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AssigneesKurita Water Industries Ltd., Japan Synthetic Rubber Co., Ltd.
InventorsKatsuhiko Momozaki, Masako Kusunoki, Fumio Kawamura, Hisao Ono, Katsumi Itoh, Yoshihiro Shimizu, Yuuichi Ono
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A method of removing scale in a cooling water system in which scale is formed comprises adding 0.01 weight % or more based on the total amount of water contained in the cooling water system of a copolymer containing vinyl monomer units having a carboxyl group or salt thereof and vinyl monomer units having a sulfo group or salt thereof in amounts to make the mol ratio of the carboxyl group to the sulfo group in the range of 30:70 to 95:5 and having weight average molecular weight calibrated with polystyrene in the range of 1,000 to 100,000 to the cooling water system while operating the cooling water system and the cleaved or dissolved scale is discharged out of the cooling water system by blowing. The scale removing agent for a cooling water system has excellent ability to remove scale, does not require much man power nor causes loss of productivity because the scale can be cleaned and removed without stopping the circulation of the cooling water while the ordinary operation of the system is maintained and has no possibility of such danger to operator as found in conventional acid cleaning processes because the agent is used in less acidic condition. Furthermore, the polymer itself has the characteristic that is not easily formed. The finishing point of the scale removal can be found easily by measuring the pH value on the spot of the operation without stopping the operation of the cooling water system.
A method of removing calcium compound-containing scale including calcium carbonate in a cooling water system in which said scale is formed which comprises adding to the cooling water in the cooling water system, while the system is operating, 0.01 weight % or more based on the total amount of water contained in the cooling water system of a scale dissolving agent which comprises a copolymer containing vinyl monomer units having a carboxy group or salt thereof and vinyl monomer units having an isoprene sulfonic acid group or salt thereof in amounts such that the mol ratio of the carboxyl group to the sulfonic acid group is in the range of 30:70 to 95:5, said copolymer having a weight average molecular weight calibrated with polystyrene sulfonic acid sodium salt of 1,000 to 100,000, thereby producing a cleaved or dissolved scale solution, and, thereafter discharging said cleaved or dissolved scale solution from the cooling water system.
Dependencies are inferred from the claim text.