高效燃煤固硫添加剂的研究与应用
重庆大学硕士学位论文
学生姓名：陈福寿指导教师：杜车副教授专 业：物理化学 学科门类：理学
重庆大学化学化工学院二OO八
年四月
Study on highly Performance Calcium-based
sulfur retention Additives
A Thesis Submitted to Chongqing University in Partial Fulfillment of the Requirement for the
Degree of Master of Science
by
Chen Fushou
Supervisor: Associate Professor Du Jun Major: Physical Chemistry
College of Chemistry &Chemical Engineering Chongqing University, chongqing, china
April, 2008
重庆大学硕士学位论文 中文摘要
摘要
我国的能源结构是以煤炭为主，煤炭燃烧以后排放SO2造成的大气污染已经成为一个相当严重的问题，对燃煤固硫问题进行深入研宄，控制SO2的排放已势在必行。在现有的脱硫技术中，干法钙基固硫技术工艺简单、脱硫成本低，特别适合生活燃煤、小型工业窑炉以及老锅炉的固硫改造。然而单一的钙基固硫剂钙利用率低，固硫效果有限，影响了该技术的发展，采用在钙基固硫剂中加入助剂制成复合固硫剂来提高固硫效率是一种较为经济可行的方法。
本文通过对三种单一物质和两种固体废弃物对钙基固硫剂的固硫促进效果的考察，发现碱金属盐以及稻草灰(RSA)都是很好的钙基固硫添加剂，相比而言，RSA/钙基复合固硫剂更适合民用燃煤固硫。考察了各工艺条件诸如RSA与CaC〇3 的配比、Ca/S摩尔比以及燃烧情况等对RSA/CaC〇3复合固硫剂固硫效果的影响，并利用RSA/CaC〇3复合固硫剂进行了现场的民用型煤固硫实验，还利用XRD对固硫灰渣的物相成分进行了分析。此外，还对钙基固硫剂进行调质处理，大大提高了其在高温阶段(1100 °C以上)的固硫效果。
实验结果表明：CaC〇3与RSA的最佳配比为10:1; Ca/S摩尔比最佳取值范围为1.5-2.5;复合固硫剂的最佳固硫温度为800C— 900C在固硫煤样中加入4% 的水分能够得到较佳的固硫效果；最佳空气流量为150ml/min。当Ca/S为2.0、空气流量150ml/min时，复合固硫剂在800C的固硫率达到70%以上。民用型煤固硫实验结果显示，本固硫剂对无烟煤和烟煤都有很好的固硫效果，固硫率高达90%。固硫灰渣XRD图谱显示在1000C以下，主要固硫产物为CaSO4，而1100C时固硫灰渣中有高温物相2Ca2Si〇4+CaS〇4的生成。通过对CaC〇3调质处理，1100C时钙基固硫剂的固硫率能够由16%左右增加到40%，1250C时的固硫率也能够达到 20%。XRD分析显示，煅烧熔融使粉煤灰得到了活化，而在1250C时固硫灰渣的XRD图谱中出现了3CaO.Al2〇3.CaS〇4的吸收峰。 关键词：钙基固硫剂，添加剂，民用型煤固硫，高温固硫，稻草灰
ABSTRACT
Coalisthemainenergyinchina5senergystructure. urgenttocontroltheemissionofSO2.
SO2fromcoalcombustionis
oneofthemajorairpollutants, leadingtoseriousenvironmentalpollution. Thus, itis
Amongallkindsofdesulphurizationtechnologies,
drycalcium-basedretentiontechniqueisthemostsuitableoneforcivilcoalcombustion, small-scaleindustrialfurnaceaswellasoldboilerduetoitssimpleprocessandlowcost.
I
重庆大学硕士学位论文 英文摘要
However, lowdesulfurizationefficiencyandlowutilizationratioofcalciumhave
dopingsomeadditivesintotheCa-basedabsorbent,
hasbeen
limitedthedevelopmentofthistechnologywhenusingcalcium-basedabsorbentalone. Aneweconomicmethod, developedtoresolvethisproblem.
