高焦混合煤气代替发生炉煤气使用中存在的问题及处理

１前言 我厂原发生炉煤气站是１９７２年建成并投产的，有４台煤气发生炉，平时开二备二，产冷净发生炉煤气１．４万ｍ３／ｈ，供给本厂生产使用。冷净发生炉煤气热值约６．０ＭＪ／ｍ３，该煤气站在国内属中小型规模的煤气站，其能源费、环保治理费、设备费等总成本费用高达９８６万元．为了节能降耗、减污增效，太钢公司决定回收南区的高炉煤气，但因高炉煤气热值较低，需配入适量的焦炉煤气，以代替我厂煤气站生产的发生炉煤气． 从１９９８年７月份开始，我厂锻造加热炉、退火炉正式使用了公司的高焦混合煤气，同时运行了２７年的发生炉…     

新型低热值发生炉煤气灶

目前,在工业生产中,许多企业建立了发生炉煤气站,为加热炉提供燃料。但由于生产负荷多变,煤气站为保持一些设备的安全使用,经常被迫将部分煤气放空。许多化工生产中的尾气也有大量的放空。一般认为这种煤气中一氧化碳含量较高,使用不安金;还认为这种煤气发热量低,回收使用价值不大。其实,将这些煤气放入空中既造成能源的浪费,又造成环境的污染。近年来有些工厂将放空的发生炉煤气收集起米,用管道输送到职工家中使用。据统计,一户四口之家直接烧蜂窝     

煤气站

<正>煤气站,主要由煤气发生炉、管路系统、煤气处理系统、循环水系统、监控系统等构建而成。煤气站主要是通过煤气发生炉生产煤气,并附有焦油、酚水及少量H2S产出。由于有很多种煤气发生炉,它们的设计不尽相同,所以各种煤气站建成后会有一些区别。由于其生产具有很大危险性,所以煤气站配     

干馏炉半冷煤气站与其他热煤气站对比分析

对干馏炉半冷煤气站与热煤气站在工艺、煤气热值与产量、焦油质量与回收、煤气洁净度、资源节约、应用与维护、投资等多方面进行了对比分析，以便于发生炉应用企业在选用煤气发生站时进行决策。     

煤气站

煤气站,主要由煤气发生炉、管路系统、煤气处理系统、循环水系统、监控系统等构建而成。煤气站主要是通过煤气发生炉生产煤气,并附有焦油、酚水及少量H2S产出。由于有很多种煤气发生炉,它们的设计不尽相同,所以各种煤气站建成后会有一些区别。由于其生产具有很大危险性,所以煤气站配有煤防站等安全协作体系。煤气炉分类：有双段发生煤气炉、单段发生煤气炉、热煤气发生炉、冷煤气发生炉。     

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.     

锰铁高炉富氧鼓风的实践

富氧鼓风在２５５ｍ３锰铁高炉上的生产实践和应用效果，在富氧率３％－４％范围内，富氧率提高１％，冶炼强度可提高８．１１％，焦比降低２．８８％，在现有富氧率条件下，未发现因风口前理论燃烧温度升高而影响高炉顺行，富氧后明显富化了煤气热值，降低了炉顶煤气温度，本文还初步探讨了锰铁高炉富氧鼓风的极限。     

钢铁企业煤气平衡问题的探讨

钢铁联合企业在生产大量钢、铁产品的同时 ,也产生大量的副产品—煤气 ,而煤气又是钢铁生产中的主要能源 ,占企业总能源消耗的比例较大。在实际生产中由于煤气系统的不平衡导致了生产不连续、能耗升高等许多问题。全面分析钢铁企业煤气系统状况 ,科学制定煤气供需之间的平衡对策 ,对发展钢铁生产、降低能源消耗和改善环境都有重要的意义。     

