【作者】 李继炳；

【导师】 王基铭； 沈本贤；

【作者基本信息】 华东理工大学 ， 化学工艺， 2011， 博士

【摘要】 煤气化是煤化工和煤清洁高效利用的起点,也是煤炭清洁高效综合利用最重要的单元技术,煤制油、煤制烯烃、煤基合成气等现代煤化工技术和IGCC技术都是以煤气化为龙头的。随着现代煤利用技术的发展,大规模煤气化技术作为一种高效、洁净的煤转化技术日益受到重视,广泛用于合成化学品和制气等众多领域。我国是一个“缺油少气”、煤炭资源相对丰富的国家。为了把有限和紧张的原油资源更多地转化为交通运输燃料,必须更多地开辟以煤为原料生产化工产品的途径,也必须更加重视煤为能源的清洁高效利用,因而,煤气化在我国具有更加重要的意义。近年来,随着原油价格的不断上涨,我国众多以石脑油和重油为原料生产化肥的企业都面临着巨额亏损。化肥原料“油改煤”是化肥产业结构调整的一项重要措施,“油改煤”的关键装置是煤气化装置。中国石化安庆分公司是我国最早引进Shell煤气化装置、最先开车成功的单位之一。但是,该煤气化装置设计用煤为皖北刘桥二矿混煤,在生产过程中遇到棘手的气化炉渣池堵渣和废锅积灰问题,严重影响了气化装置的长周期运行。为突破该技术瓶颈,本论文开展了对配煤和新型助熔剂改进Shell煤气化工艺的研究。论文首先考察了煤灰组成与煤灰熔点之间的关系,同时对配煤、助熔剂、配煤和助熔剂降低皖北刘桥二矿混煤(C07)的灰熔点效果进行了研究考察,并采用最小二乘法进行线性回归,建立了皖北刘桥二矿混煤配煤的灰熔点预测关系式。结果表明,皖北刘桥二矿混煤煤灰中SiO2和Al2O3的含量相对较高,流动温度达到1520℃,属于高灰熔点煤,难以直接使用于Shell气化炉。配煤、助熔剂、配煤和助熔剂联用均可降低C07煤的灰熔点,达到Shell气化炉对煤灰熔点FT<1350℃的要求。但仅仅以配煤的方法,配煤用量大,可选的煤种范围也相对少,同时还有煤源不稳定以及煤质不稳等问题。建立的C07配煤灰熔点预测模型关系式表明,适当增加配煤煤灰中CaO的含量可使煤灰熔点降低,而若能增加配煤煤灰中MgO的含量则可显著降低煤灰熔点；在SiO2和Al2O3总含量一定时,高硅低铝的配煤可使煤灰熔点更低。分析了不同粘结性的飞灰物理化学性质,表明：在常温下,不论易粘结还是不易粘结的飞灰均无粘结性；飞灰呈球形,飞灰六种主要元索中,Si、Al、K元素的相对含量相差较小,但Ca, Fe和S元素相差很大；不易粘结的匕灰堆积密度大,孔径分布相对较宽。对皖北刘桥二矿煤的大颗粒球形飞灰颗粒表面的不同部分——白色区域、灰色区域和部分表面附着碎屑颗粒——的元素分析,表明大球形飞灰颗粒为Si、Al为主体的颗粒,表面粘附着含Ca元素含量较高的小球：飞灰颗粒白色区域即无粘附着小球的表面,Mg元素相对含量最高,比较光滑.对不同煤气化时矿物元素的分布及集散规律考察表明：CaO和Fe2O3两种矿物质成分在飞灰中的含量与入炉煤样有明显区别,即它们之间的差异是导致飞灰粘结力有所差异的重要原因。在对堵渣和积灰两个问题获得新的认识基础上,考察不同矿石助熔剂对C07煤降低灰熔点的效果。采用优选出的助熔效果较好的矿石样品FMA与FMH复配,在考察了复配样品对皖北刘桥二矿混煤灰流动温度影响的基础上,得到新型助熔剂FHC。对FHC重复性地制备,用于对不同煤以及同一种煤不同批次进行煤灰流动温度考察。结果表明,FHC对高熔点煤的改善效果好,在添加量为4%时,可使皖北刘桥二矿混煤等高熔点煤的流动温度降至1350℃以下。同时考察了FHC对皖北刘桥二矿混煤(C07)和皖北百善混煤(C05)煤灰的粘温特性曲线的影响,在添加4%FHC条件下,高熔点煤C07与C05煤灰的粘温操作范围拓宽了,渣型从“短渣”变为“长渣”。以皖北刘桥二矿混煤为原料,与云南高硫煤进行配煤,并采用自研开发的新型助熔剂FHC,在中国石化安庆分公司Shell煤气化装置正常连续运行110天,较大幅度地延长了煤气化装置的运行周期。最后,论文采用X射线衍射(XRD)、傅立叶-红外光谱(FT-IR)、元素分析等仪器对Shell煤气化助熔与飞灰抗粘结机理进行了研究。结果表明,皖北刘桥二矿混煤的高灰熔点主要是由在高温下生成莫来石引起的。对同一比例的不同煤种的配煤煤灰和不同比例的固定煤种的配煤煤灰的红外分析可知,在配煤实验测其灰熔点的过程中,灰成分发生了变化,矿物质的结构也发生了变化,从而影响了灰熔点的变化。添加助熔剂后,高温时助熔剂与煤灰生成了低温共熔化合物,从而使煤灰熔点明显下降。而对飞灰物理化学性质、飞灰微观颗粒以及飞灰的二次加热分析表明,飞灰的粘结与飞灰的颗粒大小,即飞灰自身的元素组成有关,同时认为飞灰的粘结性与飞灰的这种在热条件下的品相转变能力或者生成趋势有关。揭示了,在皖北刘桥二矿混煤中加入石灰石助熔剂,虽然降低了煤的灰熔点,但同时却使飞灰的粘结性增强；而镁代钙新型助熔剂可在降低煤灰熔点的同时,减弱飞灰的粘结性,达到两利的效果。更多还原

【Abstract】 Coal gasification is the starting point of coal industry and coal utilization in clean and high efficient way. It is also the most important unit technology of coal utilization through clean and high efficient way. The modern coal chemical technologies, such as Coal Liquefaction, Coal to Olefin and Coal-based Syngas, and IGCC technology are dominated by coal gasification. With the development of modern coal utilization technology, large scale coal gasification technology is highly valued as a clean and high efficient coal conversion technology, widespread use in vast fields such as synthetically chemicals and gas preparation.There is abundance of coal resource but lack of oil and gas in our country. For the purpose of converting more limited crude oil into petroleum products, New path for producing chemicals from coal and pay more attention to clean and high efficient utilization of coal resource should be opened up. Therefore, coal gasification has greater significance in our country.In current years, numerous enterprises which produce fertilizer by using the materials of naphtha and heavy oil