Ho Baloa ha Bokgoni ba Thermal ho Lienjine tsa Mouoane tsa Sejoale-joale
Hangata dienjene tsa mouoane di nkuwa e le theknoloji ya "khale" ho tloha Phetohelong ya Diindasteri. Leha ho le jwalo, melaomotheo le ntshetsopele ya tsona di ntse di le bohlokwa le kajeno, haholoholo ditsing tsa motlakase tse sebedisang mashala (PLTU), ditsamaiso tsa mocheso le matla a kopaneng (CHP), le disistimi tsa turbine ya mouoane indastering ya tshebetso. "Dienjene tsa mouoane tsa sejwalejwale" di bua ka disistimi tsa tlhahiso ya motlakase tse thehilweng potolohong ya Rankine, tse sebetsang hantle haholo ho feta dienjene tsa mouoane tsa setso tse sebedisang kgatello e phahameng le mocheso, di-superheater, di-reheater le ho futhumatsa ho tsosolosang ka di-heater tsa metsi a fepang. Ho utlwisisa tshebetso ya disistimi tsena, parameter e le nngwe ya bohlokwa e dulang e balwa ke bokgoni ba mocheso.
1. Khopolo ea Motheo ea Bokhoni ba ho Futhumatsa
Bokgoni ba mocheso ba enjene ea mouoane bo hlalosa hore na ke bokae ba matla a mocheso a kenang (ho tsoa ho chesoeng ha mafura kapa mohloli oa mocheso) bo fetoloang ka katleho hore e be mosebetsi o molemo, hangata ka mokhoa oa matla a turbine shaft kapa matla a motlakase a jenereithara. Ka kakaretso, bokgoni ba mocheso bo hlalosoa e le:
\[
\eta_{th} = \frac{W_{net}}{Q_{in}}
\]
Di mana:
– \( W_{net} \) ke mosebetsi wa letlowa wa potoloho (mosebetsi wa turbine ntle le mosebetsi wa pompo).
– \( Q_{in} \) ke ho kenya mocheso potolohong, hangata ho etsahala ka har'a boiler le/kapa superheater.
Potolohong e ntle ea Rankine, likarolo tse ka sehloohong li kenyelletsa pompo, boiler, turbine le condenser. Mouoane o pompeloa (metsi a fepuoang) khatellong e phahameng, o futhumatsoa ho fihlela mouoane (o tletse kapa o futhumatsoa haholo), o atolosoa ka har'a turbine ho hlahisa mosebetsi, ebe o khutlisetsoa mokelikeling ka har'a condenser pele o kenngoa hape pompong. Bokhoni ba mocheso ke tekanyo ea mantlha ea hore na enjene ea mouoane e sebelisa matla a mocheso ka katleho hakae.
2. Potoloho e Loketseng Khahlanong le ea 'Nete ea Rankine
Lipalong tsa pele, baenjiniere hangata ba qala ho tloha potolohong e ntle ea Rankine ho fumana leseli la moeli o kaholimo oa katleho. Likhopolo tse ntle hangata ke:
1. Mokhoa oa pompo le turbine oa Isentropic (o se nang tahlehelo).
2. Ha ho na phokotso ea khatello ka har'a boiler, liphaephe, superheater, reheater le condenser.
3. Ha ho tahlehelo ea mocheso tikolohong.
4. Ho kolobisa le ho futhumatsa ho etsahala ka kgatello e sa fetoheng.
Maemong a sebele a lefats'e, likhakanyo tsena ha li fihlellehe ka botlalo. Tahlehelo ea khohlano, tahlehelo ea khatello, le bokhoni ba isentropic ba lipompo le liturbine li ka tlase ho 100%. Ka hona, bokhoni ba 'nete ba mocheso bo lula bo le tlase ho feta boleng bo loketseng, 'me lipalo li tlameha ho kenyelletsa liparamente tse kang:
– Bokgoni ba isentropic ba Turbine (\(\eta_t\))
– Bokgoni ba Isentropic ba pompo (\(\eta_p\))
– Tahlehelo ea mocheso (tahlehelo ea mocheso)
– Ho theoha ha khatello
3. Mehato ea ho Bala Katleho ea Thermal (Moralo o Akaretsang)
Ho bala bokgoni ba mocheso ba enjene ya mouoane ya sejwalejwale (e thehilweng ho Rankine), mehato e akaretsang ke ena:
a) Fumana Lintlha tsa Naha
Hangata e tšoauoa e le:
1. Sehokelo sa ho kenya/ho kenya pompo ya condenser (mokelikeli o tletseng ka kgatello ya condenser)
2. Pompo ea ho ntša metsi/sesebelisoa sa ho kenya boiler (metsi a ho fepa ka khatello e phahameng)
3. Setofo sa boiler/sehokelo sa superheater/sehokelo sa turbine (mouoane o omileng o tletseng kapa o chesang haholo)
4. Sehokelo sa ho kenya turbine/condenser (motswako wa mouoane le metsi kapa mongobo o chesang haholo)
Ka lipotoloho tse nang le li-heater tse nchafatsang le tsosoloso, palo ea lintlha tsa boemo e ea eketseha. Lienjine tsa mouoane tsa sejoale-joale lifemeng tse kholo tsa motlakase hangata li na le mekhahlelo e mengata ea ho ntša turbine le li-heater tsa metsi a fepang, e leng se etsang hore tlhahlobo e be e rarahaneng le ho feta, empa molao-motheo o lula o tšoana: etsa tekano ea matla karolong e 'ngoe le e 'ngoe.
