JPH0868517A - Ash melting method and device - Google Patents

Abstract

PURPOSE: To obtain a compact, high-efficiency ash melting device where the load per volume can be increased because of its high heat transfer effect. CONSTITUTION: Primary ash is burnt by a primary ash melting burner 4 together with combustion aids such as fuel, air, etc., to turn the ash into molten particles, and the molten particles are sprayed into secondary ash 10 at a high speed together with flame so that heat reaches deep inside the secondary ash 10, stimulating the secondary ash to melt. The primary ash is sprayed into the secondary ash 10 as molten particles at a high speed from the primary melting burner 4 together with flame. As the molten particles that are sprayed at a high speed together with flame have an excellent straight traveling property and effectively hit the surface of the secondary ash layer with the heat and kinetic energy held in the molten particles and the combustion gas, heat is transferred deep inside the secondary ash layer, stimulating the secondary ash 10 to melt.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an ash melting method and apparatus.

[0002]

2. Description of the Related Art A conventional combustion type ash melting furnace is a surface melting furnace that melts from the surface of a layer of ash by a burner flame and radiant heating of the inner wall of the furnace, and the ash is completely mixed with combustion air or this flow, There are two major types, such as swirl melting furnaces, which melt in a flame as well as on the inner wall of the furnace.

[0003]

In the surface melting furnace described above, the ash melts only on the surface, and the layer of ash immediately below serves as a heat insulating layer and functions to protect the surrounding or lower furnace body structure from heat and erosion. is there. Since only the surface of the ash layer is melted by radiant heating in the furnace, a large load cannot be taken, resulting in a large size and low efficiency. Generally, there are problems such as high flame temperature and high NOx. Further, since the swirling melting furnace described above is a method of directly hitting the flame and ash particles in the middle of melting on the inner wall of the furnace, the damage in the furnace is severe. In this type of melting furnace, the course of combustion gas and ash flow is likely to be fixed, and the furnace inner wall of this course requires frequent maintenance. In this method of mixing all the amount of ash into the flame or combustion gas, it is necessary to mix a large amount of ash into the flame in order to improve the heat source unit, but at this time it is difficult to maintain the flame and control combustion, and unburned There are problems such as the generation of minutes.

[0004]

In order to solve the above-mentioned problems, the present invention burns primary ash together with a combustion-supporting agent such as fuel and air in a primary melting burner and ejects it as molten particles into a secondary ash at high speed together with flames. The present invention provides an ash melting method characterized by accelerating the melting of the secondary ash by transferring heat to the deep part of the secondary ash.

Further, according to the present invention, an inclined melting section is formed below the secondary ash supply section, and a primary ash melting burner is installed on a wall opposite to the inclined melting section, and the primary ash melting burner has a fuel supply section. An ash melting apparatus characterized in that a combustion-supporting agent supply unit for air or the like and a primary ash supply unit are provided, and the lower portion of the inclined melting unit is a complete melting unit.

[0006]

Operation: The primary ash is ejected from the primary melting burner as molten particles into the secondary ash at high speed together with the flame. The molten particles blown out at a high speed with the flame (including those that have been melted and those in the middle) have excellent straightness, and the heat and kinetic energy that they possess effectively strike the surface of the secondary ash layer with the combustion gas to create deep areas. Transfers heat up to promote melting. The molten particles that have entered the secondary ash layer act as a trigger (nucleus) for the surrounding secondary ash to start melting, and the molten particles that remain on the surface prevent the ash from scattering from the powdery secondary ash surface. To do. Further, the surface of the secondary ash layer promotes melting due to the above effects in addition to the flame and radiant heating from the inside of the furnace. The mixing ratio of the primary ash differs depending on the material of the ash, the properties of the fuel, and the structure of the furnace body. Generally, for low-calorie fuels and hard-to-burn fuels, the ash premixing ratio is kept below 50% due to flame stability.

[0007]

EXAMPLES Reference numeral 1 is a furnace body, and 2 is a secondary ash supply section. Reference numeral 3 is an inclined melting section provided below the secondary ash supply section. A primary ash melting burner 4 is installed on the opposite wall of the inclined melting, and the primary ash melting burner 4 is provided with a fuel supply unit 5, a combustion-supporting agent supply unit 6 such as air and a primary ash supply unit 7, and the inclined melting unit A complete melting portion 12 is formed in the lower part of the. 8 is a pusher, and 9 is a discharge part. Depending on the case, the primary ash supply unit 7 may not be provided, and the primary ash may be mixed into the fuel or the combustion-supporting agent may be mixed with the primary ash.

