Uhlelo Lokunciphisa Ukukhishwa Kwegesi Emanzini
Imboni yokuthumela izimpahla idlala indima ebalulekile ekuhwebeni komhlaba wonke ngenxa yekhono layo lokuthutha imithwalo emikhulu ngentengo ephumelelayo nge-ton-kilometer. Kodwa-ke, naphezu kwalokhu kusebenza kahle, imikhumbi nayo ingumthombo wokukhishwa kwamagesi okushisa umhlaba kanye nokungcola komoya okuthinta impilo yabantu kanye nemvelo. Ukukhishwa kwemikhumbi ngokuvamile kuvela ekushisweni kwamafutha ezinjini ezinkulu, ezinjinini ezisizayo, kanye nama-boiler. Ngakho-ke, ukusebenzisa uhlelo lokunciphisa ukukhishwa kwemikhumbi kuyisinyathelo esibalulekile sokuthobela imithetho yamazwe ngamazwe nokukhuthaza ukushintshela ekuthuthweni okusimeme kakhudlwana.
Imithombo kanye nezinhlobo zokukhishwa kwegesi okuvela emikhunjini
Ukukhishwa kwemikhumbi kungahlukaniswa ngezigaba ezimbili ezibanzi: ukukhishwa kwegesi ebamba ukushisa kanye nokungcola komoya okuvamile. Igesi ebamba ukushisa eyinhloko yi-carbon dioxide (CO₂), inani layo elilingana nokusetshenziswa kukaphethiloli. Okunye ukukhishwa kwegesi kuhlanganisa i-methane (CH₄) kanye ne-nitrous oxide (N₂O), ikakhulukazi uma kusetshenziswa uphethiloli othile nangaphansi kwezimo ezithile zokusha. Ukungcola komoya kuhlanganisa ama-sulfur oxide (SOx), ama-nitrogen oxide (NOx), ama-particulate matter (PM), i-black carbon, kanye nama-volatile organic compounds (VOCs).
Amafutha asolwandle endabuko, njengowoyela osindayo (i-HFO), ngokuvamile anokuqukethwe okuphezulu kwe-sulfur, okufaka isandla kakhulu ku-SOx kanye nezinto ezincane. I-NOx ithonywa kakhulu izinga lokushisa lokushisa kanye nomklamo wenjini. Ngakolunye uhlangothi, ukukhishwa kwe-CO₂ kuncike kakhulu emfunweni wamandla ophelele womkhumbi, okunqunywa isivinini, ukumelana nomkhumbi, izimo zolwandle, kanye nokusebenza kahle kokunyakaza.
Imithethonqubo Ekhuthaza Ukunciphisa Ukukhishwa Kwegesi
Imizamo yokunciphisa ukukhishwa kwegesi emikhunjini iqhutshwa kakhulu yimithethonqubo ye-IMO (International Maritime Organisation) ngokusebenzisa uhlaka lwe-MARPOL Annex VI. Lo mthethonqubo ulawula imikhawulo yesibabule kuphethiloli, imikhawulo ye-NOx esekelwe ku-Tier (Tier I, II, III), kanye nokusungulwa kwezindawo zokulawula ukukhishwa kwegesi ezifana ne-ECA (Emission Control Area). Ngaphezu kwalokho, i-IMO iphinde ikhuthaze ukunciphisa ukuqina kwegesi ngokusebenzisa amathuluzi afana ne-EEDI (Energy Efficiency Design Index) yemikhumbi emisha kanye ne-EEXI (Energy Efficiency Existing Ship Index) yemikhumbi ekhona, kanye nezindlela zokusebenza ezifana ne-CII (Carbon Intensity Indicator).
