小型生物质颗粒燃料锅炉燃烧室设计研究

生物质能的开发利用越来越受到国际关注。在我国北方地区还有大量玉米秸秆没有得到能源化利用,小型锅炉作为生物质能转化装备其关键技术还有待突破与完善。为解决小型锅炉燃用玉米秸秆颗粒燃料过程中出现的问题,分析了燃用玉米秸秆颗粒燃料的小型锅炉燃烧室结构合理性设计的要求,设计了由象鼻状前炉拱和阶梯状火床组成的燃烧室结构,使玉米秸秆颗粒燃料的燃烧在燃烧室内分为气体燃烧区域和固体燃烧区域。经过在10kW热水锅炉燃烧玉米秸秆颗粒燃料的热工实验检验,该燃烧室结构解决了小型生物质锅炉焦油污染、燃烧不完全、不稳定以及玉米秸秆颗粒燃料灰渣结焦问题,为玉米秸秆能源化利用开辟了新途径。     

两种不同生物质成型燃料燃烧特性实验研究

以木质颗粒和玉米秸秆颗粒两种生物质成型燃料为研究对象,通过热重分析和生物质燃烧实验台对两种成型燃料的燃烧特性展开研究并将二者的试验数据进行对比分析。实验结果表明:两种生物质颗粒燃烧过程具有相似性,但在反应速率与燃烧特征参数上存在明显差异。与玉米秸秆颗粒相比,木质颗粒着火温度高,着火时间晚,但燃尽时间短;在燃烧初始阶段木质颗粒的反应速率低于玉米秸秆颗粒,而后又高于玉米秸秆颗粒,燃烧过程中木质颗粒最大反应速率明显大于玉米秸秆颗粒;木质颗粒的可燃特性、燃尽特性和综合燃烧特性指数均优于玉米秸秆颗粒;木质颗粒在低温段和高温段的活化能均高于玉米秸秆颗粒。     

混合生物质颗粒燃料的燃烧特性

从生物质燃料的灰熔融性和热值两个关键性的特性指标着手,以玉米秸秆和水稻稻壳作为主要原料,用试验优化设计和分析的方法 ,寻求混合生物质颗粒燃料的优化配方,提高混合生物质颗粒的软化温度ST>1 400℃,有效地解决了玉米秸秆颗粒结渣问题。对混合生物质颗粒进行了热重试验研究和燃烧机理、动力学特性分析,结果表明:混合生物质颗粒具有易着火和单峰值热解特性,燃烧性能良好。此研究为改善单一成分生物质燃料的燃烧性能,推广利用生物质能提供指导性建议。     

玉米秸秆颗粒燃料燃烧特性的试验研究

为了研究玉米秸秆颗粒燃料的燃烧特性,以一个小型反烧单元体炉为试验装置,分别进行了不同料层、不同水分、不同空气量下的燃烧试验,了解其燃烧特性,如点火时间、燃烧时间、燃烧过程及燃烧后的结渣现象。试验结果表明,玉米秸秆颗粒燃料易点燃,燃烧温度高,但燃烧时间短,结渣严重;料层高的玉米秸秆颗粒燃料燃烧时间相对长,但燃烧温度低,轻微结渣;干燥处理过的玉米秸秆颗粒燃料点火时冒黑烟现象明显减轻;加大燃烧过程的空气量时,玉米秸秆颗粒燃料不结渣。     

燃煤链条锅炉改燃生物质颗粒燃料的方案研究

生物质颗粒燃料取代常规煤燃料对节约常规能源、优化我国能源结构、减轻环境污染具有积极的意义。生物质颗粒燃料与常规煤燃料的特性有较大的区别。当将燃煤锅炉改造为燃生物质颗粒燃料锅炉时应采取相应的改造措施。以本公司锅炉为实例对燃煤链条锅炉的炉膛和燃烧系统进行了改造,通过对炉拱、炉排、风室、卫燃带、上料系统、燃烧控制系统进行改造实现了锅炉与生物质颗粒燃料燃烧的良好匹配。能效和环保测试结果表明,锅炉改燃生物质颗粒燃料后热效率提高,污染物排放符合标准要求。     

生物质固体成型燃料抗结渣研究进展

生物质固体成型燃料具有易储存、运输及使用方便、清洁环保、燃烧效率高等优点,是开发利用生物质能的主要方向之一.但秸秆类生物质原料中无机元素(包括K,Na,Cl,S,Ca.Si,P等)含量较高,导致了生物质固体成型燃料在热化学转化利用过程中出现结渣现象,不仅对燃烧设备的热性能造成影响,而且危及燃烧设备安全,成为阻碍生物质同体成型燃料推广应用的主要因素.文章分析了秸秆类生物质燃料的结渣机理,介绍了国内外生物质燃料抗结渣特性的研究现状,探讨了原料预处理、添加剂和颗粒密度对燃料抗结渣特性的影响,最后分析了目前生物质抗结渣研究中存在的问题,并提出了未来的研究方向.     