face with great loss with the crude oil price fluctuating on high platform. Oil replaced by coal is an important measurement for reorganization of the structure of Fertilizer Enterprises. The key for replacing oil by coal is coal gasification. Sinopec Anqing Branch is one of the companies which imported Shell Coal Gasification Process(SCGP) and achieved successful commissioning. However, the design feedstock of gasifier was Liu-qiao No.2 coal mine in northern Anhui(C07). During the commissioning, slag blockage of gasifier and fly ash deposition in gas cooler were occurred frequently, having adverse impact on the long-period running of the SCGP. In order to break out the technical bottleneck, the paper will focus on Shell’s coal gasification process improved by coal blending and new-type flux.Firstly, the relationship of the composition and melting point of coal ash was studied. Meanwhile, The effect of blending coal, flux, blending coal with flux respectively on decreasing the ash melting point of C07 was also reseached. And the prediction equation for ash melting point of C07 was established by least square linear regression. Results showed that the composition of SiO2 and Al2O3 were relatively high in C07, and the flow temperature reached up to 1520℃. Hence, such high melting point coal cannot be used for Shell coal gasification process directly. Blending coal. flux, and blending coal with flux all can decrease the coal melting point of C07, meeting the requirement of SCGP with the coal ash melting point (flow temperature. FT) lower than 1350℃. By using blending coal only, the amount of blending coal was very large and the coal that could be selected was relatively limited. In the meanwhile, there also existed some problems, such as unstable coal resource and unstable coal quality. The equation of prediction model for ash melting point of blending coal of C07 showed that the ash melting point would decrease with the increasing of CaO content. And the ash melting point would significantly decrease with the increasing of MgO content. When the content of SiO2 and Al2O3 was fixed, the ash melting point would be lower if the silicon content was higher while the aluminum content is lower in the blending coal.Secondly, the physico-chemical properties of fly ash with different agglomeration were analyzed. The results showed that fly ashes with round shape have no agglomeration at normal atmosphere temperature. The elements contents difference of Si, Al and K is relatively low while the contents difference of Ca, Fe and S have big difference in six main elements. The bulk density of ash which has little agglomeration is big and particulate distribution spread widely.The Element analysis results for different region in a big round ash from C07 of white surface, grey surface and other surface with small particles stick to big round ash surface showed that big round ash particle whose main elements were Si and Al were adhered by small ball whose Ca content was relatively high. The white region which didn’t have small ball adherence had more element of Mg, the surface was smoother. The distribution of mineral elements from different coal gasification and