增压喷动流化床煤部分气化与脱硫效率的试验研究

以空气和水蒸气为气化剂,在一内径为100 mm的V型布风板喷动流化床煤部分气化炉内进行了徐州烟煤的气化试验研究。研究了不同操作参数(温度、压力)对气化过程及脱硫效率的影响,认为提高温度和压力有利于改善煤气质量和提高脱硫效率。煤气化发展越来越向高压、大容量发展,考察压力对气化工艺过程的影响,对气化炉的放大设计与运行、降低对环境的污染均有实际意义。     

温度对中试规模的喷动流化床煤部分气化行为的影响

在构建的热输入2MW的中试规模加压喷动流化床部分气化试验装置上,对徐州烟煤的加压部分气化行为进行了研究.重点考察了气化温度对煤气成分、煤气热值、碳转化率和煤气产率等气化指标的影响.研究结果表明,煤气各组分的浓度,特别是甲烷浓度对气化温度非常敏感,碳转化率和煤气产率随温度的升高而增加,在试验的温度区间内,温度对煤气热值影响不大.部分气化炉所产生的煤气和半焦的热值均满足第二代增压流化床联合循环发电系统的要求.     

温度和压力对加压喷动流化床煤部分气化的影响

在热输入0.1MW的加压喷动流化床煤部分气化炉上以空气和水蒸气为气化剂,进行徐州烟煤的加压部分气化试验。考察了气化温度、压力等因素对煤气成分、煤气热值、干煤气产气率、碳转化率等指标的影响。气化温度是通过调整空气系数来实现的。试验结果表明:气化温度对煤气化过程影响显著,气化温度升高,煤气热值先增大后减小,产气率增加,碳转化率提高。而增大压力,床内气体速度变慢,延长了气化剂在床内的停留时间,另外压力增加改善了床内的流化质量,从而提高了气化效率,改善了煤气质量。     

煤浆浓度对水煤浆气化影响的数值模拟

采用数值方法模拟了应用于IGCC的水煤浆气化过程中煤浆浓度对出口煤气成分以及碳转化率的影响效果。总结了在具有复杂化学反应的高温、高压容器中,对水煤浆气化过程的数值模拟时经常遇到的问题和解决方法。得到了气化炉内的温度场、流场、浓度场以及出口粗煤气成分,其结果与工程实际相比非常接近;并利用得到的结果分析了影响水煤浆气化过程和出口煤气成分的主要因素之一的煤浆浓度,提出了提高出口煤气有效成分(CO H2)的措施。图7表1参8     

空气鼓风流化床煤部分气化炉煤气成分与热值试验

在内径100mm，高4．2m的常压流化床气化炉试验装置上进行试验，考察了气化炉温度，空煤比，汽煤比等影响因素对煤气成分和热值的影响，并对其气化机理进行了分析。结果表明，流化床煤部分气化炉内存在较佳气化温度，汽煤比和空煤比区域。图7表3参4     

锥形布风板喷动流化床煤气化技术及其应用

介绍了锥形布风板喷动流化床煤气化炉的系统装置和气化工艺流程 ,对喷动流化床气化及灰熔聚排渣原理作了简要介绍。在气化炉运行阶段 ,测量了煤气发生炉内炉膛温度沿高度的分布 ,研究了床层温度随流化风量和中心喷动风量的变化规律以及煤气成分和碳转化率随床温的变化规律。实验证明 ,以空气和水蒸气为气化剂的煤气发生炉 ,其适宜的气化床温在 960 980℃的范围内     

内循环流化床锅炉的研究

介绍一种具有V型布风装置和U型分离装置的内循环流化床燃烧锅炉。V型布风装置,使固体颗粒在床内作循环运动,改善了煤的燃烧。本文在一具有V型布风装置的内循环流化床中对颗粒的流动特性进行了研究,测定了最小流态化速度和压力分布。U型竖井分离装置的利用,进一步提高了细颗粒的燃烬程度。在一U型竖井分离装置中研究了颗粒的捕集程度和压力损失。自1987年以来,已有9台内循环流化床锅炉投入运行,当燃烧烟煤时,锅炉的燃烧效率达到93～95％。     

基于响应面法的煤气化工艺参数效应分析

以粉煤加压气化工艺为对象,基于ChemCAD仿真软件建立了煤气化过程仿真模型,采用中心复合设计进行了煤气化仿真试验,构建煤气化性能指标与工艺参数间的响应曲面,并在此基础上对煤气化各工艺参数对气化性能的主效应和交互效应进行了分析.结果表明：氧煤质量比是影响煤气化性能最重要的工艺参数,氧煤质量比的增加能提高煤气中CO体积分数、产气率和碳转化率,但会降低H2体积分数;蒸汽煤质量比主要影响煤气的有效气体成分,H2体积分数随其值提高而显著增加,CO体积分数下降;蒸汽煤质量比对产气率和碳转化率影响较小;压力对煤气中有效气体成分、产气率和碳转化率影响均不显著;氧煤质量比、蒸汽煤质量比和压力的综合效应对煤气中有效气体成分影响不显著,但对产气率和碳转化率等生产效率指标影响显著.     

