Lissafin Ingancin Zafi a Injinan Tururi na Zamani
Sau da yawa ana ɗaukar injunan tururi a matsayin fasahar "na gargajiya" daga Juyin Juya Halin Masana'antu. Duk da haka, ƙa'idodinsu da ci gaban su sun kasance masu dacewa a yau, musamman a cikin tashoshin wutar lantarki na kwal (PLTU), shigarwar zafi da wutar lantarki (CHP), da tsarin turbine na tururi a cikin masana'antar sarrafawa. "Injinan tururi na zamani" suna nufin tsarin samar da wutar lantarki bisa zagayowar Rankine, waɗanda suka fi inganci fiye da injunan tururi na gargajiya, suna amfani da matsin lamba mai yawa da zafin jiki, masu dumama mai yawa, masu sake dumamawa, da dumama mai sabuntawa ta hanyar dumama ruwan abinci. Don fahimtar aikin waɗannan tsarin, ma'auni ɗaya mai mahimmanci wanda koyaushe ake ƙididdigewa shine ingancin zafi.
1. Asalin Ma'anar Ingantaccen Zafi
Ingancin zafi na injin tururi yana bayyana yawan makamashin zafi da aka shigar (daga ƙona mai ko tushen zafi) da aka yi nasarar mayar da shi aiki mai amfani, yawanci a cikin nau'in wutar lantarki ta shaft ɗin turbine ko wutar lantarki ta janareta. Gabaɗaya, ingancin zafi ana bayyana shi kamar haka:
\[
\eta_{th} = \frac{W_{net}}{Q_{in}}
\]
Ina:
– \( W_{net} \) shine aikin cibiyar zagayowar (aikin injin turbine ban da aikin famfo).
– \( Q_{in} \) shine shigarwar zafi zuwa zagayowar, wanda galibi yana faruwa a cikin tukunyar jirgi da/ko babban hita.
A cikin tsarin Rankine mai kyau, manyan abubuwan da ke cikinsa sun haɗa da famfo, tukunyar jirgi, injin turbine, da kuma injin condenser. Ana tura tururi (ruwan abinci) zuwa matsin lamba mai yawa, a dumama shi zuwa tururi (wanda aka cika ko aka yi zafi sosai), a faɗaɗa shi a cikin injin turbine don samar da aiki, sannan a mayar da shi ruwa a cikin injin condenser kafin a sake shiga famfon. Ingancin zafi shine babban ma'aunin yadda injin tururi ke amfani da makamashin zafi yadda ya kamata.
2. Tsarin Rakine Mai Kyau vs Na Gaskiya
A lissafin farko, injiniyoyi galibi suna farawa daga zagayowar Rankine mai kyau don samun ra'ayi game da iyakar inganci. Mafi kyawun zato yawanci sune:
1. Tsarin famfo da injin turbine na Isentropic (ba tare da asara ba).
2. Babu raguwar matsin lamba a cikin tukunyar jirgi, bututu, na'urar dumama ruwa, na'urar sake dumama ruwa, da na'urar sanyaya daki.
3. Babu asarar zafi ga muhalli.
4. Dankalin turawa da dumama suna faruwa ne a matsin lamba akai-akai.
A yanayin zahiri, waɗannan zato ba a cika su gaba ɗaya ba. Asarar gogayya, asarar matsi, da ingancin isentropic na famfo da injinan turbine ba su kai 100% ba. Saboda haka, ainihin ingancin zafi koyaushe yana ƙasa da ƙimar da ta dace, kuma dole ne lissafi ya haɗa da sigogi kamar:
– Ingancin injin turbine isentropic (\(\eta_t\))
– Ingancin Isentropic na famfo (\(\eta_p\))
– Asarar zafi (asarar zafi)
– Rage matsin lamba
3. Matakan Lissafin Ingancin Zafi (Tsarin Gabaɗaya)
Domin ƙididdige ingancin zafi na injin tururi na zamani (bisa ga Rankine), matakan gabaɗaya sune:
a) Ƙayyade Maki na Jiha
Yawanci ana yiwa alama kamar haka:
1. Mafarin famfo / mashigar ruwa (ruwa mai cike da ruwa a matsin lamba na matsewa)
2. Mashigar famfo / mashigar tukunyar jirgi (ruwan ciyarwa mai ƙarfi)
3. Wurin shigar da tukunya/wutar lantarki/wutar lantarki (busasshiyar tururi mai cikewa ko mai zafi sosai)
4. Mashigar injin turbine / mashigar na'urar sanyaya daki (cakuda da ruwan tururi ko danshi mai zafi sosai)
A cikin zagayowar da ke amfani da na'urorin dumama da sake farfaɗowa, adadin maki na yanayi yana ƙaruwa. Injunan tururi na zamani a manyan tashoshin wutar lantarki galibi suna da matakai da yawa na fitar da turbine da na'urorin dumama ruwan abinci, wanda hakan ke sa binciken ya fi rikitarwa, amma ƙa'idar ta kasance iri ɗaya: yi daidaiton kuzari akan kowane sashi.
