热解温度对依兰煤热解特性的影响分析

本论文在处理量为2.5 kg/h的热解实验装置上,分别以两种烟煤和一种油页岩为原料,考察了热解温度对热解产物产率、组成和性质的影响规律。实验结果表明,当反应温度分别为481℃、514℃、519℃时,六级煤、油页岩、造气入炉煤的焦油产率依次达到最高,产率分别为13.58%、12.54%、4.23%;在实验温度范围内,随着温度的升高,气体产率不断增加,且气体组分不断变化。     

煤的理化性质对生物质和煤共热解焦油性质的影响

将木屑分别与黑山煤、神木煤以不同比例掺混,利用自制热解干馏炉进行共热解实验。比较木屑的添加对共热解焦油、水和轻质焦油产率的不同影响,结合煤和生物质的热重分析结果与煤的13C核磁共振分析表征,探讨煤的结构、煤和生物质的热化学反应特性,对共热解焦油产率和品质的作用机理。结果表明:在一定配比范围内,木屑和煤之间的交互作用明显提高了共热解焦油中轻质组分的产率,同时热解水产率低于计算值;轻质焦油中的脂肪烃组分主要由木屑和煤热解产生的烷基自由基相互化合生成;煤热解产生的芳烃类自由基由于与生物质热解产生的羟基自由基生成杂酚化合物,从而抑制了热解水的生成。     

中药生物质原料与药渣热解特性对比研究

以饮料厂副产物中药渣、单成分中药材及其蒸煮残渣作为研究对象,分析因蒸煮作用导致的燃料理化性质差异,通过热重、管式炉等实验手段以及气相色谱仪、气相色谱-质谱联用仪等测试手段研究中药渣的热解气液固产物特性。结果表明:相比于中药材,药渣的挥发分有所提高,Na、K、Mg、Cl、Si等元素含量降低;基本有机官能团变化不大;蒸煮后,药渣的最大失重速率提高且失重峰向高温区移动,热解残余率降低;相同温度下,热解气热值蒸煮前后(15.04~18.57 MJ/m^3)变化较小,但比麦秆热解气热值(10.63~16.23 MJ/m^3)高;蒸煮后,相同温度下药渣的热解液相产率较高(55.72%~61.92%),而焦油中苯酚的相对含量降低;相同温度下,蒸煮会降低药材的固体产率(27.62%~30.76%),但有利于增加药渣热解半焦比表面积,进而有利于热解半焦的气化反应。     

煤热解过程中碱金属对碳黑形成的影响

通过分析担载碱金属Na的酸洗煤热解产物的浓度分布、化学结构与微观结构,研究碱金属对煤衍生碳黑形成的影响.结果表明煤热解产物的粒数与质量浓度分布分别在0.12μm与0.20μm附近存在峰值,无Na酸洗煤超细颗粒生成量较多;随着煤中含量增加,热解使Na先赋存于半焦中,抑制焦油的释放;之后过量的Na气化并抑制焦油向碳黑转化;Na可增加样品中含氧官能团含量,减少脂肪族化合物尤其是短链或支链化程度较高脂肪族化合物含量、增加芳香族化合物含量并降低芳香环稠化度;气化的Na可以造成碳黑微晶体晶格缺陷,形成一些嵌套或类晶体特异结构.     

温度对生物质热解产物有机结构的影响

在管式炉上研究了生物质在不同温度下的热解过程,采用傅立叶红外光谱仪研究了热解温度对稻草热解固体产物半焦和液体产物焦油的有机结构变化的影响,用色质联用仪(GC/MS)分析了焦油的主要成分随温度的变化。研究表明,生物质的热解主要集中在200～600℃,高温有利于气体产物的析出,半焦的量及其所含的有机官能团(C=O,C=C,C-H,C-O和OH等)随热解温度的升高快速减少;焦油的量随温度的升高先增大后减小,在500℃时达到最大值,焦油中官能团的种类较稳定,但是吸收峰强度随温度的升高呈减弱的趋势。     

煤与生物质共热解工艺的研究进展

热解是将固态原料转化为液体燃料、可燃气和焦的重要途径,是实现生物质资源清洁、高效利用的重要技术。将生物质与煤混合共热解是生物质资源利用的重要方法,两者混合热解不仅有助于降低CO_2的排放量,还能有效地解决能源短缺和环境污染带来的问题。文章综述了煤与生物质共热解技术的研究进展,系统地介绍了共热解过程中煤与生物质的相互作用以及热解温度、混合比例、滞留时间、升温速率、矿物质成分、物料粒径和热解反应器类型等因素对热解过程的影响,并对煤与生物质共热解技术的发展前景进行了展望。     

生物质热解煤气中焦油含量的影响因素

采用稻杆、稻壳和木屑作为原料,对生物质材料热解产生的煤气中的焦油含量进行了系统研究。采用冷态捕集方法进行焦油取样;焦油样品用重度分析方法确定煤气中焦油含量。结果表明,由于各种生物质原料的组成及结构不同,热解煤气中,焦油含量存在较大差异,热解温度由550℃升高到900℃以上,热解煤气中焦油含量迅速下降,下降幅度甚至达到70％,随生物质原料在热解反应器内滞留时间的延长,焦油含量也下降,同时给出并分析了焦油含量随热解温度和滞留时间变化的情况。     

