A staged heat removal combustion method for reducing nitrogen oxides

Abstract

The present invention discloses a staged heat transfer combustion method for reducing nitrogen oxides. The low nitrogen oxide staged heat transfer combustion method is to divide the air required for combustion into two parts, A and B. First, the air part A is allowed to perform an initial incomplete combustion with the fuel in a closed combustion chamber, and the air part B is allowed to flow through a heat transfer device arranged in the combustion chamber, so that the air part B only absorbs part of the heat generated by the combustion of the air part A without participating in the combustion. The air part B after absorbing heat flows to the rear area through the heat transfer device and is released, and then completely burns with the fuel. The core content of the present invention is that part of the heat generated by the combustion of the air part A is transferred to the rear space, which greatly meets the low-temperature combustion under existing conditions, thereby controlling the production of nitrogen oxides.

Description

Technical Field

[0001] The present invention relates to the field of combustion technology, and is a combustion method for reducing the cost of treating nitrogen oxides. As long as the combustion is of fossil fuel, whether it is coal, oil or gas, the method can be used. Background Art

[0002] In the combustion process of fossil fuels, the generation of nitrogen oxides is part of the combustion reaction. The nitrogen oxides generated by combustion are mainly NO and NO2, collectively referred to as NOx. NOx in the atmosphere is an important factor in causing acid rain and haze, which brings extensive harm to human life and the environment and causes huge economic losses. Therefore, it is necessary to deal with the flue gas containing NOx in a timely manner before it is discharged. With the increasing environmental protection requirements, the emission requirements for NOx are also becoming more stringent.

[0003] The combustion of existing fossil fuels makes it difficult to meet environmental emission requirements for NOx produced during the combustion process, so a technical solution is needed to solve this problem.

[0004] The most preferred solution is to change the existing combustion process of fossil fuels to reduce the NOx produced during the combustion process as much as possible and control the amount of NOx at the source. Summary of the invention

[0005] The purpose of the present invention is to overcome the disadvantage of the prior art that excessive NOx generated during combustion causes increased processing costs, and to invent a new combustion method by changing the existing combustion process: a staged heat removal combustion method for reducing nitrogen oxides.

[0006] A hierarchical heat transfer combustion method for reducing nitrogen oxides is to divide the air required for combustion into two parts, A and B. First, the air part A is allowed to perform an initial incomplete combustion with the fuel in a closed combustion chamber. The initial oxygen-deficient combustion forms a reducing area and a flame center. A heat transfer device is arranged in the high-temperature area of ​​the flame center in the combustion chamber, and the air part B flows through the heat transfer device arranged in the combustion chamber, so that the air part B only absorbs part of the heat generated when the air part A is burned without participating in the combustion. The air part B after absorbing heat flows to the rear area through the heat transfer device and is released, and then completely burns with the fuel to form an oxidizing area. In this way, two-stage combustion is formed, and the air part B can also be released in batches at the rear through the heat transfer device as needed, so as to form multi-stage combustion. The core content of the present invention is to transfer the heat at the high temperature of the flame center in the reducing area to the oxidizing area at the rear to make the heat relatively balanced. Compared with the original combustion process, the combustion process after heat transfer is changed, which greatly meets the low-temperature combustion under existing conditions and can minimize the content of synthetic nitrogen oxides.

[0007] To further explain, the air required for combustion refers to the total amount of air required for complete combustion of the fuel, that is, the theoretical amount of air multiplied by the excess air coefficient. The air required for combustion is divided into two parts, A and B. Part A, which accounts for 65-85% of the total air, is first incompletely burned to form reducing gas, and part B, which accounts for 15-35% of the total air, is subsequently completely burned to form oxidizing gas. The purpose is to control the furnace temperature and the amount of NOx generated.

[0008] A staged heat transfer combustion method for reducing nitrogen oxides, which has the necessary condition that a heat transfer device must be arranged in a closed combustion chamber. Since this method is applicable to the combustion of all fossil fuels, such as power plant boilers and automobile engines, the structure of the heat transfer device must be designed based on the number and position of flame centers on the equipment used, the shape of the combustion chamber, the layout of the burner, and other conditions. Therefore, the structure of the heat transfer device cannot be represented by a single drawing and has diversity. Figure 1 The heat transfer device described is an example of the application of a staged heat transfer combustion method for reducing nitrogen oxides in the front and rear wall counter-combustion method of a power plant boiler. Obviously, if only one burner is used on the equipment, only one heat transfer device is needed. The structure of the heat transfer device is diverse, but the design principles have common points, which are described as: analyzing the number and position of flame centers on the equipment, arranging one for each flame center, arranging it in correspondence with the burner, arranging it in the high temperature area of ​​the flame center of the combustion chamber, belonging to pipeline design, selecting materials that are resistant to high temperature, wear, corrosion, and heat conduction, etc.