While the secondary ash 10 is fed from the secondary ash supply section 2, the primary ash melting burner 4 is supplied with the primary ash from the primary ash supply section 7, and the fuel supply section 5 and the combustion-supporting agent supply section 6 are connected with each other. When fuel gas, air, etc. are introduced into the primary melting burner 4, combustion starts in the burner 4, and the primary ash becomes molten particles and is ejected at high speed into the secondary ash 10 together with the flame 11. To do. The molten particles blown out at high speed (including those that have been melted and those in the middle) have excellent straightness, and due to the heat and kinetic energy possessed by them, they strike the surface of the secondary ash 10 layer more effectively than the combustion gas and reach deep areas. Conducts heat and promotes melting. The molten particles that have entered the secondary ash 10 layer serve as a trigger (nucleus) for the surrounding secondary ash 10 to start melting, and the molten particles that remain on the surface are the ash from the surface of the secondary ash 10 that is still in powder form. Prevent scattering. Furthermore, the surface of the secondary ash 10 layer is
In addition to the radiant heating from the flame 11 and the furnace, melting is promoted by the above effect. The mixing ratio of the primary ash depends on the material of the ash, the properties of the fuel, and the structure of the furnace body 1. Generally, for low-calorie fuels, the ash premix ratio should be 5 due to flame stability.
Keep it below 0%.

In general, when the materials are mixed in the flame, the flame temperature is lowered by the heat absorption, so that the burner itself may be a general-purpose one without the NOx reduction measures. However, more N
A low NOx burner can be used to seek Ox reduction. In this case, a low NOx burner that blows out at high speed is required to maintain the momentum of the flame containing ash particles, but these are generally unsuitable for this system because the flow velocity is slow. The burner effective for this system uses "direct injection in the fuel furnace". Since the NOx reduction effect increases as the flow velocity increases, the kinetic energy, which is a feature of the present invention, can be maintained at that time. An example of a burner structure for an ash melting furnace is shown in FIG. The principle of NOx reduction is mainly to lower the flame temperature. However, when it is desired to melt the material in a short flame within a limited space, the flame temperature must be raised to the contrary. It goes without saying that the optimum flame state must be selected depending on how to set the ratio of complete melting in the flame and how to set the premixing ratio. In some cases, oxygen may be used as a combustion support agent.

[0010]

As described above, the present invention has the following effects. Flame temperature drops from tens to hundreds of degrees, N
Generation of Ox is suppressed. The premixed ash is effectively melted in a flame having a high heat transfer effect. This impact heating also promotes melting at the surface portion, and together with this, highly efficient melting is realized. Since the flame containing particles is excellent in straightness, a heat spot on the surface of the ash layer, which is required when the surface is melted, is easily formed. (Generally, in the case of surface melting, it is better to have a high temperature part that actively starts melting.) The function of protecting the furnace body by the lower unmelted ash layer, which is a feature of conventional surface melting furnaces, can be maintained. . Since the overall heat transfer effect is high, the load per unit volume can be increased, and higher efficiency and compactness can be achieved.

[Brief description of drawings]

FIG. 1 is an overall cross-sectional explanatory view.

FIG. 2 is an explanatory diagram of a primary melting burner.

[Explanation of symbols]

 1 Furnace Body 2 Secondary Ash Supply Section 3 Inclined Melting Section 4 Primary Melting Burner 5 Fuel Supply Section 6 Fuel Support Agent Supply Section 7 Primary Ash Supply Section 8 Pusher 9 Discharge Section 10 Secondary Ash 11 Flame

Claims (2)

[Claims] 1. The primary ash is burned in a primary ash melting burner together with a combustion-supporting agent such as fuel and air to be ejected as molten particles together with a flame into the secondary ash at high speed to transfer heat to a deep portion in the secondary ash. A method for melting ash, characterized in that the melting of secondary ash is accelerated. 2. An inclined melting section is formed below the secondary ash supply section, and a primary ash melting burner is installed on a wall opposite to the inclined melting section. The primary ash melting burner has a fuel supply section, air, etc. And a primary ash supply section, and the lower part of the inclined melting section is a complete melting section.