冷净煤气的输送和点燃

生产清洁冷煤气时,煤气要经过一系列的洗涤、冷却、捕焦、除尘、储气、加压等设备,管路吹扫比较麻烦,但是,这一工作关系到送气的安全性,必须仔细、认真做好。蒸汽吹扫和煤气吹扫是从煤气炉的煤气出口到燃烧器前,按顺序将诸设备依次逐个进行,路线较长时应分段进行。每个净化、储存、加压、脱硫设备上都有放散口,各设备蒸汽吹扫和煤气吹扫时,不要计时间长短,而应以煤气化验结果中含氧量低于0．8％为准,前面设备合格后即可关闭放散阀,开启下一设备的蒸汽、煤气进口和放散阀进行吹扫。各设备中煤气含氧量合格后,再分段吹扫管道,直到燃烧器为止。整个煤气站调试合格,然后按热煤气点火方法一样点火,同时关闭煤气管道末端的放散阀,煤气站投入正常运行。     

煤气循环水系统的合理设计

本文对太重煤气站洗涤煤气循环水改造前后状况进行分析,通过理论计算与实际运行比较得出,在煤气工程设计中,将煤气循环水系统冷,热分开发设计是合理的。     

Experimental‐ and numerical‐simulation research on the inner–secondary‐air ratio in a 600‐MWe down‐fired boiler

Using a phase Doppler‐anemometer measurement system, the cold gas/particle‐airflow behavior in a 1:40 scale‐model furnace was assessed to study the influences of adjusting the inner–secondary‐air ratio in a 600‐MW_e multi‐injection and multistaging down‐fired boiler. Numerical simulations were also conducted to verify the results of the modeling trials and to provide heat‐state information. The results demonstrate that reducing the inner–secondary‐air ratio from 19.66% to 7.66% gradually enhances the downward velocity decay of the gas/particle airflow, while the inner secondary‐air downward‐entraining effect on the fuel‐rich flow is weakened. Lowering the inner–secondary‐air ratio greatly inhibits the decay of the near burner–particle volume flux. In addition, the fuel rich–flow ignition distance is reduced, from 1.02 to 0.87 m. A lower inner–secondary‐air ratio is harmful to restrain early NO_x formation. Reducing the ratio also causes the fuel‐rich flow to turn upwards ahead, while the penetration depth of this flow gradually decreases and the maximum temperature in the hopper region falls from 1900 to 1800 K. On the basis of these data, an optimal inner–secondary‐air ratio of 13.66% is recommended.     

厌氧膜生物反应器处理有机垃圾渗滤液的COD去除率与膜过滤性能研究

考察厌氧膜生物反应器（AnMBR）在依次改变膜过滤通量[7 L/(m²∙h)、6 L/(m²∙h)、5 L/(m²∙h)、4 L/(m²∙h)]运行下处理实际有机垃圾渗滤液的膜过滤性能,分析了膜污染后污染物阻力分布状况。在水力停留时间（HRT）为10 d、固体停留时间（SRT）为100 d、有机负荷（OLR）为5 ~ 6 g-COD/(L∙d) 的条件下运行104 d。实验结果显示,化学需氧量（COD）的去除率可以达到90% ~ 93%,过滤通量增加后压缩泥饼层使COD去除率有所提高。在初始通量为6 L/(m²∙h) 下实现了较好的过滤性能,增加通量至7 L/(m²∙h) 后不可逆污染会快速形成,即使通量再降低至5 L/(m²∙h),甚至4 L/(m²∙h) 后,膜过滤性能仍较差。通过膜清洗测定过滤阻力分布,结果显示泥饼层阻力占总阻力的52%,是造成膜污染的主要因素。降低运行通量对不可逆污染恢复效果差,需及时进行化学清洗,可通过分析膜污染特征调整清洗策略,优化试剂使用量。     

