JPH0324968Y2 - - Google Patents

Description

[Detailed explanation of the invention] [Industrial application field] This invention suppresses and reduces NOX generation and
This relates to a burner that performs complete O ₂ combustion.

[Conventional technology]

As a general combustion method in conventional boilers and furnaces, fuel (oil gas, etc.) sprayed from a burner is supplied with a fixed ratio of fuel and air to meet the load requirements of the boiler and furnace.

[The problem that the idea aims to solve]

Therefore, the flame formed is the load (fuel supply amount)
The mixture of fuel and combustion air is constant in order to form a diffusion flame with a certain shape according to Since the flame shape is constant from the surface, the flame temperature is high and there is a limit value for NOX generation.

This invention changes the flame shape by adding temporal flow rate changes to the constant flame shape formed by the fuel and air supplied from the burner at a fixed ratio according to the load, and the pressure caused by the concentrated combustion with the combustion air. By reducing the amount of fuel, it promotes mixing and reduces O ₂ , contributing to energy saving. At the same time, by changing the shape of the flame over time during a constant load, the temperature inside the flame is equalized, and it also prevents excess fuel in the combustion chamber. Enables excess air to be burned alternately within a short period of time, promoting diffusion and mixing of combustion gas.
NOX and soot are suppressed, greatly contributing to pollution.
The purpose is to improve the efficiency of the boiler and furnace by making the temperature distribution inside the furnace uniform as the flame shape changes.

[Means to solve the problem]

The present invention was made to achieve the above object, and a nozzle is provided at the tip of a sprayer that penetrates the burner body, and a damper for air adjustment is installed in each of the primary and secondary combustion air supply passages. At the same time, a spray medium supply pipe and a fuel supply pipe are connected to the sprayer, and a branch pipe is connected to the fuel supply pipe via a solenoid valve. are each equipped with a regulating valve with a maximum flow rate set, and an electromagnetic operated valve is installed in the maximum flow side branch pipe to set the time for spraying the maximum and minimum fuel supply amount in a wave pattern using a cycle setting device. The gist is:

〔Example〕

Fig. 1 shows the spray state of the fuel of the present invention, where 1 is a normal burner body;
A sprayer 3 is provided to supply fuel, atomizing steam, and air so as to penetrate through the. The tip of this sprayer 3 is equipped with a nozzle 6 for atomization. On the other hand, combustion air is controlled by a damper 2 provided in the burner body and is supplied into the burner body. The ignition flame is held by a flame holder 5 and a burner throat 4 provided at the tip of the sprayer.

On the other hand, the fuel sprayed from the nozzle 6 is injected in the form of a so-called wavy spray, in which periods of high fuel and low fuel are repeated many times within a very short period of time, resulting in concentrated combustion. This is the spray group shown in the figure. In this spray group, a location with a large amount of fuel is indicated by 7, and a location with a small amount of fuel is indicated by 8.
In order to carry out this concentrated combustion, a pipe line consisting of a spray medium supply pipe 10 and a fuel supply pipe 13 shown in FIG. 6 is connected to the burner body.

The operation system for performing the wave-shaped spray combustion is the sixth one.
As shown in the figure. This embodiment performs wave-like spray combustion of liquid fuel using steam or high-pressure air as an atomization medium.
0 and is supplied to the burner sprayer 3 through a solenoid valve 11 and a pressure regulating valve 12.

On the other hand, fuel is supplied from a fuel supply pipe 13, passes through a solenoid valve 14, and is divided into two directions. 15,1
6 are flow rate control valves, and the control valve 15 is set so that the minimum flow rate shown in FIG. 2 flows. In addition, the adjustment valve 16 is set so that the flow rate obtained by subtracting the minimum flow rate from the same maximum flow rate (50%, 50% in Fig. 2) flows, and the opening degrees of these two adjustment valves are the same in response to load changes. The valves are linked to operate according to the opening ratio, and the opening ratio of each valve can be set freely.

The wave-like spray is generated by opening and closing the solenoid-operated valve 17 in the system, causing the spray of the flame 19 to wave-like.
Further, the wavy cycle time T1 in FIG. 2 can be arbitrarily set by the cycle setter 18.

