一、NOx氮氧化物的生成机制
对于天然气锅炉来说,Nox的产生主要来自空气中的氮气和过量氧气产生的热力型Nox,热力型NOx的产生和燃烧的温度呈指数型关系,通常在燃烧温度高于1000摄氏度的时候开始产生,而在1400度以上NOx的生成速度会急剧增加。下图反映的是燃煤型锅炉的NOx排放和温度的关系,其中热力型Nox的温度关系同样适合于天然气锅炉燃烧器。
燃煤型锅炉的NOx排放和温度的关系基于以上NOx的生长机制,
低氮燃烧器的控制NOx的技术也主要着眼于两个方向:
1、降低火焰温度;
2、降低氧含量。
The formation mechanism of NOx nitrogen oxides
For natural gas boilers, the production of Nox mainly comes from the thermodynamic Nox produced by nitrogen in the air and excessive oxygen. The production of thermodynamic Nox has an exponential relationship with the combustion temperature, which usually starts when the combustion temperature is higher than 1000 degrees Celsius, and the generation speed of Nox above 1400 degrees will increase sharply. The figure below reflects the relationship between NOx emission and temperature of coal-fired boilers, in which the temperature relationship of thermal NOx is also suitable for natural gas boiler burners.
The relationship between NOx emission and temperature of coal-fired boilers is based on the growth mechanism of NOx mentioned above. The technology of controlling NOx of low-nitrogen burners also focuses on two directions:
1. Reduce the flame temperature;
2. Reduce oxygen content.
二、低氮燃烧器和超低氮燃烧器类型
传统的天然气锅炉燃烧器通常的NOx排放在120~150毫克左右。低氮燃烧器通常是指NOx排放在30~80毫克的燃烧器。NOx排放在30毫克以下的通常称为超低氮燃烧器。
传统的燃烧器的高NOx排放主要源于下述几个原因:
1、为了保证燃烧充分,采用了较大的过量空气;
2、燃烧温度通常在1800度左右。
Types of low-nitrogen and ultra-low nitrogen burners
Conventional gas boiler burners typically emit about 120 to 150 milligrams of NOx. Low nitrogen burners are usually defined as NOx burners that discharge between 30 and 80 mg. NOx emissions below 30 mg are commonly known as ultra-low nitrogen burners.
The high NOx emission of traditional burners is mainly caused by the following reasons:
1. In order to ensure sufficient combustion, large excess air is used.
2. The combustion temperature is usually around 1800 degrees.
三、低氮燃烧器三、低氮燃烧器通常基于下列技术
1.电子比例调节和氧含量控制技术;来精确控制氧含量;
2.FGR烟气再循环技术,来降低火焰温度和氧含量;
3.全预混的表面燃烧技术来降低火焰温度和实现充分燃烧;
上述技术中,通常是低氮燃烧器的必须配置。基于上述技术,市场的低氮燃烧器主要分为以下类型:
Low nitrogen burners low nitrogen burners are usually based on the following technologies
1. Electronic proportional regulation and oxygen content control technology; To precisely control the oxygen content;
2.FGR flue gas recirculation technology to reduce flame temperature and oxygen content;
3. Fully premixed surface combustion technology to reduce flame temperature and achieve full combustion;
In the above technology, it is usually necessary to configure the low nitrogen burner. Based on the above technology, the market for low-nitrogen burners is mainly divided into the following types:
四、各
低氮燃烧器优缺点介绍
1、FGR低氮燃烧器
FGR低氮燃烧器通常能够将NOx在全火范围内控制到65毫克,极限大约在40毫克左右,进一步降低NOx排放可能导致燃烧不稳定,或者牺牲可调比等弊端。
2、表面燃烧超低氮燃烧器
表面燃烧超低氮燃烧器通常能够将NOx在全火范围内控制到30毫克以内,其优点是安装简单,不需要FGR烟气再循环管道;其主要缺点是需要过滤空气,加大了维护工作量;同时氧含量在7%左右,降低了部分燃烧效率。
3、表面燃烧+FGR超低氮燃烧器
表面燃烧+FGR超低氮燃烧器结合了表面燃烧的NOx控制优点和FGR降氧含量优点,可以实现在全火范围控制NOx到20毫克水平,同时控制氧含量在3%以内,最大化燃烧效率。其主要短处是设备成本提高。
The advantages and disadvantages of each low nitrogen burner are introduced
1. FGR low nitrogen burner
FGR low nitrogen burners can usually control NOx to 65 mg in full fire range with a limit of about 40 mg. Further reduction of NOx emissions may lead to combustion instability or sacrifice of adjustable ratio and other disadvantages.
2. Ultra-low nitrogen combustion burner is burned on the surface
Surface combustion ultra-low nitrogen burners can usually control NOx within 30 mg of full fire range. Its main drawback is the need to filter the air, increased maintenance work; At the same time, the oxygen content is around 7%, which reduces the partial combustion efficiency.
3. Surface combustion +FGR ultra-low nitrogen burner
The surface combustion +FGR ultra-low nitrogen burner combines the advantages of NOx control of surface combustion with the advantages of reducing oxygen content of FGR. It can control the level of NOx to 20 mg in the whole fire range and the content of oxygen within 3% to maximize the combustion efficiency. Its main shortcoming is the increase of equipment cost.
如果想了解更多关于
低氮燃烧器相关知识,请咨询
北京云顶国际节能环保技术有限公司。
For more information on low nitrogen burners, please consult Beijing chuangwei electromechanical equipment co., LTD.