Izinhlelo Zokuvala Ezimbili Zemishini: Nini Futhi Kungani Kufanele Zisetshenziswe

Isingeniso

Isivalo esiphindwe kabili semishini ngokuvamile sikhethwa lapho ukuvuza kungenakuphathwa njengenkinga encane yokulungisa kodwa njengengozi yokuphepha, yemvelo, noma yokwethembeka. Kumaphampu aphatha uketshezi oluyingozi, oluguquguqukayo, olugubhayo, noma olungagcobi kahle, ilungiselelo lesivalo esiphindwe kabili lengeza isithiyo sesibili sokuvimbela futhi ngokuvamile lisebenza nohlelo lokusekela ukuze kuqiniswe izimo zokusebenza. Lesi sihloko sichaza ukuthi lokho bunzima obengeziwe bufanelekile nini, yiziphi izici zenqubo eziqhuba isinqumo, nokuthi kungani ukukhetha isivalo kuthinta ukulawulwa kokukhishwa komoya, impilo yemishini, kanye nesikhathi sokungasebenzi esingahleliwe. Kusukela ekunciphiseni ubungozi kuya kwezomnotho zokusebenza, ingxoxo inikeza uhlaka olusebenzayo lokunquma ukuthi isivalo esiphindwe kabili semishini siyisinqumo esifanele sobunjiniyela.

Kungani Ukukhetha Izisimbozo Ezimbili Zemishini Kubalulekile

Emisebenzini yesimanje yokuphatha uketshezi kanye nokujikeleza imishini,uphawu lomshini lusebenza njengesivikelo esiyinhlokophakathi koketshezi lwenqubo kanye nendawo yangaphandle. Nakuba izivalo zomshini ezilodwa zanele ukusetshenziswa okungenangozi, ukucaciswa kohlelo lokuvala oluphindwe kabili lwemishini kuba yisibopho esibalulekile sobunjiniyela lapho umkhawulo wephutha usondela ku-zero. Ukukhetha ubuchwepheshe bokuvala obufanele akuyona nje indaba yokugcinwa koketshezi; kuyisici esiyisisekelo sokuphepha kwezitshalo, ukuthobela imvelo, kanye nenzuzo yokusebenza yesikhathi eside.

Isinqumo sokusebenzisa ukucushwa kwe-dual seal sishintsha ngokuyisisekelo ukwakheka kohlelo lokupompa. Sethula ukugcinwa kwesibili, izinhlelo zokusekela ezisizayo, kanye nokuguquguquka koketshezi okuyinkimbinkimbi okumele kuphathwe ngokucophelela. Ukuqonda amaphrofayili engozi aqondile kanye nemiphumela yokusebenza edinga lokhu kuthuthukiswa yisinyathelo sokuqala sobunjiniyela bemishini ejikelezayo enomthwalo wemfanelo.

Ukuthembeka kanye nezingozi zokuphepha

Isizathu esisheshayo kakhulu sezivalo ezimbili zemishini sisekunciphiseni izingozi zokuhluleka okukhulu. Ezisetshenzisweni zokucindezela okuphezulu noma ezishisa kakhulu ezibandakanya uketshezi oluvuthayo, olunobuthi, noma oluqhumayo, ukwehluleka okungazelelwe kwesivalo esiyinhloko kungaholela ezingozini eziseduze. Uketshezi olunezindawo zokukhanya ezingaphansi kuka-60°C (140°F), izilinganiso zezingozi zezempilo ze-NFPA ezingu-3 noma 4, noma lezo eziqukethe ukungcola komoya okuyingozi (ama-HAP) zidinga ukugcinwa okungafuneki ukuze kuvinjelwe ukwakheka kwamafu omhwamuko noma umlilo.

