JPH08303756A - Melting and combustion device - Google Patents

Abstract

PURPOSE: To obtain a stable ignition temperature under a low air ratio and a low combustion load and keep a superior fluidized state of molten slag by a method wherein both a downstream side wall from a location near a secondary air feeding nozzle of a main combustion device and a wall of a sub-combustion device are provided with water-cooled means. CONSTITUTION: There is formed a throat 4 of which the cylindrical axis is in a cylindrical form and of which the lower end is narrowed into a reverse conical pyramid. There are provided a main combustion device 1 having a fuel feeding nozzle 2 directed toward a direction of the cylindrical axis at its upper part and a secondary air feeding nozzle 3 directed toward a tangential direction thereof and a sub-combustion device 5 in which an upstream end as seen from the flow of combustion gas is cooperatively connected to its lower end, a slag discharging hole 6 is arranged at a lower part of a downstream end and a flow passage where the combustion gas is reversed to flow toward an upper part of the downstream end and ascended. In this case, a header 9 for a water-cooled pipe 10 is arranged just near the secondary air feeding nozzle 3 installed near the upstream side of the win combustion device 1 while enclosing an inner side of the wall of the win combustion device 1. Then, the water-cooled pipe 10 is buried in the wall of the downstream side in its entire region.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a melting and burning apparatus for a fuel containing a non-combustible substance or a flame-retardant substance used in a coal-fired boiler, a sludge-fired boiler or the like.

[0002]

2. Description of the Related Art FIG. 2 and FIG. 3 show schematic views of different conventional melt combustion apparatuses.

In FIG. 2, the melt combustion apparatus is a main combustor 1,
Fuel injection nozzle 2, secondary air injection nozzle 3, throat 4, sub-combustor 5, slag discharge hole 6, generated gas duct 7,
It is made of refractory material 8.

On the other hand, the melting combustion apparatus of FIG. 3 is the same as that of FIG.
In addition to the reference numerals 1 to 8, a header 9 and a water cooling pipe 10 are provided.

FIG. 2 shows the entire furnace wall structure of the melt combustion apparatus as a fire wall structure, while FIG. 3 shows a water cooled fire wall structure as a whole.

[0006]

The above-mentioned conventional melt combustion apparatus has the following problems to be solved.

That is, in the case of the apparatus of FIG. 2, since the entire surface is a refractory wall structure, the heat loss is very small (5 to 10%), so that the combustion gas temperature in the main combustor 1 becomes higher than the melting point of the refractory material, Is eluted and mixed into the molten slag, the fluidity of the molten slag gradually deteriorates, and the slag discharge hole 6 is blocked.

On the other hand, in the case where the entire surface of FIG. 3 has a water-cooled refractory wall structure, the wall surface is self-coated with molten slag, so that the refractory material does not elute and the molten slag flows stably.
Main heat burner 1 due to large heat loss (20-30%)
The internal combustion gas temperature is 100 to 20 compared to the refractory wall structure of FIG.
There is a problem that the melting rate of ash decreases (approximately 10%) due to the decrease of 0 ° C. In addition, when the air ratio of the melting combustion device is reduced corresponding to the decrease in the gas temperature,
The fuel ignition point of the burner part (upper part of the main combustor 1) may fluctuate, and the combustion state may become unstable.

[0009]

As a means for solving the above-mentioned problems, the present invention forms a throat whose cylindrical axis is substantially vertical and whose lower end is squeezed in the shape of an inverted truncated cone, and which has the cylindrical axis direction in the upper part. A main combustor having a facing fuel injection nozzle and a tangentially facing secondary air injection nozzle, and the lower end of the main combustor is connected to the upstream end as seen from the flow of combustion gas and has a relatively horizontal cylindrical shape. And a secondary combustor having a slag discharge hole at the lower end of the downstream end and a flow path at which the combustion gas reverses and rises upward at the upper end of the downstream end. An object of the present invention is to provide a melt combustion apparatus characterized by comprising water cooling means for the wall provided on the wall downstream of the vicinity of the air injection nozzle and the wall of the sub-combustor.

[0010]

Since the present invention is constructed as described above, it has the following actions.

The fuel injected into the main combustor as the primary mixture from the fuel injection nozzle of the main combustor is ignited and melted, and then swirled by the secondary air from the secondary air injection nozzle which is oriented tangentially. Reach the wall.

That is, on the upstream side of the secondary air injection nozzle, most of the combustion gas (including fuel and unreacted char) is located slightly away from the wall surface. In addition, the air ratio before secondary air injection is as low as about 0.4, and the oxidation reaction temperature of the fuel is also low, and the refractory material temperature in this region is lower than the heat resistant temperature of the refractory material.

Therefore, even if only the upper part of the main combustor has a refractory wall structure without water cooling means, the above-mentioned problems such as elution of refractory material do not occur, and since there is no water cooling means, heat loss is reduced, and ignition is ignited. And the melting rate of ash are improved.

