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     

壳牌粉煤气化炉渣屏结渣原因探讨

介绍SCGP气化炉渣屏结构和功能。描述了渣屏结渣问题,从渣屏结构、热传递和煤质等方面分析渣屏结渣的机理,讨论了防止渣屏结渣的措施。     

Gasification of biomass wastes in an entrained flow gasifier: Effect of the particle size and the residence time

Experimental tests in an entrained flow gasifier have been carried out in order to evaluate the effect of the biomass particle size and the space residence time on the gasifier performance and the producer gas quality. Three types of biomass fuels (grapevine pruning and sawdust wastes, and marc of grape) and a fossil fuel (a coal-coke blend) have been tested. The results obtained show that a reduction in the fuel particle size leads to a significant improvement in the gasification parameters. The thermochemical characterisation of the resulting char-ash residue shows a sharp increase in the fuel conversion for particles below 1 mm diameter, which could be adequate to be used in conventional entrained flow gasifiers. Significant differences in the thermochemical behaviour of the biomass fuels and the coal-coke blend have been found, especially in the evolution of the H₂/CO ratio with the space time, mainly due to the catalytic effect of the coal-coke ash. The reaction temperature and the space time have a significant effect on the H₂/CO ratio (the relative importance of each of these parameters depending on the temperature), this value being independent of the fuel particle size.     

Steam gasification of bitumen oil in presence of Ni/dolomite catalysts

An important step in developing clean energy and reducing greenhouse gas emissions is the use of clean technologies such as gasification. In this work, we were used a bubbling fluidized bed (BFB) to convert the bitumen oil into a clean syngas in presence of three kinds of Ni/dolomite catalysts. While all three catalysts were acceptable in the process of tar elimination, but DN-22 was more successful in eliminating tar than the other two samples, which might be due to the higher amount of CaO in the composition DN-22. With increase in Ni, the amount of eliminated tars in the tar cracking process was also increased due to the delay in the deactivation of the dolomite catalyst.     

Modelling of a downdraft biomass gasifier with finite rate kinetics in the reduction zone

A model of a downdraft gasifier has been developed based on chemical equilibrium in the pyro‐oxidation zone and finite rate kinetic‐controlled chemical reactions in the reduction zone. The char reactivity factor (C_RF) in the reduction zone, representing the number of active sites on the char and its degree of burn out, has been optimized by comparing the model predictions against the experimental results from the literature. The model predictions agree well with the temperature distribution and exit gas composition obtained from the experiments at C_RF=100. A detailed parametric study has been performed at different equivalence ratios (between 2 and 3.4) and moisture content (in the range of 0–40%) in the fuel to obtain the composition of the producer gas as well as its heating value. It is observed that the heating value of the producer gas increases with the increase in the equivalence ratio and decrease in the biomass moisture content. The effect of divergence angle of the reduction zone geometry (in the range of 30–150°) on the temperature and species concentration distributions in the gasifier has been studied. An optimum divergence angle, giving the best quality of the producer gas, has been identified for a particular height of the reduction zone. Copyright © 2009 John Wiley & Sons, Ltd.     

煤气发生炉炉出煤气含水量计算

煤炭中的水和气化剂中的水等因素，对煤气发生炉炉出煤气含水量影响最大，通过气化反应过程中氢的平衡，推导了炉出煤气含水量计算公式。同时指出探火、打钎操作时汽封带入的水，和高温灰渣落入灰盘水封时汽化的部分水封水，以及煤炭中和空气中的氢元素等，也同样会不同程度地影响发生炉炉出煤气含水量，实际工程计算时应考虑据此进行适当修正。     

气化炉烧嘴损坏原因及对策

本文通过对气化炉生产状况的分析,寻找烧嘴损坏的原因,并提出相应的措施。     

浅谈合成氨装置造气炉小加氮工艺的实现

在造气炉传统工艺设计基础上,采用小加氮的工艺操作方式取代大加氮操作方式,用于稳定造气炉炉温,达到稳定造气炉运行、提高单炉发气量的目的.采用小加氮操作方式之后,单炉发气量提高50～100 m3/h(标态),吨氨原料煤消耗下降20～40 kg.     

关于Shell煤气化装置的投煤试车及载气切换

介绍了Shell粉煤气化装置投煤试车前的准备工作；分析了装置试运行期间的常见问题；从输送煤粉的载气由氮气切换为CO2以及炉温控制方面论述了气化炉工艺操作要点，提出了完善装置的建议。结果表明，投煤试车成功后，装置以90％负荷稳定运行，最高负荷达到97％，且有效气体产量稳定在8万m^3／h。     

Sustainable model for financial viability of decentralized biomass gasifier based power projects

This paper made a modest attempt for designing a sustainable model for financial viability of biomass gasifier power projects for enhancing electricity access in India and other developing countries. For long term sustainability of distributed generation projects in remote rural areas, viability from both project implementing agency (PIA) and the end-users need to be ensured. The minimum required prices of electricity from both PIA and end-user perspective have been estimated. While for PIA the cost recovery is the key for viability, the affordability to pay the electricity cost is crucial for the end users. Analysis carried out in this paper on the basis of data obtained from operational projects implemented in India reveal that it is essential to operate the system at a higher capacity utilization factor. While this can be achieved though creating convergence with locally relevant economic activity, it is also observed that micro-enterprises cannot pay beyond a certain price of electricity to keep it sustainable. This paper sets forth a case for developing a regulatory mechanism to extend the tariff fixation for the projects and providing cross-subsidies to ensure long term sustainability of off-grid project.