b) Ɗauki Bayanan Kayayyakin Thermodynamic
Babban kadarori da ake buƙata:
– Enthalpy (\(h\)) a kowane lokaci
– Entropy (\(s\)) don hanyoyin isentropic
– Matsi (\(P\)) da zafin jiki (\(T\))
– Ingancin tururi (\(x\)) lokacin da yake cikin yankin matakai biyu
Ana ɗaukar wannan bayanin ne daga tebura ko manhajoji na tururi (EES, REFPROP, Aspen, ko kalkuleta na mallakar IAPWS/IF97).
c) Lissafi Aikin Famfo
Ana iya kimanta aikin famfo mai kyau kamar haka:
\[
W_p \approx v_f (P_2 – P_1)
\]
Inda \(v_f\) shine takamaiman adadin ruwa (m³/kg) a wurin shigar famfo. Don ainihin famfo:
\[
W_{p,ainihin} = \frac{W_{p,imade}}{\eta_p}
\]
Sai enthalpy da ke fitowa daga famfo:
\[
h_2 = h_1 + W_{p,ainihin}
\]
d) Lissafin Shigar da Zafi a cikin Boiler
Shigar da zafi gabaɗaya:
\[
Q_{in} = h_3 – h_2
\]
Idan akwai na'urar dumama mai ƙarfi, ƙimar \(h_3\) ita ce enthalpy na tururin da ke dumama sosai a wurin shigar injin turbine. Idan akwai na'urar dumama mai ƙarfi, akwai ƙarin shigarwar zafi ta biyu:
\[
Q_{in,jimla} = (h_3 – h_2) + (h_5 – h_4)
\]
(ya danganta da adadin maki akan zane).
e) Lissafin Aikin Injin Turbin
Don injin turbin da ya dace (isentropic), ana samun \(s_3 = s_{4s}\) da \(h_{4s}\) daga teburin. Don injin turbin na gaske:
\[
\eta_t = \frac{h_3 – h_{4,ainihin}}{h_3 – h_{4s}}
\Rightarrow h_{4,ainihin} = h_3 – \eta_t (h_3 – h_{4s})
\]
Aikin injin turbin:
\[
W_t = h_3 – h_{4,ainihin}
\]
Idan akwai matakai da yawa na faɗaɗawa ko sake dumamawa, jimlar aikin injin turbine shine jimlar kowane mataki.
f) Lissafa Aikin Yanar Gizo da Ingantaccen Zafi
\[
W_{net} = W_t – W_p
\]
\[
\eta_{th} = \frac{W_{net}}{Q_{in}}
\]
Wannan shine ginshiƙin lissafin ingancin zafi na zagayowar.
4. Misali Mai Kyau (Mai Sauƙi)
A ce wani sauƙaƙƙen zagayen Rankine na zamani yana da bayanai (a cikin nau'in enthalpies) da aka riga aka samo daga teburin tururi kuma yana la'akari da ingancin sassan:
– \(h_1 = 191 \, \text{kJ/kg}\) (ruwa mai cike da ruwa da ke barin na'urar dumama)
– \(h_2 = 200 \, \text{kJ/kg}\) (fitar famfo, ainihin)
– \(h_3 = 3500 \, \text{kJ/kg}\) (tururin da ke zafi sosai yana shiga injin turbin)
– \(h_4 = 2400 \, \text{kJ/kg}\) (fitar injin turbine, ainihin)
Don haka:
– Aikin injin turbin: \(W_t = 3500 – 2400 = 1100 \, \text{kJ/kg}\)
– Aikin famfo: \(W_p = 200 – 191 = 9 \, \text{kJ/kg}\)
– Aikin yanar gizo: \(W_{net} = 1100 – 9 = 1091 \, \text{kJ/kg}\)
– Shigar da zafi: \(Q_{in} = 3500 – 200 = 3300 \, \text{kJ/kg}\)
Ingancin zafi:
\[
\eta_{th} = \frac{1091}{3300} = 0.331 \kimanin 33.1\%
\]
Wannan ƙimar ta dace da zagayowar Rankine mai kyau, amma tashoshin wutar lantarki na zamani masu matuƙar mahimmanci na iya zama mafi girma idan aka yi la'akari da ingancin injina (kodayake har yanzu suna shafar tukunyar jirgi, na'urar sanyaya daki da asarar kayan taimako).
