A MODEL OF A PYROLYSIS GASIFIER FOR PREDICTION COMPOSITIONS AND FLOU RATE OF PRODUCED GAS

A model of pyrolysis gasifier, which is mainly composed of a pyrolysis, a cracking and a combustion chamber, it developed to predict its performance parameters and to simulate its operation. Toe model consists of a pyrolysis-cracking sub-model, a secondary gasification sub-model and a combustion sub- model, of which the pyrolysis-cracking sub-model is modified to predict components of tbe pyrolysis gas. Then, It with the other two sub-models can predict components, heating value and flow rate of the produced gas, thermal efficiency and total energy efficiency of the gasifier as ell. Crank-Nicolson Scheme (half implicit difference formulation) in which the time step is not confined by stability and the cutting error is small, is applied to solving the model whose differential equations are nonlinear and have no analytic solution. Theo, the nonlinear difference algebraic equations are solved by interalions, which requires less storage of computer. Underrelaxation is applied to avoiding divergence of Causs-Seidel interations. Finally, the simulated results are input to Software Lotus 1-2-3, by which the results are printed and graphed so as to compare with the experimental ooes, and it shots acceptable agreement, thus validate the model.     

试论小氮肥造气工序设备的更新换代

论述小型氮肥厂近年来在煤造气工序中主要设备的更新换代问题;介绍许多优良的新设备和新技术的应用情况。     

水煤浆加压气化炉用高铬耐火材料的显微结构及损毁机理

采用扫描电镜和能谱分析方法 ,分析了水煤浆加压气化炉用高铬砖渣蚀前后的显微结构和相组成 ,探讨了主要损毁机理。结果表明 :煤熔渣与砖反应和渗透引起砖组成的改变 ,从而导致砖的结构剥落和强度弱化是砖损毁的主要原因 ;LIRR -HK90砖的显微结构呈网络状镶嵌结构 ,直接结合程度高 ,与渣反应可生成 (Mg ,Fe) (Al,Cr,Fe) 2 O4 复合尖晶石致密带 ,阻止了渣的进一步渗透 ,减缓渣蚀速度和结构剥落 ,其使用效果优于进口的同类产品     

合成气管线积灰原因分析及解决方案

分析SE-东方炉合成气管线压降高的原因,发现大量细灰在管道内累积,使得管道流通面积减小,通过工艺操作优化及工艺流程改进,解决了积灰的问题.     

Microscopic and macroscopic atomization characteristics of a pressure-swirl atomizer,injecting a viscous fuel oil

Combustion of heavy fuels is one of the main sources of greenhouse gases, particulate emissions, ashes, NOxand SOx. Gasification is an advanced and environmentally friendly process that generates combustible and clean gas products such as hydrogen. Some entrained flow gasifiers operate with Heavy Fuel Oil(HFO) feedstock. In this application, HFO atomization is very important in determining the performance and efficiency of the gasifiers.The atomization characteristics of HFO(Mazut) discharging from a pressure-swirl atomizer(PSA) are studied for different pressures difference(Δp) and temperatures in the atmospheric ambient. The investigated parameters include atomizer mass flow rate( _m), discharge coefficient(CD), spray cone angle(θ), breakup length(Lb), the unstable wavelength of undulations on the liquid sheet(λs), global and local SMD(sauter mean diameter) and size distribution of droplets. The characteristics of Mazut sheet breakup are deduced from the shadowgraph technique. The experiments on Mazut film breakup were compared with the predictions obtained from the liquid film breakup model. Validity of the theory for predicting maximum unstable wavelength was investigated for HFO(as a highly viscous liquid). A modification on the formulation of maximum unstable wavelength was presented for HFO. SMD decreases by getting far from the atomizer. The measurement for SMD and θ were compared with the available correlations. The comparisons of the available correlations with the measurements of SMD andθ show a good agreement for Ballester and Varde correlations, respectively. The results show that the experimental sizing data could be presented by Rosin-Rammler distributions very well at different pressure difference and temperatures.     

