SEAWATER DESALINATION APPARATUS AND CHEMICAL INJECTION APPARATUS

• Main Authors: MATSUI KOICHI, YAMAGATA EIKEN, MATSUSHIRO TAKESHI, YOKOGAWA KATSUYA, KUROKAWA FUTOSHI, NANBA RYO
• Format: Patent
• Language: English
• Published: 29.03.2012
• Subjects: CHEMISTRY; METALLURGY; PERFORMING OPERATIONS; PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL; SEPARATION; TRANSPORTING; TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE

PROBLEM TO BE SOLVED: To provide a seawater desalination apparatus and a chemical injection apparatus avoiding excessive chemical injection.SOLUTION: The seawater desalination apparatus includes a first reverse osmosis membrane 12 that separates seawater into desalted water and concentrated seawater, and discharges them, a second reverse osmosis membrane 14 that filters the desalted water to remove boron, a first injection device 40 that injects acid into a stage previous to the first reverse osmosis membrane 12, a second injection device 50 that injects alkali to a stage previous to the second reverse osmosis membrane 14, a first sensor S2 that measures pH at an entrance of the first reverse osmosis membrane 12, a second sensor S3 that measures pH at the entrance of the second reverse osmosis membrane 14, and a controller CTR which uses a transfer function from the acid injection to pH at the entrance of the first reverse osmosis membrane 12, a transfer function from the alkaline injection to pH at the entrance of the first reverse osmosis membrane 12, a transfer function from the acid injection to pH at the entrance of the second reverse osmosis membrane 14, and a transfer function from the alkaline injection to pH at the entrance of the second reverse osmosis membrane 14, to control an injection rate of the acid injected from the first injection device 40 and an injection rate of the alkali injected from the second injection device 50.