Ngokusebenzisa ubuso besivalo sesibili, izikhungo zithuthukisa kakhulu i-Mean Time Between Failures (MTBF) yemishini, ngokuvamile zandisa impilo yokusebenza ngo-150% kuya ku-300% uma kuqhathaniswa nezivalo ezisodwa ezinsizeni ezifanayo. Uma isivalo sangaphakathi siphazamisekile, isivalo sangaphandle siqukethe okwesikhashana uketshezi lwenqubo noma uketshezi lokuvimba, okuvumela abaqhubi ukuthi benze ukuvalwa okulawulwayo kunokuba babhekane nokukhululwa okuphuthumayo okuyinhlekelele.

Ukukhathazeka ngokukhishwa kwegesi kanye nokuvuza

Imithethonqubo eqinile yezemvelo iphoqa izikhungo zesimanje ukuthi zifinyelele cishe ku-zero ukukhishwa kwegesi okusabalele. Izinhlaka zomthetho, njenge-EPA's Method 21 e-United States noma i-Industrial Emissions Directive eYurophu, ziphoqelela imingcele yokuvuza eqinile ye-volatile organic compound (VOC), evame ukuphoqelela imikhawulo engaphansi kwezingxenye ezingu-500 ngesigidi (ppm), kanti kwezinye izindawo, ephansi njenge-50 ppm.

I-seal eyodwa, ngokwedizayini, incike efilimini yoketshezi oluncane ukuze igcobe ubuso bayo, okuholela ekushiseni okuncane (ngokuvamile kusuka ku-1 kuya ku-5 amagremu ngehora) kanye nokukhishwa kwegesi emoyeni.Izimpawu zomshini ezimbili, ikakhulukazi labo abasebenzisa uketshezi oluvimbelayo olucindezelwe (i-API 682 Arrangement 3), baqeda ngokuphelele ukukhishwa koketshezi lwenqubo emkhathini, bethatha indawo yokuvuza okungenzeka kwenqubo ngamanani amancane oketshezi oluvimbelayo olungenabungozi.

Umthelela wokukhiqiza nokugcina

Ngaphandle kwemithetho yokuphepha kanye nemvelo, ukukhethwa kwezimpawu kuthinta kakhulu ukutholakala kwezitshalo kanye nesabelomali sokunakekelwa kwazo.Ukwehluleka kwe-mechanical seal kubalelwa cishe ku-70%kuzo zonke izindlela zokulungisa iphampu ye-centrifugal. Ukufakwa kwesivalo sephampu okuvamile kudinga phakathi kwamahora angu-8 kuya kwangu-24 okusebenza kanye nesikhathi sokungasebenzi esihambisanayo, okungadala ukulahlekelwa komkhiqizo okusukela ku-$10,000 kuya ngaphezulu kuka-$50,000 ngehora ezinqubweni eziqhubekayo ze-petrochemical.

Izivalo ezimbili zemishini zihlukanisa ubuso besivalo obunemigqa eqondile ezimweni ezinzima zenqubo. Ngokuhlinzeka ngoketshezi oluvimbekile oluhlanzekile, olupholile, nolunamafutha amaningi, ubuso besivalo buvikelwe ekusebenzeni okomile, ukuguguleka okunamandla, kanye nokuphambuka kokushisa, okwandisa kakhulu umjikelezo wokuphila wephampu futhi kunciphisa ukungenelela kokulungisa okungahleliwe.

Iyini I-Double Mechanical Seal?

Isivalo esiphindwe kabili somshini, okuvame ukubizwa ngazo ezindinganisweni zobunjiniyela zanamuhla njengophawu oluphindwe kabili, luqukethe izivalo ezimbili ezizimele zemishini ezisebenza ngokulandelana noma ngokuhambisana ngaphakathi kwegumbi elilodwa lesivalo. Lokhu kulungiselelwa kudala umgodi phakathi kwezivalo ezimbili ogcwele uketshezi lwesibili, olwaziwa ngokuthi uketshezi lwe-buffer noma isithiyo, olusebenza ukugcoba ubuso besivalo, ukuqeda ukushisa, kanye nokuhlinzeka ngesendlalelo sesibili sokuthwala.

