林木基与秸秆基生物质颗粒燃烧特性对比研究

选取落叶松、红松作为林木基生物质颗粒原料,选取棉秆、玉米秸秆作为秸秆基生物质颗粒原料,采用江苏东工生物质能研究院有限公司开发的生物质颗粒燃烧器为试验装置,分析了4类生物质颗粒的燃烧特性、污染物排放特性及底灰结渣特性。结果表明:水分越低、挥发分越高、灰分越低,所需点火时间越短;运行阶段林木基与秸秆基生物质颗粒能够充分燃烧,CO排放浓度达到最小;林木基与秸秆基生物质颗粒燃烧烟气中NOx排放浓度低于国家标准,NOx排放浓度与N含量基本成正比,NOx生成方式主要为燃料型反应机制;软化温度越高,结渣率越低,当软化温度达到1390℃以上时,不会发生结渣。     

液态纳米燃料及其强化燃烧研究进展

液态纳米燃料是一种由纳米颗粒与燃料基液组成的特殊液-固两相混合物,具有热传输能力强、催化助燃性能好、污染物排放低等诸多优点。然而,纳米颗粒的小尺寸特征使得液态纳米燃料的热/质输运机理、雾化蒸发特性以及燃烧化学反应过程极其复杂,导致液态纳米燃料强化燃烧理论与应用研究至今还存在许多问题。本文首先介绍了液态纳米燃料制备与稳定性处理方法,其次分析了纳米颗粒影响下液态燃料热物性参数、雾化、蒸发与燃烧特性的研究进展,然后重点综述了液态纳米燃料在动力装置性能提升与污染物减排领域的潜在应用价值。在此基础上,对液态纳米燃料强化燃烧技术的未来研究方向进行了展望,指出高效可控制备方法、热物性参数变化规律与数学描述、催化助燃与减排机制是液态纳米燃料领域亟需解决的重点问题。     

生物质颗粒燃烧锅炉污染物释放规律及运行管理

生物质颗粒燃烧具有产量大、污染小、CO2零排放及可再生等优点.论述了生物质颗粒燃料燃烧锅炉的使用及其污染物的释放情况,总结了生物质燃烧锅炉国内外的发展现状,对锅炉实际运行中的问题提出可行性建议,同时展望了未来生物质燃烧锅炉的发展前景.     

烟煤与生物质混烧基础实验分析

在给料方式为下部进料的美国Harman热风炉内进行了烟煤煤棒和生物质棒的燃烧实验,通过燃烧效果和污染物排放情况的特性对比,考察了两种燃料的优缺点;将不同比例的烟煤和生物质的混合样品在Netzsch热重分析仪中进行燃烧动力学分析;结果表明,生物质燃料的烟尘排放指标高于烟煤煤棒,二者的优缺点可以互补,烟煤中掺烧生物质可以提高燃烧效率,混合燃烧降低了反应活化能,着火温度和燃尽温度均前移;生物质燃料和烟煤按照合理配比混烧,可提高两种燃料的清洁高效利用水平。     

典型生物质燃料燃烧污染物排放综述

生物质能源是一种清洁能源,燃烧排放的二氧化硫、氮氧化物等污染物很少,但大量燃烧依然会对环境造成一定的影响。鉴于当前国内缺乏生物质燃烧相关标准,本文主要介绍了典型生物质燃料燃烧过程中主要污染物的排放情况。     

循环流化床锅炉数值模拟研究进展

对国内外研究者在CFB锅炉气固流动特性、炉内燃烧及污染物排放特性等不同实际问题开展的数值模拟研究进行了总结,主要对气固两相流、传热、煤颗粒燃烧和S、N污染物生成与控制几个部分的数值模型进行归纳整理,并将各部分模型与煤粉锅炉数值模型进行了比较.此外,从锅炉冷态数值模拟时的气固流动特性和热态数值模拟时的燃烧和污染物排放特性...     

