移动床内高炉渣热载体与生物质热解液化实验研究

以移动床为高炉渣余热裂解生物质实验平台,研究高炉渣温度、粒径和生物质粒径等对生物质热解产物分布的影响。结果表明,生物油产率随着高炉渣温度的增加先增加后减小,当高炉渣热载体温度为650℃时,生物油产率最高;高炉渣粒径和生物质粒径越小,生物油的产率越大。炉渣温度650℃、粒径0~2mm,生物质粒径小于75μm,生物质油产率达到57.3%。生物油中含氧量和含水率较高,热值低,pH值为3.7。     

输煤系统粉尘综合治理应用实践

针对循环流化床锅炉用煤的特点,入炉煤要求煤的粒径小于8mm,平均粒径为1.5mm,典型输煤系统配置按照两级破碎两级筛分设计,原煤经粗碎机破碎至粒径小于35mm,再经细碎机破碎至粒径小于8mm.由于原煤含水通常7％ ～12％,粗碎前和粗碎后煤粉化程度低,细粉（粒径小于1.5mm）含量小于20％.粉尘经过粗碎机后的简单除尘治理,粉尘浓度容易达到10mg以内,污染情况较轻,通过喷淋水雾的投入调整可进一步使得降尘处理达到较好的效果.但经过细碎机后,煤粒径剧变,粒径小于1.5mm的超过80％,粒径小于0.5mm的超过20％,细粉尘量剧增,尽管在细碎机后的除尘器功率设计增大但实际仍不能较好地控制粉尘的飞扬,造成较严重的环境污染,严重时细碎后尾部区域粉尘量达到20mg/m3.     

烟秆裂解实验研究

系统地研究了以烟秆为原料裂解制备生物质焦油的工艺参数,以及原料粒径、裂解温度、添加剂用量对裂解产物组成的影响。结果表明,当裂解温度在550℃左右,原料粒径为0.425～1.000 mm,添加剂凹凸棒土用量为烟秆的100%时,生物质焦油产率最高,为47.9%,而残焦及气体得率分别为17.6%和34.5%。烟秆裂解得到的生物质焦油,其成分复杂。分离提纯生物质焦油中的较大组分尼古丁,可用于医药、食品和饲料、日用化工、染料及电镀等行业,应用前景相当广泛,烟秆裂解具有巨大的开发利用潜力。     

生物质烘焙预处理对气流床气化的影响

为考查生物质在烘焙预处理过程中的能量产率和颗粒研磨变化规律及对气流床气化总体效率的影响情况,在一套小型烘焙试验台上,对4种不同种类的生物质进行烘焙试验,并对固体产物研磨后进行粒径分析.最后通过小型生物质气流床进行气化试验.结果表明:生物质的能量密度随着烘焙温度的提高而升高,其中,中温烘焙(～250℃)能获得较好的固体和能量产率,减少能量损失;烘焙温度是烘焙过程中最重要的影响因素;烘焙可减少生物质研磨时的电耗,使其易磨;气流床气化试验中,烘焙生物质能够改善煤气成分,提高气化的总体效率.总之,在生物质气流床气化过程中,烘焙预处理能为生物质的粒径减小和随后的大规模利用提供了-个良好的解决途径.     

生物质废弃物在回转窑内热解研究--Ⅰ.热解条件对热解产物分布的影响

研究了生物质类废弃物在回转窑内的热解特性,讨论了物料种类,热解终温,加热方式,给料粒径和含水率对热解产物分布的影响。物料挥发份和热解终温高,加热快,粒径小,有利于燃气产率的提高以及炭产率的降低,而水分的提高会提高焦油的产率并降低炭的产率。同时,还研究了回转窑内的温升特性和热解气体的瞬态析出特性。     

生物质快速热解制取生物质油

根据浅床层鼓泡流化床的特点以及生物质的热解特性,研制出生物质快速热解的流化床热解反应器,并进行生物质快速热解制取生物质油的试验研究。通过定量给料研究不同温度、不同流化气流量对热解产物的影响规律。试验得出生物质油的产率达65%(kg/kg),并对产出的生物质油用色质联机进行成分分析得出生物质油的主要成分,通过热重分析得到了生物质油的热解特性。     