Ukwakheka okuyisisekelo kuncike ekusebenzisaneni phakathi kwe-inboard seal (ehlangana ngqo ne-process fluid) kanye ne-outboard seal (ehlangana nomoya). Amandla oketshezi lwesibili anquma ukuhlukaniswa okuqondile kanye nekhono lokusebenza kwe-dual seal assembly.

Incazelo eyinhloko kanye nomgomo wokusebenza

Isimiso sokusebenza kwesivalo esiphindwe kabili sincike ngokuphelele ekuhlukeni kwengcindezi okugcinwe emgodini ophakathi kwezivalo zangaphakathi nezangaphandle. Uma uketshezi lwesikhala lugcinwa kungcindezi ephansi kunokucindezela kwebhokisi lokugcwala kwenqubo, lubizwa ngokuthi “uketshezi lwe-buffer” (Uhlelo 2). Kulesi simo, isivalo sangaphakathi sigcotshwa uketshezi lwenqubo, futhi noma yikuphi ukuvuza kwenqubo kubanjwa uketshezi lwe-buffer.

Ngakolunye uhlangothi, lapho uketshezi lwe-cavity lucindezelwa luye ezingeni eliphakeme kunengcindezi yenqubo—ngokuvamile olugcinwa ku-1.5 kuya ku-2.0 bar (22 kuya ku-29 psi) ngaphezu kwengcindezi ephezulu yebhokisi lokugcwala elinamandla, okuvame ukudinga amazinga okujikeleza kwegazi angamalitha ama-2 kuya kwangu-8 ngomzuzu—lubizwa ngokuthi “uketshezi lwesithiyo” (Uhlelo 3). Ngaphansi kwalezi zimo, uketshezi lwesithiyo lugcoba kokubili ubuso besithiyo sangaphakathi kanye nobesingaphandle. Uma isivalo sangaphakathi siguga, uketshezi lwesithiyo luvuza ngaphakathi enqubweni, okuqinisekisa ukuthi akukho ukuvuza kwangaphandle kwe-medium yenqubo eyingozi.

Ukuqhathanisa nezimpawu zodwa

Ukuqonda umehluko oqondile phakathi kokumiswa kwesivalo esisodwa nesiphindwe kabili kubalulekile ekuhlaziyweni kwezindleko zomjikelezo wokuphila kanye nobungozi. Ukwengezwa kwesivalo sesibili kushintsha kakhulu imbobo yokusebenza yephampu.

Ukuhlelwa kwesivalo kanye nokuqondiswa kobuso

Izimbobo ezimbili zakhiwe ngezindlela eziningana ezihlukile zejometri ukuze kuhlangatshezwane nemingcele yendawo ehlukahlukene kanye nezidingo zokucindezela. Igama elidala elithi “ukubuyela emuva,” “ubuso nobuso,” kanye nelithi “i-tandem” selithathelwe indawo kakhulu yizigaba ze-API 682, yize ukuqondiswa ngokomzimba kusabalulekile.

Ukuqondiswa ngemuva kuya emuva kubeka izindandatho zesivalo ezijikelezayo zibheke kude komunye nomunye, okuyinto enhle kakhulu kuma-barrier fluids anengcindezi ephezulu (ngokuvamile alinganiswa ngamabha angu-40 kuya kwangu-60 / 580 kuya ku-870 psi) kodwa kuveza ihadiwe yesivalo sangaphakathi ku-process fluid. Ukuqondiswa ubuso nobuso kwabelana ngendandatho efanayo yokumathisana engashintshi futhi kuvame ukusetshenziswa emabhokisini okugcwala avinjelwe isikhala. Ukuqondiswa kwe-tandem (ngokuvamile i-Arrangement 2) kubeka zombili izindandatho zibheke ohlangothini olufanayo, okuvumela isivalo sangaphandle ukuthi siphathe ingcindezi yenqubo ephelele uma isivalo sangaphakathi sehluleka, okwenza kube ukukhetha okuthandwayo kwezinsizakalo zokufutha ezinomfutho ophezulu.

