Kugwiritsa Ntchito Rankine Cycle mu Steam Power Plants
Ma Steam Power Plants (PLTU) ndi amodzi mwa ukadaulo wopanga magetsi womwe umagwiritsidwa ntchito kwambiri padziko lonse lapansi. Mfundo yawo yogwirira ntchito imagwiritsa ntchito mphamvu yotentha kuti isinthe madzi kukhala nthunzi yothamanga kwambiri komanso yotentha kwambiri, kenako imasintha mphamvu ya nthunzi kukhala mphamvu yamakina kudzera mu turbine, yomwe kenako imasinthidwa kukhala mphamvu yamagetsi ndi jenereta. Pakati pa njira yosinthira mphamvu mu PLTU ndi Rankine Cycle, kayendedwe ka thermodynamic komwe kamapangidwa makamaka pamachitidwe amagetsi a nthunzi. Nkhaniyi ikufotokoza za kugwiritsa ntchito Rankine Cycle mu PLTU, zigawo zake zazikulu, ndondomeko ya njira, ndi kusintha kwa magwiridwe antchito komwe kumachitika.
Lingaliro Loyambira la Rankine Cycle
Mzunguliro wa Rankine ndi mzunguliro wokhazikika wa thermodynamic womwe umafotokoza kusintha kwa mphamvu mu madzi ogwirira ntchito (nthawi zambiri madzi/nthunzi) mu dongosolo lotsekedwa. Mzunguliro uwu ndiye maziko a kapangidwe ka malo opangira magetsi pogwiritsa ntchito malasha chifukwa ndi woyenera kupanga magetsi pogwiritsa ntchito magawo amadzimadzi ndi nthunzi. Mu mawonekedwe ake abwino, mzunguliro wa Rankine uli ndi njira zinayi zazikulu: kupopera madzi odyetsa , kuwatentha mu boiler kuti apereke nthunzi, kukulitsa nthunzi mu turbine kuti ipange ntchito, ndikubwezeretsanso nthunzi m'madzi mu condenser.
Ngakhale kuti kwenikweni mphamvu zimatayika (kukangana, kutsika kwa mphamvu, kusamutsa kutentha kosakwanira), chitsanzo cha Rankine Cycle ndi chitsanzo chowunikira magwiridwe antchito ndikupeza malo ogwirira ntchito bwino.
Zigawo Zazikulu za Chomera Chamagetsi cha Nthunzi mu Rankine Cycle
Kugwiritsa ntchito Rankine Cycle pa malo opangira magetsi pogwiritsa ntchito malasha kumaphatikizapo zinthu zingapo zofunika:
1. Pampu (Pampu ya Madzi Odyetsa)
Ntchito yake ndikuwonjezera mphamvu ya madzi oundana kuchokera ku mphamvu yochepa (condenser outlet) kupita ku mphamvu yayikulu kuti athe kulowa mu boiler. Chifukwa kupompa madzi kumafuna ntchito yochepa poyerekeza ndi kukanikiza mpweya, ntchito ya pampu mu Rankine Cycle nthawi zambiri imakhala yochepa kuposa ntchito ya turbine.
2. Boiler (Jenereta ya Nthunzi)
Boiler imagwiranso ntchito kutentha m'madzi othamanga kwambiri mpaka itasanduka nthunzi. Gwero la kutentha limachokera kuyaka kwa zinthu mafuta (malasha, biomass, mafuta, kapena gasi) kapena kuchokera kuzinthu zina monga kutentha kwa nyukiliya m'mafakitale amagetsi a nyukiliya. Mumafakitale amagetsi amakono opangidwa ndi malasha, boiler imakhala ndi madera angapo: chotenthetsera (chotenthetsera kale), chotenthetsera (chotenthetsera), ndi chotenthetsera (chotenthetsera kwambiri).
3. Chotenthetsera cha Nthunzi
Ma turbine amasintha mphamvu ya kutentha ndi kupanikizika kwa nthunzi kukhala ntchito yamakina kudzera mu kukula. Shaft ya turbine imalumikizidwa ku jenereta kuti ipange magetsi. Ma turbine nthawi zambiri amakhala ndi magawo angapo kuti awonjezere mphamvu ya kukula.
4. Chokonzetsera
Kondensa imaziziritsa nthunzi ya utsi wa turbine, ndikuisintha kukhala madzi. Mwa kupanga mpweya wochepa (vacuum yocheperako), kondensa imathandiza kukonza magwiridwe antchito a turbine komanso kugwira ntchito bwino. Kuziziritsa nthawi zambiri kumachitika pogwiritsa ntchito madzi a m'nyanja, madzi a m'mitsinje, kapena makina oziziritsira.