On the other hand, secondary air is mixed with secondary air to cause an active oxidation reaction (combustion), and the secondary air flow introduced from the secondary air injection nozzle in the tangential direction of the cylindrical main combustor Since the water cooling means is provided at the portion where the temperature becomes high due to the combustion gas swirling along the wall surface, that is, at the downstream of the vicinity of the secondary air injection nozzle, the wall does not become high temperature and does not elute.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG.

The same components as those of the conventional example are designated by the same reference numerals, and the description thereof will be omitted unless necessary.

FIG. 1 is a side sectional view of a melting and combustion apparatus according to an embodiment of the present invention. A header 9 for a water cooling pipe 10 is provided in the immediate vicinity of a secondary air injection nozzle 3 provided near the upstream side of a main combustor 1. A water cooling pipe 10 is provided so as to surround the inside of the wall of the main combustor 1 and is embedded in the wall downstream thereof.

The water cooling pipe 10 is not provided above the immediate vicinity of the secondary air charging nozzle 3, and the wall is composed only of the refractory material 8.

Incidentally, in comparison with the heat transfer area of the main combustor 1, the heat transfer area of the upper part where the water cooling pipe 10 is not provided is 15 to 3
0% is a standard. Other configurations are similar to those of the conventional example.

Since this embodiment is constructed as described above, it has only the advantages of the conventional example shown in FIGS. 2 and 3.

That is, since there is no water cooling pipe 10 on the wall above the inside of the ignition portion of the main combustor 1 and only the refractory material 8 is used, the heat loss is small, so that the ignitability and the melting rate of ash are increased.

In addition, from the upper end to the vicinity of the secondary air injection nozzle 3, the air ratio is as low as about 0.4 in the state before the secondary air is mixed, the oxidation reaction heat is not strongly generated, and the secondary air is the main combustion. Since there is no swirling flow generated by injecting in the tangential direction of the vessel 1, the main flow of the combustion gas is located far from the wall surface, so the temperature is lower than the refractory temperature of the refractory material 8,
Therefore, there is no concern that the refractory material 8 will elute.

On the other hand, since the water cooling pipe 10 absorbs heat at a portion where secondary air is mixed and a high temperature is generated, that is, a portion downstream of the secondary air injection nozzle 3, the wall does not have a high temperature.
The refractory material 8 does not elute.

As described above, according to this embodiment, an extremely ideal melting and combustion apparatus can be obtained in which heat loss is small, ash melting rate is high, and there is no concern that the refractory material 8 elutes to block the slag discharge hole 6. The advantage is that

[0025]

The present invention has the following effects because it is configured as described above.

That is, since a refractory wall, that is, a portion having no water cooling means and a portion having water cooling means are arranged in the furnace wall of the melt combustion apparatus in an optimum combination, a stable ignition point is obtained at a low air ratio and a low combustion load. To be

Further, the fluidity of the molten slag can be maintained in a good state.

Further, the flame temperature of the upper portion, that is, the burner portion is increased by about 100 ° C., and the ash melting rate of 5 to 10% is improved.

[Brief description of drawings]

FIG. 1 is a side sectional view of a melting combustion apparatus according to an embodiment of the present invention.

FIG. 2 is a side sectional view of a first conventional example.

FIG. 3 is a side sectional view of a second conventional example.

[Explanation of symbols]

 1 Main Combustor 2 Fuel Injection Nozzle 3 Secondary Air Injection Nozzle 4 Throat 5 Secondary Combustor 6 Slag Discharge Hole 8 Refractory Material 9 Header 10 Water Cooling Pipe

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number in the agency FI Technical display location F23G 5/24 ZAB F23G 5/24 ZABB (72) Inventor Hideaki Ota 5-717 Fukahori-cho, Nagasaki-shi No. 1 Mitsubishi Heavy Industries, Ltd. Nagasaki Research Institute (72) Inventor Akiyasu Okamoto 5-717-1 Fukahori-cho, Nagasaki City Mitsubishi Heavy Industries Ltd. Nagasaki Research Institute

Claims (1)

[Claims] 1. A fuel injection nozzle having a cylindrical axis with a substantially vertical axis and a lower end narrowed in an inverted frustoconical shape, and a fuel injection nozzle directed to the axial direction of the cylinder and secondary air directed to the tangential direction. The main combustor with the injection nozzle and the lower end of the main combustor are connected with the upstream end as seen from the flow of the combustion gas, forming a relatively horizontal cylindrical shape, and with the slag discharge hole at the lower end of the downstream end. In a melting combustor having a sub-combustor having a flow path in which combustion gas inverts and rises upward at an end, a wall downstream of the secondary air injection nozzle of the main combustor and a wall of the sub-combustor And a wall water cooling means provided in the melting combustion apparatus.