[0009] The following is an application example to illustrate the use of this method. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] See the instruction manual for details. Figure 1 , an example diagram of the application of a staged heat transfer combustion method for reducing nitrogen oxides in the front and rear wall counter-combustion mode of a power plant boiler.

[0011] Among them: 1. Burner; 2. Combustion chamber; 201. Combustion chamber wall; 202. High temperature area in the center of flame; 203. Reduction zone; 204. Oxidation zone; 205. Combustion chamber outlet; 3. Heat transfer device; 301. Inlet nozzle; 302. Strengthened heat conduction structure; 303. Outlet nozzle; 304. Lifting ear; 4. Air duct; 5. Fuel; A. Air entering the burner; B. Air entering the heat transfer device.

[0012] Example 1

[0013] See attached Figure 1 , an example diagram of the application of the front and rear wall counter-combustion method in power plant boilers. DETAILED DESCRIPTION

[0014] Figure 1, an example diagram of the application of a staged heat transfer combustion method for reducing nitrogen oxides in the front and rear wall counter-combustion mode of a power plant boiler. The boiler burners are arranged counter-combustibly on the front and rear walls, and the number of arrangements is related to the boiler load. This example considers 4 burners arranged on the front wall and 4 burners arranged on the rear wall. The front and rear counter-combustion forms 4 flame centers in the middle of the combustion chamber. According to the principle of NOx generation, lowering the surface temperature of the flame can inhibit the generation of NOx. Therefore, 4 heat transfer devices are arranged accordingly at the 4 flame centers to locally reduce the surface temperature of the flame. The 4 heat transfer devices have the same structure, and each heat transfer device is described as follows, see Figure 1 .

[0015] The air in the air duct 4 is divided into two parts: air A entering the burner and air B entering the heat transfer device. First, the air A is allowed to perform an initial incomplete combustion with the fuel 5 in the closed combustion chamber 2. The initial oxygen-deficient combustion forms a reduction zone 203 and a flame center. The heat transfer device 3 is arranged in the high-temperature area 202 of the flame center in the combustion chamber, so that the air B flows through the heat transfer device 3 arranged in the combustion chamber, so that the air B only absorbs part of the heat generated by the combustion of the air A at the enhanced heat conduction structure 302 without participating in the combustion. After absorbing heat, the air B flows to the rear area through the heat transfer device and is released at the outlet nozzle 303, and then completely burns with the fuel to form an oxidizing zone 204, that is, the heat transfer combustion is completed.

[0016] This example is further explained only from the structural point of view: the heat transfer device 3 requires a material that is resistant to high temperature, wear and corrosion, and easy to conduct heat; it is designed to be a movable structure in the shape of a Y, and is hung on the combustion chamber wall 201 in the form of a hanging ear 304 for maintenance; due to the needs of the boiler, the B part of the wind entering the heat transfer device 3 is first subjected to a small amount of diversion combustion at the inlet nozzle 301 of the reduction zone 203, and the remaining wind absorbs heat at the enhanced heat conduction structure 302 in the high temperature area 202 at the center of the flame, and the wind after absorbing heat flows into the oxidation zone 204 and is released at the outlet nozzle 303 for complete diversion combustion, and is released from the combustion chamber outlet 205 at the top after combustion.

[0017] In this example, two-stage combustion is formed, and part B of the air can also be released in batches at the back through the heat transfer device 3 as needed to form multi-stage combustion.

[0018] The staged heat removal combustion method for reducing nitrogen oxides of the present invention is a new combustion method and can be used in any industry as long as it is the combustion of fossil fuels.

[0019] The drawings in the embodiments of the present invention clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiment is only one embodiment of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] Finally, it should be noted that the present invention is a combustion method that can be widely used in various industries; the embodiment 1 described only represents the use of this method on a boiler in a power plant, and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments, or replace some of the technical features therein by equivalents. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A staged heat transfer combustion method for reducing nitrogen oxides, which divides the air involved in combustion into two parts, A and B, to achieve front and rear two-stage combustion, namely staged combustion; the air part A first reacts with the fuel in the lower part of the furnace, forming a reduction zone (203) due to lack of oxygen, and forming a high-temperature area (202) in the center of the flame; the air part B flows into the heat transfer device (3), absorbs heat at the enhanced heat conduction structure (302) of the heat transfer device (3) to reduce the temperature of the high-temperature area (202) in the center of the flame; the air part B after absorbing heat continues to flow to the rear part in the heat transfer device (3), and is released to the upper part of the furnace at the outlet nozzle (303) to react with the fuel to form an oxidizing zone (204), thus completing the heat transfer combustion.

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