JPH07107448B2 - Operation method of gasification combustion device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for operating a gasification combustion device applied to an industrial boiler or the like.

2. Description of the Related Art As a conventional gasification combustion apparatus, there is one described in Japanese Patent Publication No. 58-7884.

According to this conventional example, as shown in FIG. 14, primary air (or a mixture of primary air and inert gas) 1 less than the theoretical amount of air flows into a wind box 3 through a duct 2 and swirl vanes 4 , And is supplied to the pre-combustion chamber 7 formed of the refractory material 6 having a concave curved surface through the primary air port 5.

On the other hand, the fuel (oil) 8 is sprayed from the burner 9 into the pre-combustion chamber 7, mixed with the primary air 1 and burned, and is flame-held by the flame stabilizer 10 attached to the tip of the burner 9 to carry out the primary combustion. Flame 11

Then, the unburned fuel generated due to the air shortage in the primary combustion inside the pre-combustion chamber 7 has a portion of the combustion gas generated by the primary combustion that is opposite to the combustion injection direction along the concave curved surface of the wall of the pre-combustion chamber. Inverted combustion gas 1 flowing in the direction indicated by the dotted arrow
The gas is gasified by promoting the mixing of gas and fuel by being entrained in the primary air port 5 of 1'and preheating and radiating heat of the refractory material 6 forming the precombustion chamber 7.

The combustion gas 12 containing the fuel gasified in the pre-combustion chamber 7 in this manner is then passed through the gas outlet 13 which is formed by narrowing and narrowing the rear peripheral wall of the pre-combustion chamber 7, and then the cooling heat transfer of the cooling pipe wall or the like. Face 14
Flowing into the reduction chamber 15 formed in step (1), where it is cooled by the reduction of nitrogen oxides and heat dissipation, and then the reduction chamber outlet 16
The structure 17 having a mixing function such as an orifice, that is, a mixing function, such as an orifice, allows the secondary air (or the secondary air supplied through the secondary air port 18 provided in the peripheral wall of the wake portion of the reduction chamber 15 to be supplied). Mixing with (mixture with inert gas) 19 is promoted to perform complete combustion in the main combustion chamber 20, thereby suppressing the generation of nitrogen oxides and significantly reducing NOx and dust. .

Problems to be Solved by the Invention However, such a conventional example has the following problems.

That is, if a wide range of combustion load is dealt with by only the primary air 1, the flow rate of the primary air 1 is small at low load,
Due to insufficient flow velocity and swirling force, flame 11 becomes elongated. This is because it is usual to design a cross-sectional view of the flow path of the primary air 1 passing through the inlet of the pre-combustion chamber 7 on the basis of a high load.

Therefore, a poor mixing state is formed in which the air around the flame 11 is rich and the central portion of the flame 11 is rich in fuel.
Therefore, a sufficiently uniform reducing atmosphere cannot be formed and the NOx concentration does not decrease. Also, since the combustion is slow, there is much soot and dust.

On the other hand, at high load, if a strong swirl is given only by the primary air, combustion vibration is likely to occur, the swirl strength cannot be obtained as desired, and the rapid mixing of the primary air 1 and the fuel 8 is just another step, and conversely. When the rotation is made weak, the combustion state becomes stable, but since the mixing becomes gradual, there arises a problem that the pre-combustion chamber 7 must be made large.

Further, in the conventional example, the reduction chamber 15 is
The effect of reducing x is not uniform, the effect is not recognized especially at low load, and the flame temperature is too low and the amount of soot and dust often increases.

