Analisa Pengaruh Injeksi Hydrazine dan Amonia terhadap Parameter pH, Dissolve Oxygen (DO), dan Residual Hydrazine (N2H4) pada Feed Water

Abstract

Research has been carried out analyzing the effect of hydrazine and ammonia injection on pH parameters, dissolved oxygen (DO), and residual hydrazine (N2H4) in feed water at PT. PLN Indonesia Power PLTU Pangkalan Susu PGU. Boiler feed water at PT. PLN Indonesia Power PLTU Pangkalan Susu PGU is sea water which is converted into demineral water by going through several stages with the aim of removing impurities, salt levels, ions and dissolved gases in sea water. Several quality parameters of boiler feed water are pH, dissolved oxygen (DO), and residual hydrazine (N2H4) which have their own quality standards. If these three parameters do not meet the specified quality standards, they can cause corrosion and other problems in pipes and boilers. To achieve pH, dissolved oxygen (DO), and residual hydrazine (N2H4) that comply with quality standards, further treatment must be carried out in the form of chemical injection, namely injection of hydrazine and ammonia with the right dosage and pump stroke limit provisions, namely 0-100% for can increase pH and reduce dissolved gas (DO) levels in boiler feed water. Research on pH analysis begins with the multimeter electrode being rinsed with demineral water, then dipped in the sample (feed water) then the pH displayed on the multimeter is recorded. In the analysis of dissolved oxygen (DO), it begins with making a Sodium Indigo Disulfonate Storage solution, Glucose Storage solution, and Potassium Hydroxide solution, then the three solutions are homogenized with demineral water and Liquid Paraffin into a titration reagent solution, namely Sodium Indigo Disulfonate Glucose solution, then dissolved oxygen (DO) analysis is carried out using the colorimetric method where the sample (feed water) is titrated with the titration reagent and the results obtained will be compared with the standard solution that has been provided to read the DO content levels based on the color of the standard solution. In the analysis of residual hydrazine (N2H4), starting with making a solution of 4-dimethylamine benzaldehyde-citric acid, then analyzing the residual hydrazine (N2H4) by mixing the sample (feed water) and the solution of 4-dimethylamine benzaldehyde-citric acid and then analyzing it using a UV-Visible spectrophotometer at long 455 nm wave and 30 mm cuvvet. From the results of the analysis carried out on feed water samples in units 3 and 4 from the first week to the fourth week, the results obtained for pH levels in unit 3 were 9,44, 9,40, 9,42, and 9,42 as well as in unit 4, namely 9,40, 9,39, 9,38, and 9,37. For dissolved oxygen (DO) levels in unit 3, namely 3,48 ppb, 3,08 ppb, 3,38 ppb, and 2,96 ppb and in unit 4, namely 3,55 ppb, 3,31 ppb, 3,29 ppb, and 2,96 ppb. And for residual hydrazine (N2H4) levels in unit 3, namely 7,17 ppb, 6,76 ppb, 7,31 ppb, and 13,13 ppb and in unit 4, namely 7,43 ppb, 7,98 ppb, 8,93 ppb, and 12,60 ppb. In accordance with the Chemical Operation Manual 1st Edition published by SINOHYDRO CO. LTD. and Base Practice from Pangkalan Susu on Feed Water, it is stated that the data obtained in four weeks from unit 3 and unit 4 meets the quality standards that have been determined, namely with pH parameters of 9,2-9,6, dissolved oxygen (DO) <10 ppb, and residual hydrazine (N2H4) of 10-50 ppb. And it is known that at PT. PLN Indonesia Power PLTU Pangkalan Susu PGU has a pump opening value in accordance with the standard limits on the actual pump stroke for hydrazine injection, namely 50% and ammonia injection, namely 90% with the actual dose for each injection, namely 50,35 ppm and 7,03125 ppm.