JPH06184571A - Production of composite solid fuel of coal with vegetable matter, and composite solid fuel - Google Patents

Abstract

PURPOSE:To provide a process for producing a composite solid fuel which comprises coal and vegetable matter and is decreased in the amt. of sulfur oxides in the flue gas. CONSTITUTION:In a process for producing a composite solid fuel through compression molding of a starting material mixture of a coal powder with 20-25wt.% vegetable matter powder, slaked lime as a desulfurizing agent is added in such an amt. that the molar ratio of calcium in slaked lime to sulfur contained in the coal powder in the starting material mixture is in the range of 1.0 to 1.8. When the fuel is combusted, sulfur is fixed in ash by added slaked lime to greatly decrease the amt. of sulfur oxides contained in the flue gas.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a composite solid fuel of coal and plant matter and a composite solid fuel, in which a raw material prepared by mixing coal powder with vegetable powder is compression molded by a roll press to obtain a composite solid fuel. Regarding fuel.

[0002]

2. Description of the Related Art Conventionally, coal has been used for household heating stoves,
Alternatively, it is widely used as a fuel for boilers and the like, and the coal is generally in the form of lumps of about 50 to 100 mm in order to improve the air permeability. Further, pulverized coal having a diameter of several mm or less generated during mining, transportation and coal preparation processes is used as a coal briquette which is added with a binder and compression-molded by a roll press.

However, low-grade coal, which is widely stored and widely used all over the world, contains 15 to 30% by weight of ash, has a low calorific value, is poor in ignitability and sustainability, and has a large amount of soot and smoke. At the time of combustion, the ash is melted to form a large lump clinker, which deteriorates ventilation and reduces combustion efficiency.

As a measure against this, since the amount of smoke is small, and the ignitability and sustainability are good, 20 to 25% by weight of plant materials such as wood and bagasse are mixed with coal, and the mixture is molded with a high compression force. A mixed solid fuel of plant and plant matter (hereinafter referred to as a mixed solid fuel) is used.

The method for producing a composite solid fuel is as follows. A raw material prepared by drying and crushing plant matter such as coal, wood, bagasse, etc. to a size of several mm or less is further mixed with a pinder depending on the type of coal, and the outer peripheral surface of the roll is then mixed. Is formed by compression molding with a roll press called a briquette machine consisting of a pair of rolls facing each other in which pockets forming the briquette mother form are formed.

This composite solid fuel can use a wide range of coal as a raw material regardless of the type of coal such as brown coal, sub-bituminous coal, and bituminous coal, and especially when low-grade coal is used, the efficiency of cleaning is high, Since it is possible to effectively use waste wood, bagasse, etc. for plant raw materials, it is expected to be used.

[0007]

However, since the raw materials of the above-mentioned composite solid fuel, especially low-grade coal, contain a large amount of ash content of 15 to 30% by weight and sulfur content of 5 to 8% by weight, sulfur oxides are contained in the combustion exhaust gas. Since it is included in the air and is released into the atmosphere, there are problems such as causing environmental pollution.

Accordingly, it is an object of the present invention to provide a method for producing a composite solid fuel and a composite solid fuel which can reduce sulfur oxides in flue gas.

[0009]

A method for producing a composite solid fuel according to the present invention, which achieves the above-mentioned object, is a method in which coal powder is mixed with vegetable powder.
In a method for producing a composite solid fuel in which a raw material mixed with 0 to 25% by weight is compression molded by a roll press, the molar ratio of calcium to sulfur contained in the coal powder in the raw material is in the range of 1.0 to 1.8. The amount of slaked lime is added as a desulfurizing agent, and the composite solid fuel has a plant powder of 20 to 30% by weight in the coal powder and a molar ratio of calcium to sulfur contained in the coal powder of 1.0. ~ 1.8
The raw material mixed with slaked lime in the range of is compressed and molded by a roll press.