Means for Solving the Problems The present invention has been made to solve the problems of the above-described conventional techniques, and a gasification combustion device includes a pre-combustion chamber covered with a refractory material and a pre-combustion chamber. A combustor attached to the inlet for spraying primary air and fuel into the pre-combustion chamber; a sidewall nozzle disposed near the inlet of the pre-combustion chamber to surround the inlet and capable of ejecting exhaust gas and primary air; An annular projection or annular recess formed at the outlet of the pre-combustion chamber, a main combustion chamber communicating with the pre-combustion chamber via the annular projection or annular recess, and a portion of the annular projection or annular recess near the main combustion chamber A secondary air ejection port for ejecting secondary air toward the main combustion chamber, a control valve for controlling the flow rates of the exhaust gas and the primary air, and a control valve opening degree for detecting the fuel flow rate. With a control device to The cross-sectional area of the flow path of the primary air that passes through the inlet of the pre-combustion chamber is defined as a low load standard.When the load is low, exhaust gas is supplied from the side wall nozzles of the pre-combustion chamber, or a small amount of primary air is supplied from a small number of the nozzles. Is supplied at high speed, or primary air is supplied only from the inlet of the pre-combustion chamber, while at the time of high load,
It is intended to provide a method of operating a gasification combustion apparatus, characterized in that residual primary air, which is insufficient with the primary air supplied from the combustor, is supplied from each sidewall nozzle of the pre-combustion chamber.

Action According to such a method of operating the gasification combustion device, the cross-sectional area of the flow path of the primary air passing through the inlet of the pre-combustion chamber is set to the low load standard and is made narrower than the normal high load standard. During loading, exhaust gas is supplied from the side wall nozzles of the pre-combustion chamber, a small amount of air is supplied at a high speed from a small number of the nozzles, or primary air is supplied only from the inlet of the pre-combustion chamber. On the other hand, when the load is high, residual primary air that is insufficient with the primary air supplied from the combustor is supplied from each sidewall nozzle of the pre-combustion chamber.

Therefore, by such means, a sufficiently fast flow velocity and swirling force can be obtained in the pre-combustion chamber even under a low load, and rapid mixing of primary air and fuel is possible, while a stable combustion state is achieved even under a high load. Rapid mixing is possible. Therefore, a uniform high-temperature reducing atmosphere is formed within a wide range of load changes, and the gasification / reduction reaction of the fuel is promoted, so that low NOx / low dust combustion is possible. Further, the pre-combustion chamber can be downsized.

Embodiments Preferred embodiments of the present invention will be described in detail below with reference to FIGS.

FIG. 1 shows a first embodiment of the present invention, in which a precombustion chamber 21 is covered with a refractory material 22, and a combustion (oil) 23 is provided inside the precombustion chamber 21 on the inlet side of the precombustion chamber. A combustor composed of an oil gun 24 sprayed on the inside and a swirler 26 for supplying the primary air 25a into the pre-combustion chamber 21 is arranged and attached in an air register 27. In this case, the primary air 25 passing through the inlet of the pre-combustion chamber 21
The flow passage cross-sectional area of a is set to the low load standard and is narrower than the normal high load standard.

A side wall nozzle 29 for ejecting the other primary airs 25b and 28 into the pre-combustion chamber 21 surrounds the pre-combustion chamber 21 near the entrance thereof, as shown in detail in FIGS. The primary air 25b and the exhaust gas 28 that have been formed are supplied in a swirling flow aiming at the vicinity of the ignition / flame holding portion of the flame 30.

Further, the main combustion chamber 31 is communicated with the outlet of the pre-combustion chamber 21, and an annular protrusion 32, which is preferably made of a refractory material, is provided in a communication portion between the main combustion chamber and the pre-combustion chamber 21. There is. Then, especially in the portion of the annular projection near the main combustion chamber 31, the fourth to fifth
As shown in detail in the figure, the refractory material 22 is cut out to form an annular recess 33.
An annular pipe 36 having a large number of secondary air ejection ports 35 for ejecting the secondary air 34 toward the main combustion chamber 31 is arranged in the annular recess. Further, the annular projection 32 is provided with a flame holding plate 37, as shown in detail in FIGS.

Further, in FIG. 1 again, a detector 40 for detecting the flow rate of the fuel 23 is provided in the fuel supply line, and the primary air 25a
Control valves 41a and 41b for controlling the flow rate of the respective primary air are provided in the respective supply lines of 25 and 25b, and the exhaust gas 28
A control valve 42 for controlling the flow rate of exhaust gas is provided in the supply line. An arithmetic and control unit 43 for controlling the opening of each of the control valves 41a, 41b and 42 based on the detection signal from the fuel flow meter 40 is provided, and 43a, 43b and 43c show the elements thereof.

Next, control of the control valves 41a, 41b, 42 by the arithmetic and control unit 43 will be described.