Isikhathi Sokusebenzisa Isivalo Esiphindwe Kabili Semishini

Ukucacisa uphawu oluphindwe kabili lwemishini kudinga ukulinganisela izindleko zokuqala eziphezulu zemali ngokumelene nesidingo sokusebenza. Akuwona wonke uketshezi olunamandla oludinga uphawu oluphindwe kabili; ukuthuthukiswa kwezinto zobuso bophawu olulodwa kanye nezinhlelo zokuhlanza kuye kwandisa amakhono azo. Kodwa-ke, imikhawulo ethile yokusebenza kanye nezici zoketshezi kudala imithwalo engaxoxiswani yokusetshenziswa kophawu oluphindwe kabili.

Onjiniyela kumele bahlole ngokuhlelekile izakhiwo zomzimba zoketshezi lwenqubo, indawo yokusebenza, kanye nemiphumela yokwehluleka ukunquma ukuthi ukushintshela kusuka kuphawu olulodwa kuya kolubili kuvunyelwe yini ngokobuchwepheshe nangokwezomnotho.

Izimo zesevisi ezivumela ukusetshenziswa

Izimo eziningana ezinzima zesevisi zivumela ngokwemvelo ukuba yinkimbinkimbi kwesivalo esikabili. Uketshezi olunezinga eliphezulu lezinhlayiya ezihuzukayo—ngokuvamile ezidlula u-10% wezinto eziqinile ngesisindo—luzowohloza ngokushesha ubuso besivalo esisodwa. Isivalo esiphindwe kabili esicindezelwe sihlukanisa lobu buso nezivalo ngokuphelele.

Ngaphezu kwalokho, uketshezi olunamafutha amancane, njengama-hydrocarbon alula anokukhanya okungaphansi kuka-0.5 cP, izinyibilikisi ezingagcobi, noma amanzi ashisayo, zivame ukushanela zibe umhwamuko ebusweni obubodwa besivalo, okubangela ukugeleza okomile kanye nokuqhekeka kokushisa. Uketshezi olusebenzayo olusebenza eduze komfutho walo womusi ludinga ukusethwa kwesivalo esikabili lapho uketshezi oluqinile, oluvimbela ukugcoba lungagcina ifilimu ebalulekile yoketshezi phakathi kobuso obujikelezayo nobungaguquki.

Izindlela zokukhetha ezibalulekile

Izindlela zokukhetha eziyinhloko zigxile ezingozini zokushisa, ingcindezi, ubuthi, kanye ne-polymerization. Izicelo ezisebenza emazingeni okushisa aphezulu (isb., ngaphezu kuka-200°C / 400°F) zivame ukudinga izivalo ezimbili ezine-loop yangaphandle yokupholisa ukuze kugcinwe ubuso besivalo ngaphakathi kwemingcele yabo yokushisa futhi kuvinjelwe ukuwohloka kwe-elastomer.

Uketshezi olupholishayo, oluqina noma olucwebezelayo lapho luthintana nomoya-mpilo womoya, luyinselele eyingqayizivele. Uma kusetshenziswa uphawu olulodwa, ukuvuza okuncane komoya kuzocwebezela ohlangothini lomoya wophawu, okuholela ekugugeni okusheshayo nokulenga kwama-O-rings ashukumisayo. Uphawu oluphindwe kabili olunoketshezi oluvimbelayo oluhambisanayo luvimbela ukuvezwa komoya kanye nokwakheka koketshezi okulandelayo.

Umsebenzi wokukhetha osebenzayo

Umsebenzi osebenzayo wokukhetha uphawukufanele zilandele izinhlaka zemboni ezisunguliwe, njengenqubo yokukhetha i-API 682 Annex A. Umsebenzi uqala ngokuhlonza ukuhlukaniswa kwezingozi zoketshezi. Uma uketshezi lunobuthi obukhulu noma luvutha kakhulu, i-Arrangement 3 (uphawu oluphindwe kabili olucindezelwe) ikhethwa ngokuzenzakalelayo.

