湿式石灰石-石膏法烟气脱硫设计方法及过程.ppt

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 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 = so2 note atomic mass: s = 32 g/mol o = 16 g/mol ca = 40 g/mol c = 12 g/mol h = 1 g/mol,燃煤烟气成分,so2 production & removal,燃煤烟气成分,so2-content input data assumed data 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,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 2h2o + co2 note molar mass: so2 = 64 g/mol caco3 = 100 g/mol h2o = 18 g/mol co2 = 44 g/mol o2 = 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 13 % waste water flow based on cl- level input (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 water 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 %. 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,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 gypsum 25 % of solids is ash 25 % 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 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 m sum 29,7 m total 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 mbar ggh压损 12 mbar 烟道压损 7 mbar 总压损 29 mbar specific 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 = 9,5 m pressure at nozzles = 10 m (1 bar) pressure height pipes = 3 m sum = 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 m d50 15 m concentration 30 % total solids amount 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 o2 1 kg so2 needs 32:2/64 kg o2 stoichiometric 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 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/h storage volume,石膏仓计算,capacity for gypsum storage 5 days (assumption) normal density 1.000 kg/m gypsum 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 with each 70 % of maximal capacity 2 x 70 % complete filter area 2 x 0,7 x 5,1 m =