欧盟国家新兴的生物天然气产业

欧盟国家在近几十年发展沼气的过程中,经历了从以处理生活污水无害化产生的污泥为主,到以获取优质可再生能源为主、能源和环保兼顾的战略性转折,原料范围显著扩大,规模迅速向产业化方向发展。欧盟2007年沼气总量达到约100×108m3,其中50%来自垃圾填埋气,30%来自农业废弃物和能源作物,20%来自下水道处理产生的污泥。瑞典在全球率先开发车用生物天然气;德国的沼气厂由2000年的1000家发展到2010年的约5000家,发电产能为2700MW;瑞士则非常重视可持续的原料供应及沼气发酵技术的研究创新和开发;英国现有38座沼气厌氧工程,垃圾填埋气占全部沼气产量的约90%,主要用于燃气轮机发电和供热;法国议会于2010年7月通过新环保法案,强制性收购生物天然气并给予并入天然气管网的优惠性补贴。减排温室气体和提高天然气自给率是欧盟产业沼气大发展的最大推动力,而立法和扶持政策在其产业沼气的成长阶段发挥了决定性作用。随着传统原料资源量的日渐匮乏,沼气专用能源作物应运而生,其潜力远大于其他资源。能源作物青贮后可以长期不霉变、不腐烂,这对于大型沼气企业全年稳定生产具有决定性意义。另外,沼气的单位土地能量产出率是最高的。我国天然气资源短缺,大力发展产业沼气将对提高我国天然气自给率和实现应对全球气候变化中长期规划目标起到不可忽视的作用。     

Numerical Study of Nanofluid Condensation Heat Transfer in a Square Microchannel

This study presents a numerical study of nanofluid condensation heat transfer inside a single horizontal smooth square tube. The numerical results are compared to previous experimental predictions, and show that the heat transfer coefficient can be improved 20% by increasing the volume fraction of Cu nanoparticles by 5% or increasing the mass flux from 80 to 110 kg/m² s. Reducing the hydraulic diameter of the microchannel from 200 to 160 µm led to an increase in average condensation heat transfer coefficient of 10%. A new correlation estimating Nusselt number for condensation of nanofluids or pure vapor is proposed. It predicts average condensation heat transfer, with good agreement with the computed values.     

Experimental study on water recovery and SO2 permeability of ceramic membranes with different pore sizes

In this study, the water recovery performance from flue gas with ceramic membrane tubes of different pore sizes 30, 50, and 200 nm was experimentally studied. The effects of flue gas temperature, flue gas flow rate, water coolant temperature, and water coolant flow rate on the water recovery performance were analyzed. In addition, in the experimental study of SO₂ permeability, the pH of the water coolant inlet and outlet was measured using a pH meter to analyze the SO₂ permeability of ceramic membranes during the water recovery process. The results show that the water recovery performance of the 50 nm pore size ceramic membrane is better than that of the other two types of ceramic membrane in most cases. The maximum amount of reclaimed water and the highest water recovery rate are 4.82 kg/(m²·h) and 80.3%, respectively. Under the same SO₂ concentration condition, the SO₂ permeation flux of the 30 nm pore size ceramic membrane is smallest, and that of the 200 nm membrane is the largest. When the SO₂/N₂ mixed gas flow rate is 6 L/min, the SO₂ permeation flux of the 30 and 200 nm membranes is 0.407 and 0.635 mmol/(m²·h), respectively. The ceramic membrane with smaller pore size can block more SO₂ permeation, while the ceramic membrane with larger pore size can remove SO₂ better.     

Numerical study of nanofluids condensation heat transfer in a square microchannel

ABSTRACT

This paper presents a numerical study of nanofluids condensation heat transfer inside a single horizontal smooth square tube. The numerical results are compared with the previous experimental predictions. The numerical results show that the heat transfer coefficient could be improved within 20% by increasing the volume fraction of Cu nanoparticle by 5% or by increasing the mass flux from 80 to 110 kg/m² s. Reducing the hydraulic diameter of the microchannel from 200 to 160 µm leads to an increase in the condensation average heat transfer coefficient by 10%. A new correlation estimating the Nusselt number for the condensation of nanofluids or pure vapor is proposed. It predicts average condensation heat transfer with a good agreement with those computed.     

Research on the release of gases during the bituminous coal combustion under low oxygen atmosphere by TG–FTIR

The recirculation of boiler tail gas with a low oxygen concentration can reduce NO_x emissions. Experiments on bitumite combustion were carried out using simultaneous TG/FTIR dynamic runs with different atmospheric compositions, 2%, 6%, 10%, and 12% O₂. Reducing oxygen concentrations led to the burnout temperature shifting to higher temperature and coal combustion becoming more challenging. The reducing gas (CO, CH₄) emissions were abundant between 330 °C and 690 °C. However, along with the reduction in oxygen, CH₄ intensity increased, while the CO precipitation peak lowered. Kinetic parameters were defined using the Coats-Redfern model. According to the data obtained, bitumite combustion activation energy increased as oxygen concentration increased.     