气化参数对高温空气气化的影响

介绍了生物质高温空气气化思想和系统的工作原理及其过程，并就气化参数对生物质高温空气气化的影响进行了深入的分析，结畏发现：随蒸汽消耗率的增加气化温度降低，而气化所得的煤气热值增大；气化温度随氮碳比的增大而升高，而气化所得的煤气热值却随氮碳比的增加而降低；煤气热值随气化温度的增加而增大，但是增加量不大。     

煤气化过程中焦油裂解的试验研究

煤在热解和气化过程中产生的焦油，影响系统的正常运行。焦油脱除方法可分为气化炉内(初次脱除)和气化炉外(二次脱除)两类。尽管二次脱除法非常有效，但由于气化炉内初次脱除可以大大减少出口煤气中焦油含量，减轻甚至消除后期处理焦油的压力，故气化炉内脱除法得到重视。采用石灰石为催化剂，在1MW热态试验台上进行了试验，研究焦油和煤气成分在空气气化时添加不同石灰石含量工况下的变化情况，结果表明，石灰石的加入降低了焦油产率，提高了煤气产率，改善了煤气质量。     

Numerical Investigation on the Two Phase Flow Behaviors in Supercritical Water Fluidized Bed with Swirling Flow Distributor

ABSTRACT

Supercritical water fluidized bed reactor is a promising in the clean and efficient conversion of coal, and the distributor is one of the key component for the heat and mass transfer enhancement. However, the optimization study for the distributor in supercritical water fluidized bed reactor has been seldom conducted due to the special thermal properties of supercritical water. In this work, the swirling flow distributor was designed for its optimization for heat and mass transfer inside a supercritical water fluidized bed reactor. The swirling flow can be generated by the concentric circle or triangle type hole distribution in distributor with 0 or 45° intersection angle between the fluid inlet velocity direction and the distributor plane. The computational particle fluid dynamics (SCWFB) method, which has quick calculating speed and high accuracy, was used in this work to study the particle-fluid two-phase flow behaviors inside SCWFB with swirling flow distributors. Investigations were made to reveal the influence of the hole distribution type and intersection angle on the bed pressure drop and particle volume fraction characteristics. The results showed that the triangle type distributor with 45° intersection angle has the best fluidization performance. The conclusions drawn may has potential application for continuous and stable operation of supercritical water fluidized bed reactor for coal gasification.     

双室内循环流化床煤气化系统的冷态实验研究

本文发展并建了双室并列流化床煤气化系统的冷态模型。在此基础上,对影响气化系统操作的两个主要因素－两流化床之间颗粒物料的循环技术及流化床床层的膨胀特性进行了实验研究。     

关于循环流化床锅炉冷态空气动力场试验的研究

以某480 t/h循环流化床锅炉的空气动力场试验为例,详细介绍循环流化床锅炉空气动力场试验目的、试验项目和试验方法,并得出结论和建议。通过测定循环流化床锅炉锅炉布风板阻力特性和流化特性,得出锅炉的临界流化风量,为锅炉的热态运行提供必要的依据,保证循环流化床锅炉的安全、经济运行。     

Experimental investigations on a 20 kWe, solid biomass gasification system

When the objective is to generate motive or electric power via I.C. engine, the overall pressure drop through the suction gasification system in addition to gas quality has become a sensitive issue. This work, therefore, presents an experimental study on a suction gasifier (downdraft) arrangement operating on kiker wood or Acacia nilotica (L). Studies were conducted to investigate the influence of fluid flow rate on pressure drop through the gasifier system for ambient isothermal airflow and ignited mode, pumping power, and air-fuel ratio, gas composition and gasification efficiency. Results of pressure drop, temperature profile, gas composition or calorific value are found to be sensitive with fluid flow rate. Ignited gasifier gives much higher pressure drop when compared against newly charged gasifier bed with isothermal ambient airflow. Higher reaction temperatures in gasifier tends to enhance gasifier performance, while, overall pressure drop and thus pumping power through the system increases. Both ash accumulated gasifier bed and sand bed filters with tar laden quartz particles also show much higher pressure drops.     

