Konewar kwal a wuraren samar da wutar lantarki na haifar da datti, kamar kasa da tokar kuda, da iskar hayaki da ke fitarwa zuwa sararin samaniya. Ana buƙatar tsire-tsire da yawa don cire hayaƙin SOx daga iskar hayaƙi ta amfani da tsarin lalata iskar gas (FGD). Manyan fasahohin FGD guda uku da ake amfani da su a cikin Amurka sune goge-goge (85% na shigarwa), bushe bushe (12%), da bushewar allurar sorbent (3%). Wet goge yawanci cire fiye da 90% na SOx, idan aka kwatanta da busassun scrubbers, wanda ke cire 80%. Wannan labarin yana gabatar da na'urorin fasaha na zamani don magance ruwan datti da aka samar ta hanyar rigarTsarin FGD.
Rigar Tushen FGD
Rigar fasahar FGD suna da gama-gari sashin reactor da daskararrun dewatering. An yi amfani da na'urori iri-iri, da suka haɗa da cunkoso da hasumiya na tire, da venturi scrubbers, da kuma goge goge a cikin sashin reactor. Masu shayarwa suna kashe gas ɗin acid tare da slurry na alkaline na lemun tsami, sodium hydroxide, ko farar ƙasa. Don dalilai na tattalin arziki da yawa, sababbin masu gogewa suna amfani da slurry na farar ƙasa.
Lokacin da dutsen farar ƙasa ya amsa tare da SOx a cikin yanayin rage yanayin abin sha, SO 2 (babban ɓangaren SOx) ya zama sulfite, kuma ana samar da slurry mai arzikin calcium sulfite. Tun da farko tsarin FGD (wanda ake magana da shi azaman iskar oxygen da aka hana ko tsarin iskar oxygen da aka hana) ya samar da samfurin sinadari na sulfite. SabuwaTsarin FGDyi amfani da reactor oxidation wanda a cikinsa aka canza slurry sulfite zuwa calcium sulfate (gypsum); waɗannan ana kiran su azaman limestone tilasta oxidation (LSFO) FGD tsarin.
Tsarin LSFO FGD na zamani na yau da kullun yana amfani da ko dai mai ɗaukar hasumiya mai feshi tare da ingantacciyar iskar oxygenation a cikin tushe (Hoto 1) ko tsarin kumfa jet. A cikin kowane iskar gas yana shiga cikin slurry na dutse a ƙarƙashin yanayin anoxic; slurry din ya wuce zuwa wani injin motsa jiki ko yankin dauki, inda sulfite ke jujjuya sulfate, kuma gypsum yana hazo. Lokacin tsare na'ura mai aiki da karfin ruwa a cikin reactor oxidation kusan mintuna 20 ne.
1. Fesa layin farar ƙasa tilasta hadawan abu da iskar shaka (LSFO) FGD tsarin. A cikin slurry scrubber LSFO yana wucewa zuwa reactor, inda aka ƙara iska don tilasta iskar oxygen da sulfite zuwa sulfate. Wannan oxidation yana bayyana yana canza selenite zuwa selenate, yana haifar da matsalolin jiyya daga baya. Source: CH2M Hill
Waɗannan tsarin yawanci suna aiki tare da daskararru da aka dakatar daga 14% zuwa 18%. Daskararrun da aka dakatar sun ƙunshi daskararrun gypsum masu kyau kuma maras kyau, ash gardama, da kayan da ba su da ƙarfi waɗanda aka gabatar tare da dutsen farar ƙasa. Lokacin da daskararrun suka kai iyaka na sama, ana tsabtace slurry. Yawancin tsarin LSFO FGD suna amfani da rabuwa da daskararru na inji da tsarin dewatering don raba gypsum da sauran daskararru daga ruwan tsarkakewa (Hoto 2).
2. FGD tsaftace gypsum dewatering tsarin. A cikin tsarin gypsum dewatering na yau da kullun ana rarraba ɓangarorin da ke cikin tsaftar, ko kuma sun rabu, zuwa ɓangarorin da ba su da kyau da kyau. An raba ɓangarorin ƙaƙƙarfan a cikin ambaliya daga hydroclone don samar da ƙarancin ruwa wanda ya ƙunshi galibin manyan lu'ulu'u na gypsum (don yuwuwar siyarwa) waɗanda za'a iya lalata su zuwa ƙaramin ɗanɗano tare da tsarin cire ruwa mai bel. Source: CH2M Hill
Wasu tsarin FGD suna amfani da kauri mai kauri ko daidaita tafkuna don rarraba daskararru da dewatering, wasu kuma suna amfani da centrifuges ko rotary vacuum drum dewatering system, amma galibin sabbin tsarin suna amfani da hydroclones da vacuum belts. Wasu na iya amfani da hydroclones guda biyu a cikin jerin don ƙara haɓaka daskararru a cikin tsarin dewatering. Za a iya mayar da wani yanki na ambaliya na hydroclone zuwa tsarin FGD don rage kwararar ruwa.
Hakanan za'a iya ƙaddamar da tsarkakewa yayin da akwai tarin chlorides a cikin slurry na FGD, wanda ya wajaba ta iyakokin da aka sanya ta hanyar juriyar lalata kayan gini na tsarin FGD.
Halayen Wastewater FGD
Matsaloli da yawa suna shafar tsarin ruwa na FGD, kamar su gawayi da dutsen farar ƙasa, nau'in gogewa, da tsarin gypsum-dewatering da ake amfani da su. Coal yana ba da gudummawar gas na acidic - irin su chlorides, fluorides, da sulfate - da kuma karafa masu canzawa, ciki har da arsenic, mercury, selenium, boron, cadmium, da zinc. Dutsen farar ƙasa yana ba da gudummawar ƙarfe da aluminium (daga ma'adinan yumbu) zuwa ruwan sharar FGD. Dutsen farar ƙasa yawanci ana niƙa shi ne a cikin injin niƙa mai jika, kuma zaizayar ƙasa da lalata ƙwallo suna ba da gudummawar ƙarfe ga slurry na farar ƙasa. Clays yana ba da gudummawar tarar da ba ta dace ba, wanda yana ɗaya daga cikin dalilan da ake tsabtace ruwa daga goge.
Daga: Thomas E. Higgins, PhD, PE; A. Thomas Sandy, PE; da Sila W. Abubuwan da aka bayar, PE.
Imel:[email protected]
Lokacin aikawa: Agusta-04-2018