JPS5914684B2 - Powdered fuel combustion equipment - Google Patents

Description

[Detailed description of the invention] The present invention relates to a powdered fuel combustion device.

Boilers that use pulverized solid fuel such as pulverized coal as fuel;
In combustion equipment such as garrothermal furnaces, the solid fuel usually contains a considerable amount of N, and the concentration of nitrogen oxides generated by combustion is extremely high. However, it is difficult to effectively suppress its occurrence using air two-stage combustion methods, etc., and currently there are three effective combustion methods.
This is a staged combustion method.

This allows primary combustion to occur at a low air ratio using primary fuel and primary air, and supplies only secondary fuel from the surrounding area in excess of the amount required to consume the oxygen remaining in the primary combustion exhaust gas. After the NOx generated in the primary combustion area is reduced to N2 in this area, secondary air is supplied from the outer periphery or downstream of the secondary combustion area. 3
This is a combustion method in which a secondary combustion zone is formed, where reducing substances such as CO2C02H20 are converted into completely pollution-free CO2 and C20.

At this time, if the fuel is powder, especially if its particle size is coarse, the supplied secondary fuel will not be decomposed and gasified rapidly and its concentration will not be uniform, making it difficult to effectively reduce NOx. Not possible.

There was a problem that unburned carbon still remained easily, resulting in a decrease in combustion efficiency.

The present invention eliminates these drawbacks and provides a powdered fuel combustion device that can significantly suppress NOx even when using solid fuel without reducing the combustion efficiency in the same way as when using liquid fuel.

An embodiment of the present invention will be described below based on the drawings.

In Fig. 1, 1 is a combustion furnace, and 2 is a 1 installed on the furnace wall.
A primary fuel nozzle, 3 is a primary air port that supplies primary air a from around the primary fuel nozzle 2, and 4 is a primary combustion area that supplies secondary fuel d from the wake to the secondary combustion area. The secondary fuel nozzle 5 formed is a secondary air port that supplies secondary air from the wake to the secondary combustion area to form a tertiary combustion area.

Reference numeral 6 denotes a coarse particle hopper, through which coarse particles of solid fuel are supplied as primary fuel C to the primary fuel nozzle 2 through a blower 7.

Reference numeral 8 denotes a fine grain hopper, through which solid fuel fine grains are supplied to the secondary fuel nozzle 4 as secondary fuel d through a blower 9.

Next, its operation will be explained.

For example, solid fuel with an average particle diameter of 80 μm is used, and this is divided at a classification point of 60 μm, and those below the classification point are stored in the fine hopper 8 as fine solid fuel, and those exceeding the classification point are coarsely divided. Coarse hopper 6 as granular solid fuel
The fuel is stored in the tank and sent to the secondary fuel nozzle 4 and the primary fuel nozzle 2 via blowers 9 and 7 so that each supply amount is 50%, and the combustion condition is that the combustion amount is 300 kg.
/h.

Further, as primary air, 0.3 times the amount of air required to burn all the fuel was supplied.

Combustion begins with primary combustion of coarse-grained primary fuel and primary air at a low air ratio, followed by fine-grained secondary fuel that is necessary to consume the oxygen remaining in the primary combustion exhaust gas. After the NOx generated in the primary combustion zone is reduced to N2 in the secondary combustion zone, NOx is supplied in excess of the amount to create a reducing atmosphere in the secondary combustion zone. Secondary air was supplied to form a tertiary combustion zone, where the reducing substances were combusted into completely non-polluting substances.

In this case, since the secondary fuel is fine particles, the secondary fuel is rapidly decomposed and gasified, its concentration becomes uniform, and NO
The reduction of x was effectively carried out.

In other words, as shown in Table 1, when the solid fuel was not classified, NOx was 180 ppm, but when it was classified as described above, it decreased to 150 ppm, and the concentration of nitrogen oxides became small. .

FIG. 2 shows another embodiment.

Reference numeral 10 denotes a fuel hopper, in which all solid fuel with an average particle size of 80 μm, for example, is stored and sent via a blower 11 to a classifier 12, where it is divided at, for example, a classification point of 60 μm, and fine particles are separated into secondary particles. The aggregate particles are supplied to the secondary fuel nozzle 4 as fuel, and the aggregate particles are supplied to the primary fuel nozzle 2 as primary fuel.

As described above, according to the present invention, the supplied secondary fuel is rapidly decomposed and gasified, and its concentration becomes uniform, resulting in NOx
It has the advantage of being able to effectively reduce the concentration of nitrogen oxides and improve combustion efficiency, and has extremely high industrial value.

[Brief explanation of the drawing]

FIG. 1 is an overall block diagram showing one embodiment of the present invention, and FIG. 2 is a main part block diagram showing another embodiment. 2...Primary fuel nozzle, 3...Primary air port, 4...
-Secondary fuel nozzle, 5...Secondary air port, 6...Coarse grain hopper, 8...Fine grain hopper, 12...Classifier.

Claims (1)

[Claims] 1. In a powdered fuel combustion device that performs three-stage combustion by supplying powdered fuel dividedly into primary and secondary fuel and dividingly supplying combustion air into primary and secondary air, A pulverized fuel combustion device characterized in that fuel is classified so that fine particle size fuel is used as secondary fuel and coarse particle size fuel is used as primary fuel. 2. Claim 1 characterized in that the powdered fuel is dividedly supplied by a classifier installed in the middle of the powdered fuel supply pipe.
Powdered fuel combustion device as described in section.