Within one week after the boiler has been shut down, the water supply pressure method can be used for maintenance.
The methods are as follows:
1. After the boiler has been damped down, the pressure shall be stepped down and continuous blowdown shall be kept continuous.
2. When the steam drum pressure decreases to 5.0 Mpa, contact the chemical water treatment person to assay the water quality. If the water quality is unqualified, the water shall be changed. After the boiler water is qualified, close the primary and the secondary and the main water valves of the regularly blowdown expanders to disconnect the continuous blowdown expanders.
3. Before the steam drum pressure drops to 0.5 Mpa, the boiler water must be qualified.
4. When the steam drum pressure is more than 0.5 Mpa and the superheater tube wall temperature is below 200 ℃, the boiler can be fed with water for boosting.
5. The drum pressure generally remains at 0.5 to 3.0 Mpa, and shall not be less than 0.5 Mpa at minimum.
6. During the process of maintenance, when the steam drum pressure drops below 0.5 Mpa (pressure is zero), through the feed water bypass to feed water to the boiler. while the water is fed, at the same time open the regularly blowdown expander and open each draining valve of the boiler for changing water. The water-changing flow is controlled at 15-25 t/H.
7. After the pressure is charged, make a record, and inform the chemical water persons to assay the dissolved oxygen of boiler water. If the boiler has been shut down for more than one week, or the pressure parts are repaired, the waste heat drying method can be used for maintenance, the methods are as follows:
(1) After the boiler has been shutdown, close each air and smoke baffle or boiler door and tightly shut the air and smoke systems.
(2) when the steam drum pressure drops to 0.8- 1.0 Mpa, open the boiler water-draining valve and water-discharging valve to exhaust the water as soon as possible.
(3) When the steam drum pressure drops to 0.1 0.2 Mpa, fully open the air valve of the boiler body.
(4) when the pot in the inland waters has been basically put, start the induced draft fan, returns fan and a fan, maintain bed material fluidization bed and use the waste heat of bed material to dry the boiler.
(5) After the drying for boiler is stopped, close the boiler. When the outlet smoke temperature of economizer drops to 120 degrees, close the air bleeding valve and water draining valve of the boiler body.