5. Abubuwan da ke ƙara Ingancin Injinan Tururi na Zamani
a) Ƙara zafin jiki da matsin lamba na tururin da ke shiga cikin injin turbin
Mafi girman matsakaicin zafin da aka ƙara zafi, haka nan ingancinsa ya fi girma (bisa ga ƙa'idar Carnot). Fasaha mai tsanani da ta wuce gona da iri tana ba da damar aiki a matsin lamba sama da ma'aunin ruwa (22,1 MPa), tana rage asarar da ke tattare da canje-canjen lokaci da kuma ƙara inganci.
b) Rage Matsi na Mai Rage Matsi (Mafi kyawun Injin Tsafta)
Rage matsin lamba na na'urar sanyaya iska yana ƙara yawan faɗaɗa injin turbin, wanda hakan ke ƙara ƙarfin injin turbin. Duk da haka, wannan yana iyakance ne ta hanyar zafin ruwan sanyaya, girman injin, da kuma haɗarin yawan danshi a matakan ƙarshe na injin turbin.
c) Sake Zafi Zagaye
Na'urar dumama tururin tana sake dumama tururin bayan an ƙara faɗaɗa shi kaɗan, sannan ta sake faɗaɗa shi. Sakamakon shine ƙara inganci da ƙarancin zafi a wurin fitar da turbin (mafi aminci ga ruwan turbin).
d) Sabuntawa (Dumama Ruwan Sha)
Ta hanyar ɗaukar ɗan tururin daga injin turbin don dumama ruwan abinci, tukunyar ba ta buƙatar samar da zafi mai yawa don isa wurin tafasa. Sabuntawa yana ƙara ingancin zagayowar, kodayake yana rage aikin injin turbin saboda wasu tururin ba sa samar da aiki a ƙarancin matsin lamba.
6. Bambanci tsakanin Ingantaccen Tsarin Zafin Zagaye da Ingantaccen Tsarin Samarwa
Yana da mahimmanci a rarrabe:
– Ingancin zafin zagayowar Rankine: bisa ga \(W_{net}/Q_{in}\) a cikin sassan zagayowar.
– Ingancin samar da wutar lantarki: yana la'akari da asarar konewa, ingancin tukunyar jirgi, asarar janareta, kayan taimako (famfo, fanka, na'urorin jigilar kaya), da asarar watsawa ta ciki.
A cikin tashoshin wutar lantarki da ke amfani da kwal, ingancin tukunyar jirgi da asarar tsarin na iya zama mai yawa. Saboda haka, ko da ingancin zafin zagayowar ya yi yawa, ingancin wutar lantarki gaba ɗaya na iya zama ƙasa.
7. Kammalawa
Lissafin ingancin zafi a cikin injunan tururi na zamani sun dogara ne akan ma'aunin kuzarin zagayowar Rankine: lissafin aikin turbine, aikin famfo, da shigarwar zafi zuwa tukunyar jirgi (da kuma sake dumamawa, idan akwai). Mabuɗin daidaito shine ainihin tantance maki na yanayi da halayen thermodynamic (enthalpy, entropy, ingancin tururi), da kuma haɗa yanayin duniya na gaske kamar ingancin isentropic da raguwar matsin lamba. Ingancin zafi shine babban alamar aikin tsarin kuma tushen kimanta ingantawa kamar ƙaruwar zafin jiki/matsi, sake dumamawa, sake farfadowa, da haɓaka condenser.
Idan kuna so, zan iya ƙara wani misali na lissafin "na zamani" (misali sake zagayowar dumama + na'urorin dumama ruwa 1-2) tare da tebura na matsayi da zane-zanen Ts don kimanta ainihin binciken shari'ar PLTU.
