JPH05649Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a burner used in boilers, chemical industrial furnaces, etc. that use pulverized solid fuel.

Prior Art A conventional burner of this type is schematically shown in FIG.

In Fig. 3, 1 is a cyclone type separator, which converts a pulverized fuel mixture 8, which is a mixture of air, gas, etc., and pulverized fuel into a rich mixture 9, which contains a large amount of fuel with large diameter particles and a small amount of gas. and a lean air-fuel mixture 10 containing a large amount of small-diameter particle fuel and a large amount of gas. Reference numeral 2 designates a lean mixture discharge pipe into which the lean mixture separated by the separator 1 is introduced, and 3 represents a secondary air duct into which the secondary air 11 is introduced.

Numeral 4 denotes a rich mixture nozzle, which is provided so as to jet out the rich mixture 9 separated by the separator 1 downward into the furnace interior 14. Numeral 5 denotes a lean mixture nozzle, which ejects the lean mixture from the lean mixture discharge pipe 2 downward into the furnace interior 14.
The nozzle 6 is arranged next to the rich mixture nozzle 4 so as to jet the secondary air downward into the furnace 14.
The nozzles 4, 5, are arranged next to the rich mixture nozzle 4 so that the fuel is jetted downward to the
6 are installed surrounded by wind boxes 15, 16, and 17, respectively.

Reference numeral 7 denotes a lean mixture discharge amount regulator, which is provided in the lean mixture discharge pipe 2 and is used to adjust the discharge amount of the lean mixture. Note that 12 is a rich fuel flame in the furnace, and 13 is a light fuel flame.

Next, the operation of the conventional burner having such a configuration will be explained.

The pulverized solid fuel is supplied to the separator 1 as 8 streams of mixture with air from the pulverized solid fuel supply equipment (not shown).
sent to.

A swirling force is applied to the mixture 8 in the separator 1,
The separator 1 is divided into a downward flow going downwards and an upward flow going upwards, but the fine powder particles in the mixture 8 are separated from the mixture 8 by the centrifugal force generated by the swirling force and try to fall downward. Because of the force exerted, the downward flow side contains many large-diameter particles, has little gas, and has a high concentration of fine particles.
This results in a so-called rich mixture 9.

On the other hand, in the upward flow, the action of centrifugal force is weak, and a mixture of air and a group of fine powder particles of a minute particle size that could not ride on the rich mixture 9 forms a lean mixture 10 with a low concentration of fines.

The rich mixture 9 is injected into the furnace 14 from the rich mixture nozzle 4 provided at the lower end of the separator 1, and is ignited by an ignition source (not shown) to create a rich fuel flame 12.
form.

The lean mixture 10 passes through the lean mixture discharge pipe 2 and is injected into the furnace interior 14 from the lean mixture nozzle 5 provided at the tip of the lean mixture discharge pipe 2, forming a lean fuel flame 13 for combustion. be done.

Although the flow rate ratio of the rich mixture 9 and the lean mixture 10 is adjusted by the lean mixture discharge amount controller 7, it is not possible to adjust the fine powder concentration that governs the ignitability of the pulverized solid fuel flame.

Generally, the amount of air in the mixture 8 sent from the pulverized solid fuel supply equipment/the amount of pulverized solid fuel (hereinafter referred to as
A/C) is 2 to 3 (weight ratio),
If the theoretical air amount of pulverized solid fuel is 9Kg/Kg, the air amount supplied from rich and lean mixtures 9 and 10 is 22 to 33% of the theoretical air amount, which is 22% to 33% of the actual combustion air amount.
This corresponds to 18-27%. Therefore, since the amount of air supplied from the mixture 8 is insufficient for combustion of all the pulverized solid fuel, this insufficient amount is sent into the furnace 14 from the secondary air nozzle 6 as secondary air 11 by a blower (not shown). and then subjected to combustion.

Problems to be solved by the invention However, the conventional pulverized fuel burner described above has poor flame stability and difficulty in forming a stable flame because it is impossible to adjust the concentration of fine powder that controls the ignitability of the flame. It was hot.

