Chemical cleaning method for scales on tube of evaporator for producing ammonium sulfate

Abstract

The invention belongs to the field of the cleaning of scales on a tube of an evaporator, and discloses a chemical cleaning method for the scales on the tube of the evaporator for producing ammonium sulfate, which comprises the following steps: dredging and water washing; alkali washing: namely, adding water to carry out circulation, adding 10-40% of alkali, 0.5-1.0% of anionic surfactant and 0.5-3.3% of trisodium orthophosphate according to the amount of the water, and then, heating up to 65-95 DEG C, maintaining the temperature, monitoring the concentration of the alkali once per two hours, replenishing the alkali in time when the concentration of the alkali is less than 5%, so that the final concentration of the alkali is not less than 5%, discharging a cleaning solution outside, and adding the water again for cleaning, thereby completing the alkali washing; pickling: namely, adding the water for carrying out the circulation, adding 0.2-1.0% of pickling corrosion inhibitor and 5-10%of acid according to the amount of the water, reacting at a normal temperature, monitoring the concentration of the acid once per 0.5 hour, replenishing the acid in time when the concentration of theacid is less than 2%, and maintaining the final concentration of the acid to be 0.5-2.0%, thereby completing the pickling; and the water washing and passivating: namely, adding the water to carry outthe circulation, cleaning to be neutral, adding 2-5% of the alkali and 0.5-1.0% of the trisodium orthophosphate, circulating at the normal temperature, and carrying out passivation. By using the chemical cleaning method for the scales on the tube of the evaporator for producing the ammonium sulfate, the scales of sulfates and silicates on the tube of the evaporator can be thoroughly cleaned cleanly, thereby reaching a mirror face state.

Description

technical field [0001] The invention belongs to the field of fouling cleaning of evaporator tubes, in particular to a chemical cleaning method for fouling of evaporator tubes used in the production of ammonium sulfate. Background technique [0002] At present, the comprehensive utilization of domestic iron-containing smelting waste residues is mainly successful in the production of iron oxide pigments and ammonium sulfate by ammonia process. Due to the complex sources of smelting raw materials, the ammonium sulfate mother liquor contains more sulfate impurities such as calcium, magnesium, potassium, and sodium. During the evaporation, concentration, and crystallization of the ammonium sulfate mother liquor, calcium, magnesium and other metal ions are easily supersaturated, forming Fine crystals stick to the wall of the evaporator tubes, gradually forming scales, which gradually increase over time, and eventually block the tubes. Due to the high temperature in the evaporatio...

AI Technical Summary

Problems solved by technology

Due to the high temperature in the evaporation process and the complex composition of impurity ions, the formed scale mainly exists in the form of sulfate and silicate, and is very dense and hard. Use water drills to dredge, professional flexible shaft dredge dredges, high-pressure dredge pumps, etc. method, the labor intensity is high, the cost is high, the operation cycle is long, and it is easy to cause damage to the tubes and damage the mirror surface of the tubes, which makes the tubes more prone to fouling and corrosion by harmful ions

Images