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1、湿式石灰石-石膏法烟气脱硫,设计方法及过程,湿法脱硫设计,1、物料平衡计算：建立物料平衡表烟气平衡脱硫剂（脱硫产物）平衡水平衡,烟气原始参数,确定关键参数,钙硫比脱硫效率液气比石膏品质石灰品质,脱硫剂的选取,脱硫剂矿源品位脱硫剂的物理化学特性：真实密度、堆积密度、粒径分布、空隙率、分形、比表面积、活性、吸硫特性影响脱硫剂吸硫特性的因素：水份、温度、浓度、脱硫剂物理特性,2、建立工艺流程图,与物料平衡表同时,3、关键控制回路,烟气量、烟气中二氧化硫浓度及钙硫比控制进浆量pH值调节,4、脱硫反应塔,上升速度停留时间液气比pH值循环浆液浓度液柱高度脱硫能力搅拌防腐蚀防堵塞,氧化曝气装置,循环氧化槽的
2、容量氧化空气的停留时间氧化空气的过量系数氧化空气的压力、温度循环浆液的pH值CaSO3的结晶与CaSO4结晶氧化曝气装置的防堵塞氧化曝气装置的防腐蚀,浆液喷射装置,浆液流量的调节喷嘴的特殊结构浆液管道的防腐蚀浆液管道的防堵、防垢,5、平面布置,烟气脱硫过程,设计计算,烟气平衡,燃煤/烟气组份,输入数据机组容量 300 MWel燃煤热值(Hu)20.600 kJ/kg全厂效率 41,3%含硫量 0,79%假定:1 kg 煤 8,5 Nm(wet)烟气含水量 7,2%,燃煤烟气组份,燃烧计算,燃煤烟气成分,水蒸汽密度,烟气密度 assumed dataDensity flue gas 1,35 k
3、g/Nm质量流量,燃煤烟气成分,化学过程输入数据SO2 removal efficiency 95%S proportion in coal 0,79%Coal 127 t/hS+O2=SO2Note atomic mass:S=32 g/molO=16 g/molCa=40 g/molC=12 g/molH=1 g/mol,燃煤烟气成分,SO2 production&removal,燃煤烟气成分,SO2-contentInput data assumed dataO2 content in dry gas 7%,燃煤烟气成分,SO2 content at 6%O2,燃煤烟气成分,吸收塔热动力
4、学/绝热饱和,假定电除尘器出口温度 138 CGGH出口温度 108 C干烟气中水含量计算,在h,x图上,108 C 和 0,046 kg/kg,dry的交点的焓 h=233 kJ/kg.沿等焓线到饱和线可得到饱和温度,吸收塔热动力学/绝热饱和,Thermodynamics for scrubber/adiabatic saturation,吸收塔出口净烟气,吸收塔热动力学/绝热饱和,烟气计算结果,Absorber INLET,Absorber OUTLET,液相平衡,13%wt,50%wt,3%wt,石灰石消耗/石膏产量,1 SO2+1 CaCO3+2 H2O+1/2 O2 CaSO4 2H
5、2O+CO2 Note molar mass:SO2=64 g/molCaCO3=100 g/molH2O=18 g/molCO2=44 g/molO2=32 g/mol CaSO42H2O=172 g/mol Example:A flue gas desulphurisation plant with 2 t/h SO2-emissions needs:and produces:,水平衡,废水(a)keep Cl-level 15 to 20 g/l(b)keep sulfate level 35 g/l(b)keep ash+inert level in absorber slurry 1
6、3%Waste water flow based on Cl-levelInput(assumption):Data from experience HCl-removal 98%,废水流量,水平衡,工艺水消耗Sum of:Water for flue gas saturation Waste waterMoisture gypsum+crystal waterDroplet emission(negligible),水平衡,石膏脱水,For the scrubbing and crystallization process in the absorber,the gypsum solid c
7、ontent is between 5 and 20%.Inputassumed data,石膏浆液的密度,石膏脱水,旋流器底流密度旋流器顶流密度,石膏脱水,石膏产量,石膏脱水,水力旋流器,4,7assumption related to 13%solids in the flow from the absorber,3%solids in the cyclone overflow and 50%solids in the cyclone underflow,石膏脱水,吸收塔来石膏浆液,石膏脱水,石膏脱水,水力旋流器顶流成分(假定)50%of solids is gypsum25%of sol
8、ids is ash25%of solids is limestone,石膏脱水,石灰石浆液供给,石灰石消耗石灰石浆液密度石灰石固体密度石灰石浆液质量流量,石灰石浆液密度石灰石浆液体积流量,石灰石浆液供给,浆池尺寸,浆液罐的停留时间 浆液罐体积,(假定),(假定),滤液箱尺寸,滤布冲洗水量石膏冲洗水量take 50%from gypsum mass flow(assumption)滤液量,滤液箱停留时间(假定)滤液箱容积,(assumption),滤液箱尺寸,吸收塔尺寸,烟气流量SO2浓度SO2-脱硫率液气比:L/G=12 l/Am at absorber outlet(假定),吸收塔循环浆液
