Fe2O3改性电石渣高温固硫性能的研究

利用工业废弃物电石渣,经适当预处理,并掺入适量的Fe2O3对电石渣进行改性,配制成新型复合固硫剂。在高温条件下进行了固硫实验,达到了较为理想的固硫效果。研究了影响改性电石渣高温固硫效果的因素,分析了该改性电石渣的固硫机理。结果表明,改性电石渣高温固硫的适宜条件为:煤燃烧温度1200℃、Ca/S=2.2、改性电石渣的粒径为100目。在该条件下,对实验用烟煤(含硫量2.92%)燃烧20min,其高温固硫率高达88.5%,较相同条件下的普通钙基固硫剂的固硫率提高30%以上。     

氧化铝厂赤泥剂的固硫反应动力学特性研究

采用热分析法研究了山东铝业公司赤泥和石灰石固硫反应过程,利用等效粒子模型计算分析了其固硫反应动力学参数,并在此基础上利用压汞仪、SEM分析了赤泥煅烧前后的微观结构,探讨了赤泥固硫机理,为利用氧化铝生产中排放的大量赤泥代替石灰石用作燃煤固硫剂提供了理论依据.结果表明,赤泥的钙利用率是相同条件下石灰石的2～3倍,赤泥煅烧后较石灰石具有更多的中孔和较大的比表面积,可提高化学反应速度和反应深度;另外,赤泥中较多的三氧化二铁和碱金属盐也可提高赤泥固硫反应速率常数和有效扩散系数,但温度过高会降低固体熔点而易导致烧结,削弱其固硫活性.     

型煤固硫剂固硫特性的研究

利用石灰石，生石灰，电石渣，造纸废渣和赤泥作为型煤固硫剂，在燃烧温度为３００￣１０５０℃，钙硫比值为０．８９￣６．５３的范围内，对其燃烧固硫特性进行了试验研究，分别得到最佳固硫温度及加入量范围。试验证明，在模拟工业链条炉温度特性下，７种复合固硫剂的固硫效率比纯钙基固硫剂提高１２％￣２７％。     

CFB锅炉低氮燃烧对炉内固硫影响研究进展

随着火电厂烟气污染物排放标准的日益严格,循环流化床(CFB)锅炉多采用低氮燃烧技术在燃烧阶段降低NO_x的生成,但低氮燃烧应用会使炉内局部气氛,尤其是密相区的氧含量降低1%～4%,CO等还原性气氛增加1%～2%。固硫反应在不同氧浓度及还原性气氛条件下会表现出不同的反应路径,从而影响整个固硫反应速率和不同固硫产物的生成,导致最终固硫率的不同。因此CFB锅炉中引入低氮燃烧条件后会对炉内钙基固硫过程产生一定的影响。为了明晰低氮燃烧条件对CFB炉内钙基固硫反应的影响,保证燃烧中同时降低SO_2和NO_x的排放浓度,实现CFB锅炉中低氮燃烧技术与钙基固硫技术的耦合,综述了低氮燃烧反应条件对CFB锅炉炉内钙基固硫过程影响的研究现状,分别阐述了整个固硫过程中低氮还原性气氛及氧化-还原交变气氛条件对固硫剂煅烧、固硫剂固硫及固硫产物的分解转化3个不同反应阶段的影响。结果表明:CO_2浓度变化对CaCO_3煅烧影响较大且研究较多,气氛中CO_2的分压会直接减弱煅烧反应进行的程度;O_2和CO浓度变化对CaCO_3煅烧的影响未见报告,但从理论上推断影响较小,仍需进一步试验证明。在低氮燃烧形成的氧化-还原交变气氛下,炉内固硫反应过程变得复杂。氧气消失后,固硫率会降低20%左右,随着还原性气氛中CO含量的增加,固硫率还会进一步降低;随着CO等还原性气氛的增强,固硫产物CaSO_4稳定性降低,分解温度降低,CaS稳定性增强。但氧化、还原交变气氛下固硫产物的转化机制研究表明,当形成以CaS为内核,CaSO_4为外壳的固硫产物时,钙利用率和固硫效率会有所提高。可见,低氮燃烧气氛对硫化反应的影响具有不确定性。由于硫化反应的复杂性和固硫产物的不稳定性,目前尚无明确的针对不同固硫剂与反应温度和反应气氛的最佳匹配结果。因此,提出需进一步探究石灰石、电石渣等钙基固硫剂在不同氧浓度气氛及不同程度还原性气氛条件下的固硫反应机制,明确低氮燃烧条件对钙基固硫过程的影响,最终获得CFB锅炉低氮燃烧与炉内钙基固硫两者有机结合的优化反应条件,为实际生产提供可靠的理论依据。     

