Possible measures to suppress NOx generation
- Author:Shenzhen Zhongli Weiye Electromechanical Equipment Co., Ltd.
- Origin:Shenzhen Zhongli Weiye Electromechanical Equipment Co., Ltd.
- Time of issue:2021-07-03 14:49
Possible measures to suppress NOx generation
1. Reduce the peak temperature of the boiler and the amount of pulverized coal in the combustion area.
2. Reduce the oxygen concentration (i.e. reduce the excess air coefficient) and block part of the secondary air duct.
3. To ensure the output of the boiler, some pulverized coal and air can be input from the upper part of the boiler, so as to control the amount of combustion supporting air in the central area of the combustion flame, shorten the residence time of combustion products in the high-temperature flame area, and avoid the simultaneous existence of high temperature and high oxygen concentration.
4. A reburning zone is set up in the furnace to reduce no to N2 by using the hydrocarbon root Chi and incomplete combustion products co, H2, C and CnHm generated in the main combustion zone.
80% ~ 85% of the fuel is sent to the main combustion zone, where it burns to generate NOx. 15% ~ 20% of the fuel is sent to the reburning zone, where the excess air coefficient is less than 1.0（ α< 1.0), with a strong reducing atmosphere, and NOx generated in the main combustion zone is reduced; The reburning zone can not only reduce the NOx that has been generated, but also inhibit the generation of new NOx; A certain amount of air (called burnout wind) is supplied to the burnout area to ensure that the incomplete combustion products from the reburning area are burned out. According to the principle of low NOx combustion technology of pulverized coal reburning and the previous research results, the whole furnace combustion area is divided into main combustion area, reburning area and burnout area. The target value of excess air coefficient at the outlet of each area is: outlet of main combustion area α= 0.9 ~ 1.0, outlet of reburning zone α= 0.8 ~ 0.9, outlet of burnout zone α= 1.167。 The actual coal used by the boiler is used as fuel in both the main and reburning areas of the boiler. 80% ~ 90% of concentrated pulverized coal is burned in the main combustion area, and 10% ~ 20% of ultra-fine pulverized coal is injected into the reburning area as reburning fuel.
Ultra fine pulverized coal refers to the coal whose particle size is less than 43 μ According to relevant research, this size of pulverized coal has the same combustion characteristics as atomized fuel. In engineering application, the concentration dilution separator can be used to separate the conventional pulverized coal. 1. Low load
Excellent stable combustion ability under low load without oil. One of the design concepts is to establish the early concentration ignition of pulverized coal. For this purpose, the company has developed an efficient concentration dilution separation device, two layers of concentrated and light primary air sharing one layer of primary air chamber, a fully separated primary air pulverized coal burner in the middle, and a toothed pulverized coal combustion nozzle at the periphery. At the same time, the reverse tangential jet technology of primary air pulverized coal greatly improves the boiler's stable combustion ability under low load without oil. According to the design and verification of the ignition characteristics of the coal, select the appropriate concentration ratio of pulverized coal, pulverized coal nozzle and the reverse tangent angle of concentrated primary air to ensure the timely ignition and stable combustion of pulverized coal within the allowable change range of the coal, and the burner is in good condition.
2. Pulverized coal
Excellent characteristics of high-efficiency coal burnout, slagging prevention and high-temperature corrosion. First, the early ignition of high concentration pulverized coal improves the combustion efficiency; At the same time, by arranging the bottom secondary air, the offset secondary air, the upper ofa and the spatially separated s-ofa at different heights of the furnace, the furnace is divided into three relatively independent parts: combustion area, NOx reduction area and burnout area. Reasonably control the excess air coefficient in each area. This improved air classification method can effectively reduce NOx emissions and maximize combustion efficiency by optimizing the excess air coefficient in each area; Third, through the rigid bias secondary air in the burner area, an oxidation zone with low pulverized coal concentration is formed near the furnace wall to avoid slagging and high-temperature corrosion in the furnace. Fourth, this technology separates the concentration of pulverized coal from the dilution of pulverized coal. All the concentrated primary air pulverized coal is arranged at the lower part of the combustion area, which is equivalent to improving the burnout height of pulverized coal and the reduction height of NOx, which is conducive to improving the combustion efficiency of the boiler and reducing the emission level of NOx.
3. NOx combustion
Ultra low NOx combustion emission characteristics. The most prominent feature of the staged combustion technology is the ultra-low NOx combustion characteristics. On the premise of ensuring stable combustion and high efficiency, it not only ensures the early ignition and stable combustion of pulverized coal by adopting high-efficiency concentration dilution separation technology, space combustion classification technology, primary air reverse jet and other means, but also realizes the on-demand air supply in the furnace and reduces the flue gas temperature deviation at the furnace outlet by adopting the up, down, left and right adjustable burn out air nozzle technology, More importantly, it realizes the combustion emission of ultra-low NOx of the boiler.
4. Small oil spot
Excellent small oil ignition and stable combustion capacity. The design adopts the small oil combustion ignition technology of pulverized coal gasification that has been widely applied in industry. The small oil ignition device is arranged in the pulverized coal burner with rich and lean primary air on the first floor, so that the large oil gun can be completely not put into operation during the cold and hot start-up of the boiler, which greatly reduces the start-up of the boiler and the stable combustion oil consumption under lower load.
5. Separate the burnout air (soaf)
Separate burnout air soaf also has good characteristics of reducing the flue gas temperature deviation at the furnace outlet. The use of space air staged combustion technology is not only an important means to reduce NOx emissions and improve the pulverized coal burnout rate, but also the horizontal swing adjustment of sofa, which is more helpful to reduce the wall temperature deviation of superheater and reheater caused by the flue gas temperature deviation at both sides of the furnace outlet
CEE ultra-low NOx combustion technology has no operating cost. It not only realizes the ultra-low NOx emission of the boiler, but also realizes the characteristics of high-efficiency and stable combustion of the boiler, anti slagging, high-temperature corrosion, stable combustion without adding oil under low load, stable combustion of small oil ignition of the boiler, and expands the adaptability of the boiler to coal types. It has achieved excellent results in industrial application.
On the basis of absorbing advanced technologies and processes at home and abroad, Shenzhen Zhongli Weiye Electromechanical Equipment Co., Ltd. integrates years of wisdom and experience in burners. The accuracy, stability and reliability of products occupy an important position in China. The Zhongli Weiye brand burner produced by our company has been gradually upgraded from the first generation to the current third generation, and is still developing more high-end products. It is an advanced ultra-low nitrogen burner enterprise in China. With advanced technology, excellent quality and perfect service, our products are among the forefront of the super burner industry in China, and have become a well-known brand in China. Our products are all over the country. We actively advocate; Take the market as the guide, scientific research as the leader, and innovation as the means to actively explore domestic and foreign markets.