained.

Therefore, as a fourth example, in order to compare with the second example, 16.2% of dried corn stalk powder and 3% of slaked lime were added to 73.3% of the same low-grade coal as above, and stirred with a mixer for 5 minutes. After coating the surface of the coal and vegetable fibers with slaked lime, add 5% molasses dissolved in 2.5% water and mix for another 10 minutes (if you mix for more than 20 minutes, the reaction between molasses and slaked lime will quickly solidify. (This makes molding difficult) to accelerate the reaction between molasses and slaked lime. When molded using the conventional method under the same pressure conditions, the resulting briquettes had a crushing strength of 140 kgf in the vertical direction and 4000 kgf in the horizontal direction.
There was no deformation.

That is, the intensity was amplified nearly nine times that of the third example.

Similarly, the fifth example is for comparison with the third example, in which 10% dry corn stalk powder and 3% slaked lime were added to 79.5% of the same low-grade coal, and the mixture was stirred for 5 minutes with a mixer. After coating the surface of coal and vegetable fibers with slaked lime,
Add 5% molasses dissolved in 2.5% water and add 1.
The mixture was mixed for 0 minutes to accelerate the reaction between molasses and slaked lime. When the briquettes were molded using the conventional method under the same pressure conditions, the resulting briquettes did not deform even when the crushing strength was 83 Kgf in the vertical direction and 4000 Kgf in the horizontal direction. That is,
The intensity was amplified nearly four times that of the second example.

The twelfth example consists of the first to third examples in which the tissue structure of plant fibers was instantly transformed and altered into a dense material under high pressure, and the reinforcing binder was made by adding 5% molasses and 3% slaked lime. C
a- In order to compare with the products of Examples 4 to 11 in which carbohydrate conjugate was added and molded, low-grade powdered charcoal with 81.5
%, 10% molasses, 6% slaked lime, and 2.5% water were mixed in a mixer for 15 minutes, and then mixed at 1.0 ton/crn' (
If the pressure is high, molasses leaks out, so a pressure of 1.0 ton/crn' was adopted as the pressure at which almost no leakage was observed). The crushing strength of the molded product is 29.3K in the vertical direction.
gf, horizontal direction was 1650Kgf. As a result, it is better to use pressure molding using a reinforcing binder of plant fiber and Ca-carbohydrate binder at the same time than to use vegetable fiber and Ca-carbohydrate binder as binders alone. It was found that a synergistic effect (as a binder) was observed and the crushing strength was greatly amplified. Although not stated,
89.5% of the same powdered charcoal, 5% molasses, 2.5% added water, and 3% slaked lime were mixed in a mixer for 15 minutes and molded, but the strength was weak and a molded product could not be obtained. It has been found that low-grade coal cannot be molded unless vegetable fibers are used as a binder, and if molasses is less than 5 to 6%, lime is not effective as a binder even if lime is used.

(It is possible to use cement with a high ash content, but the combustibility becomes extremely poor due to the addition of ash such as cement and lime to the high ash content.) , - Heat-resistant strength obtained by using agricultural waste such as wheat straw, rice straw, vegetable fibers such as vegetable trees and weeds as binding materials for boat fishing, and reacting slaked lime with molasses as a reinforcing binding material. Because the high-pressure molding is performed with the addition of a strong binder, the calorific value does not decrease significantly even when low-grade coal is used, and briquette coal with extremely high crushing strength can be produced at the same time as molding, making it easy to cure, dry, etc. Heating heat source/
It is possible to provide a method for forming low-grade coal using vegetable fibers, which does not require any equipment and has little time loss in production time, thereby significantly reducing production costs.

In addition, the present invention has the following advantages: By mixing plant fibers,
It has excellent combustibility and ignitability, and also has the effect of suppressing smoke generation during combustion.

Furthermore, a noteworthy effect of the present invention is that slaked lime is mixed in, and this slaked lime produces a binder with strong heat resistance when reacting with the molasses mentioned above.It also has low hygroscopicity, and when burned, this lime content produces SOx. It is possible to provide a method for molding low-grade coal using plant fibers, which can produce molded coal that suppresses the generation of gases harmful to the human body.

Furthermore, only low-grade coal is produced, and it is difficult to dispose of agricultural waste, causing air pollution by burning axes after harvesting.On top of that, in order to secure daily fuel, it is unavoidable to cut down primeval forests, causing environmental damage. There are quite a lot of areas where people are forced to do this, and it is believed that the present invention will have an immeasurable effect on killing two birds with one stone for these areas.

Claims (1)

[Claims] As the first step, 3 mm of low-grade coal with a calorific value of 5500 Kcal/Kg or less is used.
Pulverized coal crushed to the following size and 10 to 30 in weight ratio
% of vegetable fibers such as grains, vegetables, or weeds are dried and crushed to a size of 3 mm or less, 3 to 5% of slaked lime by weight, and 3 to 8% of by weight. , the weight ratio to the above slaked lime is 6
In the second step, the crushed charcoal prepared in the first step, vegetable fiber, and slaked lime are mixed, and then the molasses prepared in the first step is mixed and stirred. The reaction of the slaked lime and molasses is accelerated to form a mixed raw material powder, and the third step is to pressurize the mixed raw material at a pressure of 1 to 4 ton/cm^2. Forming method for grade coal.