Cavitation ndi vuto lowononga lomwe nthawi zambiri limapezeka mu ma centrifugal pumping units. Cavitation imatha kuchepetsa mphamvu ya mpope, kuyambitsa kugwedezeka ndi phokoso, ndikupangitsa kuwonongeka kwakukulu kwa chopondera, nyumba yapampu, shaft, ndi zina zamkati. Cavitation imachitika pamene kuthamanga kwa madzi mu mpope kumatsika pansi pa mphamvu ya vaporization, kuchititsa kuti thovu la nthunzi lipangidwe kumalo otsika kwambiri. Nthunzi iyi imagwa kapena "implode" mwamphamvu ikalowa m'dera lapamwamba kwambiri. Izi zitha kuwononga makina mkati mwa mpope, kupanga mfundo zofooka zomwe zimatha kukokoloka ndi dzimbiri, ndikusokoneza magwiridwe antchito a mpope.

Kumvetsetsa ndikukhazikitsa njira zochepetsera cavitation ndikofunikira kuti mukhalebe wokhulupirika komanso moyo wautumiki wa mapampu apakati apakati .

Mitundu ya Cavitation mu Mapampu

Kuchepetsa kapena kuteteza cavitation mu mpope, ndikofunika kumvetsetsa mitundu yosiyanasiyana ya cavitation yomwe ingachitike. Mitundu iyi ndi:

1.Vaporization cavitation. Imadziwikanso kuti "classic cavitation" kapena "net positive suction head available (NPSHa) cavitation," iyi ndi mtundu wamba wa cavitation. Gawani casing mapampu amawonjezera liwiro la madzimadzi akamadutsa mu dzenje loyamwa la chipolopolo. Kuwonjezeka kwa liwiro kumafanana ndi kuchepa kwa kuthamanga kwamadzimadzi. Kuchepetsa mphamvu kungachititse madzimadzi ena kuwira (nthunzi) ndi kupanga thovu la nthunzi, lomwe limagwa mwamphamvu ndi kutulutsa mafunde ang'onoang'ono ang'onoang'ono akafika kumalo othamanga kwambiri.

2. Chisokonezo cavitation. Zigawo monga zigongono, mavavu, zosefera, etc. mu dongosolo mapaipi sangakhale oyenera kuchuluka kapena chikhalidwe cha madzi amapopa, amene angayambitse eddies, chipwirikiti ndi kuthamanga kusiyana mu madzi. Zodabwitsazi zikachitika polowera mpope, zimatha kuwononga mkati mwa mpope kapena kupangitsa kuti madziwo asungunuke.

3. Blade syndrome cavitation. Amadziwikanso kuti "blade pass syndrome", mtundu uwu wa cavitation umachitika pamene choyikapo m'mimba mwake chimakhala chachikulu kwambiri kapena zokutira mkati mwa nyumba ya mpope ndi wandiweyani / mapampu amkati mkati mwake ndi ochepa kwambiri. Zina kapena zonsezi zidzachepetsa malo (chilolezo) mkati mwa nyumba ya mpope kukhala pansi pa milingo yovomerezeka. Kuchepa kwa chilolezo mkati mwa nyumba ya pampu kumapangitsa kuti madzi aziyenda bwino, zomwe zimapangitsa kuchepa kwa kuthamanga. Kuchepetsa kuthamanga kungayambitse madzimadzi kuti asungunuke, ndikupanga thovu la cavitation.

4.Internal recirculation cavitation. Pamene mpope wogawanika pakati sungathe kutulutsa madzimadzi pa mlingo wofunikira wothamanga, amachititsa kuti madzi ena kapena madzi onse azizunguliranso mozungulira. Madzi obwerezabwereza amadutsa m'malo otsika komanso othamanga kwambiri, omwe amatulutsa kutentha, kuthamanga kwambiri, ndikupanga thovu la vaporization. Chomwe chimayambitsa kubwereza kwamkati ndikuyendetsa mpope ndi valavu yotulutsa mpope yotsekedwa (kapena pamtunda wochepa).

5. Air entrainment cavitation. Mpweya ukhoza kukokeredwa mu mpope kudzera mu valve yolephera kapena yotayirira. Ukakhala mkati mwa mpope, mpweya umayenda ndi madzimadzi. Kusuntha kwa madzi ndi mpweya kungapangitse thovu zomwe "zimaphulika" zikakhudzidwa ndi kuwonjezereka kwa mphamvu ya mpope.

Zinthu zomwe zimathandizira ku cavitation - NPSH, NPSHa, ndi NPSHr

NPSH ndi chinthu chofunikira kwambiri popewa cavitation mu mapampu ogawanika. NPSH ndiye kusiyana pakati pa kuthamanga kwenikweni kwa kuyamwa ndi kuthamanga kwa nthunzi wamadzimadzi, kuyeza pa polowera pompo. Makhalidwe a NPSH ayenera kukhala okwera kwambiri kuti madzi asasunthike mkati mwa mpope.

NPSHa ndiye NPSH yeniyeni pansi pa machitidwe a mpope. Net positive suction mutu wofunikira (NPSHr) ndi NPSH yocheperako yotchulidwa ndi wopanga mpope kuti apewe cavitation. NPSHa ndi ntchito ya mapaipi oyamwa, kuyika, ndi magwiridwe antchito a mpope. NPSHr ndi ntchito ya kapangidwe ka pampu ndipo mtengo wake umatsimikiziridwa ndi kuyezetsa pampu. NPSHr imayimira mutu womwe umapezeka pansi pa mayesero ndipo nthawi zambiri umayesedwa ngati kutsika kwa 3% pamutu wa pampu (kapena mutu woyamba wa impeller wa mapampu a multistage) kuti azindikire cavitation. NPSHa iyenera kukhala yayikulu nthawi zonse kuposa NPSHr kupewa cavitation.