Kutsatana kwa Njira ya Rankine Cycle mu Steam Power Plant
Kugwiritsa ntchito Rankine Cycle kungafotokozedwe kudzera mu magawo anayi otsatirawa:
1) Njira Yopopera (1 → 2)
Mpweya wokondetsa mpweya wochokera mu condenser umakhala ndi mphamvu yochepa komanso kutentha kochepa. Pampu imawonjezera mphamvu yogwira ntchito ya boiler. Pa siteji iyi, kutentha kumakwera pang'ono, koma kusintha kwakukulu ndi kuwonjezeka kwa mphamvu. Mphamvu yomwe pampu imafuna imachokera ku mphamvu yamkati ya jenereta, koma mphamvu yake ndi yochepa poyerekeza ndi mphamvu yopangidwa ndi turbine.
2) Njira Yowonjezerera Kutentha mu Boiler (2 → 3)
Madzi othamanga kwambiri amalowa mu boiler ndipo amatenthedwa. Choyamba, madziwo amatenthedwa mpaka kufika powira (kutenthedwa bwino), kenako amasintha gawo kukhala nthunzi yokhuta (kutenthedwa kobisika), ndipo m'mapangidwe ambiri a malo opangira magetsi opangidwa ndi malasha, nthunziyo imatenthedwanso kukhala nthunzi yotentha kwambiri. Kutentha kwambiri n'kofunika chifukwa nthunzi youma yomwe imalowa mu turbine imachepetsa chiopsezo cha kuwonongeka kwa tsamba la turbine kuchokera ku madontho a madzi.
Apa ndi pomwe mphamvu ya mankhwala ya mafuta imasinthidwa kukhala mphamvu yotentha mu madzi ogwirira ntchito. Kugwira ntchito bwino kwa kuyaka, kusamutsa kutentha, ndi kapangidwe ka boiler zimakhudza kwambiri magwiridwe antchito a chomera.
3) Njira Yokulitsa mu Turbine (3 → 4)
Nthunzi yamphamvu imalowa mu turbine ndikufutukuka, kuchepetsa kupanikizika ndi kutentha kwake pamene ikupanga ntchito yamakina pa shaft. Ntchito imeneyi imayendetsa jenereta. Pansi pa mikhalidwe yabwino, kukulitsa kumaonedwa ngati isentropic (constant entropy), koma m'mikhalidwe yeniyeni, kusasinthika kumachepetsa ntchito ya turbine.
Ubwino wa nthunzi pa nsonga ya turbine ndi nkhani yofunika kwambiri. Ngati nthunziyo ndi yonyowa kwambiri, madontho a madzi amatha kugunda masamba a turbine ndikuyambitsa dzimbiri/kukokoloka. Chifukwa chake, mafakitale amagetsi nthawi zambiri amayesetsa kusunga nthunzi yonyowa pang'ono pamalo otulukira turbine.
4) Njira Yokonzetsera Madzi mu Kondensa (4 → 1)
Nthunzi yotulutsa mpweya ya turbine imalowa mu condenser ndikutulutsa kutentha kupita ku malo ozizira, ndikuupanga kukhala madzi. Izi zimachitika pa mphamvu yochepa. Malinga ndi mphamvu, kutentha komwe kumakanidwa mu condenser kumayimira "kutayika" kwa kutentha komwe sikungasinthidwe kukhala ntchito, koma ndikofunikirabe kuti kayendedwe kabwerezedwe ndikusunga mphamvu yochepa yotulutsa mpweya, zomwe zimawonjezera magwiridwe antchito a turbine.
Madzi oundanawo amabwerera ku pampu kuti abwerezenso kayendedwe kake.
Zifukwa Zomwe Rankine Cycle Imagwirira Ntchito Pazomera Zamagetsi Za Nthunzi
Mzunguliro wa Rankine ndi wothandiza kwambiri chifukwa:
- Kugwiritsa ntchito madzi ngati madzi ogwira ntchito omwe ndi otsika mtengo, otetezeka komanso okhala ndi mawonekedwe abwino a kutentha.
- Amagwiritsa ntchito kusintha kwa gawo la madzi ndi nthunzi zomwe zimathandiza kuyamwa kutentha kwakukulu.
- Zingakonzedwe bwino mwa kuwonjezera kutentha ndi kupanikizika kwa nthunzi yolowa mu turbine, ndikuchepetsa kupsinjika kwa condenser.
- Zimathandizira kukhazikitsa ukadaulo wowonjezera mphamvu, monga kutenthetsanso ndi kutentha kobwezeretsa mphamvu.