The fuel 23 is sprayed from the oil gun 24, primary air 25a and 25b are supplied into the pre-combustion chamber 21, and gasification / high temperature reduction combustion is performed with air having a theoretical air amount or less. Further, the secondary air 34 is supplied from a large number of spray ports 35 of the annular pipe 36 at the outlet of the pre-combustion chamber 21 and is completely combusted in the main combustion chamber 31.

Then, the flow rate of the fuel 23 is detected by the detector 40, and the control valves 41a, 41b, 42 are opened / closed by the operation signal of the arithmetic control elements 43a, 43b, 43c based on the increase / decrease in the detected value.

First, when the flow rate of the fuel 23 is small and the load is low, as shown in FIG. 8, under the control of the element 43a, a constant amount of primary air 25a is supplied until the load is about 10%, and the load is 10% to 40%. The primary air 25a is gradually increased to a certain degree, and the upper limit amount of the primary air 25a is supplied when the load is 40% or more.

The lower fixed amount refers to the amount of air required for ignition / flame retention and does not cause flashback, and the upper fixed amount refers to the amount of air that does not cause blow-off / flame retention instability.

Then, from the side wall nozzle 29, the primary air 25b and the exhaust gas 2
8 is supplied according to the load.

That is, when the exhaust gas 28 can be used, a constant amount of the exhaust gas 28 is supplied under the control of the element 43c as shown in FIG. 11 when the load is low up to about 40%. When the load is 40% or more, the exhaust gas 28 is stopped and the primary air 25b
As shown in FIG. 9, under the control of the element 43b, it is gradually increased as the load is increased. On the other hand, when the exhaust gas 28 cannot be used, as shown in FIG. 9, the primary air 25b is not supplied until the load is about 40%, and only the primary air 25a is burned. Then, when the load is about 40% or more, the primary air 25b is gradually increased.

The annular projection 32 provided at the outlet of the pre-combustion chamber 21 is an annular pipe.
The backflow of the secondary air 34 'ejected from 36 is prevented. Also,
Because of the flame holding plate 37, the shape of the combustion flame in the main combustion chamber 31 is stable. Moreover, since the annular protrusion 32 is provided in the vicinity of the annular recess 33, the gas flow is stagnationd and stable combustion can be performed.

According to the first embodiment described above, therefore, low NOx / low dust combustion can be performed over a wide range from low load to high load.

As a modification of the first embodiment, the secondary air ejection port 35 formed in the annular pipe 36 may be provided in the annular protrusion 32 as shown in FIG.

That is, the secondary air 34 is supplied to the main combustion chamber inside the annular protrusion 32.
An annular secondary air passage 36 ′ is formed as a means for supplying the secondary air 31 and a large number of secondary air jets 35 extending from the annular passage and opening toward the main combustion chamber 31 are formed.

FIG. 13 shows a second embodiment of the present invention, in which reference numerals 21, 22, 23, 24,
25a, 25b, 26, 40, 41a indicate the same elements as shown in FIG.

Further, 29a is the six side wall nozzles in the plural embodiments in which the primary air 25c is ejected from the side surface of the pre-combustion chamber 21, and 29b is the plural side nozzles in which the other primary air 25d is ejected from the side surface of the pre-combustion chamber 21 in the same manner. Two side wall nozzles, these side wall nozzles
29a and 29b are arranged near the entrance of the pre-combustion chamber 21 on the same circumference so as to surround the entrance.

Further, control valves 41c and 41d for controlling the flow rates of the respective primary airs are provided in the respective supply lines of the primary airs 25c and 25d.
Is provided. Then, based on the detection signal from the fuel flow rate detector 40, the arithmetic control device 53 for controlling the opening degree of each control valve 41a, 41c, 41d for the primary air 25a, 25c, 25d is provided, 53a, 53b and 53c shows the element. In addition,
29c is a header for supplying the primary air 25c.

Next, each control valve 41a, 41c, 41d by this arithmetic and control unit 53
The control of will be described.

First, similarly to the case shown in FIG. 8 described above, the primary air 25a is controlled by the element 53a to supply a fixed lower limit amount up to a load of about 10% and gradually increase to a load of about 10% to 40%. , Load 40
If it exceeds about%, a fixed upper limit is supplied.

