Ukuthiwa kwesibonelo se-Cryogenic ku-LNG

Isiphumo esisodwa sokukhipha i-LNG

Ukuproducwa kwe-LNG kuyaphendula ekwenzeni yekhanda elinye: ukukhipha umthelelo wemethane ukuze kube yiliquidi ngokwesibini e-162°C. Umgcino wokukhipha umthelelo wokushisa ngu-“cryogenic expansion” uyindlela eyenzeka ngayo. Akukho micala omnye wokugcinwa okanye isikhathi esisodwa — kodwa ngu-“thermodynamic strategy” oyenza ngalo konke ukukhipha umthelelo wokushisa.

Ngokufuphi kakhulu, le ndlela iyathatha umthelelo wekhanda eliphezulu kakhulu futhi iyakhipha ngaphansi kwemicala noma ngapha kwe-turboexpander. Ukukhipha kuyabeka umthelelo oshisayo, futhi le mithombo yoshisayo yayisebenza njengomthelelo wokushisa wesikhathi esilandelayo. Umthwalo wokukhipha nokubonana nokushisa kuyabeka umthelelo wokushisa wokufika emthwakweni wokukhipha umthelelo wokushisa.

I-Nitrogen Rejection Unit (NRU) yisikhathi esisodwa sokusebenzisa le ndlela. Uma umthelelo wokushisa unazo amanqaku amaningi ase-Nitrogen — okungathi akhusele umthelelo wokushisa futhi ayakhipha isikhathi esingaphezulu kwe-LNG — i-NRU iyakhiqiza kona ngokusebenzisa ukukhishwa kwamandla okushisa. leqondile lelithi kubonakala kwekuphanda nokugcina ukuhlukanisa inyitrojheni kusuka kwe-LNG ngaphandle kokusebenzisa amachemikhali ukuguquka kwezinhlobo kuyiphinda ngokuthi inyitrojheni iphinde kufana nesikhombisa sokugcina okuphephile kuya kuhlanganisa izinhlobo ezinkulu zokugcina okungcono noma izinhlobo zokugcina ngokwesibalo .

Lokhu kubalulekile ngoba imithombo yezindawo zokugcina nezinkampani zokuthumela LNG ziyabhekana nezidingo zokugcina inyitrojheni ngokuphelele. Uma akukho NRU efanele, i-LNG ayikwazi ukufufana nemilingo noma umproduser ayathumela amandla angaphezu kwe-cubic meter ayo. Ngokunye namanye, izindlela zokusebenza ziyagcinwa.

Amaturobho-ekspande kanye nezivali zika-Joule-Thomson: Ukuguqula Okuphelele

Ukuphanda kwesikhathi esihlukile kwenza ngamathuba amabili: izivali zika-Joule-Thomson nezivali zamaturobho. Zombili ziyagcina uphazimbe nokulingana komlando wamandla, kodwa ziyenza ngendlela eyahlukile, futhi ukukhetha phakathi kwazo kunezimpikiswano zokusebenza kwezindawo.

Ivali ye-Joule-Thomson iyisilinganiso, ibalulekile kakhulu, futhi ayinamaphakathi ohlukeni. Igasi liyaphakanyiswa ngaphansi kwavalu, futhi ubukhulu buphela ngokusebenza kwe-Joule-Thomson. Iqiniso liyokuthi lokhu kuyiphakanyo esilinganisweni sezindawo — akukho umsebenzi owenziwa ngokuphulula kwebhurde. Lonke umsebenzi uyagcina ukuchitha igasi, kodwa ubukhulu buhambisana kakhulu.

Ngokuhambisana, iturboexpander iyathola umsebenzi ngokuphakanyiswa kwegasi. Lokhu kuyiphakanyo esilinganisweni sezindawo — okusho ukuthi amandla ebhurde ayizokwenzelwa umsebenzi othile (okunjalo ukudrivisa ikhomphresi ephakathi kwesikhombisa samekhosha) ngakolunye usuku ngokuphela ukubuka ubukhulu. Ubukhulu besilinganisweni sezindawo lwale zinhloso ziyahlala phakathi kwe-60-70% ngokwesayensi ngokwesayensi yokuqondwa nokusebenza. Lokhu kumsebenzi okutholwe kungahlinzeka okunye kwezinhloso zokugcinwa zezinhloso ezinye zokukhomphresa.

