Inqubo Yokukhiqiza I-Sulfuric Acid
I-Sulfuric acid (H₂SO₄) ingenye yamakhemikhali ezimboni abaluleke kakhulu emhlabeni. Ivame ukubizwa ngokuthi "umgogodla wemboni yamakhemikhali" ngenxa yezicelo zayo ezibanzi: kusukela ekukhiqizweni komanyolo we-phosphate kanye ne-ammonium sulfate, ngokucubungula uphethiloli, ukuhluzwa kwensimbi, ukukhiqizwa kwebhethri le-lead-acid, kuya ezimbonini zezindwangu nezokwelapha. Isidingo esikhulu se-sulfuric acid siholele ekuthuthukisweni kwezinqubo zokukhiqiza ezisebenzayo, ezonga imali, nezinobungani nemvelo. Njengamanje, indlela evame kakhulu esetshenziswa esikalini sezimboni yi-Contact Process, ethatha indawo yezindlela ezindala njenge-Lead Chamber Process.
Ukubuka konke kokukhiqizwa kwe-Sulfuric Acid
Ngokuvamile, ukukhiqizwa kwe-sulfuric acid ngeNqubo Yokuxhumana kuhilela izigaba eziningana eziyinhloko: (1) ukwakheka kwe-sulfur dioxide (SO₂), (2) ukuhlanzwa nokomiswa kwegesi, (3) ukushiswa kwe-SO₂ ku-sulfur trioxide (SO₃) nge-catalyst, (4) ukumuncwa kwe-SO₃ ku-sulfuric acid egxilile ukuze kwakheke i-oleum, kanye (5) ukuxutshwa kwe-oleum ku-sulfuric acid ngokuhlushwa okufunwayo. Isigaba ngasinye sidinga ukulawulwa okuqinile kokushisa, ingcindezi, kanye nokwakheka kwegesi ukuze kutholakale isivuno esiphezulu futhi kuncishiswe ukukhishwa kwegesi okuyingozi.
1. Ukwakheka kwe-Sulfur Dioxide (SO₂)
Izinto zokusetshenziswa eziyinhloko ekukhiqizweni kwe-sulfuric acid kungaba yi-elemental sulfur, igesi ye-H₂S evela ezindaweni zokuhlanza uwoyela, noma ama-ore e-sulfide ensimbi (isb., i-pyrite FeS₂). Indlela evame kakhulu ukushisa i-elemental sulfur emoyeni owomile:
Ama-S+ O₂(g) → SO₂(g)+ amandla
Lokhu kusabela kuyi-exothermic (kukhulula ukushisa). Ukushisa okuvelayo kuvame ukusetshenziselwa ukukhiqiza umusi, ngakho-ke izitshalo ze-sulfuric acid zivame ukuhlanganiswa nezinhlelo zokubuyisa amandla. Uma i-feedstock iyi-sulfide ore, i-ore iyagaywa ukuze ikhiqize i-SO₂. Kodwa-ke, ukusetshenziswa kwe-elemental sulfur kuvame ukukhiqiza igesi ehlanzekile futhi kwenza inqubo yokuhlanza ibe lula.
2. Ukuhlanzwa Nokomiswa Kwegesi
Amagesi okushisa awagcini nje ngokuqukatha i-SO₂ ne-N₂ emoyeni, kodwa futhi angathwala uthuli, umhwamuko wamanzi, nokunye ukungcola okufana nama-arsenic compounds noma ama-catalyst particles uma evela e-ore. Lokhu kungcola kuyingozi ngoba kungalimaza i-catalyst ngesikhathi sesigaba se-oxidation. Ngakho-ke, igesi kumele icutshungulwe ngeyunithi yokuhlanza, isibonelo:
– Isihlukanisi sesiphepho noma i-electrostatic precipitator ukuze ibambe uthuli/izinhlayiya ezincane
– Hlanza ukuze unciphise ukungcola okuthile okuncibilikayo
– Umshini wokomisa (umbhoshongo wokomisa) osebenzisa i-sulfuric acid egxilile ukuze umunce umhwamuko wamanzi
Ukomisa igesi kubaluleke kakhulu ngoba ukuba khona kwamanzi kungabangela ukwakheka kwenkungu ye-asidi, kuphazamise inqubo yokumunca i-SO₃, futhi kwandise ukugqwala emishinini.
