# US 2010/0163399 A1 · Water Treatment Process for Steam Plant > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2010/0163399 A1 - Document ID: US20100163399A1 - Status: Published application - Kind: A1 - Application number: 12/224,044 - Filed: 2007-08-28 - Published: 2010-07-01 - Earliest claimed: 2006-08-31 - Assignees: Mitsubishi Heavy Industries, Ltd. - Inventors: Nobuo Ishihara; Sumio Yamauchi; Kazutoyo Murata; Masato Kanedome; Yasuhiko Shoda; Katsuhiko Yamakami - Web page: https://patentgrep.com/patent/US20100163399A1 ## CPC - C02F 1/66: by neutralisation; pH adjustment (for degassing C02F1/20; using ion-exchange C02F1/42; for flocculation or precipitation of suspended impurities C02F1/52; for removing dissolved compounds C02F1/58) - C02F 1/008: {Control or steering systems not provided for elsewhere in subclass C02F} - F22B 37/48: Devices or arrangements for removing water, minerals or sludge from boilers (cleaning water tubes, furnace tubes or the like of boilers F28G) {; Arrangement of cleaning apparatus in boilers; Combinations thereof with boilers} - F22B 37/56: Boiler cleaning control devices, e.g. for ascertaining proper duration of boiler blow-down - C02F 5/00: Softening water; Preventing scale; Adding scale preventatives or scale removers to water, e.g. adding sequestering agents (softening using ion-exchange C02F1/42) - C02F 2101/16: Nitrogen compounds, e.g. ammonia - C02F 2103/023: {Water in cooling circuits} - C02F 2209/06: pH - C02F 2209/44: Time - C02F 2303/08: Corrosion inhibition - C02F: TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE (separation in general B01D; special arrangements on waterborne vessels of installations for treating water, waste water or sewage, e.g. for producing fresh water, B63J; adding materials to water to prevent corrosion C23F; treating radioactively-contaminated liquids G21F9/04; regeneration of reactants for recirculation into processes, see the relevant places for the processes) - F22B: METHODS OF STEAM GENERATION; STEAM BOILERS ## Abstract In a steam plant, scale adhesion to the inside of a specific device is prevented, while reducing the amount of an agent such as hydrazine to the lowest possible level. A temporary change in the chemical environment or an approximately periodic variation in the chemical environment is brought about in a channel (21) inside the prescribed device, during operation of the steam plant. ## Claims ### Claim 1 A water treatment process for a steam plant including a steam generator for generating steam by heat from a heat source, a steam turbine driven by the steam from the steam generator, a condenser for condensing the steam exhausted from the steam turbine, a water feeder for feeding the water condensed in the condenser to the steam generator, and a circulation channel for sequentially connecting the steam generator, the steam turbine, the condenser, and the water feeder, wherein a change in the chemical environment is temporarily brought about in the channel inside a prescribed device disposed in the channel, during operation of the steam plant. ### Claim 2 (depends on 1) The water treatment process according to claim 1, wherein the change in the chemical environment is an increase in pH of water in the channel inside the prescribed device. ### Claim 3 (depends on 2) The water treatment process according to claim 2, wherein the range of the increase in pH is 0.1 or more and 1.0 or less. ### Claim 4 (depends on 2) The water treatment process according to claim 2, wherein the increase in pH is achieved by temporarily injecting a volatile base into the channel near the prescribed device at the upstream side thereof or inside the prescribed device. ### Claim 5 (depends on 2) The water treatment process according to claim 2, wherein the increase in pH is achieved by temporarily increasing the injected amount of a volatile base under the condition of constant injection of the volatile base into the channel near the prescribed device at the upstream side thereof or inside the prescribed device. ### Claim 6 (depends on 4) The water treatment process according to claim 4, wherein the steam plant has at least one branched channel that is branched from the channel at the upstream side of the prescribed device and becomes confluent with the channel at the downstream side of the device, and the same type of device as the prescribed device is disposed in parallel in the branched channel; and under the condition of injection of a volatile base into the branched channel near the same type of device at the upstream side thereof or inside the same type of device, the amount of the volatile base supplied to the same type of device is reduced, when the volatile base is supplied to the prescribed device, by approximately the same amount as that of the volatile base supplied to the prescribed device. ### Claim 7 (depends on 5) The water treatment process according to claim 5, wherein the steam plant has at least one branched channel that is branched from the channel at the upstream side of the prescribed device and becomes confluent with the channel