富氧气氛下钙基固硫剂固硫的热力学和动力学分析

煤燃烧过程中生成NO_x和SO_2,随其任意排放,将增大环境污染,在煤燃烧中用固硫剂固硫是一种可行的方法。笔者从热力学角度分析了煤燃烧中钙基固硫剂吸收二氧化硫生成硫酸钙反应的各种影响因素,从动力学角度分析了硫酸钙的分解特性,探讨了在富氧条件下,降低烟气中NO_x的含量,提高钙基固硫剂固硫率的可能性。研究发现高温不利于固硫,但富氧则能提高固硫率。     

工业洁净型煤固硫性能研究及其链条炉应用

以普通烟煤(长焰煤)为原料煤,考察了固硫剂的引入以及固硫添加剂的添加对烟煤固硫率的影响,并通过TG-MS初步分析了复合固硫剂的固硫机理。进一步压制得到了工业洁净型煤,并在0.5 t的工业链条锅炉上进行了试烧,进一步获得了型煤在实际燃烧过程中的污染物排放数据。研究结果表明,随着钙硫比的增大(1.5~2.5),钙基固硫剂固硫率逐渐提高,以SiO_2作为添加剂时,复合固硫剂固硫率效果较好,达到了69.1%。实际试烧效果也表明,加入添加剂后,型煤燃烧固硫减排效果明显,链条炉上SO_2减排量达到33.3%。     

钙基固硫产物动力学的实验研究

采用改进后的自动定硫仪,把硫酸钙直接放到高温区,测出不同温度下的硫酸钙分解率。应用物理化学中热力学函数,得到了固硫分解动力学方程,证明在一定温度范围内,温度变化对活化能的影响不太显著。     

高温固硫添加剂的选择

根据煤中硫在不同温度下的释放特性 ,对不同固硫剂、添加剂进行了试验研究。根据南桐煤中硫在低温区 ( 50 0℃左右 )显著释放的特性 ,选择了 Ca O作为固硫剂 ,试验表明该固硫剂固硫稳定性好 ,固硫率可达 70 %以上     

影响燃煤固硫因素的研究

从热力学基本方程推导并预测钙基固硫剂的固硫产物——硫酸钙在其所处的还原性气氛中分解的可能,通过实验验证CaSO_4在还原性气氛中分解温度与理论推导温度的一致性。得出结论,在低温时,燃煤所处的还原性气氛是导致固硫率降低的主要因素。     

改性粉煤灰对型煤固硫性能的影响研究

介绍了研究型煤固硫性能的实验流程和方法,通过在钙基型煤中添加改性粉煤灰作为固硫添加剂,考察了改性粉煤灰对型煤固硫效果的影响。研究结果表明,钙基型煤添加改性粉煤灰后,型煤固硫率可达55.41%,活化粉煤灰在高温下可抑制硫酸盐的分解和SO_2释放;型煤固硫率随粉煤灰添加量的增加而升高,随燃烧温度的增加而降低,而燃烧时间对其影响不大。     

燃烧固硫反应的动力学和热力学及其影响固硫产物分解因素的研究

煤在高温条件下燃烧不利于固硫反应，并从热力学角度出发，得出了煤燃烧中钙基固硫剂反应自由能与温度的关系函数，由化学反应动力学得出院 硫酸钙分解反应的动力学方程及其相关参数，在还原性气氛中，从理论和实验上都证明了硫酸钙在较低温下会发生二次分解，理论分解温度与实际分解温度非常吻合，煤灰中氧化钙和三氧化二铝的存在，可以提高硫酸钙的分解温度同阳也给出了钙基固硫剂的应用条件。     

燃生物质固硫型煤热管式热风炉的设计开发

介绍了生物质固硫型煤的节能环保特点和成型加工工艺,讨论了生物质固硫型煤在炉膛内的燃烧过程及其在炉前的成型制作方法,分析研究了燃生物质固硫型煤热管式热风炉、热管式换热器、链条炉排与炉拱的结构型式,总结了该型热风炉烟气再循环系统的设计计算。     

生物质型煤固硫性能研究及经济性分析

对生物质型煤固硫机理进行了理论分析 ,通过实验研究了 Ca/S,固硫剂种类及型煤含硫量对固硫率的影响 .结果表明 ,固硫率随 Ca/S比增大而提高 ,Ca/S=1 .5～ 2范围内 ,固硫率趋于最大值 ,当 Ca/S比大于 2后 ,固硫率随 Ca/S增加的趋势显著变缓 ;在同一 Ca/S比下 ,Ca( OH) 2 的固硫效果最好 ,Ca O次之 ,Ca CO3 的固硫效果最差 ;型煤含硫 3%以下 ,固硫率与含硫量成正比 ,含硫量继续增加 ,固硫趋势不断减缓 .通过对生物质型煤固硫费用的分析 ,得出生物质型煤固硫技术是可行的 .     

