75TPH Gas Boiler is one set gas steam boiler currently used in a petrochemical company in Xinjiang Province. However, due to the improvement of production capacity, the steam amount is insufficient. Based on the principle of saving resource and reducing cost, we decide to make renovation on it. The steam capacity after renovation can reach 90t/h. TG75-3.82/450-Q gas power plant boiler is a medium temperature and pressure, single drum, natural circulation boiler. The design fuel is natural gas and light diesel oil. The burner is in single-layer tangential arrangement.
75TPH Gas Boiler Design Parameter
| S/N | Item | Unit | Designed data |
| 1 | Rated capacity | t/h | 75 |
| 2 | Superheated steam pressure | MPa | 3.82 |
| 3 | Superheated steam temperature | C | 450 |
| 4 | Feed water temperature | C | 104 |
| 5 | Cold air temperature | C | 20 |
| 6 | Hot air temperature | C | 105 |
| 7 | Flue gas temperature | C | 145 |
| 8 | Fuel LHV (natural gas) | KJ/Nm3 | 35290 |
| 9 | Fuel consumption | Nm3/h | 6744 |
| 10 | Design efficiency | % | 91.6 |
| 11 | Economizer structure | – | Bare tube |
| 1) | Tube specification | mm | Φ32*3 |
| 2) | Number of horizontal row | row | 21/24 |
| 3) | Number of longitudinal row | row | 80 |
| 4) | Heating area | m2 | 906.5 |
| 5) | Average velocity of flue gas | m/s | 10.07 |
| 12 | Air preheater structure | – | Heat pipe |
| 1) | Heating area | m2 | 877 |
| 2) | Average velocity of flue gas | m/s | 7.01 |
We made three kind of renovations: renovation of heating surface, expansion of combustion system and expansion of drum internals. With the load increase, it needs more adequate heating area to absorb heat. Therefore, we increase the economizer and air preheater tube bundle to increase the heating area. At 75t/h boiler, economizer has 21/24 horizontal rows and 80 longitudinal rows, with a total heating area of 906.5m2. The total heating area of heat pipe air preheater is 877m2. After renovation to 90t/h, the heating area of economizer reaches 1002m2. The heating area of air preheater reaches 1720m2.
75TPH Gas Boiler Calculation Result After Renovation
| S/N | Item | Unit | Design data |
| 1 | Rated capacity | t/h | 90 |
| 2 | Superheated steam pressure | MPa | 3.82 |
| 3 | Superheated steam temperature | C | 450 |
| 4 | Feed water temperature | C | 104 |
| 5 | Cold air temperature | C | 20 |
| 6 | Hot air temperature | C | 175 |
| 7 | Flue gas temperature | C | 140 |
| 8 | Fuel LHV (natural gas) | KJ/Nm3 | 35290 |
| 9 | Fuel consumption | Nm3/h | 7942 |
| 10 | Design efficiency | % | 92.3 |
| 11 | Economizer structure | – | Bare tube |
| 1) | Tube specification | mm | Φ32*3 |
| 2) | Number of horizontal rows | row | 21/24 |
| 3) | Number of longitudinal rows | row | 88 |
| 4) | Heating area | m2 | 1002 |
| 5) | Average velocity of flue gas | m/s | 11.5 |
| 12 | Air preheater structure | – | Heat pipe |
| 1) | Heating area | m2 | 1720 |
| 2) | Average velocity of flue gas | m/s | 12.5 |
Combustion system renovation mainly includes burner replacement, air inlet system renovation and ID fan system renovation. The gas fired boiler was originally with four natural gas and diesel dual fuel burners, with the maximum output power of 14.58 MW per burner. The total maximum output power of four burners is about 58 MW. Four low nitrogen burners with total output over 63 MW are selected. The maximum output power of each burner is 17.8 MW, and the total output power is 71.2 MW.