泥沙自然堆积孔隙率计算的试验研究

泥沙孔隙率是泥沙研究的一个重要物理量,确定泥沙孔隙率与粒径的定量表达式具有重要意义。通过室内试验,采用排水体积法测量不同粒径组泥沙、均匀沙、混合沙的自然堆积孔隙率,验证了细颗粒泥沙比粗颗粒泥沙孔隙率大的一般性结论,并通过试验结果分析与拟合,给出了均匀沙自然堆积孔隙率的经验公式。同时,运用圆球模拟泥沙颗粒的方法求得均匀沙的理论孔隙率,当均匀沙的中值粒径小于4.5mm时,圆球理论孔隙率与实测孔隙率的相对误差小于3%,得到的理论孔隙率较可靠。     

微波热解生物质废弃物的研究

利用微波热裂解生物质废弃物,使其转化为可直接利用的能源,是一种非常重要的处理工艺。运用自行研发的单模谐振腔微波设备对生物质废弃物进行热解反应试验,考察了微波功率、反应时间、含水率和物料粒径对木屑热解的影响,得到较优的反应工艺条件:微波功率为2.0 kW,反应时间为8 min,含水量为20%,物料粒径为0.5~0.8 mm。分析研究了固、液、气3种热解产物:固体产物(炭)的性质得到了改善;生物油主要是芳香烃类化合物和呋喃类化合物的复杂混合物;热解气体产物主要为CO,CO2,甲烷等,热值相对较高。     

水蒸气气氛下生物质热解制取富氢气体试验研究

以水蒸气为流化气在鼓泡流化床中进行木屑的热解特性研究,考察一些主要参数[如热解温度、生物质颗粒粒径、水蒸气/生物质(S/B)]对产气率和目标气体(H2,CO)产率的影响.试验结果表明,提高热解温度和降低生物质颗粒粒径有利于气体的产生;在热解过程中加入水蒸气,能提高气体产率,但是水蒸气的引入量有一个最佳值.本试验中产气率和H2,CO的产率都随着S/B的增加先上升后降低,适宜的S/B为2～2.5.     

纤维素废弃物稀酸水解残渣制氢研究

对纤维素废弃物水解残渣催化气化制氢进行了研究,考察了气化温度、催化温度、催化剂颗粒粒径和S/B (单位时间内进入气化器中水蒸汽质量与生物质质量之比)4个主要参数对气体组成和氢气产率的影响并和以木屑为原料催化气化制氢进行了比较。在试验范围内提高气化温度、催化温度和S/B的值以及减小催化剂颗粒粒径对提高氢产率有利,其中气化温度和S/B对提高氢产率影响较大。气化温度在800～850℃内较为理想,催化剂颗粒的适宜粒径为2～3mm,S/B取1.5～2.0较佳;和木屑制氢相比,使用水解残渣制取的气体中CO和CO_2的体积百分比小,H_2/CO的值大,氢气含量高,有利于后续处理,且氢产率大,对制氢有利。     

An experimental study on a novel shredder for municipal solid waste (MSW)

Based on composition and volume-mass properties of MSW (i.e., unit weight, void ratio, and water content), a new way for the breakage of the organic MSW is presented to effectively convert MSW to heat and fuel gas. A lab-scale shredder consisting of compaction and shredding chambers is designed and the breakage process of MSW in the shredder can be divided into three successive phases: deformation, further deformation, compressive shearing. The performances of the shredder, such as the effect of the rotor velocity and hydraulic pressure on product size distribution and specific energy are investigated. The results show that with hydraulic pressure the specific energy is reduced, and size distribution of product is finer. When hydraulic pressure is constant, the specific energy decreases with increasing rotor velocity, while the products size distribution is coarser.     

A novel biomass pulverization technology

In order to improve fuel quality of biomass, a novel biomass crushing system was presented. In this paper there were different biomasses, namely pine chips, corn stalk and cotton stalk, chosen for size reduction study. The production process was described and physical characteristics (particle size distribution, micro-morphology and bulk density) of biomass powder were investigated. The results show that 95% of biomass powders are below 200 μm in size, and the bulk density is significantly increased after pulverization. The micro-morphology of biomass powder changes with biomass species, corn stalk presents flake, different with the block structure of cotton stalk. Compared with hard straw, finer particles are more easily achieved for the pulverization of soft straw in the crushing system.     