以污泥为粘结剂的生物质型煤固硫试验研究

往污泥为粘结剂的型煤中加入固硫剂及生物质,通过实验分析了Ca/S及生物质的量对固硫率的影响,结果表明,固硫率随Ca/S比增大而增大,Ca/S达到2时,固硫率趋于最大值,当Ca/S比大于2后,固硫率提高不明显;同一Ca/S比下,加入生物质的型煤固硫率比不加入生物质的型煤固硫率要高,且生物质越多,固硫率越高。     

Effect of CaSO4 Pelletization Conditions on a Novel Process for Converting SO2 to Elemental Sulfur by Reaction Cycles Involving CaSO4/CaS – Part II: Reduction of SO2 with CaS

A new process for converting sulfur dioxide to elemental sulfur by a cyclic process involving calcium sulfide and calcium sulfate without generating secondary pollutants, developed at the University of Utah, was described in Part I of this series. In this process, sulfur dioxide is reacted with calcium sulfide to produce elemental sulfur and calcium sulfate; the latter is reduced by hydrogen to regenerate calcium sulfide. Here, in Part II, the effects of different pelletization conditions for the initial reactant calcium sulfate on the reactivity of CaS pellets produced from calcium sulfate pellets toward sulfur dioxide were studied. Experiments were performed to investigate the effects of temperature in the range 1023–1173 K, pellet size, cycle repetition, and water vapor or carbon dioxide content in the sulfur dioxide stream. The binder amount and the presence of nickel catalyst did not significantly affect the reaction rate.     

Simulations and process analysis of the carbonation–calcination reaction process with intermediate hydration

Several technologies are currently being developed to separate carbon dioxide from large point sources, such as coal-fired power plants. An emerging technology that shows great potential is a calcium oxide–calcium carbonate cycle. A major drawback is the calcium carbonate decreases in reactivity over multiple cycles. The Ohio State University demonstrated in 2008 the first carbonation–calcination reaction (CCR) process that includes intermediate hydration for sorbent regeneration and its feasibility over multiple cycles at the 120 kW_th scale with actual flue gas from coal combustion. The CCR Process utilizes a calcium-based sorbent to react with the carbon dioxide and sulfur dioxide in a flue gas stream to form calcium carbonate and calcium sulfate, respectively. The carbon dioxide is subsequently released from the calcium carbonate to produce a high-purity, sequestration-ready carbon dioxide stream while regenerating the calcium oxide sorbent. The sulfur dioxide is fixated as calcium sulfate and removed through a purge stream. An intermediate hydration step restores reactivity to the calcium oxide sorbent. Process analysis from computer simulations shows the CCR Process to be highly effective and efficient in removing both carbon dioxide and sulfur dioxide at low energy penalties under realistic conditions. A 20–22% decrease in electricity generation efficiency with the CCR Process is expected, compared with amine scrubbing around 27% and oxy-combustion around 25% energy penalty. A 25–28% increase in thermal energy with the CCR Process is expected to maintain a constant electrical output. Further, the CCR Process consumes half the oxygen necessary for an oxy-combustion plant and 25% less steam necessary for amine scrubbing.     

芒硝制纯碱和硫酸新工艺探讨

我国芒硝储量世界第一,大部分位于欠发达的西部地区,芒硝还是许多工业过程的副产物,大多含有环境污染物.芒硝本身利用价值低,市场容量小,开发新的利用途径具有重要意义.提出了一种芒硝制纯碱和硫酸的新工艺,它是以氧化钙和重铬酸钠水溶液为转化介质,硫酸钠先和氧化钙在重铬酸钠水溶液中反应,得到硫酸钙沉淀和铬酸钠水溶液,前者高温还原分解再生氧化钙,同时得到二氧化硫和二氧化碳,二氧化硫经转化吸收得硫酸;后者和二氧化碳反应再生重铬酸钠水溶液,同时得到碳酸氢钠沉淀,碳酸氢钠经脱铬处理制得纯碱.该工艺借鉴了工业上成熟的石膏分解制硫酸技术和铬酸钠碳化制重铬酸钠技术,具有成本低、腐蚀轻、无废物排放等特点,有望为我国丰富的芒硝资源开辟新的应用途径.     

石灰法脱硫后石灰渣中硫含量分析

把石灰粉喷入烟气中脱硫,脱硫后石灰渣中硫绝大部分以亚硫酸钙的形式存在,同时含有硫酸钙,能准确测定石灰渣中硫含量,确定脱硫效率对工艺操作者起着指导生产的作用。有了准确的数据,能使工艺操作人员根据数据进行调整,保证二氧化硫的去除率,达到环保设施的要求。采用燃烧碘量法测定石灰渣中硫含量,能够测量0.1%~20%范围的硫含量,是现有检测方法中综合成本最低的一种方法。操作简单,完全自动化,节省成本,分析时间短、分析过程减少了许多危险因素。     

Dynamic thermogravimetric studies on the effect of boric oxide on a coke and a char

Blast furnace production of zinc and lead requires metallurgical cokes of low reactivity. Boric oxide is known to act as a negative catalyst for the oxidation of coke. The present work investigates the effect of boric oxide on the reactivity of Nantgarw coke and Australian brown coal char towards air and carbon dioxide using simultaneous thermogravimetric/differential thermal analysis. The effect of heating rate, gas flow rate and particle size on the oxidations has been investigated.     