Ukubuyisana kuyisiphumo sokukhula nokuthabatha imali. I-turboexpander yindlela yokusebenzisa izinkampani ezikhulu nezinkampani ezinkulu, nezinkampani zokuphepha okwamanzi, nezinkampani zokugcina ezingcono. Kufuneka kuzenzekwe ukulungisa okungakwazi ukwenza i-JT valve. Kuma-plant amancane noma kumaqembu apho ukuguqula kwesifuba kuyisifuba esincane, i-JT valve ishaya ngokwesibonelo sokuthabatha imali yonke. Kumaqembu ase-LNG apho ukuthengisa kuyakwenzeka ngokwesibonelo sokuthengisa, i-turboexpander iyathola imali yayo ngokuphakeme.

Kuphi Ukuthiwa Kwesikhali Sokuvaleka Kusuka Ku-LNG Train

Isiphumo sokuvaleka kwesikhali sibonakala emazwi amaningi kumqembu wokuvaleka kwe-LNG. Ukuzwa kuphi nokuzwa ukuthi kungani kuyakusiza ukuchaza ukuthi umqembu wokuvaleka uyasebenza njani.

U-MCHE wokhuluma kakhulu kwezindawo zokusebenza zama-LNG. U-refrigerant — okwesibonelo u-mixed refrigerant noma u-nitrogen okuphele — uyaphakanywa, uyakhiwa, bese uyaphakanywa ku-temperatures ozimnandi ngaphansi kweminyaka emibi phambi kokufika esikhathini sokuhlisa kwe-MCHE. Le sikhathi sokuhlisa sokumnandi siyakhiwa kusukela kwe-refrigerant, sithatha umthelela wesikhathi esikhulu kusuka kwe-feed gas esikhathini sokunene, futhi le sikhathi sokunene siyakhiwa kusukela kwe-methane. Isikhathi sokuhlisa siyakhiwa kusukela kwe-turboexpander yomthwalo we-refrigerant, futhi le sikhathi sokuhlisa sokumnandi siyakhiwa kusukela kwe-exchanger.

Kukusetshenziswa kwe-nitrogen rejection, isikhathi sokuhlisa siyakhiwa kusukela kwe-temperatures ozimnandi okunconywa ukwenza ukubhekana. U-feed gas uyakhiwa kusukela kwezinyathelo ezimbili, futhi le sikhathi sokuhlisa sokumnandi — okwesibonelo uyakhiwa kusukela kwe-methane — uyakhiwa kusukela kwezinyathelo ezimbili zokubhekana, futhi le sikhathi sokuhlisa sokumnandi — okwesibonelo uyakhiwa kusukela kwe-nitrogen — uyakhiwa kusukela kwezinyathelo ezimbili zokubhekana. Le sikhathi sokuhlisa sokumnandi sokubhekana siyakhiwa kusukela kwe-nitrogen okwesibonelo uyakhiwa kusukela kwezinyathelo ezimbili zokubhekana, futhi le sikhathi sokuhlisa sokumnandi siyakhiwa kusukela kwezinyathelo ezimbili zokubhekana.

Izinkampani ezincane zezinkampani zokuphatha i-LNG zisebenzisa indlela yokusebenzisa i-nitrogen yonke, apho i-nitrogen isebenza njengomthwakuli wokuhlisa nokusebenza. I-nitrogen isekhompreshiwe, isahliswe ngokubambisana nezinto eziphatha kuyo, ishwekwe kwi-turboexpander, futhi ekhulula i-methane kwi-heat exchanger engeyona. Indlela iyisibonelo esihlukene futhi isebenza kahle kumakhala amancane apho ubuncinane be-mixed refrigerant system akasenzi ukuthi bube yilokho okufanele.

Ukubuka kwezinto ezibalulekileyo kwezinkinga zokususa i-nitrogen

I-unit yokususa i-nitrogen ibonakala esihlukene kuzinhloso. Kwenyathelo, yilokho okubalulekile kakhulu kwezinkinga zezinkampani zokuphatha i-LNG.

