60-150t/h Steam Boiler Project Introduction
1.CASE HISTORY
1.1 General
The power plant includes 4 boilers built on 1976-1977 and new fifth boiler built on 2002.
During last years of operation, the experienced several mechanical problems due to high corrosion of flue ducts flue gas exhausters, economizers, air preheaters and due
to failure of steam superheaters. At this time boilers are not capable to operate at full capacity and maintenance cost are veering.
Environmental problems were also experienced such as emissions of:
-Solid particulate
-CO
-SO3 and acid smut
1.2 Design characteristics of the boilers
| Nominal capacity for four boilers | Tons/hr | 120 |
| Nominal capacity for fifth boiler | Tons/hr | 150 |
| Minimum capacity | Tons/hr | 60 |
| Nominal superheated ste | - pressure , atg | 100 |
| - temperature ℃ | 540 | |
| Steam drum pressure | atg | 110 |
| Superheated steam temperature | Min, ℃ | 530 |
| Nom, ℃ | 540 | |
| Max, ℃ | 545 | |
| BVW temperature at economizer | Inlet: Min, ℃ | 140 |
| Nom, ℃ | 215 | |
| Max, ℃ | 225 | |
| Flue gas temperatures | ||
| - combustion chamber | ℃ | 1170 |
| - superheater Ⅰ inlet | ℃ | 970 |
| - superheater II inlet | ℃ | 865 |
| - superheater III inlet | ℃ | 690 |
| - Economizer inlet | ℃ | 520 |
| - Air preheater inlet | ℃ | 310 |
| - Stack inlet oc- actual | ℃ | 140 to 230 |
| BFW temperatures | ||
| - Economizer Ⅰ inlet | ℃ | 215 |
| - Economizer Ⅰ outlet | ℃ | 240 |
| - Economizer inlet | ℃ | 290 |
| - Economizer II outlet | ℃ | 315 |
| Steam temperatures: | ||
| - superheater Ⅰ inlet | ℃ | 317 |
| - superheater Ⅰ outlet | ℃ | 412 |
| - superheater III inlet | ℃ | 448 |
| - superheater III outlet | ℃ | 540 |
| Air temperatures: | ||
| - air preheater inlet | ℃ | 25 |
| - steam air heater outlet | ℃ | 110-120 |
| - air preheater outlet | ℃ | 240 |
| Flue gas pressures: | ||
| - Combustion chamber bottom | mm WG | ﹣15 |
| - Combustion chamber top | mm WG | ﹣﹣5 |
| - Steam superheater III in]et | mm WG | ﹣11 |
| - Steam superheater II in]et | mm WG | ﹣20 |
| - Economizer inlet | mm WG | ﹣35 |
| - Air preheater inlet | mm WG | ﹣35 |
| - Stack inlet | mm WG | ﹣180 |
| Air pressures: | ||
| - Air preheater inlet | mm WG | 350 |
| - Burners inlet | mm WG | 230 |
| stack | ||
| Internal diameter at top | m | 4.4 |
| Internal diameter at entry | m | 4.4 |
| Height aboveground | m | 120 |
| Fuel oil consumption for four boilers | Kg/hr | 8700 |
| Fuel oil consumption for fifth boiler | Kg/hr | 11200 |
| Overall efficiency | % of LHV | 90 |
| Volumetric heat load | Kcal/m³ | 233 000 |
| Air fan capacity | m³/hr | 2x70 000 |
| - Discharging head | mm WG | 520 |
| - Operating temperature | C° | 25 |
| - Driver | E1 motor 6 KV | |
| - Driver power | KW | 200 |
| - Driver speed | RMP | 750 |
| Flue gas fan: | ||
| Capacity | m³/hr | 230 000 |
| Discharge head | mm WG | 260 |
| Operating temperature | C° | 180 |
| Driver | E1 motor 6 kv | |
| Driver power | KW | 315 |
| Driver speed | RMP | 750 |
| Heat transfer surface: | ||
| Radiant section | m2 | 307 |
| Convection section | m2 | 39 |
| Steam super heater1 | m2 | 140.8 |
| Steam super heater II | m2 | 660 |
| Steam super heater III | m2 | 550 |
| Economizer 1 | m2 | 660 |
| Economizer II | m2 | 640 |
| Air preheater1 | m2 | 1290 |
| Air preheater II | m2 | 1290 |
| Air preheater III | m2 | 1290 |
1.3 Brief description of boilers
a) Boiler combustion chamber: Rectangular cross section of size width 6336 mm x length 4160 mm, height 19180 mm formed by steam generation tubes.
