Water quality issues in catalytic medium-pressure steam drums

What is the purpose of adding trisodium phosphate to the medium-pressure steam drum? What are the hazards if the phosphate level in the drum water remains below the required standard for an extended period? (The phosphate level remains low for an extended period.) The purpose of adding trisodium phosphate is to react with the calcium and magnesium ions present in the water of drum boilers to form sludge that does not adhere to the heating surfaces; this sludge can then be removed through regular drainage, thereby controlling the hardness of the boiler water. This helps prevent scaling on the heating surfaces from affecting the heat transfer efficiency, as well as avoiding tube bursts and under-scale corrosion. Additionally, trisodium phosphate serves to prevent intergranular corrosion (I am not a specialist in materials science; this question should be answered by a materials expert, so I will not go into further detail on it). Deoxygenated water still has a certain level of hardness; as the water in the steam drum evaporates, calcium and magnesium ions become more concentrated, increasing the hardness of the water and thus the likelihood of scale formation. During normal operation, a certain margin should be maintained for phosphate, and it can be controlled in accordance with your company’s specifications. The bottom level doesn’t need to be a concern as long as it remains within the specified range; after all, the establishment of these thresholds is based on experience and relevant criteria. Can the medium-pressure drum bank be shut down? (The alkalinity of the drum water has always been quite high.) First of all, it should be noted that “lianpai” refers to continuous drainage, that is, the discharge of wastewater on a continuous basis. It cannot be shut down for a long time; it can be shut down for a short period. The function of continuous drainage is to remove the scum on the surface of the steam-water interface and to control the salt content in the boiler water, thereby ensuring the quality of the steam. If it is necessary to shut down for a short time in order to calibrate the displacement, that is no problem. What is the purpose of regular drainage from the medium-pressure steam drum, and based on what parameters is it carried out? The function of regular drainage in the medium-pressure drum is to remove the sludge at the bottom of the drum, as well as various impurities such as fine sediment contained in the desalinated water (the quality of desalinated water in refineries is currently very good, so fine sediment can be practically ignored). For scheduled drainage, there are no analytical test results available for reference; however, when the quality of the boiler water is substandard at present, regular drainage can be used to accelerate the replacement of the boiler water. Thank you to all the teachers for their guidance!