Kusasa kwakugcina kwezinsiza zaseNtshonalanga kaKanada kusasa kwezinyanga eziningi, umsebenzisi wabulawa i-NRU entsha eyadluliswa ukuthi yisebenze ngokwesibonelo sesigas sokufaka esinabantu abaningi kwe-8%. Isibonelo sokudesign sibe yilungile, izinkampani ziyaphakamisa ngokuphelele, futhi umthengisi we-EPC uyayiqonda ngempilo yokuqondisa isigas ngokuchitha. Kodwa isibonelo sokufaka esihlanganiswe kuyabonakala kubaluleke kakhulu kunokuba kubonakala kwezinsiza zasezantsi. Ubunzima be-nitrogen buyagcina kuma-11% kusasa kwezinyanga zokuproducwa.

I-NRU ibuyela ukuthi ibe yisibonelo. Ubunzima be-nitrogen obungaphezu buyagcina ikholomu yokuchitha kuthi ibe yisibonelo sokuthi "iflooding" — umsindo wokuchitha uyagcina kakhulu kusukela ubungaphumeleli bokuvula kwezincwadi. Isiphumo sisibonelo esingavumelekile, noma kubizwa ngokuthi ubungaphumeleli bekuchitha, nokuthi ubungaphumeleli bekuchitha kuyagcina kakhulu kwe-methane ekhaya kwezindawo zokuvula futhi ubungaphumeleli bekuchitha kuyagcina kakhulu kwe-nitrogen ekhaya kwezindawo zokuvula. Iplanti yayikufuna ukuthintela ukufaka ukuthi ukuthintela ukuproducwa kwe-LNG kusukela ukuthi kuyathintela ukuproducwa.

Ukuthintela kwenzeke ngokudala kwesibhakabhaka yesibili kumkhala wokuhlisa isikili nekuvamisela kabusha izikhathi zokubuyela kusuka kucolomu. Kwenzenjani, kodwa kubiza umsebenzisi iminyaka emibili yokungasebenzi futhi ukuthengiswa kwemali engenakho kubudhajethi yokuqala.

Isifundo esikhiywe lapha kukuthi izindlela zokukhanyisa kwezinkulungwane ziyisenzakalo sokuguqula kokufika. Umthunyi wokuthola okuziqondile lokhu kuzoba kwenza ukuthi kwenzeke ukuthayiwe kwezindawo eziphakeme — ukuphakamisa izinkambo ezithile, ukudala ukuthi kungenzeka ukuthi kubhekwe phambili, nokuhlanganisa izibopho ezinokuthi zilungiselela ukuthi kwenziwe izinyathelo zokusebenza. Umthunyi owenza le ndlela njengokuthi kuyinto ekhuluma ngokuphelele kuzoba kwenza indawo eyenzeka kakhulu ngokubhalwe kodwa ayizange ikhulume ngokwempilo.

Izinkinga Zokusebenza Ngokwengeziwe Nezinto Ezibalulekileyo Okubhalwe Ngazo

Kukhona ukuthetha kakhulu ngendlela yokuqasha kwe-LNG ngokwengeziwe kwezindlela, kodwa izinombolo azizange zibandakanya izinto abantu bafunda.

Izindlela zokushebeka kwezinkulungwane zokufakwa kwamanzi zinakwenzela ukuthuthukiswa okukhulu kwesilinganiso sokufakwa kwamanzi uma kuzokwenyelwa ngokuphelele. Izifundo zazisombulula ukuthi izindawo zokushebeka ezithunywa ngokuphelele zinakwenzela ukuthuthukiswa kwesilinganiso sokushebeka ngokuphelele ngokugcwele 5% ngaphezu kwezindlela zokusebenza eziphakathi. Ngokuxhumana nezindlela zokufakwa kwamanzi zokusebenza ngokuphelele, lokhu kubhekisa kuqinisekiswa kokuthuthukiswa kokuprodukwa. Izingxelo ezithile zisombulula ukuthuthukiswa kokuprodukwa kwamanzi ngokugcwele 5-7% ngokuvuselela ukuthuthukiswa kokusebenza kwesikhundla sokushebeka.

Kodwa lezi zinombolo zinamaphoyisa. Ukuthuthukiswa kwesilinganiso kuyaphenduka kakhulu ngokwesimo sokusebenza esithile — isiphumo sokungena, isimo sokugcina, ubusha bokuphakeme, nokuhlanganiswa kwesinye isikhundla sokusebenza. Ukuthuthukiswa okugcwele 5% kwesilinganiso sokushebeka kahle akubikho ukuthuthukiswa okugcwele 5% kwesilinganiso sokusebenza kwesikhundla sokuprodukwa ngokuphelele. Isiphumo esihlukene sisho kancane futhi sivaryela ngokuhlukahluka kwesikhundla sokusebenza ngasinye.