Le mithethonqubo idinga ukuthi abaqhubi bemikhumbi bangagcini nje ngokugxila ekuthobeleni imithetho kodwa futhi nasekunciphiseni ukukhishwa kwegesi njengendlela yokusebenzisa kahle izindleko isikhathi eside. Ukusetshenziswa kwamafutha ahlanzekile, ukusebenza kahle kobuchwepheshe okwandisiwe, kanye nokwenza ngcono ukusebenza kubalulekile ekunciphiseni kokubili ukusetshenziswa kukaphethiloli kanye nokukhishwa kwegesi.
Ubuchwepheshe Bokunciphisa i-SOx: Ama-Scrubbers kanye Namafutha Ane-Sulfur Ephansi
Kunezindlela ezimbili eziyinhloko zokunciphisa ukukhishwa kwe-SOx. Eyokuqala ukusetshenziswa kwamafutha ane-sulfur ephansi, njenge-Very Low Sulfur Fuel Oil (VLSFO) noma i-Marine Gas Oil (MGO). Lesi sixazululo silula kakhulu, sidinga ukulungiswa kokusebenza kuphela, kodwa singakhuphula izindleko zikaphethiloli futhi sidinga ukuphathwa ngokucophelela kwekhwalithi kaphethiloli.
Indlela yesibili ukufakwa kwe-scrubber (i-Exhaust Gas Cleaning System/EGCS), uhlelo "olugeza" igesi yokukhipha ukuze kususwe ama-sulfur oxides ngaphambi kokuba akhishwe emoyeni. Ama-scrubber eza ngezinhlobo eziningana, kufaka phakathi i-open-loop, i-closed-loop, kanye ne-hybrid. Inzuzo yama-scrubbers ukuthi avumela ukusetshenziswa kwe-HFO ngenkathi esahlangabezana nemikhawulo yokukhishwa kwe-SOx, kodwa adinga ukutshalwa kwezimali okukhulu kokuqala, isikhala sokufaka, ukusetshenziswa kwamandla okwengeziwe, kanye nokunaka imithetho yokuphathwa kwemfucuza kanye ne-port ngezinye izikhathi ekhawulela ukusetshenziswa kwezinhlelo ze-open-loop.
Ubuchwepheshe Bokunciphisa i-NOx: i-SCR ne-EGR
Ukuze kuncishiswe ukukhishwa kwe-NOx, izixazululo ezisetshenziswa kakhulu yi-Selective Catalytic Reduction (SCR) kanye ne-Exhaust Gas Recirculation (EGR). I-SCR isebenza ngokufaka i-urea noma i-ammonia emseleni wegesi yokukhipha umoya, bese idlula ku-catalyst, ivumela i-NOx ukuthi isabele futhi iguquke ibe yi-nitrogen (N₂) kanye nomhwamuko wamanzi (H₂O). Uhlelo lwe-SCR lunikeza izinga eliphezulu lokunciphisa i-NOx, ikakhulukazi ukuze kuhlangatshezwane nezindinganiso ze-IMO Tier III, kodwa ludinga isikhala se-catalyst reactor, ukulawulwa kokushisa, kanye nokunikezwa kwe-urea okuzinzile.
Okwamanje, i-EGR yehlisa i-NOx ngokubuyisela igesi yokukhipha umoya ekamelweni lokushisa, ngaleyo ndlela yehlisa ukugcwala komoya-mpilo kanye nokushisa okuphezulu kokushisa. Lolu hlelo luhlanganiswe kakhulu nenjini futhi ludinga ukulawulwa okunembile nokugcinwa kwezingxenye ezengeziwe njengezipholile zangaphakathi kanye nezihlanzi ukuze kuvinjelwe ukuchithwa.
