Boiler alkali washing system and method

The invention discloses a boiler alkali washing system and method. The low-pressure heater water side cleaning loop, the high-pressure heater water side cleaning loop, the low-pressure heater steam side cleaning loop, the low-pressure heater critical drain cleaning loop, the low-pressure heater cleaning loop branch, the drain flash tank cleaning loop, the high-pressure heater steam side and critical drain cleaning loop and the external steam cooler cleaning loop are connected with one another through temporary pipelines; valves and chemicals required by alkali washing of the boiler are arranged on the temporary pipelines, alkali washing is carried out on the boiler, all devices and pipelines in the boiler washing range can be completely covered through loop division, and the temporary pipelines are few and easy to arrange. On the basis of an original equipment arrangement mode, the mode that temporary pipelines are additionally arranged, equipment and pipelines in a formal system are divided into different cl