煤粉燃烧热态试验研究方法综述

燃烧器是煤粉锅炉的核心部件,燃烧器的性能关系到煤粉燃烧程度和污染物排放水平。采用热态试验方法研究燃烧器的性能,获得的数据对于开发高效低氮煤粉燃烧器更具有指导意义。笔者从基本原理出发论述了煤粉燃烧各热态试验方法的优缺点以及适用场所,对于火焰温度测量,热电偶测温操作简易、便捷,但精确度不高,且只能同时单点测温,对火焰扰动较大;抽气式高温测温准确度较热电偶高,但操作复杂,对气流易造成干扰;光谱法有足够的精确度,对火焰扰动较小,可同时多点测量,能进行三维温度场重建,但相较于热电偶测温法和抽气式高温测温法,光谱法操作复杂、造价高。对于气固相采集,冷却取样法是准确采集燃烧器内煤粉燃烧烟气实时成分的常用手段,由于水的比热容较大,因而水冷式取样法是应用最广的取样方法;XPS和灰示踪法均为煤粉燃烧过程中测量煤焦样品化学组成的常用方法,均可定量分析固体煤焦样品,但两者检测重点不同,XPS主要分析化学官能团组成,灰示踪法着重分析其元素组成、计算煤转化率等;XPS操作较繁琐,灰示踪法操作简单。对于气体样品的检测和分析,电化学检测法和红外检测法均可测量多种气体,具有较强的适用性,但红外检测法检测范围更广;溶液吸收法适用于检测NH3和HCN浓度,但由于测量中不易捕捉、较为繁琐,且易受其他因素干扰,工程应用较少。在现场测量时,尽可能采用多种测量方法或多次测量,以规避可能导致误差的因素。通过多种测量方法可建立煤粉燃烧器热态下三维温度场、三维气氛场等,多维度研究煤粉的燃烧过程及污染物生成过程,从而采取有效手段治理污染,对于新型高效低氮燃烧器的开发以及煤粉工业锅炉污染物的综合治理具有重要意义。

A review of experimental research methods for pulverized coal combustion hot-state

The burner is the core component of the pulverized coal boiler.The performance of the burner is related to the degree of pulverized coal combustion and the level of pollutant discharge.The thermal test method is used to study the performance of the burner,and the obtained data are more instructive for the development of high-efficiency and low-nitrogen pulverized coal burners.From the basic principles,the advantages and disadvantages of various thermal test methods for pulverized coal combustion and the applicable places were discussed.In the flame temperature measurement,the thermocouple thermometry is simple and convenient,but its accuracy is not high and can only measure temperature at a single point at the same time,which has a large disturbance to the flame.The accuracy of air-pumped high temperature thermometry is higher than that of thermocouples,but its operation is complicated and it is easy to cause interference to the air flow.The spectrometry has sufficient accuracy and less disturbance to the flame,multi-point measurement at the same time,and the measurement can be used to reconstruct the three-dimensional temperature field,but compared with thermocouple thermometry and the air-pumped high temperature thermometry,the spectral method has complex operation and high cost.In the collection of gas-solid phase samples,the cooling sampling method is a common method for accurately collecting real-time components of the flue gas in the burner. Because the specific heat capacity of water is large,the water-cooled sampling method is the most widely used sampling method.XPS and ash tracer are common methods for measuring the chemical composition of coal char samples during pulverized coal combustion. Both can be used for quantitative analysis of solid coal char samples,but the detection focuses of the two methods are different.XPS is mainly used to analyze the composition of chemical functional groups.Trace method focuses on analyzing its elemental composition,calculating coal conversion rate,etc.XPS operation is more tedious,while the gray tracer method is simple to operate.In the detection and analysis of gas samples,a variety of gases can be measured by both electrochemical detection and infrared detection,which has strong applicability,but the infrared detection has a wider detection range.The solution absorption method is suitable for detecting the concentration of NH3 and HCN,which is tedious and difficult to capture in the measurement,and easy to be interfered by other factors,so it has fewer engineering applications.Therefore,when measuring in the field,a variety of measurement methods or multiple measurements are used as far as possible to avoid factors that may cause errors.Three-dimensional temperature field and three-dimensional atmosphere field of the pulverized coal burner in the hot state can be established through a variety of measurement methods. The pulverized coal combustion process and pollutant generation process can be studied in multiple dimensions,so as to take effective measures to control pollution.It is of great significance to the development of burners and the comprehensive treatment of pollutants from pulverized coal industrial boilers.