b) Steam generation system: Boiler is equipped with one steam drum and distribution headers. Boiler tubes are seam - less spaced center to center 64 mm are connected with header at top and bottom. The bottom headers are supplied with water om steam drum through 28 down comers.
Tubes O.D 133x8mm, mat OLT 45(A53 Gr B)
| Front wall | - 3 headers, 10 down corners, 2headers37tubes1header 24 tubes |
| Back wall | - 3 headers, 8 down comers, 2headers39tubes1header 20 tubes |
| Left side wall | - 3 headers, 5 down comers, each header 30 tubes |
| Right side wall | - 3 headers, 5 down comers, each header 60 tubes |
| Summary | - Front wall 97 tubes, 60 x5 mm, mat OLT 45 (A 53 Gr B) |
| -Back wall 98 tubes, 60 x5 mm, mat OLT 45 (A 53 Gr B) | |
| -Left wall 60 tubes, 60 x5 mm, mat OLT 45 (A 53 Gr B) | |
| -Right wall 60 tubes, 60 x5 mm, mat OLT 45 (A 53 Gr B) |
Top header are 0.D.219 x18 mm mat OLT 45 located outside combustion chamber and connected with steam drum by pipes O.D.133x8 mm, matOLT 45
c) Steam drum:
Steam drum O.D.1600x60 mm, total length 10 320 mm. Steam drum is equipped cyclones at entry of water steam mixture. The upper section is provided with sieve demisters. Normal water level in drum: 200 mm below drum center line.
The 2-external cyclone of O.D.426x36 mm are provided at level of steam drum
and connected with steam drum at both ends.
The cyclones are connected with top headers and with 2 pipes to set drum.
d) The condenser is used as attemperator for superheated team.
A portion of saturated steam om steam drum is condensed by BFW in special condenser, made of 70 coils of O.D.25x3 mm material OLT 45(A53 Gr B).
The steam condensate is introduced to superheated steam of 2 pipes
O.D.273x26, mat OLT45(A53 Gr B), excess condensate is drained steam drum via 2 pipes O.D.133x8 mm provide with seal loops.
e) Steam super heaters:
The boiler is equipped with 3 super heaters
Super heaters 1 located in radiant section
Super heaters II located in convection section
Super heaters III located in convection section
FUEL OIL ANALYSIS CERTIFICATE
| Characteristics | Method | Guaranteed |
| Specific Gravity @ 60/60 oF | ASTM - D 1298 | Max: 0.9700 |
| Density @15 oC | By Table /23/ | Max: 0.9694 |
| Sulphur Wt. Pct. | ASTM-D 1552 | Max: 3.50 |
| Asphaltenes Wt. Pct. | UOP-614 | MAX: 5.10 |
| Flash Point oC | ASTM-D 92 | Min:194 |
| Pour Point oC | ASTM-D 97 | Max: +9 |
| Kin. Viscosity Cst @ 210 oF | ASTM-D 445 | Max: 36.00 |
| Heat of Combustion Cal/g(Net) | ASTM-D 240 | Min: 9500 |
| Ash Content Wt. Pct. | ASTM-D 482 | Max: 0.30 |
| SODIUM PPM | UOP- 391 | MAX: 19 |
| Water by Distillation %VOL | ASTM D-95 | Max:0.30 |
| B.S & W %VOL | ASTM D 96 | Max: 0.20 |
| Vanadium PPM | UOP – 391 | Max:110 |
| Hot Filtration Wt. Pct. | IP -375 | Max: 0.02 |