钙元素对褐煤热解和气化特性的影响

综述了钙元素对褐煤热解和气化特性的影响,讨论了钙元素对热解产物中挥发分、焦油产率和气体产物分布的影响,以及对褐煤半焦气化的催化作用。结果表明,与酸洗煤相比,热解过程中,钙元素降低焦油产率,提高半焦产率;气化过程中,钙元素的植入提高褐煤半焦的反应活性,缩短了反应时间。高温时钙元素主要以氧化态的形式存在,低温时则不断与半焦基体键合而参与交联反应,少部分挥发。     

简析铁元素如何影响褐煤热解及气化特性

本文重点对铁元素影响褐煤热解与气化的主要方面进行详细论述,以及在褐煤中添加铁元素能够对褐煤的热解与气化所产生的半焦产物和气体产物的影响;并将褐煤中植入铁元素与褐煤中植入其他金属元素所产生的影响进行对比。最后论述铁元素对褐煤半焦转化率的影响。     

昭通褐煤半焦气化特性的研究

以O2/水蒸气作为气化剂,对褐煤半焦气化过程进行实验研究.结果表明,随着气化温度的提高,在生成的煤气组成中CO和H2含量增加,而CO2和CH4的含量减少,煤气热值和合成气产率均增加;在温度一定时,随着氧气流量的增加,煤气中CO含量和H2含量先增加然后逐渐减少,CO2含量增加,CH4含量减少,煤气热值和合成气产率均存在一个最大值.     

铁元素对褐煤热解及气化特性的影响

综述了铁元素对褐煤热解及气化的影响方面的研究进展,在褐煤中植入铁元素对褐煤热解和气化的半焦产物、气体产物的影响,分析了铁在褐煤热解和气化过程中的迁移和转化,并与褐煤中植入的其他金属元素产生的影响进行了简单对比。     

大尺度褐煤的地下气化热解特性

为了考察地下气化过程中干馏和干燥作用对于气体产物组成的影响,以乌兰察布原煤为研究对象,采用大直径固定床反应装置进行了150℃～800℃范围内热解气体的形成与释放研究.结果表明,大粒径褐煤热解在400℃才开始有气体逸出,随着温度的升高气体总产率升高,平均孔径和孔容积呈现先增大后减小的趋势;不同粒度的块状煤有效气体析出规律大致相同,但5cm见方的褐煤呈现气体析出缓慢、产量较大的趋势;在慢速升温和中速升温过程中,5℃/min的升温速率可以明显增加大粒度褐煤热解失重率,提高气体产率.     

生物质快速热解制油试验及流程模拟

使用自主研发的流化床热解反应器对生物质热解制油进行实验研究,通过对不同实验温度450、500、525、550、580、610℃下得到的目标产物进行分析,得到了反应温度对生物油产率的影响规律。实验表明：550℃时,最大液体产率为42.5%（质量）;实验得到的不可冷凝气体的组分以CO、CO₂、CH₄和H₂为主,气相产物产率约为37.7%（质量）。在实验基础上,利用Aspen Plus流程模拟软件,建立了生物质热解制油工艺模拟流程,模拟分析了热解温度对生物油产率的影响,结果表明该模型能准确模拟实际热解过程,具有较好的适用性和可靠性。     

褐煤经四氢化萘处理后的结构及热解-气化特性分析

在小型反应釜上采用非极性有机溶剂四氢化萘(tetrahydronaphthalene, THN)对内蒙古锡林郭勒褐煤进行脱水,获取了不同温度下的脱水试样,运用傅里叶红外光谱(Fourier transform infrared spectroscopy,FT-IR)分析技术对比研究了在不同脱水温度下煤样中有机官能团的变化,通过FT-IR谱图的分峰拟合计算,对脱水煤样的化学结构变化特征进行半定量分析,并结合热重(thermal gravity analysis/differential thermal gravity,TG/DTG)和实验室固定床反应器(fixed bed reactor)考察了不同脱水温度下煤样的热解气化特性和热解气相产物分布规律,并对脱水煤样在最大失重速率区间的动力学参数进行了计算。试验结果显示:四氢化萘溶剂对褐煤的脱水提质是有效的,150~200℃时C O开始分解,而此时芳香环上的C C仍然相对稳定。随着脱水温度的升高,芳香类氢含量先减小后增大,脂肪类氢含量先增大后减小,芳香度和芳香碳在脱水温度范围内逐渐增大。煤样的脱水温度升高,热解气相产物H₂、CH₄、CO累积产率增大,CO₂累积产率减小;脱水煤样热解活化能随着脱水温度的升高而升高,进而导致脱水温度较高煤样热解失重率降低。     

