流化床-气流床耦合反应器中煤气化特性

利用化工动力学软件CHEMKIN建立了流化床-气流床耦合反应器等效网络模型,在φ300 mm反应器中的煤气化实验结果基础上,充分考虑耦合反应器不同区域物料间两相流动、传质传热,对耦合反应器各部分流体力学特征以及耦合反应器中不同区域的化学反应进行了分析。利用模型对飞灰的碳转化率、耦合反应器的碳转化率、耦合反应器内温分布及物料停留时间进行计算,结果表明,流化床耦合气流床反应器后,气流床可将出口飞灰碳转化64.1%,实现了耦合反应器对飞灰的再气化;耦合反应器煤气化系统的碳转化率由单独流化床的84.9%提高到92.2%。     

灰熔聚流化床粉煤气化技术加压大型化研发新进展

灰熔聚流化床粉煤气化技术历经20余年的研发和工程化放大,低压气化技术已日趋成熟,并用于氮肥企业原料气改造和新建甲醇合成厂。该气化技术可使用不同灰含量和灰熔融性温度的煤,过程效率也较高,符合我国资源特点。为此在山西省发展和改革委员会的支持下,中科院山西煤化所和山西晋煤集团合作成立的“山西省粉煤气化工程研究中心”正在建设3.0MPa加压灰熔聚流化床粉煤气化中试平台,2006年年底已建成,预计于2007年3月进行加压气化试验,2007年完成加压灰熔聚流化床煤气化工业装置设计软件包的编制,形成具有我国自主知识产权、适应中国煤炭特点的大规模加压灰熔聚流化床粉煤气化技术。本文介绍了灰熔聚流化床粉煤气化过程,指出它的优点、缺点、适用范围、技术现状和发展方向,并对加压灰熔聚气化中试技术进行了简介。     

流化床燃烧/气化器内流动特性

以灰熔聚流化床粉煤气化工艺为背景,概括了射流床内床层动力学、射流特性以及密相中的气泡性质的研究进展。旨在为该工艺过程的工业化放大和实际操作提供必要的参考和有益的信息。     

Influence of ash agglomerating fluidized bed reactor scale‐up on coal gasification characteristics

To study the influence of fluidized‐bed reactor scale‐up on coal gasification characteristics, a model of the ash agglomerating fluidized‐bed reactor has been developed using an equivalent reactor network method. With the reactor network model, the scale‐up effects of a gasifier were studied in terms of the characteristics of the chemical reactions in the jet zone, the annulus dense‐phase zone and the freeboard zone. Results showed that the changes occurred in the inequality proportion of the volume of the jet zone during the reactor scale‐up. Taking into consideration the utilization of a portion of the backflow gas, the expansion of the jet zone volume and the coal particle residence time, the temperature of the jet zone was increased from 1592 to 1662 K. Also, both the annulus dense‐phase zone temperature and the freeboard zone temperature decreased, causing subsequent decrease in the carbon conversion efficiency. © 2014 American Institute of Chemical Engineers AIChE J, 60: 1821–1829, 2014     

串行流化床煤气化试验

针对串行流化床煤气化技术特点,以水蒸气为气化剂,在串行流化床试验装置上进行煤气化特性的试验研究,考察了气化反应器温度、蒸汽煤比对煤气组成、热值、冷煤气效率和碳转化率的影响。结果表明,燃烧反应器内燃烧烟气不会串混至气化反应器,该煤气化技术能够稳定连续地从气化反应器获得不含N₂的高品质合成气。随着气化反应器温度的升高、蒸汽煤比的增加,煤气热值和冷煤气效率均会提高,但对碳转化率影响有所不同。在试验阶段获得的最高煤气热值为6.9 MJ•m^-3,冷煤气效率为68％,碳转化率为92％。     

中国高灰、高硫、高灰熔融性温度煤的灰熔聚流化床气化

煤气化将会在未来中国可持续发展中占有相当重要的位置。对目前的煤气化技术和中国的煤种特性进行了描述和分析,介绍了中国科学院山西煤炭化学研究所灰熔聚流化床的研究与开发现状以及一些煤种的实验结果。结果表明:灰熔聚流化床煤气化技术适合中国高灰、高硫、高灰熔融性温度煤的气化。     

气流床煤气化炉壁面反应模型

建立了气流床煤气化炉煤灰渣颗粒沉积和壁面反应模型,相应完善了渣层流动、传热传质和相变模型,发展了数值模拟方法,并以国内某型两段式干煤粉加压气流床煤气化中试炉为对象进行了模拟。利用建立的模型可以得到壁面反应速率、渣层含碳量、固态渣层厚度、液态渣层厚度、渣层平均温度和液态渣层平均速度等。结果表明:氧煤比升高,渣层平均温度升高,固态渣层厚度、液态渣层厚度和气化炉出口灰渣含碳量降低。计算得到的灰渣含碳量在14%左右,整体碳转化率为95.2%左右,与实际值相近。通过模拟发现壁面反应对于所分析气化炉的碳转化率、排渣含碳量、壁面渣层流动和温度状态具有重要影响,进而影响气化炉的安全稳定运行。     

