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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湿法脱硫设计1、物料平衡计算：建立物料平衡表、物料平衡计算：建立物料平衡表烟气平衡烟气平衡脱硫剂（脱硫产物）平衡脱硫剂（脱硫产物）平衡水平衡水平衡烟气原始参数烟气原始参数确定关键参数确定关键参数钙硫比钙硫比脱硫效率脱硫效率液气比液气比石膏品质石膏品质石灰品质石灰品质2、建立工艺流程图、建立工艺流程图与物料平衡表同时与物料平衡表同时3、关键控制回路、关键控制回路烟气量、烟气中二氧化硫浓烟气量、烟气中二氧化硫浓度及钙硫比控制进浆量度及钙硫比控制进浆量pH值调节值调节4、脱硫反应塔上升速度上升速度停留时间停留时间液气比液气比pHpH值值循环浆液浓度
2、循环浆液浓度液柱高度液柱高度脱硫能力脱硫能力搅拌搅拌防腐蚀防腐蚀防堵塞防堵塞氧化曝气装置循环氧化槽的容量循环氧化槽的容量氧化空气的停留时间氧化空气的停留时间氧化空气的过量系数氧化空气的过量系数氧化空气的压力、温度氧化空气的压力、温度循环浆液的循环浆液的pHpH值值CaSOCaSO3 3的结晶与的结晶与CaSOCaSO4 4结晶结晶氧化曝气装置的防堵塞氧化曝气装置的防堵塞氧化曝气装置的防腐蚀氧化曝气装置的防腐蚀浆液喷射装置浆液流量的调节浆液流量的调节喷嘴的特殊结构喷嘴的特殊结构浆液管道的防腐蚀浆液管道的防腐蚀浆液管道的防堵、防垢浆液管道的防堵、防垢5、平面布置、平面布置烟气脱硫过程设计计算烟气平
3、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 kg/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
4、 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
5、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 INLETAbsorber OUTLET液相平衡13% wt50% wt3% wt石灰石消耗/石膏产量1 SO2 + 1 CaCO3 + 2 H2O + 1/2 O2 CaSO4 2H2O + CO2 Note molar mass:SO2 = 64 g/molCaCO3 = 100 g/molH2O = 18 g/molCO2 = 44 g/molO2 = 32 g/mol CaSO42H2O =172
6、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 13 %Waste water flow based on Cl- levelInput (assumption):Data from experience HCl-removal 98 %
7、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Forthescrubbingandcrystallizationprocessintheabsorber,thegypsumsolidcontentisbetween5and20%.Input assumed 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水力旋流器From AbsorberTo
8、AbsorberTo Belt Filter4,7assumption 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AbsorberAbsorberHydrocycloneHydrocycloneunderflowunderflowHydrocycloneHydrocycloneoverflowoverflowBeltfilterBeltfilterFil
9、trateFiltrateMassflowMassflowsuspensionsuspension47.940kg/h10.200kg/h37.740kg/h5.670kg/hgypsumwet4.530kg/hMassflowMassflowGypsumdryGypsumdry6.232kg/h5.100kg/h1.132kg/h5.100kg/hMassflowMassflowWaterWater41.708kg/h5.100kg/h36.608kg/h570kg/hwateringypsum4.530kg/hVolumeflowVolumeflowsuspensionsuspension
10、44,4m/h7,3m/h37,1m/h石膏脱水水力旋流器顶流成分 (假定)50 % of solids is gypsum25 % of solids 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
11、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
12、first spray bank (from flue gas duct) 2,5 mSpraying banks: 2x1,5 m 3,0 mHeight 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总压损总压损 2
13、9 mbarSpecific flue gas transport workFor booster fan with 85 % effectiveness功率消耗Pump 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中间层泵的能耗的能
14、耗三层泵的总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
15、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 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
16、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 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
17、算Capacity for limestone silo7 days (assumption)Maximum density1.400 kg/mNormal density1.000 kg/mLimestone consumption2,97 t/hStorage 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
18、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 with 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