高密度聚乙烯热解-CO2气化制备清洁能源的研究

以高密度聚乙烯(HDPE)塑料为原料,通过高温热解-CO_2气化法成功制备了清洁燃料合成气CO及H_2。使用热重分析法对HDPE的热解及气化过程进行分析,结果发现材料的失重过程主要分为2个阶段:在450℃左右,HDPE的长链开始发生裂解为低分子碳链,部分低分子碳链进一步裂解为小分子量挥发气体,此阶段材料的失重率达到80%;当温度达到900℃时,热解后剩余的焦样开始在CO_2气氛下气化。另外,红外光谱测试显示气化过程中生成的CO量明显低于热解过程。为研究温度对材料失重率的影响,改变热解温度(400～550℃)和气化温度(900～1 100℃),发现随着温度的升高,热解过程及气化过程原料的失重率均相应上升,主要是因为CO_2气氛下的热解过程及气化过程均为吸热反应,而温度的升高将推动反应正向进行。     

CO2＋O2气化制气配水煤气生产甲醇的构想与可行性分析

以干燥后的焦炭为原料，O2和CO2为气化剂，在气化炉内进行气化反应并制得粗CO气。主要反应如下：C＋O2=CO2＋394．4kJ／mol（1）、C＋CO2=2CO—168．5kJ／mol（2）、C＋1／2O2=CO＋112．9kJ／mol（3）。反应主要按（1）、（2）式进行，反应（1）、（3）为氧化反应，是强放热过程，反应（2）为还原反应，是吸热过程。CO2除参与反应外，还起调节温度作用，控制燃烧层最高温度低于灰熔点（t2），防止灰渣结块。     

不同CO2捕集技术的CO2耦合绿氢制甲醇工艺研究

大量的化石燃料燃烧导致温室气体排放增加,全球气候变暖。世界各国以全球协约的方式减排CO₂,我国也由此提出“碳达峰·碳中和”目标。CO₂捕集以及转化制液体燃料和化学品是双碳目标下行之有效的碳减排措施之一,不仅可以实现CO₂的资源化利用,同时也缓解了国家能源安全问题。本文以燃煤电厂烟气CO₂捕集和CO₂合成甲醇为研究对象,分析了基于四种不同CO₂捕集技术的CO₂耦合绿氢制甲醇工艺。对四种不同CO₂捕集技术的CO₂制甲醇工艺进行了严格的稳态建模和模拟,分析和比较了不同CO₂捕集技术情景下的CO₂制甲醇工艺的技术和经济性能。结果表明,MEA、PCS、DMC和GMS情景的单位甲醇能耗分别是7.81、5.48、5.91和4.66 GJ/ t CH₃OH,GMS情景的单位能耗最低,其次是PCS情景,但随着更高效相变吸收剂的开发,PCS情景的单位甲醇产品的能耗将降低至2.29~2.58 GJ/t CH₃OH。四种情景的总生产成本分别是4314、4204、4279和4367 CNY/ t CH₃OH,PCS情景的成本最低,更具有经济优势。综合分析表明PCS情景的性能表现最好,为可用于燃煤电厂最佳的碳捕集技术,为CO₂高效合成燃料化学品提供方向,缓解化石燃料短缺和环境污染问题。     

焦炉煤气制甲醇合成系统补碳的研究

介绍了焦炉煤气制甲醇的工艺原理。以唐山中润煤化工有限公司为例,分析了甲醇合成工艺中普遍存在的合成气中CO2含量不足的原因及后果。为解决这一问题,提出通过外购液态CO2,并通过CO2气化装置将其气化对甲醇合成工艺进行补碳的措施。从7个方面介绍了再补碳过程中的注意事项。通过这一措施,可以显著提高甲醇产量和甲醇合成系统补碳的经济效益。     

CO2 gasification of wood charcoals derived from vacuum and atmospheric pyrolysis

The gasification of biomass derived char obtained via vacuum and atmospheric pyrolysis of Populus tremuloides has been studied in the ranges of 725–960°C and 0.1 to 6 MPa. CO₂ was used as the oxidizing gas. The results show that char reactivity is influenced by the preheating rates and that pressure effects are significant between 850°C and 950°C. A correlation based on the expression: df/dt = k₀{exp(-E/RT)}(1 - f)^af^βP^yCO₂ was used to fit the experimental data. In general, vacuum pyrolysis derived char showed a higher reactivity than atmospheric pyrolysis chars. An explanation based on a higher oxygen content of the vacuum pyrolysis char is suggested.     

基于能量集成的CO2减排量的确定

能源活动引起的排放占CO2排放量的绝大多数。因此,对企业的能量系统进行集成,不仅可以提高能源的利用效率,也可以减少CO2的排放。本文给出了由于节能所引起的CO2减排量的计算方法,并以某石化公司对苯二甲酸装置的能量集成项目为工程实例,计算出能量集成形成的CO2减排量。计算结果表明能量集成对CO2减排有显著的作用。     

Study on CO2 gasification reactivity of chars obtained from Soma-Isıklar lignite (Turkey) at various coking temperatures

A kinetic study on the gasification of char with CO₂ is presented in this paper. The chars from different coking temperatures show a different reactivity, which can be mostly attributed to kinetic parameters (E_A, k_m, η) and the specific surface area values. The kinetic analysis results with CO₂ gasification of chars from the Soma-Isıklar lignite present that CO₂ gasification rates for chars are controlled by chemical reaction at experimental gasification temperature range. Therefore, the specific surface area and kinetic parameters of prepared chars from Soma-Isıklar lignite should be considered as a very important factor for the gasification reactivity and rates.     

