| 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.
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