Hydrogen production from methanol reforming in microwave “tornado”-type plasma

A microwave (2.45 GHz) “tornado”-type plasma with a high-speed tangential gas injection (swirl) at atmospheric pressure conditions has been applied for methanol reforming. The vortex gas flow “detaches” the hot plasma core from the wall and stable operation of the plasma source has been achieved. The hydrogen production rate dependence on the partial methanol flux has been investigated both in Ar and Ar + water plasma environments. Hydrogen, carbon oxide and carbon dioxide are the main decomposition products. Mass and FT-IR spectroscopy have been used to detect the species in the outlet gas stream. It has been found that the hydrogen production rate increases by nearly a factor of 1.5 when water is added into the plasma. Higher energetic hydrogen mass yield is achieved when compared with the results obtained under laminar gas flow conditions. Practically 100% methanol conversion rate has been achieved. Moreover, optical emission spectroscopy has been applied to determine the gas temperature, the electron density and the radiative species present in the plasma. A theoretical model based on a set of equations describing the chemical kinetics and the gas thermal balance equation has been developed. The theoretical results on the decomposition products agree well with the experimental ones and confirm that microwave plasma decomposition of methanol is a temperature dependent process. The results clearly show that this type of plasma is an efficient tool for hydrogen production.     

Inverse Identification of Thermal Properties of Charring Ablators

The modified Levenberg-Marquardt method is used for simultaneous estimation of decomposition kinetic coefficients and temperature-dependent thermophysical properties of charring ablators with a moving boundary over a wide temperature range. No prior information is used for the functional forms of the unknown thermal conductivity and specific heat. The procedure used differs from the traditional one in that it does not require prescribed time-dependent surface heat flux, recession rate, and pyrolysis gas mass flow rate. These time-dependent quantities may recover during an iterative procedure. The measured temperatures are simulated numerically by the Charring material ablation code, which accounts for unsteady ablation. The method can determine unknown parameters in an efficient manner with reasonable accuracy, without exact advance knowledge about the net surface heat flux, surface recession, and gas flux through the material.     

A combustion concept for oxyfuel processes with low recirculation rate – Experimental validation

Oxyfuel combustion is a technology for Carbon Capture & Storage from coal fired power plants. One drawback is the large necessary amount of recirculation of cold flue gases into the combustion chamber to avoid inadmissible high flame temperatures. The new concept of Controlled Staging with Non-stoichiometric Burners (CSNB) makes a reduction of the recirculation rate possible without inadmissible high flame temperatures. This reduction promises more compact boiler designs. We present in this paper experiments with the new combustion concept in a 3 × 70 kW natural gas combustion test rig with dry flue gas recirculation of 50% of the cold flue gases. The new concept was compared to a reference air combustion case and a reference oxyfuel combustion case with recirculation of 70% of the cold flue gases. FTIR emission spectroscopy measurements allowed the estimation of spectral radiative heat fluxes in the 2–5.5 μm range. The mixing of the gases in the furnace was good as the burnout and the emissions were comparable to the reference cases. The flame temperatures of the CSNB case could be controlled by the burner operation stoichiometry and were also similar to the reference cases. The heat flux in the furnace through radiation to the wall was higher compared to the oxyfuel reference case. This is an effect of the lowered recirculation rate as the mass flow out of the furnace and therefore the sensible heat leaving the furnace decreases. The higher oxygen consumption with lower recirculation rate could be compensated by a lower furnace stoichiometry. This was possible due to better burnout with increased oxygen concentrations in the burner. The results prove that a reduction of the flue gas recirculation rate in oxyfuel natural gas combustion from 70% down to 50% is possible while avoiding inadmissible high flame temperatures with the concept of Controlled Staging with Non-stoichiometric Burners.