Effect of lignite pyrolysis conditions on calcium oxide dispersion and subsequent char reactivity

A demineralized North Dakota lignite was loaded with 2.9 wt% Ca by ion exchange. Chars were prepared by pyrolysis in N₂ at 1275 K and residence times between 0.3 s and 1 h. Major differences were observed in their subsequent reactivities in 0.1 MPa air. X-ray diffraction analysis was carried out to obtain information on the state and dispersion of the Ca species on the various chars. The results clearly indicate that CaO is the predominant species responsible for catalysis of lignite char gasification. It is concluded that pyrolysis residence time also has a profound effect on CaO dispersion. Thus, a correlation was established between a fundamental physical property (catalyst dispersion) and the observed gasification behaviour of lignite chars prepared under different pyrolysis conditions.     

Pyrolysis and hydropyrolysis of Louisiana lignite

Pyrolysis and hydropyrolysis kinetics of five samples of Louisiana lignite have been studied in an atmospheric pressure TG system as a function of heating rate and atmosphere. Final pyrolysis temperature was always 800 °C. The total volatile yield (dry basis) was 33.5–43.8wt%. For all lignites the volatile yield in hydrogen was greater than that obtained in nitrogen at similar conditions. However, variation in heating rate produced an opposite result in the two atmospheres with volatile yield increasing with heating rate in nitrogen but decreasing in hydrogen. Results have been analysed using the distributed activation energy pyrolysis model and parameters compared to similar studies using North Dakota and Montana lignites.     

褐煤及其热解产品利用现状

为了提高褐煤利用率,介绍了国内褐煤资源的储量形态、分布。分析了目前褐煤的利用途径,包括共伴生资源的利用、直接燃烧、干燥脱水与成型、气化、液化、制水煤浆与热解。并进一步分析了褐煤热解气、液、固产品的利用方向。提出了褐煤半焦利用的新方法,即利用半焦干法气化,或将半焦和热解废水等制成水煤浆,通过湿法气化制得合成气,再通过甲烷化催化剂将合成气制成甲烷,或将合成气通过费托合成制成汽油柴油。     

Strategies for CO2 capture from different CO2 emission sources by vacuum swing adsorption technology☆

Different VSA(Vacuum Swing Adsorption) cycles and process schemes have been evaluated to find suitable process configurations for effectively separating CO2 from flue gases from different industrial sectors. The cycles were studied using an adsorption simulator developed in our research group, which has been successfully used to predict experimental results over several years. Commercial zeolite APGIII and granular activated carbon were used as the adsorbents. Three-bed VSA cycles with- and without-product purge and 2-stage VSA systems have been investigated. It was found that for a feed gas containing 15% CO2(representing flue gas from power plants), high CO2 purities and recoveries could be obtained using a three-bed zeolite APGIII VSA unit for one stage capture, but with more stringent conditions such as deeper vacuum pressures of 1–3 k Pa. 2-stage VSA process operated in series allowed us to use simple process steps and operate at more realistic vacuum pressures. With a vacuum pressure of 10 k Pa, final CO2 purity of 95.3% with a recovery of 98.2% were obtained at specific power consumption of 0.55 MJ·(kg CO2)-1from feed gas containing15% CO2. These numbers compare very well with those obtained from a single stage process operating at1 k Pa vacuum pressure. The feed CO2 concentration was very influential in determining the desorption pressure necessary to achieve high separation efficiency. For feed gases containing N 30% CO2, a singlestage VSA capture process operating at moderate vacuum pressure and without a product purge, can achieve very high product purities and recoveries.     

德士古煤气化工艺CO2排放分析

煤化工是高耗能高CO₂排放的工业,利用热力学分析方法对其工艺过程中能量利用情况进行分析,可以有效地发现工艺的能量利用缺陷和节能潜力,为过程的节能优化改造提供依据.目前热力学分析方法主要包括能量衡算法和(火用)分析法,本文在对传统热力学方法进行分析和评价的基础上,指出了已有方法的不足,提出了新的熵(火用)分析相结合的分析方法,并以德士古煤气化工艺为例,分别使用传统的能量衡算法、(火用)分析法和本文提出的熵(火用)结合分析法对工艺过程的能量利用情况进行了分析,获得了工艺过程中内各模块的能量、熵增和(火用)损分布.在此基础上,将(火用)损与工艺过程中CO₂排放量建立联系,经过计算得到了工艺过程中各个设备对应的CO₂排放分布和(火用)损系数,得出气化炉是工艺过程中主要的节能位置.这种能量与CO₂排放的关联能为工艺过程的节能减排提供理论依据.