What are the regulations regarding the timing and temperature of water filling before starting the boiler? Why?

The water inflow rate before starting the boiler should not be too fast; generally, it should take no less than 4 hours in winter, and 2–3 hours in other seasons. The inflow rate must be particularly slow at the beginning. The feedwater temperature of cold boilers is generally not higher than 100°C, so that the difference between the feedwater temperature entering the drum and the drum wall temperature does not exceed 40°C. For a boiler that has not yet cooled down completely, the inlet water temperature can be set based on the temperature of the drum wall; generally, the difference should be kept within 40°C. Otherwise, the inlet water flow rate should be reduced. The reason is: (1) Since the wall of the steam drum is thick, its expansion is slow, whereas the walls of the tubes connected to the steam drum wall are thin, resulting in faster expansion. If the inlet water temperature is too high or the flow rate is too fast, it will lead to uneven expansion, causing cracks in the welds and resulting in equipment damage. (2) When feedwater enters the drum, it first comes into contact with the lower half of the drum’s wall. If the temperature difference between the feedwater and the drum wall is large, and the flow rate of the feedwater is high, a significant difference in expansion will occur between the upper and lower walls as well as between the inner and outer walls of the drum. This creates substantial additional stress on the drum, leading to deformation; in severe cases, cracks may form.

1. After the inspections prior to boiler startup are completed, qualified water can be supplied to the boiler via the economizer; its temperature should generally not exceed 100°C. Water addition should be carried out slowly; the difference between the temperature of the feed water entering the drum and the temperature of the drum’s metal should not exceed 40°C. Water addition is not permitted when this temperature difference exceeds 40°C. The total time required for the boiler to go from a water-free state to a water level of 100 millimeters below that indicated by the drum level gauge shall be no less than 2–3 hours in summer, and no less than 4 hours in winter. 2. Before and after water intake, a dedicated person should be responsible for recording the expansion indicator and checking whether its indication is normal. 3. During the water inlet process, check whether there are any leaks in the pipes, valves, etc. If any leakage is detected, the water supply should be stopped; once the issue is resolved, the water supply can be resumed. The water inflow rate should be adjusted slowly and evenly; the valves must not be opened or closed abruptly to prevent water shock. 4. Prevent water from the drum from entering the superheater. Once the boiler is filled with water, water is introduced for backwashing through the superheater; once water sprays out rapidly from each air release valve, they are closed one by one. 5. The pressure increase of the boiler should be controlled by valves with a diameter of DN50 or less to regulate the water inflow rate; the pressure increase rate shall not exceed 0.3 MPa per minute. Once the pressure reaches the operating level, the water inlet valve should be closed for 3 minutes to record the pressure drop, after which the valve should be slightly opened to maintain the operating pressure, allowing for a thorough inspection. This post was last edited by jfhou126 on 2009-2-7 14:19.]

The regulations require that the water supplied to boilers must be deoxygenated, and its temperature must not exceed 100°C; the treatment time should be no less than 2 hours in summer and no less than 4 hours in winter, with differences also existing between the north and the south. For areas above the upper and lower walls of the boiler’s drum, temperature sensors are installed; it is necessary to keep the temperature difference between these upper and lower walls within 50°C, as otherwise it can easily lead to deformation of the drum.

The opinions on floors 2 and 3 are both good; I agree with those views