Njira Zochepetsera Cavitation - Wonjezerani NPSHa Kuti Mupewe Cavitation

Kuwonetsetsa kuti NPSHa ndi yayikulu kuposa NPSHr ndikofunikira kuti mupewe cavitation. Izi zitha kukwaniritsidwa ndi:

1. Kutsitsa kutalika kwa mpope wogawanika wofanana ndi posungira / sump. Mulingo wamadzimadzi mu posungira/sump ukhoza kuonjezedwa kapena mpope ukhoza kuyikidwa pansi. Izi zidzakulitsa NPSHa polowera pompo.

2. Wonjezerani kukula kwa mipope yoyamwa. Izi zimachepetsa kuthamanga kwamadzimadzi pafupipafupi, potero zimachepetsa kutayika kwa mutu pamapaipi ndi zolumikizira.

2.Kuchepetsa kutayika kwa mutu muzowonjezera. Chepetsani kuchuluka kwa zolumikizira pamzere wokokera pampu. Gwiritsani ntchito zomangira monga zigongono zazitali, ma valve odzaza, ndi zochepetsera zochepetsera kuti muchepetse kutayika kwa mutu chifukwa cha zolumikizira.

3.Pewani kuyika zowonetsera ndi zosefera pamzere wothira pampu ngati kuli kotheka, chifukwa nthawi zambiri zimayambitsa cavitation mu mapampu a centrifugal. Ngati izi sizingapewedwe, onetsetsani kuti zowonera ndi zosefera pa chingwe chokokera pampu zimawunikiridwa ndikuyeretsedwa nthawi zonse.

5. Muziziziritsa madzi opopa kuti muchepetse mphamvu ya nthunzi yake.

Kumvetsetsa NPSH Margin Kupewa Cavitation

NPSH malire ndi kusiyana pakati pa NPSHa ndi NPSHr. Mtsinje wokulirapo wa NPSH umachepetsa chiopsezo cha cavitation chifukwa umapereka chitetezo choteteza NPSHa kuti isagwe pansi pamiyezo yogwira ntchito chifukwa cha kusinthasintha kwa magwiridwe antchito. Zinthu zomwe zimakhudza malire a NPSH zimaphatikizapo mawonekedwe amadzimadzi, kuthamanga kwa pampu, ndi kuyamwa.

Kusunga Kuyenda Kochepa Pampu

Kuonetsetsa kuti pampu ya centrifugal ikugwira ntchito pamwamba pa kutsika kochepa komwe kumatchulidwa ndikofunikira kuti kuchepetsa cavitation. Kugwiritsira ntchito mpope wogawanika pansi pamtunda wake woyenda bwino (malo ovomerezeka ogwiritsira ntchito) kumawonjezera mwayi wopanga malo ochepetsetsa omwe angapangitse cavitation.

Zolinga Zopangira Impeller Kuti Muchepetse Cavitation

Mapangidwe a choyikapo chimagwira ntchito yofunikira ngati pampu ya centrifugal imakonda kukhala cavitation. Ma impellers akuluakulu okhala ndi masamba ochepa amatha kupereka kuthamanga kwamadzi pang'ono, zomwe zimachepetsa chiopsezo cha cavitation. Kuphatikiza apo, zotulutsa zokhala ndi mainchesi akulu olowera kapena masamba opindika zimathandizira kuyendetsa bwino kwamadzimadzi, kuchepetsa chipwirikiti ndi kuphulika. Kugwiritsa ntchito zinthu zomwe zimakana kuwonongeka kwa cavitation zimatha kukulitsa moyo wa impeller ndi mpope.

Kugwiritsa Ntchito Anti-Cavitation Devices

Zida zotsutsana ndi cavitation, monga zowonjezera zowonjezera zowonjezera kapena cavitation kupondereza liners, ndizothandiza kuchepetsa cavitation. Zipangizozi zimagwira ntchito poyang'anira mphamvu zamadzimadzi zomwe zimazungulira poyimitsa, zomwe zimapangitsa kuti zisamayende bwino komanso kuchepetsa chipwirikiti ndi madera otsika omwe amachititsa cavitation.

Kufunika Koyenera Pampu Kukula Popewa Cavitation

Kusankha mtundu wa pampu yoyenera ndikutchula kukula koyenera kwa ntchito inayake ndikofunikira kuti mupewe cavitation. Pampu yowonjezereka ikhoza kugwira ntchito moyenera pamtunda wotsika, zomwe zimapangitsa kuti pakhale chiwopsezo chowonjezereka cha cavitation, pomwe pampu yocheperako iyenera kugwira ntchito molimbika kuti ikwaniritse zofunikira zoyenda, zomwe zimawonjezera mwayi wa cavitation. Kusankhidwa koyenera kwa pampu kumaphatikizapo kusanthula mwatsatanetsatane kwazomwe zimafunikira, zachizolowezi komanso zochepa zoyenda, mawonekedwe amadzimadzi ndi dongosolo la dongosolo kuti zitsimikizire kuti pampu ikugwira ntchito mkati mwazomwe zimagwiritsidwa ntchito. Kukula kolondola kumalepheretsa cavitation ndikuwonjezera mphamvu ndi kudalirika kwa mpope m'moyo wake wonse.