at the downstream side of the device, and the same type of device as the prescribed device is disposed in parallel in the branched channel; and under the condition of injection of a volatile base into the branched channel near the same type of device at the upstream side thereof or inside the same type of device, the amount of the volatile base supplied to the same type of device is reduced, when the amount supplied to the prescribed device is increased, by approximately the same amount as the increased amount of the volatile base supplied to the prescribed device. ### Claim 8 A water treatment process for a steam plant including a steam generator for generating steam by heat from a heat source, a steam turbine driven by the steam from the steam generator, a condenser for condensing the steam exhausted from the steam turbine, a water feeder for feeding the water condensed in the condenser to the steam generator, and a circulation channel for sequentially connecting the steam generator, the steam turbine, the condenser, and the water feeder, wherein a change in the chemical environment is brought about, approximately periodically, in the channel inside a prescribed device disposed in the channel, during operation of the steam plant. ### Claim 9 (depends on 8) The water treatment process according to claim 8, wherein the change in the chemical environment is a fluctuation in pH of water in the channel inside the prescribed device. ### Claim 10 (depends on 9) The water treatment process according to claim 9, wherein the range of the fluctuation in pH is within ±0.05 to ±0.3 of a predetermined standard value. ### Claim 11 (depends on 9) The water treatment process according to claim 9, wherein the cycle of the fluctuation in pH is within the range of from 5 minutes to 1 hour. ### Claim 12 (depends on 9) The water treatment process according to claim 9, wherein the fluctuation in pH is achieved by injecting a volatile base into the channel near the prescribed device at the upstream side thereof or inside the prescribed device, while varying the injected amount approximately periodically. ### Claim 13 (depends on 12) The water treatment process according to claim 12, wherein the steam plant has at least one branched channel that is branched from the channel at the upstream side of the prescribed device and becomes confluent with the channel at the downstream side of the device, and the same type of device as the prescribed device is disposed in parallel in the branched channel; and a volatile base is injected into the branched channel near the same type of device at the upstream side thereof or inside the same type of device while causing an approximately periodic fluctuation in the injected amount such that the fluctuation has a phase approximately opposite to that of the fluctuation in the amount supplied to the prescribed device. ### Claim 14 (depends on 1) The water treatment process according to claim 1, wherein the prescribed device is the water feeder. ### Claim 15 A water treatment process for a steam plant including a steam generator for generating steam by heat from a heat source, a steam turbine driven by the steam from the steam generator, a condenser for condensing the steam exhausted from the steam turbine, a water feeder for feeding the water condensed in the condenser to the steam generator, and a circulation channel for sequentially connecting the steam generator, the steam turbine, the condenser, and the water feeder, wherein the water feeder is a centrifugal pump including a volute chamber and an approximately disk-shaped impeller rotatably arranged in the volute chamber and transferring water introduced to the center of the impeller from the outside of the volute chamber to the outside of the volute chamber from the circumference of the impeller by a centrifugal force caused by the rotation of the impeller; and a change in the chemical environment is brought about in a gap between the impeller surface opposite to the surface at the water-introducing side and the inner surface of the volute chamber, during operation of the centrifugal pump. ### Claim 16 (depends on 15) The water treatment process according to claim 15, wherein the change in the chemical environment is an increase in pH of water in the gap. ### Claim 17 (depends on 16) The water treatment process according to claim 16, wherein the increase in pH makes the pH of water in the gap 7 or more and 12 or less. ### Claim 18 (depends on 16) The water treatment process according to claim 16, wherein the increase in pH is achieved by injecting a volatile base into the gap. ### Claim 19 (depends on 15) The water treatment process according to claim 15, wherein the change in the chemical environment is a decrease in pH of water in the gap. ### Claim 20 (depends on 19) The water treatment process according to claim 19, wherein the decrease in pH makes the pH of water in the gap 5 or more and 9 or less. ### Claim 21 (depends on 19) The water treatment process according to claim 19, wherein the decrease in pH is achieved by injecting an acid into the gap.