JPH02115603A - Burning device - Google Patents

Abstract

PURPOSE:To complete combustion without unburned component and smoking irrespective of reduction in combustion amount and to improve reduction of NOx by providing a plurality of sets of primary and secondary air nozzles together with a primary air port at the side of a pre-combustion furnace. CONSTITUTION:A burning device 7 having a burner 6 for spraying fuel oil (c) and a primary air port 2 for supplying part of primary air of theoretical air amount or less is disposed at the inlet side of a pre-combustion furnace 1. Primary air nozzles 3a, 3b for stepwisely supplying remaining primary air and a secondary air nozzle 4a for supplying part of secondary air are disposed at a suitable internal sequentially in a range that burning flame (b) becomes short from the burning device 7 side to a following stream. A secondary air nozzle 4b is opened at the outlet of the following stream side of the furnace 1 through a secondary air supply passage 10, and an annular partition plate 8 is interleaved. Since the secondary air can be supplied in a range that the temperature of flame does not excessively drop, its combustion can be completed without smoking.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a combustion device used in industrial boilers, chemical industry equipment, etc., and particularly to a combustion device with a pre-combustion furnace.

BACKGROUND OF THE INVENTION An existing technology for a two-stage gasification combustion apparatus and its combustion method is disclosed in Japanese Patent Publication No. 5B-7884.

That is, as shown in FIG. 5, this combustion apparatus is roughly composed of a pre-combustion furnace (chamber) O1, a reduction chamber 02, a main combustion furnace (chamber) 03, and a combustor 04.

Inside the combustor 04 are a burner 05, a flame stabilizer 06, and a swirl vane 0.
7 is provided, and a primary air port o8 is opened around this burner 05.

A pre-combustion furnace covered with a refractory material 09 is formed downstream of this combustor 04, and further downstream thereof a reduction chamber o2 and a main combustion furnace 03 are provided.

In addition, there is a secondary air port (nozzle) on the peripheral wall of the downstream part of the reduction chamber 02.
OlO is provided, and a cooling heat transfer surface 011 is provided inside its peripheral wall.
is formed.

Further, a partition plate 012 having a mixing function is disposed at the exit of the reduction chamber 02.

With this configuration, the combustion temperature can be sufficiently increased even when there is insufficient air under the atmosphere of the primary air port (or a mixed gas of primary air and inert gas) that is less than the theoretical amount of air supplied from the primary air port 08. Primary combustion is performed inside the pre-combustion furnace (chamber) Ol.

In the figure, the reference numeral ``a'' indicates the primary combustion flame, b' indicates the inverted combustion gas, and C indicates the fuel.

Thereafter, in a reducing atmosphere, the unburned fuel C' produced due to lack of air is gasified, and the reduction chamber 0 communicates with the pre-combustion furnace O1.
2 to promote the reduction of NOx (nitrogen oxides) in primary combustion.

By sucking in secondary air/(or a mixture of secondary air and inert gas) from the secondary air port 010 of the reduction chamber 02 at this stage, the main combustion furnace 03 placed downstream Performs complete combustion and suppresses the generation of NOx.

This makes it possible to significantly reduce the Now concentration even under high load combustion.

Problem to be Solved by the Invention However, when the amount of fuel C sprayed from the burner 05 is small, the flame length of the combustion flame that is formed is short, so the temperature near the secondary air port 010 as described above particularly decreases. do.

Due to this phenomenon, if the secondary air a' is supplied from the peripheral wall of the downstream part of the reduction chamber 02 provided with the secondary air port 010, there will be problems such as an increase in unburned content and smoke generation.

Moreover, if the temperature falls too much below the range for maintaining combustion, it becomes impossible to reduce the original NO+c concentration as two-stage combustion.

Means for Solving the Problems In order to solve such conventional problems, the present invention provides N.
In a combustion device that supplies primary air below the stoichiometric air amount to a pre-combustion furnace covered with a refractory material for a 0W low range, and supplies secondary air to a main combustion furnace that communicates with the pre-combustion furnace, the above-mentioned A method of installing multiple sets of primary air nozzles and secondary air nozzles together with a primary air port on the pre-combustion furnace side, and adjusting and using the supply amount of each primary and secondary air according to an increase or decrease in the amount of combustion. The combination of each primary or secondary air nozzle is selected.

According to this method of operation, a plurality of sets of primary,
Since a secondary air nozzle is provided, the supply amount of each primary and secondary air can be adjusted according to the increase or decrease of the combustion amount.
By using the primary and secondary air nozzles in combination (using them properly), it is possible to supply an amount of air corresponding to the flame length of the combustion flame and to achieve good combustion.