Model validation of a CFB biomass gasification model

The developed 1-dimensional biomass gasification mathematical model [1] was validated using the experimental results obtained from a circulating fluidized bed biomass gasifier. The reactor was operated on rice husk at various equivalence ratios (ER), fluidization velocities and biomass feed rates. The model gave reasonable predictions of the axial bed temperature profile, syngas composition and lower heating value (LHV), gas production rate, gasification efficiency and overall carbon conversion. The model was also validated by comparing the simulation results with two other different size circulating fluidized beds biomass gasifiers (CFBBGs) using different biomass feedstock, and it was concluded that the developed model can be applied to other CFBBGs using various biomass fuels and having comparable reactor geometries.     

流化床煤气化技术的工业应用

介绍了几种典型的流化床煤气化炉 ,重点阐述了一种自主开发的流化床水煤气发生炉的工艺、结构、水煤气的组成和污染物的排放等 ,分析了流化床煤气的特点并与流化床燃煤技术进行了比较。认为流化床煤气化技术的开发值得我国锅炉制造行业的重视。     

Effect of the type of gasifying agent on gas composition in a bubbling fluidized bed reactor

It is commonly accepted that gasification of coal has a high potential for a more sustainable and clean way of coal utilization. In recent years, research and development in coal gasification areas are mainly focused on the synthetic raw gas production, raw gas cleaning and, utilization of synthesis gas for different areas such as electricity, liquid fuels and chemicals productions within the concept of poly-generation applications. The most important parameter in the design phase of the gasification process is the quality of the synthetic raw gas that depends on various parameters such as gasifier reactor itself, type of gasification agent and operational conditions. In this work, coal gasification has been investigated in a laboratory scale atmospheric pressure bubbling fluidized bed reactor, with a focus on the influence of the gasification agents on the gas composition in the synthesis raw gas. Several tests were performed at continuous coal feeding of several kg/h. Gas quality (contents in H₂, CO, CO₂, CH₄, O₂) was analyzed by using online gas analyzer through experiments. Coal was crushed to a size below 1 mm. It was found that the gas produced through experiments had a maximum energy content of 5.28 MJ/Nm³ at a bed temperature of approximately 800 °C, with the equivalence ratio at 0.23 based on air as a gasification agent for the coal feedstock. Furthermore, with the addition of steam, the yield of hydrogen increases in the synthesis gas with respect to the water–gas shift reaction. It was also found that the gas produced through experiments had a maximum energy content of 9.21 MJ/Nm³ at a bed temperature range of approximately 800–950 °C, with the equivalence ratio at 0.21 based on steam and oxygen mixtures as gasification agents for the coal feedstock. The influence of gasification agents, operational conditions of gasifier, etc. on the quality of synthetic raw gas, gas production efficiency of gasifier and coal conversion ratio are discussed in details.     

Quality of gas produced from wheat straw in a dual-distributor type fluidized bed gasifier

A 400 kW, dual distributor type fluidized bed gasifier was used to investigate the production rate and composition of the gas produced from wheat straw at various equivalence ratios (0.17, 0.20, 0.25, 0.35) and fluidization velocities (0.28, 0.33 and 0.37 m s⁻). The results showed that the equivalence ratio was the major parameter affecting the gas composition. The equivalence ratio of 0.25 appeared to be the optimum with respect to the quality of the gas. The mole fractions of the combustible components reached their maximum values at this equivalence ratio. A typical gas composition at the equivalence ratio of 0.25 was 7% H₂, 7% hydrocarbons (CH₄, C₂H₂, C₂/H₄ and C₂H₆), 14% C0₂, 22% CO and 50% N₂. The higher heating value of the produced gas (6.3–7.3 MJ Nm⁻³) obtained at this equivalence ratio appeared to be higher than most values reported in the literature for several types of biomass fuels.     

The generation of high temperature gas from fluidized bed furnaces

The work described relates to the development of a coal-fired fluidized bed furnace for the generation of hot gases for industrial heating processes. Following a programme of coal model studies of the internal solids circulation rates between adjacent beds, a furnace test facility was developed in the form of two interconnected fluidized beds. One bed is operated as a partial gasifier/pyrolyser and the other as a char combustor. The gas produced by pyrolysis is mixed above the bed with the oxygen-rich gas from the char combustor and burns to give hot gas at temperatures of up to 1600°C. The use of low ash washed singles grade coal (13–25 mm size range) gives an overall combustion efficiency better than 98 per cent.