电石水解制备复合钙基吸附剂及其循环吸附CO2的特性

利用电石水解制乙炔工艺制备新型电石渣CaO/Ca12Al14O33复合钙基吸附剂,考察了Ca12Al14O33含量、碳酸化和煅烧再生温度对CaO转化率和多循环吸附CO2的影响,并与分析纯CaCO3和传统电石渣进行了比较,对其表面形貌、比表面积和孔结构进行了分析. 结果表明,新型复合钙基吸附剂在多循环煅烧/碳酸化过程中具有较好的多循环吸附CO2的性能. Ca12Al14O33有效减缓了吸附剂烧结现象. 20次循环后,自制电石渣吸附剂的CaO转化率仍保持在48%以上.     

循环流化床锅炉固硫剂的研究

研制开发了一种适合于循环流化床燃煤锅炉的固硫剂,以熟石灰[Ca(OH)2]和石灰石(CaCO3)混合作为主固硫剂,蛭石、珍珠岩和Na2CO3作为添加剂.并进行燃煤固硫试验,对其加入量、加入方式和燃烧温度进行了研究.结果表明,当Ca/S=2.25时,加入蛭石(9%蛭石/钙基)、珍珠岩(17%珍珠岩/钙基),并用少量Na2CO3调质,分别可以达到86.4%、84.8%的固硫率.     

利用固体废物研制高温固硫剂

通过分析高温固硫剂的固硫机理,以工业废弃物电石渣为钙基脱硫剂,盐泥为添加剂,研制高温固硫剂,考察了盐泥添加剂的词质效果及合理配比.结果表明,盐泥添加剂能够提高钙基固硫剂固硫率,其合理配比为电石渣与盐泥的质量比为8:1.通过SEM分析发现,调质改善了固硫剂颗粒的孔隙分布,提高了固硫剂的固硫性能.     

盐泥对钙基固硫剂促进作用的研究

以固体废弃物电石渣为钙基固硫剂,工业废弃物盐泥为添加剂进行脱硫实验。实验结果表明,盐泥添加剂能够提高钙基固硫剂的固硫率,其合理配比为电石渣与盐泥的质量比为8:1,固硫率由27.55%提高到45.73%。通过SEM分析发现,盐泥使固硫剂颗粒的表面微观形貌发生改变。同时研究也发现,盐泥中的主要成分不仅可以改变钙基固硫剂的微观结构,同时也有固硫及提高固硫产物高温稳定性的作用。     

天然矿物制备固硫剂的实验研究

利用熟石灰[Ca(OH)2]和石灰石(CaCO3)混合作为主固硫剂,蛭石、珍珠岩和Na2CO3作为添加剂,研制了一种适合于循环流化床燃煤锅炉的固硫剂,并进行了燃煤固硫试验,对其加入量、加入方式进行了研究.结果表明,Ca/S=2.25时,加入蛭石(11%蛭石/钙基)、珍珠岩(22%珍珠岩/钙基),并用少量Na2CO3调质,分别可以达到85%、84%的固硫率.     