秸秆成型燃料双胆反烧炉的设计

根据秸秆成型燃料的单颗粒燃烧试验,分析了秸秆成型燃料的燃烧速度、燃烧机理和燃烧动力学特性,总结了秸秆成型燃料的燃烧规律,并根据秸秆成型燃料燃烧特性,研制出适合于生物质秸秆成型燃料燃烧的双胆反烧锅炉。该锅炉采用双层炉排反烧结构,可使成型燃料连续稳定燃烧,同时基本上解决了秸秆燃烧的结渣、飘尘问题。试验结果表明:该锅炉燃烧效率高达99.23%~91.75%,而且烟气中的烟尘含量,氮氧化物及二氧化硫含量远低于国家锅炉的污染物排放标准要求。图1表6参10     

秸秆压块户用采暖装备设计与性能测试

为解决当前秸秆压块燃料采暖炉存在的燃烧不稳定、燃烧效率和热效率低、封火或低温缺氧燃烧情况下焦油生成量大等问题,设计了一种具有自动送料功能的秸秆压块采暖装备,自动送料装置能够实现12 h连续稳定输送块状燃料(输送量为2.5~3.5 kg/h),彻底取消了采暖炉夜间封火工艺,解决了炉内燃烧不稳定问题;采暖炉双燃烧室结构实现了秸秆压块燃料的分区燃烧和低温燃烧,有效防止焦油凝结和灰分结渣,降低污染物排放。经计算,反平衡综合热效率高达80.11%。反算得体积热强度为247.3 k W/m~3,炉排热强度为167k W/m~2,故推荐分区燃烧生物质采暖炉体积热强度为200~300 k W/m~3,炉排热强度为150~200 k W/m~2。研究结果可为北方农村地区秸秆压块采暖装备的设计和应用提供参考。     

生物质成型燃料化学实验分析

生物质对提高能源利用率和缓解环境污染具有非常重要的作用。以松木、棉柴、花生壳和玉米秸秆这4种典型生物质成型燃料为实验材料,分析其化学特性。结果表明:当原料配比为80%松木+20%花生壳或玉米秸秆时,生物质成型燃料燃烧效率最高,其研究结果可为生物质燃料的高效清洁燃烧提供理论依据。     

上燃均衡供氧式生物质成型燃料炊事炉的设计与性能测试

为提高农村用能效率,依据生物质燃烧特性和热工计算标准,设计上燃均衡供氧式生物质成型燃料炊事炉。确定炊事炉的主要设计参数,构建相互独立的螺旋式分级配风系统及灰仓与风管相结合的自然进风系统,并对炊事炉的性能进行测试。结果显示炊事炉热效率为40.25%,炊事火力强度为3.32 kW,烟尘、CO、SO_2、NO_x等烟气污染物排放均符合国家相关标准,可保证成型颗粒燃料的充分燃烧,提高燃烧性能。     

家用生物质颗粒燃料炉的效益分析

家用生物质颗粒燃料炉是一种新型的炊事炉具,是现行传统炉具的更新换代产品,具有良好的经济效益和社会效益.     

Thermogravimetric studies of the behavior of wheat straw with added coal during combustion

The combustion behavior of biomass and biomass–coal blends under typical heating conditions was investigated. Thermogravimetric analyses were performed on bituminite coal, aspen strawdust and wheat straw used alone and blended with different coal weight ratios. The behavior of biomass fuels in the burning process (different rates of volatilization, char burning and heat production) was analyzed, and the effects of a cold molding procedure for wheat straw on the burning properties were investigated. In addition, the kinetic parameters for the thermal conversion of each fuel were determined. Cold molding led to easier firing, and 5% coal was identified as the ideal ratio to achieve similar heat release characteristics to strawdust. Such a mixed pellet fuel with burning characteristics similar to aspen wood can be produced to take advantage of the wide design basis for wood-fired boilers.     

The characteristics of air pollutants from the combustion of biomass pellets

Biomass is renewable clean energy. The aim of this study is to explore the combustion properties and emission characteristics of NO_X, SO₂, PM, and HCl in the combustion process of biomass pellet fuels. In this study, three kinds of fuels (pine sawdust, mixed wood, and corn straw) were selected to be studied by using a tube furnace to simulate industrial boiler. Experiments were conducted under different combustion conditions (combustion temperature and air flow). The results show that pollutant emissions were related to fuel type, combustion temperature, and air flow. The emissions of NO_X were contingent on N content in the fuel and the peak emissions of NO_X appeared in the range of 50~600 mg/m³ at 4 L/min and 700℃. The emissions of SO₂ were related to combustion condition and close to zero under the condition of sufficient combustion. The emissions of HCl and particulate matter (PM) increase with the rise of temperature, but the emission of PM was minimal at 800℃. Average HCl emission was 0.2~0.5 mg/g under steady-state conditions (4 L/min and 700℃). All in all, the pollutant emissions of biomass pellet fuels during combustion are lower than those of the traditional fuel, and the combustion efficiency is relatively higher.     