b) Nka Lintlha tsa Thepa ea Thermodynamic
Matlo a mantlha a hlokahalang:
– Enthalpy (\(h\)) ntlheng ka 'ngoe
– Entropy (\(s\)) bakeng sa ditsamaiso tsa isentropic
– Kgatelelo (\(P\)) le mocheso (\(T\))
– Boleng ba mouoane (\(x\)) ha o le sebakeng sa mekhahlelo e 'meli
Hangata data ena e nkiloe litafoleng tsa mouoane kapa software (likhalkhuleita tsa thepa tsa EES, REFPROP, Aspen, kapa IAPWS/IF97).
c) Bala Mosebetsi oa Pompo
Mosebetsi o motle oa pompo o ka hakanngoa ka tsela ena:
\[
W_p \hoo e ka bang v_f (P_2 – P_1)
\]
Moo \(v_f\) e leng bophahamo bo itseng ba mokelikeli (m³/kg) monyakong wa pompo. Bakeng sa pompo ya nnete:
\[
W_{p,actual} = \frac{W_{p,ideal}}{\eta_p}
\]
Ebe enthalpy e tswang pompong e a tswa:
\[
h_2 = h_1 + W_{p,ea sebele}
\]
d) Bala Mocheso o Kentsweng ka Boiler
Ka kakaretso, ho kenya mocheso:
\[
Q_{ka hare} = h_3 – h_2
\]
Haeba ho na le superheater, boleng ba \(h_3\) ke enthalpy ea mouoane o chesang haholo ho keno ea turbine. Haeba reheater e le teng, ho na le tlhahiso ea bobeli e eketsehileng ea mocheso:
\[
Q_{kahare,kakaretso} = (h_3 – h_2) + (h_5 – h_4)
\]
(ho latela palo ea lintlha tse setšoantšong).
e) Bala Mosebetsi oa Turbine
Bakeng sa turbine e ntle (e nang le isentropic), \(s_3 = s_{4s}\) le \(h_{4s}\) di fumanwa tafoleng. Bakeng sa turbine ya nnete:
\[
\eta_t = \frac{h_3 – h_{4,actual}}{h_3 – h_{4s}}
\Motsu o nepahetseng h_{4,actual} = h_3 – \eta_t (h_3 – h_{4s})
\]
Ts'ebetso ea Turbine:
\[
W_t = h_3 – h_{4,ea sebele}
\]
Haeba ho na le mekhahlelo e mengata ea katoloso kapa ea ho futhumatsa hape, kakaretso ea mosebetsi oa turbine ke kakaretso ea mohato ka mong.
f) Bala Mosebetsi oa Marang-rang le Bokgoni ba Thermal
\[
W_{net} = W_t – W_p
\]
\[
\eta_{th} = \frac{W_{net}}{Q_{in}}
\]
Ena ke motheo oa palo ea katleho ea mocheso oa potoloho.
4. Mohlala o Hlalosang (O Bonolo)
A re re potoloho e bonolo ea sejoale-joale ea Rankine e na le data (ka mokhoa oa li-enthalpies) e seng e fumanoe litafoleng tsa mouoane 'me e nahanela bokhoni ba likarolo:
– \(h_1 = 191 \, \text{kJ/kg}\) (mokelikeli o tletseng o tsoa ka har'a condenser)
– \(h_2 = 200 \, \text{kJ/kg}\) (tlhahiso ea pompo, ea 'nete)
– \(h_3 = 3500 \, \text{kJ/kg}\) (mouoane o chesang haholo o kena ka har'a turbine)
– \(h_4 = 2400 \, \text{kJ/kg}\) (tlhahiso ea turbine, ea 'nete)
Kahoo:
– Mosebetsi oa Turbine: \(W_t = 3500 – 2400 = 1100 \, \text{kJ/kg}\)
– Mosebetsi oa ho pompa: \(W_p = 200 – 191 = 9 \, \text{kJ/kg}\)
– Mosebetsi wa inthanete: \(W_{net} = 1100 – 9 = 1091 \, \text{kJ/kg}\)
– Ho kenya mocheso: \(Q_{in} = 3500 – 200 = 3300 \, \text{kJ/kg}\)
Bokgoni ba ho futhumatsa:
\[
\eta_{th} = \frac{1091}{3300} = 0.331 \hoo e ka bang 33.1\%
\]
Boleng bona boa utloahala bakeng sa potoloho e ntle ea Rankine, empa limela tsa motlakase tsa sejoale-joale tse nang le matla a holimo haholo li ka ba holimo ha li talingoa e le bokhoni ba fektheri bo hloekileng (le hoja li ntse li angoa ke tahlehelo ea boiler, condenser le moroalo o thusang).