Ukunciphisa Ama-Particulate kanye ne-Black Carbon
Izinto ezisanhlamvu (PM) kanye ne-black carbon kuyakhathaza ngenxa yomthelela wazo omkhulu empilweni kanye negalelo ekufudumaleni komhlaba, ikakhulukazi ezindaweni ezibucayi njenge-Arctic. Ukunciphisa i-PM kungatholakala ngokuthuthukisa ikhwalithi kaphethiloli, ukwenza ngcono ukushisa, kanye nokusetshenziswa kobuchwepheshe bangemva kokusha. Eminye imikhumbi ingasebenzisa izihlungi zezinhlamvu noma ubuchwepheshe obuthile bokusheshisa, yize ukusetshenziswa emikhunjini kuyinselele kakhulu kunezimoto ezisemhlabeni ngenxa yobukhulu besistimu, ukuhlukahluka komthwalo, kanye nezidingo zamandla aphezulu.
Ukusetshenziswa kwamafutha ahlanzekile njenge-MGO, i-LNG, noma amanye amafutha okwenziwa ngokuvamile kunciphisa i-PM kanye ne-black carbon. Ngaphezu kwalokho, amasu okusebenza njengokugcina injini isebenza ezingeni elifanele lomthwalo kanye nokugcinwa kahle kwe-injector kunganciphisa ukwakheka kwe-soot.
Ukusebenza Kahle Kwamandla Okuthumela: Indlela Eqondile Kakhulu Yokunciphisa I-CO₂
Ngenxa yokuthi i-CO₂ ihambisana ngqo nokusetshenziswa kukaphethiloli, ukunciphisa i-CO₂ kufezwa ngempumelelo enkulu ngokuthuthukisa ukusebenza kahle kwamandla komkhumbi. Lo mzamo uhlanganisa izici zokuklama nokusebenza. Ngokombono wokuklama, izinto ezintsha zifaka phakathi ukwenza ngcono ukuma kwe-shell, ukusetshenziswa kwezimbozo eziphansi, amadivayisi athuthukisa ukusebenza kahle kwe-propeller (isb., amapayipi angaphambi kokujika kanye nama-rudder bulbs), kanye nokuthuthukiswa kokusebenza kahle kwenjini kanye nesistimu yokunyakaza.
Ngasohlangothini lokusebenza, izindlela ezifana nokushisa kancane (isivinini esincishisiwe), ukwenza ngcono umzila ngokusekelwe esimweni sezulu, ukuphathwa kokusika kanye nokulawula i-ballast, kanye nokuqapha ukusetshenziswa kukaphethiloli ngesikhathi sangempela kuye kwabonakala kunciphisa kakhulu ukukhishwa kwegesi. Ukwenziwa kwedijithali nakho kudlala indima ebalulekile, isibonelo, ngezinhlelo zokwenza ngcono uhambo kanye nokuhlaziywa kokusebenza kwemikhumbi ukuthola ukwehla kokusebenza kahle ngenxa yokungcola noma umonakalo.
Amafutha Ahlukile kanye Nokufakelwa Ugesi
Ukushintshela kumafutha anekhabhoni ephansi kuyinsika ebalulekile yesistimu yokunciphisa ukukhishwa kwegesi isikhathi eside. I-LNG inganciphisa kakhulu i-SOx kanye ne-PM, futhi inamandla okunciphisa i-CO₂ uma kuqhathaniswa ne-HFO, yize izinkinga zokushelela kwe-methane zidinga ukuxazululwa. Ngaphandle kwe-LNG, ezinye izinketho zifaka phakathi i-methanol, i-ammonia, i-hydrogen, kanye ne-biofuels kanye namafutha okwenziwa (ama-e-fuels). Inketho ngayinye inemiphumela ekwakhiweni kwemikhumbi, ukuphepha, ingqalasizinda yokubeka imikhumbi, kanye nezindleko.
Emikhumbini ehamba ibanga elifushane, ukuhlanganiswa kwamabhethri kanye nama-batteri kuya ngokuya kuqaliswa, ikakhulukazi ezikebheni, ezikebheni zechweba, kanye nasezikebheni zokudonsa. Izinhlelo zamabhethri zinganciphisa ukukhishwa kwegesi ngesikhathi sokuhamba kanye nokusebenza ezindaweni zechweba, zinciphise umsindo, futhi zandise ukusebenza kahle. Kodwa-ke, ohambweni olude olunezidingo ezinkulu zamandla, amabhethri ngokuvamile asadlala indima yokusekela, hhayi ukufaka esikhundleni uphethiloli.