Means for Solving the Problems In order to solve the above problems, the present invention aims to combine a pulverized fuel mixture, which is a mixture of gas and pulverized fuel, with a rich mixture containing many large-diameter particles and a small amount of gas. A cyclone separator that separates the lean mixture into a gas-rich lean mixture containing many particles, a lean mixture nozzle that spouts the lean mixture separated by this separator downward into the furnace, and this lean mixture. a rich mixture nozzle which is arranged in parallel with the nozzle and which injects the rich mixture separated by the separator downward into the furnace; and a rich mixture nozzle which is arranged in parallel with these nozzles and which injects secondary air downward into the furnace.
a pulverized fuel-fired burner having a secondary air nozzle, a concentration adjusting chamber provided between the rich mixture outlet of the separator and the rich mixture nozzle inlet, and adjusting an opening of the rich mixture outlet; The device includes a concentration regulator that adjusts the amount of rich mixture fed into the concentration adjustment chamber, and a primary air introduction pipe that introduces primary air into the concentration adjustment chamber.

Effect According to the above means, by mixing the rich air-fuel mixture and the primary air in the concentration adjustment chamber, the concentration is set to a concentration that provides good ignitability, and combustion is performed stably in the entire burner. can be set.

Embodiment An embodiment of the pulverized fuel-fired burner according to the present invention will be described in detail below with reference to FIGS. 1 and 2. Note that in these figures, the same parts as in FIG. 3 are denoted by the same reference numerals, so the explanation of those parts will be omitted.

The present invention provides a means for adjusting the concentration of the rich mixture between the rich mixture outlet of the separator of the conventional pulverized fuel-fired burner and the rich mixture nozzle inlet, and the main parts thereof are as follows: It is shown enlarged in FIG.

That is, an inverted cone-shaped concentration regulator 28 is provided at the outlet of the rich mixture 9 of the separator 1, and a concentration regulator operating rod 29 connected to the concentration regulator 28 is passed through the separator 1 to be connected to the outside. It has been pulled out. The concentration regulator 28 is surrounded by a cylindrical concentration adjustment chamber 30, the upper end of which reaches the rich mixture outlet of the separator 1, and the lower end of which reaches the rich mixture nozzle 4.
has reached the entrance. In this way, the concentration adjusting chamber 30 is located between the rich mixture outlet of the separator 1 and the inlet of the rich mixture nozzle 4 so as to surround the concentration adjusting device 28, and the concentration adjusting chamber 30 is It is provided in the wind box 15 for rich mixture. A primary air introduction pipe 31 is connected to this rich mixture air box 15 .

Next, the operation of the present invention configured as described above will be explained.

A mixture 8 fed into the separator 1 from a pulverized solid fuel supply facility (not shown) is separated into a rich mixture 9 flowing downward and a lean mixture 10 flowing upward.

A concentration regulator 28 is provided at the lower outlet of the separator 1 and can be operated up and down from the outside of the separator 1 via a concentration regulator operating rod 29.

The concentration regulator 28 has an inverted conical shape as shown in FIG. 2, and is mounted on a cylindrical portion below the separator 1. When the concentration regulator 28 is pulled upward by the operation stick 29, the discharge port area of the rich mixture 9 is narrowed, and the flow rate and A/C of the rich mixture 9 are reduced.
Conversely, pushing down will increase the flow rate of the rich mixture 9 and the A/C.

The burner of the present invention improves the ignitability of the rich fuel flame 12 and stabilizes the flame holding so that it can self-combust, and the light fuel flame 13 is made to maintain its flame holding by the rich fuel flame 12. , Therefore, the rich mixture 9 is adjusted to its A/C by the concentration regulator 28.
is reduced and sent to the concentration adjustment chamber 30 provided in the air box 15 for rich mixture.

The low A/C rich mixture 9 sent to the concentration adjustment chamber 30 is separately connected to the primary air introduction pipe 31.
Primary air 32 is blown in by a blower (not shown) through the concentration adjustment chamber 3.
After the A/C is adjusted to have good ignitability, the mixture is injected from the rich mixture nozzle 4 into the furnace 14, and ignited by an ignition source (not shown) to create a rich fuel flame. form 12.

That is, the primary air and pulverized coal in the rich mixture 9 blown into the furnace 14 from the rich mixture nozzle 4 are as follows:
It receives radiant heat from the surrounding flames and high-temperature slag adhering to the furnace side wall, ignites it, begins combustion, and forms a primary combustion zone. This primary combustion zone is mainly a combustion zone for volatile matter in the pulverized coal, and the volatile matter in the pulverized coal is evaporated from the pulverized coal particles.
CH ₄ , H ₂ , CO, etc. mix with oxygen (mainly in the primary air) diffusing from the surroundings and form a flame around the pulverized coal particles.