3. Ukushiswa kwe-SO₂ ku-SO₃ (Isigaba Esiyinhloko Senqubo Yokuxhumana)
Isinyathelo esiyinhloko seNqubo Yokuxhumana ukushiswa kwe-sulfur dioxide ibe yi-sulfur trioxide:
2 SO₂ (g) + O₂ (g) ⇌ 2 SO₃ (g)
Lokhu kusabela kuyi-exothermic futhi kuyi-equilibrium reaction. Ngokombono, amazinga okushisa aphansi asekela ukwakheka kwe-SO₃ (ngoba ukusabela kuyi-exothermic). Kodwa-ke, izinga lokushisa eliphansi kakhulu lehlisa izinga lokusabela. Ngakho-ke, imboni ikhetha izimo ezifanele: izinga lokushisa elicishe libe ngu-400–450°C kanye nengcindezi eseduze nengcindezi yomoya (noma ephakeme kancane). Ukuze kusheshiswe ukusabela, kusetshenziswa i-catalyst ye-vanadium(V) oxide (V₂O₅), ebekwa embhedeni we-catalyst ku-converter.
Ama-converter ngokuvamile anemibhede eminingi ye-catalyst enesistimu yokupholisa. Lokhu kuqinisekisa ukuthi izinga lokushisa lihlala ngaphakathi kwebanga elifanele: uma kushisa kakhulu, ukulingana kubuyela ku-SO₂, kuyilapho i-catalyst ingabhekana nokusebenza okunciphile emazingeni okushisa aphezulu.
Ukuze kuthuthukiswe ukusebenza kahle nokulawula ukukhishwa kwegesi, izitshalo eziningi zesimanje zisebenzisa uhlelo lwe-Double Contact Double Absorption (DCDA). Kulolu hlobo lokucushwa, igesi idlula ku-converter, lapho enye ye-SO₃ imuncwa khona, bese igesi ibuyiselwa ku-converter ukuze i-oxidation iqhubeke ngaphambi kokumuncwa kokugcina. Umphumela uba ukuguqulwa kwe-SO₂ okuphezulu kanye nokukhishwa kwegesi okuphansi.
4. Ukumuncwa kwe-SO₃ kanye nokwakheka kwe-Oleum
Isinyathelo esilandelayo ukubamba i-SO₃. Uma uqala ukubona, kubonakala kulula ukumane uphendule i-SO₃ ngamanzi:
SO₃ (g) + H₂O (l) → H₂SO₄ (l)
Kodwa-ke, emisebenzini yezimboni, ukusabela okuqondile namanzi kudala inkinga enkulu: I-SO₃ isabela ngokushesha kakhulu futhi ikhiqize inkungu ye-sulfuric acid okunzima ukuyihlanganisa nokuyimunca, ngaleyo ndlela yandisa ukulahleka komkhiqizo kanye nezingozi zokukhishwa komoya. Ngakho-ke, i-SO₃ ayimuncwa ngamanzi, kodwa yi-sulfuric acid egxilile (ngokuvamile i-98%) ukuze yakhe i-oleum (i-sulfuric acid engaphezu kwe-SO₃):
SO₃ (g) + H₂SO₄ (l) → H₂S₂O₇ (l)
I-Oleum (H₂S₂O₇) ibizwa nangokuthi i-pyrosulfuric acid. “Iyindlela yokugcina” ye-SO₃ okulula ukuyiphatha ezinhlelweni zoketshezi. Ukumunca i-SO₃ ku-sulfuric acid egxilile kusiza nokuvimbela ukwakheka kwenkungu ye-asidi futhi kwandisa ukusebenza kahle kokumunca.