A low carbon cooling system using renewable energy resources and technologies

A simulation study to assess the performance of a renewable energy (solar-biomass) based single effect LiBr-water absorption chiller suitable for residential applications was conducted. The model took into account the characteristics of all the components of the system. Using Bangkok meteorological data and component specifications from manufacturers and other sources, the performances of solar collector, storage tank, biomass gasifier and boiler, and the absorption cooling system, as well as the overall system performance on a daily and monthly basis has been evaluated. The chiller and overall system coefficient of performances was found to be 0.7 and 0.55 respectively and the biomass (charcoal) consumption for 24 h operation was 24.44 kg/day. To validate the model formulation and its predictions, experimental observations of a similar system (same chiller size) were compared with the model results. The results of the study indicate that solar-biomass hybrid air conditioning for tropical locations for residential applications is feasible, and can replace conventional vapor compression systems, thus reducing the need for fossil fuel based energy systems for cooling purposes.     

Flow properties and rheology of slag from coal gasification

We have studied the rheological characteristics of Texaco gasifier slag at high-temperature. Slag samples have been analyzed by X-ray fluorescence, X-ray diffraction, and scanning electron microscopy. The rheological behavior of the slag has been investigated experimentally using a high-temperature rheometer at temperatures between 1200 °C and 1340 °C. The effects of the shear rate and temperature on the rheological behavior of the slag have been explored. Moreover, the observed rheological behavior of the slag has been correlated with its solid-phase content, as calculated with the aid of the computer software package FactSage. The results show that the sensitivity of the slag viscosity to temperature decreases with increasing rotation speed. Above its liquidus temperature calculated by FactSage, the slag behaves as a Newtonian fluid; below its liquidus temperature, however, the rheological behavior of the slag becomes non-Newtonian owing to its increased solid-phase content. Meanwhile, Slag containing a number of crystalline particles shows dramatic shear-thinning and thixotropic behavior. Moreover, the shear-thinning behavior of the slag becomes ever more distinct as the temperature is decreased. The yield stress values of the slag and the number and particle size of the crystalline particles in the slag increase with decreasing temperature.     

Experimental Study on a Hot‐Oxygen Burner in a Bench‐Scale Gasifier

The direct‐ignition technology of an entrained‐flow coal‐water slurry gasifier with hot‐oxygen burner (HOB) is presented. Experimental tests were carried out using diesel oil and coal‐water slurry in a bench‐scale entrained‐flow opposed multi‐burner (OMB) gasifier. Using a CCD camera equipped with high‐temperature endoscope, flame images inside the gasifier were recorded and subsequently processed. The results show that the HOB diesel flame is more stable than the normal two‐channel burner flame typically used. Entrained‐flow coal‐water slurry gasifiers can start up using the HOB directly without a higher preheated wall temperature. An HOB can potentially save gasifier preheating time and operation costs and enables a wide range of future applications.     

Thermochemical modeling of refractory corrosion in slagging coal gasifiers

Slagging coal gasifiers suffer corrosive attack on the refractory liner and these interactions were thermochemically simulated. The slag is observed to penetrate the refractory, which complicates modeling the phase behavior of the slag-penetrated interior of the refractory. A simple strategy was adopted such that stepwise changes in composition with decreasing slag content were assumed to account for the compositional changes as slag penetrates the refractory. The thermochemical equilibrium calculations following this strategy typically yielded three solution phases as well as the stoichiometric crystalline phases AlPO₄ and Ca₃(PO₄)₂ depending on composition/penetration. Under some conditions a slag liquid miscibility gap exists such that two slag liquids coexist.     

德士古水煤浆加压气化装置应用技术总结

结合德士古水煤浆加压气化技术的生产实践情况．从工艺流程及主要生产指标、运行情况与德士古公司工艺软件包（ＰＤＰ）中的数据进行了对比．主要工艺指标均高于原设计值，系统开工率也逐步提高。还介绍了在近两年的主要技术改造工作，优化了工艺生产系统及国产化耐火砖与进口砖使用情况及价格方面的对比，阐明了系统中存在的问题以及如何改进。