浮法玻璃窑炉用燃料及其烟气污染物排放特性与治理技术分析

浮法玻璃制造业是一个高能耗行业,在生产过程中使用大量气体燃料、液体燃料、固体粉状燃料。目前,玻璃窑炉使用的主要燃料有天然气、发生炉煤气、石油焦粉和重油等。由于各燃料的组成、燃烧特性差异很大,对烟气污染物的形成有重要的影响。对浮法玻璃窑炉用燃料及其烟气污染物排放特性进行有效分析与梳理,对治理烟气污染物技术与方法的列举,可为其烟气污染物治理技术的选择提供参考。     

我国民用散煤使用现状及治理措施综述

概述了全国民用散煤使用现状,分析了我国不同煤种不同燃烧阶段污染物排放情况,包括颗粒污染物排放,气体污染物排放和VOCs排放情况。结合我国目前散煤燃烧防控存在的问题,并针对洁净型煤在推广、使用中出现的问题提出了相应的建议。     

洁净燃烧技术的应用

石油化工管式加热铲排放的尾气是大气污染的主要污染源之一，从燃料燃烧角度出发，分析了几种主要污染物的生成机理及燃料燃烧的影响因素，介绍了洁净燃烧设备的特点及应用情况，指出添加燃料添加剂、控制好燃烧工况及选用洁净燃烧设备能有效降低甚至脱除尾气中的污染物，达到洁净燃烧的目的。     

兰炭与秸秆混合燃料燃烧污染物排放和灰熔融性试验

兰炭具有热值高、灰分低、硫分低等优点，但挥发分含量低、着火温度高；秸秆热值低、挥发分含量高，着火温度低；二者着火特性具有互补性。为考察兰炭与生物质混合燃料燃烧的硫氧化物、氮氧化物排放和灰熔融性能，利用固定床试验系统研究了3种兰炭、麦秆和玉米秆单独及混合燃料污染物排放特性及掺混比例和燃烧温度对污染物析出的影响，并通过灰熔融测定仪分析灰样熔融性能。结果表明：混合燃料的硫氧化物、氮氧化物析出与掺混条件相关，原料组成和燃烧过程影响污染物析出特性。在燃料中掺混20%～30%玉米秆时，混合燃料固硫效果较好，氮析出率在0.04%左右。提高燃烧温度明显促进硫析出，而低于1 000℃时，府谷兰炭和玉米秆的掺混样具备良好的自固硫特性，氮析出率低于0.02%。另外，混合燃料的灰熔融温度介于两原样间，与混合比例存在一定相关性，兰炭的抗结渣特性明显优于玉米秆，掺混有助于改善秸秆的结渣特性。本研究为兰炭和生物质的清洁利用提供理论参考。     

Toxicological characterization of particulate emissions from straw,Miscanthus, and poplar pellet combustion in residential boilers

Wood pellets have been used in domestic heating appliances for three decades. However, because the share of renewable energy for heating will likely rise over the next several years, alternative biomass fuels, such as short-rotation coppice or energy crops, will be utilized. We tested particulate emissions from the combustion of standard softwood pellets and three alternative pellets (poplar, Miscanthus sp., and wheat straw) for their ability to induce inflammatory, cytotoxic, and genotoxic responses in a mouse macrophage cell line. Our results showed clear differences in the chemical composition of the emissions, which was reflected in the toxicological effects. Standard softwood and straw pellet combustion resulted in the lowest PM₁ mass emissions. Miscanthus sp. and poplar combustion emissions were approximately three times higher. Emissions from the herbaceous biomass pellets contained higher amounts of chloride and organic carbon than the emissions from standard softwood pellet combustion. Additionally, the emissions of the poplar pellet combustion contained the highest concentration of metals. The emissions from the biomass alternatives caused significantly higher genotoxicity than the emissions from the standard softwood pellets. Moreover, straw pellet emissions caused higher inflammation than the other samples. Regarding cytotoxicity, the differences between the samples were smaller. Relative toxicity was generally highest for the poplar and Miscanthus sp. samples, as their emission factors were much higher. Thus, in addition to possible technical problems, alternative pellet materials may cause higher emissions and toxicity. The long-term use of alternative fuels in residential-scale appliances will require technological developments in both burners and filtration.

Copyright © 2016 American Association for Aerosol Research     

生物质燃烧技术综述

利用清洁、可再生生物质能源燃烧发电技术日益受关注。本文介绍了生物质燃料特性、利用情况、当今主流燃烧技术及生物质燃烧发电概况及遇到的问题,同时还对生物质与煤混烧技术及城市生活垃圾焚烧发电作了简单介绍。     

Combustion and Heat Properties of Lignin–Containing Fuels

Results of studying the combustion process of pellet fuels produced on the basis of obsolete gun powder and lignin are described. The temperatures of diffusion combustion of the flame and coke of pellet fuels and the linear velocities of flame and flame–free stages of combustion are determined. A model is proposed, and calculation results for the radiant component in the overall balance of combustion heat of lignin–containing fuels are presented.     

