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
2、防堵塞,氧化曝气装置,循环氧化槽的容量 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,
3、烟气密度assumed data Density 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/h S + 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 dataassumed data
4、O2 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 C GGH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,Absorb
5、er 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 2H2O + 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,
6、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 %,废水流量,水平衡,工艺水消耗Sum of: Water for flue gas saturation Waste water Moisture gypsum + crystal wa
7、ter Droplet emission (negligible),水平衡,石膏脱水,For the scrubbing and crystallization process in the absorber, the gypsum solid content 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
8、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 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
9、 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Su
10、mp height 11,9 m Height till flue gas duct 1,5 m Flue gas duct height 4,0 m Height to first spray bank (from flue gas duct) 2,5 m Spraying banks: 2x1,5 m 3,0 m Height till mist eliminator 1,3 m Height of two stage droplet separators 2,5 m Height flue gas outlet duct 3,0 mSum 29,7 m Total absorber he
11、ight: 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 mbar GGH压损 12 mbar 烟道压损 7 mbar总压损 29 mbarSpecific flue gas transport work For booster fan with 85 % effectiveness,功率消耗Pump efficiency = 0,89 Volume flow (pump) = 5.300 m/h Liquid level = 11,9 m Geod. height = 1,5 m + 4,0 m + 2,5 m + 1,5 m =
12、 9,5 m Pressure 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) 石灰石浆液输送管 Particle size limestone =90 % 44 md50 15 m Concentration 30 % total solids amoun
13、t Transport velocity 6 x settling velocity Normally wtransport 2,5 m/s Volume 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 circulation 2Vsuspension (Absorber),管道计算,2) 石膏浆液管径 Particle size gypsum d50 = 35 50 m Transport velocity 6 x setting velocity Normally wtransport 2,5 m/s至旋流器石膏浆液管径,管
14、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 liquid level = 6 m,氧化风计算,吸收塔搅拌器计算,Need of energy
15、for agitating 80 W/mel Absorber sump volume 865 m Agitator capacity Pel = 865 m x 80 W/m = 69 kW Number of agitators 4能耗及搅拌器,石灰石粉仓计算,Capacity for limestone silo 7 days (assumption) Maximum density 1.400 kg/m Normal density 1.000 kg/m Limestone consumption 2,97 t/hStorage volume,石膏仓计算,Capacity for gy
16、psum storage 5 days (assumption) Normal density 1.000 kg/m Gypsum production 5,11 t/h dry5,11/0,9 = 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 with each 70 % of m
17、aximal capacity2 x 70 % complete filter area2 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 absolute The 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,