循环流化床锅炉处理电石渣的探讨

乙炔法生产聚氯乙烯树脂过程中所产生的电石渣,其主要成份是 Ca(OH)_2,脱水后为 CaO,年产10,000t 聚氯乙烯便有2.6t/h 干基电石渣产生。循环流化床锅炉可采用炉内脱硫,最常用的脱硫剂为石灰或石灰石。S+O_2→SO_2↑CaO+SO_2+(1)/(2)O_2→CaSO_4每台35t/h 循环流化床锅炉耗煤6000kg     

电石渣用于循环流化床锅炉脱硫工艺的探讨

简要介绍了热电厂循环流化床锅炉运行现状，针对电石渣脱硫工艺进行了试验与分析，论证了电石渣应用于流化床锅炉脱硫的可行性。     

电石渣在燃煤电厂脱硫工艺中的应用研究进展

近年来,电石渣在燃煤电厂干法脱硫工艺的应用中取得了较多进展,但在湿法脱硫的应用中仍存在消溶特性差、亚硫酸钙氧化率低、石膏脱水困难等诸多问题,导致其难以大规模推广。本文从电石渣的理化性质出发,分析了孔隙结构、反应温度、Ca/S摩尔比对脱硫效率的影响,并探讨了电石渣作为脱硫剂对循环流化床锅炉效率及运行的影响,结合电石渣的消溶特性、浆液氧化特性及石膏脱水特性,分析了电石渣在湿法脱硫工艺应用中存在的问题,提出了一种以电石渣为原料,利用燃煤机组再生水深度处理系统生产石灰石浆液的工艺路线,并在2×660MW超超临界燃煤机组再生水深度处理系统中进行了可行性试验,当Ca(OH)₂纯度≥95%时,合理的污泥掺配比例区间为50%~70%,所产石膏达到了二级石膏的品质要求。     

Characterization of the reactivity of limestones with SO2 in a fluidized bed reactor

The reaction between SO₂ and calcined limestone particles has been studied in a fluidized bed combustor. Measurements of sorbent reactivity with SO₂ were made for small batches of limestone injected into the combustor. Simultaneous continuous combustion of bituminous coal provided conditions like those of a boiler for study of the sulphation reaction. A semi-empirical rate model of the CaO-SO₂ reaction has been developed. External mass transfer of SO₂, diffusion within the particles and chemical reaction are taken into account. The limestone reactivity with SO₂ is characterized by two parameters which are dependent on the temperature and sorbent particle size. A model for predicting the limestone requirements in a fluidized bed boiler has been developed. Parameters from the batch experiments are included. The predictions for sulfur retention agree with the experimental results. In addition, effects of operating conditions (gas velocity, recycle, limestone particle size) on the retention of SO₂ were simulated using the model.     

石灰石在燃煤流化床中固硫的数学模拟进展

石灰石在燃煤流化床中的固硫属于非催化气－固反应，其复杂性在于它是由反应气体在氧化钙颗粒孔内扩散、反应气体在产物层内扩散以及反应气体和氧化钙进行表面化学反应等三个过程的耦合，而且固体反应物的结构随着反应进行而变化。本文评述了固硫过程模拟工作的历史发展及最新趋势，并基于大量的实验事实和偏微分方程数值解的可能性，提出在建立模型时应考虑石灰石中惰性物含量和固硫反应热的影响。     

Assessment of ettringite from hydrated FBC residues as a sorbent for fluidized bed desulphurization

The performance of synthetic ettringite as a sorbent in fluidized bed desulphurization has been assessed and compared with that of a commercial limestone. Experiments have been carried out in a bench scale fluidized bed reactor under simulated desulphurizing (steadily oxidizing) combustion conditions. Sorbent performance has been characterized in terms of desulphurization rate, maximum sulphur uptake and attrition propensity. Fluidized bed sulphation experiments have been complemented by microstructural characterization of solid samples, accomplished via X-ray diffraction analysis, scanning electron microscopy and sulphur mapping of cross-sections of particles embedded in epoxy resin.