煤热解研究的分析方法

为了让更多的科研工作者了解煤热解试验仪器及其分析方法,对热重-差热、红外、气相色谱、质谱等仪器分析方法的特征性能进行了综述,重点描述了其在原煤、半焦、焦油、热解气体等分析研究中的应用,同时简要介绍了一些先进的联合分析法在煤热解研究中的应用。另外还对热重分析仪(瑞士METTLER-TOLEDO公司生产TGA/SDTA851e热重/同步差热分析仪)、傅立叶变换红外光谱仪(Nicolet公司生产的5700型)、气相色谱仪(5975MSD)、质谱仪(6890GC)进行了介绍。     

半焦催化剂对生物质热解产物催化重整的试验研究

利用自行建设的两段式热解炉为试验平台进行重整试验,以松木屑经成型的棒状颗粒原料,热解半焦为催化剂,通过对气相组分、焦油傅里叶变换红外光谱及半焦催化剂催化重整前后扫描电镜与X-射线衍射变化等进行试验测试分析,研究生物质在添加和不添加半焦催化剂条件下热解形成热解气、焦油、焦炭三相产物的规律。结果表明:对比添加和未添加半焦催化剂,燃气产率由650℃时的43.7%升高到46.4%,850℃时的49.7%升高到54.1%,燃气产率和H₂的升高速率明显提高,H₂体积分数增加;加入半焦催化剂后,焦油生成率明显下降,液相产物气态时经过半焦催化剂高温催化重整后,O-H官能团的化合物明显减少,C-H、C-O、C=O等伸缩振动的特征峰峰面积有所加强,特征峰峰数减少;半焦催化剂在催化重整过程中参与了反应,表面断裂加重了积灰堵塞孔道的现象,催化活性降低。     

我国煤热解多联产技术的发展概况

目前煤热解多联产已成为一项提高煤炭资源综合利用率的高新技术,是未来洁净煤主要的发展方向.以煤热解为核心的多联产工艺已成为我国煤炭利用的主要途径,通过煤热解多联产技术可有效地将煤炭化工和电力工业结合起来,不仅解决了煤炭利用率低下、化工产品制造成本高等问题,而且对我国的环境保护有着重要影响.介绍了国内外煤热解多联产工艺的研究状况,并对国内几种典型的煤热解多联产工艺进行了评述,总结了当前煤热解多联产工艺的优缺点和主要发展方向.     

High-temperature solar pyrolysis of coal

Subbituminous coal from Western United States was pyrolyzed by directly exposing 50 mg powdered samples to concentrated solar radiation. It was found that exposure to flux levels > 200 W/cm² for 12.5 s devolatilized 51 per cent of the coal. At flux levels between 100 and 200 W/cm² devolatilization was slightly less. Gas yield was a maximum of 31 mmol/g coal at a flux of 100 W/cm² and decreased slightly with increasing flux. Gas yields were more than twice as great as those obtained by a laser technique developed to simulate solar pyrolysis. In experiments with spectral cut-off filters there was no effect due to changing the wavelength distribution of sunlight.     

Finding order in coal pyrolysis kinetics

A number of experiments have suggested that the rate constants for the release of tar and for the thermal decomposition of the various functional groups in coal pyrolysis depend on the nature of the bridging bond or of the functional group, but appear relatively insensitive to coal rank for lignites, subbituminous and bituminous coals. The principal variation of pyrolysis behavior with rank is due to variations in the concentrations of functional groups and hence, the amount of each pyrolysis product. If the insensitivity of coal pyrolysis kinetics to coal rank can be generally demonstrated, it represents an important simplifying assumption in any general theory of coal pyrolysis. But the rank insensitivity of rate constants is controversial. There are two major questions. What species exhibit rank insensitive kinetics? Quantitatively, what does insensitivity mean, variations less than factors of two, ten, hundred, etc.? This paper considers whether pyrolysis data in the literature support the hypothesis of rank insensitive kinetic rate constants. The experiments considered vary in duration from 1.4 msec to 12 hr and in temperature from 350°C to 1800°C. Considering the available data, it appears that the decomposition of aliphatic, methyl and aromatic functional groups and the evolution of tar and hydrocarbon species have rates which are relatively insensitive to rank variation. The rate varies by at most a factor of five between lignite and bituminous coals. Oxygen species are somewhat more rank sensitive. The factor of five variation in rate due to coal rank is substantially less than the factors of 100–10,000 in variation typical of reported rates. Rank variation appears therefore to be a minor cause for these differences which consequently must be attributed to the effects of heat and mass transfer and to the assumptions used in deriving a kinetic rate. The observation that pyrolysis rates are insensitive to rank over such a wide range of conditions suggests that using this approximation in a pyrolysis theory can have wide applicability.     