Use of grey relational analysis to assess and optimize small biomass boilers

This paper presents a new methodology for the evaluation of the environmental and economic feasibility of combustion of different biomass fuels in small boilers. The study focuses on pellets as the basic co-firing product and forest residues as the complementary product. Although the co-firing of forest residues can be economically profin, it is difficult to evaluate the general economic advantages due to the worsening of combustion in terms of performance and emissions caused by the presence of the forest residues in the fuel mixture. The grey relational analysis of different energetic and emission variables and also residue prices allows for the definition of a new single variable called the grey relational grade. Thus, evaluation and optimization of complicated multiple responses can be converted into the optimization of a standardised single variable. Experimental analyses by means of the Grey theory of different forest residues have revealed the possibility of co-firing crust of pine combined with wood pellets as a way of reducing fuel costs, keeping performance and emissions within average standards in small pellet boilers.     

Characterisation of biomass and coal co-firing on a 3 MWth Combustion Test Facility using flame imaging and gas/ash sampling techniques

Co-firing of biomass with pulverised coal at existing coal power stations remains a practical option available to power plant operators and is being widely adopted as one of the main technologies for reducing greenhouse gas emissions. However, there is a range of technological problems that are not well understood. This paper presents experimental investigations into the co-firing of pulverised coal directly co-milled with 5–20% biomass on a 3 MWth Combustion Test Facility. A number of combustion parameters, including flame temperature and oscillation frequency and particle size distribution, were measured under a range of co-firing conditions. The gas species within the flame and fly ash in flue gas were also sampled and analysed. The experimental data collected are used to study the impact of biomass additions to pulverised coal on the combustion characteristics of the co-firing process. The relationships between the flame characteristics, gas species and ash deposition of the furnace are investigated. The results suggest that, due to the varying physical and chemical properties of the biomass fuels, the biomass additions have impact on the combustion characteristics in a very complicated way. It has been found that the biomass addition to coal would improve the combustion efficiency because of the lower CO concentrations and higher char burnout level in co-firing. In addition, NO_x emission has been found closely linked to the flame stability, and SO_x emission reduced in general for all co-firing cases.     

Peach and apricot stone combustion in a bubbling fluidized bed

In this study, a bubbling fluidized bed combustor (BFBC) of 102 mm inside diameter and 900 mm height was used to investigate the combustion characteristics of peach and apricot stones produced as a waste from the fruit juice industry. A lignite coal was also burned in the same combustor. The combustion characteristics of the wastes were compared with that of a lignite coal that is most widely used in Turkey. On-line concentrations of O₂, CO, CO₂, SO₂, NO_X and total hydrocarbons (C_mH_n) were measured in the flue gas during combustion experiments. By changing the operating parameters (excess air ratio, fluidization velocity, and fuel feed rate), the variation of emissions of various pollutants was studied. Temperature distribution along the bed was measured with thermocouples.During the combustion tests, it was observed that the volatile matter from peach and apricot stones quickly volatilizes and mostly burn in the freeboard. The temperature profiles along the bed and the freeboard also confirmed this phenomenon. It was found that as the volatile matter of fruit stones increases, the combustion takes place more in the freeboard region.The results of this study have shown that the combustion efficiencies ranged between 98.8% and 99.1% for coal, 96.0% and 97.5% for peach stone and 93.4% and 96.3% for apricot stones. The coal has zero CO emission, but biomass fuels have very high CO emission which indicates that a secondary air addition is required for the system. SO₂ emission of the coal is around 2400–2800 mg/Nm³, whereas the biomass fuels have zero SO₂ emission. NO_X emissions are all below the limits set by the Turkish Air Quality Control Regulation of 1986 (TAQCR) for all tests. As the results of combustion of two biomass fuels are compared with each other, peach stones gave lower CO and NO_X emissions but the SO₂ emissions are a little higher than for apricot stones. These results suggest that peach and apricot stones are potential fuels that can be utilized for clean energy production in small-scale fruit juice industries by using BFBC.     