5. Mabaka a Eketsang Bokgoni ba Dienjene tsa Mouoane tsa Sejoale-joale
a) Eketsa mocheso le kgatello ya mouoane o kenang ka turbine
Ha mocheso o tloaelehileng oa ho eketsa mocheso o phahame, bokhoni boa eketseha (ho latela molao-motheo oa Carnot). Mahlale a Supercritical le Supercritical a lumella ts'ebetso likhatellong tse kaholimo ho ntlha ea bohlokoa ea metsi (22,1 MPa), a fokotsa tahlehelo e amanang le liphetoho tsa mekhahlelo le ho eketsa bokhoni.
b) Ho Fokotsa Khatello ea Condenser (Vacuum e Molemo)
Ho theola khatello ea condenser ho eketsa sebaka sa katoloso ea turbine, ka hona ho eketsa ts'ebetso ea turbine. Leha ho le joalo, sena se lekanyelitsoe ke mocheso oa metsi a pholileng, boholo ba condenser, le kotsi ea maemo a mongobo a phahameng mehatong ea ho qetela ea turbine.
c) Potoloho ea ho Futhumatsa Hape
Sefuthumatsi se futhumatsa mouoane hape ka mora ho atolosoa hanyane, ebe sea o atolosa hape. Sephetho ke bokgoni bo eketsehileng le boemo bo tlase ba mongobo sebakeng sa ho ntsha turbine (se bolokehileng bakeng sa mahare a turbine).
d) Tsosoloso (Ho Futhumatsa Metsi a Feeding)
Ka ho nka mouoane o itseng ho tsoa ho turbine ho futhumatsa metsi a fepang, boiler ha e hloke ho fana ka mocheso o lekaneng ho fihlela ntlha ea ho belisa. Nchafatso e ntlafatsa katleho ea potoloho, leha e fokotsa mosebetsi oa turbine hobane mouoane o mong ha o hlahise mosebetsi ka khatello e tlase.
6. Phapang pakeng tsa Bokgoni ba ho Futhumala ha Potoloho le Bokgoni ba ho Hlahisa Motlakase
Ho bohlokoa ho khetholla:
– Bokgoni ba mocheso ba potoloho ya Rankine: bo itshetlehile hodima \(W_{net}/Q_{in}\) dikarolong tsa potoloho.
– Bokgoni ba ho hlahisa motlakase ka botlalo: bo ela hloko tahlehelo ea ho tuka ha motlakase, bokgoni ba ho futhumatsa motlakase ka botlalo, tahlehelo ea jenereithara, meroalo e thusang (lipompo, lifene, li-conveyor), le tahlehelo ea phetisetso ea motlakase ka hare.
Litsing tsa motlakase tse sebelisoang ka mashala, bokhoni ba boiler le tahlehelo ea sistimi e ka ba kholo. Ka hona, leha bokhoni ba mocheso ba potoloho bo bonahala bo le holimo, bokhoni bohle ba netweke bo ka ba tlase.
7. Qetello
Lipalo tsa katleho ea mocheso lienjineng tsa mouoane tsa sejoale-joale li thehiloe ho leka-lekana ea matla a potoloho ea Rankine: ho bala mosebetsi oa turbine, mosebetsi oa pompo, le ho kenya mocheso ho boiler (le ho futhumatsa hape, haeba ho le joalo). Senotlolo sa ho nepahala ke ho fumana lintlha tsa boemo le thepa ea thermodynamic ka nepo (enthalpy, entropy, boleng ba mouoane), hammoho le ho kenyelletsoa ha maemo a 'nete a kang katleho ea isentropic le ho theoha ha khatello. Bokhoni ba mocheso ke sesupo sa mantlha sa ts'ebetso ea sistimi le motheo oa ho lekola ntlafatso joalo ka keketseho ea mocheso/khatello, ho futhumatsa hape, ho nchafatsa le ntlafatso ea condenser.
Haeba o lakatsa, nka eketsa mohlala wa dipalo wa "sejwalejwale" (mohlala, potoloho ya ho futhumatsa hape + dihitara tsa metsi a fepang tse 1-2) tse felletseng ka ditafole tsa dintlha tsa boemo le di-diagram tsa Ts ho hakanya thuto ya nnete ya nyeoe ya PLTU.