9、流量及每泵的流量Absorber temperature=48 C喷淋层数(pumps)=3,吸收塔尺寸,吸收塔直径吸收塔烟气流速w=3,7 m/s(assumption)吸收塔循环区体积循环浆液停留时间 t=4,3 min(assumption),吸收塔尺寸,吸收塔循环浆液区高度Sump height11,9 mHeight till flue gas duct 1,5 mFlue gas duct height 4,0 mHeight to first spray bank(from flue gas duct)2,5 mSpraying banks:2x1,5 m 3,0 mHeight
10、 till mist eliminator 1,3 mHeight of two stage droplet separators 2,5 mHeight flue gas outlet duct 3,0 mSum29,7 mTotal absorber height:H=30 m,吸收塔尺寸,增压风机和循环泵的能耗,增压风机吸收塔压损(assumption)10 mbarGGH压损 12 mbar烟道压损 7 mbar总压损 29 mbarSpecific flue gas transport workFor booster fan with 85%effectiveness,功率消耗Pum
11、p efficiency=0,89Volume flow(pump)=5.300 m/hLiquid level=11,9 mGeod.height=1,5 m+4,0 m+2,5 m+1,5 m=9,5 mPressure at nozzles=10 m(1 bar)Pressure height pipes=3 msum=22,5 m,增压风机和循环泵的能耗,中间层泵的能耗三层泵的总能耗,增压风机和循环泵的能耗,烟道尺寸,净烟气烟道直径Flue gas velocity w=18 m/s(assumption)Saturated clean gas原烟气烟道直径,管道计算,1)石灰石浆液输
12、送管Particle size limestone=90%44 m d50 15 mConcentration30%total solids amountTransport velocity 6 x settling velocityNormallywtransport 2,5 m/sVolume flow suspension=8 m/h石灰石浆液输送管直径,石灰石浆液循环管直径Volume flow circulation2Vsuspension(Absorber),管道计算,2)石膏浆液管径Particle size gypsumd50=35 50 mTransport velocity
13、 6 x setting velocityNormally wtransport 2,5 m/s至旋流器石膏浆液管径,管道计算,氧化风计算,强制氧化SO2+H2O HSO3-+H+HSO3-+O2 SO42-+H+1 mol SO2 needs mol O21 kg SO2 needs 32:2/64 kg O2Stoichiometric factor for O2-absorption in absorber sump 2,5 specific weight O2:,O2体积:空气体积:,氧化风计算,氧化风压头Injection point in absorber:distance to
14、liquid level=6 m,氧化风计算,吸收塔搅拌器计算,Need of energy for agitating80 W/melAbsorber sump volume 865 mAgitator capacity Pel=865 m x 80 W/m=69 kWNumber of agitators 4能耗及搅拌器,石灰石粉仓计算,Capacity for limestone silo7 days(assumption)Maximum density1.400 kg/mNormal density1.000 kg/mLimestone consumption2,97 t/hStora
15、ge volume,石膏仓计算,Capacity for gypsum storage 5 days(assumption)Normal density 1.000 kg/mGypsum production 5,11 t/h dry 5,11/0,9=5,7 t/h wet(10%moisture)存储容积,真空带式脱水计算,过滤面积1 m for a gypsum production of 1 t/h dry(assumption)Gypsum production Filter area=5,1 m(no redundance)真空带式脱水机容量Install 2 filters wi
16、th each 70%of maximal capacity2 x 70%complete filter area 2 x 0,7 x 5,1 m=2 filters each 3,5 m,所需真空泵真空泵电耗A typical pressure drop is 0,3 bar absoluteThe energy needed for one cumicmeter of air is Eel=40 Wh/m(assumption)The electric power needed for one belt filter is Pel=1.050 m/h x 40 Wh/mPel=42 kW each filter,真空带式脱水计算,
