JPS62288420A - Catalytic burner - Google Patents

Abstract

PURPOSE:To provide a combustion system having a low NOx and a high efficiency by a method wherein the premixture gas of excessive rich fuel is ignited in a catalyst and a transformation from a fuel N to NOx is restricted and at the same time a generated gas is completely burnt with the catalyst arranged downstream of the catalyst. CONSTITUTION:A pilot burner 1 is located at the hard part of a liner 4 of a burner. Fuel to be used here is oil or natural gas or the like which is different from a main fuel. A premixing gas nozzle 2 may supply a fuel including a fuel N and a premixture gas having an air excessive rate of less than 0.5. The premixture gas is preheated by the pilot burner and guided to a downstream catalyst 3. The preheated fuel is partly oxidized at the catalyst 3 and then guided to a downstream combustion chamber 5. Air is fed into the liner downstream of the catalyst in a stepwise manner and then complete combustion is carried out while an air excessive rate increases. Since the fuel including fuel N can be burnt stably with a fuel excessively rich, it is possible to decrease a rate of conversion from the fuel N to NOx and a complete combustion under a lean combustion downstream side of the catalyst can be performed, so that a burner having a low NOx and a high efficiency can be provided.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a combustor for a gas turbine, and particularly relates to a combustor for a gas turbine, and particularly relates to a combustor for reducing nitrogen oxides emitted when nitrogen compounds such as ammonia are combusted. The present invention relates to a combustor configuration suitable for reducing combustion.

[Conventional technology]

Conventionally, so-called two-stage combustion, in which main combustion is performed in an air-deficient state and re-combustion air is blown in to remove unburned components in the downstream, reduces thermal NOx and fuel NOx from combustion such as gas combustion. is known to be effective. It is also generally known that when air is blown into the second stage, the final NO after blowing decreases as the blowing position moves away from the tip of the burner. (Published by Japan Society of Mechanical Engineers 855.12.20) Generation mechanism and control method of environmental pollutants associated with combustion Primary combustion is performed on the rich side, and fuel N
This is a two-stage combustion in which the unburned components remaining from the combustion are combusted by mixing secondary air, while suppressing the conversion of NO into NO.

A flammable combustion combustor has a stable combustion range apart from the flammability limit, and outside this range, incomplete combustion or no flame is formed at all. This unstable region exists on the fuel-rich side and on the fuel-lean side, respectively.

Therefore, even if the fuel is burnt in a rich manner in order to suppress NOx from the fuel N, there is naturally a limit.

The limit value for flaming combustion is about 0.8 when converted to excess air ratio, and the Noχ conversion ratio of fuel N at this time is 50%.
It will be about 60%. In order to achieve this conversion rate of 20% to 30%, it is necessary to create highly fuel rich conditions by combustion instead of flaming combustion.

[Problem that the invention seeks to solve]

The present invention has a problem in that because the conventional combustor uses flaming combustion, the range in which it can burn in a fuel-rich state is limited, and it is difficult to lower the NOx conversion rate of fuel N.

An object of the present invention is to provide a combustor structure that can create a higher fuel enrichment state and achieve stable combustion.

Conventional catalytic combustion is often used in fuel lean conditions, and there are no particular problems from a combustion standpoint. That is, there is sufficient oxygen around the fuel, and since the oxidation reaction progresses on the catalyst, the temperature in that area becomes high and the flame stability improves.

On the other hand, in the present invention, since the catalyst is used in a fuel rich state,
Sufficient mixing of fuel and oxygen cannot be expected with the catalyst alone, and therefore the reaction temperature will not increase.

The present invention allows the reaction to proceed even in this state, ultimately resulting in low NOx
, to create a highly efficient combustion system.

[Means for solving problems]

In order to achieve the above objective, the combustion process is as follows. The fuel-rich premixture is combusted in a catalyst provided for partial oxidation, and the fuel N to N
Prevents conversion to Ox.

On the other hand, since the gas generated from this catalytic reaction contains a large amount of unburned components such as CO2HC, it is completely combusted by a catalyst separately provided downstream of this catalyst.

Since heat to sustain the combustion reaction cannot be expected in the partial oxidation catalytic reaction, a separate heat source is provided upstream of the catalyst to facilitate the partial reaction.

