基于炉排炉的气化燃烧技术实验研究

为了更深入地研究生活垃圾气化工艺技术,本文基于我司逆推式生活垃圾机械炉排炉,发展了新型的垃圾气化燃烧技术,设计了新型的两段式垃圾气化炉,对生活垃圾气化燃烧过程进行了试验研究。研究结果表明:低位热值相对较高的生活垃圾可以实现长时间持续稳定的气化燃烧;可燃性合成气体的比例一直处于波动状态;实现了SO_2和NO_X的达标排放,并实现了CO的零排放,充分验证气化燃烧工艺的低排放的环保优势;一定的上料速度下,气化炉炉膛出口烟气温度越高,合成气燃烧热越低,实验时需要控制炉膛出口烟气温度这一重要指标。作为新一代垃圾处理技术,气化燃烧技术在环保方面更具优势,但为了维持整个系统的平衡及安全稳定运行,需要较高的垃圾热值。     

不同气化剂下海藻粉在气流床下气化特性试验研究

为考察O2/水蒸气和O2/CO2作为气化剂对海藻粉气化特性的影响,在自制的小型生物质气流床气化炉上开展海藻粉在气流床下气化特性试验研究。当氧气/生物质比（O/B）为0.3、气化温度为1200℃时,不同水蒸气/生物质比（S/B=0～1.2）对合成气组成有较大影响,其中H2产量的上升趋势最为明显,S/B=1.2时比单纯氧气气化提高了81.4%。而在O2/CO2气化条件下,由生物质产生的CO2随二氧化碳/生物质比（CO2/B）的增加而下降,当CO2/B=0.9时,H2、CO的产量分别比单纯氧气气化提高了33.9%和75.8%,热值由5521 kJ/m3上升至8576 kJ/m3。结果表明,如果以提高热值为制取合成气的目标时,添加CO2在一定范围内可以达到水蒸气的效果,同时降低了系统能耗及简化了气化设备。     

CO_2生物质气化的数值模拟研究

基于计算颗粒流体力学探究三维鼓泡流化床气化炉中CO_2部分或完全替代水蒸气作为气化剂、CO_2与生物质的比例及其在气化剂中的比例以及CO_2代替惰性气体作为播料风对生物质气化特性的影响。结果表明:用CO_2替代水蒸气不能有效改善气化特性,替代比例从0%增长到100%,气化效率随之降低,碳转化率略微增加,合成气低位热值也从0%CO_2的3.94 MJ/m3降低到100%CO_2的3.54 MJ/m3;在CO_2混合空气气化时,为保证合成气低位热值以及气化效率,CO_2在气化剂中应占比60%以上,且CO_2与生物质的比例不宜超过0.6;CO_2作流化风或播料风有益于生物质气化,播料风换成CO_2后低位热值、气化效率以及碳转化率分别增加0.25%、0.58%、0.18%。CO_2作气化剂对CO_2的循环利用和净排放具有积极影响,同时也为生物质气化与CO_2捕集相结合提供一种有益方法,有助于生物质气化炉的设计和运行。     

城市垃圾气化试验研究初探

介绍了在试验室里采用自行研制的液态化气化炉，进行城市固体生活垃圾高温气化的初步试验。试验结果表明：经过处理的有机垃圾是很好的热解和气化原料。产生的气体热值为6500－7500kJ/m^3；可以用作发电、烧锅炉或者生活用气。垃圾气化比生物质量更容易，而且炉渣比较松散。     

生物质混流式固定床气化炉运行特性分析

以桉木为原料,对1.5 t/h生物质混流式固定床气化炉运行特性进行了测试分析与评价,与文献报导报道的相关炉型包括上吸式、下吸式、两段式等炉型运行结果进行了比较。实验以气化炉空气通入量作为主要控制变量,对有或无水蒸气条件下的气化炉温度及压力分布、燃气组成、焦油与飞灰含量、气体产率等参数进行了较长周期的测试,结果表明：气化炉运行效果符合设计要求,各项指标相当于或优于传统的下吸式气化炉;气化炉运行温度与压力比较稳定;以冷燃气计算的燃气热值一般约为4 900 ~ 5 500 kJ/Nm3;气化效率约为70% ~ 78%;燃气焦油含量约600 ~ 3 500 mg/Nm3,运行负荷在50%以上时,焦油含量一般低于1 500 mg/Nm3。研究结果有望为混流式气化炉的改进和操作提供优化建议,同时可为其他气化工艺设计提供参考依据。     