5. Ukuxutshwa kwe-Oleum ibe yi-Sulfuric Acid
Uma i-oleum isivele yakhekile, isinyathelo sokugcina ukukhiqiza i-sulfuric acid ekugxilweni okufanelekela isidingo semakethe, njengo-98% wokusetshenziswa kwezimboni okuvamile noma amazinga aphansi ezicelo ezithile. Ukuncibilikiswa kutholakala ngokungeza amanzi ngendlela elawulwayo:
I-H₂S₂O₇ (l) + I-H₂O (l) → 2 I-H₂SO₄ (l)
Lokhu kuncibilikiswa nakho kuyindlela yokusabela exothermic, ngakho-ke kumele kwenziwe ngokulawula izinga lokushisa okuqinile kanye nezinqubo zokuphepha. Umkhuba wokuphepha owaziwayo ukufaka i-asidi emanzini, hhayi okuphambene nalokho, ukuvimbela ukuchitheka ngenxa yokushisa okungazelelwe. Ezingeni lezimboni, izinhlelo zokuxuba zakhiwe ngezifudumezi, izixubi, kanye nezinzwa zokushisa ukulawula ukukhishwa kokushisa okuvela ekusabela.
Izici Zokuphepha Nezemvelo
Ukukhiqizwa kwe-sulfuric acid kuhilela amagesi ayingozi (SO₂, SO₃) angabangela ukucasuka okukhulu kokuphefumula futhi afake isandla emvuleni ene-asidi uma ekhishwa emoyeni. Ngakho-ke, lesi sitshalo sisebenzisa:
1. Uhlelo lwe-DCDA kanye neyunithi yokumunca ukuze kukhuliswe ukuguqulwa kwe-SO₂ ibe yi-SO₃ nokunciphisa ukukhishwa kwegesi.
2. Isiqedi senkungu ukuze sibambe inkungu ye-asidi emgudwini wegesi ngaphambi kokuba ikhishwe ngeshimini.
3. Izinto ezingamelani nokugqwala (isib. izinsimbi ezithile, ama-alloy akhethekile, noma izembozo ezivikelayo) ngoba i-H₂SO₄ igqwala kakhulu, ikakhulukazi ekujuleni okuthile kanye namazinga okushisa athile.
4. Ukuqapha okuqhubekayo kokukhishwa komoya ukuqinisekisa ukuthi ukusebenza kwemvelo kuhambisana nemithethonqubo.
Ngaphezu kwalokho, ukushisa kokusabela kwe-exothermic kuvame ukusetshenziswa ezinhlelweni zokubuyisa amandla, okwenza inqubo ibe ngcono kakhulu ngamandla futhi inciphise umthelela wekhabhoni.
I-Penutup
Izinqubo zokukhiqiza zesimanje ze-sulfuric acid zilawulwa yi-Contact Process ngenxa yokusebenza kwayo kahle, ikhwalithi yomkhiqizo omuhle, kanye nokukhishwa okulawulwayo ngobuchwepheshe obufana ne-DCDA. Izinyathelo ezibalulekile zifaka phakathi ukushisa kwe-sulfur ukukhiqiza i-SO₂, ukuhlanzwa kwegesi nokomisa, i-catalytic oxidation ku-SO₃, ukumuncwa kwe-SO₃ ku-sulfuric acid egxilile ukuze kwakheke i-oleum, bese kuncishiswa i-oleum ibe yi-sulfuric acid njengoba kudingeka. Ngemingcele yokusebenza elawulwayo, ukwakheka kwesitshalo okufanele, kanye nezinhlelo zokuphepha eziqinile kanye nezemvelo, imboni ingakhiqiza ngokwethembeka inani elikhulu le-sulfuric acid ukusekela imikhakha eyahlukene yezomnotho.
Uma ufisa, ngingakha inguqulo yalesi sihloko enesakhiwo sezemfundo (ngemibhalo engezansi ethi “isingeniso–indlela–imiphumela–ingxoxo”) noma ngengeze ishadi lokugeleza kwenqubo ukuze kube lula ukuyiqonda.