Use of energy crops for domestic heating with a mural boiler

The combustion process of two residues from energy crops in a 12 kW mural boiler for domestic heating was studied. The fuels used were common reed (Arundo donax L.), sorghum (Sorghum bicolor L.) and forest pellet recommended by the boiler manufacturer. A comparison with the combustion process of two industrial residues (tomato residue and almond pruning) and other energy crop (Cynara cardunculus L.) has been established. The experimental tests carried out in “La Orden” farm on common reed and sorghum cultivation revealed a production of dry biomass of 35 and 30 t/ha, respectively. Previously, the fuels were characterised by means of the higher heating value, proximate and ultimate analyses. The influence of the residue type, fuel mass flow, draught and residues mixture on the combustion parameters has been studied. A TESTO 300 M-I analyzer was employed to determinate the principal parameters of the combustion process (CO₂, CO, and O₂ contents, fumes temperature, not-burnt gaseous and sensitive heat losses in the fumes, air excess coefficient, flow rate and velocity of the fumes, and efficiency). The behaviour shown by the two studied residues was similar to that of the forest pellet. The boiler efficiencies obtained with the maximum fuel mass flow (100%) and minimum draught (0%) were 84% and 85.3% for reed and sorghum pellets, respectively. The obtained efficiency with the forest pellet was 90.5%. The optimum residue mixture assayed was almond pruning (75%) and sorghum (25%), with a boiler efficiency of 87.2% for a mass flow and draught of 100% and 0%, respectively.     

A fundamental study on the control of the HCCI combustion and emissions by fuel design concept combined with controllable EGR. Part 2. Effect of operating conditions and EGR on HCCI combustion

In Part 1, the effects of octane number of primary reference fuels and equivalence ration on combustion characteristics of a single-cylinder HCCI engine were studied. In this part, the influence of exhaust gas recirculation (EGR) rate, intake charge temperature, coolant temperature, and engine speed on the HCCI combustion characteristics and its emissions were evaluated. The experimental results indicate that the ignition timing of the first-stage combustion and second-stage combustion retard, and the combustion duration prolongs with the introduction of cooled EGR. At the same time, the HCCI combustion using high cetane number fuels can tolerate with a higher EGR rate, but only 45% EGR rate for RON75 at 1800 rpm. Furthermore, there is a moderate effect of EGR rate on CO and UHC emissions for HCCI combustion engines fueled with n-heptane and RON25, but a distinct effect on emissions for higher octane number fuels. Moreover, the combustion phase advances, and the combustion duration shorten with the increase of intake charge temperature and the coolant out temperature, and the decrease of the engine speed. At last, it can be found that the intake charge temperature gives the most sensitive influence on the HCCI combustion characteristics.     

生物质气化技术的研究进展

近年来,由于世界能源与环境危机,生物质能作为一种清洁的、可再生的能源越来越受到世界的关注,其中生物质气化是利用生物质能最重要的方式之一。本文介绍了生物质气化技术的原理,生物质气化工艺及气化设备,并对影响生物质气化装置的优化设计的各种因素进行了分析与讨论,提出了生物质气化工艺过程亟待解决的问题,为生物质气化的发展提供了一定的参考。     

Abatement of emissions in small-scale combustors through utilisation of blended pellet fuels

This paper presents the results of a study carried out on a small-scale 10 kW fixed-bed combustor fired by blended pellet fuels burning on a thin depth fuel-bed. The use of the thin fuel-bed may contribute to major advances in the introduction of low-cost, fully automated small-scale combustors by eliminating de-ashing mechanisms, and improving operating conditions. The pellets were made by pressing the mixture of finely ground lignite or its by-product (xylite) with wood chips. The xylite (woody lignite) and the wood chips are wastes produced during the production of lignite fuel and timber, respectively. Therefore, using these materials to produce the high quality pellet fuel contributes to environmental conservation. Water and calcium hydroxide suspensions were used as pelletising agents playing the role of binders. The major objective was to study the improvement of the quality of the blended pellet fuels in regard to their combustion and emission behaviours when burned on the thin fuel-bed. The ignition and combustion behaviour of the pellets were compared to those of conventional lignite briquettes. The study proved that the pellets on the thin fuel-bed ignited faster and had steady burnout. The emissions of NO_x, SO₂, CO and hydrocarbon compounds were comparatively lower than those from burning of lignite briquettes in a domestic combustor. The addition of calcium hydroxide suspensions played not only the role of binding together the raw material blends, but also provided favourable Ca/S molar ratio optimum for considerable reduction of the SO₂ emissions. The need to reduce further the specific emissions of SO₂ leads to exceeding the proportional value of Ca/S molar ratio, which lowers the calorific value of the pellets. Thermogravimetric studies helped in establishing the comparative pyrolysis behaviours of the lignite and wood chips.