Itwasfoundthatalkalimetalsaltsandricestrawash(RSA) calcium-basedabsorbentadditives,
threedifferentpurechemicaladditivesandtwodifferentsolidwastes. Ca/S,
combustionconditionswereinvestigated,
arebothappropriate
Comparedwith andcivilbriquette
byinvestigatingthedesulphurizationpromotingof
purechemicaladditives, RSAismoresuitableforciviliancoal. Theeffectofricestraw ashratio, experimentswerecarriedoutatthescene. alsoanalyzedbyXRD. Aceticacidandactivatedflyash
(FA),
〇
Thephasesofthesulfurretentionashwere andthesulfurretentionefficiencywasgreatly
Thecalcium-basedsulfurretentionabsorbentwastreatedby
improvedwhenthetemperatureisabove 1100 C.
TheresultsoftheexperimentshowthattheoptimizeprocessconditionsofRSA/
CaCO3sulfurretentionabsorbentareasfellow: massratioofCaCO3andstrawashis 10:1, theCa/Sratioisbetween
1.5-2.5,
thetemperatureisbetween
800C-900C,
the
amountofadditionalwateris4%, andtheairflowis 150 ml/min. Thesulfurretention rateofRSA/CaCO3isabove70%, WhenCa/S = 2.0, theairflowis 150 ml/minandthe temperatureis 800 C.
TheCivilbriquetteexperimentsresultsshowthat,
thesulfurretentionabsorbent
which
hasthehighersulfurretentionefficiencytobothanthraciteandbituminouscoal,
reachedto 90%. Thesulfurretentionrateincreasedfrom16% to40% at 1100 Cby acetate-qualityprocessingandactivatedFA; whenthetemperatureis 1250C, thesulfur ratereachedto 20%.
TheXRDpatternsindicatedthat, areCaSO4whentemperatureisbelow
〇
themainformofsulfurinthesulfurretentionash 1000C;
2Ca2SiO4.CaSO4isfoundwhenthe
sulfurretentiontemperatureis1100 C; theabsorptionpeaksof 3CaOAl2〇3.CaS〇4 are alsofoundWhenthetemperaturerisesto 1250^.
Keywords: Ca-basedabsorbent, Additive, Civilbriquette, High-temperaturesulfur
retention, Ricestrawash
II
重庆大学硕士学位论文
目录
目录
中文摘要 ....................................................................... I 英文摘要 ...................................................................... II 1绪论 ......................................................................... 1 1.1课题背景 ................................................................. 1
1.1.1能源结构 ............................................................ 1 1.1.2二氧化硫的排放污染现状 ............................................... 2 1.2我国二氧化硫排放控制对策 ................................................. 4 1.3燃煤二氧化硫控制技术现状 ................................................. 4
1.3.1赚前脱硫 ............................................................ 5 1.3.2燃烧中脱硫 ........................................................... 5 1.3.3燃烧后烟气脱硫(FGD) ................................................. 6 1.4钙基复合添加剂的研宄进展 ................................................. 7
1.4.1 Fe-S-Al类氧化物 ...................................................... 7 1.4.2碱金属和碱土金属化合物 ............................................... 8 1.4.3有机溶液的调质处理 ................................................... 9 1.5课题研宄内容 ............................................................ 10 2固硫原理 ................................................................... 12 2.1原煤中的硫的雜形态 ...................................................... 12 2.2单一的钙基固硫剂固硫机理 ................................................ 12 2.3钙基固硫添加剂的促进机理 ................................................ 14
2.3.1碱金属化合物的促进机理 .............................................. 14 2.3.2 Fe-Si-Al类氧化物促进机理 ............................................ 15 2.4固硫反应热力学 .......................................................... 15 2.5固硫反应动力学模型 ...................................................... 16 2.6钙基固硫剂固硫效果的影响因素 ............................................ 21 2.7钙基固硫剂存在的问题 .................................................... 21 3实验方法 ................................................................... 22 3.1药品及仪器 .............................................................. 22 3.2实验装置 ................................................................ 23 3.3燃煤释放的S〇2含量的测定 ............................................... 23
3.3.1溶剂的配制 .......................................................... 24
III