the discipline of collection and distribution were investigated. The contents of CaO and Fe2O3 in fly ashes distinguish from the contents when they were put into the gasifier. The difference of the elements contents lead to the different agglomeration of fly ash.On the basis of getting the new understanding of slag blockage of gasifier and ash deposition in gas cooler, the effect of different mineral fluxes on decreasing the melting point of C07 was investigated. The optimal minerals of FMA and FMH were complexed. And their effection on decreasing the ash melting point of C07 was studied. And the new-type flux of FHC was formed. The reproducibility of FHC, effect of different coals and same coal with different batches on decreasing FT had also been investigated.The results indicated that, the new-type flux of FHC can efficiently decreasing the ash melting point of coal with high melting point. The FT of coal with high melting point such as C07 dropped to below 1350℃by adding 4% FHC. The viscosity-temperature characteristic curve was also studied by adding flux of FHC to C07 and Bai-shan coal in northern Anhui(C05). The operating range of temperature-agglomeration of high melting point C07 and C05 had been broadened by adding 4% FHC, the type of slag changed from short slag to long slag. The feedstock of gasifier was C07 mixed with different proportion of high content sulfur coal in Yunan and flux. Except two stops caused by electricity and instrument, the SCGP of Sinopec Anqing Branch was running for 110 days continuously without failure caused by slag blockage or ash agglomeration. The operation cycle running time was significantly extended.Finally, the mechanism of SCGP melting behavior of flux and non-agglomerating behavior of fly ash was investigated by using the analysis instruments such as XRD, FT-IR and elements analysis. Results showed that mullite formed under high temperature has an effect on increasing the ash fusion temperature of coal, and this was the major reason which leads to high ash fusion temperature of C07. It is known from the results of different coals in the same proportion and same coals in different proportion that during the coal blending experimental period of measuring the ash melting point, the ash composition has changed and the mineral structure also has changed accordingly, which leads to the change of the ash melting point. After flux is added, low temperature eutectic mixtures are generated by flux with coal ash, which leads to the ash melting point shapely dropping. Through the analysis of fly ash’s physico-chemical properties, fly ash’s microcosmic particulate and ash’s double heating, the fly ash’s agglomeration is affected by their particle size distribution. Simultaneously, non-agglomeration has a relationship with the crystal phase transition or crystal generation trend under high temperature condition. It is revealed that limestone as flux is added into the blending coal of C07 for SCGP, the melting point could be decreased but at the same time the agglomeration would strengthen. New-type flux using Mg replaced by Ca can decrease the coal ash melting point and weaken the agglomeration of fly ash.更多还原