The primary air 25d is a small amount of air, and the small number of nozzles 2
Supplied at high speed from 9b. In this case, the element 53b opens and closes the control valve 41d so as to gradually increase the primary air 25d until the load of the fuel 23 is small to about 40% and supply a constant amount above about 40% as shown in FIG. .

Further, the primary air 25c is supplied from a large number of nozzles 29a under the control of the element 53c, as in the case shown in FIG. 9 described above. That is, element 53c has a low fuel 23 load of 40%.
The control valve 41c is opened / closed so that the primary air 25c is not supplied up to about 40% and gradually increased when the load is about 40% or more.

According to the second embodiment described above, therefore, only the primary air 25d is used when the load is low, and the primary air 2d is used when the load is high.
Since 5c and 25d correspond to each other, a sufficiently strong turning force can be obtained in a wide load range, and a uniform reducing atmosphere can be formed at high temperature. Therefore, low NOx and low dust combustion is possible.

Effects of the Invention As described in detail above, according to the present invention, low NOx / low dust combustion is possible over a wide range from a low load to a high load, and since there is no reduction chamber, a wide range of load changes is possible. A uniform NOx reduction effect can be obtained over the entire range. Further, since the pre-combustion chamber can be simplified and downsized, effects such as low cost can be obtained.

[Brief description of drawings]

FIG. 1 is a flow conceptual diagram showing an example of a gasification combustion apparatus in which an operating method according to the present invention is carried out, FIG. 2 is a partially enlarged view of FIG. 1, and FIG. 3 is a III-III line of FIG. Sectional view, FIG. 4 is another partially enlarged view of FIG. 1, FIG. 5 is a view taken along the line VV of FIG. 4, and FIG. 6 is still another partially enlarged view of FIG. FIG. 7 is a view taken along the line VII-VII in FIG. 6 (FIG. 6 is a sectional view taken along line VI-VI in FIG. 7), and FIGS. 8, 9 and 10 are primary airs according to the present invention. FIG. 11 is a diagram showing the flow rate control characteristic of FIG.
FIG. 12 is a view showing a modified example of FIG. 1, FIG. 13 is a view showing still another modified example, and FIG. 14 is a sectional view showing a conventional gasification combustion device. 21 …… pre-combustion chamber, 22 …… refractory material, 23 …… fuel, 24 …… oil gun, 25a, 25b, 25c, 25d …… primary air, 26 …… swirler, 27 …… air register, 28 …… Exhaust gas, 29, 29a, 29b ...
… Side wall nozzle, 31… Main combustion chamber, 32… Annular protrusion, 33…
… Annular recess, 34, 34 ′ …… Secondary air, 35 …… Secondary air jet, 36 …… Annular tube, 36 ′ …… Annular passage, 40 …… Fuel flow rate detector, 41a, 41b, 41c, 41d ... Air flow control valve, 42 ...
… Exhaust gas flow control valves, 43, 53… Control device.

Claims (1)

[Claims] 1. A pre-combustion chamber covered with a refractory material, a combustor attached to an inlet of the pre-combustion chamber for spraying primary air and fuel into the pre-combustion chamber, and the pre-combustion chamber. A side wall nozzle which is arranged near the inlet of the combustion chamber and surrounds the inlet and is capable of ejecting exhaust gas and primary air; an annular projection or annular recess formed at the outlet of the pre-combustion chamber; and the annular projection or annular recess. A main combustion chamber that communicates with the pre-combustion chamber via a secondary air ejection port that ejects secondary air toward the main combustion chamber from the annular projection or annular recess near the main combustion chamber, and the exhaust gas and A control valve for controlling the flow rate of the primary air, and a control device for detecting the flow rate of the fuel to control the opening of the control valve, and the flow passage cross-sectional area of the primary air passing through the inlet of the pre-combustion chamber. Is set as a low load standard, and when the load is low, Exhaust gas is supplied from the sidewall nozzles of the combustion chamber, or a small amount of primary air is supplied at high speed from a small number of the nozzles, or primary air is supplied only from the inlet of the pre-combustion chamber, while high load is applied. Sometimes
A method for operating a gasification combustion apparatus, characterized in that residual primary air, which is insufficient with the primary air supplied from the combustor, is supplied from each sidewall nozzle of the pre-combustion chamber.