[Effect]

A pilot burner located at the head of the combustor heats the first stage catalyst and also provides the heat necessary for partial oxidation of the premixed fuel.

The first stage catalyst partially oxidizes the fuel-rich premixture and converts it mainly into UHC. It also converts nitrogen contained in the fuel into cyanide or ammonia.

The second stage catalyst is UCH produced in the first stage catalytic reaction.
Completely burn l or co.

〔Example〕

Figure 1 shows the basic principle of a combustor. A preburner at the head of the combustor heats the premixture and catalyst A to assist partial combustion in catalyst A. The supplied premixture has an excess air ratio of λ=0.5 or less. Nitrogen components such as ammonia contained in the fuel are decomposed into cyanide and ammonia in the process of passing through catalyst A, and other combustible components such as HztC
H4, CO, etc. are decomposed and discharged into carbon monoxide and unburned hydrocarbons. Generally, the process in which fuel N containing ammonia etc. is converted to NOx is decomposed in a reaction zone and N
An intermediate product containing the atom is produced, and the intermediate product reacts with a species containing 0M atoms to form NO, or the intermediate product reacts with NO to decompose the NO.

Take the route that leads to N2. Here, the chemical species containing the ○ atom are OH radicals and the like. Also, the intermediate product is N Hz,
N Hl or N can be considered. In general, the reaction between fuel N and chemical species containing O atoms after the decomposition of fuel N into intermediate products such as NHZ, NH, and N is known as fuel no.
It will control generation.

This suggests that the nature of the flame is the main controlling factor. Generally, the lower the combustion temperature, the more N is emitted.
o concentration is known to decrease. Therefore, it is necessary to equalize the flame temperature and create a low flame temperature condition. Catalytic combustion satisfies these two requirements.

Downstream of the catalyst, the air that is introduced in stages is mixed with unburned gas that is partially oxidized by the catalyst. Here, the mixture becomes a lean mixture, and the complete combustion chamber moves to complete combustion in stages. Possible methods include flaming combustion and using a catalyst. The effect is the same in either case.

FIG. 2 shows an embodiment of the combustor. Pilot burner 1
is provided at the head of the combustor liner 4.

The fuel used here can be oil, natural gas, etc.
Different from main fuel. The premixture nozzle 2 supplies a premixture containing fuel including fuel N and a premixture having an excess air ratio of 0.5 or less into the liner.

The supplied premixture is preheated by a pilot burner and guided to the catalyst 3 downstream. In the catalyst 3, the preheated fuel is partially oxidized and guided to the downstream combustion chamber 5. Air is introduced in stages from the liner downstream of the catalyst, and complete combustion occurs as the excess air ratio increases.

〔Effect of the invention〕

According to the present invention, it is possible to stably burn fuel containing fuel N in a fuel-rich state.
The conversion rate to Ox can be reduced, and complete combustion can be achieved through lean combustion downstream of the catalyst, resulting in low NOx
, resulting in a highly efficient combustor.

[Brief explanation of drawings]

Claims (1)

[Claims] 1. A gas turbine power generation device equipped with a combustor for fuel gas containing nitrogen compounds, wherein the combustor includes a combustion chamber having a fuel and air supply port and an outlet for discharging combustion gas, and the combustion chamber has a flow path. and a catalytic reaction layer and a combustor for heating the catalyst layer or the premixture of fuel and air are accommodated in the flow path, and the flow path is formed by the catalyst layer to form a plurality of All the gas upstream of the catalyst layer passes through the catalyst layer and reaches the space downstream of the catalyst layer, and the space upstream of the catalyst layer is for mixing air with fuel containing the nitrogen compound such as ammonia. The space downstream of the catalyst layer is a space for complete combustion of the gas generated by the catalytic action in the catalyst layer, and air necessary for complete combustion is supplied to this space, In the catalyst layer, the mixture gas of fuel and air containing the nitrogen compound is activated by a catalytic action, and the concentration of the mixture supplied to the catalyst layer is set to 0.5 or less in terms of excess air ratio; The activation temperature is limited to a temperature of 1000°C or less at which ammonia is not converted into the nitrogen oxides, and in the space downstream from the catalyst layer, nitrogen compounds such as cyanide generated in the catalyst layer can be decomposed into nitrogen and water. A catalytic combustor characterized by controlling the amount of air so that the temperature is maintained.