EXAMPLE Hereinafter, an example of the present invention will be described in detail with reference to FIGS. 1 to 4.

In addition, in these figures, in order to distinguish each primary and secondary air for convenience, the amount of air is indicated by symbols a and a', and the amount of air ejected from each of the supply air ports and nozzles of the primary air system is indicated by symbols a and a'. Each symbol an (n=1.

2, .
...). Further, in the figure, as an example, the number of sets of a plurality of air nozzles in the pre-combustion furnace is two sets of primary air nozzles 3a and 3b apart from the secondary air port 2, and a secondary air nozzle 4a, The case where two sets of 4b are arranged is shown. However, according to the present embodiment, these numbers of sets are those that are normally used, and are not limited to this.Of course, the number of sets can be increased depending on the combustion amount and the flame length of the combustion flame. good.

However, according to the present invention, as shown in FIG. 1, the fuel oil C
A combustor 7 is arranged, which consists of a burner 6 that sprays air into the pre-combustion furnace l, and a primary air port 2 that supplies air into the pre-combustion furnace l. In addition, in the figure, the code|symbol 8 shows a swirler.

Then, on the peripheral wall of the pre-combustion furnace 1, the remaining primary air a, +a3 (=a-aυ) is passed in stages from the combustor 7 side to the wake at appropriate intervals, and the combustion flame is a short flame. It is placed in a range where it can be.

In addition, at the outlet on the downstream side of this pre-combustion furnace I, strictly speaking, at the communication part with the main combustion furnace 9 disposed on the downstream side, secondary air a'1 (=a a'+ ) A secondary air nozzle 4b is bored through the supply passage IO, and an annular partition plate 8 having a mixing function for combustion gas (not shown) is interposed.

In this case, the injection angle of the secondary air nozzle 4b is set inward in the direction of the main combustion furnace 9, but according to this embodiment, from the viewpoint of combustion amount, flame length, etc. When the capacity of the secondary air nozzle 4b is large, the setting position of the secondary air nozzle 4b may be set to the t-flow inside the pre-combustion furnace 1.

On the other hand, these primary and secondary air nozzles 3a, 3b
.

The respective airs a and a' are supplied to 4a and 4b by distribution (distribution) and air volume adjustment using an air supply adjustment device (not shown) provided outside the pre-combustion furnace I.

Next, its effect will be explained.

In low NOx combustion using the pre-combustion furnace 1, in principle a high temperature reducing atmosphere is mainly created at the primary air port to reduce NOx. Subsequently, combustion is completed with secondary air a' to prevent smoke generation.

However, in the conventional case, as mentioned above, when the combustion amount is less than a predetermined value, the flame is short, so the flame temperature is low at the conventional secondary air nozzle position, and if the secondary air is supplied as it is, the secondary air The temperature of the surrounding area where the supply is made drops and smoke is produced.

Therefore, according to this embodiment, the secondary air nozzle 4a.

4b to the side of the pre-combustion furnace I and secondary air a' can be supplied within a range where the flame temperature does not drop too much, making it possible to complete combustion without generating smoke.

That is, depending on the increase or decrease in the amount of combustion, each primary and secondary air a, a'
and adjust the supply amount of each primary air port 2, primary air nozzle 3a, 3b or secondary air nozzle 4a.

By using any of 4b in combination, optimum combustion conditions can be achieved.

Below is the second part about adjusting the supply of primary and secondary air a, a'.
To explain specifically based on FIG. 4, FIG. 2 shows the total amount of primary air a, that is, the amount of air supplied from the primary air port 2 and the two sets of primary air nozzles 3 a and 3 b = j1+ +
The relationship between al + as and combustion amount [%] is shown, and the third
The figure shows the total amount of secondary air, that is, the secondary air nozzle 4a.

The relationship between the air amount a'=a'1+a' supplied from 4b and the combustion amount [%] is shown.

In addition, FIG. 4 shows (a): (primary air port in the primary air port 2)/(total primary air 11a), (b) = (primary air port in the primary air nozzle 3a)/(total primary air Quantity a), (c) = (primary air port in the primary air nozzle 3b,) / (total primary air jla), and (d): (secondary air amount a′υ in the secondary air nozzle 4a / (total The relationship between the air amount a/) and the combustion amount [%] is shown.

