Guide: 1. Why should the boiler be discharged regularly at the beginning of ignition? Answer: At this time, regular sewage discharge is carried out, and part of the water at the bottom of the circulation loop is discharged.
1. Why should the boiler be discharged regularly at the beginning of ignition?
Answer: At this time, regular sewage discharge is carried out, and part of the water at the bottom of the circulation loop is discharged, which not only allows impurities to be discharged and guarantees the quality of the pot water, but also strengthens the heat exchange of the weakly heated part of the circulation loop, preventing local water circulation from stagnating and causing The metal heating surface of each component of the water circulation system expands evenly, reducing the temperature difference between the upper and lower walls of the steam drum.
2.Why do you still need to control the boost speed at the later stage of the boiler startup?
Answer: Although the temperature difference between the upper and lower walls of the steam drum is gradually decreasing at this time, the temperature difference between the inner and outer walls is still large due to the thick metal of the drum wall, and it may even increase. In addition, the steam drum is subjected to stress close to the working pressure in the later stage of start-up, so the pressure rise rate in the later stage must be controlled to prevent the stress on the drum wall from increasing.
3. How to control the water level of the drum during the boiler startup?
Answer: During the boiler start-up process, the water level of the drum should be controlled and adjusted according to the changes in the boiler working conditions. In the initial stage of ignition, the pot water is gradually heated, vaporized, and expanded to raise the water level. At this time, it is not easy to use the accident drain gate to lower the water level, but should be discharged from the regular drain gate to improve the quality of the pot water and promote the water circulation; with the steam temperature When the steam pressure rises and the exhaust steam volume increases, the water supply should be supplemented in time according to the trend of the change of the drum water level; when flushing the boiler pipe or checking the safety door, it is often caused by a sudden increase in steam flow and a rapid drop in steam pressure. Therefore, before the above operations, the water level should be kept low, and then the water supply should be increased according to the changed steam flow to prevent the safety door from returning to the seat and other reasons to cause the water level to be too low; switch in time according to the boiler load The water supply pipeline is running, and the water supply is automatically put into operation according to the specified conditions.
4. What should I do if the steam temperature does not increase during the boiler startup?
Answer: During the start-up process of the unit, it is often encountered that the steam pressure has reached the requirements, but the steam temperature is too different, especially before the steam turbine is flushed or combined.
The following measures should be taken: appropriately increase the amount of coal fed to increase the heat load in the furnace; adjust the ratio of the secondary air to increase the secondary air volume; increase the air volume, air pressure, and increase the flue gas flow rate; fully open drainage and air exhaust and The main steam pipe isolates all drains in front of the door.
5. Why should the unit be operated at a constant pressure within a certain range during operation?
Answer: The unit adopts constant pressure operation, which can improve the cycle thermal efficiency of the unit. Because the decrease in steam pressure will reduce the enthalpy drop of steam in the steam turbine, which will increase the steam consumption and coal consumption. Some data show that when the steam pressure is 5% lower than the rated value, the steam consumption of the steam turbine increases by 1%. In addition, constant pressure operation increases the flexibility of scheduling to a certain extent, which can meet the needs of system frequency modulation.