JPS6021605Y2 - Low NOx burner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a low NOx burner suitable for use with preheated air.

Boilers, heating furnaces, etc. often use air preheating to recover heat.

On the other hand, with a low NOx burner, when air preheating is used, the output amount is 200 to 300% compared to room temperature air.
It is known that preheating air to ℃ increases NOx levels several times.

For example, a two-stage air combustion burner in which the burner forms a primary combustion region and the insufficient amount of air is introduced into the rear of this region to form a secondary combustion region exhibits characteristics such as curve A in Figure 3. ,
8 in Figure 3 for a two-stage fuel/air two-stage composite two-stage combustion burner in which the primary burner forms the primary combustion area, and the secondary burner forms the secondary combustion area around or behind this area.
It exhibits curve-like characteristics.

The present invention proposes a low NOx burner suitable for use with preheated air, which combines energy savings through air preheating and low pollution with NOx emissions comparable to the NOx value of room-temperature air.

In order to achieve the above object, the present invention includes: a primary fuel nozzle; a primary air port having a traveling vane and provided along the circumference of the primary fuel nozzle; an annular secondary air port provided on the outer periphery of the annular secondary air port; and secondary fuel nozzles provided at appropriate intervals on the outer periphery of the annular secondary air port;
A tertiary air port is provided between the secondary fuel nozzle and maintains low-temperature combustion, and the primary burner is composed of the primary fuel nozzle and the primary air port. A secondary combustion area is formed on the outer periphery of the primary combustion area with a secondary burner consisting of the secondary fuel nozzle and the primary air port, and tertiary air is formed on the outer periphery of the secondary combustion area. It is designed to supply

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

In FIGS. 1 and 2, 1 is a combustion air supply chamber provided behind the burner tile 2, and communicates with a central opening 3 provided in the middle of the burner tile 2 through a primary air port 4. are doing.

Reference numeral 5 denotes a primary fuel nozzle, which is configured to supply fuel oil a1 from the central portion and steam from the peripheral portion, and penetrates the combustion air supply chamber 1 to the center of the primary air port 4. The tip thereof is arranged so as to face the outlet of the primary air port 4.

Reference numeral 6 denotes a swirling vane provided between the primary air port 4 and the primary fuel nozzle 5, which gives a swirling flow to the primary air C1 supplied to the combustion chamber 7.

These primary fuel nozzles 5 and primary air ports 4 constitute a primary burner.

8 is a burner tile 2 in the circumferential direction outside the central opening 3.
is an annular secondary air port provided in the combustion air supply chamber 1, the rear part of which is connected to the combustion air supply chamber 1, and a guide vane 9 is provided inside.
The secondary air C2 is rectified.

10 is a secondary fuel nozzle, which, like the primary fuel nozzle 5, is configured to supply fuel oil a2 from the center and steam b2 from the circumference, and further outside the secondary air port 8 in the circumferential direction, for example. Four of them are arranged at equal intervals to penetrate the combustion air supply chamber 1 and the burner tile 2, and their tips face the combustion chamber 7 near the surface of the burner tile 2.

These secondary fuel nozzles 10 and secondary air ports 8 constitute a secondary burner.

For example, 4 11 is provided at an intermediate position of the secondary fuel nozzle 10 of the burner tile 2 outside the secondary air port 8.
The rear portions of each of the tertiary air ports communicate with the combustion air supply chamber 1, and each has a damper 12 capable of adjusting the flow rate of the tertiary air C3.

13 is an air supply port provided in the combustion air supply chamber 1.

■The secondary burner forms the primary combustion area, the secondary burner forms the secondary combustion area around the primary combustion area, and tertiary air is further supplied around the area, so the combustion temperature This suppresses the generation of NOx by keeping the combustion temperature low and the combustion state slow.

By adjusting the opening degree of Dan-12, even when using preheated air, the N
Almost no increase in Ox value was observed.

C heavy oil (N content 0.21%) was used as the fuel at this time, and the combustion amount was 1. Qx 1Q7kcal/71, and the air ratio was 1.1.

Further, the flame (gas flame) dimensions and the smoke generation limit in the furnace (expressed in %% at the outlet) were as shown in Tables 1 and 2.

As can be seen from the table above, this low NOx burner has a slightly longer flame length in room temperature air and a higher percentage of smoke generation limit at the exit of the furnace, but when preheating the air to 300'C, the composite two-stage low NOx Excellent results were obtained, which were equivalent to those obtained when the burner was at room temperature, and the NOx value was low, as shown by curve C in FIG.

Furthermore, when compared with a normal air two-stage combustion burner, as is clear from FIG. 3, the increase in NOx due to air preheating is significantly smaller.

As described above, according to the present invention, low NOx combustion is possible even during air preheating, and it has energy saving properties due to air preheating, and low pollution properties such that NOx emissions are equivalent to the NOx value of room temperature air. This has led to the creation of a low NOx burner that also has the following features.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a cross-sectional side view;
FIG. 2 is a front view, and FIG. 3 is a characteristic diagram showing the relationship between air preheating temperature and NOx. 1... Combustion air supply chamber, 2... Burner tile, 4... Primary air port, 5...
Primary fuel nozzle, end...Secondary air port, 10...
... Secondary fuel nozzle, 11 ... Tertiary air port.

Claims (1)

[Scope of utility model registration request] a primary fuel nozzle, a primary air port having a swirl vane and provided along the periphery of the primary fuel nozzle, and an annular secondary air port provided on the outer periphery of the primary air port; , having secondary fuel nozzles provided at appropriate intervals on the outer periphery of the annular secondary air port, and a tertiary air port provided between the secondary fuel nozzles to maintain low-temperature combustion. A low NOx burner featuring