Figure 2 is an explanatory diagram showing the principle of generation of wavy spray.
Minimum flow rate to maintain ignition at a given load
QM is always injected and the maximum flow rate QA within a certain time T
Determine the number of times. The time between the maximum flow rate and the next maximum flow rate, ie, the wave cycle time T1, is determined by the boiler, furnace shape, size, fuel type, and planned NOx value.

Further, in FIG. 2, as an example, the ratio between the minimum flow rate QM and the maximum flow rate QA is set to 50% to 50%, but this ratio is also determined by the NOX value.

Also, the rated flow rate during this wavy spray is QC.

FIG. 3 shows an injection diagram of a conventional burner. Also the fourth
The figure is a comparison diagram of the combustion flame during the wave-shaped spray explained in FIG. 2. In a conventional burner, the combustion amount is constant at a certain load due to the constant flow rate, so the flame shape is constant regardless of time, as shown in Figure 4A, whereas the wave-like spray flame has a constant flame shape A at the maximum flow rate. As shown in Figure B, the flame C at the minimum flow rate becomes approximately 1/2 of the flame B at the maximum flow rate, as shown in Figure C, and this flame pattern changes within a very short time during the wave-like cycle time. By setting T1, the repeated combustion gas promotes diffusion and mixing, and as a result contributes to low O ₂ and NOx suppression.

Figure 5 explains the principle of NOX suppression using wave-like spray.The vertical axis shows the amount of NOX generated and the horizontal axis shows the excess air coefficient.Generally, when burning liquid fuel, the amount of NOX generated is approximately 1.2 when the excess air ratio is around 1.2. The amount generated decreases as the excess air ratio decreases. Conversely, when the excess air ratio becomes larger than 1.2, it tends to decrease.

In the case of slightly wavy spray combustion, the maximum flow rate in Figure 2
If the ratio of QA and minimum flow rate QM is 50% and 50%, the amount of combustion air supplied from the burner is the same, so the excess air coefficient at maximum flow rate is approximately
The excess air coefficient at the minimum amount of 0.8 is 1.65, and both are diffused and mixed in the furnace, and the excess air coefficient becomes a constant value. Note that this excess air coefficient can be freely set by changing the maximum and minimum flow rate ratios.

The relationship between the excess air coefficient and NOX generation is shown in Figure 5: B at excess air coefficient 0.8, C (maximum value) at 1.2, and D at 1.6.

In this case, if the final excess air coefficient is set to 1.1, the NOX value A generated in conventional burner combustion is
On the other hand, the NOX generation value in the combustion method of the present invention is A', and the difference E is suppressed compared to the conventional burner.

[Effect of idea]

According to the present invention, the combustion supplied to the sprayer in the burner body is controlled via a branch pipe designed to supply a minimum flow rate and a maximum flow rate, and a cycle setting device is used in this branch pipe for supplying the maximum flow rate. Because it is equipped with an electromagnetic valve, the fuel can be supplied in a concentrated manner, i.e., wavy spray is used for combustion, which results in lower NOx, lower _O2 , and lower furnace temperatures that could not be achieved with conventional combustion. It has advantages such as improved uniform distribution of water, which can greatly contribute to pollution and energy conservation.

[Brief explanation of the drawing]

The drawings show an embodiment of the burner of the present invention, FIG. 1 is an explanatory diagram showing the fuel spray state of the present invention, FIG. 2 is an explanatory diagram of the principle of generation of wavy spray, and FIG. Figure 4 is a comparative illustration of the present invention and the conventional method.
FIG. 5 is an explanatory diagram of the principle of NOX suppression, and FIG. 6 is an explanatory diagram of the fuel and spray medium supply pipeline of the present invention. 1 is burner, 2 is damper, 3 is sprayer, 4
is the burner throat, 5 is the flame holder, 6 is the nozzle,
7 and 8 are spray groups.

Claims (1)

[Scope of utility model registration request] A nozzle is provided at the tip of the sprayer that penetrates the burner body, dampers for air adjustment are provided in the primary and secondary combustion air supply paths, and a spray medium supply pipe and a fuel supply pipe are connected to the sprayer. In addition, a branch pipe is connected to the fuel supply pipe via a solenoid valve, and one of the branch pipes is equipped with a regulating valve with a minimum flow rate, and the other with a regulating valve with a maximum flow rate. A burner equipped with an electromagnetic valve in the branch pipe on the maximum flow rate side to set the time for spraying the maximum and minimum amount of fuel in a wave pattern.