Now, in Fig. 2, the total amount of primary air a is always injected into the precombustion furnace l during combustion, but the combustion flame is at its maximum length, in other words, the combustion amount is 100%. Considering the case where the combustion amount gradually decreases from It will be planned.

However, in this case, within the range where the combustion amount is 25% or less, the value of the total primary air 1ta is kept constant at around 25% due to the relationship with the furnace internal pressure.

On the other hand, in FIG. 3, under the above usage conditions, the total secondary air amount a' is adjusted so as to gradually decrease together with the total primary air amount a in accordance with the reduction in the combustion amount.

However, in this case, within the range where the combustion amount is 25% or less, the value of the total secondary air amount a' is set to 0% due to the relationship with the furnace internal pressure and the flame length of the combustion flame.

However, even if the total primary and secondary air amounts a and a' shown in Figures 2 and 3 are adjusted in full view and adjusted to correspond only to changes in the combustion amount, it is obvious that good combustion conditions will not be obtained. Therefore, as shown in FIG. 4, especially in the pre-combustion furnace 1, the primary and secondary air nozzles 3a, 3 are removed in stages corresponding to the flame length of the combustion flame. b,
The air 1a, a' needs to be adjusted using 4a, 4b.

First, for (a) and (b) in the figure, the combustion amount is 100 to 5.
In the range of 0%, the primary air port 2 and the primary nozzle air 3a are used in combination, so that high-temperature reductive combustion is performed only with a and +.

At this time, since the flame chamber is formed sufficiently long, the secondary air a'v from the secondary air nozzle 4b provided on the partition plate 8
can complete the combustion.

Note that it goes without saying that Al is supplied in the entire combustion amount range of 100% to 0%.

Next, regarding (c) in the figure, when the combustion amount is in the range of 50 to 25%, the flame formed will be short, so the primary air a in (b) is stopped and the primary air nozzle 3b is replaced instead.
By using primary air a3 from with a,
Delays combustion time and lengthens flame.

At this time, even if the secondary air a/ is supplied from the position of the secondary air nozzle 4b (see FIG. 1), the air a'.

This is sufficient to complete low NOx combustion.

Furthermore, regarding (d) in the figure, in the range where the combustion amount is 25% or less, the flame that is formed is very short, so the primary air a3 in (c) is stopped and only a is used, and the secondary air is By stopping a't and using only a/, low NOx combustion can be reliably completed.

Effects of the Invention As detailed above, according to the present invention 1, the combustion amount is reduced and the flame length of the combustion flame is shortened, so that the temperature near the secondary air nozzle at the outlet on the downstream side of the pre-combustion furnace decreases. Even if the flame length decreases, the secondary air nozzle can be easily switched to another secondary air nozzle located upstream in the pre-combustion furnace in accordance with the flame length, and the secondary air nozzle can be continuously supplied with the primary air within the short flame length range. Since secondary air can be supplied, combustion can be completed without unburned matter or smoke, regardless of the reduction in combustion amount, and NOx reduction can be improved.

[Brief explanation of drawings]

Fig. 1 is a schematic structural sectional view showing an example of a combustion device according to the present invention, Fig. 2 is a diagram showing the relationship between the total amount of primary air and the amount of combustion, and Fig. 3 is a diagram showing the relationship between the total amount of secondary air and the amount of combustion. Figure 4 shows the relationship between the amount of primary and secondary air supplied from each primary or secondary air nozzle, which is used in stages according to the length of the combustion flame, and the amount of combustion. The figure shown in FIG. 5 is a schematic structural sectional view showing a conventional combustion device. l... Pre-combustion furnace, 2... Primary air port, 3 a, 3 b
...Each primary air nozzle, 4a, 4b ...Each secondary air nozzle, 5..Refractory material, 9..Main combustion furnace, a, al
~a3... Each primary air (amount), a + a l + a *.
・Each secondary sky (1 other person) Fig. 2 Bo trowel t (,9g) Fig. 3 Kyobi t (χ)

Claims (1)

[Claims] A combustion device that supplies primary air below the stoichiometric air amount to a pre-combustion furnace covered with a refractory material to reduce NOx, and supplies secondary air to a main combustion furnace that communicates with the pre-combustion furnace,
A plurality of sets of primary air nozzles and secondary air nozzles are provided on the side of the pre-combustion furnace together with a primary air port, and the supply amount of each primary and secondary air is adjusted according to an increase or decrease in the amount of combustion, and the amount of the primary and secondary air used is adjusted. A combustion device characterized in that a combination of each primary or secondary air nozzle is selected.