Dilihat dari phase-nya, boiler terbagi menjadi 3 yaitu
:
- Subcritical Boiler
Subcritical artinya adalah phase yang terbentuk
di boiler tidak homogen (masih bisa
dibedakan antara cair dan uap) sehingga tipe boiler ini membutuhkan steam drum / boiler drum
untuk memisahkan kedua phase untuk lanjut dipanaskan kembali menjadi superheated steam yang digunakan untuk memutar sudu turbine. Operasi subcritical boiler adlalah pada < 22,1 MPa (1 bar = 0,98 kgf / cm2
= 0,1 MPa). Contoh operasi boiler P = 170 bar dan T = 540 oC
mempunyai efisiensi 32 - 38 %.
"Subcritical is not homogeneous produced phase in Boiler (still can be distinguished between liquid and vapor) so that this types Boiler requires a Steam Drum to separate 2 phases before it is used to rotate Turbine Blade. Subcritical Boiler operation 22,1 MPa (1 bar = 0,98 kgf / cm2 = 0,1 MPa). Examples Boiler operation are P = 170 bar dan T = 540 oC has the efficiency of 32 - 38 %."
"Subcritical is not homogeneous produced phase in Boiler (still can be distinguished between liquid and vapor) so that this types Boiler requires a Steam Drum to separate 2 phases before it is used to rotate Turbine Blade. Subcritical Boiler operation 22,1 MPa (1 bar = 0,98 kgf / cm2 = 0,1 MPa). Examples Boiler operation are P = 170 bar dan T = 540 oC has the efficiency of 32 - 38 %."
- Supercritical Boiler
Supercritical artinya keadaan substansi dimana
tidak bisa dibedakan antara phase cair dan uap (kedua phase homogen) dan tipe boiler ini tidak membutuhkan steam drum
sehingga sering disebut once through boiler (boiler satu kali lewatan
dimana air masuk langsung menjadi steam dan langsung digunakan untuk memutar sudu turbine).
Air mencapai keadaan critical pada
tekanan 22,1 MPa, jadi operasi supercritical boiler > 22,1 MPa. Contoh operasi boiler ini
adalah P = 250 bar dan T = 615 oC mempunyai efisiensi 37 - 42 %.
"Supercritical is substance condition which it can not be distinguished between liquid and vapor phases (2 phases is homogeneous) and this types a Boiler no requires Steam Drum so that called One Through Boiler ( one through direct to be used to rotate Turbine Blade). Water reach Critical Point at pressure 22,1 MPa, so operating of Supercritical Boiler must > 22,1 MPa. Examples Boiler operating are P = 250 bar dan T = 615 oC has the efficiency of 37 - 42 %."
"Supercritical is substance condition which it can not be distinguished between liquid and vapor phases (2 phases is homogeneous) and this types a Boiler no requires Steam Drum so that called One Through Boiler ( one through direct to be used to rotate Turbine Blade). Water reach Critical Point at pressure 22,1 MPa, so operating of Supercritical Boiler must > 22,1 MPa. Examples Boiler operating are P = 250 bar dan T = 615 oC has the efficiency of 37 - 42 %."
- Ultra Supercritical Boiler
Boiler supercritical & ultra supercritical didesain dengan konstruksi metalurgi yang sangat baik
(high grade quality) karena tidak
adanya steam drum, sehingga
konstruksi boiler dan turbine dijaga jangan sampai terdapat reaksi kerak dan
korosi. Contoh operasi ultra supercritical boiler adalah pada P = 300 bar dan T = 630 oC mempunyai
efisiensi 43 - 45 %.
Penambahan tingkat efisiensi boiler berdampak
menurunnya biaya operasional dan mengurangi emisi CO2
"Supercritical Boiler designed with the best metallurgical construction (high grade quality) because it is no Steam Drum, so that construction Boiler and Turbine are guarded from reaction of scale and corrosion. Examples Ultra Supercritical Boiler operating are P = 300 bar and T = 630 oC has the efficiency of 43 - 45 %.