Isidingo esinye sikhona kukusebenza kahle. Umshini wokususa okuphela kufa kuyakhipha isikhephe sokususa ngokwesibonelo. Kwenye indawo yokuprodukha i-LNG, lokhu kuthiwa ukuthi konke okuprodukha kufa. Ngalesi simo, abasebenzi abaningi bakhanya amasimbi e-rotor abanqamuka futhi banezindlela zokubuyela ku-mfr. Ikhanda lokugcina lokho kufanele libhalwe ekhanda lokusebenza kwezinhlelo zokusebenza, akalifaneli kuphela ukulinganisa i-khanda lokuphatha phakathi kwe-JT valve ne-turboexpander.

Kungani Ukuchaza Kwesikhundla Kufanele Kuhlanganise Ekusebenzeni Okudala

Ukuchaza kwesikhundla sokususa okususwa kuzo kufana nokubhekisa kwezinye izinsuku ezingu-20 uye ezingu-30. Indawo eyadluliselwe ngokusebenzisa i-JT valves kuyakwazi ukuthi yizinkulu kakhulu futhi iyakwazi ukuthi yingcono ukuzilungiselela, kodwa kuyakwazi ukuthi yizinkulu kakhulu ukuthi yenzela i-LNG ngokwesikhundla. Indawo eyadluliselwe ngokusebenzisa i-turboexpanders kuyakwazi ukuthi yizinkulu kakhulu ukuthi yenzela i-LNG ngokwesikhundla kodwa kuyakwazi ukuthi yizinkulu kakhulu ukuzilungiselela, kodwa kuyakwazi ukuthi yenzela i-LNG ngokwesikhundla esifanayo.

Akukho impendulo eyoqobo. Indlela eyodwa ephakathi kuyisiphumo sokuthi yini okufanele ukwenziwa kusenzo esithile — izindlela zokuthenga amandla, isivinini sezindlela zokuproducisa i-LNG, ukuthi kungakhona abafundi bezokulungisa izinkambo, nokuthi ubunzima bokuhlukana kwesikhathi sokuzimela okungasemthwakweni.

Okubalulekile kukhona ukuthi umsebenzisi we-EPC uyazi ukuthi kungani okuhlanganisa nokuthi kungani okuhlanganisa futhi akwazi ukubonisa ngokucacile. Umsebenzisi oshaya amandla we-turboexpanders kuzo zonke izenzo ngoba ziyathetha ngokuthi zingcono kakhulu ayibonisi umphathi ngokuvamile. Ngokufanayo, umsebenzisi oshaya amandla we-JT valves kuzo zonke izenzo ngoba zingcono kakhulu ayabhekisa imali engezansi ephakamile ekufuneka kuthengwa ngokusebenzisa izindlela eziningi zokusebenza ngokuphelele.

Indlela enzima yokuqonda ngokuphelele kukuthi kufanele isithembiso sifanane nezinga lezinkinga zokusebenza ngokulinganisa nezindlela zokusebenza zomshini. Kuma-projekthi apho ukubhalwa kwe-feed kuyaziwa kahle futhi kuyasemthwakathwakeni, indlela encane yokunqamuka inokuba yisifano esihle kakhulu. Kuma-projekthi apho ukubhalwa kwe-feed kuyashintsha noma izindlela zokusebenza zokuphatha amandla kuyaphakeme, ukuthengiswa kwabantu bokunqamuka ngokushesha (turboexpanders) nokusebenzisa izikhombisa zokuchitha okungcono kusobala ukuthi kuyabonakala ngokuphelele.

Ukunqamuka ngokushesha kungumlando wokubhekana ngokujabula. Kuyizinketho eziningi zokusebenza okufanele zifanane nezinkinga zokusebenza. Abaprojekthi abazi lokho — futhi abanembono yezinto eziphathelene nako — bayabhekana ngokuphelele. Greenfir ibeka le ndlela yokubhekana ngokuphelele emisebenzini yokuprosesa amagasi ngokushesha, ibeke ngokuthi kuyasebenzisa i-ASME U-stamp certification futhi kuyasebenzisa isikhundla sokusithembisa esinamandla amaningi ekuproseseni kwezinto zokusebenza ngokushesha eNingizimu Afrika .