Effect of CaSO4 Pelletization Conditions on a Novel Process for Converting SO2 to Elemental Sulfur by Reaction Cycles involving CaSO4/CaS – Part I. CaSO4 Pellet Strength and Reducibility by Hydrogen

A new process for converting sulfur dioxide to elemental sulfur by reaction cycles involving calcium sulfide and calcium sulfate without generating secondary pollutants was developed at the University of Utah. In this process, sulfur dioxide is reacted with calcium sulfide to produce elemental sulfur and calcium sulfate. The latter is reduced by hydrogen to regenerate calcium sulfide. In the present work, the effects of different pelletization conditions for the initial reactant calcium sulfate on the strength and reactivity of the pellets were determined. These pelletization conditions included the type, amount, and impregnation method of catalyst, the binder amount, and sintering. The pellets with the best properties were then reduced with hydrogen in the temperature range 973 to 1173 K, while measuring the kinetics, over several cycles of the two‐step process. Nickel‐catalyzed and fired pellets produced by the use of molasses or cement as a binder showed the highest compressive strength as well as good reactivity during the cyclic tests. The binder amount did not significantly affect the reaction rate.     

硫磺流化法还原钛白石膏工艺模拟研究

利用硫磺、碳等还原硫酸法钛白粉生产副产物钛白石膏是处理钛白石膏堆放问题的方法之一。针对硫磺在回转窑分解钛白石膏制硫酸和氧化钙的过程存在时间长、硫磺用量大、硫化钙产量不高等问题,提出了以钛白石膏为原料利用酸浸法去除铁杂质后,利用硫磺为还原剂将石膏在气固竖式反应器中煅烧生成硫化钙和二氧化硫,前者再与硫酸钙煅烧制得氧化钙和二氧化硫,得到的氧化钙可以中和废酸和废水,产生的二氧化硫用来制硫酸的方法。先利用反应热力学计算软件HSC分析确定实验方案,分别在流态化实验（800 ℃,保温40 min）和煅烧实验（1 100℃,保温1.5 h）后得到硫化钙转化率与氧化钙纯度均达到90%左右。再利用Aspen软件模拟了工艺流程,模拟出二氧化硫体积分数可达12.09%,满足制硫酸的需求。硫酸生产成本估算为263.9元/t,具有较大的市场前景。     

Thermal transport and chemical conversion in single reacting sorbent particles

The effects of particle size and carbon dioxide concentration on chemical conversion in engineered spherical particles undergoing calcium oxide looping are investigated. Particles are thermochemically cycled in a furnace under different carbon dioxide concentrations. Changes in composition due to chemical reactions are measured using thermogravimetric analysis. Gas composition at the furnace exit is evaluated with mass spectroscopy. A numerical model of thermal transport phenomena developed previously is adapted to match the physical system investigated in the present study. The model is used to elucidate effects of reacting medium characteristics on particle temperature and reaction extent. Experimental and numerical results show that (1) an increase in particle size results in a decrease in carbonation extent, and (2) the carbonation step consists of fast and slow reaction regimes. The reaction rates in the fast and slow carbonation regimes increase with increasing carbon dioxide concentration. The effect of carbon dioxide concentration and the distinction between the fast and slow regimes become more pronounced with increasing particle size.     

钛白粉厂硫酸亚铁资源综合利用实验研究

钛白粉生产过程中硫酸亚铁是其主要的副产品,硫酸亚铁的产生量大,回收利用率低成了制约钛白粉生产的"瓶颈"。文章目的通过采用投加一定量的氯化钙然后调节pH来回收铁的方法对钛白粉生产过程中的副产品硫酸亚铁进行综合利用的实验分析。通过研究发现:氯化钙与硫酸亚铁反应过程中在一定的搅拌强度反应一段时间后,氯化钙的最佳投加量为Ca2+与SO42-的摩尔比1.3;氢氧化钙的最佳投加量OH-与Fe2+物质的量之比2.4,能够将硫酸亚铁中的铁全部转化成氢氧化铁,其中氯化钙溶液在整个系统中循环利用。     

Sulfur speciation in granulated blast furnace slag: An X-ray absorption spectroscopic investigation

Sulfur speciation in a granulated blast furnace slag (GGBFS) was analyzed by X-ray absorption near edge structure spectroscopy (XANES) before and after activation by saturated calcium hydroxide and five normal sodium hydroxide solutions. The solution to GGBFS ratio was 0.4.XANES showed that sulfur in GGBFS existed mostly as sulfides (frozen in calcium polyhedra) with a minor amount as sulfate. A slowly-cooled blast furnace slag, in contrast, had most of the sulfide transformed to sulfate. After activation of GGBFS, more sulfate formed and crystalline sulfide phases became more apparent. More slag reacted at lower pH than at higher pH.