The addition degree of Boiler efficiency has effect decreasing operational cost and reduce CO2 emissions."
"Supercritical Boiler designed with the best metallurgical construction (high grade quality) because it is no Steam Drum, so that construction Boiler and Turbine are guarded from reaction of scale and corrosion. Examples Ultra Supercritical Boiler operating are P = 300 bar and T = 630 oC has the efficiency of 43 - 45 %.
The addition degree of Boiler efficiency has effect decreasing operational cost and reduce CO2 emissions."
 |
| Rankine Cycle with Superheater |
Keterangan :
1 - 2 : Siklus
awal yaitu air dipompa dari tekanan rendah ke tekanan tinggi (menggunakan pompa BFP) yang kemudian dilewatkan ke pre-boiler (economizer) untuk dipanaskan awal, sehingga temperatur pelan-pelan naik
2 - 3 : Proses
pemanasan di boiler pada tekanan
tetap, sehingga air berubah menjadi saturated steam dan entropi naik (energi per satuan temperatur yang tidak bisa digunakan untuk melakukan kerja)
3 - 3' : saturated steam yang terbentuk harus
dipanaskan lagi sehingga temperaturnya naik yang berimbas juga pada tekanan naik dan berubah
menjadi superheated steam. Kenaikan pressure inilah yang digunakan untuk memutar sudu turbine
3' - 4' : superheated steam telah digunakan untuk
memutar sudu turbine tekanan tinggi sehingga
temperatur dan tekanan pelan-pelan turun
4' - 4 : entropi terus turun karena mengikuti penurunan temperatur namun energi yang ada pada steam masih bisa dinaikkan lagi temperaturnya (reheater) pada siklus 4 - 3 sehingga bisa digunakan untuk memutar sudu turbine tekanan rendah
4' - 4 : entropi terus turun karena mengikuti penurunan temperatur namun energi yang ada pada steam masih bisa dinaikkan lagi temperaturnya (reheater) pada siklus 4 - 3 sehingga bisa digunakan untuk memutar sudu turbine tekanan rendah
4 - 1 : Setelah
tekanan menjadi rendah, low pressure steam diubah menjadi air lagi di condenser
Siklus terjadi terus menerus dalam keadaan tertutup (close cycle) dan proses inilah yang terjadi di
PLTU.
"Description :
1 - 2 : the first cycle is water pumped from low pressure to high pressure (BFP) then to Pre Boiler (Economizer) to be heated so that rising temperature
2 - 3 : heating process in Boiler at constant pressure, so that water converted into Saturated Steam
3 - 3' : Saturated Steam that produced must be heated again so that rising temperature at constant pressure and changed to Superheated Steam
3' - 4' : Superheated Steam used to rotate Turbine Blade so that decreasing of temperature and pressure
4 - 1 : after pressure become low. Low Pressure steam converted into water in Condenser
The cycles occur continuously in close cycle and this is occuring process in PLTU"
Referensi :
[1] http://www.answers.com/Q/What_is_difference_between_subcritical_supercritical_boiler
[2] http://www.scribd.com/doc/87622501/Super-Critical-Boilers-vs-Sub-Critical-Boilers
[3]
http://www.nationalboiler.com/blog/boiler-repair/the-benefits-of-supercritical-boilers/
[4] http://www.slideshare.net/SHIVAJICHOUDHURY/super-critical-boiler
[5]
http://www.erc.uct.ac.za/jesa/volume19/19-1jesa-kapooria-etal.pdf
[6] https://en.wikipedia.org/wiki/Rankine_cycle
ARTIKEL TERKAIT :
1. Macam - Macam Boiler
2. Macam Cycle Proses
3. Boiler & Permasalahannya
ARTIKEL TERKAIT :
1. Macam - Macam Boiler
2. Macam Cycle Proses
3. Boiler & Permasalahannya
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