Concretely, several meters obtained by drying and crushing coal
A raw material obtained by mixing 20 to 25% by weight of wood, bagasse, and the like with coal powder of m or less and plant powder of several mm or less obtained by pulverizing the powder has a molar ratio of calcium to sulfur contained in the coal powder. Slaked lime is added as a desulfurizing agent in an amount in the range of 1.0 to 1.8. Next, this mixture is compression-molded by a roll press called a briquette machine consisting of a pair of opposed rolls having pockets that form a briquette matrix on the outer peripheral surface, and is, for example, an almond-shaped composite solid fuel having a volume of about 4 cm ^3. Manufacture briquette of.

In the composite solid fuel obtained by such a production method according to the present invention, calcium and sulfur react in the combustion process and about 80% by weight of sulfur in the raw material is fixed in the combustion ash. A large reduction of sulfur oxides released in the combustion exhaust gas is obtained, and no clinker is generated.

Next, the present invention will be described in detail by showing test examples.

This test was conducted in order to determine the optimum addition amount of slaked lime depending on the amount of sulfur contained in the coal of the composite solid fuel.

(1) Method for producing composite solid fuel Coal and wood (mixture of cypress and cedar) are used as raw materials, and respective elemental analysis values are shown in Table 1. Coal powder (about 3m
m) and 20% by weight of wood powder (about 2 mm or less), and a predetermined amount of slaked lime added as a desulfurizing agent.
Compression molding was performed at a pressure equivalent to HPa.

Table 1 Ash content Carbon Hydrogen Nitrogen Oxygen Total sulfur Coal powder 11.36 72.99 4.82 1.05 7.88 2.15 Wood powder 0.81 52.10 6.14 0.10 40.82 0.04 Total sulfur value includes sulfur content in ash

(2) Analysis of combustion exhaust gas Electric furnace heated to 300 ° C. (heating section length 300 mm)
Quartz glass combustion tube (inside diameter 28 m
m) is set, and while heating about 1.6 liters of air per minute for 20 minutes, the temperature is gradually raised to 700 ° C.
The gas produced by combustion by burning for 0 minutes and the surplus air were collected with a gas back, and sulfur dioxide was measured by a gas analyzer.

(3) Test Results As a result of burning the mixed solid fuel having a mixing ratio of wood powder of 20% by weight while changing the addition amount of slaked lime, the molar ratio Ca of calcium Ca in slaked lime to total sulfur S content in the sample Ca The results shown in FIG. 1 were obtained for the / S ratio and the immobilization rate of sulfur. As is clear from FIG. 1, the amount of slaked lime added increases linearly up to a Ca / S ratio of 1, and the immobilization rate reaches the maximum when the Ca / S ratio is around 1.2, reaching about 80%. When the Ca / S ratio is 1.8 or more, the immobilization rate is approximately constant at about 78%, and the addition amount of slaked lime as a desulfurizing agent is 1 to 1.8 in terms of the Ca / S ratio.
The range of is effective. When slaked lime is not added, the immobilization rate is about 28%.

[0018]

INDUSTRIAL APPLICABILITY In a method for producing a composite solid fuel in which a raw material obtained by mixing 20 to 25% by weight of plant powder with coal powder is compression-molded by a roll press, the molar ratio of calcium to sulfur contained in the coal powder is 1. It is possible to efficiently reduce the amount of sulfur oxides in the combustion exhaust gas by adding slaked lime in an amount in the range of 0.0 to 1.8 as a desulfurizing agent, and it is possible to largely avoid deterioration of environmental pollution. The ignitability is increased, soot and smoke are reduced, and since no clinker is generated, ventilation is maintained and combustion efficiency is improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between a Ca / S ratio and a sulfur immobilization rate.

Claims (2)

[Claims] 1. A method for producing a composite solid fuel comprising compression-molding a raw material, which is obtained by mixing 20 to 25% by weight of plant powder with coal powder, by a roll press, in a molar amount of calcium to sulfur contained in the coal powder in the raw material. The ratio is 1.0 to 1.8
A method for producing a composite solid fuel of coal and plant matter, characterized in that slaked lime in an amount within the range is added as a desulfurizing agent. 2. A raw material obtained by mixing coal powder with 20 to 30% by weight of vegetable powder and slaked lime in an amount in the molar ratio of calcium to sulfur contained in the coal powder in the range of 1.0 to 1.8. A composite solid fuel, characterized by being compression-molded by a roll press.