4.5　Boiler Drying，Boiling Out，Purging and Tightness Test

4.5.1　The boiler drying shall be in accordance with the following requirements:

1　The boiler drying shall meet the following requirements:

1）The pressure test，boiler wall construction and maintenance of waste heat boiler have been completed；

2）The systems of water & steam，flue gas or temporary flue gas，feed water，blowdown，auxiliary equipment，fire fighting related to boiler drying have been carried out with trial running and meet requirement of design documentation；

3）The thermal measurement instruments related to boiler drying haven been installed，regulated and commissioned to be qualified；

4）The expansion indicators on drum and headers shall be set to zero in cold state；

5）The supply of hot air for boiler drying shall be coordinated operated with the cement production line.

2　According to the boiler drying technical requirement of the wear resistance and refractory material provided by supplier，prepare the boiler drying program and temperature rising curve.The boiler drying shall strictly control the temperature increasing and decreasing speed and the duration of constant temperature，the allowable deviation of temperature wave shall be±20℃；

3　During boiler drying，the expansion of every part shall be checked；

4　It can be considered to be qualified for boiler drying that the remained water content in the unshaped refractory test specimen applied in boiler drying is smaller or equal to 2.5%；

5　After the boiler drying is finished，and after the boiler internal temperature is cooled to ambient temperature，carry out appearance checking to the castables，if damages or serious defects are found out，carry out repairing and drying.

4.5.2　Boiling out shall be in accordance with the following requirements:

1　The boiling out shall be carried out after the boiler drying is finished，the supply of hot air for boiling out shall be coordinated operated with the cement production line；

2　The boiling out chemicals and dosing quantity shall be adopted according to the regulation of boiler technical documentation，for no regulation，the dosing quantity for boiling out can be chosen as per table 4.5.2 according to the tarnishing degree inside the boiler；

3　Trisodium phosphate and sodium hydroxide（or sodium carbonate）can be applied at the same time；

4　The expanded joint boiler should not use boiler with sodium hydroxide；

5　The duration for boiling out shall be decided by the tarnishing degree inside the boiler，and it should be 2d-3d.The temperature and pressure increasing speed and the pressure keeping duration shall be subject to the boiler instruction manual and the operation regulation；

6　In the later period of boiling out，carry out periodically sampling and analyzing to the boiler water from drum and bottom header，when the PO4 3-concentration in the boiler water is stable，stop boiling out；

7　After the boiling out is completed，the cleaned metal surface inside the boiler shall be free of grease dirt and rust，and the integrated passivation coating shall be formed.

4.5.3　The feed water pipe，desuperheating water pipe，superheater and the pipelines in the boiler scope shall be flushed and steam purged before being put into operation.

4.5.4　The flushing and steam purging shall comply with the regulations of Article 7.5.2 and 7.5.3 of this code.

4.5.5　The steam tightness test shall meet the following requirements:

1　The boiler pressure shall be increased to rated working pressure；

2　There shall be no leakage at boiler auxiliaries，steam water valves，welding joint，manholes，handholes，and flanges；

3　There shall be no abnormal in the expansion of drum，header，and heating surface and steam water pipes and the stress，displacement，and flexibility of the supports，hangers，and spring.

4.5.6　After the boiler drying，boiling out，purging and tightness test are completed，submit the following documentation:

1　Qualified certificate for tightness test；

2　Qualified certificate for boiler drying；

3　Qualified certificate for boiling out；

4　Qualified certificate for flushing and purging.