Ukuphathwa Kwamandla Olwandle kanye Nokukhishwa Kwegesi Emachwebeni
Ukukhishwa kwemikhumbi akugcini nje ngolwandle, kodwa futhi nalapho ivalwe echwebeni, lapho izinjini ezisizayo zihlinzeka ngogesi ezidingweni zomkhumbi. Isixazululo esithandwa kakhulu amandla ogwini, noma i-ayina ebandayo, ehlinzeka ngogesi ovela ezweni ukuze umkhumbi ukwazi ukucima ijeneretha yawo ngenkathi usesimeni. Ukusebenzisa amandla ogwini kudinga ukuhambisana kobuchwepheshe phakathi komkhumbi nezindawo zechweba, kanye nokutholakala kukagesi owanele nohlanzekile ukuze kukhuliswe ngokugcwele izinzuzo zokunciphisa ukukhishwa kwegesi.
Ngaphezu kwalokho, ukuphatha amashejuli okumisa imikhumbi, ukwandisa ukusebenza kahle kokulayisha nokukhipha impahla, kanye nokunciphisa izikhathi zokulinda nakho kuyizindlela ezibalulekile zokunciphisa ukukhishwa kwegesi ezindaweni zamachweba, ezivame ukuba seduze nezindawo zokuhlala zabantu.
Izinselele Zokusebenzisa kanye Neziqondiso Zesikhathi Esizayo
Nakuba ubuchwepheshe bokunciphisa ukukhishwa kwegesi buhlukahlukene, ukusetshenziswa kwabo kubhekene nezinselele ezifana nezindleko zokutshalwa kwezimali, isikhala esincane semikhumbi, izidingo zokuqeqeshwa kwabasebenzi, ukutholakala kwezingxenye ezisele, kanye nengqalasizinda kaphethiloli ehlukile. Abaqhubi bemikhumbi kumele futhi bacabangele ukuhwebelana phakathi kokuthobela imithetho yesikhathi esifushane kanye nokulungiselela isikhathi eside. Isibonelo, ukukhetha ama-scrubbers kungaba okonga ngaphansi kwezimo ezithile, kodwa akunciphisi ngokuzenzakalelayo i-CO₂. Ngakolunye uhlangothi, ukutshala imali kuphethiloli onekhabhoni ephansi kudinga ukuqinisekiswa kochungechunge lokuhlinzekwa kanye nemithethonqubo eguqukayo.
Kusukela manje, izinhlelo zokunciphisa ukukhishwa kwegesi olwandle zizogxila kakhulu ekuhlanganisweni kwezixazululo: ukusetshenziswa kahle kwamandla okwandayo, ukusebenza kwedijithali, ukwamukelwa kobuchwepheshe bangemva kokusha, kanye nokushintsha kancane kancane kube uphethiloli ophansi nongenawo uphethiloli. Ngokuhlanganiswa okufanele, ukuthunyelwa kwemikhumbi kungahlala kungumgogodla wezokuthutha zomhlaba wonke ngenkathi kunegalelo emigomweni yokunciphisa ukukhishwa kwegesi emhlabeni jikelele.
Ekugcineni, i-Marine Emission Reduction System ayilona nje iqoqo lamathuluzi obuchwepheshe, kodwa kunalokho isu eliphelele elihlanganisa ukuklama, ukusebenza, ukukhulisa amandla, kanye nokubambisana phakathi kwabaqhubi, abakhi bemikhumbi, amachweba, kanye nabalawuli. Uma leli su lisetshenziswa ngokushesha nangokuqhubekayo, kulapho ithuba elikhulu lomkhakha wezolwandle lokuba uhlanzeke, usebenze kahle, futhi uhlale isikhathi eside.
