Flue gas circulating fluidized bed desulfurization process
煙氣循環(huán)流化床脫硫工藝由吸收劑制備、吸收塔、脫硫灰再循環(huán)、除塵器及控制系統(tǒng)等部分組成。該工藝一般采用干態(tài)的消石灰粉作為吸收劑,也可采用其它對二氧化硫有吸收反應(yīng)能力的干粉或漿液作為吸收劑。
The flue gas circulating fluidized bed desulfurization process consists of absorbent preparation, absorption tower, desulfurization ash recycling, dust collector and control system. In this process, dry hydrated lime powder is generally used as absorbent, and other dry powder or slurry with absorption and reaction ability to sulfur dioxide can also be used as absorbent.
由鍋爐排出的未經(jīng)處理的煙氣從吸收塔(即流化床)底部進(jìn)入。吸收塔底部為一個(gè)文丘里裝置,煙氣流經(jīng)文丘里管后速度加快,并在此與很細(xì)的吸收劑粉末互相混合,顆粒之間、氣體與顆粒之間劇烈摩擦,形成流化床,在噴入均勻水霧降低煙溫的條件下,吸收劑與煙氣中的二氧化硫反應(yīng)生成CaSO3 和CaSO4。脫硫后攜帶大量固體顆粒的煙氣從吸收塔頂部排出,進(jìn)入再循環(huán)除塵器,被分離出來的顆粒經(jīng)中間灰倉返回吸收塔,由于固體顆粒反復(fù)循環(huán)達(dá)百次之多,故吸收劑利用率較高。
The untreated flue gas discharged from the boiler enters from the bottom of the absorption tower (i.e. fluidized bed). There is a venturi device at the bottom of the absorber. The flue gas accelerates after flowing through the venturi tube, and is mixed with very fine absorbent powder here. There is fierce friction between particles and between gas and particles to form a fluidized bed. Under the condition of spraying uniform water mist to reduce the flue gas temperature, the absorbent reacts with sulfur dioxide in the flue gas to form CaSO3 and CaSO4. After desulfurization, the flue gas carrying a large amount of solid particles is discharged from the top of the absorption tower and enters the recycling dust collector. The separated particles return to the absorption tower through the middle ash bin. Because the solid particles are recycled for hundreds of times, the utilization rate of absorbent is high.
此工藝所產(chǎn)生的副產(chǎn)物呈干粉狀,其化學(xué)成分與噴霧干燥法脫硫工藝類似,主要由飛灰、CaSO3、CaSO4和未反應(yīng)完的吸收劑Ca(OH)2等組成,適合作廢礦井回填、道路基礎(chǔ)等。
The by-product produced by this process is in the form of dry powder. Its chemical composition is similar to that of the spray drying desulfurization process. It is mainly composed of fly ash, CaSO3, CaSO4 and unreacted absorbent Ca (OH) 2. It is suitable for waste mine backfilling, road foundation, etc.
典型的煙氣循環(huán)流化床脫硫工藝,當(dāng)燃煤含硫量為2%左右,鈣硫比不大于1.3時(shí),脫硫率可達(dá)90%以上,排煙溫度約70℃。此工藝在國外目前應(yīng)用在10~20萬千瓦等級機(jī)組。由于其占地面積少,投資較省,尤其適合于老機(jī)組煙氣脫硫。
For typical flue gas circulating fluidized bed desulfurization process, when the sulfur content of coal is about 2% and the calcium sulfur ratio is not greater than 1.3, the desulfurization rate can reach more than 90% and the flue gas temperature is about 70 ℃. This process is currently used in 100000 ~ 200000 kW units abroad. Because of its small floor area and low investment, it is especially suitable for flue gas desulfurization of old units.
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