高效燃用生物质颗粒蒸汽锅炉的研究与设计

介绍了生物质颗粒燃料的燃烧特性,针对燃用生物质颗粒燃料的蒸汽锅炉结构设计的要求,提出了增大锅炉炉膛结构,改善一二次进风的配比,采用二次进风热能回收和PLC自动控制等方面的改进措施。     

Reprint of: Pelletizing properties of torrefied wheat straw

Combined torrefaction and pelletization are used to increase the fuel value of biomass by increasing its energy density and improving its handling and combustion properties. However, pelletization of torrefied biomass can be challenging and in this study the torrefaction and pelletizing properties of wheat straw have been analyzed. Laboratory equipment has been used to investigate the pelletizing properties of wheat straw torrefied at temperatures between 150 and 300 °C. IR spectroscopy and chemical analyses have shown that high torrefaction temperatures change the chemical properties of the wheat straw significantly, and the pelletizing analyses have shown that these changes correlate to changes in the pelletizing properties. Torrefaction increase the friction in the press channel and pellet strength and density decrease with an increase in torrefaction temperature.     

生物质成型燃料技术及应用前景

分析了现国内生物质电厂集中存在的燃料问题,而生物质成型燃料能够解决秸秆运输、储存、防火等问题,具有广阔的发展前景。对比介绍了生物质成型技术,分析生物质成型燃料的燃料特性。结果表明,生物质成型燃料可以改善燃烧特性,燃烬时间长,有利于提高生物质灰熔点。     

The emissions from a space-heating biomass stove

In this paper, the flue gas emissions of carbon monoxide (CO), nitrogen oxides (NO_X), sulphur dioxide (SO₂) and soot from an improved space-heating biomass stove and thermal efficiency of the stove have been investigated. Various biomass fuels such as firewood, wood shavings, hazelnut shell, walnut shell, peanut shell, seed shell of apricot (sweet and hot seed type), kernel removed corncob, wheat stalk litter (for cattle and sheep pen), cornhusk and maize stalk litter (for cattle pen) and charcoal were burned in the same space-heating biomass stove. Flue gas emissions were recorded during the combustion period at intervals of 5 min. It was seen from the results that the flue gas emissions have different values depending on the characteristics of biomass fuels. Charcoal is the most appropriate biomass fuel for use in the space-heating biomass stoves because its combustion emits less smoke and the thermal efficiency of the stove is approximately 46%.     

The properties of pellets from mixing bamboo and rice straw

Rice straw pellets are the main type of biomass solid fuel and have great potential as a bioenergy resource of the future in China. But it also showed important problems because of its high content of ashes and its low gross calorific value, reducing the possibility to be used in domestic heating. It was certified that mixing different types of biomass materials was helpful to improve the properties of pellets. To improve properties of rice straw pellets and investigate the effect of mixing bamboo and rice straw on the pellet properties, some properties of pellets, manufactured using different mixing ratio of bamboo and rice straw particles, were determined in this research. It can be concluded from this research that physical properties of all pellets meet the requirements of Pellet Fuels Institute Standard Specification for Residential/Commercial Densified except for bulk density of pellets, manufactured using mixing ratio (≤3:2) of bamboo and rice straw. The inorganic ash and gross calorific value of rice straw pellets cannot meet the requirement of Pellet Fuels Institute Standard Specification for Residential/Commercial Densified (8.0%) and the minimum requirement for making commercial pellets of DIN 51731 (>17,500 J/g). Both properties are improved through mixing bamboo particles and rice straw particles. It is significant that inorganic ash content and gross calorific value of pellets, manufactured using mixing ratio (≥3:2) of bamboo and rice straw, were lower than 8.0% and higher than 17,500 J/g, respectively. This also shows that mixing different biomass materials is an effective way to optimize properties of biomass solid fuel. All pellets after improvement are proposed as biomass solid fuel and have the potential to be developed as commercial pellets on an industrial scale in China.     

Wood fuel use in the traditional cooking stoves in the rural floodplain areas of Bangladesh: A socio-environmental perspective

A study was conducted, using a multistage simple random sampling design, to determine the structural characteristics of the traditional cooking stoves, amount of wood fuel consumed in the rural floodplain areas in Bangladesh, and also to figure out the socio-economic and environmental consequences of wood fuel usage in the traditional cooking stove. The study showed that family size, income, amount cooked and burning hours significantly affected the amount of wood fuel used per family per year. Taking into account different family sizes, the study observed that 4.24 tonne fuelwood were consumed per family per year. The study showed that 42% of families used only biomass fuel, 5% used liquefied petroleum gas (LPG) and 53% used kerosene along with biomass fuels. The main source of biomass fuel was homestead forests (40%). It has been figured out that the incomplete combustion of biomass in the traditional cooking stove poses severe epidemiological consequences to human health and contributes to global warming. The study also showed that 83% of the respondents would prefer improved cooking stoves over traditional cooking stoves.