Upgrading of flash pyrolysis oil and utilization in refineries

Flash pyrolysis oil from an ENSYN RTP pilot plant was upgraded in a continuous bench scale unit with commercial CoMo and NiMo catalysts in anticipation of scaling up the process. Large amounts of product were produced in a pilot plant for use in an extended analytical characterisation programme.

In bench-scale experiments, high deoxygenation rates of 88–99.9% were achieved. Low liquid and high water yields were obtained. The fractionated products of the production run did not fulfil the requirements for direct use as gasoline and diesel.

The process is restricted by several operational problems such as rapid catalyst deactivation, coking and plugging. Due to high feedstock and hydrogen addition costs, pyrolysis upgraded oil by the process tested is significantly more expensive than petroleum-derived oil at present oil prices.     

Static model of coal pyrolysis in a circulating fluidised-bed reactor

Four different coals were investigated: two sub-bituminous, one bituminous and lignite, which were processed in the temperature range 750–950 °C. The heat for pyrolysis was generated by partial gasification of the char produced. Air was used as the gasifying medium with amounts of 0.6–1.5 m³/kg of coal, depending on the required gasification-temperature. Two sequential phenomena were taken into account: char gasification and coal devolatilisation in respect of temperature. The experimental data on carbon dioxide and monoxide concentrations in a LCV gas produced were used for the correlation of Boudouard's equilibrium and the data on carbon burn-off and final volatile matter content in char were used for the solid-products yield. The equations for the quasi-equilibrium state were developed and calculated values were compared with the measurements. The model takes into account the equations developed and the total energy-balance assuming the heat losses of the experimental system. The investigated coal throughput amounted to 200–300 kg/h depending on the coal properties. Process characteristics were discussed, namely: the effect of air/coal ratio on the pyrolysis temperature; char and gas yield, volatile matter and ash content in a char; as well as the gas calorific value.     

Experiments and modelling of coal pyrolysis under fluidized bed conditions

INTRODUCTIONPyrolysisistheinitialandimportantstepinmostcoalconversionprocess3whichismainlyinfluencedbytemperature,pressure,heatingrate,coalparticlesize,coalrankandreactionenvironment.IthasbeenstudiedwithavarietyofexperimentalmethodsfSimpleweightlossm...     

煤气化过程中焦油裂解的试验研究

煤在热解和气化过程中产生的焦油,影响系统的正常运行。焦油脱除方法可分为气化炉内(初次脱除)和气化炉外(二次脱除)两类。尽管二次脱除法非常有效,但由于气化炉内初次脱除可以大大减少出口煤气中焦油含量,减轻甚至消除后期处理焦油的压力,故气化炉内脱除法得到重视。采用石灰石为催化剂,在1MW热态试验台上进行了试验,研究焦油和煤气成分在空气气化时添加不同石灰石含量工况下的变化情况,结果表明,石灰石的加入降低了焦油产率,提高了煤气产率,改善了煤气质量。     

Integrated energy systems based on cascade utilization of energy

Focusing on the traditional principle of physical energy utilization, new integration concepts for combined cooling, heating and power (CCHP) system were identified, and corresponding systems were investigated. Furthermore, the principle of cascade utilization of both chemical and physical energy in energy systems with the integration of chemical processes and thermal cycles was introduced, along with a general equation describing the interrelationship among energy levels of substance, Gibbs free energy of chemical reaction and physical energy. On the basis of this principle, a polygeneration system for power and liquid fuel (methanol) production has been presented and investigated. This system innovatively integrates a fresh gas preparation subsystem without composition adjustment process (NA) and a methanol synthesis subsystem with partial-recycle scheme (PR). Meanwhile, a multi-functional energy system (MES) that consumes coal and natural gas as fuels simultaneously, and co-generates methanol and power, has been presented. In the MES, coal and natural gas are utilized synthetically based on the method of dual-fuel reforming, which integrates methane/steam reforming and coal combustion. Compared with conventional energy systems that do not consider cascade utilization of chemical energy, both of these systems provide superior performance, whose energy saving ratio can be as high as 10%–15%. With special attention paid to chemical energy utilization, the integration features of these two systems have been revealed, and the important role that the principle of cascade utilization of both chemical and physical energy plays in system integration has been identified.     

热处理炉改造与能源梯级利用研究

我国金属热处理行业设备相对落后,存在能源不能高效利用的问题,因此通过改造设备、应用新技术来达到节能目的有着广阔的发展空间。在此背景下提出了一套天然气热处理炉系统改造方案,并通过计算、比较改造前后系统热耗、气耗、热效率,表明新方案在节能方面的优越性,并定性地分析在火用效率方面该方案具有更明显的优势。     

Problems of coal utilization in Romanian thermopower plants

In this paper, we present the most important problems regarding coal utilization in Romanian thermopower plants (TPPs). Reflected are the economic and technical difficulties of coal utilization as fuel. Consideration of this fuel is from the perspective of Romania. Presented are the results of Romanian researches for resolving the necessary problems regarding ecological standards and obtaining good efficiency in TPPs functioning with coal. Proposals are made for application of such researches.