Uma uketshezi lungeyona ingozi, unjiniyela uhlola izakhiwo zomzimba zoketshezi (isb., imingcele yomhwamuko engaphansi kwebha engu-0.35, ukuqina okungaphansi kuka-0.5 cP, noma imithwalo yezinhlayiya edlula u-10%). Uma lezi zakhiwo ziwela ngaphandle kwemingcele yokusebenza yesivalo esisodwa, ukuhamba komsebenzi kuya ku-Arrangement 2 (isivalo esiphindwe kabili esingacindezelwanga) noma i-Arrangement 3, kuye ngokuthi umgomo oyinhloko uwukugodla okuyisipele noma ukuhlukaniswa kobuso ngokuphelele.

Ukuncintisana Kobunjiniyela Nokuhambisana Nemithetho

Ukuqaliswa kwesivalo esiphindwe kabili somshini akulona neze ukuthuthukiswa kwemishini okuzimele; kudinga ukuhlanganiswa kwezinhlelo zokusekela eziyinkimbinkimbi. Lezi zinhlelo zilawula ingcindezi, izinga lokushisa, kanye nokuhlanzeka kwe-buffer noma uketshezi lokuvimbela, futhi ukwakheka kwazo kubaluleke kakhulu njengesivalo ngokwaso.

Onjiniyela babhekene nezindlela eziningi zokushintshana lapho beklama lezi zinhlelo, belinganisa ukuhambisana okuqinile nezindinganiso zomhlaba wonke ngokumelene nemikhawulo yesikhala esibonakalayo sesitshalo, ukutholakala kwezinsizakusebenza, kanye nokuhambisana kwezinto.

Izinhlelo zokusekela kanye nezinhlelo ze-API

Izivalo ezimbili zithembele ngokuphelele ezinhlelweni zamapayipi e-API ukuze zisebenze. Isivalo ezimbili esingacindezelwanga ngokuvamile sisebenzisa i-API Plan 52, ejikeleza uketshezi lwe-buffer kusuka echibini langaphandle (ngokuvamile elingamalitha ayi-12 kuya kwangu-20 ngomthamo, eklanyelwe ukukhipha ukushisa kobuso be-seal okungu-1 kuya ku-5 kW). Lolu hlelo ludinga uxhumano nohlelo lokubuyisa i-flare noma i-vapor ukuze kulawulwe ngokuphephile ukuvuza kwesivalo ngaphakathi.

Izivalo ezimbili ezicindezelwe zisebenzisa i-API Plan 53 (A, B, noma C) noma i-Plan 54. I-Plan 53A isebenzisa i-reservoir ecindezelwe yigesi, ekhawulelwe ku-10.3 bar (150 psi) ukuvimbela ukumuncwa kwegesi ku-barrier fluid. Ngezingcindezi eziphakeme, i-Plan 53B isebenzisa i-bladder accumulator, kuyilapho i-Plan 53C isebenzisa i-piston accumulator eqhutshwa yi-process pressure. I-Plan 54, eyinkimbinkimbi kakhulu, isebenzisa i-external lubrication skid ephakathi ukuze inikeze i-barrier fluid kuma-pump amaningi ngesikhathi esisodwa.

Izinto zokwakha, ukupholisa, kanye nomklamo wamapayipi

Ukukhethwa kwezinto ngaphakathi kwesistimu yesivalo kanye nokusekela kumele kubhekele kokubili indlela yokusebenza kanye noketshezi lokuvimba. Ubuso besivalo buvame ukwakhiwa ngezinto zekhwalithi ephezulu njenge-sintered Silicon Carbide (SiC) noma i-Nickel-bound Tungsten Carbide (TC) ukuze kusingathwe amanani aphezulu okucindezela (PV), avame ukwedlula ama-bar-m angu-35,000 (1,000,000 psi-ft/min).

