Partial combustion is a thermo-chemical conversion process, which is applicable to tar reduction in the producer gas. Cracking and polymerization of tar, however, occur simultaneously during the partial combustion gas reforming process. In our research, effects of carbon dioxide and water vapor on the producer gas reforming under partial combustion are investigated by using the partial combustion gas reformer and the laminar counter-flow burner. From the experimental results, it was found that carbon dioxide and water vapor indeed had positive effects on tar reduction. We will continue to aim the acquisition of further useful knowledge relating to combustion characteristics of diluted multi-component fuels and formation characteristics of minor products such as soot and nitrogen oxides by upgrading experimental techniques shown in the present article.
This R&D project is being undertaken to establish a highly efficient process for SNG production from woody biomass by combining dual fluidized bed gasification with a novel methanation process under normal pressure. The R&D items include optimization of a dual fluidized bed gasifier (Twin IHI Gasifier (TIGAR®)), development of a highly efficient tar reformer and a methanation process for gasified gas. Experimental results using a pilot gasifier showed that the TIGAR® could be applied to any kinds of woody biomass regardless of fuel type such as pellet or chip. As for the development of highly efficient tar reformer, two kinds of reformer (regenerative reformer and catalytic reformer) were developed and tar reforming performance exceeding 99.5% was achieved in pilot-scale experiments; unreformed tar was less than 50mg/Nm3. Pilot-scale test of the methanation process was successfully conducted in continuous operation for about 50hrs; a methanation efficiency more than 76% had been obtained. Market survey showed that the business of SNG production from woody biomass will be profitable in south Asia.
Primary pyrolysis is the first step of coal combustion or gasification reactions. Char and volatile matters form during the primary pyrolysis. Their yields directly affect the following reactions, such as char combustion, char gasification or gas phase reactions. The volatile matter compositions are also important because they affect gas phase reaction and soot formation behavior. Two kinds of primary coal pyrolysis models to predict the volatile matter formation behavior were proposed in literature. One is assuming the primary pyrolysis as a global type reaction. The other is considering coal chemical structures. The former models are used only for predicting volatile matter yields. Several researchers analyzed assuming the reaction as a first order reaction, the results were not consistent with each other. The distributed activation energy model which assumes that countless first-order reactions having different rate parameters occur in parallel, is one of the effective alternatives. In latter, there are three famous models considering coal chemical structure; the FG-DVC model, FLASH-CHAIN model and CPD model. Progress of coal chemical structure analysis techniques, such as a NMR method helps increasing prediction accuracy of these kinds of model. Furthermore, these models are expected to be applied for predicting volatile matter compositions. For example, the CPD model was extended for predicting volatile matter compositions. In the extended CPD model, we considered nine reactions of functional groups and bridges, and also determined an aromatic nucleus cluster size distribution by NMR analysis data and pyrolysis experimental data. The polycyclic aromatic hydrocarbon (PAH) formation behaviors which were simulated by the extended CPD model, were consistent with the soot formation behaviors in coal gasification experiments.
Supercharged fluidized furnace is a incinerators that combines bubbling fluidized furnace and turbocharger. The combustion exhaust gas generated in the incinerator is introduced into the supercharger to drive the turbine, by producing compressed air by a compressor, power consumption, auxiliary fuel usage and N2O emissions are reduced. Summary In this paper, we introduce the operational status and the like.
Ammonia is regarded as one of the alternative fuels because of the physical properties of Ammonia are suitable for transportation and storage as the “hydrogen carrier”. On top of those preferable characteristics, the high amount of mass productivity can be achieved through Haber-Bosch process. However, there are some issues of ammonia fuel based on the combustion characteristics to be solved for appling ammonia to the industrial combustion furnaces, such as the low laminar burning velocity, the low flux of radiative heat transfer and also the large amount of Fuel NOx formation. These features of ammonia fuel may lead on the instability of the system operation, and quality of the material in the industrial combustion furnaces. Therefore, it is necessary to know the fundamental characteris of ammonia flame and to find the way how to improve those issues and how to apply ammonia as the fuel in the industrial combustion furnaces. In terms of those requirements, the fundamental characteristics of ammonia/N2/O2 laminar premixed flame and the effects of oxygen enrichment were experimentally investigated.
The objective of this paper is to provide basic information of the flow field around a fire whirl created by a fixed-frame or a rotating-frame fire whirl generator. Similar fire whirl generators to previous experimental studies are used to generate fire whirls under different conditions. A PIV method is used to obtain average flow field. The difference in tangential velocity distributions generated by the two different fire whirl generators is examined, and the validity of previous theoretical models is discussed. Radial velocity distribution near the flame base is also measured to reveal the presence of a boundary layer in which a fast flow toward flame is observed. This boundary layer controls the shape of flame base, hence the burning rate, and eventually the flame height of a fire whirl.