Abstract:
Objective The aim of this study is to explore the feasibility of phosphorus-free corrosion and scaling inhibitors in circulating water system of natural gas purification plant.
Methods A phosphorus-free corrosion and scaling inhibitor was developed with polyepoxysuccinic acid and zinc salt as the main raw materials.Firstly, the water quality adaptability of the inhibitor was evaluated by means of indoor rotating coupon corrosion test, static scale inhibition test, and microscopic morphology observation, which were followed by field application in the circulating water system of a single natural gas purification plant with a capacity of 150 m3.
Results The indoor evaluation results showed that the corrosion rate of carbon steel could be controlled below 0.02 mm/a and the static scale inhibition efficiency was observed to exceed 90% within the range of calcium hardness of 100-600 mg/L.The field application also confirmed that the CT4-39B has favorable effects since the corrosion rate is far lower than the control value of 0.075 mm/a.At the same time, the total phosphorus contents in circulating water calculated by phosphate radical reduced from 10 mg/L to less than 0.5 mg/L, which has a positive effect of energy conservation and emission reduction.
Conclusions Both the indoor studies and field tests confirm that the phosphorus-free stable operation technology has excellent effects when facing the water with calcium hardness ranging from 100 mg/L to 600 mg/L, and can effectively support the overall environmental protection upgradation of the purification plant while ensuring the stable operation of the circulating water system.
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