Izinto zokuvala zesibili (ama-O-rings) zilawula imingcele yokushisa yesistimu. Ngenkathi ama-Fluoroelastomers ajwayelekile (i-FKM) efanelekile kufika ku-200°C, ama-Perfluoroelastomers akhethekile (i-FFKM) ayadingeka emazingeni okushisa asondela ku-320°C (608°F). Ngaphezu kwalokho, ukwakheka kwamapayipi ezimbobo zokupholisa kumele kunciphise ukulahlekelwa kokungqubuzana; ukusebenzisa amapayipi amancane kunobubanzi obungu-0.5 inches (12.7 mm) kungavimbela ukuhamba kwe-thermosyphon, okuholela ekushiseni ngokweqile kwesivalo okubi kakhulu.

Ukuthobela imithetho kanye nezindinganiso zezitshalo

Ukuhambisana nezindinganiso zomhlaba wonke kuqinisekisa ukuphepha okuyisisekelo kanye nokuthembeka kodwa kwethula imikhawulo ebalulekile yobunjiniyela. Emikhakheni kawoyela, igesi, kanye ne-petrochemical, i-API 682 (Uhlelo lwesi-4) kanye ne-ISO 21049 kuchaza izidingo eziqinile zobukhulu begumbi lokuvala, izinqubo zokuhlola iziqu eziguquguqukayo zamahora ayi-100, kanye nokufakwa kwezinsimbi.

Ezikhungweni ezisebenza ezindaweni eziqhumayo, ukuhambisana ne-ATEX Directive (eYurophu) noma

Indlela Yokwenza Isinqumo Sokugcina

Izinto Ezibalulekile Okufanele Uzicabangele

• Iziphetho ezibaluleke kakhulu kanye nesizathu se-Double Mechanical Seal
• Imininingwane, ukuhambisana, kanye nokuhlolwa kwengozi okufanele kuqinisekiswe ngaphambi kokuthi uzibophezele
• Izinyathelo ezilandelayo ezisebenzayo kanye nezixwayiso abafundi abangazisebenzisa ngokushesha

imibuzo ejwayelekile ukubuzwa

Kufanele kusetshenziswe nini uphawu oluphindwe kabili lwemishini?

Sebenzisa uma i-media epompiwe inobuthi, ivutha kalula, ihudula, ishisa kakhulu, noma ingase ikhiqize amakristalu, futhi uma ukuvuza kufanele kuncishiswe ukuze kuphephe noma kuhambisane nomthetho.

Kungani uphawu oluphindwe kabili lwemishini lungcono kunophawu olulodwa olusemsebenzini oyingozi?

Ingeza isikhombikubona sesibili sokuvala kanye ne-buffer noma uketshezi lokuvimba, ngakho-ke uma uphawu oluyinhloko lonakala, ukuvuza kugcinwa isikhathi eside ngokwanele ukuze kulungiswe noma kucinywe okulawulwayo.

Uyini umehluko phakathi koketshezi oluvimbayo noketshezi oluvimbelayo?

Uketshezi lwe-buffer luvame ukungacindezelwa futhi lusekela uphawu lwangaphandle; uketshezi oluvimbelayo lucindezelwa ngaphezu kokucindezela kwegumbi lophawu ukuze kuvinjelwe uketshezi lwenqubo ukuthi lungafiki emkhathini.

Ingabe i-Victor Seals ingahlinzeka ngezimpawu ezimbili zemishini ezihambisana ne-OEM zamaphampu ezimboni?

Yebo. I-Victor Seals inikeza izixazululo zokuvala ezihambisana ne-OEM kanye nezokushintshwa kwezinhlobo eziningi zamaphampu ezisetshenziswa ekusetshenzisweni kwamakhemikhali, olwandle, uwoyela negesi, kanye namanzi.

Ukuvalwa okuphindwe kabili komshini kunganciphisa kanjani isikhathi sokungasebenzi kokulungiswa kwephampu?

Ngokugcina ubuso besivalo bupholile, buhlanzekile, futhi bugcotshwe kangcono, kunciphisa ukusebenza okomile, ukuguguleka, kanye nokuvuza okungazelelwe, okusiza ukwandisa isikhathi sokuphila kwesivalo futhi kunqande ukumiswa okungahleliwe.