灰熔聚流化床粉煤气化技术0.6MPa工业炉运行概况

介绍了中科院山西煤炭化学研究所开发的灰熔聚流化床粉煤气化技术及其适用范围、工业应用情况。灰熔聚流化床粉煤气化技术具有气化温度适中、氧耗量较低、煤种适应性宽、产品气不含焦油、气化炉耐火材料要求低等优点。同时,对0.6 MPa工业装置的运行情况进行了介绍,总结了0.6 MPa工业装置运行结果,并指出当前需要改进和完善之处。     

Experiment and mathematical modeling of a bench-scale circulating fluidized bed gasifier

The gasification of two different coals and chars with CO₂ and CO₂/O₂ mixture in a 48-mm-i.d. circulating fluidized bed (CFB) gasifier is investigated. The effects of operation condition on gas composition, carbon conversion and gasification efficiency were studied. A simple CFB coal gasification district mathematical model has been set up. The effects of coal type and CFB operating conditions on CFB coal gasification are discussed based on the CFB gasification test and model simulation. The main operation parameters in CFB gasification system are coal type, gas superficial velocity, circulating rate of solids and reaction temperature. It is found that CO concentration and carbon conversion increase with increasing solids circulating rate and decreasing gas velocity due to the increase in gas residence time and solids holdup in the CFB. The carbon conversion increases with increasing temperature and O₂ concentration in the inlet gas. The experimental results prove that the CFB gasifier works well for high volatile, high reactivity coal.     

外部流化床燃烧气化反应器的试验研究

针对循环流化床气化炉普遍存在的飞灰及底渣含碳量高、煤炭利用率低、气化效率不高等问题，研制了外部流化床燃烧气化反应器。通过冷态试验，研究了外部流化床燃烧气化反应器的布风板空板阻力和料层阻力与流化风量的关系，测定了飞灰在反应器内的停留时间，研究了外部流化床燃料气化反应器的输送特性。试验证明外部流化床燃烧气化反应器对于降低循环流化床气化炉飞灰和底含碳量是完全可行的。     

Modeling and simulation of co-gasification of coal and petcoke in a bubbling fluidized bed coal gasifier

In this work we discuss the modeling and simulation of a fluidized bed coal gasifier which uses a mixture of coal and petcoke as its feed. A two phase model consisting of the bubble phase and the emulsion phase is used to describe the coal gasification process. We consider a non-isothermal model taking into account the effect of four heterogeneous reactions and four homogeneous reactions. We analyse the effect of various operating parameters such as composition of feed, location of feed point and ash content on the performance of the gasifier. The results of predictions of the simulations have been found to be in good agreement with the experimental results in the literature. It has been found that increase in petcoke content in the feed mixture tends to lower the efficiency and carbon conversion but increases the amount of syngas produced. Also, from the simulations, it has been found that increase in ash content of coal decreases the carbon conversion. We have concluded that the feed point of the solids should be above the point where O₂ that is present in the bed gets exhausted, in order to obtain the maximum carbon conversion and efficiency.     

流化床煤气化技术的研究进展

结合流化床煤气化过程原理和循环流化床反应器开发应用状况,综述了流化床煤气化技术的进展,分析比较了目前广泛应用的3种煤气化流化床:鼓泡流化床,循环流化床及增压流化床的工艺及特点,并对工业上应用的典型的煤气化流化床(高温温克勒(HTW)及灰熔聚气化)的气化工艺流程具有的优势和存在的问题进行了较为详细的分析,并概括了流化床煤气化技术的发展趋势及应用前景.     

Fluidized bed gasification of coal

Gasification of high ash India coal has been studied in a laboratory-scale, atmospheric fluidized bed gasifier using steam and air as fluidizing media. A one-dimensional analysis of the gasification process has been presented incorporating a two-phase theory of fluidization, char gasification, volatile release and an overall system energy balance. Results are presented on the variation of product gas composiiton, bed temperature, calorific value and carbon conversion with oxygen and steam feed. Comparison between predicted and experimental data has been presented, and the predictions show similar trends as in the experiments.     

