JPH033121B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for starting a combustion device, and more particularly to a method for starting a combustion device that can reduce the amount of nitrogen oxide emissions.

The amount of nitrogen oxides (hereinafter abbreviated as NOx) generated in combustion devices such as boilers is regulated as an air pollutant. NOx is generated mainly by (1) nitrogen molecules in combustion air being oxidized at high temperatures (thermal NOx), and (2) mainly by oxidation of nitrogen compounds contained in fuel. It is roughly divided into two types: NOx (fuel NOx). It is known that both NOx are greatly affected by the oxygen partial pressure as well as the combustion temperature. For this reason, in each combustion device, the amount of combustion air supplied is controlled as precisely as possible as a means of reducing NOx.

However, in equipment such as large boilers for business use, in which a large number of burners are installed in a single combustion equipment, the NOx concentration tends to increase when the equipment is started for the following reasons, which has become a problem. In other words, in such large-scale combustion equipment, some of the burners are ignited, and then the remaining burners are gradually ignited to start up, but combustion air leaks from unlit burners and this Leak air (leak air)
Therefore, the air-fuel ratio of the burner during ignition increases and NOx
The amount of produced increases. Combustion air to each burner is controlled by opening/closing devices such as dampers, but it is virtually impossible to completely seal these opening/closing devices, and the occurrence of leakage air to some extent is unavoidable. Furthermore, in order to protect the unlit burner from the radiant heat of the ignited burner flame and cool it, a certain amount of air from the unlit burner tends to be actively used as a cooling medium. Control of NOx is becoming more difficult.

The present invention was constructed in view of the above-mentioned problems, and an object of the present invention is to provide a method for starting a combustion device that reduces the amount of NOx produced.

In short, this invention reduces the influence of leakage air from unlit burners by first igniting the side burners among the lowest stage burners when starting a combustion device in which a large number of burners are arranged in multiple stages. This is a method for starting a combustion device.

Embodiments of the present invention will be described below with reference to the accompanying drawings.

In FIG. 1, reference numeral 1 denotes the wall surface of the combustion apparatus main body, and on this wall surface, a plurality of burners (12 burners in the illustrated case) are arranged in three stages in the furnace height direction. In the figure, reference numeral 2 is a lowermost burner, 3 is a middle burner, and 4 is an upper burner. code 5
6 is a wind box provided for each lower burner 2, 6 is a wind box provided for the middle burner 3, and 7 is a wind box provided for the upper burner 4. Air supply passages 8, 9, and 10 are connected to each of these wind boxes. Reference numerals 11, 12, and 13 indicate dampers arranged in each of these air supply passages 8, 9, and 10.

The following method is used to start the combustion apparatus.

First, among the burners 2 at the lowest stage, the burners 2a and 2b located on both sides are ignited and activated. This is because an upward flow is formed in the furnace when one of the burners is ignited, but in this case, if the upper burner is ignited early, leak air from the lower burner will mix into the burner flame due to the upward flow in the furnace. However, as a result, the air-fuel ratio increases and the amount of NOx produced increases. For this reason, the burners on both sides of the lowest stage are ignited, where the influence of leakage air from other burners is least. Once the burners 2a and 2b on both sides are lit,
The remaining burners 2 are ignited to complete the ignition of the lower burners, then the burners 3a and 3b at both ends of the middle burner 3 are ignited, and then the remaining burners 3 are ignited. Similarly, the burner 4 on the top stage is ignited from the burners 4a and 4b on both sides, and then the remaining burners 4 are ignited.
By igniting the burner, all burners are ignited and the combustion equipment is started. After the equipment starts up, low NOx combustion is achieved through two-stage combustion and exhaust gas recirculation.

By implementing this invention, it is possible to start up the combustion apparatus while minimizing the influence of leak air from each burner, so that low NOx can be achieved when starting up the combustion apparatus.

[Brief explanation of drawings]

FIG. 1 is a front view of a burner installation part of a combustion apparatus for carrying out the method according to the present invention. 2...lowest burner, 3...middle burner, 4...
...Top burner, 5, 6, 7...Wind box.

Claims (1)

[Claims] 1. In a method for starting a combustion device in which multiple stages each having a plurality of burners are arranged in parallel on the furnace wall, the burners located at both ends of the lowest stage burner group are first ignited, and then the remaining lowest stage burners are ignited. The burners are ignited, and after the ignition of the lowest burner group is completed, the burners at both ends of the burner group located in the upper stage of the lowest burner group are ignited, and the remaining burners are further ignited to ignite this burner group, A low NOx starting method for a combustion device characterized by igniting up to the highest stage burner group by repeating this method thereafter.