Kukonza Kuchita Bwino: Kusintha kwa Rankine Cycle
M'machitidwe, mafakitale opangira magetsi pogwiritsa ntchito malasha nthawi zambiri amagwiritsa ntchito njira yosavuta ya Rankine. Zosintha zingapo zimagwiritsidwa ntchito nthawi zambiri kuti ziwongolere magwiridwe antchito ndikusunga kudalirika kwa zida:
1) Chotenthetsera champhamvu komanso chowunikira kwambiri
Kuonjezera kutentha kwa nthunzi turbine isanakwere (superheat) kugwiritsa ntchito bwino kutentha chifukwa zimawonjezera kusiyana kwa mphamvu zomwe zingatulutsidwe mu turbine. Mafakitale ena amakono opangira magetsi pogwiritsa ntchito malasha amagwiritsa ntchito zinthu zowopsa kwambiri kapena zowopsa kwambiri, zomwe zimagwira ntchito pamavuto ndi kutentha kwakukulu kotero kuti palibe malire omveka bwino a gawo la nthunzi yamadzimadzi mu boiler. Ukadaulo uwu ukhoza kuwonjezera magwiridwe antchito koma umafuna zipangizo zomwe zimatha kupirira kutentha ndi kupsinjika kwakukulu.
2) Tenthetsaninso
Mu nthawi yotenthetseranso, nthunzi yotambasuka pang'ono mu turbine yamphamvu imabwezeretsedwa ku boiler kuti itenthedwenso, kenako imalowetsedwa mu turbine yapakati/yotsika. Cholinga chake ndi:
- kuwonjezera ntchito yonse ya turbine,
- kuchepetsa chinyezi cha nthunzi kumapeto kwa turbine,
- kupititsa patsogolo magwiridwe antchito a kayendedwe ka kayendedwe ka zinthu.
3) Kutentha kwa Madzi Obwezeretsa Mphamvu
Nthunzi ina imachokera ku magawo ena a turbine (nthunzi yotuluka magazi) kuti itenthetse madzi operekera chakudya asanalowe mu boiler kudzera mu chotenthetsera madzi operekera chakudya. Mwa kukweza kutentha kwa madzi operekera chakudya, zofunikira pa kutentha kwa boiler zimachepa ndipo magwiridwe antchito amawonjezeka. Dongosololi lingagwiritse ntchito chotenthetsera chotseguka (deaerator) kapena chotenthetsera chotsekedwa (chotenthetsera chotsekedwa).
4) Kukonza Kondensala ndi Dongosolo Loziziritsira
Kuchepetsa mphamvu ya condenser (kuwonjezera vacuum) kudzawonjezera kutsika kwa enthalpy mu turbine ndikuwonjezera mphamvu yotulutsa. Komabe, izi zimadalira pa kuthekera kwa makina oziziritsira kutenthaChifukwa chake, ubwino wa condenser, ukhondo wa chubu, ndi kutentha kwa madzi ozizira ndizofunikira kwambiri kuti ntchito iyende bwino.
Mavuto Ogwira Ntchito Pakukhazikitsa Rankine Cycle
Kupatula zabwino zake, kugwiritsa ntchito Rankine Cycle mu PLTU kumakumana ndi zovuta:
- Kutayika kwa mphamvu chifukwa cha kukangana, kutuluka kwa madzi, komanso kusamutsa kutentha kosayenerera.
– Ubwino wa madzi ndi dzimbiri: madzi odyetsera ayenera kutsukidwa mosamala kuti asawonongedwe ndi dzimbiri m'maboiler ndi ma turbine.
– Mpweya woipa ndi chilengedwe: m'mafakitale opanga magetsi pogwiritsa ntchito malasha, kuyaka kumapanga CO₂, SOx, NOx, ndi tinthu tating'onoting'ono, kotero zida zowongolera mpweya woipa zimafunika.
– Zofooka pa zinthu: kutentha kowonjezereka ndi kupanikizika kumafuna zipangizo zapadera zomwe zimakhala zodula komanso zovuta kusamalira.
Mapeto
Mzunguliro wa Rankine ndi gawo lofunika kwambiri pa ntchito za magetsi pogwiritsa ntchito malasha (PLTU) chifukwa umalola kusintha mobwerezabwereza mphamvu ya kutentha kukhala mphamvu yamakina ndi yamagetsi kudzera mu njira zinayi zazikulu: kupopera, kutentha, kukulitsa, ndi kuzizira. Pakugwiritsa ntchito kwenikweni, mzungulirowu umasinthidwa ndi ukadaulo monga ma superheater, ma reheater, kutentha kobwezeretsa, ndi kukonza ma condenser kuti awonjezere magwiridwe antchito ndikusunga kudalirika kwa turbine. Ngakhale kuti pali zovuta zokhudzana ndi kutayika kwa mphamvu, ubwino wa madzi, ndi zotsatira zachilengedwe, kukhazikitsa mzunguliro wa Rankine kumakhalabe chisankho chachikulu cha mafakitale amphamvu a nthunzi chifukwa cha kusinthasintha kwake, kukhwima kwaukadaulo, komanso kuthekera kokulitsa magwiridwe antchito ngati pakufunika.
Ngati mukufuna, nditha kuwonjezeranso chithunzi cha kayendedwe ka njira kapena kufotokozera kochokera ku ma curve a T–s (Temperature–Entropy) kuti kayendedwe kake kawonekedwe bwino komanso mwaukadaulo.
