JP2686313B2 - Low temperature combustion method of methane gas fuel - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an improvement in a method for low-temperature combustion of methane-based gas fuel such as natural gas.

[Conventional technology]

Conventionally, the combustion temperature is lowered by the two-stage combustion method, the rich-lean combustion method, the steam atomization method, the uniform combustion method, the catalytic combustion method, etc.
It was aiming for low NO _X.

[Problems to be solved by the invention]

However, as the combustion temperature is lowered, the combustion becomes unstable and incomplete combustion occurs, the amount of CO generated increases, and the flame lifts and disappears.

Therefore, in order to stabilize the combustion is limited to a decrease in the combustion temperature, there has been room for further improvement in terms of low NO _X reduction.

An object of the present invention is to burn a methane-based gas fuel at a low temperature,
At the same time, incomplete combustion can be suppressed, and low NO _X can be achieved more sufficiently.

[Means for solving the problem]

The characteristic means of the first invention is that, immediately before low-temperature combustion of the methane-based gas fuel, the methane-based gas fuel is irradiated with an ultraviolet laser, and CH ₄ is dissociated into CH ₂ and H ₂ by the action of the ultraviolet laser. In particular, its action is as follows.

(Operation)

That is, by irradiating at moderate intensity ultraviolet light laser of moderate wavelengths at room temperature for CH _4, the CH ₄ than can dissociate into H ₂ and CH ₂ excellent flammability, prior to burn CH ₄ The method of the present invention, which burns H ₂ and CH ₂ more than the technology, can sufficiently maintain complete combustion at a lower temperature.

Therefore, for example, CO / CO ₂ <0.005, while maintaining good combustion in which CO generation is sufficiently suppressed, the combustion temperature can be sufficiently lowered, and NO _x can be further effectively reduced.

[Means for solving the problem]

The characteristic means of the second invention is that the sensitizer is mixed into the methane-based gas fuel and the infrared laser is irradiated immediately before the methane-based gas fuel is burned at a low temperature. CH ₄ and O ₂ are reacted with each other, an oscillating light is generated by the action of the sensitizer accompanying the reaction, and the remaining CH ₄ is dissociated into CH ₂ and H ₂ by the action of the oscillating light. And its action is as follows.

(Operation)

That is, by irradiating CH ₄ at room temperature with an infrared laser having an appropriate wavelength at an appropriate intensity in the coexistence of a sensitizer X such as NO, He or SF ₆ and O ₂ , one of the following CH ₄ Oscillation light hv can be generated by the oxidation reaction of the part.

CH ₄ + O ₂ + X → CO ₂ + H ₂ O + X + hv And the remaining CH ₄ can be dissociated into H ₂ and CH ₂ by the action of the oscillating light hv, and low NO due to low temperature combustion while maintaining stable combustion as in the first invention. _X conversion can be realized more effectively.

〔The invention's effect〕

As a result, we were able to establish a clean combustion method that enables extremely low temperature complete combustion, which was not possible before, and that produces very little NO _X or CO.

In particular, it is extremely effective for cleaning indoor air in a city gas combustion device in which natural gas is frequently used.

〔Example〕

 Next, examples will be described.

Example 1 (see FIGS. 1 and 2) The methane gas fuel from the fuel supply passage (1) and the combustion air from the blower (B) are mixed to form a mixture in the case (12). Send to supply room (3).

Air-fuel mixture is supplied from the inner porous body (4) such as porous ceramics to the outer porous body (5), and the air-fuel mixture is surface-combusted on the surface of the outer porous body (5).

Heat-resistant mirrors (8) and (9) in which an ultraviolet laser from a laser oscillator (7) is arranged to face each other in a gap (6) formed between the inner porous body (4) and the outer porous body (5).
The methane gas fuel immediately before combustion is irradiated with an ultraviolet laser, and CH ₄ is dissociated into CH ₂ and H ₂ by the action of the ultraviolet laser as shown in the following reaction formula.