Experimental results show that both the rate and the maximum extent of sulphur uptake by ettringite significantly exceed those of the limestone. Maximum degree of free calcium utilization is 0.58 for ettringite compared with 0.27 for the limestone. Sulphation tests also indicate that attrition propensity of ettringite is larger than that correspondingly observed for the limestone. Microstructural characterization indicates that sulphation of ettringite takes place evenly throughout the particle cross-section, whereas sulphation of limestone mostly conforms to a core-shell pattern.

Along a parallel pathway, the rate and yield of ettringite formation by hydration of fly ash from a utility fluidized bed boiler have been assessed. Formation of ettringite in these experiments appears to be quantitative upon curing of ash at 70 °C for times up to 4 days.     

Sulfur dioxide release in fluidized bed combustion of Jorban oil shale

Due to high concentrations of sulfur and carbonates in Jordan oil shale, it was anticipated that the deposits would be a suitable burning fuel in an atmospheric fluidized bed system. The SO₂, capture by calcium oxide and calcined dolomite in spent shale prompted this experimental program to verify spent shale reactivity and SO₂ retention. Concentrations of SO₂, in effluents were analyzed vs. time in a fluidized bed material of silica sand, pure limestone rock (99.6% carbonates) and spent shale. The SO₂, release was studied in batch tests for each bed material. The effect of particle size in spent shale FBC was tested.Some model sulfur containing compounds were impregnated on limestone carrier solids and combusted to give time-release data. A sample of pyrite was charged to the bed of limestone sand in order to study its sulfur release and compare the data. A component balance was attempted to trace sulfur in the various bed materials.     

新型钡基高温燃烧固硫剂的研究与应用

引　言燃烧脱硫技术是在高温燃烧过程中将煤中的硫转化为硫酸盐或硫化物 ,因而其固硫率与硫酸盐或硫化物的热力学形成过程密切相关 .据文献报道 ,ＣａＳＯ3和ＣａＳＯ4 分别在 10 0 4℃[1] 和 1195～ 12 14℃[2 ] 就已开始分解 .纯ＣａＳＯ4 在 12 5 0℃高温下的分解率为 85 % .纯ＢａＳＯ4 的分解温度为 15 80℃[3] ,大大高于ＣａＳＯ4 ,显示较高的热稳定性 .根据元素周期表递变规律 ,位于第 6周期的Ｂａ较位Ｆｉｇ .1　Ｓｃｈｅｍａｔｉｃｏｆｉｎｔｅｌｌｉｇｅｎｔｓｕｌｆｕｒｄｅｔｅｒｍｉｎａｔｉｏｎ1—ｍａｉｎｆｒａｍｅｏｆｉｎ…     

Some implications of co-combustion of biomass and coal in a fluidized bed boiler

Laboratory combustion experiments were conducted to clarify some implications of co-firing coal with hog fuel and sludge in a power boiler. Combustion tests in a fixed bed stainless steel reactor at four temperatures (675, 725, 775, and 825 °C) under conditions simulating different moisture contents of hog-sludge blends indicated no problems with ignition. Burn-out of the coal reached 88–99%. However, the burn-out was very sensitive to the excess air, especially when co-firing wet hog fuel. Co-firing with coal will lead to higher sulfur dioxide emissions. Sulfation experiments were conducted in a fixed bed quartz reactor for five limestone particle size ranges (90–150 μm, 212–300 μm, 425–595 μm, 850–1000 μm, 2.0–3.4 mm) at the same temperatures as the combustion tests, with steam added to simulate the variation in the moisture content of the fuel mixture. The tests showed that the capacity of limestone to capture sulfur depends on temperature and particle size. The highest Ca utilization of the limestone was 51% (for the smallest particle size, at 825 °C). At 825 and 775 °C, the sulfur capture capacity of the limestone decreased significantly with increasing particle size, whereas at lower temperatures (725 and 675 °C), the Ca utilization was much less dependent on particle size. The sulfur capture capacity of the limestone was unaffected by the moisture content of the hog-sludge fuel. Calcium contained in the sand used as an inert in the power boiler may be capable of capturing small amounts of sulfur.