灰融聚流化床粉煤气化技术应用及节能减排措施

介绍了灰融聚流化床粉煤气化技术的特点、工艺流程及采取的节能减排措施和效果.对常压和加压1.0 MPa灰融聚流化床粉煤气化炉生产1 000m3煤气的能耗分别与UGI富氧气化炉进行比较,结果表明:常压灰融聚流化床粉煤气化技术的能耗略低于UGI富氧气化技术,而加压1.0 MPa灰融聚流化床粉煤气化技术比常压灰融聚流化床粉煤气...     

灰融聚CAGG流化床粉煤气化技术述评

灰融聚CAGG流化床粉煤气化技术是我国具有自主知识产权的新型煤气化技术.介绍了该技术的气化原理、技术特点以及CAGG气化炉的结构特点;分别阐述了常压和加压灰融聚煤气化装置的工艺流程、气化指标、"三废"排放处理和装置投资情况;结果表明,新型CAGG灰融聚流化床粉煤气化技术适宜于中小型化肥、化工装置的气头改造以及燃料气、焦...     

灰熔聚冷模流化床中双组份体系颗粒分离特性的研究

本研究采用了等密度及不等密度的三种双组份混合体系，考察了不同分离气速及不同原始配比时沉积组份的分离效率和分离速率；给出了这两种分离特性的定量关联式；提供了达到高效分离（分离效率大于90％）的气速选择范围；得到的分离速率的定量方程能成功预测实际焦粉－灰球混合体系的实验结果，为实际灰熔聚气化炉中分离柱的高效稳定操作提供了依据     

Gasification of coal and PET in fluidized bed reactor

Blended fuel comprising 23 wt.% polyethyleneterephthalate (PET) and 77 wt.% brown coal was gasified in an atmospheric fluidized bed gasifier of laboratory-scale. The gasification agent was composed of 10 vol.% O₂ in bulk of nitrogen. Thermal and texture analyses were carried out to determine the basic properties of the fuel components. The influence of experimental conditions, such as the fluidized bed and freeboard temperatures on major and minor gas components and tar content, as well as features of the blended fuel gasification in comparison with the single coal gasification, were studied. In the case of coal with PET gasification, only the fluidized bed temperature showed significant influence on CO, CO₂, CH₄ and H₂ content in the producer gas, whereas the effect of the freeboard temperature was insignificant. In single coal gasification both temperatures had considerable and almost the same influence. The content of minor components, such as ethane, ethylene, acetylene and benzene, was found to be more dependent on the freeboard temperature than on the fluidized bed temperature. It was observed that the higher the freeboard temperatures get, the lower is the concentration of the minor components, with the exception of acetylene. The absolute contents of almost all minor and tar components were approximately three times higher in blended fuel gasification than that in single coal gasification. Finally, partition of carbon (char) and selected metals into bottom and cyclone ash in gasification of both fuels is discussed.     

反应器结构对多段气化炉内颗粒分布的影响

针对多段气化炉(上部快速床、下部鼓泡床),采用MP-PIC(Multi-Phase Particle In Cell)方法模拟了多粒径煤粉颗粒的三维全循环流化过程,考察了鼓泡床与快速床床径比及鼓泡床和快速床之间的过渡段高度对气化炉内流动特性的影响。结果表明,基本工况下,大颗粒主要存在于下部鼓泡床中,细颗粒主要存在于上部快速床内,但细颗粒会通过旋风分离器和回料管再次进入鼓泡床参与循环。进入旋风分离器的大部分为半径622 ?m以下的小颗粒,无1216 ?m以上的大颗粒。旋风分离器对小颗粒的分离效率为99.75%,分离效率良好。增大床径比(即减小快速床直径),快速床中气速增大,整个气化床更快达到稳定状态,被夹带到快速床中的颗粒增多,所夹带的颗粒粒径增大。过渡段高度存在一个适当值(炉高0.6~1.0 m),升高或降低过渡段高度,快速床中颗粒浓度均增大,颗粒通量均升高,旋风分离效率降低。     

气化对煤质的要求

介绍了气流床气化对煤质的要求,论述了煤的水分、反应活性、粒度和灰分对气化的影响。研究表明,煤的内水含量是决定煤浆性能的主要因素,灰渣的黏温曲线比灰熔点对气化炉的操作更具指导意义,选择在操作温度区间灰渣黏度变化平缓的煤种有利于气化炉的安全、平稳运行。     

Gasification of coal by a pilot flame in a modified fluidized bed

Coal is successfully gasified in the presence of a pilot flame in a modified fluidized bed. Except for the pilot flame, no external heat is required to operate this gasifier. The results showed that increasing the solid-to-air ratio in the feed increased the temperature and the products, carbon monoxide and hydrogen. About 95% of the volatile materials and 80% of the fixed carbon of the feed coal could be gasified by this pilot-flame gasification method. The ash could be efficiently separated during gasification by a distributor within the dead-zone collector of this gasifier.