CH ₄ → CH ₂ + H _{2 In other} words, by performing surface combustion of CH ₂ and H _2, which have better flammability than CH ₄ , stable low-temperature combustion is achieved and incomplete combustion and flame lift are prevented. To achieve a sufficiently low NO _X.

As the laser oscillator (7), for example, a YAG laser,
Appropriate ones such as excimer laser, Ar ⁺ laser, N ₂ laser and dye laser can be used.

The wavelength of the ultraviolet laser is generally 60 to 390 nm, preferably 150 to 355 nm.

The intensity of the ultraviolet laser is generally 1 mJ or more, preferably 10 mJ or more.

Example 2 A methane-based gas fuel and combustion air were mixed in the same manner as in Example 1, and a sensitizer such as NO, He or SF ₆ was premixed with the methane-based gas fuel or combustion air. Alternatively, the air-fuel mixture is mixed by simultaneous mixing or post-mixing.

A mixture of methane gas fuel, combustion air, and sensitizer,
As in Example 1, the inner porous material is supplied to the outer porous material and the surface of the outer porous material is surface-combusted.

An infrared laser from a laser oscillator is reflected by a mirror in the gap between the inner and outer porous bodies and irradiated on the methane-based gas fuel immediately before combustion as in Example 1, and CH A part of ₄ reacts with O _2, and the action of the sensitizer X causes oscillation light hv.

_{CH 4 O 2 + X → CO} 2 + H 2 O + X + hv Then, the CH ₄ is dissociated into H ₂ as reaction formula the remainder of the CH ₄ by the action of the oscillation light hv.

CH ₄ → CH ₂ + H ₂ That is, similar to Example 1, by surface-burning CH ₂ and H _2, which are more combustible than CH ₄ , stable low temperature combustion is achieved, and incomplete combustion and It aims to achieve a sufficiently low NO _X while preventing the lift of the flame.

As the laser oscillating device, a suitable device such as a YAG laser, a CO laser, a CO ₂ laser, or the like can be used.

The wavelength of the infrared laser is generally 1 μm or more, preferably 1 to 10.6 μm.

The intensity of the infrared light laser is generally 10 mJ or more, preferably 100 mJ or more in the case of a pulse laser, and 10 W or more in the case of a CW (continuous oscillation) laser.

(Another embodiment)

 Next, another embodiment will be described.

The type of methane-based gas fuel, methane concentration, excess ratio of combustion air, and burner model can be selected as appropriate, and the present invention can be used in various fuel devices for industrial use, domestic use, and the like.

The specific means for irradiating the ultraviolet light laser or the infrared light laser can be appropriately changed depending on the type of burner.

In the claims, reference numerals are provided for convenience of comparison with the drawings, but the present invention is not limited to the structure shown in the attached drawings.

[Brief description of the drawings]

The drawings show an embodiment of the present invention, FIG. 1 is a conceptual diagram of a surface combustion burner, and FIG. 2 is an explanatory diagram of a laser irradiation state.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Koji Morie, 4-1-2, Hirano-cho, Chuo-ku, Osaka-shi, Osaka Prefecture, Osaka Gas Co., Ltd. (72) Inuro Tamura, 4-chome, Hirano-cho, Chuo-ku, Osaka-shi, Osaka No. 1 and 2 in Osaka Gas Co., Ltd.

Claims (2)

(57) [Claims] 1. A method for burning a methane-based gas fuel at a low temperature, which comprises irradiating an ultraviolet laser to the methane-based gas fuel immediately before combustion, and dissociating CH ₄ into CH ₂ and H ₂ by the action of the ultraviolet laser. Low temperature combustion method of methane gas fuel. 2. A method for burning a methane-based gas fuel at a low temperature, which comprises mixing a sensitizer into the methane-based gas fuel immediately before combustion and irradiating an infrared light laser with the action of the infrared light laser. Part of CH ₄ and O ₂ react with each other, and the reaction causes a sensitizer to generate oscillating light, and the oscillating light causes the remaining CH ₄ to dissociate into CH ₂ and H ₂ . Low temperature combustion method of methane gas fuel.