A secondary combustion zone is formed downstream of this primary combustion zone. This secondary combustion area is a char (carbon)
This is the combustion zone where the unburned gas and chiar flowing from the primary combustion zone are combusted by diffusion mixing with the secondary air 11 blown from the secondary air nozzle 6. The combustion of chir is the combustion of oxygen and carbon that diffuse through the surface of the chir or the pores in the chir, and the burnout time of the chir is more than 80 to 90% of the burnout time of the entire pulverized coal. occupy

From the above, the ignitability of the pulverized coal flame is controlled by the combustion conditions in the primary combustion zone, and the combustibility is controlled by the combustion conditions in the secondary combustion zone.

Therefore, in order to ignite a pulverized coal flame favorably, it is important to supply an optimum amount of primary air for igniting and burning the volatile matter generated from the pulverized coal.
Therefore, the present invention aims to supply the optimum amount of primary air for ignition and combustion of volatile matter generated from pulverized coal.
Primary air 32 is supplied to the rich air-fuel mixture 9 within the concentration adjustment chamber 30, and the concentration is thereby adjusted to a concentration that provides good ignitability, thereby achieving good ignition of a pulverized coal flame. be.

The theoretical air amount of pulverized coal is the amount of air required to burn the entire pulverized coal, that is, the volatile matter and the entirety of the char in the pulverized coal, and the amount of primary air equivalent to the theoretical air amount in the primary combustion area is If this is injected, the concentration of combustibles in the primary combustion zone becomes too dilute, making it even more difficult to ignite.

On the other hand, the lean mixture 10 is detected by the lean mixture discharge amount controller 7.
The flow rate and concentration are set to predetermined values by the concentration regulator 28, and the mixture is injected into the furnace 14 from the lean mixture nozzle 5 provided in the lean mixture air box 16 through the lean mixture discharge pipe 2. The light fuel flame 13 is ignited by an ignition source (not shown), but the flame holding is stabilized by the rich fuel flame 12.

Effects of the invention As detailed above, according to the invention, since the concentrations of both the rich and lean mixtures 9 and 10 can be set freely, the ignitability of the rich fuel flame 12 is particularly improved. A pulverized fuel-fired burner capable of stabilizing the combustion of the burner as a whole is provided.

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional view of an embodiment of the pulverized fuel-fired burner according to the present invention, Fig. 2 is an enlarged longitudinal cross-sectional view of the main part of the embodiment of the present invention shown in Fig. 1, and Fig. 3 is a longitudinal sectional view of a conventional burner. 1... Cyclone type separator, 2... Lean mixture discharge pipe, 3... Secondary air duct, 4... Rich mixture nozzle, 5... Lean mixture nozzle, 6... Secondary air nozzle, 7 ...Lean air mixture discharge amount regulator, 14...Furnace, 15...Wind box for rich air mixture, 16...Air box for lean air mixture, 17...Secondary air air box, 28...Concentration adjustment 29...Concentration regulator operation stick, 30...Concentration adjustment chamber, 31...Primary air introduction pipe.

Claims (1)

[Scope of utility model registration request] A cyclone separator that separates a pulverized fuel mixture, which is a mixture of gas and pulverized fuel, into a rich mixture containing many large diameter particles and less gas, and a lean mixture containing more gas and containing many small diameter particles, and this separation. a lean mixture nozzle that injects the lean mixture separated by the separator downward into the furnace; and a lean mixture nozzle installed in parallel with the lean mixture nozzle that injects the rich mixture separated by the separator downward into the furnace. In a pulverized fuel-fired burner having a rich mixture nozzle that blows out, and a secondary air nozzle that is juxtaposed with these nozzles and blows secondary air downward into the furnace, the rich mixture outlet of the separator and the rich mixture a concentration adjustment chamber provided between the mixture nozzle inlet and the concentration adjustment chamber; a concentration regulator that adjusts the opening of the rich mixture outlet to adjust the amount of rich mixture sent into the concentration adjustment chamber; and the concentration adjustment chamber. A pulverized fuel-fired burner comprising: a primary air introduction pipe for introducing primary air into the pulverized fuel;