Recovering of forest biomass from Spanish hybrid poplar plantations

Residues recovering from traditional poplar plantations for timber production are a potential relevant biomass source in Spain and other temperate countries. Three different residual biomass harvesting systems have been work-studied in order to characterize the work methods and analyze their productivity and cost. Two were oriented to branches, top and/or energy wood collection, chipping and transport using different work methods, while the other one consisted of after-logging stumps removal and shredding. Different sized and powered chippers worked in the two first cases, besides different farm tractors with trailers for off-road chips transport. Also the trucks and the loading machines were different. In the third site, a backhoe excavator removed the stumps, and a bucket loader collected them to be grinded by a shredding machine. Productivity and cost have been analyzed using IUFRO standards, providing average figures and, when possible, predictive productivity equations. Most capital-intensive equipment option has shown to be most productive, but less investment requiring system is cheaper and may be most interesting for some enterprise and plantation sizes. In addition, logistics of biomass and timber supply has been analyzed, and some indications about equipment sizing, machine annual production and relocation costs related to supply area and average plantation size are provided.     

电厂生物质灰渣全组分分选及特性试验研究

根据生物质灰渣在不同领域进行资源化利用时粒径R的特征差异,通过磁选与筛分串联使用的方式对生物质电厂发电作业产生的生物质灰渣进行分选。将生物质灰渣原料分选成1号（R > 5 mm）、2号（R为2～5 mm）、3号（R为1～2 mm）、4号（R为0.5～1 mm）、5号（R为0.25～0.5 mm）和6号（R < 0.25 mm）等6种粒径规格,各规格生物质灰渣质量分数分别为26.3%、17.5%、17.6%、19.7%、14.3%、3.8%。1、2号生物质灰渣因其粒径较大,一般多作为填埋路基、建筑等原料;3、4和5号生物质灰渣特性研究结果以及现有将其应用于水处理方面的相关研究成果为将该规格生物质灰渣作为水处理的一种新型功能性材料提供了依据;6号生物质灰渣因其粒径小以及富含Fe、P等营养元素,故一般可作为复合化肥的原料应用于农业生产。     

生物质粉体燃烧特性的研究

文章提出了一种生物质粉体燃烧模型,根据此模型设计了专用的燃烧炉.研究揭示了生物质粉体燃烧特性突出表现为体积特性,其次是粒径特性,同时温度场的分布验证了燃烧模型的合理性.当粉体粒径为0.177mm左右,每千克粉体燃料配送4m3风量时,燃烧效果与破碎成本最优化.而且风粉混合物可以像燃气一样输送、控制和燃烧.这种新的燃烧方式对提高生物质的燃烧效率、改善结渣现象有重大的意义,并为生物质能的利用开辟了一条新途径.     

Effect of densification variables on density of corn cob briquettes produced using a uniaxial compaction biomass briquetting press

Densification of loose biomass improves its properties for use as fuels. To design efficient briquetting equipment, there is a need to study properties of briquettes under different conditions. In this study, the effects of process variables (pressure, temperature, and hold time) and a material variable (particle size) on the density of corn cob briquettes were investigated. It was discovered that increasing the pressure, temperature, and particle size had positive effects on the density of biomass briquettes. The density of biomass briquettes produced using the selected values of pressure (9, 12, and 15 MPa), temperature (90°C and 120°C), hold time (7.5 and 15 min), and particle size (<2.5 mm and >2.5 mm) ranged between 570 and 1300 kg/m³.     

Prototype for the harvesting of cultivated herbaceous energy crops,an economic and technical evaluation

The scope of this study was to evaluate a multi-purpose prototype, the biotriturator, for the harvesting of biomass species cultivated in Northern Italy that would allow the baling of biomass to reduce the handling and storage costs. Harvesting trials were conducted on two herbaceous perennials: giant reed (Arundo donax L.) and switchgrass (Panicum virgatum L.), plus a herbaceous annual fiber sorghum (Sorghum bicolor L. Moench).A technical and economic evaluation compared three harvesting systems in which the biomass was shredded with the biotriturator. The first system was a cutting-shredding-baling in the same operation. The second required two successive steps, the first was cutting and shredding with the biotriturator, the second was baling. The third harvesting system required three successive steps: cutting and shredding with the biotriturator, windrowing with star wheel rakes and baling. While the first and second systems were evaluated on the two perennial crops the third was evaluated on an annual crop.Considering the hectares that can be covered by the biotriturator (170 ha of sorghum and 270 of switchgrass, with an average annual use of 200 h) and the total harvest cost (9.9–12.1 € Mg⁻¹ dry biomass), the harvesting system represents an effective solution for situations like that in Italy, where average farm sizes are small.     