氧煤比对气流床煤气化过程的影响

为研究氧煤比对气流床煤气化炉气化过程的影响,对某厂运行的Texaco气化炉进行了数值模拟研究。利用所建立的数学模型,分析了Texaco气化炉内的气化过程,以及氧煤比对炉内温度、气相成分及炉膛出口合成气成分的影响规律。结果表明:Texaco气化炉内下行火焰的长度约占气化炉高度的1/3,炉膛上部火焰高度区域内气相温度及主要成分浓度的变化梯度最大,而在炉膛下部气相成分及温度的变化均不明显;随着氧煤比的增大(0.95~1.10),气化炉出口合成气有效成分(H2+CO)浓度逐渐降低,CO2和H2O的浓度及气化炉内气相温度逐渐升高;在保证顺利排渣和合适的出口合成气成分的条件下,存在一个最佳氧煤比。     

合成气中CO_2含量与水煤浆气化温度关系研究

为了研究合成气中CO_2含量与气化炉温度的关系,将气化炉分为3个区域:水分蒸发及挥发分热解区、燃烧区及气化区。水煤浆和氧气相继经过这3个区域发生一系列物理、化学反应最终生成合成气。建立计算模型,得到整个气化过程反应放热Q与合成气中CO_2的关系。结论表明:合成气中CO_2含量越多,气化炉温度越高;增大氧煤比,可使气化炉温度升高;较粗的煤粉,可使气化炉温度高。因此合成气CO_2含量可作为判断炉温的依据,氧煤比和煤粉细度可以作为调节炉温的手段。     

气化焚烧技术

原理:垃圾气化采用正常焚烧所需要风量的1/5~1/3,使垃圾在高温缺氧状态下生成CO,H2,CH4等可燃气体,而后燃烧利用。根据不同的反应条件、生成物、气化炉结构形式等,气化工艺有不同分类方法。根据反应气氛可分为水蒸气气化、氧气气化和空气气化;根据气化炉结构可分为回转窑气化、流化床气化和固定床气化;按灰渣状态可分为气化焚烧和气化熔融。     

两级下吸式生物质气化炉气化性能的研究

在自行设计的两级下吸式生物质气化炉中,研究了空气当量比(ER)对气体组成、气体热值、气化效率以及焦油含量的影响。试验结果表明,该新型两级气化炉能够产生焦油含量较低的燃气;在空气预热的条件下,焦油含量更低,可达238 mg/m3。该新型两级气化炉的最佳ER为0.33~0.35,当ER=0.34时,气化气低位热值(LHV)最高为4 409 kJ/m3,气化效率为63.7%,焦油含量低于300 mg/m3。     

生物质化学链气化联合燃气轮机发电系统模拟

使用Aspen Plus软件对以Fe_2O_3为载氧体的生物质化学链气化系统进行模拟,分析温度、压力、载氧体与生物质摩尔比、水蒸气与生物质摩尔比等因素对合成气制备的影响;对不同生物质的气化条件进行优化;将气化制得的合成气通入M701F燃气轮机中发电,考察系统的发电效率。结果表明:常压下,不同生物质气化的优化温度均在740℃左右,此时制备的合成气冷煤气效率较高;提高反应压力有利于系统热量自平衡,但合成气的冷煤气效率降低;载氧体与生物质摩尔比的优化值与生物质中氧碳摩尔比呈负相关,且达到优化值时,气化环境中氧碳摩尔比在1.25左右;水蒸气通入气化系统后冷煤气效率可提高15.00%～20.00%,主要原因为H_2的产量显著增加,通入水蒸气后的气化环境的氧碳比在1.4左右时,制备合成气的冷煤气效率较高;系统的发电效率在30.00%～37.00%,高于生物质发电效率。     

50t炼钢电弧炉烟气佘热回收系统的设计应用

以电弧炉炼钢过程烟气余热的回收利用及烟气净化除尘为主线,以热管蒸发器为换热元件,合理控制烟气流速,解决高温烟尘的沉降和蒸发器热管灰堵以及烟气温度波动大的难题,完成了50t电弧炉烟气余热回收净化系统设计与施工.对电弧炉炼钢过程中所产生的高温烟气直接进行余热回收,满足电弧炉炼钢流程VD真空处理对蒸汽的需求,实现了高温烟气余热回收利用和环境净化,为国内电弧炉节能降耗和清洁生产进行了有益的探索.     