Particulate matter emission and K/S/Cl transformation during biomass combustion in an entrained flow reactor

This study aims to demonstrate the effect of ash chemistry, especially, the transformation of potassium (K), chlorine (Cl), and sulfur (S) species, on the fine particle emission during biomass combustion. Biomass was burned in an entrained flow reactor at varied temperature from 1000 to 1300 °C, where fine particles were sampled using a 13-stage low pressure impactor, and the morphology and composition of the fine particles were analyzed. The fates of K, Cl, and S during biomass combustion were compared between the entrained flow reactor and the muffle furnace. Results show that the particle size distributions of PM₁₀ are bimodal for all studied cases. A higher concentration of fine-mode particle is observed at 1000 °C, with the peak position at 0.274 μm. When the temperature is increased from 1000 to 1100 °C or higher, the concentration of fine-mode particle is reduced by about 50%, and its size becomes smaller with a peak position at 0.097 μm. K, Cl and S are enriched as potassium chloride and sulfate, dominantly in PM_1.0; while Mg, Ca and Si are enriched in PM_1.0–10. A certain amount of sulfur in PM_1.0 at 1000 °C is observed, while the sulfur disappears above 1100 °C. This indicates that the process of potassium sulfation tends to occur at a moderate temperature, and affects the emission amount and the particle size distribution of particulate matters. Analyzing results of the fates of K, Cl and S in the particle phase indicate a completed sulfur-release from biomass ash above 1200 °C, as well as a maximum capture efficiency for potassium-containing vapors at 1100 °C, which results in a minimum PM_1.0 emission at 1100 °C.     

Use of fine-grained shredder dust as a cement admixture after a melting, rapid-cooling and pulverizing process

Shredder dust is a residue, which is removed from valuable ferrous metals found in scrap automobile and electronic waste. It is also an industrial waste byproduct which, under legislation in place since April 1996, must be disposed of in landfill sites. One method of disposing shredder dust is by scorification, however, this is a costly process and therefore impractical. Costs could be reduced if the shredder dust had a valuable use, and, in this paper, the authors examine its effectiveness as a cement admixture.

First, molten shredder dust was crushed for use as a cement admixture. However, it was difficult to crush it completely because metallic grains were mixed in with molten shredder dust. These particles were removed by sifting and the molten shredder dust was crushed once again. Eventually, a fine 75 μm and less powder type of slag was obtained. This slag was mixed with Ordinary Portland Cement (OPC) to form a cement mortar and subsequently a mortar test was conducted. From the test results, it was found that the long-term strength of the cement did not deteriorate even when it included 30% by weight of the pulverized molten shredder dust.     

Analysis of cold flow fluidization test results for various biomass fuels

A systematic theoretical and experimental study was conducted to obtain hydrodynamic properties such as particle size diameter, bulk density, fluidizing velocity, etc. for locally available biomass residue fuels in Malaysia like rice husk, sawdust, peanut shell, coconut shell, palm fiber as well as coal and bottom ash. The tests were carried out in a cold flow fluidization bed chamber of internal diameter 60 mm with air as fluidizing medium. The height of the chamber could be raised up to 630 mm by five separate cylindrical rings. Bed-pressure drop was measured as a function of superficial air velocity over a range of bed heights for each individual type of particle. The data were used to determine minimum fluidization velocity, which could be used to compare with theoretical values. The particle size of biomass residue fuel was classified according to Gildart's distribution diagram. The results show that Gildart's particle size (B) for sawdust, coal bottom ash, coconut shell have good fluidizing properties compared to rice husk, type (D) or palm fiber, type (A). The bulk density and voidage are found to be main factors contributing to fluidizing quality of the bed.