Effects of fuel compositions on the heat generation and emission of syngas/producer gas laminar diffusion flame

Demand for the clean and sustainable energy encourages the research and development in the efficient production and utilisation of syngas for low-carbon power and heating/cooling applications. However, diversity in the chemical composition of syngas, resulting due to its flexible production process and feedstock, often poses a significant challenge for the design and operation of an effective combustion system. To address this, the research presented in this paper is particularly focused on an in-depth understanding of the heat generation and emission formation of syngas/producer gas flames with an effect of the fuel compositions. The heat generated by flame not only depends on the flame temperature but also on the chemistry heat release of fuel and flame dimension. The study reports that the syngas/producer gas with a low H_2:CO maximises the heat generation, nevertheless the higher emission rate of CO₂ is inevitable. The generated heat flux at H_2:CO = 3:1, 1:1, and 1:3 is found to be 222, 432 and 538 W m^-2 respectively. At the same amount of heat generated, H₂ concentration in fuel dominates the emission of NO_x. The addition of CH₄ into the syngas/producer gas with H_2:CO = 1:1 also increases the heat generation significantly (e.g. 614 W m^-2 at 20%) while decreases the emission formation. In contrast, adding 20% CO₂ and N₂ to the syngas/producer gas composition reduces the heat generation from 432 W m^-2 to 364 and 290 W m^-2, respectively. The role of CO₂ on this aspect, which is weaker than N₂, thus suggests CO₂ is preferable than N₂. Along with the study, the significant role of CO₂ on the radiation of heat and the reduction of emission are examined.     

炼厂加热炉烟气与工艺废气达标排放分析探讨

烟气氮氧化物和二氧化硫的排放控制已成为炼油企业关注的重点。对加热炉烟气、催化裂化装置、硫磺回收装置和废酸再生装置的工艺废气的排放控制进行探讨,从操作优化与技术改造两方面提出应对措施。对氮氧化物排放不合格的燃气加热炉,采用低氮燃烧器进行改造,以满足特别限值排放地区NOx排放限值100mg/m3的标准;导致惠州炼化燃料气硫含量偏高的主要因素是催化/焦化干气硫含量偏高、气柜回收瓦斯未脱硫。通过提高干气脱硫能力、对火炬系统气柜回收瓦斯脱硫后再补入燃料气系统,可满足加热炉烟气二氧化硫排放标准。催化裂化装置通过加入脱硝助剂,催化烟气中NOx由640mg/m3降至85mg/m3左右,满足特别排放限值地区NOx排放标准。增上催化烟气湿法脱硫除尘措施,可满足催化烟气SO2排放标准。硫磺回收装置通过液硫脱气改造,并采用高效复配脱硫剂,可满足尾气SO2排放标准。废酸再生装置通过操作优化与增加尾气洗涤系统,其烟气可满足国家最新排放标准。     

石墨烯-PFA复合材料换热器与金属换热器的传热性能对比

氟塑料换热器以其耐腐蚀、耐磨损等优点而备受关注,但氟塑料热导率较低,换热能力差,限制了其广泛应用。石墨烯-PFA复合材料兼具石墨烯优异的导热性和可熔性聚四氟乙烯(PFA)良好的耐酸碱腐蚀性,是新一代的换热器材料。搭建了余热回收测试实验台,对石墨烯-PFA复合材料换热器和金属换热器的传热性能进行对比。研究了不同烟气流速、不同进口烟气温度以及不同石墨烯配比对复合材料传热性能的影响。结果表明:对于金属换热器和复合材料换热器,当烟气流速从2.0增加到4.0 m/s时,传热系数分别增加到原来的1.19和1.34倍;随着进口烟温的升高,两种材质的传热系数分别降低了15.6%和14.7%;随着石墨烯含量增加,复合材料的导热系数以及传热系数均增加。     

径向热管换热器在天然气工业炉低温烟气中的应用

当前我国的能源形势紧张,能源利用状况令人担忧.在一些高耗能的企业,工业生产中排放的中低温烟气余热由于回收难度高、回收成本大等问题,一直得不到合理的利用,如何合理回收成为亟待解决的难题之一.简要介绍了一种新型余热利用换热设备——径向热管换热器,提出了计算热管换热器经济性评价指标的方法,并以某工厂低温烟气余热回收工程为实例,对烟气余热的回收利用进行了技术和经济效益分析.实践应用证明,径向热管换热器在工业低温烟气余热回收中有很好的实用性和可行性.     

火电厂低低温烟气处理系统烟气余热利用研究

低低温烟气处理系统与传统的除尘、脱硫工艺相比,具有良好的节能环保性能。从热力学性能和经济效益两方面分析比较了低低温高效烟气处理系统中两种烟气余热利用的方案,并以国产600 MW空冷机组为例,进行了定量分析比较。定量计算结果得出的结论对低低温烟气处理系统在中国火电厂推广使用具有一定的指导意义。     

Developing gasification process of polyethylene waste by utilization of response surface methodology as a machine learning technique and multi-objective optimizer approach

This study set out to evaluate the performance of response surface methodology as a machine learning technique on gasification process of polyethylene waste. Different models were developed for predicting gas yield, cold gas efficiency, carbon dioxide emission and lower heating value of syngas in gasification of polyethylene waste using response surface methodology. The accuracy and validity of these models were checked in comparison with the results obtained from the validated model. Most studies in the field of response surface methodology have only focused on its application for multi-objective optimization and largely have ignored its utilization as a machine learning technique. Central composite design was utilized to develop a model between the variables and the responses. Pressure and temperature of the gasifier, moisture content of polyethylene and equivalence ratio were the variables and the responses were gas yield, cold gas efficiency, carbon dioxide emission and lower heating value of syngas. The findings revealed that root mean square errors of the models developed by response surface methodology were 0.235, 0.438, 0.294 and 1.999 indicating their high validity. Finally, multi-objective optimization of polyethylene waste gasification was carried out using response surface methodology resulting in gas yield of 96.29 g/mol, cold gas efficiency of 76.22%, carbon dioxide emission of 4.66 g/mol and lower heating value of 493.44 kJ/mol. The optimum responses were predicted by response surface methodology with errors smaller than 5%.     

EDV湿法烟气脱硫装置的优化措施

辽河石化0.8Mt/a重油催化裂化装置采用EDV湿法烟气洗涤脱硫技术,可以有效脱除装置排放的烟气中的SO2、催化剂颗粒等污染物。应用该技术,可将SO2含量从313.1mg/m3(标准)降到31.1mg/m3(标准),脱除率达到90.37%;催化剂固体颗粒从363.1mg/m3(标准)降到30.6mg/m3(标准),脱除率达到91.58%,均优于国家排放标准。为解决装置运行中存在的耗电量高、新鲜水用量大和装置排水中TSS含量高等问题,分别采取洗涤塔吸收区喷管分层可选洗涤功能、降低入塔烟气温度,以及废液处理单元选用絮凝剂-助凝剂组合加注方式,代替絮凝剂单一加注等优化措施。优化后,装置排放烟气中SO2、固体颗粒等污染物含量仍优于国家排放标准,装置每小时节电176kW·h,新鲜水用量从15t/h减少到12t/h,排水中TSS含量从101mg/L降到43mg/L。     

Numerical analysis of the tubular heat exchanger designed for co-generating units on the basis of microturbines

The application of numerical simulations using the computational fluid dynamics (CFD) analysis when mapping processes in the course of which the heat transmission occurs has become an essential part of the heat transfer systems. The present contribution deals with the possibility to use the waste heat of the flue gas produced by small microturbines. The waste heat is mapped by means of both the numerical simulations applying the FLUENT software and the practical experiment. Utilizing a part of the waste heat for water heating and decreasing the outlet temperature of the flue gas into atmosphere when applying in co-generating units represents one of the partial benefits. The present paper brings information concerning the newly designed type of heat exchanger including the results of its numerical analysis.The analysed heat exchanger designed in the system with microturbine (MT) C30 reached generally the efficiency of 75%. Both the results of simulations and the carried out practical experiment confirmed the temperature of the flue gas to be sufficient behind the exchanger to prevent the condensation of water from the flue gas. On the contrary, except for heating water the exchanger under consideration offers – thanks to its design – also other possibilities to use of the flue gas. The practical experiment confirmed the results of the CFD prediction with rather small differences as the temperature of water obtained from the exchanger was 359 K and the designed shape of the exchanger did not result in substantial pressure losses in flue gas approximately 50 Pa. The mean logarithmic temperature difference of the mapped and verified exchanger was ～203 K.     

Fuel saving, carbon dioxide emission avoidance, and syngas production by tri-reforming of flue gases from coal- and gas-fired power stations, and by the carbothermic reduction of iron oxide

Flue gases from coal, gas, or oil-fired power stations, as well as from several heavy industries, such as the production of iron, lime and cement, are major anthropogenic sources of global CO₂ emissions. The newly proposed process for syngas production based on the tri-reforming of such flue gases with natural gas could be an important route for CO₂ emission avoidance. In addition, by combining the carbothermic reduction of iron oxide with the partial oxidation of the carbon source, an overall thermoneutral process can be designed for the co-production of iron and syngas rich in CO. Water-gas shift (WGS) of CO to H₂ enables the production of useful syngas. The reaction process heat, or the conditions for thermoneutrality, are derived by thermochemical equilibrium calculations. The thermodynamic constraints are determined for the production of syngas suitable for methanol, hydrogen, or ammonia synthesis. The environmental and economic consequences are assessed for large-scale commercial production of these chemical commodities. Preliminary evaluations with natural gas, coke, or coal as carbon source indicate that such combined processes should be economically competitive, as well as promising significant fuel saving and CO₂ emission avoidance. The production of ammonia in the above processes seems particularly attractive, as it consumes the nitrogen in the flue gases.